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Article X. — Any member or holder of second class stock, detected in mutilating the newspapers, pamphlets or books belonging to the Insti- tute shall be deprived of his right of membership, and the name of the offender shall be made public. Digitized by the Internet Archive in 2015 https://archive.org/details/practicaltreatisOOgill_0 Professional Papers of the Corps of Ei^gin-eers, U.S.A. No. 9. PRACTICAL TREAT! LIMES HYDEAULIC CEMENTS, MORTARS BY Q. A. GILLMOEE, A.M., Lieutenant-Colonel U. S. Corps of Engineers, Brevet Major-Geh. U. S. Army. EIGHTH EDITION. D. VAN NOSTRAND, PUBLISHER 33 MuBRAT Street and 27 Warren Street. 1886. TA Entered according to Act of Congress, in the year 1872, BY D. VAN NOSTRAND, In the Office of the Librarian of Congress at Washington. isroTE. The experiments and researches, wLicli fumisli tlie groundwork for all tlie original matter contained in tlie following work, were conducted under the authority of the Engineer Bureau of the War Department, and were completed in the summer of 1861. The manu- script was nearly ready for the publisher at the same time. Since then, active professional duties have rendered it impossible for me to devote even a brief personal superintendence to the publication of the work. I am, therefore, not insensible to the many disadvantages under which its hasty publication is now undertaken. It doubtless contains many defects. For the method of analysis given in Chapter V., I am indebted to Captain E. C. Boynton, U. S. Army, late Professor of Chemistry in the University of Mis- sissippi. Q. A. GILLMOEE, Brig.' General. Hea J-QuARTEHs, Dept. of the South, ]^ Poet Royal, S. 0., June 15, 1863. J PREFACE TO THE FOUETH EDITIOE". In preparing the fourth edition this work for the press, it has been thought proper to give, in an Appendix, brief descrip- tions of the two methods, one by hand and the other by machinery, followed in making the several qualities of Portland cement concrete, applied, for various purposes, in the construction of the fortifications on Staten Island, 'New York Harbor, of which the author has charge as superintending Engineer. The special information given has been derived from the ex- perience of two working seasons — 1870 and 1871 — and all the data with regard to the cost and proportions of the constituent ingredients — the cement, lime, sand, gravel, and broken stone — as w^ell as the cost of the finished concrete in position, may be relied upon as correct, within reasonable limits. The Appendix also contains a description of the new concrete mixer, in use on the works, a drawing of which serves as a frontispiece to this edition. A new and carefully prepared index has been inserted in place of the old one, and the work has been, in other respects, essentially revised and improved. Q. A. GILLMOEE, Bvt. Mc0 or- General, U.S.A.. New York, January, 1872. STIj"OPSIS OF CONTElNrTS. CHAPTER I. Geographical and geological localities of hydraulic cement in the United States. — Analysis of various specimens from Virginia, New Jersey, New York, Massachusetts, and Mississippi. Pages 15-27. CHAPTER II. Precautions employed in procuring cements for testing. — Appliances for testing the transverse strength, hardness, and adhesive properties of mortars. Pages 28-35. CHAPTER III. Rosendale cement. — Location and capacity of the manufactories. — Cement works at Shepherdstown, Va. — The Round Top cement works near Hancock, Md. — The Cumberland cement works. — The James River cement works. — The works at Utica, La Salle Co., 111. — Sandusky, Ohio. Louisville, Ky. — Kensington, Conn., and Akron, Manlius, and Chitte- nango, N. Y. — The Portland and the Roman cements. Pages 36-66. CHAPTER IV. Common lime, and lime mortars. — Hydraulic limes and cements. — ^Natural pozzuolana and trass. — Ar^nes. — Artificial hydraulic cement and lime. The use of alkaline silicates. — Silicatization. — Endurance of hydraulic mortars and betons in sea- water. — Opinions thereon of Marshal Vaillant, Inspector-General Noel, MM. Ravier, Feburier, Vicat, and other French authorities. Pages 67-109. CHAPTER V. Diversified character of limestone beds. — Method of testing the stone ex- perimentally. — Qualitative and quantitative analysis. — Analyses of vari- ous cements, limes, trass and pozzuolana. — Kilns for burning cement and method of burning. — EflTect of varying the intensity and duration of the heat. — Preservation and restoration of cements. Pages 110-173. 14 CONTENTS. CHAPTER VI. Mortar defined. — Aggregates. — The use of sand. — Method of slaking hme. — Action of hydrates in air and under water. — Mill-made mortar. — Hand- made mortar. — Composition and cost of mortar used in Forts Rich- mond, Tompkins, and Warren. — Pointing mortar. — Interior and exterior plastering. Pages 174-222. CHAPTER VII. Concrete or beton. — How made and used. — How laid under water. — Com- position and cost of concrete used at Forts Richmond, Tompkins, and Warren. — Use of concrete at Toulon, Algiers, Marseilles, Cherbourg, Dover, Alderney, etc. — Tables giving strength of various kinds of con Crete. Pages 223-258. CHAPTER VIII. Neat cement made semi-fluid with excess of water. — Superiority of Portland over the natural quick cements, when so employed.— Comparison of Portland and Roman cements. — xldhesive properties of American ce- ments. — Transverse strength of various mortars. Pages 259-293. CHAPTER IX. Mural efflorescences.— Induration of mortars of fat lime. — Theory of hydrau- lic induration. — The hardening by artificial means of stone, brick, mortar, etc. Pages 293-316. APPENDIX. Description and cost of several kinds and qualities of concrete used in the construction of the fortifications on Staten Island, New York Harbor, during the years 1870 and 1871.— Description of new concrete mixer. Page, 317-326. A PEACTICAL TEEATISE ON LIMES, HYDRAULIC CEMENTS, AOT) MORTARS. CHAPTEE I. INTRODUCTION. 1. Nature has supplied us with limestones in great profusion and endless variety. Those suitable for common lime are so widelj diffused, and have such an extensive development in this country, that no attempt will be made, — nor An abimdance would it be consistent with the character and stone?SThe™^' scope of a work devoted to the consideration of United states. " mortars," even under the most comprehensive signification of that term, — to particularize the numerous localities where its manufacture is extensively and successfully carried on. 2. Impure or compound limestones, possessing the property of hardening under water after being calcined, and reduced by slaking, or by the aid of mechanical means, to Compound lime- the state of paste, although more rare than the g^^^^emurir' common limestones, nevertheless occur in numer- caiities. ous localities in the United States ; and from the great and peculiar value, as a cementing material for submarine and sub- terranean constructions, of the mortars derived xVom them, they merit a more detailed notice. 3., The most extensive beds have thus far been discovered in the valleys of the great Appalachian chain of mountains, as they traverse the States of New York, New Jersey, Pennsyl- 16 PRACTICAL TREATISE ON LIMES, vania, Virginia, Tennessee, and the northern portions of Georgia and Alabama. They are, however, by no means con- fined to those States, but have been found to some extent in the northern terminus of this range, as it passes through Massa- chusetts and Vermont, at the forks of the Kennebeck, and other places m Maine, and in the northern counties of Missis- sippi. In a westerly direction, and beyond the lateral limits of the great Appalachian Yalley, in the western regions of New York, Pennsylvania, Yirginia, and Tennessee, as well as in Kentucky, Ohio, Indiana, and Illinois, the same kind of stone exists in numerous and extensive deposits. 4. There is no geological formation to which the term " hydraulic lime" or " hydraulic cement" can with propriety be exclusively applied, inasmuch as we find none which, over extensive areas, and in localities widely separated, is capa- The character of furnishing uniformly either the one or the stone suitable for other of these products. All sedimentary rocks cement^Ts^very^ are noted for the marked variations in their variable. lithological characters, within very limited areas, owing to the existence of local causes, affecting the conditions of their deposition. This is specially the case with those impure limestones of which the composition is such as to render them, as an exceptional class, suitable for hydraulic mortars, — a circumstance due to their peculiar geological position. They The usual ingre- usually contain, in widely varying proportions, dients the same, carbonate of lime, carbonate of magnesia, silica, alumina, oxide of iron, and a small amount of alkali, and are generally comprised in the beds of passage between deposits that are purely silicious or argillaceous, and those that are purely calcareous or dolomitic. They therefore, in the general case, derive their character from the contiguous underlying and overlying rocks, and approximate more intimately to the one or to the other, in proportion as the causes operating during the period of formation unduly favored its deposition. If a limestone, for example, was formed upon a sandstoTie, by the HYDRAULIC CEMENTS, AND MORTARS. 17 gradual and progressive subsidence of calcareous particles, commenced and carried on before the deposition of the silicious matter was completed, the intermediate beds created by this mingling process would be a silicious limestone, with propor tions depending on the manner of deposition, and the nature and extent of the causes by which it was produced and regu- lated. It could be uniform only while those causes remained fixed and persistent. The intervention of local disturbances of whatever extent or character, tending to hasten, retard, or ran der intermittent the deposition of either of the principal ingre- dients, would of course modify their proportions, and materi- ally afi(ect the character and properties of the compound rock. 5. Observations show that the argillaceous and argillo- magnesian limestones of the United States are characterized, in an eminent degree, by variations in composition, due to such causes ; and that these variations frequently, and, in fact, generally, occur within very short distances. 6. At the base of the Lower Silurian System we find the Potsdam Sandstone, the lowest known fossiliferous rock, and interesting in this connection from the fact that it, in a mea- sure, imparts hydraulic character (by supplying the silica) to the calcareous deposits restine^ upon it. In 'New ^ , . , ^ . r, .The Potsdam York, this sandstone is a nrm quartzose rock; Sandstone under- while, in some portions of the West, the cohesion caicar^ousTed^s between the particles is so slight that it can be possessing hy- ^ draulicity. easily crumbled in the hand. It occurs of various shades of yellow, red, and gray, approaching to white, and is most intimately related to the calcareous beds which underlie it. In many places, it gradually passes into easily recognized compact magnesian limestone, sometimes alternating with the calcareous beds above. This sandstone corresponds to Formation I. of Prof. Rogers' classification of the rocks of Pennsylvania and Virginia. 7. The next rock in the ascending series belongs to Forma- tion II., known as the calcareous " sandrock." or, more com- 18 PEACTICAL TEEATISE ON LIMTSfc monly, calciferous group," which, in both composition and age, must be regarded as intermediate between tne Potsdam " Calciferous Sandstone and the purer limestones above, viz. . Group." the Chazy, Bird's Eye, Black Eiver, and Tren- ton Groups. It is the oldest known fossiliferous limestone, is ealcareo-silicious in character, as its name indicates, and is the lowest member of the series capable of yielding either hydraulic lime or cement. In many localities, it exhibits the water-lined lamin?e of deposition in a marked and conspicuous degree. Three distinct masses of this rock are usually observed wherever it presents a fully developed outcrop. 8. The lowest beds are highly silicious, and in the eastern portions of the United States, where it has been most examined, quite compact, being undoubtedly produced by a partial con- tinuation of the Potsdam Sandstone deposit, carried on simul- taneously with that of the calcareous matter, the composition of the rock showing a notable excess of the Its lower^ middle, ^ and upper subdi- former. ^^^^*^°^* 9. The middle beds appear to comprise a variable mixture of yellowish sand and carbonate of lime, pre- senting, when newly broken, a gritty and sparklm^: fracture. They are those to which the term " Calciferous Sandrock" is usually applied. 10. The uj)per or superior mass more nearly approximates m character to the limestones above, and is very frequently intermixed with argillaceous matter. The appearance of a recent fracture is granular and sparkling, and often exhibits a sub-crystalline structure. This rock, however, assumes at dif- ferent points a remarkable diversity in both its physical appear- ance and its chemical composition. It is synonymous with the Barnegat, Newburgh, Warwick, Oolitic, and Slaty lime- stones, the Transition Sandrock of Eaton and the Fucoidal Layer?., and with the Magnesian limestones of the West. Jl. The purer calcareous beds which rest immediately upoD HYDRAULIC CEMENTS, AND MORTAES. 19 the " Calciferous Group" also belong to Formation II. of Prof. Rogers' classification, and are known at different points as the Black River limestone, the base of the Trenton limestone, the Mohawk, Bird's Eye, Bald Mountain, Blue, and Chazj lime- stones, the Transition Limerock of Eaton, Blue limestone of Kittatinny Yalley, Pennsylvania ; and, in the West, as the Fos- siliferous limestones, and the Blue limestones and marls. These beds are frequently connected very intimately .11 1 .1 11 1 •' The calcareous With the members oi the group below, and, m beds resting on numerous localities, possess in suitable propor- Group''^suUaU^^ tions, and in proper combination, those ingre- for hydraulic dients which confer the hydraulic property. 12. It is unnecessary for our purpose, in a work like this, — in which rocks of a particular class, and bearing a close resem- blance to each other in their general features, are discussed specially with reference to their adaptation to a particular use, — that all the technicalities of a strictly geological classification should be kept constantly in view. It will be Between the sufl&cient to intimate, in brief terms, that among ^tone and^^e^' those deposits lying above the Potsdam Sand- utica Slate, many , , , * , . ^, . argillo-magnesian stone, and below the Utica blate or its corre- deposits possess spending member, all of which are comprised in l^y^irauhc energy. Prof. Rogers' Formation II., are found in numerous places extensive beds of argillo-magnesian limestone, possessing the hydraulic energy in a high degree ; and that these beds occur sometimes higher, and sometimes lower in the series, as deter- mined by causes operating during the period of their forma- tion. They have an extensive development in the United States, particularly along the great Appalachian range. 13. In the State of JSTew York, they occupy a narrow belt along the eastern portion of the State, extending from the Ver- mont line in a southerly direction through Williamstown, Leba- non Springs, Pine Plains, Barnegat, and ISTew- Geographical bur2:h : thence stretchino: in generally parallel l<^?^i\*^es of the ^ . principal outcrops strips in a southwesterly direction towards the in New York. 20 PEACTICAL TEEATISE ON LIMES, New Jersey State xine, which it crosses between Union ville and the Long Pond. The same stone is also brought to the surface repeatedly in New York, in the counties of Montgom- ery, Herkimer, Oneida, Lewis, Warren, Clinton, and Jefferson. In but few of the localities mentioned is the stone manufac- tured into hydraulic cement, and in none, perhaps, have its full capabilities in this regard been ascertained by adequate experi- mental tests. 14. Within the State of New Jersey this formation continues its course, exhibiting extensive outcrops, lying generally within the limits of a belt or zone from twenty to twenty-five miles in width, which intersects the Delaware River In New Jersey. . ... ^ . „ .iiti-t m the vicinity oi its coniluence with the Lehigh. It then crosses into the State of Pennsylvania, and spreads itself over a large tract in the eastern portion of that State, southeast of Kittatinny valley, in Lehigh, Berks, Chester, Lan- caster, and York counties, and elsewhere. 15. In Virginia the limestones of this formation also exist in numerous and extensive beds in the counties of Rockingham, Botetourt, Roanoke, Washington, Rockbridge, Page, Augusta, ^ ^. _ Giles, and Shenandoah. Cement from the James River and KanaAvha Canal has, for several years, been manufactured at Balcony Falls, Rockbridge County. At the present time cement for constructing the Covington and Ohio Railroad is derived from Dunlop's Creek, a tributary of the James River, a few miles above Covington. There are three cement manufactories on the Potomac River: one at Shepherdstown, Ya., another three miles above Hancock, Md., and another at Cumberland, Md. From the present state of our knowledo;e,it would be inferred that the beds TheYirginianand ^ ^ . i . « • . -^r- • • i Pennsyivaniande- belonging to this formation m Virginia and to bforsuprfor Pennsylvania are better calculated to furnish a quality to those reliable cement than those found in the more farther North. t tvt -xr ^ northern parts of the range. In New York, one member of the series — the Black River limestone — was HYDRAULIC CEMENTS, AND MORTAES. 21 formerly made into cement at and near Galesville, Washington County, for the Champlain Canal. At Point-aux-Koches, on Lake Champlain, a bed of it five to six feet in thickness exists, which possesses a good degree of hydraulic energy, but has never been manufactured for the market. The same stratum has been found to yield only hydraulic lime in some localities, and has been used for that purpose at Lowville, Lewis Coun- ty, N. Y. 16. Among the many analyses that have from time to time been made of specimens from the various deposits of these limestones, those in Table 1. have been selected from the most reliable sources of information which were at command. It is proper to remark in this connection, that those given in the table, — having been derived from State Geological Reports, principally, for the general purposes of which they are doubt- less sufficiently exact, — ought not, perhaps, to be implicitly relied upon, as the basis of any special or criti- , , . „ ^ ^ . . Analysis of the cal research upon the subject of hydraulic above-mentioned mortars and the theory of sub-aqueous indu- ration. None of them show the presence of either potash or soda in any form. It is well known, however, that the salts of both these substances exist in some of the quarries exam- ined, and it is fair to infer, from the close resemblance other- wise preserved in the nature and proportion of g^^^ potash the constituent parts, that adequate tests would probably exist in detect a notable quantity in all. The Rosendale cements contain them. An easy process for detecting their presence, and measuring their quantity, has yet to be dis- covered, which may account for the fact that ^^^^ ^^^^^^ their existence in this class of rocks is so very tected and mea- generally ignored.* * M. Fred. Kuhlmann, Professor of Chemistry at Lille, and Corresponding Mem- ber of the lustitut de France, submitted a report to the Academy of Sciences of France in 1841, from which the following extract is taken. The subsequent wri- tings of M. Kuhlmann, down to a period quite recent, sustain the opinions here 22 PRACTICAL TREATISE ON LIMES, TABLE L AlfALTSIS OP SEVERAL OF THE OLDEST FOSSILirEROtJS LIMESTONES OCCUPYING POSITIONS BETWEEN THE POTSDAM SANDSTONE AND THE UTICA SLATE. I—, cc c ^ Cabonate of lime Carbonate of magnesia Alumina and oxide of iron. . Silica Sulphuret of iron Carbonate of potash and soda Water and loss 54. 42.5 1.5 1.5 52. 37.5 1.5 8.5 46.5 34.5 4. 13. 1. 1. 52. 41.8 1.2 4.7 54. 42.5 .7 2.4 52.9 44. .6 2.2 53. 41.1 1. 3.2 1.7 53.5 38.8 .7 6.3 54.9 34. 2.1 7.5 1.5 53.6 41.6 1.4 3.4 53.3 22.6 1.7 20.T M 1.6} 17. After passing the argillo-magnesian limestones associated ^ ^ with the " Calciferous Sandrock," and inter JNo cement stone ' between the utica mediate in lithological features between this Slate and the Nia- i t -i t , ^ gara Group of the rocK and the purer limestones above, we meet Ontario Division, ^.^j^ calcareous deposit suitable for hydraulic cement until we reach, in the ascending order, the Niagj-ra Group of the Ontario Division, among the beds of pa.c>e.^ge from the shale to the limestone of that group. Here i<' found an argillaceous limestone brought to the surface reyc/'chdlj in the State of ISTew York, in Wayne County, and ^ ; t^iC towns of Kose, Williamson, and Ogden, in Monroe UrcAtj. This expressed as to the general prevalence of the alkaline salts i^- '/.e hydraulic limea and cements of Europe. Extract. — In speaking of the nature of the efflorescences t^on walls, he says . " Mes investigations sur ce point m'ont permis de constar^rt la presence de la po- tasse ou de la soude dans la plupart des calcaires de diversujs epoques geologiques, et de justifier I'existence de ces alcalis dans les vegetaux qui croissent sur un sol cal- cftire." M. K. also analyzed the cements of Pouilly, Vassy-les-Avallon, Bou- logne, and the Roman cement from the Septaria, taken from the banks of the Thames, and found potash in all of them, notwithstanding the confirmed opinirjn of chemists that they contain no alkahne ingredient. American cements conth,*u chlorides of potassium and sodium generally, sometimes as high as V per cent HYDEATJLIC CEMENTS, AND MORTARS. 23 deposit exposes very good cement stone in Orleans County, at Oak Orchard Creek, town of Shelby, and at Farwell's Mills, town of Clarendon ; also in Niagara County, at Lewiston. Among these beds of passage, only those occupying a central position can be relied upon for hydraulic mortar, the layers above being, as a general thing, too highly charged with car- bonate of lime, while those below contain too much clay. 18. Overlying the Niagara Group, we find, in the Helder- berg division, a limestone among the upper beds of the Onon- daga Salt group, sometimes called the Magnesian u Magnesian De- deposit of that group, which furnishes nearly all ^^daga^sllt^ the hydraulic cement manufactured in the group, western part of the State of New York. It appears on the eastern shore of the Cayuga Lake, and further west, in Phelps and Manchester townships, Ontario County, at Williamsville, Grand Island, and Akron, Erie County. At East Yienna it has been used for cement, and at Akron a manufactory of some extent is in operation now. At Morgantown, Genesee County, and at Black Rock, Erie County, the limestones of this group have an extensive devel- opment in connection with those of the Water Lime Group proper. Its full thickness is seen at the Falls of Falkirk. It underlies the village of Caledonia, Livingston County, ex- tending thence easterly towards the Genesee River, and, re- appearing on the other side of that stream, is found at Mendon, Monroe County, and other neighboring localities. 19. Beyond the limits of the State of New York, the layers above mentioned are not found possessing such prominent features as to entitle them to a distinct and separate descrip- tion, but are included in the contiguous groups under a more general classification. 20. Overlying the Onondaga Salt Group, in regular suc- cession, is found, along the great Appalachian range, the Tentaculate, or Water limestone, from which a » Tentaculate" or very large proportion — perhaps nine-tenths — of p^^^^^^ 24 PRACTICAL TEEATISE ON LIMES, tlie hydraulic cement manufactured in the United States is de- rived. It appears to be wanting in the West- Geographical lo- ^ caiities of the ern States, or to have been replaced hj the principal beds. q^j^ limestone of Ohio. In E ew York, it is found in large quantities in Oneida, Onondaga, Madison, Ul- ster, Sullivan, and Erie Counties. Its principal deposit is in Ulster County, where it furnishes the celebrated Rosendale cement,* so extensively used on the government works on the Atlantic, Gulf, and Pacific coasts, and along the northern frontier. It is quarried for cement at Manlius and Fayette- ville, Onondaga County, and Chittenango, Madison County. The cements from these localities vary very much in quality. A cement manufactory is also carried on at Lockport, Niagara County. The stone that may be used for cement, occurring frequently along the line of the Erie Canal, occupies, with some local exceptions, two geological positions quite distinct General character from each other. The lowest layers are mostly stone^afo^The Confined to the beds of passage from the shale Erie Canal. of the Niagara Group to the purer lime- stones above, while the others are similarly situated with refer- ence to the marls and shales of the Onondaga Salt Group and the purer calcareous beds which overlie them. In either po- sition, great care is requisite in selecting the stone for burning, the best cement being generally confined to the middle of these beds of passage — those below being too argillaceous, those above too calcareous. 21. Reserving a more detailed and minute description of the Ulster County deposits for a subsequent part of this work, we will here simply state that they are mostly found within the limits of a narrow belt, scarcely one mile in width, skirting the Principal deposits northwestern base of the Shawangunk Moun- of " Rosendale tains, alouff the line of the Delaware and Hudson Cement" stone. ^ Canal, in the valley of Rondout Creek. They are * Named from the town of Rosendale, in which the cement was first discovered and manufactured, during the construction of the Delaware and Hudson Canal. HYDEAULTC CEMENTS, AND MOETAES. 25 not, however, confined to this locality, but can be traced in a southwesterly direction through Ulster and Sullivan Counties to the State Line at Carpenter's Point, and thence, within the State of New Jersey, in a narrow strip along the left bank of the Delaware Kiver, to Walpack's Bend, where they cross over in- to the State of Pennsylvania. In a northerly direction, this rock has not been distinctly recognized east of the Hudson Eiver. At the mouth of Eondout Creek the belt takes a turn due north, and can be correctly followed along the right bank of the Hudson, a distance of five or six miles, with occasional glimpses of it in detached masses ten or twelve miles higher up. Except in Ulster County, towards the northern terminus of the range, these beds have not been manufactured into cement, and have not, it is believed, been very critically ex- amined with that view. 22. The only limestone in Massachusetts that has ever been employed for hydraulic mortar is that at Paine's Quarry, West Springfield. It is said to be very good hydraulic lime, and contains, by analysis, .93i of carbonate of lime. Cement stone in .5/o- of argillaceous clay, and less than .1 of car- Massachusetts, bonate of magnesia. Another hydraulic limestone that has been tried, but never worked, is found in the bed of the Chi- copee Piver, just below the Chicopee Factory. It contains .S6j\ of carbonate of lime, and .13y\ of argillaceous clay. Both of the stones just mentioned are fetid and partially bitu- minous. They belong to the new Red Sandstone formation. Nodules of Septaria are found on the Chicopee and at Cabot- ville, and an argillaceous limestone at West Springfield, that are pronounced by Prof. Hitchcock to furnish a cement as energetic as the " Poman " The following table contains their analysis ; 26 PRACTICAL TREATISE ON LIMES, TABLE 11. Argillaceous limestone, West Springfield. Septaria from the Chicopee. Septaria from Cabotville. 1st Sample. 2(1 Sample. Carbonate of lime Carbonate of magnesia . . Silica and alumina Oxide of Iron 46.06 27.35 20.97 5.62 43.69 39.35 13.57 3.39 30.81 26.04 18.33 13.45 45.33 54.00 5.53 6.51 The 2d sample from West Springfield is but feebly hydraulic. 23. East of Massachusetts, cement stone is found in some localities, but is not used for hydraulic mortar. Deposits exist r««^^r,f of^r,n ir. ^t Machlas aud at the forks of the Kennebec locality, analyzed several years ago by Dr. Charles T. Jackson, contained .54:yV of carbonate of lime, .05 of carbonate of magnesia, .028 of carbonate of iron, .024 of silicate of iron and manganese, .27 of silica, .082 of alumina. 24. Near Kensington, Conn., a good cement stone is found, Cement stone in which is manufactured to a limited extent for at the Falls of the Ohio Kiver. 25. The following extract from the forthcoming work of the Cement stone in State Geologist of Mississippi, gives the analysis Mississippi. cement stones found in that State in Tish- amingo County : " E'o. 1 furnishes a cement which sets as rapidly as Plaster of Paris and becomes very hard. 'No. 2 dif- fers from No. 1 in requiring more time to harden." See Cement stone in Maine. Piver, Me. ; a specimen from the last-named Table III. TABLE III. Silica and insoluble Silica Potash Lime Magnesia Protoxide of iron Alumina Phosphoric acid Carbonic acid Water, organic matter, and loss No. 1. 54.201 .473 23.247 .788 .903 1.064 Trace 15.572 3.752 No. 2. 35.281 .348 32.603 .630 .158 1.914 27.643 HTDEAULIC CEMENTS, AND MOETAES. 27 26. No deposits of hydraulic lime or cement stone are found on the Pacific coast, although inquiries to a considerable extent have been made. The Eosendale cements are depended upon for hydraulic mortar. 28 PEACTICAL TREATISE ON LIMES, CHAPTEK II. 27. The method pursued in testing the mortars which fur- nish the basis of all tables introduced into this report, with the exception of those compiled from the labors of others, for the purpose of reference and comparison, is briefly as follows : 28. With some exceptions that will be pointed out in the proper place, all the samples of hydraulic ce- The cements not , ^ i . , i . • i prepared under ment not prepared at the manuiactories, under the writer's super- ^-^^ personal supervision of the writer or an vision were sam- ^ ^ pies from cargoes affcnt appointed by him, were obtained from in the market. ^ . \, i , . . cargoes m the market, by opening several casks selected at random, and taking two or three pounds from each. This precaution was adopted in order to secure, beyond a ques- tion, samples of an average quality from the respective cargoes, and for the time being, of the respective cements furnished bj the several manufactories. 29. Identity in the composition and properties of samples of the same brand, obtained from different cargoes and at differ- ent times, was never assumed. An examination and compari- son of the tables throughout this work, clearly establish the necessity of this precaution. As some manufacturers habitu- ally grind their stone finer than others, and as there is consid- erable difference, in this particular, in cement from the same establishment manufactured at different times, due in part to the difiiculty with which a high degree of pulverization can be secured with newly-dressed millstones, but principally to negli- gence on the part of the miller, it was important that this cause HYDEAULIC CEMENTS, AND M0RTAK8. 29 of variation sliould be eliminated in all the trials, and particu- larly from those which were to furnish the data for a direct comparison of the qualities of the several cements, and of mor- tars of diiferent composition, but particularly those containing large doses of sand. To this end, all the varieties of cement subjected to trial were passed through a fine wire sieve, designated Ko. 80, that is, containing eighty ^ere^sifted ^in fine wires to the lineal inch, each way, or 6,.4:00 ^i^® ^^^^^ meshes to the square inch. The sand used for the mortars, when the object was simply to compare the qualities of the several varieties of cementing substance, whether of pure cement, or a mixture of cement and lime, though quite fine, was clean, and tolerably sharp and angular. It is mostly sili- cious, and was obtained from a pit on Governor's Island, New York harbor, between Castle William and Fort Columbus. After being passed through a wire sieve No. 30, to remove a small per centage of gravel heterogeneously distributed through it, 1,000 parts by weight contained : 1 63 parts between and of an inch in diameter. » » -L- » -i- '« » " » » Character of the 40 6 0 sand used. 352 " " ^0 " " " " " 183 " less than /o" CHARACTER OF THE TESTS APPLIED TO THE MORTARS. 30. 1st. Their capacity to resist a transverse strain, which is also a measure of their tenacity. To this end, rectangular prisms were formed in a cast-iron mould, under pressure or otherwise, as specially set forth in each particular case. The base of these prisms was two inches square, their height eight inches. The first that were prepared were formed in a hori- zontal mould, the pressure being applied to the upper side. As it was always necessary to shave off one of the sides of these blocks, in order to reduce the cross-section to a square, the ho. zontal mould was soon replaced by a vertical one, measuring 30 PRACTICAL TREATISE ON LIMES, Mortars made in ^ m. by 2 in. by 8 in. in the interior, to one end prisms 2 in. by 2 which the pressure was applied. "When the •n. by 8. and bro- , , ken on ' supports prisms had attained the requisite age, they were 4 m. apart. broken on^ supports 4 in. apart, by a pressure applied at the middle point. 31. 2d. Their relative hardness. — This was measured by the penetration of a steel point or needle, impelled by the impact of a falling body. The needle, which is slightly conical, or tapering toward the point, is truncated at right angles to the axis, so as to give a diameter at the lower end of i^^- of an inch. It protrudes from a socket in the lower extremity of a vertical rod or spindle, to which it is firmly secured by means of a Hardness com- thumb-screw. To the upper extremity of the dfe^^penetrating spindle is attached a diagonal scale of steel, accu- by impact. rately graduated to tenths, hundredths, and thou- sandths of an inch, and provided with a horizontal index firmly fixed to the frame-work of the instrument. The absolute pen- Fig. 1. . etration of the needle is obtained by taking the difierence be- tween the index readings before and after impact. The falling body is a hollow metal cylinder, weighing one pound, of which the exterior diameter is about equal to the length. This cylin HYDE AT] Lie CEMENTS, AND MORTARS. 31 der, in its descent, passes freely over the spindle, and strikes upon a shoulder attached just above the screw. The mortar used to determine the hardness was that of the broken prisms, and the penetrations were taken the same day, generally but a few hours after they had been broken. As these fragments were 2 in. square in cross-section, and seldom less than 2^ in. long, they admitted of several trials with the needle. An average of not less than four penetrations, and sometimes more, at each end of the prisms, was taken on all occasions, except, when the frag- ment split open at a lower number, which was sometimes the case. This instrument will be well understood by referring to 32. 3d. Their adhesive properties. — This was measured by cementing bricks and blocks of stone together in pairs, and afterwards drawing them apart by a force applied Adhesiveness to at right angles to the plane of the joint. The ^ea^^reT''''^ bricks or stone of each pair were arranged at right angles to each other, as seen in Fig. 2, and were kept together under a pressure of 500 lbs., except on occasions specially mentioned, until the mortar had set. 33. The device for applying the pressure to the Tig^ prisms^ and to the pairs of bricks or stone, while the mortar was setting, is essentially the same as that heretofore used for simi- lar purposes. It was also used for testing the strength and ad- hesiveness of the mortars, when they had attained ^ . , ^ Device for com- the proper age. The apparatus consists essen- pressing the tially of a bed-piece and two upright posts, about S^mouids,^^ one foot apart, connected by a cross-piece at the ^^^^^^^f ' ^ prisms, &c. top, from the centre of which is suspended a scale- beam, so arranged that it can be elevated or depressed, as oc- casion may require, by means of a screw. The lower hook of this beam is connected with a horizontal lever of equal arms, so that any weight indicated by the beam will be transmitted without loss to the reverse end of the lever, and will then act 32 PRACTICAL TEEATISE ON LIMES, as a downward pressure. The application of this pressure to the breaking of prisms is explained by Fig. 3. It is only necessary to replace the wedge-shaped piece which acts upon the prisms by another which will diffuse the pressure over a aorizontal area of greater or less extent — say about one super- ficial inch — in order to adjust the instrument for applying pres- sure to the mortar in the moulds, and to the pairs of bricks or stone. Fig. 4 represents a prism under pressure. The lower Fig. 4. Fig. 5. rig. 3. portion of the mould is inserted into a mortise in the bed-plate. In order to measure the force necessary to separate the bricks or stones, they are placed directly under the hooks of the scale- beam, the lower lever having first been removed. The lower brick or stone is then confined to the bed-pieces by staples, keyed from below, while the upper one is embraced by the ends of a crescent-shaped iron, suspended from the hook of the scale-beam, as shown in Fig. 5. 34. In all cases, the moment of rupture was attained as quickly as possible — care being taken to avoid shocks— by Instant of ru pouring sand into the pan of a spring-balance ture to be at- suspended from some given point on the beam, tained quickly. shown in Fig. 3. In setting forth the results HYDEAULIC CEMENTS, AND MORTAES. 33 of these trials in a tabulated form, the actual breaking weight and penetration are, in all cases, entered without reduction except in the case of separating the bricks and stone, when an additional column is inserted in some cases, giving the ad- hesive power per superficial inch. 35. The trial with the needle was adopted as the most ready means of measuring the relative hardness ^^^^ ^^^^ of the several mixtures containing no sand, with needle was . adopted, whether of pure cement or a combmation oi cement with fat lime. Is'othing further than this was at first expected from it. M. Yicat at one time entertained the opin- ion, which he subsequently qualified and even abandoned, that " the squares of the numbers which express the penetra- tion of the rod are reciprocally proportional to ^ ^ . Law deduced by the resistances to the force which tends to break Vicat ; aban- the mortars." General Treussart not only doubts the existence of this law, as not fully established by M. Yicat's experiments, but advances objections to the use of the needle, which do not appear to be wholly tenable, viz : 1st. That it is difficult to appreciate exactly (jeneral Xreus- its penetration ; sart's objections n 1 m i. -i? 'J. ii' n • ^ 1 to the needle test, 2d. lhat, II it tails upon a gram of sand or gravel, or even a grain of lime, incorrect conclusions will be drawn ; 3d. That it is applied to the surface of the mortar, which frequently difi'ers in hardness from the interior. 36. It is submitted that the first of these objections cannot apply to an instrument like that shown in Fier. ^, ^ , ^ ^ The first not ten- 1, if constructed with accuracy and used with able when needle .1 T . n i /> 1 is used with care. care ; the second is equally without force when no sand is introduced into the mixtures; and even the effect of sand of fine grains, in large doses, might be re- T , • n . .11 The second ditto, garded as practically inappreciable, provided for mortars with- the weight <5.f the falling body and the distance ^^^er ^eavy massed over in the descent are such as to cause impacts. 3 34 PRACTICAL TREATISE OK LIMES, deep penetrations. Moreover, an ordinary degree of precaution would suggest the propriety of taking the average of a h^rge number of trials in preference to the results indicated by a single one, when they can be repeated with such ease and rapidity. It is not contended that penetrations from impact afford reliable data for comparing mortars containing different proportions of sand, or sand in different degrees of fineness. The objection urged against deducing conclusions with regard to the quality of a mass of mortar from the results of trials restricted to its surface, is certainly worthy of consideration when mortars of common lime, either with or without sand, are under trial, but is scarcely applicable to hydraulic mix- Remarks on tures. The absolute strength of a mass of third objection. mortar is not the only good quality we seek. Deterioration from the action of the elements first takes place upon the surface in all cases, and it is upon the surface, with- out regard to interior qualities, that the requisite power of resistance against these agents must be conferred. Experience teaches us that those mortars which attain the greatest degree of superficial hardness, as shown by the penetrations of the needle, absorb the least amount of water, and are consequently the least liable to undergo disintegrations from frost or " weathering." The resistance offered at the surface to the penetration of a point acted upon by an impulsive force, there- fore, affords reliable means of judging of a most important property in mortars, even if we admit that our conclusions must necessarily be restricted to their surface. But this is not so. It is well known that hydraulic mixtures owe very little of their powers of sub-aqueous induration to the absorption of car- bonic acid gas, or to superficial desiccation ; that harden^ s^ulta^ the setting is not initiated at the surface, but neousiy through- almost simultaneously throu2:hout the mass ; and out the mass. . . . that the subsequent induration is not augment- ed, but rather retarded, and in some measure even destroyed^ by free contact with the air, and the absence of humidity. HYDRAULIC CEMEJSTTS, AND MOETAES. 35 37. We may safely assume that mortars of hydraulic cement, either with or without sand, if submerged, harden so nearly homogeneously throughout their entire thickness, that there is no perceptible difference in hardness at the centre, and at a depth of -J-^ to of an inch. At any rate, those disposed tc entertain doubts upon this point can readily convince them- selves, by reference to the tables, that, with individual excep- ^ ^ , tions, the mortars which sustain the greatest The strongest ' ^ ^ ^ prisms gave the transverse strain give the smallest penetrations least penetrations. n i«- ^ • t ' With the needle; and it certainly is not un- reasonable to suppose that there may exist a fixed law or pro- portion between the resistances offered to two kinds of forces, — one constant, and the other impulsive, — by an inflexible sub- stance like mortar. 36 PEACTICAL TEEATISE ON LIMES, CHAPTER III. 38. The celebrated Rosend ale cements, — so named from the fact that the stone was first discovered in the township of The "Rosendale" I^osendale, Ulster County, I^ew York, in opening Cement. Wj^q of ^j^g Delaware and Hudson Canal — are derived from the tentaculate or water limestone belonging to the lower Helderberg Group, known as Formation YI. in Pro- fessor H. D. Rogers' classification of the rocks of Pennsylvania. As stated in Chapter I., the deposits are mostly found within Geographical limits of a narrow belt scarcely one mile limits of the beds in width, skirting the northwestern base of the Shawangunk Mountains, along the line of the Delaware and Hudson Canal, in the valley of Rondout Creek. The beds are found occupying every conceivable in- clination to the horizon, being sometimes vertical, seldom on a level, and ordinarily dipping at a greater or less degree either to the northwest or to the southeast. The entire face of the country in this region exhibits unmistakable evidences of hav- ing been subjected to a succession of remarkable upheavings ; some of them have evidently taken place while the limestone deposits were as yet in a plastic form, by which the strata, in The beds are tor- niany localities, were twisted into a variety of complex and tortuous shapes, while others, trans- piring at subsequent periods more or less remote, have ruptured the beds in a variety of ways, frequently producing faults, but ordinarily resulting in a multitude of seams more or less open, running diagonally across the planes of stratification. The HTDEAULIC CEMENTS, AND MOETAES. ^7 useful effect of these upheavings has been to develop, into accessible and convenient positions, a vast amount of cement stone, that would otherwise have been buried beyond the prac- ticable reach of ordinary mechanical skill. 39. The aggregate thickness of the several layers of this deposit averages about forty-six feet. This includes several strata, varying from four to twelve feet in total thickness, which are so changeable in character that they ^g^^egate thick- are fit for use only in certain localities. The ness of the sev- whole deposit is subdivided into several distinct layers, which are widely dissimilar, as a general thing, in the color, grain, and texture of the raw stone, and also in their hydraulic properties after calcination. As Seventeen layers many as seventeen of these layers can be traced ^ throughout the entire range in Ulster county. 40. ISTo one manufacturer makes use of all of these beds, and no two of them of the same beds, in the same Not all used for proportions. This is due, principally, to those the^ changeable** marked variations in the hydraulic character of character of stone, the stone, within comparatively short distances, which con- stitute a characteristic feature of this deposit, already referred to in general terms. 41. In some localities, the upper layers of the cement bear- ing series have been removed by abrasion, while Upper layers in others, the lower ones have been thrust so sometimes absent, ^ and lower ones much out of place by the interposition of other beyond reach. rocks, or are so far below the general surface level, that they cannot be reached with facility or economy. 42. Few of the manufacturers have rendered themselvea familiar with the distinctive and peculiar properties of the several layers which they introduce into their combination, in stances being comparatively rare where they have caused them to be quarried, calcined, and ground separately, even for the purpose of experiment. 43. With few exceptions, all the stone taken from a qnarrj 38 PEAOTICAL TEEATISE ON LIMES, bad, not necessa- rily objectionable in a combination. 2 enters into the cement prepared for market. This includes certain layers, or portions of layers, possessing little or no Some inferior hydraulic energy by themselves, on account of stone IS used. i]^q preponderance of inert silica or alumina which they contain, and the absence of homogeneousness in the composition; other portions, in which the carbonate of lime is largely in excess, and which may be classed among ordi- nary hydraulic limes ; and still others, which are an exagger- ated type of the dividing limes {chaux limites) of Yicat, setting rapidly in water under the most difficult circumstances, suc- cedeed sooner or later by a gradual softening of the whole mass. 44. Although mortars giving rise to the phenomena last- Stone individually mentioned contain an excess of caustic lime, which becomes hydrated very sluggishly, and indeed not until the hydraulic induration has \ fully commenced, and which, therefore, is insusceptible of prompt neutralization by the sil- ica, alumina, and magnesia pre- sent, in the formation of those tre- ble hydrosilicates that are prac- tically insoluble in water, it does not necessarily follow that their incorporation in subordinate pro- portions, and under judicious re- strictions, into the aggregate pro- duct of a' quarry, is injurious. In certain cases, when care is taken to reduce the cement to a very fine powder, with a view to facilitate the hydration of the lime, and to secure a thorough incorporation of the sev- eral kinds of stone used, they are believed to operate beneficially by furnishing those requisite constituent ingredients of good ce- ment not found in sufficient quantity in the contiguous rocks, Light cement or Upper Series. Middle Series. ■* 1 6 « > Dark cement or Lower Series. Fig. 6. HYDRAULIC CEMEJ^TS, AND MORTAES. 39 or existing there in proportions capable of considerable in- crease, without producing an injurious excess. The marginal sketch, Figure 6, shows an actual Section of the p,, , .^T. T ^ T cement deposits section 01 these deposits, verined m several locah- of Ulster Co., N.Y. ties, where the layers occur in regular order.* 45. In some localities, where the beds have been upheaved into a vertical position, or nearly so, and the stone of inferior quality occurs in layers of sufficient thickness to sustain them- selves, they are left intact, supported at appropriate intervals by masses of the stone composing the adjacent layers. 46. Some of the most prominent features of these several layers will now be briefly noticed. They were quarried and calcined separately by an experienced workman. For their burning, " try -'kilns''' 7 to 7|- feet high and 20 to 24 inches in in- terior diameter were used, and the object aimed at in each case was to submit every variety of stone to that degree and duration of heat that would produce the best results. Besides these tests, others were made with the stone by submitting it to different degrees of calcination in crucibles. 47. Nximher One is moderately fine grained, of a dark gray color, and contains rather too much silica. After burning, the cement is of a light-drab color, and sets under water in fifteen * The sections of the cement strata in Ulster County, as given in the Report of the State Geological Survey, are singularly at fault. The one purporting to have been taken at High Falls, near and just below the bridges (see Report of First District State Geological Survey, p. 353), is as follows: Cement rock 12tol5 feet . Limestone 10 to 30 " Cement rock 6 to 8 " Pyritous slaty limestone 4 to 10 " Red shale, &c 15 to 20 " Conglomerate and Shawangunk grits unknown thickness. The correct section of the beds in this locality, now constituting Ogden & Co.'s quarry, and at the time of the survey owned and worked by Mr. J. L. Hasbrook, is as follows : — the layers above No. 9 do not occur here. Cement rock 15 to 16 feet. Magnesian limestone, unsuitable for cement, and therefore not used. It is dividing lime 2 to 2| " Cement rock 5 to 6 " Argillaceous slaty limestone -J to 1 " Pyritous limestone Shale, &c., as before 40 PEACTICAL TREATISE OlS^ LIMES, Number One a minutes to bear the light testing- wire.* This Spt^aSwrence- ^tone, except in the vicinity of Lawrenceville, where it possesses, to a limited extent, the objec- tionable properties of intermediate limes, furnishes a good cement by itself. 48. Nuraber Two resembles the preceding, when in the raw state, but is of a somewhat darker color, and is much quicker setting after calcination. In the vicinity of Lawrenceville it pos- sesses, to a limited extent, the bad qualities of the Number Two . ' . . ^ resembles Num- "intermediate" limes, and is unfit for use, except ber One. combination with the other layers. It is not excluded by any of the manufacturers. 49. Numher Three is a coarse-grained light-gray magnesian limestone, containing, after calcination, an excess of caustic lime and silica in the form of sand. It belongs to the worst Number Three ^-^P® intermediate limes, and is incapable of ia an " interme- being used alone, except after several months' diate lime." i pt^ ^ • i • . -^i exposure to the enects oi air and moisture, either in casks or in bulks, and even then is greatly improved by being mixed with ten to fifteen per cent, of an active cement, with a riew to restore the energy destroyed during the process of spon- taneous slaking. A fresh sample, mixed to a stiff paste, and Sets in the air formed into a cake, set in the air in eight min- ens'when"^^^^^ ^^^^s, and was then immersed in water at 65° F. water. soon began to soften, and in one hour allowed the light-testing wire to pass freely through it. Another cake, immersed in water in the condition of paste, began to set in four or five minutes, so far as to lose the plastic form, which was immediately followed by the appearance of a multitude of small cracks, and a rapid and progressive softening from the surface inwards. After fifteen minutes it was worked up under the trowel, dried off with blotting-paper to a stiff" paste, again formed into a cake, and immersed. At the expiration of twenty ♦For a desci-iption of the testing-wire, see paragraph 121. HYDEAULIC CEMENTS, AND MOETARS. 41 minutes, a close network of cracks again covered the surface, when it was worked up, as before, for the second time. This operation was repeated for the third and fourth times before the submerged cake would retain its form under water, and indu- rate without cracking. It then required six days to bear the aV inch wire, loaded to one pound. Some of the powdered cement was heated to redness for half an hour, in order to approximate more nearly to the condition of complete calcina- tion, but its qualities were in no respect improved thereby. Some of the same cement, when fourteen months old, after having been preserved in an ordinary powder-keg, without paper lining, during that period, had entirely lost the dangerous property of disintegrating under water, which it possessed in such an eminent degree when fresh. It had also parted with much of its hydraulic energy, requiring from eight to nine hours, when submerged, to attain the requisite hardness to support the light-testing wire, and twenty hours to support the heavy one. Some of this old cement was heated to redness for half an hour, which, while it fully restored its hydraulic activity,, at the same time destroyed its ability to stand up under water. Trials were also made by adding to this cement a soluble alkaline silicate, in order that silica might be Trials with " solu- presented to the lime in a condition favorable to glass." an immediate combination with it, with a view to anticipate, as it were, the initial induration of the native hydraulic ingredients. The results were entirely satisfactory. The double silicate of potash and soda was employed for this purpose, in the succes- sive proportions of 11, 9 and 5i per cent., by mixing it with the water used for bringing the cement to the con- Eleven per cent, dition of paste. In the first two cases the sue- Three cess appeared to be perfect, and resulted in the ^ good cement cakes setting under water in ten minutes to bear the light test- ing-wire, and in twenty-five and thirty minutes respectively to bear the heavy one, without any subsequent appearance of cracks or change of form. With 5^ per cent, of the alkaline 42 PEACTICAL TEEATISE OlS^ LIMES, silicate, the cracks upon the surface were not entirely avoided, but they penetrated but a very little way into the mortar, caused no visible change of form, and appeared to exercise no influence upon its ultimate strength and hardness. 50. Nwmher Four^ in some localities, is solid and compact Number Four throughout, and in others is subdivided into two subdivided into layers of nearly equal thickness. The upper two layers. portion is fine grained, dark blue, burns of a light drab color, and is quick setting ; that below is darker after calcination, contains more lime, and does not set readily under water, if immersed in the state of paste. Between these two subordinate members of this layer, a thin sheet of argillo- calcareous slate sometimes occurs, which has to be excluded from the combination. With this exception, the entire layer, ,. , worked tosrether, makes a cement of fair average Tne entu'e layer ^ ? t> makes good ce- quality, and there is perhaps no member of the deposit in Ulster Co. which preserves, through- out its entire development, a character more uniformly reliable. Immersed in the state of paste, in water at 65° F., it hardens so as to support the light testing-wire in fifteen to twenty min- utes, and the heavy one in twenty-five to thirty minutes. 51. Numher Five. This layer, throughout the entire range of the beds as yet opened, except in the quarries belonging to the Newark Lime and Cement Manufacturing Company, at the mouth of the Rondout Creek, is a coarse-grained magnesian limestone, containins; so larp:e an excess of car- Number Five ^ ' . . . m 1 T slakes after cai- bonate 01 hme that it generally slakes alter cal- meagTe\me%iid cination, like hydraulic or meagre lime. In the js^g^erally re- quarries of the Hudson River Company, about five miles back from the Hudson, the upper half of the layer is more highly charged with clay and magnesia, and is so far modified in its prevailing character that it is in- cluded in the combination. "With these two exceptions, the stone is rejected by manufacturers. 52. Number Six is a limestone of slaty structure, containing HYDEAULIC CEMENTS, AND MORTAES. 43 a .arge amount of clay and lime, particularly of the latter, and possessing, to a certain extent, the objectionable dumber Six is an jroperties of J^umber Three. It varies in thick- intermediate lime, ness from six inches to two feet, and possesses a distinct devel- opment in all the quarries, except those at the mouth of the Rondout Creek, where it has either been omitted in the depo- sition, or has been more or less uniforml}^ distributed through out the contiguous layers. The latter would appear to be the most probable hypothesis, as those layers. (Five and Seven) which in most of the quarries contain a ruinous excess of car- bonate of lime, constitute in this locality the best stone of the deposit. "When made into cement, and allowed to set in the air, the influence of water upon it after immersion is moderately slow, so that the mortar is not thrown down completely, like that derived from I^umber Three, but is simply covered with many deep cracks. A prism measuring 2 in. X 2 in. X 7 in. was formed of a paste of the pure cement from . . ^ -t rrism of pure this layer, as developed at High Falls, and im- cement from . . . this layer. mersed m water alter supporting m twenty min- utes the light testing-wire in the air. After twenty hours, it began to swell and crack along the longest edges, the cracks being directed toward the axis. After thirty hours, these cracks presented an exterior opening of and after fifty hours, of J of an inch. The prism then broke into three pieces trans- versely, and was nearly a week in assuming a stable form. The form of a cross section at that time is shown in Fig. Y. 53. Number Seven is perhaps the most changeable member of the cement deposit. ISTear High Falls, on Coxon Cove Creek, it was manufactured into a cement several years ago by Mr. 0']Sfeill, which was considered by the late Col. J. L. Smith, of the Corps of Engineers, superior aS^oTNumbe^* to any cement brought into market at that time. S?!®^;""^^^^ _ ^ O'Neill cement In other localities, near High Falls, the stone is PEACTICAL TEEATISE ON LIMEb, in every respect as good as that used by O'l^Teill, but all at- tempts to turn it to any account elsewhere have failed, except at a point above one mile south of Rosendale Tillage, where it was worked in 1840, and at the mouth of Eondout , „ Creek, twelve miles distant, where it is of ffood Number Seven, ^ not generaUy quality, and furnishes about 25 per cent, of all the stone used in that neighborhood. In con- nection with the two overlying strata, Five and Six, it con- stitutes the middle rock, a prominent feature, common to all parts of the range (with the exceptions mentioned above) which is not disturbed in quarrying. The prevailing character of Is generally left dumber Seven, to which its bad qualities are undisturbed in chiefly due, is its remarkable and persistent want the quarry. 01 homogeneousness. When burnt, it presents an entire absence of any uniformity of color, being generally vari- egated and mottled in appearance, exhibiting almost every grade of neutral tint between pure white, derived from masses of carbonate of lime, and the darkest brown, approach- ing to black. Hence the constituent elements of the stone, although they may be present in suitable proportions, are be- yond the influence of those mutual reactions which take place dnring the calcination, when the ingredients are in intimate and homogeneous contact, and the lime which should have en- tered into combination with the silica remains free and in ex- cess. Instead of being pure, however, or practically so, a con- dition which would be favorable to its instantaneous slaking when brought into contact with water, it is mixed with a suffi- ciency of foreign matter to render it meagre, technically so called, and consequently sluggish and tardy in assuming the form of hydrate. ]^ umber Seven is therefore, with the excep- tions noted, an intermediate lime, and unfit for cement. 54. Number Eight is unsuitable for cement in any part of the range yet opened. It is much more uniform in appearance, Number Eight and is far less heterogeneous in composition, than L'cement^^ Number Seven. In the vicinity of High Falls, HYDEATJLIC CEMENTS, AND MOETAES. 45 it is characterized by the objectionable proper- ties of ISTumber Three. It will commence to set readily under water, but in a few hours becomes converted will not set into a thin paste. Further east, it loses all underwater power of indurating under water, and will not retain in that situation a set taken in the air. In some localities it adheres to, or rather forms a part of Number Seven, and is left stand- ing with it, while the underlying and overlying strata are removed ; in others it becomes separated in blasting, and in many cases, it is feared, finds its way into the manufactured cement, and injures its quality. 55. The layers numbered from Nine to Sixteen^ inclusive, possess no striking individual characteristics, ex- Layers Number cept in two localities. Taken together in the doTouS^'' proportion of their development in the beds, strikingly, they furnish a cement of good quality. Its hydraulic activity is somewhat less than that derived from a combination of the " Upper Series" of layers exclusively, but, in ultimate strength and hardness, it will compare favorably with any cements in the country. The two exceptions are as follows, viz. : one at High Falls, where Number Fifteen is an inter- mediate lime like Number Three, while Num- at High Falls is ber Sixteen sets more rapidly under water than Sm? and Num! any strata in Ulster Co.; and the other at the ber SLxteen very mouth of Eondout Creek, where the Lower Series" of strata do not occur at all, or are so changeable in hydraulic character, chemical composition, and lithological features, that their geological identity is a matter of some doubt. 56. Nwnber Seventeen^ although difiering very materially from Number Sixteen after calcination, is mechanically at- tached to it, and has generally to be taken out with it. It contains a very large proportion of refractory j^^^^er Seventeen clay, and is in most localities, and particularly ^^^t a good stone, at High Falls, very hard, like overburnt bri cks, when cal- 46 PEACTICAL TEEATISE 01^ LIMES, cined in the same kiln with the other layers. It possesses little hydraulic energy, and should be excluded from the com- bination. As a prominent feature of the entire deposit, the color of the burnt stone is subject to great changes, within short distances. 57. At High Falls, the southwestern terminus of the deposit as now worked, where the manufactories of the Ogden Com- pany, and Delafield & Baxter (formerly Ogden & Delafield) ^ ^ are located, all the layers, and consequently com- at High Falls is binations of them adopted for the articles sent cf "es"'r "as ^'^ -narket, are lighter colored after burning than we approach the in any other locality. As we approach the Hud- Hudson Eiver. . . son River the "Lower Series" undergo a decided and sudden change, so much so, indeed, that at Lawrence villa, only two and a half miles from High Falls, although they fur- nish but .60 of the combination used by the Lawrence Com- pany, and although one-half of the remainder is brought from High Falls, and is very light-colored, the combination is one of the darkest of the Rosendale brands. Between this point and the Hudson, their color remains dark, and that of the " Upper Series" becomes moderately so. In point of fact, the only Rosendale cements technically termed " Ughf^ are the two brands manufactured at High Falls by Delafield & Baxter, and the Ogden Cement Company. 58. The Newark Lime and Cement Manufacturing Com- Newark Lime ^pany is located on the Hudson River, at the ZnuStoing Rondout Creek. Its works comprise Company.— Ca- seventeen cylindrical kilns of the pattern shown pacity of their . .n i • works. m Figure 12, and the mill driven by steam- power, containing five " crackers" and eleven run of stone of two and a half feet in diameter, and two run of four and a half feet diameter. Four of the crackers, and five run of stone, can grind eight hundred barrels of cement per day. The cement stone occurs in a continuous bed varying in thickness from twenty to thirty feet, and dipping to the northwest HYDRAULIC CEMENTS, AIS^D MORTARS. 47 from 45° to 75°. It crops out along the eastern slope of a high hill or bluff, at an elevation, in places, of from 150 to 170 feet above the level of the Hudson River. This deposit is reached by five horizontal tunnels, which pierce the slope of the hill near its base at five difierent points, by means of which the quarried stone is conveyed to the kilns by cars. There is a marked difi'erence in the qualities of the stone in these several quarries, as well as among the several layers of the same quarry, and great care is exercised in distributing the aggregate yield of the entire deposit among the several kilns, in order to secure as great a degree of uniformity in the quality of the cement as possible. 69. None of the Lower Series of cement strata (see para- graph 44) are used by this company. The upper a j^q^^j. genes" layers, from ^^'umber One to l!^umber Three in- not used bj this elusive, are in some places too highly charged with carbonate of lime to admit of their entering into the combination. No attempt, however, is made (and it probably would not be advisable) to exclude any layer entirely, the skill and experience of the workmen being, in a great measure, depended upon to detect and throw out those portions of the stone which might injure the quality of the cement. These generally occur in patches, varying from a few inches to sev- eral feet in length and breadth, which are recognized by their coarse-grained or crystalline appearance, or some other charac- teristic feature. With the exception of these rejected portions, all the layers from Number One to Number Seven, inclusive, enter into the cement in the proportion of their thickness in the deposit. This company has a branch at Newark, New Jersey, to which place the stone is conveyed in the raw state. 60. The Lawrence Cement Comjpany^ manufacturing the " Hoffmann" brand, have their quarries and kilns above White- port, about seven miles back from Rondout. ^j^e Lawrence Their mill, driven by steam-power, is located on <^ement Company. 48 PRACTICAL TREATISE ON LIMES, the left bank of the Rondont Creek, about two and a half miles from its month, and below the slack water of the Dela- ware and Hudson Canal. They have twelve kilns of the old pattern (Figure 12), four run of stone two and a half feet in diameter, and two crackers. Their combination comprises stone from three quarries, as follows : the first, eighteen feet in thickness, comprising the layers fi )m Nine to Sixteen, inclusive ; the second, eight to ten feet in thickness, containing l^umber One to Four, inclusive, rejecting Number Three, separated from the first by the "Mid- dle Rock ;" and the third, ten to eleven feet in thickness, com- prising the same strata as the latter (One to Four, rejecting Number Three). After calcination, the stone is carried in wagons to the mill, four miles distant, and is then mixed together in the proportion of 13|- per cent of the first quarry (Numbers Nine to Sixteen), 26f " " " second quarry (Number One to Four, rejecting Number Three). 60 " " " third quarry ( " " " " " ). 61. The Wewark and Rosendale Company have all their works at Whiteport, six miles from Kondout, and about three miles from the point of delivery to boats below the locks of the canal. They have fifteen kilns of the old pattern (Figure 12), and one of Page's Patent (Figures 13 to 18). Their grinding apparatus comprises three crackers and four run of five feet stone, driven by steam, and one cracker The Newark , , i t . p and Eosendale and three run of lour and a halt leet stone, Company. driven by water. Their quarries are in the im- mediate vicinity of those belonging to the Lawrence Company, noticed above, and they make use of the same kind of stone, but combined in different proportions. They have, from time to time, derived their stone from eight different openings, but, at the present time, work three principally. Two of these are parallel to each other, comprising respectively the Upper and the Lower Series of layers, separated by the Middle Kock, HYDRAULIC CEMENTS, AND MORTARS. 49 which is worthless in this locality ; the third furnishes the Upper strata only, One to Four, inclusive. Their combination is as follows : 50 of the Upper Layers (One to Four) from two quarries, rejecting part of No. Three. 50 of the Lower Layers (Nine to Sixteen). 62. The Rosendale Cement Company^ manufacturing the Lawrence" brand, is located at LawTenceville, on the line of the Delaware and Hudson Canal, six and a half miles from Rondout. They have seven kilns of the old pattern (Fig. 12), and four run of stone, four feet nine inches in diameter. They grind by water power. The ^^^fntCompL,. Stone is procured from three quarries, as follows The^r^^ is near High Falls, two miles above Lawrenceville, and furnishes the Upper Layers (One to Four, inclusive), of which a large proportion of Number Three is rejected. This stone, after burning, is conveyed by land carriage to the mill at Lawrenceville. The second quarry is situated on the east side of Rondout Creek, at LawTenceville, and furnishes the Lower Layers (JSTine to Sixteen, inclusive). The third is about a quarter of a mile distant from the latter, on the west side of the creek, and contains the layers One to Four, inclusive, of which J^umber Three is rejected. This last- mentioned bed overlies in regular order the Middle and Lower Series. Numbers Nine to Sixteen were formerly quarried at this point, and included in the combination, but for some years past have been omitted, on account of the alleged presence of an excess of carbonate of lime, an objection which is presumed to be more imaginary than real, as the strata, having been treated separately with great care, gave results which com- pared favorably with those obtained from the corresponding layers on the opposite side of the creek. The stone from each quarry, after being burned separately, is added to the combination in grinding in the following pro- portions, viz. : 4 \ 50 PEACTICAL TREATISE ON LIMES, .20 of the first, One to Four, inclusive, rejecting most of No. Tliree. .60 " second, Nine to Sixteen, inclusive. .20 " third. One to Four, inclusive, rejecting No. Three. 63. Delafield & Baxter^ formerly Ogden & Delafield, are located at the High Falls of Eondout Creek, twelve miles Delafield & from its mouth, on the Delaware and Hudson Baxter. Canal. Their mill is driven by water-power, and consists of three crackers, and four run of four and a half feet stone. They have six kihis of the usual form (Fig. 12). Three quarries furnish the stone used in the combination. The first comprises the layers from Kine to Sixteen, inclusive, of which parts of Thirteen and Fifteen are too highly charged with carbonate of lime, and have to be rejected ; the second comprises the Upper Strata, One to Four, inclusive, of which portions of JS^umber Three are excluded. These two quarries are located near each other ; the third is about half a mile distant, and contains Number Sixteen only, which occurs in a partially disintegrated or slaty form, and is therefore known as the " Slate Quarry." In the combination, the products of these three quarries are mixed together in equal proportions, viz. : 33^ of Nine to Sixteen, inclusive, rejecting portions of Thirteen and Fifteen. 