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EXPEEIMENTS 
 
 - A' I 
 
 STEENGTH OF CEMENT, 
 
 CHIEFLY IN REFERENCE TO THE PORTLAND CEMENT 
 USED IN THE SOUTHERN MAIN DRAINAGE WORKS. 
 
 BY 
 
 JOHN GEANT, M. Inst. C.E. 
 
 These Papees were originally presented to the Institution of Civil 
 Engineers and Read at the Meetings of the Society, Sessions 1865-6 
 AND 1870-1, and are now Reprinted by permission of the Council. 
 
 % LONDON: 
 E. & F. N. SPON, 48, CHAEING CEOSS. 
 
 NEW YORK: 
 446, BROOME STREET. 
 
 1875. 
 
TA 
 IS7S 
 
PEEFAOE. 
 
 The first of the following Papers on Cement was read before 
 the Institution of Civil Engineers, London, in December, 1865 ; 
 the second in April, 1871. Both have been out of print for 
 some time, the first for several years ; and as frequent inquiries 
 are being made for them, it has been considered advisable to 
 reprint them, the Council of the Institution having very kindly 
 given their permission. 
 
 Nothing has occurred since these Papers were read to invali- 
 date the facts or make it necessary to modify the statements 
 made by the Author, who hopes that they may form a safe 
 starting point for anyone who wishes to pursue the subject 
 farther. 
 
( V ) 
 
 INDEX. 
 
 Abernethy, Mr., remarks, 50. 
 Abrasion of Portland cement concrete, 
 93. 
 
 Abstracts of tables, 6-16. 
 Adhesion and cohesion, 149, 155. 
 Age, effect of, on cement, 11, 12, 108, 
 109. 
 
 Air, concrete kept in, 142, 143. 
 Aird, jun., John, remarks, 68. 
 Albert Embankment concrete, 118. 
 Ashlar, 53. 
 
 Ballast in concrete, 17, 138-143, 160- 
 164. 
 
 Bateman, J. F., remarks, 85. 
 Baynes, Carleton, remarks, 61. 
 Bazalgette, J. W., remarks, 63, 154. 
 Be'ton, 49, 95-97. 
 Betons agglomeres, 119. 
 Bevan, Thomas, remarks, 71. 
 Blocks, concrete, 85, 116, 138-143. 
 Blue bricks, strength of, 35, 37. 
 Blue lias lime concrete, 47. 
 Bramley Fall stone, 14, 38, 43. 
 Bramwell, F. J., remarks, 78, 153. 
 Brereton, K. P., remarks, 86. 
 Bricks, cement, crushing strength of, 
 
 13, 34, 115, 128, 137. 
 
 , strength of, 13, 35-38, 115, 128. 
 
 Brickwork and cement, strength of, 47, 
 
 126, 127. 
 
 blocks, quantities of cement for, 
 
 39. 
 
 — for tidal work, 66. 
 
 Bridge cylinders, concrete in, 68, 69, 86. 
 
 Briquettes, concrete, 146. 
 
 Cement bricks, 130-137. 
 , cost of, 3. 
 
 , effect of age on, 11, 108, 122, 123, 
 
 125. 
 
 , mode of testing, 2, 110-114. 
 
 in sewers, 19-21, 117, 119. 
 
 Cements, tensile strains on, 40-45. 
 
 , London Main Drainage, 116. 
 
 Chalk for Portland cement, 4, 72, 81, 
 151. 
 
 Chemical tests, 168, 169. 
 
 Clay for Portland cement, 4, 72, 151. 
 
 bricks, strength of, 37. 
 
 Cohesion and adhesion, 149, 
 Concrete blocks, 87, 88, 95, 138-143. 
 
 briquettes, 146. 
 
 , cost of, 103. 
 
 in bridge cylinders, 68. 
 
 for foundations, 86, 87. 
 
 — — for quay walls, 85. 
 
 in air and in water, 142, 143. 
 
 , Eegistration form for tests, 113. 
 
 sewers, 19-21, 117, 119, 144-148. 
 
 , use of, under water, 65, 68. 
 
 specification, Suez Canal, 74, 
 
 75. 
 
 , strength of, 47, 116. 
 
 Coode, John, remarks, 87. 
 Cost of cement, 3. 
 
 of concrete, 103. 
 
 of testing cement, 5. 
 
 Crossness Works, cement tests, 41, 42. 
 Curtis, Cockburn, remarks, 76. 
 
 Dines, G., remarks, 69. 
 Dock wall, concrete for, 162. 
 Druce, E., remarks, 51, 93. 
 
vi 
 
 INDEX. 
 
 Embankment, Albert, concrete at, 118. 
 Exbury bricks, strength of, 38. 
 Experiments, mode of conducting, 3, 
 110-114. 
 
 Fine grinding, importance of, 6. 
 Firebricks, strength of, 35, 37. 
 Flints in concrete, 139-143. 
 Form, tabular, for tests, 111-113. 
 Foundations in water, 86. 
 Fowler, John, remarks, 104. 
 Fox, Sir Charles, remarks, 68. 
 Francis, 0. L., remarks, 62. 
 Fresh water, and cement, 13, 27, 
 Further experiments, 107. 
 
 Gatjlt bricks, strength of, 35, 36. 
 Glass in concrete, 139-143. 
 Granite and Portland stone compared, 
 89. 
 
 in concrete, 139-143. 
 
 , resistance to compression, 43. 
 
 Grant, John, remarks, 98, 149, 169-172. 
 Gravity, test by, 79. 
 
 Half-brick sewers, 144, 147. 
 Hand-mixed cement, 125. 
 Hartley, Sir Charles, remarks, 95. 
 Hawkshaw, John, remarks, 90. 
 Heavily burnt cement, 56-58, 62. 
 Heavy and light cement, 56-58, 62, 93. 
 Hemans, G. "W., remarks, 49. 
 Hydraulic limestone, 54. 
 lime mortar, 151. 
 
 Innbs, Lieut. W., remarks, 163. 
 
 Iron, action of Portland cement on, S3. 
 
 ships, Portland cement for, 70. 
 
 Jennings, Joseph, remarks, 70. 
 Jetties, construction of, 96. 
 Joints for tidal work, 66. 
 
 Keene's cement, experiments with, 13, 
 33, 46. 
 
 Kinipple, Mr., remarks, 65. 
 
 Lane, C. B., remarks, 77. 
 
 Latham, B., remarks, 168. 
 
 Lias lime, 92, 151. 
 
 lime concrete, 47. 
 
 lime and Portland cement com- 
 pared, 103. 
 
 Light and heavy cement, 93. 
 
 Lime concrete, 47, 152. 
 
 mortars and brick, 115. 
 
 Limestone, Halkin Mountain, 54. 
 
 Liverpool docks, mortar at, 53. 
 
 Loamy pit sand, experiments with, 8, 
 9, 24. 
 
 Longridge, J. A., remarks, 74. 
 
 Machine bricks, 37. 
 Machine-mixed cement, 125. 
 Manufacture of Portland cement, 4. 
 Marble, strength of, 69. 
 Maudslay, Henry, remarks, 70. 
 Medina and Portland cements mixed, 
 94. 
 
 cement, experiments with, 13, 33, 
 
 45, 46, 108, 123, 159, 160. 
 Metropolitan sewers, cements for, 1-4. 
 Mill-mix«d cements, 125. 
 Mortar, 54, 55, 152, 153, 163-168. 
 
 at Liverpool docks, 53. 
 
 , quantities used for, 39. 
 
 Moulds for testing cement, 2, 6, 109, 
 
 124, 149, 161. 
 
 Neat cement, strength of, 7, 9, 12, 17, 
 
 24, 26, 47, 114, 122, 130-135, 166, 
 167. 
 
 , strength in water, 17, 18, 
 
 25, 26, 40. 42. 
 
 Packing cement, 90, 158, 161. 
 Parian cement, experiments with, 13, 
 33, 45. 
 
 Parkes, W., remarks, 155. 
 Piers, use of Portland cement for, 49, 
 51. 
 
 , concrete for, 87, 88, 96. 
 
 Pit sand, experiments with, 8, 9, 24, 
 164. 
 
INDEX. 
 
 vn 
 
 Plaster of Paris in mortar, 152, 153. 
 Portland cement, 1. 
 
 and Medina cements mixed, 9i. 
 
 cement for sea walls and piers, 49. 
 
 manufacture, 4. 
 
 , neat, strength in water, 40, 
 
 42. 
 
 , resistance to pressm-e, 43. 
 
 , specification for, 2, 162. 
 
 stone and granite compared, 89. 
 
 , strength of, 14, 38, 43, 84. 
 
 Pottery in concrete, 139-143. 
 Pozzolana, 92, 95, 97, 153. 
 Preliminary experiments, 3. 
 Pressed bricks, strength of, 35-37. 
 
 Quantities of cement, &c., for brick- 
 work, 39. 
 Quay walls, concrete for, 85. 
 
 Kawxikson, Kobert, remarks, 52. 
 Kedman, J. B., remarks, 84. 
 Eeds, bricks, strength of, 35. 
 Kegister of Portland cement, form of, 
 48- 
 
 of experiments, 110-114. 
 
 Ee-mixing mortar, 149. 
 Eidley, T. D., remarks, 98. 
 Eoman cement, 1, 3, 108, 121, 159. 
 
 , experiments with, 13, 28-32, 
 
 44, 45, 122, 123. 
 Eosendale, American, cement, 149, 150. 
 Eubbers, bricks, strength of, 35. 
 
 Salmon bricks, strength of, 35. 
 Salt water, and cement, 13, 27, 74, 76, 
 87. 
 
 Samples, how collected, 2. 
 Sand and Portland cement, 7-9, 18, 26, 
 122, 130-137. 
 
 and Eoman cement, 29-32. 
 
 for cements, 50, 75, 76, 82, 83, 91. 
 
 , proportions of, 7-10. 
 
 Scott Eussell, Mr., remarks, 70. 
 . , Lieut.-Ool., remarks, 150-153. 
 
 Sea sand in mortar, 164. 
 
 walls, concrete or cement for, 49, 
 
 87-89, 94, 103. 
 Selenitic mortar, 153. 
 Sewers, concrete, 19-21, 117, 119, 144- 
 
 148. 
 
 , specification, 146-148. 
 
 Shingle for concrete, 71. 
 Ships, Portland cement for, 70. 
 Sicilian marble, strength of, 69. 
 Slag in concrete, 139-143. 
 Smiths' ashes in mortar, 164. 
 Southern outfall, cement tests, 41, 42. 
 Specification for Portland cement, 48, 
 147. 
 
 , concrete, Suez Canal, 74, 75. 
 
 , concrete sewers, 146-148. 
 
 Specific weight of cement, 55, 56, 79, 
 80. 
 
 Stocks, bricks, strength of, 35, 36. 
 Stone, strength of, 13, 14, 38, 43. 
 
 , Portland, in concrete, 139-143. 
 
 Storage of cement, 62. 
 Stucco, Portland cement for, 69. 
 Suez Canal, concrete specification, 74, 
 75. 
 
 Sufiblks, bricks, strength of, 35. 
 Summary of results, 14-16. 
 
 of tests, 128. 
 
 Supervision necessary, 5. 
 
 Tables, abstracts of, 6-16. 
 Tabular form for tests, 110-113. 
 Tensile strain, concrete briquettes, 
 146. 
 
 , Portland cement, 100-102, 
 
 156, 157. 
 
 , Portland cement and brick, 
 
 115. 
 
 strains of cements, 40-45. 
 
 Test-blocks, size of, 51. 
 Test-moulds, 2, 6, 109. 
 Testing machine, 2. 
 
 for small works, 4. 
 
 Tests, chemical, 169. 
 
 , summary of, 126. 
 
 Thames sand, experiments with, 7, 9, 
 18. 24, 26. 
 
Vlll 
 
 INDEX. 
 
 Tideways, cement in, 49-51, 66, 70, 84, 
 
 89-91, 95. 
 Towle, H. E., remarks, 149. 
 
 ViGKOLES, Mr., remarks, 76. 
 
 Washed sand, experiments with, 8. 
 Water, action on cement, 5. 
 
 for cement, 81, 82. 
 
 test for Portland cement, 102, 
 
 103. 
 
 Water test for Eoman cement, 122, 123. 
 
 for concrete, 142, 143. 
 
 Weight of Portland cement, 99, 101. 
 
 of experimental materials, 114. 
 
 , specific, of cements, 55-65, 120, 
 
 156, 157. 
 White, G. F., remarks, 55, 159. 
 Whites, bricks, strength of, 35. 
 
 YoBK stone, strength of, 14, 38, 43. 
 
EXPERIMENTS ON THE STRENGTH OF 
 CEMENT." 
 
 Since the formation of tlie Metropolitan Board of Works, about 
 ten years ago, the great system of drainage for the metropolis, 
 recently described in Mr. Bazalgette's Paper,^ has been designed 
 and executed. The Author, who superintended that portion of 
 the scheme which lies south of the Thames, believes that the 
 following description of the means adopted to ensure the use of 
 cement of the best quality only, in these works, may not be 
 without benefit or interest to the members. 
 
 Previous to 1859 Eoman cement was, with few exceptions, 
 the only cement used for the inverts of the London sewers, the 
 arches being set in blue lias lime, and Portland cement scarcely 
 ever tried. In view, however, of these large works, the Author, 
 about the end of the year 1858, commenced an extensive series 
 of experiments upon bricks, cements, and other materials. 
 Portland cement had, in this country, been chiefly confined to 
 ordinary building operations, such as external plastering, and to 
 some harbour works on the southern coast and in the Channel 
 Islands, where it was mostly used in the form of concrete 
 blocks. 
 
 In France, and in other parts of Europe, large harbour and 
 dock works had been constructed with Portland cement, made 
 in England, and the tests employed, which were generally of a 
 searching, though in some respects tedious, character, no doubt 
 
 ' The discussion upon tills Paper extended over portions of four evenings, but 
 an abstract of the whole is given consecutively. 
 2 Vide ' Minutes of Proceedings Inst. C.E.,' vol. xxiv. 
 
2 
 
 THE STBENGTH OF CEMENT. 
 
 prepared the principal manufacturers of this country for the 
 production of cement suitable for works like those then con- 
 templated for the drainage of London. 
 
 As a preliminary step, for the purpose of experiments, applica- 
 tions for samples were made to the leading manufacturers of 
 Portland'cement, and Tables I. II. III. and IV. of the Appendix 
 give the result of the tests to which they were subjected. The 
 names of the makers of these earlier samples have been omitted, 
 as it might be considered invidious to compare one producer with 
 another, especially as some of the samples forwarded for experi- 
 ment were, avowedly, specially prepared. Other specimens were 
 subsequently obtained from various makers, in the ordinary way, 
 without mentioning the purpose for which they were required ; 
 and the^results obtained, though they widely disagreed, were 
 sufiSciently satisfactory to warrant the insertion of the following 
 clause, in the specification for the Southern High-Level Sewer 
 (1859), being the first contract on the south side of the river 
 Thames : — 
 
 " The whole of the cement to be used in these works, and 
 referred to in this specification, is to be Portland cement, of the 
 very best quality, ground extremely fine, weighing not less than 
 110 lbs. to the striked bushel, and capable of maintaining a 
 breaking weight of 400 lbs. on an area 1^ inch x 1^ inch, equal 
 to 2|- square inches, seven days after being made in an iron 
 mould, of the form and dimensions shown on drawing No. 1 
 (Plate 2), and immersed six of these days in water." The 
 Board having adopted this test, attention was next turned to 
 devising some safe and ready mode of practically applying 
 it with accuracy. For this purpose, moulds were made of 
 bell-metal, having a sectional area, at the breaking point, of 
 1^ inch X 1^ inch = 2^ square inches, with templates of thin 
 iron, exactly fitting the mould, so that, with the aid of a simple 
 machine, the bricks could be pressed out shortly after the mould 
 had been filled. The machine devised for showing the tensile 
 strain was a lever balance (Plate 5), very accurately constructed 
 by Mr. P. Adie (Assoc. Inst. C.E.). The whole apparatus was 
 fixed in testing houses on the works, and access to these premises 
 could only be obtained through the proper officers. The 
 machines used for testing have since, in several cases, been 
 adopted by the manufacturers at their own works, an acknow- 
 
THE STKENGTH OF CEMENT. 
 
 3 
 
 ledgment of the soundness of the principle, and of its adapt- 
 ability to the requirements of this manufacture. No difficulty- 
 was experienced in training an ordinary workman to test the 
 cement by means of these machines ; and after using, during 
 the last six years, more than 70,000 tons of Portland cement, 
 which has been submitted to about 15,000 tests, it can be 
 confidently asserted, that none of an inferior or dangerous 
 character has been employed in any part of the works in 
 question. 
 
 In the construction of branch sewers it has, in many cases, 
 been necessary to cut through main sewers, and specimens of 
 the materials are submitted, to show the perfect adhesion 
 between the bricks and the cement. 
 
 During the preliminary experiments objection was taken to 
 the standard then proposed, and afterwards adopted, and it was 
 strongly urged that a standard of 300 lbs., instead of 400 lbs., 
 would be found, in practice, to be the highest attainable. But, 
 fortunately for the cement trade itself, not only was the higher 
 standard established, but, in subsequent specifications, it was 
 increased. After the first start, little difficulty was experienced 
 in obtaining Portland cement of standard quality. A few of the 
 earliest deliveries were rejected, but subsequently the makers 
 of them regained their position ; and the Author feels bound to 
 express his thanks to those who so materially assisted, by the 
 excellence of their manufacture, in obtaining such satisfactory 
 results. While aiming at a high quality of cement, the necessity 
 of sufficiently remunerating the manufacturer was not lost sight 
 of ; and, in the first schedule of prices, 2s. dd. per bushel was 
 the price inserted. This, however, is much above its present 
 market value. 
 
 Though the use of Portland cement had been comparatively 
 limited, the extensive adoption of this material in the construc- 
 tion of the metropolitan sewers drew the attention of engineers 
 and contractors to its value and importance ; and it may be 
 safely assumed, that during the progress of these works double 
 the quantity of this cement has been used in London which has 
 ever been employed, in the same time, since its first introduc- 
 tion or discovery. 
 
 Koman cement is, under certain conditions, useful, but in 
 works of importance, even with the adoption of precautionary 
 
 B 2 
 
4 
 
 THE STEENGTH OF CEMENT. 
 
 measures to ensure purity and freshness, its strength is much 
 inferior to Portland cement. Besides its inherently weaker 
 character, Eoman cement has the great practical disadvantage 
 of losing its strength by being kept long before use, or by 
 being exposed to the air ; whereas Portland cement improves 
 by being kept and by exposure to the air, provided it be 
 kept dry. 
 
 No reference will be made in this Paper to the chemical 
 properties of Portland cement, or to any theories as to the 
 admixture, in its manufacture, of one material with another in 
 various proportions. These points have already been so fully 
 treated by Members of the Institution and by different foreign 
 authors, as to have rendered familiar at least the prominent 
 features of limes and cements. 
 
 The manufacture of Portland cement is not one of complex 
 character, although it requires the exercise of extreme care in 
 the admixture of its two simple and well-known ingredients, 
 clay and chalk. This cement is almost solely manufactured on 
 the rivers Thames and Medway, and the clay is obtained from 
 the creeks and bays between Slieerness and Maidstone. Much 
 care is required in the selection of the clay, so that it shall be 
 as free from sand as possible ; and the proportion in which it 
 is used depends altogether on the quality of the chalk with 
 which it is to be incorporated. In the white chalk districts 
 the clay forms from 25 per cent, to 30 per cent, of the whole 
 bulk, and in the grey chalk districts the proportion of clay 
 varies from 16 per cent, to 20 per cent. Both districts have 
 contributed to the satisfactory results recorded in the accom- 
 panying Tables. 
 
 Experience in the daily use of Portland cement has enabled 
 the clerks of the works and others to judge, generally by colour 
 and by weight, of its quality ; and many of the bricklayers who 
 have been employed on these works, and who had previously a 
 very imperfect acquaintance with this cement, or with its peculiar 
 properties, have now acquired confidence and experience in using 
 it, which will be valuable hereafter on other works upon which 
 they may be engaged. It is not to be expected that, in ordinary 
 small building operations, the necessary testing, though simple 
 and inexpensive, will be maintained. In such cases the pre- 
 caution must be taken of employing respectable manufacturers. 
 
THE STKENGTH OF CEMENT. 
 
 5 
 
 who have the means of thoroughly testing the cement made by 
 them, and who can confidently guarantee its quality. If proper 
 care had been exercised, many buildings would have been saved 
 the disfigurement caused by the blowing or cracking of the 
 cement with which they are covered. In all works of magni- 
 tude, engineers and architects should insist upon the cement 
 being thoroughly tested before being used. To do so no great 
 expense need be incurred ; for the first cost of one of the 
 machines is about 501., and the annual charge for labour about 
 80Z. The whole expense of testing the cement used in these 
 works, which extend over a district eighteen miles in length, 
 and cost upwards of 1,250, OOOZ., has only been about five 
 farthings per ton of cement ; an utterly insignificant cost, when 
 compared with the great advantages gained in quality and 
 in soundness of work. 
 
 It was at first intended that the tests should be confined to 
 the simple requirements of the works, and it was not contem- 
 plated further to extend the observations and experiments. The 
 facilities, however, which were afforded for the successful inves- 
 tigation of so interesting and useful a subject, induced the 
 Author not only to keep an accurate record of all the ordinary 
 tests, but to extend his inquiry into other points, the results of 
 which are shown in No. XVI. and following Tables. 
 
 Although the testing apparatus will indicate the strength of 
 the cements-, it must not be inferred that it renders unnecessary 
 all supervision afterwards. Among the more important points 
 requiring attention are, the quality of the sand to be mixed with 
 the cement, and the thorough saturation of the bricks, so that, 
 in setting the cement may not be robbed, by absorption, of the 
 moisture necessary for its perfect hardening. Instances have 
 occasionally occurred where, in consequence of negligence on 
 the part of the workmen, imperfect adhesion of the cement to 
 the bricks has resulted. Great care is also necessary to prevent 
 any current of water from passing over the cement, or through 
 the joints, during the process of setting, as this would wash 
 away the soluble silicates, which form a necessary element in 
 the cement. The drainage works were protected from this 
 danger by stoneware pipes laid under the invert of the sewer, 
 so as to carry off the water while the brickwork was in progress. 
 In concrete this must be specially guarded against, although 
 
6 
 
 THE STEENGTH OF CEMENT. 
 
 the risk would be much reduced by the use of a cement of less 
 specific gravity, which would set more quickly. In some cases 
 even Eoman cement could be advantageously employed for 
 such purposes. 
 
 Tables I. II. III. and lY. may be considered the first of the 
 series, and their only value consists in showing how precarious 
 and irregular the quality of Portland cement was at that time. 
 Some of the irregularity in the results may be attributed to the 
 imperfect apparatus used at that early stage ; but this was 
 of course avoided subsequently by the adoption of the new 
 apparatus. 
 
 Tables I. II. and III. show an average weight of 108 ' 6 lbs. 
 
 per bushel, and an average breaking, or tensile strain, varying 
 from 75 lbs. to 719 lbs. on 2^ square inches. The adoption of 
 this particular size was, to some extent, obligatory, from its 
 being the only known form of mould in use. It is intended, 
 however, to substitute a mould with sectional area of 4 square 
 inches (Plate 3), and of a somewhat different form.^ 
 
 The importance of having the cement finely ground was 
 shown very early in these experiments ; and there can be no 
 doubt that much of the difference in these first results is attri- 
 butable to the several samples varying greatly in this respect. 
 At the same time, it was also manifest that the cement, when 
 carefully moistened, and only supplied with sufficient water to 
 reduce it to a state of paste, gave better results than when 
 unduly charged with water. The best method for applying 
 water is by a perforated nozzle at the end of a pipe or watering- 
 can. It should be stated that in every case the shape and 
 sectional area of the mould were the same, viz. 1^ inch x 1^ 
 inch = 2|- square inches. Where not otherwise stated, the 
 samples were immersed in water from the time of setting to 
 the time of testing ; and the results are, as a rule, the average 
 of ten tests. Whilst setting, each sample was numbered at 
 both ends, and recorded in duplicate, in registers, of which the 
 form is given in the Appendix. 
 
 The means adopted to obtain accurate results having been 
 described, and reference having been made to the earlier of 
 
 1 Later experience has shown that the original size, with form slightly modified, 
 is preferable. — J. G. 
 
THE STRENGTH OF CEMENT. 
 
 these, as set forth in Tables I. to IV., attention will nowBS= 
 drawn to Tables V. to XV. inclusive, which give the strength, 
 as tested by tensile strain, of 1,369,210 bushels of the Portland 
 cement used in the drainage works on the south side of the 
 Thames, between the years 1859 and 1865. 
 
 These Tables, of which V. and VI. are summaries, give the 
 names of the manufacturers, the quantity supplied by each, 
 theT weight per bushel, the average breaking weight, and the 
 specified standard. The tests have been 11,587 in number, and 
 the general results are, that the cement supplied to these works 
 has weighed, on an average, 114-15 lbs. per bushel, and has 
 borne a tensile strain of 606 • 8 lbs., equal to 270 lbs. per square 
 inch ; whilst the specifications required a weight of 110 lbs. 
 per bushel, and a tensile strength of 400 lbs. in the first instance, 
 and afterwards of 500 lbs. Thus the cement has been 51^ 
 per cent, above proof, in the first case, and 21 per cent, in the 
 second. 
 
 Besides these daily tests of the strength of the cement sup- 
 plied for the works, further experiments were made on the 
 strength of cement by itself, and with difierent proportions and 
 different kinds of sand, at periods varying from one week to 
 twelve months. 
 
 Table XVI. gives the results of 370 experiments with Port- 
 land cement, weighing 112 lbs. to the imperial bushel, gauged 
 neat, and with different proportions of various kinds of sand. 
 The neat cement bore, at the end of a week, 558*5 lbs. ; at the 
 end of twenty-eight days, 784 • 5 lbs. ; at the end of six months, 
 960*8 lbs.; and at the end of twelve months, 1009*8 lbs. 
 Mixed with an equal proportion of clean Thames sand, the 
 breaking weight, at the end of a week, was 190*7 lbs.; at 
 twenty-eight days, 373 * 5 lbs. ; at six months, 603 * 2 lbs. ; and 
 at twelve months, 724 lbs. It will be observed that at the end 
 of a week the strength is only 34 * 1 per cent, of neat cement ; 
 at the end of a month, 47 * 6 per cent. ; at six months, 62 * 8 
 per cent. ; and at twelve months, 71 * 7 per cent. When mixed 
 with Thames sand, in the proportion of 1 of cement to 3 of sand, 
 the breaking weights were, respectively, 62 lbs., 108 lbs., 
 308 * 1 lbs., and 371 * 1 lbs., at the end of a week, one month, six 
 months, and twelve months ; that is, 11 * 1, 13 * 8, 32 * 1, and 36 * 7 
 per cent, of the strength of neat cement. When mixed with 
 
8 
 
 THE STRENGTH OF CEMENT. 
 
 the same sand, in the proportion of 1 to 4, the breaking weights 
 at one month, six months, and twelve months respectively were 
 90 -5 lbs., 149 lbs., 198-2 lbs.; or, 11-54, 15-5, and 19-62 per 
 cent, of the strength of neat cement. When mixed with the 
 same sand, in the proportion of 1 to 5, the breaking weights 
 were 43 lbs. at one month, 122-5 lbs. at six months, and 
 204-4 lbs. at twelve months; or, 5-48, 12-75, and 20-24 per 
 cent, of neat cement. The next column gives the breaking 
 weight of the same cement mixed with another sample of 
 Thames sand, in equal proportions. The results were 213-1 lbs. 
 at a week, 418 lbs. at a month, 614 ■ 5 lbs. at six months, and 
 757 - 9 lbs. at twelve months ; or, from 2 per cent, to 12 per 
 cent, more than in the first case. The next two columns give 
 the breaking weight of the same cement, when mixed with very 
 clean pit sand, taken from the excavations. These results were 
 somewhat higher than with either of the samples of Thames 
 sand, being with a proportion of 1 to 1227-8 lbs. at a week, 
 423 - 1 lbs. at a month, 625-9 lbs. at six months, and 815-4 lbs. 
 at twelve months. The last being 12 • 6 per cent, above the first, 
 and 7 * 71 per cent, above the second sample of Thames sand. 
 The next two columns give the breaking weight of the same 
 cement, with an inferior, or loamy pit sand, in the proportion of 
 1 to 1. The strength, at a week, was 166 - 8 lbs., and at a month 
 376 ' 9 lbs. ; the latter being very nearly the same as the first 
 sample of Thames sand = 373 - 5 lbs. When mixed with 2 
 parts of sand, the breaking weight, at a month, was 251 - 5 lbs., 
 or 11*4 per cent, above the first-mentioned Thames sand. The 
 last two columns show the breaking weight of the same cement 
 when mixed with an equal quantity of the last-mentioned pit 
 sand, washed ; the result being 223 - 9 lbs. at a week, and 
 364-9 lbs. at a month. The washing of the sand seems to add 
 about 35 per cent, to the strength at the end of a week ; but at 
 the end of a month this experiment is not so satisfactory. With 
 washed pit sand, in the proportion of 1 of cement to 2 of sand, 
 the breaking weight, at twenty-eight days, was 330 lbs., or 
 46 - 2 per cent, above the first specimen of Thames sand, or 31 - 21 
 per cent, above the same sand, when not washed. 
 
 Table XVII. gives the results of 960 experiments as to the 
 breaking weight of Portland cement weighing 112 lbs. to the 
 bushel, gauged neat, and also with different proportions of 
 
THE STEENGTH OF CEMENT. 
 
 9 
 
 Thames, clean pit, and loamy sands, 
 cement bore : — 
 
 When gauged neat the 
 
 1 week . 
 1 month 
 3 months 
 6 „ 
 9 „ 
 12 „ 
 
 lbs. 
 
 445-0 
 679-9 
 877 
 978 
 995 
 1075 
 
 Thus in three months the cement bore about double the 
 strain it did at the end of a week, and at the end of twelve 
 months, 241 • 70 per cent., or nearly twice and a half the strain 
 that it bore at the end of a week. These results agree, in the 
 main, with those of the last Table, although the cement seems 
 to have been somewhat slower in setting, breaking at 445 lbs. 
 against 558 • 5 lbs. at the end of a week ; but overtaking the first 
 set at the end of six months, and at twelve months being 
 1075 • 7 lbs. against 1009 - 8 lbs., or having 6 • 5 per cent, greater 
 strength. The next five columns give the breaking weights of 
 the same cement mixed with clean, sharp, Thames sand, in 
 proportions varying from 1 to 1, to 1 to 5. 
 
 When mixed with an equal proportion of sand, the breaking 
 weights are at : — 
 
 lbs. 
 97-0 
 
 Per cent, of the strength 
 of neat Cement. 
 
 1 
 1 
 
 3 
 6 
 9 
 
 12 
 
 week 
 month 
 months 
 
 309-3 
 367-0 
 546-8 
 607-8 
 700-3 
 
 21 
 44 
 41 
 
 55' 
 
 61 
 
 65 
 
 When mixed with twice the proportion of sand, the breaking 
 weights are at : — 
 
 lbs. 
 
 1 week . 
 1 month 
 3 months 
 6 „ . 
 
 9 „ ■ 
 12 „ . 
 
 Per cent, of the strength 
 of neat Cement. 
 
 52-5 = 11-80 
 
 123-5 = 18-16 
 
 254-5 = 29-00 
 
 425-1 = 43-46 
 
 431-5 = 43-33 
 
 458-5 = 42-62 
 
10 
 
 THE STBENGTH OF CEMENT. 
 
 When mixed in the proportion of 1 of cement to 3 of sand, 
 the breaking weights are at : — 
 
 1 week . 
 1 month 
 3 months 
 
 6 „ . 
 12 „ . 
 
 lbs. 
 
 27-0 
 58-0 
 135-5 
 232-4 
 
 320-6 = 
 
 Per cent, of the strength 
 of neat Cement. 
 
 6-07 
 8-53 
 = 15-43 
 = 23-74 
 29-90 
 
 When mixed in the proportion of 1 of cement to 4 of sand, 
 the breaking weights are at : — 
 
 lbs. 
 
 1 month 32-5 
 
 3 months 109 • 0 
 
 6 „ 1570 
 
 12 „ 221-6 
 
 When mixed in the proportion of 1 of cement to 5 of sand, 
 the breaking weights are at : — 
 
 lbs. 
 
 1 month 21-0 
 
 3 months 88-5 
 
 6 „ . . 95-5 
 
 12 „ 122-3 
 
 The next five columns show the breaking weights of the same 
 cement, mixed with similar proportions of clean pit sand taken 
 from the excavations. The strength is, in every case, much 
 greater than in the corresponding columns just described, where 
 Thames sand was used. The succeeding five columns, giving 
 similar particulars with a loamy pit sand, correspond more with 
 the first five, where Thames sand was used, and show the im- 
 portance of attending to the quality of the sand, especially 
 where the proportions of sand vary. Looking down the three 
 columns which give the breaking weights with equal propor- 
 tions of cement and sand, it will be perceived that the strength 
 rapidly gains in proportion upon that of the neat cement. 
 Thus, in the first case, that which was only 21 - 8 per cent, at 
 
THE STEENGTH OF CEMENT. 
 
 11 
 
 the end of a week, and 45 • 5 per cent, at the end of a month, 
 at the end of the year has increased to 65-1 per cent, of the 
 strength of neat cement. With clean pit sand the corre- 
 sponding column 1 to 1 shows that the gain is much greater, 
 increasing from 34-2 per cent, at the end of a week, to 74-0 
 per cent, at the end of a year. Again, if the breaking weights 
 at twelve months, in the three sets of columns for the propor- 
 tions of cement to sand of 1 to 2, 1 to 3, and 1 to 4, are mul- 
 tiplied by 2, 3, and 4 respectively, on the average it will be 
 found that the normal strength of the neat cement (1075 -7 lbs.) 
 is, as nearly as possible, diluted in proportion to the quantity of 
 sand, the average numbers being 1066 'libs., 1103 -4 lbs., and 
 1044 -8 lbs. This, however, does not hold good with the pro- 
 portion of 5 of sand to 1 of cement, except where the sand is 
 purest ; the strength at the end of twelve months, multiplied as 
 before by 5, being 611-5 for Thames sand, 1078 for clean pit 
 sand, and 831 for loamy pit sand, against 1075*7, the normal 
 strength of the neat cement. 
 
 The foregoing experiments, extending only to twelve months, 
 still left some interesting points unsettled ; as, for instance, the 
 age at which cement, whether neat or mixed with sand, ceases 
 to increase in strength ; the age at which the several com- 
 pounds of cement and sand approach nearest to the normal 
 strength of neat cement, or, in other words, obtain their maxi- 
 mum strength ; also, the most economical proportion of cement 
 and sand, with an assumed minimum strength. The last point 
 has been approximately ascertained by the Table just referred 
 to, inasmuch as it has been shown that with sand in the pro- 
 portion of 2, 3, and 4 to 1 of cement, the sand simply acts as a 
 diluting agent ; but with sand in the proportion of 5 to 1 of 
 cement, any imperfection in the sand materially affects the 
 strength of the compound. Thus it is only with clean pit sand 
 that the full strength of the cement is obtained ; the strength, 
 215-6, multiplied by 5, gives 1078 lbs. against 1075 '7 lbs., the 
 strength of the neat cement. 
 
 With the view of ascertaining, if possible, the age at which 
 cement mixed neat and with sand attains its greatest strength, 
 another series of 300 experiments, intended to extend over 
 ten years, was commenced, but at present only those for the 
 first three years, 160 in number, can be given (Table XVIII.). 
 
12 
 
 THE STRENGTH OF CEMENT. 
 
 The cement in this case weighed 123 lbs. per imperial bushel. 
 The breaking weights of the neat cement are at:— 
 
 lbs. 
 
 817-1 
 935-8 
 1055-9 
 1176-6 
 1219-5 
 1229-7 
 1324-9 
 1314-4 
 
 The same cement when mixed with an equal proportion of 
 Thames sand broke at the following weights : — 
 
 lljg Per cent, of neat 
 
 Cement. 
 
 1 week 353-2 = 40 78 
 
 1 month 452-5 = 48-35 
 
 3 months .. .. 547-5 = 51-85 
 
 6 „ 640-3 = 54-42 
 
 9 « 692-4 = 56-77 
 
 12 „ 716-6 = 58-27 
 
 2 years 790-3 = 59-65 
 
 3 » 784-7 = 59-70 
 
 The proportionate strength of cement and sand increases, it 
 will be perceived, between three months and twelve months, at 
 the rate of 2 per cent, every three months, but in the course of 
 the second year only 1-38 per cent, per annum. In the third 
 year there is no increase. 
 
 Table XIX. gives the result of 225 experiments, made with 
 cement gauged neat and kept for periods varying from seven 
 days to twelve months, first, in water ; secondly, out of water, 
 in-doors ; and thirdly, out of water, exposed to the action of 
 the weather. At the end of twelve months the results are 
 respectively as 1099, 827-4 and 719-6; that is to say, the 
 cement which was kept out of water in-doors attained only 
 75 - 29 per cent, of the strength of that which was kept in water ; 
 while that which was out of water, and exposed out of doors', 
 acquired only 65-48 per cent. As there are considerable 
 
 1 month 
 3 months 
 6 „ 
 
 9 „ 
 12 „ 
 
 2 years , 
 
 3 . 
 
THE STEENGTH OF CEMENT. 
 
 13 
 
 variations in the apparent strength at different ages, if the 
 averages are taken, they are as 100, 80 • 64, and 76 • 8. Cement 
 allowed to set under water seems, from these experiments, to 
 gain strength from 24 per cent, to 30 per cent. 
 
 Tables XX. and XXI. give the relative strength of cement 
 gauged with fresh water and with salt water, at various ages, 
 from a week to five months. The difference, though not very 
 material, is in favour of salt water. This is satisfactory, as 
 in the case of harbours, docks, and piers, where the water is 
 either salt or brackish, there need be no hesitation in using 
 salt water, either in making Portland cement concrete or in 
 building. 
 
 Tables XXII. to XXYII. inclusive show the results of 685 
 experiments made with Koman cement. The only inferences 
 to be drawn from these are, that the best Koman cement is very 
 inferior to Portland, especially when mixed with sand. 
 
 Table XXVIII. gives the strength of Keene's cement and 
 Parian cement, in water and out of water, for periods varying 
 •from seven days to three months. At three months the 
 strength of Keene's cement in water is 508*8 lbs. ; out of 
 water, 720 • 5 lbs. ; or 41 per cent. more. Parian cement in 
 water, 521 lbs. ; out of water, 853 '7 lbs. ; or 64 per cent. more. 
 
 Table XXIX. gives the strength of Medina cement at various 
 periods, from seven days to two years, the increase being from 
 211 lbs. at seven days, to 476 '9 lbs. in twelve months, and 
 276 lbs. in two years. There is a great falling off in the second 
 year. 
 
 These three cements have only been used for internal archi- 
 tectural purposes. 
 
 Table XXX. gives the number of tons required to crush 
 bricks made of Portland cement neat, and with five different 
 proportions of sand at three, six, and at nine months, at which 
 different periods the strength of the neat cement bricks was 
 65 tons, 92 tons, and 102 tons respectively, or more than that 
 of Staffordshire blue bricks. Bricks made of a mixture of sand 
 with cement, in the proportions of 4 to 1 and 5 to 1, stand a 
 pressure equal to the best stock bricks. 
 
 Tables XXXL to XXXIV. give the results of about 300 ex- 
 periments on the strength of different kinds of bricks. 
 
 Table XXXV. shows the strength of blocks of Portland, 
 
14 
 
 THE STEENGTH OF CEMENT. 
 
 Bramley Fall stone, and York stone landings, of the same size 
 as an average brick. Portland stone, on its bed, bears a crusli- 
 ing weight of 47 tons, on an area of about 40 square inches, 
 equal to 2631 lbs. per inch ; and against its bed it bears 
 somewhat less. Bramley Fall, on its bed, bears 91^ tons, equal 
 to 5122 lbs. per square inch, or nearly double that of Portland ; 
 and against its bed it bears 52| tons, or 2953 lbs. per square 
 inch. 
 
 The following is a recapitulation of the results of the tests 
 and experiments shown in the annexed Tables, and of such facts 
 as have come under observation : — 
 
 1st. The earlier experiments, made six years ago (Tables I. 
 to lY.), gave, at the end of a month, a breaking weight varying 
 from 75 lbs. to 719 lbs. on an area of 2^ square inches. 
 
 2nd. A minimum test of at first 400 lbs., and afterwards of 
 500 lbs., was specified. 
 
 3rd. During six years the average strength of 1,369,210 
 bushels used in the Southern Main Drainage works has been 
 606-8 lbs. (Tables V. and VI.), being 52 per cent, above the 
 standard first specified, and 21 per cent, above that subse- 
 quently adopted. 
 
 4th. The average weight per bushel has been 114*15 lbs., 
 being 4 • 15 per cent, above the specified standard. 
 
 5th. Portland cement has been proved to be peculiarly suit- 
 able for hydraulic works, and may be procured in any quantity, 
 and of the highest quality. 
 
 6th. Portland cement, if it be preserved from moisture, does 
 not, like Eoman cement, lose its strength by being kept in 
 casks or sacks, but rather improves by age ; a great advantage 
 in the case of cement which has to be exported. 
 
 7th. The longer it is in setting, the more its strength in- 
 creases. (Tables XVIII. and XIX.) 
 
 8th. Neat cement is stronger than any admixture of it with 
 sand. 
 
 9th. Cement mixed with an equal quantity of sand (as has 
 been the case throughout the Southern Main Drainage works), 
 may be said to be, at the end of a year, approximately three- 
 fourths of the strength of neat cement. 
 
 10th. Mixed with 2 parts of sand it is half the strength of 
 neat cement. 
 
THE STRENGTH OP CEMENT. 
 
 15 
 
 11th. With 3 parts of sand the strength is a third of neat 
 cement. 
 
 12th. With 4 parts of sand the strength is a fourth of neat 
 cement. 
 
 13th. With 5 parts of sand the strength is about a sixth of 
 neat cement. (Table XVII.) 
 
 14th. The cleaner and sharper the sand, the greater the 
 strength. 
 
 15th. Very strong Portland cement is heavy, of a blue-grey 
 colour, and sets slowly. Quick-setting cement has generally 
 too large a proportion of clay in its composition, is brownish in 
 colour, and turns out weak, if not useless. 
 
 16th. The stiffer the cement mortar, that is, the less the 
 amount of water used in working it up, the better. 
 
 17th. It is of the greatest importance that the bricks or 
 stone with which Portland cement is used should be thoroughly 
 soaked with water. If under water in a quiescent state, the 
 cement will be stronger than out of water. Table XIX. shows 
 that cement kept in water was one-third stronger than that 
 kept out. 
 
 18th. Blocks of brickwork or concrete made with Portland 
 cement, if kept under water till required for use would be 
 much stronger than if kept dry. 
 
 19th. Salt water is as safe for mixing with Portland cement 
 as fresh water. 
 
 20th. Bricks made with neat Portland cement are as strong 
 at from six months to nine months as the best quality of Staf- 
 fordshire blue bricks, or similar blocks of Bramley Fall stone 
 or Yorkshire landings. 
 
 21st. Bricks made of 4 parts or 5 parts of sand to 1 part of 
 Portland cement will bear a pressure equal to the best picked 
 stocks. 
 
 22nd. Portland cement concrete, made in the proportions of 
 1 of cement to 8 of ballast, in some cases, and of 1 to 6 in others, 
 has been extensively used for the foundations of the river wall, 
 piers of reservoirs, and foundations generally, at Crossness and 
 Deptford, with the most perfect success ; and it is believed that 
 it might be much more extensively used as a substitute for 
 brickwork or masonry wherever skilled labour, stone, or bricks 
 are scarce, and foundations are wanted at the least expenditure 
 of time or money. 
 
16 
 
 THE STBENGTH OF CEMENT. 
 
 23rd. Wherever concrete is used under water, care must be 
 taken that the water is still ; as otherwise a current, whether 
 natural or caused by pumping, will carry away the cement and 
 leave only the clean ballast. 
 
 24th. Boman cement, though about two-thirds the cost of 
 Portland, is only about one-third its strength, and is therefore 
 double the cost, measured by strength. 
 
 25th. Eoman cement is very ill adapted for mixing with 
 sand. 
 
 In conclusion, whilst recommending Portland cement as the 
 best article of the kind that can be used by the Engineer or 
 the Architect, the Author would warn anyone against its use 
 who is not prepared to take the trouble or incur the trifling 
 expense of testing it ; as if manufactured with improper propor- 
 tions of its constituents — chalk and clay — or improperly burnt, 
 it may do more mischief than the poorest lime. 
 
 Further experiments are desirable on the strength of adhesion 
 betw^een bricks and cement under varying circumstances ; on 
 the limit to the increase of strength with age ; on the relative 
 strength of concrete made with various proportions of cement 
 and ballast ; and on the use of cement in very hot climates, 
 where, probably, extra care will be required in preserving the 
 cement from damp, and in keeping it cool, until the process of 
 setting has been completed. On these and other points it is 
 trusted that all who have the opportunity will make a record of 
 their observations, for presentation to the Institution. Great 
 credit is due to those manufacturers who have produced the 
 high quality of cement (from 20 per cent, to 50 per cent, above 
 the specified strength), shown in Table VI. 
 
THE STRENGTH OF CEMENT. 
 
 17 
 
 APPENDIX. 
 
 Table I. 
 
 Abstbact of 70 Experiments with Portland Cement, mixed neat, and im- 
 mersed in water, for seven and fourteen days. January, 1859. 
 
 Manufacturer. 
 
 A 
 B 
 0 
 
 D 
 
 E 
 F 
 G 
 H 
 I 
 
 Average 
 
 Weight 
 
 per 
 Bushel. 
 
 Ihs. 
 113 
 109 
 112 
 112 
 103 
 110 
 110 
 109 
 106 
 83 
 
 106-7 
 
 In Moulds 7 Days. 
 
 No. of 
 Experi- 
 ments. 
 
 38 
 
 Average 
 Brealcing 
 'J'ests.i 
 
 lbs. 
 663 
 335 
 518 
 397 
 373 
 371 
 299 
 299 
 294 
 215 
 
 354-61 
 
 In Moulds 14 Days. 
 
 No. of 
 Experi- 
 ments. 
 
 32 
 
 Average 
 
 Tests. 1 
 
 lbs, 
 691 
 525 
 502 
 485 
 464 
 465 
 355 
 334 
 313 
 
 462-5 
 
 Table II. 
 
 Table of the Eesnlts of 200 Experiments with Portland Cement, mixed neat, 
 and immersed in water for seven days, made between 12th April and 4th 
 July, 1859. 
 
 
 Weight 
 
 Breaking Tests, i 
 
 
 
 
 
 Manufacturer. 
 
 per 
 
 
 
 
 
 Bushel. 
 
 Minimum. 
 
 Maximum. 
 
 Average. 
 
 
 lbs. 
 
 lbs. 
 
 lbs. 
 
 lbs. 
 
 K 
 
 120 
 
 313 
 
 719 
 
 526-75 
 
 0 
 
 116 
 
 327 
 
 509 
 
 417-50 
 
 A 
 
 105 
 
 327 
 
 481 
 
 395-90 
 
 G 
 
 109 
 
 187 
 
 472 
 
 370-15 
 
 D 
 
 110 
 
 187 
 
 478 
 
 360-40 
 
 J 
 
 106 
 
 187 
 
 439 
 
 328-15 
 
 B 
 
 105 
 
 131 
 
 383 
 
 318-90 
 
 H 
 
 107 
 
 75 
 
 540 
 
 315-80 
 
 E 
 
 102 
 
 75 
 
 404 
 
 251-70 
 
 F 
 
 96 
 
 175 
 
 318 
 
 237-50 
 
 Average . . 
 