33^ of One to Four, " " No. Three. 33^ of No. Sixteen. Layer l^umber Sixteen in this locality possesses remarkably quick settino^ properties. It will harden under Layer Number ^ . if i . tt, Sixteen very water more rapidly than any cement in Ulster quick setting. County, and is added to the combination with a view simply to increase its hydraulic activity and energy. Delafield & Baxter are also the proprietors of the quarry w^hich some years ago furnished the O'Neill cement, an article which sustained a high reputation among military engineers. It comprises the middle layers Six and Seven. It is not worked at the present time, but will probably, at no distant period, have to replace their "Slate Quarry" in the combina- tion, as the latter is becoming exhausted. HYDRAULIC CEMENTS, AND MORTARS. 51 64. The Ogden Rosendale Cement Company is also lo- cated at High Falls, near Delafield & Baxter's. Their mill is driven by water-power of great capacity, and contains two crackers and four run of four and a half feet The Ogden Ro- stone ; their kilns, at present four in number, sendaie Cement are of the old pattern (Fig. 12). The stone is ^°°^P^°y- derived from an opening contiguous to Delafield & Baxter's " Slate quarry," and comprises the Lower Series of layers Kine to Sixteen, inclusive, rejecting IS'umber Fifteen on account of the large excess of carbonate of lime which it contains, and which places it among the intermediate limes. Layers Mne to Thirteen are subject to frequent and peculiar variations in hydraulic energy, containing in places so large an excess of caustic lime after calcination, as to render it necessary to reject these portions when detected. The combination adopted by this company is varied from time to time, as circumstances require, Number Sixteen being principally depended upon to compensate for any deficiency in hydraulic activity in the superincumbent layers. The usual proportion is : 50 of layers Nine to Fourteen, inclusive, rejecting parts of Nine and Thirteen. 50 No. Sixteen. The color is light, like that of Delafield & Baxter. Layer Number Sixteen of Ogden's quarry appears to possess all the distinct and characteristic properties of Delafield L^yer Number & Baxter's "Slate" quarry, that is, it has a Sixteen, slaty structure, burns light colored, and is remarkably quick setting under water. It is a noticeable fact, that, in this par- ticular spot, this stratum, although distant but 400 or 500 yards from the other quarries in the neighborhood, possesses local properties so peculiar, that it would be difficult, in the absence of the most direct and palpable evidence of their geo- logical identity, to believe them to be parts of the same layer. Tt is only at High Falls, and apparently within contracted limits even there — possibly not more than two to three hundred 52 PEACTICAL TEEATISE ON LIMES, yards in extent — that it possesses any superior hydraulic ac- tivity. As we descend the valley of the Rondout, it burns dark colored, and becomes comparatively slow setting. 65. At Bruceville, half to three-quarters of a mile below High Falls, Mr. iV^. Bruce manufactures cement from the Lower Layers, WmQ to Sixteen, inclusive, to which is added a stratum about eighteen inches thick, situated twelve feet below I^^umber Sixteen, and separated from it by a conformable bed of argillaceous shale. It is not certain whether this stratum forms a part of the cement bed as described, or is a separate and independent deposit, formed out of its usual position by the local intervention of the shale. This cement is light colored, like Delafield & Baxter's. Mr. Bruce also works the Lower Layers at the Green kilns, five miles from Rondout, near the line of the Delaware and Hudson Canal. 66. Martin (& Clearwater have their works on the line of the Delaware and Hudson Canal, seven and a half miles from Rondout. This mill, comprising four run of four feet eight inches stone, and the requisite number of crackers, is driven Martin & steam-power. They have six kilns of the old Clearwater's. pattern. (Figure 12). Their stone is derived from two parallel beds comprising the Upper and the Lower Series of strata respectively, separated by the Middle Rock, Numbers Five, Six, and Seven, which is here entirely unfit for cement. Their combination is as follows : •50 of the layers One to Four, inclusive ; rejecting portions of Three and Four. .50 " " Nine to Sixteen, inclusive. 67. The quarries of The Hudson River Cement Company are situated about one and a half miles from the Delaware and Hudson Canal, five miles from Rondout. Their mill, compris- ing four run of four and a half feet, and two run of two and a The Hudson ^^^^ ^^^^ stone, as well as their kilns, are in River Company. Jersey city. Their combination comprises equal proportions of the stone from the Upper and from the Lower Layers, including about one half of Number Five, and differs HYDEAULIC CEMENTS, AND MORTARS. 53 from all others into which the Lower Layers enter at all, in including the whole of [N'umber Three. It is therefore as follows : -50 of layers One to Four, inclusive, and one-half of Number Five. .50 ** Nine to Sixteen, inclusive. 68. Maguire^ Crane (& Co. have recently commenced manu- facturing cement near Martin & Clearwater. Their quarries join each other, and are, in every respect, alike Maguire, Crane in the character of the stone and the number and ^ thickness of the strata. Tlieir mill is driven by steam-power, and contains four run of four and a . half feet stone. Four cylindrical kilns of the old pattern (Figure 12) are used in burning the stone. 69. The Lawrenceville Cement Manufucturing Company is located at Lawrenceville. Their milling apparatus com- prises six run of four and a half feet stone, four of them driven by steam-power of ample capacity, and two by water- power, provided with the requisite number of The Lawrence- crackers. Their stone is derived principally from Y^^^® Cement ^ r J Manuiactunng the Lower Series of layers. A portion of JN'um- Company, ber Seven, which is divided into three layers possessing very different qualities, is also added to the combination. This quarry is but two or three hundred yards distant from the one worked by the Rosendale Cement Company, on the west side of the Rondout Creek, in which the Lower Layers have been regarded — with insufficient cause, it is thought — as too highly charged with carbonate of lime. 70. The Rosendale and Kingston Cement Company are located at Flatbush, on the right bank of the Hudson River, about three miles above Rondout. Their mill is worked by steam-power, and contains four run of four and a half feet stone. Their stone is burned in the old-fashioned kilns (Figure 12), and is derived in part from quarries situated about 300 yards from the mill, which furnish the layers Three and Four of the Upper Series, and ^N'ine to Sixteen, inclusive, of the 54 PEACTICAL TREATISE ON LIMES, The Rosendale I^ower Series ; and in part from an opeaing ip and Kingston Ce- the Lower Layers on the line of the Canal, neai ment Companj. -»t . d i mi • JVLartm de Clearwater s works, ihis stone is transported in the raw state to the kilns, which are located near the mill. Their combination is as follows : .33^ of layers Three and Four, at Flatbush. .33^ " Nine to Sixteen, inclusive, at Flatbush. .33^ " " from near Martin & Clearwater's, ten miles distant. 71. Hydraulic cement is manufactured on the Potomac River, which finds its way to an eastern market, via the Ches- apeake and Ohio Canal. There are three works, located respectively at Sheplierdstown, Ya., at Hancock, Md., and at Cumberland, Md. 72. The Shepherdstown Works comprise two run of four and a half French burr stones and the necessary crackers, driven by water-power, and three perpetual kilns of the form given in Figure 11. Cumberland coal is used for burning. The stone is derived from deposits which crop out in several places on the banks of the Potomac, near the mill. Though consider- . ^ , . ably tortuous and irre2:ular, their general posi- Cement Works at ^ ^ . . Shepherdstown, tion is nearly vertical. The stone is quarried from the top of the hill, is then passed into the kilns, situated on the slope below, and subsequently to flat- boats in the mill-race. These are then floated into the mill, and the burnt stone is discharged through hatchways up to the crackers. 73. The deposit is in two principal layers, one of which furnishes a quick^ and the other a slow set- iayefs%n?gM5° ting cement. The two are mixed together in and the other nearly equal proportions, a combination which shw settmg. j i r r ^ is believed to yield a better cement than either of the beds w^ould if used alone. 74. Besides the quarry from which the stone is at present derived, there are several outlying cement strata, or perhaps HYDEAULIC CEMENTS, AND MOETAllS. 55 other outcrops of the same strata, near bj, intermixed with layers of nearly pure limestone, which were added to the com- oination in former years ; but the extra expense arising from the necessity of quarrying out the common limestone in con nection with them, and the doubt as to their possessing any superior qualities, led to their final exclusion. It is impossible to estimate satisfactorily the extent and capacity of these quarries, and it is believed that no critical examination by experienced geologists has ever been made with that end in view. The peculiar position of the beds would lead to the inference that their development is not only very extensive, but practically available through its entire extent. (See Table l^o. lY., paragraph 226, for analysis.) 75. The Round Top Cement ^YoT'ks are located about three miles above Hancock, Md., on the Chesapeake and Ohio Canal. The mill, which stands on the tow-path between the Potomac River and the canal, comprises two run of four feet French burrs, driven by a forty-horse water-power, derived from the discharge of the water of the Cem^^t'm)rk8. canal into the river. The kilns resemble those at Shepherdstown (Figure 11), and Cumberland coal is used for burning. 76. The cement layers at this place crop out on the left bank of the Potomac, and have been cut off for the excavating of the canal. They are exceedingly crooked and Aggregate thick- tortuous, bending up and down, and doubling ^^^s of deposit, upon each other in a very complex manner. Their aggregate thickness is about 48 to 50 feet, comprising eleven distinct layers, each possessing marked and peculiar properties. — Commencing at the top : Number One^ 8 feet thick, is highly argillaceous, and is very hard and difficult to grind after calcination. It sets slowly, and will not bear immersion, unless first allowed to set in the air. Number Two, 4 feet thick, is mostly argillaceous slate, and 56 PEAOTICAL TKEATISE Olf LIMES, is rejected. Portions of good cement stone are sometimes found mixed with it. Number Three^ one foot thick, is a good cement when properly treated, and hardens readily under water. Nuinher Four^ 4 feet thick, is too calcareous to be used Characteristic cement alone. When suitably underhurnt features of the jt possesses a moderate decree of hydraulic activi- fieveral layers. . , , i -, t ty but IS rendered almost worthless, ii exposed to heat of sufficient intensity and duration to burn the other layers of the quarry properly. It is therefore rejected. Nmiiber Five, 5 feet thick, furnishes a remarkably quick cement, when the calcination is arrested at the point of complete expulsion of the carbonic acid gas. Beyond this point it will bear immersion in the state of paste, but does not harden so quickly as when in the condition of sub-carbonate. Number Six, one foot thick, is nearly pure carbonate of lime and is rejected. Numher Seven, 6 feet thick, burns dark colored, like the Rosendale cements, but is not a quick cement by itself. It is used in the combination. Numher Fight, 4 feet thick, resembles Seven, though superior to it. Numher Nine, 5 feet, contains an excess of carbonate of lime, and is, in fact, an energetic hydraulic lime. It is used in the combination. Number Ten, one and a half feet thick, is a slate. Rejected. Number Eleven, 11 feet thick, gives a quick and energetic cement, which hardens readily under water. It is depended upon, in a measure, to confer hydraulic activity on the combination, whenever from bad burning, carelessness in assorting the stone, or any other cause, there is deficiency in this particular. With the partial exception last mentioned, the layers that are used are combined together in the proportion of their developed thickness in the quarry. HTDEAULIO CEMENTS, AND MOETAES. 51 The Round Top quarries contain a very large amount of cement stone, so situated, on the slope of the river and canal, as to secure to the manufacturer every advantage which position can afford. (See Table lY., paragraph 226, for analysis.) 77. The CuinbeTland Cement WorTts are located at Cum- berland City, Md,, and comprise two run of French burrs, 4|- and 5 feet in diameter, respectively, driven by a 35- , • rri • •'•11 Cumberland norse-power engme. Ihis power is considered cement Works, sufficient to drive three run of stone. Three kilns, burning Cumberland coal, and resembling those used in Ulster Co., I^. Y., are in operation. 78. The cement stone is derived from two quarries, situated in close proximity to each other, on Will's Creek, near its junction with the Potomac. The principal bed is from 35 to 40 feet thick, of which the lower half furnishes a slow cement, that will not indurate under water unless first allowed to set in the air, and, even then, rather slowly. The upper half yields a cement that will bear immersion in the state of paste. Each of these two layers furnishes one-third of the combination, the remainder being derived from a nine-feet ledge a few yards distant, which is quarried by tunnelling. It is quick- setting. Below this there are other layers of good cement, which are not at present used on account of the extra expense of quarrying, and one or two thin beds of argillo-magnesian limestone, possessing the properties of intermediate limes. For analysis of Cumberland cement, see Table lY., paragraph 226. 79. The James River Cement Works are located at Balcony Falls, Rockbridge county, Ya., on the James River, and the James River and Kanawha Canal. The mill stands on the tow-path, and contains two crackers and four run of French burr-stones of medium size, driven by water-power derived from a dam across James River, erected by the Canal Company. The power is deemed sufficient to turn six run of stone. Six kilns, as represented in Figure cemenrworks. 11, are located at the mills The quarries, of 58 PRACTICAL TREATISE ON LIMES, which there are two opened in the same stratum, jire on the mar- gin of the river, about one mile above the mill, from which point the stone is transported to the kilns in boats, on the slack water of the dam. This deposit is generally known in Yirginia as the " Blue Ridge quarry." The writer visited these rocks in the summer of 1858, under orders from the Engineer Bureau of the War Department. The following is an extract from his report, rendered on the 31st of July of that year : The cement vein or stratum is twelve to thirteen feet thick, and dips to the northwest fifty-five degrees (55°). It crops out on the summit of an undulating table-land, or, perhaps, more properly, a ridge situated at the base of the mountain. The direction of the outcrop is nearly north- rorentd^e^ol ^ast and southwest. The upper ridge of the stratum changes its character very materially before it reaches the surface, gradually disappearing in a soft, porous yellow stone, which in turn runs into a hard clay, of various shades of yellow and light orange, and in various stages of decomposition. This becomes perceptibly softer as it approaches the surface ; the upper portion, to the depth of several feet, yielding readily to the pick and shovel. The entire bed is subdivided into layers, varying in thickness from one and a half to four feet." "The color of the raw stone is dark blue, its texture compact, grain moder- ately fine, and fracture slightly conchoidal." For the analy- sis, see Table lY., paragraph 226. The James Eiver Works, driven to their full capacity, will turn off 350 to 400 barrels of cement daily. It is sent to the eastern markets via the James River and Kanawha Canal, and James River. 80. At Utica^ Lasalle county, Illinois, cement is manufac- tured from a bed of stone seven feet thick, which crops out on the margin of Illinois River, just above the level of high water. . . TT^- It is burnt with bituminous coals in intermittent Cement at Utica, Lasalle county, kilns of about 200 barrels capacity. It is stated by one of the manufacturers that perpetual kilns HYDRAULIC CEMENTS, AND MOETAES. 59 would not discharge the burnt stone readily, on account of the thin slaty fragments into which it splits in quarrying. Two parties are engaged in its manufacture. One of them has eight kilns and three run of stone (two of four feet and one of four and a half feet diameter) ; the other has three kilns and one run of four feet stone. Steam-power is used for grinding. The full capacity of both works is stated at 700 to 800 barrels per day. (For analysis, see Table lY., paragi-aph 226.) 81. The SandusTcy Cement Works are in Yan Kensselaer town- ship, Ottawa county, Ohio, on the point of the peninsula oppo- site Put-in-Bay Island, and near Hat Island. The thickness of the cement deposit is not accurately known. It is nearly hori- zontal, and is quarried in three or four places to a depth vary- ing from five to eight feet, down to the level of the water of Lake Erie. The stone is burnt cemtnfwofm in perpetual kilns with coal, either bituminous or anthracite, in a manner similar in every respect to that pur- sued in Ulster county, New York. The mill is driven by steam-power, and comprises four run of French burrs with the requisite number of crackers, and is capable of grinding 300 barrels per day. (See Table lY., paragraph 226, for analysis.) 82. I^ear Louisville^ Kentucky^ at the foot of the falls of the Ohio River, there is a deposit of cement stone, which for many years has beei;i extensively used throughout the West, and particularly along the Mississippi River. The deposit is six feet thick j the stone is burnt Louisville, Ky. in the ordinary draw-kilns (Figure 12), anthra- cite coal being used for fuel. The mill contains one pair of four and a half feet French burrs, driven by water-power. As early as the year 1848, Col. Long, of the Corps of Topo- graphical Engineers, who had witnessed the successful appli- cation of the Louisville cement to building purposes in the West, entertained a very high opinion of its Long's quality, and pronounced it, when used " in the opinion of the , Louisville cement formation of subterraneous and submarine foun- 60 PEACTICAL TEEATISE ON LIMES, dations, and other structures in similar situations, a cement unsurpassed by any materials of the kind hitherto employed for such purposes in this or any other country." * * The cost of manufacturing cement varies, of course, among the different works, according to local circumstances, such as the kind of motive power used for milling, the proximity of the kilns to the quarries and to the mill, the dip of the strata, and the proportion of quarried stone not suitable for use, the character of the burnt stone with respect to hardness, &c., &c. The Rosendale cements, on account of the superior facilities, and the brisk com- petition among the manufacturers, are produced at less expense than any in the country. Great pains have been taken to obtain data for a correct estimate of this expense. The following table is based upon a work whose estimated capacity is 300 bar- rels per day, on the supposition that the kilns and mills are in such proximity that the transportation of the raw stone to the kilns, and of the manufactured product to the canal, can all be accomplished with five single teams. In some works it is considerably below this estimate. CURRENT ANNUAL EXPENSES OF A CEMENT MANUFACTORY OF 300 BARRELS DAILY CAPACITY, WORKING 200 DAYS IN THE YEAR: Salary of Superintendent $ 800 00 " " 1 Engineer 500.00 " " 1 Fireman $1.00 for 200 days 200.00 " " 1 Smith 1.25 " " " 250.00 " " 13 Quarrymen 1.00 " " " 2,600.00 " " 5 Single Teams 1.75 " " " 1,750.00 " " 1 Head Burner 2.00 " " " 400.00 « " 3 Assistant Burners . . 1.00 " " " 600-00 " " 4 Drawers 1 00 '* " " 800.00 " " 1 Miller 1.75 " " » 350.00 " " 1 Assistant Miller 1.25 " " " 250.00 » " 5 Packers 1.00 " " " 1,000.00 Powder for blasting 14,049 Tons of Stone 1,200.00 Coal for burning " " " 2,700.00 Coal for engine, $1.00 per day, 200 days 800.00 Paper and nails for packing, I^g. per barrel 900.00 Total Expenditure $15,100.00 Add 15 per cent, for incidental and contingent expenses, accidents, delays, wear and tear 2,235.00 Annual consumption of quarry, based on total consumption in 12 years 1,000.00 Interest on capital invested, $30,000 at 7 per cent 2,100.00 Insurance on building and machinery, $18,000 at 2 per cent 360.00 60,000 new barrels delivered at the works, at 28c 16,800.00 Total cost of 60,000 bbls. of cement, ready for delivery at the work. $37,595.00 Cost per barrel at the work, ready for delivery 62-]% HYDEAULIC CEMENTS, AND MORTARS. 61 83. At Kensington^ Conn.^ a cement has been manufactured for many years, which has never found a distant market in large quantities, owing to the expensive land transportation to which it would be subjected, and which pre- cludes its ever coming in competition with the Kenskigton Conn. Kosendale cements, for general use. A marked superiority for stucco-work in exposed positions is claimed for it by the proprietors, on the authority of the late A. J. Down- ing, Esq., who gave it a preference over all others for that par- ticular purpose. The mill is driven by water-power, and con- tains two run of four feet Esopus Stone (Shawangunk grit). The deposit of cement stone is about three miles from the mill. Its thickness varies from one to eight feet. 84. Cement manufactories also exist at Akron, Erie county, ^^ew York, at Lockport and Fayetteville, New York, and at other points on the line of the Erie Canal. The cements from Manlius and Chittenango, tori^s^at Ak^ou °* New York, rank in point of hydraulic activity ^^^j^J^^!;^^^^^^ Y between the genuine cements and the eminently hydraulic limes, some portions of the quarries partaking largely of the character of intermediate limes. These two last-named cements require to be used with great care. 85. Besides the foregoing cements, two well-known imported varieties have been introduced to a limited extent into these trials, viz. : the artificial Portland cement of England, and Parker's Koman cement. As these cements are both exten- sively used in Europe, and have been submit- ted to a great many trials, their character and PorTiandcementa value are well known among those who have given the subject attention. They therefore furnish us the means of comparing mortars made from our products with those in common use throughout Europe. In Europe, all natural cements are generally denominated Poman cements, to distinguish them from Portland cements, which are artificial combinations of limestone (usually chalk) and clay. 62 PEACTICAL TEEATISE ON LIMES, KOMAN CEMENT. 86. Tins cement is manufactured in both England and France^ by a process essentially similar to that pursued in making ce- ent in this country. It is derived from argillo-calcareous, kid- ney-shaped stones called " Septaria," belonging Source of Roman to the Kimmerido-e and London clay, g-enerally cement. ^ j ' » ./ gathered on the sea-shore after storms and high tides, though sometimes obtained by digging. The manufac- tured article usually takes its name from the locality which furnishes the stone, as " Boulogne" Roman cement, " Har- wich" or Sheppy" Roman cement. The several brands pos- sess almost identically the same composition. ( See Table lY., paragraph 226.) NATURAL PORTLAND CEMENT. 87. A cement is manufactured by MM. Demarle & Co., of Boulogne-sur-mer, from one of the layers of the Kimmeridge clay, situated about 160 feet below the strata Natural " Port- land" cement of in which the " Boulogne pebbles" or " Septaria" Boulogne-sur-mer. ^^.^ ^^^^^^^ rpj^^ ^^p^^-^ is argillo-calcareous, and is burned and ground up for cement in its natural state without the addition of lime, furnishing the so-called Natural " Portland" cement. It was exhibited in Paris at the Palais de rindustrie, in 1855, and a report thereon by M. Delesse, Engineer of Mines, sent to me by the manufacturers, has sup- plied the following particulars : No locality, except Boulogne, is known to furnish a soft de- posit that can be excavated with pick and shovel, possessing in suitable proportions all the ingredients of good cement. The calcareous clay which is used in making " Port- infTrior CrSa-^ land" cement is found in the Inferior Cretaceous ceousFormation. p^r^nation. Its paste is nearly homogeneous, and Percentage of contains from nineteen to twenty-five per cent, clay contained. ^^^^ rj.^^^ proportions of silica and alumina HYDEAULIO CEMENTS, AND MORTAES. 63 contained in the latter may vary, v^ithout any inconveniences resulting therefrom ; but it is important to avoid sand, as far as possible. Accordingly, those portions containing more than one-twentieth of sand are rejected. 88. It is known, that in order to obtain artificial "Portland'' cement, it is by no means necessary to use exclusively the ar- gillaceous mud deposited by certain rivers : the limestone may be mixed with either marls or clays, the only necessary condition being to secure a perfectly homogeneous mixture of carbonate of lime and clay, in the above-mentioned propor- tions. It is, moreover, indispensable that the mixture should be quite intimate, otherwise, even with the required propor- tions, it may fail to yield good " Portland" cement. For this reason, M. Dupont, the patentee, has adopted for grinding the original materials for the natural "Portland" , . . . Mills for grinding cement, horizontal mill-stones, similar to those the calcareous used for sjrindins: corn. Instead of using a great quantity of water, in order to separate the materials by levigation, as is practised in the English process, he adds only enough to form a plastic paste. Immediately after this paste has passed under the mill, it is shaped into small bricks, which are placed in the kiln as soon as they are properly dried. As above intimated, a most essential condition of the paste is that its composition should be quite homogeneous, otherwise the portions richest in silica would fuse and form a silicate, which could not enter into combination with water. 89. During the calcination, it is of the utmost importance to have the temperature sufficiently elevated. The ordinary temperature of lime-kilns would be far too low, for that would merely drive off the water and a high heat, carbonic acid. The materials must receive a producing incipi- ent vitrincation. white heat, whereby they can become slightly agglutinated. The state of incipient vitrification appears to be the proper limit of calcination. 90. Moreover, a high heat, however intense, is not ob- 64 PRACTICAL TREATISE ON LIMES, jectioiiable, as only those portioDs that would have injured the quality of the cement will become completely fused. This fusion will then afford the means of separating and excluding those parts which do not possess the proper composition, and are unfit for use. Assorting the After the calcination, a selection is neces- burnt clay. g^^^ . ^j^^ pulverulent and scorified portions of the mass are picked out and thrown away. 92. Properties. — When taken out of the kiln, it is in the shape of fragments warped and cracked by contraction, and of a gray and sliglitly greenish color. Its powder has a some- what paler shade. The weiglit of one cubic metre of loose powder is 1,270 kilograms (2,136 pounds to the Siogne^ '^^ Port- cLibic yard), which will sometimes reach 1,385 X?:" with kilograms (2,329 pounds per cubic yard). The that of artificial Boulogne " Portland" cement, therefore, has a "Portland." ^ . . i -r^ -,. -, -r. greater specific gravity than the English " Port- land," as that from ^Newcastle weighs only 916 kilograms to the cubic metre, and that from London 1,057 kilograms (1,541 and 1,778 pounds per cubic yard, respectively). During the mixing with water in forming paste, the Boulogne " Portland" undergoes a diminution in volume of .3, the same as the Bou- logne "Boman" made from " Septaria." The volume of water which combines with it in mixing is .366, according to M. Dupont. In weight, 1.00 of " Portland" cement, therefore, absorbs .29 of water, which shows that, for an The Boulogne . i t-» i t~» i m "Portland" ab- equal weight, the Boulogne " Portland cement thanVrBouTogne i-^quires far less water than the Boulogne "Roman." It is " Roman" cement. This difierence is doubt- slower setting. - ^ 11.1 1 ' 1 ^ less due to the high temperature at which the " Portland" cement is burnt. The same cause also explains its slow setting, which does not take place until after twelve, or even eighteen hours. 93. This property of setting slowly may be an obstacle to the use of the Boulogne "Portland" cement for hydraulic works HYDRAULIC CEMENTS, AND MORTARS. 65 which have to contend against immediate causes Slow-setting oe- . ments objection- 01 destruction, as, for instance, sea construe- able, under some tions which have to be executed under water ^^^^cumstances. between tides. It is, however, possible, in the last-mentioned case, to obviate this inconvenience by temporarily covering the *' Portland" with a quick-setting cement. " Moreover, a quick-setting cement is always difficult to be used ; it often requires special workmen, and, at Advantageous im- all events, a very active supervision. A slow- others, setting cement, like the natural "Portland" of Boulogne, pos- sesses the great advantage of being manageable by ordinary masons, and can be mixed up with additional water after twelve, or even twenty-four hours. 94. M. Delesse, in the report which furnished the foregoing details, remarks : " We have made, in the laboratory, some gangs with Boulogne 'Portland' cement. The sample upon which we operated, and the composition of which we give be- low, was in fragments, and the gangs were made directly after the cement had been ground. After a few days, they displayed cracks showing contraction. As the cement exhibited at the Palais de I'Industrie showed no cracks, these were probably due to the fact that the cement experimented upon was fresh from the kiln, whereas ground cement, after being stored for some time, becomes more or less hydrated, and is less liable to con- traction. We observed, moreover, that the water in which the gangs were immersed was impregnated with a considerable quantity of lime. In the natural ' Portland' the lime is there- fore in excess, and the whole of it does not enter into combi- nation to form hydrosilicate. 95. "The composition of the natural Boulogne * Portland' cement is as follows : "Lime 65.13 Magnesia 58 Analysis of the nat- Silica 20.42 ural Boulogne "Port- Alumina and small quantity of oxide ) -lo oh land" cement. of iron f ^^-^^ Sulphate of lime a trace." 5 66 PRACTICAL TREATISE ON LIMES, In analyzing the same cement, M. Yicat found only 61.75 of lime. This composition comes very near that of the Eng- lish artificial " Portland," which is given in paragraph 131. They are both classed among the intermediate limes of Vicat. The calcination of these cements, at a temperature producing vitrification, develops a peculiar state of combination of the ingredients, which confers upon them their remarkable proper- ties. HYDRAULIC CEMENTS, AND MORTAES. 67 CHAPTEE lY. 96. The calcination of statuary marble, or any other pnre variety of limestone, produces quicklime, by expelling from the carbonate of lime (CaO.OOg), of which they Lime a metallic . oxide, and how are essentially composed, the carbonic acid gas, produced. (CO2), water of crystallization, and organic coloring matter. Lime is therefore a j)rotoxide of calcium, or, in other words, a metallic oxide, the base, calcium, having been classed, since Sir H. Davy succeeded in effecting the decomposition of lime^ among the metals. Pure lime (CaO) has a specific gravity of 2.3, is amorphous, somewhat sponffy, hierhlv ' . . . ^ ' , I J Its characteristics, caustic, quite infusible, possesses great avidity for water, and, if brought in contact with it, will rapidly absorb .22 to .23 of its weight, passing into the condition of hydrate of lime, a chemical compound, of which the formula is CaO.HO. The reactions resulting from this Phenomena de- , . . T T . 1 . 11 veloped in combination are attended with certain marked "slaking." phenomena, such as a great elevation of temperature, the bursting of the lime into pieces with a hissing and craclcling noise, the evolution of a hot and slightly caustic vapor, and finally, after a few minutes, its reduction into an impalpable powder, of which the volume is about three and a half times that of the original lime. In this condition the lime is said to be slaked. 97. Water dissolves, according to Sir H. Davy, about one four-hundredth of its weight of lime, or, according to Thomson, 68 PEACTICAL TEEATISE ON LIMES, one seven hundred and fifty-eighth, while Dalton states it to be, Solubility of lime ^^^^^ hundred and seventy- in water. eighth, and, at 212°, one twelve hundred and seventieth. The solutions, commonly called lime-water, are valuable re-agents and antacids. Lime being more soluble in cold than in hot water, its solution becomes turbid when boiled. A similar result is produced by breathing into a solu- tion through a tube, owing to the carbonate of lime formed by respiration, which, however, is dissolved by an excess of car- bonic acid gas. A paste of the slaked lime is therefore a mix- ture of the hydrate of lime and lime-water. It will remain in a soft condition for an indefinite period, if kept in a damp place, excluded from direct contact with the atmosphere. 98. Lime, on account of its great afiinity for It absorbs moist- . ^ . • /. , . . , ure and carbonic moisture, and, when moist, lor carbonic acid, acid from the air. absorbs them gradually from the atmosphere, returning to the state of carbonate of lime, with an excess of hydrated base (CaO.COa -f- CaO.HO). To protect it against the efiects of these deteriorating agents, it is necessary to pre- serve it in close vessels. 99. Lime may be distinguished by its dilute solution giving a white precipitate of oxalate of lime, when a Test for lime. ... ... solution of oxalic acid is added to it, which is not redissolved by an excess of oxalic acid ; and by not yielding a precipitate with sulphuric acid and sulphate of soda. 100. The purest minerals of the calcareous class are the rhombohedral prisms of calcareous spar, the transparent double The purest calca- refracting Iceland, spar, and white or statuary reous minerals. marble. They are entirely dissolved in dilute hydrochloric acid, with a brisk effervescence, due to the escape of carbonic acid gas, and contain, according to an analysis of a specimen of white marble by General Treussart, about .33 parts of carbonic acid, .64 of lime, .03 of water. In pure carbonate of lime the lime amounts to .56 of the whole. 101. The limestones which furnish the limes of commerce are HYDRAULIC CEMENTS, AND MOETARS. 69 eeldom if ever pure, but usually contain, besides the carbonate of lime and the water of crystallization, vari- Limestones are able proportions, seldom exceeding .10 in the P^^®- aggregate, of some if not all of the following impurities, viz.: silica, alumina, magnesia, oxide of iron and oxide of manganese, and sometimes traces of the alkalies, the presence of which modifies to a greater or less degree the phenom- phenomena devel- ena developed during the process of slaking, as °P®^ slakmg. noticed in paragraph 96, and renders necessary certain precau- tions in their manipulation and treatment, when employed, for the purposes of construction, as mortars. 102. The striking and characteristic property of hardening under water, or when excluded from the air, conferred upon a paste of lime by these foreign substances, when their aggregate amount exceeds .10 of the whole, furnishes the basis for a gen- eral arrangement of all natural or artificial products suitable for mortars, into five distinct classes, as follows: 1st. The common or fat limes. Their classifica- tion as sources of 2d. The poor or meagre limes. mortar. 3d. The hydraulic limes. 4th. The hydraulic cements. 5th. The natural pozzuolanas, including pozzuolana, properly so called, trass or terras, the arenes, ochreous earths, schists, grau- wacke and basaltic sands, and a variety of similar substances. 103. Tlie common^ fat, or rich limes usually contain less than 10 per cent, of the impurities mentioned A t r.H T 1 r. 1 1 • Common lime, m paragraph 101. in the process oi slakmg to a paste, their volume is augmented to from two to three and a half times that of the original mass, accom- panied by a hissing noise, an elevation of tem- ^o'umTiTskki^^^ perature, and the rapid and progressive reduc- tion of the lime to powder, and finally, if sufficient water be added, to a homogeneous and consistent paste. With the ex- ception of a portion of the foreign substances mentioned, it is soluble to the last degree in water frequently changed. If 70 PBAOTICAL TREATISE ON LIMES made into a stiff paste, it will not harden under water, or evim , .„ , in damp localities excluded from contact with The paste will not ^ ^ harden under the air, or under the exhausted receiver of an air-pump. In the air, it hardens by the gradual formation of carbonate of lime, due to the absorption of car- bonic acid gas, aided by the deposition of crystals of hydrate Theory of its in- ^f lime from the lime-water of mixture, during duration in the air. ^he process of desiccation. ■ 104. The pastes of fat lime shrink in hardening to such a deerree that they cannot be employed as mor- CJse of sand. ^ . . ^ ^ '^^^ tar without a large dose of sand. When used alone, they are unsuitable for masonry under water, or for Lime mortars un- foundations in damp soils ; but in other situa- suitabie for sub- tions, have an extensive application, possessing, aqueous works ; . . , , , as they do, great advantages over the other limes on the score of economy, on account of the large aug- much used under nientation of their volume in slaking, their ex- other circum- tensive distribution over the surface of the globe, and the simplicity of their process of manufacture. Paste of fat lime may be added to a cement mortar, in quantities equal to that of the cement, without ma- terial diminution of strength. 105. The poor or meagre limes generally contain silica (in the shape of sand), alumina, magnesia, oxide limes ^^^^^^ of iron, sometimes oxide of manganese, and in most cases traces of the alkalies, in relative proportions which vary very considerably in different locali- Amountofimpu- ^lieir aggregate amount is seldom less rities which they than .10 or greater than .25, although, in contain. ... , , . i some varieties, it reaches as high as .35, and even, though rarely, .39 of the whole. In slaking they proceed sluggishly, as compared with the rich limes, and sel- dom produce a homogeneous and impalpable powder. They Phenomena de- exhibit a more moderate elevation of tempera- veloped in slaking, ture, evolve less hot vapor, and are accorapa- HYDEAULIC CEMENTS, AND MOETAES. 7l nied by a much smaller increase of volume than the rich limes. Like the latter, they dissolve in water frequently renewed, though more sparingly, owing to the presence of a larger amount of impurities, and like them will not harden, if placed in the state of paste, under water or in wet soil, or if excluded from contact with the atmosphere, or carbonic acid gas. They should be employed for mortar, only when it is impossible to procure common or hydraulic lime, or cement, : , . , . . -, T .p Not to be used in which case it is recommended, ii practicable, for mortars, ex- to reduce them to powder by grinding. As a cautions.^'' fertilizer, they have an extensive application. 106. A very large proportion, frequently .90 of the silica, con- tained in meagre limes, is in the state of inert ^^^^ ^.^.^^ grains of sand, which accounts for the frequent meagre limes, absence of those peculiar properties of hardening or setting" under water, which would place them in one of the classes of hydraulic limes, were the silica present, or a suitable propor- tion of it, in a more appropriate form. 107. The hydraulic limes, including the three subdivisions of " limes slightly hydraulic,^' " hydraulic Hy^^auiic limes. limes,^^ and " limes eminently hydraulic^^ sel- Three classes, dom contain an aggregate of silica, alumina, magnesia, oxide of iron, &c., exceeding .35 of the whole. The proportion in the first class ranges generally between .10 and .20 of the whole ; in the second class, between .17 and .24 ; ^1^0^^^ of impu- while the eminently hydraulic limes contain rities which they rarely less than .20, or more than .35 They all slake under proper treatment, though more slowly than the meagre limes, with but a slight elevation of temperature, the disengagement of little or no vapor, and but pj^enomena de- a small augmentation of volume, rarely ex- veloped in slak- ing. ceeding .30 of the original, — their appearance presenting in this respect a striking contrast with the phe- nomena exhibited during the slaking of rich limes. If mixed into a stiff paste, after being slaked, they possess 72 PRACTICAL TREATISE ON LIMES, Their paste will valuable property of hardening under water, harden under in periods varying from fifteen to twenty days water. after immersion, if " slightly hydraulic six tc eight days, if " hydraulic ;" and one to four days, if " eminently hydraulic." As a general fact, these limes undergo, in slaking, an increase of volume, inversely proportional to their hydrau- lic energy and quickness. 108. The hydraulic limes, in their chemical composition, as well as in those qualities which confer value in ^een^loSo^ their application to the purposes of construc- Uc^ceme their geological position, occupy an intermediate place between the common or fat limes and the hydraulic cements. They are consequently found in the United States in numerous and extensive deposits ; but as they possess no valuable property not present in a pre-emi- Found extensive- degree in those limestones which furnish ly in the United hydraulic cement, it has not been found neces- States, but not *^ , ' , manufactured for sary, and certainly it would not be remunera- live, to engage in any extensive manufacture of them for the trade. 109. The JiydrauliG cements contain a larger amount of silica, alumina, magnesia, &c., than any of the preceding va- HydrauUc ce- rieties of lime, though the amount rarely, if ment. ever, exceeds .61 of the whole. They do not , , slake at all after calcination, differinsr materi- Will not slake. . ' 5 ally in this particular from the limes proper. Water does not pulverized, they can be formed into a paste cause increase of with water, without any sensible increase of volume, and with little, if any disengagement of heat, except in certain instances among those varieties which contain the maximum amount of lime, or border on the " in- termediate limes." They are greatly superior to the best " emi- nently hydraulic limes," for all the purposes A paste will har- . . . den quickly under of hydraulic construction ; some of them being 60 energetic as to set" under water at 65° F., HYDRAULIC CEMENTS, AND MORTARS. 73 ill three or four minutes, although others require as many hours. They do not shrink in hardening like the JT.ri^'td " paste of fat lime, and therefore make an excel- ^ "^^^ ^ . . out sand. lent mortar without any addition of sand ; al- though, for the sake of economy, sand, and frequently both sand and lime, are combined with them. In the United States, they are almost exclusively depended upon for hydraulic mortar. 110. Lying between the two preceding classes in the amount of foreign substances which they contain, and possessing such characteristic features as to entitle it, perhaps, to a separate notice, if not a separate classification, there is a class of com- pound limestone prominently developed in the ^ , ^ ^ Intermediate. argillo-magnesian deposits of this country, pos- limes of the Uni- 1 T T n ii 1 • ted States, sessmg m a very marked degree ail the objec- tionable properties of the argillaceous intermediate limes {chaux limites\ noticed by M. Yicat. "When completely calcined, they set rapidly, both in the air and in water ; but in the latter case are soon thrown down by the slaking of the Their charactoris- meagre caustic lime, which they contain in ex- feairures. cess. This result is brought about either by the appearance, soon after submersion, of a fine network of cracks, all over the surface of the mortar, which gradually pene- T . . , 1 -, . f -, Action of their trate into the interior until the whole is reduced paste under to a granulated or lumpy paste, possessing no cohesion, or, by the progressive softening of the whole mass, to a fine and homogeneous pulp, frequently accompanied in either case with a considerable enlargement of volume. If, after the action of the water has commenced, as indicated either by the appearance of cracks, or by a general softening upon the surface, the paste be again worked up with the trowel, dried off with bibulous paper, formed ^ , ' r JT 7 Destruction of into a stiff cake and immersed, the same phe- hydraulic energy nomena, though in a more moderate form, will frequently exhibit themselves again, and with some varieties, PEAOTICAL TEHATISE ON LIMES, will not entirely disappear, until four or five repetitions of this process. This is particularly the case with some of the layers in Ulster county, N^. Y. In all cases, however, whether one or several remixings suffice, the hydraulic energy is so far im- paired that the substance cannot assume a higher rank than hydraulic lime, requiring from three to ten days to. harden sufficiently to support the 2V inch wire loaded to one pound. When considerably underburnt, these limestones yield a good cement. They ought not, under any circum- Not to be used for 1 • i i mortar, except stance, to be introduced, even m a small pro- caution ^^^"^ P^^i'tion, into any combination which is intend- ed to be kept up to the standard of good ce- ment, without being subjected to a calcination by themselves ; and even then it will be found extremely difficult, if not prac- tically impossible, to so regulate the heat that all the stone shall be suitably underburnt. 111. The natural pozzuolanas comprise pozzuolana properly Natural pozzuo- so-called, trass or terras, the arenes, some of lanas. the ochreous earths, and the sand of certain grauwackes, psammites, granites, schists, and basalts. Their Principal ingredi- principal ingredients are silica and alumina, ents thereof. with a large preponderance of the former. Most varieties contain small quantities of soda, potash, ox- ides of iron and manganese, and not unfrequently magnesia. None of them contain more than .10 of lime, when pulverized When finely pulverized without previous cal- and mixed with cination, and combined with the paste of fat lime in suitable proportions, to supply their deficiency in that ingredient, they possess hydraulic energy to a degree that will compare favorably, in some of the varieties, with that of the " eminently hydraulic limes." Those de- . ^. . rived from the disinteo^ration of ^rauwacke, Some varieties im- o ° ' proved by calci- psammite, granite, and the other rocks men- tioned, are the least energetic of the class, and are somewhat improved by a slight calcination. HYDEAULIC CEMENTS, AND MORTAES. 75 112. Pozziwlana^ which confers the name upon this class of substances, is of volcanic origin, and has therefore been sub- jected to the action of heat, whereby its constituent elements have experienced a chemical change in their primitive mode of combination. It w^as originally discovered at the foot of Mount Yesuvius, near the village of origin. ' Pozzuoles, whence its name, although it is com- mon to all localities that have been exposed to igneous agency, being found sometimes upon the surface of the earth, though most generally in beds, which frequently extend to considerable depths. It is extensively disseminated through- out Europe, and large quantities for building f^^rope'''''^^^^ purposes, have been derived from the vicinity of Rome and Civita Yecchia, in Italy, and from the Puy-de- Dome, Upper Yienne, Upper Loire, Cantal and ' . V -r^ T . 1 . T . r.. .1 Localities. Yivarais, m France. It is also found m Sicily, in the Isle of France, and in Guadaloupe and Martinique. It sometimes exists in a coherent form, but more frequently is either pulverulent or in coarse grains, sharp, angular, and rude 10 the touch. Its prevailing color is brown, ^ ^ with many exceptional shades of red, violet, gray, and yellow, and oftentimes approaching white and black. It is hipjhly magnetic, parts with about .09 of , . . . T , . T Properties, water by calcination, is entirely solvent m sul- phuric acid, and in concentrated hydrochloric acid at the boil- ing point. As might be inferred, from the character of the agencies v/hich produce pozzuolana, its hydraulic properties differ very much in different localities. Its value for the purposes of construction in combination with rich lime, has been known for many centuries, and Yitru- vius and Pliny both speak of its admirable properties, as exhi- bited in the marine constructions of the Pomans, extant in their day. In using pozzuolana, it is '^^^ customary after pulverizing it, to add sand as well as lime ; the relative proportion of the three ingredients 76 PEACTICAL TREATISE ON LIMES, depending on the kind of sand employed, and the character of the lime and pozzuolana. For the Italian pozzuolana, there ia perhaps no better combination than that recommended by Yitruvius himself, which has been followed, with slight varia- tions, very generally throughout Italy, and at Toulon, and other ancient ports on the French coast. It is as follows, viz. : 12 parts of pozzuolana well pulverized, 6 " " quartzose sand well washed, 9 " " rich lime recently slaked ; to which is added 6 " " fragments of broken stone, porous and angular, when it is intended for a pise or a filling in. , , The pozzuolanas of this country, if any exist. Not known to be ^ ^ j.jj native to the have never been used in constructions, and have United States. • t • i i never been examined with that view. 113. Trass or terras. — In the valley of the Rhine between Mayence and Cologne, and in various localities in Holland, a substance of volcanic origin is found, called Trass or Terras, ^ which has been extensively employed through- out that region, particularly by the Dutch engi- neers, for the production of hydraulic mortar. It is derived from immense pits or quarries, occupying the Its sources. ^« . i j • • i Sites 01 extmct volcanoes, and enjoys m nearly every particular the distinguishing properties of Italian poz- zuolana, closely resembling it in its composition, zuda^a^^and^^s' details of its manipulation, requiring used m the same pulverized and combined with rich lime, manner. ^ ' in order to render it fit for use, and to develop any of its hydraulic properties. 114. The trass used in Holland is obtained principally from Bonn, Andernach, and from the village of Dor- Dutch*trass^ dreck, exclusively devoted to its production, and at the confluence of the Rhine and the Meuse. 115. Trass is of a grayish color, has an earthy appearance, and is found in beds that are sometimes co- herent, though usually composed of a bete- HYDRAULIC CEMENTS, AND MOETARS. 77 rogeneoiis mass of pulverulent lumps, from the size of a small pea to that of an egg. Sulphuric, and even concentrated hydrochloric acid, attacks it -^^^^P®^^®^- with readiness, leaving a residue of insoluble silica. Smeaton regarded it as inferior to the Italian pozzuolana in some essen- tial particulars, and mentions, as one of its objectionable fea- tures, that of throwing out unsightly efflorescences upon the faces of walls in which it is used, which attain such a degree of hardness, as to render their removal with instruments necessary, specially in positions where smoothness and regularity of sur- face are essential, as in water conduits, navigable sluices, &c. More recent experiments have led to the suspicion that Smea- ton either made use of a lime ill adapted to the purpose, or what is perhaps more probable, that he unduly augmented its propor tion, which should rarely exceed the ratio of one to one. 116. Arenes is the name given to a species of ochreous sand, claimed by some to be of fossil orisfin, and Arenes. found abundantly in France, in the Depart- ment of Dordogne, and in several localities on the tributaries of the Loire and the Somme. On account of the large pro- portion of clay which many of them contain, which often reaches as high as .70, they can be ^[thouf i^e!^ formed into a paste with water, without any addition of lime, and are often used in that state for the walls of buildings constructed en pise^ as well as for mortar. Mingled with rich lime, they give apparently excellent mortars, which attain great hardness under water ; and, in hydraulic quickness, compare favorably with the most ener- getic hydraulic limes. 117. It is doubtful, from some careful experiments that have been made, whether their properties, as regards the ulti- mate strength and hardness of the mortars • ^ . ^ ^ ^ Their hydraulic made from them, are improved by calcination, activity increased or otherwise. Their hydraulic quickness, how- burning, ever, is greatly increased thereby. Their colors are various, such 78 PEACTICAL TREATISE ON LIMES, as red, brown, yellow, and sometimes white. They contain from .10 to .70 of clay, the balance beinff a Oompositiou. mixture oi coarse and nne calcareo-siiicious sand ; and have hitherto been principally found upon the sum- mits of small hills, or forming the superior strata of plateaux bordering water-courses, but rarely in the valleys. These beds exhibit the characteristic physical features of alluvial deposits, and are probably accretions of diluvial or tertiary earths, transported from a distance. This conclusion excludes the idea that they have been subjected to the action of vol- canic heat, and leaves us to account by some other hypothesis for their hydraulic properties, and their close resemblance, in other respects, to the Italian pozzuolana. The most reason- able supposition is that they owe their hydraulic energy, when mixed with the paste of fat lime, to the presence of silica, not in the state of quartz, but in a form favorable SethydSdty^^ free combination with the lime, in the production of an insoluble silicate. To account for the hydraulic energy in crude arenes requires a more lengthy discussion of certain chemical reactions, than can with propriety be introduced here. It will therefore be deferred to the chapter containing the " theory of the subaqueous induration." 118. When the arenes were first discovered, great attention was paid to their examination, and with such favorable results at the outset, that they immediately took rank among the most valuable sources of hydraulic mortar. Subsequent experi- ments, however, have not fully realized the high expectations originally entertained with regard to them, or verified their claims to any superiority in initial energy over the pozzuolana and trass ; while the efiects of time upon the mortars composed of them, have established the fact that, with few exceptions, they should be classed among the most feeble pozzuolanas, that they contain ingredients which exercise a hurtful influence upon mortars in the air, and that immersed in water, they at tain but a medium degree of ultimate hardness. HTDEATTLIC CEMENTS, AND MOETAES. 79 119. Properties similar to those possessed by Llie arenes have been discovered in grauwacke, psammite, granite, scliist, basalt, and other rocks, when in a state of disintegra- tion. They must, however, be considered as natural -J ' ' pozzuolanas. verj feeble pozzuolanas, in the crude state, and acquire but a slight increase of hydraulic energy by any degree of calcination. Even their feeble powers, however, confer upon them this advantage, that, for mortars not absolutely immersed in water, when green, and when there is ample time for their properties to develop themselves before submersion, they can be employed in larger proportions than any species of sand, wholly inert, would admit of. 120. It may be said that a mortar has set^ when it has at- tained such a degree of induration, that its form cannot be altered without causing a fracture, that is, when it has entirely lost its plasticity. As the rmortlTdefined precise moment when this takes place is some- what difficult to ascertain in practice, it is important that some more rigorous standard of comparison should be established. The common method is to make use of an iron or steel wire point loaded to a given wsight ; and the mor- tar is assmned to have set, when it has become Si^tfmeo^setting. sufficiently stiiF and firm to support the point without depression. 121. Some cements are remarkably quick in exhibiting their hydraulic property, and will lose their plastic state immersed in water at 65° F. in one or two minutes, but afterwards pro- ceed very sluggishly in their induration. These, therefore, Betting aside the question of their value in other respects, are admirably adapted to constructions under water, or in positions subjected to immediate submersion. There are others, again, which, though comparatively slow in developing the first in- dications of hydraulic energy, yet in a few hours, greatly sur- pass the former in withstanding the wire test, as well as in their ultimate strength and hardness, and are therefore to be 80 PEACTICAL TREATISE OlS LIMES, preferred in all positions where a very quick induration is not ^ T ^- specially important. The former are remark- " Hydraulic activ- ^ ^ i ity" and " hydrau- able for what we propose to term hydraulic lie GDcrsrv," . . quickness or activity ; the latter, for hydraulic energy or power. In order that we may be able to detect and recognize these somewhat obscure properties, it is necessary to have at least two testing wires, which differ either in their size, or weight, or in both. General Totten, for his experiments, carried on at Fort Adams, H. I., during several years prior to 1830, used a j\ inch wire, loaded to weigh J of a pound, and a »V inch wire, loaded to weisrh one pound. We Testing wires. f* ^ ' . -n , . . have used the same m ail our tests, makmg in every instance two cakes of the mortar under consideration, by forming them in a circular mould or ring inch in diameter, and |- inch deep. As soon as these cakes are prepared, whicli is done by pressing the mortar into the ring with a spatula, and smoothing off the upper surface, one of them is immersed immediately in water of an established temperature (65^ F.), and the periods of time which it requires to be able to bear respect- ively the inch wire, weighing J of a pound, and the ^\ inch wire, weighing one pound, are accurately noted by the watch. The other cake is left in the air (also brought to 65^ F.), until it supports the ii^ch wire, and is then immersed in water, and the time required to bear the small wire and heavy weight ascertained. 122. The wire test of hydraulic activity, when applied to cement paste without sand, does not furnish Wire test of pure . . , . . ^ , , . oement paste not even an approximate indication of the relative reliable. value of mortars of the same cements when mixed with a full dose of sand ; for a quick cement might contain one-half or three-fourths of its volume of inert matter ground up with it, and consequently be incapable ol Roasonswhy. ^ , , ' -, -, .-n , . receivmg much sand, and still be superior in hydraulic activity to another, although the latter might bo entirely unadulterated and its capacity for sand unimpaired. HYDRAULIC CEMENTS, AND MOETARS. 81 In pronouncing on the value of cements, from a comparison of their relative hydraulic activity, they should, therefore, be mixed with two and a half to three ^| to^brused. times their volume of sand. Even with this pre- caution, the result is far less reliable than some simple device for trying the strength of the mortars, when ten or twelve days old. As an evidence of the truth of this remark, it may be stated that, although eminent hydraulic activity or quick- ness is not necessarily accompanied by inferior hardness and strength, and conversely, neither is a slow setting cement necessarily a strong one ; still, within the range of the experi- ments which furnish the tables of this work, it is somewhat remarkable that the quickest cements gave the worst results, and the slowest ones the best. 123. The efiects of a variation of temperature upon the hydraulic quickness of mortars, whether derived from hydraulic lime, hydraulic cement, a mixture of common lime and pozzu- olana, or produced by artificial means is very ^^^^^ change marked; so much so indeed, that in all compar- of temperature on hydraulic activity. ative tests of this kind, it is important to adopt some fixed standard of temperature, not only for the water with which the cement is mixed, as well as that in which the cement is immersed, but for the dry ingredients and the surrounding atmosphere. To illustrate the necessity for these precautions, we will in- stance two kinds of United States cements. With the dry cement and water for mixing at 90°F., one of these cements immersed in the state of paste in water at 90° F., supported the yV i^ich wire loaded to J of a pound in 1^ minutes. The other one required 4 minutes to attain the same set. , . , ^ Examples cited. Lowering the temperatures to 65^, the former required 6 minutes, and the latter, 17 minutes ; while at 35*^,. the respective periods were lengthened to 39 and 82 minutes^ showing for a depression of 55^ in the temperature of the" paste (viz. : from 90^^ to 35*^), a corresponding prolongation of the 6 82 PRACTICAL TREATISE ON LIMES, period required to set, amounting in the one case, to 37^ minutes, and in the other, to one hour and 18 minutes. Hence, all cements are not equally sensitive to a variation of temperature ; also, those varieties which contain an excess Deduct'ons ^ caustic lime may exhibit a superior degree of hydraulic activity^ due to the heat generated in bringing this lime to the state of hydrate. 124. The diagram (Figure 8) is intended to show the effect of a variation of temperature upon the time of setting of cements formed into cakes or cyh'nders of stifi paste, as de- scribed, paragraph 121, immersed in that condition in water. The curves are constracted with abscissas, which Sa^r^*^^^ represent the temperature of the air, water, and dry cement (these being varied equally and kept together in all cases), and with ordinates, which repre- sent the times of setting, in minutes, that is, the period of time which elapses before the immersed paste can support the loaded wire point without depression. The dotted curves refer to tests with yV inch wire, loaded to | pound, and the full curves to the 2V i^^ch wire, loaded to one pound. OBSERVATIONS ON THE DIAGRAM, FiG. 8. Ko. 1 is from the Round Top Cement Works, on the Poto- mac River, near Hancock, Md. (See paragraph 75.) This is a very quick setting cement, whether left in the air, or im- mersed in water. For masonry, or concrete work in running water, when it is necessary to carry on operations in cold weather, the dotted curve indicates that no cement in the country is superior to it in rapidity of first induration. It sus- tains a change of temperature better than any cement tried, except Ko. 3. No. 2 is from the James River Works, at Balcony Falls, Rock- bridge Co., Ya. For all temperatures above 55°, this cement exceeds in hydraulic activity, all the specimens submitted to trial ; while below 48° it is surpassed by only two, the Round HYDEAULIC CEMENTS, AND MORTARS. 83 Top and the Cumberland (No. 3). At all temperatures it sets in the water almost as quickly as it will in the air. (See para- graph 79.) 90" 85° 80° 75" 70" 65° 60" 55 50" 45° 40° SI Temperature of water, dry cement, and »ir. Fig. 8. 84 PRACTICAL TREATISE 01^ LIMES, 'No. 3 is from the Cumberland cement. (See paragraph 77.) It is less sensitive to a depression of temperature than any ex- hibited in the diagram. No. 4 belongs to the ITewark and Rosendale brand, from Ulster Co., N. Y., and is a fair type of the dark-colored Rosen- dale cements. (See paragraph 61.) No. 5 is a light-colored Rosendale cement, manufactured at High Falls by Messrs. Delatield & Baxter. (See paragraph 63.) By examining the above-mentioned curves, a marked differ- ence is observed between No. 1, No. 2, and No. 3, as compared with No. 4 and No. 5. At high temperatures, they all begin to harden under water with nearly equal promptness, requirin g less than five minutes to bear the light testing wire ; while at two degrees above the freezing point, the James and Potomac River cements set in periods varying from twenty-seven to thirty-eight minutes, while the Rosendale brands require seventy-two and eighty-four minutes respectively. The latter are therefore more sensitive to a variation of temperature than the former. No. 6 belongs to a cement from Sandusky, Ohio. (Para- graph 81.) This cement is characterized by a remarkable w^ant of uniformity in quality, as it is offered in the market. One sample obtained in the summer of 1859, required several hours under water at 65° F., before it could support the light testing wire (^2 inch wire and } pound weight), and would not supporl the heavy wire until the second day after immersion. Anothei specimen, obtained several months later, gave for the light test- ing wire the curve No. 6. The cement hardened so slowly after the first set, that the curve for the heavy wire does not come within the limits of the diagram. No. 7 belongs to the cement manufactured at Utica, 111 (See paragraph 80.) It closely resembles that from Sandusky, Ohio, although it conducts itself under water rather more satis- factorily. By mixing the Sandusky and Utica cements to- hyi>kac"l:o cements, and mortaes. 85 getlier, :n equal quantities, a combination is obtained, which from experiments carefully repeated on a small scale, appears to be superior to either. It is therefore suggested to Western engineers and architects to use them in this way. 'No. 8 is derived from an artificial cement prepared from a stiff paste of fat lime mixed up with a sufficiency of double al- kaline silicate, of 39° Baume, in solution to bring it to the con- sistency of ordinary mortar. Almost any required degree of hydraulic activity may be conferred upon a paste of fat lime in this way. Limes that have been allowed to remain some days in the state of paste before adding the silicate, are pref- erable to those that have been slaked to a powder and pre- served in that condition. These latter are apt to crack under water, after the silicate has been added. No. 9 was from Roman cement manufactured from " Sep- taria," or clay nodules found on the coast of Scotland. It is proper to remark, that this cement bore evidences of having suffered from exposure during transportation, and was not therefore so fresh, and of course, not so energetic as an average sample would have been. In hydraulic quickness, fresh Ro- man cement is by no means inferior to the best Rosendale brands, while its subsequent progressive induration probably exceeds that of most American cement. No. 10 is from the cement manufactured at Louisville, Ky. Artificial Hydraulic Cement and Lime. 125. It is possible to make hydraulic mortar by using arti- ficial preparations of hydraulic cement, lime. Artificial hydrau- and pozzuolana, and this course is often pursued, mortar, particularly in France, in localities where there are no naturai deposits suitable for such purposes. There are ^^^^ methods of four methods of attaining this object, viz. : making it. First, by combining thoroughly slaked common lime with unburnt clay in suitable proportions, burnins: • ^ • T T i ^ f First method, the mixture in a lime-kiln or furnace, and 86 PEACTICAL TREATISE ON LIMES, then grinding it, producing what is called twice-kilned " arti- ficial hydraulic lime." Second, by substituting for the quicklime a carbonate of lime that can be pulverized without burning, Second method. in. ,^ n ^^ - t t like chalk, m other respects lollowing the direc- tions of the first process. Third, by making artificial pozzuolana, which is effected whenever calcareous sand and certain kinds of Third method. , . . clay are subjected to a slight calcination. Fourth, by adding silica, in a soluble form, to a paste of Fourth method. common lime. FIEST METHOD. 126. Before the calcination, the clay should be fully dried in the open air, or under sheds prepared for the Drying the clay. p. /i. • i a ^ purpose, alter the manner oi bricks and pot- tery. The proportion of lime and clay used should be varied Proportion of according to the quality of the clay, the charac- Ume and clay. ^^^.j^^ ^j^^ j-^^^^ ^j^^ degree ol hydraulic quickness which the resulting product should possess, that is, whether it is intended to imitate hydraulic cement or hydraulic lime. Ten per cent, of clay will confer "moderately hydraulic" energy, while it will never be necessary to exceed 54 per cent, to produce a very active cement. The clays that Kinds of clay have been found most suitable for that purpose most suitable. a^e those which are unctuous to the touch, and are of common use for manufacturing various kinds of earthen- ware. They contain .30 to .50 of alumina, and .04 to .05 of carbonate of lime. It is of the highest importance that the lime and clay should be thoroughly and homogeneously incor- porated with each other by means of a mortar mill, if prac- ticable, previous to the drying process, and that this latter should be continued until no trace of humidity remains. If this last condition be not fulfilled, no good results can be ob- tained, as the silica contained in the clay will not be in a state HYDRAULIC CEMENTS, AND MORTAES. 87 favorable to its combination with the lime in the dry way, and the clay will remain almost entirely inert, from the moment the mixture reaches a dull red heat. These facts, originally promulgated by M. Rancourt, have been amply verified by repeated experiments conducted by M. Ducreux and others. To prepare the mixture of lime and clay for preparation of drying and burning, it is customary to cut mixture for biim- it up into small cakes, or roll it into balls of two or three inches diameter. 127. The calcination is efi*ected at a lower temperature than that required by the natural stone ; a bright calcined at a low red heat is sufficient, as water is more easily dis- temperature, engaged from the cakes than carbonic acid would be. It is also necessary that this second calcination should take place un- der the influence of a good draught, or in contact with the air. The material thus obtained is said by M. Yicat to be prefer- able to the best hydraulic limes directly obtained from argil- laceous limestones, but we shall see further on, that this is at least doubtful. A saving of fuel can be effected by burning raw bricks, or common lime, or both, in the same kiln, with the argillo-calcareous balls, and this is practised in many countries. It can be done in kilns somewhat higher than the average, say eighteen feet, filling them with carbonate of lime up to nine and a half or ten feet, placing over it bricks to a height of five feet, and over the latter, the small pieces of lime and clay which have to be converted into hydraulic lime. The burnt balls may be pulverized between millstones, or by any other suitable means. SECOISTD METHOD. 128. When a soft carbonate of lime, like chalk, or calcareous tufa, is employed for making artificial hydraulic lime or cement, it is not necessary or customary to subject it to ^^^^ and clay calcination, previously to its being mixed with mixed together the clay. The reduction of both ingredients ^^^^^ burnmg. 88 PRACTICAL TREATISE ON LIMES, to a fine powder by suitable machinery, li(^wever, is essential as the first step ; after which they are thoroughly mixed together in proportions ascertained by previous experiments to give the desired results, made into cakes or balls, dried, cal- cined, and ground for use, as in the first case. The " Portland" cement of England and France* is made in this way, the calcination being carried to the laid^^ceinent^^' ^'^rge of vitrification. In its manufacture, chalk is generally depended on to furnish the calcare- ous ingredient. The necessity of reducing the carbonate to a state of paste, and of incorporating it with tlie clay before any calcination takes place, practically excludes the more compact varieties of limestone. The chalk may be amm.^^^^^ ground in any mill suitable for reducing such substances. One consisting of a circular trough of stone or brick work, in which two wheels are made to turn, has been used in England, and found to answer a good pur- pose. The wheels are located on the axis at unequal distances from the centre of motion, so as not to run in the same track. For extensive operations, a steam mortar mill like the one used at Fort Taylor (Figure 34), or some modification of it, would perhaps possess many advantages. 129. Water is added to the chalk before lu^rp^s^oTwater'! grinding, generally in considerable surplus. After this preliminary manipulation is com- pleted, the semi-fluid mass is conveyed into bins with grated or perforated bottoms, or made up into heaps and left, until, by drainage and evaporation, it is reduced to the consistency of stiff mortar. It is then in a condition to be mixed with the clay. Pwre oUuvial clay, or, when this cannot be pro- cured, fine pit clay, free from sand, is next eSabie.^^^^ added to the chalk paste, and the thorough and homogeneous incorporation of the two ingredi- ents is effected by means of a pug-mill. For the English Port* * The " artificial" Portland is here referred to. HYDEAULIC CEMENTS, AND MOETAKS. 89 land," the ai'gillaceous mud deposited by the Tliaraes and Med- way Rivers is used. The chalk is derived from , . The chalk used. the middle and upper layers oi that lormation, as it crops out on the banks of the Thames. These sub- stances are ground up together by millstones, v^^ith a sufficiency of water to produce a semi-fluid mass. A process of decanta- tion into vats, or hollows scooped out below the surface of the ground then ensues, by which the unground and heaviest par- ticles are left behind. 130. The mixture having attained the consis- tency of potter's clay, is kneaded into balls of into balls; drying about three inches in diameter, and dried in f/^^^^J caicma- ' tion. the air under cover for about forty-eight hours, and then burned in an ordinary lime-kiln. If the kiln be perpetual, the drawing may commence in about three days, provided a white heat has been preserved during the interval. 131. In comparing this process with the one in which slaked lime is used, it w^ill be observed that they differ in two essential particulars, viz. : 1st. The lime mixture must be thoroughly dried before burning, wdiile the chalk mixture need not be. 2d. The former is calcined with a burm^og?y^first^ moderate or brig-ht red heat, and the latter at a and second ° ' ^ ^ methods. white heat. The burnt cement is ground in the ordinary way between millstones. The proportions of clay and sand in the "Portland" cement should, of course, vary with the kind and quality of the clay used. M. Yicat analyzed a sample from the manufactory of Messrs. White & Sons, with the following results : Lime 68.11 Sihca 20.67 ^^^}5;sis of arti- ficial "Portland" Alumina 10.43 cement. Oxide of iron .81 This composition very nearly corresponds to that of the inter- mediate limes. 132. The following is a synopsis of the method of preparing 90 PEACTICAL TBEATISE ON LIMES, artificial cement followed in England, before the Old process. p , . -i i advantages oi the intense heat applied in burn- ing " Portland" cement were known. Selection of the ingredients of artificial cement. — The chalk. — The white or upper chalk of the geologists being a tolerably pure carbonate of lime, is to be preferred to the Chalk. . . 1 n -rw marly or impure deposits near the surface. By mechanical means it must be reduced to an impalpable powder, or, by the addition of water, to a homogeneous paste. The clay should be the hlue alluvial of lakes or rivers, in a state of minute division, and free of sand. In England, the deposits of the Medway, and in the United States, the compact beds of this unctuous clay, and the clays used for pottery, will answer. A long exposure to the air should be avoided, as it has been found to injure the quality of the clay for artificial cement. Proportions of clay and chalk. — By weighty 100 pounds of pure dry chalk to 137|- pounds of fresh blue ThTInd^'ciry. ^^^J' ^ei^g equivalent to four of chalk to five and a half of clay. By measure.^ one cubic foot of stiff chalk paste to one and a half cubic feet of fresh blue clay. ]^inety-six pounds of dry chalk produces one cubic foot of chalk paste. Mode of grinding the chalk. — ^The chalk is ground with the water necessary to produce a thin paste, in a mortar mill. Colonel Pasley recommends one with two broad vertical iron wheels, on a common axle, carried around by Sr^^^"^""^ means of a vertical shaft connected with the axle, and turning on a pivot in the centre of a cast iron pan. The wheels are placed at unequal distances from the centre of motion. The horizontal axle is attached rather loosely to the shaft, so as to allow the wheels to rise over lumps that may be larger or harder than usual. Scrapers are attached to the vertical shaft, to remove the paste from the circumference and centre of the pan, and throw HYDEAULIC CEMENTS, AND MOETARS. 91 Fig. 9. it in the track of the wheels, while other scrapers, attached to the axle, clean the sides of the wheels, as they rise out of the paste. The wheels may be four and a half to five feet in diameter, and from ten to fifteen inches wide at the rim which grinds the materials, and one of them may be placed at the central distance of eighteen inches, and the other of twenty-four inches from the centre of the pan. The radius of the horse- path may be eleven feet. Figures 9 and 10 will sufficiently explain the general construction of this mill. After grinding, the chalk paste will usually be found in too fluid a state for immediate use, and is generally allowed to stiffen by evaporation. The incorporation with the clay is ^'^S- 10. effected by means of a pug mill, and the mixture is then made up into balls about two and a half inches in diameter. These balls are al- lowed to dry under cover about forty-eight da/ hours, or until sufficiently hard to bear their own weight when piled in the kiln for burning. The burning 92 PRACTICAL TEEATISE ON LIMES, and grinding difi'er in no essential particular from the process used in the " first method". (Paragraph 126.) 133. Hydraulic limes and cements are artificially manufac- tured in many localities in France. The hydraulic lime of St. Leger may be taken as a type of the former. St. Leger It is composed of four measures of chalk and hydraulic lime. measure of clay, which corresponds, accord- ing to the analysis by Berthier, to eighty-four of carbonate of lime, and sixteen of clay containing ten of silica ; or in other words, one part of clay calcined with five and chX^and^day. ^ quarter parts of pure limestone. The chalk broken np into pieces of the size of three or four inches cube, is placed with the clay in a large vertical mill driven by two horses, and both materials are crushed and mixed together with a plentiful supply of water. The semi fluid mixture is then run off into a series of five troughs placed on different levels, in which it remains imtil sufiiciently stiff to be made up into balls two to three inches in diameter. When these are sufiiciently dry, they are cal- balisl^^*^°^ cined in an ordinary lime-kiln, and then ground up between millstones for use. The fuel used in this burning is a mixture of coal and coke, which is mingled with the balls in a perpetual kiln. The degree of heat is consid- erably below that required in burning the " Portland" cement. For producing artificial cement, M. Yicat recommends the proportion of sixty parts of clay for one hundred of chalk, or fifty-seven of lime. 134. MM. Chatoney and Pivot, Fre^ich engineers, recom- mended to the French Academy of Sciences, in 1856, the use of pulverized silica in combination with fat lime, for the pro- duction of artificial hydraulic limes. Hydraulic lime These gentlemen claim that excellent arti- composed of ficial hydraulic limes can be obtained, by sub- pulverized silica , . . and fat lime. mitting to a moderate calcination an intimate mixture of nearly pure lime and very fine sand HYDEAULIC CEMEKTS, AND MORTARS. 93 or ground silica, in the proportion of twenty to twenty-five parts of the pulverized silica to eighty to seventy -five of lime. The greater the care taken to produce a homogeneous mixture, the better will be the product obtained." In another place, they remark : " pulverized silica burnt with fat lime produces hydraulic lime of excellent quality. In the experiments tried at Havre within the last two years, it has set under water in three or four days, and acquired a hardness r i ' ^ Is equal or supe- in twenty-two months equal and sometimes rior in hardneaa to , .11 T t T-t 1 T> Portland cement;. superior to that attamed oy the ' r^ortland cement in one or two months." The proportions between the silica and lime were various : the weight of the powdered lime never exceeded four times, and was never less than one-half that of the powdered silica. The calcination of the mixture may be conducted according to the directions given for the clay and chalk mixtures. THIRD METHOD. 135. Artificial pozzuolana is produced whenever clay is sub- jected to a slight calcination. The properties pos- sessed by brick or tile dust, of forming with fat pozzfioJ^na. lime a mixture possessing hydraulic energy, were known to the ancient Romans. Many of the feebly natural pozzuolanas have their activity very sensibly in- „ ^ ^ -J J J Feeble pozzuo- creased by burning, while there are many inert lanas improved substances, besides the clays and argillaceous sands that may be converted into artificial pozzuolana by the application of a moderate heat. Forge scales, snch as fall from a smith's anvil, the slags from iron foundries, the ashes from under the grates of lime-kilns, containing cinders, coal, and lime, are artificial pozzuolanas. 136. It is a well established fact that nearly, if not all, mag- nesian, argillaceous, or argillo-magnesian lime- , i? 1 • 1 ii -J.' 'J. Underburnt stones, of which the composition approximates limestones, to that of good cements, however destitute they 94 PRACTICAL TREATISE Olf LIMES, may be of hydraulic energy and quickness, when fully cal- cined, are moderately, if not eminently quick setting, if suitably underburnt. (See paragraph 264 and following.) The same is known to be the case with pure carbonate of lime when partially burnt. Some of the coral sand Ke^ West. ^^^^ from Key West, calcined for half an hour in a crucible at a bright red heat, and then pulver- ized, yielded a paste which attained a permanent set under water in half an hour. The tests of the strength of the mortars thus formed without sand were not very satisfactory, as com- pared with cement mortars. They were, however, stronger than mortai-s of common lime and sand, besides possessing the advantage of sustaining immersion in a short time after being mixed. There seems no reason to doubt that good artificial Acts as pozzuo- pozzuolanas may be produced by suitably under- lana when under- burnine: calcarcous sands, and in localities burnt. 1 . 1 , , . where, or at times when cement cannot be had, this method of obtaining hydraulic mortar might be advan tageously resorted to. 137. It must be admitted as a general fact, that all attempts to utilize the hydraulicity which characterizes underburnt cmnmon lime have either signally failed, or, at best, met with but indifferent success. Trials with compound limestones and certain mixed earths and sands have been more successful. 138. Some compact dolomitic earths of France have pro- duced excellent artificial pozzuolanas. The earth is quarried by using wooden wedges, inserted and driven into notches or grooves cut in the beds, in such a manner as to favor the splitting out of good sized masses. These are divided into small blocks, dried in the sun or under a shed, and then baked in an ordi- nary lime-kiln. For burning, there is required about one mea- sure of charcoal to sixteen or eighteen measures of the clay. 139. At Calais, France, a good artificial pozzuolana is pro- duced by burning an argillo-calcareous earth taken from the sea-shore. The earth is produced by admixture, from natural HYDRAULIC CEMENTS, AND MORTAES. 95 causes, of the calcareous washings of the cliffs of the E^ormandy coast, and the argillaceous mud either brought down by rivers, or formed by the crumblings of the upper bed of the cliffs. The earth is taken from the beach, dried and burned in the same manner as the paste of ordinary clay, in making artificial pozzuolana. At Brest, gneiss sand is found in considerable beds. By submitting it to calcination in a reverberatory furnace, a poz- zuolana is obtained, which, although not very energetic, is yet sufiiciently so to cause ordinary fat lime mortar to harden in seven days. FOURTH METHOD. 140. The fourth method, not very well understood at pres- ent, of conferring hydraulic properties upon fat lime, is strictly and technically artificial, and skives promise of . , Fourth method more extensive application m this country than not very well either of those above noticed. It is, besides, ^^^^^stood. Bubservient to a variety of useful purposes in the indus- trial arts, to which the others could have no possible appli- cation. It consists essentially and briefly in transferring to the lime mortar, or paste, when undergoing the last manipulation at the hands of the workman, a suitable quantity of silica, in such a minute state of subdivision, that it vnll enter into combina- tion with the lime, in the formation of insolu- ble hydro-silicate of lime— the compound to feat^^"'^''* which the cements, derived from the argilla- ceous limestones, principally owe the property of hardening under water. 141. The alkalies have been found to constitute a conve- nient and efficacious medium for this transfer. It is known that if pulverized chalk, or, in fact, any li i cMtoue in the con- 96 TEACTICAL TREATISE ON LIMES, dition of fine powder, be made into a paste with an alkaline solution of silica, or what is commonly known iifaHne^sUiiates ^s liquor of flints," "soluble quartz," or ohaHi^^'^^^^^^ " glass," a chemical decomposition en- sues between the carbonate of lime and the silicate of potash or soda — the carbonic acid being transferred to the alkali, wliilst the silicic acid (silica) enters into combina- tion with the lime, producing silicate of lime. These reactions take place readily under water ; and the paste, undeTwater.^*^ immersed, hardens with greater or less rapidity, depending on the amount of silica used, and comports itself, apparently in all respects, like hy- draulic cement. It is, in fact, an artificial stone, which, w^hen prepared in a sufficiently liquid state, and with the proper amount of silica, possesses the property of adhering with con- siderable force to the surface of bodies receiving it, constitut- ing a stony envelope, or covering, as it were, and rendering them, to a great extent, indestructible by fire or water. It is ^ not theoretically or even practically necessary need not be in that the alkaline silicate should be in solution, solution. when added to the lime. If employed solid, howevw, it must be reduced to an impalpable powder, in or- der to secure its thorough and complete incorporation with the pulverized carbonate, and the mixture may then be formed into a paste. Some attempts to produce artificial hydraulic mortar by this method did not give satisfactoiy results. 142. If the limestone has been previously calcined, as will be generally the case in all preparations of mortar for mason- ry, whether of brick, stone, or concrete, and is in the condition of dry hydrate, similar results may be ob- .AJ.lcdJij3.6 silicates mixed with tained by forming this hydrate into a paste, quicklime. ^-^-j^ ^ requisite proportion of silicate of soda or potash, or a mixture of both, which, as in the former case, may be either in solution or dry powder. It is believed that the advantages to be derived from a thorough and homoge- HYDRAULIC CEMENTS, AND MOETAES. 9Y neous paste can be most readily obtained, when the silica is added in solution. 143. By the means just indicated, probably the common or feebly hydraulic limes, and (what in practice will prove of greater importance) the dividing limes (chaux limites of Yicat), those which possess the objectionable and dan- gerous property of setting rapidly under water, ^draSfc a^d only to be immediately followed by a gradual intermediate and complete disintegration, due to the slug- gish caustic lime present, may all be transformed into reliable and valuable cements. All the initial energy of the dividing limes may be preserved in this manner. 144. Experience has shown that, if any hydraulic mortar, possessing no matter how high a degree of quickness and energy, be re-pulverized and formed into a paste, after hav- ing once set^ it immediately descends to a level, in point of hydraulicity, with the moderately hydraulic limes. A great destruction of the hydraulic principle therefore results from any disturbance of the molecular Sget^^desta-oys arrangement of the mortar, after the crystalli- hydrauUc zation has commenced. This is precisely what takes place in those cements denominated intermediate or di- viding limes, which take the initial set promptly and firmly, but are subsequently thrown down by the slaking of the im- pure caustic lime which they contain. 145. The alkaline silicates supply a specific remedy for the defects just referred to, and when added in the proper form, and in sufficient quantity, to cements of this type, preserve intact all their hydraulic power, a remedy by presenting to the defective ingredient an efficacious neutralizing agent. Eight to ten per cent, of an alkaline silicate, of the consistency of thin syrup, will confer upon a mortar of fat lime a decree of hydrau- Ml 1 . . , ? ^ Proportion of licity that will place it m the class of cements alkaline silicate in hydraulic activity, and any inferior grade of ^ ^® 98 PEACTICAL TREATISE ON LIMES. energy that may be desired, is secured by proportionally di- minishing the percentage of silica. To elevate the hydraulic limes to the standard of cements, or to any fixed standard, re- quires, of course, a less amount of silica than is necessary for the common lime, the proportion varying inversely with the active energy of the limes acted upon. 146. There is a variety of other important uses to which this silicifying process, as it may be termed, can be advantageously applied, for our knowledge of which we are chiefly indebted to M. Fred. Kuhlmann, Professor of Chemistry at Lille College, France, and M. Fuchs. We will refer to them very briefly in. this connection. 147. When a solid body, of any degree of porosity, is im- mersed in water or any other fluid, it rapidly absorbs a certain quantity of the latter, until the point of complete saturation is reached; and if, in addition, the fluid possesses reacting powers, certain chemical changes will ensue within the pores of the solid body. If a porous limestone, like chalk, Action of the „ , . „ i? . t silicate on porous lor example, or a piece oi mortar oi lat lime, ^stone or dipped in a solution of alkaline silicate, a certain portion of the silica in solution, after its absorption, will part with its potash or soda, and enter into combination with the lime, whilst another portion will remain mechanically interposed in the pores of the solid body, and wiU, in time, if exposed to a current of air, solidify by desicca- tion. The result will be that, with a single immersion, the density and hardness of the chalk or the mortar bec^mef harder. ^® augmented, and after several alternate immersions and exposures to the air, these properties are attained in a considerable degree. The softest varieties of chalk may be thus hardened, so as to become capa- ble of receiving a high polish. 148. Upon the sulphate of lime or plaster, the action of the alkaline silicate is essentially the same, though more rapid, and is accompanied by the inconvenience of giving rise to HTDKAULIC CEMENTS, AKD MORTAES. 99 an alkaline sulphate, which, in crystallizing Action of the within the pores of the solid body, near the silicate on the „ . . T . sulphate of lime; suriace, is apt to cause disintegration. It is recommended in this case to use the solution more diluted, with a view to retard or diminish the effects of the crystal- lization of the sulphate, to such a degree that the indurating solid will be able to resist it. 149. The process of silicatization^ so named by Mr. Kuhl- mann, which rests upon the principles enunciated above, is of undoubted utility, although, as yet, its practical application is attended with difficulties, and followed, not unfrequently, with uncertain results. It appears destined to meet with a varied and extensive application, in the industrial and fine arts, not only in the conversion, at a moderate cost, of . , 1 , T T /. .11 " Silicatizatioa" common into hydraulic lime oi any required de- applicable to a gree of activity, and with a fair, or at least, ^^^^fjjj^ ""'^^"^ encouraging degree of strength, but in the preservation of walls of whatever kind, already constructed imadvisedly of materials liable to more than ordinarily rapid decay, whether of brick, stone, pise, or concrete ; in the restora- tion and conservation of statuary, monuments, architectural ornaments, &c. ; in transforming designs cast in ordinary plas- ter into hard and durable stone, in rendering wood- work, and, to a limited extent, even cloth fabrics indestructible by fire, and in a multitude of other collateral uses, some of which are even now well developed and in practical operation, while others remain still in their infancy, giving more or less encour- aging promises of future utility and value. 150. Within the last ten years, grave doubts have arisen among European engineers, as to the suitability « , , • 1 . J -u • • Doubts of the ot those artincial mortars prepared by mixing stability of artifi- slightly-burnt clay with common limo, for con- rortShe"«. structions exposed to the action of sea-water. The French engineers had entertained very favorable opinions of those mortars, and had paid great attention to their use 100 PRACTICAL TEEATISE ON LIMES, between the years 1820 and 1840, deriving their opinions mainly from the investigations of MM. Yicat, Authority for Treussart, Eancourt, and others, who thouajht using them. . ' ^ themselves justified in deducing from their re- sults that the clays, when subjected to the proper degree of calcination, would operate in expediting the hardening of lime, in all respects like the natural pozzuolanas. For some years, these mortars exhibited no marks of weakness or instability, but more recently have, according to the opinion of MM. Chatoney and Rivot, so far yielded to the solvent action of sea- water in some localities, that but few constructors would be justified in using them, until their peculiarities are further developed by experiments and the test of time. The mortars Natural pozzuo- derived from a mixture of natural pozzuolana lana mortars give and fat lime have been found to give better re- better results suits, although it is conceded by many who have advocated the preparation of hydraulic mortar by this method, that the Romans were more successful in the employ- ment of natural pozzuolana than those engineers who have given attention to this subject during the present century. 161. Marshal Yaillant, member and reporter of a commission of the Academy of Sciences of France, to whom was referred a memoir of MM. Chatoney and Rivot, entitled, " General Considerations upon Hydraulic Materials used for Constructions in the Ocean," submitted to the Academy in the SfiTamantttiere- year 1856, says in his report, when speaking of or^iencts'^'^^'^^ mortars of lime and pozzuolana: '^Natural pozzuolana mortars were used by the Romans for submarine constructions, which are, at the present day, in a perfect state of preservation. The Dutch engineers have likewise used them successfully in their sluice works. But all , . , .^^ recent trials with pozzuolana, natural or artifi- Recent tnals with . pozzuolana unsuc- cial, have resulted in failures. According to cessfui. MM. Chatoney and Rivot, these mistakes in the use of pozzuolana could, without doubt, have been avoided if, HYDEAULIO CEMENTS, AND MOETAES. 101 in conformity to the usages of the ancients, they had been pre- viously submitted to a long concoction. Those gentlemen have as yet, no experimental results to furnish in support of this assertion, but it appears very rational. We can comprehend, in fact, that if the previous concoction is advantageous to mor- tars of lime, and even of cement, it is indispensable to the success of mortars of pozzuolana, which differ from the former, in that the combinations of the lime with the silica exist, for the limes and cements, already formed by the calcination, and have only to become hydrated at the time of their use ; whilst, in the fabrication of mortars of pozzuolana, the silica and alum- ina have to free themselves from combinations in which they exist in the pozzuolana, in order to form with the lime, in the wet way, those compositions which form hy- drates under water. We see from this, that it cltin'S'Id!'''' is better to mix pozzuolana with fat lime than with hydraulic lime, since in the latter case, the hydraulic com- positions formed in the dry way (voie seche) during the calci- nation, will have set a long time before those formed in the wet way {voie humide) become hydrates, and the setting of these latter might endanger the stability of the mortars by disinte- gration." Moreover, in mortars of natural pozzuolana and hydraulic lime, it is only the excess of caustic lime contained in the latter, which combines advantageously with the silica and alumina of the pozzuolana. The report goes on to say : " The artificial pozzuolanas consist of burnt clay pulverized ; most of them contain lime, and possess the same causes of de- struction as the mortars of natural pozzuolana and hydraulic lime. They have not yet been successful in the ocean, and their employment will always be attended with difficulty, principally on account of the irregularity of the mortars into which they are introduced. " The authors have had in view, in their memoir, only those mortars exposed to the action of sea-water, but they entertain the opinion that most of these observations are applicable to 102 PE ACTIO AL TREATISE ON LIMES, mortars immersed in fresh water. Scarcely ten years have elapsed since the disintegration of mortars by the action of sea- water became a well-established fact. It was not observed until after the time when a too absolute confidence in continued!^^ hydraulic materials, led to the execution of heton (concrete) masonry in immediate contact with water, without any revetment of cut stone or carpentry, with- out any covering of wood, and without any of the protections which the ancient works received. It is also but a short time since heton has been placed in contact with currents of fresh water, and although alterations have not, as yet, taken place in that kind of masonry, nevertheless, it may be presumed that they are gradually produced by the dissolving action of the gas, and the salts which the water contains, modified by the tern perature, and the action of the tides." 152. The proposition laid down by MM. Chatoney and Rivot, that the mortars of Italian mzzuolana. Opinion of MM. ' _ , . .7 7., , Chatoney, and recentiy employed m the Mediterranean^ ham given unsatisfactory results^ is concurred in substantially by M. Tostain, Inspector-General of Eoads and , . , Bridges, who, in his letters written subsequently concurred in by & 3 ? 1 j Inspector-Gen- to his inspections in the years 1857 and 1858, wherein his attention had been specially di- rected to the condition of the mortars and concretes, observes : " I have said, and shall again say, that I saw in all the ports which I visited on the Mediterranean, in France, Algeria, Cor sica, and on the coast of Italy, pozzuolana mortars attacked by sea-water. I do not say absolutely that all the mortars, with- out exception, were altered. There were, no doubt, good portions on which I saw nothing wrong ; but everywhere, that is, at all the ports, I found partial alterations. On the other hand, I have not examined the walls of Dock JSTo. 3, mentioned by Mr. Noel.* " With regard to the portions exposed to the shock of heavy * The dock referred to is in the harbor of Toulon. HYDRAULIC CEMENTS, AND MOETAHS. 103 seas, such as the large blocks of the outside works of the break- water, I shall go further, and state that I have not seen a single one that was free from alterations, that is, one whose whole surface was intact and well preserved. The surface be- comes rough at first, and is continuously made more so by the waves ; the pebbles of the beton are left projecting and after- wards get loose ; the edges of the work get blunt, and the volume of the block gradually decreases." 153. On the other hand, M. E^oel, Inspector-General of Roads and Bridges, who takes the other side of . IT . . Contrary opinion the question, brmgs to the discussion a ripe ex- of inspector-Gen- perience, and a reputation by no means second ^^^^ to that of M. Tostain. In reference to the alleged failure of mortars of fat lime and Italian pozzuolana, he says: "This assertion is in contradiction of well-established facts. All the hydraulic works at the port of Toulon, have been executed ex- clusively, even of late years, with mortars composed of Italian pozzuolana and lime, either fat or hydraulic (that of Lagoubran), and I affirm with all the authority which a thirty years' resi- dence at this port can confer, that not one of the works has failed on account of defective mortar." M. Noel also refers to the successful use of the same kind of mortar by Colonel Sauli, in the construction of the dry dock at Genoa, where it was used as concrete. A description of this dock in the " Annales des Fonts et Chaussees," for 1853, furnishes the following extract : " If the work is examined more in detail, it is found that the heton (concrete) which constitutes the bottom of the apron and the exterior surface of the side walls, has acquired a very great hardness in consequence of its composition, (pozzuolana of Rome, ordinary lime, and calcareous gravel), and that it is free from all porosity, in consequence of the care which the skilful di- rector of these works took to clear his beton, by constantly pumping up the washings (laitance) during the operation of immersion." 154. The mole of Algiers was executed in concrete, some 104 PEACTICAL TREATISE ON LIMES, portions of which were composed of artificial blocks, allowed to dry in the air before immersion, and other portions, of concrete immersed fresh. In this connection, therefore, we will briefly refer to certain " observations and experiments upon the mortars Mortars of the employed in the sea at Algiers," made by M. mole of Algiers. Ravier, engineer of roads and bridges, and pub- lished in the " Annales des Fonts et Chaussees," vol. viii., 1854. From this we learn that prior to the year 1852, the mortars immersed, after drying in the air, were composed of fat lime and a mixture of equal parts of sand and Roman pozzuolana, and that the lime was slaked successively by the ordinary process, and by aspersion. In the first case, the mortar contained equal volumes of lime paste, sand, and pozzuolana, in the second 2J volumes of slaked lime in powder, 1-J of sand, and 1^ of pozzu- olana. Mortars for immediate immersion were composed of fat lime and Roman pozzuolana in various proportions. Since the beginning of the year 1852, hydraulic lime from Theil, on the right bank of the river Rhone has been used, the stone being calcined at Algiers, and slaked by aspersion, as required for use. For making the mortar for the artificial blocks, it is mixed with sand. In exceptional cases, when the blocks are to be immersed at the age of thirty days, one-half of the sand is replaced by pozzuolana. An analysis of the Theil limestones is given in Table lY. Page 226. 155. "Without attempting a connected synopsis of M. Ra- vier's report, referred to in the last paragraph, a few brief extracts are given below : 1st. Page 25 : " It results from the foregoing experiments, that all mortars on trial of fat lime, sand, and Roman pozzuo- ^ ^ ^ ^ lana, after dryinp* in the air, or immersion in Extracts from M. ' ./to ' Ravier's report fresh water, are destroyed when placed in sea- thereon. water. This takes place even with a mortar containing by weight about twenty of caustic lime for one hun- dred of pozzuolana, and one hundred and thirty of sand." 2d. Page 29 : " It follows from these observations that fat HYDEAULIC CEMENTS, AND MORTAES. 10 lime mortars do not sustain immediate immersion (in sea water) no matter what proportion of pozzuolana they con- tain " a r^^Q trials were all favorable to mor- tars of hydraulic lime with or without pozzuolana." 3d. The trials with mortars of fat lime and Grenoble cement allowed to dry in the air, show that the cohesion of these gangs diminishes w^th age. A mortar composed by volume of 2.15 of fat lime, 1.00 of cement, and 5.40 of sand (correspond- ing with equal weights of dry cement and quicklime) gave a cohesion strength of 2.55 killograms per centi- metre square, at the age of two months, and of fain^ortars?^^" 1.16 killograms at the age of twenty months. Another mortar, with the same proportion of sand, with a gang containing by weight 100 of dry cement and 47 of quicklime, gave at the same ages, breaking weights, 2.82 kilos, and 1.59 kilos, per centimetre square, respectively. 156. The following is a condensed view of the resume given by M. Ravier himself : 1st. The Roman pozzuolanas used at Algiers are, contrary to the opinion hitherto entertained, incapable of forming with fat limes, mortars able to resist the saline action of the sea- water. 2d. The form of the mortars submitted to immersion exerts an important influence upon the action of the sea- water; the sharp edffes and curves of small „ , , , M. Ravier's radius assist the destructive action ; plane sur- condeiised re- faces, OR the contrary, essentially protect the cohesion of the mortars, and may preserve them unaltered for several years. 3d. Tl^e preservation of the works executed at Algiers with fat lime and Roman pozzuolana, is specially due to the deposits of mineral substances secreted by marine animals. 4th. In this respect, the artificial development of beds of oysters upon sea works, appears to promise important results. 5th. Mortars of fat lime and l^aples or Rachgoun pozzuo- 106 PRACTICAL TREATISE ON LIMES, lana, also fail in the sea. Similar failure attaches to the mor tars of sand and St. Chamas hydraulic lime. 6th. All the observations are favorable to the perfect pres- ervation in sea-water of mortars of sand and hydraulic lime horn the Theil quarries. 7th. The substitution of an equal volume of Rachgoun or Eonian pozzuolana for a part or the whole of tinuecT^^' ^^^* "^^^ sand, in the mortal's of Theil hydraulic lime disposes them unfavorably at first, to re- sist the saline action. The phenomena of disaggregation that were observed were limited, and furnish no sufiicient reason, without further proof, for excluding the use of pozzuolana con- currently with hydraulic limes, when it is desirable or neces- sary to obtain a mortar that will indurate rapidly. 8th. The Roman, Rachgoun, and Naples pozzuolanas used in the trials, are not homogeneous ; the differences afi:ecting the composition of the silicate of alumina, in each of these materials, vary between somewhat wide limits. 9th. The same want of liomogeneousness is established for the limestones of the Theil and Alignol quarries, which both belong to the same formation. 10th. The analysis of the limestones of the Theil quarry, and the results obtained in the sea with the limes manufac- tured from them show, that by taking for the measure of re- sistance to the saline action, the ratio of the clay plus the magnesia to the lime, this ratio, which has been called the index of hydrcmlicity, can, on the average fall to without the mortars being destroyed, whether they were immersed dry or fresh. 11th. The disaggregation of the mortars coincides with the increase in the quantity of the sulphate of lime, U^ueT""^' ^® attributed to that salt, produced by the action upon the lime, of the sulphate of magnesia of the sea-water. It was produced in variable pro- portions in all the gangs experimented upon, but destroys HYDRAULIC CEMEOTS, AND MORTAES. 107 them only in the cases when it is produced in sufficient quan- tities. The surfaces upon which this salt exists abundantly, can acquire and preserve a considerable hardness. 12th. In the mortars of fat lime and Roman pozzuolana, the sea-water attacks not only the free lime, but also that com- bined with the silica. 13th. In the mortars of hydraulic lime preserved intact, after having been kept under water for several years, and also in the gangs of Yassy cement, a notable proportion of free lime is detected. 157. M. Feburier, as the result of numerous experiments at St. Malo upon various limes, pozzuolanas (nat- Feburier's ural and artificial), and trass, arrives at the fol- experiments, lowing conclusions, which, although indorsed by M. Yicat, are by no means coincident with the deductions of other emi- aent French engineers : 1st. " That mortars of fat lime and Dutch trass do not resist the action of sea-water." 2d. " That ordinary artificial hydraulic limes, or natural feebly hydraulic limes, even when mixed with feebly hydraulic poz- zuolanas, equally do not resist." 3d. "The only limes capable of thus resisting are the ^ twice kilned' artificial hydraulic limes, or the natural His conclusions hydraulic limes which approach the limits of cements." These conclusions are irreconcilable with the excellent re- sults obtained by the Dutch engineers with mixtures of rich shell-lime, trass, and sand. 158. There seems no reason to doubt that the natural quick- setting cements, such as the Roman, the Yassy, the Rosendale, and the Boulogne "Portland" brands, and those artificial Portland cements, produced by calcining a mixture of chalk and clay with a heat sufficiently great to produce incipient vitrification, can furnish mortars capable of resisting the sol- vent action of sea-water. 108 PRACTICAL TREATISE ON LIMES, 159. Upon the general question of the destructive effects of Bea-water upon those gangs, natural or artificial, which form the bases of hydraulic mortars, whether derived from hy- draulic lime, cement, or pozzuolana, M. Yicat's researches led him to certain conclusions which may be condensed as follows, from the "Annales des Fonts et Chaussees" for 1854: : 1st. The double hydro-silicates of alumina and lime are de- void of stability, and will, without exception, if pulverized and „ , . immersed in sea-water, or even pure water, be- M. Vicat's views. t , , , . lore they have been subjected to the action of carbonic acid, and thereby transformed to carbonates, give up to the water an appreciable quantity of lime. 2d. The other conditions remaining the same, a dilute solu- tion of sulphate of magnesia substituted for the jpure water, will convert all the lime of these silicates into a sulphate, un- less carbonic acid be present during the reaction, in which case its equivalent of lime will become a carbonate. 3d, All pozzuolanas, irrespective of origin or comjDOsition, require for their complete practical saturation a much smaller dose of lime than they generally receive, when made into mortar, owing to imperfect pulverization and manipulation. 4th. The afiinity of carbonic acid for the lime is sufficiently powerful, in the presence of water, to separate its full equiva- lent of lime from combination with the other ingredients of these silicates, leaving the said ingredients, whether combined or not with each other, simply mixed mechanically in the compound. 160. From the foregoing it would appear that sea- water will destroy the gangs of all mortars derived Protecting coat. ' • t . i i n i from the sources indicated, ii it be allowed to penetrate the immersed masses ; but as some mortars do prac- tically withstand continuous immersion in sea-water, it fol- lows that the latter meets on the surface something to impede or prevent its penetrations. These impediments are : 1st, and principally, a coating of carbonate of lime ; the car- HYDEAULIC CEMENTS, AND MOETAES. 109 bonic acid being sri])plied from the atmosphere befcre immer- sion, and subsequently from the water ; ^ , ^ ^ ./ . , . , Carbonate of lime. 2d, in certain cases, particularly with gangs derived from the ma^nesian limestones, the for- Carbonate of mag. ° , nesia. mation of carbonate of magnesia. 3d, an incrustation of shells and submarine vegetation. 161. M. Yicat was subsequently led to recommend mag- nesia as a suitable ingredient of mortars to be Magnesia re- immersed in sea-water, stating that if it could commendfid. be obtained at a cost that would permit its application to such purposes, " the problem of making heton (concrete) unaltera- ble by sea-water would be solved." That learned experi- menter also intimates that the Theil hydraulic lime is the only one with which he is acquainted, that could unquestionably furnish a mortar indestructible by sea-water, suggestion by AJ. Balard suggests that the mother water of ^- ^alard. salt ponds, applicable to no other useful purpose, might sup- ply magnesia at a moderate cost. 162. In the presence of these conflicting opinions, which are characterized by apparently irreconcilable elements, the American engineer can congratulate himself that the supply of hydraulic cement in this country affords a American ce- more reliable source of hydraulic mortars than "^^"^^ mortars, either natural or artificial pozzuolana ; and that this question, therefore, possesses for him no important practical bearing. 110 PEACTICAL TEEATISE ON LIMES CHAPTER Y. 163. Our nomenclature of the products derived from the calcinations of the several varieties of limestone, still remains imperfect. 164. These products are as varied and diversified in their character, and require as many distinct and peculiar modes of , , manipulation, in order to satisfy the conditions Diversified char- ' acterofiime- which are indispensable to their advantageous Btones. employment for mortar, as there are variations in the composition of the limestones themselves. This is more especially the case with those limestones which contain so large an amount of foreign matter, such as silica, alumina, magnesia, etc., usually exceeding ten of the whole, as to disqualify them for ordinary use as fat lime, but which places them in the cate- gory of hydraulic limes or cements. When we keep in view the multiplicity of causes for such variation in all sedimentary rocks, causes, indeed, that pertain in their fullest force to all calca- reous formations, and more especially to those which, from their compound character, have proved to be best adapted to the production of hydraulic mixtures, we obviously need seek no further for an explanation of that remarkable want of homo- geneousness which characterizes these deposits, or expect to find any locality in which it does not exhibit itself. 165. The same strata, even within very narrow lateral limits, frequently become so changed in their physical appearance as well as in their chemical composition, as to lose not only the means of verifying their geological identity, but their most prominent lithological features. HYDRAULIC CEMENTS, AND MORTAES. Ill 166. We miglit, therefore, expect that the best practical rales for converting such heterogenoeus material into use as a gang for mortar, would require to be modified to suit local circum- stances. It is equally self-evident that such modifications can only be properly determined by adequate pre- j^ocai examina- liininary and local tests. Although the theoret- tio^s and testa ical correctness of these premises will perhaps ^ be questioned by very few, their practical observance by manu- facturers and consumers of limes and cements, is greatly neg- lected. 167. The calcareous deposits in the United States, from which the present supplies of lime and cement are derived, if severally classified and arranged according to their composition, as shown by quantitative analyses, would strikingly illustrate the necessity of awarding to each locality such special rules for manipulation as can only be supplied by an extended series of experiments. It is not to the almost endless variety of quarries of dissimilar stone simply, tliat the difficulty is confined, since this, however great, is only coextensive with the extraordinary heterogeneity generally existing among the strata of the same quarry. Al- though this feature does not characterize the beds of common limestone, at least, not to an extent ^meri?depo^ts^ that can be regarded as prominent, it is so uni- formly present in the argillo-magnesian deposits, that we may safely assume that every extensive deposit capable of furnish- ing an energetic cement, will also furnish from among its several layers, every inferior grade of combination, down to slightly hydraulic, meagre, and common lime. 168. Frequently, and perhaps generally, among deposits fur nishing cement stone, the several lay ers— which vary consider- ably in thickness, though they are seldom less than one foot or more than six — so far preserve the character and relative pro- portion of their constituent parts within the ordinary lateral limits of a single quarry, as to require only an occasional, — it may be a semi-weekly, or weekly, or perhaps, in rare cases, a 112 PRACTICAL TREATISE ON LIMES, montlilj, — verification of their respective characters, but in a majority of cases, the v^^ant of homogeneousness ^stenrfi'L^''" extends to the several layers individually, and attaches to them persistently for miles in ex- tent, rendering it necessary to keep a daily, and even hourly surveillance upon the workmen, to prevent their making use of bad or worthless stone. 169. When the stone occurs in distinct and easily recognized layers which, for considerable distances, retain with little vari- ation, a known and specific character, whether good, bad, or doubtful, and which are readily separated from each other along the principal planes of subdivision, the practical difficulties to be overcome in quarrying are comparatively few, and simply require for their removal, the employment of reliable and faith- ful workmen, who will exercise the precaution to reject those strata which are known to be unfit for use. 170. In the general case, however, the problem is far less easy of solution, for we find those materials, whose exclusion from the combination is of the highest importance, disseminated throughout a series of strata, in constantly and widely varying Practical d ffic 1 Proportions, and frequently in a form present- ties in selecting ing no physical features except to the most good stone. practiced eye, to assist in their detection. The calcination sometimes so far alters their appearance, as to ren- der them more easily identified. These materials generally consist of carbonate of lime more or less pure ; or a compound stone, in which the preponderating ingredient is inert silicious sand ; or argillaceous slate or limestone, containing an excess of clay and granulated silica. They usually occur in rather thin masses or sheets, varying from two or three inches to sev- eral feet in length and breadth. There is probably not a single quarry in the United States, worked for hydraulic lime or ce- The ordinary pre- entirely free from them. For the detec- cautions neces- tion and exclusion of these objectionable por- gary. tions of a quarry, we must, therefore, depend HYDRAULIC CEMENTS, AND MOETAES. 118 conjointly npon tlie faithfulness of tlie quarryman, the experi- ence of the burner, and his skill in detecting them after calci- nation. 171. Changes in the character of a cement stone often take I lace slowly and progressively within the limits of individual beds, in directions both perpendicular and parallel to the planes of stratification, without any perceptible variation in the ap- pearance of the stone, or in its homogeneousness, and simply require for their correction a modification in either the propor- tion of the difiPerent layers introduced into the combination, in the degree of calcination to which they are subjected, or in both. It might, under such circumstances, become necessary to use separate kilns for layers that had pireviously been mixed to- gether in burning. Deposits of this character require close and constant attention, in order dSsTmUar stone, that the proportion of the several dissimilar layers, and the intensity and duration of the heat employed in burning them, may be so regulated as to give results that shall be uniform, or at least approximately so. 172. It is therefore important that some practical method of ascertaining the absolute ^s well as the relative value of these several kinds of stone, should be pointed out, and it is equally important that such a method fectmiSel'^^^ should be simple, inexpensive, and easy of ap- plication. It is not necessary, though it might be advanta- geous in some cases, that it should comprise any essay upon the composition of the stone, or the proportion of its constituent parts. Indeed, any practical method would be much better without any accessory requiring the exercise of any theoretical knowledge, not within the ready comprehension of that class of men to whom manufacturers, with few exceptions, confide the details of their work, and consequently not susceptible of daily and hourly application by them. 173. The only apparatus required for this purpose is a cruci- ble of the capacity of one pint or thereabouts, and a mortar and 8 114 PRACTICAL TEEATISE ON LIMES, pestle. The crucible should be perforated near the bottom, in several places, to give an upward current of air and facilitate the escape of carbonic acid gas, and should be pro- chtr1!cter!^^^ vided with a cover Hkewise perforated. When access can be had to a grate fire of anthracite coals, this single crucible may be advantageously replaced by several of smaller size. When more than one One or more crucibles is used, however, care must be taken to so reg- reqmred. ulate the fire, that all will be subjected to an equal degree of heat throughout the burning. 174. The stone to be tried, after being broken into pieces as nearly equal in size as possible, and not ex- Stone broken -,. T n ' \ 1 . . into equal-sized ceedmg three-quarters of an mch cube, is m- P^®^®^" troduced into the crucibles, supposing several to be employed, each receiving the same number of fragments, if practicable. All the crucibles, with the covers on, are then imbedded in the fire and covered up with coals, so that the top and bottom portions will attain a bright red Smulteneously ^^^^ simultaneously. This last precaution is essential to the complete success of the process. In about forty-five minutes after the stone has reached a bright red heat, one of the crucibles is removed from Pieces removed at equal intervals the fire, the others following in succession at of time. intervals of forty-five minutes. In order to se- cure similar results with a single large crucible, two or three of the fragments are taken out at the end of the first forty-five minutes of bright red heat, and others subsequently, as the periods of time above designated are reached, allowing not less than four and a half hours to the last portions, or per- haps six hours, should the stone be very refractory, which will be sufficient to expel all the carbonic acid gas, and to carry some varieties of cement stone, if broken up as directed, to the point of incipient vitrification. 175. A long-continued bright red heat operates in a singular manner upon some argillaceous varieties of cement, border- HYDRAULIC CEMENTS, AND MORTAES. 115 mg on the intermediate limes, in conferring j^^^ continued apon them remarkable hydraulic properties and heat sometimes energy, which they do not possess at the point of complete calcination, but which may have been present in a lower degree before all the carbonic acid was expelled. In order to render certain the detection of stone possessing this property, when its presence is suspected, it is recommended to continue the calcination of some of the fragments for eight or nine hours. 176. By means of the several aforementioned crucibles, we obtain portions of the stone that are overburnt, other portions that are insufficiently burnt, and an intermediate class, among the several members of which will be discovered good cement, if the stone be capable of yielding it. There will also be indi- cated, to an extent sufficiently exact for practical deductions, the relative degrees of calcination adapted to the several va- rieties operated upon, with their exact and appropriate maxi- mum limits, respectively. These specimens, unless the stone belongs to some grade of common, meagre, or hydraulic limes, will not slake when sprinkled with water. Upon being sepa- rately reduced to powder in a mortar, mixed to a stiff paste with fresh water, and immersed in water either fresh or salt, they will indicate in their respective times of setting, their relative hydraulic energy, and approximately, — though subject to many individual exceptions in regard to the ultimate strength of the gangs, — their value as cements. 177. Whether the stone be suitable for cement, or otherwise, it will be found, with very few if any exceptions, that the underburnt fraerments, those which contain in ^ , , ^ ' ^ Underburnt stone the centre a small core of partially raw stone, as possesses supe- indicated by its density, color, and hardness, ^^^^^^^^^^J"- and which effervesce briskly with dilute hydrochloric acid, will be superior in hydraulic activity to the more highly calcined samples, and will set under water at 65*^ F., in periods vary- ing from five to fifty minutes. Those which do not effervesce with dilute acid, and have consequently parted with all their 116 PRACTICAL TREATISE 01^ LIMES, carbonic acid gas, will exhibit a less degree of hydraulic quick- ness, and will require a longer time by twenty-five to fifty per Some overbumt ^ent. to harden under water; while the over- varieties nearly burnt samples, those in which the calcination has proceeded to the verge of vitrification, will, in some instances, be almost entirely wanting in hydraulic activity, and in others, will have this property very much impaired. It by no means follows that this last-mentioned class is inferior to the others in the ultimate energy and strength The same not gangs or mortars ; on the contrary, some ce- necessarily of ments, the " Portland" for example, are much inferior strength. . i i i • i pi . i improved by this degree oi burning. Others, however, are rendered entirely worthless by it, so that M. Pet- ot's assertion that "it is equally possible to obtain plastic (that is hydraulic) cements by a super-calcination, and by an incom- plete calcination," must be received in a modified sense. Pet- Remark by M further remarks, that the fact most worthy ot Petot. Alleged notice is, that at the point of comjplete calcination •'instant of i .n / i i i i inertia" of not Only Will " the stone not slake, but ii treated cements. ordinary cement, will give a substance nearly inert." ''This instant of inertia of plastic cements, be- tween the points of incomplete calcination and supercalcination, seems to us a capital fact in the study of the substances. It ex- plains how a suitable limestone might escape discovery and be rejected as unsuitable, from a simple fault of calcination, which would not be a fault with fat lime, or with hydraulic lime." Does not inva- poi^^t of fact, there is no such " instant riably exist. qJ^ inertia^'' invariably existing between two points of maximum energy, in genuine cements. It may or may not be the case, according to the composition and molecular constitution of the stone. Moreover, some M. Petot's deduc- tion altogether cements have three points of maximum energy, too general. ^^^.^^ ^^^^^^ j^^^^ ^^^^ rj.^^^^ ^^I^.^j^ p^g, eess one, in a pre-eminent degree, at the point of vitrification, generally approximate to the intermediate limes in the nature HTDEAtTLIC CEMENTS, AKD MOKTAES. Ill and proportion of their constituent ingredients. M. Petot seems to have made general a deduction, on evidence drawn from a particular case only, and to have simply opened, far less exhausted, the investigation. 179. M. Yicat's opinion that a complete expulsion of the carbonic acid gas, although operating disastrously upon the intermediate limes, is necessary in order to fully develop the merits of genuine cements, must also be dis- carded as a rule, although individual cases in opSfo?^^^^^* * support of it are by no means rare. 180. If none of the samples from the crucibles, except those that are considerably underburnt, set under water, without being followed by cracks, disintegrations, or increase of volume, the stone belongs to that class termed intermediate or divid- ing limes, already mentioned, and should be rejected with scrupulous care, unless provision can be made Treatment re for burning it by itself, and for arresting the cal- quired for inter- mediate limes. cmation at the proper time. 181. By carefully subjecting, from time to time, the several undivided layers of a quarry to the trials above indicated, taking care to secure a faithful fulfilment of all the conditions specified, so that each will receive precisely the same treat- ment, we are able to ascertain with sufficient accuracy, and to keep constantly in view, the peculiar character of each kind of stone ; such as its appearance when properly calcined ; the requisite degree and duration of heat ; the correct limits of cal- cination ; and consequently the best mode of burning it on a large scale (whether by itself or mixed with the other layers), and the most advantageous proportions in which it should enter into a combination of the whole. 182. Experience teaches us that the physical Physical appear- ance of raw stone appearance of calcareous stones, which suni- no criterion of its cieiitly serves to distinguish and classify them, P^^^P^'^'^i^s- when in the natural state, into limestone and marbles of various kinds, furnishes no indication of their qualities after 118 PEACTICAL TEEATISE ON LIMES, calcination. Even a chemical analysis of the raw stone is to a certain extent unreliable, and deductions from it, under the most favorable circumstances, can only be regarded as tolerable approximations, and are not unfrequently contradictory. The hydraulic induration is due, in a great measure, to the chemical Source of combination of lime and silica, a union which is hydrauiicity. partially perfected in the dry way during the burn- ing, and is subsequently carried on and completed by the agency of water. The analysis of a cement stone after calcina- tion, should therefore show the commencement of this process by the presence of a certain quantity of silicate of lime. QUALITATIYE EXAMIISTATION OF HYDEAULIC LIMESTO^^^ES. 183. Hydraulic limestones are characterized, as a class, by Mineral their fine-grained, compact, or granular texture, characters. presenting a conchoidal fracture, yielding readily to a file or sharp-pointed instrument, and effervescing more or less freely, on the application of hydrochloric or nitric acids. 184. The prevailing colors are gray, bluish gray, grayish white, and drab, with intermediate shades. 185. The powdered mineral is more readily acted on by the acids than the massive form. 186. Hydraulic limestones will generally be found to con- tain silica^ alumina^ oxide of iron^ oxide of manganese^ limey magnesia^ potash^ soda^ with carbonic^ sulphuric^ and phos- phoric acids^ and occasionally some organic matter of a bi- tuminous nature. As some of these may be absent, it will be necessary to ascertain the character of those present, before proceeding to an ultimate qualitative analysis. 187. For this purpose, an unweighed portion Preparation. mineral is reduced to a fine powder in an agate mortar, and digested in one measure of water, for eight or ten hours, aided by the gentle heat of a sand-bath, HYDEAULIC CEMENTS, AND MOETAKS. 119 and the solution is then to be filtered clear, and divided into so many equal portions in wine glasses. 188. Nitrate ofharyta added to one of these *^ . . 1 . 1 -, . T Sulphuric acid, gives a white precipitate, which does not dis- appear on the addition of nitric .or hydrochloric acid, and indicates the presence of suljphuric acid, 189. By evaporating another portion to dryness^ in a sand- bath, at a gentle heat, and igniting the residue, subsequent addition of hydrochloric acid, followed by diluting with an excess of water, will cause the silica to separate as a gelatinous hydrated precipitate. 190. If another portion be treated with pure water of ammo- nia, and gives a pure white gelatinous precipitate, it indicates the presence of alumina^ or magnesia^ or both. In this case, hydrochloric acid must be added, until the pre- cipitate is re-dissolved, and the solution rendered distinctly acid. If, on the addition of ammonia, the pre- cipitate reappears undiminished in quantity, ^^nesL^^^ it contains alumina only ; if it be distinctly less in quantity, we may infer rhe presence of both magnesia and aluinina ; but if no precipitate now appears, it contains magnesia only. 191. If the precipitate above by ammonia has more or less of a brown color, the presence of oxide of iron or ma/ngamjese may be inferred ; but, if after re-dissolving and adding ammonia as above, the brown color an^tlngaTse. disappears, it is due to the oxide of mangam^ese only. Should the brown color still continue, it is owing chiefly to the presence of oxide of iron. 192. If, after the addition of ammonia, the solution be filtered to remove the magnesia, alumina, the oxides of iron and manganese, oxalate of ammonia be added to the filtrate, causing a white precipitate, it indicates the presence of lime, 193. K oxalate of ammonia be added, until all the lime be 120 PEACTICAL TEEATISE ON LIMES, precipitated, and then filtered, and the filtrate Potash and soda. evaporated to dryness, and ignited to destroy the excess of oxalate of ammonia, the residue if found to be sol- uble in "Water, indicates the presence of potash, or soda, or both. 194. If upon treating the last solution with pure bi-chloride of platinum, no precipitate appears, we may infer the presence of soda; but if a yellow precipitate appears, ^6>toA is present in the solution. 195. The yellow precipitate of potash and platinum having been collected on a filter, the filtrate treated with sulphide of hydrogen, and again filtered, to separate the excess of bi-chlo- ride of platinum, and then evaporated to dryness, a residue soluble in water remaining, indicates the presence of soda. 196. Eeturning to one of the original wine glass solutions, to which a portion of strong nitric acid must be added, if it be then dropped into a solution of molyhdate of Phosphoric acid. . . . ammonia, and a yellow precipitate appears, it indicates the presence of phosphoric acid. 197. The presence of bituminous matter is matter?^^^ shown by the odor or loss of weight upon igniting a specimen previously dried at 212°F. QUAI^TITATIYE EXAMmATION OF HYDKAITLIO LIMESTONES. 198. It is usual, in conducting this process, to ascertain : 1st. The specific gravity. 2d. The amount of hygrometric water. 3d. The amount of phosphoric acid. 4:th. The amount of silica and insoluble matter. 5th. The amount of alamina- 6th. The amount of oxide of iron. 7th. Tlie Programme. . t p o i rm amount oi oxide oi manganese. 8th. 1 he amount of carbonate of lime. 9th. The amount of sulphuric acid. 10th. The amount of potash and soda. 11th. The amount of carbonate of magnesia. 199. The specific gravity of the specimen to be analyzed having been determined, a portion of the mineral is reduced to HYDEAULIC CEMENTS, AND MOETAKS. 121 mie powder in an agate mortar, and a given quantity, say 50 grains, is placed in a platinum crucible previous- ly counterpoised with its cover. The crucible moStuj^^^*^ and its contents are then to be placed in a steam bath oven, and heated for two hours, when it is to be cooled in a receiver over sulphuric acid, and then quickly weighed. The loss in weight is the weight of the uncombined water. 200. The contents of the crucible must then be transferred to a beaker glass, and digested in strong nitric acid, to wliich a little hydrochloric acid has been added, for forty-eight hours, the action being favored meantime by the Phosphoric acid. gentle heat oi a sand bath. 201. At the termination of this process, the solution is to be filtered, an excess of molybdate of ammonia added to the filtrate, and the whole evaporated nearly to dryness. 202. During the process, the chlorine of the hydrochloric acid, aided by the excess of nitric acid, decomposes the ammo- nia of the molybdate of ammonia, and the molybdic acid goes down with the phosphoric acid, as jpliospho-molyhdate of am- monia^ in the form of a yellow precipitate, with the formula : 2 (3E'H40.P05) + 15(H0.4Mo03). Tliis precipitate is insolu- ble in water and in nitric acid. After diluting the mixture, and giving it time to settle, the precipitate is collected on a filter, washed in pure cold water, and while T T T . •/Ill Phosphoric acid. yet moist, dissolved m ammonia (the beaker glass being rinsed with the latter, and added thereto). 203. From this solution in ammonia, sulphate of magnesia precipitates all the phosphoric acid as ammonia phosphate of magnesia. This is to be washed with dilute water of ammonia, collected on a filter, dried, ignited at low red-heat, and weighed, — the filter having been burnt, and the ashes added to the rest. 204. Deducting the weight of the filter, every 100 grains of phosphate of magnesia thus obtained, contain 64.06 grains of phosphoric aoid j every 100 grains of phosphoric acid may represent 217.60 of phosphate of lime. 122 PKACTIOAL TREATISE Olif LIMES, 205. This determination of phosphorio acid being an inde- pendent process, the filtered solution left above Remark. . , ' , . , IS thrown away, and, as in the start, a new so- lution must be prepared. 206. Fifty grains of the same mineral prepared and dried as before at 212*^, are now to be dissolved in strong hydrochloric acid, the action being favored by the gentle heat of a sand Silica and insolu- bath for forty-eight hours, after which, the so- ble silicates. ^^^-^^ ^.^^^^^ ^.^^ ^^^^^^ filtered,— and the silica and insoluble silicates washed, dried, ignited, and weighed, are recorded. 207. The filtered solution from the preceding is then precip- itated by strong ammonia, and the precipitate, consisting of alumina, oxide of iron, and phosphates, after be- Alumina. . t/ ^ ^ u. j. ing well washed, is transferred while moist, filter included, into a strong solution of pure potash, which dis- solves out the alumina. 208. This potash solution, filtered from the oxide of iron, &c., is rendered acid by the addition of hydrochloric acid, and the alumina is then thrown down by an excess of ammonia, with a little sulphide of ammonium. 209. The precipitate thus obtained is washed with hot water, dried, ignited, and weighed. Deducting the weight of the fil- ter, we record the absolute weight of the alumina. 210. The oxides of iron and manganese remaining from the potash solution, are dissolved from the filter in hydrochloric acid, the solution carefully neutralized by am- Oxideofiron. ^ , f . . n > moma, and then, upon the addition oi succi- nate of ammonia, succinate of iron is precipitated. 211. Upon filtering this, and adding ammonia to withdraw the succinic acid, the residue is washed, dried, ignited, weighed, and the weight of the oxide of iron ascertained. 212. To the preceding filtrate concentrated to a small bulk by evaporation, sulphide of ammonium is added, causing a pre- cipitate of sulphide of manganese. The latter, collected on a HYDRAULIC CEMENTS, Am MORTARS. 123 filter, washed, dried, and thoroughly roasted^ changes the sulphide into oxide of manganese^ which is then weighed. 213. Return now to the first filtrate, caused by the addi- tion of ammonia to the original acid solution, and which con- tains the lime, magnesia, and sulphuric acid, ^ simultaneously. With the processes described, we precipitate the lime by oxalate of ammonia. Collect it after eight or ten hours repose, on a filter, and weigh it ; de- ducting the ashes of the filter, the weight of carbonate of lime is known. Every 100 grains contain 44 of lime. 214. The filtrate now contains a quantity of oxalate of am- monia, and ammoniacal salts, to decompose which pure nitric acid is added in excess, and the filtrate evapo- _ . T 1 1 . , . -, Sulphuric acid. rated to dryness. Kedissolve the residue in hy- drochloric acid, to which an excess of nitric acid has been added, and again evaporate to dryness. This dried residue of nitrates is now drenched with pure acetic acid, and then wash- ed with water. Upon the addition of acetate of harytes to the solution, the sulphuric acid present is precipitated as sulphate of harytes^ which is collected on a filter, dried, and weighed. Every 100 grains contain 34,31 of sulphuric acid. 215. The filtrate from the sulphate of barytes is now evap- orated to dryness, and transferred by a little oxalic acid and water into a small porcelain crucible, in which it is heated, and again evaporated to dryness, with an excess of pure oxalic acid, which changes the nitrates into oxalates. 216. The dried residuum thus obtained contains the alkalies and the magnesia, and must then be perfectly Alkaline ignited, to change all the oxalates into carbon- chlorides. ates. In order to separate the alkalies from the other ingredi- ents in this last residuum, it is dissolved and thoroughly washed through a filter with water. The dissolved carbonates contain- ed in the filtrate are changed into chlorides by the aid of a little hydrochloric acid, and then, evaporating the filtrate to dry- 124 PKACTICAL TEEATISE ON LIMES, ness and igniting, the saline residue is weighed, and the weigh of the alkaline chlorides of j[>otassium and sodium recorded. 217. Redissolving the mixture of alkaline chlorides in a small quantity of water, a solution of bi-chloride of platinum is added, and the whole of the chloride of potassium present is changed into the double chloride of platinum and potassium, appearing as a yellow, insoluble precipitate. 218. Being evaporated by a gentle heat to near dryness, weak alcohol is added to dissolve the chloride Potash. T 01 sodium, and any excess of the platmum salt which may be present. The yellow powder is collected on a filter, washed well with alcohol, dried, and weighed. 219. Every 100 grains indicate the presence of 19.31 of potash, or 30.51 of the chloride of potassium. 220. The weight of the chloride of potassium thus obtained, deducted from the weight of the mixed alkal- Soda. ine chlorides, gives the weight of the chloride of sodium. 221. Every 100 grains of the latter indicate the presence of 53.17 of soda in the limestone. 222. The magnesia which remains in the portion of the re- siduum which is insoluble in water, is now dissolved on the filter in diluted sulphuric acid, and after evapo- Magnesia. . , . . . . , . , . ratmg and igniting m a platinum . crucible, is weighed as sulphate of magnesia. 223. Every 100 grains contain 33.33 of magnesia ; 100 grains of magnesia indicate 210 of carhonate of magnesia. 