 107-6 
 
 198-4 
 
 474-3 
 
 352-27 
 
 1 Sectional area, 2-25 square inches. 
 
 0 
 
18 
 
 THE STEENGTH OP CEMENT. 
 
 Table III. 
 
 Table of the Results of 17 Experiments with Portland Cement, mixed neat, 
 and immersed in water for seven days. March, 1859, 
 
 MAlTOFACltrEER. 
 
 No. of 
 Experi- 
 ments. 
 
 Weight 
 
 per 
 Bushel. 
 
 Breaking Tests.' 
 
 Minimum. 
 
 Maximum. 
 
 Average. 
 
 
 
 lbs. 
 
 lbs. 
 
 lbs. 
 
 lbs. 
 
 K 
 
 2 
 
 120 
 
 635 
 
 719 
 
 677-0 
 
 !> 
 
 2 
 
 104 
 
 509 
 
 546 
 
 527-5 
 
 D 
 
 3 
 
 112 
 
 453 
 
 551 
 
 499-6 
 
 A 
 
 2 
 
 113 
 
 383 
 
 489 
 
 436-0 
 
 C 
 
 2 
 
 112 
 
 383 
 
 467 
 
 425-0 
 
 B 
 
 2 
 
 109 
 
 405 
 
 419 
 
 412-0 
 
 G 
 
 2 
 
 114 
 
 306 
 
 327 
 
 315-5 
 
 E 
 
 2 
 
 110 
 
 299 
 
 327 
 
 313-0 
 
 Average ,. 
 
 17 
 
 111-75 
 
 421 
 
 484 
 
 453-68 
 
 Table IV. 
 
 Table of the Eesults of 15 Experiments with Portland Cement, mixed with 
 an equal proportion of sand, and immersed in water for seven days. 3rd to 
 10th March, 1859. 
 
 Manupactuker. 
 
 No. of 
 Experi- 
 ments. 
 
 Weight 
 
 per 
 Bushel. 
 
 Breaking Test 
 
 3.1 
 
 Minimum. 
 
 Maximum. 
 
 Average. 
 
 
 
 lbs. 
 
 lbs. 
 
 lbs. 
 
 lbs. 
 
 A 
 
 3 
 
 113 
 
 387 
 
 398 
 
 392-0 
 
 0 
 
 3 
 
 112 
 
 173 
 
 187 
 
 182-3 
 
 E 
 
 3 
 
 110 
 
 159 
 
 198 
 
 177-3 
 
 B 
 
 3 
 
 109 
 
 145 
 
 173 
 
 163-6 
 
 D 
 
 3 
 
 112 
 
 117 
 
 131 
 
 121-6 
 
 Average .. 
 
 15 
 
 111-2 
 
 195-4 
 
 217-4 
 
 207-4 
 
 ' Sectional area, 2-25 square inches. 
 
THE STRENGTH OF CEMENT. 
 
 19 
 
 Table V. 
 
 METEOPOLITAN MAIN DRAINAGE. 
 Contracts on the South Side. 
 Summary of Tables VII. to XV. inclusive. 
 
 Portland Cement, Seven Day Tests, from 1859 to 1865. 
 
 Name of Contract. 
 
 Quantity 
 in 
 
 Busliels. 
 
 Average 
 Weight per 
 Bushel. 
 
 Number 
 
 of 
 Tests. 
 
 Average 
 Breaking 
 Tests.' 
 
 Specified 
 Standard 
 Test.3 
 
 SouthemHigli-Level Sewer^ (vn.) 
 St. George's Wharf (VIII.) 
 Southern Outfall Sewer^ (ix.) . . 
 Deptford Pumping Station (x.) 
 Southwark Improvement (xi.) . 
 Southern High-Level Exten-1 
 
 sions (xii.) / 
 
 Bermondsey Branch (xiii.) 
 Southern Outfall Works» (xiv.) 
 Southern Low-Level Sewer' (xv.) 
 
 Generally 
 
 148,728 
 6,791 
 
 391,405 
 83,714 
 39,212 
 
 50,443 
 
 78,492 
 349,620 
 220,805 
 
 lbs. 
 119-04 
 113-28 
 
 110- 96 
 
 111- 63 
 117-39 
 
 113-81 
 
 11907 
 
 113- 57 
 
 114- 15 
 
 1,532 
 222 
 
 3,350 
 740 
 600 
 
 780 
 
 690 
 2,097 
 1,576 
 
 lbs. 
 558-07 
 436-56 
 550-62 
 486-75 
 672-14 
 
 626-81 
 
 688-27 
 692-99 
 668-79 
 
 lbs. 
 . 400 
 
 400 & 500 
 400 
 500 
 
 1,369,210 
 
 114-15 11,587 
 
 606-80 ! 
 
 1 
 
 Table VI. 
 
 METROPOLITAN MAIN DRAINAGE. 
 Contracts on the South Side. 
 Summary of Tables VII. to XV. inclusive. 
 Portland Cement, Seven Day Tests, from 1859 to 1865. 
 
 •Nahbs of Mantjpactitbers 
 AND Agents. 
 
 Mr. Robins 
 
 BurhatQ Brick and Cement^ 
 Company (Mr. Webster)' . . j 
 Messrs. Lee and Co.^ 
 Messrs. E. Bow and Co. (Agents) 
 Messrs J. B. White & Brothers 
 
 Mr. Hilton 
 
 Messrs. Knight and Co 
 
 Mr. Smeed 
 
 Mr. Wood (Agent) 
 
 Messrs. Cubitt and Co 
 
 Mr. Buckwell (Agent) . . 
 Messrs. Fletcher & Co. (Agents) 
 Messrs. Francis Brothers . . 
 Mr. Tatham (Agent) 
 
 Quantity 
 
 in 
 Bushels. 
 
 Average 
 Weight per 
 Bushol. 
 
 Number 
 
 of 
 Tests. 
 
 Average 
 Breaking 
 Tests.3 
 
 Specified 
 Standard 
 Test.3 
 
 
 lbs. 
 
 
 lbs. 
 
 lbs. 
 
 128,467 
 
 119-43 
 
 1,423 
 
 670-67 
 
 400 
 
 938,322 
 
 112-89 
 
 7,023 
 
 631-09 
 
 400 & 500 
 
 99,450 
 
 120 03 
 
 962 
 
 612-85 
 
 400 
 
 1,000 
 
 
 10 
 
 546-80 
 
 
 34,430 
 
 109-13 
 
 327 
 
 544-18 
 
 
 27,788 
 
 114-17 
 
 510 
 
 511-01 
 
 
 69,358 
 
 112-66 
 
 574 
 
 500-53 
 
 
 44,241 
 
 111-85 
 
 423 
 
 452-36 
 
 
 3,600 
 
 107-83 
 
 102 
 
 444-50 
 
 
 112-00 
 
 6 
 
 409-11 
 
 
 ].,400 
 
 100-00 
 
 3 
 
 408-50 
 
 
 20,154 
 
 118-00 
 
 179 
 
 394-03 
 
 
 1,000 
 
 105-66 
 
 31 
 
 328-22 
 
 
 106-00 
 
 14 
 
 184-71 
 
 
 1,369,210 
 
 114-15 
 
 11,587 
 
 606-80 
 
 
 of the works cm- 
 
 1 Mr. Webster was the Contractor for the erection of two-thirc 
 braced in Tables V. and VI. , ^ , „ 
 
 2 Wm. Lee, Esq., M.P., was the Contractor for the Southern High-Level bewer. 
 
 3 Sectional area, 2-25 square inches. 
 
 0 2 
 
20 
 
 THE 8TEENGTH OP CEMENT. 
 
 Table VII. 
 METROPOLITAN MAIN DEAINAGE. 
 Southern High-Level Sewer. 
 Messrs. Lee and Co., Contractors. 
 Summary of Portland Cement, Seven Day Tests, from 1859 to 1862. 
 
 Name op Manufacturer. 
 
 Quantity 
 in 
 
 Bushels. 
 
 Average 
 Weight per 
 Bushel. 
 
 Number 
 
 of 
 Tests. 
 
 Average 
 Breaking 
 Tests. 1 
 
 Messrs. Lee and Co 
 
 99,300 
 
 lbs. 
 120-06 
 
 952 
 
 lbs. 
 614-66 
 
 Messrs. E. Bow and Co. 
 
 
 
 10 
 
 465 • 80 
 
 Mr. Kobins 
 
 19,300 
 
 120-87 
 
 183 
 
 544-32 
 
 Messrs. Knight and Co 
 
 6,338 
 
 118-50 
 
 75 
 
 541-13 
 
 Messrs. Fletcher, Lark, and Co. 
 
 18,154 
 
 118-50 
 
 159 
 
 515-15 
 
 Mr. "Wood 
 
 3,600 
 
 107-83 
 
 102 
 
 444-50 
 
 
 36 
 
 
 6 
 
 426-00 
 
 Messrs. Francis Brothers . . 
 
 1,000 
 
 105-66 
 
 31 
 
 328-22 
 
 Mr. Tatham 
 
 
 106-00 
 
 14 
 
 184-71 
 
 
 148,728 
 
 119-04 
 
 1,532 
 
 558-07 
 
 ' Specified standard, 400 lbs. 
 
 Table VIIL 
 METROPOLITAN MAIN DRAINAGE. 
 
 St. George's Wharf Contract. 
 Messrs. John Aird and Son, Contractors. 
 Summary of Portland Cement, Seven Day Tests, from 1860 to 1862. 
 
 Name op Manhfactukek. 
 
 Quantity 
 in 
 
 Bushels. 
 
 Average 
 Weight per 
 Bushel. 
 
 Number 
 
 of 
 Tests. 
 
 Average 
 Breaking 
 Tests. I 
 
 
 6,500 
 
 lbs. 
 113-64 
 
 202 
 
 lbs. 
 440-00 
 
 Messrs. Knight and Co 
 
 96 
 
 105-66 
 
 12 
 
 408-08 
 
 Messrs. J. B. White & Brothers 
 
 195 
 
 119-00 
 
 8 
 
 392-50 
 
 Total 
 
 6,791 
 
 113-28 
 
 222 
 
 436-56 
 
 * Specified standard, 400 lbs. Sectional area, 2 * 25 square inches. 
 
THE STRENGTH OF CEMENT. 
 
 Table IX. 
 
 METROPOLITAN MAIN DEAINAGE. 
 SoDTHEBN Outfall Seweb. 
 Mr. William Websteb, Contractor. 
 SuMMABY of Poetland Cement, Seven Day Tests, from 1860 to 1862. 
 
 Name of Manufactukei!. 
 
 Quantity- 
 ill 
 
 Bushels. 
 
 Average 
 Weight per 
 Bushel. 
 
 Number 
 of 
 Tests. 
 
 Average 
 Breaking 
 Tests. I 
 
 33urliaiin Brick ariid. Cement Com-'l 
 
 317,671 
 
 lbs. 
 111-51 
 
 2,726 
 
 lbs. 
 564-14 
 
 Messrs. J. B. Wliite and Brothers 
 
 26,280 
 
 108-85 
 
 179 
 
 521-38 
 
 Messrs. Knight and Co 
 
 31,888 
 
 110-92 
 
 ■ 247 
 
 510-52 
 
 
 10,766 
 
 112-18 
 
 153 
 
 476-65 
 
 Messrs. Oubitt and Co. 
 
 
 112-18 
 
 6 
 
 409-11 
 
 Mr. Buckwell 
 
 1,400 
 
 100-00 
 
 3 
 
 408-50 
 
 
 1,400 
 
 111-00 
 
 16 
 
 402-30 
 
 Messrs. Fletcher, Lark, and Co. 
 
 2,000 
 
 111-00 
 
 20 
 
 223-10 
 
 Generally . . 
 
 891,405 
 
 110-96 
 
 3,350 
 
 550-62 
 
 * Specified standard, 400 lbs. 
 
 Table X. 
 
 METROPOLITAN MAIN DRAINAGE. 
 Deptfobd PuMPiNa Station and Gas Woeks. 
 Messrs. John Aied and Son, Contractors. 
 SuMMABY of Poetland Cement, Seven Day Tests, from 1860 to 1862. 
 
 Name of MANtrFACuJEKK. 
 
 Quantity 
 
 in 
 Bushels. 
 
 Average 
 Weight per 
 Bushel. 
 
 Number 
 
 of 
 Testa. 
 
 Average 
 Breaking 
 Tests.i 
 
 
 1,200 
 
 lbs. 
 118-00 
 
 10 
 
 lbs. 
 691-40 
 
 
 17,952 
 
 115-18 
 
 210 
 
 545-28 
 
 Messrs. Knight and Co 
 
 30,937 
 
 109-55 
 
 240 
 
 482-03 
 
 
 150 
 
 118-00 
 
 10 
 
 440-90 
 
 
 33,475 
 
 111-66 
 
 270 
 
 438-62 
 
 Generally . . 
 
 83,714 
 
 111-63 
 
 740 
 
 486-75 
 
 ' Specified standard. 400 lbs. Sectional area, 2-25 square inches. 
 
22 
 
 THE STEENGTH OE CEMENT. 
 
 Table XI. 
 
 METROPOLITAN MAIN DRAINAGE. 
 
 South WARK and Westminster Communication (Soutliwark Street and 
 
 Subway). 
 
 Messrs. Downs and Pearson, Contractors. 
 Summary of Portland Cement, Seven Day Tests, from 1862 to 1863. 
 
 Name of Manufactukeu. 
 
 Quantity 
 in 
 
 Bushels. 
 
 Average 
 Weight per 
 Bushel. 
 
 Number 
 of 
 Tests. 
 
 Average 
 Breaking 
 Tests. 1 
 
 Mr. Robins 
 
 Burham Brick and Cement Coin-\ 
 pany (Mr. Webster) .. .. j 
 Messrs. J. B. White and Brothers 
 
 26,438 
 4,720 
 8,054 
 
 lbs. 
 120-12 
 
 122-66 
 
 108-07 
 
 430 
 30 
 140 
 
 lbs. 
 700-64 
 
 684-20 
 
 582-00 
 
 Generally . . 
 
 39,212 
 
 117-39 
 
 600 
 
 672-14 
 
 1 Specified standards, 400 lbs. and 500 lbs. 
 
 Table XII. 
 METROPOLITAN MAIN DRAINAGE. 
 Southern High-Level Extensions (Dulwich, Brixton, and Denmark-hill 
 
 Contracts). 
 
 Messrs. Pearson, Webster, and Dowell, Contractors. 
 Summary of Portland Cement, Seven Day Tests, from 1862 to 1863. 
 
 Name of Makdfacturek. 
 
 Quantity 
 in 
 
 Bushels. 
 
 Average 
 Weight per 
 Bushel. 
 
 Number 
 
 of 
 Tests. 
 
 Average 
 Breaking 
 Tests. I 
 
 Mr. Robins 
 
 Mr. Hilton 
 
 Burham Brick and Cement Com-\ 
 pany (Mr. Webster) / 
 
 3,037 
 1,200 
 
 46,206 
 
 lbs. 
 114-59 
 117-71 
 
 113-11 
 
 110 
 60 
 
 610 
 
 lbs. 
 674-95 
 644-28 
 
 616-54 
 
 Generally . . 
 
 50,443 
 
 113-81 
 
 780 
 
 626-81 
 
 1 Specified standards, 400 lbs. and 500 lbs. 
 
 Table XIII. 
 METROPOLITAN MAIN DRAINAGE. 
 Low-Level Sewer (Bermondsey Branch). 
 Messrs. John Aird and Son, Contractors. 
 
 Summary of Portland Cement, Seven Day Tests, from 1862 to 1863. 
 
 Name of Manufactckek. 
 
 Quantity 
 In 
 
 Bushels. 
 
 Average 
 Weigtit per 
 Bushel. 
 
 Number 
 
 of 
 Tests. 
 
 Average 
 Breaking 
 Tests.i 
 
 Mr. Robins .... 
 
 78,492 
 
 lbs. 
 119-07 
 
 690 
 
 lbs. 
 688-27 
 
 1 Specified standard, 500 lbs. Sectional area, 2-25 square inches. 
 
THE STRENGTH OF CEMENT. 
 
 23 
 
 Table XIV. 
 METROPOLITAN MAIN DRAINAGE. 
 Southern Outfall Works. 
 Mr. William Webster, Contractor. 
 
 Summary of Portland Cement, Seven Day Tests, for 1862-1864. 
 
 Name of Manhfactueek. 
 
 Quantity 
 
 in 
 Bushels. 
 
 Average 
 Weight per 
 Bushel. 
 
 Number 
 
 of 
 Tests. 
 
 Average 
 Breaking 
 Tests. I 
 
 
 
 lbs. 
 
 
 lbs. 
 
 Burham Brick and Cement Com-"i 
 
 349,620 
 
 113-57 
 
 2,097 
 
 692-99 
 
 pany (Mr. Webster) . . . . / 
 
 
 
 
 ' Specified standard, 500 lbs. 
 
 Table XV. 
 METROPOLITAN MAIN DRAINAGE. 
 Southern Low-Level Sewer. 
 Mr. William Webster, Contractor. 
 Summary of Portland Cement, Seven Day Tests, for 1864 and 1865. 
 
 Name of Manufactueer. 
 
 Qoantity 
 in 
 
 Bushels. 
 
 Average 
 Weight per 
 Bushel. 
 
 Number 
 of 
 Tests. 
 
 Average 
 Brealiing 
 Tests. I 
 
 Burham Briek and Cement ComA 
 pany (Mr. Webster) . . . . / 
 
 Generally 
 
 220^105 
 700 
 
 lbs. 
 114-15 
 
 114-00 
 
 1,560 
 16 
 
 lbs. 
 669-52 
 
 598-44 
 
 220,805 
 
 114-15 
 
 1,576 
 
 668-79 
 
 ' Specified standard, 500 lbs. Sectional area, 2-25 square inches. 
 
THE STRENGTH OP CEMENT. 
 
 r-l 
 
 S 00 
 > —I 
 
 fl . 
 
 S3 
 
 C« O 
 
 Si 
 
 So B 
 
 03 
 
 3 o 
 
 ,_< 
 
 bC.9 
 P CD 
 
 a ^ 
 
 o ~ 
 
 rr, 
 
 "C a; 
 
 Ph O 
 > 
 TO 
 
 02 
 
 ^ a 
 o _o 
 
 CO 
 
 Oh 
 2 P 
 Ph ft 
 
 +^ § 00 
 
 « 
 H 
 
 Last kind of Sand, 
 Washed. 
 
 IN 
 rH 
 
 lbs. 
 
 330-0 
 
 Itol 
 
 lbs. 
 224-9 
 
 364-9 
 
 Inferior, or Loamy 
 Pit Sand. 
 
 1 to 2 
 
 lbs. 
 
 251-5 
 
 1 to 1 
 
 lbs. 
 166-8 
 
 376-9 
 
 Clean Pit Sand. 
 
 1 to 2 
 
 lbs. 
 
 185-5 
 
 1 to 1 
 
 lbs. 
 
 227-8 
 423-1 
 
 625-9 
 
 815-4 
 
 Thames 
 Sand from 
 Southern 
 Outfall 
 Sewer. 
 
 Itol 
 
 lbs. 
 
 213-8 
 418-0 
 
 614-5 
 
 757-9 
 
 ement and Thames Sand 
 ^ptford Works in the 
 proportion of 
 
 in 
 
 o 
 
 lbs. 
 
 116-0 
 122-5 
 
 204-4 
 
 1 to 4 
 
 lbs. 
 
 149-0 
 198 '2 
 
 n 
 o 
 
 lbs. 
 62-0 
 
 108-0 
 308-1 
 371-1 
 
 The same C 
 from D( 
 
 lt02 
 
 lbs. 
 
 225-7 
 395-7 
 483-4 
 
 
 1 to 1 
 
 lbs. 
 
 190-7 
 373-5 
 
 603-2 
 
 724-0 
 
 Neat 
 Cement. 
 Breaking 
 w eignt 
 in 
 
 lbs. 
 
 558-5 
 784-5 
 
 960-8 
 
 1009-8 
 
 Age. 
 
 7 Days 
 28 ditto 
 
 3 Months . . 
 
 6 ditto 
 
 9 ditto 
 12 ditto 
 
26 
 
 THE STBENGTH OF CEMENT, 
 
 Table XVIII. 
 
 Table of the Results of 160 Experiments with Portland Cement, weighing 
 123 lbs. to the Imperial Bushel, gauged neat, and with an equal proportion 
 of clean Thames Sand, showing the Breaking Weight on a Sectional Area 
 of 2 • 25 square inches. 
 
 These form the first portion of a Series intended to extend over 10 years. The 
 whole of these Specimens were kept in Water from the time of their being 
 made till the time of testing, 1863 and 1866. 
 
 
 
 Neat Cement. 
 
 1 of Cement to 
 1 of Sand. 
 
 
 
 Age. 
 
 Average Break- 
 ing Test of 10 
 Experiments. 
 
 Average Break- 
 ing Test of 10 
 Experiments. 
 
 
 
 7 Days 
 
 1 Month 
 
 3 Months 
 
 6 ditto 
 
 9 ditto 
 
 12 ditto 
 
 3 ditto 
 
 lbs. 
 817-1 
 935-8 
 1055-9 
 1176-6 
 1219-5 
 1229-7 
 1324-9 
 1314-4 
 
 lbs. 
 353-2 
 452-5 
 547-5 
 640-3 
 692-4 
 716-6 
 790-3 
 784-7 
 
 
 Table XIX. 
 
 Table of the Eesults of 225 Experiments with Portland Cement, weighing 
 100 lbs. to the Imperial Bushel, gauged neat, and kept — 1st, in Water in 
 Testing-house ; 2nd, out of Water in Testing-house ; and 3rd, out of Water 
 on Roof of Testing-house, exposed to the action of the Weather. August, 
 1863, to September, 1864. 
 
 
 Average Breaking Tests of Five 
 
 
 
 
 Experiments.! 
 
 
 
 Age. 
 
 
 
 
 
 
 First. 
 
 Second. 
 
 Third. 
 
 
 
 lbs. 
 
 lbs. 
 
 lbs. 
 
 
 
 767-6 
 
 511-2 
 
 522-8 
 
 
 14 ditto 
 
 810-6 
 
 558-4 
 
 627-8 
 
 
 21 ditto 
 
 812-4 
 
 698-0 
 
 708-2 
 
 
 28 ditto 
 
 886-4 
 
 705-6 
 
 636-8 
 
 
 2 Months 
 
 881-0 
 
 877-0 
 
 594-0 
 
 
 3 ditto 
 
 952-0 
 
 612-8 
 
 671-0 
 
 
 4 ditto 
 
 968-6 
 
 774-6 
 
 814-8 
 
 
 
 993-0 
 
 786-6 
 
 783-2 
 
 
 6 ditto 
 
 1033-4 
 
 761-4 
 
 783-4 
 
 
 7 ditto 
 
 986-6 
 
 756-0 
 
 901-0 
 
 
 8 ditto 
 
 941-0 
 
 878-0 
 
 814-8 
 
 
 9 ditto 
 
 1048-6 
 
 845-8 
 
 714-0 
 
 
 10 ditto 
 
 1037-0 
 
 994-0 
 
 786-6 
 
 
 11 ditto 
 
 1039-4 
 
 909-6 
 
 876-0 
 
 
 12 ditto 
 
 1099-0 
 
 827-4 
 
 719-6 
 
 
 Total .. .. 
 
 14256-6 
 
 11496-4 
 
 10954-0 
 
 
 ' Sectional area. 2-25 square inches. 
 
THE 8TEENGTH OF CEMENT. 
 
 27 
 
 Table XX. 
 
 ^J'able of the Kesults of 33 Experiments with Portland Cement, weighing 
 117 lbs. to the Imperial Bushel, mixed with Fresh and Salt Water from 
 Sheerness. 1863 and 1864. 
 
 Sectional area, 2 '25 square inches. 
 
 i 
 
 Fresh Water. 
 
 Salt Water. 
 
 
 
 Age op Specimens 
 
 IMMERSED IN WaTEE. 
 
 Average 
 Breaking 
 Tests. 
 
 Average 
 Breaking 
 Tests. 
 
 
 
 
 lbs. 
 
 lbs. 
 
 
 
 
 738-2 
 
 891-00 
 
 
 
 14 ditto 
 
 
 938-66 
 
 
 
 21 ditto 
 
 
 973-50 
 
 
 
 
 
 940-40 
 
 
 Table XXI. 
 
 Table of the Results of 151 Experiments with Portland Cement, weighing 
 121 lbs. to the Imperial Bushel, gauged with Fresh and Salt Water. 1864. 
 
 Sectional area, 2 - 25 square inches. 
 
 
 Fresh Water. 
 
 Salt Water. 
 
 Age op Specimens 
 immersed in water. 
 
 Average 
 Breaking 
 Tests. 
 
 Average 
 Breaking 
 Tests. 
 
 
 lbs. 
 
 lbs. 
 
 
 922-0 
 
 942-86 
 
 14 ditto 
 
 1062-6 
 
 1056-60 
 
 21 ditto 
 
 1138-5 
 
 1147-70 
 
 28 ditto 
 
 1123-9 
 
 1203-30 
 
 2 Months 
 
 1175-5 
 
 1341-00 
 
 3 ditto 
 
 1256-9 
 
 1368-60 
 
 4 ditto 
 
 1320-7 
 
 1464-00 
 
 
 1327-16 
 
 1353-00 
 
 Total .. .. 
 
 9327-26 
 
 9877-06 
 
28 
 
 THE STRENGTH OF CEMENT, 
 
 Table XXII. 
 
 Table of the Results of 5 Experiments with Roman Cement, mixed neat, and 
 immersed in water for seven days. February, 1859. 
 
 Mandfacturee. 
 
 Number 
 of 
 
 Weight 
 per 
 
 Breaking Tests. Sectional area, 2-25 
 square inches. 
 
 
 Specimens. 
 
 Bushel. 
 
 Minimum. 
 
 Maximum. 
 
 Average. 
 
 
 
 lbs. 
 
 lbs. 
 
 lbs. 
 
 lbs. 
 
 Mr. Oldham.. .. 
 
 2 
 
 82-0 
 
 271 
 
 275 
 
 273-0 
 
 Mr. E, Cleaver .. 
 
 3 
 
 79-0 
 
 131 
 
 138 
 
 133-3 
 
 Average .. 
 
 5 
 
 80-5 
 
 201 
 
 206-5 
 
 189-2 
 
 Table XXIII. 
 
 Table of the Results of 60 Experiments with Roman Cement, weighing 
 82 lbs. to the Imperial Bushel, gauged neat, and immersed in water^ 
 showing the Breaking Weight on a Sectional Area of 2*25 square inches' 
 1862 and 1863. 
 
 Age. 
 
 Roman Cement. 
 
 Average Breaking 
 
 Tests of 
 10 Experiments. 
 
 
 lbs. 
 
 7 Days 
 
 77-5 
 
 28 ditto 
 
 94-5 
 
 
 114-5 
 
 6 ditto 
 
 90-5 
 
 9 ditto 
 
 85-5 
 
 12 ditto 
 
 104-3 
 
THE STRENGTH OF CEMENT. 
 
 Remarks. 
 
 ( 1 Four of these 
 I would not bear the 
 ( minimum strain. 
 
 ( 2 Three of these 
 1 would not bear the 
 (minimum strain. 
 
 3 One of these 
 would not bear the 
 minimum strain. 
 
 ent to 3 Sand. 
 
 Average 
 Break- 
 ing 
 Test. 
 
 lbs. 
 17-5 
 
 Max. 
 Break- 
 ing 
 Test. 
 
 i : :S • : 
 
 a 
 
 3 
 
 Min. 
 Break- 
 ing 
 Test. 
 
 1 : S : 
 
 1 Cement to 2 Sand. 
 
 Average 
 Break- 
 ing 
 Test. 
 
 lbs. 
 18-5 
 
 Max. 
 Break- 
 ing 
 Test. 
 
 ^ . m ■ ■ 
 S • CO • • 
 
 Min. 
 Break- 
 ing 
 Test. 
 
 1 : o : : 
 
 1 Cement to 1 Sand. 
 
 Average 
 Break- 
 ing 
 Test. 
 
 ^ fl : : : 
 
 Max. 
 Break- 
 ing 
 Test. 
 
 lbs. 
 
 Tin 
 
 Min. 
 Break- 
 ing 
 Test. 
 
 i 8 : : : 
 
 Neat Cement. 
 
 Average 
 Breaking 
 Test. 
 
 OOOi-hCOCDOOCOQO 
 S.-IC0i-IC001=0t--C0 
 <Nr-l(M(MCOeOr-ICO 
 
 Maximum 
 Breaking 
 Test. 
 
 mrHi— liOOOOOOCq 
 
 Minimum 
 Breaking 
 Test. 
 
 OOOMOOIMCOO 
 £rHi-l(Mi-HIM<M rH 
 
 Age and Time 
 immersed in water. 
 
 21 ditto 
 
 1 lYLon in 
 
 3 Months 
 
 6 ditto 
 
 9 ditto 
 
 12 ditto 
 
THE STRENGTH OF CEMENT. 
 
 <!fq 
 
 a bD 
 
 3 
 
 6c a 
 > St 
 
 .9 §H 
 
 S <M t-i 
 
 ?5 Vii-' f 
 
 P 
 
 ^ ^ ^ ^ ^3 
 
THE STRENGTH OF CEMENT, 
 
 33 
 
 Table XXVIII. 
 
 Table of the Results of 120 Experiments with Keene's Cement, manufactured 
 by Messrs. J. B. Whi'Te and Beothees ; and Parian Cement, manufactured 
 by Messrs. Feancis and Sons. 
 
 In Water in Testing-house, and out of Water in Testing-house, September, 
 1864. 
 
 SectioQal area, 2 * 25 square inches. 
 
 Age and Time 
 
 IMMEKSED IN WATEE. 
 
 Keene's Cement. 
 
 Parian Cement. 
 
 In Water. 
 
 Otit of Water. 
 
 In Water. 
 
 Out of Water. 
 
 Average 
 Breaking 
 Test. 
 
 Average 
 Breaking 
 Test. 
 
 Average 
 Breaking 
 Test. 
 
 Average 
 Breaking 
 Test. 
 
 
 lbs. 
 
 lbs. 
 
 lbs. 
 
 lbs. 
 
 
 543-9 
 
 546-0 
 
 595-1 
 
 642-3 
 
 14 ditto 
 
 486-9 
 
 585-8 
 
 600-8 
 
 671-2 
 
 21 ditto .. .. 
 
 503-0 
 
 579-4 
 
 543-4 
 
 696-6 
 
 1 Month 
 
 490-2 
 
 584-2 
 
 544-3 
 
 746-7 
 
 
 464-7 
 
 648-4 
 
 500-7 
 
 725-6 
 
 3 ditto 
 
 508-8 
 
 720-5 
 
 621-1 
 
 853-7 
 
 Table XXIX. 
 
 Table of the Results of 110 Experiments with Medina Cement and Sand. 
 Manufactured by Messrs. Feancis Beothers, 1864. 
 Sectional area, 2 - 25 square inches. 
 
 
 Neat Cement. 
 
 1 Cement to 1 Sand. 
 
 Age and TmE 
 
 IMMEUSKD IN WATEK. 
 
 Minimum 
 Breaking 
 Test. 
 
 Maximum 
 Breaking 
 Test. 
 
 Average 
 Breaking 
 Test. 
 
 Minimum 
 Breaking 
 Test. 
 
 Maximum 
 Breaking 
 Test. 
 
 Average 
 Breaking 
 Test. 
 
 
 lbs. 
 83 
 
 lbs. 
 100 
 
 lbs. 
 92-1 
 
 lbs. 
 
 lbs. 
 
 lbs. 
 
 ditto (2nd Series) 
 
 195 
 
 236 
 
 211-0 
 
 41 
 
 63 
 
 49 
 
 
 238 
 
 335 
 
 303-4 
 
 
 
 
 21 ditto 
 
 274 
 
 332 
 
 298-0 
 
 
 
 
 1 Month 
 
 210 
 
 346 
 
 306-0 
 
 
 
 
 3 Months 
 
 420 
 
 468 
 
 448-8 
 
 
 
 
 6 ditto 
 
 376 
 
 438 
 
 412'4 
 
 
 
 
 9 ditto 
 
 438 
 
 507 
 
 457-2 
 
 
 
 
 12 ditto .. . . .. 
 
 456 
 
 527 
 
 476-9 
 
 
 
 
 
 235 
 
 328 
 
 276 
 
 
 
 
 D 
 
THK STEENGTH OF CEMENT. 
 
 B 
 
 S fl a 
 'S £ 
 
 I.S g 
 
 OOOSCOOCOCqOi— lM>-l<NCO!NCOr-(eOO<N 
 
 l-l<r>lO-*Ot>rH(NOi-ieOOOOOT-lTfHrHOO 
 
 (3 a 
 
 |.si 
 
 OOOiOOOrHrH-*0(NOOi-Hi-IO<N<M 
 
 0000>f50>OiM<MrHOOO-<tiO(Mi-IO 
 
 :3 :=! :d :b o a :B 
 
 o o 
 
 -4-3 -4-3 
 
 o o 
 
 o o 
 
 o o : ^ o o o o 
 
 . ^ rg 17^ rj3 
 
 o o 
 
 CD 
 
 la 
 
 f-i 0 
 
 o q 
 
 H •■-! •■-! 
 
 '3 
 
 Si 
 
 M Id 
 O o3 
 
 P-i : 
 II 
 
 o o 
 
 *-a -4-3 
 
 U5 1— I (jq eo ■* 10 
 
 "So 
 
 go 
 
36 THE STBENGTH OP CEMENT. 
 
 M 
 X 
 
 III 
 
 3 c 
 
 "R a 
 s a 
 
 i2 
 
 6"? 
 
 o a 
 So 
 
 iD ■■3 
 
 s a 
 
 s a 
 
 -§5 
 
 •suampadg jo 'o^ 
 
 0.2 
 
 rH l-l CO r-l 
 
 CO 
 
 ■M 
 
 
 
 
 "m 
 
 
 
 
 
 0 
 
 
 tto 
 
 1 
 
 •3 
 
 
 
 0 
 
 
 iz; 
 
 
 2 2 
 ■3 '■3 
 
 locks 
 
 
 edBri 
 
 
 03 
 
 
 
 
 
 0 
 
 pre 
 
 0 
 
 p< 
 
 
 1 
 
 dit 
 
 3 
 
 to 
 
 
 0 
 
 
THE STRENGTH OF CEMENT. 
 
 37 
 
 ml 
 
 11 
 a a 
 
 TtlOOOi— It-Cl CD1005 05 
 .1— lOi— lOCOi— I l>r-llO CO 
 )0<M(N-*iXi:D .i-H05t> CO 
 
 t^OOCOi— IrJJCOlOOO 
 lOOOOCOOSiOCDTH 
 
 CO <>q rH i-H 
 
 I— ICqrH r-t j-l a T-f r-i 
 
 • CO 1> O CO (M 
 
 • lO (M 05 l> l> 
 
 O to O O O 
 
 • in CO SO iM CM 
 
 CO i-H CO o o 
 
 oooooooo 
 
 •S (N lO CO CO (M 
 
 S CO CO 
 
 _g(M(M O CO 1-H .0000 l> 
 
 a-*-*! (M (M CO CO (N C<J 
 
 i-HOi-ti-HOSOOCO 
 
 eoeococo(Mcoco(r^ 
 
 .gco'-O r*<<M -^tJHtH -1h TH■*lT^^Tj^T^^Tj^Tf^■*l 
 
 .SOSCO 00 0505 05 05 00 QO Q0O5 00 00 O5000000 
 
 i-Hi-t i-H rHi-(l01ClOC<J I— I eOr-<(M!?q(Mi-(rHeO 
 
 •a (B 
 
 t O 
 
 ^ o 
 o 
 
 2 t» 
 
 < 
 
 ^ CD 
 
 ^ o3 
 
38 
 
 THE STRENGTH OF CEMENT. 
 
 o 
 
 O r-l 
 
 I— I rfl 
 
 M (M 
 
 p 
 
 ZD a 
 
 CC 
 
 m 
 O 
 
 M o d 
 
 M ^ 
 
 M ^ I 
 
 H g W 
 
 <l fx 
 
 E-t 
 
 Pressure 
 per 
 Cubic Inch. 
 
 . CO t> CO o 
 S O O 00 
 £ l> l> t> 1-H 
 
 Pressure 
 per Square 
 Inch. 
 
 (M S<J CO 0> 
 05 (M lO -H 
 
 00 CO i> 00 ira 
 
 i-H i-i r-l O 
 
 Cubical 
 Contents. 
 
 inches. 
 85-75 
 
 92-04 
 111-63 
 
 Area. 
 
 inches. 
 
 37- 73 
 
 35-06 
 
 38- 83 
 
 Crushed. 
 
 Average 
 
 ^lO o o o 
 
 O 05 05 05 
 <M (M (N 
 
 Max. 
 
 i CO O O 05 
 ^ CO CO CO 
 
 Min. 
 
 00 l> 05 
 ^ (M !M (N 
 
 Cracked. 
 
 o 
 bD 
 03 
 
 > 
 
 O O CO O 
 O O CO O 
 
 o 1-H <M I-H i-H 
 <M (M i-H 
 
 Max. 
 
 2 CO (N CO 1-H 
 o (N (M i-i 
 
 Min. 
 
 C O (M rH 
 
 o (M (M 
 
 Size. 
 
 Depth. 
 
 inches. 
 2-75 
 
 2 •625 
 2-875 
 
 Breadth. 
 
 ^(M • 1-H CO 
 
 Length. 
 
 inches. 
 8-875 
 
 8-500 
 8-875 
 
 Number 
 
 of 
 Speci- 
 mens.;' 
 
 (M CO 1-H 
 
 Descbiptiok of Brick. 
 
 No. 1 Exbury's Best 
 Second Quality 
 Tiiird ditto . . . . 
 Unbumt Brick 
 
 Crush- 
 ing 
 Power 
 
 
 l-H CO ^1 
 
 CO 01(M lO 00 lO 
 m CO CO i-H 05 CO 00 
 
 gq (M to (M to lO 
 
 Cubical 
 Contents 
 
 inches. 
 109-83 
 105-27 
 
 Area. 
 
 inches. 
 39-94 
 38-28 
 
 
 
 K5 lO 
 t- t> 
 
 ze in Inch 
 
 
 0-45 
 4-375 
 
 tZ 
 
 
 8-875 
 8-75 
 
 Weight. 
 
 J 05 O . . . . 
 
 a> 
 n 
 
 o . 
 
 03 
 > 
 
 O CO CO CO - N 
 CO CO CD § § 
 
 o (N 'H !>q -b o 
 
 05 iO 05 O 
 1-H 
 
 ht when 
 is Crushe 
 
 i 
 
 C 00 00 CO 1> o o 
 o CO lO o o 
 rH rH 
 
 
 Min. 
 
 S CO CO Ttl i> 3d o 
 O rfH CO 00 TjH 00 O 
 1-H 
 
 racking 
 ice. 
 
 O) 
 M 
 
 > 
 
 , J O CO CO CO CO CO 
 c O CO CO CD CO CD 
 
 1-H 00 Tfl 05 (M r-l 
 >-H rH (M 
 
 II 
 
 c3 
 % 
 
 2 <M O >C CM 00 00 
 ^ rH rH IM rH (M Cq 
 
 Weigh 
 firs 
 
 Min. 
 
 ? O I> CO 03 O l> 
 O l-l (M rH 
 
 Desckiption of Stone Experimented on. 
 
 Portland Stone on tlie Bed 
 
 Yorkshire Landing on the Bed 
 Yorkshire Landing against the Bed . . . . 
 
THE STEENGTH OF CEMENT. 
 
 39 
 
 Table XXXVI. - 
 
 QuAKTiTiES used in making Brickwork Blocks, in Compo composed of 
 Portland Cement and Eiver Sand in equal proportions, each Block being a 
 3 feet cube = 1 cubic yard. February, 1865. Number of Bricks in each 
 Block, 384. 
 
 Materials. 
 
 No. 1 Block. 
 Gault Bricks with 
 
 Frogs. 
 Average, 8- 75X4-1 
 X2-75=98-6562, 
 
 No. 2 Block. 
 Gault Bricks, Wire 
 
 Cut, no Frogs. 
 Average size, 9 ■ 08 
 X4-14X2-r5=105-08. 
 
 No. 3 Block. 
 Sand Stocks. 
 Average size, 9-08 
 X4-21X2-70 
 =105-7573. 
 
 Cement weighing ■ "4 
 112 lbs. per bushel / 
 
 bushels. 
 3-615 
 
 cubic feet. 
 4-6406 
 
 bushels. 
 8-29 
 
 cubic feet. 
 4-2187 
 
 bushels. 
 3-29 
 
 cubic feet. 
 4-2187 
 
 
 3-615 
 
 4-6406 
 
 3-29 
 
 4-2187 
 
 3-29 
 
 4-2187 
 
 
 17-090 
 
 21-9236 
 
 17-98 
 
 23-0786 
 
 18-29 
 
 23-4780 
 
 Totals .. .. 
 
 24-320 
 
 31-2048 
 
 24-56 
 
 81-5160 
 
 24-87 
 
 81-9154 
 
 Table XXXVII. 
 
 Showing Two Series of Experiments as to the Quantities of Portland Cement, 
 Sand, and Water used in making One Cubic Yard of Compo, or Cement 
 Mortar. 
 
 First Series. | Second Series. 
 
 P.O. Sand. 
 
 1 to 1 
 
 1 to 2 < 
 
 1 to 3 ^ 
 
 1 to 4 
 
 1 to 5 
 
 Cement 
 Sand . 
 
 Bushels. 
 . 12| 
 
 2U 
 
 56 Gallons of Water. 
 
 Cement 
 Sand 
 
 16J 
 241 
 
 44 Gallons of Water. 
 
 Cement 
 Sand 
 
 6| 
 
 .. 19^ 
 
 26 
 
 46 Gallons of Water. 
 
 Cement ,, .. 5| 
 Sand 21 
 
 26i 
 
 47 Gallons of Water. 
 
 Cement 
 Sand . . 
 
 51 Gallons of Water. 
 
 21i 
 25^ 
 
 Cement 
 Sand 
 
 Bushels. 
 13 
 13 
 
 26 
 
 48 Gallons of Water. 
 
 Cement .. .. 8^ 
 Sand .. ..17 
 
 25^ 
 
 36 Gallons of Water. 
 
 Cement .. ,. 6 J 
 Sand ., ,. 18f 
 
 25 
 
 28| Gallons of Water. 
 
 Cement .. .. 5 
 Sand .. .. 20 
 
 25 
 
 38 Gallons of Water. 
 
 Cement 
 Sand 
 
 20| 
 241 
 
 34 Gallons of Water. 
 
40 
 
 THE STRENGTH OF CEMENT. 
 
 Table XXXVIII. 
 
 Eighty Experiments with Neat Portland Cement immersed in Water iaime- 
 diately on Setting, intended to illustrate the Increase of Strength from One 
 to Fourteen Days. Weight, 104 lbs. per Bushel. 
 
 The Series for each Day consisted of Ten Samples out of a Quantity selected 
 from various bags. 
 
 Age 
 of 
 
 Specimens 
 in Days. 
 
 Average 
 Breaking Strain 
 on 
 
 3 • 25 Square Inches. 
 
 
 lbs. 
 
 1 
 
 133- 
 
 2 
 
 417-7 
 
 3 
 
 500-8 
 
 4 
 
 540-4 
 
 5 
 
 586-0 
 
 6 
 
 665-9 
 
 7 
 
 705-5 
 
 14 
 
 826-8 
 
 Table XXXIX. 
 
 Showing Tensile Strains of Cements of different Specific Grravities at 
 different Periods. Sectional area, 2*25 square inches. 
 
 
 No. 
 of Table. 
 
 Weight 
 
 per 
 Bnshel. 
 
 1 Week. 
 
 1 Month 
 or 
 
 4 Weeks. 
 
 1 Year. 
 
 
 
 
 lbs. 
 
 
 
 
 
 
 19 
 
 109 
 
 767-6 
 
 886-4 
 
 1099-0 
 
 
 
 16 
 
 112 
 
 558 '5 
 
 784-5 
 
 1009-8 
 
 
 
 17 
 
 112 
 
 445-0 
 
 679-9 
 
 1075-7 
 
 
 
 18 
 
 123 
 
 817-0 
 
 935-8 
 
 1229-7 
 
 
THE STRENGTH OF CEMENT, 
 
 41 
 
 Table XL. 
 
 SOUTHEEN OUTFALL WORKS, CROSSNESS. 
 Summary of Portland Cement Tests, from 1862 to 1866, stowing generally 
 increase of Strength with increased Specific Gravity. 
 
 Number 
 of 
 
 Bushels. 
 
 1,800 
 5,800 
 26,166 
 37,036 
 20,820 
 6,900 
 13,812 
 10,610 
 24,224 
 16,240 
 27,400 
 26,800 
 '23,306 
 12,500 
 18,530 
 15,144 
 5,000 
 5,428 
 13,400 
 5,400 
 1,800 
 1,800 
 3,600 
 1,820 
 1,800 
 
 327,136 
 
 Average 
 Weight 
 
 per 
 Bushel. 
 
 lbs. 
 
 106 
 
 107 
 
 108 
 
 109 
 
 110 
 
 111 
 
 112 
 
 113 
 
 114 
 
 115 
 
 116 
 
 117 
 
 118 
 
 119 
 
 120 
 
 121 
 
 122 
 
 123 
 
 124 
 
 125 
 
 126 
 
 127 
 
 128 
 
 129 
 
 130 
 
 Tensile Strain 
 on 
 
 area = 2-25 
 Square 
 Inches. 
 
 lbs. 
 
 472-6 
 592-3 
 650-1 
 646-6 
 708-3' 
 693-8 
 687-5 
 701- 
 699- 
 705- 
 768- 
 718- 
 644- 
 777- 
 732- 
 705- 
 716-6 
 673-6 
 819-9 
 816-2 
 657-2 
 864-6 
 916-6 
 920-2 
 913-9 
 
 550-6 
 
THE STRENGTH OP CEMENT. 
 
 Days. 
 
 a s 
 
 as 
 
 118 lbs. 
 
 Tensile 
 Strain 
 per 
 
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 THE STKENGTH OF CEMENT. 
 
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44 
 
 THE STEENGTH OF CEMENT, 
 
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 I 
 
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THE STRENGTH OF CEMENT. 
 
 45 
 
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46 
 
 THE STRENGTH OP CEMENT. 
 
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THE 8TEENGTH OF CEMENT. 
 
 47 
 
 lip 
 
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 05 S ^ a 
 
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48 
 
 THE STEENGTH OF CEMENT. 
 
 CLAUSE AS IN EAELIER SPECIFICATIONS. 
 
 21. The whole of the cement to be used in these works and referred to in 
 this specification, is to be Portland cement of the very best quality, ground 
 extremely fine, weighing not less than 110 lbs. to the striked bushel, and 
 capable of maintaining a breaking weight of 400 lbs. seven days after being 
 made in an iron mould, of the form and dimensions shown on Drawing No. 1, 
 and immersed six of these days in water. 
 
 CLAUSE AS FIRST AMENDED. 
 
 27. The whole of the cement shall be Portland cement of the very best 
 quality, ground extremely fine, weighing not less than 110 lbs. to the striked 
 bushel, and capable of maintaining a breaking weight of 500 lbs. seven days 
 after being made in an iron mould, of the form and dimensions shown on 
 Drawing No. 1, and immersed in water during the interval of seven days. 
 The Contractor shall at all times keep in store upon the works a supply of 
 cement equal to at least fourteen days' requirements ; and with each delivery 
 of cement shall send to the Clerk of Works a memorandum of the number of 
 bushels sent in, and the name of the manufacturer. 
 