224. It will be perceived by the foregoing process, that with the exception of the moisture, organic matter, and phosphoric acid, which we estimated in a separate quantity of the lime- stone, all the ingredients have been determined from a single weighed portion, and thus a check over the whole is secured ; for if the sum of the weight, of all the ingredients varies much from the 50 grains of limestone used at the outset, it is proof of errors in the process. HYDEAULIC CEMENTS, AND MOETAES. 125 225. Should the amount of silica and insoluble silicates be Ifrge, they should be fused with three times their weight of carbonate of soda, for three or four hours, by which they may be brought into a soluble condition, and the solution treated as in the foregoing, and the sum of the weights ascertained. TABLE lY. 226. ANALYSES OF HYDRAULIC LIMES, CEMENTS, TRASS, AND POZZUOLANA. 2.652 2.678 2.680 2.753 2.844 2.735 2.806 2.822 2.793 2.788 2.761 2.786 2.790 2.793 2.781 Dtash. ■a Ph m .62 .40 12.10 1.54 4.64 31.00 29.00 29.77 31.00 22.75 25.20 19.66 24.74 17.84 18.52 29.34 39.74 19.64 26.00 28.08 18.46 27, 11.10 19.80 6.16 3.14 16.74 4.60 2.18 5.74 6.00 7.52 4.64 5.72 4.22 2.34 2.52 4.40 3.96 .. 14, 18.20 34.225 49.530 18.00 17.75 12.00 24.00 9.375 57.0 44.5 23.94 5, 6.00 8.80 1.31 17.75 5.0 12.0 40.54 41.80 58.25 43.30 33.54 30.74 30.72 28.48 43.32 37.50 46.00 40.00 33.90 •ss.eo 53.3 65.0 45.63 60.00 17, 25.152 30.20 35.00 34.08 30.50 29.25 2.6 11.16 26.04 20.80 14.48 35.10 32.86 14.52 35.62 17.76 39.04 34.1 19.26 22.6 5.3 10.38 17.98 4.10 10 3.875 9.6 9.2 + 1.22 - 2.68 + 2.25 + 1.70 + 2.04 — .72 —1.60 —1.40 + .44 + 1.38 + .42 — .32 + .062 + .261 + ].0t) + .33 + 5.40 + .48 126 PRACTICAL TREATISE OK LIMES, REFERENCE. No. 1, from Utica, La Salle county, Illinois. No. 2, ' ' Sandusky, Ohio. No. 3, ' ' Cumberland, Maryland. No. 4, ' ' Shepherdstown, Yirginia. No. 5, ' * Layer No. 9 from High Palls, Ulster county, New York. No. 6, ' * do. No. 10, 11 (( (( u No. V, ' ' do. No. 11, (( (( (( (( No. 8, ' do. No. 12 11 11 (1 i( No. 9, ' ' do. No. 13, (( (( a {( No. 10, ' ' do. No. 14, U i( (( (i No. 11, ' ' do. No. 15, U (( (t 11 No. 12, ' ' do. No. 16, t( (( (( u No. 13, ' ' do. No. 17, (I 11 (( It No. 14, ' ' Layer No. 3, from Lawrenceville, Ulster county. New York. No. 15, ' ' Akron, Erie c ounty, New York. No. 16, ' ' Point-aux-Roches, Lake Champlain. No. 17, ' ' Layer No. 11, from Round Top Cement "Works, near Hancock, Md No. 18. Yassy (France) cement. No. 19. Theil (France) limestone (raw). No. 20. Theil hydraulic lime, from the above. No. 21, from Balcony Falls, Rockbridge county, Virginia (raw). No. 22, " do. do. do. do. (burnt). No. 23. Calderwood (Scotland) Roman cement (raw). No. 24. Sheppy (England) No. 1 cement stone. No. 25. do. do. No. 2 do. No. 26. Southend (England) cement stone. No. 27. Yorkshire do. do. No. 28. Harwich do. do. No.' 30: Pozzuolana, [ "'"^ ^reussart, at Strasburg. No. 31, from Lockport, Niagara county. New York (burnt, rather old). 227. The samples from Nos. 1 to 15, inclusive, were analyzed by Professor E. C. Boynton, Oxford University, Mississippi ; Nos. 16 and 17 by Lieutenant Caleb Huse, Asst. Inst. Chem., etc., U. S. Mil. Academy; ISTo. 23 by Professor F. Penny, Ph. D., F. C. S. ; ISTos. 29 and 30 by Berthier; the others were derived from reliable sources. 228. All the manufacturers of cement in the United States, pursue essentially the same process, in preparing the article for market. The only difference worthy of notice is, that while some use for burning the stone the ordinary perpetual kiln, of HYDEAULIC CEMENTS^ AND MORTAES. 127 a cylindrical form very nearly, terminating at the bottom in the inverted frustum of a right cone, in which the raw stone, broken into pieces of random size, but measur- . . Kilns used for ing not more than 8 in the longest dimen- burning cement sions, and the fuel (either bituminous or an- thracite coal) are mixed together in alternate layers, extending to the top of the kiln ; others prefer the perpetual " furnace kiln," in which the heat is applied by means of furnaces, suit- ably arranged for wood or coal, near the bottom of the kiln, In some localities, as at Utica, Illinois, intermittent kilns, burning bituminous coal, are used. 229. For kilns of the first above-mentioned class, when an- thracite coal is used, the latter should be broken up very fine. What is technically known as " second screenings," or " pea and dust," at the mines of the Delaware and Hudson Canal Company, and the Pennsylvania Coal Company, has been found to give the most satisfactory results in Ulster county, "New York, among the Kosendale Works, and can be obtained at a trifling advance on the cost of transportation from the mines. 230. Whether anthracite or hituminous coal be used for burning, the quantity requisite and proper to be used will de- pend not only upon its kind and quality, but upon the charac- ter and composition of the cement stone, the form and locality of the kiln, and the skill of the burner. In the works situated on the Potomac Piver, at Shepherdstown, Hancock, and Cumberland respectively, the Cumberland ^""^^ semi-bituminous coal is used for burning ; and, according to the opinion of Chas. H. Locher, Esq., proprietor of the James Piver Cement Works, at Balcony Falls, Virginia, is superior to the bituminous coal used by him, obtained near Pichmond, Virginia. 3,500 lbs. ^""^^ *— ' ' necessarj'. of anthracite coal is sufficient to burn 100 bar- rels of cement, of 300 lbs. each. 231. The ordinary perpetual kiln is set in operation by first filling it with thin, alternate layers of coal and raw stone, and 128 PRACTICAL TREATISE ON LIMES, Starting the kiln. then igniting it from below with light, dry wood. The layers of stone should not exceed six inches in thickness. The burnt stone is drawn out at the bottom, twice or thrice every twenty-four hours, raw stone and coal being Fig. 11. added in suitable proportions at the top after each drawling. Fig. 11 represents a vertical section, through the uaf kifns. ^^^^ draw-pit, of the kilns used in Maryland and Yirginia ; and Fig. 12, of those preferred in New York and Ohio. 232. There are serious defects in the method of burning above indicated, for which no easy and practi- of^burning!^^*^^*^ cable remedy has yet been devised, unless it be the furnace kiln or some modification of it. Some of the stone becomes so much overburnt, having reached the stage of incipient vitrification, as to be not only very vari- able in quality among the products of the sev- unSrburntTtone. ^^^^ ^^jers, and in many cases quite worthless, but exceedingly hard and tough, and conse- quently difficult to reduce to powder ; while another portion, HYDRAULIC CEMENTS, AND MORTARS. 129 usually the largest fragments, or those that have subsided too rapidly in the drawing, are underburnt and perhaps partially raw inside.* These also, being difficult to grind, should be selected out and subjected to a second calcination. Much of it, however, finds its way into the cement, and as superior activity the subcarbonates are known to be very prompt subcarbo- nates. in hydraulic energy during the incipient indu- ration, the injurious effect of the adulteration is not detected by ordinary tests. 233. Lying between the two varieties of burnt stone just mentioned, one of which quite generally, and the other quite frequently, produces cement p^od^c^s^^^^^ greatly inferior in quality to that which the stone, properly treated, is capable of yielding, we find another considerable portion, either too much or not enough burnt to develop the maximum energy and value of the cement, or in the general case, a mixture of both of these extremes, which offers no distinguishing physical feature by which it is possible to assort it from the rest. With some varieties of stone, these inferior products are yielded, by a heat of moderate intensity and duration, at a stage but SLtion varies little in advance of a condition of incomplete '^^^^ different stones. calcination ; with others^ they are produced as we approximate to a state of incipient vitrification; with aU^ they are essential elements in the individual properties of the stone, each quarry, and even the separate layers of the same quarry, possessing distinct characteristic features in this re- spect, which features are, withal, subject to considerable vari- ations within very narrow lateral limits. The converse of these premises is also true, to wit, that the state of maximum energy corresponds to a condition of incomplete calcination in some cases ; of complete calcination in others ; while in others still, it is only produced by vitrification more or less complete. We * It wiU be seen hereafter, that some varieties of stone require to be overburnt to the stage of incipient vitrification, to develop their full value as cements. 9 130 PEACTICAL TEEATISE ON LIMES, therefore see the necessity for resorting to what SamfnatioTor* appears to be the only efficient method of elim- stones neces- inatinff these elements of inferiority in hydran- sary. ^ ' . . lie cement, viz : a constant daily examination of the stone by adequate tests, combined with a calcination in separate kilns of all those layers in a quarry which possess marked features of dissimilarity. 234. Suitably burnt cement may therefore contain a nota- ble quantity of carbonic acid gas, and effervesce briskly with Each variety dilute hydrochloric acid, or it may not, accord- requires special ing to inherent properties in the article itself. Each variety requires a special mode of treat- ment, as to the duration and intensity of the heat to which it should be subjected. This great difference is, perhaps, mainly due to the variable amounts of silica and the alkalies which the stone contains, but is by no means entire - Sof!^ ly dependent on them. Other ingredients ex- ercise an important influence, particularly those which act as fluxes. The obscure reactions which take place at high temperatures, when a compound limestone is under treatment, cannot be accounted for by any general theory. It is fortunate that we are able, in a measure, to comprehend and estimate the results. 235. The great abuse to be abolished, is the mingling of dis- similar stones in burning. When this is done, most if not all Dissimilar stones Elinor evils will disappear. The idea that sev- shouldnotbe eral kinds of cement stone^ — some of which burned together. . i • i r> require twenty, some thirty, and some forty hours, calcination — can be burnt together, in the same kiln, is both theoretically and practically absurd. Very little extra expense would be involved in a suitable separation and classifi- cation of the stone during the process of quarrying, and few of the manufacturers would require any more kilns than they usually keep going. The least extensive works keep from three to five in operation, with one or two in reserve, and there HTDEAULIC CEMENTS, AND MOETARS. 131 are few quarries that would require a more extensive subdi- vision than these would accommodate. 236. Besides the several inferior products of the kiln just noticed, which are due to differences in the properties of the stone, there are others of a similar character, which have their origin in causes to a certain extent independent of these properties, and which, with proper precautions, are more or less under control : such as variations in the force of the draught through the kiln, due to changes either in the direction and force of the wind, or in the barometric state of ^ ^ . ' Certain causes the atmosphere ; neglecting to draw the burnt of bad burning . , , . . - . , within control. stone with the requisite care, taking perhaps equal quantities at stated times, which may be either too much or not enough, depending on circumstances ; not preserving the proper proportion between the fuel and raw stone, when adding these at the top, or not adding them at the proper time and in the suitable quantities ; irregularities in the settling of the stone in the kiln at each drawing, which result in some portions being exposed to the heat a much longer time than others ; the formation of " cinders," or vitrified pieces of stone, which adhere together or to the sides of the kiln, choking the draught, and retarding the expulsion of the carbonic acid gas : these, and many other variable causes, will always operate to such an extent as to render the proper calcination of the cement an operation of the utmost delicacy, and one requiring on the part of the manufacturer, a high order of intelligence, experience, and skill. Even supposing that all the stone yielded by a quarry and introduced into the cement is alike in compo- sition and character, and requires the same treatment in burn- ing, the theory upon which this practice of mixing the fuel and stone together in the kiln avowedly rests, is singularly at fault, and will by no means bear a critical examination ; for, inasmuch as all the coal is consumed, or sup- Theory of mixing posed to be consumed, during the calcination,— the stone and fuel , . . , , , not tenable. otherwise it is drawn m the cement and ground 132 PEACTICAL TREATISE ON LIMES, up in it ; — and as the proportion between the amount of fuel and raw stone, as well as the times of drawing the kilns and the quantities drawn are also pre-established ; and as no provi- sion is made to regulate the force of the draught, with a view to anticipate in a measure the intervention of one of the principal causes of variation referred to, it virtually assumes that a moderate heat, long continued, and a high heat, pro- portionally short in duration, will produce identical results, a premise which, with all its apparent plausibility, is directly opposed to the teachings of experience. 237. A perpetual "flame" or "furnace" kiln, for burning either lime or cement, patented by Mr. C. D. Page, of Roches- ter, Y., has recently been extensively introduced into the western part of the State of New York, which is intended to obviate some of the most glaring defects of all that class of kilns which require the fuel and stone to be mixed together. Either wood or coal may be used for fuel, although the details of the arrangements for supplying the heat are not exactly the same in each case. Figs. 13 to 18 represent sections of these kilns, whose horizontal section of the interior of the cupola is, it will be observed, of an oval or elongated form, with grates and flues ranged along either side. The conjugate axis of this oval, on a level with the fire, should not exceed five feet six inches. Its traverse axis may be increased to any length necessary to attain a given capacity, the coal-grates being correspondingly prolonged ; and when the enlargement is considerable, suitable openings for drawing the burnt stone being made at the proper intervals along the sides. A little above the point where the flame plays directly upon the stone, small horizontal openings, Q, called " peak holes," are provided, which extend through the walls of the kiln into the cupola, and through which the progress of the burning may be ascertained from time to time, with a view to regulate the times of drawing the burnt stone, and the amount to be drawn. At the bottom of the kiln, and dividing the lower part of the cupola into two symmetrica] HYDEAULIC CEMENTS, AND MOETARS. 133 parts, a vertical division wall, O (Figs. 14, 15, and 16), is placed, which extends a little above the level of the furnaces, the object of which is to prevent a horizontal draught through the kiln. In burning common lime, this is sometimes omitted, or replaced by a wedge-shaped " air-saddle," through which a current of cold air constantly passes, which divides and gradually cools the lime as it falls below the fires, thereby rendering it less liable to injury from spontaneous slak- ing. 238. All who have used this kiln, whether for lime or ce- ment, so far as any statements have been received from them, consider its success perfect, and dpu-tk of it in the highest terms. Mr. Lemuel Thompson, or Koclieste.i N" Y., who used one of them for burning lime, says: '^^ My kilr is but 28 feet in height, yet I have been able to burn 320 bnshels of perfect lime with 3|- cords of wood m twenty-foiii hours, and that, while the kiln was new. and of course, somewhat damj . The fires are applied at four points, producing a uniform heat on all points of the stone, and leaving not a stone unburnt. I find that I have burnt 44,000 bushels of perfect lime, w^ith 394 cords of wood, being 114 feet or wood to 100 bushels of lime on the average , during which time I let the fire go down many times, owing to want of market for the lime, and by so doing, losing a large amount ol heat. 1 never drew the kiln down the entire period of my running it ' 239 One of them is in use for burning cement at Akron, Erie county IN Y,., by Messrs. Newman & Bro. Under date of March 12th, 1859, these gentlemen say : " We are now burning ^>ur 100 barrels, on account of the dulness of the market, — we can burn 130 barrels every twenty-four hours with three Gords of wood. The peculiar shape of the cupola and furnaces are such, that the cement is perfectly and uniformly burnt, which adds 20 per cent, to the value of our cement over that obtained by the old mode of burning. Now, we know just what we can depend upon every day ; we get no raw stone, no 134 PRACTICAL TREATISE ON LIMES, cinders, nothing but pure cement. We can grind one-fourth nioi'e of this cement and with less power." -A. Eig. 13. Fig. 14. Fig. 13 shows a front elevation of the kiln witli ten furnaces, designed for anthracite coal, although bituminous coal may be used in it, without any change being required. A sec- tion of the same, through A B, is represented in Fig. 14, and through C D, in Fig. 15. When wood is used for burning, the kiln is constructed, as represented in Fig. 16, with four' fur- naces, and in Figs. 17 and 18 with two furnaces. The parts marked K, show the crib at the top of the cupola ; L and M, are timbers intended to bind the walls together ; Q, are the peak holes, through which the progress of the burning can be watched ; R, the feed ovens, for heating the coal, before it HYDEAULIC CEMENTS, AND MOETAES, 135 passes throiio'li the dampers, S, into the furnaces, T ; U, the ash-pits ; Y, the draw-pit ; and W, a platform in front of the furnaces. Fig. 17. 240. In order to have the advantages claimed for this kiln f ul I y tested, under circumstances that would lead to conclusive results, it was suggested to the Newark & Rosendale Company 136 PEACTICAIi TEEATISE ON LIMES, to give it a thoroiigli trial at their works in Ulster county, to which they readily consented. They adopted the coal-burning pattern (Figures 13, 14, and 15), which was erected during the autumn of 1859, under the personal supervision of the patentee. 241. The value of the flame Tcihi^ as compai-ed with the draw kiln, in which the stone and fuel are mixed together in alter- nate layers, may be inferred from the results given in Table Y. The cements used for the mixtures recorded in this table, were produced by combining, in equal proportions, the upper and the lower series of cement layers as developed in the quarries of the I^ewark & Rosendale Company, at Whiteport, Ulster county. New York. This is the same combination which that company makes use of in manufacturing for the market. In Table Y., the two cements under trial are designated Flame Kiln cement and Dram Kiln cement. They were samples of two lots made on the same day ; one having been burnt in the new and the other in the old form of kiln. 242. TABLE Y. Shows the ultimate strength of rectangular parallelopipeds of mortar (2" x ^" X 8"), from cement calcined in different kilns, formed in vertical moulds, under a pressure of thirty-two pounds per square inch applied at the upper end until the mortar had " set," and broken on supports four inches apart by pressure from above, midway between the points of support. The mor- tars were kept in a damp place for twenty-four hours, and then immersed in salt water. Age of mortars, ninety-five days. 243. Ohservations on the following Table. — The Draw Kiln cement of the following table was not quite so quick-setting as the Newark & Rosendale cement usually is. It is possible that the mortars made from it are correspondingly inferior in strength and tenacity ; although such a result would not, by any means, necessarily follow. Neither of the cements in Table Y. comes up to the standard quality of the best Eosea* HYDRAULIC CEMENTS, AND M0RTAE8. 137 TABLE Y. Composition of the mortar. ^3 Mame kiln. Draw kiln. Flame kiln. Draw kiln. Pure cement (stiff paste.). Dry cement vol. 1, Sand vol. 2, (stifi' mortar.) 499^ lbs. 360f 462' 510 447 529 541 I' 573 470 462 400' 400 322 314 391 369 337 353 369^ 373 267 259 297 307 314 353 341 279 291 220' 291 291 248 244 197 y22S-i\ lbs. 197 202 204 209 213 J 313ff Rtf: dale brands. They both range low in their breaking weights. As they were derived from one day's yield of quarry, and were manipulated and broken consecutively under the same condi- tions, the inference is, that sudden variations in the quality of the stone enter largely into the causes of this inferiority. In 138 PEACTICAL TREATISE ON LIMES, fact, it is upon this hypothesis only that many striking dis- crepancies in the resistance of cements from the same quarry, treated precisely alike, and brought into market during the same month, can be explained. This illustrates the necessity of the precaution adopted and adhered to in all the trials reported in this work, of never assuming identity in quality of separate sam- ples from the same manufactory, or even from different barrels of the same cargo, and of preserving within the range of each series of experiments, the means of an independent comparison of results. The cement used for Table Y., paragraph 242, and Table XXYIL, paragraph 547, for example, came from the same quarry, were identical in the proportion adopted for combining the several strata, and were treated in precisely the same man- ner ; yet in one the breaking weight of the cement paste, without sand, is only 499|- pounds for the flame kiln product, and 360| pounds for that of the draw kiln ; while in the other (burnt in the draw kiln), it reaches as high as 1,002 pounds, and it is only when about 133 per cent, of lime paste is added, that the inferior limit of 360f pounds is approximately reached. This affords another proof of the necessity of keeping a close and constant watch upon the quarries and kilns, and of pursuing a rigid sys- tem of daily tests, to guard against deterioration in quality. 244. Perpetual kilns are always to be preferred to those that are intermittent^ for burning either lime or cement, on account of the smaller quantity of fuel which they consume. As the object is chiefly to expel the water and carbonic acid, for which a bright red heat is sufficient, the most crude devices are some- times resorted to, in order to accomplish this result. For making common lime, a rude pile of logs, burning in the open air, with the limestone thrown on the top, has frequently been made to answer. Cement, in case of necessity, might also be calcined in the same manner. As its manufacture, however, is seldom resorted to, except to supply a somewhat extensive demand of trade, and as its calcination requires considerable HTDEAULIC CEMENTS, AND MOETAES. 139 ekill, to produce an article of even medium quality, this primi tive mode is seldom resorted to. Of all known methods of burning, it is tlie most expensive in the consumption of fuel. 245. For burning common lime, the simplest form of kiln in common use in Europe (and with some slight modifications, in the United States), is that represented in Fig. 19, in which wood Fig. 19. is used for fuel. This kiln is circular in horizontal section, and is generally constructed of rough-hammered limestone without mortar. It is usually located on the side of a hill, so that the top is accessible for charging the kiln, and the bottom for sup- plying the fuel, and drawing the burnt lime. The largest pieces of the stone to be burnt are first selected and formed into an arch, c, c. Above this arch, the kiln is filled by throwing the stone in loosely from the top, taking the largest first, and the smaller pieces afterwards. These latter are also piled up above the mouth of the kiln. The arched entrance, C, afibrds a convenience for supplying the fuel. 246. A necessary precaution in using intermittent kilns of 140 PEACTICAL TREATISE ON LIMES, this class is, that the heat should be raised gradually to the re- quired degree. There is a controlling reason for this : a sud- den elevation of temperature will cause a sudden expansion of the stones, c, c, c, and the moisture will be driven off with such force as to rupture them in many cases. As these stones are of irregular shape and unconnected with mortar of any kind, the consequence might be a downfall of the entire contents of the kiln, and of course an interruption of the burning. Moreover, a too sudden elevation of temperature might cause many of the stones to break up into small pieces, and thereby seriously choke the draught, without injuring the arch. 247. In all intermittent kilns, there is an enormous waste of fuel, as tlie furnace must cool each time it is discharged^ and the quantity of fuel expended in raising the contents of the kiln, as well as its thick side-walls, to the point necessary to burn lime, has to be repeated each time the kiln is recharged. There are other defects : the stone nearest the fire is liable to become injured by overburning, before the top portions become fully caustic. 248. A better form of intermit- tent kiln is shown in Fig. 20. Be- sides the outer wall of stone mason- ry, there is an interior one of fire- bricks. The fireplace, J, rests on a permeated brick arch, through which there is a sufficiently free cir- culation of air, to secure the neces- sary draught. 249. Perjpetual or draw kilns are intended to obviate the evils of irreg- ular calcination, and useless expense of fuel, attendant on inter- mittent kilns. A very simple form of perpetual kiln, for burn- ing lime with coal interstratified with the stone, is represented in Figs. 21, 22, and 28. It is much used on the continent of Europe. The interior is an inverted frustum of a cone, from HYDEAULIC CEMENTS AND MORTAKS, 141 -/p/- -> — Fig. 21. five, to five and a half feet in diameter at the bottom, and from ]iine to ten feet at top, and thirteen to fourteen feet high. It may be hirger. This is generally surround- ed by a thick, circular wall, from twenty to twenty-one ^'^S- 22. feet in diameter, pierced at the bottom Fig. 23. with three apertures for drawing the burnt lime. The draught may be regulated by doors placed at the en- trance to the apertures. A kiln of this form and of the dimensions indicated above, ought to yield about 500 cubic feet of quicklime every twenty- four hours, with a consumption of about two tons of coal. The quantity of coal, however, varies considerably with its kind and quality, and with the character of the stone to be burnt ; some reaching as high as one-fourth of the weight of the limestone. 250. In all kilns of this description, when the stone and coal are mixed together, the burning is started by first placing a layer of light- wood at the bottom of the kiln, then a layer of coal on the wood, and then a layer of limestone. Layers of coal and limestone follow alternately, until the kiln is filled, and the stone is piled upon the top of the kiln. When the lime near the bottom is sufficiently burnt, the drawing of it 142 PRACTICAL TREATISE 01^ LIMES, commences, and may follow constantly at intervals of lialf an bonr. In some localities, it is customary to draw but three or four times every twenty-four hours. 251. In the consumption of coal, a small quantity of ash is produced, which is easily separated from the burnt lime. Wood is not so easily distributed as coal, uniformly through the kiln, on account of the difficulty with which it is reduced into small pieces ; and even if it could be thus distributed, the large quantity of ash which it produces, taken in connection with a more or less considerable quantity of small fragments of stone, caused by the disintegrating influence of heat, would have a ten- dency to interfere seriously with the draught of air through the kiln. As before remarked (paragraph 237), Page's kilns are used for burning both cement and lime, in the western part of the State of 'New York. These kilns were introduced into Maine four or five years since, for burning Thomaston or Rock- land lime. They have received various modifications in form i Fig. 24. ' Fig. 25. md detail since that time. Figures 24, 25, 26, and 27 repre- sent a stack of two of the kilns now in general use in Eockland. 252. When lime-burning is conducted on a small scale in one kiln, two furnaces for the wood are introduced on op- posite sides of ihe shaft, saving v ixes on the same diame- HYDKAULIC CEMENTS, AND MOETAES. 143 ter. On a third side is placed the liole for drawing the burnt lime. Fig. 26. Fig. 27 253. In burning in any perpetual wood-burning kiln, it is essential that the draw-hole be kept tightly closed, except while drawing the burnt lime, and to regulate the draught entirely by the furnace doors. 254. Soft wood is used for lime-burning in Ilockland, such as hemlock, pine, spruce, and fir. About four cords (of 128 cubic / feet each) are required to burn one hundred barrels of lime, of 230 to 240 pounds each. This is a saving of about f of the fuel, as compared with the consumption of intermittent kilns. 255. When first starting the kiln, the portion below the level of the grate, called the thimble, is filled with light-wood. The interior of the kiln, nearly up to the top, is also lined with w^ood one stick deep, set up on end. These precautions are necessary, first, because the stone on a level with, as w^ell as below the grates, would otherwise be insufficiently burnt ; and, second, because the expansion of the stone, when heated, would injure the kiln, if the latter was compactly filled. The stone for burning is generally broken into pieces of various sizes, not exceeding ten inches cube. 256. A kiln holding enough stone to make 175 barrels of lime w^ll yield, after being started, about 100 barrels every twenty-four hours. The stone is exposed to the heat from forty-two to forty-eight hours. The lime is drawn every six oi 144 PRACTICAL TREATISE ON LIMES, eight hours, and oftener, if the capacity of the thimble is rather restricted. 257. Moist limestone is said to burn more readily than that which is dry, a circumstance which is explained by the fact that the presence of aqueous vapor not only offers no obstacle t\j the evolution of carbonic acid, but in reality mechanically aids the escape of that gas. 258. The great number of trials which have been made with the cement stones from different parts of the country, within the last two years, by subjecting them to every conceivable degree of calcination, point so uniformly to the necessity of Undoubted no exercising the utmost care in conducting this cessity of careful delicate operation on a large scale, that it is im- possible to gainsay its importance. They also establish beyond a doubt the magnitude of the error committed by manufacturers, in mingling the different varieties of stone together in burning. A few of the results will be briefly no- ticed, somewhat in detail. 259. The stone from Eockbridge county, Virginia, from which the James River cement is manufactured, was broken Stone from James ^^^^ P^^^^^ ^^^^^ * ^^^^ ^^b^' River Cement cined at a bright red heat, for periods varying from thirty-five minutes to eight hours. It re- quired three hours to expel all the carbonic acid gas, below which point, all the samples gave a quick and energetic cement, which hardened readily under water, without being subse- quently thrown down. The pieces burnt for thirty-five min- utes and one hour respectively, were both partially raw inside. After three hours' burning, a rapid destruction of hydraulic energy ensued, w^hich was in no degree restored when the heat was continued to eight hours. At this point, though not below it, some portions of the stone showed evidences of partial vitrifi- cation. For analysis of this stone, see Table lY. " The James Hiver cement," as prepared for market, effervesces briskly with dilute hydrochloric acid, and will indurate under water at 65o HYDRAULIC CEMENTS, AND MORTAES. 145 F., in four to five minutes, and in six to eight minutes, so as to support the light and the heavy testing-wires, respectively. 260. At Point-aux-Koches, Lake Champlain, a good cement stone is found, which will sustain, without injury, a somewhat longer calcination than that from Virginia. It has never been used for cement, but when properly burnt, will compare favorably with our best Roch^er.^^^*^"^" cements, in hydraulic activity. 261. Some of this stone was broken up and burnt as before, samples being removed from the fire at periods of 1, 2, 3, 4, 5, 6, and 7 hours, respectively. It required 6 hours to expel the last traces of carbonic acid gas. All the samples set readily both in the air and in water. That which had received seven hours' burning, however, even when allowed to harden in the air considerably longer than was necessary to support the heavy testing wire, would not bear immersion, but, after fifteen to twenty minutes, was reduced to the condition of soft paste. For analysis of this stone, see Table lY. 262. Two pieces of stone, from Lockport, !Nr. Y., were sent for trial, the composition of both being almost identical. They are argillaceous limestones strictly speaking, and contain no magnesia. For their analysis, see Table lY. The natural color of this stone is a grayish blue, the texture granular ; the first specimen was fine grained, the second rather coarse. Both were subjected to calcination in a crucible, samples being removed for trial at the expiration of the first half hour of brip-ht red heat, and , ^ , . From Lockport, subsequently at intervals of one hour, allowing k Y. nine hours to the last portions. 263. Of the ^r^^ specimen, all the burnings set rapidly in the air, but none of them perfectly sustained subsequent con- tinued immersion in water, except the three corresponding to one-half hour's, two hours', and nine hours', calcination. The sample burnt eight hours did not fall entirely to pieces on im- mersion, but swelled slightly and was soon covered with sev- 10 14(3 PRACTICAL TREATISE ON LIMES, ei-al deep cracks on the upper and lateral surface, in whicli eoni' dition it continued to indurate in a satisfactory manner, and underwent no furtlier change. The trials with this stone de- veloped some novel and exceptional properties. Among the several stages of calcination through which it passed success- ively, there were exhibited three points of maximum, and two of minimum, hydraulic energy. The two minima are found on either side of the sample burnt two hours, while the three max- ima correspond with the samples burnt one-half hour, two hours, and nine hours, respectively. In mixing with water, a consider- able elevation of temperature was exhibited by all the burnings. By working the paste over with the trowel as long as it remains warm, or by reworking it after it has commenced to swell and crack, it loses the objectionable and characteristic properties of the intermediate limes, and will retain its form in water ; but is, at the same time, degraded in hydraulic power to a level with the eminently hydraulic limes. The portion burnt nine hours turned a dark bluish green color, a few hours after it had been immersed in water. This may be due to the carbonate of the protoxide of iron present in the raw stone, which parts with its carbonic acid gas after a long exposure to heat. The pro- toxide thus formed would turn green by the absorption of water, becoming the hydrated protoxide of iron (FeO + HO). Tho green color is readily driven off by heat. A more probable hypothesis appears to be, that it is the peroxide (FcgOg), which is present in the raw stone. This, losing a portion of its oxy- gen at a high temperature, is converted by a new combination of its elements into the magnetic oxide (Fes04), a substance known, under certain conditions, to possess the properties of the pozzuolanas. This, however, does not account for the change in color. 264. The curves of the diagram, Fig. 28, will perhaps illus- trate the peculiarities developed during the calcination more prominently than a written description can. Let o be the ori- gin of co-ordinate, and the horizontal and vertical lines through HYDRAULIC CEMENTS, AND MOKTAES. 147 'fzTir 1 2 5 4 5 6 7 8 9 2 o' JfS /L ^ . . i f +(-+t- i i ^ - 1 2 Fig. 28. 6> the axes of abscissas and ordinates respectively. From o lay off on (9, d distances proportional to the several degrees of calcination, as determined by the duration of the heat. These distances are marked on the top horizontal line for every half hour, up to nine hours. On the perpendiculars, through the points thus determined, lay off distances from the line o, o\ that shall represent the hydraulic activity of the cements at the several stages of burning. These are positive ordinates, and lie above the line o, o' . The absence of hydraulic activity capable of sustaining immersion, or in other words, the rela- tive rapidity with which the paste yields to the solvent action of water, is represented by nesrative ordinates ^ ' ^ / . Curves of energy below the line (9, d ; the line o, o', therefore, in- of certain Ameri dicates the points of hydraulic equilibrium, so cements, to speak, at which the cements either part with or resume the power of " setting" under water, if immersed in the state of paste. A Gurve traced through the several points obtained with a single cement, is called the curve of energy of that ce- 148 PEACTICAL TREATISE ON LIMES, ment. The cements which furnished the curves of Fiii. 28. were from the following localities : No. 1. Cement, from Loci port, N. T., first specimen. No. 2. " " " second do. No. 3. " ** centre of Round Top Quarry, near Hancock, Md. No. 4. " " Stratum No. 15 of paragraph 21, from High Falls, Ulstei county, N. Y. No. 5. " " Balcony Falls, Rockbridge county, Ya. No. 6. " *' Point-aux- Roches, Lake Champlain. No. T. " " Stratum No. 1, from Martin & Clearwater's Quarry, Ulster county, N. Y. No. 8. " " Stratum No. 3, from Martin & Clearwater's Quarry, Ulster county, N. Y. 265. Ohservations on Fig. 28. — By examining the curves derived from the two specimens of Lockport cement, it is seen that : Ist. When burnt from i to f of an hour, both will set under water, and, in combination, would therefore make a good ce- ment when thus treated. 2d. Between f of an hour and \\ hours' calcination, the Observations on ^'^^ under water, while the second diagram. Fig. 28. will ; and the properties of the combination would depend on the proportion adopted. 3d. Two hours' burning exactly reverses this state of things, the first setting under water, while the second will not, and this condition obtains until the calcination is continued for ?>\ hours. 4th. Beyond this point, neither will set under water, until a calcination of 7^ hours is reached, when the first resumes its hydraulic action, and continues so, the second remaining as before. As there is no greater diversity among the eight varieties of cement represented in diagram. Fig. 28, than is ordinarily to be found in the several layers of the same quarry, which, ac- cording to the usual custom, are burnt together, we can to some extent realize, by an inspection of the diagram, the practical effect of the system now in vogue among manufac- turers. iryDEAULIO CEMEOTS, AND MOETAES. 149 5th. All the eight varieties, burnt from ^ to f of an hour, set under water, and when thus treated, would make a quick setting combination. This corresponds with the well-known fact that the subcarbonates are very actively hydraulic. 6th. Calcined two hours, four of them set well under water, and four do not. 7th. Burnt four and a half hours, three of them set under water, and five do not. 8th. Burnt six and a half hours, only two of them set under water, (and one of these two rather sluggishly), while six do not. Of these latter, however, No. 4 and 'No. 2 may be re- garded as intermediate limes ; while JSTo. 7 and No. 1 are inter- mediate limes at some stages of calcination, and ordinary hy- draulic limes, apparently, at others. For remarks on the stone which furnished curve No. 4, see paragraph 21, w^here it de- scribes layers nine to sixteen inclusive, of the deposit in Ulster Co., N. Y. 9th. Burnt eight hours, the specimens are again equally di- /ided, that is, four of them will bear immersion in water, and 'bur will not. 10th. It is evident that the quickest setting combination of the eight varieties of stone, would be secured by burning them separately, to that degree indicated by the highest point in their respective curves; wlJle the combination least likely to sustain immersion, would in like manner correspond with the lowest points in the curves. 11th. Inasmuch as the quickest setting cements do not always give the strongest mortars, while slow setting ones may excel in that respect, it may be inferred that curves which would represent the degrees of calcination corresponding to the several degrees of strength of cement gangs, varying with and dependent on the calcination, might difier very materially from those given in the diagram, which have especial reference sim- plj' to the hydraulic activity of the gangs, when immersed in the state of paste. Such mii*ves of strength could readily be 150 PRACTICAL TEEATISE ON LIMES, constructed, however, by making mortar prisms of the pro ducts obtained at the several stages of calcination, and sub- jecting them to the usual breaking test. Such a diagram, comprehending all the dissimilar layers of a cement deposit, and corrected from time to time, as often as the changeable character of the rock might require, v^ould furnish the only unerring guide to a proper calcination of the stone of the quarry. 12th. As all the specimens subjected to nine hours' burning liad parted v^ith the whole of their carbonic acid, while some of tliem reached the same condition in a much shorter space of time, it follows that M. Petot's deduction, that cement stone at the point of complete calcination" gives *' a substance near- ly inert," is by no means correct as a principle, but is only an improper generalization of results obtained in a particular case ; for the diagram shows that at every stage of the burning, some of the curves lie above the zero line, and therefore repre- sent more or less energetic cements. It is true that at six and a half hours' calcination, six curves out of the eight lie below that line, and might therefore, relatively speaking, be said to represent " inert substances ;" but with this exception, every stage of burning gives active cements from about one- half of the specimens under trial, while one specimen from the Round Top quarry (curve No. 3) was quick and energetic at every stage, after the first twenty minutes. 266. "We cannot do better perhaps in this connection, than to give a diagram of the curves of energy of several calcareous substances, as constructed by M. Petot. We know from the foregoing discussion that the one representing, or said to repre- sent, hydraulic cement (plastic cement, as it is therein termed), must refer to a particular case only. It is possible that the others do also. M. Petot does not inform us on this point, and our experiments have not extended far enough to enable us to speak with confidence on the subject. The curves are indi- cated in the diagram. Figure 29. 151 7^ Tlie numbers on the lower ;i -rizontal line (marked zero I'lJc'), represent the distances from the o point, propor- tional to some of the princi- pal degrees of torref action. Fig. 29. No. 1 corresponds to the degTee of moderate burning of bricks. No. 2 " '* thorough " " " No. 3 " " " complete calcination of fat lime. No. 4 " " " super-calcination of fat lime. On the perpendiculars through these points, distances are laid off, above the zero line proportional to the hydraulic energy of each particular product, at the several stages of calcination respectively. The curves of energy are the lines drawn through the points thus determined. A total want of hydrau- lic energy is indicated when the curve lies on the zero line. Curve No. 1 belongs to fat lime. " " 2 ** " hydraulic lime. " " 3 " " " (or plastic) cement. " "4 u calcareous clays suitable for pozzuolana. *' "5 " " clays not calcareous. 267. In the absence of any information as to the method pur- sued in obtaining these curves, and knowing from our trials that curve Ko. 3, said to represent cement stone as a class, does not so represent it, and, in all probability, was obtained from a single sample, it seems safe to infer, that M. Petot restricted his inves- tigations of the other substance to individual specimens also. "With the exception of fat lime, it is believed that all the sub- stances which he tried, represented in Figure 29, might be ex- pected to produce curves, as dissimilar in character as those obtained for American cements. 268. It would appear, from the results given above, that the hydraulicity of cements derived from the Capricious varia- T , . , . 1 . n during same quarry and bearmg almost identically calcination. 152 PRACTICAL TREATISE ON LIMES, the same composition, is subject to singular and apparently capricious variations during the progress of calcination. Al- though the diagram. Figure 28, does not exhibit the charac- teristic peculiarities in this respect of all the individual layers of any one quarry, experiments to elucidate this feature have been carried on with considerable minuteness of detail, and show quite conclusively that the principal, and it may be said, the only cause of the frequent failure to attain uniform results by any known method of calcination, lies in the obscure, because unstudied changes in hydraulic character, through which the stone successively passes during the burning. There are, it is true, many layers of stone that yield a really good and c, , energetic cement at any and all stages of cal- Some cements are o J t> good at all stages cination between the points of half calcination and complete vitrification ; and it luckily so hap- pens, so far as recent observation teaches, that this kind of stone is very extensively distributed throughout the country, and comprises at least one-half of the thickness of the deposits to which w^e now look for our supply, viz. : those in Ulster county, "New York, and on the Potomac and James Rivers in Maryland and Virginia. The negative character of some of the other contiguous layers of these deposits, as well as the positively injurious character of many, or rather, the indiffer- ently good as well as the really bad cement obtained by an They redeem the injudicious calcination of them, is thereby par- defects m others, tially redeemed, or, in a measure, counteracted, as it is the average aggregate result we obtain in all cases in practice. 269. JSTot unfrequently, as before remarked, the changeable Cements act like cements, as they may be termed, when burnt to Um^sTt^certain ^ certain point, possess in a marked degree all stages of burning, the objectionable properties of the intermediate limes,— setting rapidly when first mixed into a paste, and im- mersed in water, but possessing no permanence or stability ; while sometimes above and sometimes below this point, and HYDEAULIC CEMEOTS, AND MOETAES. 153 often both above and below it, a 2:ood cement is . , ' * Maximum and produced. At other times this condition of minimum hydrau- things is reversed, there being but one point of ^^^^^^ maximum, while there are two of minimum hydraulicity. Sometimes the substance conducts itself like imperfectly slaked common lime, and begins to swell up and soften the moment it is immersed, possessing not even the dangerous energy of the intermediate type; at others again, it appears to be almost entirely inert, like clay. The influence which these changes exert on the stren2:th and hardness of the result- ^, , o These changes ing cement, presents a subject for serious caU for serious mi • • 1 • 1 inquiry. inquiry. lhat those varieties which, at any stage of calcination, give intermediate limes, should be either burnt by themselves, and with extra care, or Cements that can else carefully excluded from the combination, produce interme- , - ^ ^ , - - diate limes to be there would appear to be no doubt ; unless, burnt by them- indeed, the precaution is taken to manufacture some time before and store them in bulk, several months before use. they are used. This is believed to be a specific remedy for the defects which belong to this type of cements. It, however, degrades them in hydraulic energy, as well as in strength and hardness, to a level with ordinary hydraulic . ^. , ' «^ Objections to the limes. 'No adequate trials of strength have last-mentioned T . -, ^ T . . 1.1 precaution. been made with any oi those varieties which, at any stage of calcination below that of incipient vitrification, part entirely with the power of sustaining immersion in water. 270. The results given in Table YI. were obtained with Layer ISTo. 12 of the deposit at High Falls, Ulster county. The table contains four kinds of cements designated sever- ally, Number One, N^umber Two, ISTumber Three, Number Four. They were obtained by burninsr the -n , ., ^ , Trials with Layer stone m a small kiln, about seven feet deep and No. 12, Ulster twenty inches to twenty-four inches in diam- eter, called a " try " kiln, and subsequently separating the burnt stone into four portions, differing from each other in the 154 PRACTICAL TREATISE ON LIME», degree of calcination which they had respectively attained. These after being ground, were passed through wire sieve No. 80, in order to secure a uniform degree of pulverization. 271. Numlxir One was underburnt stone ; the fragments, when broken open, showed a raw core, in the centre, of the natural color of the stone, though, on the exterior, they presented the appearance of having been sufficiently calcined. In the ordinary process of manufacturing SiclftS''^ cement, nearly all this variety is used. The . only precaution usually observed is to exclude those portions that might, on account of their hardness, endanger the safety of the machinery in grinding. In assort- ing the burnt stone, it is readily distinguished by its greater specific gravity. 272. Wwnber Two was selected by an experienced burner, as the inferior limit of complete calcination. ISTone of the frag- ments contained a raw core, and none showed Sldnation^^ J vitrification on the exterior. They effervesced with dilute hydrochloric acid very slightly. 273. Number Three was well burnt, and was selected to represent the superior limit of complete cal- calcination^ ci nation. All the carbonic acid gas was ex- pelled, but no vitrification had taken place. 274. Number Four was overhurnt and vitrified stone, commonly called " cinders " by the workmen. Sdnatfon^*^ ^ small proportion only of this variety finds its way into the cement manufactured for market. From its extreme hardness, a due regard to wear and tear of machinery suggests its careful exclusion. It usually occurs in masses that are glazed over and run together, and it is easily distinguished from the other portions of the kiln. 275. TABLE YL Showing the effect of different degrees of calcination, on the quality of hydraulic cement. The mortars were HYPKAULIC CEMENTS, AND MOETAES. 155 in the form of rectangular parallelopipeds, 2" x 2" X 8", which had set, under a pressure of 32 lbs. per square inch. They were allowed to harden one day in the air, and were then kept in sea-water. They were broken on supports four inches apart by a force applied at the middle. In all cases, the composition of the mortar was cement powder 1 vol., sand 2 vols. ; age of mortars, 95 days. Kind of cement. It was all derived from Layer Number Twelve, Ulster County, N. Y. Number One, underbumt. Number Two, inferior limit of complete calcination. , Number Three, superior limit of complete calcination Number Four, vitrified. 216 204 189 181 300 246 248 26.3 204 209 203 209 209 213 197 275 281 298 326 348 353 263 259 267 211 259 255 82 88 79 73 83 86 79 76 156 PPvACTICAL TEEATISE ON LIMES, Ohservations on Tabh VI. — The cements were fresh from the kiln. IN^umber One possessed the greatest degree of hydraulic activity, and required but ten or twelve minutes to set under water, so as to support the light testing wire. Number Two required twenty-five minutes ; Number Three, rhirty to thirty-five minutes; and Number Four, ninety to one hundred minutes, to attain the same degree of induration. Similar results, as regards simply the superior promptness of the initial energy of underburnt cements, were obtained with other strata from the same locality, as well as with stone from the Potomac and James Rivers. Each cement has, however, beyond the stage of incomplete calcination, its marked pecu- liarities of strength and hydraulic activity. 276. This property is so universal, that even common fat lime may be rendered moderately hydraulic, and the Uy of^under^*^^' ii^itial energy of hydraulic limes considerably burnt limes very increased, by suitable underburning. This in- creased activity, however, does not appear to be accompanied by a corresponding augmentation of the strength of the resulting paste, especially in the genuine cements, as seen by Table YI. 277. After the mortars of the foregoing table were mixed, the balance of the four varieties of cement was carefully preserved in a dry room for subsequent trial. At the end of six months, other prisms were made of the cement paste without sand The results are given in the following table : TABLE YII. Showing the breaking weight of rectangular parallelepipeds (2^' X 2^' X 8'^) of pure cement mixed stiff, of different de- grees of calcination, broken on supports four inches apart by a pressure at the middle. The mortars " set" under a pressure of thirty-two pounds per square inch, and were put in sea-water when one day old. and kept there until broken, at the age of HTDRAULIC CEMENTS, AND MOKTAES. 157 ninety-five days. The cement was measured by volume of powder. Kind of cement. Penetration of point in inches. g « o its Number One, underburnt. Numbe'- Iwo, inferior limit of complete calcination. . • U t( (I (i tl It (I Number Three, superior limit of complete calcination, u n ti n Number Four, vitrified .097 .107 .106 .195 .075 .050 .050 .060 .130 .100 .150 .106 .090 .090 .170 .187 .187 ,182 .127 .100 .100 .112 .230 .170 .260 .170 .150 .165 615 689 621 542 519 689 662 546 443 863 595 918 894 -654 lbs 608 " 494 " 817 " The results given in Table YII. were so difierent from those obtained for. Table VL, in the character assumed by the vitrified cement, that other trials were made with the same kind of stone in order that all doubts, as to the relative value of the products, derived at the several stages of calcination, might, if possible be removed. The same sized parallelepipeds (2" X 2" X 8") were made without pressure (some with and some without sand). These were put in sea-water when one day old, and kept there, until broken at the age of sixty days, the sup- ports, as usual, being four inches apart. Several trials gave the following average results. The cement was measured by volume of dry powder. TABLE YIII. No. of ce- ment. Degree of caleination. Breaking weight of prisms of Cfment with- out sand. Cement, 1. Sand, 2. 1 2. 4 557 lbs 646 " 513 " 670 " 190 lbs. 224 *' 143 " 237 " Number Two, inferior limit of complete calcination Number Three, suuerior limit of complete calcination 278. Ohservations on Tables VL, YIL, and. YTIL—Vcl^ dis- 158 PEACTICAL TREATISE 01^ LIMES, crepancies between the breaking weights of Number Four (vit- rified cement) in the three Tables, appear irreconcilable on any other supposition than that of error in recording the results of Table YL It is possible that cements I^umber Three and ISTum- ber Four, may have been exchanged accidentally while making the mortars of Table YL By making this transposition in Table YL, that is, by exchanging the names of cements Num- ber Three and Number Four; the results of the last three tables pre more readily comprehended, cement Number Four giving the strongest of the four mortars in each case, and cement Number Three, the weakest. 279. We will now, as a matter of interest, con- struct, in the manner in- dicated in the 11th obser- vation on Fig. Sgth. 28, the curve of strength of the cement used for Tables YL, YIL, and YIIL, bas- Fig. so. od on the several progressive stages of calcination, as described in paragraph 266, and the breaking weights given in the three tables. 280. These breaking-weights were obtained under four vary- ing conditions, as regards age and kind of mortar, and the curve of strength for each is given in Fig. 30. 281. These conditions (see Tables YL, YIL, and YIIL,) are : 1st. Cement vol. 1, sand vol. 2 2d. Pure cement 3d. Pare cement . . . 4tli. Cement vol. 1, sand vol. 3 Age 95 days, gives curve No. 1 Age 95 days, gives curve No. 2. Age 60 days, gives curve No. 3, Age 60 daya, gives curve No. 4. 282. The abscissas are laid off on the horizontal line from the zero point to the numbers 1, 2, 3, and 4, in lengths corre- Bxplanationof ^ponding to the four degrees of burning (para- Figure 30. graph 266). On the ordinates through the points HYDKAULIC CEMEInTS, AND MOETAES. 159 1, 2, 3, and 4, distances proportional to the strength of the prisms, at the rate of 100 lbs. to i of an inch, are laid off. The points thus obtained, fix the position of the curve. 283. The dotted branch a h, of curve No. 1, corresponds to results given in Table YI., on the supposition that they are there recorded correctly, while the full branch supposes the exist- ence of the error already referred to above, to wit, that the average breaking weights of mortars from cement Number Four, Table VI., is 276 lbs., and from cement Number Three, 82 lbs. and not as recorded. 284. The fact that curves Nos. 2, 3, and 4 give two points of maximum strength, while curve No. 1 does not, except under the supposition of error, affords a geometrical confirmation of this hypothesis. 285. We have not constructed the curve of strength of any of the American cements, except that made from layer No. 12 of the Ulster Co., N. Y., deposit, recorded in the last three tables, and illustrated by Fig. 30. 286. We see that a proper treatment of this stone requires that the calcination should stop at or below the inferior limit of complete calcination, or be carried to the point of vitrifica- tion, and that, at the point of superior limit of complete calci- nation, and just before vitrification sets in, the mortars are deficient in strength. The impro- ^sed^n burnhig. priety of mixing this stone, for burning, with another differing from it in the period or periods of time neces- sary to reach the maximuin points of the curve of strength ; or, of burning many kinds of stone together, whereby several maxima and minima of strength may be developed simultane- ously, needs no comment. 287. If the layers of cement rock preserved individually a uniform character over extensive areas, it would be a simple matter to test them all in the manner above described, con- struct their respective curves of strength, and establish for the manufacturers the necessary rules and precautions for burning ; 160 PRACTICAL TREATISE OTf LIMBS, but the cliangeable character of the deposits renders such a labor necessarily one of constant recurrence, and one of the appropriate duties of the manufacturer himself. We have not therefore undertaken this work, except so far as seemed necessary to illustrate the subject. 288. The cement stone, after calcination, is reduced to pow. der between ordinary millstones, after being first passed through a ''cracker," which crushes it up into pieces not ex- ceeding the size of a pea or a hazel-nut. The cracker is made of cast iron (Figs. 31 and 32), and consists es- sentially of a frustrum of a solid cone called the core, working concentrically within the inverted frustrum of a right hollow cone, both being pro- vided on their adjacent surface with suitable Fig. si. grooves and flanges for breaking up the stone as it passes down between them. The elements of the lower portions of both cones make a smaller angle with the common axis than those pertaining to the upper portions, with a view to lessen the strain, and the effects of sudden shocks upon the machinery, by securing a more gradu- Fig. 32. al reduction of the stone to the required size. These lower portions being subject to very rapid wearing, are made of chilled iron, and are moreover cast in separate pieces, in order that they may be replaced by new ones, as occasion requires. The greatest diameter of the core at the top, including the flanges, is 9 inches, at the bottom 5^ to 6 inches, and its height is 15 to 16 inches. The diameter of the shell, measured within the largest flanges, is 14 to 15 inches at the top, and 5i to 0 inches at the bottom, a trifle greater than that of the core ; its height is 16^ to 18 inches. One cracker of this size, working with a velocity of 80 to 85 revolutions per minute, is sufficient for a mill grinding 250 to 300 barrels per day. It is custom- ary to provide one cracker for every two run of stone. For the cement mills, the French Burr stone is generally used in HYDRAULIC CEMENTS, AND MOETAES. 161 tr.LF ronntry, except in Ulster county, New York, where the Shawangunk conglomerate or grit (Formation TV. of Professor Rogers' classification of the Rocks of Pennsylvania and Vir- ginia) has been fomid to be an excellent substitute. In the vicinity of High Falls, it occurs only a few feet below the ce- ment deposit, and in Rochester township, a few miles further west, is extensively quarried for millstones. These are of va- rious sizes, from 2-J to 5 feet in diameter. When driven with full power, one run of the largest size will grind, on an aver- age, 300 pounds of cement (one barrel) in four minutes, as or- dinarily prepared for market, or in six minutes, if ground ex- tra fine, as it should be. To carry the degree of pulverization beyond a certain point involves a consumption of either power or time which appears to be strikingly out of proportion to the results secured thereby. For example, a cement of which 85 per cent, will pass a fine wire sieve of 6,400 meshes to the superfi- cial inch (No. 80), cannot be ground so that 95 per cent, will pass the same sieve without doubling one or the other of these func- tions. This accounts for the fact that the cements sent to market are, as a general thing, imperfectly ground. The capa- city of a cement to receive sand, other thins^s ^ ' ^ Cement apt to being equal, varies directly with its degree of be ground too fineness, which is, therefore, for this reason, an important consideration to consumers to say nothing of other advantages secured by approximating to an impalpable powder. Not more than 8 per cent, of a cement should be rejected by a sieve of 6,400 meshes to the square inch. 289. In practice, one solid cubic yard of raw stone is found to yield an average of 2,700 lbs. or nine barrels of cement, ex- clusive of those portions rejected in assorting the burnt stone. 290. The Rosendale cements are packed in barrels from the mill-spout as fast as ground. In Virginia, the custom prevails of storing the ground element in bulk, until sent to market, a practice which, besides involving additional expense, injures the hydraulic quickness and energy of all cements, except. 11 162 PEACTICAL TREATISE ON LIMES, those containing too much free lime, or which border on the intermediate limes. The objectionable properties, in such cases, disappear in time, but invariably at the expense of the hydraul- icity. It must be admitted that there are very few quarries in this country, that do not assume such a character at times, that the cements are of better quality, and may be more safely used by ordinary mechanics when six months old, than when freshly ground. 291. Attempts have been made to economize the power necessary to produce a very high degree of pulverization, by passing the ground cement through fine wire bolts. It was found, however, that these bolts required Bolting cement. i i . such irequent renewal, as to render their use in every way inexpedient. 292. The color of the manufactured cement, being due prin- cipally to the presence of a small quantity of oxide of iron, and sometimes of manganese, or to the carbonates of these oxides, which, for all practical purposes, are conceded to be a passive ingredient in hydraulic mortar, should be a matter of indiffer- ence to consumers, except in special cases, as in exterior stucco work or ornamentation, in pavements, and in the fronts of edi- fices, when a particular shade of color is sought for. In fact, the presence of a large proportion of the coloring principle, like that of any other inert substance, might be expected to have a tendency to deteriorate the quality of the mor- Color of cement. ,*,...,. , . tar, by dimmishmg the cohesive strength of the cementing substance, and, therefore, if taken into con- sideration at all, ought, at least, to direct suspicion to the darker varieties. On the contrary, there exists among dealers generally, a strong prejudice in their favor, which, if ana- lyzed and traced to its source, will be found to have had its origin, not in opinions based upon experiment, or even upon a theoretical examination of the substances, but in the per- nicious system of building by contract, so extensively, and it might almost be said, so exclusively practised in this country, HYDKAULIC CEMENTS, AND MOETARS. 163 and under which nine-tenths, and perhaps nineteen-twentieths of our masonry work, is superintended by men whose utmost endeavors are directed to " economy of construction." They, therefore, encourage and cater to a popular belief of their own creation, that a dark colored mortar is necessarily a rich and energetic one, and give the preference to those cements which will sustain a large dose of sand, without presenting the ap- pearance of having been injuriously diluted with it. The fact that some of the cements first discovered and manufactured in this country on the line of the Erie Canal, and in Connecticut Yalley, which were little more than eminently hydraulic limes, were light in color, while the excellent Parker's Koman ce- ment, which appeared here soon after, was very dark-colored, renders it more difiicult to abate this prejudice. 'No import- ance whatever is accorded to the fact, that the quickest setting cements manufactured at the present day happen to be light- colored, and that the Portland cements, both natural and arti- ficial, though rather slow-setting, have never been surpassed in strength and hardness by any of the natural cements of this country or Europe. 293. As to the oxide of manganese, the idea, at first promul- gated by the chemist, Bergmann, and subse- quently endorsed by Guy ton de Morveau, that ^^^^ of manga- the hydraulic property was due to the presence of a few hundredths of that substance, has long since been abandoned, for the obvious reason that some of the best ce- ments known are entirely devoid of it. 294. The extent to which the oxide of iron exerts its influ- ence, if at all, upon the induration of hydraulic mortars, is still a subiect of controversy, as well as the ques- , , , . \ . IP.-, Oxide of iron. tion whether the virtues claimed lor it by some writers, rest with the uncombined peroxide or protoxide, or with a carbonate of one of these bases. The fact, however, appears to be well established that their presence does not con- fer hydi'aulic activity, whatever may be their action at some 164 PRACTICAL TREATISE Ol^ LIMES, subsequent stage of the induration. We also know that, al- though some of the best cements known, as, for instance, the cement of Yassy, in France, and Parker's Roman cement, con- tain a comparatively large amount *of the carbonate of the protoxide of this metal, the former .Uto? and the latter .06, there are many good cements in the United States which con- tain less than .02, while there are some meagre, non-hydraulic limes, which contain, after calcination, as much as .10 of the protoxide. It has been suggested by Messrs. Malaguti & Du- rocher, in a paper submitted to the Academy of Sciences in July, 1854, that the presence of the peroxide in hydraulic mor- tars exposed to the action of sea-water was beneficial. The fol- lowing conclusions to which their experiments led them are very general, and were to be considered at the time as simply initiatory to a more extensive examination. 1st. Those cements which are reported as the best for " re- sisting the destructive action of sea- water, always contain a notable quantity of peroxide of iron." 2d. Certain combinations of silica, alumina, and lime " give, under otherwise similar conditions, very different reactions, according as they are deficient in, or contain large quantities of oxide of iron." 295. M. Yicat throws the weight of his high authority against the inference to be drawn from these two propositions, and arrays a number of "well ascertained facts in direct oppo- iiition to that method of explaining the resistance to the effects of sea-water," in the form of tabular statements, ex- hibitinei: the amount of peroxide of iron in sev- Oxide of iron. . , . t -.. eral hydraulic limes, cements, &c., possessing in different degrees the power of withstanding these destruc- tive influences. He also in effect reaffirms the opinion ex- pressed by him as early as 1846, and subsequently in 1860, that peroxide of iron exerts an injurious influence upon hy- draulic materials. He shows that of two cements, both i7ide- st/rucUhle by sea- water, one (Medina) contains .12, and the other HYDEAULIC CEMENTS, AND MORTARS. 165 (Cahors) .055 of the peroxide of iron. Of cements slightly de- structible, the Pouilly contains .051 ; the Yassy, .0735 ; and the Portland, .053. Of cements entirely destructible in a few days' immersion, that from Gutaery (Lower Pyrenees) contains .059. Among the natural pozzuolanas, some from Pome, that stand the action of sea-water well, contain .12 of this peroxide ; others from JN'aples, that are unsatisfactory under similar cir- cumstances, contain .163 ; those from the Isle of Bourbon, still worse, contain .35 ; while all the pozzuolanas from the volca- noes of the Yivarais, which are worthless, contain, on an aver- age, .20. 296. M. Yicat further states that all artificial pozzuolanas prepared with white clay, and carefully applied, resist the action of sea- water. ^ Some of them do not contain any iron at all, and most of them not more than .012 to .02, while the celebrated lime of Theil, hitherto regarded as the only one known that could, with sand alone, furnish a mortar indestruc- tible by sea-water, contains but a trifling quantity of peroxide of iron, and sometimes none at all, while some other limes, most successful in fresh water, and containing as much as .9 or .10 of peroxide of iron, are destroyed in salt water after a few days. Tlie conclusion drawn by M. Yicat is that " it is difiicult to attribute a useful influence to the peroxide of iron," in virtue of the trials made by MM. Malaguti & Durocher. It is submitted that some doubts may, with reason, be enter- tained with regard to the correctness of the premises assumed by M. Yicat, viz., that if ^^^^ vSit'sTTn this oxide exercises the influence suggested by ion the subject of those gentlemen, in augmenting the power of hydraulic mortars to withstand the dissolving action of sea- water, the extent of this influence should be invariably in pro- * In view of the suspicions that have recently arisen in reference to the stability of maritime structures laid up in artificial hydraulic mortars, entertained by some of the ablest European engineers, and men of high attainments in practical science, we must be allowed to express some doubts as to the correctness of this premisa. 166 PEACTICAL TREATISE ON LIMES, portion to the quantity of the oxide present. May not the molecular state of the oxide, and the obscure kcu'iarcondftiST' variable modifications and reactions and heat on the which it, like some of the other constituent ele- oxide. ments of hydraulic mortars, may undergo during the calcination, — conditions which are known to vary materially with the duration of the calcination, and the degree of heat under which it is effected, — have an important bearing upon this question ? May not a portion of this oxide exist in a condition favorable to its entering into stable ^tiir and indestructible combinations, while another portion is practically inert or even injurious in its tendency, as is not unfrequently, and perhaps generally the case, with the silica and the lime ? Finally, may not the iron be present in several forms, such as the protoxide FeO, the per- oxide FcsOs, the magnetic oxide Fe304 or perhaps (FeO + FesOs) ? This last compound, in the form of cinders or scales thrown off under the smith's hammer, has long Forge scales. been known to possess the property oi pozzuo- lana, of conferring moderate hydraulic energy upon common fat lime, and although the activity of cements cannot in any degree be ascribed to its presence since some of the most active contain, of all the compounds of iron together, only a minute proportion ; still it is not improbable that ferruginous combina- tions may be developed, which are well adapted to resist the dissolving power of sea-water. 297. The gradual and progressive effects of sea-water upon hydraulic mortars immersed in it, notwithstand- Effect of sea- . . , , ' water on mortars ing the attention which the subject has received not understood. /? -r^ • • . -n i i • irom iLuropean engmeers, is still enveloped m considerable doubt. It is an easy matter to ascertain that its retarding influence upon the initial hydraulic induration is not very great, if the cement be mixed up with fresh water ; and it does not become very marked when the cement is both mixed with, as well as immersed in sea-water. The strength of mor- HYDEAULIC CEMENTS, AJS^D MOKTAES. 167 tars, however, is considerably impaired by using sea- water for mixing them, as is shown bj the following table : Mixing mortars with sea-wafcer TABLE IX. Sliowing the ultimate strength of rectangular parallelopipeds of mortar 2"x2"x8" formed in vertical moulds, under a pres- sure of thirty-two pounds per square inch, applied at the upper end, until the mortar had " s&t^'' and broken on supports four inches apart by a pressure from above midway between the points of support. The mortars were kept in a damp place for twenty-four hours, and then immersed and kept in sea-water. Some of the mortars were mixed with fresh water and some with sea-water. The cement was calcined in the Flame Kiln, and the mortars were ninety-five days old. Composition of the mortar. AS, Pure cement mixed with fresh water to a stiff paste tl u u « " « n » II (I (I (( k( (I (( (( U U (( (( Pure cement mixed with sea-water to a stiff paste II (I (I v. V. (( (( » U II (I (I U (I II II II II Cement powder, vol. 1, sand, vol. 2, mixed with fresh water U It II II II II it II II It It (I II II It II II (I II II Cement powder, vol. 1, sand, vol. 2, mixed with sea-water It it II It It II it it II It Cement powder, vol. 1, sand, vol. 2, mixed with sea-water concentrated by heat 25 per cent 197. 165 165 goa >A 499^ lbs. 379i " 3132 195 165 298. Preservation of Cement. — Hydraulic cement exposed 168 PEACTICAL TKEATISE ON LIMES, to the air absorbs moisture and carbonic acid gas, and is rapidly deteriorated bj the progressive forma- ?!^!t ^i"*""''" tion of the carbonate and hydro-silicates and rates m air. «/ aluminates of lime, in the condition of pow- der. Even when put up in the usual way in the casks ordi- narily supplied for that purpose, which are quite as tight as flour barrels, and are always lined throughout with paper, it loses much of its energy in the course of six or eight months, and at the end of fourteen or sixteen months is unfit for use in important works, and is incapable of sustaining the full dose of sand. Cements thus deteriorated are scarcely d'eterioSJ!? equal, in hydraulic energy, and in the strength and hardness of the mortars made from them, to those that have been once mixed into mortar, and repulver- ized at the expiration of three or four days. 299. When liable to be kept on hand for several months cement should be stored in a tight building, Preservation of f^Q^ from any o:reat draught of air throu2:h it. cement. ^ o o o If the floor is of earth, or paved with stone, and consequently likely to condense moisture from the atmos- phere, the casks should be raised several inches Kps^'^*"^^^ above it. Unground cement in the state of lumps as it leaves the kiln, may be kept for two or three years without sensible deterioration. Circum- stances might arise when it would be expedient to pursue this course. In such a case a run of small millstones driven by horse-power, or some other suitable apparatus for pulverizing it as required for use, would have to be provided. 300. Cements that contain meagre lime in excess, and bor- der on the intermediate limes, are improved by Intermediate limes , ^ ... . improved by age age to within certain limits. After the lime to a certain time. r. ^ j . t i i n i has had time to slake, or has so far progressed in that operation that the process of mixing up with water will com23lete it, the deterioration commences and goes rapidly on. The slaking of the lime being due to absorption of mois- HYDRAULIC CEMENTS, AND MOETAESL 169 ture, the cement itself receives injury from the same cause, and is degraded in hydraulicity. Several of tlie layers of tlie deposit in Ulster Co., 'N. Y., furnish cements of this type. 301. Genuine cements that have been iniured _ Dotonorated by age or exposure, or have from any cause cements restored , , , i. J • • • 1 by recalcination. become wet, may be restored to their original energy by re-calcination. For this purpose it is convenient to mix the cement into paste, with about ten per cent, of clay, to secure cohesion, and then form it into balls or cakes of suitable size for burning. It is advantageous to mix the clay, with the water as the first step, as its thorough incorporation with the cement is more readily secured thereby. Cement that has become wet through in the barrels, and taken a " set," as might frequently occur on long sea voyages, may be broken into lumps, reburnt in that condition, and subsequently pulverized. A bright red heat of one and a half to two hours' duration is quite sufficient to restore the Jequked^ activity of injured cements. 302. Some mortars made from the " Hoffman" brand (para- graph 60), composed of two measures of ^ „ " ^' ^ Old mortar from cement paste and one measure of sand, taken Hoffman's Rosen- in the summer of 1859 from the Embrasure Target erected at West Point five years previously, was pul- verized in a mortar and heated in a crucible for one and a half hours at a bright red heat. It was then mixed into mortar and formed into two cakes. One of these, left in the air, bore the inch testing wire, loaded to i pound, in ten minutes, and being then immersed, bore the 2V inch wire and one pound weight in fifteen minutes more ; the other, immersed as soon as mixed, sustained the heavy wire in fifty-five minutes, though not very well. 303. Two varieties of cement, viz. : the " Hoffman" and the James River brands, were formed into a paste -r. , . ^ ' ^ Repulverized with fresh water without sand and allowed to cement after two harden for three days. They were then repul- setting. 170 PEACTICAL TEEATISE ON LIMES, veiized and sample-cakes of stiff paste formed. ISTeither of them would sustain immersion in water at all, but appeared entirely deprived of hydraulicity. The sample left in the air bore the light testing wire in about four hours, but they appeared to have hardened more from the effects of desiccation than hydraulic energy, and fell to pieces soon after immersion in water. Samples restored by a red heat of one hour's dura- tion, were in every respect as energetic as new cements. Numerous trials seemed to indicate that cements repulverized after but twenty-four hours' induration, are scarcely more ener- getic than those that remained set" three days. 304. The alkaline silicates were thoroughly tried, as a means of restoring the energy of damaged cements, but without suc- cess. The trials of strength were confined mostly to prisms left in the air to harden. The silicate seemed to operate inju- riously. 305. Some of this cement mortar, containing no sand, repul- verized after three days' " settins:," and without Its Btren^h. -, . -. i t i . . -. havmg been restored by burning, was mixed with an equal volume of sand, and formed into prisms. Other prisms of like composition were made of the same kinds of cement, fresh from the barrel. The breaking weights of both are given in the following table. Table X. shows the ultimate strength of rectangular prisms 2" X 2" X 8" of mortar formed in vertical moulds, under a pressure of thirty-two pounds per square inch, applied to the upper end, until the mortar had " set," and broken on supports four inches apart, by pressure midway between the supports. The prisms were kept in sea-water after the first twenty-four hours, and were 320 days old when broken. The cement was measured in powder. HYDRAULIC CEMENTS, AND MOKTAKS. 171 TABLE X. Kind of ce- ment. Hoffman. Cement repulverized after 3 days' set, vol. 1, sand vol. 1 . James River. Composition of the mortar. Cement fresh from barrel, vol. 1, sand vol. 1 . Cement fresh from barrel, vol. 1, sand vol. 1 Cement repulverized after 3 days' set, vol. 1, sand vol. 1 , Penetration of point by^ .065 .072 .075 .095 .075 .090 .077 .100 .050 .057 .045 .057 .097 .112 .102 .112 .080 .085 .097 .100 .077 .113 .117 .125 .112 .122 .127 .160 .137 .159 .132 .165 .077 .092 .085 .092 .165 .187 .177 .187 .130 .147 .145 .160 .135 St: 2 866 822 806 643 697 228 254 248 244 217 228 681 623 585 635 209 204 271 244 267 296 279 254 306. Some of the James River cement, manufactured at a different time, and apparently not as good as that referred to ill the foregoing table, was obtained. A few prisms were made of this cement without sand, and while quite fresh. The barrel was then reheaded, and kept for one year without be- ing disturbed, when other prisms were made, also without sand. Both sets of prisms were kept in water for , , , , n • Strength of dete- 320 days, and then broken on supports lour inches riorated James apart, as usual, with the following results : River cement. The prisms formed of the fresh cement, bore as an average of 6 trials, 402 lbs. " stale " " " 6 " 244 lbs. This cement being originally of inferior quality, in conse- quence probably of careless burning, as well as of a careless se- lection of stone, the ratio of deterioration is doubtless much less marked than would have been exhibited by a prime article. 307. Hydraulic lime also loses its energy by Hydraulic lime deteriorates by exposure, in the same way as cement. age. General Treussart tried some of the Obernai and Metz hydrau- 172 PRACTICAL TEEATLSE ON LIMES, lie limes. The composition of the raw Obernai Qbernai and Metz stone was lime, .422; magnesia and iron, .050; hydraulic lime, silex, .105 : alumina, .043; carbonic acid and water, .380. The Metz lime bm^nt contains .683 of lime, .090 of magnesia, .170 of clay, and .057 of oxide of iron. These limes were slaked by an infusion of about } of their volmne of water. Some of the lime was made into mortar, and formed into prisms, as soon as it was slaked, and while perfectly fresh. Other prisms were formed after the slaked lime had been kept for some time in an uncovered vessel. The ages selected for the lime powder were 15, 25, 30, 45, 60, 90, and 120 days, respectively, The prisms were retained 12 hours in the air, and were then immersed and kept in water. They were broken on supports 4 inches apart, when one year old. The results are given below : TABLE XI. SHOWING THE STRENGTH OF MORTARS 1 YEAR OLD, IN PRISMS 2" X 2" X 6", BROKEN ON SUPPORTS 4 IN. APART, BY A PRESSURE AT THE MIDDLE POINT. Composition of the mortar. j Obernai lime in powder vol. / Sand vol. Lime and sand same as above Lime as above vol. Sand vol. Trass vol. Liiiie, sand, and trass as above \ Metz lime in powder vol. I Sand vol. [ Lime as above vol. < Sand vol. I Trass vol. ii Bi-eaking weight of the mortars, in pounds. The ago of the slaked lime when made into mortar, is given at the heads of the column. 264 121 473 209 116 180* ! 121 132 7T 299 44 312 M o ^ a 77 304 a I 117 299 352 22 319 s a 70 317 66 495 22 385 Remarks on the above Table. — We judge from the results given in Table XI. that hydraulic limes deterio- draulic limes and rate by the absorption of moisture and carbonic acid gas, if left exposed to the air after slaking ; * This sample was found split longitudinally. The two halves were carefully put together, and the prism broken in that way. The strength must have been diminished by the sphtting. HYDRAULIC CEMENTS, AJ^D MORTAES. 173 but that the evils of such exposure may be counterbalanced by mixing the deteriorated limes with a suitable proportion of trass. This conclusion might have been arrived at from our knowledge that trass and common lime make a good mortar, and that the practical effect on hydraulic limes, of exposure to the air, is to reduce them to the condition of common lime. 308. General Treussart also found by experiment that the strenp^th of hydraulic limes is injured by air- ^ , ,. ° J ./ Hydraulic limes slaking, in a ratio varying directly with their injured by alr- hydraulicity, but that mortars composed of one ^^^^"^S- measure of powdered air-slaked lime, one measure of sand, and one of trass gave very good results. 174 PEACTICAL TREATISE ON LIMES, CHAPTEE YI. 309. Calcareous mortae, being composed of one or more of the varieties of lime or cement, natural or arti- Caloareous mor- ^(.lal, mixed with sand, will vary in its proper- ties with the quality of the lime or cement used, the nature and quantity of sand, and the method of manipulation. ISTo fixed rules for its preparation, that shall be equally well adapted to all the varying circumstances of locality, temperature, and the seasons, can be prescribed. 310. The objects to be attained by the use of mortar are chiefly of two kinds, as follows : First, to bind together the solid materials Their uses. -Qged in masonry constructions ; or, in other words, to produce in each particular case, arti- ficial monoliths, of the required form and dimensions. Second, to form coverings to the solid materials, under the general denomination of stucco work. Under this head may be included all exterior covering, and interior plaster work and ornamentation. 311. Sand exercises no sensible chemical action in the com- position and induration of mortars of hydraulic l^^t'''' li^e ; if the sand be silicious, there is believed to ensue a slow formation of silicate of lime, which considerably augments their power of resistance, and in positions excluded from contact with the air, such as the in- terior of thick walls, becomes an important auxiliary in the hardening process. HYDEAULIC CEMENTS, AND MORTARS. 175 In a general sense, therefore, an 3^ mixture of fragmentary substances, like sand, gravel, pebbles, or pieces of brick or stone, formed into a state of aggregation by a calcare- ous cementing matter or matrix, might be termed mortar; but as this definition would evidently include concrete or beton, which is made by incorporating into ^^^^^^.^^^ mortar, fragments of brick or of stone, shells cation of the term . , mortar, and pebbles, it is perhaps well to retain the technical signification of the term mortar, by limiting its appli- cation to mixtures of sand and a paste of the cementing sub* stances, reserving for a general classification of mortars and concrete under one head, the more Aggregates, comprehensive denomination of aggregates. 312. The practical strength of aggi-egates, considered with regard to their tenacity, hardness, and power of resisting com- pression, depends upon four essentially distinct conditions : 1st. The constant resistance of the parts enveloped by the matrix, whether composed of sand, gravel, peb- bles, fragments of brick or stone, or a mixture gregates. of them all. 2d. The resistance varying, and generally increasing with time, of the matrix or cementing matter. 3d. The force of adhesion between the matrix and the other parts, resulting in part, from the former penetrating the in- terstices of the latter, and in part from the chemical afiinities existing between them. 4th. The strength due to the interlacement of the enveloped parts with each other, which produces leverage and friction among them, and enlarges the surface of least resistance. 313. It might be inferred theoretically, that the capacity of an aggregate possessing no voids, to resist any particular kind of strain, cannot surpass that of its matrix or gang ; or rather cannot be equal to it, except when the inherent strength of the enveloped parts, as well as the adhesion between them and the matrix, equals or exceeds the resisting power of the latter. 176 PRACTICAL TREATISE ON LIMES, In practice, when these conditions do approximately obtain in exceptional cases, mortars are weakened by we^ened^ by the ^^^^ addition of sand or any of the substances sand used. above mentioned. These latter have the im- portant effect, however, of preventing or dim in- cises of the sand, jgj^j^g shrinkage, of hastening the induration of rich limes, and of rendering all kinds of mortars less liable to crack in drying, which is often of very great advantage. They are, moreover, by far the least costly ingredient of mor- tars, and a due regard to economy compels their use in the largest possible proportions. 314. It might also be inferred that the minimum amount of . , . . the cementinoi: material that can be used in any Theoretical mmi- ^ ° ^ mum of cement- case, is exactly equal to the volume of the voids mg su s anoes. ^j^^ sand, w^hen the latter is well compacted. This theory supposes that there is no shrinkage in the matrix w^hile hardening, and that the manipulation is complete. But as these conditions can never be fully attained in practice, it is unsafe to descend to this inferior limit. Moreover, mortars com- Not safely appli- P^^^^ ^^^^^ principle would be deficient in cable in practice, both adhesive and cohesive power, from the fact that the particles of sand would present a large area, practically void of matrix, to the surfaces of the solid ma- terials that are to be bound together, and would, for the same reason, be in more or less intimate contact with each other throughout the mass. In order to avoid these defects, it is customary to determine the amount of cementing matter to be used in any particular case, by adding 45 to 50 Proportion of , , * • i • i sand to the gang per cent, to the volume 01 void space m tlie of mortars. sand. One method of ascertaining these voids is, to determine the volume of water which a known volume To determine the of the sand (damp and well compacted in a ves- voids in the sand, suitable form) will receive ; another, ap- plicable only when all the particles of sand are derived from the same kind of rock, is to ascertain the weight of a known HTDEAULIC CEMENTS, AND MOETAES. volume of the sand and compare it with the weight of an equal volume of the solid rock, as calculated from its known specific gravity. 315. "When sands of various sizes are at hand, a considerable saving of the cementing material may be g^nds of different secured by mixing them together in suitable sizes can be mixed rn 1 • 1 . • advantageously, proportions. To determme this point, take a measure of convenient capacity, say a little more than one cubic foot, and put in it a known volume, say one cubic foot, of the coarsest variety of sand. Then add to it, little by little, so long as there is no augmentation of volume, the sand which stands next in order of size, shaking the vessel well during the operation. Add to this mixture in the same way the other sands in regular order, so long as there is no increase of bulk. The original volume of the coarsest sand, and the several v^olumes of the other varieties successively added to it, will indicate the proportion in which they should be combined, in order to produce a mixture possessing the smallest measure of void space which they are capable of yielding. Having made the mixture, its voids may be measured by either of the methods given above, or by subtracting from the known voids of the coarsest variety, the difference between the aggre- computation of gate volume of added sands, and their aggre- tlie voids of mixed sand. gate voids. 316. The density of sand depends somewhat on its state of humidity and the manner of measuring it. In determining the properties of the constituent parts of mortars, due allowance should always be made, as ascertained by trial, for these causes of variation. A convenient method of ascertaining the pro- portion of grains of different sizes in any given kind of sand, with a view to institute a comparison between different varie ties, is by usina; sieves of various decrees of fine- ' \ , . , ^ , Sifting tbe sand, ness, noting the amount by weight or volume retained by each sieve in succession, commencing with thr coarsest. These several amounts, added to that which passea 12 178 PKACTICAL TREATISE ON LIMES, through the last or finest sieve, should be equal to the known amount taken for trial. Sieves are classified into numbers, which correspond with the number of openings Classification of i i • t i • i i? ^.i • r ggj.jgg embraced in a lineal inch oi the wire gauze of which thej are made. Those used in the experi- ments reported in this work were Nos. 12, 18, 24, 30, 40, 50, and 60. A few of the many sands that have been examined are introduced into the following table, which contains an equal quantity of each kind represented by 1.000. TABLE XIL No. 1. Calcareous sand, from Key West, Fla. No. 2. Sand, from Governor's Island,NY. Harbor.* No. 3. Mixed sili- cious sand. No. 4. Mortar sand, Fort Kichmond. No. 5. Sand, from Brooklyn, N. Y. Weight of grains between ^^2" in. and -i-g- in. diameter, Weight of grains between -^^ in. and ^4- in. diameter, Weight of grains between 2-4 in. and in. diameter. Weight of grains between -3-0 in. and -^^ in. diameter. Weight of grains between -^q in. and g-o in. diameter, Weight of grains between 5^0- in. and -^q in. diameter, Weight of grains less than -gV in. diameter. Total .080 .138 .243 .222 .138 .103 .076 .163 .302 ,352 .183 .140 .175 .584 .043 .019 .008 .031 .038 .092 .179 .183 .224 .284 .341 .302 .163 .119 .060 .015 1.000 1.000 1.000 1.000 1.000 Percentage of void space by ) volume. ) .347 .363 .339 1064 lbs. 103| lbs. 107i lbs. * This sand is fine grained, containing a very snaall proportion of particles exceeding ono thirtieth of an inch in diameter, which is in the condition of rather smooth gravel, heterogena ously distributed throughout the mass. 1 cubic fDot of sand, No. 3, damp and not compacted, weighed 87 pounds. 1 " " " " damp and compacted, " 97 " 1 " " " " dried in an oven and not comp.," 97^ " HYDRAULIC CEMENTS, AND MOETAES. 179 1 ctibic foot of sand, No. 3, dried and compacted, weighed 106^ pounds. 1 " *' " comp. and afterwards dampened *' 112^ " 1.11^ cubic feet of loose, damp sand has its volume diminished, by shaking, to 1 cubic foot. 1.09 cubic feet of loose, oven-dried sand has its volume diminished, by shaking, to 1 cubic foot. METHODS OF SLAKING LIME. 317. Lime is usually sent to market in barrels, either in lumps, as it leaves the kiln, or, in the case of those varieties that are more or less meagre, and S^the^market^^ consequently difficult to reduce to fine pulp by any of the known methods of slaking, in the condition of coarse powder to which it has been brought by grinding. In either case, it must be slaked before it can be employed as a matrix for mortar. 318. Three methods of slaking lime are usually described in works on mortars ; on the continent of Eu- rope, the third method, and in the United States, Three methods of the second and third are seldom resorted to in ^^^^^^ practice. 319. The first or ordinary method termed drowning, from the excessive quantity of water sometimes injudiciously em- ployed, consists in pouring upon the lumps of lime, collected together in a layer of uniform depth not exceed- ing six to eight inches, either in a water-tight drownkTg.^^^' wooden box or a basin formed of the sand to be subsequently added in making mortar, and coated over on the inside with lime-paste, to render it impervious to water, a suf- ficient measure of fresh water, — previously ascer- tained approximately by trial, — to reduce the ^^once.*^^ whole to the consistency of thick pulp. It is important that all the water required for this purpose, which, with the different limes, will vary from two and a half to three times the volume of the quicklime, should be added at the out- set, or, at least, before the temperature becomes sensibly ele- 180 PRACTICAL TREATISE ON LIMES, vated. In this condition the lime will remain entirely sib- merged, and comparatively quiescent, until after an interval of five to ten minutes, the water becomes grad- The slaking. usiWj heated to the boiling point, when a sud- den evolution of vapor, a rapid increase in volume, and a reduc- tion of the lime to pulp, ensues. The increase of volume is sometimes denominated the " growth." 320. This process is liable to great abuse at the hands of workmen, who are apt to use either too much process^^*^'^ water, thus conferring upon the slaked lime a condition of semi-fluidity, and thereby injuring its binding qualities ; or, not having used enough in the first instance, they seek to remedy the error by adding more after the extinction has well progressed, and a portion of the lime is already reduced to powder, thus suddenly depressing the tem- perature, and chilling the lime, which renders it granular and lumpy. 321. As soon' as all the water required has been poured upon the lime, it is recommended to cover up the vessel con- taining it with canvas or boards, in order to concentrate the heat and the escaping vapor, and direct their action upon the uppermost portions deprived of immediate to L^covered up. contact with the water, by the swelling of the portions at the bottom. When it is not practi- cable to apply this covering, a tolerable substitute is found in Sand may be sand to be subsequently added to the used for this mortar. This can be spread over the lime in a layer of uniform thickness, after the slaking has well progressed. Another precaution of equal and perhaps greater importance is, not to stir the lime S'^eS^ft^rt. whilst slaking; but to allow it gradually to absorb the water by capillary attraction and its natural avidity for it, taking care that all portions are supplied with it to that degree requisite to produce a paste of the slaked lime, and not a powder. When the lime is to be used HYDEAULIO CEMENTS, AND MOETARS. 181 for whitewashing or grouting, the water should be added at the outset in larger quantities than specified above, and the whole mass should be run off wMtewashing. while hot into tight casks, and covered up to prevent the escape of water. 322. In slaking, the essential point is to secure, if possible, the reduction of all the lumps. It will be found difiicult to obtain this result with the hydraulic varieties, Hydraulic limes and the difficulty increases in a direct ratio with slake with diffi- . culty. the hydraulic energy, until we reach the inter- mediate limes, or the inferior limit of cement, when the reduc- tion must be effected by mechanical means. Even with those hydraulic limes that do slake, it is often necessary to employ a mortar mill to reduce the lumps, — a condition Mechanical means which should always be secured, as these lumps pi^e*^°^for rT' constitute not only a dangerous substitute for ducing them, sand, if left intact, but furnish when pulverized, the most ener- getic portion of the gang. 323. Slaking hy Immersion. — The second second process method of slaking i^y immersion).^ consists in of slakmg. suspending the quicklime, previously broken into pieces of about the size of a walnut, and placed in a basket or other suitable contrivance, in water, for one or two minutes, taking care to withdraw it before the reduction commences. The lime should then be quickly heaped together, or emptied , , ; , - . , Precautions, into casks or bins, and covered up, m order to concentrate the heat and prevent the escape of vapor. In this condition it soon begins to swell and crack, and finally becomes reduced to a fine powder, which may be preserved several months without serious deterioration, if packed in casks, and kept from direct contact with the atmosphere. The expense which would ordinarily attend the practical application of thia process, and the difiiculty, and even impossi- . . \ . . . This process ei- bility of securing with certainty, at the hands of pensive and di£S- v\x)rkmen, the period of immersion, have led to ^^^* 182 PEACnOAL TREATISE ON LIMES, a modification of it, which consists in sprinkling the broken A modification fragments formed into heaps of suitable size, of it- with one-fourth to one-third of their volume ol water. This should be applied from the rose of a finely gauged watering-pot, after which the lime should be immediately cov- ered with the sand to be used in the mortar. In this condition it should not be disturbed for at least a day or two, and the Practice in Eu- Opinion prevails in the southern portions of the ^<^P®- continent of Europe that the quality of the lime is improved by allowing the heaps to remain several months, without any other protection from the inclemency of the weather than an ordinary shed, open on the sides. In the vicinity of Lyons this custom very generally obtains, the au- tumn being usually selected for slaking all the lime required for the following season's operation. In Europe, this method of slaking is applied to the fat and slightly hydraulic limes only, and not to those that are eminently hydraulic, upon which it seems to act disadvantageously, by depriving them, in a measure, of their hydraulic energy. 324. Spontaneous slaking. — Quicklime has a great avidity for water, and when not secured from direct Third process — ' Spontaneous or contact with the atmosphere, gradually absorbs air slaking. moisture from it and falls into powder, exhibit- ing but very slightly, and sometimes not at all, the other phe- nomena usually developed in slaking. The lime is then said to be slaked sjpontaneously ^ or air slahed. 325. It has been claimed by some engineers that this method, if the precaution be taken to stir the Thought to con- , , , fer hydrauiicity lime Irequently, so as to expose every portion in ashght degree. ^.^^^'^ ^^^^^^^^ ^.^j^ ^^^^ ^^^^^^^ a slight degree of hydrauiicity upon fat lime ; and Culmann, _ . . . ^ , in his " Cours sur les Chaux, Mortiers, et Mas- Opinion of Cul- ' mann needs tics" says, " it produces very advantageous re- sults upon fat or feebly hydraulic limes that are to be mixed with pozzuolana and used under water." It HYDRAULIC CEMENTS, AND MOETAES. 183 is believed that both of these statements need confirmation. A great and insurmountable objection to the process, however- is the expense of storage room or sheds which it necessarily . volves, to say nothing of the time required for its completion. Spread out in layers of from ten ortSFocSs. to twelve inches in depth, some varieties of fat lime might become thoroughly reduced in twenty or twenty- five days; others would require as many weeks; while with a few, the process would continue for a whole Hydraulic limes year. Hydraulic limes are greatly injured by ^J"^^^^ spontaneous slaking. Fat limes slaked to powder by the second or third process, are converted into paste with less water, and undergo a less aup-mentation of their orisrinal ^ ^ ^ Remarks, volume, than w^hen slaked by the first process. 326. By neither of the three processes of slaking, nor any modification of them, have I succeeded in obtaining as great an augmentation of the volume of fat lime measured in the state of paste, as is stated by M. Yicat to belong to the fat limes of France, viz. : that one volume of the quicklime in lumps, by the absorption of 2.91 volumes of water, will give 3.5 volumes of paste. According to the same authority, these limes slaked by im. raersion to powder, and afterwards reduced to ^ Yicat's de- paste, absorb 1.72 of water, giving 2.34 of paste ; Auctions, while, by spontaneous slaking they required 1.88 of water, and gave 2.58 of paste. It is also stated that the hydraulic limes in slaking absorb 1.05 volumes of water increase of by the first process, .71 by the second, and .68 vo^^^^- by the third, producing respectively 1.37, 1.27, and 1.00 vol- umes of paste. 327. I have repeatedly tried all the limes ofiered to any extent, in the New York market. In slaking them, quantities of five to ten pounds were s^enerally employed ; ^ ^ ^ jr./? Expermients m and the utmost care was taken, in all cases, to slaking American obtain perfect accuracy in the weights and meas- 184 PRACTICAL TREATISE ON LIMES, urements, and bj the use of glass and tin vessels to prevent the waste or absorption of water. The glass vessels found most Vessels used convenient were two cyhndrical jars, one eight inches in diameter and eighteen inches deep, and the other three inches in diameter and ten inches deep. They were accurately ground off at the bottom to a plane sur- face at right angles to the axis, so as to stand in a vertical position on a horizontal surface, and were graduated to cubic inches, and the small one to fractions of an inch throughout their entire length. The large jar was used for determining the vol- ume of the quicklime and of the resulting powder or paste ; the small one, for measuring the water absorbed in slaking. When the quicklime to be tried was in the condition of lumps, the usual process of ascertaining its volume by the displacement of sand was employed. 328. To hold the lime while slaking, tin cans about one foot square and one foot deep, were found to answer a good purpose. 329. General Totten, from an average of many Results of Gen. . -, -r^ a -. i i c Totteu's experi- trials at l* ort Adams, states that one volume of quicklime slaked with \ its volume of water gave an average of 2.27 of powder ; f of water gave 1.74 ; f gave 1.81, while equal volumes gave 2.06. Slaked by drown- Increaseofvol- i^g^ ^.54 volumes of water gave 2.68 of thin paste ; and by sprinkling, 1.70 of water gave 1.98 of thin paste. Mixing the powder with .40 of water gave .66 of thick paste, while .50 gave .76 of thinner paste. One volume of lime slaked spontaneously produced 1.84 of powder, and one volume of this powder and .50 of water gave .75 of thin paste. One volume of quicklime when pulverized, gave ,90 of powdered quicklime. 330. TABLE XIII. Shows the results obtained by many trials of slaking applied to the limes in common use in the United States : HYDRAULIC CEMENTS, AND MORTAES. 185 18 Kind of lime used. Kocklaud lump lime J Sing Sing lump lime from I Sing Sing marble Rondout ground lime U (I u tl « » (I it K Glen's Falls lime in lumps by immersion. " slaked Before slaking. 11 91.2 86.5 91.2 95.0 87.4 89.3 88.4 110.2 well shaken. 110.2 well shaken. 115.9 well shaken. 124.5 well shaken. 1^.5 well shaken. 128.3 well shaken. 93.1 93.1 93.1 91.2 87.4 After slaking. Eatio of increase to Volume of watei soi-bed, in cubi inches. o a, xi S c3 " A II bf) '3 0 a 235.6 269.8 182.4 11.19 11.78 13.25 11.06 + 224.2 245.1 292.6 227.0 2.24 2.36 2.65 2.21 + 2.46 + 2.83 + 3.21- 2.40 210.0 11.12 227.0 2.22 + 2.61- 197.6 195.7 11.78 10.67 10.62 248.9 225.1 222.3 2.86— 2.13 + 2.12 + 2.79— 2.56- 2.00 + 201.4 11.37 239.6 2.27 + 2.14 247.0 281.2 2.42 + 209.0 11.37 + 248.9 2.27 + 2.00 209.0 11.44- 249.9 2.29- 2.00 + 197.6 11.25 247.0 2.25 1.93- 269.8 267.9 279.3 51.2 to produce a powder. 181.5 to produce a paste. 68.4 to produce a powder. 201.4 to produce a paste. 13.33 12.44 13.50 6.19 of powdei. 10.50 of paste. 6.62 + of powder. 10.87 + (.f paste. 285.0 271.7 304.0 260.3 of powder. 202.8 of paste. 285.0 of powder. 224.2 of paste. 2.66-- 2.49- 2.70 1.24 for powder 2.10 for paste. 3.06 + 2.92- 3.26 + 2.86 for powder 2.54 for pa«te. EXPLANATION OF THE ABOVE TABLE. No. 1. About one-half the quantity of water mentioned was poured on at once, and the balance gradually, with occasional stirring. No. 2. Most of the water was poured on at the outset, and the lime was stirred occasionally. No. 3. All the water (269.8 cubic inches) was poured on at once, submerging the lime completely, in which condition it was left covered up for several hours without being agitated at all. No. 4. 83-1 cubic inches were first added, and the balance of the 182.4 inches grad- ually, with occasional stirring. No. 5. The water was poured on gradually, with occasional stirring. No. 6. The Hme was nearly covered up with the water at the outset. "When the slaking had well progressed, more was added, with occasional stirring. No. 7, Water poured on gradually, with occasional stirring. No. 8. do. do do. do. ISG PEAC'TICAL TREATISE ON LIMES, No. 9. All the water was poured on at the outset, and after the expiration of one hour, the Urae was stirred. No. 10. All the water was poured on at once, and the canvas was covered up, and not disturbed until the next day. The paste was very thin and of the con- sistency of cream. No. 11. Water all poured on, and the can covered as before. The paste was much stiflfer than No. 10, but rather lesg so than most of the foregoing. No. 12. Water poured on as above, and not disturbed until the following day. Tho paste was not quite so thin as No. 10, but much more so than No. 11. No. 13. Water all poured on, and the can covered as above. The paste was a trifle less stiff than that adopted as the standard in these compari- sons. No, 14. The lime was broken into pieces of 1 to 1| inch cube, and 209 cubic inches of water poured on at once. The can was then covered up with canvas and left for several hours, until it had become cool. The lime was then in the condition of a powder, requiring QO-^ cubic inches of water to reduce it to a paste of the requisite consistency. No. 15. The lime was broken up as above, and 83^ cubic inches poured over it at the outset. The can was left open, and the balance of the water added in quantities of 20 to 24 cubic inches at a time, until 211 cubic inches had been used. This was just enough to produce a damp powder which re- quired 56-^) cubic inches more to bring it to a paste. No. 16. The lime was broken up as in No. 14, and submerged in 270 cubic inches of water. The can was then covered, and not disturbed until after the ex- piration of four hours. 9-i% inches of water were added to produce the re- quisite degree of consistency. No. 17. The hme, broken as in No. 14, was placed in a basket and suspended one minute in water, of which it absorbed 51-^ cubic inches. It was then poured into a can, covered up, and not disturbed until the next day, when it was found to be reduced to a powder containing about ten per cent, of smail lumps. After these were pulverized, 130 cubic inches of water brought the whole to a stiff paste. No. 18. The lime, broken as above, was suspended in water If minutes, and was then poured quickly into a can, and kept covered up until next day, when it was found very well slaked, with very few lumps, and none but what could easily be rubbed fine under a spatula. 331. Action of the hydrates in the air. — A paste of the hy- drate of fat lime in free contact with the atmosphere, absorbs carbonic acid gas upon the surface, although Sneln^the^ah-^ point of complete saturation, and becomes coated with a mixture of hydrate and carbonate of lime, (CaO.COg+CaO.HO). The gas gradu- ally penetrates the substance, at a rate of progress con- stantly on the decrease, and at the end of one year, according HYDRAULIC CEMENTS, AND MORTARS. 18? to M. Yicat, the layer of impure carbonate is from .10 to .12 of an inch in depth. The same f^l'^'^^l authority says, that the absorption and penetra- tion of this gas proceeds more rapidly in the hydraulic limes than in the fat limes — a statement which not only needs confir- mation, but is believed to be the converse of what is true. My researches lead me to the same results as those enunciated by Geo. Eobertson, Esq., in a paper recently ^^^^^ absorp- read before the " Koyal Society of Edinburgh," ^}^^ ^^^^^s ^h® ^ ^ ' different limes in- viz. : " The depth to which carhonic acid is ah- verseiy as their sorhed into mortar in a given time^ and^ to ^y^^^^^^*)^- a certain extent^ the induration from that cause varies in- versely with the hydraulic properties of the lime, which depend upon the silica contained in itP 332. The incrustation is due in the case of hydraulic limes to the combined influence of reactions, con- . „ ' The covering of siderably more complicated and obscure than subcarbonate those which obtain with the hydrate of fat lime. The hydrosilicate and aluminate of lime (Si03 4 CaO + 6 HO) and (AlA + 3 CaO + 6HO) are formed in addition to the hydrocarbon ate. Other compounds lormea. The formation of these compounds of silica and alumina is not confined to the crust on the surface, but takes place throughout the mass, and is really the principal eflicient cause of the induration of this class of limes, when placed under water, or in humid localities excluded from atmospheric influ- ences. It appears not improbable that these circumstances attending the superficial induration of hydraulic ^.^^ ^ o Difficult to meas- limes in the atmosphere, have led to errors in ure the subcar- 1 T 1 1 . p ^ bonate covering. measuring the depth oi the covering oi subcar- bonate, owing to the difiiculty in determining with precision the exact position of the surface which separates the crust formed by the combined influence of exterior and interior causes, from those portions in which the induration is entirely independent of atmospheric influences. 188 PRACTICAL TREATISE ON LIMES, 333. The Lardness assumed by the hydrate in the air is in- timately connected with the process of slaking, S^eenTardness appears to sustain a direct ratio with the of hydrate and increase in volume. The three modes of slaking mode of slaking. ^ " arranged in order of their superiority in this respect stand as follows : 1st. For fat limes : ordinary slaking, spontaneous slaking, slaking by immersion. 2d. For hydraulic limes : ordinary slaking, slaking by immer. sion, spontaneous slaking. 334. The hydrates of fat lime, drying in the air, shrink and crack to such an extent, that they cannot be employed in mor- tar for masonrv without a laro^e dose of sand. Hydrate of lime -^^^^'^^ hydrate under wotev. — soluble in water The hydrate of fat lime is soluble to the last de- changed. It ab- gree in water frequently renewed. Immersed sorbs water. -^^ condition of stiff paste in still water, it absorbs a certain quantity of the fluid, without any augmenta- tion of volume, or sensible change of consistency. The amount thus absorbed depends upon the mode of slaking. A paste formed by the ordinary oy fii^st process takes up .04 of water; if slaked by immersion^ nearly .11 ; and if ^3^^>-slaked, .245. An increase in density ensues, varying with the amount of water absorbed, and we might therefore be justified in assum- ing that fat limes slaked by the second or third process, which are to be rendered hydraulic by the addition of natural or arti- Mixed with poz ^cial pozzuolana, or cement, would be superior zuoiana, or ce- to tliose slaked by the first process, on account 01 the more intimate contact between the ingre- dients, and consequently, the more favorable condition for combination developed by the interior compression due to this increase of density. We would also suppose that the same assumption would be T, , VI- iustified, in the case of hydraulic limes which Hydraulic limes ' and pozzuolana. are to receive additions of pozzuolana. This HYDRAULIC CEMENTS, AND MOETARS. 189 theory is not fully confirmed by experience, winch shows that the latter class, when they are to be mixed with pozzu- olana, may be slaked by either the first or second process, with similar results, and that the third process should invariably be proscribed. When they are to be combined with inert sand only, they should be slaked by the first process. 336. For fat limes, the second and third methods have been supposed by many engineers to possess some , 1 /. ..... , Supposed advan- ad vantage; the former, in conierrmg increased tage of the second hardness and tenacity upon the mortar; the for'^faSe^g'''^^^^^ latter as a means of securing hydraulic proper- ties in a moderate degree ; but as there are some doubts upon these points, particularly as to the alleged superiority of air- slaking, and as any requisite degree of strength, hydraulic energy and quickness may be conferred upon lime mortars with more certainty and with equal economy, by the judicious use of hydraulic agents, either natural or artificial hydraulic lime, pozzuolana, or cement, (particu- ^^^^f^ tmtmpor^ larly the latter in the United States,) the first i^nt in the United States. mode of slaking, inasmuch as it s& attended with less original outlay, gives more certain results, and requires fewer precautions at the hands of the workman, - . The first process may be regarded as the most advantageous m the most advan- nearly every case, provided the precaution is *^seous. taJce7i to pour on at the outset all the water required to pro- duce a stiff paste ^ but no more. 337. For slaking lime, fresh water should be ^^^^^^ ^^^^ used, sea-water giving in all cases greatly dimin- for slaking, ished volumes. 338. General Totten announced the following as the results of experiments made at Fort Adams, upon the different modes of extinction : 1st. Slakinff by drowning, or using: a lars^e The " drowning" r. . , PIT. process weakens quantity oi water m the process of slaking, the lime. affords weaker mortars than slaking by sprinkling. 190 PRACTICAL TREATISE ON LIMES, 2d. Experiments with air-slaked lime were imratrsfactory^ too few to be decisive, but the results were unfavorable to that mode of slaking. 339. Preservation of Lime. — The paste of fat lime, whatever may have been the mode of extinction, may be preserved intact for an indefinite length of time, if kept from Ume paTteJ''' contact with the air. It is usual to put it in tight casks, or in reservoirs or trenches covered up with sand ; or, when shed-room is available, to form it into rounded heaps similarly protected and under cover. 340. The powder derived from the second and third modes Preservation of extinction may be preserved for several lime powder. months, without sensible deterioration, in cov- ered casks or bins, or if heaped up in dry sheds, and covered over with straw, cloth, or dry sand. 341. Until quite recently, opinions among engineers were divided as to the effect of time upon the quality Gen. Treussart. . p n t -, . i . i -, 01 paste 01 lat lime, preserved with suitable precautions for future consumption. General Treussart en- tertained the opinion that they should be made into mortar and used soon after their extinction. This idea finds few ad- Practice at the vocates at the present day, although the practice present day. in this country conforms to it with singular una- nimity. As before observed, it is customary in some parts of the continent of Europe to slake the lime the season before it is to be used. 342. Fabrication of Mortars. — ^The relative quantities in Fabrieation of which sand and the cementing substance, wheth- mortars. the latter be derived from common or hydrau- lic lime, or cement, should exist in mortar, depend in a great .measure on the character of the work in which it is to be used ; its locality and position with regard to a state of moisture The proportion of or dryness; and, if subjected to alternations in tary'^wTth dr' ^^^^ respect, the character of the moisture, de- cumstances. pending on its proximity to or remoteness from HYDRAULIC CEMENTS, AND MORTARS. 191 the sea, the nature and magnitude of the forces which it will be required to resist, the peculiarities of the climate, and the season of the year in which the work is to be performed. 343. In practice, the actual quantities of the different in- gredients to be portioned out ''depend on the varying con- ditions of dampness and dryness, looseness and compactness, powder and paste, in which they may be measured." 344. The following data, derived from the work of General Totten and from direct trials, will be found useful in estimat- ing the amounts of the different ingredients necessary to pro- duce any required quantity of mortar. One cask = 240 lbs. of lime, will make from . K 1 • n ^ 'm One cask of lime. 7.80 to 8.15 cubic feet of stiff paste. One cask *= 308 lbs. of finely ground cement, will make from 3.70 to 3.75 cubic feet of stiff ment. paste ; 79 to 83 lbs. of cement powder will make about one cubic foot of stiff paste. One cubic foot of dry cement, shaken down, but not com- pressed, mixed with .33 cubic feet of water (about ^^^j^ ^^^^ 2i gallons), will give .63 to .63^ cubic feet of stiff cement powder, paste (about 4yV gallons). One cubic foot of dry cement powder, measured loosely and without any compression, will measure only .78 to .80 cubic feet, if packed (as at the manufactorjes) with a wedge-shaped stick or paddle. The data given in the following table (XIY.) are compiled from General Totten's work. The quantities are represented by volume. ♦ 300 lbs. net is the standard barrel, but it usually orerruns about eight lbs. 192 PEACTICAL TREATISE ON LUVIES, TABLE XIY. Cement paste. Sand well compacted. .UU .yju 1 Art .00 .50 .45 1.82 .69 1.39 .25 1.00 .68 .91 .18 .71 .78 •78 .00 2.00 .25 2.00 .75 2.00 1.00 2.00 Mortar produced. 2.02 of mortar with 2.13 (( 4.30 (1 (( 4.67 4.30 <( 4.95 (( (( 5.53 (1 (( 2.25 1.71 1.07 , 2.49 2.22 , 1.85 1.95 1.57 1.84 .64 water made 2.54 grout. .92 " " 3.10 " 1.04 " " 3.56 » 1.22 " " 3.76 " .87 " " 2.90 " .87 " " 3.05 " 1.80 " 6.04 " 2.01 " " 6.60 " 1.80 " " 6.20 " 1.76 " " 6.64 " 1.80 " " 7.11 " 345. When mortar is to be made in quantities sufficiently- large to warrant the expense, a mortar mill of some approved pattern should be provided, for incorporating the ingredients, as the mortar thus obtained is invariably superior to that pro- duced by the use of the hoe and shovel only. 346. The mill used at Fort Warren^ Boston harbor, during the construction of that work by Col. Thayer, of which a ver- tical section through the centre of motion is given in Fig. 33, is thus described by Lieut. W. H. Wright, in his " Treatise on Mortars," page 98 : " It consists of a circular trench built of masonry, with slopins: sides. In the trench Description of ' i i /. • t mortar mill driven rests a heavy wheel, 8 feet m diameter, lur- by horse-power. njgj^ed with a tire \ inch thick and 12 inches broad, and loaded by having its interior space filled with sand. At the centre of motion is a drum, or circular mass of masonry, 4 ft. 8 in. in diameter, in which is firmly fixed a vertical axis about 8 inches square. With this axis is con- nected th'? horizontal shaft (also about 8 inches square), which HYDEAULIO CEMENTS, AND MORTAES. 193 passes through the centre of the wheel, and to which the horse is attached. Fig. 33. " The distance from the centre of motion to the centre of the wheel or trench is 7 ft. 6 in., and the radius of the horse- path is 20 ft. " The space comprised between the drum and trench is use^ as a reservoir for the slaked lime. It is sufficiently capa- cious to contain the paste which sixteen casks of lime will afford, and is conveniently divided, by means of movable radial partitions, into sixteen equal parts ; so that the laborer, who prepares the mortar, is J^^ued!'*'^''' relieved of the necessity of measuring the paste. The mill is protected from the weather by a cheap roof; it is placed in the vicinity of a pump, immediately under the spout of which stands a box, 7 ft. long, 5 ft. broad, 1 ft. 4J- inches deep, used for slaking the lime. This box is connected at one extremity with a small compartment, in the bottom of which is an iron grating, which allows the fluid paste to pass out into the reservoir, but retains the stones and imperfectly slaked lumps of lime. During the process of slaking, the compartment is separated from the rest of the box by a 13 194 PEACTICAL TEEATISE ON LIMES, movable board, which slides in grooves made water-tight with a little of the lime putty. " The board being in its place, water is pumped into the box in sufficient quantity to convert the lime, (three casks at once,) into a thin cream that will readily run off through the grating. The lime is then added and well stirred, in order to break up the lumps, a large hoe being usually employed for the purpose. When the slaking is completed, the sliding board is raised, and the cream conveyed by means of the trough, E, attached to the grating for the purpose, to the basin, F, w^here it is allowed to remain as long as possible before it is used." This mill is capable of making six hundred cubic feet of mortar per day of ten hours. By increasing Capacity of mill. the radius of the trench to 12^ ft., and the radius of the horse-path to 25 ft., the working capacity of the mill would be nearly, if not quite, doubled. 347. The other implements that will be found convenient in the preparation of mortar are a hoe and shovel, differing little, if at all, from the ordinary form ; a box for measuring lime and cement paste, which should be of conven- requL'r^'"'''''*' ient capacity, say 3 cubic feet, and should be arranged with handles projecting horizontally on two opposite sides, like those of a hand-barrow, and a sec- ond box of the same size as tlie foregoing, or rather a little larger (say 3|- cubic feet in capacity), so that it will contain, loosely thrown in and struck, a volume of sand corresponding to three cubic feet well compacted. This box may be provided with handles like the other, but had better be arranged on a wheel-barrow. 348. To make mortar with the mill above described, the lime paste is first put into the trench from one morta'r^"''^^ of the central compartments. To this is added by measurements from the wheel-barrow box, about one-half of the sand required for the batch, and the mil] HYDEAULIC CEMENTS, AND MORTAES. 195 i3 then set in motion, and the ingredients thoroughly incorpor ated. The remainder of the sand then follows, with such additions of water as may be necessary to bring the mass to the proper consistency. When lime mortar is to be rendered hydraulic by the use of cement or of an alkaline silicate, these had better be added — the cement in powder and the silicate in solution — to the lime paste just before the mill is set in motion, in order that the mixing may be thorough and complete ; ex- cept in the case of very quick-setting cement, when its incor- poration into the mortar should be deferred until the last por- tions of sand are added. 349. This process of slakinsj the lime with an ^ ^ ^ ^ ° Excess of water excess of water was never employed at Fort War- not used in ren, except when hydraulic cement was to be ^^^^^^s- added to the mortar. For mortars composed of lime and sand only, the lime was slaked in the ordinary way with a sufficiency of water, simply to produce a thick pulp. The result given in Table XIIL, page 185, which may be easily verified on a large scale, indicate, apparently beyond a doubt, that with the limes most extensively in use for public works on our Atlantic coast, the largest augmentation of volume in slaking is secured by adhering to the following directions, viz.: put the lime into a box, break up the larger lumps with a hammer ; pour in at once the quantity of water (ascertained previously by trial) necessary to reduce them to a stiff paste, and then cover up the box so as to prevent, as ^sedln Xking.^^ much as possible, the escape of heat and vapor, allowing it to remain in that condition, without stirring, until the reduction is complete. In order to connect this process with the operations of a mortar-mill, it might be necessary to provide several boxes, so that the lime might, in all cases, have at least forty-eight hours to digest before it is made into mortar. 350. Major E. B. Hunt, Corps of Engineers, formerly charged with the construction of Fort Taylor, Key West, 196 PEACTICAL TREATISE ON LIMES, Florida, has kindly furnished me the following description of the steam mortar-mill in use at that work. levation of Mortar-Mill. Fig. 34. 351. The steam mortar- / ill which was erected at Fort Tay- lor in 1857, Steam mortar mill. is of the kind devised by the late Brevet-Major J. Sanders, and was pur- chased and set up un- der his direction. The mill and engine were made by E. C. Stotsen- berg, Wilmington, Del- aware, and cost $3,466. The frame and house for the mill, and setting them up cost $237, to which Plan of bed-plate ; scale i in. to 1 foot. Ym. 35. Bhould be added the freight and cost of engine-house, making HYDRAULIC CEMENTS, AND MORTAES. 197 nearly $5,000 as the cost of the whole m work- Description of 1 rrn • • 1 • same. mg order. ine engine is about sixteen to twenty horse-power, and has a heavy fly-wheel. Two-thirda of this powxr would run the mill, though at greater cost foi fuel and at higher pressure. The engine is geared into a fixed connection with the mortar-mill, which is a fault, as the engine cannot be used for any other purpose, without driving the mill, The mill. Figs. 34 and 35, consists essentially of a pan geared into a cogged connection with the engine, and support- ed on large conical bed rollers ; and of a pair of hollow cast- iron wheels, so joined by an axle, that they revolve in the opposite sides of the pan with the same velocity as the pan itself. The grinding surfaces have thus a compound or double velocity. Two helical scrapers are fixed to the vertical driving shaft of the wheels, and are so shaped as to throw a sort of furrow in the mortar materials when mixing. A scraper is fixed to each end of the horizontal shaft, so as to scrape the faces of the large wheels as they roll around that shaft. Another scraper is also fixed to this axle, so as to scrape the inner face of the pan and to throw a furrow towards the centre. The lime paste is first put in the pan, and is ground while the sand and cement are measured out, on a fixed platform at the level of the bottom of the pan and bordered up close to its rim. The mixed cement and t^rS.""^ ''''''^ sand are shovelled in, and water added until the whole batch is introduced. The greatest resistance is encountered when the dry materials are thrown in, at which time the speed is very much slackened, and the engine requires nearly its full power at the working pressure, if the filling be done very rapidly. As the mixing proceeds, the speed of rev- olution quickens greatly, but is controlled by the engine- driver in proper limits. Wlien the batch is sufficiently ground and mixed, it is scooped out by the use of a scoop-shovel, the workman stand- ing on a lower portion of the platform, about a foot below the 198 PRACTICAL TREATISE ON LIMES, bottom of the pan, and throwing tlie mortar into a mortar-box wliich is backed in by a sling cart, so arranged as to carry the batch to the derrick or point of use, and then to rim the box down to the ground by two screws with arras and long links, one at the fore and one at the near end of the box. Each batch of mortar corresponds to one barrel of cement, and the mill has repeatedly made over fifty batches in a day, and can do this as a regular day's work. It requires worrtii^miif engine-driver, one fireman, and from two to five men at the mill, according to the amount of mortar to be made. It has also been used during the last and present season to make the mortar for concrete, which is transported by the sling cart, hoisted by the derrick on the con- crete platform, and then thrown over the broken stone spread out to receive it. Two turnings* mixed it very well. The broken s^one is hoisted by a light platform carrying five barrels, the usual amount for a batch. This using it for con- crete as well as for masonry mortar, will often make running the mill an economy, when it would not be so, were only the mortar for masons made there. It will hardly be found an economy, to run the mill for less than twenty to twenty-five batches a day. The mortar made in this mill is very much better than that made by hand from the material found at Key Quality of mill- 'W'est, as the coarse calcareous sand requires made mortar. ' ^ pulverization to make the mortar work well. It is what the masons call " woolly," when made by hand, and requires a much larger dose of cement or lime, to work properly under the trowel. The brick- work joints with mill-made mortar are observ- ably thinner than with the hand-made mortar, thus giving a saving of mortar per cubic yard. The gain by using the mill, is rather in the superior qual- * These turnings are described in the third step of the method of manipulation practised at Forts Richmond and Tompkins, New York. (Paragraph 369.) HiTDEAULIC CEMENTS, AND MORTAKS. 199 ity and saving of quantity of the mortar, than Advantage of in the cost of mixing, though, when large oper- atives are steadily maintained, there is a great gain under this head, when circumstances favor its easy distribution. Ordinarily, a batch needs to be g^round not ^. . , . " ^ ° Time required m less than seven minutes, and not beyond fifteen making mortar i 1 • IT • -1 with the mill. m mutes irom the time the hme paste is put in the pan. If the grinding be carried much beyond this time, the mortar is decidedly impaired, and sets very slowly. Tliis is ascribed, in part, by Major Hunt to the extreme pulverization of the calcareous' sand, whereby the void spaces are made all small and nearly uniform, and partly to the incessant breaking up of the ' incipient setting by long continued grinding." Fig. 36. 352. Another mortar-mill., successfully used by the designer, M. Greyveldinger, on the works connected with the drainage of the Boulevard de Sevastopol, Paris, is repre- sented by Fig. 36 ; it consists of a hopper of ^;,g^er?mm. Sheet-iron, A, closed at the bottom by a disk, B, surmounted with a cone, C ; the disk and cone receive a rapid, rotary motion by means of the cogwheel D. The hopper is provided with a rectangular opening, E, ]• of a metre (7.9 inches) in width, and of which the height can be varied at 200 PRACTICAL TEEATISE ON LIMES, pleasure by means of a sheet-iron slide controlled by a ratchet and cog-wheel, F. Below the hopper, is a cylindrical spout, G, containing a revolving screw, to the core of which, iron points are attached at regular intervals. Jets of water regu- lated at pleasure by hand, by means of the stop-cock K, are let into the funnel J, at the bottom, through a hose leading to a reservoir of water. 353. The dry ingredients of the mortar having first been roughly mixed with a shovel, and if necessary, passed through a screen, are introduced into the hopper. The rotation of the disk and cone completes the incorporation of the dry mate- rials, and imparts to them a centrifugal motion which in- sures a constant flow from the opening E, into the funnel J, where they receive the requisite supply of water, and pass into the spout G. The motion of the screw carries the mortar to the other end of the spout, completes the mixture, and dis- charges it into barrows or buckets placed to receive it. M. Greyveldinger had four buckets arranged on a revolving plat- form, M. By means of the crank the buckets are passed under the opening in the spout, and thus tilled in succession without w^asting the mortar or arresting the motion of the machine. Two men at the crank L, can work the machine. 354. At the Boulevard de Sevastopol, Paris, motion was derived from a one-half horse-power engine, by means of a belt working on the drum, O. 355. There were required to tend the machine eight labor- Force required to ers, to measure the materials, fill the hopper, ^^^^ take away the mortar, &c., one intelligent fore- man to regulate the opening in the hopper and the supply of water, and one engineer. 356. The average daily expense, neglecting the wear and tear, is as follows : HYDKAULIC CEMEOTS, AND MORTAKS. 201 Nine men at three francs - - - fr. 27 One engineer, - 4 Coal 2 33=$6.10 357. The capacity of the machine was thirty - . r. 1 . 1 N "Its capacity, cubic metres (38.3 cubic yards) oi mortar, per day, of ten hours. Cost of making one cubic metre, 1.10 fr., and of one cubic yard, sixteen cents. 358. Estimating the laborers at ninety-one cents per day, the engineer at $1.50, and supposing the other expenses to remain the same, the cost of making one cubic yard of ^Qg^ making mortar would be twenty-eight cents. The cost mortar with it. of making the mortar at Fort Warren, with the mill consisting of a heavy wheel turning in a circular trough by horse-power, and labor at ninety-one cents per day, was thirty-nine cents per cubic yard. Mr. G.'s mill will answer for the quickest set- ting cements, as only eight seconds of time elapse after the materials receive the water, before the mortar is discharged in- to the buckets. 359. Extensive operations requiring large quantities of mor- tar are frequently carried on by experienced engineers, without the aid of a mortar-mill of any kind. When jj^king mortar ordinary lime mortars are thus made by hand, ^7 i^^^- it is customary and convenient to slake the lime by the first method described, and in no greater quantity than may be re- quired for immediate use. The operation should be conducted under a shed. The measure of sand required for the "batch" is first placed upon the floor, and formed into a basin for the reception of the unslaked lime. After this the latter is put in, and the larger lumps broken up with a mallet or hammer ; the quantity of water necessary to form a stiff paste is let on, from the nozzle of a hose, or with watering-pots, or even ordinary buckets. The lime is then stir- of slaMng^Sne^^ red with a hoe, as long as there is any evolution of vapor, after which the ingredients are well mixed together 202 PEACTICAL TEEATISE ON LIMES, with the shovel and hoe, a little water being added occasionally if the mass be too stiff. At this stage of the operation, it is customary to heap the mortar compactly together, and allow it to remain until required for use. When circumstances admit, it should not be disturbed for several days, and during the pe- riod of its consumption should be broken down and " temper- ed" in no larger quantities than may be required for use from day to day. ^ 360. It is believed that certain slight modifi dons^recommend- cations of this common method of procedure can be made, with decided advantage in the final results. They may be indicated as follows : 361. First. All the lime necessary for any required quantity of mortar should be slaked at least one day be- Slake the hme at . . . i • i i least one day be- Tore it IS incorporated With the sand. fore it is wanted. g^^. Second. The sand-basin, to receive the unslaked lime should be coated over on the in- In a water-tight . i . t t , i c basin. Side With lime-paste, to prevent the escape oi water. AH the necessary 363. Third. All the water required to slake water to bo pour- ,1. .pr, ed on at once. the lime to a stiii paste, should be poured on at once. This will completely submerge the quick- lime. The heap should then be covered over with tarpaulin or old canvas, and left until next day. 364. Fourth. The ingredients should be Mix ingredients, i i • i i i i i and heap up for thoroughly mixed, and the mortar heaped up for future use. 365. The mortar used by Lieut.-Col. J. G. Barnard, Corps of Engineers, in the construction of Forts Richmond and Tomp- kins, ]^ew York harbor, was made by hand. When required for stone masonry, or concrete, it was composed of hydraulic cement and sand, without lime. 366. *Each batch of mortar, or concrete, corresponded to one * These data were furnished by Captain M. D. McMester, of the Engineers, at that time Assis^tant to Lieutenant-Colonel Barnard, Corps of Engineers. HYDRAULIC CEMENTS, AND MOETARS. 203 cask, or 308 pounds net, of hydraulic cement powder. Four men constituted a fi^an^ for measuring: out and ^, . r ^ " ^ Method of mamp- raixing the ingredients, who proceeded to the uiation. several steps of the process in the following order : 367. First The sand is spread in a rectangu- ^.^ ^^^^ lar layer of two inches in thickness. naent together, dry. 368. /Second. The dry cement is spread equal- ly all over the sand. 369. Third. The men place themselves, shovel in hand, two on each side of the rectangle, at the angles, incorporating the facing inwards. Furrows of the width of a ingredients, shovel, are then turned outwards along the ends of the rectan- gle, until the whole bed is turned. The two men on one side thus find themselves together, and opposite the two on the other side, having, of course, left a vacant space transversely through the middle, of double the width of a shovel. They then move back to their original positions in turning furrows as be- fore, when the bed occupies the same space that it did previ- ous to the first turning. The turning is executed by succes- sively thrusting the shovel under the material, and turning it over about one angle as a pivot. Each shovel thus moves to the middle of the bed, where it is met by the one opposite, when each man moves back to the side in dragging the edge of his shovel over the furrow he has just turned. 370. Fourth. A basin is formed, by drawing all the mate- rial to the outer edsre of the bed. . , ^ . , Adding the water. 371. Fifth. The water is poured into the basin thus formed. 372. jSixth. The material is thrown back upon the water, absorbing it, when the bed occupies the same space that it did at the beginning. 373. Seventh. The bed is turned twice, by the process described above. If required for mason's use, the mortar is then heaped up, to be carried when and where required. If for concrete, (the mortar occupying the rectangular space, as at first). 204 PJiACTICAL TEEATISE ON LIMES, Ooncreta ^^9^^^' broken stones are spread equally over the bed. 375. Nvnth. A bucket of water, more or less, (depending upon the quantity of stones, their absorbing power, and the temperature of the air), is sprinkled over the bed. 376. Tenth. The bed is turned once as before, and then heaped up for use. The act of heaping up, bX^stone^s*^^ Wl^^^^ ^^^^ ^^^^^ ^^^^^ ^ second turning. 377. The time consumed in making a batch of mortar is a little less than twenty minutes; in incorporating the broken stones, ten minutes more. 378. When the mortar is required in very small quantities, to avoid deterioration, instead of proceeding to the fourth step of the manipulation, the mixture of cement and sand is heaped up, and the water added and paste formed with the hoe, in sudh quantities as are required. 379. Composition of Mortar. — The mortar at Forts Rich- mond and Tompkins, whether required for stone ^emortar.^ masonry or for concrete, contained one cask* (or 308 pounds net) of hydraulic-cement powder, which produced 3.70 to 3.75 cubic feet of stiff paste ; and three casks, or about twelve cubic feet of loose sand, equal to 2.44 casks (about 9.75 cubic feet), well compacted. These ingredients being incorporated, produced 11.75 cubic feet of rather thin mortar. 380. Convposition of Mortar used at Fort Warren. — The mill-made mortar for the st07ie masonry at Fort Composition of the Fort Warren Warren w^as composed of lime, hydraulic ce- ment, and sand, in the following proportions,viz/. One cask dry cement (325 lbs. net), producing 3.75 to 3.85 cub. ft. of stiff paste. O/ie-AaZ/ cask of Rockland lime (120 lbs. net), producing four cub. ft. of stiflf paste. Nineteen md one-fourth cubic feet of loose sand, equal to fourteen and a half cubic feet well compacted. * The average net weight of a barrel of cement is 308 pounds. HYDEAULIC CEMENTS, AND MOKTAES. 