 CLAUSE AS LAST AMENDED. 
 
 - 25. The whole of the cement shall be Portland cement of the very best 
 quality, ground extremely fine, weighing not less than 112 lbs. to the striked 
 bushel, and capable of maintaining a breaking weight of 250 lbs. per square 
 inch seven days after being made in a brass mould, and immersed in water 
 during the interval of seven days. The Contractor shall at all times keep in 
 store upon the works a supply of cement equal to at least fourteen days' 
 requirements ; and with each delivery of cement shall send to the Clerk of 
 Works a memorandum of the number of bushels sent in, and the name of the 
 manufacturer. 
 
 METROPOLITAN MAIN DRAINAGE. 
 Register of Portland Cemekt. 
 186 . Manufactured hy 
 
 Delivered. 
 
 Quan- 
 tity in 
 Bushels 
 
 Weigbt 
 
 per 
 Bushel. 
 
 When 
 Moulded. 
 
 When 
 Tested. 
 
 Days 
 
 in 
 Moulds. 
 
 Broke 
 at 
 lbs. 
 
 No. of 
 Test. 
 
 Remarks. 
 
 1. 
 
 2. 
 
 3. 
 
 4. 
 
 5. 
 
 6. 
 
 1. 
 
 8. 
 
 
THE STRENGTH OP CEMENT. 
 
 49 
 
 Mr. G. W. Hemans thought the Paper just read formed the 
 best record of experiments on cement that had hitherto been 
 brought forward. He hoped the discussion would lead to the 
 consideration of what seemed to him to be the most interesting 
 application of cement, viz. the practicability of using it for 
 forming piers or walls in water, where currents prevailed, so as 
 to get rid of the cumbrous and expensive plan of constructing 
 coffer-dams. In 1862, a Paper was read before the Institution, 
 on deep-sea constructions of this nature,^ at which time the 
 amount of knowledge with regard to cements and betons was 
 less than it was now. Some facts in the Paper were new to 
 him. One was, that Portland cement appeared to set better in 
 salt water than in fresh water ; that was a valuable discovery. 
 Another new point, and in some respects rather alarming, was 
 that this cement was not applicable where there were currents 
 of water. But a considerable extent of sea wall had been he 
 believed, constructed at Brighton and other places, where Port- 
 land cement was largely used, without detriment, in situations 
 exposed to the action of tides and currents. If no further 
 experiments removed the difficulty with respect to the use of 
 Portland cement in moving water, its application to beton piers 
 would be very limited. He thought t]iat in England Engineers 
 were too timid in the application of concrete. Works were 
 often required which would not bear the expense of building 
 coffer-dams; it was, therefore, time this question should be 
 better understood. In France, Engineers who wanted to put a 
 pier in deep water, simply constructed a wooden box in the 
 water, which they filled with beton, of better quality than that 
 which had hitherto been used in this country ; and when the 
 work was raised to the level of the surface of the water, they 
 built the masonry upon it with great success, and this plan he 
 was about to carry out, in conjunction with Mr. Barton 
 (M. Inst. C.E.), in Carlingford Bay, in deep water, where it 
 was impossible, with the means at their disposal, to build an 
 ordinary coffer-dam ; the depth at low water being 19 feet, and 
 the rise of tide 16 feet more. A wooden box was, in fact, the 
 only covering that could be afforded. The concrete would be 
 deposited in the salt water for a depth of 19 feet, and on that 
 the masonry would be built. The concrete sy stem of construc- 
 » Vide « Minutes of Proceedings Inst. O.E.,' vol. xxii., p. 417. 
 
 E 
 
50 
 
 THE STEENGTH OF CEMENT. 
 
 tion was relied upon with so much confidence, that it was pro- 
 posed to remove the wood entirely from the back of the structure, 
 leaving it only in front ; and as it was evident the front casing 
 could only be temporary, the result would be, that the whole 
 weight of the superstructure, the total height being 46 feet, 
 would rest upon the concrete alone, which would eventually be 
 exposed to the action of the sea. Until this Paper was read, 
 he had resolved to construct that foundation with beton formed 
 of Portland cement ; but if the deductions of the Author were 
 true — and it was right to take them as such, from the extreme 
 care with which the experiments were conducted — it would 
 appear that, in this instance, with a rise of tide of 16 feet, it 
 would be inapplicable. He hoped other members would be able 
 to throw more light on the use of Portland cement in such 
 positions, in order that they might judge whether it was prudent 
 to rely upon it, instead of the ordinary hydraulic limes, for the 
 composition of that description of beton. The cost of the wall 
 he had alluded to, on the plan he had proposed, would be about 
 50Z. per running foot, while the construction of a coffer-dam 
 would enhance the cost by about lOZ. to 151. per foot, and the 
 removal of the dam would, under the circumstances stated, 
 endanger the work, and where the pecuniary means at command 
 were limited that risk could not be run. 
 
 Mr. Abeenethy said the question of the use of Portland 
 cement for the foundations of marine works had been one of 
 great interest to him for many years past, and he had gathered 
 from the Paper one or two facts which he was not previously 
 acquainted with. There was one fact, however, with which all 
 were well acquainted, viz. that the sand used in cement must 
 be sharp and clean ; but the information which was most 
 satisfactory to him was, that Portland cement set better in salt 
 water than in fresh. 
 
 With regard to the doubts as to employing Portland cement 
 in situations exposed to currents, it occurred to him that if the 
 wooden boxes were used that difficulty would be removed. 
 
 Mr. Hemans said the box would be used only up to low- 
 water mark. 
 
 Mr. Abernethy added, under those circumstances, the con- 
 crete in the box would only be exposed on the surface. He 
 thought Mr. Hemans might safely undertake the work in the 
 
THE STRENGTH OF CEMENT. 
 
 51 
 
 way he proposed, inasmuch as the concrete would be, for a 
 considerable time, protected from the action of the current by 
 the facing of the box. 
 
 Mr. Druce said, a large quantity of Portland cement had 
 been used in the pier works at Dover, all of which had been 
 carefully tested, and he could corroborate the opinion, by his 
 own experience, that no detriment to the cement was occasioned 
 by the use of it in salt water. Where currents prevailed, he 
 had found that cement in liquid concrete, from its slow-setting 
 property, was liable to be washed away ; but after it was once 
 set it was not affected by them. The difficulty with Portland 
 cement was to obtain it of thoroughly good quality, the demand 
 for it at the present time being beyond the means of supply. 
 With reference to the mode of testing, he had adopted the 
 steelyard system for the last ten years, but he did not think it 
 sufficient. He had met with many instances in which cement 
 after having stood the ordeal of that machine, and shown high 
 results, had afterwards entirely failed from causes for which the 
 cement-maker was chiefly to blame. The surest way to guard 
 against the effects of inferior or " blowing " cement was to 
 have a sufficient stock on hand to enable it to be thoroughly 
 air-slaked before it was used. Provided it was kept from 
 damp it could not have too much air. His practice at Dover 
 was to expose it to the air for at least one month, which 
 reduced the imperfectly burnt portions to an inert and harm- 
 less condition ; and since that had been done, faulty cement in 
 the work had become very rare. 
 
 A point to be considered was the size of the test-blocks. He 
 believed more reliable results were obtained from blocks having 
 an area of about six inches than from smaller ones. A sure 
 criterion of quality was the weight per bushel, and that de- 
 pended a great deal upon the burning. As an instance of the 
 little effect produced by currents upon Portland cement, he 
 would state that, in the construction of a small pier on the 
 Sussex coast, Portland cement concrete blocks had been used 
 with satisfactory results, even where exposed to the action of 
 the tide and the constant abrasion of shingle ; and it had stood 
 for some years the wear and tear of them. He regarded this 
 as a most valuable cement for hydraulic work, and for very 
 many purposes it was far superior to any other; but the con- 
 
 E 2 
 
52 THE STRENGTH OF CEMENT. 
 
 tinuous and careful testing required was a disadvantage con- 
 nected with its use. 
 
 Mr. Egbert Rawlinson, C.B., remarked, that some years 
 ago he had acquired considerable experience in the use of 
 hydraulic mortars and cements. If he might be permitted to 
 do so, he would inquire how the Author specified for the mixmg 
 of the Portland cement— whether it was mixed on mortar- 
 boards with a shovel, or ground in a pan, or in what way it was 
 mixed ; and whether mortar, which had been mixed overnight 
 and stood all night, was allowed to be re-tempered and used in 
 the work. There was one application of Portland cement not 
 generally known, viz. its use, when of good quality, under 
 water, by the aid of a diver. He had used it to make a joint 
 between iron and iron, under a 90-feet head of water, with 
 perfect success, to keep out a quicksand. No other means had 
 enabled him to master that quicksand. He had occasion to sink 
 a well where there was a quicksand at the depth of 90 feet, 
 overlaid by a thick bed of marl, and underlaid by new red 
 sandstone irock. A first well was sunk in the ordinary manner, 
 by miners of the district, and, being an utter failure after two 
 years' work, was abandoned. The second well was sunk within 
 30 feet of the same site, by 7-feet cylinders, which were sunk 
 without pumping, and lowered by working inside, till they 
 rested on the new red sandstone rock ; but the dip of the rock 
 was at such an angle that the 7-feet cylinder could not be made 
 to bed into its surface. He then worked with drills in the 
 sandstone rock, by placing a second cylinder inside the first, 
 with a cast-iron diaphragm bottom, having a 2-feet hole in the 
 centre for the passage of the boring tool ; but the difficulty 
 was to make the joint between the two cylinders tight. The 
 ordinary iron cement, of iron borings and sal-ammoniac, would 
 not set, but washed out. He then sent down pure, stiffly-made 
 Portland cement in buckets ; this was put in place by divers 
 and set perfectly, where it had remained for three or four years, 
 though exposed to a severe strain by the constant pumping.^ 
 He should be glad of further information upon the cost of 
 
 1 To close the joint round tbe bore pipe passed through the diaphragm, 
 Portland cement concrete was used, sent down also in 90 feet of water, spread out 
 and placed by a diver. 
 
THE STRENGTH OP CEMENT. 
 
 53 
 
 Portland cement. All the mortar used at the Liverpool docks 
 — and there could be no better for hydraulic purposes — was 
 made with sea sand, and mixed with salt water. The limestone 
 was from Halkin, in North Wales, was burned at the works, 
 drawn warm from the kiln, slaked on the floor, mixed with 
 1 part sea sand, ^ part furnace ashes, ground in a revolving 
 pan twenty minutes, and cost, net on the floor of the mill, from 
 9s. to 10s. per cubic yard. He thought Portland cement would 
 be, at least, three times that cost. At the Liverpool docks 
 4 cubic yards of brickwork contained 1 cubic yard of mortar, 
 or in the proportion of 1 to 4. In rubble work the proportion 
 was 3 to 1. In other words, 3 cubic yards of rubble con- 
 tained 1 cubic yard of mortar. Mr. Hartley abandoned the 
 use of ashlar for facing sea and dock walls, and relied upon 
 granite rubble. The red sandstone ashlar cost about 24s. to 
 30s. per cubic yard, and the granite facing rubble, only from 
 12s. to 15s. per cubic yard ; red sandstone rubble backing cost 
 about 9s. per cubic yard. One of the great uses of Portland 
 cement, or mortar like that at the Liverpool docks, would be 
 to enable Engineers to accomplish great works of this class — 
 river walls and dock works — at much less cost than by using 
 the more expensive granite ashlar veneering. Last autumn he 
 visited the works at Cherbourg, than which, as specimens of 
 ashlar masonry, perhaps finer could not be seen. The inner 
 harbour, graving docks, and the several structures on the great 
 breakwater there, were all, however, faced with granite ashlar. 
 To show the misuse of this granite ashlar veneering, he might 
 mention that, probably from a ship coming in contact with it, 
 a considerable length of the said granite ashlar face- work had 
 fallen into the entrance of the harbour, leaving the rubble 
 backing standing, as sound as the day on which it was put up. 
 The casemate forts on the breakwater were splendid specimens 
 of granite ashlar, but they were rent and split in all directions 
 by the giving way of the foundations, and by the impossibility 
 of the mortar, in their beds and joints, holding such work 
 together. If that work had been executed on the plan adopted 
 by Mr. Hartley for the last twenty years, viz. rubble to the 
 face, it would have saved the French Government one-third of 
 the entire expense of those works, and the masonry would 
 have been of much greater strength. Forts, instead of being 
 
54 
 
 THE STRENGTH OF CEMENT. 
 
 faced with ashlar, would be stronger and more fit for their 
 purpose if built with good solid rubble put together with 
 hydraulic mortar, or with Portland cement, of this or of an 
 analogous character. Ashlar would split, and break away in 
 lumps and masses, under the pounding of heavy artillery. 
 Eubble work would not split in like manner, but would rather 
 indent and crush; only the immediate part struck being 
 affected, and small portions being detached.^ 
 
 ' The following details relative to Halkin Mountain limestone were subse- 
 quently supplied by Mr. Rawlinson. This limestone is obtained from quarries 
 situate near Holywell, Flintshire. Limestone from these quarries has been 
 obtained for the great hydraulic works at the Liverpool docks for the last thirty 
 years. 
 
 The following analysis by Dr. S. Musprat, of Liverpool, was made in 1862 : — 
 
 This hydraulic limestone affords — 
 
 Substances soluble in acids 74 " 726 per cent. 
 
 Substances insoluble in acids 25 ■ 274 „ 
 
 These two classes afford the following approximate components — 
 
 Centesimally. 
 
 ! Carbonate of lime 71*546 
 
 Carbonate of magnesia 1 • 348 
 
 Proto-carbonateSfiron\ , ... 
 
 Sulphide of iron | ^ ^^^ 
 
 Alkalies 0-792 
 
 {Silicic acid 20-068 
 
 Alumina 3-521 
 
 Sesquioxide of iron, &o 1 - 192 
 
 Water and carbonaceous matter 0 • 493 
 
 100-000 
 
 The sample of limestone, of which the preceding is a carefully-performed 
 analysis, is of the blue lias variety. 
 
 The components, which induce cementation of the mortar under water, exist in 
 this sample of lime to an extent of about one-fourth of its weight. The carbonate 
 of lime and other matters soluble in hydrochloric or nitric acids are in proportion 
 as 1 to 3. The best cement or mortar is obtained from limestones which 
 contain carbonate of lime, magnesia, and clay, naturally commingled in this 
 ratio, of three parts of the former to one of the latter. The quantity of silicic 
 acid and silica which exists in Halkin Mountain limestone, as per sample analyzed 
 being evenly distributed through its entire mass, is rendered, by calcination of 
 the stone, most favourable to the production of an insoluble crystallized silicate of 
 lime, when made into mortar. 
 
 This limestone burns to a yellowish-white colour, producing lime of average 
 whiteness. ° 
 
 At the Liverpool docks, the lime kilns and mortar mills are situate together. 
 
THE STRENaTH OF CEMENT. 
 
 55 
 
 Mr. G. F. White, as a manufacturer of Portland cement, 
 desired to express his high, appreciation of the Paper, the 
 details of which were, for the most part, in accord with his own 
 experience. He thought the Meeting would agree with him, 
 that greater intelligence and honesty of purpose could hardly 
 have been brought to the investigation of the subject than had 
 been evinced by the Author, who, whilst consulting, as was his 
 duty, the interest of the public, yet, at the same time, dealt in 
 the fairest manner with those manufacturers who had been 
 brought into contact with him. 
 
 In the few remarks he had to make, he should direct atten- 
 tion particularly to the question of the " specific weight " of the 
 cement which the Engineers of the Board of Works had exacted 
 from the manufacturers. It might be remembered that in the 
 year 1852 he had presented a Paper to the Institution, con- 
 taining "Observations on Artificial Hydraulic, or Portland 
 Cement,"^ the object of which was, to explain the composition 
 of that material, and to place on record the results of the 
 experiments which had, up to that period, been made on the 
 cement, chiefly by the Engineers of the French Government. 
 For the first few years after its introduction, Portland cement 
 had been supposed, even by Engineers, to be, in part at least, 
 composed of Portland stone. In the Paper referred to he had 
 
 The fresh-burned lime is drawn from the kiln, slaked, mixed with sea sand and 
 furnace ashes, put in the mortar pan, and ground for immediate use. 
 
 Best mortar : — Lime, by measure, 1 part. 
 
 Sand ,, 1 
 Ashes „ I 
 Common mortar : — Lime „ 1 
 Sand „ 2 
 Ashes „ i 
 
 It is ground in pans, which revolve beneath heavy cast-iron rollers, so that the 
 process crushes by partial sliding as well as by grinding. 
 
 This mortar on the floor, when made, costs from 8s. to 10s. per cubic yard. 
 
 Random rubble requires about 1 cubic yard of mortar to 3 cubic yards of 
 rubble masonry. Brickwork requires about 1 cubic yard of mortar to 4 cubic 
 yards of brickwork. Grout is made by diluting the best mortar with water until 
 it will pour evenly over the work. Both rubble masonry and brickwork, when 
 used in dock, sea, or river walls, are regularly grouted as the work proceeds, so as 
 to wet the entire mass, and every stone and every brick is bedded, jointed, and 
 covered by grout and mortar, so as to constitute one solid mass, 
 
 • Vide ' Minutes of Proceedings Inst. O.E.,' vol. xi., p. 478. 
 
56 
 
 THE STBENGTH OF CEMENT. 
 
 explained that it was an artificial compound of chalk and clay, 
 the peculiar nature and proportions of which had been quite 
 correctly re-stated in tlie Paper just read. In introducing a 
 cement of this character it was very necessary to adopt some 
 general standard of excellence, and the Engineers of the Fonts 
 et Chaussees, to whom this cement had been introduced about 
 the year 1850, were not slow in bringing the analyzing powers 
 of the French mind to bear on the subject. They had proposed 
 and applied numerous tests, which had not been materially 
 varied to the present day, and which, for the sake of comparison 
 with the Board of Works tests, might be stated as follows : — 
 
 Specific weight .. .. 1200 kilogrammes per metre, cube, or 
 
 103 lbs. per imperial bushel. 
 Tensile strain, tried on bricks with the same sectional area employed by the 
 Board of Works, viz. 2 '25 square inches. 
 Neat cement . . . . 2 days 64 kilogrammes, or 140 lbs. per brick. 
 
 5 „ 128 „ 280 „ 
 
 30 „ 240 „ 530 
 
 Cement 1 part \ . . 5 „ 64 „ 140 „ 
 
 Sand 2 parts / ., 30 ., 128 „ 380 „ 
 
 The Engineers of the Board of Works were the first public 
 ofiGcials in this country who had instituted analogous tests, 
 though Mr. Kendel, in the year 1852, and Mr. Druce, at a sub- 
 sequent period, had carefully investigated the subject, in con- 
 nection with the works at Holyhead and at Dover. The Board 
 of Works tests were of a threefold character : 1st. The cement 
 must be of a given specific weight ; 2nd. When gauged neat, it 
 must have a certain resistance to tensile strain ; 3rd. It must 
 bear immersion in water, without sign of cracking. The tensile 
 strain, at first fixed at 400 lbs., had been raised to 500 lbs., and 
 the specific weight, fixed originally at 110 lbs., had been raised 
 to 112 lbs. per bushel. It was to this test of 112 lbs. per bushel, 
 which indicated a very heavily burnt cement, that he desired 
 to direct some attention, as pressing severely on the manu- 
 facturers, without, as he believed, conferring any corresponding 
 benefit on the Engineer. The way in which it affected the manu- 
 facturers was as follows : — In the first place, the less the con- 
 centration given to the cement by burning, the greater was the 
 volume of cement that could be obtained from a given quantity 
 of raw material. In other words, if a certain quantity of chalk 
 and clay, calcined to the specific gravity of 104 lbs. per bushel, 
 
THE STBENGTH OF CEMENT. 
 
 57 
 
 produced 21^ bushels of cement to the ton, the same quantity 
 of raw material, burnt to weigh 112 lbs. per bushel, would pro- 
 duce only 20 bushels to the ton, and thus occasion the manu- 
 facturer a loss, in volume, of 7^ per cent. Secondly, cement of 
 so high a specific gravity as 112 lbs. involved a much larger 
 consumption of the fuel, employed in burning it, an item which, 
 under the most favourable circumstances, counted for nearly 
 one-third of the prime cost of the cement. Thirdly, the destruc- 
 tion of kilns, and of the machinery employed in grinding the 
 cement, was enormously increased by the intensity of the heat 
 required to produce it, and by the hardness of the material to 
 be ground. Fourthly, the quantity of this highly-calcined and 
 heavy cement, that could be produced in any one kiln, bore 
 only a certain proportion to a residue, which was not sufficiently 
 burnt to produce cement weighing 112 lbs., but which could be 
 employed advantageously in the manufacture of cement that 
 was iutended to set more quickly, and to weigh only 104 lbs. per 
 bushel. And he might add — what was really, to the makers, 
 the most important consideration of all — that very little, if any, 
 increase of price was given for this heavy cement, over that 
 which was so much less costly in the manufacture. 
 
 He would now, however, look at the question as it affected 
 Engineers ; and, fl^rst, this heavily burnt cement was a dangerous 
 cement to use. It was well known to manufacturers that to be 
 able to push the calcination far enough to produce a cement of 
 a uniform gravity of 112 lbs., it was needful to combine more 
 lime with the clay than was required for lighter burnt cement ; 
 and that, in so doing, there was the risk that a perfect amalga- 
 mation of the lime and clay would not be effected ; but some 
 of the lime, being left in a free state, would be liable to be 
 slaked by water, or even by the moisture of the atmosphere, 
 and produce, sooner or later, the fatal disintegrations which all 
 Engineers had witnessed. 
 
 The next consideration was the slowness of the setting of this 
 heavily burnt cement. The Author had stated that it would 
 not set in running water, and that, therefore, he had used 
 means to prevent any water passing over the cement in the 
 sewers during their construction. Now, Portland cement of 
 English manufacture had been successfully employed for con- 
 crete en masse, in constructing the under-water foundation for 
 
58 
 
 THE STRENGTH OF CEMENT. 
 
 a lighthouse on a coral reef in the Eed Sea.^ It was quite 
 intelligible that, though the cement of 112 lbs. would set too 
 slowly for this purpose, a lighter burnt cement would effect the 
 desired object. To lose sight of this, and to insist that all 
 cement, whatever its destined use, should be thus concentrated 
 in burning, would be simply to deprive it of one of its most 
 valuable properties — that of setting rapidly under water. 
 
 Another inconvenience, to which this heavily burnt cement 
 exposed the Engineer, was the almost certainty that it would 
 not be properly ground. Theoretically, the cement should be 
 an impalpable powder, and every grain of sand a matrix, round 
 which the cement should form a film, or coating ; but this could 
 scarcely be the case with a material, which it was so difficult 
 to reduce to powder, as the heavy cement in question. On the 
 contrary, if carefully scrutinized, by passing it through a sieve 
 or by washing it, a considerable residue of particles resembling 
 sand would be found, comparatively inert in their character, 
 with very feeble setting properties, and of a nature to diminish 
 the amount of real sand which the cement would otherwise 
 carry. He might also add, that the coarsest ground cement 
 being found to weigh the heaviest, the exaction of a very heavy 
 specific weight, unaccompanied by any other restriction, offered 
 an inducement to imperfect pulverization. 
 
 A fourth objection was the loss of volume, which would be 
 sustained by the Engineer, equally with the manufacturer, if 
 he were to become the buyer of cement by the ton, instead of 
 having it furnished through the contractor. The Engineers of 
 France, who almost always bought the cement for the Govern- 
 ment works under their charge, were careful to regulate this 
 question, by procuring a cement of sufficient density to pass 
 their tests, while stipulating that it should not exceed that 
 weight, so as to produce a needless loss in volume. 
 
 In support of these views, he had compiled the following 
 table, showing the requirements of the Board of Works and of 
 the French Engineers, side by side, and the results of the tests 
 which had been applied to the cement delivered to both of those 
 services during the last five years or six years. 
 
 The French tests were made at two days, at five days, and at 
 
 ' Vide ' Minutes of Proceedings lust. C.E.,' vol. xxiii., p. 1. 
 
THE 
 
 STRENGTH OF CEMENT. 
 
 r-l 1-1 (M 
 
 03 -B 
 
 in ci 
 
 CO 
 
 P 
 I 
 
 Eh 
 Ph 
 
 II 
 
 r-l 
 
 EH 
 
 O 
 
 « 2 
 
 o3 -J^ 
 O 'TS 
 
 >> -1^ 
 
 Q 'm 
 
60 
 
 THE STRENGTH OF CEMENT. 
 
 thirty days, on cement of 103 lbs. or 104 lbs. specific gravity ; 
 and it would be observed that the cement supplied to meet 
 these demands had been from 50 per cent, to 100 per cent, in 
 excess of the requirement. 
 
 The Board of Works tests had been made at seven days, 
 the requirements being — specific gravity 112 lbs., tensile strain 
 500 lbs. ; and the general average of the whole of the cement 
 supplied for the works of the Metropolitan Main Drainage on 
 the south side of the river Thames had been stated to be — 
 specific gravity 114 lbs., tensile strain 606 lbs., or 270 lbs. per 
 square inch. In one of the Tables (XXXVII.), however, the 
 average strength of cement of 112 lbs. weight per bushel had 
 been shown to be, at seven days, only 501 lbs., or 222 lbs. per 
 square inch — which was on a par with the requirement and no 
 more ; while cement weighing but 104 lbs. had acquired, at 
 seven days, a strength of 560 lbs., or 250 lbs. per square inch, 
 being 12 per cent, in excess of the strength exacted by the 
 Engineers of the Metropolitan Board of Works, When mixed 
 with sand, the difference between the two cements was still 
 more marked, for while, at seven days, the cement of 112 lbs. 
 resisted only 90 lbs. per brick, or 40 lbs. per square inch, the 
 cement of 104 lbs. resisted, at five days, a strain of 196 lbs., or 
 87 lbs. on the square inch, being 40 per cent, in excess of the 
 strength demanded by the French tests, and more than double 
 that of the heavily burnt cement. The comparisons were also 
 in favour of the lighter cement at the age of thirty days, both 
 neat, and with sand. 
 
 The only conclusion he could draw from these results was, 
 that the test of specific weight was too variable to be relied on, 
 if unaccompanied with other conditions ; that the heavily burnt 
 cement would, very commonly, be coarsely ground, and that it 
 would, in consequence, carry less sand, or, if gauged with two 
 or three parts of sand (the usual proportion), it would be a long 
 time in indurating. As a rule, only one part of sand to one of 
 cement had been used in the sewers, which would, doubtless, 
 make a strong, though it must be confessed a rather costly, 
 mortar. Perfect pulverization was a more essential condition 
 than great specific weight, and a lighter cement, more finely 
 ground, would have carried two parts of sand, and made as good 
 a mortar, at less cost. 
 
THE STRENGTH OF CEMENT. 
 
 61 
 
 The question here invoh^ed, however, was not so much one of 
 high quality or low quality, as of the adaptation of different 
 classes of material to various sorts of work. Different works 
 demanded, without doubt, different qualities of cement. Where 
 a long time could be given for induration, a slow-setting cement 
 might be advantageously used ; but for tide-work and water- 
 work generally, as well as for the purposes of ordinary building, 
 medium burning, fine grinding, and rapid induration were pre- 
 ferable to the slow induration and the coarse grinding which 
 were the practical concomitants of the heavily burnt cement. 
 
 Mr. Caeleton Baynes said that he had made experiments 
 on cement weighing 114 lbs. to the bushel, which was moulded, 
 and the bricks then immersed in water for periods varying 
 from one day to seven days, one being broken each day. 
 After one day in water, the cement broke at 275 lbs. ; after 
 two days, at 265 lbs., owing to a fracture in the mould ; after 
 three days, at 520 lbs. ; after four days, at 580 lbs. ; after five 
 davs, at 570 lbs. ; after six days, at 765 lbs. ; and after seven 
 days, at 890 lbs. Another set of moulds, from a similar parcel, 
 broke on the second day at from 254 lbs. to 378 lbs. 
 
 The test was excellent, and specially suited to the work in 
 question; but he would suggest that there should be some 
 limit, for, to judge from the tables, the cement of 123 lbs. to 
 the bushel would be very superior to that of 112 lbs. to the 
 bushel. He considered that the cement of 112 lbs., emteris 
 ^paribus, would be a better cement than that of 123 lbs., on 
 account of the slowness of setting of the latter. It was indeed 
 quite a different cement to work from that of 112 lbs., and that, 
 in its turn, was quite different from a cement of 104 lbs. 
 The hard-burnt cement was not generally useful ; the builder 
 and plasterer would be much disappointed if it were sent to them, 
 and in tide-work a slow-setting cement was not desirable. In 
 an article which was sold by the bushel, bulk was a thing to be 
 desired, and if equal efficiency was attainable with a less 
 specific weight, the lighter cement was preferable. 
 
 The conditions demanded for general purposes were— to cover 
 the greatest extent of surface, to be of uniform colour and 
 setting power, and not to crack, or peel off from the brick- 
 work; the breaking test would be of little service in obtaining 
 these conditions. 
 
62 
 
 THE STRENGTH OF CEMENT. 
 
 There was probably no manufactured article which depended 
 so much for its excellence on the manipulation it received as 
 cement. Thousands of tons of good cement were spoilt by- 
 being improperly gauged, or by being gauged a second time 
 after having partially set, and oftentimes first-rate cement was 
 condemned because a mason had not been accustomed to its 
 particular way of setting. On great works, where large stores 
 of cement must necessarily be kept, it was desirable that, 
 instead of being stowed in bags, as was generally the custom' 
 it should be shot in a large shed, and occasionally turned over. 
 It would be as much to the interest of the Engineer as to that 
 of the contractor, because the cement would be greatly im- 
 proved by it. The cement was sometimes taken from the 
 manufacturers quite hot and stored in bags, tons and tons over 
 each other, and it had no chance of cooling, but was almost 
 certain to " blow " in the work. 
 
 In reply to an inquiry, Mr. Baynes said, in objecting to a 
 heavy cement as being slow setting, he referred particularly to 
 that weighing 123 lbs. per bushel. He was led to desire a 
 limit to the specific weight required in cement, because it 
 might be supposed, if cement was burnt to 130 lbs., it would be 
 better than that which was burnt to only 123 lbs. When this 
 heavy cement was gauged, it would not set enough to be taken 
 out of the mould for a long time ; it had then to be coaxed into 
 the water, and after all, three moulds or four moulds would often 
 run together in the water, and the moulds would not keep 
 their edges, though they stood this enormous breaking test. 
 If, however, it had been tide-work, it could not have been 
 humoured in that way. It was frequently requisite to let the 
 cement set for hours, after being taken out of the mould, before 
 putting it into the water ; and of those briquettes, many would 
 have to be trimmed to go into the machine, so as to be tested 
 and broken. 
 
 Mr. C. L. Francis thought there was yet much to learn from 
 the analysis of the materials of which cement was composed, 
 as well as in its uses and application. Cements of so great 
 weight were costly and inconvenient to the manufacturer, and 
 should be costly to the consumer. It was stated in the Paper 
 that bricks of neat Portland cement, after being made three 
 months, six months, and nine months, withstood a crushing force 
 
THE STRENGTH OP CEMENT. 
 
 63 
 
 of 65 tons, 92 tons, and 102 tons respectively, or were equal in 
 strength to the best quality of Staffordshire blue bricks ; and 
 that bricks of the same cement mixed with four parts and five 
 parts of sand, bore a pressure equal to the best picked stock 
 bricks ; while Portland stone of similar size bore, on its bed, a 
 crushing weight of 47 tons, and against its bed somewhat less, 
 and Bramley Fall stone sustained on its bed 93^ tons, and 
 against its bed 54 1 tons. Portland stone crushed easier than 
 the lowest experiment with Portland cement. Where, then, 
 was the practical use of having a cement stronger than the 
 material which had to be joined together ? If the stone de- 
 cayed what were the joints good for ? He believed that cement 
 of from 100 lbs. to 103 lbs. would last as long as any materials 
 it could unite. With respect to the preliminary experiments 
 made with samples of Portland cement, of the average weight 
 of 108-6 lbs. per bushel, it appeared that they sustained 
 breaking or tensile strains varying from 75 lbs. to 719 lbs. upon 
 21 square inches. Manufacturers produced cements of different 
 weights and quality. In his own case, he generally manufac- 
 tured cement weighing from 100 lbs. to 104 lbs. per bushel, and 
 he thought to make it from 112 lbs. to 114 lbs. was quite a 
 superfluous strength ; and when such a difference as between 
 75 lbs. and 719 lbs. was shown, it ought to be known whether 
 the same description of cement was used, otherwise the ex- 
 periment could not be regarded as a fair one. But the great 
 question to be considered was, the advantage to be gained by 
 having a cement stronger than the material it had to unite, 
 and therefore unnecessarily costly. 
 
 Mr. J. W. Bazalgette felt it to be his duty to bear testi- 
 mony to the great care which was taken by the Author in 
 conducting these experiments. The facts laid before the In- 
 stitution were nothing but the naked truth. He believed 
 that great good had been done by the tests ; that the manu- 
 facture of cement had been improved thereby ; and that Port- 
 land cement was destined to be used to a much larger extent 
 than it had been hitherto in engineering works. In many 
 cases Portland cement would bear admixture with sand, so as 
 to enable it to compete in price with common mortar, and 
 secure greater strength in the work at the same expenditure. 
 The time would probably arrive when all Engineers would test 
 
64 
 
 THE STRENGTH OF CEMENT. 
 
 their own cement, and would obtain the best that was to be had ; 
 and those tests would give more confidence than the character 
 of any firm, although much value should always be attached to 
 the character of the manufacturer, and would yet improve the 
 manufacture of cement. He regarded the test of weight as one 
 of considerable importance. It had been ingeniously suggested 
 that the weight of 112 lbs. per bushel was adopted because it was 
 1 cwt. ; and twenty sacks of cement made a ton ; but, as would 
 be seen from the Paper, 110 lbs. to the striked bushel was first 
 adopted, not 1 cwt. That weight was selected after careful ex- 
 periments ; and if, after obtaining these results, it was found by 
 further experience and experiments that it might be increased 
 with advantage, it was a proof that an excessive weight had not 
 been chosen in the first instance. That the heavier cements 
 bore the greatest strain was clearly found to be the case. An 
 examination of the tables would show that, as a rule, the 
 cement burned to weigh 112 lbs. and upwards ^vould bear a 
 considerably greater strain than cement of less weight ; that it 
 was in fact the best, and there was no exception to that rule. 
 A manufacturer's experiments upon his own cement could 
 hardly be accepted, in contrast with experiments made by im- 
 partial and independent persons upon the cements of various 
 other manufacturers, taking the cement from the bulk — good 
 and bad together — and gauged perhaps not under the same 
 advantages as would probably be secured by the manufacturer 
 testing for himself. Then it had been argued that if the 
 cement was stronger tlmn the materials which it had to unite, it 
 was not surprising that the manufacturer should be unwilling 
 to raise the standard of quality. But he had yet to learn that 
 any cement had been obtained which was " too good." When 
 that pitch was arrived at, it could readily be diluted with a 
 larger amount of sand, and its cost and its strength could be 
 reduced at pleasure. It was the Engineers' duty to raise the 
 standard of quality, and when it had fairly been determined 
 what was the best material, it would always command its price 
 in the market, and that would determine the question which 
 was the most marketable article to produce. 
 
 With reference to the setting of Portland cement in running 
 water, he did not know that there was greater objection to 
 using Portland cement in running water than any other kind of 
 
THE STRENGTH OF CEMENT. 
 
 cement. If care were not taken, all cements would be washed 
 out by the mechanical action of the water ; therefore the more 
 rapidly it set, the less it was subject to that action, and 
 the more cement was retained. In his experience, Portland 
 cement did set perfectly well under water; but with any 
 cement, if concrete was loosely thrown into the water, the 
 gravel would descend to the bottom more rapidly than the 
 cement, because its specific gravity was greater, and thus con- 
 crete so used would become deteriorated in quality. 
 
 Mr. KiNiPPLE remarked that the Author had stated that 
 " Portland cement concrete, made in the proportions of 1 of 
 cement to 8 of ballast, in some cases, and of 1 to 6 in others, 
 had been extensively used for the foundations of the river wall, 
 piers of reservoir, and foundations generally at Crossness and 
 Deptford, with the most perfect success." Now to have obtained 
 such perfect success, it must have been absolutely necessary to 
 have kept the entire works clear of water, for it was not possible 
 to get good concrete under water, whether quiet or not, if it 
 was thrown in dry immediately after mixing. He had ascer- 
 tained that in only 1 inch of quiet water, concrete, made in the 
 proportions of 3 to 1, was endangered by the working out of the 
 silicates, or the best of the cement, from the ballast ; those sili- 
 cates resembled slime on the surface, and with the slightest 
 motion or run of water were lost. In concreting an outer 
 apron just inside a coffer-dam at low water, he had used Portland 
 cement concrete, in the proportions of 4 of ballast to 1 of 
 cement. It was all put in at the same time, in the same 
 manner, with the same cement and ballast, and by the same 
 men, and was allowed to remain in quiet water for three 
 months. When he had again occasion to examine it, the con- 
 crete nearest the abutments was sound and hard, but in the 
 centre, or rather in the part last closed in, it was quite soft ; in 
 fact it was ballast, with a mere fraction of cement retained in it. 
 This was executed in aboat 2 inches of quiet water, and had to 
 be removed for the insertion of fresh concrete. To avoid this 
 for the future, he had resolved that all Portland cement con- 
 crete should be mixed on the surface, and allowed to set for 
 several hours ; the length of time for setting to be in propor- 
 tion to the quantity of the cement used, and when set, to be 
 used in a crumbled condition. By experiments he found that 
 
66 
 
 THE STRENGTH OF CEMENT. 
 
 he was able to retain nearly the whole of the cement, without 
 any loss as to strength. 
 
 He then referred to several specimens which he exhibited. 
 No. 1 was composed of 1 part of Portland cement, weighing 
 114 lbs. to the bushel, and 1 of fine river ballast; this was 
 thro-wn into 6 inches of quiet water, dry, immediately after 
 being mixed, and was submerged eighteen days, at the expira- 
 tion of which time it showed the great separation, even iu quiet 
 water, which had taken place. Specimen No. 2, similarly com- 
 posed, was also thrown into 6 inches of quiet water, but not 
 until it had been allowed to set, after being mixed for five 
 hours in the open air, previously to being submerged for 
 eighteen days. This specimen was so hard that it had to be 
 split by a cold chisel and hammer, and had retained nearly the 
 whole of the cement. Passing dry concrete down shoots would 
 not prevent the separation, as the larger stones rolled out and 
 set the cement free. If mixed and allowed to set a day or so, it 
 would without doubt be a success. As to the mode of executing 
 brickwork free from a current of water, he agreed generally 
 with the Author, but he did not think that all bricks should 
 be thoroughly saturated with water. For tidal work, such as 
 wharf walls, river wings, &c., Koman cement stood the " wash " 
 best, lias lime next, and Portland cement last. A joint was 
 seldom lost in Eoman cement compo brickwork, in lias lime 
 mortar now and then, but in Portland cement compo there was 
 great difiiculty in preventing sometimes six or more courses 
 being destroyed in one tide, from the loss of the joints. Port- 
 land cement brickwork, covered twice by water iu twenty-four 
 hours, should be made with compo as stiff as it was possible to 
 use it. The bricks should be perfectly dry, cleansed from the 
 maker's sand, the face joints raked out for a depth of 1 inch 
 whilst green, and pointed, temporarily, with Rochester yellow 
 clay. The clay joints would last many days, and by the time 
 the clay joints were washed away, the cement work would be 
 perfectly set, and could then be pointed in neat cement. Work 
 executed in the manner described seldom failed, and was free 
 from many of the consequences of the running of the joints. 
 Complaints were often made of the badness, or rather of the 
 irregular qualities of Portland cement. He believed, in many 
 cases, those complaints were chiefly due to the manner in 
 
THE STRENGTH OF CEMENT. 
 
 67 
 
 which it was applied to uses so varied in their character. He 
 would recommend, for all brickwork executed under water, that 
 the joints of compo should be dispensed with, that the bricks 
 should be coated with compo, and be allowed to set out of water 
 some hours, and be then rubbed together in position under 
 water. Specimen No. 3 showed nine bricks moulded, or coated, 
 in neat Portland cement, of an average thickness of 3-16ths of 
 an inch, allowed half an hour to set in the open air, rubbed 
 together into the present form in agitated water, and kept sub- 
 merged for eighteen days. Specimen No. 4 showed a better 
 result. Nine ordinary stock bricks were coated, as before, in 
 neat cement, then allowed five hours to set in the open air, 
 afterwards rubbed together under agitated dirty water, and 
 kept submerged for eighteen days. Both these experiments 
 went to prove that jointless work in almost any working depth 
 of water, whether clear or muddy, or where there was a great 
 current, could be executed with perfect success. The specimens 
 were not disturbed from the time they were submerged until 
 they were taken out, when the work was found to be thoroughly 
 sound. 
 
 The statement as to the making of a joint to a mining pump 
 pipe, under water at a considerable depth, was interesting, and 
 proved what might be done with Portland cement under water. 
 Joints might be caulked under water with cement nearly set, 
 and broken in pieces about the size of a pea. He had fre- 
 quently made use of neat cement for grouting between sheet 
 piles, with perfect success ; in one case under water, the cement, 
 in its descent or settling down, drove out the clear water, and 
 filled every crevice ; within ten days it was hard enough to 
 resist a chisel point. Model No. 5 showed blocks of concrete 
 coated with compo in the same way as the specimen bricks, 
 guided into position by rods or chains, built on a concrete 
 foundation, the face joints caulked with cement or soft wood 
 wedges, and the chains or light rods grouted in with neat 
 cement. 
 
 Mr. Kinipple added that the concrete out of which the 
 cement had been washed was mixed in the ordinary way. He 
 suggested, in order to ensure success, that the proportions should 
 be accurately measured in the usual way, mixed together dry, 
 and water added by means of a common watering-pot; the mass 
 
 F 2 
 
68 
 
 THE STRENGTH OF CEMENT. 
 
 then turned over, and afterwards separated and allowed to 
 remain for some hours in layers of 3 inches or 4 inches thick, 
 exposed to the open air ; and when it became so tough that it 
 would not receive an impression from the hand, it was ready to 
 be turned over again and passed into the water. By working 
 it in that way he had retained the whole of the cement. 
 
 Mr. John Aird, jun., said, from the opportunities he had 
 had of witnessing the experiments conducted by the Author, he 
 could bear testimony to the great care bestowed on them. He 
 believed they had been carried out in the most conscientious 
 manner, and with every desire to do justice to all the manufac- 
 turers whose cement was operated upon. He thought there 
 was some mistake as to the concrete being thrown in quite dry. 
 That certainly was not the plan adopted at Deptford; for there 
 it was previously mixed with a moderate amount of water, then 
 thrown into the work, and in all instances where Portland 
 cement was used it was perfectly successful. In his opinion, 
 the quality of the cement could not be too good ; but having 
 got that, the Engineer must look to the nature of the work to 
 be carried out, and determine the extent to which inferior 
 materials (always more readily obtainable) should be employed. 
 With regard to the influence of water upon cements, his expe- 
 rience led him to believe that Eoman cement was better suited 
 in some few cases. For instance, for facing work to river walls, 
 when it was subject to the rise and fall of the tide. The pro- 
 bability was, that even if the greatest care was taken, Portland 
 cement would, to a certain extent, be washed away. Much 
 better results would be obtained by the use of Roman cement, 
 as that soon set, and became quite firm before the water rose 
 and destroyed it. 
 
 Sir Charles Fox would mention an interesting instance, in 
 which the difiSculty of putting concrete into running water was 
 successfully overcome in a simple manner. In forming the 
 foundations of the Rochester bridge, the cylinders were sunk 
 42 feet below the bed of the river ; being a tidal river there 
 was in those cylinders a good deal of what the workmen called 
 " breathing ;" in other words, the water rose about a foot at 
 the bottom of the cylinder, and then receded, and continued to 
 rise and fall as it was supposed by simple momentum. It was 
 found that, as a consequence, all the cement in the concrete. 
 
THE STRENGTH OP CEMENT. 
 
 69 
 
 when placed at the bottom of the cylinder, was washed out and 
 came to the surface, so that for 9 inches or 10 inches at the 
 bottom only ballast remained. The difficulty was got over in 
 the following manner : — A quantity of concrete having been 
 prepared, a piece of stout canvas sail-cloth, such as was used 
 for hose -pipes, was cut one foot larger in diameter than the 
 bottom of the cylinder. When the water subsided, the sail- 
 cloth was spread over the surface at the bottom of the cylinder, 
 to which it was well fitted all round, and when covered with 
 about 2 feet of concrete, it held down the water until the re- 
 maining concrete was deposited safely upon it. In that case 
 Portland cement was used. The same plan was adopted with 
 all the cylinders for those foundations. 
 
 Mr. G. Dines remarked that he had had considerable expe- 
 rience with Portland cement, from its first introduction to the 
 present time, and had experimented largely, both for himself 
 and for the late Mr. Thomas Cubitt, as to its tensile, trans- 
 verse, and crushing strengths. The strongest piece of Portland 
 cement he had tried broke with a strain equal to 739 lbs. per 
 square inch, the average was 558 lbs. The pieces experi- 
 mented on were made of neat cement, without sand. That 
 material was much stronger than Portland stone, which bore a 
 tensile strain averaging 332 lbs., while Sicilian marble was 
 equal to 1073 lbs., or double that of Portland cement. For 
 brickwork and river walls Portland cement was most valuable, 
 and it was sometimes used in ordinary mortar, if the mortar 
 was required to be of extra strength. When it was used for 
 stucco it frequently gave much trouble, and the makers had 
 yet something to learn about its properties. It was very dif- 
 ferent to Eoman cement, as regarded expansion and contrac- 
 tion ; and for purposes for which he had used Portland cement 
 he was obliged to go back to Eoman. Some long pieces of 
 Eoman and of Portland cement had stood in his office for some 
 time, and he found the Portland cement, although made per- 
 fectly straight, was twisted like a piece of green deal, while the 
 Eoman cement remained perfectly true. He had seen Portland 
 cement, where used for the coping of a wall, buckled up, so as 
 to let the light through between it and the wall, and when he 
 began a work with Portland cement, he hardly knew when he 
 should finish it. He feared that it had a corrosive effect upon 
 
70 
 
 THE STRENGTH OF CEMENT. 
 
 iron ; therefore when cement had to be in contact with iron he 
 always used Koman. 
 
 Mr. Scott Eussell said Portland cement had been exten- 
 sively used in the insides of ships, to preserve the iron from 
 corrosion ; and after eighteen years' use, he had seen Portland 
 cement dug out of an iron ship, when the red-lead paint and 
 the skin of the iron were as sound as on the day they were put 
 there. 
 
 Mr. Heney Maudslay said this fact appeared to show that 
 the cement had not been in actual contact with the iron, as it 
 was protected by the red-lead paint, to the extent probably of 
 two or three thick coats. The caution raised with reference to 
 the effects of Portland cement in contact with wrought iion had 
 been made upon the supposition of fact which did not appear to 
 exist. 
 
 Mr. Scott Eussell observed that the inference to be drawn 
 from Mr. Maudslay's observation would be that wherever cement 
 was used with iron, the iron should be painted with red-lead. 
 
 Mr. Joseph Jennings said that when he had used Eoman 
 cement, where it was subject to tidal influence, it had produced 
 sound work, although the tide had returned in five minutes ; 
 while Portland cement, under the same circumstance!^, had 
 become perfectly fluid. He had used Portland cement for 
 filling up, as concrete, between stones at the bottom of a river, 
 and had experienced the difficulty occasioned by the cement 
 washing out, and he had found, upon examination by divers, 
 six months or eight months afterwards, that the Portland 
 cement which had been put in between the stones with trunks 
 and divers had washed out, whereas the Eoman cement, with 
 which the bottom of another lock had been repaired when the 
 water was out, stood perfectly well, although the water was 
 allowed to flow over it within five minutes after the time of its 
 being put in : yet for many purposes of construction Portland 
 cement was no doubt a most valuable material. 
 