205 These ingredients being well mixed, make eighteen and a half cubic feet of good mortar. For mortar for hrick masonry, the same quantities of lime and cement received but fifteen and three-quarters cubic feet of loose sand, equal to twelve cubic feet well compacted, giving sixteen cubic feet of good mortar. Estimating the cost of the lime at .70 cents per cask of 240 lbs. net, the cement at $1.62^ per cask of 325 lbs. net, and the sand at .50 cents per gross ton, labor at .91 cents, and horses .40 cents per day of ten hours, and we have the following analysis of the cost of the two kinds of mortar used at Fort Warren : MORTAR FOR STONE MASONRY. Mortar for ^ ^^^^ cement, 325 lbs. net=385 cubic feet of paste, at stone masonry. $1.62^ $1,630 \ cask lime^four cubic feet of paste, at 70c 350 14.61 cubic feet sand, at 50c. per ton 496 Labor of men, at 91c. per day 245 Labor of horse, at 40c. per day 028 Total cost of a batch of 18^ cubic feet of mortar, corresponding to one cask of cement $2.15 Cost of 1 cubic foot of mortar ,14^ " 1 " yard " 3.93 MORTAR FOR BRICK MASONRY. Mortar for ^ oement, at $1.63 $1.63 brick masonry. \ cask lime, at 10c 35 12 cubic feet sand, 50 c. per ton 409 Labor of men, 91c. per day 208 " horse, 40c. per day 024 Total cost of a batch of mortar of 16 cubic feet, corresponding to one cask of cement 2.621 Cost of 1 cubic foot of mortar 16^ " 1 " yard " 4.40 381. Some engineers object to the use, in works of impor- tance, of mortar containing so large a proportion of sand as that adopted at Forts Richmond and Warren ; others again very sel- dom add lime to their cement mortars. Touching this last-men- tioned point, recent experiments show, with a uniformity quite satisfactory, that most American cements will sustain, without 206 PEACTICAL TREATISE ON LIMES, any great loss of strength, a dose of lime paste equal to that of the cement paste ; while a dose equal to -J to f the volume of cement paste may safely be added to any ener- Ume^that may be getic Rosendale cement, without producing dete- monars? rioration in the quality of the mortar, to a degree requiring any serious consideration. JSTeither is the hydraulic activity of the mortars so far impaired by this limited addition of lime paste, as to render them unsuita- ble for concrete, under water or other submarine masonry ; while, for constructions not subject to immediate submersion, or the action of the returning tide, it is to be preferred on many accounts. By the use of lime, we secure the of the^Ume^^^^ double advantages of a rather slow mortar — one that is in no danger of setting before it reaches the mason's hand — and a cheap mortar. We also avoid the principal serious objection to the use of a quick-setting mortar, due to careless and tardy attendance on the masons, and conse- quently the constant breaking up of the incipient set on the mortar-board, whereby cements are degraded in energy to a level with ordinary hydraulic limes. 382. If the lime paste had been replaced by cement paste in the Fort Warren mortars, the mortar for stone Comparison of ce- ment and of lime masonry would have cost $5.96 instead of $3.93 mor t^i*s per cubic yard, and that for brick masonry $6.69 instead of $4.40 ; while if lime paste had been used ex- clusively, the cost would have been only $2.53 for the first, and $2.72 for the second. 383. In extensive operations it is well to have a mortar-box and cai't for transporting the mortar from the Mortar-box and ^.-^^ work. The box should be made of stout planks, and be about 5|- feet long, feet wide, and 9 to 10 inches deep, and so arranged that it can be readily slung up underneath the cart, by means of a windlass. Figs. 37, 38, and 39 represent the cart and box used with entire satisfaction at Fort Warren and elsewhere. HYDRAULIC CEMENTS, AND MOKTARS. 207 Fig. 37. Fi-. 39. Why "pointing is necessary. POUsTTING MOETAR. 384. In laying up masonry of any character, whether with common or hydraulic mortar, the exposed edges of the joints will naturally be deficient in density and hardness, and, therefore, unable to withstand the destruc- tive action of the elements ; particularly varia- tions in temperature, producing extremes of heat and cold. It is therefore customary, to fill the joints as compactly as possi- ble, to the depth of about half an inch, with mortar prepared especially for the purpose. This operation is called '''' jpointing^' and the mortar, jpointing mortary The cleaning out of the joints to the requisite depth should take place while the mortar 208 PRACTICAL TREATISE ON LIMES. is new and soft ; and (in stone masonry) when the stones come in contact, or nearly so, the joints mnst be enlarged, to the width of about three-sixteenths of an inch by a stone-catter. 385. Pointing mortar is compounded of a paste of finely erround cement, and clean sharp silicious sand. Composition of . > ^ ^ " pointing in such proportions that the volume of cement paste shall be very slightly in excess of the volume of voids in the sand. These voids should be care- fully ascertained. The measure of sand will generally vary between 2^ and 2f that of the cement paste; or by Aveight, one of cement powder to from 3 to 3J of sand. The mortar, when ready for use, should appear rather incoherent and quite deficient in plasticity. The mixing should take place under shelter, in an iron or stone mortar, or some other suitable vessel, and in quantities of not over Made np in small two or three pints at a time. quantities. • . 386. Before pomtmg, the wall should be thor- The wa 1 should oughly saturated with water, and kept in such 6^ore pointing, ^ Condition, that it will neither absorb water and not allowed from the mortar, nor impart any to it, — two to dry rapidly ^ ^ ... . afterwards. conditions of special importance, the first being paramount. Walls should not be allowed to dry too rapidly after point- ing, but should be kept moist for several days, or better still, for two or three weeks. Pointing in hot weather should there- fore be avoided, if possible ; or else some temporary shelter from the direct action of the sun's rays should be provided. 38Y. For pointing masonry in courses, the tools required be- sides an ordinary mason's trowel are, a straight- en pointS^^^^^ edge? ^b^^t six feet long ; a caulking iron, measuring three inches by one-eighth of an inch on the edge ; a hammer, and some conveniently shaped iron or steel instrument for polishing the surface of the joint in the last stage of the operation. The mortar is put in the joint with the trowel, the straight-edge being placed HYDRAULIC CEMENTS, AKD MOETAES. 209 against the wall, just below the joint, as an Manner of using auxiliary. The joint is then well caulked with the caulking iron, by repeated blows of the hammer, until a film of water shows itself on the surface of the mortar ; after which, mortar is again put in, and the caulking repeated. In using the straight-edge, two men, one at each end, can conveni- entlj work. The operation is continued until the joint is entire- ly full. The mason then rubs and polishes the joint, under as great a pressure as he can exert, and finishes off by using the straight-edge and trowel point, to remove any mortar spread out upon the stones on either side, make the pointing straight, and give the appearance of exact equality in the thickness of the joints. 388. In pointing rubble masonry, the same general direc tions are applicable, but the use of the straight-edge has to be dispensed with. INTEEIOK PLASTEEING. 389. The signification of the term plastering will be limited to the covering of interior walls and ceilings, interior plaster- Exterior plastering will be denominated "stuc- CO," although the technical signification of the latter term is much more limited, and refers to a mixture of white lime, putty, and white sand or powdered marble, used for inside finishing, and to a coating made with this compound. 390. Among the implements used by the plasterer, the prin- cipal ones are the hawk, the plastering or lay- ^ ^ ing-on trowel, the fioat, and straight-edges of various lengths. 391. The hawk, used by the plasterer for conveying and holding the mortar, while he applies it with the trowel, is a piece of board about eleven inches square, and is held by a handle fixed beneath in the centre of, and at right angles to the board. 14 1 210 PEACTICAL TREATISE ON LIMES, 392. The trowel for laying the mortar consists of a steel blade about 3 inches by 9 inches, rounded slight- Trowslt ly at the front end, and a little convex on the face, with a wooden handle on the back parallel to the blade. 393. The hand-float is of wood, similar in shape to the trowel, and is used to rub down the finished work and make it solid, smooth, and even. A cork float is used upon surfaces that are to receive a high degree of polish with the trowel. 394. The mortars used for inside plastering exclusively, are Mortars used for " coarse stuff," "fine stuff," "gauge stuff," or plastering. hard-finish, and "stucco." 395. Coarse stuff is nothing more than common lime mor- tar, suitable for brick masonry, to which has Coarse stuff. , ^ ^ ^ . ^ iV • i -. i i been added a quantity oi well-switched bul- lock's hair, to act as a kind of bond. The following proportion is a good one : 1 cask lime = 8 cubic feet of paste. Sand 16 to 18 cubic feet. Hair 1^ do. do. 396. When ample time for hardening cannot conveniently be allowed, it will be advantageous to replace 12 to 15 per cent, of the lime paste in the coarse stuff, by an equal volume of the paste of hydraulic cement or plaster of Its uses. X ./ 1 Paris. Coarse stuff forms the principal part of all inside plastering. For the second coat, in three-coat work, the quantity of hair given above may be slightly diminished. 397. Fine stuff is made of pure lump-lime slaked to paste with a moderate quantity of water, and after- Fine stuff. -. wards diluted with water to the consistency of cream, and then placed where it can stiffen by evaporation to the proper condition for working. 398. Fine stuff is used for the finishing coat, but never with- out the addition of sand or plaster of Paris, ex- its uses. . . cept for what is termed a " slipped coat." HTDEAULIC CEMENTS, AND MORTAES. 211 Even for slipped work, a little fine sand is sometimes added, to make the paste work more freely. 399. Gauge, stvff, or hard-Jmish^ is composed of fine stuff (lime pntty) and plaster of Paris, in proportions regulated by the degree of rapidity required in ^ard^fiiJsh^' hardening. As it sets rapidly, it is always pre- pared in small quantities at a time, not more, for instance, than can be used up in half a^i hour. It is used for the finish- ing coat of walls, and for cornices, mouldings, and other kinds of ornamentation. For finishing, the proportions are three to four volumes of lime putty to one volume of plaster of Paris, and for cornices, &c., about equal volumes of each. 400. Stucco is composed of lime putty and white sand, with . a preponderance of the latter. The usual pro- portions are three to four volumes of sand for one volume of putty. Its uses. Stucco is only used for the finishing coat. 401. According to the English plasterer's nomenclature, ap- plying the first coat, which is always done with coarse stuff, is technically termed " rendering," TomSiclature. if on masonry ; " laying," if on laths in one or two coat work; and "pricking up," if on laths in three-coat work. In the United States, the first coat of three-coat work on laths is called the " scratch" coat, instead of the " pricked up" coat. The other terms, with the English signification, are retained here. 402. In " rendering," the joints of the masonry should be raked out to the depth of half an inch, the sur- face freed of dust, and the walls moistened. Precautions in Old masonry, if smoky or greasy, should also rendering. be scraped out and roughened. 403. One-coat work, — Plastering in one coat without finish, either on masonry or laths, that is, either ren- ... One-coat work. dered or laid^ though the most inferior kind of covering for walls, is frequently used for attics and kitchens in 212 PEACTICAL TEEATISE ON LIMES, f ^ ^ ^ cheap houses, and for cellars, vaults, and places of like character. The coarse stuff is applied in the same manner as the first coat in two-coat work, described below. A light hand-floating is of great advantage to this kind of work. 404. Two-coat work. — Plastering in two coats is done either in a " laying coat and or in a " screed coat and The screed coat is also called the floated coat. It is more commonly applied as the second coat in three-coat work. Laying the first coat in two-coat work, is resorted to in common work instead of scr ceding^ when the finished surface is not required to be exactly even, to a straight- edge. It is performed in a pretty thick coat, — say half an inch, — more care being taken to secure a smooth and even sur- face than in the scratch coat for three-coat work, because, in the latter case, all the irregularities are removed by the screed coat which follows. In both the laying and the wertempered ^c^^*^^ ^0^*^' the coarse stuff should be well tempered, and of such moderate consistency, that when pressed with force against the laths, it will penetrate between them, and bend down over them on the inside, so as to form a good key. A common fault in lath- latSng^ ^"S' ^® t^ place the laths so close together, as to render it impossible to obtain a strong key. 405. Except for very common work, the laying coat should be hand-floated^ to give it density and solidity. This is done by usins: the float in the ris^ht hand, and a hair Hand-floating. . ^5 brush holding water, in the left ; both instru- ments passed quickly over the wall at the same time, the brush preceding the float, and wetting the surface to the required degree. The firmness and tenacity of plastering is very consid- erably increased, by hand-floating, and at a moderate expense. 406. Hand-floating must take place while Must take place . ° while the mortar the mortar IS green, when it is intended as a ifi green. preparation for the setting coat. HTDKAULIC CEMENTS, AND MOETAES. 213 407. In two-coat work, performed in a screed coat and set^ tli-e first coat must be put on in " screeds" and " filling out." The screeds are strips of mortar six to eight inch- es in width, and of the required thickness of the described first coat, applied at the angles of the room, and parallelly, at intervals of three to five feet, all over the surface to be covered. These screeds are carefully worked on, so as to be accurately in the same plane, by the frequent appli- cation of the straight-edge in all possible directions. When these have become sufficiently hard to resist the pressure of the straight-edge, the " filling out" of the interspaces flush with the surface of the screeds takes place, so as to produce a continuous, straight, and even sur- The screed coat to face. The surface should then be hand-floated as described above. 408. After the first coat, whether it be a laying coat or a screed coat, has become partially dry, so as to resist the pressure of the trow^el, it is ready for the setting, or finish- ing coat. This may be either in slipped work^ Finishing. stucco^ hastard stucco^ or hard-finish. In all cases, the surface to receive it must be roughed up with a birch or hickory broom, or some suitable instrument, and if too dry, must be moistened. 409. A slipped coat is merely a smoothing ofi* of a browii coat (coarse stuif ) , with the smallest quantity of lime putty that will answer to secure a comparatively even surface. It is seldom sufficient to cover the filJ^^^i^^^ browning up entirely. 410. A small quantity of white sand, seldom Sand sometimes . . Ill us^d in the sUpped exceedmg three per cent., is sometimes addea coat, when shp- to the putty to make it work more freely. The ^^rtTtt trowel alone is used for this kind of finish. It answers very well for surfaces that are to be finished in distem- per, or with paper-hangings of common or medium quality. 411. Finishing or setting in stucco is suitable for a screed 214 PEACTICAL TEEATISE Oii LIMES, Stucco flntshiug: coat, but is never applied to laying or to inferior work, on account of the extra labor which it Applied with requires. The stucco is applied with the trowel, to the thickness of about one-eighth of an inch, keeping in view the fact that the straight surface gained by screeding can only be preserved by applying the set in ^ , , , a coat of uniform thickness. The stucco is well To be hand- floated, hand-floated, the water-brush being used freely while so doing. After the wooden float has been used, the surface is again floated in the same manner with the cork float, which being soft, leaves the surface in good condition for polish- PoHshing ^^^* '^^^ polishing is performed with the trowel and brush; this operation, however, is omitted, when the stucco is intended to present a rough appearance for painting, or for any style of ornamentation in distemper. 412. bastard stucco, like stucco, is also used Bastard stucco . i i r • i • as a settmg coat on screed work. It is done in stucco mortar, containing a smaller quantity of sand than is Done m stucco suitable for genuine stucco, and sometimes a mortar with a rj^^^^.^ -g haud-floatiug in thig diminished dose ^ ^ ^ ^ of sand. kind of work, and the trowelling is done witL less labor than that conferred on trowelled stucco, as above Is superior to described. Bastard stucco is superior to slipped shpped work. work as a preparation for papering. 413. Rard-finuli is applied with the trowel. Hard-finish. iti/^t •itp - t t to the depth oi about one-eighth oi an inch. It may be polished with the water-brush and trowel, but the hand- float cannot be used upon it. Hard-finished walls, though fre- quently painted, are by no means so well adapt- hand-floated ^^^^ '^\Vi^ of covering as stuccoed walls. They may, however, be well finished in distem- per; a suitable composition for this purpose consists of ten May be well pounds of Paris white and one pound of glue, finished in colored as required. The advantage of hard- distemper, finish over stucco consists in its requiring less HYDEAULIO CEMENTS, AND MOBTAES. 215 Three-coat work. Scratch, coat. labor to apply it. It is extensively practised in the United States. 414. Three-coat worh. — The first and second coat are termed respectively the scratch coat and hrown coat, and the third is either hard-finish^ or stucco. 415. The scratch coat, or first coat, is applied in the same manner as laying^ with this exception, that, as it is simply intended to form a good foundation for the screeding which follows, its thickness need not exceed one- quarter to three-eighths of an inch. When completed, and partially dry, though still quite soft, the mortar is scratched over nearly to its entire depth, with a pointed stick, in two systems of parallel scorings at right angles to each other, run- ning diagonally between the extreme limits of the surface cov- ered. These scorings are about two inches apart, and assist the adhesion of the coat which follows. 416. The second coat is applied in " screeds" and " filling out," in all respects as described in screed-coat and set work. 417. The finishing or setting is also applied as before de- scribed 418. Table XY. gives an estimate of labor and materials for 100 yards of lath and plaster w^ork : TAELE XV. Materials. Rockland lime Lump lime for fine stuff. Plaster of Paris Laths Hair Common sand White " Nails Mason's labor Laborer Cartage Cost of 100 yards $25.50 Three coats Hard-finished work. 4 casks. 2,000 4 bushels. . 7 loads bushels. 13 lbs 4 days $4.00 .85 .10 4.00 .80 2.00 .25 .90 1.00 3.00 2.00 Two coats Slipped work. 3^ casks , 2,000 3 bushels. 6 loads. . . 13 lbs. . 'i^ days. $3.33 4.00 .60 L80 .90 6.12 2.00 1.20 216 PEACTICAL TREATISE ON LIMES, EXTEEIOR PLASTEEma, OR " STUCCO." 419. Mortars composed of the paste of common lime and sand, either with or without the addition of uStfo? outsSr P^^^*^^ Paris, are unsuitable for covering work. surfaces exposed to the direct action of the ele- ments. 420. Lime, Lowever, forms the basis of many excellent out- side stuccos, and, by proper treatment, may be rendered very durable. 421. If the water for mixing the mortar contains coarse sugar or molasses in solution, the effect on the solidifi- water ^ cation of the outer surface of the stucco is very beneficial. This method is practised by the natives of India, as reported by Captain Smith in his transla- tion of Yicat. The proportions for the sweetened water are about one pound of sugar to eight gallons of water, except for the outer or hand-floated coat, in which one pound of sugar should be mixed with two gallons of water. 422. Powdered slaked lime and smith's forge scales mixed up with bullock's blood in suitable proportions, scales ^ ^^^^^ make a durable and moderately hydraulic mor- tar, which adheres well to masonry previously coated over with boiled oil. It is used for outside stucco. 423. The custom in the United States is to use hydraulic cement and clean sand, mixed up with a sufli- SS^r^"" ciency of water to produce the ordinary consist- ency of mortar for plastering, and in such quan- tities that all may be used up before the batch begins to set. The proportions are one volume of stiff cement paste to 1.66 vol umes of damp, compact sand ; or, if measured dry, one volumo of cement powder to two volumes of loose, dry sand. 424. "When masonry, either of brick or stone, is to be stut ^ ^ . coed, the joints should be raked out to the depth same. of half an inch ; the surface cleansed of dirt and HYDEAULIC CEMExNTS, AND MORTARS. 217 dust, and tlien thoroughly wetted, (with a hose, if possi- ble,) so that the mortar will not be too rapidly deprived Df its moisture by absorption, and its strength and density thereby impaired. If the surface is greasy, it should be scored with an axe. 425. The mortar is applied in two coats laid on in one oper- ation. That for the first coat should be some- ^ ^ „ First coat of what thinner than that for the second, in order rather thin that it may be pressed into thorough contact with the wall, and enter and fill up all the joints and other openino^s. The second coat is applied upon the ^ 1 .1 1 1 . n f 1 Second coat. first, while the latter is yet soit, so that the same workman finishes ofi" as he goes along, never covering more than two or three superficial feet at one time. The two eoats thus laid should form one compact coat, of about one-half inch in thickness. The finished stucco should be kept shaded from the direct rays of the sun ^^^^ protected for some days, and moistened from time to f'^^^ sun, and ' kept moist. time. 426. As a modification of the above process, the first coat is sometimes omitted, or rather replaced by a wash of thick cream of pure cement, applied with a Slve^process.^ stiff brush, from time to time, just before the mortar is put on. If the brush-work is faithfully done, and not allowed to dry before the surface receives the stucco, an inti- mate contact and firm adhesion are sure to result. 427. A necessary precaution in this kind of work is to secure the services of a faithful workman, one who will Precaution. not spare his strength, or Jay any oi the mortar on too loosely, or on too dry a surface ; otherwise, there will be portions without adhesion, that will be thrown off on the first occurrence of frost. 428. After the stucco has been on for a few days, the whole surface should be carefully Sltriortu^' Bounded with a small iron instrument like a 218 PEACTICAL TREATISE ON LIMES, tack-hammer, when all places destitute of adhesion will be readily detected by their hollow sound. From these, the stucco should be carefully removed, the surface roughened and wetted, and new mortar applied. 429. Many of the best cements of the United ^ion^^°^^^* States are of too dark a color to furnish an agreeable shade for the exterior of dwelling houses. A very simple remedy for this is to use light colored or white sand, in whole or in part. When this is not practicable, lime paste may be added, without material injury, until its volume equals that of the cement paste. Lively tints may be obtained by a judicious use of the several ochres, singly or combined. 430. The principal causes of the gradual de- SZarTiftheal terioration and decay of mortars left in the open air are : 1st. Ordinary changes of temperature, producing expansions and contractions, which, being unequal in the several materials ordinarily used in masonry, tend to cause a separation of the mortar from the more solid parts. 2d. Alternations of freezing and thawing, by 2d cause. which exfoliations and disintegrations are pro- duced. 431. As a p-eneral fact, within certain limits. General fact. . r. ^ . solid bodies resist the action oi irost m propor- tion to their density, or inversely as their capacity for imbibing water ; but this rule is not capable of strict application, and it is quite possible for one mortar to be a better Some mortars « - . n . . i i resist frost better pi'oot against irost than another less porous than others that i^i its character. Moreover, of two mortars of are less porous. ' equal density, one may be materially impaired in tenacity and hardness by the action of frost, while the other exhibits few, if any, evidences of its effects. 432. Immersed in water, more especially sea-water, mortars HYDEAULIC CEMEOTS, AND MOETARS. 219 are subjected to the solvent action of the salts -^^^^^^ of certain — principally the sulphates of magnesia and salts in sea- soda, — and certain gases contained in the water. Between tides, are witnessed the effects of a combination of the foregoing causes, modified and sometimes augmented by the circumstance, that the protecting coat of marine animals and shells, to which many submarine construc- tions in a measure owe their stability, is be^tween the tides, seldom found at all, and at best, but very im- perfectly, in positions not subject to constant submersion. It is hence, not an uncommon thing to see the mortar of that portion of a structure between high and low water, in a more advanced stage of decay than that above or below. 433. The effects of frost on mortar may be ascertained by subjecting it to repeated action of artificial frigorific mixtures. To do this, the mortar should be four or five months old, and in the form of a prism of effects of fros*t^ suitable size, say 2" X 2" X 8". Ascertain the strength before the freezing trial, by breaking the prism, near one end, on supports four inches apart. Then saturate the largest piece with water, put it in a thin, water-tight bag of India-rubber or gutta-percha cloth, and immerse it in one of the frigorific mixtures given below, where it should be kept until the temperature of the mixture rises above the freezing point. The sample should then be laid in some warm, dry place, until it is completely thawed out. After eight or ten repetitions of this process, the strength of the mortar should be ascertained as in the first instance, when the effect of frost will become known. 220 PRACTICAL TREATISE ON LIMES, TABLE XYL FRIGORIFIC MIXTURES. Mixtures. 1 Parts. 1 Thermometer sinks. Mixtures. 1 Parts. 1 Thermometer sinks. Snow or pounded ice 2 1 1 From any temperature -to- 5° F. Snow or pounded ice . . 5 2 1 0 ^ 1 tto-12<'F. ^ ) Snow or pounded ice Common salt 24 10 5 5 ^to-18° F. Snow or pounded ice.. Common salt 12 5 5 3 ■ 1) 1 Vto-25oF. Nitrate of potash . . . Nitrate of ammonia . . . 434. The process of a French chemist, M. Brard, for esti- M. Brard's pro- mating the probable effects of frost on stone, cess. given in the "Annales de Chimie et de Physi- que," volume 38, is equally applicable to mortar. It may be stated very briefly as follows, viz. : Prepare a cold saturated solution of sulphate of soda, then bring it to the boiling point, and suspend in it, by a string, for thirty minutes, the sample under trial. Then pour the liquid, free of sediment, into a flat vessel, and suspend the stone over it in a cellar. When efliorescences appear on the specimen, it must be dipped in the solution, say two or three times a day for about a week ; at the end of which time the quantity of earthy sediment in the ves- sel, collected on a filter and weighed, will indicate the effect to be expected from frost on the same sample. The sample under trial might also be of such a form, that its strength could be tested before and after subjection to the above process. M. Brard, however, makes no recommendation of the kind, and it is perhaps unadvisable when operating upon stone. 435. The subject of the action of sea- water on mortars, par- Effect of the sea- ticularly the pozzuolana mortaa's used in the water on mortars. Mediterranean Sea, and the conflict of opinion thereon among European engineers, has been referred to in brief terms in Chapter lY. To estimate by preliminary ex- periments the probable effects of sea-water on mortars, in any HYDRAULIC CEMENTS, AND M0RTAH8. 221 given case, is a difficult thing : in fact, there are so many ele- ments of uncertainty involved in it, that many engineers deem it impossible. ^Nevertheless, M. Yicat proposed in 1857 "a new mode of tryins; sea-mortars in the labora- ,^ ^, _® ^ M. Vicat's new tory," which, as it emanates from high au- method of testing thority, is entitled to notice. The mortar to be tried, when mixed up, is pressed, while green, into an earthen vessel. The vessel should be full and should be kept closely covered, to prevent contact with the air. At the expiration of one month break the vessel, so as to free the T ,1 . ^ j^i. • i Immerse the mor- mortar, and then immerse the latter m water ^g^^ ^ solution containing: four or five thousandths of anhy- of anhydrous sui- c> phate of magnesia drous sulphate of magnesia. Reaction takes place,— 'the water dissolves the sulphate of lime formed, its presence being detected by oxalate of ammonia, which yields a precipitate of oxalate of lime. 436. The solution of sulphate of magnesia should be re- newed until no more of this oxalate is formed, Renew the so- and even beyond that point, for greater cer- lution. tainty. 437. If the sample shows no external signs of decay after ten months, break it open and examine the frac- Examination of ture. If the interior is in a state of perfect pres- specimen, ervation, treat some fragments, taken from the inside, by the game process applied to the original sample. If these frag- ments remain intact, for a given time, (yet to he ascertained) the mortar may be pronounced suitable for sea constructions. For cement mortars, twenty months' successful resistance to the solution of sulphate of magnesia is considered ample by M. Yicat. For mortars of pozzuolana or hydraulic lime, it is not considered entirely safe to assign a minimum of two years ; while it is by no means impossible for a mortar that fails to stand this test to sustain immersion in the sea, from the fact that the protecting coat, before referred to, is formed on the exposed surface. PRACTICAL TREATISE ON LIMES, 438. M. Minard, Engineer des Fonts et Chaussees, (retired,) concludes a review of M. Yi cat's work in the Jliin^on!'''^'' Annales des Fonts et Chaussees" for 1858, as follows : " The only means of knowing the action of the sea on a new mortar is to immerse it in the sea, in the locality where it is to be used. Substituting chemical operations in laboratories for the sea itself, involves us in new disasters." HYDKAULIO CEMEOTS, AND MOETAES. 223 CHAPTEK YII. A'M. ^Jf^i Crete or Beton. — These terms, by no means origin- sj/ionymous, have become almost strictly so by usage. As generally understood in modern practice, they apply to any mixture of mortar (generally hydraulic), with coarse materials, such as gravel, pebbles, shells, or fragments of Definition of terms tile, brick, or stone. Two or more of these mate- " concrete" and rials, or even all of them, may be used together. More strictly speaking, as originally accepted, the matrix or gang of heton possesses hydraulic energy, while that of concrete does not. 440. As lime or cement paste is the cementing substance in mortar, so mortar itself occupies a similar relation to concrete or beton. Its proportion should be determined in accordance with the principle, that the volume of the cement- y^q^q^<^-^q^ of ing substance should always he somewhat in ex- matrix to the „ , , ... coarse materials. cess of the volume of voids m the coarse mate- rials to he united. The excess is added as a precaution against imperfect manipulation. 441. In England, some years ago, when concrete first came into extensive application, common or feebly hydraulic lime, such as the Blue Lias limestone yields, was generally used for the cementing substance. The quicklime, having been first reduced to a powder by mechanical means, was incorporated with the sand and coarse materials in the dry Btate. Water, in sufficient quantity to slake Concrete of quick- the lime, being then added, the concrete was 224 PRACTICAL TREATISE ON LIMES, rapidly mixed up with a png-mill or with shovels, conveyed away in barrows or carts, and used while hot. Used while hot. ^ ^ ^ . -, ^ . -, it was employed extensively for loundations, or as a substratum in light and yielding soils. In order to se- cure the requisite degree of compression and density, it w^as customary to throw it into its position from a height, and some- times to ram it afterwards. In mixing the materials for fat Its contraction concrete as usually composed, there is a and subsequent contraction of about "I in volume ; this is suc- expansion. i i , • i i • ^ ceeded by an expansion, when the setting takes place, of about f of an inch for every foot in height, which does not entirely cease for a month or two afterwards. 442. Concrete of fat or feebly hydraulic lime has been ex- tensively employed in Europe for making artifi- S^uropf "^^ ^^^^ ^^'^ blocks of any required form and dimensions, which, after attaining in the air a degree of hard ness and strength sufficient to render the handling of them safe and practicable, are laid up in walls with mortar joints, like ashlar-work. The practice of 443. Of late years, the practice of laying fat crete^getting into ^^^'^^ Concrete hot has grown into disrepute disrepute. among English architects and engineers. They now prefer that the lime should be thoroughly slaked, reduced to a pulp, and made into mortar with the sand before the coarse materials are added. This process is always followed in making beton. The advantages of it are, immunity from the danger of partial slaking before use, superior homoge- neousness in the mass, and economy in the amount of lime required. 444. [N'either the English method of making concrete to be English methods ^^^^ while hot, nor the practice of forming ar- httle used in the tificial blocks which must attain in the air a United States. , , r. • - • i. j? i.i certain degree oi resisting power beiore they can be placed in the work for which they are designed, have ever received any extensive application in the United States. HYDRAULIC CEMENTS, AND MORTAES. 225 445. Natural hydraulic cement, to which, un- Hydraulic cement der circumstances requiring only a moderate the^united^^^ degree of energy and strength, paste of fat lime States. is sometimes added, in quantities seldom greatly exceeding that of the cement, is almost invariably used as the basis of the con- crete mortar ; and the concrete, when made, is at once deposited in its allotted place, and well General practice, rammed in horizontal layers of about 6 inches in thickness, until all the coarser fragments are driven below the general surface. The ramming should take place before the cement begins to set, and care ^Precautions in ^ ^ ' ramming, and m should be taken to avoid the use of too much the use of water wa^er in the manipulation. The mass, when ready for use, should appear quite incoherent. Concrete should , . . ^ , . , . . be incoherent be- contammg water, however, m such quantities, fore ramming, that a thorough and hard ramming will produce a thin film of free water upon the surface, under the rammer, without causing in the mass a gelatinous or quicksand motion. 446. It will be found in practice that cements vary very consid- erably in their capacity for water, and that fresh ground cements require more than those that have become stale. An excess of water is, however, better than a deficiency, particularly when a very energetic cement is used, as the capacity of this substance for solidifying water is great. A too rapid desic- cation of the concrete might involve a loss of ^anTdefidencj cohesive and adhesive strength, if insufficient of water, water be used. 447. Concrete is admirably adapted to a variety of most im- portant purposes, and is daily growing into more extensive use and application. For foundations in damp and yielding soils, and for subterranean and submarine masonry, under almost every combination of circum- ^^ges of "^concrete, stances likely to occur in practice, it is superior to brick- work in strength, durability, and economy ; and in some exceptional cases, is considered a reliable substitute for the be&t 15 * 226 PRACTICAL TREATISE ON LIMES, stone, while it is almost always preferable to the poorer varieties. 448. For submarine masonry, concrete possesses the advan- Advantages for ^^g^j ^^^t it may be laid without exhausting the submarine works, water, (which under the most favorable circum- stances, is an expensive operation,) and also without the aid of a diving-bell, or submarine armor. On account of its continuity and impermeability to water, it is well suited to the purposes of a substratum in soils infected with springs, for sewers and conduits, for basement and sustaining walls, for columns, piers, and abutments, for the hearting and backing of walls faced with bricks, rubble, and ashlar-work, for pavements in areas, base- ments, and cellars ; for the walls and floors of cisterns, vaults, &c. Groined and vaulted arches, and even entire bridges, dwelling-houses, and factories, in single monolithic masses, with moulded ornamentation of no mean character, have been con- structed of this material alone. 449. The methods pursued in mixing mortar on the fortifica- tions of Boston and New York harbors, and at Key West, Florida, have been described in brief and general terms in Chapter YI., paragraph 346 and following. The manner of incorporating the broken stone fragments, as practised on the works at New York, is also briefly alluded to in the 7th, 8th, 9th, and 10th steps in the method of manipulation, paragraphs 373, 374, and 375. When the coarse fragments vary very much in their sizes, and these have been separated by a screen, as may be the case with gravel and pebbles collected in the usual way, a more thorough incorporation may per- haps be secured by spreading them first on the platform with the smallest sizes at the bottom, and then distributing the mortar uniformly over the mass. This process was followed in Boston, and is thus described by Lieutenant Wright, in his work on mortars : 450. " The concrete was prepared by first spreading out the gravel on a platform of rough boards, in a layer from eight to HYDEAULIC CEMENTS, AIS^D MORTAES. 227 twelve inches thick, the smaller pebbles at the Incorporating the bottom and the larger on the top, and after- coarse ingredi- , J. ,1 , 'i? 1 ents by ha.nd. wards spreading the mortar over it as uniiormly as possible. The materials were then mixed by four men, two with shovels and two with hoes, the former facing each other, and always working from the outside of the heap to the centre, then stepping back ; and recommencing in the same way, and thus continuing the operation until the whole mass was turned. The men with hoes worked, each in conjunction with a shov- eller, and were required to Txih well into the mortar^ each shovelful, as it was turned and spread, or ratker scattered on the platform by a jerking motion. The heap was turned over a second time in the same manner, but in the opposite direc- tion, and the ingredients were thus thoroughly incorporated, the surface of every pebble being well covered with mortar. Two turnings usually sufficed to make the mixture complete, and the resulting mass of concrete was then ready for transpor- tation to the foundation. " The success of the operation, however, depends entirely upon the proper management of the hoe and shovel, and though this may be easily learned by the laborer, yet he seldom ac- quires it without the particular attention of the overseer. "^"^ 451. In Europe, machinery is sometimes employed for incor- porating the ingredients of concrete, when large quantities are required. 452. The concrete for the bridge over the River Theiss, Hun- gary, completed in the year 1857, was prepared with a machine extensively used in Germany at that time. It consists of a cylinder about four metres (13 feet) in length. Machine used in and 1.25 metres (four feet) m diameter, open at Hungary for mix- both of its extremities and revolving fifteen to '""^ concrete, twenty times per minute around its axis, which is inclined to the horizon at an angle of six to eight degrees. The stone and mortar are thrown from the wheel-barrow into a hopper, which empties them into the upper end of the cylinder. 'Jhe mixture 228 PRACTICAL TREATISE ON LIMES, is produced by the rotation of the cylinder, from the lower end of which the concrete drops into either wheel-barrows or carts. Tlie inner surface of the cylinder is smooth and coated with sheet-iron ; the proportion of the material is measured by reg- ulating the number of wheel-barrow loads of mortar and oi stone, as these are poured into the hopper. The incorporation of the ingredients is complete. The cylinder is kept in motion without cog-wheels or pulleys, simply by means of a leather strap which passes over its exterior surface ; the motive power was furnished by a locomotive, which worked a heavy mortar- mill at the same time. This machine easily mixes from 80 to 100 cubic metres (105 to 130 cubic yards), in ten hours, and (when worked in connection with a mortar-mill) at a trifling expense. (See Annates des Fonts et Chaussees^ Vol. XYII., 1859.) 453. Another machine for making concrete, the mortar hav ing been previously mixed, is represented by Figures 40, 41^ 42, 43, and 44, the latter being a top view. It is always used in a vertical position, and being comparatively light and port- able, and worked altogether by hand, possesses the advantage that, for founding in dry positions, or where the water has been exhausted, it can be suspended with its lower end resting on „ , . ^ . the position to be occupied by the concrete, and Machine for tcxsl- ^ ^ . ing concrete one handling of the materials be thereby saved. worked by hand. A«i^' i ' i jy As it IS moved successively irom one position to another, during the progress of the work, it is followed up by laborers who level off and ram the concrete already de- posited by it. In using this machine, the mortar and coarse materials, after having been measured, are placed in the top compartment, Fig. 40. The levers, hh^ Fig. 44, being then put in motion, the materials fall successively from one compart- ment to another, little by little, and finally reach the bottom thoroughly and completely mixed. As the top compartment becomes empty, the ingredients for another batch of concrete are placed in it. HYDEAULIC CEMEXTS, AND MORTARS. 229 r 0 u Fig. 40. Fio:. 43. Fig. 44. 454. Wheel-barrows are generally used for conveying the concrete from the platform on which it is ... 1 mi 1 Wheel-barrows mixed, to its position m the work, ihe plat- for conveying form should be so arranged, if possible, that concrete. ':he distance to be passed over will not exceed twenty or twen- 230 PEAOTICAL TEEATISE ON LIMES, tj-five yards. The concrete having been emptied from the barrows into its position, is levelled off with a hoe, and rammed in layers six to ten inches in thickness. 455. The instrument used for ramming concrete is generally a cylinder of w^ood six to eight inches in diameter, and about eight inches high, shod with sheet-iron on the lower end, and having a handle, three to three and a half feet long, in- serted in the other end, in the prolongation of the axis. For greater convenience, a hand-piece is sometimes attached at a suitable height on the handle. 456. When concrete is made by a machine, particularly one Sling-cart for con- very portable, and not conveniently kept in veying concrete. ^losc proximity to the place to be concreted, a sling-cart, like that described in paragraph 383, would be a valuable auxiliar to the work. The box slung underneath the cart, could be replaced by a platform arranged to receive a certain number of square boxes of convenient size for handling when filled. With a view to economize labor, the mill should be adjusted so as to discharge the manufactured concrete di- rectly into the boxes. 457. The device for confining the concrete layers laterally, so as to 2:ive to the finished work the desired A boxing neces- ^ sary in making form, will, of course, to a certain extent, depend concrete walls. , -. ... ^ .i i on the character and position or the work, ii required for foundations, or for the backing of walls, or in any position not exposed to view, or not requiring a smooth finish, a rough, movable boxing, composed of two or more planks, with their edges together, and well secured by battens on the back, will suffice. 458. When it is required to give a smooth finish to the con- crete wall, and when it is essential that the direction and po- sition of the surfaces should be maintained with great accuracy, special attention should be directed to the boxing. 459. A device by Mr. E. E. Clarke, of ISTew Haven, Conn., to be used in erecting concrete houses, has been pronounced HYDEATJLIC CEMENTS. AISTD MOETAKS. 231 both convenient and satisfactory, while it apparently leaves nothing to be desired on the score of simplicity improved mov- and economy. It consists essentially of a wood- ^^1® boxing. en clamp, the vertical parallel arms of which can readily be adjusted by means of traverse screws, to any required thick- ness of wall. These arms sup- port the planking which deter mines the thickness of the wall, and are attached — one fixed, and the other movable — to a horizontal brace. When in use^ the entire apparatus is kept in position by securing this brace to some fixed point of sup- port. In carrying up the walls of a building, these points of support are provided on the in- side, being vertical posts secured to the ground, in the first in- stance by braces, and afterward to tlie flooring joists of the uj)- per stories. Fig. 45 rep- Fig. 45. Hollow walls. Fig. 46. resents this apparatus in position for laying a hoL low concrete wall, not intended to be furred on the inside. The hollow is secured by means of a movable plank, called a core, a trifle thinner on the lower than on the upper edge, so that it can be moved after the concrete is rammed around it. The ties between the inner and the outer walls may be common bricks, and these are placed under the core" in each of its positions, as the building progresses. The " core" is notched on the lower edge, so as to fit down upon the ties flush with 232 PRACTICAL TREATISE ON LIMES, their lower beds. Fig. 46 represents a side view of the core. The width of the hollow should be from two to three inches, the thickness of the inner wall from four to five inches, and that of the outer wall ten inches and upwards, as determined, to give the requisite strength. The hollow is sometimes placed in the centre of the wall, a practice which may be admissible in buildings not intended for residences. For these latter, when a thickness of five inches for the inner wall is exceeded, it should be furred for plastering, to prevent the condensation of moisture. 460. The apparatus in common use on the continent of Europe and in some portions of South America, in constructing pise work, would answer in forming walls of L^tS'work!"^ concrete, and would, besides, be less expen- sive, and perhaps more easy of adjustment and use than that shown in Fig. 45. It consists simply of a box- ing of planks, kept in place by upright posts on the exterior, at suitable distances apart, say four or five feet. The lower ends of the posts are mortised and keyed into horizontal cross- pieces called futtocks, which reach entirely through the wall and are withdrawn, and the holes filled up, after the box is filled with the pise or concrete, and a new course is to be com- menced. The upper ends of the posts may be kept in position by similar cross-pieces, but the more common practice is to confine them by lashings of rope or cord, tightened or loos- ened at pleasure by a stick used as a lever for twisting up the lashings. The wall may be made hollow by a core like that shown in Fig. 45.* * Pise work is formed of clay or earth rammed in layers. The best material is clay which contains small gravel, and is of such consistency, that it can be dug with a spade. The clay must first be thoroughly beaten up and passed through a screen to remove stones larger than a hazel-nut, and then moistened to a uniform consis- tency, so that, when moulded into form by hand, it will not fall to pieces under water. In forming walls, the pise is rammed, like concrete, in layers from three to four inches in thickness, care being taken not to carry up the walls too rapidly, lest the lower portion be pressed out of shape, while damp and plastic, by the weight of the superincumbent mass. Except in very dry climates, the exterior of walls in pise should be protected, by a coat of mortar, from the action of rain. The walls should be thoroughly dry, before being plastered. . HYDRAULIC CEMEJNTS, AND MORTAES. 233 461. Within the last ten years, the practice of Hollow concrete buildiiiff concrete houses with hollow walls, has ^^'^^^^ becoming ^-^ ' extensively used. received considerable attention, both in the United States and in Europe. In Sweden and Northern Ger- many, it is quite common. The facility with which the fire, smoke, and ventilating flues can aSranteo-es! be arranged in the wall, by using movable tubes during the progress of construction, the partial immunity from risks by fire, the security against the ravages of rats and other vermin, and the equality of inside temperature through sudden changes of weather, secured by this method of construc- tion, judiciously followed, specially recommend it to the at- tention of American architects, particularly in those districts where the ingredients of concrete are plentiful and inexpen- sive, and timber or good building stone scarce. There are many recent examples of its successful application among us. 462. Fence or railing posts, of the minimum size consistent with the requisite degree of strength, may be firmly set and retained permanently in their upright position by surrounding them with concrete, or rather, by inserting them in a concrete foundation. The mortar for this purpose need . . . Post foundations. not be very rich in cement, and m quantity, might barely exceed the volume of voids in the coarse mate- rials. One foundation properly prepared would serve for an indefinite period of time, and the posts could be renewed as often as decay rendered it necessary. It is believed that by slightly tapering the lower end of the posts so as to render their removal simple and easy, and by lowering the entire foundation so as to place its upper surface below the reach ot a plough, an excellent and inexpensive system of movable fences for farmers' use could be devised. 463. The quick -setting varieties of hydraulic Use of cement for cement have recently been quite extensively Mac^hf^ffor mak- applied to drainage and sewerage purposes, the pipes. in a mode at once new and pecuHar. The mortar, composed 234 PRACTICAL TREATISE ON LIMES, FiR. 48. of 2 to 2^ measures of clean coarse sand to one measure of the cement powder, mixed with a small quantity of water, is mould- ed into pipe in sections of suitable length, say about three feet, and of any required diameter of bore up to 3^ or 4 feet. These sections, on being joined together with cement mortar, form a continuous water-tight tube. The junction may be secured by means of the ordinary " hub" joint, or by the " bevel" joint referred to below. The essential parts of the machine for manufacturing these pipes are : First^ a sheet-iron cylindrical "case" in which the pipe is formed, its diameter being of course the same as the exterior diameter of the pipe. This cylinder is open longitu- dinally on one side, the two edges along the opening being turned out at right angles, thus forming flanges, by means of which the case can be firmly held together with wooden clamps. Second^ a solid cast-iron cylindrical " core" equal in diameter to the " bore" or interior diameter of the pipe. When this " core" is placed concentrically in the case, the cylin- drical opening between the two, forms the mould for the pipe. Thirds a hollow cylindrical cast-iron ram- mer or " plunger" which fits over the core, so as to pass freely between the " core" and the " case." It is used for compressing the mortar. These several parts are represented separately by Figs. 48, 49, and 50, in which a, is the " case" clamped together at ^, i; h, the " core," and c, the " plunger." They are combined together into a machine, worked by hand, which is represented by Fig. 51, in which A is the outside case and Fig. 49. Fig. 50. HYDRAULIC CEMENTS, AND MORTAES. 235 13, the " core" not yet in position. This is suspended above the case. The plunger C is partially seen just below the hopper. The bottom of the mould is composed of a ring, d, d, Fig. 49, which gives the interior of one end of the section of pipe the bevel form of joint. A corresponding exterior bev- el on the other end of the pipe is secured by making the lower end of the plunger of the required form (see Fig. 48). When the mould is filled the core is forced down into a pit below the machine, leaving the mould- ed pipe and the case con- taining it intact. These are then set on one side until the mortar has attained such condition of hardness that the case can be removed, which is easily done after the clamps are taken off. The motion of the plunger, (?, the pressure on the mortar, and the removal of the core, 2>, are all regulated by suitable machinery worked by hand, which need not be explained. Different sized pipes can be manufactured with the same machine by changing the essential parts, that is, the case, core, and plunger. In making large pipe, the plunger is dispensed with, and the requisite degree of density conferred by constantly ramming or " tamping" with crowbars. The bevel on the upper end is then formed by a ring (the reverse of that below) forci- Fig. 51 236 PEACTICAL TREATISE OX LIMES, bly driven on when the case is full. By using i to 4J- parts of sand to one of cement, the pipe becomes porous and makes a good water iilterer.* 464. In laying concrete under water, an essential requisite Laying concrete ^^^^ should not fall from any height, but under water. be deposited in the allotted place in compact masses, otherwise the cement would be washed away from the other ingredients, thereby seriously affecting the strength of the work. It is moreover proper that the concrete should contain a larger proportion of mortar, and that this latter should be rather richer in cement than w^ould 111 suffice under other circumstances. The most common method of depositing concrete is by means of a box of from nine to twelve cubic feet capacity, or by using a wooden pipe or conduit with its lower end resting on the posi- tion to be occupied by the concrete. A modi- fication of this last mentioned de- Tremie used at . Fort Carroll, Vice was used in laying the concrete Chesapeake Bay. fou^^jation of Fort Carroll, Chesa- peake Bay. It is called a tremie (Fig. 52), is made of boiler iron, and consists essentially of a truncated conical base, called the stock or hopper, and a vertical shaft in five sections. The lower section is permanently attached to the base, the other four are arranged with joints, and can be readily connected together. The tremie is suspended on a wooden frame or mov- able crane having four cast-iron wheels, running pig-, 52. on a railway, by means of which the whole machine is moved * Two manufactories of this pipe are in operation in the vicinity of New York, viz. : Pierce & Co. Sixty-first street, near Third Avenue ; and Knight & Crawford, Jersey City. The prices of some of the principal sizes per lineal foot are as fol- lows : 3 inch bore, 8 cents ; 6 inch bore, 16 cents- 10 inch bore, 30 cents ; 15 inch bore, 62 cents; 18 inch bore, 85 cents. HYDEAULIC CEMENTS, AND MORTARS. 237 and regulated, as the work progresses. An upward and downward motion of the tremie, by which, in conjunction with the column of concrete in the shaft, the materials are com- pressed as they issue from the hopper, is secured and con- trolled by a powerful screw on the top of the frame. Thi8 screw is worked by two men. 465. The sections of the sea-wall at Fort Carroll filled with concrete by the tremie, were, in the clear, 8 feet by 8 feet horizontal section, and fourteen feet vertical height, equal to 896 cubic feet each. The time occupied in filling Q^j^ntity of work one of them was 9 hours 51 minutes (one day), the force employed consisting of 29 men including the over- seer. Of this time 2 hours and 13 minutes were occupied in filling the submerged portion of the tremie stock, at the commencement of each day's operations. This was done by m-eans of a cylindrical tub of such a size as to pass freely up and down within the tremie, and arranged to open at the bot- tom, like the concrete box described in paragraph 466, Fig. 53. The tremie stock was filled in this manner, until the con- crete rose above the level of the water. After this, the concrete was thrown into the tremie with hods. In deep water, it is sometimes necessary to load the tremie. It is important that the upper surface of the column of concrete should be kept above the surface of the water. When, in the progress of the work, the base of the hopper reaches the w^ater level, the tremie is dispensed with, and the concrete is rammed in the usual way. 466. Fig. 53 represents an end view of the semi-cylindrical box for lowering concrete. It is in two parts, which join along the line o\ a, and open around the Fig. 53. hinge, o\ so as to let the concrete through the bottom. A 238 PRACTICAL TREATISE O'N LIMES, pin at a keeps the two parts together until the box reaches the desired position, when it is withdrawn by Box for lowerino' r> , i -, concrete in water. ^^^^^ns of the COrd, C. It opens at the After the concrete is placed in the box, the bottom. top should be closed by sheet-iron covers, s, s, to prevent a rush of water over the mixture. 467. An improvement in the device for fastening the two parts of the box together, and one which, while it would render it impossible for careless or unfaithful workmen to open the box prematurely, and allow the cement to An improved fast- „ , ening, which be- lall through the water, would also secure a con- wiK^r th^*^ box ^' siderable saving of labor, has been recently in- tom^^^ ^^** ti'^^cluced by M. Sesquieres, Superintendent of Roads and Bridges in France. The box is of a prismatic form, of -pj/V cubic yards capacity, and the bottom of it opens of its own accord, when it reaches and rests upon the soil or the concrete previously laid, and not before. This re- sult is secured by a bar, attached longitudinally to the lower part of the box, and carrying a latch on each extremity, working into corresponding catches in such a way that an upward pres- sure on the bar, obtained in eifect when the loaded box is low- ered to its position, unfastens the bottom, allowing the mass of concrete to fall out when the box is raised again. M. Ses- quieres prefaces his description of this box, in the Annales des Fonts et Chaussees, for 1854, by the following Se^squie^res^^ ^' I'emarks : " Frior to the year 1841, ' beton' was laid under water in the hydraulic works exe- cuted in the Department of Tarn and Garoune by means of a box, of the form of a truncated pyramid, suspend- Depositmg con- ' ^ ^ . . Crete by inverting ed at its extremity by a rope, winding around an axle worked with heaving bars ; a rope is also at- tached to the middle of the bottom of the box, by means of which it can be inverted in order to empty it. This method is defec- tive, as the box must be turned upside down to be emptied, which operation cannot be performed, unless the box is suspended at a HYDRAULIC CEMENTS, AISTD MOETARS. 239 certain height above the bottom of the water ; the consequence is that the beton becomes divided and washed off, so that, when it reaches the bottom, nothing is left of it but sand and pebbles. An unscrupulous contractor could even empty the box as soon as it had disappeared under the water," &c. 468. It may be remarked, however, that among French en- gineers, the relative advantages of the two r> T / Relative advan- methods oi depositing con(;rete reierred to (one tages of the two by inverting the box, and the other by opening methods of depos- 'J in 5 .7 r iting concrete not it at the bottom), have not yet been definitely settled by French settled, some preferring and practising one, and some the other. The size of these caisses a immersion is also a question still in controversy. M. Baudenioulin recommends the capacity of y',^ cubic metre. Experience seems to show that larsfer ones are better, as not favorino^ the ^ . The size of boxes formation of large quantities of laitancef^ At also a question of Calais, boxes of yV cubic metre (3J cubic feet) ^^^^^^'^'^^sy. capacity were first used by M. Nehon ; these were subsequent- ly replaced by those of \ cubic metre (1 1\ cubic feet) capacity, which in their turn gave way to others, tirst of 1 and then of 2 cubic metres capacity, the constant aim being to lessen the volume of laitance formed. Preference was given to large sizes. 469. It is considered injurious to ram concrete deposited under water. To obtain the necessary density, concrete not to we must depend on the rake or some similar be rammed under 1 11 11 water. instrument gently used, to keep the layers ap- proximately level, and on the weight of the superincumbent mass. Some eminent French engineers recommend the forma- tion in a single mass or layer of concrete work , , , ^, J? *£. J 1 . Formation of sub- under water, wli ether tor toundations, plat- merged masses of forms, or areas. The only advantage to be de- ^^^^''^^^^ ^^^^^^ ' . mass. rived from this method, over the one of thin, continuous layers formed successively over extensive areas, ap- * See paragraph 474 on the subject of laitaryie 240 PEACTICAL TREATISE ON LIMES, pears to be the increased density of the portion first laid. This, before it begins to set, becomes well compressed by the weight subsequently added. 470. In founding with concrete, it is usual pHes.^ ^ ' surround the place to be occupied by the work with sheet-piles, driven somewhat below the level of the base of the structure, and then to remove the When sheet-piles ^^^^ requisite depth. In certain cases, can be dispensed when the soil is very firm, and the foundation with. ' has to reach to a small depth only, the piling need not be used ; in others where these conditions do not ob- tain, it may be necessary to use piles of extra strength and length, and to support them against the pressure of the earth To prevent cur- by braces at top. In order to prevent currents wash the^on?^^ that might wash the concrete, holes should be left in the piling near the top, so that the water will remain at the same level within and without. In founding over springs, the action of which might drench Precautions when the concrete, and wash out the cement, they founding over • i i i i i springs. might be stopped oii by tarred canvas stretched over the area.. 471. Concrete walls are frequently revetted or faced with stone. In fact, this is a common method at the present day of constructing sea-walls, and sustaining walls, oftonrte walls. The stone facing is generally in courses, com- posed of headers and stretchers alternately. The stretchers are so jointed on the end as to be a few inches longer on the back than on the front. The vertical joints on the headers, being formed at a corresponding angle with the face, while the tails of the headers, reaching entirely through the concrete backing, are left undressed, the wall becomes a firm and connected system of dovetailing. In constructing a wall of this kind, as soon as a course of facing Manner of eon- ^ ^ ... . Btructing such a stone is laid, the back to its entire thickness is levelled up with concrete, rammed in compact HYDEAIJLIC CEMENTS, AND MOETAES. 241 layers not exceeding one foot in depth, the surfaces of the stone having previously been freed from dust, moistened with water, atffl coated over with mortar, in order to insure the adhesion of the concrete. 472. Submarine walls of this description cannot be laid without exhausting the water within the area to be built upon, or using the diving-bell, or some other method of subaqueous construction. 473. For laying the sea-wall for the cover-face of Fort Tay lor, located in 7 ft. of water, at mean low tide, Major Hunt, of the Corps of Engineers, devised a coffer- Description of dam surrounded with a canvas case. This devised^b^ M^j case consists of two parts firmly sewed together, Hunt. viz. : the upright part, or case proper, and the fl.ap. The case, when in use, stands vertically against the sheathing of the dam on the exterior, and its height should exceed somewhat the depth of the water where it rests. The flap lies out on the bottom, and has a width of 20 ft. all around the case, its object being to cut off infiltration through porous soils, when the coffer-dam is exhausted of water. The size of case at Fort Taylor is adapted to laying nearly 50 running feet of wall. In order to connect the section under construction with the part previously laid, a slit is left in the case, at one end. .474 When concrete is deposited in water, a pulpy, gelatin- ous fluid is washed from the cement, and rises to the surface. This causes the water to assume a milky hue, hence the term laitance. which French ensiineers apply to this , . . / 1 -, Laitance. substance. As it sets very imperiectly, and, with some varieties of cement, scarcely at all, its interposition between the layers of concrete, even in moderate quantities, will have a tendency to lessen, more or less sen- sibly, the continuity and strength of the mass, effelti!*"'^''* This pulp is produced more abundantly in sea- water than in fresh water. Its composition, as determined at the " Ecole des Ponts et Chaussees" in 1856, is given below. 16 242 PRACTICAL TEEATISE ON LIMES, The sample was a thick jelly, of a dirty white color, possessing d,n alkaline reaction, and was produced in laying concrete in the Mediterranean Sea. The analysis gave the following results : Analysis of laitance from the Mediterra- nean Sea. Insoluble in water Silicious sand 2.888 Silica 2.692 Carbonic acid 2. 5^0 Alumina and traces of iron 34t Free caustic lime 345 Combined lime 3.998 L Magnesia 2.027 Total insoluble in water 14.867 Soluble in water 3.462 Water and loss 81.671 100.000 475. The water of the Mediterranean contains nearly three pounds of magnesia per cubic yard, and the theory of this pulpy Theory of the formation is that the immersed concrete gives formation of up to the Water free caustic lime in a finely di- laitance. • i i ^ • ■, . . . . vided state, which precipitates magnesia m a light and spongy form. This precipitate, interposing itself among particles of the mortar thrown into suspension by the motion of the liquids, produces the laitance so much com- How the evil plained of. The evil might be lessened by might be operating in a limited space where the sea- water could not be constantly renewed, or by using mortars possessing sufficient hydraulic activity to retain all The laitance is t^ieir free caustic lime ; but the usual means is usually removed to use several pumps for its removal. These by pumps. should not be too large and powerful, on account of the injurious effects, on the mortar, of strong currents; even small ones should be operated with care. The proportion of the laitance is greatly diminished by using large immersing boxes, say of one to one and a half yards' capacity. 4:76. The nature and size of the coarse ingredients of con HYDEAULIC CEMENTS, AND MORTAKS. 243 Crete will depend, of course, upon local circuin- , -iTT-r, . , p 1 J 1, Nature and size stances. W hen a mixture oi gravel and peb- of the coarse bles can be had, at a slidit advance on the cost ingredients of ' Y concrete. of collecting the same, it is generally used, on the score of economy, in preference to fragments of brick or stone. For a similar reason, oyster-shells are sometimes used, almost exclusively. 477. When concreting is carried on in connection with stone- cutting, and stone-masonry operations in gen- eral, the spalls, chips, and irregular fragments chips. made by the cutters, can be converted into ex- cellent concrete material at. a moderate cost. This cost will, of course, vary somewhat with the kind of masonry and the quality of cutting, generally ranging, however, between fifty- five and seventy cents per cubic yard for labor only, allowing nothing for the refuse stock used. Fisr. 54. 478. The preparation of concrete material by Breaking con- ^ ^ ••111 Crete by hand an hand, from large masses of stone is considerably expensive opera- tion. more expensive. 479. Figure 54 shows a longitudinal section of the essential 244 PEACTICAL TREATISE ON LIMES, parts of a stone-breaking machine in use on the New York Central Park. A, A', A", A'" is the frame of Stone-breaking , . • . , . , . , . , machine used in cast-iron m a smgle piece, which receives and New York and supports the Other parts. This frame consists of elsewhere. ^ ^ ^ two parallel cheeks A connected together by the parts A', A, "A''' (shaded with diagonal lines). The arc, B, represents a fly-wheel, of which there are two, one on each side of the frame, working on a shaft having its ^Zt^^^"" bearing on the frame. This shaft is formed into a crank E between the bearings, and car- ries a pulley C to receive a belt from a steam-engine or other driver. The fly-wheel, the section of fly-wheel shaft, the pul- ley, and the arc described by the centre of the crank in its revo- lution, are indicated by dotted circles. F is a pitman or rod which connects the crank with the lever^ G. This lever has its fulcrum on the frame at H. A vertical piece I stands upon the lever against the top of which piece the toggles J J have their bearings, forming an elbow or toggle-joint. K is fixed jaw^ against which the stones are crushed. This is bedded in zinc against the end of the frame, and held back to its place by cheeks L that fit in recesses in the interior of the frame on each side. M is the movable jaw. This is supported by the round bar of iron K which passes freely through it, and forms the pivot upon which it vibrates. O is a spring of India rubber, which is compressed by the forward movement of the jaw, and aids its return. Every revolution of the crank causes the lower end of the movable jaw to advance towards the fixed jaw about \ of an inch and return. Hence, if a stone be dropped in between the convergent faces of the jaws, it will be broken by the next suc- ceeding bite ; the resulting fragments will then fall lower down and be broken again, and so on, until they are made small enough to pass out at the bottom. The distance between the jaws at the bottom limits the size of the fragments, and may be regu- lated at pleasure. A variation to the extent of f of an inch HYDEAULIC CEMENTS, AND MOETARS. 245 may be made by turning the screw-nut, P, which raises or lowers the wedge^ Q, and moves the toggle-hloch^ R, forward or back. Further variations may be made by substituting for the toggles, J J, or either of them, others that are longer or shorter ; ex- tra toggles of different lengths being furnished for this pur- pose. The broken stone passes from the machine Screening of the mto a revolving cylindrical screen standmg at broken stone, an inclination to the horizon, by means of which the material is separated in fine, medium size, and coarse stone. The meshes of this screen are small at the upper end, medium size at the middle, and large at the lower end. Fragments which pass entirely through the cylinder are returned to the machine and broken again. 480. The product of these machines per hour, in cubic yards of fragments, will vary considerably with the character of the stone broken. The proper speed is about 200 revolutions per minute. 481. The following table will give an idea of the capacity of these stone-breakers : TABLE XYII. Sizo of chamber at top. Product per hour. Power required. 10" X 5" 15" X 5" 20" X 1" 3 cubic yards. 6 " 6 horses. 9 " 12 " Capacity of the machine. 482. Another excellence of the machine is the superior quali- ty of its work. For concrete, a cubic yard of stone requires about 25 per cent, less of cement than stone broken by the hammer, for the reason that the former packs closer. The harder the stone, within certain limits, the greater the quantity the machine w^ill break, as the product runs off more freely. Tlie 15-inch machine weighs about 8,100 lbs ; the 10-inch, 5,800. 