 There was one point which he thought had not been quite 
 sufficiently considered in the Paper, which was, that of the 
 extent to which cement might be used in the form of concrete 
 blocks, in buildings. He believed that, in a few years, a much 
 larger proportion of cement blocks would be used for building 
 purposes, such as dock walls, in the same way as they were 
 
THE STBENGTH OF CEMENT. 
 
 71 
 
 now used at Dover. With this heavy Portland cement a large 
 portion of gravel and sand could be mixed, and by that means 
 much stronger work could be executed than any brickwork in 
 general use ; and therefore it was most important to consider 
 in what form the Portland cement could be most profitably 
 employed in these concrete blocks, as an artificial stone for use 
 in London. At the present time the great expense of stone 
 was a serious consideration, but cement blocks, if large, would, 
 he believed, almost entirely obviate the use of stone for many 
 purposes. With regard to this point he should be glad to hear 
 how far the shingle, which was now being used, and which to a 
 great extent had been deprived of all angular points, had a dis- 
 advantage, as compared with the use of angular stones, in 
 forming these concrete blocks. He was not aware that it had 
 been used to any great extent in the form of angular gravel. 
 The blocks at Dover and at Brighton were all formed with the 
 ordinary sea shingle. Another point was the effect of fire upon 
 Portland cement, when employed in the construction of furnaces 
 of various kinds. As far as his own experience went, he 
 thought Portland cement would stand in furnace work better 
 than Eoman cement. 
 
 Mr. Thomas Bevan remarked, in reference to the Tables 
 appended to the Paper, that it would be found that the large 
 manufacturers, in high repute with foreign Engineers, supplied 
 cements with a breaking strain which, although equal to the 
 requirement, was lower than that of the firms which furnished 
 the chief quantities to the Main Drainage Works. No hasty 
 inference should be deduced from this. He was persuaded that 
 the Author would be the first to admit that those manufac- 
 turers could, if they liked, produce cement to break at a much 
 higher strain. It should be remembered that a high breaking 
 ' test could only be produced by an extra expense in the manu- 
 facture. It would cost at least 3d. to 4d per bushel extra to 
 break at 700 lbs. than it would to break at 500 lbs. If the 
 Autlior was consequently satisfied, as was the case at first, with 
 400 lbs., it was not surprising that those firms which had a full 
 demand for their cement, and a well-established business, should 
 be content when they gave from 500 lbs. to 550 lbs. ; as to have 
 given more would have occasioned a much enhanced cost. 
 While, on the other hand, it was perfectly intelligible that 
 
72 
 
 THE STRENGTH OF CEMENT. 
 
 other firms should be willing to incur a sacrifice, in order to 
 attain a higher result. As a manufacturer, he desired it to be 
 understood that there was no fair ground for any trade use 
 being made of these Tables, to the disparagement of the large 
 manufacturers. The comparison, moreover, of the breaking 
 tests of cement of the same specific weight, but made by 
 different manufacturers, could not, within certain limits, lead to 
 any conclusion, to the depreciation of either. Provided that he 
 was safely above the test of the Engineer, a manufacturer would 
 desire to make not only what would be most economical in 
 the burning, but what would be most safe. Attention had 
 been drawn to the necessity of working with a maximum 
 of chalk and a minimum of clay, in order to secure a high 
 breaking test. But even in more moderate tests it would be 
 found that a different breaking strain would result at the same 
 specific weight, according as more or less clay was used in the 
 composition. In fact, the more clay was used without deteri- 
 orating any of the qualities of the cement, except by a little 
 reducing the breaking strain, the "kindlier," to use' the lan- 
 guage of the workman, would be the cement ; and the more 
 chalk was used, within those same limits, the more " hungry " 
 and more difficult to work would be the cement, although it 
 would certainly bear a higher breaking strain. It was not to be 
 assumed therefore that if cements of the same specific gravity 
 broke unequally within certain limits, that there was neces- 
 sarily any superiority or better composition in the manufacture 
 of either, but only that one had more, or less, clay than the 
 other. He was of opinion that the test of 500 lbs. in seven 
 days was not an undue one ; practically, it was little, if at all, 
 more than the old test of 400 lbs., as that test was first used. 
 The application of a breaking test upon any briquette of Port- 
 land cement depended altogether upon the quantity of water 
 used in gauging it. Working men who constantly manipulated 
 these tests, after a time became exceedingly expert in gauging, 
 and insensibly acquired the habit of gauging with a minimum 
 of water. A brick made with a minimum of water would bear 
 a much higher strain than one gauged with sufficient water to 
 make a good stiff paste. Any Engineer who might doubt this 
 experiment would see it at once if he tried cement gauged 
 with two parts of sand, and broke the briquette against one 
 
THE STEENGTH OF CEMENT. \\ > ' 7^ 
 
 similarly composed, but to which was added a^>6(dMoSe ' bf 
 water. The results, as it would tell more when sand was'mixed, 
 would be 50 per cent. wide. It was well known by those who 
 were in the habit of supplying the French Engineers, that 
 the breaking machine in use by the Fonts et Ohaussees and 
 the Imperial Marine was widely different from that employed 
 by the Author, and at least 25 per cent, more unfavourable to 
 the brick. It was a simple clamp, and the brick was usually 
 broken with a jerk, by the gradual addition of weight in the 
 most primitive manner, while the Author's machine was a 
 regulated steelyard. Therefore, if the test was attainable upon 
 the French machine, it would be much more so upon one so 
 favourably constructed as the latter. The argument that a 
 good and highly breaking cement could be made of a less 
 specific gravity than 112 lbs. might be conceded ; but that the 
 same cement that would break well at 104 lbs. would break 
 still higher at 112 lbs. could not be denied. He was of opinion, 
 therefore, on the whole, that the actual test, so far from being 
 an inconvenience or a disadvantage to the manufacturer, was a 
 benefit, because it separated the genuine Portland cement from 
 many counterfeits that bore its name. An objection was taken 
 to a seven days' test, and an inquiry made if an earlier test 
 could not be used. The Admiralty had used a test of forty hours 
 and sixty hours, and his impression was that it was possible for 
 bad cement of one particular description to pass that test — he 
 meant over-limed cement; but certainly none of this could 
 pass a seven days' test. It would discover itself by defective 
 arrises and small cracks before that time. He thought the test 
 at seven days was the best, and that the tests of forty hours and 
 sixty hours were quite unsuitable for a slow-setting cement. In 
 forty hours and sixty hours cement of 104 lbs. to the bushel would 
 perhaps break as well as cement of 112 lbs., but it was in the 
 longer dates that the superiority of the heavier cement was to 
 be seen. If it was suspected that cement was over-limed, and 
 if it was desirable to form a judgment before seven days, a 
 small pat gauged neat might be put in water, immediately 
 after it was set, and left unprotected. The thin edges would 
 fly much more quickly in this way than would be the case in a 
 brick in a mould. It was interesting to hear that Portland 
 cement withstood a higher strain than the materials for which 
 
74 
 
 THE STRENGTH OF CEMENT. 
 
 it was used as mortar. It would seem that the argument that 
 such excessive strength was unnecessary should give way to 
 the consideration that with the possession of good cement — 
 cement stronger than the materials — it wa,s time to procure 
 better bricks and better materials. 
 
 Mr. J, A, LoNGRiDGE said a question was raised in reference 
 to the use of salt water in slaking cement and lime. He had 
 been accustomed for years to use sea water for that purpose, 
 and had always found it succeed quite as well as fresh water. 
 He had also largely used sand of the sea-shore, impregnated 
 with salt, and he had found the lime set as well with that as 
 with other sand, provided it was sharp sand. But a more 
 interesting case was that which was being carried out at Port 
 Said, in connection with the Suez Canal. The last time he 
 passed through Egypt he was informed by one of the Engineers 
 that salt water was being used for slaking the lime, and that 
 sea sand alone, and without any gravel or stones, was being 
 employed for the concrete for the piers. It was a bold experi- 
 "ment, but it appeared to be exceedingly successful. He had 
 since received from M. de Lesseps a copy of the specification, 
 according to which the concrete was made, accompanied by a 
 letter, stating that sea water was used exclusively, copies of 
 which are annexed. The blocks were about 11 feet 6 inches 
 long, by 5 feet by 7 feet, and they were required by the 
 specification to be made two months before being immersed. 
 The work done amounted on an average to about 220 cubic 
 yards per day. 
 
 (Copy.) 
 
 " Eenseignements sur les jetees de Port Sa'id. — No. 5968. 
 " Monsieur, « Paris, le 26 JDecemhre, 1865. 
 
 " En reponse a la lettre que vous avez adressde le 22 courant a M. le 
 President de la Compagnie, j'ai I'honneur de vous adresser ci contre, un 
 exti-ait du marche que nous avons passe avec Dussand freres pour la con- 
 struction des jetees de Port Said, extrait qui r^pond a la plus grande partie de 
 vos questions. 
 
 " Je dois ajouter pour completer ces renseignements que le ciment est traits 
 k I'eau de mer exclusivement, et que nous immergeons par jour environ 170 
 mdtres cubes de blocs de beton. 
 
 " Agreez, Monsieur, I'assurauce de ma consideration distinguee, 
 
 (Signed) " Cadiat. 
 
 " L'Ingenieur, Chef du Service de Paris, a Monsieur James Longridge, 
 Abingdon Street, No. 18, Westminster, a Londres." 
 
THE STRENGTH OF CEMENT. 
 
 75 
 
 " ExTEAiTS du Marche Dussand pour I'execution des Jetees de Port Said en 
 
 Blocs artificiels. 
 
 " Les jetees k construire doivent avoir, celles de I'ouest, une longueur 
 d'environ deux trois mille trois cents metres; celle de Test, une longueur 
 d'environ deux mille metres. 
 
 " Elles seront construites sur le meme profil, lequel prdsente un couronne- 
 ment horizontal de cinq metres de largeur, emergeant de deux metres au dessus 
 du niveau moyen de la Mediterranee, avec des talus a quarante-cinq degres. 
 
 " Les blocs auront trois metres quarante centimetres de longueur, deux 
 nidtres de largeur, et un metre cinquante centimetres de hauteur, soit, deduc- 
 tion faite des rainures, un cube de dix metres. 
 
 " Une partie du massif des jetees pourra etre faite avec des blocs de quatre 
 metres cubes, sous la condition expresse que les revetements ext^rieurs seront 
 composes exclusivement de blocs de dix metres. 
 
 " Les blocs de I'une et I'autre categoric seront formes de sable de la plage et 
 de chaux du Theil, dans la proportion de trois cents vingt-cinq kilogrammes 
 (325 kls.) de chaux en poudre seche pour un mhtre (1^- 3) de sable. La Cie. 
 se reserve le droit de faire varier le dosage de la chaux jusqu'k concurrence de 
 vingt-cinq kilogrammes (25 kls.) en plus ou en moins de la proportion indiquee. 
 
 " La chaux proviendra des fours de M. Savin de la Farge au Theil 
 (Ardeche), ou elle sera de toute autre provenance, donnant une chaux de 
 quantite egale et acceptee par la Cie. Toutes les enveloppes porteront la 
 marque du fournisseur. 
 
 " Les blocs demeureront soumis a la dcssiccation k I'air l^bre pendant deux 
 mois ou moins, sauf les reductions de delai qui pourra autoriser le Directeur 
 Ge'neral des Travaux en cour d'execution." 
 
 Mr. Longridge added, that Portland cement was not used at 
 Port Said, but a hydraulic lime brought from Theil, in Ardeche 
 — a lias lime, he believed, but the specification gave the name 
 of the manufacturer. His own experience had been chiefly 
 with hydraulic lime, and coral lime which had no hydraulic 
 properties, and witli the latter he had used sea sand for outside 
 work, and found it to set well. 
 
 Mr. Scott Eussell said he had been requested to inquire 
 what was the kind of sand with which the cement was mixed ? 
 He did not put this question from any impression of his own, it 
 was suggested to him by Mr. Harrison, who had had great 
 experience in the use of cements, and who said that, according 
 as the sand used with the cement had been formed by the sea 
 from one substance or another substance, he got most variable 
 returns; and that what was called Thames sand was mainly 
 the sand of flint, and on the other hand, the sand found on the 
 western coast was to a great extent formed from limestone. It 
 
76 
 
 THE STKENGTH OF CEMENT. 
 
 was therefore obvious if a fine sand formed from limestone was 
 mixed with cement, the result would be different from that of 
 sand which was formed from flint. He would ask whether any 
 experiments had been made in which the quality and nature 
 of the sand had been examined as closely as the quality and 
 nature of the cement ? 
 
 Mr. CocKBURN Curtis said his experience and observations 
 led him to believe that great advantage was derived from 
 mixing the mortar, cement, or concrete, intended to be used in 
 submarine, coast, or estuary works, with salt or brackish water, 
 of the same character as that in which the works would 
 eventually be submerged. The minute component elements of 
 salt water had not yet been ascertained with the degree of 
 precision which was essential in forming a correct theory on 
 this branch of the subject ; but able chemists had asserted that 
 it contained small proportions of acids, and it was probably by 
 those acids that the mortar and cement, if mixed with fresh 
 water, were acted upon when submerged. The difference in 
 specific gravity between fresh and salt water, although small, 
 was of sufficient importance to be taken into consideration. 
 Fresh-water rocks frequently became disintegrated when ex- 
 posed to the chemical action of salt or brackish water, and for 
 that reason he considered it desirable, in the construction of 
 such works in beton or concrete, to use the sand, shingle, or 
 other materials found on the foreshore or beach from which the 
 particles subject to the chemical action of salt water had 
 already been removed. 
 
 Mr. ViGNOLES said that more than twenty years ago French 
 Engineers employed salt water in making concrete blocks for 
 Algiers, but many of those blocks (whether from the fact of 
 their having been formed of concrete mixed with salt water, or 
 from some supposed chemical action of the waters of the 
 Mediterranean) had become disintegrated, and considerable 
 destruction had taken place, though the great mass still re- 
 mained in position. At the new port of Marseilles salt water 
 was used for the concrete blocks with greater success. It was, 
 therefore, of no recent application. He would observe, that 
 having been on more than one occasion compelled, in foreign 
 countries, to make his own hydraulic cement, he found the 
 great principle of perfection was drying the clay as much as 
 
THE STRENGTH OF CEMENT. 
 
 77 
 
 possible, either in the sun or by artificial means previous to 
 baking it. Having dried it in a more perfect manner than was 
 generally done, the degree of baking was regulated to be as 
 little as possible, done slowly, and only just sufficient to 
 accomplish the object without affecting the properties of the 
 clay. When so burned the material could be reduced under 
 rollers to an impalpable powder ; used in that state it was most 
 successful, and the specific gravity was higher than if it had 
 not been so perfectly treated. A scientific reason was thus 
 afforded in favour of weight, because the specific gravity 
 became a test of the good burning and preparation of the 
 cement. 
 
 Mr. C. B. Lane remarked that the axiom "no chain is 
 stronger than its weakest link," was an established mechanical 
 principle, and that the argument based on that principle had 
 not, he thought, been answered. It occurred to him that if the 
 Author, in making these experiments, had supplemented them 
 with a series of experiments upon pieces of brick clay cast in 
 the same moulds and properly burnt, he would, so soon as he 
 had arrived at equality of cohesion between the brick and the 
 cement, have solved the question not only mechanically, but 
 also commercially and economically ; and any expenditure for 
 procuring a material beyond the cohesive strength of the brick 
 was so much labour lost. Having arrived at what might be 
 called an equation of values, to endeavour to increase one side 
 of that equation without increasing the other appeared to be 
 incurring an expenditure which was hardly justified. With 
 respect to the argument of competition, more than one of the 
 great cement-makers had stated that they had not supplied 
 cement for these works. It therefore appeared that the limits 
 of competition had been rather narrowed than widened by the 
 processes followed. The great prospective advantages that 
 were anticipated, and which would in all probability be ob- 
 tained, when they did accrue would be for the benefit of future 
 works, but not for the works which had paid for them. With 
 respect to the relative merits of blue lias lime and Portland 
 cement, he thought that a great portion of these works might 
 have been constructed with blue lias lime ; at the same time 
 it might be argued that it was all-important, in the streets of 
 London, to use a material which would lead to the completion 
 
78 
 
 THE STRENGTH OF CEMENT. 
 
 of the work with the greatest rapidity ; but there were many 
 districts in which blue lias lime might have been substituted 
 for Portland cement (perhaps in most cases for concrete) with 
 a considerable saving of expenditure. 
 
 Mr. F. J. Bramwell thought that a humble view had been 
 taken of the duties of Engineers in high position, when it 
 was argued that it was not a part of that duty to experiment 
 for the benefit of posterity. For his own part, he believed an 
 Engineer eminent in his profession, and entrusted with large 
 and important works, could not do better service than to en- 
 deavour to raise the standard of work carried out under his 
 directions; and those who had inspected the character of the 
 work executed under the superintendence of Mr. Bazalgette 
 and Mr. Grant, must acknowledge that those gentlemen had 
 raised the standard of work in such a manner as to deserve the 
 thanks of the profession. 
 
 With regard to cement, he thought it one of the most im- 
 portant subjects that Engineers connected with structures in 
 brickwork could consider, because clearly there was no use in 
 having good bricks to build with, unless they had also good 
 means of fastening them together, that was to say, one great 
 difficulty Engineers had to contend with was the means of 
 attachment of the material ; therefore he thought time was well 
 bestowed upon the consideration of the question. Mr. Grant 
 came before them with so many years' experience, and with the 
 results of so many thousands of experiments, that it was almost 
 impossible for anybody, except those who had been engaged in 
 the manufacture, and had been in the habit of making daily 
 experiments, to speak with any confidence on this subject in 
 the face of the numerous experiments which had been made by 
 Mr. Grant. That gentleman had started in effect, that there 
 were three tests which the cement must satisfy before it could 
 be pronounced to be thoroughly good ; one as to strength at 
 various ages, neat and mixed ; the second as to the power of 
 resisting water ; and the third, the test of weight per bushel. 
 The latter test was the only one as to the propriety of which 
 any difference of opinion had been expressed. For his own 
 part he would say, as soon as he heard of the test by weight, he 
 was struck with the difficulty of correctly ascertaining what the 
 weight was, because he knew by experience that when dealing 
 
THE STRENGTH OP CEMENT, 
 
 79 
 
 with granulated matter it was almost impossible, even with the 
 greatest care, to get uniformity of condition in the respective 
 trails, that was to say, to get the same amount of granulated 
 material into a particular measure. In corroboration of this he 
 would state the results of what he had tried lately. A quantity 
 of cement was poured into a bushel measure by a man accus- 
 tomed to the work, and struck off level; it then weighed 107 lbs. 
 exclusive of the weight of the measure. Then another portion 
 of the same cement was poured slowly out of the sack down 
 an inclined board into the bushel measure, and it then weighed 
 only 97 lbs.; he then had it shaken down in the measure, 
 and the weight then got up to 132 lbs. When it was found, 
 therefore, with the same measure of capacity and with the same 
 material, there could be a variation of from 97 lbs. to 132 lbs., 
 he could not help thinking if a test of gravity could be obtained 
 which was not liable to those variations, it would be a very 
 desirable thing. Until the mode of ascertaining the weight 
 was altered so as not to be affected by the question as to 
 whether, in the trial, the cement was more compact in the 
 measure, he thought that the stipulation as to weight— though 
 probably the manufacturers did not wish to have any more tests 
 imposed— should be combined with that of sifting, so as to 
 ensure the fine grinding of the cement, as if this were not done 
 he thought the requirement as to weight was liable to act as a 
 premium for coarse grinding. In reference to this, he would 
 state that he had sifted through a sieve with 900 holes to the 
 square inch, a certain portion of the cement which weighed 
 as before stated, when very carefully put into the measure, 
 97 lbs., and when put in the ordinary way 107 lbs., to the bushel ; 
 those portions which would not go through the sieve were then 
 poured into the bushel measure with the same care as that 
 which made the unsifted weigh, as previously stated, only 
 97 lbs. ; with this care the coarse weighed as much as 101 lbs., 
 and when shaken down hard into the measure, 144 lbs., whereas 
 the unsifted cement weighed, as before stated, only 132 lbs. 
 He then took by themselves the fine particles which had passed 
 through the sieve, and they then weighed only 98 lbs. as 
 against 97 lbs., and, when shaken, 130 lbs. as against 132 lbs. for 
 the mixed and 144 lbs. for the coarse. He gathered from this 
 that weight, as ascertained by pouring the material into a 
 
80 
 
 THE STRENGTH OF CEMENT. 
 
 measure, was liable to extremely variable results, evi n when 
 the greatest care was taken ; and further, that unless it was 
 accompanied by the test of sifting there might and probably 
 would be badly ground cement present in the mass. That 
 being so, and agreeing as he did in the importance of the test 
 of weight, it occurred to him that a means of ascertaining the 
 true weight for cement might be adopted similar to that 
 which was employed for ascertaining that of gunpowder, and 
 which means had been shown to him by Mr. Abel, of Woolwich 
 A-rsenal. The mode pursued in ascertaining the gravity of 
 gunpowder was in effect this : — A vessel capable of containing a 
 known weight of mercury was employed ; then a known weight 
 of gunpowder was taken and put into the vessel, and thereby 
 a bulk of mercury equal to that of the grains of gunpowder 
 was displaced, and this exact bulk could be ascertained by the 
 diminished weight of the bottle. Thus the weight of the 
 cement having been known and its bulk ascertained, its specific 
 gravity was at once determinable. Mr. Abel kindly allowed 
 one of Mr. Bramwell's assistants to use the apparatus to test the 
 gravity of cement ; but it was found that the liquid used, viz. 
 mercury, was not suitable as a test for so finely powdered a 
 material as cement ; but by using turpentine as the liquid, the 
 gravity had been ascertained without difficulty, and he found the 
 specific gravity of the cement before mentioned, which, as put 
 into the bushel measure, weighed, as before stated, the 107 lbs., 
 was 3-11. Now 3 • 11, it would be found, was equal to a weight 
 per bushel of 249 lbs., so that if that cement could be obtained 
 in a really solid state, it would weigh 249 lbs. instead of 107 lbs. 
 120 lbs. cement was equal to a specific gravity of only 1 • 5, and 
 104 lbs. was equal to only 1-3 as it lay in the bushel. The 
 way in which the gravity was taken was this : — A phial, 
 holding when filled to a certain point a known quantity of 
 turpentine, was taken, and a certain weight of cement was put 
 into itv It was then filled up to the marked point; the con- 
 tents were weighed, and the excess of weight found was clearly 
 that which was due to the weight of the cement above that of 
 the turpentine which it displaced, and in that way the gravity 
 was ascertained. Whether it would be possible to employ so 
 refined a test as this in practice he was not prepared to say. 
 He thought Mr. Grant would tell them it was not. 
 
THE STEENGTH OP CEMENT, 
 
 81 
 
 Then came the next question, which was, whether this in- 
 sistance of great weight in cement was not likely to lead to 
 trouble — whether there ought not to be some limit put to it ? 
 Tiie manufacturers said, if they were bound to produce cement 
 of great strength and high specific gravity, it would cost them 
 more to make it, and they argued that it was better to use a 
 weaker cement with a less admixture of sand, than a stronger 
 cement obtained at a greater cost with a larger admixture of 
 sand. The heavy cement was obtained by hard burning ; and 
 when that was carried too far it was likely to cause the cement 
 to fuse into a vitrified mass, which was of no use whatever. To 
 prevent that it seemed there was an excess of chalk added, and 
 if the chalk were not properly burned there was danger of 
 that original defect of Portland cement, viz. that after it was 
 thought to have been set it blowed," from the lime not 
 having been fully acted upon in the burning. Therefore it was 
 well to see whether this 114 lbs. to the bushel was not as high 
 a specific gravity as was required, and whether the 120 lbs. was 
 a thing to be sought after ; because he could understand that 
 an Engineer, finding that the weight had been gradually raised 
 from 110 lbs. to 112 lbs. and 114 lbs., and that 120 lbs. was 
 attainable, might, in the desire to do the best, put into his spe- 
 cification cement of 115 lbs. to 120 lbs. weight per bushel, and 
 by so doing might do harm instead of good. There could be no 
 doubt that heavy cement set very slowly — not that at the end 
 of a week it had not great tensile strength, but that at the end 
 of an hour it was not in a condition to resist water so well as a 
 lighter cement. He might say, in passing, with reference to 
 the most desirable quality of cement for hydraulic works, that 
 the material which was left behind out of the cement, after 
 sifting through a sieve with 36 holes per linear inch, would not 
 set at all. After several days it crumbled like sand; and he 
 thought it would be well if chemists would determine whether 
 that difficulty in setting arose from a difference in the con- 
 stituents of the larger and harder particles, or merely from 
 their having escaped the action of the millstones. He had 
 found, even after pounding these particles fine enough to go 
 through the sieve, that often, if they set at all, it was in a very 
 poor manner. 
 
 The next point was as to the amount of water used in 
 
 G 
 
82 
 
 THE STRENGTH OF CEMENT. 
 
 gauging the cement for these experiments. He found, as a rule, 
 that about one fourth-part by weight of water was the least 
 quantity that would gauge the cement. If the cement were 
 very quick-setting, or if it were very fine, it could not be gauged 
 with so little water as that ; that was the least that could be 
 used with hard-burnt weighty cement. He had been curious to 
 see what the effects would be of gauging with different quan- 
 tities of water, and he found if only one-third weight of water 
 were used, a sample would break at the end of ten days with 
 244 lbs., while if one-half the weight of water were used, the 
 sample broke at the same period at 90 lbs. 
 
 Then he found that the resulting weight was nearly that of 
 the mixed materials. Taking an equal weight of cement in all 
 cases, viz. 30 oz., and mixing with 9| oz. of water (which was 
 the lowest quantity he could use), then with 10 oz. and then 
 with 15 oz. ; then pouring the mixture into square boxes, 
 2 inches square, the smaller amount of water gave a resulting 
 bulk of a height of 8 inches, the next of 8^ inches, and with 
 half water it gave a height of 10 inches. This showed that 
 there was great temptation to use water largely, as it went to 
 make bulk of the finished cement, although it was at the 
 expense of its cohesive powers. 
 
 It had been stated in the Paper that it was important care 
 should be taken as to the amount of water used in the gauging ; 
 but it had not been stated what proportions of water were used 
 in the experiments. Mr. Bramwell might state that in his 
 own experiments the specific gravity of the block made from 
 cement mixed with half its weight of water was only 1 • 83 (that 
 was taken at the end of four days), whilst the specific gravity 
 of that mixed with only one-fourth weight of water was 2 • 25. 
 
 A suggestion had been made as to whether they were 
 thoroughly acquainted with the different kinds of sand mixed 
 with the cement when those two materials were allied together. 
 In one of his experiments he took well-washed sand from the 
 Thames, and in another some pounded Portland stone, the sand 
 and the pounded stone being both sifted through the same 
 sieve, and there was no doubt as to the superior strength of the 
 cement block mixed with the pounded Portland stone ; but he 
 could not give the results with particularity, because a suffi- 
 cient time had not elapsed to show the full effect, but it was 
 
THE STRENGTH OF CEMENT. 
 
 evident the Portland stone was considerably the stronger of the 
 two. As regarded the way in which sand set with cement, it 
 was desirable to know what changes took place after a block of 
 this kind had set. He presumed, in the case of lime, that if 
 they used lime alone they got very bad mortar, but that when 
 mixed with sand it operated chemically upon the lime. The 
 necessity for sand did not, however, exist with Portland cement, 
 as that was strongest without any mixture of sand. It was a 
 question whether Jibe sand acted chemically, or merely as a 
 means of filling up' the spaces ; if the latter were the case, he 
 could understand that the larger grained the sand was, the 
 better it was for the purpose, even irrespective of its being 
 clean ; for he believed with large particles they had less cubical 
 contents of interstices than with small, as small particles did 
 not lie much closer than large ones, so that the thickness of the 
 interstices to be filled was nearly the same in both cases, while 
 the area of the interstices was much greater in small particles 
 than in large. A question had been raised with respect to 
 cement placed in contact with iron, which turned out to be a 
 question of cement upon oil. He might say, that having 
 occasion to form a deck upon a floating dock, which deck he 
 did not wish to be combustible, so as to be in danger if a hot 
 rivet fell upon it, nor to be liable to rot if temporarily immersed 
 in water in a tropical climate, and which therefore did not 
 admit of the use either of creosoted or of unprotected timber, 
 he had made every inquiry he could as to the behaviour of 
 Portland cement concrete in contact with iron, and he was now 
 Iiaving prepared a Portland cement deck 3 inches thick ; but 
 he was afraid that experiment \a ould not settle the question at 
 issue, because, after all, it would only be cement upon oil, all 
 the iron having been steeped in oil when hot. 
 
 It had been suggested that there were great probabilities of 
 cement with a large admixture of sand being used as a sub- 
 stitute for bricks. There was no doubt that good bricks had 
 attained to an extraordinarily high price. From the Paper it 
 appeared that the resistance to crushing of bricks, except the 
 very best gault bricks, was 5 tons, while with proportions of one 
 of cement to five of sand the resistance was on an average 
 12 tons. It was clear that in respect of crushing the cement 
 bricks were far better than the ordinary run of bricks; so 
 
 Q 2 
 
84 
 
 THE STRENGTH OF CEMENT. 
 
 much so, that he presumed it would be practicable to econo- 
 mize the material by making perforated bricks; but even if 
 they were made solid, he calculated that at the present time 
 they would cost 41s. 6d. per thousand. If the use of cement 
 were still further economized, so as to bring down the power to 
 resist compression at six months to that of ordinary bricks, 
 there was some prospect of the cement brick being able to 
 compete successfully with ordinary bricks. 
 
 Mr. J. B. Kedman said he thought there was force in the 
 remark that it was better to arrive at a high standard value for 
 cement than to keep it down to that of the material" to be 
 attached. At the same time, it occurred to him that the value 
 of the artificial material as evolved by these experiments, 
 compared with some of the natural stones, gave a very high 
 value to the former, and a very low value, in some cases, to the 
 latter. Looking to the comparisons of Portland cement with 
 Portland stone, the Author's tables gave the power of resisting 
 crushing weight of the latter as only 167 tons per superficial 
 foot, while Barlow gave a value of 294 tons per superficial foot. 
 Some experiments were made two years ago by a Committee of 
 the Eoyal Institute of British Architects, and in testing the 
 relative merits of Kansome and Co.'s and M. Coignet's cements, 
 and other materials, they found Portland stone gave a value of 
 from 240 tons per superficial foot to 326 tons. It was clear 
 therefore there was a wide difference between the observed 
 results as to the value of Portland stone. As regarded the 
 results brought out for the artificial material, Mr. Grant's 
 experiments gave to the Portland cement a crushing power of 
 412 tons to the superficial foot, while Mr. White's Paper,^ read 
 some few years back, gave only from 146 tons to 160 tons, as 
 shown by experiments made at the International Exhibition. 
 This had relation to crushing power. It had been suggested 
 that Eoman cement might be usefully employed in tidal works 
 in getting in deep foundations, and he might refer to a work 
 which he carried out at East Greenwich twelve years back, in 
 which a heavy river wall, subject to the tide twice a day, was 
 put in without coffer-dams. That wall, which had been perfectly 
 successful, was built in Eoman cement, faced with rough 
 
 > Vide ' Minutes of Proceedings Inst. C.E.,' vol. xi. p. 478. 
 
THE STRENGTH OF CEMENT. 
 
 85 
 
 Guernsey pitching blocks, which had the property of resisting 
 vegetation. A few years after that he built another M^all, on 
 the opposite side, in blue lias lime, on a base of concrete of 
 blue lias lime, also without coffer-dams, and that was equally 
 successful. He had also used concrete made with Koman 
 cement in excluding the water at a great depth below low water, 
 in a rapid tideway, in the bottoms of cylinder foundations. 
 
 Mr. J. F. Bateman, on the subject of hydraulic cements and 
 mortars, would state the mode of construction adopted by Mr. 
 Stoney for the Ballast Board at Dublin, for quay walls at that 
 port. The ordinary quay walls were of concrete formed of one 
 part of Portland cement to ten parts of the gravel of the Liffey. 
 The crushing power at three months was 16 tons to the square 
 foot, and this concrete was made at a cost of from 10s. 6d. to 
 10s. 8d. per cubic yard when set, exclusive of the cost of plant. 
 It was not set in blocks, but was deposited between planks, in 
 the ordinary way of making concrete walls. Owing to the 
 success of those walls Mr. Stoney had undertaken the formation 
 of concrete blocks on a larger scale than, he believed, had been 
 hitherto attempted, in the building of a wall 24 feet below low 
 water without coffer-dams. These blocks were made 23 feet 
 upon the base, 26 feet deep, and 10 feet upon the face, weighing 
 330 tons each. They were built on a strong platform formed 
 on the shore to carry this enormous weight, and were allowed 
 to remain as long as was necessary to harden before they were 
 removed. They were then floated to their destination, and 
 lowered to the base previously prepared for them, under a 
 large diving bell 20 feet square. The cost of these blocks, 
 formed of one part of Portland cement to six parts of the 
 gravel of the Liffey, and faced with granite, was estimated at 
 16s. per cubic yard exclusive of plant, and at 18s. with plant. 
 In fine weather they might be laid on an average of one block 
 at every tide ; but by supposing that only one block could be 
 laid every other day, or one hundred and fifty blocks in the 
 course of the year, they would form a wall 1500 feet long, at a 
 cost which was a mere bagatelle compared with other modes of 
 construction involving the use of coffer-dams. It was about ten 
 months since he investigated the question, and he could not 
 report Avhat had been done since. He could, however, speak 
 with confidence as to the stability, strength, and apparent 
 
86 
 
 THE STBENGTH OF CEMENT. 
 
 durability of the Myalls already constructed — those in which the 
 composition was one part of Portland cement to ten parts of 
 the gravel of the Liffey. 
 
 Mr. E. P. Breeeton said, doubts having been expressed as 
 to the advantages of the use of Portland cement in water 
 foundations, if passed through water either running or still, he 
 would state that he had had opportunities of using it very 
 largely under the latter condition. About seventeen years ago, 
 when Portland cement was first thought of for foundations 
 inside of cylinders, the late Mr. Brunei was employed in 
 building a bridge across the Thames at Windsor. It was at 
 that time stated that Portland cement answered well, used in 
 the proportion of one part of cement to ten parts or twelve parts 
 of gravel, and in that way formed an economical mode of filling 
 up foundations in the water. In putting it in through water it 
 was not considered prudent to try it in those proportions, but it 
 was tried with one part of cement to nine parts of ballast. The 
 cylinders were sunk through the gravel without pumping, and 
 they became full of water through the bottom and under the 
 sides. Through that water the concrete was passed, after being 
 properly mixed, and it set hard and well in eight or ten days. 
 The result of the first experiment was surprising. On pumping 
 out the water there was on the top of the concrete a thin layer 
 of slime and matter, which led to the expectation that the 
 cement had been washed out of the concrete in its deposition, 
 and for satisfaction on that point the concrete was carefully 
 examined. It had set very hard, and on drilling nearly 3 feet 
 into the concrete no amount of drilling, consistent with reason, 
 could make any further impression. This proved that the slime 
 was due to only a very small portion of the cement that had 
 been washed out, and that the great bulk of it remained in the 
 concrete ; the proportions were afterwards increased to 1 to 6. 
 The result of the experiment led to the use of that concrete 
 very largely in subsequent bridges, and it was deposited in 
 depths even of from 50 feet to 70 without the least attempt at 
 pumping. When sufficient concrete had been deposited to 
 balance the water pressure, and when, after ten days or a fort- 
 night, it had set, the water was pumped out of the cylinders, 
 and the remainder was filled in with concrete of the ordinary 
 kind. 
 
THE STBENGTH OF CEMENT. 
 
 87 
 
 Those instances were sufficient to prove that concrete was 
 good for all purposes so required of it. Those foundations, 
 which had been built sixteen years or eighteen years, showed 
 no symptoms of failure. With regard to the setting properties 
 of this cement when used with sea sand or otherwise, he had 
 found the use of sea sand and salt water perfectly satisfactory, 
 both with Portland cement and lias lime ; but there was no 
 question as to its setting being rather retarded by that course. 
 A few weeks ago, at some works in Wales on which he was 
 engaged, in a tideway, he used cement mixed with sea sand 
 and salt water, but it did not set quickly enough. He then 
 tried the blown sand taken from the hills, not wet, and mixed 
 with fresh water, and the cement set satisfactorily, whereas if 
 the sand was saturated with salt water it took a longer time to 
 set. In the case of lias mortar, so long as it was not subject to 
 the wash of the sea it might be covered with water ten minutes 
 after it was put in, and would set perfectly well, but not so 
 quickly as if used in the dry state. 
 
 Mr. Fowler, President, inquired whether, in passing the 
 concrete through deep water, wooden spouts were used for the 
 purpose ? and whether Mr. Brereton's remarks, as to the com- 
 parative speed of setting of cements mixed with sea water and 
 of those mixed with fresh water, had reference to works under 
 water or above the surface ? 
 
 Mr. Brereton replied, that at Windsor, with a depth of 
 12 feet to 18 feet, the concrete was lowered in bags holding 
 about IJ- yard at a time, and it was discharged at the bottom. 
 The same plan was adopted elsewhere in deeper water upon a 
 larger scale, but a different disengaging apparatus was used. 
 The result of his experience as regarded the speed of setting 
 was, that the cement did not set fast enough before the tide 
 rose when saturated sea sand and salt water were used. The 
 work referred to was that of the invert of a dock entrance. It 
 was put in when dry, but the tide rose before the cement had 
 time to set ; with the blown sand it set in half an hour. 
 
 Mr. John Coode submitted that the average results given in 
 the Author's tables, if taken without reference to the extreme 
 results, were calculated to mislead. The Board of Works test 
 was 500 lbs. on the briquette. Now 500 lbs. might be a mean 
 or an average of 499 lbs. and 501 lbs., so would it be also a 
 
88 
 
 THE STRENGTH OF CEMENT. 
 
 mean of 1 lb. and 999 lbs. It would be desirable to ascertain 
 what proportion of the cement of each maker had been below 
 or above the required standard, and in what degree, so that the 
 degree of superiority which the cement of one maker possessed 
 over that of another might be known. There appeared to be 
 an extraordinary range in the results, varying from 75 lbs. to 
 719 lbs. (Table II.) He thought it desirable also to have some 
 experiments made on the relative strength of concrete formed 
 with Portland cement and of that made with blue lias lime. 
 (Table XLI.) He quite agreed that probably Portland cement 
 would be used much more extensively than it was at present. 
 Hitherto this cement had been rather dreaded. He was so 
 satisfied with it that he had, some twelve months since, speci- 
 fied for the construction of a pier facing the German Ocean, 
 and exposed to the " fetch " of a sea of from 190 miles to 200 
 miles, the whole of which, from the foundation courses upward, 
 was to be of Portland cement concrete blocks, the face of the 
 work, both seaward and towards the harbour, being of the 
 same material, and he believed it would prove, both in point of 
 strength and durability, to be equal to any orjlinary building 
 stone. In point of cost, it involved the question of building 
 the pier in that material or not at all, for if the pier had been 
 faced with stone, the expense would have been beyond the 
 funds at the disposal of the authorities of the harbour in ques- 
 tion. He was led in a great measure to adopt that material in 
 the face of the work from having seen the result of the action 
 of the sea upon a pier at Hartlepool. Some of the members 
 might be aware that in the year 1856 a pier was projected in 
 Hartlepool bay, which was stopped somewhat abruptly by Act 
 of Parliament, and the work was left with the bare ends, both 
 of the face-stones and concrete blocks in the hearting, stepped 
 back in the ordinary way. He examined it after seven years' 
 exposure to the action of the sea, and he found that the arrises 
 of the Portland cement blocks — though they were not of first- 
 class quality — were quite as sharp as those of the Bramley Fall 
 stone with which the pier was faced. He had the authority of 
 Mr. James May for saying, that the experience of more than 
 fourteen years at Alderney had shown that the blocks of con- 
 crete made with Portland cement indurated with time rather 
 than disintegrated. This seemed to be a reason for making 
 
THE STRENGTH OP CEDENT. 
 
 89 
 
 experiments upon the relative strength of concrete made with 
 Portland cement and with different proportions of shingle and 
 sand. He would also observe that amongst all the experiments 
 made with that cement, he was not aware of any having been 
 made with reference to its resistance to the action of attrition 
 or abrasion. That was a quality which Portland cement pos- 
 sessed in a remarkable degree, and experiments in that direc- 
 tion might be worth the attention of manufacturers, and would, 
 he anticipated, exhibit some extraordinary results, which would 
 be very useful, and encourage the larger use of the material. 
 Sea walls or piers faced with concrete blocks, and exposed to 
 heavy seas, would not only have to resist the shock of the 
 waves, but also the severe test of the attrition due to the 
 moving sand and shingle, which were always found to tell con- 
 siderably upon such works at the ground line in shallow water, 
 and this was one of the greatest enemies to contend against 
 in works so founded. In reference to the remarks upon the 
 relative strength of test blocks when made with different 
 descriptions of sand, it had been stated that in one experi- 
 ment granulated Portland stone had been used as sand. The 
 strength in that case depended upon mechanical adhesion, due 
 to the porous and absorbent character of the material used as 
 sand. Some years ago he had cemented together a pair of 
 granite blocks, a pair of Portland Eoach blocks, and a pair of 
 blocks of ordinary Portland stone, all of the same sectional 
 area, and he had found the relative amount of adhesion to be 
 represented by 11 in the case of granite, 12 in the case of 
 Portland Eoach, and 16 in the case of the ordinary Portland 
 stone — results which he believed to be simply in ratios cor- 
 responding to the porosity of the different stones. 
 
 His experience with Portland cement for works in an open 
 tideway had not been altogether satisfactory, and he could not 
 agree that it could be used for all purposes in a water-way. 
 He first tried it about twelve years since, in attempting to set 
 some large ashlar stones in a tideway at about 18 inches above 
 low-water level. The blocks having been set, and a mere 
 ripple— not to call it a wave — coming upon them, the cement 
 was fairly pumped out of the joints. That, perhaps, was the 
 strongest test to which a cement or mortar joint could be 
 exposed, viz. the kind of pumpiug action which kept the whole 
 
90 
 
 THE STRENGTH OF CEMENT. 
 
 body ot cement in motion, and that action was more destruc- 
 tive in a straight ashlar joint than in rubble masonry. With 
 regard to the export of Portland cement, the best and cheapest 
 mode of conveyance on long voyages was by packing it in 
 wrought-iron tanks, measuring about 4 feet each way as a con- 
 venient size, instead of in casks. Thus protected it always 
 arrived at its destination in first-rate condition. He had on 
 several occasions sent cement in that way to some harbour 
 works he was executing without a contractor in South Africa. 
 It resisted all moisture and damp on the voyage, whether from 
 leakage of the vessel or any other cause, and the iron tanks 
 had been sold in the colony generally for the same money, and 
 in some cases even for more, than they had cost in this country. 
 
 Mr. Beeketon explained that he had never used Portland 
 cement concrete in a tideway ; but in deep still water he had 
 done so. 
 
 Mr. John Hawkshaw, Past-President, said he had used 
 Portland cement in a tideway, and had not experienced any 
 difficulty in so using it. Neither had he experienced difficulty 
 in using concrete blocks in similar situations. In positions 
 where the water was rough he took the precaution of immedi- 
 ately pointing the surface joints with Medina cement, which set 
 very rapidly. As to the setting of concrete in water, he had 
 passed it by means of boxes through 70 feet of water, and with 
 the usual precautions it succeeded. In Italy he had seen sea 
 walls built in 20 feet of water without passing the concrete to 
 the bottom in boxes. Nothing more was done than to mark 
 out the outline of the wall by piles boarded on the sides. It 
 was mixed very rapidly, and a large number of men and boys 
 were employed to carry it away in small quantities and throw it 
 where it was to be deposited. Extensive sea walls were built in 
 the Mediterranean in that way. 
 
 There could be no doubt that within his own experience the 
 manufacture of Portland cement had been greatly improved, 
 and it could now be relied on to an extent which could not have 
 been done formerly. Therefore he could quite understand how 
 the tests had been increased from time to time. He had so 
 much confidence in it, that he was now commencing a large 
 harbour on the Dutch coast, at the mouth of the Amsterdam 
 sea canal, the piers of which were to be carried out a mile and 
 
THE 8TBENGTH OF CEMENT. 
 
 91 
 
 a quarter into the sea, and he proposed to build them of blocks 
 of concrete made with shingle and Portland cement. He 
 agreed that these blocks, when well made, appeared to retain 
 their forms and preserve their surfaces equal to those of any- 
 stone which was used for these purposes. 
 
 With regard to the experiments where, by using a larger 
 proportion of water, larger-sized cubes were obtained, he did 
 not think they could ^be taken as a safe criterion, unless a con- 
 siderable time was allowed for the concrete to dry. He did not 
 gather that this had been the case ; for there could be no doubt 
 that cubes made of Portland cement and sand did go on im- 
 proving for a considerable period. Some such cubes were in 
 the room which had been made ten years ago, and they had 
 evidently hardened with time, for he had lately made similar 
 cubes and compared the two. Those he had made were of the 
 finest sand (similar to that of the Dutch coast) and Portland 
 cement, varying in proportions from 1 in 4 to 1 in 10. He 
 believed blocks made in that way, could they be given time 
 enough, would answer in some situations. The difficulty in 
 using sand and cement arose from the fact that blocks so com- 
 posed took a long time before they could be handled. The fact 
 that no shingle was to be found on the coast of Holland had 
 caused his attention to be directed to the Hse of sand alone for 
 hearting or internal blocks. Since he had visited the Suez 
 Canal he had been informed that there was some idea of 
 making the piers at Port Said of blocks of sand and cement 
 only, and no doubt, where there was time to wait till these 
 blocks became hard, they would be suitable for portions of the 
 work. Portland cement had the remarkable quality that it 
 indurated to a higher extent in water than in air. That was in 
 itself a great advantage in sea works. One thing which gave 
 him confidence in adopting concrete blocks so extensively as he 
 had done was what he noticed some years ago at ports on the 
 Mediterranean. He endeavoured to ascertain the age of some 
 concrete blocks which he saw in an old pier at one of those 
 ports, not built, but thrown in as j^ierre perdue, and as far as 
 he could make out, those blocks had been made about one 
 hundred years. They were not perfect in form, but they had 
 not been made with the care with which blocks were made at 
 the present time for works of that kind. 
 
92 
 
 THE STKENGTH OP CEMENT. 
 
 As to how far Engineers should stop short of securing the 
 best material they could get, of course that was a question 
 which, could not be solved by any specific resolution. If they 
 had only a little money, they must make the most of it, and 
 buy what materials they could afford. The Metropolitan Board 
 of Works had plenty of money, and a large constituency to fall 
 back upon, and they were not to blame for having tried to 
 secure the best kind of work. The Author of the Paper had 
 made numerous and careful experiments, and had presented 
 them in a clear 'and lucid form ; at the same time it would be 
 a mistake to suppose that this was the first extensive use of 
 this material, or that the experiments were very new. Many 
 Engineers had used Portland cement for years, and many had 
 made careful experiments with it. He agreed with the Author 
 that weight was a test of quality, though that test alone could 
 not be relied upon. 
 