246 PRACTICAL TEEATISE ON LIMES, 483. Concrete foundations of Forts Richmond crX of F^ortT" ^'^^ Tom:pkins,—T\ie concrete for the founda- Richmond and tions of Forts Eichmond and Tompkins, New Tompkins. York harbor, was composed of hydraulic cement, sand, and granite fragments in the following proportions, viz : — 1 cask (308 lbs. net) of hydraulic cement which produced 3.65 to 3.70 cubic feet of stiff paste. 3 casks or 12 cubic feet of loose sand, equal to 9.15 cubic feet well compacted, The sand and cement being well incorporated, yielded 11.75 cubic feet of rather thin mortar, to which were added 5 casks (20 cubic feet) of granite fragments, producing a batch of concrete measuring 21.75 cubic feet when rammed in the foundation. Concrete for su- 484. Concrete for swperstructures at Forts FortrRt'hmond ^iGhmond and Tomjpkins.—Fov superstruc- and Tompkins. tures, the concrete contained 11.75 cubic feet of mortar as above, and 16 cubic feet of broken stone fragments. 485. The concrete foundation of Fort Tompkins contained about one-twelfth of its bulk of stone masses of various dimen- sions, measuring from J to f of a cubic foot, each rammed into the heart of the wall as the concrete was laid. 486. Cost of concrete foundation of Fort Tomjpkins. — Esti- mating the cement at 85 cents per barrel, (which was the average Cost of concrete of pi"ice during the summer of 1859, when that Fort Tompkms. portion of the work supplying these data was laid), the broken stone at eight cents per barrel, which is merely the cost of the labor expended in reducing the chippings of the stone-cutters to the proper size for concrete, and allowing six cents per barrel for excavating and screening the sand, which was procured from a deposit close at hand on the premises, and nothing for water, the cost of the concrete was $2.46 per cubic yard, rammed. This was reduced to $2.26 per cubic yard, by the introduction of the unbroken masses of irregular size, allowing nothing for the granite stock thus consumed. These HYDRAULIC CEMENTS, AND MORTAES. 247 results are the averages of an entire season's operations, as exhibited in the following table : 48T. TOTAL COST OF LABOR AND MATERIAL EXPENDED IN LAYING CONORHTB FOUNDATION AT FORT TOMPKINS, DURING THE YEAR 1849. Labor. Wages of sub-overseer 42.2 days at $2 per day $84 40 " mason setting plank 82.8 days at $2 per day 165 60 " laborers assisting) 153.6 days at $1 per day 153 60 ** laborers transporting and ramming concrete 2,911.8 days at $1 per day 2,971 80 Total cost of labor $3,3t5 46 Materials. 4,096 casks cement at 85 cents $3,481 60 12,288 " sand at 3 cents 368 64 20,480 " broken stone at 8 cents 1,638 40 5,488 64 Total cost of labor and materials $8,864 04 Total number of cubic yards of concrete laid, excluding the stone masses rammed in 3,60637 Cost per cubic yard of pure concrete $2 46 Deduct for stone masses rammed in 20 Cost per cubic yard as laid 2 26 If the price of the cement had been the same as at Fort "Warren, viz. ; ^ cent per lb., the cost of one cubic yard of pure concrete would have been 3.52 488. The following is an analysis of the composition and cost of the concrete employed for laying the foundations of the sea-wall at Lovell's Island, Boston harbor : 1 barrel of cement, 308 lbs. net ... . > 3.70 cubic feet of paste.' J ^^'^^ 8 cubic feet sand at 51 cents per ton .20 Labor .09 Cost of 10 cubic feet mortar $1.83 Gravel, 30 cubic feet .28 J Making concrete, .130 day ^ Transporting do., .065 " V , =.28 Packing do., .037 " ) Tools, implements, &c .13 Cost of 32.30 cubic feet of concrete, Cost of 1 cubic yard laid 2.52i $2.11 248 PEACTICAL TREATISE ON LIMES, 489. For the concrete backing of the sea-wall at Lo veil's Island, the proportions exhibited in the following analysis were adopted : Cement, 1 cask = 308 lbs. = 3.70 cubic feet paste $1.54 Sand, 812 lbs. =:7.89 cubic feet dense, producing 9.8 cubic feet mortar 21 Gravel, 26.4 cubic feet 25 Making mortar 065 Making- concrete 02 Transporting do 065 Packing do 09 Tools, implements, &c 12 .24 day. . .40 Cost of 1.09 cubic yard «=» 2.52 Cost of 1 cubic yard laid = 2.31 Concrete may 490. Concrete containing common lime. — Ex- contain a large . proportion of ccpt iinder circumstances of rare occurrence, common lime, concrete may receive a large proportion of the paste of fat lime without serious prejudice to its hydraulic en- ergy and strength, and with great advantage on the score of economy. 491. For founding above water level, the following propor- tions have been employed in Boston harbor, and elsewhere : Cost of con- Cement, 1 barrel = 308 lbs. =3.70 cub. ft. paste. .,.$1.54 Crete contain- Lime, \ cask, = 2.50 cub. ft paste 22 ing lime. Sand, .67 ton =14.6 cub. ft. dense 33 Producing .475 cub. yds. mortar = 12.825 cub. ft. Making mortar in mills, .475 yds., at 39 c 18^ Cost of .475 yds. = 12,825 cubic feet of mortar $2.27^ Granite, 21.249 cubic feet, at 70 c. per yd 55| Gravel, .61 ton, at 50c per ton 30|^ Making, carrying, and packing concrete 42 — 1,28 Cost of 1.355 cub. yd. concrete $3.55^ Cost of 1 cub. yd. concrete, laid $2.62^ 492. If we increase the volume of lime paste, in the concrete last mentioned, to four times that of the ce- JS^a^tat^of toe. «ient paste, thereby giving to the mortar the following composition, viz. : HYDEAULIC CEMENTS, AND MOKTARS. 249 Cement paste 1.24 cubic feet. Lime paste 4.96 " " Sand 16.6 " " The corresponding cost per cubic yard of concrete will be $2.03 493. It is customary to cover the upper tier of arches in casemated fortifications with concrete, formed, for carrying off the water, into ridges and valleys, by a series of inclined plane surfaces, which, after receiving a coating of lime mortar, are covered with bituminous mastic. This mastic adheres but in- differently to cement mortar, which, on account Bituminous mas- of its comparative impermeability to air and here^weii to con- moisture, does not absorb the steam and rari- crete. fied air produced when the hot mastic is applied. The sepa- rating medium, thus interposed between the mortar and the mastic, produces air bubbles in the latter while hot, thereby seriou-sly impairing its quality as a covering ; objections which do not obtain when lime mortar is used. In cases where the concrete covering is not relied Remedy, upon in part to render the casemates bomb proof, the principal portion of the roofing, being intended sim- ply to give the required form to the roof surfaces, may be of a cheap quality of concrete, enough cement being used, however, to insure its setting sufficiently quick to prevent interruption to the progress of the work. The composition given above, estimated to cost $2.03 per cubic yard, would perhaps be good enough for this purpose. The upper, or exterior portion, to the depth of five or six inches should be rich and contain no lime. The following is the analysis of that used at Fort Warren for this outer coat : Cement 308 lbs. = 3.70 cub. ft. of paste 1.54 Sand (including waste) 7.4 cub. ft. = .372 ton, at 50 c 18^ Broken bricks, 15.4 cub. ft. = .57 cub. yds. at 35 c. per yd. .20 °f ^^f^^?* xx ^• 4. ^, n uiv^on T, concrete at Fort Makmg mortar, 7.7 cub. ft. at 39 c. per cub. yd 11 barren. Making, transporting, and packing concrete, &c 40^ Cost of 18.5 cub. ft. of concrete $2 44 Cost per cubic yard, laid , 3.56 250 PEACTICAL TEEATISE OlS^ LIMES, 494. Some blocks of concrete were made in the harbor of New York, in 1860, in the course of these experiments, by in- jecting a thin paste of light colored Rosendale cement without sand, into boxes filled with coarse gravel and bj^a^pastfo™^^ pebbles, and submerged in sea-water. The cement injected cement was mixed, in some cases with fresh, in under water. ^ ' others with sea water, in the proportion by volume of 48 of water to 100 of cement powder. It was poured through a tin pipe 1^ inches in diameter and 18 feet in vertical height. The boxes were 5yVx5y»o-"x36" clear dimensions, and were perforated with small holes, to facilitate the ejection of the water. At the expiration of some weeks, the boxes were taken from the water, and the blocks removed. The cement was found to have penetrated to the remotest corners of the boxes, and to have filled perfectly the interstices in the gravel and pebbles. ^ . -, 495. The cement mixed with sea-water fur- The paste mixed with sea-water nished by no means a stable concrete. A few not good. dsLjs, after exposure to the air, it began to crack all over the surface, and was very deficient in cohesive strength and solidity. That mixed with fresh w^ater retained its sharp corners and angles perfectly ; no cracks or other evidences of decomposition appeared. The blocks remained solid and compact and when broken for examination it appeared that the adhesion to the pebbles was very good, and that every void was perfectly filled. 496. There is reason to believe that the cream of cement would be improved by the addition of 8 to 10 per cent, of fat lime paste, and that the long pipe can be advantageously re- placed by a syringe or force pump of suitable The cement paste n n ' • i . 2.^ j. j.i i ^ would be im- torm ; tor it IS evident that the pressure due to proved by a little the vertical height of the pipe, supposing a perfect fluid to be used, is only partially se- cured by the semi-fluid cement, and can only be augmented by HYDEAULIC CEMENTS, AND MORTARS. 251 thinning the paste, or by lengthening the pipe. Any arrange- ment, by means of which a stiffer paste can be injected, would be an improvement. 497. We infer from the foregoing results that a thin paste of Eosendale cement is worthless for concrete, if mixed up with sea-water, while with fresh water, it will harden when injected nnder water, either fresh or salt, and affords the means of submarine construction, that may be of great value under certain circumstances. ' 498. TABLE XYin * Mortars. Composition in volumes. .62 .43 .38 .35 .34 32 1.69 1.24 1.12 1.05 .96 Concretes. Compo- sition in volumes 1.56 1.03 1.— 1.— 1.45 1.11 1.00 1.40 1.11 1.03 1.40 1.14 1.01 1.45 1.13 1.03 1.45 1.13 1.03 Resistance of the concrete to rupture. W, or breaking vpeight in lbs. found by experi- ments. 10 days, 1,087 800 856 492 20 days, lbs, 1,093 1,322 1,065 646 778 889 778 954 492 668 404 315 271 227 149 163 141 114 114 191 136 176 448 463 359 346 289 240 304 218 202 192 196 181 a «j ? Calculated value of 72, or resistance per square inch to a force of exten- sion. 60 days, o 'C : lbs. ^1=^'^ 1,376 1,504 1,480 481 1294 1016 906 430 633 600 542 437 404 392 326 306 381 337 370 92 99 95 92 10 days. 20 day.s. 60 days, lbs. lbs. lbs. 92 261 196 208 123 190 190 123 103 83 73 63 45 48 42 37 37 55 42 51 262 339 257 IGO 215 231 105 113 117 93 90 77 66 80 60 56 55 56 52 328 360 352 122 299 235 219 109 157 148 135 111 104 101 85 77 98 88 96 * From experiments made at Boulogne-sur-mer hy Engineer Yoisin, published in ** Annales des Fonts et Chaussees" for 1858. 252 PRACTICAL TREATISE ON LIMES, Table XYIII shows the resistance of prisms of concrete made with the natural Portland cement of Boulogne- sur-mer. The prisms were 5.9056 inches square in cross section, and were broken by a load at the middle, while resting on supports Strength of con- cretes of natural Boulogne Port- land cement. Id} a 31.496 inches apart. The formula W = f R wasused in deducing the values of R. (See paragraph 554.) 499. TABLE XIX. GIVINa TEIALS MADE AT FORT ADAMS, R. I., BY GENERAL TOTTEN, IN JUNE, JULY, AND AUGUST, ISST, OF THE STRENGTH OF CONCRETES MADE IN DECEMBER, 1836. Composition of the mortars. Granite fragments with 1 measure of mortar. Granite fragments ^ with 2 measures of mortar. Brick fragments with 1 measure of mortar. Brick fragments Avith 2 measures of mortar. Stone gravel witli 1 measure of mor- tar. Stone gravel with 2 measures of mor- tar. Brick gravel with 1 measure of mor- tar. Brick gravel with 2 measures of mor tar. Stone fragments grouted. Brick fragments grouted. E = R = R = R = R = R ^ Cement, 1.00 Sand 0 Lime 0 Cement, 1.00 Sand 50 Lime 0 Cement, 1.00 Sand 50 Lime 25 ! Cement, 1.00 Sand.... 1.00 Lime 0 i Cement, 1.00 Sand.... 1.00 Lime. . . .25 Cement, 1.00 Sand.... 1.50 Lime .. .0 Cement, 1.00 Sand.... 1.50 Lime 25 o o • r-(ci "fl • • g s s Cement, 1.00 Sand.... 2.00 Lime 25 4973 4142 2778 3989 2721 2045 2056 lost 1574 311 260 174 251 171 129 130 99 4068 4983 5064 4088 5366 1547 8537 1643 1972 255 312 317 313 336 3242 2117 4127 3254 1788 2136 1567 3649 204 133 259 205 113 134 98 229 2S05 5047 2826 4232 1178 3655 3856 2320 4803 1T6 316 277 265 74 229 242 146 301 1097 1049 66 1240 78 1256 79 1066 67 2347 4247 2655 1295 3351 147 267 167 82 210 5437 6183 3088 lost. 4726 341 887 194 296 6025 5712 5480 8142 2699 377 358 343 197 169 3278 1846 2012 1158 117S 206 116 127 73 74 1634 2305 2869 2726 2770 103 145 180 171 111 The results given in the above table show the weight in HYDRAULIC CEMENTS, AND MOETARS. 253 pounds required to break prisms of concrete, 12" x 6" x 0" the distance between the supports being 9 inches. In tlie table, one measure of mortar corresponds to the vokime of voids in the granite, or brick fragments used, and two measures to twice that vobime. Tlie values of R are computed for this work from the formula, paragraph 55i. The cement was from Ulster county, I^ew York, and the lime from Fort Adams, and was very slightly hydraulic. The volume of voids in the granite and brick fragments was .48 and in the stone and brick frag- ments .39. The lime paste was passed through a paint mill just before using it, and the coarse fragments were drench- ed with water just before mixing them with the mortar. 500. The quay walls and certain parts of the Mole of Al- jjiers, as described by M. Poirel in "Memoires . m V -, I M 1 Mole of Algiers, sur les iravaux a la mer, 1841, were built by pouring and ramming concrete into caissons, sunk in position, and lined with tarred cloth, a system borrowed from the Italian engineers, who repair breeches in walls by casting down bags of concrete, from which the mortar exudes in sufficient quan- tity to bind the whole together. M. Poirel also employed concrete as artificial blocks of 360 cubic feet each, weighing 22 tons, formed and allow^ed to set in wooden moulds in the air For concrete immersed green, the mortar was composed as follows : paste of fat lime, one volume ; powdered j)ozzuolana, two volumes. The mortar for forming the artificial concrete blocks in the air was composed of : paste of fat lime, 1 ; powdered pozzuo- lana, 1 ; sand 1. In both cases, one volume of the mortar mixed with one volume of broken stone, gave one volume of concrete in place. The pozzuolana which succeeded best was the Roman, and it was used in the state of fine powder, being, in fact, quite inert if left in coarse grains, like sea-sand. 501. In executing the new Graving Dock, 'Ro. 3, at Toulon, 254 PR AC l ie AL TREATISE ON LIMES, Graving Dock, M. Noel, the engineer, adopted a concrete foun o. 3, at Toulon. elation, laid under water while green. It was 400 feet long, 100 feet wide, with an average thickness of 15 feet, all in one mass. This area was first enclosed on three sides with close piling, lined on the inside with tarred canvas. Having thus prepared a solid foundation at the requisite level, the concrete hearting of the side, head, and gate walls of the dock was laid under water in caissons of appropriate dimen- sions, leaving nothing but a lining or revetment of masonry to complete these walls. The total quantity of concrete was 554,300 cubic feet in the bottom, and 418,600 cubic feet in the sides. The mortar of this concrete was composed of one vol- ume of paste of fat lime, and two volumes of finely pulverized Italian pozzuolana. 502. At Marseilles, M. Pascal made use of immense blocks Jetties at Mar- concrete, allowed to harden in the air three seilies. months before immersion, for the protection of the outer or seaward slopes of the jetties, which enclosed the basins and docks of that harbor. The concrete blocks weio^hed about 22 tons each, and were formed in moulds of 353 cubic feet capacity. The mortar was composed of three parts of Theil hydraulic lime slaked by immersion and measured in powder, and five parts of sand ; for a more active mortar, one-third of the lime was replaced by an equal quantity of Italian pozzuolana. One volume of this mortar was mixed w^ith two parts of broken stone. For concrete to be immersed immediately, two volumes of mortar to three volumes of broken stone were used. 503. M. Pascal expressed his preference for good hydraulic lime, over any pozzuolana mixture, or any natural or artificial cements, provided plenty of time could be allowed to harden before immersion. 504. The Cherbourg breakwater is composed of a hearting of rubble, d pierre perdue^ upon which rests, at the level of ordi- nary low water, a bed of concrete seven feet thick, composed IIYDKAULIO CEMENTS, AND MORTAKP 25^ of lime mortar and broken stone. The parapet resting on this platform is thirty feet wide at the base and thirtv-one feet high towards the sea. Recently it was found necessary to protect the exposed base of the wall seaward by huge artificial blocks capable by their inertia of resisting the waves of the Atlantic. These blocks contained 720 cubic feet each, and weighed forty-four tons, and were formed by rubble masonry, built up by hand on platforms, in positions subjecting them to submersion at each returning tide. The stone used was mostly the schistous rock of the neighbor- hood, and the mortar was composed of either Parker's or Me- dina cement and sand, or Portland cement and sand. The three cements were sometimes mixed together. The propor- tions were one volume of Parker's or Medina cement to one and a half of sand, or one volume of Portland cement to two of sand, or intermediate proportions, when the cements were mixed together. Rubble masonry was preferred to concrete for these blocks, as no wooden moulds were required. These blocks have satis- factorily withstood the action of the waves for fourteen years. 505. At Dover and at Alderney hrealcwaters Portland cement has been extensively used in forming artificial blocks which were laid in the jetties instead of blocks of ashlar. The jetties have ashlar facings or revetments. The blocks of con- crete at Dover were composed of — 1 vol. Portland cement, 2 " Coarse shingle. 2 " Fine " 2 " Sand, 4 " Spalls of the Island stone, Mixed together in a box which revolves eccentrically. The concrete blocks were made in moulds, in which they were allow- ed to harden eight or ten days, and were then subjected to two or three months' exposure, before submersion by the aid of a diving-bell 256 PRACTICAL TREATISE ON LIMES, At Alderney, tlie concrete is composed of — 1 part Portland cement, 2 " Sand. 4 " Shingle, Formed in moulds into which irregular masses of rubble, to the extent of thirty-eight or forty per cent, of the whole, are rammed. Some lime-blocks which were used there were composed of — 2 parts Coarse shingle. 2 " Fine " 1 » Sand, 2 " Spalls of the Island stone. 1 part pound Aberthaw lime. The cement blocks are tested by lifting them four days after they are made, and the lime-blocks eight days after. At these ages respectively they were required to sustain their own weight. For handling the blocks, two pieces of stone around which the concrete is rammed, are introduced into each. These stones act as a dovetail, being broader at the bottom than at the top, and have lewis holes in them. The cement blocks were required to be two months old, and the lime-blocks four months in summer and six in winter, before they were placed in the works. Two cubic yards of cement-concrete required five and a half bushels of dry cement, and the same quantity of the lime-con- crete required six and one-eighth cwt. of blue Lias or Aber- thaw lime. 500. In the United States concrete has for many years been very extensively employed in the construction of the civil and military public works of the country, and recently in the foun- dations and even the exterior and partition walls of private residences and factories. HYDRAULIC CEMENTS, AND MOETARS. 257 501. TABLE XX. SHOWING THE COST OF VARIOUS KINDS OP MASONRY PER CUBIC YARD, AND THE VOLUMES OF MORTAR REQUIRED FOR EACH. ■is « 3 g 9 ween ment ison- rtar. Cost per cubic 1 lira 10 CG o W G 1- fl 2 i u u u 1,258 1,242 1,284 1,398 End of brick broke off. J Continuous fracture in the 1 brick. End of brick broke off. 10 Kingston & Eosendale. (( u 1,227 Fig. d. 11 u u u 969 End of brick broke off. 12* u 836 Fig. e. 18* 14 u M M U U '"'^ 1,284 1,055 End of brick broke off. Sancoclc, Maryland... M U 648 Fig./ 16 u W »• 777 End of brick broke off. 17 M M » 1,023 Fig. g. 18 tt U 617 Fig. h. 19 Newark & Eosendale.. W H 1,213 End of brick broke off. 20* James Kiver l( U 859 Fig. i. > «^ ^ i 21 Delafield & Baxter .... Cement in powder 8, siftings 1 . 1,278 Brick broke off. 22 Fig.^-. u Cement in powder 4, siftings 1 . 979 Fig. b. HYDRAULIC CEMENTS AND MOETARS. 275 Kind of cement Composition of mortar. The meaaurements are by volume. Breaki'g weight by force of trac tion, in Kemarks. Delafield & Baxter. Cement in powder 4, siftings 1 Cement in powder 2, siftings 1 , M U Cement in powder 1, Biftings 1 , 843 1,182 1,211 1,310 1,246 1,180 1,043 Cement in powder 1, siftings 2. Cement in powder 4, sand 1 812 570 1,192 1,096 974 1.055 Fig.Z. End of brick broke off. I Broke out a continuous < piece in the brick avcr- ( aging i to i in. tliick. Fig. m. End of brick broke off. Fig. n, Fig.o. Fig. p. Fig. q. Fig. r. j Continuous sep;irauon ( from the brick. Brick broke off. Fig. «. Fig. t. Fig. u. 276 PRACTICAL TREATISE ON LIMES, Kind of cement. 41 42 47 48* M 661 DelafieldA Baxter., Composition of mortar. The measurementa are by yoIam«. Cement in powder 4, sand 1 . Cement in powder 2, sand 1. . Cement in powder 1, sand 1. . . Cement in powder 1, sand 2 Breaking weight by force of trac- tion, in 1,420 1,023 1,113 1,070 420 732 812 523 367 260 491 Eemarks. Fig. V. Brick broke off, J Continuous splitting \ through the mortar. Fig. w. Fig, X. Fig, y. 0 a Continuous splittuuc through the m( rt xi Fig, z. Fig A. Continuous splitting through the mo ar. FigB. Fig. C ( Continuous separation < from brick. SampL ( probably defective. Fig D. Fig. F. HYDEAULIC CEMEOTS, AND MOETAES. 277 Kind of cement Composition of mortar. The measurementB are by volume. Breaking by lore of trac tion, ii lbs. Remarks. S6 5T* 68 63* 64* 65 James Eiver. Cement in powder 8, sand 1. . . , ( Nfiwark Lime and \ Cement Mfg. Co. Cement in powder 4, sand 1. Cement in powder 1, sand 1. Cement in powder 1, sand 2. Stiff paste of pure cement. Cement in powder 1, sand 1. . . 67 68* Cement in powder 1, sand 2. . . 978 812 Fig. F. Fig G. Fig. H. 740 392 1001 1,492 Continuous separation from the brick. Brick broke oflF. ?. I. Fig. J. defective. 1,451 913 Fig. K. Fig. L. Fig M. 1,036 Continuous splitting througb the mortar. Fig. N. Fig.O. 278 PEAOTICAL TREATISE ON LIMES, 71 Kind of cement Newark Lime and Cement Mfg. Co. Composition of mortar. The measurements are by volume. Breaking weight by force of trac- tion, in Cement in powder 1, sand 2. . . Eemarka. Fig. P. Fig. Q. ( Continuous separation 1 from tlie brick. 535. The positive deductions from tfie foregoing table appear to be as follows : 1st. That particles of unground cement exceeding -^q inch in diameter may be allowed in cement paste without sand to the extent of fifty per cent, of the whole, without detriment to its adhesive or cohesive properties, while a cor- responding proportion of sand injures the strength of the mortars in these respects about forty per cent, 2d. That when these unground particles exist in the cement paste to the extent of sixty-six per cent, of the whole, the adhesive strength is diminished about twenty-eight per cent. For a corresponding proportion of sand, the diminu- tion is sixty-eight per cent. 3d. The addition of these siftings exercises a less injurious effect upon the cohesive than upon the adhesive property of cement. The converse is true when sand, instead of siftings, is used. 4th. In all the mixtures with siftings, even when the latter amounted to sixty-six per cent, of the whole, the cohesive strength of the mortars exceeded its adhesion to the bricks. The same results appear to exist when the siftings are replaced by sand, until the volume of the latter exceeds twenty per cent, of the whole, after which the adhesion exceeds the cohesion. 6th. At the age of 320 days (and perhaps considerably within that period), the cohesive strength of pure cement mortar exceeds that of Crotoif front bricks. The converse is true when the mortar contains fifty per cent, or more of sand. 6th. "When cement is to be used without sand, as may be the case when grouting is resorted to, or when old walls are to be repaired by injections of thin paste, there is no advantage in having it ground to an impalpable powder. 536. The ingenious device mentioned below, for laying stone- ^ ^ . masonry in cement-mortar under water, was Btone under water suggested to me by Major B. S. Alexander, HYDRAULIC CEMENTS, AND MOETARS. 279 Corps of Engineers, and was, I believe, practised by that officer in the construction of the Minot's Ledge Light-House, Boston harbor. It consists in protecting the mortar from the dissolv- ing action of the water during the descent of the stone to its bed, by an envelope of muslin sufficiently loose in texture to allow the mortar to ooze through between the fibres, and thus form a bond with the stone previously laid. The idea is an- alogous to that followed by some Italian engineers in repair- ing and protecting submarine masonry by concrete, rammed into position in bags of loose, open texture. It may be ap- plied in the following manner, viz. : a piece of muslin of suitable quality, and somewhat larger than the bed of the stone to be laid, is first spread out on a horizontal surface and cov- ered with a coat of mortar of the thickness desired in the work, and of an area somewhat exceeding that of the bed of the stone. On this mortar the stone is then carefully placed and allowed to remain there until the mortar begins to stiffen a little, the margin of the cloth exterior to the stone having been folded up against the sides of the latter, and secured there by cords leading over the top. The stone is then lowered to its position on the wall, rammed into place, and not again dis- turbed. 537. Some trials made with a view to test the efficacy of this method of construction, although giving discrepant results, show, that if applied with Jbt^f^S^.^. care, it may be made to subserve a good pur- pose. Bricks were cemented together in pairs, as shown in the table last given. Some of them had cement paste only between them, others had a single layer of muslin next to one of the bricks, and others had muslin in the centre of the mortar joint. Other trials were made with prisms, 2"x2" in cross section, with a layer of muslin extended transversely across and through the prism, midway between the supports on which the prisms were broken. 538. Cement jpaste without sand was used in all cases, and 280 PEACTICAL TREATISE ON LIMES, the samples were ninetj-six days old when broken. Water was applied to them with a sponp-e two or three Same continued. . i i . i times a week, durmg the entire period. All the bricks were cemented while thoroughly wet. Table XXXIII. contains the results. The numbers 15, 16, IT, and 18 were dipped in sea-water just before being cemented. 539. TABLE XXXIII. Showing the adhesive and cohesive strength which mortars of pure cement paste can attain, through a layer of com- o ?5 Mode of trial. to a ua oj.a j Eemarks. Two wet bricks cemented together, without muslin. : t ■ I with wet muslin in ' the middle of the joint. with muslin soaked I in crean of cement > next to one of them ) muslin soaked in cream of cement, and bricks dipped in sea-water. 572 279 884 939 908 572 82 94 106 978 709 1153 572 719 1153 197 872 185 Fig. K. j Continuous separation \ from brick. Fig. S. Fig. T. End of brick broke off. J Continuous separation 1 from brick. Separated along the muslin. End of brick broke off. Separated along the muslin. End of brick broke off. Separated along the muslin. Continuous separation from brick. HYDEAULIC CEMENTS, AND MOETAES. 281 mon thin muslin. The mortar set under a pres- . Same continued, sure of thirty-eiglit pounds per square inch, or about 500 pounds on the pair of bricks. Age of mortar, ninety-six days. 540. OBSERVATIONS ON THE FOREGOING TABLE. 1 . The average resistance, where there is a continuous separation from the muslin, is 507 pounds. 2. The average resistance, where there is a continuous separation from the brick, and no mushn was used, is 425 pounds. 3. The average resistance, where there is a continuous separation from the brick, and mushn was used, is 446 pounds. 4. The average resistance of all the cases where muslin was used, is 568 pounds. 6. The average resistance of all the cases where muslin was not used, is 692 pounds. 6. The case of muslin soaked in cream of cement next to one of tlie bricks, gave the best average result, viz.: 826 pounds; the next best being when the bricks are put together without muslin, which gave an average of 632 pounds. 1. The three greatest resistances in the above table were obtained when muslin was used. In two of these (Nos. 10 and 12), the end of one brick broke off; in the third, (No. 15,) the separation took place continuously along the muslin. 8. The worst results, when musHn was used, were obtained when the latter was placed in the centre of joint, and not in contact with either brick, the differ- ence being very considerable, as an inspection of the table will show. The muslin used in these trials was much thicker than would be necessary in practice. 541. TABLE XXXIY. other trials with muslin. Showing the strength of rectangidar jprisim x 2" in cross-section, some of them having a hiyer of muslin transversely across the prisms, midway between the sup- ports, and some having none. The prisms were ninety-six days old, of pure cement paste, the supports four inches apart. The pressure was applied in the middle. Nature of test Piece of muslin transversely across the prism No muslin was used C CO 113 103 353 337 322 304 Bemarks. Broke along the muslin. 282 PRACTICAL TREATISE OJ^ LIMES, 542. OBSERVATIONS ON THE FOREGOING TABLE. 1. The average breaking weight of the prisms containing muslin, is 107 pounds; and of those containing no mushn, 329 pounds. 2. The 8th observation of Table XXXIII. is corroborated, viz. : that the most dis- advantageous place for the muslin is in the body of the mortar. 3. With thin raushu of loose texture, both the adhesion and cohesion through the muslin would undoubtedly b§ much greater than the foregoing Tables (XXXIII. and XXXIV.) indicate. The effect of the sand on the ad- hesive properties of mortars. 543. TABLE XXXY. Showing the adhesion to Croton front hrielcs and fine cut granite^ of mortars containing dif- ferent proportions of sand. The mortar was of the consistency ordinarily used for brick masonry, and the bricks were nsed wet, and were pressed well too:ether by hand. They were wetted with fresh water every alternate day for 29 days, the age of the mortar when tested. Each re- sult is the average of five trials. The right-hand column shows the ratio of the adhesive strength of the several mortars, assum- ing that of pure cement to be 1. Composition of the mortar. Materials cemented. IS 9 « 5; o rt O o ^ 1 .2 S M 421 30.f 1 215 15.7 -No 169 12.3 94 6.h 71 5.2 59 4.3 45 3.3 .1 1. 1 00 4401 332| 27.5 20.b' 1 201 12.C -1%%- 146| 9.2 127 7.P Pure cement paste 1 vol. cement powder, 1 vol. sand 1 " " " 2 " 1^ <( (( (( 2 « (( U (( ^ u I " " 5 " Pure cement paste 1 vol. cement powder, 1 vol. sand 1 " " 2 II (< (( 2 u Croton bricks. Fine cut granite, 544. The adhesion of mortars to stone or bricks varies con- siderably among the different kinds of these materials, and par- ticularly with their porosity. With the same material, it varies with the consistency of the mortar, and the quantity of sand which it contains. HYDEAULIC CEMENTS, AND MOETAKS. 283 645. TABLE XXXYI. Showing the adhesion to very fine cut granite of pure ce- ment made by the I^ewark & Kosendale Co., mixed with different proportions of water. The blocks measured 4" x 8" on the face, and were cemented together in pairs, face to face, at right angles to each other, and kept in fresh water. The stones were pressed together by hand, as in laying bricks, and were pulled apart at the expiration of 96 days by the device, shown in Fig. 5. o a Composition of the mortar. 1 vol. loose, dry cement, and \ vol. water. Consistency of cream (( (( u l( C( 1.1. (I II u 1 vol. loose, dry cement, and -iij. vol. water. Consistency of very thick creain U (I (I u u » II (( (I » » K (I » C( !.<. U K » 1 vol. loose, dry cement, and -^^^ vol. water. Consistency of ordinary mortar. 2.4 O) o |?U0ilbs. 314 J 6111 .584 i 3^1^ u 591 r '4 599 J 454] 490 449 472 546. For the sake of economy, it is customary to add lime to cement mortars, and this may be done, to a considerable extent, when in positions sake^oT economy where hydraulic activity and strength are not re- quired in an eminent degree. The following table contains the results of trials with cement paste and mixtures of cement and lime paste, without sand. The cement was the dark Kosendale of excellent quality. 54:7. TABLE XXXYIl. Showing the ultimate strength of rectangular parallelopijyeds X 2" X 8'') of cement paste, and mixtures of cement and lime paste without sand, formed in vertical moulds, under a pres- sure of 32 lbs, per superficial inch, and broken when 95 days 284 PRACTICAL TREATISE OK LIMES, old, on supports 4 inches apart, by a force applied at the middle. The mortars were kept in sea-water from the time they were one day old. Composition of the cement Pure cement paste. (Average of two trials.) 1,1 il It (I Cement paste, 1 vol. Lime paste, i vol ivol. 1vol. ivol. ivol. 1 vol. Penetration of the point in inches. 1 impact. 2 impacts. ^ S tS .114 .112 .117 .lOT .155 .160 .147 .155 .155 .150 .159 .121 .200 .180 .187 .iso .207 .210 .180 .200 .180 .180 .200 .220 .230 .270 3 S .195 .163 .192 .187 .250 .250 .243 .250 .265 .200 .195 .200 .300 .220 .395 .295 .325 .330 .300 .320 .293 .290 .300 .340 .260 .380 994 957 ,025 ,034 ,0!)0 996 992 931 S63 847 1S5 769 597 570 513 I 582 J 597^ 574 1 558 f 550 J 3f.5~l 363 ! 355 375 339 316 286 280 l,002i lbs. 9793 816 565* 5693. 364t 305^ 548. Othe?' mortars of light colored E-osendale cements and lime, mixed, formed into blocks of the same size, preserved and broken in precisely the same manner as the foregoing, gave the following results when 95 days old. The average of four trials is given in each case. TABLE XXXVIII. No. of the mortar. Composition of the mortar. Breakino; weight, in lbs. 1 Cement pas 738 2 u 1 " " i " 3 u 732 4 'it ]^ u "1 " 608 Effect of lime on the strength of cement mortar. 549. Observations on Tables XXX YII, and XXX F//Z— 1st. We infer from the last ta- bles (XXXVTI. and XXXYIIL), that the dark HYDEAULIC CEMENTS, AND MORTARS. 285 colored Eosendale cements are less able to sustain a large dose of lime than those that are light colored, and that the latter suffer no serious deterioration of strength until the amount of lime paste exceeds the amount of cement paste. It does not necessarily follow that the ingredients which confer color on the cement are the cause, either immediate or remote, of this difference. The light colored Rosendale ce- ments are confined to one locality, that of High Falls, and it may be that local causes, operated at the period of, or subse- quent to their deposition, which so modified or changed the molecular or chemical condition of some of the ingredients, as to cause this variation, and at the same time be beyond the reach of ordinary analytical research. 550. 2d. In Tables XXXYII. and XXXYIII., no record is made of the effects which the addition of lime has on the hy- draulic activity of the cement. In regard to Effect of lime on this point, however, numerous trials show that Jf^^ty^ol-'cem^^ a gang composed of equal proportions of the mortars, pastes of Rosendale cement and lime is sufficiently quick set- ting for all purposes, except when immediate submersion is required ; and possesses, besides, the positive advantage over pure cement of coming to the hands of the masons in a better working condition, and is not liable to have its incipient set constantly disturbed on the mortar board, and its ultimate strength thereby impaired by remixing. There is a remarka- ble difference in the capacity of cements to withstand this degrading treatment. The extent to which they are affected by it seems to vary directly with their hydraulic activity Thus, the Rosendale cements, which require 25 to 30 minutes to set at 65° F., will bear reworking much better than those James and Potomac River cements, which harden in five or six minutes. We would expect that the extent of the disturbance of the crystallization would be in direct proportion to the hy draulic activity. 651. The me of alkaline silicates {soluble glass) as a means 286 PEACTICAL TEEATISE Olf LIMES, of conferring hydraulic energy upon fat lime has been reverted to in foregoing portions of this work. Experiments uniformly indicate that its efficiency for such purposes, has been overrated. It may, and probably can be advantageously applied to the reclamation of the intermediate limes, (those in which the hy- draulic energy is exerted powerfully and rapidly when first mixed, but which soon yield and fall down under the action of the sluggish free lime present) ; but for fat limes, they appear so unsuitable, that even the statements of M. Kuhlmann him- self are insufficient to authorize their use. When added to the intermediate limes, they appear to exert their influence by giv- ing up their silica to the free lime present, thus neutralizing or perhaps only retarding its action, until the hydraulic principle has time to exert its indurating power. 552. Presuming, under ordinary circumstances, that the ad- dition of soluble glass to a paste of fat lime not only conferred hydraulicity, but augmented the strength of the Effect of soluble ' , j. • i i - i • . i glass on the mortars, some trials were undertaken with the strength of mor- double silicate of potash and soda, in order to test its relative value when thus employed, as compared with hydraulic cement itself. The specific gravity of the soluble glass used was 39° Beaume, at O^'' F. Prisms of the usual size were made and kept in the air ninety-five days, when they were broken in the usual manner, on supports four inches apart. In the following table, the breaking weights are given in the right hand column. The first and second samples were formed under a pressure of 32 pounds per square inch, the others without pressure. The adhesion to bricks cemented together transversely is as follows : rormona.of|«««^;J[ 9,,} lbs. ( limepaste •< sand ( soluble glass .125 ( limepaste 1.0 ) For mortar of i sand 3.0 1 51 1 lbs. HYDBAULIC CEMENTS, AND MORTARS. TABLE XXXIX. 287 o is 3 4 5 6 1 8 9 10 11 12 Composition of the mortar, in volumes. Lime paste, 1.0, sand, 2.0, soluble glass, .11. . 1.0, " 2.0, " " .11.. " 1.0, " 2.0 " 1.0, " 2.0 " 1.0, " 3.0 " 1.0, " 3.0, soluble glass, .08. . " 1.0, " 3.0, " " .10.. 1.0, " 3.0, " .125. " 1.0, " 3.0, cement paste .50. . " 1.0, " 3.0, " " .33.. " 1.0, " 3.0, " " .25.. " 1.0, " 3.0, " " .166. — =2 .9 40 54 in 67f 65 24i 23 18 1821 166f 92 94| It injures the strength and ad- hesive properties of mortars. 553. From the foregoing results, which are the averages of many trials, it may be inferred that the double alkaline silicate, while it renders common mortar hydraulic, injures its strength and its adhesive properties, and is greatly inferior to cement as a hydraulic agent, in both efficiency and economy, irrespective of the degree of energy required. At the same time, it is con- ceded that in many cases, particularly for hardening soft and porous stones and concrete walls or stucco work, after these are well dried, it is of value when judiciously applied. Its use has, however, been attended with many failures, even in France, where the subject has received much attention, and we are yet without an easy and entirely practicable method of manipula- tion, that can safely be intrusted to the hands of ordinary me- chanics. Silicate of soda should be employed rarely if at all. 554. The experiments undertaken to ascertain the law of progressive increase in the strene::th and hard- , ^ ^ ° Increase of ness of mortars of American cements do not ex- strength and hard- tend over a very large period of time. The re- sults obtained, however, afford the means of a very fair com- parison between the strength of these mortars and some placed on trial at Toulon, with a view to determine the combinations 288 PRACTICAL TREATISE OJST LIMES, to be used in the construction of the dock in that harbor^ under the superintendence of M. Noel, Engineer-in- chief of Roads and Bridges. The trials at Toulon were made during the years 1840 to 1844:, upon rectangular prisms 1.57 inches wide by .984 inches deep ; they were broken on supports 2.36 inches apart, by a pressure at the middle. A comparison of the results obtained in the two cases has been made by using the formulas : (1 .) W^l E ^ - - 1 (2.) W'= f R ^' In the general formula (1) W represents the weight which the prism bears at the moment of rupture ; J, the breadth, and d, the depth of the prism ; Z, the distance between the supports, and a, the weight of that portion of the prism represented by 1. The value of R, the co-efficient of rupture, having been ob- tained from the above equation from M. I^oel's prisms, by substituting for W, h, d, Z, and their known values as reported we readily obtained the value W for M. Noel's mortar wheD the prisms are supposed to be two inches square in cross sec- tion, and broken on supports four inches apart, like the Amer- ican mortars, by substituting in equation (2) the deduced value of R, and the value of h', d', l\ and a\ corresponding to the American prisms. 555. The results of the computations above mentioned, which are the resistances to rupture of rectangular prisms 2"x 2" in cross section, resting on supports four inches apart, are given in Fig. 56, by curves constructed with abscissas, which represent the resistances or breaking weights, laid down, to a scale of yV of an inch to 20 pounds, and with ordinates, which represent the age of the mortars to a scale of of an inch to twenty-five days. The mortars were kept in salt water imtil broken. The proportions of cement, lime, and sand are given by vol- ume in all cases. HYDKAULIC CEMENTS, AND MOETARS. 289 Jos. 1250 1 1 fl?o MOO J050 j 1820 j [ m . 350 - -j BOO // — 750 " / \ ! 2 700 ^ — ; esp - / i fiOP f\ 1 — 550 - / / — ^. / 5^ ■-1 -g- - / 1 / ^1 -T / ^ — • - — ^_ s- . 400 n -] \U } / y ^ 300 4 r / / / -j 1 / ft" 150 I i H T~ m] 1 fo j ff«cri.20 60 n 0 200 300 ^00 600 600 700 fiOO ^ 000 19 Fig. 55. 290 PRACTICAL TREATISE ON LIMES, No. 1. Mortar composed of two parts Roman pozzuolana and 1.50 parts Theil hydraulic lime. No. 2. Mortar composed of two parts Roman pozzuolana and 1 part ordinary lime. No. 3. Mortar composed of two parts Roman pozzuolana and 1 part Theil hy- . draulic lime. No. 4. Mortar composed of two parts sea-sand and 1 part Theil hydraulic lime. No. 5. Mortar composed of one part Roman pozzuolana, one part Theil hydraulic lime, and one part sea- sand. No. 6. Mortar composed of one part Roman pozzuolana, one part ordinary lime, and one part sea-sand. No. 1. Mortar composed of one part Rosendale and Kingston cement and one part sand. No. 8. Mortar composed of one part Ogden's Rosendale cement, and one part sand. No. 9. Mortar composed of one part Hudson River cement, and one part sand. No. 10. Mortar composed of one part Lawrence ville Cement Manufacturing Co., and one part sand. 556. Of the four American cements represented in Fig. 56, Nos. 7, 9, and 10 are what are known as " dark" colored, and take the initial set, so as to support the ,V inch wire, loaded to J of a pound, in from twenty-five to thirty minutes, at a tempera- ture of 65° F. ^^J'o. 8 is a " light" cement, manufactured from Layer "No. 16 at High Falls, (see paragraph 55). It sets very rapidly, (in from five to eight minutes,) when first mixed, provided the paste is not mixed too long, and is left entirely undisturbed ; but if the manipulating process continues beyond the time when the in- duration properly begins, the continual breaking up of the in- cipient set destroys the energy very much. It is far more sensitive in this particular than the slower acting cements, 7, 9, and 10. It may be further remarked that of the three American cements whose trial extended through the period of one year, the two slower setting " dark" colored varieties are inferior in strength to the other which is " light" colored and quick, until all attained the age of about three hundred days, when this condition of things is reversed. From this point onwards, the former increase in strength very rapidly, and the latter quite moderately. At four hundred days, the "light" ce- HYDRAULIC CEMENTS, AND MORTARS. 291 ment is no stronger than a mortar of 1^ parts Theil hydraulic lime and 2 parts of Koman pozzuolana, (curve 1). 557. TABLE XL. Showing the strength of mortars of various cements made into prisms 2" X 2" X 8" in vertical moulds, un- ^ ^ ^ ^ . Strength of mor- der a pressure of 32 pounds per square inch, tars of sundry and broken on supports four inches apart, by a pressure midway between the supports. The prisms were kept in sea-water after the first 24 hours, and were 320 days old when broken. The breaking weights given are averaged from many trials. The cement was measured in powder. Breaking weights of mor tars composed of Kind of cement used. Pure ce- ment. Cement, vol. 1, Sand, vol. 1. Cement, vol. 1, Sand, vol. 2. English Portland (artificial) Cumberland, Md Newark and Rosendale Delafield and Baxter (Rosendale) "Hoffman" Rosendale "Lawrence" Rosendale Round Top, Md TJtica, 111 Shepherdstown, Va Akron, N. Y Kingston and Rosendale Sandusky, Ohio James River, Va * Roman cement, Scotland The following were broken when one year old: Lawrenceville Manuf. Co. (Rosendale) Sandusky, Ohio Kensington, Ct Lawrence Cem't Co. (Rosendale) "Hoffman" Brand. Round Top, Md lbs. 1,536 954 841 836 849 m 732 V47 764 720 554 553 802 954 875 lbs. 1.260 920 560 692 607 600 756 618 651 556 464 623 910 709 911 840 lbs. 950 558 500 532 562 450 603 500 638 380 506 * This cement appeared to be inferior in hydraulic energy to Roman cement generally, and had probably been injured by age and exposure. 558. From General Treussart''s experiments with mortars of fat lime and trass, or pozzuolana, it may be in- Q^n. Treussart's ferred that these two substances possess very experiments. 292 PRACTICAL TREATISE 01^ LIMES, nearly equal merit, as agents for conferring strength and hy- draulic energy on common mortar. He says pozzuolana gave rather the better results with the same kind of lime ; although " in general there was little difierence between the trass and the pozzuolana used." The results given in the following table were obtained by that engineer, and are introduced liere as affording a just medium of comparison between such mortars, and those of the same age (one year) recorded in the table last given. (Table XL.) 559. TABLE XLI. Breaking weights of jpozzuolana and trass mortars^ one year old, formed into prisms 2" X 2" X 6", and resting on supports four inches apart. The lime was slaked to powder and meas- ured in that condition. The prisms had been kept in water. 'SI Coinpoaition of the mortar. 5 S-^ Strasburg lime, 1 vol., sand, 1 vol., trass, 1 vol Strasburg lime, 1 vol trass, 2 vol Strasburg limo, 1 vol., sand, 1 vol., pozzuolana, 1 vol. Straeburg lime, 1 vol por^uolana, 2 vol. Vasselone lime, 1 vol., sand, 1 vol., trass, 1 vol Yaasolone lime, 1 vol tra^s, 3 vol Brunstat limo, 1 vol., sand, 1 vol., trass, 1 vol...... BVunstat limo, 1 vol trass, 2 vol White mai'ble lime, 1 vol., sand, 1 vol., trass, 1 vol White marble lime, 1 vol trass, 2 vol White marble lime, 1 vol., sand, 1 vol., pozzuolana, 1 vol. White marble lime, 1 vol pozzuolana, 2 vol. Strasburg lime, 1 vol pozzuolana, 2 vol. Strasburg lime (paste), 1 vol pozzuolana, 2^ vol Strasburg lime (paste), 1 vol trass, 2 vol 4 4 5 4 5 4 5 4 4 3 4 5 to 16 lbs. 4L1 330 499 444 449 385 510 535 308 407 396 367 495 550 231 to 580 560. Experiments seem to prove that fat liine shiked to Lime with trass powder will give better mortars with trass and mortars. sand, or with trass alone, if left exposed to the air for a month or more after slaking, than if made into mortar when perfectly fresh ; and also that a mortar composed of one volume of lime powder and two volumes of trass, is injured if HTBEAULIC CEMENTS, AND MOETAES. 298 a portion of the trass be replaced by sand. General Treussart also found that air slaked lime did not give as good results as lime slaked to powder with water. CHAPTER IX. 561. White alkaline effloresences upon the surface of brick walls laid up in mortar, of which natural hy- T T . , T . > , Effloresencos on draulic hme or cement is the basis, irequently brick walls laid in produce a most unsightly appearance, and offer mortor. a grave objection to the use of cement for masonry exposed to view, or where it is desired to preserve any agreeable shade or tint, or retain the natural color of the brick employed. 562. On stone, these effloresences never at- tain a formidable aspect, and with the denser ^^^f formidable ^ ' on stone walls, varieties are almost imperceptible, being confin- ed exclusively to the pointing of the joints; but on brick work, they not unfrequently spread themselves over the entire surface of the wall. 563. A more serious objection than any due to appearance simply, is furnished by the fact J^nJation™ that the crystallization of these salts within the pores of the bricks, into which they have been absorbed from the mortar, is certain to cause disintegration. Even stone, particularly the most porous varieties, is not exempt from the effects of this destructive agent, which acts, especially the soda salts, in many respects like frost. 564. The exudation of those alkaline solu- tions, which, in crystallizing, produce deleterious Ttmosphere. salts, appears to be favored by a humid state of the atmosphere, and is, therefore, more prominently developed on the sea-shore than in localities more inland. 565. At Newport, R. /., pints of it may at From Fort Adama any time be collected from the walls of Fort Adams. Being almost entirely soluble in water, it is removed 294 PEACTICAL TKEATISE ON LIMES, by rain from all localities exposed to the direct action of this element, to be reabsorbed, in a great measure, before the aque- ous solution has time to run off. 566. A portion of this Fort Adams' efflorescence takes the Analysis of Fort ^^^^^ ^^^^ ^^^^^ needles, frequently pro- Adtims' efflores- jecting more than one inch from the face of the OGUCG. wall. Other portions present the appearance of fine snow. When collected in a mass, it closely resembles Epsom salts in appearance, and is not unlike it in taste. Its composition, as determined by analysis, is reported by Profes- sor Boynton, of the University of Mississippi to be as follows : Carbonic acid 19.90 "Water expelled at a low red heat 52.30 Lime 04 Soda 2'7.96 Sulphuric acid 10 lesia , 06 • 100.36 567. Another sample of efflorescence from the ruins of an embrasure tara^et erected at West Point in the w^K. -. T . , . From West Point year 18o4, subjected to qualitative analysis, gave carbonate of potash as the principal ingredient. Its ap- pearance upon the surface of the bricks, resembled that of a thin, rough coating of white sugar. It was readily removed as a powder by scraping. 568. M. Kuhlmann^ of Lille ^ France, who gave his attention to this subject many years ago, and who has fxpfriei^e^'''''^ from time to time published his investigations, without proposing any efficient remedy for the evils complained of, notices some efflorescences of a much more complicated composition than those from Fort Adams. Pro- fessor Kuhlmann found, that although efflorescences of nitrate of potash (saltpetre), or ammonia, were of no rare occurrence, those of carbonate and sulphate of soda were much more com- mon, and that many stone and brick walls, laid up in hydraulic HYDEAULIO CEMENTS, AND MORTARS. 295 mortar within periods quite recent, were covered with exuda- tions of caustic and carbonated potash, containing chlorides of potassium and of sodium. 569. One source of these salts of soda and potash is, beyond doubt, the hydraulic lime or cement used in the mortar; derived partly from the stone itself and potlh!"^ and partly from the ashes of the fuel used in calcination, when the burning takes place in ordinary draw kilns. About 35 lbs. of anthracite coal are required to calcine 1 bbl. (300 lbs.) of cement, and no precaution whatever is taken to separate the coal ashes. From the same cause, the cement also becomes adulterated with fine particles of unconsumed coal, amounting sometimes to three or four per cent, of the whole. When the cement is coarsely ground, these particles are plainly visible, but in the condition of impalpable powder, they are lost to the naked eye. 570. Proximity to the sea, where the atmosphere is a con- stant source, will account for the preponderance proximity to the of carbonate of soda in the walls of Fort Adams, sea favors efflo- as well as for the exceedingly large volume of efflorescence. It seems improbable that the mortar could be the origin of so much alkali. 571. Three plausible methods of obviating the appearance of these salts suggest themselves : First, to add some chemical re-aqent that will Remedies. permanently fix them within the body of the mortar by converting them into insoluble compounds. Second^ to render them deliquescent either before, or after they form those compounds that effloresce. Third^ to saponify them by adding some oily substance. 672. Under the^r^i^ method^ potash can be managed very well. Hydrofluosilicic acid converts it into a well-known insoluble compound, while the action upon the soda, if present, is not disadvantageous. Potash, however, is harmless in its effects, compared with soda. The sulphate of soda, likely to be formed 296 PRACTICAL TREATISE ON LIMES, in the vicinity of large cities, from the absorption of the snl phuric acid gas, acts like frost in crystallizing. 573. The second method does not seem to give promise of success. 574. The third method^ on the contrary, does promise success, and our trials under it have been numerous. "We have found it convenient to make common lime the vehicle for conveying the fatty substance to the cement, and here take occasion again to call attention to the fact that lime paste may be added to a cement paste in much larger quantities than is usually prac- tised in important works, without any considerable loss of ten- sile strength or hardness. There is no material diminution of strength until the volume of lime paste becomes nearly equal to that of the cement paste (see Tables XXX YII. and XXXYIII.), and it may be used within that limit without apprehension, under the most unfavorable circumstances in which mortars can be placed. 575. To secure a complete dissemination of the fatty matter, it should be mixed up with the caustic lime, so connection^^ other phenomena developed in slaking will complete the incorporation. Its amount will depend upon the proportion between the cement and lime pastes in the mortar, and may vary between 5 and 10 per cent, of the weight of the quicklime, when the latter is employed simply as a vehicle. 576. In examining and judging results, in duc\^4tLTiais. ^^^^^ ^^^i^ apprehended from the minute quantity of alkali generally present in cement, and from the apparently precarious law which seems to control its appearance in the efflorescent state, the amount of alkali was,, in many cases, greatly increased, (some- times several hundred per cent.,) by adding to it from a solu- tion of the salts taken from Fort Adams. This solution was mixed with the water used for making the mortar. With the mortar thus prepared, bricks were cemented together and laid HTDEAULIC CEMEOTS, AND MORTAES. 29? away in pairs, some of tliem being moistened occasionally, and others left dry. Cakes of the mortar not in contact with brick were also preserved. In all cases where there was any considerable excess of the alkaline ingredients, a plentiful crop of crystals appeared on the surface within a day or two after the mortar wag prepared. "No additional efflorescence took place after these vr ere removed. In no case was there any efflorescence from mortar containing the fatty substance, but to which no saline ingredients had been added. It is believed that the proportion of the several ingredients in practice should be from 8 to 12 pounds of the fatty substance to 100 pounds of quicklime, and 300 pounds of cement powder. The cheapest kinds of animal fatty matter will answer. 577. It would not be safe to pronounce at once in favor of this method of remedying the evils of efflorescence. It certainly appears to give promise of success. USTDURATIOK OF MORTARS OF FAT LIME. 578. We have indicated, paragraph 331, that the hardening of fat lime mortars could be partially attributed to the absorp- tion of carbonic acid gas, producing carbonate of lime (CaO. CO 2). The lime absorbs only about one-half the quantity of car- bonic acid (CO2), necessary to convert the whole into carbonate of lime ; or, in other words, only ^^^Sfacid!^ about one-half of the lime becomes thus con- verted, the formula for the hydrate present being CaO.COjX CaO.H. But the hardening of the fat lime mortars cannot be entirely attributed to the formation of carbonate of lime. For we know that mortar, in the centre of thick walls, which never becomes carbonated, nevertheless possesses a fair degree of adhesiveness and hardness. Some mortars, 300 years old, examined in Dresden by Petzholdt, yielded a strong lime water when digested in fresh water, and must therefore have con- 298 PRACTICAL TEEATISE ON LIMES, tained caustic lime. Another portion of the same mortar effer- vesced freely with cold dilute muriatic acid, and after a few minutes yielded a stiff jelly, proving the previous combination of lime and silica. Analysis of mortars of fat limes and sili- cious sand 100 years old, and of the limes which furnished them were also made. 579. From the experiments of Petzholdt, certain conclusions were drawn : 1st. That there was more soluble silica in the lime mortar than in the original lime. 2d. That there was three times as much soluble silica in the raiortar three hundred years old, as in the mortar one hundred years old, and consequently, 3d. That there must have been a chemical combination be- tween the lime and the silicious sand. 4:th. The presumption is that the silicious compound formed, acted as an indurating agent. But we do not find in these trials a reason Mortars contain- for the induration of mortars containing none ing calcareous i * i i sand only. but calcareous sand. Analyses do not prove a chemical combination between the lime and the raw limestone composing this sand, and we must therefore look to the crystallization of the hydrate of lime during the process of desiccation, for the cause of the hardening in this case. 580. The gang of ordinary lime mortars is a mechanical mixture of a paste of hydrate of lime and Ordinary mortar lime water, and in drying, small crystals a mechanical />i,it i .i i t mixture, 01 soluble lime are deposited on the adja- cent surfaces, and adhere with such force to them, as to increase very materially the strength of the aggre- gates, when the surfaces become closely approximated, as is the case with mortars. In practice, the proportion of sand would be such, that the hydrate will form the thinnest possible stratum between the grains. Mortars containing a deficiency HYDEAULIC CEMENTS, AND MOKTARS. 299 of sand, indurate very slowly. Wherever the soluble lime comes in contact with air, or even with water, carbonic acid is absorbed, and subcarbonates formed, which accounts for the superior hardness of the surface of mortars. When carbonic acid is thus absorbed, its chemical equivalent of water escapes from the hydrate ; hence the dampness of newly-built w^alls, and newly-plastered rooms. To the foregoing causes collec- tively, therefore, to wit : the chemical formation of silicate of lime and carbonate of lime, and the crystallization of the hydrate between and upon the surfaces of the sand, we must ascribe the solidification of common mortars. 581. Mortars of common lime^ suitably compounded, "set," or lose their plasticity in a very few days, and acquire strensjth with such rapidity, that in Setting of mor- , . ^ ^ TO 1 . tars of commcn the erection oi the largest edmces, there is no lime, occasion to w^ait for the mortar to harden. They become sufficiently strong to resist a pow^erful force of compression long before they exhibit any adhesion to the solid materials. Such mortars obtain their maximum strength and hardness only after the lapse of years and even centuries. THEOKY OF HYDRAULIC mDURATION. 582. The ingredients of hydraulic limestones may be sepa- rated by analysis into two distinct classes of substances : 1st. Ordinary carbonates of lime, of mag- j p J.1 -J Inarredients of nesia, and of the oxides. hydraulic lime- 2d. Various silicates, that is, combinations of silica with alumina, lime, magnesia, the alkalies, &c. Not unfrequently, the only ingredient, except those of the first class, is almost pure silica. In burning, the first effect is to expel carbonic acid ; the second, to effect a combination between the lime, magnesia, &c., thus liberated, and a por- burai^^*^°* tion of the silicates or silica, producing com- V 300 PRACTICAL TREATISE ON LIMES, pounds having an excess of base, and therefore easily attacked by acids. In fact, burnt hydraulic lines are generally quite soluble in acids, leaving gelatinous silica. Another portion of the silica remains uncombined until it is brought into contact with lime in the presence of water, when it unites with the lime held in aqueous solution. 583. A lengthy discussion of the reciprocal actions of the several substances entering into the composition Theory of hy- of hydraulic mortars, which take place during draulic induration ^ ^ - ^ •, continued. the burning ot the stone, and the subsequent induration of the mortars, will not be attempted. A brief reference to the parts played by the principal ingre- dients, particularly the lime, magnesia, silica, and alumina, would seem to be required. The hydraulicity of mortars is the result of combinations between these substances, effected or commenced during the calcination, in the production of compounds which become hydrated in the presence of w^ater, and afterwards undergo a species of crystallization, technically termed " setting." The reactions begun by the agency of heat, are therefore continued and perfected by the .agency of water. 584. We will first take a silicious lim.estone for example, capable of producing fair hydraulic lime, as dis- dout nlftot;. tinguished from_ cement, like many of the beds found in the calciferous sand rock, (paragraph 9), containing carbonate of lime in excess, and silica in every stage of subdivision, ordinarily found in fine quartzose sand. If the several ingredients are homogeneously mixed in the raw stone, a proper, that is to say, a complete calcination of this stone results in a combination of all the silica, not in the state of inert sand, with its equivalent of lime. The resulting hy- draulic lime will contain free caustic lime, inert sand, and a silicate of lime, of which the formula in the general case will be SiOs.SCaO. The hydraulic virtue of this variety of lime is derived in a great measure from this silicate. When mixed into a paste with fresh water, the silicate combines with six HYDEAULIC CEMENTS, AND MORTARS. 301 equivalents of that substance, producing the hydrosilicate ol lime (SiOs.CaO+^HO). All our experience and researches go to prove that silica plays a most important part in the solidification of hydraulic limes and cements, and that the de- gree of hardness attained depends on the molecular condition of the silica, and the amount of base which ultimately com- bines with it. In the formation of silicate of lime, the limit of saturation should never be reached, for this requires two equivalents of silicic acid (silica) to three of lime (2Si03.3CaO), and contains .48 of lime and .52 of silica — a compound pos- sessing no hydraulicity at any stage of calcination, and con- taining double the proportion of silica deemed most advan- tageous for mortars. From analyses of mortars of the Theil hydraulic lime, it was discovered that the hydrosilicate con- tained .25 of silica, .47 of lime, and .28 of water. Besides the silicate of lime formed during the calcination, there is another, formed by a transfer of soluble lime to the silica, which, from the heterogeneous character of the stone, does not combine under the influence of heat. 585. If the limestone contains alumina in addition to the sHica, or, in other words, if clay be one of its constituent ele- ments, in proportions suitable for ordinary hy- reactions draulic lime, carbonate of lime still being in when alumina is excess, the reactions which take place during the calcination and the quality of the resulting product will depend on the intensity and duration of the heat. When this is simply sufficient to expel all the carbonic acid, a separate and independent combination of lime with silica and alumina takes place during the burning, producing silicate and aluminate of lime, both of which become hydrated by taking up six equiva- lents of water. The resulting hydrosilicates are represented by the formulas Si03.3CaO+6HO, and A103.3CaO-}-6HO. 302 PRACTICAL TREATISE ON LIME8, Syntlielical experiments appear to indicate that the ahimin- ate is the least stable of these two substances. 586. If loe vary the conditions of calcination in the last Effect of augment- mentioned case, by augmenting the intensity ing intensity and and duration of the heat to that degree neces- duration of heat. . ^ sary to cause partial vitrmcation of some por- lions, but not of all, the product becomes heterogeneous. In those 23ortions burnt the most, the silica, alumina, and lime are combined together by the heat under certain reactions that at present appear to be rather obscure. This is more especially the case, when other substances are present, which may aet as fluxes. MM. Chatoney and Rivot incline to the opinion that the silicates of alumina and of lime are both formed, and that these compounds, in the presence of water, are decomposed, the results being aluminate and silicate of lime, which become hydrated by combining with three equivalents of water. In that case, the formula for these compounds will be Al.Oa.SCa 0-f 3H0 and Si03.3CaO+3HO. The fact that these chemical reactions require for their completion only half as much water as when the heat is less intense during the burning, may be intimately connected with the superior hardness of some of the gangs made from vitrified cement. In those portions least burnt, the aluminate and silicate of lime are separately formed by the action of heat, and these combine directly with 6 HO, as in paragraphs 584 and 585. 587. If we suppose the clay to he in excess in the limestone, as is orenerally the case with marls, a moderate The reactions . ^ . , , , . when the clay is burning, just sumcient to expel the carbonic in excess. acid, causes a separation between the alumina and silica of the clay, the alumina remaining practically^ inert, while the silica combines with the lime, producing SiOs.SCaO. This becomes hydrated by taking up six equivalents of water, producing a hydrated silicate of the same composition as that recorded in paragraphs 584 and 585. A high heat produces rather complicated and obscure reactions on this class of sub- HYDIIAULIC CEMENTS, AKD MOETAES. 303 stances. A partial triple combination of alumina, silica, and lime takes place during the burning, and the compounds thus formed become hydrated under conditions not very tlioroughly understood. 588. The setting of mortars of fat lime and pozzuolana, natu- ral or artificial, is likewise due to the formation of hydrated compounds of lime with silica and fnTpoLuofan^^^ alumina. The lime attacks the silica and alu- mina, freeing them from previous combinations, when such exist, and slowly forms with them SiOa.SCaO, and AI2O3. 3CaO. 589. It has been recommended to allow these mortars to remain mixed for some time, before temperino* . . . To remain mixed them just previous to use, a precaution which some time before rests upon a plausible, and doubtless, a sound *®°^P®"^^'^r theory ; for while the combinations of lime with silica and alumina previously exist in the hydraulic limes and cements, (having been formed during the calcination and are, therefore, in condition to become hydrates at once, in presence of water,) the conditions are quite different with mortars of fat lime and pozzuolana, in which the silica and alumina have to first free themselves from combinations peculiar to, and existing in the pozzuolana before they can form in the wet way those com- pounds, which afterwards become hydrates, and confer hydrau- licity. From this we can comprehend why fat lime should be used in preference to hydraulic lime for pozzuolana mortars, since the compounds formed during the burning of hydraulic lime will have become hydrates, and will have initiated the hydraulic set, before those formed in the wet way between the free caustic lime and the pozzuolana will have completed the preliminary decomposition : and because, for the same reason, if we employ hydraulic lime, it is only the excess of caustic lime in it that combines advantageously with the pozzuolana. The operation in the mortar of two dissimilar powers, one cmii- posmg^ and the other decomposing in character, might operate 304 PRACTICAL TREATISE ON LIMES, disadvantageously. The conditions should be such, that the difierent combinations of the lime with the silica and alumina, no matter how, when, or where formed, should become hy- drated simultaneously. 590. Magnesia plays an im^portant jpart in the setting of . ,. p mortars derived from the ar^iillo-mao^nesian Action 01 magne- ci ?3 sia on the setting limestones, such as those w^hich furnish the of cements. -r» i i mi . im i Kosendale cements. ihe magnesia, like the lime, appears in the form of the carbonate (MgO.COs). During calcination, the carbonic acid (CO2) is driven off, leaving prot- oxide of magnesia (MgO) which comports itself like lime in the presence of silica and alumina, by forming silicate of magne- sia (SiOo.SMgO) and aluminate of magnesia (AlgOg.SMgO). These compounds become hydrated in the presence of water, and are pronounced by both Yicat and Chatoney to furnish gangs which resist the dissolving action of sea-water better than the silicate and aluminate of lime. This statement is doubtless correct, for we know that all of those compounds, whether in air or water, absorb carbonic acid, and pass to the condition of subcarbonates, and that the carbonate of lime is more soluble in water holding carbonic acid, and certain or- ganic acids of the soil in solution, than the carbonate of mag- nesia. At all events, whatever may be the cause of the supe- riority, it is pretty well established by experience, that the ce- ments derived from the argillo-magnesian limestones furnish a durable cement for constructions in the sea. In Marshal Yaillant's report to the French Academy of Sciences, from the Commission to which MM. Ohatoney and Rivot's paper was referred in 1856, this superiority of the magnesian hydrates is distinctly asserted ; but the Commission appear to have been led to erroneous inferences in regard to the conditions under which it is expedient or possible to take advantage of this prop- erty. We quote from the first part of their report, as follows : " On pourrait en conclure qu'il serait utile de remplacer la chaux par la magnesie pour fabriquer les mortiers hydrau- HYDRAULIC CEMENTS, AKD MOETARS. 