 He had used lias lime extensively, and had found that when 
 exposed to sea action and when mixed with pozzolana it some- 
 times softened to a very small extent upon its exposed surface. 
 This fact would not be discovered unless the surface were ex- 
 amined minutely. In the interior of the work it would be quite 
 hard, but where it was exposed to the sea a thin film would be 
 found softened by the sea water ; he had not yet observed that 
 Portland cement was so affected; whether it was in conse- 
 quence of using pozzolana he could not say. With regard to 
 pozzolana, it was, he thought, in many cases a mistake to apply 
 it to hydraulic limes. It was much esteemed by the old 
 Engineers, who knew that the Romans used it to a great extent, 
 and their works were regarded as being of a very enduring 
 character. He had taken the pains to examine almost every 
 important work in Italy. He had seen most of the aqueducts, 
 and he found that pozzolana was always used ; but the Italians 
 mixed it with common white lime, and with that lime it made 
 a good mortar ; but he was inclined to believe the combination 
 of pozzolana with hydraulic or lias limes was not in every case 
 beneficial ; and it would be better, where good lias lime was to 
 be had, to leave out the pozzolana. 
 
 Mr. E. Druce referred to the specimens which showed the 
 results of Portland cement mixed with different proportions of 
 sand up to 1 to 10. These specimens were mixed by himself just 
 
THE 8TEENGTH OF CEMENT. 
 
 93 
 
 ten years ago, and were, he thought, of special interest, as show- 
 ing the cement in its ultimate state of hardness. There was also 
 a piece of a Portland cement block, which bore upon the point 
 alluded to as to the abrasion of a Portland cement concrete by 
 shingle, it having formed, during a period of six years, the outer 
 corner of a sea- shore groyne on the coast of Sussex, round which 
 very large quantities of shingle had been constantly passing. It 
 was part of an ordinary Portland cement concrete block, made 
 in the proportions of one part of cement to nine parts of shingle 
 and sand. The abrasion had been very slight, and the cement 
 had shown no signs of weakness, nor had any stones been dis- 
 placed. He would now direct attention to the appeal of the 
 cement manufacturers in behalf of light cement as against heavy, 
 or more highly manufactured cement, the statement being that 
 cement of 104 lbs. to the bushel was, for all practical purposes, as 
 good as that of 114 lbs., and a table of results was brought 
 forward in proof of that assertion ; but the comparison, as made 
 in the table exhibited, was between 104 lbs. and 112 lbs., and 
 not between 104 lbs. and 123 lbs., which latter was the subject 
 of the table prepared by the Author, and with which the results 
 obtained from the light cement bore no comparison. The latter 
 was the class of cement that was used in the works at Dover, 
 the average of the cement employed there being 124 lbs. to the 
 bushel. It was further to be remarked that the comparison in 
 Mr. White's table was between cements of only thirty days old, 
 and it was no doubt wished that the inference should be drawn 
 that the ultimate strength would follow in the same proportion. 
 He apprehended that it was the ultimate strength of cement, 
 and not that at its earlier or intermediate stages, which con- 
 cerned Engineers. A comparison, however, of the properties of 
 these cements would explain how this apparent equality in re- 
 sults had been obtained, and also why the heavier would give an 
 ultimate result far better than the lighter quality. The light 
 cement of 104 lbs. had the property of quick setting, and showed 
 good results in the first instance, but it arrived at its state of 
 ultimate hardness at a comparatively early period ; while the 
 heavier cements showed moderate results at the earlier stages, 
 but continued the process of hardening at a rate much more 
 in proportion to their age ; the period for arriving at their 
 ultimate hardness being also much longer, as shown by the 
 
94 
 
 THE STKENGTH OF CEMENT. 
 
 Author's table, which stated it to be from one year to two years. 
 The results of four hundred experiments made by himself on 
 each of these classes of cement satisfactorily proved the supe- 
 riority of the heavy cement, and that the inference sought to 
 be established was entirely fallacious. These results had been 
 fully borne out in practice on the works at Dover by the quality 
 of the concrete blocks and in other ways, and the contractors 
 were so satisfied that it was to their own interest to use heavy 
 cement that they now declined to receive any but that above 
 named. They had lately executed a most important work, 
 which was one of the large detached forts in the deep water of 
 Plymouth Sound ; and from using only the highly manufac- 
 tured cement they had lost but three blocks during the whole 
 time of the contract. He considered the requirements of the 
 French Engineers were below the standard of what Portland 
 cement should be ; but they used it in a peculiar way. They 
 mixed Portland cement with Medina cement, which was much 
 quicker in setting than the Portland, and the union of the two 
 materials might possibly result more satisfactorily when their 
 rates of setting were more nearly alike. It had been asked. 
 What was the use of having a cementing material of greater 
 strength than the materials which were to be joined together ? 
 To that inquiry the general answer might be given that there 
 was no use ; but at the same time it did not follow that such a 
 result would attend the use of heavy instead of light cements. 
 The strength of cement might be reduced to any extent that 
 was desired, and economically so, by increasing the proportions 
 of sand employed; and as for a long time past the price of 
 heavy and light cements in the market had been much the 
 same, there was a considerable saving in using the heavy 
 cement with the larger proportion of sand that it would take. 
 At the same time it must be admitted that greater weight 
 meant nothing less than higher manufacture, and tliat heavy 
 cement was worth a higher price. The natural conclusion was 
 that the light cement, from the great demand for it, was com- 
 manding a higher price than it deserved. The difficulty with 
 Portland cement now was that it could not be depended upon. 
 If a sudden break in a sea wall occurred Medina cement could 
 be used with the certainty of good results ; but with Portland 
 cement it was almost a matter of necessity that it should 
 
THE STBENGTH OF CEMENT. \ . 95 
 
 undergo a course of tedious tests before assurance could be 
 obtained that the cement would not " blow " in the work, and 
 this bar to its use would remain until the makers adopted 
 the course pursued in other manufactures, which was, to 
 aim at every possible improvement in quality, with the cer- 
 tainty of a good article always commanding its value in the 
 market. 
 
 Sir Chaeles Hartley said, in connection with the employ- 
 ment of cement and pczzolana abroad, that he could give a 
 brief account of certain works he had inspected during the last 
 month on the French and on the Italian coasts. Harbours of 
 refuge were being constructed at Biarritz and at St. Jean 
 de Luz, situated on the rocky seaboard between the mouths of 
 the Adour and the Bidassoa, and consequently at the very head 
 of the Bay of Biscay, a position peculiarly exposed to the fury 
 of Atlantic gales from the N.W. The rise and fall of the tide 
 at this part of the coast varied from 3 metres to 5 metres. At 
 Biarritz the works were carried on under great difficulties, 
 owing to its being without a safe haven for the shelter of small 
 craft, to the number of detached rocks, to the great depth of 
 the sea close in-shore, and to the presence of an almost in- 
 cessant ground swell even at times of perfect calm. This 
 unfavourable condition of things obliged M. Daguenet, the 
 Engineer in charge, to advance the new jetty from the mainland 
 to its full height at once by pitching large blocks of bdton into 
 the sea from a temporary waggon road. Many of the blocks were 
 broken and the work often breached by the adoption of this 
 plan ; but such mishaps were difficult to avoid, as there was no 
 possibility of conveying the blocks by water. The blocks used 
 had a cube of 33 tons each, and were composed of Portland 
 cement, stone, and sand, in the proportions of 1 part of cement 
 to 2 parts of sand and 3 parts of broken stones. After being 
 made they were allowed to remain for three months to harden, 
 and were then conveyed in waggons to the tip-head. 
 
 At St. Jean de Luz the proximity of a small tidal harbour 
 rendered the formation of a new jetty ^ a much easier task, for 
 under its shelter blocks were made on the shore, between high- 
 
 ' This work, like the Biarritz jetty, is intended to have a length of about 
 300 metres, founded at an average depth of 24 feet below low-water mark. — C. H. 
 
96 
 
 THE STRENGTH OF CEMENT. 
 
 water and low-water mark, and from one month to two months 
 afterwards, according to the season, were taken to the jetty by 
 a couple of pontoons, and quietly lowered into place. The 
 blocks measured 4 metres by 2^ metres and 2 metres on their 
 sides, and weighed 44 tons. They were begun and completely 
 finished during the ebb of a single tide^ and the boards which 
 then encased them were removed within twenty-four hours after- 
 wards. The proportions of these blocks were 1 of Portland 
 cement, 2^ of sand, and 3 of stones. They set much sooner and 
 supported more sand than the Biarritz blocks, in consequence of 
 their frequent immersion in water immediately after being built ; 
 and they were not liable to fracture when deposited, on account 
 of the employment of pontoons. The jetty above the level of 
 ordinary low water was entirely constructed of very small 
 rubble — faced with ashlar rarely more than 3 feet cube — set in 
 Eoman cement, or rather in the quick-setting Spanish cement, 
 which very nearly resembled it, and which, after being used 
 half an hour, was capable of resisting the heaviest seas. This 
 appeared to be a skilful application of two cements differing 
 widely in their respective qualities, and however much the 
 durability of a very quick-setting cement might be questioned, 
 its success in the meantime at St. Jean de Luz, where it was 
 employed under trying circumstances, was undoubted. 
 
 At Genoa a pier was being carried out in a depth of 42 feet, 
 and was advancing at the rate of 50 metres annually. Its width 
 at the water-line was about 120 feet; its sea-slope stood at 
 2 to 1 ; and its inner slope at 1^ to 1. The body of the work 
 consisted of small rubble and quarry rubbish, the outer coating, 
 next the sea, of natural blocks of limestone from 5 tons to 90 
 tons in weight, and the inner slope of first and second class 
 rubble. From the water-line to 4 feet below it the whole width 
 of the pier was covered with a layer of beton built in situ, and 
 the interior quay wall, which had a thickness of 18 feet, and 
 was built of the same material, was founded at a depth of 9 feet 
 by means of a temporary casing of 3-inch sheet piling, supported 
 by timber walings and stout iron upright bars fixed in the 
 rubble. The beton thus so extensively used consisted of 1 part 
 of rich lime, 2 parts of pozzolana, and 3 of broken stones ; and 
 so well had it answered that along the line of the finished pier 
 not the slightest sign of settlement could be detected. Above 
 
THE STRENGTH OP CEMENT. 
 
 97 
 
 the water-line blocks of 12 metres cube were built in place, 
 some of them consisting of Italian cement, sand, and shingle, in 
 the proportions of 1, 2, and 3 respectively, and others of 
 mortar, of the same quality and proportions, and third-plass 
 rubble. 
 
 At Spezzia pozzolana was used exclusively for the dock walls, 
 where they were set dry, in the proportions of 2 parts of pozzo- 
 lana to 1 part of lime and 3 parts of stones ; but for the quays, 
 built in the water in the manner described by Mr. Hawkshaw, 
 the cement of the country was used in the proportion of 1 part 
 of cement, 2 parts of sand, and 3 parts of broken stone. 
 
 At Leghorn a noble breakwater 1040 metres long, and built 
 in a depth of 30 feet, was on the eve of completion. With the 
 exception of the interior quay wall and the parapet, it consisted 
 entirely of beton blocks, and so well had the blocks, built on 
 shore, been placed by means of pontoons, that the outer as well 
 as the inner slope stood immovable at an angle of 45° The 
 submerged blocks of 10 metres cube consisted of 0-70 of lime, 
 0*42 of sand, and 0*42 of pozzolana; and the still larger blocks 
 built in place above water consisted of third-class rubble, and 
 mortar made of 0*70 of lime and 0*84 of pozzolana.^ 
 
 With regard to the relative value of cement and pozzolana, 
 he might state that Italian Engineers, as a general rule, pre- 
 ferred the latter, principally on the ground that it had stood 
 the test of centuries, whereas they contended that cement for 
 sea work was still on its trial. They argued, moreover, that 
 beton formed of pozzolana was infinitely cheaper in Italy than 
 beton composed of the cements of France or of England ; and 
 in support of this assertion they might have quoted the fact 
 that pozzolana blocks only cost from 20 francs to 28 francs a 
 cubic metre, at almost any part of the Italian seaboard, whilst 
 a wall built at Genoa with the Valentine cement of France 
 had cost 45 francs ; the blocks used at Biarritz, and made of 
 
 * At Leghorn and Spezzia pozzolana will only be received from a certain 
 locality in the neighbourhood of Kome, where its peculiar colour is unmistakable • 
 and in order to test the actual quantity delivered it is held that a cubic metre of 
 this pozzolana weighs 1195 kilogrammes. On reaching the works therefore it is 
 measured and not weighed (so that there may be no temptation to water it), and 
 payment is made at so much per ton — generally 17 francs delivered — by assuming 
 that 10 cubic metres weigh 12 tons. — C. H. 
 
 H 
 
98 
 
 THE STRENGTH OF CEMENT, 
 
 Portland cement, 40 francs ; and the Cherbourg blocks, made 
 also of Portland, as much as 55 francs per cubic metre — the 
 cost of materials, labour, and immersion being included ia each 
 case. 
 
 The choice of a cement, or of pozzolana as a substitute for 
 it, depended so much on the character of the work to be 
 executed, and on its geographical position, that the greatest 
 merit would ever be due to those who selected the materials of 
 construction best adapted to the exigencies of the situation. 
 Thus it might be found that pozzolana was superior to cement 
 where, as in Italy, the former was plentiful and cheap and the 
 latter scarce and dear ; that Portland cement was more suitable 
 than pozzolana wherever there was a constant wash of the sea 
 to contend with, or where, as at Biarritz, great tenacity was 
 required ; and that a very quick-setting cement was best where, 
 as at St. Jean de liuz, the construction of a temporary coffer- 
 dam or casing was impossible. 
 
 He believed, as a rule, foreign Engineers were bolder in their 
 concrete works than English Engineers had been hitherto ; and 
 he fully agreed with those who predicted a much larger use of 
 English cements, and especially of Portland cement. 
 
 Mr. T. D. EiDLEY wished to draw the Author's attention to 
 the mode of applying the tests. At the Thames Embankment 
 works, when a bargeload of cement arrived, an officer ap- 
 pointed by the Board of Works inspected it, and from each tenth 
 bag a sample was taken, which was made into blocks and then 
 tested. In these tests it was almost invariably found, certainly 
 in more than ninety cases out of one hundred, that the fracture 
 took place at the junction of the small part of the section with 
 the large, and in a curved form. He therefore inferred that 
 the fracture was due, to a certain extent, to transverse, and not 
 altogether to tensile, strain. If such were the case it would 
 detract from the correctness of the results arrived at in these 
 experiments, and it might be desirable to devise a means of sus- 
 pending the block, so that the strain should be entirely tensile. 
 He wished to add his meed of praise for the assiduous care 
 bestowed in the testing of these cements, which had, no doubt, 
 greatly contributed to the improved manufacture of cement. 
 
 Mr. John Grant, in reply, said he wished to notice the 
 principal exceptions that had been taken to the tests he had 
 
THE STRENGTH OF CEMENT. 
 
 99 
 
 ventured to establish. A formidable list of the objections to 
 a very heavy specific gravity and high quality of cement had 
 been made out, and he had arranged those objections in the 
 following order : — First, loss of quantity produced from a given 
 amount of material. Second, loss of fuel in extra burning. 
 Third, wearing out of the kilns. Fourth, wearing out of the 
 millstones. Fifth, impossibility of getting the whole of the cal- 
 cined results of the materials of the same quality. Sixth, no 
 increase of price to the manufacturers. Seventh, the dangerous 
 character of this high quality of cement. Eighth, its slow-set- 
 ting character, under certain circumstances. Ninth, its liability 
 to inferior grinding. 
 
 With regard to the first six objections, he thought they might 
 be dismissed as being entirely questions for the manufacturer. 
 He would confine himself therefore to the two which were 
 raised in an engineering point of view, and chiefly to the point 
 that cement of this high specific gravity was dangerous. The 
 best answer he could give was the experience which had been 
 obtained in using between three and four millions of bushels 
 during the last six or seven years in the Main Drainage works 
 of London. Those works had been seen by a large number 
 of the Members of this Institution ; and he felt assured that if 
 those works were critically examined no proofs of this cement 
 being dangerous could possibly be discovered. Any such 
 instance of the cement being dangerous was utterly unknown 
 to him, either in the works on the south or on the north side 
 of the river. 
 
 As to specific gravity, a table was exhibited by an eminent 
 manufacturer, of which, after the careful examination it had 
 received, it was unnecessary for him to say more than that as 
 far as regarded the experiments on the cements used on the 
 Main Drainage works, three out of the four lines composing that 
 Table were inaccurate. 
 
 Table XXXIX. in the Appendix, showing the tensile strains 
 of cements of different specific gravities at different periods, was 
 a summary of four preceding Tables. From this it would be 
 perceived that cement weighing 109 lbs. per bushel bore a 
 tensile strain at the end of a week of 767 lbs., at the end of a 
 month of 886 lbs., and at the end of a year of 1099 lbs. ; cement 
 of 112 lbs. (two lines) bore 558 lbs. and 445 lbs. at the end of a 
 
 H 2 
 
100 
 
 THE STBENGTH OF CEMENT. 
 
 week, 784 lbs. and 680 lbs. at the end of a month, and 1010 lbs. 
 and 1075 lbs. at the end of a year ; but when it weighed 123 lbs., 
 which was the quality of cement used by Mr, Druce at Dover, 
 a marked difference was visible, as then at the end of a week it 
 bore 817 lbs., at the end of a month, 936 lbs., and at the end of 
 a year, 1230 lbs., considerably higher tlian those of any of the 
 lighter cements. But there was still stronger proof, and proof 
 which had the advantage of being taken from the ordinary daily 
 records, made without the slightest view of illustrating this 
 point. In those records, which were kept on every contract 
 under the Metropolitan Board of Works, an entry was made of 
 the weight per bushel of every load of cement brought in. He 
 had taken from one of these records kept at the outfall works 
 at Crossness, the result of 327,000 bushels of cement used there 
 during two years. In Table XL. were shown the results of the 
 tensile strain of cement varying from 106 lbs., 107 lbs., and 
 108 lbs. per bushel up to 130 lbs.; beginning at 106 lbs., with 
 a tensile strain of 472 lbs., and finishing at 130 lbs., with a 
 tensile strain of 914 lbs. This Table, as was evident, had not 
 been prepared in any way to illustrate this point, for there were 
 several discrepancies in it, and several results that would seem 
 to be unfavourable to the argument he was maintaining ; but 
 he had given it in its integrity, and the main lesson which that 
 Table taught was, that weight legitimately obtained by burning 
 meant strength. It was true that there might be weight with- 
 out strength ; it might be got improperly ; but he said, in the 
 presence of many large manufacturers of cement, most of 
 whom, he was certain, agreed with him, that weight meant 
 strength. 
 
 Only that day additional confirmatory proof had been ob- 
 tained on this point. On the Embankment works, on the north 
 side of the river, one maker supplied 1600 bushels. These 
 w.pre tested by eighty tests ; the weight of the cement per 
 bushel was found to be 113 lbs. and the tensile strain at the 
 end of a week was 596 lbs. Another maker supplied 1000 
 bushels, which were tested by fifty tests ; the weight per bushel 
 was 117 lbs., the tensile strain 655 lbs. In another case 1500 
 bushels of cement of 121 lbs. were tested by seventy-five tests ; 
 and the tensile strain was more than 790 lbs. Four of those 
 tests broke between 465 lbs. and 650 lbs. ; but seventy-one out 
 
THE STEENGTH OF CEMENT. 
 
 101 
 
 of the seventy-five tests went to the full extent of the instru- 
 ment, which was 790 lbs., and the cement was not broken at 
 that strain. He had been asked to explain how he came to 
 adopt these tests. He had been challenged on that point, 
 otherwise he had not intended to refer to it. In 1858-9, when 
 he commenced these experiments, he sent to some of the 
 principal manufacturers for samples. He tested these carefully, 
 and made numerous experiments, aud found that the manu- 
 facturer who had advanced the objection to specific weight 
 furnished the heaviest of those samples, which also proved to be 
 the strongest cement of all. When he ascertained that it was 
 intended to put such high tests into the specification as 110 lbs. 
 weight per bushel, and 400 lbs. tensile strain at the end of a 
 week, he objected that 400 lbs. was much too high a test in 
 practice. In reply, that maker's own particular cement was 
 pointed out, which showed a result 40 per cent, higher than was 
 specified. The Author was then told candidly that he must not 
 take these results and expect to get cement in any quantity equal 
 to the sample of cement which had been sent in, as it had been 
 prepared specially for the purpose. In fact no other specimen 
 came within 10 per cent, of that sample, and due allowance had 
 been made for this circumstance, as would be seen by a tensile 
 strength of only 60 per cent, having been fixed upon. The 
 weight of 110 lbs. and tensile strain of 400 lbs. were, after full 
 consideration, maintained. 
 
 A remark had been made, to the effect that he had gone too 
 far in insisting upon such high tests ; but it would be seen that 
 all due caution had been exercised, when it was considered that 
 those tests had been continued for three years, and that it was 
 only after using nearly a million of busliels, averaging 114 lbs. 
 per bushel, and a breaking weight of 607 lbs., that 2 lbs. were 
 added to the weight per bushel, and 100 lbs. to the tensile strain 
 on the 21 square inches sectional area. Experience had fully 
 confirmed the moderation of these requirements. Instead of 
 110 lbs., the average specific weight of 114 lbs. per busliel had 
 been realized; and instead of 400 lbs. tensile strain, 607 lbs. had 
 been attained, the quantity used on the south of the Thames 
 having been about one and a half million bushels. There had 
 been thus no cause to regret the adoption of so high a standard, 
 either from danger to the works or from any other cause. 
 
102 
 
 THE STBENQTH OF CEMENT, 
 
 While on the question of tensile strain, it might be as well 
 to refer to a point which had been raised by Mr. Coode as to 
 averages, that there might be a high average through very 
 great extremes. He was happy to state, in general terms, that 
 the minimum had exceeded the specified standard, the maximum 
 being very large indeed, upwards of 1000 lbs. at seven days, 
 and the average 50 per cent, above the original standard. To 
 show how important the specific gravity of Portland cement 
 seemed to the manufacturer he might cite the following fact : — 
 Mr. William Lee, M.P., who was surety for a contractor who 
 failed, had to carry out the Southern High-Level Sewer, and 
 was responsible for the strength and soundness of the work. 
 This work he did very well. Mr. Lee manufactured his own 
 cement, but instead of contenting himself with sending cement 
 of 110 lbs. per bushel, breaking at 400 lbs., which was the 
 requirement, he sent in cement of 120 lbs. to the bushel, and a 
 breaking weight of 680 lbs. tensile strain, being 70 per cent, 
 above proof strength . But there was one point which seemed to 
 have been overlooked by the objector to a very high quality — 
 viz. the interest of the purchaser, wlio, if a contractor, was 
 responsible for the soundness of the work ; or, if an Engineer, 
 was staking his credit and good name on the character of the 
 work executed with the cement. This point was of greater 
 importance than the difference of price between cements of first 
 and of second rate qualities. 
 
 It had been suggested that Portland cement might pass those 
 tests of weight per bushel, tensile strain, and even the water 
 test, and yet afterwards prove to be dangerous. Such a result 
 was quite impossible. It might pass the weight per bushel ; it 
 might, for a short time, pass the test of tensile strain : but it 
 could not pass the test of water. This brought him to the 
 question of what should be done in cases of emergency, in order 
 to ascertain the character of the cement. In such cases the 
 tests of specific gravity and tensile strain might be laid aside, 
 and the water test alone be applied. A very short experience 
 would enable anyone to ascertain whether a cement was safe, 
 strong, or weak. When it was necessary to know the character 
 of cement without loss of time two pats were made of it. One 
 was put into water and the other was kept dry. By the colour 
 alone it was obvious whether there was an undue preponderance 
 
THE 8TEENGTH OF CEMENT. 
 
 103 
 
 of clay. If there was, the cake which was put into water would 
 assume a buff colour. If it had been overchalked, or overburnt 
 to the point of danger, little cracks would be perceptible all 
 round the edge in the wet cake; and if the latter of these 
 indications was found, the cement must be laid aside, and it 
 must be ascertained whether it had merely been supplied too 
 new and hot, or was really so improperly manufactured as to be 
 unfit for use. 
 
 A question had been asked as to the relative cost of lias lime 
 mortar of first quality, and Portland cement compo or mortar. 
 First-class mortar at the Liverpool docks had been stated to 
 have cost from 9s. per cubic yard to 10s. per cubic yard. In 
 Mr. Eobertson's Paper on Hydraulic Mortar used at the London 
 Docks,^ it was stated that the net cost of the first quality of 
 mortar at the works was 14s. 3f d per yard of one kind, and 
 12s. 9d. for another. He had endeavoured to ascertain the cost 
 of Portland cement mortar, or compo, mixed in different pro- 
 portions. In the proportion of 1 to 1 the cost was about 258. 
 per cubic yard, in the proportion of 2 to 1, 18s. dd., of 3 to 1, 
 15s,, of 4 to 1, 13s., and of 5 to 1, lis. 6d. per cubic yard. The 
 sand and cement seemed to lose about one-sixth of their bulk 
 when made into compo, and another sixth in setting — altogether 
 about one-third of the original bulk of the sand and cement. It 
 had also been asked whether the cement could be regauged ? 
 He did not think it could ; and he did not think it desirable 
 that Portland cement should be allowed to stand very long 
 after being gauged before it was used, inasmuch as the process 
 of setting or crystallization appeared to commence immediately 
 after it was wet. If disturbed after one hour or two hours it 
 lost much of its strength. The gauging was always done in 
 moderate quantities with a shovel upon a mortar board. 
 
 Portland cement blocks for facing sea walls might be made 
 of extra strength and density by increasing the proportion of 
 cement ; and (when not of too large size) by compressing the 
 materials in iron moulds or boxes and using the smallest 
 quantity of water. Some excellent specimens of artificial stone, 
 made in this way some years ago at East Greenwich, might be 
 seen in front of the Terrace, Lewisham, Kent. 
 
 > Vide 'Minutes of Proceedings Inst. C,E.,' vol. xvii. p. 410. 
 
104 
 
 THE STRENGI'H X)F CEMENT. 
 
 He would add some Tables of experiments made to illustrate 
 the principal points raised in the discussion (Tables XXXYI. 
 and following Tables) ; and would say generally with regard to 
 these experiments, about fifteen thousand in number, that they 
 had been made with all integrity upon the cements used in the 
 works, and made by different manufacturers. He had not 
 compared his results with those of anyone else; he had given 
 them exactly as they transpired. If these experiments, made 
 for practical purposes, had not been given to this Institution, 
 they would have been buried in the records of the office, and 
 perhaps never been published. He had started with no theory 
 of his own; he had none to establish: moreover, his own know- 
 ledge of the subject was at first very slight. What he had 
 ascertained was by experience from day to day during a period 
 of seven years. He had previously used Portland cement only 
 on a small scale and in running water, where it was apt to 
 leave the joints, and he had not persevered with it to the extent 
 he had since. But having been called on to take part in carry- 
 ing out the Main Drainage works, it seemed to him to be of the 
 greatest importance to get cement which could be thoroughly 
 depended upon, in works carried through ground so full of 
 water that the pumping in many cases came to 10 per cent, of 
 the whole cost. 
 
 Mr. Fowler, President, said this was one of the most able 
 and useful Papers that had come before the Institution for a 
 long time. But it occurred to him, as no doubt it had to several 
 others, that this Paper would be still more valuable and useful 
 if it were supplemented by another on blue lias and greystone 
 lime mortars, so that comparisons could be made between the 
 results of experiments upon mortars and the results of the 
 experiments made upon Portland cement ; and he hoped that 
 from the Author, or from some other Member, such a Paper 
 would be forthcoming, either in the present or in the next 
 session of the Institution. It was almost impossible to ai-rive at 
 the true value of such a material as Portland cement, ex- 
 cepting by comparison with other cements or mortars used by 
 Engineers for the same purposes. He trusted that if the 
 subject was undertaken it would be with the .same care as that 
 bestowed upon the experiments upon Portland cement, and that 
 the experiments would be continued for the same period. If 
 
THE STRENGTH OF CEMENT. 
 
 105 
 
 another Paper on mortars could be equally well prepared, and 
 the discussion upon it be equally well sustained, this Institution 
 would have on that subject confirmation of the most valuable 
 kind — valuable, he might say, to experienced Members as well 
 as to young Members; because he thought there was not a 
 single Member, whatever his experience had been, who had not 
 derived some new information and some new knowledge from 
 the present Paper and the discussion that had taken place 
 upon it. 
 
FUETHER EXPERIMENTS ON THE STRENGTH OF 
 PORTLAND CEMENT.^ 
 
 In a previous Paper, Session 1865-6,^ the Author stated that 
 " further experiments were desirable on the strength of adhe- 
 sion between bricks and cement under varying circumstances ; 
 on the limit to the increase of strength with age ; on the rela- 
 tive strength of concrete made with various proportions of 
 cement and ballast," &c. The experiments described in this 
 communication have been tried with the view of throwing some 
 additional light upon these points ; and though no one can 
 feel more than the Author their fragmentary and incomplete 
 character, he has, after long hesitation, decided to lay them 
 before the Institution. If they serve no other purpose, their 
 incompleteness may point out to those who are interested in 
 the subject, and have time for further investigation, the direc- 
 tion which their inquiries might advantageously take, and the 
 large field yet open for their labours. 
 
 Before describing the new series of experiments it may be 
 useful to review some of the points in the previous Paper. 
 Among these was " the limit to the increase of strength with 
 age." Tables XYIII. XXIY. XXV. and XXIX. were intended 
 to illustrate this point, and the five years which have since 
 elapsed have to some extent afforded the desired opportunity. 
 
 Thus in Table XVIII. were given the results of one hundred 
 and sixty out of three hundred experiments intended to extend 
 over ten years, and made with Portland cement weighing 
 123 lbs. to the imperial bushel. It was shown that neat 
 cement which at seven days broke at 817 "1 lbs. increased 
 
 1 Vide ' Minutes of Proceedings Inst. O.E.,' vol. xxv. p. 79. 
 
108 
 
 THE STRENGTH OF CEMENT. 
 
 gradually in strength till at two years it bore a tensile strain of 
 1324-9 lbs., and at three years of 1314*4 lbs., or practically the 
 same. By the extended Table in the Appendix it will be per- 
 ceived that the maximum was attained at two years, the further 
 results being 1312-6 lbs., 1306 lbs., 1308 lbs., and 1327-3 lbs. 
 at four, five, six, and seven years respectively. With cement 
 and sand in equal proportions the tendency to increase in 
 strength continued ; that which at seven days broke at 
 353 ■ 2 lbs., or 42 per cent, of neat cement ; at one month at 
 452 • 5 lbs., or nearly 50 per cent, of neat cement ; at two years 
 at 790*3 lbs., or 60 per cent, of neat cement; bore strains of 
 818*1 lbs., 821 lbs., 819*5 lbs., and 863*6 lbs., at four, five, six, 
 and seven years respectively. The results at four, five, and six 
 years were practically the same, being 62 * 6 per cent, of neat 
 cement, and at seven years 65 per cent. 
 
 Table XXIY. gives the strength of Roman cement at various 
 stages from seven days to seven years. The results do not uni- 
 formly and regularly increase. It was shown that this cement 
 bore a strain of 201 * 83 lbs. at seven days, of 376 * 8 lbs. at six 
 months, and of 323*8 lbs. at twelve months. The further 
 experiments give the following results : 438 ll)s., 450 *8 lbs., 
 512*6 lbs., 466*9 lbs., 466*6 lbs., and 553*2 lbs., at two, three, 
 four, five, six, and seven years respectively. The differences 
 between the minimum and the maximum are very great, and 
 confirm the conclusion that this kind of cement is not nearly 
 so uniform in strength as Portland cement, and that though 
 about two-thirds of the price it is only about one-third of the 
 strength, and therefore double the cost of Portland cement 
 measured by strength. 
 
 Table XXV. relates to another Eoman cement, and brings 
 down the experiments six years later. Cement which at seven 
 days broke with a tensile strain of 202 lbs., and attained to its 
 maximum 643*1 lbs. at twelve months, broke at 546*3 lbs., 
 603*8 lbs., 632*2 lbs., 627*4 lbs., 666*4 lbs., and 708*7 lbs., at 
 two, three, four, five, six, and seven years respectively. 
 
 Table XXIX. refers to Medina cement, which at seven days 
 bore strains of 92*1 lbs. (1st series), and 211 lbs. (2nd series), 
 attained a maximum strength of 476 * 9 lbs. at twelve months, 
 and bore only 276 lbs. at two years. At three, four, five, six, 
 and seven years the strains were 275-5 lbs., 287*8 lbs., 307 lbs., 
 
THE STRENGTH OF CEMENT, 
 
 109 
 
 365 lbs., and 377 '5 lbs., respectiyely. This series of experi- 
 ments is to be continued to eight, nine, and ten years. 
 
 As a preliminary to the further experiments hereafter de- 
 scribed, upwards of two hundred were made to ascertain if any 
 improvement could be devised in the form of mould previously 
 used. The results of these are given in Table I. of Appendix, 
 Form No. 1 is that which was adopted at first (January, 1859), 
 because it was found in use both in France and in England. 
 Form No. 2 shows the same mould with the inner angles 
 rounded off. In Form No. 3 the outer angles and shoulders were 
 also rounded off. This form and the other shapes which follow 
 were found to have a tendency to slip in the clips when under 
 tension. Forms Nos. 4, 5, and 6 were like dowels of different 
 lengths, but with the same sectional area at the neck as the 
 preceding, viz. 1^ inch by 1-^ inch = 2 J square inches. Forms 
 Nos. 7, 8, and 9 were like the three preceding, but with a 
 breaking area of 2 inches by 2 inches = 4 square inches. Form 
 No. 10 is that shown on Plate 3 of the original Paper, and has 
 the same area as Forms Nos. 7, 8, and 9. Twenty moulds were 
 made of each kind : ten were broken at seven days, and ten at 
 thirty days, all having been kept in water. Forms 2 and 3 gave 
 the highest and almost identical results. It was therefore 
 presumed that No. 2, which is the form of mould shown in 
 Plate 4 of the original Paper, was of all the least subject to 
 error and irregularity ; and this form has been used in the tests 
 and experiments described in this Paper, except where other- 
 wise stated, and is the standard constantly employed by the 
 officers of the Metropolitan Board of Works. Perhaps the lower 
 results given by the moulds Nos. 4-9 were due to the wedge- 
 shaped ends opening the breaking clips when the strain was 
 applied. The later investigations of Mr. Bramwell, " On the 
 Influence of Form on Strength " ^ would lead to the preference 
 of this form to those marked Nos. 1, 2, 3, or 10. Further 
 experiments are being made on this point, and means taken to 
 prevent the clips from opening. 
 
 On another point a large number of experiments were made, 
 viz. as to the best mode of avoiding any distortion or departure 
 from the line of strain. The plan originally adopted is shown 
 
 1 Vido ' Keport of Britisli Association, 1869,' p. 422. 
 
110 
 
 THE STRENGTH OF CEMENT, 
 
 on Plate 2, and a modification on Plate 4, of the former Paper. 
 It was found, however, that the altered moulds frequently broke 
 at the holes in each end of the specimen instead of at the neck. 
 The original clips were therefore reverted to, but in combination 
 with knife-edges in the eye and pin at each end. 
 
 The next step was to establish the conditions to be observed 
 in the following new series of experiments : — 
 
 A. On the strength of Portland cement tested by tensile 
 strain at different periods, from one day to twelve months. 
 
 B. On the adhesion between bricks cemented with Portland 
 cement and lime mortars, tested by tensile strain at the end of 
 twelve months. 
 
 C. On the strength of Portland cement bricks, neat, and with 
 different proportions of sand, tested at the end of twelve months 
 by compression in a hydraulic press. 
 
 D. On concrete blocks of different proportions of Portland 
 cement and lime, with gravel, sand, and other materials, tested 
 at the end of twelve months by compression. 
 
 For the purpose of these experiments the directions given 
 were : — 
 
 " Take about 40 bushels of Portland cement weighing not less 
 than 112 lbs. per bushel ; sift the whole of it through a sieve 
 with twenty holes to the lineal inch. 
 
 " Note the proportionate quantity which will not pass through 
 this sieve. Fill each bushel measure from a movable hopper 
 placed at an uniform height of 2 feet above the mouth of the 
 measure, and weigh each ' striked ' bushel. Afterwards put the 
 whole quantity together and turn it over many times to ensure 
 the thorough admixture of the cement. Use the same cement 
 for the several varieties of experiments. 
 
 ** Ascertain the quantity of cement required to fill a mould, 
 and the quantity of water required to bring the cement to the 
 consistency of paste. 
 
 *' In filling a mould with neat cement, use always the same 
 proportion (by weight) of cement and of water. 
 
 " Get 40 bushels of clean sharp sand, wash and afterwards 
 dry it ; take the weight per bushel, and in making tests with 
 different proportions of cement and sand weigh the proportions 
 of each — thus, to ensure equal quantities of Portland cement 
 
THE STRENGTH OF CEMENT. 
 
 Ill 
 
 and sand, take, say one-fiftieth part of a bushel of cement (by 
 weight) and one-fiftieth part of a bushel of sand (by weight), 
 and mix the two together for an experiment of 1 to 1. 
 
 " Use scales and weights, the latter adapted to show decimal 
 parts of a lb. instead of ounces. 
 
 EXPEEIMENTS. Seeies A. 
 
 " On the strength of Portland cement tested by tensile strain 
 at different periods, and with dififerent proportions of sand. 
 Kept in water. 
 
 Time in Moulds. 
 
 Mixed by hand. 
 
 Ground In a Mortar-Mill 
 
 Ten Moulds each. 
 
 for Thirty Minutes. 
 
 
 Broke at lbs. 
 
 Broke at lbs. 
 
 1 day .. .. 
 
 
 
 2 days . . 
 
 )) 
 
 
 3 „ .. ,. 
 
 )5 
 
 
 4 „ .. .. 
 
 )> 
 
 
 5 „ .. .. 
 
 » 
 
 
 6 „ .. .. 
 
 
 
 7 „ .. .. 
 
 »» 
 
 
 1 month 
 
 » 
 
 
 2 months 
 
 »» 
 
 
 3 .. .. 
 
 )> 
 
 
 4 „ .. .. 
 
 » 
 
 
 5 „ .. .. 
 
 )» 
 
 
 6 „ .. .. 
 
 )> 
 
 
 7 „ .. .. 
 
 )> 
 
 
 8 „ .. .. 
 
 )» 
 
 
 9 „ .. 
 
 » 
 
 
 10 „ .. .. 
 
 II 
 
 
 11 „ .. .. 
 
 12 „ .. .. 
 
 n 
 
 
 Total, 190 moulds. 
 
 Total, 190 moulds. 
 
 Series B. 
 
 Kinds of Bricks to he used. 
 
 1. Gault clay. Pressed. 
 , 2. Do. Wire cut. 
 
 3. Do. Perforated. 
 
 4. Suffolk (brimstones). 
 
 5. Picked stocks or shippers. 
 
 6. Farnham red. 
 
 7. Blue Staffordshire, pressed, with frog. 
 
 8. Do. do. rough, without frog. 
 
112 
 
 THE STRENGTH OF CEMENT. 
 
 " Before using the bricks : — 
 
 " 1st. Take their dimensions in inches and tenths ; give 
 area of bed, area of edge, and cubic contents. 
 "2nd. Weight— dry. 
 
 " 3rd. Do. after being soaked twenty-four hours. 
 4th. Strength by compression in a hydraulic press. 
 
 " Put together blocks, each composed of four bricks, making 
 the joints one-fourth of an inch thick, viz. : — 
 
 i. 10 of the gault clay, pressed, with neat cement. 
 
 ii. „ with Portland cement and sand 1 to 1 
 
 iii. „ „ „ 1 to 2 
 
 iv. „ „ „ 1 to 3 
 V. „ ,, „ 1 to 4 
 
 vi. „ „ „ 1 to 5 
 
 . vii. 10 with lias lime (specially burnt and ground forty minutes 
 in an edge-stone mortar-mill) and sand, in the proportion 
 of 1 to 2. 
 
 viii. 10 with ground Dorking lime-mortar, 
 ix. 10 with chalk lime-mortar. 
 
 " Make the same number of blocks of each of the other kinds 
 of bricks. 
 
 " Make— 
 
 10 Bricks (9 in. by 4 
 
 Series C. 
 
 in. by 3 in.) of Portland cement neat. 
 
 Portland cement and sand 
 
 to 
 to 
 to 
 to 
 to 
 to 
 to 
 to 8 
 to 9 
 to 10 
 
 " Put half of each kind in water and keep the other half out 
 of water ; test at end of twelve months by compression. 
 " Take weight dry, and same wet. 
 
 " Make a similar series of cement bricks, compressing them 
 in moulds either by hydraulic press or by ramming, and test as 
 above. 
 
THE STRENGTH OF CEMENT. 
 
 113 
 
 Series D. 
 
 " Concrete blocks, 12 inches by 12 inches by 12 inches, and 
 6 inches by 6 inches by 6 inches. To be tested at end of 
 twelve months. 
 
 " One of each to be kept in the open air, and one immersed 
 in water all the time. 
 
 4 to be made of 1 cement to 1 ballast. 
 
 >7 )» 2 )> 
 
 A. 
 
 if » ^ >r 
 
 K 
 
 )> ii ^ !' 
 
 7 
 q 
 
 " Make two of those above by compressing the materials in 
 layers of 1 inch thick, either by rammers or in a hydraulic 
 press. 
 
 " After setting, put one of each in water as before. Note the 
 quantity and weight of the materials composing the two kinds 
 of blocks. 
 
 " Make— 
 
 4 of Portland cement to 6 ground pottery. 
 >j »j ^ " 
 
 " One of each to be kept in air, and one immersed in water. 
 Two of each kind to be formed by compressing the materials as 
 before. 
 
 " Make twelve more of same proportions, using ground slag. 
 
 " Make twelve more of ground bottle glass. 
 
 " Make twelve of ground flints ; the chalk on the surface of 
 the flints to be washed off by diluted muriatic acid. 
 
 " Make twelve more of broken or ground granite and twelve 
 of broken or ground Portland stone." 
 
 In accordance with these instructions 88 bushels of Portland 
 cement were procured ; the gross weight being 4800 lbs. 11 oz., 
 or 113-176 lbs. per bushel. When sifted through a sieve 
 
 I 
 
114 
 
 THE STRENGTH OF CEMENT. 
 
 of four hundred holes per square inch this was reduced to 
 4231 lbs. 4 oz., or 110-56 lbs. per bushel. About 36 lbs. were 
 afterwards rubbed through the sieve ; 34 lbs. would not pass, 
 and there was a loss of 29 lbs. The sifted cement used in the 
 following experiments, except when otherwise stated, weighed 
 therefore 110-56 lbs. per "striked" bushel. A certain quan- 
 tity of cement weighing 19-2 lbs. was sifted through a sieve of 
 four hundred holes per square inch, 18 lbs. passing through and 
 1-2 lb. or one-sixteenth being left. Five moulds made of the 
 sifted material neat were placed in water, and at the end of 
 seven days broke at 959-4 lbs. = 427 lbs. per square inch. 
 Five more moulds were made of the same cement unsifted, and 
 under the same conditions broke at 842 lbs. = 375 lbs. per 
 square inch. The gain by sifting was therefore about 14 per 
 cent. 
 
 The following are the weights per bushel and per cubic foot 
 of the materials used in the new series of experiments : — 
 
 Materials. 
 
 Portland cement 
 Sand and ballast 
 Portland stone , , 
 Broken granite . . 
 
 „ pottery ., 
 
 „ slag 
 
 „ flints 
 
 „ glass . , 
 
 Weight of 
 1 Bushel. 
 
 Weight of ! 
 l^Cublc Foot. 
 
 lbs. 
 
 lbs. 
 
 110-56 
 
 ; 86-375 
 
 123-40 
 
 96-400 
 
 98-00 
 
 76-560 
 
 116-00 
 
 90-625 
 
 113-00 
 
 88-280 
 
 107-00 
 
 83-594 
 
 126-00 
 
 98-440 
 
 120-00 
 
 93-750 
 
 Table 2, Series A, gives the strength of neat Portland 
 cement used throughout these experiments at different periods 
 from one day to twelve months ; first, mixed by hand, and next, 
 ground in a mortar-mill for thirty minutes. At the end of a 
 month that which was ground in a mill had less than three- 
 fourths the strength of that which was mixed by hand. The 
 maximum strength of that mixed by hand seems to have been 
 attained at five months, and that ground in a mortar-mill at 
 one month, the greatest strength of the former being nearly 
 double that of the latter. The strength of that which was 
 mixed by hand was maintained, while that which was ground 
 in a mortar-mill declined, from the maximum in each case to 
 
THE STEENGTH OF CEMENT. 
 
 115 
 
 the end of the experiments. This result was probably due 
 partly to the process of crystallization, or setting, having been 
 interrupted by the continued agitation, and partly to the 
 destruction by attrition of the angular form of the particles. 
 
 Table 3, Series B, on the tensile strain required to separate 
 bricks cemented together with Portland cement and lime 
 mortars, would require to be greatly extended before any very 
 trustworthy deductions could be made from them. The area 
 from 36 inches to 40 inches is not large, and yet there are con- 
 siderable mechanical difficulties in making this class of experi- 
 ments with any machine which combines the necessary strength 
 and delicacy. The pressed gault bricks show the lowest amount 
 of adhesiveness ; partly because of their smooth surface, and 
 partly because in making them some oily matter is used for 
 lubricating the dies of the press through which they are passed 
 before being burnt. In the case of the perforated gault bricks 
 the cement-mortar seems to act as dowels, and the results are 
 consequently high. The Suffolk and the Fareham red bricks, 
 which each absorb about a pound of water per brick, adhere 
 much better than the Staffordshire, which are not absorbent. 
 This shows the importance of thoroughly soaking bricks which 
 are to be put together with cement, as dry bricks deprive the 
 cement-mortar of the moisture which is necessary for its setting. 
 
 Table 4, Series 0, on the strength of Portland cement bricks 
 tested by crushing, is, so far as it goes, instructive. As a rule, 
 and as might be expected, the denser the brick, the greater its 
 strength. When the cement is in proportion to the sand less 
 than 1 to 2 or 1 to 3, those dried in air bear a greater pressure 
 than those kept for twelve months in water. This would lead 
 to the inference, that when the quantity of cement is small, 
 bricks or blocks of concrete should be kept some time out of 
 water, and be allowed to harden before being used. 
 
 Contrasting the strength of these concrete bricks with the 
 different clay bricks as given in the first column of the Table 3, 
 it will be seen that down to the proportion of 5 to 1 the former 
 compare favourably. Thus, bricks made of neat cement bore 
 a pressure equal to that of Staffordshire blue bricks or of best 
 Fareham red bricks. Cement bricks made in proportions of 
 from 2 to 1 of cement to 5 to 1 are equal to the picked clay 
 bricks of the first six varieties in Table 3. It is further 
 
 I 2 
 
116 
 
 THE STRENGTH OF CEMENT. 
 
 evident that if these concrete bricks were more compressed 
 their strength would be greatly increased. The compressed 
 specimens in the Table were only from 3 to 9 per cent, denser 
 than those not compressed. Further experiments on the rela- 
 tion of density to strength are most desirable. 
 
 The Tables referring to the D series show the strength of con- 
 crete blocks, or cubes, made with Portland cement mixed with 
 various materials in different proportions and crushed after 
 being kept a year, half of them in air and half in water. 
 The general deductions from these Tables are, that the blocks 
 made with the largest proportion of cement to ballast are the 
 strongest— the strength being nearly in proportion to the quan- 
 tity of cement ; that it is desirable to spend no more time than 
 is absolutely necessary to effect a thorough admixture of the 
 cement with the sand and gravel ; and that the compressed 
 blocks are apparently stronger than the uncompressed blocks 
 in a larger proportion than their difference in density. 
 