305 liqnes ; mais la magnesie n'est pas assez repandue dans la na- ture pour qu'on puisse i'employer a 1' exclusion de la chaux dans les constructions a la mer. ^^n'ya^Lnt'" En tout cas, il faut proscrire avec soin le mel- ange de ces bases, c'est-a-dire I'emploi des calcaires magnesiens, attendu que les silicates et aluminates formes par la magnesie ne s'hjdratent pas avec la meme vitesse que ceux formes par la chaux, et qu'ils risquent d'ailleurs d'etre partiellement decom- poses apres I'immersion par la chaux restee en exces, si le me- lange n'a pas ete longtemps digere au prealable dans une faible quantite d'eau. En d'autres termes, ces mortiers ne presentent aucune homogeneite, aucune chance de stabilite dans la prise." It is needless to say that the " careful proscription" of "mag- nesian limestones" so forcibly inculcated in this quotation is altogether too comprehensive. While we are not prepared to say that the double carbonate of lime and magnesia, called dolomite, containing a single equivalent of each of the bases, although eminently hydraulic, could, in practice, be relied upon for hydraulic mortars, even in localities where the supply is sufficiently abundant for such a purpose, yet it is certain, that many magnesian limestones, especially those which contain clay, do furnish good cements, and that the Rosendale brands, our chief and best reliance in the United States, are derived from this class, and ai-e by no means open to the objection ad- vanced above, viz. : that they offer " neither homogeneousness nor chance of stability in setting." Some portions of the de- posit of Rosendale cement stone contain as high as .39 of car- bonate of magnesia to .40 of carbonate of lime; others, as low as .1448 of carbonate of magnesia, to .2848 of carbonate of lime. Between these extremes are found numerous interme- diate proportions. 591. Kecent analyses of American cements . American ce- show that they all contain more or less of the ments contain alkalies, sometimes caustic and sometimes in the form of chlorides of sodium and potassium. The chlorides are 20 306 PEACTICAL TREATISE ON LIMES, present in all the Rosen dale cements, as well as in those from Shepherdstown, Virginia, and Akron, Erie Co., New York. The alkalies promote hydraulic induration in their own pecu- liar way. We know that mortars of American cements part with soda and potash when immersed in water, and render the latter alkaline; and that alumina and gelatinous silica are soluble in potash ; also that a solution of an alkaline silicate readily gives np its silica to lime. We may therefore presume that the alkalies, particularly the potash, act by first dissolv- ing the silica and then transferring it to lime, at the same time that the water acts by dissolving the lime and carrying it to the silica. Wlien the silica is 592. When the silica, present in suitable form m excess. ^-^^ entering into combination, is in excess of the equivalent required by the lime and magnesia, the proportion should be adjusted in practice, as far as possible, by adding paste of fat lime, otherwise the mortar will be deficient in strength and liable to crack. Several prisms (2"x2"x8") were made of the paste of J ames Kiver cement without sand, atid kept in water until they were 320 days old. This cement contains nearly fifty per cent, of silica, although the analysis does not state in what form it exists. Some of the prisms broke in handling. They were all covered over more or less with cracks, were quite brittle, and ranged rather above the average hardness of mortars of pure cement paste as shown by the penetration of the needle. On supports 4" apart those that remained whole gave an average breaking weight of 346 lbs. The fracture was quite jagged and angular, although each of the small surfaces composing it was in itself, compara- tively smooth and conchoid al. The first impact of the needle split most of the prisms, and none of them withstood the second. When the block did not split, the effect of the first impact was to raise up the mortar in thin scales around the needle. Tig. 56. HYDRAULIC CEMENTS, AND MORTARS. 307 The general appearance of the fraction is given in Figs. 56 and 57. ISTone of the prisms left in the air conduct- ed themselves in this peculiar way, although they gave low breaking weights, the average being only 330 lbs. A paste of this cement is improved by the addition of lime paste, up to the limit of 75 to 100 per cent. Inert silica in cement acts simply as an adulterating agent, and takes the place of so much sand. THE HARDE^^IKG, BY ARTIFICIAL MEAISTS, OF STONE, BEICK, MORTAR, &c. 593. "Within the last twelve or fifteen years, the attention of engineers and architects has been directed, in a manner more than usually active, particularly in Europe, to the destructible character of many of the materials in most common use for the walls of constructions of all kinds. The consequence is, that a variety of methods have been devised, and to a limited extent practised, for increasing their durability. 594. -No material will retain through a long The hardest stone series of vears the same appearance as when liable to gradual " decay. fresh from the hands of the workman. Even the hardest, most solid and compact rocks, such as granite, sienite, gneiss and the densest silicious rocks, exhibit after long exposure, indubitable evidences of " weathering while many buildings erected within the last quarter of a century, of some varieties of the limestone, marble, and sandstone of this country, the Bath, Reigate, and Caen stone of the British Isles, and their corresponding formations on the continent of Europe, are already in an advanced state of decay. 695. Of all the causes of progressive destructibility in stoiie 808 PEAOTICAL TREATISE O^^ LEVIES, Alternations of ^^^^ more active or more difficult to guard heat and cold, a against, than frequent alternations of heat and cold, and of moisture and dryness. However slight a change of temperature may be, all bodies will expand when it is raised, and contract when it is lowered, although some, even among different kinds of stone, are much more sen- sitive to those variations than others. In the United States, the thermometer will vary 110 to 120 degrees between the severe frosts of winter and the direct rays of the summer's sun ; extremes which, operating in conjunction with the presence of moisture in the pores of the solid body, alternating not only with the seasons, but oftentimes, especially in the winter, with the recurrence of night and day, between the opposite condi- tions of water and ice, cannot but result in a change in the state of aggregation of the body, and, if the latter be more than or- dinarily porous, in serious disaggregations near the surface. This will be more especially the case, if the mass be made up of several substances of different specific gravities, and of unequal capacity for resisting the expanding power of heat. 596. The methods devised for increasing the durability of stones, hricks, tiles, &c., are doubtless equally well adapted to mortar work, such as exterior stucco or concrete, and may with propriety be noticed here. In fact, those modes which now give the best promise of efficacy, 'base their claims to pub- lic support, in a great measure, upon their alleged applicability to such purposes, particularly to the restoration of monuments, statuary, interior and exterior ornamentation, &c. 597. The methods of artificial induration are reduceable to The general tWO, as follows : methods of artifi- First. By means of those mixtures or solu- cial induration. . i . i i i t i i /. tions, which, whether applied to the suriace with a brush like paint or oil, or by immersing the solid body in them for a longer or shorter time, act simply as mechanical protectives against the penetration of moisture, by forming either an impervious coating upon its surface, or, by penetrat- HYDEAULIC CEMENTS, AND MORTAES. 309 ing to a greater or less depth, close up the pores, and render it non-absorbent. Second. By means of those aqueous solutions, which possess the properties of reagents, and which, when entering the inter- stices of the solid, give rise to certain chemical reactions by combining with it, or with other and different solutions ap- plied before or after, whereby insoluble solids are produced, and the density and hardness, and consequently the durability and strength of the solid are increased. 698. Among the first class may be noticed Examples belongs a patent " for indurating and preserving stone,-' ing to the first granted in England in 1847. The stone to be operated upon was first dressed to the required form, and then thoroughly dried in a heated chamber, or by some other suita- ble contrivance, to drive off' the moisture. The solution, com- posed of resin dissolved in turpentine, oil, wax, tallow, or some other fatty substance, being brought to the boiling point in a vessel of the requisite dimensions, is retained at that tempera- ture while the stone is immersed in it. Ordinarily, two hours' boiling has been found sufficient to impregnate the stone to the depth of one inch. A similar process was patented in England in 1853, in the application of which it is recommended to operate upon the stone in air-tight chambers, exhausted, or partially so, of the air, by wdiich means a more thorough impregnation of the material is secured. Several varieties of indurating mixtures were recommended by the patentee, only two of which we will give. The first is composed of resin dissolved in naphtha, turpentine, or spirits of wine, mixed with gutta percha dissolved in coal-tar naphtha, and when heated, mixed still further with some kind of oil, after whicli w^ell pulverized " anti-corrosia" is added. Another mixture is made from unslaked lime, to which is added, whilst slaking, oil, or soap fat, and Eussia tallow. When the slaking is completed, the whole is placed in a vessel with alum water, aio PRACTICAL TEEATISE ON LIMES, pulverized " anti-corrosia," and proto-sulphate of iron, and a solution made from potatoes and beer settlings. After settling, the solution is decanted for use. Another patented process consists in the repeated applica- tion, with a brush, of a solution of bee's wax in coal-tar naph- tha, which is varied when the natural color of the stone is to be preserved, to white wax dissolved in double distilled cam- phene. 599. Without discussing the respective merits of these First method not ^^ethods, we will simply suggest that no process practicable al- of indurating and preserving stone, that re- ^^^^ quires the handling and removing of heavy masses, will ever be likely to reach an extensive application in the United States. The characteristic impetuosity of our peo- ple, the very active competition existing in all departments of industry, and the low scale of prices to which this state of things has given birth, excludes the idea that any slow, plod- ding, and costly method, however valuable and efficacious for attaining a desirable end, can enter into successful competition with one that is more rapid, less expensive, and easy of appli- cation. It is also unlikely that any plan for indurating and preserving architectural stonework, that cannot be advan- tageously executed without complicated appliances, and aftei the building is erected, will ever become of any practical utili ty ; and it is equally unlikely that any solution of resin, wax, or like substances in the fixed or essential oils, which, whether applied hot or cold, merely remain mechanically interposed in the interstices of the solid body, can ever furnish other than a. temporary protection. 600. The methods of preservation which belong to the second Examples belong- ^^^^^^ indurating media are ap- ing to the second plied in the condition of an aqueous solution, method. possessmg reacting powers, rest upon a more scientific basis, and are essentially different from those referred to abovn. Mr. Fred. Ransome gives the following particu- HYDRAULIC CE:.IEIS[TS, AND MORTARS. 3H (ars of a process for whicli he procured a pat- Ransome's pro- C6SS. ent in England : It " consists in the employ- ment of two or more separate solutions, which, by mutually acting upon each other, produce within the pores of the stone an indestructible mineral precipitate. In operating, the stone, may either be immersed in, or saturated on the surface with a weak solution of silicate of soda or potash, and afterwards with a solution of chloride of calcium or barium, when an insoluble silicate of lime or baryta is formed in the pores of the stone, rendering it impervious to moisture, and in- susceptible of injurious effects from atmospheric influences. Or, instead of a silicate of potash or soda, a solution of sul- phate of alumina may be employed, and then, by an applica- tion of baryta, a compound of sulphate of barytes and alumina is formed." This process, although apparently closely re- ^ Kuhimann's sembling that recommended by Professor Fred, general process. Kuhlmann, of Lille, briefly referred to in paragraph 551, difiers from it in the important particular of its alleged adaptation to all kinds of stone, and of using, in all cases, two solutions in- stead of one, the increase of density of the stone operated upon, being due to the solid compound formed by the mutual decom- position of the two fluids employed ; whereas M. Kuhlmann recommends his process of silicatization to the hardening of soft limestones and marble, whether in the walls of buildings or in the form of monuments, ornamentation, or statuary, tO; calcareous mortars of all kinds, and to all works of whatevei character made of plaster, such as mouldings, casts, &c. 601. The following extract is taken from the " Report of the Commission chargied by the Minister of Am- 1 ^ 1 V» 1. ^ 1 11 Report of Corn- culture, Commerce, and Public W orks, with the mission on Kujil- examination of M. Kuhimann's processes of sili- ^^^^ ® process, catization." " The liquo7' of flints — silicate of potash or silicate of soda- is the base of the new process. As far back as the year 1840, 312 PEACTICAL TREATISE ON LIMES, some examination into the origin and nature of the efflores- cences on walls, had given M. Kuhlmann an opportunity to establish, beyond doubt, the presence of potash and of soda in most of the limestones of all geological epochs, in larger pro- portions in the hydraulic limestones than in those suitable for common lime. What influence can they exert upon the hy- draulic property ? M. Kuhlmann is of the opinion that, under the influence of carbonate of potash or of soda, the silicious limestones give rise by calcination, to double combinations of lime, of silica, or alumina, with an alkali, analogous to those obtained by the calcination of some species of hydrated mine- rals, such as the apophyllite, the stilbite, and the analcime; that these compounds, subsequently put in contact with water, undergo a reaction analogous to that which causes the consoli- dation of sulphate of lime, viz. : a hydration, and as a conse- quence thereof, an induration. " The principal eflfect produced by the potash and the soda, is to convey a certain portion of silica to the ^h^and^soda!'^*" Hmo, giving birth to silicates, which, while they absorb the water with avidity, retain only such quantity of it as is necessary for their composition as hydrates, and for their induration. Numerous facts support this theory : fat lime, placed in contact with a solution of silicate of potash, is immediately transformed into hydraulic lime ; mortars of fat lime, injected several times with a solution of alkaline silicates are transformed into hydraulic mortars ; lastly, with the vitre- ous alkaline silicate, and lime more or less energetic, hydraulic cements can be produced, which can be utilized in localities where none but fat lime is found in the quarries. 602. Silicatization. — M. Kuhlmann^ by noticing the great aflinity of lime for silica, left free in the nascent state, from its combination with potash, was also led to study the action of the silicates of potash and of soda upon the soft limestones and chalk. He noticed the fact, that if chalk is placed in contact, at the ordinary temperature, with a solution of silicate of pot HYDEAULIC CEMENTS, AND MOETAES. 313 ash, it is partially changed into a silicio-carbonate of lime, while a corresponding portion of potash is displaced ; that the chalk gradually hardens in the air, and becomes harder than the best hydraulic cements ; that the same chalk, made into a paste with the silicate, possesses the property of strongly adhering to the surface of bodies on which it is applied. He has thereby discovered a mastic suitable for the restoration of public mon- uments, and for the fabrication of works of moulding. Carry- ing his experiments still further, he found that the chalk, in the state of rock as found in nature, if repeatedly immersed in a solution of silicate, and alternately exposed to the action of the atmosphere, is capable of absorbing a considerable quantity of silica, and after some time acquires great hardness on its surface; that the induration, at first superficial, penetrates by degrees towards the centre, so much so that a sample, experi- mented upon fifteen years previously, and placed before the Commission for inspection, had acquired that induration to a depth of nearly one centimetre (.39 in.) This " silicatization," as M. Kuhlmann styles his process, is due to the decomposition of the silicate of potash, partly by the carbonate of lime, and partly by the carbonic acid of the air. A solution of silicate of potash left in the air, will, in effect, after some time, form a gelatinous «,iid contractible deposit of silica, and a layer of car bonate of potash. The deposit of silica acquires, after some time, a hardness sufficient to scratch glass. Of two balls of chalk of the same size and quality, both silicatized in the same manner, the one left in the open air acquires a greater hard- ness than the other placed under a glass receiver, where the air is free from carbonic acid. By this process, therefore, there is formed a kind of a hydrated silicio-carbonate of lime, which indurates while gradually abandoning its water of hydration, and a contractible deposit of silica, which also augments the hardness of the stone. The carbonate of potash produces on the surface a perceptible exudation or efflorescence, which de- creases by degrees, and at last totally disappears, without hav- 314 PRACTICAL TREATISE ON LIMES, ing altered the surface in any manner. By means of the hy- drofluo-silicic acid, M. Kuhlmann has succeeded in obviating the inconveniences that may arise therefrom, while he at the same time increases the progressive induration " Calcareous stones thus prepared assume a compact texture, a smooth appearance, and are capable of receiving a fine polish. The induration is singularly favored by heat. Some porous limestones, immersed in a boiler, under a high pressure, con- taining a bath of silicate of potash, assumed soon after removal all the characters of compact silicio-calcareous stones, without the slightest intervention of the carbonic acid of the air. 603. M. Kuhlmann experimented upon other porous stones^ and observed that the action of the carbonic acid of the air upon silicate of potash, was sufficient to cause on the surface of the stones a consolidation varying in intensity with their porosity. 604. Upon the sulphate of lime or plaster, the action is sen- sibly the same, but is more rapid, and possesses Action on sul- . . p . . . phate of lime. the mconvenience oi giving rise to sulphate of potash, which, by crystallizing, has the property of disaggregating the surfaces. In this case the solution must be more diluted, in order to secure a slower action, although producing a sufficient consolidation for avoiding the effects of the crystallization of the sulphate of potash. 605. " Mode of appliGation. — The solution of the silicate of potash, as manufactured by M. Kuhlmann for the market, is quoted at 35° by Beaume's areometer. It is sufficient to dilute it in twice its volume of water, in order to obtain the degree of concentration most suitable for induration. Upon recent con- structions, the application can be made without preparation ; on old ones, it is preceded by a thorough washing of the surface, using for this purpose a hard brush dipped in a dilute solution of caustic potash. Upon large surfaces, the applications are made with force-pumps or syringes, care being taken to collect, by means of ridges made of potter's clay, at the foot of the wall, the liquid in excess. For sculptures and certain portions of HYDRAULIC CEME^^TS, AND MOETAES. 315 buildings, soft brushes, or more advantageously pencils, are made use of. Experience has shown that three applications made during three days consecutively, are sufficient to properly harden the stone. The quantity of solution absorbed varies with the nature and porosity of the stone ; the cost of the silicate never reaches above 75 centimes per square metre (12 cts. per square yard) for the most porous stones." 606. " This process, having been applied to the new sculp- tures of the Lille Bourse, to the works of res- n nr • i i Examples. toration oi bt. Maurice Chm-ch, to the construc- tion of a new church at Wazemmes, to the Seclin Hospital, in some works of military engineering, and in private construc- tions at Lille, has completely succeeded." 607. " As early as 1841, MM. Benvignat, Marteau, and Yerly witnessed the efficacy of this process. It was also practised elsewhere, at Yersailles, Fontainebleau, the Chartres Cathedral, the Lyons City Hall, the Louvre, and Notre-Dame at Paris. Yery able engineers, such as MM. Lassus, Lefuel, and Yiolet- Leduc, have obtained from it the most satisfactory results."* 608. " jStone Dyeing. — M. Kulilmann observing that the sili- catization of constructions and sculptures gives rise to various discolorations which showed the joints more dis- Mauagement of tinctly, was led to find a remedy for this defect ^o^^^- in his process. By means of the double silicate of manganese and potash, he obtained a blackish solution applicable to cal- careous stones of too light a color. By diluting in the silicious solution some artificial sulphate of baryta, those limestones ♦Although proofs, apparently the most conclusive, of the efficacy of the alkaline silicates as indurating agents, may be multiplied, the subject still appears to be surrounded with practical difficulties ; and the advocates of the new theory meet at every turn reports of unsatisfactory results or mortifying failures. The " London A-thenseum" of August, 1859, contains a statement that the exterior walls of Noire Dame^ and the Palace of the Louvre are in a very unsatisfactory condition, that the rains had apparently destroyed the preservative powers of the silicate, before the surface had, by the absorption of carbonic acid gas, attained a degree of hardness sufficient to resist their action. — Author. 316 PRACTICAL TREATISE ON LIMES, ETC. that are too dark are lightened up. He found that the porous limestones submitted to ebullition in solutions of metallic sul- phates of oxides, insoluble in water, cause the fixing, at a certain depth, of said oxides in intimate combination with the sulphate of lime. With sulphate of iron, he obtains a rusty color more or less dark ; with sulphate of copper, a magnificent green dye ; with sulphate of manganese, brown hues; with a mixture of the sulphates of iron and of copper, a chocolate color, &c. He also observed that the double sulphates thus formed penetrate into the stone and also increase its hardness." THE END. APPENDIX. DESCRIPTION AND ANALYSIS OF THE COST OF SEVERAL QUALITIES OF CONCRETE USED IN THE CONSTRUCTION OF THE FORTIFICATIONS ON STATEN ISLAND, NEW YORK HARBOR, DURING THE YEARS 1870 AND 1871. DESCRIPTIOK OF MATERIALS USED. Portland Cement. — Portland cements from three localities were used during the two seasons, viz., from Stettin, Germany, from Boulogne Sur-Mer, France, and from the Thames, near London, England. They were found to differ very little in quality. The tests of strength made from time to time showed the Boulogne cement to be a little superior to either of the others, but the difference in this respect was about compensated by its extra cost. The Boulogne and the London Portland cements used on the Staten Island works through two consecutive seasons, as well as several thousands of barrels received ia l^ew York, and tested, either for private use, or for officers of the corps of Engineers located at distant points, have, with one exception, been found to be fully up to the standard exacted by the English aud the French Engineers. The use of the Stettin cement on the fortifications has been 318 APPENDIX. limited to one invoice, which was entirely satisfactory as to quality, hut fell short in weight seven pounds to the cask. In- asmuch as manufacturers of Portland cement invariably sell by weight, this difference is of no moment, except to dealers and consumers who purchase by the cask. STANDARD QUALITY OF THE CEMENTS USED. Portland cement should weigh not less than 106 lbs. to the struck imperial bushel, loosely measured, and should be ground so finely that at least ninety per cent, of it will pass a ISTo. 35 wire gauze sieve, of 47 wires to the lineal inch each way. When mixed with fresh water into a paste of the consistency of stifl' plasterers* mortar, without sand, and pressed into a mould, it should, at the end of seven days, sustain a tensile strain of 500 lbs. on a sectional area of 2 J square inches, (IJ inches by l^ inches) equal to 222 lbs. per square inch, having been kept six days in water. This is a combination of the tests applied by the English and the French engineers, that is, it is the lowest English standard of weight, the highest of tensile strength, and the ordinary French standard of fineness. Cement of this quality can be made with as much ease and certainty as that of a lower grade, while the increase in the cost of manufacture, due to the consumption of extra fuel and grind- ing power, is but trifling. As it is not a wise policy to pay ocean freight on an imported cement of inferior quality, the highest standard of excellence should be exacted. Lime. — The lime was quarried, burned, and ground at Eon- dout, Ulster Co., IT. Y. It is known in the market as Kondout ground lime. One barrel of this lime (268 lbs. net) produces 2f bbls. of fine powder loosely measured, when slacked with 15 gallons of water. If water be added in suitable quantities, the 2|- bbls. of loose powder will yield If bbls. of paste of the consistency of plasterers' mortar. This lime is not pure white, but slightly drab in color, and APPENDIX. 319 although it does not possess any perceptible hydraulic properties, it is generally thought to make a stronger mortar than the white limes. Bosendale Cement — The Eosendale cement was from the manufactory of the IS'ewark and Eosendale Company. Its quality ranges rather above the average of American cements. It weighs from 70 to 74 lbs. to the bushel, loosely measured, and when made into a stiff paste without sand, and pressed into a mould, it will attain, in seven days, having been six days in water, a tensile strength of 140 to 150 lbs., seldom greater, on a sectional area of 2J square inches, equal to 62 to 66 lbs. to the square inch. It is, like other Eosendale cements, subject to very considerable variations in quality from time to time, and often falls greatly below this test. Stone. — The stone used in the several kinds of concrete des- cribed below, was prepared by crushing ordinary limestone in a Blake's stone-breaker. ' The fragments were of all sizes below a two-inch cube, and were of various shapes, being generally quite angular and ir- regular in form. This stone cost $2.00 per ton of 2,240 lbs., delivered to the wharf at the fort on Staten Island. Gravel. — The gravel was the usual mixture of smooth gravel and pebbles from the sea-shore, with the sand screened out. It varied from the size of a pea to that of a hen's egg, and cost $1.60 per ton of 2,240 lbs., delivered on the Government dock at the works. Both gravel and stone varied in size from time to time with the different cargoes, sometimes running a little larger, and fre- quently much smaller, than the general average given above, requiring corresponding changes in the proportions used for making concrete. The mixture containing the least measure of voids was the one constantly sought, and it was always found between the limits of eleven and fifteen volumes of stone, to fifteen of gravel, that is, fifteen measures of gravel were mixe'd with from eleven to fifteen measures of broken stone. 320 APPENDIX. The following table gives the proportions of some of the mixtures tried at various times, with different sizes of stone and gravel : voids 23^ voids 24^ voids 25^^^ voids 26^^ voids 27^^ voids 30^ Mill-made concrete, for all the various uses to which it is ap- plied, possesses sufficient superiority in quality over that manipu- lated by hand, as to justify the expense of suitable power and machinery, when operations of considerable magnitude are to be carried on. The more thorough manipulation secured by machin- ery enables a smaller proportion of the cementing substance to be used, and effects a saving in the cost of both materials and labor. Portland cement of good quality, containing no quick-lime and weighing, say, 106 lbs. to the struck bushel loosely measured, requires 42 to 44 per cent, of its volume of water to convert it into a paste of the consistency of masons' mortar. When quick- lime is present, which is often the case with cements when first made, a larger amount of water is needed. Portland cements that have been overburnt, or those that have become injured from age or exposure, by the absorption of moisture from the atmosphere, and the spontaneous conversion into hydrates, of tke silicates and aluminates and any excess of quick-lime formed in the kiln, require less water for mixing than they otherwise would. 13 measures stone ) 15 " gravel ) 15 measures stone ) 15 " gravel j 11 J measures stone ) 15 " gravel ) 22 measures stone ) 15 " gravel j 12 measures stone ) 15 " gravel f 27 measures stone ) 15 " gravel j APPENDIX. 321 The following tables show the quantities jf paste and mortar of different qualities, some with and some without lime, that can be made with one barrel of cement as the basis : Cement Paste. 1 Boulogne Portland Cement (France). Water. 1 PaPte produced. 1 a 8 1 bbl. (400 lbs. nett) = 1.34 bbls. loose powder 1 " =^1.40 1 " = 1.33 " 16 gallons 16 m " 1.17 bbls. L19 " 1.12 " As an average, therefore, from the foregoing table, 1 bbl. of Boulogne Portland cement, as packed for market, will produce 1.35 bbls. of loose powder, and 1.16 bbls. of paste of the con- sistency of plasterer's mortar. Mortar. I Stettin Portland Cement (Germany). bbl. = 392 lbs. nett Sand. Water. Mortar produced. 1 2 3 4 5 5 6 14 gallons. 17* " 20 2.5 28* " 35 42 1.16 bbls. 1.80 " 2.54 3.36 4.00 <' 4.77 " 5.40 " 5.70 " Mortar. Boulogne Portland Cemeut. Sand. Water. Mortar produced. 1 2 3 4 6 6 7 1 bbl. (400 lbs. nett) 1 >( It it 1 ii (( H (C 1 11 (( (I (t 1 (( (( (( (( 1 2 3 4 5 6 16 gal 21 23* 28* 35* 43* 51 ons. 1.12 bbls. 1.38 " 2.54 " 3.31 " 4.19 " 4.92 " 5.65 " Cement and Lime Paste. Boulogne Portland Cement. 1 bbl. 1 " (400 lbs. nett) = 1.40 bbls. loose powder. " " " = 1.35 " " " " = 1.35 " " " " = 1.31 " " " " = 1.38 " " " = 1.34 " Gi-ound Lime slaked (powder.) 1.25 bbl 1.25 1.25 1.50 1.50 1.50 Paste produced. bbT^~ 85 " 92 " 27 " 34 " 5 " Mortar. Boulogne Port. Cement. Slacked Lime powder loose. Water. Paste produced. Additional Sand. Water. Mortar produced 1 1 bbl.= 1.31 bbls. loose pow. 2 1"= 1.38 " 3 1"= 1.34 " " 4 1 " =1.35 " 1.5 5 1.5 2.62 bbl. 32* galls.! 2.27 32* " 2.34 32* " 2.15 30 . 27* 33*. 7.6.-) bbls. 7.69 " 7.54 " 10.37 " 322 APPENDIX. MORTAK. Rosendale Cement. Sand. Water. Mortar produced. 1 3 4 5 1 bbl. (300 lbs. nett). 1 " 1 " 1 " 1 " 1 bbl. 2 " 3 4 " 15 galls. 178 21 " 25 " 30 1.05 bbls. 1.69 " 2.50 " 3.27 " 4.05 " Concrete Number 1. 1 Bbl. Germau Portland cement (393 lbs.) $3.45 [ ^ a u^Io ^^^.^vnfo r^^vfo,. 5i - damp sand loosely measm-ed, |. 33 f 6 " gravel and pebbles from seashore $1.94)=rJ^t„ "^jiwr. ^nJ^tl 5^.1^1 !! Q a broken stone 28 f shaken down contammg y bi olicn stone, ^d.Z^ J p^^. ^^^^^ ^^-^^^ One batch of concrete composed as above, makes fifty cubic feet of rammed concrete. Tliis is an average of several batches. This concrete is of first-rate quality, being compact, free from voids, and strong. It is richer in mortar than would be neces- sary for most purposes. The cost of the materials for one cubic yard of this concrete delivered at the concrete bed ready for use, omitting the Custom-house duty on the cement, amounts to $4.86 The cost of mixing, transporting, and ramming the concrete, per cubic yard, amounts to $1.37 Lumber and timber, and carpenters' labor in setting up same, $ .32 Total cost of concrete per cubic yard, $6.55 The cost of labor is based upon the following prices for a day's work of ten hours: sub-overseer, $3.50, mason or carpenter set- ting plank, $3.80, and laborers, $1.80. The labor in constructing concrete magazines, in consequence of the extra work in setting the planking at the entrance angles and doors, and in making and setting the centres, and the con- sumption of extra lumber, will amount to about $1.90 per cubic yard instead of $1.69, as given above. Concrete ISTumber 2. 1 Bbl. German Portland cement (393 lbs.) $3.45 ) ^ ^^^^ ^^^^^.^^^ 6 " damp sand loosely measured, $ .36 ) 5 " gravel and pebbles from seashore, $1.62 | Mixed together and shaken 9 " broken stone, $3.28 f down, contains 30^ of voids. One batch of Number 2 makes 50 cubic feet of rammed concrete. The materials for one cubic yard of concrete Number 2, cost, delivered at the concrete bed, $4.70 Cost of mixing, transporting, and ramming, per cubic yard, $1.37 Lumber and timber, and carpenters' labor in setting up same, $ .32 Total cost of concrete per cubic yard, $6.39 APPENDIX. 323 Concrete IN'tjmber 3. 1 Bbl. Boulogne Portland cement (400 lbs.) $3.45 ) 1 " Slaked ground lime in powder, $ .58 >■ =7. Bbls. mortar. 7 " loosely measured damp sand, $ .42 ) 13 " Gravel and pebbles from seashore, $4.20 j* V^^^^^ 13 " Broken stone |. ^4 ^ getber and shaken down, Id tJioken stone, 74 j ^.^^^ ^4^ ^^.^^^^ One batch of concrete Number 3 makes 86J cubic feet of rammed concrete. Strength of the mortar. The mortar with which concrete Number 3 is made, composed of 1 bbl. Portland cement, 1 bbh of shiked ground lime in powder, and 7 bbls. of sand, possesses, when two months old, a crushing strength of 300 lbs. to the square inch, the test being applied to 5 inch or 6 inch cubes. Cost of concrete Number 3. Cost of materials for one cubic yard, $4.18 Cost of mixing, transporting, and ramming, per cubic yard, $1.37 Lumber and timber, and carpenters' labor in setting up same, $ .32 Total cost of concrete per cubic yafd, $5.87 Concrete Number 4. 1 Bbl. Boulogne Portland cement, (400 lbs.) $3.45 ] -7 9 Bbls concrete mor- \\ " Slaked ground lime in powder, $ .72 " ^-I^D'S-concrete moi- 8 " loosely measured damp sand, $ .48 ) 16 " Gravel and pebbles from seashore, $5.17 " tier Pnd shaklrlwn 16 " Broken stone, $5.82 \ ^^-,,0^2 T ' . ^ ) with 24^ of voids. One batch of concrete Number 4 makes 105 cubic feet of rammed concrete, of suitable quality for most kinds of massive work. It contains the greatest admissible proportions of gravel and broken stone. The quality of the concrete would be im- proved by using 18 barrels of gravel and 14 of broken stone, instead of 16 barrels of each. Strength of the mortar. The mortar of concrete Number 4, composed of 1 barrel of Portland cement, 1\ barrels of slaked ground lime in powder, and 8 barrels of sand, possesses a crush- ing strength of 220 lbs. to the square inch, when two months old, the pressure being applied to 5 inch or 6 inch cubes. Cost of concrete Number L Cost of materials for one cubic yard, $4.02 Cost of mixing, transporting, and ramming, per cubic yard, $1.37 Lumber and timber, and carpenters' labor in setting up same, $ .32 Total cost of concrete per cubic yard, $5.71 324 APPENDIX. Concrete ^sTumbek 5 (made with Eosendale cement) : 1 Bbl. Rosendale cement (300 lbs.) $1.77 ) 3 " Damp loose sand, $ .18 >• =3.27 Bbls. concrete mortar. 5 " Broken stone, $1.82 ) This batch of concrete, as the average of an entire season'? work, has been found to yield 21.75 cubic feet, rammed in position. Strength of the mortar. The mortar of concrete ISTumber 5, composed of 1 barrel Rosendale cement and 3 barrels of sand, possesses a crushing strength of 130 lbs. per square inch when two months old, the test being applied to 5 inch or 6 inch cubes. Cost of concrete Number 5. The materials for one cubic yard cost $4.67 Cost of mixing, transporting, and ramming, per cubic yard, $1.37 Lumber and timber, and carpenters' labor in setting up same, $ .32 Total cost of concrete per cubic yard, $6.36 Concrete J^umber 5 is the standard quality of Rosendale cement concrete generally adopted upon government works. It pos- sesses sufficient -strength in foundations and thick walls for any position in which concrete is usually placed. The nearest approximation to it in quality and strength, of any of the Port- land cement concrete used at Fort Tompkins, is concrete Num- ber 6 given below. Concrete Number 6. In this concrete the proportion of mortar to the broken stone, adopted for the Rosendale cement concrete Number 5, has been carefully maintained. Portland cement, 1 Bbl. $3.45] Ground lime, 1 Bbl. producing of lime 1 = to 10.37 Bbls. of concrete powder 2f Bbls. $1.50 j mortar. Sand, 10 Bbls., $ .60 J Broken stone, 16 Bbls., $5.82 One batch of concrete produces 6 9 J- cubic feet, rammed in position. St/rength of the mortar. The mortar of concrete Number 6, composed of 1 barrel Portland cement, 1 barrel ground lime (producing 2| bbls. slaked powder), and 10 bbls. sand, possesses a crushing strength of 154 lbs. to the square inch wlien two APPENDIX. 325 months old, the pressure being applied to 5 inch or 6 inch ciubes. Cost of concrete Number 6. Cost of materials for one cubic yard, $4.41 Cost of mixiiif^, transporting, and ramming;, per cubic yard, $1.37 Lumber and timber, and carpenters' labor in setting up same, $ .33 Total cost of concrete per cubic yard, $6.10 This concrete therefore possesses two advantages over con- crete I^umber 5, viz, : the mortar, although used in the same proportions to the broken stone as in Number 5, costs nearly 11 per cent, less, and is more than 18 per cent, stronger. Hand-made concrete. All the several kinds of concrete described above were made by hand, after the manner indicated in paragraphs 366 to 376. When lime was used, the slaked lime powder and the dry cement were rudely mixed together on the mortar-bed before the sand and water were added. Mill-made concrete. The mill used for mixing concrete is a cubical wooden box measuring four feet on each edge in the in- side. It is provided on one face with a trap-door about two feet square, close to one of the angles, and is mounted on an iron axle, passing through opposite diagonal corners. An ar- chimedean screw mortar-mill, for mixing the concrete mortar, is used in connection with the box, and both are driven by a small engine of about six-horse power. Eight revolutions of the box, made in less than one minute, are found to be quite suf- ficient to produce the most thorough incorporation of the mortar with tlie broken stone and gravel. Every piece of stone, and every pebble and gravel, become completely coated over with mortar. In making the mortar, the cement, lime, and sand are first rudely mixed together with shovels on the mortar-bed, and are then passed through the mill once; one measure of the dry mixture (about a cubic foot), alternating with one small measure of water. The precise amount of water necessary is determined by trial, and will vary from time to time with the more or less moist condition of the sand. 326 APPENDIX. Four men with barrows are employed in conveying the con- crete materials (the mortar, broken stone, and gravel) into the concrete box, one barrow full of the mortar (2 cubic feet) alter- nating with three heaped up barrows full of the coarser ingre- dients (7 cubic feet). The materials are dumped into the box from a staging, erected on the level of the trap-door when at its highest point. One charge of the box contains : 4 barrows of mortar (8 cubic feet). 6 heaped up barrows of broken stone (14 cubic feet). 6 " " " gravel (14 " ' ). After mixing, the trap -door is opened and the contents de- posited on the platform below, by two or three revolutions of the box. The concrete box produces such a thorough and com- plete trituration of its contents, that it is not necessary that the mortar should be mixed beforehand. The mortar-mill, as an auxiliary, may therefore be dispensed with. The ingredients of the mortar (the cement, lime, sand, and water), after being pro- perly proportioned by measure and rudely mixed together with shovels, require no further preparation, but may at once be added to the coarse materials in the box. The method of charging the box by barrows, practised at the Staten Island works, is not considered the most economical that can be devised. A crane or derrick worked by the same engine that turns the box, and having a sweep of sufficient length to reach the mor- tar-bed, and the piles of broken stone and gravel, would doubt- less be an improvement. A concrete box employed by General Duane in Portland Harbor, Maine, is operated in this way. One box of the capacity above described (4' x 4.' x 4' on the inside) will mix from 95 to 100 cubic yards of concrete in one day of ten hours, and will do the work very mucL better than it can be done by hand, and at a saving of from 15 to 20 per cent, in the cost of labor. INDEX. Paragraph. Absence of upper layers of Rosendale cements 40 Absorption of carbonic acid by limes, 98, 831, 578 Abundance of common limestones in the U. S 1 Abuse in burnino- limestones 235 " in slaking lime by drowninsf. 320 Activity, hydraulic 121, 122, 123 Adhesion of cement mortars to bricks and fine-cut {granite 543-545 Adhesion of mortars 32, 531-535 " of cement through muslin. 536-542 Advantages of concrete 447-448 " of slow-setting cements. ... 93 Aggregates, meaning of term 311 " strength of. 312 Air, hydrate of lime in 331-338 " cement deteriorates in 298 lime hardens in 103 " disintearrati on of mortars in 430-438 Air-slaked limes, Totten on 338 Air-slaked hydraulic lime 308 Akron cement contains alkalies 591 cement manufactory at 84 " cement, strength of . . 557 Algiers, concretes at mole of. . .. 154, 15G, 500 Alkalies in American cements 591 Alkaline salts in hyd. limestones 4, Itt " silicates acting on chalk 141, 147 " " " sulphate of lime 148 Alkaline silicates in mortars 142, 143, 145, 551-553 Alluvial clay for artificial cement 129 Alumina in hydraulic limestone 4 how detected 190,207-209 " re-action of in kiln .585-587 American cements, alkalies in 591 " " strength of. 520 " limes, experiments in slak- ing 327-330 Analysis of Akron limestone 226 " " Argillo-magnesian lime- stones of New York, New Jersey, and Virginia 16, 22(5 Analysis of Vicat's artificial Portland cement 131 Analysis of Cumberland limestone, Md.. 226 " Englii^h cement stones 2-26 " " James River cement 226 " laitance 474 " " Lockport cement, Niagara Co.. N. Y 226 Ammonia, molvbdate of 196, 201, 202 oxalate of, 192, 193, 213 pure water of, 190-192, 202, 203, 207, 208, 210 Paragraph. Anaylsis of Maine cement 23 "• " Massachusetts cement 22 " " Mississippi cement 25 " " Point-aux-Roches cement. . . 226 " " Boulogne Portland cement. . 95 " " Pozzuolana 226 " " Round Top cement, Md 226 " " Sandusky, O., cement 226 " " Shepherclstown, Va., cement. 2-26 " Theil limestone 2->6 " Trass 226 " " Ulster Co. cement 226 " " Utica, 111., cement 226 " " Vassy cement, France 226 " " white marble 100 Ancients used Pozzuolana Ml Appalachian chain, limestone in 3, 12 Apparatus for trying cements 173 Arenes 102, 111, 116-118 " are hydraulic 116 " hydraulic activity of increased by burning 117 Aro-illaceous limestones ot U. S 5 Argillo-calcareous deposits of Portland cements 87. 88, 129 Argillo-magnesian limestones in U.S. 5. 12, 110 " " ill New York, New Jersey, and Virginia. . . 13-16 Artificial cements 125-145 " hardening by Kuhlmann's and Ransome's processes 600-607 Artificial hydraulic lime of St. Leger. . . 133 " " Chatony. ... 134 " means of hardening stone, brick, mortar, etc 593-607 " Portland cement 88, 12S-132 " Pozzuolana-mortars, in the sea 150 Pozzuolana's..l24, 135-139, 150, 151 Balcony Falls, Va., cements at 15, 79, 124 Barnegat limestone 10 Baryta, nitrate of 188 Basaltic sands 102, 111, 119 Bastard stucco 408. 412 Belgrand & Michelot's experiments ()f.523. 524 Beton or concrete 161, 4')9-.507 " definition of, &c 439-440 Bi-chloride of platinum 194-195 Bird's-eye limestones 7, 1 1 Bituminous matter 197 Black river group of limestones 7, 11, 15 Blocks of concrete 494, 496, 500, 505 Blue lias limestones 44] Blue limestone of Kittatinny Valley 11 " " and marls of the West 11 Blue ridge Quarry, Va 79 Bolting cement 291 Boulogne pebbles or Septaria. . . . ... 87, 51^ 328 INDEX. Parag:raph. Boulogne Portland cement 87-95 Boulogne Roman cement 92 Box lor lowering concrete in water. , 466-468 Brard's frost test 434 "Breaking the set'' destroys hydraulic energy 144 Breaking weight of cement and lime without eand 547-550 " " of pure cement 520,529 " " of Portland and Roman cements 526, 528, 530 " " of pure and mixed American and European cements.555, 557 Breaking weight of Trass and Pozzuolana mortars 559 Brick masonry, mortar for 380 hardened artificially. . 593-607 Brown coat 414 Bruce, N., cement works of 65 Burning cement atones, abuse in 235 " capricious variations while. 268-287 " care to be exercised in 286 defects of method ot 232 kilns for 237-253 " necessity of care in 258 observations on... 233-236, 263-2,s7 Burning hydraulic limestone. 582, 584-587, 590 " where alumina is present. . . 585-587 silicious limestones 584 Calcareous beds of calciferons group 11 " clay for Boulogne ' Portland cement 87-91 " beds on Potsdam sandstone. . 6 minerals, purest 100 " mortar, definition of 309 " uses of 310 " sand, mortars containing only 579 sandrock 7,8,9,11 Calciferons group or formation 7-11 Calcination of Portland cement 89 conduct of cem'ts during.268-287 " of dissimilar stones 171 " improves Pozzuolanas, 135, 136, 264 " of St. Leger hy. lime 133 " of artificial cement 127, 130 Calcium the base of lime 96 Capacity of Cumberland cement works 77 " " James River " " 79 " " Kensington (Conn.) cement works 83 Capacity of Louisville (Ky.) cement works' 82 Round Top " " " 75 " Sandusky (O.) " 81 " " Shepherdstown (Ya.) cement works 72 Capacity of Utica (111.) cement works. . . 80 " '• Delafield & Baxter cement works 63 Capacity of Hudson River cement works 67 " " Lawrence Cement Co 60 " " Lawrenceville Cement Man- ufacturing Co 69 Capacity of works of Maguire, Crane & Co 68 Capacity of works of Marting&Clearwater 66 " •' " the Newark Lime & Cement Manufacturing Co 58 Capacity of works of Newark and Rosen- dale Co 61 Capacity of works of Ogden Rosendale Co. 64 " " " Rosendale Cem't Co. 62 " " " " Rosendale & Kiug- eton Cement Co ,. 70 Paragraph. Carbonate of lime 96 " " '* in hydraulic limestones 4 " " " on sea-walls 160 " " magnesia in hydraulic lime- stones 4 Carbonate of magnesia on sea-walls 160 Carbonic acid absorbed by limes, 98, 103, 331, 578 Caustic lime in cement mortar 44, 49, 123 Cements at certain stages of burning 269 " American, trials of 520 " artificial hydraulic 125-145 " of Black River limestone 15 color of 292 Cement deposits, heterogeneous 167 " " in Ulster Co 44 " for drain-pipes 463 " and hydraulic limes 102-109 " action of, in sea-water 158 Cementing substance, theoretical mini- mum of 314 Cements will not slake 109 Cement and lime mortars compared 382 Cement manufactory at Akron, N. Y 84 Cement works at Balcony Falls, Va, 15, 79, 124, 226, 264, 295 " " cost of running 82 at Lockport, N. Y 84 " Chittenango, N. Y... . 84 " " " Fayetteville, " 84 " Manlius, N. Y 84 " " "• Kensington, Conn. .. 24 in the West 24 " on the Potomac 15 Cement mortars, the efi'ect of lime in, 549, 550 " " harden simultaneously throughout 36. 37 " " why lime is added to.. 546 " precautions in testing.28-29 " " proportion of lime in, 381 Cements, the basis of concrete mortar in the U. S 445 Cement paste, through muslin 537-542 Cements, precautions in testing 122 " with excess of water 509 " preservation of 2S)8 " (Rosendale) contain alkaline salts 16 Cement stone, analysis of Eno-lish 226 " " difficulty in selecting 170 " " prominent features of. . . 46-95 " " general features of layers ol, 168 " " hydraulicity of underburnt 177 " " in Mississippi 25 " inertness of overburnt 177 " " kilns for burning 228-232, 237-241 " " observations on burning of, 233-23r. " " preliminary trials of. .. 172-182 " stucco, hydraulic 423-429 Cements, some good at all stages of burn- ing 268 Cements, with silica in excess .592 Chalk and clay, for artificial cement. 128. 129 Changeable character of cement stones. . 40 Character of limestones. .. 163-165,183-186 Characteristics of intermediate limes ... 110 " " pure limes 96 Chatoney and Rivot, on hydraulic mate. rials 151,152 Chaux limites of Vicat 43, 110 Chazy group of limestones 7, 11 Cherbourg breakwater 504 Chittenango, N. Y., cement works at. . . . 84 INDEX. 329 Paragraph. Classification of hydraulic limes 107, 108 " " limes for mortar 102 Coarse Ptuff for plastering, 394-396,403, 404, 409 Cofferdam, by Maj. Hunt 473 Cohesive strength of cement through muslin 539, 540 Color of cement 57,292 " " stucco, management of 429 Combinations of good and bad limestones for cements . . 44 Commercial limestone 101 Common limes 102-104 " " paste, under water 103 " " concrete containing. . . 490-492 " mortars, for outside stucco 419 Comparison of cement and lime mortars 382 Composition of concrete at Loveli's Isl- and 488, 489 Composition of mortar 379-380 " " pointing mortar .385 Compound limestones 2 Concrete or beton 161, 439-507 " definition of 439 " blocks 500-505, 515 "• for the Cherbourg breakwater 504 " coarse ingredients of 476-507 " use of in the U. S 506 " of Forts Richmond and Tomp- kins 4!S3, 484, 486, 4S7 " injected under water 494-497 " general practice in making. 445, 446 " ramming 455 " jetties at Marseilles 502 " laid under water 464^75 " English mode of making 444 " made by machinery 451-453 " materials for 478 " may contain common lime. .490-492 " for Boston fortifications 449, 450 " for mole at Algiers 500 " " graving dock at Toulon. ... 501 " not rammed under water 464-475 " proportion of matrix in 440 " of quicklime 441-444 " for roofing arches 493 " in single mass 469 " cart for conveying 456 " founding with 470 " advantages of 447,448 " hollow walls, devices for con- structing 457-462 Concrete, walls revetted with stone ..471-473 " wheelbarrows for conveying 454 Coral sand as pozzuolanas 136 Cost of concrete at Lovell's Island 488^89 " " at Fort Tompkins. . 486, 487 " " plastering 418 " " roofing concrete at Ft. Warren.. 493 "• " manufacturing cement 82 " various kinds of masonry 507 Cracker for grinding cement 288 Cretac(!Ous formation for Portland cement 87 Crotou-bricks, adhesion of mortars to. 531-543 Crucible tests of cement stones 46, 173-182 Culmann on slaking 325 Cumberland cement, strength of 557 " " works, Md., 77, 78 " stone, analysis of 226 Curves of energy of cements 263-268 " " strength of cements 279-285 Darcel on Roman and Portland cement, 522-524 Decay, hardest stone liable to 594 Device for compressing green mortars.. . 33 Devices for laying stone under water 53R constructing walls of concrete, 457^62 Delafield & Baxter's cement, strength of, 557 " " works.. 63, 124 Delesse on Boulogne Portland cement. .87-95 Demarle & Co., Boulogne, France 87 DestructibiUty of stones, causes of 595 Deteriorated cements 301 "• " strength of James River 306 Deterioration of cement and lime in air, 298-307 Difference in burning for artificial cement 131 Dissimilar stones, burning of 171 Distemper 413 Dividing limes of Vicat 43, 143, 180 Dolomitic earths as pozzuolanas 138 Dover & Alderney Breakwaters 505 Drain-pipes, cement for 463 Draw kilns and flame kilns, . .241-243, 249-256 Drowning, slaking lime by 319-322 Totten's experiments on 338 Dunlop's Creek, Va., cement from 15 Dupont's mill, for grinding cement 88 Durability of stone 596-607 Eaton, transition sandrock of 10 Efilorescences, mural 561-577 Energy, curves of hydraulic 264-266 " hydraulic 121,123 English cement, analysis of 226 European limes and pozzuolanas, in sea- water 150-161 Europe, pozzuolanas found in 112 Examination of limestones 166-227 Excess of caustic lime, in mortar 44-49 Experiments on limes and pozzuolanasl50-161 Experiments in slaking limes 327-330 " by General Tot- ten 329, 338-344 Experiments based on change of tempera- ture 124 Exterior plastering or stucco 419^9 Fabrication of mortars 342-383 Fat limes 102, 103 Fayetteville, N.Y., cement works at 84 Feburier, experiments of 157 Fertilizer, poor lime as 105 Fine stuff for plastering 394, 397-399 Finishing coat 398, 399, 408-413, 417 Flame kiln 241-243 Floated coat 404 Formation I. of Rogers' classification — 6 II. " " 7, 11, 12 VL " " 38 Formula for rupture 497, 527, 554 Forge scales 135 Fort Adams, efflorescences at 565, 566 " experiments by General Tot- ten at 1-21, 499 Fort Carroll, laying concrete at 464, 465 Forts Richmond and Tompkins, concrete for 483-487 Fort Taylor, mortar mill used at 128 " Warren, cost of concrete at 493 Fossiliferous limestone 11 France, arenes found in 116 " artificial cements in 125 " pozzuolanas found in 112 Fresh water for slaking 337 Frigo rifle mixtures 433 Frost, its eflect on mortars 430-434 Fuchs on Alkaline sUicates 146 330 INDEX. Paragraph. Fuel for burning cement 230, 254 Gauge stuff 399 General feature of cement deposits 168 Geographical localities of argillo-magne- sian limestones of New York, New Jersey, and Virginia 13, 14, 15 Glenn's Falls lime 330 Gneiss-sand, as pozzuolana 139 Goveniors Island, concrete blocks at 515 Granites Ill, 119 Grauwacke 102, 111, 119 Grinding cement 288-291 Growth, in slaking process 319 Guadaloupe, pozzuolana of 112 Hand-floating 403, 405-407, 411, 413 Hand-made mortar 359, 365-378 Hardening of stone, etc., artificially . .593-607 Hardening of cements under water 107 Hardening under water, classification based on 102 Hard finish 399, 408, 413, 414 Hardness of arnees-mortar 116 " cement mortars 510-515 " mortars, method of testing. . 31 Harwich Roman cement 86 Helderberg division of hyd. limestones. . . 18 Heterogeneity of cement deposits 167 High Falls cement, trials with 529 Hoffman brand of cement ... .60, 302, 303, 557 Holland, trass found in. 113, 114 Hydrate of fat lime in the air 331-338 " " lime as a chemical compound 96 " " magnesia 590 Hydraulic activity 121, 122, 123, 124, 276 " cements in sea-water 158 " cement stucco 423-429 " cements require no sand 109 " cements, from Onondaga Salt group 18 " cements, clast^iflcation of. . . 102-109 " energy, how destroyed 144 " induration, theory of 582-592 Umes 102, 107, 108, 307, 308 " " slake with difficulty 322 " limestones, examination of, 166-308 " " eftects of burning, 582, 584-587, 590 '* limestones, qualitative exami- nation of 183-197 " limestones, quantitative ex- amination of 198-227 Hydraulicity of arenes, theory of 116, 117 " index of, in Theil Lime 156 " maximum and minimum of, 263-285 " cause of 182 " of underburnt cement stones 177 Hydro-chloric Acid, in analyses, 189, 190, 200, 202, 206, 208, 210, 214, 216 Hydro-chloric Acid, pozzuolanas soluble in 112 Hydrogen, sulphite of, its use 195 Hydro-silicate in artificial cement 140 Illinois, limestones in 3 Immersion, slaking by 323 Impact, hardness of mortars by 31 Impurities in limestones 101-109 Increase of strength of mortars 554-558 " of volume in slaking lime, 96, 103, 105, 107 Index of hydraulicity 156 Indiana, deposits of limestones in 3 Paragrapli. Indurating mixtures 598 Induration by absorption of carbonic acid 331 " in the air , 103 " artificial 597-607 " of hydraulic limes 332 " hydraulic, theory of 582-592 " of mortars of fat limes... 578-581 Inertia, instant of 177-179 Inertness of overburnt cement 177 Inferior cement stone used 43 Ingredients of artificial Portland cement.88,182 " " concrete 476-507 " " hydraulic limestones 4, 582 " " natural pozzuolanas Ill " St. Leger hydraulic lime. . . 133 Interior plastering 389^18 Intermediate limes 269 " "• improved by age 300 " " unfit for use, 47-49, 52, 53, 143, 180 " in the United States. 109, 110 " " when used under water, 110, 143 Iron, oxide of, how detected, &c., 191, 207, 294-296 Isle of Bourbon, cements of 295 Italy, pozzuolanas found in 112 James River cement mortars, strength of, 520, 557 " " " works, 79, 124, 226, 2.59, 264, 268, 303, 306 Kensington cement works, Conn 83 Kentucky, limestone in • • • 3 Kimmeridge clay, England 86, 87 Kilns for burning cement 228-282, 237-241 " common lime 24.5-256 " intermittent 244-248 " perpetual 231,237-241,249 Kiln, starting the 231 Kingston and Rosendale cement mortar,, 5.57 Kuhlmann on alkaline silicates.. 146, 149, 551 " " efllorescences 5t)8 " process of silicatization. . 600-607 " process of stone dyeing 608 Kuhlmann's report 16 Laitance 468, 474 , 475 Lathing, common faults in 404 Lawrence cement 62, 5.57 Cement Co 60, 61 Lawrenceville Manufacturing Co. 69 Layers of cement, general feature, of.. 168 " Rosendale cements 39 Laying 401, 403-405 coat and set 404 " concrete under water 464-475 " stone under water, device for, 536-542 Light Rosendale cement 57 Liquor of flints 60^ Lime in cement mortars 5-n " and arenes ... lit Lime, alkaline salts in 16 " concrete containing coninion490-492-496 " for stucco 4-JO " mortars with pozzuolana 588, 589 " " with trass 558, 55!> " quantity of, how determined.. 192, 213 " in cement mortars 549, 550 " mortar over arches 498 " added to trass 113 " preservation of 339-341 " pure, how tested 99 " method of slaking 317-383 INDEX. 331 Paragraph. uime, the characteristics of. 96 " added to cement mortar 381 " added to pozzuolana 112 " for vvhitewashing 321 Limes as sources of mortar 102 common 102-101 Lime, kihis for bnrning • 245-256 hydraulic slakes with difficulty — 322 " hydraulic 102, 107, 108 induration of 331, 578 " intermediate 109, 110 " poor or meagre 102,105,106 Limestone and chiuk, action of silicate on. 147 Limestones, argillo-magnesian 12, 16 " in New York, New Jersey, Virginia, and Penns^ylvania 13-15 Limestones containing alumina 585-5S7 '• diversified character of. . 163-165 " examination of 106-308 " hydraulic, effects of burning, 58i, 584-587, 590 " " mineral character of 183 analyf^isof 183-227 "silicious, products of burning 584 Limestones underburnt 136 Lockport, cement works at... .84, 226, 262-265 Louisville cement works 82, 124 Lovell's Island concrete, Boston 488, 489 Machine for breaking stone 479-482 " " making concrete 451-453 " " " drain pipes 463 Magnesia a protection of sea walls 161 " deposit 18, 19 " how detected in limestones, 191, 212 hydrates of 590 limestones of the West 10 Maguire, Crane & Co's cement worlis 68 Malaguti & Durocher on mortars 294, 296 Manganese, how detected in limestones, 191, 212 " oxide of 293 Manlius, cement works at 84 Manufacturers neglect assorting the stone 42 Marsseilles, concrete for jetties at 502 Martins & Clearwater's cement works. . . 66 Martinique, pozzuolanas found in 112 Masonry, cost of various kinds of 507 " volumes of mortar in 507 Massachusetts, limestone in. 22,23 Maximum and minimum hydraulicity 269 Meagre limes 102 Memoir by Chatoney & Rivot,151, 152, 508-519 Method of burning (ements 232 Method of slaking hme 317. 359-364, 383 " testing strength of mortars, 27, 32, 531-535 Mills for grinding clay 88 " " chalk. 128-132 Minard's opinion of tests for mortar 438 Mineral character of limestones 183-186 Mississippi, limestones in. 25 Mixing stands for mortars 315 Modifications of ordinary method of slaking lime. 360-364 Moisture absorbed by lime 98 Molybdate of ammonia 196, 201, 202 Mortar, action of magnesia on setting of 590 ofarenes, with rich lime 116 " artificial hydraulic 125 " of artificial pozzuolanas in sea water .. 150 Mortar box and cart 383 " cement hardens simultaneously throughout 36,37 Paragrrapli Mortar of common lime, where employed 104 " " setting of .581 " containing calcareous sand only. . 579 " cost of making 356-358 " definition of the setting of 120 " disintegration of 430-438 " eff"ect of frost on 430-434 " eftect of sea water on 435-438 " fabrication of 342-383 " of fat lime, induration of . . . 578-581 " frigorific mixtures for testing. . . 433 " of intermediate lime 110 " made of lime and trass, or lime and pozzuolanas 558-560, 5S8, 589 Mortar making by hand 359, 365-378 mill 345, 546, 350-358 " mill at Ft. Taylor 350. 351 " mill of M. Greyveldinger. . . . 352-358 " mill for grinding chalk 132 " mill for grinding Portland ce- ment 129 " of the mole of Algiers 154-156 "■ a mechanical mixture 508 " pointing 384-388 of Portland cement, its superi- ority 517-519 " proportion of ingredients for, 344, 379 " for various kinds of masonry 507 " for stone and brick mas^onry 380 Mortars, strength of certain 1,55 Mortar, technical signification of term.. 31! " used for plastering 394-400 Mud, argillaceous, for Portland cement. . 129 Mural efflorescences 561-577 Muslin, its use in laying stone under water 536-542 Natural cement of Boulogne 87-95 Needle test of mortars 35, 36 " " for mortars as to hardness, 31, 528, 547 Newark Lime and Cement Co 58 Newark & Rosendale Co ... . 61, 124, 243 " cement, strength of 545, 557 Newburgh limestone 10 New Jersey limestone 3, 14 New York limestone 3, 13 Niagara group of Ontario division ... 17, 20 Nitrate of baryta 188 Nitric acid 196, 200 Obernai and Metz hydraulic lime 307 Ochrous earth 102, 111 " sand 116 Ogden Rosendale Cement Co 64 " " strength of . ,. 555 Ohio, limestone in 3 Old method of making artificial cemen'* , 132 One coat work 403 Onondaga Salt Group 18, 20 Oolitic limestone lu Overburut cement stones 177 Oxalic acid to test lime 99^ Oxide of manganese in cement 293 " of iron, how detected, 191,207, 210, 211 " of iron, an ingredient of hydraulic limestones 4 Oyster beds, artificial 155 Oyster shells used in concrete 476 Pacific coast, no cement on 26 Parker's Roman cement 292, 294 Paste of lime under water 103 Pennsylvania, beds of limestone in i 332 INDEX. Paragraph. Percentasfe of day in Boulogne cement. . 87 " of impurities in cements and limes 103, 105, 107, 109 Perpetual kiln 231, 244 patent kiln 237-211 Petzholdt's experiments with old mor- tars 578, 57f» Phenomena developed in slaking poor limes 96, 101, 103, 107 Phosphoric acid in limestones 1%, 200-206 Physical appearance of raw stone no cri- terion of its properties 182 Pise-work, boxing for 460 Plaster of Paris 398,399 Plasterer's nomenclature and tools, 390-392,401 Plastering, cost of 418 " exterior and interior, 389-392, 419-429 Plastering, mortars used for 394-400 Platinum, bi-chloride of 194, 195 Pointing mortar 384-388 Polishing 411 Poor limes ... 102,105,106 Porous limestones with alkaline silicates. 147 Portland artificial cements 128, 295 " cements, strength of 523, 557 " cement of Boulogne 87-95,498 " cement, a superior article, 517-519, 524 " " tractile strength of 516 " *' used at Cherbourg 521 " " used " en coulis" 515-517 Portland and Roman cement mortars, compared 522-530 Potash and soda, how detected. 193-195, 216 -221 " " in hydr. limestones, 16,111, 193, 194 " " in mural efflorescences.. 569 Potomac River, cement works on, 15, 71-78, 268, 275 Potsdam sandstone, 6 Pouilly, cement of 295 Pozzuolana.102, 111, 112,152-154,156, 157, 295 " analysis of 226 " artificial 150, 157 " Italian in sea water, 152, 153, 155, 157, 295 with fat lime 558-5.59, 588-589 " Roman mortar 555 Precautions in selecting cement stones. . 170 " with slaked lime 321,323 " in selecting cement for test- ing 28, 29 " in mixing good and bad • cements 44 Preliminary trials of cement stones. . 172-182 Prepaxation of lime and clay cement 126 " for qualitative examination. 187 Preservation of cements 298. 299 " " limes 339-341 Pricking up 401 Process of silici/ying 146-149 Prominent features of cement stones.. 46-95 Properties of arenes 116 " '• Bo ilogne Portland cement. 92 " "• pozzuolanas 112 " trass 113 Proportion of alkaline silicate 145 Proportion of ingredients, St. Leger hyd. lime 133 Proportion of ingredients for mortars 344 Proportion of lime and clay in artificial cement 126 Paraerapl*. Proportion of lime for cement mortars.. . " " sand to gang of mortars^. . . 314 " " clay in Portland cement... 87 Protecting coat for sea walls 160 Proximity to sea favors efflorescence 570 Psammites Ill, 119 Pure cement with excess of water 509 Pure limestone 96 Purest calcareous minerals 100 Qualitative examination 183-197 Quantitative examination 198-227 Quarries of water lime 20 Quarry of hydraulic lime, Massachusetts, 22 Quicklime, how produced. 96 " mixed with alkaline silicates. 142 Ravier's report on cements and pozzuo- lanas. . 155-156 Ramming concrete underwater injurious 4fi9 Ransome's process- for hardening, etc 600 Remedies for efflorescence 571-577 Remedy for feebly hydraulic limes, etc. . . 145 Rendering 401-403 Report by M. Delesse, on Boulogne Portland cement 87-94 Report of M. Ravier, on seaworthy ce- ments and pozzuolanas 155, 156 Restoration of detei-ioi-ated cements. 301-304 Revetting concrete walls with stone. 471^73 Rhine, trass in the valley of the 113, 114 Rockland lump-lime 330 Roman cements 85. 86, 124, 226, 292, 294 Roman cement mortars, strens^th of. .,557-523 Roman and Portland cement mortars compared , ..... 5-?2-530, 557 Rondout ground lime 330 Roofiny concrete for arches 493 Rosendale cements 20, 26, 290 Rosendale Cement Co., Lawrence brand 62 cements contain alkalies 591 " cement mortars, stren<;th of, 5:20, 557 " " stone, where found, 21, 38 " " layers of 39 " " injected under water, 494-497 Rosendale and Kingston Cement Co... 70 " " mortars .. .555, .557 Round Top cement strength of 557 works, Md., 75, 76, 124, 226 Rubble masonry, pointing of 388 Rupture, instant of 34 Sand, computation of voids in 315 " used in testing 29 " in Portland cements 87 " not necessary for hyd. cement paste 109 Sand, proportion of in mortars 314 Sand rock, calcareous 7 " " transition of Eaton 10 " sifting the 316 " used in mortars 311, 313 " usually added to pozzuolana 112 Sandusky cement mortars 557 " works 81, 124 " limestone, analysis of 226 Sand, why used in mortars 104 Saponifying salts in efflorescences. . . 574-577 Scratch coat 401, 404, 414, 415, 419-429 Schists 111. 119 Screed coat and set 404, 407, 415, 416 Sea-walls, mortar of, how protected 160 INDEX. T^aragraph. Sea-water, cements able to resist 158 ** " pozzuolana mortars in 150 " " its effect on hydraulic mortars 297 " " its effect on mortars artiaci- ally tested 435^38 Sea-water; European limes etc in. 150-162, 435 *' " lor mixing cement 495 Section of Rosundale cement deposits 44 Septaria, for Koinan cement... 86, 87, 124, 512 Setting of mortar defined 120 " " mortars, action of magnesia on the 590 Setting of mortars of common lime 5ol " " mortars influenced by tempe- rature 124 Shawangunk conglomerate, 288 Sheet piles in founding with concrete . . . 470 Sliepherdstown cement contains alkalies. 591 " " mortars, strength of 557 " " works, Va., 72-74 " '• limestone 226 Sheppy Roman cem ent 86 Shrinking does not occur in cements 109 of paste of fat lime.. 103 Sifting cements for testing 29 " sand for mortars . . 316 Silica in hyd. limestone 4 how detected 189,206,225 " in poor limes 106 " when in excess in cements 592 Silicate of potash or of soda 606, 607 Silicatization 146-149 " definition of the term 602 Silicious limestone, products of burning. 584 Sing-Sing lump lime, slaking of 330 Slaking, experiments by Gen. Totten on. 329 " hydraulic limes 107 by immersion 323 " lime, ordinary method of. 359-364 effects of 96, 104 " lime, methods of. 317-383 " poor or meagre limes 105 " spontaneous or air 324-325 Slaty limestone 10 Sling-cart for conveying concrete 456 Slipped work 408, 409, 412 Slow setting of Portland cements 93 Smeaton's opinion of trass 115 Smith's forge scales for stucco work 422 Soda and potash, how detected, 194, 195, 220, 221 Soda and potash in hyd. limestones 16 " in efflorescences 569 Soluble glass, in mortars 551, 558 " ' with bad limestones 49, 141 Solubility of lime in water 97 Source of hydraulicity 182 Spontaneous slaking 324-325 St. Leger hydraulic lime 1.33 Stone-breaking machine 479-482 " cutters' chips for concrete 477 " dyeing 608 " hardening 593, 607 " masonry, mortar for 380 " revetment of concrete walls.. 471-473 Strength of mortars injured by alkaline silicates 553 Strength of aggregates . . 312 "• " certain mortars 155 " concrete experiments on the 498, 499 " of mortars, increase of. . . 554-557 Stucco .389, 400, 408, 411, 414 Subaqueous works, common lime in 104 Subaqueous work, concrete for 448 Sugar water in preparing stucco 421 Piira^raph. Sulphate of lime 148, 604 " " magnesia for testing effect of sea water 435-437 Sulphate of soda for testing lime 99 Sulphide of hydrogen 195 Sulphuric acid, how detected 188,214 " " a solvent for pozzuolana. 112 Temperature, hydraulicity influenced by, 123, 124 Tennessee, limestones in 3 Tentaculate deposit 20,39 Testing mortars, method of 27-29 " wires used by Gen. Totten 121 Test for limes by oxalic acid 99 general character of, for mortars.. 30-32 " of limestones in crucibles 46 Theil, hydraulic lime 154, 156, 502 " " " mortar, strength of. 555 " lime, analysis of 2<;6 Theoretical minimum of cementing sub- stances 314 Theory of the formation of laitance 475 " •' hydraulic induration 582-592 " " the hydi-anlicity of aienes 117 " " mixing cement stones and fuel not tenable , 236 Theory of subaqueous induration 117 Thickness of Rosendale cement beds 39 Three-coat work 4 14 417 Tools required in plastering and pointing, 387, 390-392 Tostain's opinion of pozzuolanas 15-3 Totten's (Gen.) experiments on mortars 121 " slacking lime 3^8, 338-344 Totten's (Gen.) trials of strength of con- cretes 499 Toulon Graving Dock, concrete blocks for .501 Tractile strength of Portland and Roman cements 521, 524, 527, 530 Tractile strength of pure Portland cement 516 Transition sandrock of Eaton 10 Transverse strain of mortars 30 Trass, analysis of 226 " mortars with fat lime 5.58-560 " or Terras 102, 111, 113-115, 157 " where found 113,114 Treatment in burning hydraulic limes, &c. 234 Treatment required for intermediate limes 180 Tremie for laying concrete in water 464 Trenton group of limestones 7, 11 Treussart's (Gen.) experiments with mor- tars .558, 559 Treussart's (Gen.) objections to needle test 35, 36 Trials, preliminary, of cement stones. 172-182 Trying sea-mortars in the laboratory.. 435-437 Try-kilns ... 46 Two-coat work 404 Ulster Co. deposits of cement, 20, 21, .38, 44, 226, 264, 268, 288 " layers of intermediate lime in, 110, 300 Underburnt cement stones 177,2^2 " limestones for artificial puz- zuolanas 136, 187 United States, common lini« in 1 " argillaceous and argillo- magnesian limestones in. .5, 12 " calcareous deposits in 167 " deposits of hyd. limes in . . 11)8 " intermediate limes in 110 334 INDEX. Paragraph, United States, puzzuolanas not known to exist in 112 Utica cement, strength of 557 " " works, 111 80, 124 " limestone, analysis of 226 " slate 12 Vaillant (Marshal) on hydraulic materials 151 " " report on raaj^nesian hydrates 590 Variations of temperature, influence set- ting 123, 124 Variety of cement stones requires variety of treatment 234 Vassy, cement of 294, 295 Vicat's dividing limes , 43, 110 " and Keibell's experiments... 510-518 " mode of trying sea-mortars in laboratory 435-437 Vicat on natural Boulogne Portland ce- ment 95 Vicat's opinion of artificial hydraulic limes 127 Vicat's opinions on the needle-test 35 " " " slaking o20 " researches on the cftects of sea- water 159-1()1, 295, 29(» Virginia and Pennsylvania beds of com- pound limestones 3, 15 Vitruvius speaks of pozznolana 112 Volcanic origin of pozzuolana 112 Water absorbed by the Boulogne ce- ments 92 Water, intermediate limes under 110 arenes under 116 " laying concrete in 464,466-468, 475 hardening of limes in 102-107 " hydraulic cements under 109 " laying concrete under 464-475 Water-limestone 20 Western cements, where made 24 West Point, efflorescence from 567 West Springfield, Mass., limestones 22 Wheelbarrows for conveying concrete 454 Whitewashing, lime for 321 Wire test of pure cement 122 " by General Totten 121 INDEX TO APPENDIX. 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