 In this series Tables 4, 5, and 6 give the strength of 12-inch 
 cubes of concrete made with ballast, Portland stone, broken 
 granite, pottery, slag, flints, and glass, mixed with Portland 
 cement in the proportions of 6 to 1, 8 to 1, and 10 to 1, 
 and compressed. Half were kept in water for twelve months! 
 Tables 7 to 12 give the strength of 6-inch cubes of concrete 
 made of the same proportions and with the same materials, 
 half of them compressed and half uncompressed. Some of these 
 were kept in air and some in water for twelve months. Tables 
 13 to 18 exhibit the results of the six preceding Tables in 
 another form. 
 
 The most prominent result of the D series of experiments is 
 that concrete made of broken stone or broken pottery is much 
 stronger than that made of gravel. This is no doubt due partly 
 to the greater proportion of cement absorbed in the latter case 
 in cementing the finer particles of sand, and partly to the want 
 of angularity in the gravel. Compression and an increase in 
 the proportion of cement alike increase strength. In making 
 concrete bricks or blocks of moderate size compression might be 
 applied with advantage; but with large masses of concrete it 
 would be difficult to do so without running the risk of interrupt- 
 ing the process of crystallization or setting, which commences 
 immediately on the application of moisture. The cost of labour 
 
THE STRENGTH OF CEMENT. . v , 117 
 
 so applied would therefore be better employed in a larger ad- 
 mixture of cement. For the same reason that absorbent bricks 
 should be thoroughly soaked with water before being used, the 
 broken stones, bricks, or other materials used in making con- 
 crete should be saturated with water before the cement is 
 applied. 
 
 Dififerent illustrations of the Portland cement in the con- 
 struction of sewers for the Main Drainage of London, and of the 
 Albert or Southern Embankment of the river Thames, are 
 shown in Plate 15.^ It will be observed that in some cases it 
 has only been used as a foundation, or as a backing for brick- 
 work ; while in other instances sewers, 4 feet 6 inches high 
 by 3 feet wide, of concrete, have been lined with brickwork 
 4^ inches thick (Fig. 7). Again, some sewers have been formed 
 entirely of concrete, in the proportion of 1 of cement to 6 of 
 sand (Figs. 8, 9, and 10). There have been constructed in the 
 metropolis, south of the Thames, 5440 lineal feet of concrete 
 sewers, lined with 4^-inch brickwork, and 6800 'lineal feet 
 (about IJ mile) of sewers entirely of concrete. The details of 
 these will be found in Table 5 iu the Appendix. The cost of 
 this concrete is less than half that of brickwork, but if rendered 
 inside with cement it 'is about the same as if lined with half 
 brick — perhaps the cheapest form of sewer combining strength 
 with soundness. Sewers and culverts of almost any size might 
 be made on this principle. Sewers of concrete not rendered 
 inside, though somewhat cheaper, have one practical disadvan- 
 tage in busy thoroughfares, inasmuch as they require a longer 
 length of centering, on account of the slow setting of the con- 
 crete, and it is therefore necessary that about double the length 
 of trench should be open at one time. Fig. 8 shows the invert- 
 mould for forming the lower half of concrete sewers. Iron ribs 
 are set up 12 feet apart, and narrow laggings are inserted 
 between them. The concrete is put in and rammed behind 
 the latter. The centre is planed smooth, and if the internal 
 face is not to be rendered the centre is greased to prevent 
 the concrete adhering. Where the arch is not to be ren- 
 
 ' In the Appendix, page 146, will be found " Extracts from the Specifications 
 for Sewers made of Portland Cement Concrete and Concrete lined ith Brick- 
 work." 
 
118 
 
 THE STRENGTH OF CEMENT. 
 
 dered, fine concrete, composed of sand instead of gravel, is put 
 next to the centre. The cost of the concrete sewer, 4 feet by 
 2 feet 8 inches (Fig. 9), M^as 10s. per lineal foot, exclusive of 
 excavation. Under the same contract a brick sewer, of the 
 same size, 9 inches thick (Fig. 6), cost 16s. 6d. per lineal foot. 
 The concrete sewer, 7 feet 1 inch in diameter (Fig. 10), cost 
 per lineal foot, irrespective of earthwork, 16s. ; but inclusive of 
 earthwork, side entrances, junctions, &c., it was about 23s. per 
 lineal foot. This sewer was in some respects exceptional, inas- 
 much as it consisted of little more than an arch over a pre- 
 viously existing invert ; the lower half was, however, rendered 
 with cement and sand, in equal proportions, 1 inch thick. 
 Everything being taken into consideration, the most economical 
 combination is 4^ inches of brickwork in cement and the rest 
 in concrete. Another sewer, 9 feet 6 inches by 9 feet 6 inches, 
 to be constructed of concrete with a lining of 4|-inch brick- 
 work in cement, is shown in Fig. 11. 
 
 In the construction of the Albert, or Southern Embankment 
 of the river Thames (Fig. 12), it was originally intended to form 
 the wall of brickwork, with a granite facing ; but after about a 
 fourth part of the work had been executed, 14,335 cubic yards 
 of Portland cement concrete, made in the proportion of 6 to 1, 
 at lis. per cubic yard, were substituted for an equal quantity of 
 brickwork at 30s. per cubic yard. In the No. 3 contract of the 
 Victoria Embankment about 15,000 cubic yards of Portland 
 cement concrete were used instead of brickwork. The Chelsea 
 Embankment Wall, soon to be commenced, will be formed of 
 about 25,000 cubic yards of cement concrete, faced with about 
 5000 cubic yards of granite (Fig. 13). 
 
 From the experience already gained in the use of Portland 
 cement concrete, there would seem to be hardly any limit to the 
 purposes to which it may be applied. It is gradually being 
 brought into use in the construction of dwelling-houses in 
 different parts of the country, and there is no doubt it will be 
 still more extensively employed in the construction of docks, 
 piers, bi eakwaters, and other massive engineering works. Mr. 
 Joseph Mitchell, M. Inst. C.E., has tried Portland cement con- 
 crete, made of broken granite and cement, and laid on about 
 6 inches thick, at Inverness, Edinburgh, and in London, as a 
 
THE STRENGTH OF CEMENT. 
 
 119 
 
 substitute for ordinary metalling for the surfaces of the streets 
 of towns. 
 
 Many experiments have been made in the itianufacture of 
 bricks of different proportions of Portland cement and sand. 
 As these can be made equal, if not superior, both in strength 
 and appearance, to most kinds of clay bricks, it is difficult to 
 understand why they are not manufactured as a substitute for 
 clay bricks in localities where the latter are dear. Probably, 
 however, it is only a question of time. Where concrete can 
 be used in a mass it is cheaper than when used in the form of 
 blocks, and still cheaper than in the form of bricks. Each of 
 these modes has its advantages, according to the nature of the 
 work. 
 
 In France it has been long used in the form of "Betons 
 Agglomeres." In 1867 a number of arches were formed with it 
 by M. Coignet, under the steps leading from Westminster Bridge 
 to the Albert Embankment, and also about 40 feet of sewer, 
 4 feet by 2 feet by 8 inches, in the Camberwell Eoad. 
 Similar arches and sewers were constructed of Portland cement 
 concrete, and the general result was that the Portland cement 
 concrete was both stronger and cheaper than the beton. 
 
 In the construction of a sewer at Dulwich, where a cement 
 weighing 118 lbs. per bushel was used, considerable quantities 
 of milky-looking fluid exuded from the joints for a few weeks 
 after the work was completed. This was probably the result 
 of an excessive proportion of chalk having been used in the 
 manufacture of the cement. With the view of ascertaining 
 whether or not the cement deteriorated with age, the tests 
 shown in Table 6 were made first with neat cement, then with 
 cement and sand in equal proportions. It was satisfactorily 
 ascertained that in both cases the cement continued to harden 
 during the three months over which the experiments extended. 
 The neat cement at seven days bore a tensile strain of 
 805 • 2 lbs., and gradually increased in strength to 1239 lbs. at 
 three months. The mortar composed of cement and sand in 
 equal proportions, stood a strain of 275-8 lbs. at the end of a 
 week, and 538-6 lbs. at three months. The strength of the 
 latter mixture increased from 34 per cent, of the neat to 43-4 
 per cent. ; and had the experiments been extended over a year 
 
120 
 
 THE STRENGTH OF CEMENT. 
 
 or more, analogy would lead to the conclusion that this propor- 
 tion would have continued to increase. 
 
 Table 7 gives the strength of 589,217 bushels of Portland 
 cement used during the last five years on various works south 
 of the Thames. The cement has borne an average tensile 
 strain at the end of a week of 806-63 lbs., equal to 358-5 lbs. 
 per square inch ; being an improvement on that reported five 
 years ago of 200 lbs. on the breaking area of 2| square inches, 
 or 89 lbs. per square inch. It is satisfactory to know that the 
 quality has not only been maintained, but has continued to 
 improve. The strength at the end of thirty days of 37,200 
 bushels of the same cement, as ascertained by eleven hundred 
 and eighty tests, averaged 1024 lbs., equal to 455 lbs. per 
 square inch, showing an average of 234 lbs., or 30 per cent, 
 over the cement tested at seven days, which broke at 790 lbs. 
 Wherever the nature of the work will admit of it, tests at the 
 end of a month will be found more satisfactory than if made 
 earlier, as heavy cements, though the strongest eventually, are 
 the slowest to set. 
 
 The standard originally specified, 400 lbs., on 2^ square inches, 
 was soon afterwards raised to 500 lbs., or 222 lbs. per square 
 inch. This has since been increased to 350 lbs. per square inch, 
 or 787 lbs. on the breaking area at seven days (Table 8). A 
 standard of 450 lbs. per square inch at thirty days would be 
 about an equivalent practical test to specify. For the purpose 
 of comparison the same sectional area at the breaking point 
 (2-25 inches) has been retained, though various experiments, 
 already described, have been made as to different forms. 
 
 Further experience has confirmed the earlier conclusions, 
 that the strength of Portland cement increases with its specific 
 gravity, its more perfect pulverization, and its thorough admix- 
 ture with the minimum quantity of water in forming mortar. 
 It has also shown that to effect perfect cohesion, it is of the 
 utmost importance that the bricks to be cemented together 
 should be thoroughly saturated with water. Dry bricks absorb 
 moisture from the cement and destroy it. 
 
 Heavy cement, weighing 123 lbs. a bushel, like that referred 
 to m Table XVIII., takes about two years to attain to its maxi- 
 mum strength used neat : the admixture of sand not only 
 
THE STRENGTH OF CEMENT. 
 
 121 
 
 reduces its strength, but prolongs the period during which its 
 strength increases — in other words, by the admixture of sand or 
 gravel, cement-mortar or concrete sets less rapidly than neat 
 cement. 
 
 Roman cement, though from its quick-setting property very 
 valuable for many purposes, deteriorates by exposure to the air 
 before use, and is about double the cost of Portland cement if 
 measured by strength. 
 
122 
 
 THE STBENGTH OF CEMENT. 
 
 APPENDIX. 
 
 Table XVIII., in Appendix to Paper 1865-6, extended to Seven Years.^ 
 
 Eesults of Experiments with Portland Cement, weighing 123 lbs. to the 
 Imperial Bushel, mixed neat, and with an equal proportion of clean Thames 
 Sand, showing the Breaking Weight on a Sectional Area of 2 • 25 Square 
 Inches. The original Form of Mould is shown in Plate 2, vol. xxv., and in 
 Table I., No. 1, of the Appendix to the present Paper. 
 
 These form parts of a Series intended to extend over Ten Years. The whole of 
 the Specimens were kept in Water from the Time of their being made till 
 the time of Testing. 
 
 Age. 
 
 Neat Cement. 
 
 1 of Cement 
 to 1 of Sand. 
 
 Average Break- 
 ing Test of 10 
 Experiments. 
 
 Average Break- 
 mg Test of 10 
 Experiments. 
 
 
 lbs. 
 
 lbs. 
 
 
 817-1 
 
 353-2 
 
 
 935-8 
 
 452-5 
 
 
 1055-9 
 
 547-5 
 
 
 1176-6 
 
 640-3 
 
 
 1219-5 
 
 692-4 
 
 12 ditto 
 
 1229-7 
 
 716-6 
 
 
 1324-9 
 
 790-3 
 
 
 1314 -4 
 
 784-7 
 
 4 ditto 
 
 1312-6 
 
 818-1 
 
 5 ditto 
 
 1306-0 
 
 821-0 
 
 
 1308-0 
 
 819-5 
 
 
 1327-3 
 
 863-6 
 
 Table XXIV., in Appendix to Paper 1865-6, extended to Seven Years, 
 
 Eesults of Experiments with Eoman Cement, weighing 80 lbs. to the Imperial 
 Bushel. Manufactured by Messrs. Coles, Shadbolt, and Co. Sectional 
 Area, 2 - 25 Square Inches. Original Mould. 
 
 Time kept imjiersed 
 IN Watek. 
 
 Neat Cement. 
 
 Minimum 
 Breaking Test. 
 
 Maximum 
 Breaking Test. 
 
 Average 
 Breaking Teat. 
 
 
 1158. 
 
 lbs. 
 
 lbs. 
 
 7 Days 
 
 180 
 
 213 
 
 201-83 
 
 14 ditto 
 
 130 
 
 215 
 
 168-00 
 
 21 ditto 
 
 200 
 
 253 
 
 221-14 
 
 1 Month 
 
 173 
 
 283 
 
 243-33 
 
 
 238 
 
 400 
 
 329-60 
 
 
 252 
 
 408 
 
 376-80 
 
 
 78 
 
 306 
 
 167-80 
 
 12 ditto 
 
 137 
 
 428 
 
 323-80 
 
 
 377 
 
 472 
 
 438-00 
 
 3 ditto 
 
 425 
 
 462 
 
 460-80 
 
 4 ditto 
 
 454 
 
 574 
 
 512-60 
 
 5 ditto 
 
 442 
 
 494 
 
 466-90 
 
 6 ditto 
 
 i 447 
 
 487 
 
 466-60 
 
 7 ditto 
 
 488 
 
 620 
 
 553-20 
 
 I In Tables XVIII. and XXIV., the darker type refers to the later experiments. 
 
THE STEENGTH OF CEMENT. 
 
 123 
 
 Table XXV., in Appendix to Paper 1865-6, extended to Seven Years.^ 
 Results of Experiments witli Roman Cement. Manufactured by Messrs. J. B. 
 White and Beothers. Sectional Area, 2 • 25 Square Inches. Original Mould. 
 
 Time kept immebsbd in Water. 
 
 7 Days 
 14 ditto 
 21 ditto 
 
 1 Month 
 3 Months 
 6 ditto 
 
 9 ditto 
 12 ditto 
 
 2 Years 
 
 3 ditto 
 
 4 ditto 
 
 5 ditto 
 
 6 ditto 
 
 7 ditto 
 
 Neat Cement. 
 
 Minimum 
 Breaking 
 Test. 
 
 Maximum 
 Breaking 
 Test. 
 
 Average 
 Breaking 
 Test. 
 
 lbs. 
 
 lbs. 
 
 lbs. 
 
 170 
 
 240 
 
 202-0 
 
 160 
 
 190 
 
 173-0 
 
 170 
 
 205 
 
 186-5 
 
 246 
 
 291 
 
 260-3 
 
 307 
 
 344 
 
 322-5 
 
 442 
 
 502 
 
 472-7 
 
 813 
 
 520 
 
 471-1 
 
 596 
 
 680 
 
 643-1 
 
 677 
 
 610 
 
 546-3 
 
 522 
 
 647 
 
 603-8 
 
 600 
 
 658 
 
 632-2 
 
 582 
 
 662 
 
 627-4 
 
 603 
 
 711 
 
 666-4 
 
 646 
 
 780 
 
 708-7 
 
 Table XXIX., iu Appendix to Paper 1865-6, extended to Seven Years. 
 Results of Experiments with Medina Cement. Manufactured by Messrs. 
 Fbancis Brothebs, 1864, Sectional Area, 2-25 Square Inches. Original 
 Mould. 
 
 
 
 Neat Cement. 
 
 
 
 Time kept immeksed in Water. 
 
 Minimum 
 Breaking 
 Test. 
 
 Maximum 
 Breaking 
 Test. 
 
 Average 
 Breaking 
 Test. 
 
 
 
 
 lbs. 
 
 lbs. 
 
 lbs. 
 
 
 
 83 ■ 
 
 100 
 
 92-1 
 
 
 
 ditto (2nd series) 
 
 195 
 
 235 
 
 211-0 
 
 
 
 
 238 
 
 335 
 
 303-4 
 
 
 
 21 ditto 
 
 274 
 
 332 
 
 298-0 
 
 
 
 
 210 
 
 346 
 
 306-0 
 
 
 
 
 420 
 
 468 
 
 448-8 
 
 
 
 
 376 
 
 438 
 
 412-4 
 
 
 
 
 438 
 
 507 
 
 457-2 
 
 
 
 
 456 
 
 527 
 
 476-9 
 
 
 
 
 235 
 
 328 
 
 276-0 
 
 
 
 
 200 
 
 342 
 
 275-5 
 
 
 
 4 ditto 
 
 236 
 
 430 
 
 287-8 
 
 
 
 
 245 
 
 395 
 
 307 0 
 
 
 
 6 ditto 
 
 309 
 
 475 
 
 365 0 
 
 
 
 7 ditto 
 
 335 
 
 440 
 
 377-5 
 
 
 ' In Tables XXV. and XXIX. the darker type refers to the later experiments. 
 
124 
 
 THE STBENGTH OF CEMENT. 
 
 Table 1. 
 
 Eesults of Experiments on different Forms of Moulds. Weight of Portland 
 Cement used, 114 lbs. per Bushel. October and November, 1866. 
 
 
 
 Dimen- 
 sious at 
 Breaking 
 Point. 
 
 At 1 Days. 
 
 At 30 Days. 
 
 No. 
 
 Form. 
 
 Breaking 
 
 Breaking 
 Weight 
 per Sc[uar6 
 Inch. 
 
 Average 
 
 per 
 Square 
 Inch. 
 
 Breaking 
 w eignt. 
 
 Breaking 
 Weight 
 per Square 
 Inch. 
 
 Average 
 
 per 
 Square 
 Inch. 
 
 1 
 
 
 II " 
 
 778-1 
 
 345-8 
 
 
 
 
 1010-7 
 
 449-2 
 
 
 
 2 
 
 
 ditto 
 
 1034-7 
 
 459-9 
 
 
 
 
 1151-6 
 
 511-8 
 
 
 
 3 
 
 
 ditto 
 
 1064-3 
 
 473-0 
 
 
 
 
 1145-4 
 
 509-0 
 
 
 
 4 
 
 H 
 
 ditto 
 
 918-9 
 
 408-4 
 
 
 
 
 969-0 
 
 430-66 
 
 
 
 5 
 
 i 
 
 ditto 
 
 924-0 
 
 410-6 
 
 
 
 
 967-0 
 
 429-8 
 
 
 422 
 
 6 
 
 I 
 
 ditto 
 
 860-0 
 
 382-2 
 
 
 
 
 912-1 
 
 405-4 
 
 ) 
 
 
 7 
 
 H 
 
 tt It 
 2x2 
 
 1199-2 
 
 300-0 
 
 
 
 
 1354 -T 
 
 338-7 
 
 
 
 8 
 
 
 ditto 
 
 1172-6 
 
 293 0 
 
 
 i297 
 
 
 1315-1 
 
 328-8 
 
 
 337 
 
 9 
 
 
 ditto 
 
 1190-5 
 
 297-6 
 
 
 
 
 1371-2 
 
 342-8 
 
 
 
 10 
 
 
 ditto 
 
 1286-3 
 
 321-6 
 
 
 
 
 1460-3 
 
 365-0 
 
 
 
THE STBENGTH OF CEMENT. 
 
 Table 2. Series A. 
 
 Experiments on Cement mixed by Hand and in a Mortar-Mill. The Form 
 of Mould is shown in Table 1, No. 2. Sectional Area, 2 '25 Square Inches. 
 1868. Average of Ten Experiments in each case. 
 
 
 Cement, 110'66 lbs. to the Bushel 
 Mixed by hand. 
 
 Cement, 110-56 lbs. to the Bushel. 
 Ground in a Mortar-Mill for 30 Minutes. 
 
 
 
 IDay .. 
 
 362-1 
 
 IDay .. 
 
 341-1 
 
 
 
 2 Days . . 
 
 509-8 
 
 2 Days .. 
 
 388-1 
 
 
 
 3 .. 
 
 698-3 
 
 3 „ .. 
 
 478-3 
 
 
 
 4 „ .. 
 
 765-0 
 
 4 „ .. 
 
 512-6 
 
 
 
 5 „ .. 
 
 794-4 
 
 5 „ .. 
 
 563-7 
 
 
 
 6 „ .. 
 
 829-8 
 
 6 „ 
 
 604-1 
 
 
 
 7 „ .. 
 
 897-5 
 
 7 „ 
 
 613-2 
 
 
 
 , 1 Month 
 
 1096-3 
 
 1 Month 
 
 755-8 
 
 
 
 2 Months 
 
 1215-0 
 
 2 Months 
 
 557-7 
 
 
 
 3 „ .. 
 
 1220-0 
 
 3 „ .. 
 
 611-6 
 
 
 
 
 1422-9 
 
 4 „ .. 
 
 521-9 
 
 
 
 : : :: 
 
 1435-6 
 
 5 „ .. 
 
 504-8 
 
 
 
 6 „ .. 
 
 1424-9 
 
 6 „ .. 
 
 538-2 
 
 
 
 7 „ .. 
 
 1357-8 
 
 7 „ .. 
 
 451-4 
 
 
 
 8 „ .. 
 
 1360-1 
 
 8 „ .. 
 
 637-8 
 
 
 
 9 „ .. 
 
 1372-4 
 
 9 „ .. 
 
 496-6— 3 moulds broke. 
 
 
 
 10 „ .. 
 
 1381-1 
 
 10 „ .. 
 
 Nil — all moulds broke. 
 
 
 
 11 „ .. 
 
 1387-1 
 
 11 „ .. 
 
 256-4 — 2 moulds broke. 
 
 
 
 12 „ .. 
 
 1396-5 
 
 12 „ 
 
 443-2 
 
 
126 
 
 THE STRENGTH OF CEMENT. 
 
 Table 3. SiiBiES B. Summaey of Tests.^ 
 
 Tensile Strain required to separate Bricks cemented together in Blocks 
 
 
 Average 
 
 Dimensions in Inches. 
 
 ,Desceiption of Buick. 
 
 Strength - 
 by Com- 
 pression 
 
 Length. 
 
 Breadth. 
 
 Thick- 
 
 Area. 
 
 Cubical 
 
 
 BrFck in 
 Tons. 
 
 nesB. 
 
 Bed. 
 
 Edge. 
 
 Contents. 
 
 
 
 ins. 
 
 ins. 
 
 ins. 
 
 ins. 
 
 ins. 
 
 ins. 
 
 Gault clay, pressed 
 
 40-04 
 
 8-75 
 
 4-125 
 
 2-75 
 
 36-09 
 
 24-06 
 
 99-25 
 
 Gault clay, wire cut 
 
 32-70 
 
 9-00 
 
 4-125 
 
 2-75 
 
 37-125 
 
 24-75 
 
 102-09 
 
 Gault clay, perforated . . 
 
 46-40 
 
 9-00 
 
 4-375 
 
 2-G25 
 
 39-375 
 
 24-625 
 
 103-48 
 
 
 34 '94 
 
 9-00 
 
 4-5 
 
 2-625 
 
 40-5 
 
 23-625 
 
 106-312f 
 
 
 38-74 
 
 9-00 
 
 4-125 
 
 2-625 
 
 37-125 
 
 23-125 
 
 97-45 
 
 
 90-40 
 
 8-75 
 
 4-125 
 
 2-625 
 
 36-01 
 
 22-97 
 
 94-74 
 
 Staffordshire blue (pressed,^ 
 
 111-04 
 
 8-75 
 
 4-125 
 
 2-75 
 
 36-09 
 
 24-06 
 
 99-25 
 
 Staffordshire blue (rough," 
 
 in -92 
 
 &-75 
 
 4-125 
 
 2-75 
 
 36-09 
 
 24-06 
 
 99-25 
 
 1 The details of this Series may be consulted at the Institution. 
 
THE STEENGTH OF CEMENT. 
 
 127 
 
 Table 3. Series B. Summaby op Tests. 
 
 of 4 with Portland Cement and Lime Mortars, at end of 12 Months. 
 
 Weight. 
 
 Tensile Strain in lbs. 
 
 
 in lbs. 
 
 Portland Cement and Sand. 
 
 Lime and Sand. 
 
 Set in Air 
 or Water. 
 
 Dry. 
 
 Wet. 
 
 Neat. 
 
 1 to 1. 
 
 2 to 1. 
 
 3 to 1. 
 
 4 to 1. 
 
 5 to 1. 
 
 1 to 2 
 Blue Lias. 
 
 1 to 2 
 Dorking. 
 
 1 to 2 
 Chalk. 
 
 i-13 
 
 6-47 
 
 1631-4 
 
 1576-4 
 
 871- 
 
 988-2 
 
 735-2 j 
 
 Broke 
 
 1448-0 
 
 1520-5 
 
 638-7 
 
 Air. 
 
 
 
 1673-4 
 
 1642- 
 
 1708- 
 
 1264' 
 
 750-31 
 
 in 
 
 drilling 
 
 
 
 
 Water. 
 
 )-86 
 
 6-85 
 
 2440- 
 
 1558-3 
 
 Not set. 
 
 1037- 
 
 791- 
 
 772- 
 
 Not set. 
 
 Not set. 
 
 679-4 
 
 Air. 
 
 
 
 1679- 
 
 1408-3 
 
 Not set. 
 
 Not set. 
 
 Not set. 
 
 Not set. 
 
 
 
 
 Water. 
 
 t-&5 
 
 5-76 
 
 3898-8 
 
 2982- 
 
 2231-6 
 
 1663-21088-6 
 
 812-6 
 
 1763-0 
 
 1349-3 
 
 547-0 
 
 Air. 
 
 
 
 3011- 
 
 2721- 
 
 1834-4 
 
 1561-4 
 
 933-2 
 
 641- 
 
 
 
 
 Water. 
 
 MS 
 
 7-14 
 
 3275-2 
 
 2346- 
 
 2247- 
 
 2030-6 
 
 1930-6 
 
 1337- 
 
 2372-0 
 
 1788-2 
 
 428-6 
 
 Air. 
 
 
 
 3231- 
 
 2484- 
 
 2238- 
 
 1934-4 1869- 
 
 1154-2 
 
 
 
 
 Water. 
 
 )• 
 
 557 
 
 2816-8 
 
 2264- 
 
 1571-8 
 
 1516-2 
 
 825-8 
 
 792-6 
 
 1210-6 
 
 1479-3 
 
 423-8 
 
 Air. 
 
 
 
 3445- 
 
 2455- 
 
 2009- 
 
 1580-8 
 
 1259-6 
 
 845-6 
 
 
 
 
 Water. 
 
 5-55 
 
 7-52 
 
 4538- 
 
 2990- 
 
 2064- 
 
 1499- 
 
 1236- 
 
 1040- 
 
 1919-0 
 
 1743-0 
 
 449-0 
 
 Air. 
 
 
 
 4449- 
 
 2237- 
 
 1917- 
 
 1128- 
 
 1145- 
 
 653- 
 
 
 
 
 Water. 
 
 V82 
 
 7-90 
 
 2563-4 
 
 2008- 
 
 1844- 
 
 1535- 
 
 1188- 
 
 752- 
 
 1102-7 
 
 1330-6 
 
 Not set. 
 
 Air. 
 
 
 
 2749- 
 
 1329- 
 
 1304- 
 
 1053- 
 
 1016- 
 
 718- 
 
 
 
 
 Water. ' 
 
 r-75 
 
 7-81 
 
 1744-4 
 
 1701-6 
 
 1746- 
 
 1299-6 
 
 988- 
 
 Not set. 
 
 1269-6 
 
 1030-8 
 
 Not set. 
 
 Air. 
 
 
 
 1451- 
 
 1048-2 
 
 1186- 
 
 1090- 
 
 843- 
 
 Not set. 
 
 
 
 
 Water. 
 
128 THE STEENGTH OF CEMENT. 
 
 Table 4, Series C. Summary of Tests. Portland Cement Bricks (9 x U x 3) 
 
 
 Cement. 
 
 Sand. 
 
 Water. 
 
 Compressed. 
 
 Not Compressed. ' 
 
 Compressed. 
 
 Not Compressed. 
 
 Compressed. 
 
 Measure. ' Weight. 
 
 Measure. 
 
 W 6i.t! nt. 
 
 
 w eigiib. 
 
 
 Weight. 
 
 Measure. 
 
 Weight. 
 
 Neat 
 ) » 
 
 9 J 
 > ) 
 
 4-64 
 
 8^03 
 
 4-34 
 J > 
 
 7*50 
 
 NH. 
 » » 
 
 > J 
 
 > > 
 
 Nil. 
 
 > > 
 
 Nil. 
 
 » J 
 
 Nil. 
 
 > ) 
 J » 
 
 1^375 - 
 » > 
 
 1^65 
 
 1 to 1 
 J ) 
 J J 
 > ' 
 
 2-39 
 •• 
 
 4-13 
 
 2 '42 
 
 '4 -19 
 
 J ? 
 
 2^38 
 
 4-60 
 
 2-31 
 
 4-45 
 
 •875 
 > > 
 
 1-05 
 
 2 to 1 
 
 > > 
 
 1-63 
 > > 
 
 2-82 
 > > 
 
 r'45 
 
 2-51 
 » » 
 
 2-83 
 
 5^46 
 
 .■; 
 
 2^91 
 > » 
 
 !: 
 
 5^62 
 
 •75 
 
 •90 
 
 3 to 1 
 
 > > 
 
 > > 
 » > 
 
 114 
 
 1-97 
 » > 
 
 l-()6 
 
 1-83 
 > » 
 
 3^43 
 
 J f 
 
 6-62 
 
 3-19 
 
 6 -14 
 
 f 1 
 
 •625 
 > > 
 
 •75 
 > » 
 
 4to 1 
 » > 
 » > 
 
 •88 
 • > 
 
 1^53 
 « J 
 
 •82 
 » ) 
 
 • • 
 
 l'42 
 
 3-55 
 > > 
 
 6^85 
 
 3-29 
 
 6-36 
 » J 
 
 •50 
 > » 
 
 •60 
 
 > ? 
 
 5 to 1 
 
 > > 
 » > 
 
 •72 
 
 125 
 » ) 
 
 •68 
 
 f » 
 
 l'i8 
 > > 
 
 3^64 
 
 7^02 
 » > 
 
 3-43 
 
 6-62 
 
 •50 
 > > 
 
 •60 
 
 6 to 1 
 > » 
 
 •60 
 
 1-04 
 
 •58 
 
 l-OO 
 
 364 
 
 7^03 
 
 3-48 
 > » 
 
 6-71 
 
 •375 
 
 •45 
 
 7 to 1 
 » ? 
 » > 
 > ) 
 
 •52 
 
 •90 
 
 •48 
 • > 
 
 •84 
 
 3^71 
 > » 
 
 7^15 
 
 3-44 
 
 6-64 
 
 •375 
 
 •45 
 
 » 1 
 
 8 to 1 
 ? > 
 
 •46 
 
 •80 
 > J 
 
 •43 
 
 •74 
 > > 
 
 3-75 
 
 7-24 
 
 3-44 
 
 » > 
 
 6 •63 
 
 •375 
 
 •46 
 
 9 to 1 
 
 > J 
 
 > > 
 
 5 > 
 
 •42 
 
 •73 
 
 •39 
 ' » 
 
 •66 
 ) ) 
 
 3^82 
 > > 
 
 7-36 
 
 3-48 
 
 6 "72 
 
 •375 
 > > 
 
 •45 
 
 10 to 1 
 > > 
 
 •39 
 
 •66 
 
 9 9 
 
 •36 
 
 •60 
 
 3^84 
 » > 
 
 7^41 
 > > 
 
 3-52 
 
 6 '79 
 » J 
 
 •375 
 
 •45 
 » J 
 
THE STRENGTH OF CEMENT. 
 
 Neat, and with diflferent proportions of Sand, tested by Crushing in a Hydraulic Fn 
 
 Water. 
 
 Average Weight of Five Moulds, 
 One Year Old. 
 
 Broke at Tons. 
 
 ■ 
 
 Not CJompressed. 
 
 Compressed. 
 
 Not Compressed. 
 
 Compressed. 
 
 Not Compressed. 
 
 Measure. 
 
 Weight. 
 
 Air. 
 
 Water. 
 
 Air. 
 
 Water. 
 
 Air. 
 
 Water. 
 
 Air. j Water. 
 
 1-625 
 > > 
 
 1-75 
 > » 
 
 9-51 
 
 1 
 
 9*76 
 
 9-24 
 
 9-47 
 
 96-60 
 
 132-62 
 
 112-46 
 .. 
 
 113-86 
 
 Neat. 
 > ' 
 
 1-1225 
 
 1-35 
 » ? 
 
 9^65 
 
 9-93 
 
 9-28 
 
 9-67 
 
 82-80 
 
 83-32 
 
 63-26 
 
 62-74 
 
 1 to 1 
 1 > 
 > ) 
 
 i-6o 
 
 1-20 
 
 9-14 
 
 9-59 
 
 8-85 
 
 9-25 
 
 70-00 
 
 57-14 
 
 41-48 
 
 39-40 
 
 2 to 1 
 > » 
 > » 
 
 •9375 
 ! » ' 
 
 1-12 
 
 9-13 
 
 9-56 
 
 8-50 
 
 6-30 
 
 53-80 
 
 26-60 
 
 26-50 
 
 21-70 
 
 3 to 1 
 
 9 > 
 
 •9375 
 > > 
 
 1-12 
 
 8-79 
 
 9-51 
 
 8-24 
 
 9-08 
 
 43-60 
 
 29-92 
 
 19-82 
 
 13-72 
 
 4 to 1 
 > » 
 > » 
 
 •875 
 > ■> 
 
 I'os 
 
 8-64 
 
 9-48 
 
 8-15 
 
 8-86 
 
 37-40 
 
 15 -io 
 
 15-28 
 
 8-60 
 
 5tol 
 » » 
 
 » > 
 
 •875 
 J » 
 
 l'65 
 
 5 > 
 
 8-43 
 
 9-38 
 
 7*94 
 
 8-73 
 
 30-28 
 
 11-24 
 
 11 -oo 
 
 5-78 
 
 6tol 
 » > 
 
 » > 
 
 •875 
 
 l-"()5 
 » > 
 
 8-40 
 
 9-37 
 
 7-84 
 
 8-70 
 
 28-88 
 
 10-54 
 
 9-05 
 
 4-26 
 
 7 to 1 
 > ) 
 
 » > 
 
 •875 
 
 1-65 
 
 8-33 
 
 9-43 
 
 7-69 
 
 8-56 
 
 19-24 
 
 8-i8 
 
 \ '06 
 
 2-32 
 
 8 to 1 
 > > 
 
 -875 
 
 i-os 
 
 8-36 
 
 9-25 
 
 7-68 
 
 8-54 
 
 17-52 
 
 7-42 
 
 5-32 
 
 2-32 
 
 9 to 1 
 » > 
 » • 
 
 -875 
 
 1-05 
 
 J 5 
 
 8-27 
 
 9-30 
 
 7-61 
 
 8-75 
 
 15-44 
 
 5-62 
 
 4-80 
 
 2-28 
 
 10 to 1 
 
 > > 
 
 > > 
 
 K 
 
130 
 
 THE STRENGTH OF CEMENT. 
 
 C Sebies.— CEMENT BRICKS. 
 
 Portland Cement Bricks (9" x H" x 3") — Neat, and with different 
 Proportions of Sand, tested by Crushing in Hydraulic Press. 
 
 Weight of one Bushel of Cement, 110' 56 lbs. 
 
 Cement, Neat. 
 
 Cement 
 Sand 
 
 Water 
 
 When 
 Moulded 
 When 
 Tested 
 
 Cement 
 Sand 
 
 Water 
 
 When 
 Moulded 
 When 
 Tested 
 
 (Measure 
 
 \ Weight 
 
 /Measure 
 
 \Weight 
 
 /Measure 
 
 \Weight 
 
 4 • 34 pints. 
 7-50 lbs. 
 
 Nil. . . 
 
 Nil. . . 
 1-625 pint. 
 1-75 lb. 
 
 [Oct. 1, 1867. 
 [Oct. 1, 1868. 
 
 /Measure 
 \Weight 
 / Measure 
 \ Weight 
 /Measure 
 \ Weight 
 
 }Oct. 7, 1867 
 
 4-64 pints. 
 8-03 lbs. 
 Nil. . . 
 Nil. . . 
 1-375 pint. 
 1-65 lb. 
 
 [Oct. 7, 1868. 
 
 Weight of Five 
 
 Moulds after 
 being kept One 
 Year. 
 
 In 
 Air. 
 
 lbs. 
 
 9-25 
 9-20 
 9-25 
 9-25 
 9-26 
 
 9-24 
 
 9-51 
 9-50 
 9-52 
 9-54 
 9-50 
 
 9-51 
 
 In 
 Water. 
 
 lbs. 
 
 Broke at Tons. 
 
 In 
 Air. 
 
 120 '0 
 110-1 
 114-6 
 107-0 
 110-6 
 
 9-47 112-46 
 
 9-80 
 9-75 
 9-73 
 9-78 
 9-75 
 
 90-0 
 
 96- 5 
 100-0 
 
 97- 3 
 99-2 
 
 9-76 96-60 
 
 In 
 Water. 
 
 Ill 
 115 
 112 
 116 
 113 
 
 Number 
 of 
 Test. 
 
 113-86 
 
 118-0 
 143-8 
 128-1 
 146-2 
 127-0 
 
 101 
 102 
 103 
 104 
 105 
 106 
 107 
 108 
 109 
 110 
 
 Average. 
 
 132-62 
 
 101 
 102 
 103 
 104 
 105 
 106 
 107 
 108 
 109 
 110 
 
 Average. 
 
 Proportion of Sand, 1 to 1. 
 
 Cement 
 Sand 
 
 Water 
 
 When 
 Moulded 
 When 
 Tested 
 
 /Measure 
 \Weight 
 /Measure 
 \ Weight 
 /Measure 
 \Weight 
 
 JSept. 30, 1867. 
 jSept. 30, 1868. 
 
 2-42 pints. 
 4-19 lbs. 
 2-31 pints. 
 4-45 lbs. 
 1-2225 pint. 
 1-35 lb. 
 
 9-27 
 
 
 65-0 
 
 
 91 
 
 9-28 
 
 
 64-6 
 
 
 92 
 
 9-30 
 
 
 64-5 
 
 
 93 
 
 9-32 
 
 
 62-2 
 
 
 94 
 
 9-25 
 
 
 60-0 
 
 
 95 
 
 
 9-66 
 
 
 57-6 
 
 96 
 
 
 9-64 
 
 
 74-0 
 
 97 
 
 
 9-64 
 
 
 56-8 
 
 98 
 
 
 9-70 
 
 
 56-9 
 
 99 
 
 
 9-70 
 
 
 68-4 
 
 100 
 
 9-28 
 
 9-67 
 
 63-26 . 
 
 62-74 
 
 Average. 
 
 o 
 
THE 8TEENGTH OF CEMENT. 
 
 131 
 
 C Series— CEMENT BMCKS— continued. 
 
 Portland Cement Bricks (9" x ih" x 3") — Neat, and with different 
 Proportions of Sand, tested by Crushing in Hydraulic Press. 
 
 Weight of one Bushel of Cement, 110 '56 lbs. 
 
 Proportion of Sand, 1 to 1 — continued. 
 
 Cement 
 Sand 
 
 Water 
 
 When 
 Moulded 
 When 
 Tested 
 
 /Measure 
 \Weight 
 /Measure 
 \Weight 
 /Measure 
 \Weight 
 
 Joct. 7, 1867. 
 JOct. 7, 1868. 
 
 2-39 pints. 
 4-13 lbs. 
 2-38 pints. 
 4-60 lbs. 
 
 0- 875 pint. 
 
 1- 05 lb. 
 
 Weight of Five 
 Moulds aft' r 
 being kept One 
 Year. 
 
 In 
 Air. 
 
 In 
 
 Water. 
 
 Broke at Tons. 
 
 in 
 Air. 
 
 lbs. 
 9-65 
 9-67 
 9-67 
 9-65 
 9-63 
 
 9-65 
 
 9-91 
 9-95 
 9-92 
 9-93 
 9-93 
 
 9-93 
 
 85-0 
 
 84- 0 
 78-2 
 
 85- 6 
 81-2 
 
 In 
 Water. 
 
 88-2 
 84-0 
 83-5 
 79-3 
 81-6 
 
 Number 
 of 
 Test. 
 
 91 
 92 
 93 
 94 
 95 
 96 
 97 
 98 
 99 
 100 
 
 82-8 
 
 83-32 
 
 Average.' 
 
 Proportion of Sand, 2 to 1. 
 
 Cement 
 Sand 
 
 Water 
 
 When 
 Moulded 
 When 
 Tested 
 
 Cement 
 Sand 
 
 Water 
 
 When 
 Moulded 
 When 
 Tested 
 
 /Measure 
 \Weight 
 /Measure 
 \Weight 
 /Measure 
 \Weight 
 
 jSept. 30, 1867 
 
 1- 45 
 
 2- 51 
 2-91 
 5-62 
 1-00 
 1-20 
 
 I Sept. 
 
 30, 1868. 
 
 /Measure 
 \Weight 
 /Measure 
 \Weight 
 /Measure 
 \Weigbt 
 
 jOct. 5, 1867. 
 
 1- 63 
 
 2- 82 
 2-83 
 5-46 
 0-75 
 0-90 
 
 jOct. 5, 1868. 
 
 pint. 
 
 lbs. 
 
 pints. 
 
 lbs. 
 
 piut. 
 
 lb. 
 
 pint. 
 
 lbs. 
 
 pints. 
 
 lbs. 
 
 pint. 
 
 lb. 
 
 8-90 
 
 
 39-6 
 
 
 81 
 
 8-85 
 
 
 39-6 
 
 
 82 
 
 8-85 
 
 
 42-4 
 
 
 83 
 
 8-83 
 
 
 43- 0 
 
 
 84 
 
 8-83 
 
 
 42-8 
 
 
 85 
 
 
 9-20 
 
 
 39-4 
 
 86 
 
 
 9-26 
 
 
 39-4 
 
 87 
 
 
 9-30 
 
 
 39-8 
 
 88 
 
 
 9-28 
 
 
 39-2 
 
 89 
 
 
 9-20 
 
 
 39-2 
 
 90 
 
 8-85 
 
 9-25 
 
 41-48 
 
 39-40 
 
 Average. 
 
 9-15 
 
 
 71-0 
 
 
 81 
 
 9-15 
 
 
 69-0 
 
 
 82 
 
 9-13 
 
 
 68-2 
 
 
 83 
 
 9-14 
 
 
 70-8 
 
 
 84 
 
 9-13 
 
 
 71 -0 
 
 
 85 
 
 
 9-60 
 
 
 59*-§ 
 
 86 
 
 
 9-61 
 
 
 56-0 
 
 87 
 
 
 9-57 
 
 
 55-0 
 
 88 
 
 
 9-58 
 
 
 60-0 
 
 89 
 
 
 9-58 
 
 
 55-2 
 
 90 
 
 9-14 
 
 9-59 
 
 70-0 
 
 57-14 Average. 
 
 K 2 
 
132 
 
 THE STKENGTH OP CEMENT. 
 
 C Series.— CEMENT BRICKS— contimied. 
 
 PoKTLAKD Cement Bricks (9"x4i"x3") — Neat, and with different 
 Proportions of Sand, tested by Crushing in Hydraulic Press. 
 
 Weight of oue Bushel of Cement, 110*56 lbs. 
 
 Proportion of Sand, B to 1. 
 
 Cement 
 Sand 
 
 Water 
 
 When 
 Moulded 
 When 
 Tested 
 
 Cement 
 Sand 
 
 Water 
 
 When 
 Moulded 
 When 
 Tested 
 
 /Measure I'OQ pint, 
 
 t Weight 1-83 lb. 
 
 (Measure 3 •19 pints. 
 
 \Weight 6-14 lbs. 
 /Measure 0-9375 pint. 
 
 \Weight 1-12 lb. 
 
 JSept. 28, 1867. 
 Jsept. 28, 1868. 
 
 /Measure 
 \Weight 
 /Measure 
 \Weight 
 /Measure 
 \Weight 
 
 JOct. 5, 1867, 
 jOct. 5, 1868 
 
 I'll pint. 
 1-97 lb. 
 3-43 pints. 
 6-62 lbs. 
 0-625 pint. 
 0-75 lb. 
 
 Weight of Five 
 Moulds after 
 being kept One 
 Year. 
 
 In 
 Air. 
 
 lbs. 
 50 
 47 
 45 
 55 
 53 
 
 9-13 
 
 In 
 "Water. 
 
 lbs. 
 
 .50 9-32 
 
 Broke at Tons. 
 
 In 
 Air. 
 
 26 
 
 9-56 
 
 50 
 
 53-80 
 
 In 
 Water. 
 
 21-70 
 
 28-4 
 26-0 
 26-0 
 26-4 
 26-2 
 
 26-60 Average, 
 
 Proportion of Sand, 4 to 1. 
 
 8-28 
 
 
 20-0 
 
 
 61 
 
 8-20 
 
 
 19-2 
 
 
 62 
 
 8-24 
 
 
 20-4 
 
 
 63 
 
 8-20 
 
 
 20-0 
 
 
 64 
 
 8-28 
 
 
 19-5 
 
 
 65 
 
 
 9-05 
 
 
 14-0 
 
 66 
 
 
 9-07 
 
 
 14-2 
 
 67 
 
 
 9-10 
 
 
 13-5 
 
 68 
 
 
 9-10 
 
 
 13-5 
 
 69 
 
 
 9-09 
 
 
 13-4 
 
 70 
 
 8-24 
 
 9-08 
 
 19-82 
 
 13-72 
 
 Average. 
 
 Cement 
 Sand 
 
 Water 
 
 When 
 Moulded 
 When 
 Tested 
 
 /Measure 0-82 pint. 
 
 \Weight 1-42 lb. 
 
 /Measure 3-29 pints. 
 
 \ Weight 6-36 lbs. 
 
 /Measure 0 • 9375 pint. 
 
 \Weight 1-12 lb. 
 
 JSept. 27, 1867. 
 
 jSept. 27, 1868. 
 
THE STRENGTH OF CEMENT, 
 
 133 
 
 C Series.— CEMENT BUICKQ— continued. 
 
 Portland Cement Bricks (9" x 4^" x 3")— Neat, and with different 
 Proportions of Sand, tested by Crushing in Hydraulic Press. 
 
 Weight of one Bushel of Cement, 110*56 lbs. 
 Proportion of Sand, 4 to 1 — continued. 
 
 Cement 
 Sand 
 
 Water 
 
 When 
 Moulded 
 When 
 Tested 
 
 /Measure 0*88 
 \Weight 1-53 
 /Measure 3 '55 
 \ Weight 6-85 
 /Measure 0-50 
 \Weight 0-60 
 
 jOct. 4, 1867. 
 JOct. 5, 
 
 1868. 
 
 pint, 
 lb. 
 
 pints, 
 lbs. 
 pint, 
 lb. 
 
 Weight of Five 
 Moulds after 
 being kept One 
 Year. 
 
 la 
 Air. 
 
 lbs. 
 8-80 
 81 
 80 
 76 
 79 
 
 In 
 Water. 
 
 lbs. 
 
 9-50 
 9-56 
 9-50 
 9-50 
 9-50 
 
 Broke at Tons. 
 
 In 
 Air. 
 
 In 
 Water. 
 
 45-0 
 44-0 
 43-0 
 43-0 
 43-0 
 
 23-2 
 
 20- 0 
 
 21- 4 
 20-0 
 20-0 
 
 Number 
 of 
 Test. 
 
 61 
 
 62 
 63 
 64 
 65 
 66 
 67 
 68 
 69 
 70 
 
 8-79 i 9-51 
 
 43-60 i 20-92 i Average. 
 
 Proportion of Sand, 5 to 1. 
 
 Cement 
 Sand 
 
 Water 
 
 When 
 Moulded 
 When 
 Tested 
 
 /Measure 0-68 pint. 
 
 \Weight l-]8 lb. 
 
 /Measure 3-43 pints. 
 
 \ Weight 6-62 lbs. 
 
 /Measure 0-876 pint. 
 
 \Weight 1-05 lb. 
 
 jSept. 26, 1867. 
 jSept. 26, 1868. 
 
 Weight of each 
 Brick, being the 
 average of Five 
 after being kept 
 One Year. 
 
 In 
 Air. 
 
 lbs. 
 8-12 
 8-17 
 8-19 
 8-15 
 8-15 
 
 In 
 Water. 
 
 lbs. 
 
 •86 
 •92 
 •84 
 •86 
 •83 
 
 8^15 ! 8-86 
 
 Broke at Tons. 
 
 In 
 Air. 
 
 15^28 
 
 In 
 Water. 
 
 Number 
 of 
 Tests. 
 
 51 
 52 
 53 
 54 
 55 
 56 
 57 
 58 
 59 
 60 
 
 8-60 'Average. 
 
134 
 
 THE STRENGTH OF CEMENT. 
 
 C Series— CEMENT BUICKS— continued. 
 
 Portland Cement Bricks (9" x 4i" x 3")— Neat, and with different 
 Proportions of Sand, tested by Crushing in Hydraulic Press. 
 Weight of one Busliel of Cement, 110*50 lbs. 
 
 Proportion op Sand, 5 to 1 — continued. 
 
 Cement 
 Sand 
 
 Water 
 
 When 
 Moulded 
 When 
 Tested 
 
 /Measure 
 \Weight 
 /Measure 
 \Weight 
 /Measure 
 \Weight 
 
 JOct. 4, 1867. 
 JOct. 5, 1868. 
 
 0- 72 
 
 1- 25 
 3-64 
 7-02 
 0-50 
 0-60 
 
 pint, 
 lb. 
 
 pints, 
 lbs. 
 pint, 
 lb. 
 
 Weight of each 
 Brick, being the 
 average of Five 
 after Iselng liept 
 One Year. 
 
 In 
 Air. 
 
 8-64 
 8-64 
 8-65 
 8-63 
 8-63 
 
 In 
 
 Water. 
 
 lbs. 
 
 8-64 9-48 
 
 Broke at Tons. 
 
 In 
 Air. 
 
 37-0 
 87-0 
 
 37- 5 
 
 38- 5 
 37-0 
 
 37-40 
 
 In 
 
 Water. 
 
 15-0 
 15-8 
 15-2 
 15-0 
 14-5 
 
 15 • 10 Average, 
 
 Proportion of Sand, 6 to 1. 
 
 Cement 
 Sand 
 
 Water 
 
 When 
 Moulded 
 When 
 Tested 
 
 Cement 
 Sand 
 
 Water 
 
 When 
 Moulded 
 When 
 Tested 
 
 /Measure 
 \Weight 
 /Measure 
 \Weight 
 /Measure 
 \Weight 
 
 JSept. 26, 1867. 
 Jsept. 26, 1868. 
 
 0-58 pint. 
 1 00 lb. 
 3-48 pints. 
 6-71 lbs. 
 
 0- 875 pint. 
 
 1- 05 lb. 
 
 /Measure 
 \Weight 
 /Measure 
 \Weight 
 /Measure 
 \Weight 
 
 jOct. 3, 1867. 
 }Oct. 3, 1868. 
 
 0- 60 pint. 
 
 1- 04 lb. 
 3-64 pints. 
 7-03 lbs. 
 0-375 pint. 
 0-45 lb. 
 
 7-94 
 
 8-40 
 8-41 
 8-44 
 8-44 
 8-45 
 
 8-43 
 
 9-88 
 9-37 
 
 9-88 
 
 •73 I 11 
 
 30-28 
 
 00 
 
 6-4 
 5-9 
 5-9 
 5-5 
 5-2 
 
 41 
 42 
 48 
 44 
 45 
 46 
 47 
 48 
 49 
 50 
 
 5-78 
 
 10- 8 
 
 11- 4 
 
 12- 0 
 11-0 
 11-0 
 
 11-24 
 
 Average. 
 
 41 
 42 
 43 
 44 
 45 
 46 
 47 
 48 
 49 
 50 
 
 Average. 
 
THE STEENGTH OF CEMENT. 135 
 
 C Seeies.— CEMENT BMCKS— continued. '-.^ 
 
 Portland Cement Bricks (9" x 4^" x 3") — Neat, and with different 
 Proportions of Sand, tested by Crushing in Hydraulic Press. 
 Weight of one Bushel of Cement, 110-56 lbs. 
 Proportion of Sand, 7 to 1. 
 
 Cement 
 Sand 
 
 Water 
 
 When 
 Moulded 
 When 
 Tested 
 
 Cement 
 Sand 
 
 Water 
 
 When 
 Moulded 
 When 
 Tested 
 
 /Measure 
 \ Weight 
 /Measure 
 \Weight 
 /Measure 
 \Weight 
 
 jsept. 25, 1867, 
 jSept. 26, 1868, 
 
 0-48 pint. 
 0-84 lb. 
 3*44 pints. 
 6-64 lbs. 
 
 0- 875 pint. 
 
 1- 05 lb. 
 
 /Measure 
 \Weight 
 /Measure 
 \Weight 
 /Measure 
 \Weight 
 
 jOct. 3, 1867. 
 joct. 3, 1868. 
 
 0-52 pint. 
 0-90 lb. 
 8-71 pints. 
 7-15 lbs. 
 0-375 puit. 
 0-45 lb. 
 
 Weight of each 
 Brick, being the 
 average of Five 
 after being Itept 
 One Year. 
 
 In 
 Air. 
 
 lbs. 
 7-74 
 7-84 
 7-82 
 7-90 
 7-90 
 
 7-84 
 
 -40 
 -38 
 -40 
 -42 
 •41 
 
 8-40 
 
 In 
 
 Water. 
 
 lbs. 
 
 8-69 
 8-67 
 8-67 
 8-71 
 8-77 
 
 8-705 
 
 9-37 
 9-35 
 9-42 
 9-39 
 9-35 
 
 9-37 
 
 Broke at Tons. 
 
 In 
 Air. 
 
 8- 4 
 
 9- 0 
 9-0 
 9-8 
 
 9-05 
 
 28-88 
 
 In 
 Water. 
 
 4-0 
 
 3- 2 
 
 4- 2 
 
 4- 8 
 
 5- 1 
 
 4'26 
 
 10- 5 
 
 11- 2 
 10-4 
 10-4 
 10-2 
 
 10-54 
 
 Number 
 of 
 Test. 
 
 31 
 32 
 33 
 34 
 35 
 36 
 37 
 38 
 39 
 40 
 
 Average. 
 
 31 
 
 32 
 33 
 34 
 35 
 36 
 37 
 38 
 39 
 40 
 
 Average. 
 
 Proportion of Sand, 8 to 1. 
 
 Cement 
 Sand 
 
 Water 
 
 When 
 Moulded 
 When 
 Testel 
 
 /Measure 
 \Weight 
 /Measure 
 \Weight 
 /Measure 
 \Weight 
 
 jSept. 24, 1867 
 jsept. 25, 1868 
 
 0-43 pint. 
 
 0- 74 lb. 
 3-41 pints. 
 6-63 lbs. 
 0 -875 pint. 
 
 1- 05 lb. 
 
 7-694 
 
 60 
 55 
 56 
 55 
 55 
 
 •562 
 
 8-0 
 7^0 
 6^7 
 6-9 
 6-7 
 
 7-06 
 
 2-3 
 2-2 
 2-6 
 2-2 
 2-3 
 
 2-32 
 
 21 
 22 
 
 23 
 24 
 25 
 26 
 27 
 28 
 29 
 30 
 
 Average. 
 
136 
 
 THE STRENGTH OF CEMENT. 
 
 C Series.— CEMENT BRICKS— continued. 
 
 Portland Cement Bricks (9" x 4:h" x 3")— Neat, and with different 
 Proportions of Sand, tested by Crushing in Hydraulic Press. 
 
 Weight of one Bushel of Cement, 110 • 56 lbs. 
 
 Proportion of Sand, 8 to 1 — continued. 
 
 Cement 
 Sand 
 
 Water 
 
 When 
 Moulded 
 When 
 Tested 
 
 /Measure 
 \Weight 
 /Measure 
 \Weight 
 /Measure 
 \Weight 
 
 joct. 2, 1867. 
 joct. 2, 1868. 
 
 0-46 pint. 
 0-80 lb. 
 3-75 pints. 
 7-24 lbs. 
 0-375 pint. 
 0-45 lb. 
 
 Weight of each 
 Brick, being the 
 average of Five 
 after being kept 
 One Year. 
 
 In 
 Air. 
 
 lbs. 
 33 
 34 
 35 
 32 
 32 
 
 8-33 
 
 In 
 Water. 
 
 9-43 
 
 Broke at Tons. 
 
 In 
 Air. 
 
 19-24 
 
 In 
 Water. 
 
 8-18 
 
 Number 
 of 
 Test. 
 
 21 
 
 22 
 23 
 24 
 25 
 26 
 27 
 28 
 29 
 30 
 
 Proportion ojf Sand, 9 to 1. 
 
 7 
 
 70 
 
 
 5 
 
 4 
 
 
 11 
 
 7 
 
 70 
 
 
 5 
 
 2 
 
 
 12 
 
 7 
 
 68 
 
 
 5 
 
 2 
 
 
 13 
 
 7 
 
 70 
 
 
 5 
 
 5 
 
 
 14 
 
 7 
 
 65 
 
 
 5 
 
 3 
 
 
 15 
 
 
 
 8-55 
 
 
 
 2-2 
 
 16 
 
 
 
 8-54 
 
 
 
 2-2 
 
 17 
 
 
 
 8-54 
 
 
 
 2-2 
 
 18 
 
 
 
 8-56 
 
 
 
 2-5 
 
 19 
 
 
 
 8-54 
 
 
 
 2-5 
 
 20 
 
 7 
 
 686 
 
 8-546 
 
 6 
 
 32 
 
 2-32 
 
 Average. 
 
 8 
 
 38 
 
 
 17 
 
 8 
 
 
 11 
 
 8 
 
 32 
 
 
 17 
 
 6 
 
 
 12 
 
 8 
 
 40 
 
 
 17 
 
 8 
 
 
 13 
 
 8 
 
 30 
 
 
 17 
 
 0 
 
 
 14 
 
 8 
 
 39 
 
 
 17 
 
 4 
 
 
 15 
 
 
 
 9-24 
 
 
 
 7'5 
 
 16 
 
 
 
 9-26 
 
 
 
 7-4 
 
 17 
 
 
 
 9-26 
 
 
 
 7V5 
 
 18 
 
 
 
 9-23 
 
 
 
 7-2 
 
 19 
 
 
 
 9-27 
 
 
 
 7-5 
 
 20 
 
 8-36 
 
 9-25 
 
 17 
 
 52 
 
 7-42 
 
 Average. 
 
 Cement 
 Sand 
 
 Water 
 
 When 
 Moulded 
 When 
 Tested 
 
 /Measure 
 \Weight 
 /Measure 
 \Weight 
 /Measure 
 (Weight 
 
 JSept. 24, 1867. 
 Jsept. 24, 1868. 
 
 0-39 pint. 
 0-66 lb. 
 3-48 pints. 
 6-72 lbs. 
 
 0- 875 pint. 
 
 1- 05 lb. 
 
 /Measure 
 \Weight 
 /Measure 
 \Weight 
 /Measure 
 \Weight 
 
 JOct. 2, 1867. 
 
 Cement 
 Sand 
 
 Water 
 
 When 
 Moulded 
 
 0-42 pint. 
 0-73 lb. 
 3*82 pints. 
 7 '36 lbs. 
 0-375 pint. 
 0-45 lb. 
 
 S 
 
 o 
 O 
 
THE STRENGTH OF CEMENT. 
 
 137 
 
 C Series— CEMENT BBIGKS— continued. 
 
 Portland Cement Bricks (9" x 4i" x 3")— Neat, and with different 
 Proportions of Sand, tested by Crushing in Hydraulic Press. 
 Weight of one Bushel of Cement, 110*56 lbs. 
 Proportion of Sand, 10 to 1. 
 
 Cement 
 Sand 
 
 Water 
 
 When 
 Moulded 
 When 
 Tested 
 
 Cement 
 Sand 
 
 Water 
 
 When 
 Moulded 
 When 
 Tested 
 
 (Measure 
 \Weight 
 (■Measure 
 \ Weight 
 ] Measure 
 \Weight . 
 
 Jsept. 23, 1867, 
 jsept. 23, 1868, 
 
 0-86 pint. 
 0-60 lb. 
 3 • 52 pints. 
 6-79 lbs. 
 
 0- 875 pint. 
 
 1- 05 lb. 
 
 /Measure 
 \Weight 
 ] Measure 
 \Weight 
 ("Measure 
 \Weight 
 
 JOot. 1, 1867, 
 Joot. 1, 1868 
 
 0-39 pint. 
 0-66 lb. 
 3-84 pmts. 
 7-41 lbs. 
 0-375 pint. 
 0-45 lb. 
 
 Weight of Five 
 Moulds after 
 being kept One 
 Year. 
 
 In 
 Air. 
 
 In 
 Water. 
 
 lbs. 
 7-64 
 7-60 
 7-56 
 7-64 
 7-64 
 
 lbs. 
 
 8-80 
 8-82 
 8-70 
 8-65 
 8-80 
 
 7-616 8-754 
 
 8-23 
 8-27 
 8-30 
 8-27 
 8-30 
 
 8-27 
 
 9-30 
 9-25 
 9-31 
 9-32 
 9-33 
 
 9-30 
 
 Broke at Tons. 
 
 In 
 Air. 
 
 4-50 
 4-60 
 
 4- 50 
 
 5- 40 
 5-00 
 
 4-80 
 
 14- 6 
 16-6 
 16-6 
 
 15- 0 
 15-0 
 
 In 
 Water. 
 
 2-50 
 2-50 
 2-20 
 2-10 
 2-10 
 
 2-28 
 
 5-5 
 5-0 
 5-5 
 
 5- 7 
 
 6- 4 
 
 15-44 5-62 
 
 Number 
 of 
 Test. 
 
 1 
 
 2 
 3 
 4 
 5 
 6 
 7 
 8 
 9 
 10 
 
 Average. 
 
 Average. 
 
138 
 
 THE STRENGTH OF CEMENT. 
 
 D Sebies.— CONCRETE BLOCKS. 
 
 Portland Cement Concrete Blocks of various Materials, set and kept in 
 Air for One Year, also set and kept in Water for the same time. 
 
 Table I. 
 Material — Ballast. 
 
 Size of Block— 12" x 12" x 12". Compressed. 
 
 Propor- 
 tion. 
 
 Weight in lbs. 
 
 Weight of each 
 Block in lbs. 
 
 Crushed at Tons. 
 
 Remarks. 
 
 Cement. 
 
 Sand. 
 
 Water. 
 
 Kept in 
 Air. 
 
 Kept in 
 Water. 
 
 Air. 
 
 Water. 
 
 1 to 1 
 
 59-36 
 
 66-96 
 
 16-00 
 
 137-60 
 
 147-25 
 
 107-0* 
 
 170-50 
 
 * Exceptional. 
 
 2 1 
 
 42-64 
 
 96-40 
 
 12-00 
 
 142-60 
 
 152-50 
 
 149-0 
 
 160-0 
 
 3 „ 1 
 
 32-00 
 
 108-56 
 
 10-00 
 
 145-25 
 
 152-25 
 
 113-0 
 
 115-50 
 
 
 4 „ 1 
 
 25-84 
 
 116-96 
 
 8-80 
 
 145-75 
 
 152-50 
 
 103-0 
 
 108-50 
 
 
 5 „ 1 
 
 21-28 
 
 120-24 
 
 8-00 
 
 142-10 
 
 150-95 
 
 89-0 
 
 99-50 
 
 
 6 „ 1 
 
 18-08 
 
 122-48 
 
 8-00 
 
 141-56 
 
 150-00 
 
 80-50 
 
 91-0 
 
 
 V „ 1 
 
 15-84 
 
 125-04 
 
 7-60 
 
 141-70 
 
 150-20 
 
 75-0 
 
 80-50 
 
 
 8 „ 1 
 
 14-08 
 
 127-04 
 
 7-60 
 
 142-30 
 
 150-80 
 
 61-50 
 
 76-0 
 
 
 9 „ 1 
 
 12-64 
 
 128-64 
 
 7-20 
 
 142-10 
 
 151-50 
 
 54-0 
 
 68-50 
 
 
 10 „ 1 
 
 11-36 
 
 128-88 
 
 6-80 
 
 142-00 
 
 150-00 
 
 48-50 
 
 48-0 
 
 
 Table II. 
 Material — Ballast. 
 
 Size of Block— 6" x 6" x 6". Compressed. 
 
 1 to 1 
 
 7 
 
 42 
 
 8 
 
 37 
 
 2 
 
 00 
 
 17 
 
 50 
 
 18 
 
 04 
 
 38 
 
 0 
 
 33 
 
 60 
 
 
 2 „ 1 
 
 5 
 
 33 
 
 12 
 
 05 
 
 1 
 
 50 
 
 17 
 
 78 
 
 18 
 
 97 
 
 43 
 
 0 
 
 34 
 
 50 
 
 
 3 „ 1 
 
 4 
 
 00 
 
 13 
 
 57 
 
 1 
 
 25 
 
 18 
 
 28 
 
 19 
 
 35 
 
 30 
 
 0 
 
 35 
 
 50 
 
 
 4 1 
 
 3 
 
 23 
 
 14 
 
 62 
 
 1 
 
 10 
 
 18 
 
 28 
 
 18 
 
 71 
 
 30 
 
 0 
 
 28 
 
 00 
 
 
 5 „ 1 
 
 2 
 
 66 
 
 15 
 
 03 
 
 1 
 
 00 
 
 18 
 
 26 
 
 18 
 
 98 
 
 24 
 
 50 
 
 35 
 
 50 
 
 
 6 „ 1 
 
 2 
 
 26 
 
 15 
 
 31 
 
 1 
 
 00 
 
 17 
 
 90 
 
 18 
 
 60 
 
 20 
 
 40 
 
 19 
 
 60 
 
 
 7 „ 1 
 
 1 
 
 98 
 
 15 
 
 63 
 
 
 95 
 
 17 
 
 85 
 
 18 
 
 85 
 
 16 
 
 50 
 
 16 
 
 0 
 
 
 8 „ 1 
 
 1 
 
 76 
 
 15 
 
 88 
 
 
 95 
 
 17 
 
 86 
 
 18 
 
 90 
 
 13 
 
 50 
 
 13 
 
 50 
 
 
 9 „ 1 
 
 1 
 
 58 
 
 16 
 
 08 
 
 
 90 
 
 17 
 
 78 
 
 19 
 
 0 
 
 12 
 
 0 
 
 11 
 
 00 
 
 
 10 „ 1 
 
 1 
 
 42 
 
 16 
 
 11 
 
 
 85 
 
 17 
 
 68 
 
 18 
 
 70 
 
 10 
 
 50 
 
 10 
 
 50 
 
 
 Table III. 
 Material — Ballast. 
 
 Size of Block— 6" x 6" x 6". Not Compressed. 
 
 1 to 1 
 
 7-12 
 
 8-04 
 
 1 
 
 •92 
 
 ]6 
 
 44 
 
 17 
 
 60 
 
 30 
 
 -0 
 
 37-50 
 
 2 „ 
 
 1 
 
 4-90 
 
 11-09 
 
 1 
 
 -38 
 
 17 
 
 57 
 
 18 
 
 03 
 
 38 
 
 50 
 
 36-00 
 
 3 „ 
 
 1 
 
 3-56 
 
 12-11 
 
 1 
 
 11 
 
 17 
 
 75 
 
 18 
 
 98 
 
 24 
 
 0 
 
 28-00 
 
 4 „ 
 
 1 
 
 2-85 
 
 12-92 
 
 
 97 
 
 17 
 
 84 
 
 18 
 
 28 
 
 28 
 
 0 
 
 27-00 
 
 5 „ 
 
 1 
 
 2-33 
 
 13-18 
 
 
 87 
 
 17 
 
 90 
 
 18 
 
 73 
 
 24 
 
 0 
 
 23-50 
 
 6 „ 
 
 1 
 
 2-00 
 
 13-49 
 
 
 88 
 
 17 
 
 35 
 
 18 
 
 30 
 
 18 
 
 20 
 
 17-00 
 
 7 „ 
 
 1 
 
 1-77 
 
 14-02 
 
 
 85 
 
 17 
 
 32 
 
 17 
 
 90 
 
 14 
 
 0 
 
 12-50 
 
 8 „ 
 
 1 
 
 1-60 
 
 14-51 
 
 
 85 
 
 17 
 
 38 
 
 17 
 
 95 
 
 12 
 
 50 
 
 11-00 
 
 9 » 
 
 1 
 
 1-43 
 
 14-59 
 
 
 80 
 
 17 
 
 40 
 
 17 
 
 97 
 
 10 
 
 0 
 
 9-00 
 
 10 „ 
 
 1 
 
 1-26 
 
 14-35 
 
 
 75 
 
 17 
 
 20 
 
 17 
 
 50 
 
 8 
 
 0 
 
 7-00 
 
THE STRENGTH OP CEMENT. 
 
 139 
 
 D Seeies.— CONOEETE BLOCKS— continued. 
 
 PoETLAND Cement Conoeete Blocks of various Materials, set and kept in 
 Air for One Year, also set and kept in Water for the same time. 
 
 Table IV. 
 
 Materials — Various. 
 
 Size of Block— 12" x 12" x 12". Compressed. 
 
 Propor- 
 tion. 
 
 Weight in lbs. 
 
 Weight of each 
 Block in lbs. 
 
 Crushed at Tons. 
 
 Remarks. 
 
 Cement. 
 
 Sand. 
 
 Water. 
 
 Kept in 
 Air. 
 
 Kept in 
 Water. 
 
 Air. 
 
 Water. 
 
 6 tol 
 
 18 
 
 08 
 
 122-48 
 
 8-00 
 
 141-06 
 
 150-0 
 
 80-50 
 
 91-0 
 
 Ballast. 
 
 
 19 
 
 20 
 
 102-40 
 
 11-60 
 
 127-80 
 
 140-50 
 
 118-0 
 
 138-50 
 
 Portland stone. 
 
 
 18 
 
 48 
 
 116-48 
 
 10-40 
 
 143-50 
 
 147-54 
 
 113-20 
 
 96-50 
 
 Granite. 
 
 
 17 
 
 28 
 
 106-64 
 
 14-00 
 
 128-95 
 
 139-45 
 
 109-20 
 
 136-50 
 
 Pottery. 
 
 
 16 
 
 88 
 
 98-32 
 
 12-80 
 
 122-50 
 
 131-54 
 
 110-50 
 
 111-0 
 
 Slag. 
 
 
 16 
 
 24 
 
 111-28 
 
 11-60 
 
 131-90 
 
 141-33 
 
 116-00 
 
 126-0 
 
 Plints. 
 
 
 18 
 
 96 
 
 124-08 
 
 10-40 
 
 147-70 
 
 155-50 
 
 99-00 
 
 112-50 
 
 Glass. 
 
 Table V. 
 
 Materials — Various. 
 
 Size of Block— 12" x 12" x 12". Compressed. 
 
 8 to 1 
 
 14-08 
 
 127-04 
 
 7-60 
 
 142-30 
 
 150-80 
 
 61-50 
 
 76-0 
 
 Ballast. 
 
 
 14-88 
 
 106-08 
 
 13-20 
 
 130-00 
 
 140-30 
 
 110-0 
 
 126-50 
 
 Portland stone. 
 
 
 12-24 
 
 116-56 
 
 10-00 
 
 140-20 
 
 144-68 
 
 73-80 
 
 84-60 
 
 Granite. 
 
 
 13-12 
 
 108-24 
 
 12-80 
 
 127-40 
 
 136-20 
 
 97-50 
 
 118-0 
 
 Pottery. 
 
 
 12-80 
 
 98-96 
 
 12-00 
 
 114-60 
 
 127-85 
 
 85-20 
 
 70-0 
 
 Slag. 
 
 
 12-48 
 
 114-24 
 
 10-40 
 
 133-10 
 
 140-12 
 
 103-50 
 
 117-50 
 
 Flints. 
 
 
 14-56 
 
 126-32 
 
 9-20 
 
 143-20 
 
 153-23 
 
 65-0 
 
 94-0 
 
 Glass. 
 
 Table VI. 
 
 Materials — Various. 
 
 Size of Block— 12" x 12" x 12". Compressed. 
 
 10 tol 
 
 11-36 
 
 128-88 
 
 6-80 
 
 142 
 
 0 
 
 150 
 
 0 
 
 48-50 
 
 48 
 
 0 
 
 Ballast. 
 
 
 12-16 
 
 108-48 
 
 14-88 
 
 128 
 
 0 
 
 143 
 
 10 
 
 72-60 
 
 78 
 
 0 
 
 Portland stone. 
 
 
 9-84 
 
 116-82 
 
 9-20 
 
 139 
 
 85 
 
 142 
 
 80 
 
 49-80 
 
 60 
 
 50 
 
 Granite. 
 
 
 10-72 
 
 110-00 
 
 11-60 
 
 126 
 
 80 
 
 136 
 
 00 
 
 90-0 
 
 100 
 
 0 
 
 Pottery. 
 
 
 10-24 
 
 99-68 
 
 11-20 
 
 113 
 
 25 
 
 124 
 
 80 
 
 60-0 
 
 52 
 
 0 
 
 Slag. 
 
 
 10-08 
 
 114-96 
 
 10-20 
 
 130 
 
 00 
 
 141 
 
 00 
 
 70-0 
 
 98 
 
 0 
 
 Plints. 
 
 
 11-84 
 
 129-28 
 
 8-40 
 
 143 
 
 30 
 
 152 
 
 10 
 
 53-0 
 
 75 
 
 0 
 
 Glass. 
 
140 
 
 THE STBENGTH OF CEMENT. 
 
 D Sebies.— CONCEETB BLOCKS— continued. 
 
 Portland Cement Concrete Blocks of various Materials, set and kept in 
 Air for One Year, also set and kej)t in Water for the same time. 
 
 Table VII. 
 
 Materials — Various. 
 
 Size of Block— 6" x 6" x 6". Compressed. 
 When Moulded, Nov. 4, 1867. When Tested, Nov. 4, 1868. 
 
 Propor- 
 tion. 
 
 Weight in lbs. 
 
 Weight of each 
 Block in lbs. 
 
 Crushed at Tons. 
 
 Remarks. 
 
 Cement. 
 
 Sand. 
 
 Water. 
 
 Kept in 
 Air. 
 
 Kept in 
 Water. 
 
 Air. 
 
 Water. 
 
 6 to 1 
 
 2-26 
 
 15-31 
 
 1-00 
 
 17-90 
 
 18-60 
 
 20-40 
 
 19-60 
 
 Ballast. J 
 
 
 2-40 
 
 12-80 
 
 1-45 
 
 16-90 
 
 17-67 
 
 40-60 
 
 34-50 
 
 Portland atone. 
 
 
 2-31 
 
 14-56 
 
 1-30 
 
 18-53 
 
 18-88 
 
 30-50 
 
 27-0 
 
 Granite. 
 
 
 2-16 
 
 13-33 
 
 1-75 
 
 16-10 
 
 17-50 
 
 28-80 
 
 26-50 
 
 Pottery. 
 Slag. 
 
 
 2-11 
 
 12-29 
 
 1-60 
 
 15-08 
 
 16-61 
 
 23-0 
 
 23-50 
 
 
 2-03 
 
 13-91 
 
 1-45 
 
 16-50 
 
 17-65 
 
 20-50 
 
 24-00 
 
 Flints. 
 
 
 2-37 
 
 15-51 
 
 1-30 
 
 18-50 
 
 19-25 
 
 28-0 
 
 23-00 
 
 Glass. 
 
 Table VIII. 
 Materials — Various. 
 
 Size of Block — 6" x 6" x 6". Compressed. 
 When Moulded, Nov. 6, 1867. When Tested, Nov. 6, 1868. 
 
 8 to 1 
 
 1 
 
 76 
 
 15-88 
 
 
 95 
 
 17 
 
 86 
 
 18-90 
 
 13-50 
 
 13-50 Ballast. 
 
 
 1 
 
 86 
 
 13-26 
 
 1 
 
 65 
 
 16 
 
 32 
 
 17-50 
 
 33-00 
 
 29 - 00 Portland stone. 
 
 
 1 
 
 53 
 
 14-57 
 
 1 
 
 25 
 
 18 
 
 10 
 
 19-00 
 
 '19-60 
 
 16-00 Granite. 
 
 
 1 
 
 64 
 
 13-53 
 
 1 
 
 60 
 
 16 
 
 15 
 
 16-95 
 
 22-00 
 
 23-00 Pottery. 
 
 
 1 
 
 60 
 
 12-37 
 
 1 
 
 50 
 
 14 
 
 20 
 
 15-91 
 
 19-50 
 
 13-40; Slag. 
 
 
 1 
 
 56 
 
 14-28 
 
 1 
 
 30 
 
 16 
 
 45 
 
 17-62 
 
 17-50, 
 
 20-00 Flints. 
 
 
 1 
 
 82 
 
 15-79 
 
 1 
 
 15 
 
 18 
 
 00 
 
 18-93 
 
 18-00 
 
 17-50 Glass. 
 
 1 
 
 Table IX. 
 Materials — Various . 
 
 Size of Block — 6" x 6" x 6". Compressed. 
 When Moulded, Nov. 8, 1867. When Tested, Nov. 9, 1868. 
 
 lOtol 
 
 1-42 
 
 16-11 
 
 
 85 
 
 17-68 
 
 18-70 
 
 10 
 
 5o| 
 
 10-50 Ballast. 
 
 
 1-52 
 
 13-56 
 
 1 
 
 86 
 
 16-44 
 
 17-90 
 
 22 
 
 0 
 
 16-50: Portland stone. 
 
 
 1-23 
 
 14-60 
 
 1 
 
 15 
 
 17-60 
 
 18-50 
 
 15 
 
 50, 
 
 12-40 Granite. 
 
 
 1-34 
 
 13-75 
 
 1 
 
 45 
 
 16-09 
 
 16-80 
 
 18 
 
 50 
 
 19-00: Pottery. 
 
 
 1-28 
 
 12-46 
 
 1 
 
 40 
 
 14-00 
 
 15-50 
 
 10 
 
 50! 
 
 10-00. Slag. 
 
 
 1-26 
 
 14-37 
 
 1 
 
 15 
 
 16-15 
 
 17-60 
 
 15 
 
 00, 
 
 18-50; Flints. 
 
 
 1-48 
 
 16-16 
 
 1 
 
 05 
 
 17-90 
 
 18-73 
 
 12 
 
 50 
 
 12-801 Glass. 
 
 1 
 
THE STRENGTH OF CEMENT. 
 
 141 
 
 D Series.— CONCRETE BLOCKS— continued. 
 
 Portland Cement Oonceete Blocks of various Materials, set and kept in 
 Air for One Year, also set and Jcept in Water for the same time. 
 
 Table X. 
 
 Materials — Variou s. 
 
 Size of Block— 6" X 6" x 6". Not Compressed. 
 
 Propor- 
 tion. 
 
 Weight in lbs. 
 
 Weight of each 
 Block in lbs. 
 
 Crushed at Tons. 
 
 Kemarlis. 
 
 Cement. 
 
 Sand. 
 
 Water. 
 
 Kept in 
 Air. 
 
 Kept in 
 Water. 
 
 Air. 
 
 Water. 
 
 6 to 1 
 
 2-00 
 
 13-49 
 
 -88 
 
 17-35 
 
 18-30 
 
 18-20 
 
 17-00 
 
 Ballast. 
 
 2-23 
 
 11-91 
 
 1-35 
 
 15-70 
 
 17-12 
 
 30-00 
 
 23-0 
 
 Portland stone. 
 
 
 1-98 
 
 12-55 
 
 1-12 
 
 17-40 
 
 18-30 
 
 24-50 
 
 15-50 
 
 Granite. 
 
 
 1-91 
 
 11-78 
 
 1-54 
 
 15-85 
 
 17-00 
 
 24-60 
 
 24-00 
 
 Pottery. 
 
 
 1-95 
 
 11-36 
 
 1-23 
 
 14-80 
 
 15-77 
 
 20-00 
 
 19-20 
 
 Slag. 
 
 
 1-76 
 
 12-11 
 
 1-26 
 
 15-20 
 
 16-60 
 
 15-50 
 
 15-50 
 
 Flints. 
 
 
 2-04 
 
 13-35 
 
 1-11 
 
 17-76 
 
 18-40 
 
 16-50 
 
 17-00 
 
 Glass. 
 
 Table XI. 
 
 Materials — Various. 
 
 Size of Block— 6" X 6" x 6". Not Compressed. 
 
 8 to 1 
 
 1-60 
 
 14-51 
 
 •85 
 
 17-38 
 
 17-95 
 
 12-50 
 
 11-00 
 
 Eallast. 
 
 
 1-70 
 
 12-15 
 
 1-51 
 
 15-63 
 
 17-00 
 
 24-50 
 
 19-50 
 
 Portland stone. 
 
 
 1-31 
 
 12-53 
 
 1-07 
 
 17-45 
 
 18-20 
 
 14-50 
 
 13-40 
 
 Granite. 
 
 
 1-43 
 
 11-83 
 
 1-40 
 
 15-71 
 
 16-70 
 
 18-00 
 
 18-00, Pottery. 
 
 
 1-47 
 
 11-37 
 
 1-37 
 
 13-73 
 
 15-12 
 
 14-00 
 
 9-50 
 
 Slag. 
 
 
 1-34 
 
 12-02 
 
 1-12 
 
 15-40 
 
 16-60 
 
 14-00 
 
 12-50 
 
 Flints. 
 
 
 1-52 
 
 13-22 
 
 -96 
 
 17-30 
 
 17-80 
 
 13-60 
 
 11-40 
 
 Glass. 
 
 Table XII. 
 
 Materials — Various. 
 
 Size of Block— 6" x 6" x 6". Not Compressed, 
 
 10 tol 
 
 1 
 
 26 
 
 14-35 
 
 
 75 
 
 17-20 
 
 17-50 
 
 8-00 
 
 7-00 
 
 Ballast. 
 
 1 
 
 38 
 
 12-34 
 
 1 
 
 69 
 
 16-15 
 
 17-00 
 
 19-00 
 
 10-00 
 
 Portland stone. 
 
 
 1 
 
 06 
 
 12-62 
 
 
 99 
 
 16-97 
 
 17-63 
 
 11-50, 
 
 11-00 
 
 Granite. 
 
 
 1 
 
 15 
 
 11-88 
 
 1 
 
 25 
 
 15-66 
 
 16-50 
 
 14-00 
 
 17-00 
 
 Pottery. 
 
 
 1 
 
 17 
 
 11-43 
 
 1 
 
 28 
 
 13-75 
 
 15-00 
 
 8-50 
 
 5-50 
 
 Slag. 
 
 
 1 
 
 13 
 
 12-00 
 
 
 90 
 
 15-12 
 
 16-60 
 
 12-80, 
 
 11-00 
 
 Flints. 
 
 
 1 
 
 22 
 
 13-31 
 
 
 86 
 
 16-95 
 
 17-70 
 
 10-00 
 
 10-80 
 
 Glass. 
 
142 
 
 THE STRENGTH OF CEMENT. 
 
 D Series.— CONCRETE BLOGKS—continued. 
 
 Portland Cement Concrete Blocks of various Materials, set and kept in 
 Air for One Year, also set and kept in Wafer for the same time. 
 
 Table XIII. 
 Materials —Various. 
 Size of Block— 6" x 6" x 6". 
 
 
 Weight of 
 
 Weight of 
 
 Weight of 
 
 Weig 
 
 ht of 
 
 Crushed at 
 
 
 
 Cement. 
 
 Sand, &c. 
 
 Water. 
 
 each Block, 
 
 Tons. 
 
 
 
 lbs. 
 
 lb 
 
 s. 
 
 lbs. 
 
 lb 
 
 s. 
 
 
 
 
 Propor- 
 
 
 
 
 ■a 
 
 •d 
 
 
 ■a 
 
 ■d 
 
 •d 
 
 d 
 
 Bemarks. 
 
 tion. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 Not 
 
 a. 
 
 Not 
 pres 
 
 u 
 Ck 
 
 Not 
 pres 
 
 1 
 
 Not 
 pres 
 
 u 
 P. 
 
 Not 
 pres 
 
 
 
 a 
 
 a 
 
 a 
 
 a 
 
 B 
 
 o 
 
 i 
 
 a 
 
 i 
 
 a 
 
 a 
 
 o 
 
 
 
 o 
 
 a 
 
 o 
 
 6 
 
 o 
 Q 
 
 O 
 
 a 
 
 6 
 
 o 
 
 o 
 O 
 
 a 
 
 
 
 
 
 
 
 
 
 
 
 
 
 Kept in Air. 
 
 6 to 1 
 
 2-26 
 
 2-00 
 
 15-31 
 
 13-49 
 
 1-00 
 
 •88 
 
 17-90 
 
 17-35 
 
 20-40 
 
 18-20 
 
 Ballast. 
 
 
 2-402-23 
 
 12-80 11-91 
 
 1-45 
 
 1-35 
 
 16-90 
 
 15-70 
 
 40-60 
 
 30-00 
 
 Portland stone. 
 
 
 2-311-98 
 
 14-56 12-55 
 
 1-30 
 
 1-12 
 
 18-53 
 
 17-40 
 
 30-50 
 
 24-50 
 
 Granite. 
 
 
 2-16,l-91 
 
 13 -33111 -78 
 
 1-75 
 
 1-54 
 
 16-10 
 
 15-85 28-80 24-60 
 
 Pottery. 
 Slag. 
 
 
 2-llil-95 
 
 12-29'll-36 
 
 1-60 
 
 1-23 
 
 15-08 
 
 14 -80 23 -00 20 -00 
 
 
 2-031-76 
 
 13-9112-11 
 
 1-45 
 
 1-26 
 
 16-50 
 
 15-2020-5015-50 
 
 Flints. 
 
 
 2 -37 2 -04 
 
 15-51 13-35 
 
 1-30 
 
 111 
 
 18-50 
 
 17 -76 28 -00 16 -50 
 
 Glass. 
 
 Table XIV. 
 Materials — Various. 
 Size of Block— 6" X 6" X 6'. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 Kept in Water. 
 
 6 to 1 
 
 2-26 
 
 2 
 
 00 
 
 15 
 
 31 
 
 13-491 
 
 00 
 
 
 88 
 
 18 
 
 60 
 
 18-30 
 
 19 
 
 6017 
 
 00 
 
 Ballast. 
 
 2 -.40 
 
 2 
 
 23 
 
 13 
 
 80 
 
 11-911 
 
 45 
 
 1 
 
 35 
 
 17 
 
 67 
 
 17-12 
 
 34 
 
 5023 
 
 00 ; 
 
 Portland stone. 
 
 
 2-31 
 
 1 
 
 98 
 
 14 
 
 56 
 
 12-5!51 
 
 30 
 
 1 
 
 12 
 
 18 
 
 88 
 
 18-30 
 
 27 
 
 0015 
 
 15! 
 
 Granite. 
 
 
 2-16 
 
 1 
 
 91 
 
 13 
 
 33 
 
 11-7 81 
 
 75 
 
 1 
 
 54 
 
 17 
 
 50 
 
 17-00 
 
 26 
 
 50 24 
 
 00 
 
 Pottery. 
 
 
 2-11 
 
 1 
 
 95 
 
 12 
 
 29 
 
 11-3:61 
 
 60 
 
 1 
 
 23 
 
 16 
 
 61 
 
 15-77 
 
 23 
 
 5019 
 
 
 Slag. 
 
 
 2-03 
 
 1 
 
 76 
 
 13 
 
 91 
 
 12-1111 
 
 45 
 
 1 
 
 26 
 
 17 
 
 65 
 
 16-60 
 
 24 
 
 00^15 
 
 lol 
 
 Flints. 
 
 
 2-372 
 
 04 
 
 15 
 
 51 
 
 13-3 51 
 
 30 
 
 1 
 
 11 
 
 19 
 
 25 
 
 18-40 
 
 23 
 
 0017 
 
 00, 
 
 Glass. 
 
 Table XV. 
 Materials — Various. 
 Size of Block— 6" X 6" X 6". 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 Kept in Air. 
 
 8 to 1 
 
 1 
 
 76 
 
 1 
 
 60 
 
 15 
 
 88 
 
 14-51 
 
 
 95 
 
 
 85 
 
 17 
 
 86 
 
 17-3813-5012 
 
 50 
 
 Ballast. 
 
 
 1 
 
 86 
 
 1 
 
 70 
 
 13 
 
 26 
 
 12-15 
 
 1 
 
 65 
 
 1 
 
 51 
 
 16 
 
 32 
 
 15-63 33-00 24 
 
 50 
 
 Portland stone. 
 
 
 1 
 
 53 
 
 1 
 
 31 
 
 14 
 
 57 
 
 12-53 
 
 1 
 
 25 
 
 1 
 
 07 
 
 18 
 
 10 
 
 17-4519-60 14 
 
 50 
 
 Granite. 
 
 
 1 
 
 64 
 
 1 
 
 43 
 
 13 
 
 53 
 
 11-83 
 
 1 
 
 60 
 
 1 
 
 40 
 
 16 
 
 15 
 
 15-7122-0018 
 
 00 
 
 Pottery. 
 
 
 1 
 
 60 
 
 1 
 
 47 
 
 12 
 
 37 
 
 11-37 
 
 1 
 
 50 
 
 1 
 
 37 
 
 14 
 
 20 
 
 13-73 19-5014 
 
 00 
 
 Slag. 
 
 
 1 
 
 56 
 
 1 
 
 34 
 
 14 
 
 28 
 
 12-02 
 
 1 
 
 30 
 
 1 
 
 12 
 
 16 
 
 45 
 
 15-40 17-5014 
 
 00 
 
 Flints. 
 
 
 1 
 
 82 
 
 1 
 
 52 
 
 15 
 
 79 
 
 13-22 
 
 1 
 
 15 
 
 
 96 
 
 18 
 
 00 
 
 17-30'l8-00jl3 
 
 60 
 
 Glass. 
 
THE 8TKENGTH OF CEMENT. 143 
 
 D Series.— CONCRETE BLOCKS— continued. — 
 
 Portland Cement Concrete Blocks of various Materials, set and kept in 
 Air for One Year, also set and kept in Water for the same time. 
 
 Table XVI. 
 Materials — Various. 
 Sizeof Block-6"x6"x6", 
 
 Propor- 
 tion. 
 
 Weight of 
 Cement, 
 lbs. 
 
 Weight of 
 Sand, &c. 
 lbs. 
 
 Weight of 
 Water, 
 lbs. 
 
 Weight of 
 each Bloclj. 
 lbs. 
 
 Crushed at 
 Tons. 
 
 Remarks. 
 
 Compressed. 
 
 Not 
 Compressed. 
 
 Compressed. 
 
 Not 
 Compressed. 
 
 Compressed. 
 
 Not 
 Compressed. 
 
 Compressed. 
 
 Not 
 Compressed. 
 
 ■d 
 
 m 
 
 •V 
 
 a 
 
 o 
 
 Not 
 Compressed. 
 
 
 
 
 
 
 
 
 
 
 
 
 Kept in Water. 
 
 8 to 1 
 
 1-76 
 
 1-60 
 
 15-88 
 
 14-51 
 
 •95 
 
 -85 
 
 18-90 
 
 17-95 
 
 13-50 
 
 11-00 
 
 Ballast. 
 
 
 1-86 
 
 1-70 
 
 13-26 
 
 12-15 
 
 1-651-5117-50 
 
 17-00 
 
 24-50 
 
 19-50 
 
 Portland stone. 
 
 
 1-53 
 
 1-81 
 
 14-57 
 
 12-53 
 
 1-25:1-0719-00 
 
 18-20 
 
 16-00 
 
 13-40 
 
 Granite. 
 
 
 1-64 
 
 1-43 
 
 13-53 
 
 11-83 
 
 1-601-4016-95 
 
 16-70 
 
 23-00 
 
 18-00 
 
 Pottery. 
 
 
 1-63 
 
 1-47 
 
 12-37 
 
 11-37 
 
 1-50 
 
 1-3715-91 
 
 15-12 
 
 13-40 
 
 9-50 
 
 Slag. 
 
 
 1-56 
 
 1-34 
 
 14-28 
 
 12-02 
 
 1-30 
 
 1-1217-62 
 
 16-60 
 
 20-00 
 
 12-50 
 
 Flints. 
 
 
 1-82 
 
 1-52 
 
 15-79 
 
 13-22 
 
 1-15 
 
 •96 18-93 
 
 1 
 
 17-80 
 
 17-50 
 
 11-00 
 
 Glass. 
 
 Table XVII. 
 Materials' — Various. 
 Size of Block— 6" x 9" x 6". 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 Kept in Air. 
 
 10 to 1 
 
 1 
 
 42 
 
 1 
 
 26 
 
 16 
 
 11 
 
 14-35 
 
 
 85 
 
 -7517 
 
 68 
 
 17-20 
 
 10 
 
 50 
 
 8 
 
 00 
 
 Ballast. 
 
 
 1 
 
 52 
 
 1 
 
 38 
 
 13 
 
 56 
 
 12-34 
 
 1 
 
 86 
 
 1-6916 
 
 44 
 
 16-15 
 
 22 
 
 00 
 
 19 
 
 00 
 
 Portland stone. 
 
 
 1 
 
 23 
 
 1 
 
 06 
 
 14 
 
 60 
 
 12-62 
 
 1 
 
 15 
 
 •99J7 
 
 40 
 
 16-97 
 
 15 
 
 50 
 
 11 
 
 50 
 
 Granite. 
 
 
 1 
 
 3411 
 
 15 
 
 13 
 
 75 
 
 11-88 
 
 1 
 
 45 
 
 1-25:16 
 
 09 
 
 15-66 
 
 18 
 
 50 
 
 14 
 
 00 
 
 Pottery. 
 
 
 1 
 
 281 
 
 17 
 
 12 
 
 46 
 
 11-43 
 
 
 40 
 
 1-2814 
 
 00 
 
 13-75 
 
 10 
 
 50 
 
 8 
 
 50 
 
 Slag. 
 
 
 1 
 
 261 
 
 13 
 
 14 
 
 37 
 
 12-00 
 
 1 
 
 15 
 
 -9016 
 
 15 
 
 15-12 
 
 15 
 
 00 
 
 12 
 
 80 
 
 Flints. 
 
 
 1 
 
 48'l 
 
 1 
 
 22 
 
 16 
 
 16 
 
 13-31 
 
 1 
 
 05 
 
 -8617 
 
 90 
 
 16-95 
 
 12 
 
 50 
 
 10 
 
 00 
 
 Glass. 
 
 Table XVIII. 
 Materials — Various. 
 Size of Block— 6" x 6" x 6". 
 
 
 
 42I1 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 Kept in Water. 
 
 10 to 1 
 
 1 
 
 
 26 
 
 16-11 
 
 14 
 
 35 
 
 
 85 
 
 
 75 
 
 18 
 
 70 
 
 17-50 
 
 10-50 
 
 7-00 
 
 Ballast. 
 
 
 1 
 
 52:1-3813-56 
 
 12 
 
 34 
 
 1 
 
 86 
 
 1 
 
 ■69 
 
 17 
 
 90 
 
 17-00 
 
 16-5010-00 
 
 Portland stone. 
 
 
 1 
 
 23|1 
 
 0614-60 
 
 12 
 
 62 
 
 1 
 
 15 
 
 
 9918 
 
 50 
 
 17-63 
 
 12-40 
 
 11-00 
 
 Granite. 
 
 
 1 
 
 341 
 
 1513-75 
 
 11 
 
 88 
 
 1 
 
 45 
 
 1 
 
 2516 
 
 80 
 
 16-50 
 
 19-00 
 
 17-00 
 
 Pottery. 
 
 
 1 
 
 281 
 
 17 
 
 12-46 
 
 11 
 
 43 
 
 1 
 
 40 
 
 1 
 
 2815 
 
 50 
 
 15-00 
 
 10-00 
 
 5-50 
 
 Slag. 
 
 
 1 
 
 261 
 
 13 
 
 14-37 
 
 12-00 
 
 1 
 
 15 
 
 
 9017 
 
 60 
 
 16-60 
 
 18-50 
 
 11-00 
 
 Flints. 
 
 
 1 
 
 481 
 
 22 
 
 16-16 
 
 13 
 
 31 
 
 1 
 
 05 
 
 
 8618 
 
 73 
 
 17-70 
 
 12-80 
 
 10-80 
 
 Glass. 
 
144 
 
 THE STRENGTH OF CEMENT. 
 
 Table 5. 
 
 Concrete Sewers. 
 
 Locality. 
 
 Size 
 (internally). 
 
 Length 
 
 In 
 Feet. 
 
 Cost per 
 
 Foot 
 Lineal, ir- 
 respective 
 of Earth- 
 works and 
 Adjuncts. 
 
 Remarks. 
 
 Concrete 
 per C. 
 Yard. 
 
 Render- 
 ing per 
 
 Supl. 
 
 Yard. 
 
 Concrete 
 rendered 
 
 per C. 
 
 Yard. 
 
 Tooting . . . . 
 
 Bridge Road.Bat- \ 
 tersea. ... J 
 
 Camberwell Road . 
 
 Falcon Brook 
 
 Earl Sewer.Dept- > 
 ford Lower Rd. J 
 
 ft. in. ft. in. 
 
 3 9X2 6 
 
 4 0X2 8 
 
 4 0X2 8 
 4 3X2 10 
 
 1 1X1 1 
 
 115 
 
 644 
 
 2355 
 2030 
 
 1023 
 
 s. d. 
 11 4 1 
 
 13 5 
 
 10 0 
 
 14 10 
 
 16 0 1 
 
 P. C. Concrete C to 
 1, and rendered 
 with P.C. Cement 
 1 to 1. 
 
 Ditto. 
 
 Ditto, but 7 to 1. 
 Ditto, 6 to 1. 
 Only lower half ren- 
 dered as above. 
 
 
 
 
 CONCiEETB AND HALF-BRICK SeWERS. 
 
 
 
 
 
 Half-brick in Ce- 
 
 
 
 
 Blackfriars Road.. 
 
 4 6X3 0 
 
 3486 
 
 11 9 1 
 
 ment, and P. C. 
 
 
 
 
 
 
 
 Concrete 7 to 1 . 
 
 
 
 
 NewingtonCause- X 
 
 4 6X3 0 
 
 1953 
 
 12 2i 
 
 Ditto. 
 
 
 
 
 
 
 
 
 
 
 Table 6. 
 Sewer at Dulwich. 
 
 Register of Experiments made with Portland Cement, Form of Mould, 
 No. 2, Table 1. Sectional Area, 2*25 Square Inches. Manufactured by 
 Messrs. Foemby. October 17, 1868— January 28, 1869. 
 
 
 
 
 
 Averages of 5 Tests each. 
 
 Proportionate 
 Strength of 
 the 1 to 1 
 to Neat. 
 
 Weight 
 
 per 
 Bushel. 
 
 When 
 Moulded. 
 
 When 
 Tested. 
 
 Days in 
 Mould. 
 
 Broke at lbs. 
 
 Broke at lbs. 
 
 
 
 
 Neat. 
 
 1 to 1. 
 
 lbs. 
 118 
 
 Oct. 17 
 
 Oct. 24 
 
 7 
 
 805-2 
 
 275-8 
 
 34-25 
 
 » > 
 
 
 Oct. 31 
 
 14 
 
 924-4 
 
 316-0 
 
 34-18 
 
 
 Oct. 19 
 
 Nov. 9 
 
 21 
 
 982-6 
 
 388-2 
 
 39-50 
 
 
 
 Nov. 19 
 
 Months. 
 1 
 
 995-4 
 
 384-4 
 
 38-61 
 
 
 Oct. 28 
 
 Dec. 28 
 
 2 
 
 1237-0 
 
 479-0 
 
 38-71 
 
 5 5 
 
 
 Jan. 28 
 
 3 
 
 1239-0 
 
 538-6 
 
 43-47 - 
 
THE STRENGTH OF CEMENT. 
 
 145 
 
 Table 7. 
 Contracts on the South Side. 
 Particulars of Portland Cement supplied during the last five years, with 
 
 average breaking weight at seven days. 
 Sectional Area, 2 ' 25 Square Inches. 
 
 Form of Mould, No. 2, Table 1. 
 
 Names of Manufactureks 
 AND Agents. 
 
 Formby 
 
 Booth 
 
 Lee and Co 
 
 Burham Brick and Oement| 
 
 Company / 
 
 Casson and Co., Agents . . 
 Knight, Bevan, and Sturge .. 
 Kobins and Co. (Limited) . . 
 
 White and Co. 
 
 Burge and Co., Agents . . 
 
 Hilton 
 
 Beaumont, Agent 
 
 Layers, Agent 
 
 Weston 
 
 Young and Son, Agents 
 Coles and Shadbolt 
 
 Tingey 
 
 Harwood and Hatcher, Agents 
 
 Generally 
 
 Quantity 
 in 
 
 Busliels. 
 
 Average 
 Weight per 
 ijusnei. 
 
 Number, 
 of 
 Tests. 
 
 Average 
 Breaking 
 Weight. 
 
 
 lbs. 
 
 
 lbs. 
 
 31,581 
 
 1 1 Q ' 
 
 lio 
 
 
 862 
 
 01 
 
 12,464 
 
 119-75 
 
 80 
 
 846 
 
 50 
 
 
 
 10 
 
 839 
 
 00 
 
 320,716 
 
 113-54 
 
 3,705 
 
 825 
 
 73 
 
 5,200 
 
 114-50 
 
 58 
 
 816 
 
 80 
 
 19,429 
 
 114-52 
 
 820 
 
 803 
 
 38 
 
 68,880 
 
 118-00 
 
 620 
 
 795 
 
 31 
 
 60 
 
 119-00 
 
 10 
 
 791 
 
 70 
 
 4,500 
 
 113-00 
 
 30 
 
 789 
 
 30 
 
 103,453 
 
 117-17 
 
 1,300 
 
 786 
 
 99 
 
 40 
 
 116-00 
 
 10 
 
 765 
 
 00 
 
 12,002 
 
 116-17 
 
 160 
 
 706 
 
 97 
 
 600 
 
 120-00 
 
 10 
 
 666 
 
 40 
 
 200 
 
 117-00 
 
 10 
 
 655 
 
 80 
 
 240 
 
 107-00 
 
 10 
 
 580 
 
 00 
 
 6,300 
 
 115-50 
 
 100 
 
 564 
 
 27- 
 
 3,040 
 
 117-78 
 
 30 
 
 408 
 
 03 
 
 589,217 
 
 115-23 
 
 7,505 
 
 806 
 
 -63 
 
 Table 8. 
 
 Specified Standard of Portland Cement supplied by Manufacturers. 
 
 
 Breaking 
 
 Weights. 
 
 
 At per 
 
 On 2i 
 
 
 Square Inch. 
 
 Square Inches. 
 
 
 lbs. 
 
 lbs. 
 
 Greenwich and Deptford sewers 
 
 2-22-2 
 
 500 
 
 
 250 
 
 562-5 
 
 
 >' 
 
 » 
 
 The Earl, Battle Bridge, &c 
 
 
 
 
 
 
 
 )> 
 
 )i 
 
 Southern Thames Embankment . . . . 
 
 350 
 
 787-5 
 
 
 
 » 
 
 » 
 
 
 )' 
 
 )) 
 
 
 
 )> 
 
 
 1' 
 
 >> 
 
 
 )) 
 
 5) 
 
 
 
 )) 
 
 
 )) 
 
 )» 
 
 L 
 
146 
 
 THE STRENGTH OP CEMENT. 
 
 Table 9. 
 
 Sixty Experiments on Conorete Briquettes subjected to a tensile strain. 
 Cement weighing 112 lbs. per Bushel. Form of Mould, No. 2, Table 1. 
 Sectional Area, 2*25 Square Inches. Average of Two in each case. 
 
 ] Month. 
 
 6 Weeks. 
 
 lbs. 
 
 306-0 
 
 403-5 
 
 Broke wind- 
 ing up. 
 
 133-5 
 
 159-0 
 
 103-0 
 
 lbs. 
 383-0 
 397-5 
 
 246-0 
 
 189-5 
 186-0 
 143-0 
 
 2 Months. 6 Months. 
 
 12 Months. 
 
 lbs. 
 
 lbs. 
 
 lbs. 
 
 
 407-5 
 
 505-5 
 
 541-0 
 
 3 to 1 
 
 411-0 
 
 479-0 
 
 554-5 
 
 4 „ 1 
 
 269-5 
 
 439-0 
 
 482-0 
 
 5 „ 2 
 
 221-0 
 
 273-0 
 
 319-0 
 
 6 „ 1 
 
 215-0 
 
 280-5 
 
 368-0 
 
 7 „ 1 
 
 140-5 
 
 282-5 
 
 352-5 
 
 8 „ 1 
 
 ExTBACTS from Specification for Sewers made of Portland Cement Concrete, 
 and Concrete lined with Brickwork. 
 
 " 7. 1953 feet run of egg-shaped sewer, 4 feet 6 inches in height and 3 feet 
 in width in the clear, half brick in thickness in Portland cement, to be sur- 
 rounded with Portland cement concrete, with a 9-inch stoneware pipe under 
 invert of sewer, as shown on Drawing No. 6 (Plate 15, Fig. 7), commencing 
 by an existing bell-mouth at Stone's End, from thence along Newington 
 Causeway to an existing eye opposite London Eoad. (See Clause 34.) 
 
 " 8. 3486 feet run of egg-shaped sewer, 4 feet 6 inches in height by 3 feet 
 in width in the clear, half brick in thickness, to be surrounded with Portland 
 cement concrete, and a 9-inch stoneware pipe under invert of sewer, as shown 
 on Drawing No, 7, commencing at an existing bell-mouth in Saint George's 
 Circus, thence along Blackfriars Eoad, to near Blackfriars Brido-e flee 
 Clause 34.) " ° ' ^ 
 
 " 9. 2355 feet run of egg-shaped sewer, 4 feet in height and 2 feet 8 inches 
 in width in the clear, to be in Portland cement concrete, with a 9-inch stone- 
 ware pipe under invert of sewer, as shown on Drawing No. 8 (Plate 15, Fig. 9), 
 commencing near Wyndham Eoad, from thence along Camberwell Eoad and 
 High Street to Cold Harbour Lane, there to be connected with the existinc^ 
 sewer by a vertical shaft. ° 
 " 10. 1023 feet run of barrel sewer, 7 feet 1 inch inside diameter, to be in 
 Portland cement concrete, and constructed, as shown on Drawing No. 9 
 (Plate 15, Fig. 10), along the line of Open Earl Sewer between Grand Surrey 
 Canal and Deptford Lower Eoad. The ballast for the concrete sewers is to be 
 clean, fine, sharp Thames ballast, or other of equal quality, to be free from 
 clay or other earthy substances, and mixed and used in every respect as the 
 Engineer may direct. (See Clause 33.) " 
 
THE STRENGTH OF CEMENT. 
 
 147 
 
 Concrete Sewees. 
 
 «« 33. The sewers in Camberwell Eoad and the Earl, shown on Drawings 8 
 and 9 (Plate 15, Figs. 9 and 10), are to be entirely constructed of Portland 
 cement concrete, made in the proportion of three bushels of cement to one 
 cubic yard of sand and ballast. The same kind of concrete is to be used for 
 the entire cross section, including that which surrounds the pipe under invert. 
 In making this concrete a box 3 feet by 3 feet by 3 feet is to be used for 
 the ballast, and another box capable of holding three ' striked ' bushels for the 
 cement. The cement and ballast are to be turned over at least three times, 
 and thoroughly mixed together. 
 
 " 33a. The centering used for the arches is to be covered with thin sheet 
 iron, copper, or zinc, and, if necessary, greased to ensure a smooth face for the 
 arch. The invert below the springing line is to be rendered with Portland 
 cement and sand, in equal pro^rtions, and finished off half an inch thick with 
 a smooth trowelled face. This work is to be done by a plasterer, ihe 
 concrete for the arches is to be of sand and cement next the face, and wherever 
 the face is rough it is to be touched up by a plasterer, after the centres are 
 drawn ; and left in a neat and workmanlike' state. The concrete side entrances 
 are to be formed of cement and ballast of the same proportions and quality as 
 that for the concrete sewers, and are to be entirely rendered with cement half 
 an inch thick and finished like the sewers." 
 
 Half-beick Sewees. 
 " 34. The sewers in Newington Causeway and Blackfriars Eoad, Drawings 
 6 and *7 (Plate 15, Fig. 7), are to be of half brick in thickness, and to be 
 surrounded by Portland cement concrete of the same proportion, and in every 
 respect like that described in the Clause, No. 33. Below the springing line, 
 that part of the sewer which is of concrete is to be formed first, and is to be 
 allowed to set hard before the brickwork is commenced. The brickwork is to 
 be entirely of the best picked and assorted No. 1 bricks, and to have a collar 
 joint between it and the concrete of half an inch of cement." 
 
 Cement. 
 
 " 37. The whole of the cement shall be Portland cement of the very best 
 quality, ground extremely fine, weighing not less than 112 lbs. to the striked 
 bushel,'and capable of maintaining a breaking weight of 350 lbs. per square 
 inch seven days after being made in a mould, and immersed in water during 
 the interval of seven days. The Contractor shall at all times keep in store 
 upon the works a supply of cement equal to at least fourteen days' require- 
 ments ; and with each delivery of cement shall send to the Clerk of Works a 
 memorandum of the number of bushels sent in, and the name of the manu- 
 facturer. 
 
 " 38. The cement as hereinbefore described shall, except where otherwise 
 specified, be mixed in the proportion of one of Portland cement to one of sand. 
 No cement to be used which has become hard or set." 
 
 J Concrete Sewee with Beick LiNiNa. 
 
 « The concrete for the 9 feet 6 inches by 9 feet 6 inches sewer, shown on 
 
 L 2 
 
148 
 
 THE STBENGTH OP CEMENT. 
 
 Drawings Nos. 1 and 3 (Plate 15, Fig. 11), is to be Portland cement concrete, 
 with a lining of brickwork 4^ inches thick in Portland cement, the concrete to 
 be made in the proportion of three bushels of cement to one cubic yard of sand 
 and ballast. In making this concrete a box 3 feet by 3 feet by 3 feet is to 
 be used for the ballast, and another box capable of holding three striked 
 bushels for the cement. The cement and ballast are to be turned over at 
 least three times and thoroughly mixed together. Below the springing line 
 that part of the sewer which is of concrete is to be formed first, and is to be 
 allowed to set hard before the brickwork is commenced ; the brickwork is to 
 be entirely of the best picked and assorted No. 1 bricks, and to have a collar 
 joint of cement half an inch in thickness between it and the concrete." 
 
 Concrete. 
 
 "40. Excepting for the 9 feet 6 inches by 9 feet 6 inches sewer, the concrete 
 to be used throughout the works shall be Portland cement concrete, composed 
 of clean Thames ballast or approved pit ballast, in the proportion of eight 
 parts by measure of ballast to one part by measure of Portland cement." 
 
THE STRENGTH OF CEMENT. 
 
 149 
 
 Mr. J. Grant said, at this stage he would simply point out 
 the form of moulds used in the experiments. No. 1, Table 1, 
 was the first form, and was used previous to 1865. It would 
 be perceived that the angles were very sharp, which was the 
 cause of irregular fractures. After some experience the original 
 form of mould was modified, as shown in No. 2, Table 1, in 
 which the angles were rounded off, and which had been in use 
 for several years. This was the form which had been used 
 throughout the experiments described in this Paper, except 
 where otherwise mentioned. At the same time other experi- 
 ments, given in Table 1 of the Paper, were made with a variety 
 of other moulds differing in length, shape, and sectional area. 
 Some, instead of being broken between clips, as shown in Plate 
 2 of his former Paper, were broken by means of knife edges 
 inserted in holes, as shown in Plate 4, attached to that Paper. 
 Further experiments were made with the fiddle-shaped mould. 
 No. 10, Table 1, which did not break uniformly at the neck ; 
 the slightest distortion making it break in a diagonal line. 
 Some other experiments were detailed in the Paper ; but these 
 were sufScient to explain their general character. 
 
 Mr. H. E. TowLB said in 1856 he was employed to take 
 charge of works, where there had been a large quantity of the 
 American Eosendale cement in store for a long time; and it 
 became a question whether it should be used or rejected. It 
 was determined that experiments should be made to ascertain 
 the character of the cement, and some curious results were 
 developed. This cement, in the United States, corresponded to 
 the Portland cement of England. He tried the cement with 
 various proportions of sand and lime paste, making up eight 
 batches altogether. In making these experiments he desired 
 to ascertain>hat effect working and re-working the mortar had 
 upon its strength. He tried the mortar re-mixed daily for 
 twenty days, and daily stuck bricks together transversely, and 
 after five months pulled them apart, measuring the strain 
 as carefully as possible. In these experiments he found it 
 advisable to make a distinction between cohesion and adhesion. 
 Cohesion was the quality which made the particles of a sub- 
 stance stick together between themselves ; adhesion was the 
 force which united the material to something else. Now, if 
 bricks or stones were stuck together with mortar which did not 
 
150 
 
 THE STRENGTH OF CEMENT. 
 
 adhere to the brick as strongly as it did to itself, all expense in 
 making the component parts of that mortar more cohesive was 
 wasted ; and therefore there was a limit to the expense to be 
 incurred for this purpose. Eeverting to the re-mixing of the 
 mortar, he found that the maximum strength was obtained after 
 ten times mixing and re-mixing. He certainly did not advocate 
 mixing and re-mixing twenty or any other number of times ; 
 nevertheless this fact about this particular kind of hydraulic 
 mortar might serve as a suggestion to others endeavouring to 
 render the subject less obscure. Newark Eosendale cement was 
 sold in barrels of a capacity of 4 cubic feet, and each barrel con- 
 tained on an average 300 lbs. of cement. The weight of the 
 barrels when empty averaged 25 lbs. each. A weight of 300 lbs. 
 of Rosendale cement required 1^^% cubic foot of water to reduce 
 it to a stiff paste, and produced 3x^^ cubic feet of pure cement 
 mortar in a state of stiff paste, weighing 117 lbs. per cubic foot. 
 The volume of 800 lbs. of cement unpressed was 4| cubic feet ; 
 and as sold in the barrels 4 cubic feet. 
 
 1 Barrel Rosendale cement 4 cubic feet. 
 
 1 Box lime paste, 2 feet by 2 feet by f foot 3 „ 
 5 Boxes sand, damp and loose 15 . „ 
 
 Total 22 
 
 produced a batch of 17 cubic feet of good mortar, weighing 
 124 lbs. per cubic foot : 
 
 Lime paste weighed, per cubic foot . . 84 lbs. 
 Cement „ „ . . 117 ,^ 
 
 A block of unslaked lime 1 cubic foot in volume weighed 
 91tV^ lbs., and when slaked by the addition of water, and 
 reduced to a thick paste, the volume increased to 3 • 047 cubic 
 feet. A bushel of this lime, as purchased coarse and fine 
 together, weighed 75 lbs., and when reduced to a state of stiff 
 paste increased in volume to 2tV¥^ bushels. 
 
 Lieut-Colonel Scott, E.E., remarked that Mr. Grant had 
 brought up the strength of Portland cement to a pitch which a 
 few years ago was thought impossible; but he was not quite 
 certain that in carrying it so far danger might not be incurred 
 which at first sight might hardly be suspected. Persons who 
 
THE STRENGTH OF CEMENT. 
 
 151 
 
 were in the habit of using large quantities of Portland cement 
 were aware that at times it expanded to an extraordinary degree. 
 This was due generally to too large a quantity of chalk having 
 been used in its preparation. A few years ago, on examining 
 some cases where great strength was aimed at by the manufac- 
 turer, he found that where the clay was reduced to 18 or 19 per 
 cent, instead of 22 or 23 per cent, very extraordinary expansion 
 occurred. By the exposure of such cement to the air, the 
 tendency to expand might be, no doubt, greatly modified, but by 
 demanding cement of extreme strength Engineers undoubtedly 
 ran into this danger. With a large proportion of clay there 
 was greater safety, though somewhat less strength. A remark 
 had been made that it was of no use getting the cohesive 
 strength of the cement greater than the adhesion of the cement 
 to the materials that were to be joined together by it. If that 
 were right, and in the use of Portland cement the strength of 
 the bricks in ordinary use was exceeded, he thought Engineers 
 might be content to go no farther and avoid the danger he had 
 pointed out. As to the instance cited of cement mortar when 
 beaten up afresh, though first losing strength, afterwards 
 becoming stronger again, he thought it might be explained by 
 assuming that the cement might have contained some particles 
 which had an expansive tendency. In using hydraulic lime- 
 mortar the lime was slaked, and thus was obtained a hydrate of 
 lime mixed with sand, and in the work a solidification occurred, 
 partly from the action of the atmosphere and partly from the 
 slaked lime entering into fresh combination with the silex, 
 thus forming slowly a hydrated silicate without expansion ; but 
 if particles of unslaked lime were mingled with this, inequality 
 of action resulted, inasmuch as the particles of unslaked and 
 slaked lime were in a different condition. In using lias lime, 
 for instance, unless it was ground to a fine powder and the 
 slaking allowed to go on some time before use, the work was apt 
 to get distorted, because those particles which were uncombmed 
 with water expanded in the work when hydration took place 
 and burst it. In the experiments alluded to he thought that 
 something of this kind had occurred. There was continued 
 expansion of some of the lime particles through slakmg, till the 
 material was brought wholly into the state of hydrated silicate 
 of lime, when it again gained in strength by the quiet and 
 
152 
 
 THE STRENGTH OP CEMENT. 
 
 gradual rearrangement of the particles, such as occurred with 
 hydraulic limes, without any disturbing element. 
 
 He now would say a few words on a subject which merited 
 attention from Engineers. There was a new mode of using lime 
 which had been adopted in the buildings at South Kensington. 
 If m the ordinary slaking of lime just sufficient water was added 
 to bring It to a dry impalpable powder, this powder would have 
 a bulk sometimes much greater than that of the original lime, 
 and if made into paste would, when it dried, exhibit a con- 
 siderable degree of porosity. It could be imagined that if the 
 hme, instead of being slaked, were ground to powder and 
 induced to set as cement, with its original density, much 
 greater strength would be attained in the solidified mortar. In 
 the use of lime the combination with water took place first, and 
 then subsequently the solidifying action went on. If it was 
 hydraulic lime a silicating process was set up after slaking, and 
 a fresh arrangement of particles took place. In the case of 
 cements the slaking and the setting went on simultaneously, 
 and the water entered at once into combination with the 
 cement to form a stone-like substance. If by any means lime 
 could be induced to combine with the water slowly, so as not to 
 burst with the heat, a much better result would follow than 
 from the ordinary way of using it. This, in fact, was what he 
 had accomplished by the mode in which he was now making 
 mortar, and his general method of procedure was as follows, the 
 Hime used at Kensington being ordinary grey lime finely 
 ground. First of all he mixed 5 per cent, of plaster of Paris, as 
 compared with the quantity of lime to be used, in a bucket of 
 water, making a milk of sulphate of lime. He then threw this 
 into the pan of a mortar-mill and added the ground lime 
 gradually,, and instead of the lime slaking as it would when 
 treated with water only, the lime showed no symptoms of 
 slaking, and was brought to a thin paste without any sensible 
 increase of temperature. When that was done he added sand, 
 and for most purposes as much as 6 parts of sand to 1 of lime! 
 In thin brickwork he obtained far greater strength with grey 
 hme treated in this way, with 6 parts of sand, than with 
 Portland cement with 4 parts of sand. He did not say the 
 same results would follow the use of grey lime in very damp 
 situations or under water; in such situations another set of 
 
THE STBENGTH OF CEMENT. 
 
 153 
 
 phenomena came into play ; but he spoke of cases where the 
 carbonic action of the atmosphere was chiefly depended on to 
 bring about the hardening of the mortar. The process he had 
 described would not give setting property under water if the 
 lime did not possess it before. It might indeed be thought 
 that he destroyed the water-setting property by the plaster 
 of Paris, which was itself soluble, but that was not the case. 
 The quantity of plaster of Paris did not exceed 0 • 75 per cent, 
 of the mortar ; and in three or four weeks crystallized out in 
 the pinhole cavities in it, where it showed itself in little 
 crystalline spangles or plates. In proportion as the percentage 
 of clay increased in the lime employed, so this became more 
 suitable for mortar to be used under water. Pozzolana was at 
 one time largely imported into this country. At that time it 
 was not known that there were large beds of a material in 
 England which made excellent pozzolana. He believed that 
 with his process the pozzolana of this country would come into 
 use. He had examined the shales of the lias beds, notably 
 those of Leicester, and he found by the use of this material 
 calcined, and a small quantity of common chalk lime, treated as 
 described with a milky solution of sulphate of lime, he got 
 under certain conditions, viz. by experiments with small blocks 
 and by putting a few bricks together, greater strength than he 
 could get out of Portland cement. He spoke of such instances 
 as those mentioned only. His experiments had so far extended 
 only to such cases. He had only to add that in using this new 
 method of mortar-making (which he termed the selenitic 
 method) for plastering the walls in the galleries of. the 
 Exhibition Building at South Kensington, he employed 6 parts 
 of sand to 1 part of lime, and for the finishing coat 1 part of 
 lime with 4 parts of sand. 
 
 Mr. Bramwell said that when, five years ago, Mr. Grant 
 brought before the Institution a Paper on this subject,^ and 
 pointed strongly towards the improvement that he thought 
 would be derived from increasing the weight of the cement, Mr. 
 Bramwell threw doubts upon the probability of such a result, 
 since, from experiments he had made, he believed, if the 
 weight of the cement were alone considered, it would hold out 
 
 ' Vide ' Minutes of Proceedings Inst. C.E.,' vol. xxv., p. 136 et seq. 
 
154 
 
 THE STRENGTH OF CEMENT. 
 
 a premium for bad grinding, and that badly-ground cement 
 meant inferior cement. He was glad to find tliis opinion cor- 
 roborated in the present Paper: for Mr. Grant now said that, 
 with cement of 113 lbs. per bushel when unsifted, he got a 
 strength of 375 lbs. per square inch, but when sifted the same 
 cement, weighing only 110^ lbs. per bushel, gave an increase 
 of strength reaching to as much as 427 lbs. He thought this 
 abundantly justified what he stated five years ago, that the 
 mere test of weight alone was a premium for bad grinding, 
 and calculated to mislead. He also, at the same time, gave 
 instances in which large variation of strength was occasioned 
 by an extremely small variation in the amount of water with 
 which the cement used in the sample was gauged. He was 
 glad now to hear Mr. Grant state that the proportions, both of 
 water and cement, were determined by weight in the mixing 
 of the samples tested. 
 
 Mr. Bazalgette remarked that he could not understand 
 how it was possible to manufacture cement of too good a 
 quality. The improved manufacture of Portland cement up to 
 the present time had been promoted by the careful experiments 
 of Mr. Grant. Portland cement concrete could now be used 
 with advantage and safety where brickwork and stonework were 
 formerly used, thus effecting a large economy in engineering 
 works. In the Southern Thames Embankment the cost was 
 reduced to nearly one-third of what it would have been had 
 the embankment continued to be constructed in brickwork 
 behind the granite facing. A further portion of embankment 
 was on the point of commencement on the north side of the 
 river, and this also it was intended to construct with granite 
 facing and concrete backing without any brickwork, which he 
 believed, owing to the good quality at which Portland cement 
 had now arrived, would be quite as strong, and probably would 
 form a more homogeneous mass than if constructed in brickwork. 
 The Paper had drawn attention to the fact that Eoraan cement 
 was two-thirds the price of Portland cement, but that its 
 strength was only one-third; therefore it was more advantageous 
 to use Portland than Eoman cement. He did not notice 
 whether the Author had made any comparison between Port- 
 land cement and lias lime mortar ; but as far as his experience 
 went, Portland cement was so superior to the ordinary limes 
 
THE STBENGTH OF CEMENT. 
 
 155 
 
 used for mortar in brickwork that the cement became the 
 cheaper material of the two. For instance, he had in his ex- 
 periments added in bulk the quantity of lime required to bring 
 it up to the same price as a less quantity of Portland cement ; 
 and he found, using it in that way in mortar, that Portland 
 . cement produced much stronger brickwork than was produced 
 by the use of the proportionately increased quantity of lime. 
 
 He did not clearly understand the distinction drawn in the 
 course of the discussion between adhesion and cohesion. As he 
 understood the argument, it was contended that, with harder 
 and better cement, its power of adhering to stone or bricks 
 would not increase in proportion to its increased power of 
 holding together its own particles in one mass. He was, how- 
 ever, of opinion that if this argument had reference to cement 
 uniting brickwork or stone, it would be found if the face of the 
 materials to be united were rough and absorbent, the cement 
 could penetrate the face of the brick or stone, combine with 
 and lay hold of it, and have the same affinity to the brick or 
 stone as to itself ; and that this power of combining the whole 
 mass together would under such conditions increase proportion- 
 ately with the increased strength of the cement, so that the 
 adhesion and the cohesion would increase at the same time and 
 in the same proportion. He thought therefore if the strength 
 of the cement was increased, and the building materials to be 
 united were suitable, both the adhesion and the cohesion would 
 also be increased, and the whole structure strengthened. The 
 Paper led to this practical result — that by attention to the 
 production of good Portland cement the cost of engineering 
 works might be reduced, particularly those of large bulk, to less 
 than half that which had been spent upon similar works before 
 its introduction. 
 
 Mr. W. Paekes said he had lately had the opportunity of 
 making some experiments with Portland cement, from which 
 he had drawn conclusions similar to those of Mr. Bramwell. 
 Everyone who had to do with Portland cement must feel 
 indebted to Mr. Grant for the attention he had given to the 
 subject and the results he had made public ; but though the 
 former Paper was of great use, he found the conclusions given 
 by Mr. Grant were also liable to great abuse. Those con- 
 clusions were apparently so simple that people who were not 
 
156 
 
 THE STRENGTH OP CEMENT. 
 
 altogether well versed in the subject were apt to suppose tlmt 
 they could test cement, and know good from bad by the simple 
 application of the rules. He concurred with Mr. Grant that 
 two of the qualities of good cement were high specific gravity 
 and high tensile strength ; but he thought it would be inexpe- 
 dient to push those principles to extremes. Good cement was 
 generally heavy and strong, but it did not always follow that 
 the quality was proportionate to the weight, or to the tensile 
 strength, or to the two combined. In the case of some Port- 
 land cement lately required for sea-work in India, the Govern- 
 ment had, under his advice, applied for tenders from several 
 manufacturers of repute, and the three lowest tenders were 
 accepted. It happened that the cement supplied by those 
 three makers differed, to some extent, in the points under con- 
 sideration. One being a heavy cement weighing about 120 lbs. 
 to the bushel, equal to a tensile strain of 800 lbs. to 1000 lbs., 
 on a sectional area of 2-25 square inches ; another weighing 
 about 108 lbs. to the bushel which bore a strain of 600 lbs. or 
 700 lbs. ; and the third was intermediate between the two in 
 weight, viz. about 114 lbs. to the bushel ; but the tensile 
 strength was, on the whole, greater than that of the heavier 
 cement. The superintendent of the works was, in the first 
 instance, favourably disposed towards the heavier cement, with 
 high tensile strain ; but after testing it, by exposing blocks of 
 concrete to the action of the sea during a monsoon, he was 
 unable to say that one cement was practically better than 
 the other, as judged by this test. Subsequently he had the 
 means of applying another practical test, by cutting into the 
 blocks. According to this test, he gave the preference to 
 the first heavy cement, as being decidedly harder than the 
 other two. As to the two others, he could not say which was 
 the best. But on the whole there was probably no great prac- 
 tical difference between the three cements. 
 
 He would mention another fact, to show that weight and 
 tensile strength did not always go together. A firm of cement 
 manufacturers requested him to test some cement which had 
 been condemned, and he applied the ordinary tests to it. In 
 the first place, he weighed it, and found the weight to be 
 101^ lbs. to the bushel. This was very light, and he expected 
 to find a very weak cement; he noticed, however, one remarkable 
 
THE STRENGTH OF CEMENT. 
 
 157 
 
 fact in making up the test-blocks. He adopted the plan, which 
 Mr. Grant now recommended, of using exact proportions of 
 cement and water; but he measured the cement and water, 
 instead of weighing them. With this light cement he found 
 this curious result: the measure he adopted had a capacity 
 about 50 per cent, greater than that of the test-block mould, 
 and this quantity of heavy cement in powder was suflScient, 
 when worked up with water, to fill the mould, and even left a 
 little excess after the mould was filled; but with the light 
 cement it was not enough ; the contraction of bulk was greater, 
 so that it required a larger measure of that light cement to fill 
 the mould than it did of the heavier material. When he broke 
 the test-blocks he was surprised at the strength — the several 
 breaking strains were 680 lbs., 600 lbs., 600 lbs., 585 lbs., and 
 these did not give the full strength, for they were taken out 
 of the mould quite soft. Two other samples, which were kept 
 in the mould till quite hard, were equal respectively to 960 lbs; 
 and 840 lbs., which for cement of only 101 lbs. to the bushel 
 was, he thought, very high indeed. Now, if the virtue of that 
 cement was in proportion to its tensile strength, it was not in 
 proportion to the weight. 
 
 He was glad to find the Author now insisted that extreme 
 care was necessary in making these tests. G-enerally speaking, 
 the makers tested their cement at their own works, and em- 
 ployed for that purpose a man called a sampler, who had little 
 else to do but test the cement as it was made ; and those men 
 from long practice, had acquired so much skill that, though 
 they performed the operation in a very rough manner, they 
 obtained pretty regular results. But when the cement was sent 
 to the customer, and the customer wished to test it for himself 
 he necessarily employed a person of less skill to make up the 
 test-blocks, and it was almost impossible to get consistent re- 
 sults. There would sometimes be a difference of 100 per cent, or 
 150 per cent., without any apparent cause, in the breaking strain 
 of two bricks made from the same sample. Consistent results 
 could only be obtained by adopting exact proportions of cement 
 and water. He had made some experiments to illustrate this. 
 In one experiment he used four-tenths of a pint of water for 
 each test-block, when the breaking weight in four cases was 
 970 lbs., 980 lbs., 1000 lbs., and 980 lbs. After that, he made 
 
158 
 
 THE STRENGTH OF CEMENT. 
 
 up two more samples, mixed with a half-pint of water, instead of 
 four-tenths of a pint, and those broke with 590 lbs. and 370 lbs. 
 Two others, made up with nine-twentieths of a pint, broke with 
 750 lbs. and 375 lbs. Other experiments, giving similar results, 
 led to the conclusion that it was most important to reduce the 
 quantity of water to a minimum, and for this purpose to have 
 it accurately measured. He would mention a case in which 
 neglect of this precaution had nearly led to serious results. 
 Part of the cement which he sent out to India had been tested 
 by himself before shipment, and the samples broke at a little 
 over 800 lbs. When the cement arrived at its destination, the 
 works had been stopped for a time, and 400 tons of cement were 
 left on hand. This was transferred to another work at Bombay, 
 and when it arrived there the Engineer who was to employ it 
 was directed to test the cement. The tests were made, and 
 the results were given in a strongly-worded despatch to the 
 India Office, stating that the cement was good for nothing; 
 inasmuch as the tests gave as its tensile strength only 248 lbs. 
 on the brick ; and that its employment in the work would not 
 be permitted. He thereupon recommended that some samples 
 of the cement should be sent home for further tests. On its 
 arrival it was found to be damaged by damp, to which it had 
 been naturally exposed in its three voyages and various tran- 
 shipments ; nevertheless, the test-blocks made from it bore 
 strains of 660 lbs., 690 lbs., and 800 lbs., showing that there 
 was no great deterioration of the cement. There could be 
 no doubt that the tests at Bombay were not made with the 
 necessary precautions ; but he was convinced that there was at 
 present a very prevalent ignorance as to their necessity, which 
 he hoped would be removed now that Mr. Grant had brought 
 the weight of his authority to insist upon them. Properly 
 employed the tests were most valuable, but in the hands of in- 
 experienced persons they were worse than useless. He would 
 also express his opinion, that it was a mistaken practice to 
 record only average results. All records should give individual 
 results, by which alone the value of the tests could be judged. 
 
 The weight test was one which also required to be applied 
 with due precaution. The rough mode employed by the makers 
 of shovelling the material into a bushel measure was safe enough 
 if always carried out by the same person, and he a careful and 
 
THE STEENGTH OF CEMENT. 
 
 159 
 
 experienced one ; but it was possible, by an almost involuntary 
 increase of force, to increase the density 2 or 3 per cent., and 
 by an increase such as could not be prevented by a specification, 
 to increase it 10 or 12 per cent. The employment of a hopper,' 
 as described by Mr. Grant, was the best precaution against this 
 source of error. 
 
 There was another point, however, in which care was re- 
 quired. He had alluded to some very light cement on which 
 he had experimented. The maker had assured him that this 
 cement, when manufactured, was of much greater density. 
 This led him to experiment on other samples ; and he found in 
 four cases that cement taken fresh from the manufactory or 
 from the cask was heavier by respectively 6^ lbs., 7 lbs., 4| lbs., 
 and 2f lbs. per bushel than it was after two or three days' 
 exposure to the air ; though in this latter state it was in better 
 condition for employment in practical work. It was therefore 
 necessary to specify that the density should be determined when 
 the cement was fresh from the manufactory, and not at any 
 subsequent time. 
 
 Mr. G-. F. White observed that, as one of a numerous body 
 of cement manufacturers, he desired to express his obligations 
 to Mr. Grant for the continuance of his investigations into the 
 subject of Portland cement. It was needless to say that the 
 manufacturers themselves were anxious and critical investigators 
 of the products they turned out, and had their attention con- 
 stantly directed to their improvement. He might say that in 
 his own works there were recorded thousands of experiments 
 for years past on the strength of cement ; but he could well 
 understand that no trials made by a manufacturer on his own 
 material could have for the Members of the Institution the 
 same value as those conducted by an independent Engineer. His 
 own observations on the subject of Eoman cement enabled him 
 to corroborate the remarks of Mr. Grant as to that material. It 
 was the fact that even after five years this cement did not 
 attain to a greater tensile strength than 100 to 120 lbs. on the 
 square inch, which Was less than a third of the strength of Port- 
 land cement. This sufficiently accounted for what was at one 
 time a large manufacture having dwindled down to nothing, 
 Portland cement having entirely superseded it. The same 
 remark would, in great measure, apply to Medina cement, which 
 
160 
 
 THE STKENGTH OF CEMENT. 
 
 was but a variety of Koman cement with rather more lime in it ; 
 and which, though valuable for under- water work, where rapid 
 setting was indispensable, had on the other hand the disad- 
 vantage which attached to all quickly crystallizing cements of 
 attaining to only a moderate degree of ultimate hardness. He 
 fully agreed with the Author of the Paper as to the superiority 
 of the moulds made with curved instead of straight shoulders, 
 as tending to reduce the inequality of the strain, and to bring 
 the pressure of the lever more equally on the centre of the brick 
 to be tested. With respect to the wide differences of the results 
 obtained by different experimenters on the same cement 
 there was no doubt that different modes of gauging were 
 adopted by different manipulators, some using more and others 
 less water to mix the cement. Something too might be due, in 
 the case of long voyages, to the cement having become slow 
 setting from staleness : but the mode of testing and the machine 
 used were at the bottom of the difficulty, and it would be highly 
 desirable that some rule of universal application should be 
 adopted in order to put an end to these differences. Persons 
 who had used Portland cement for the arches of tunnels or 
 bridges would have noticed the milky exudation referred to by 
 Mr. Grant in cases where there was much moisture above the 
 arch. The appearance, indeed, was not confined to cement, but 
 often showed itself where lime mortar was present. He con- 
 sidered that the milk of lime so formed was, in both cases, 
 attributable to the mechanical action of the moisture, which 
 released a minute quantity of the uncombined lime, and caused 
 it to exude. If there had been an excess of lime, in the sense 
 intended by Mr. Grant, the water would have slaked it and 
 ruptured the brickwork ; but he gathered that no bad results 
 had followed these appearances. It was, however, a subject well 
 worthy of further investigation. Concurring as he did in the 
 main with Mr. Grant's conclusions, that concentration of burning 
 and tensile strength had a direct and significant relation to one 
 another, he still maintained that, inasmuch as cement weighing 
 120 and 125 lbs, to the bushel could only be obtained by the 
 admixture of excessive proportions of lime, there was always 
 the liability to disintegration of the mortar if any of the lime 
 were in a free state. He could not avoid noticing the fact that 
 the strength of the mortar made with the heavy cement did not 
 
THE STRENGTH OF CEMENT. 
 
 161 
 
 bear the same relation to mortar made of the h'ght cement as 
 the two cements did to one another when mixed pure. This 
 seems to show that it would be fairer to test the cement with, 
 say, 2 parts of sand in the way it was going to be used in the 
 work, after the manner usually adopted by the French Engineers. 
 If Mr. Grant, in addition to the other services he had rendered, 
 could point out how good cement could be made with less fuel, 
 and thus lighten a burden which was at present their hete noire, 
 he would be conferring a lasting obligation on cement manu- 
 facturers in helping them to cheapen the cost and improve the 
 quality of their fabrication at one and the same time. 
 
 Mr. J. A. M'CoNNOCHiE inquired whether in Mr. Parkes' ex- 
 periments, where unequal quantities of water were used in 
 mixing the test-blocks, the time allowed for setting was the 
 same in each case ? It appeared to him that the time allowed 
 for setting should be regulated by the quantity of water used, if 
 a comparison were to be drawn from the experiments as to the 
 relative ultimate strength of the cement. He recently had 
 occasion to send several thousand tons of Portland cement to 
 Bombay for the drainage works, and in the case of one shipment 
 a similar report reached him as that referred to by Mr. Parkes, 
 that the cement on its arrival did not stand the tests it had 
 been subjected to before it left this country. He believed that 
 this resulted from the cement having been put into casks 
 before it had sufficiently cooled, and that it had consequently 
 deteriorated during the voyage. This was of great importance 
 in sending Portland cement to hot climates, and on its arrival 
 it should be removed from the casks, spread out, and turned 
 over to cool. 
 
 The result of an extended series of tests which he had made 
 entirely confirmed Mr. Grant's conclusions, that the two im- 
 portant features to be sought for in Portland cement were 
 weight and fineness; and that as cement possessing these 
 properties was slower in setting, tests at a longer period than 
 seven days were more satisfactory where they could be obtained, 
 for although several samples of unequal weights might attain 
 nearly the same strength in the seven days' test, the heavier 
 and slower setting would ultimately be decidedly the stronger. 
 
 He had adopted a different breaking section in his test-moulds 
 from that of Mr. Grant, retaining the same sectional area of 
 
 M 
 
162 
 
 THE STBENGTH OF CEMENT. 
 
 2-25 square inches, but disposed in a depth of 2-25 inches by 
 1 inch wide, in place of 1^ inch square. He found that with 
 this section the blocks broke in nearly all cases in the smallest 
 section, and not at the shoulders, as so often happened even 
 with Mr. Grant's improved Pattern. 
 
 He was surprised to find from Mr. Grant's experiments that 
 cement mixed by hand was double the strength of that ground 
 in a mortar-mill. He believed that this must be due to the 
 materials having been mixed for an excessive time (thirty 
 minutes) in the mill; if six or seven minutes were tried he 
 expected the result would be reversed, and that the cement 
 ground in the mill would be superior to hand-mixed. 
 
 In the case of a dock wall recently built at the Surrey Com- 
 mercial Docks, he specified Portland cement for concrete block 
 facing to weigh 116 lbs. to the bushel, with a breaking weight of 
 350 lbs. per square inch at seven days in water. The contractors 
 delivered a cement procured from Messrs. Lee, Son, and Co., ex- 
 ceeding the specification, and weighing 120 lbs. to the bushel, 
 with a breaking weight of 440 lbs. per square inch at seven days. 
 Finding this to be the case he abandoned blue lias lime for the 
 concrete backing, and substituted Portland cement concrete 
 mixed in the proportion of 1 of cement to 12 of sand and gravel. 
 This proved entirely satisfactory. He mentioned this as an 
 illustration to show that the idea which had been advanced, 
 that it was unnecessary seek for a cement stronger than the 
 materials to be cemented, was, even on the ground of economy, 
 an erroneous one, as the additional cdst per ton of a heavy and 
 strong over a light and weak cement was trifling compared with 
 the saving resulting from being able to use a greater quantity 
 of sand with it. A valuable property of Portland cement, which 
 had not been alluded to, was that the work executed with it 
 scarcely ever suffered from frost. 
 
 It was to be regretted that, with one or two exceptions, the 
 rule of thumb still so largely prevailed in the manufacture of 
 Portland cement, and he believed that by raising the standard 
 of quality still higher than Mr. Grant had yet done, the manu- 
 facture would be improved and cement more uniform in quality 
 be produced. 
 
 Mr. W. Parkes replied that in all his experiments the time 
 allowed for the cement to set had been uniformly seven days. 
 
THE STBENGTH OF CEMENT. 
 
 163 
 
 Lieutenant W. Innes, E.E., described some experiments on 
 which he had been engaged. The cement used was sampled 
 out of a large quantity supplied for War Department Works, 
 and was of a high average weight and tensile strength . Weighed 
 in the ordinary manner it would have been from 118 lbs. to 
 120 lbs. per bushel; the weights given in the following Tables 
 were lower, having been got by sliding the cement into the 
 measure down a piece of board. Each result given was the 
 mean of not less than ten experiments, all due precautions 
 having been taken with the manipulation, and the specimens 
 broken by tension in one of Addie's machines, similar to those 
 used by the Metropolitan Board of Works. 
 
 Table I. (p. 164) showed the tensile strength at three weeks 
 and three months of mortars composed of cement with two parts 
 of seven different substances, including four varieties of sand, 
 stone-dust, clay ballast, and smiths' ashes. The whole of the 
 sands, &c,, had the grains above one-twelfth of an inch in 
 diameter sifted out before use, to avoid the uncertainty caused 
 by larger grains in results got from a section only 1 J inch square. 
 The proportion of each which would have been rejected by a 
 sieve of 2500 meshes per square inch was inserted, to give some 
 idea of the different degrees of fineness, but what was actually 
 used was not so sifted. Cseteris paribus, coarse sand gave better 
 results than fine, both as regards strength and bulk of mortar 
 produced (a and h, Table I.) ; and of mortars attaining nearly 
 the same ultimate strength, that made with the finest sand set 
 the slowest (h and e, Table I.). The great difference seemingly 
 caused by a small mixture of minute shells was very noticeable. 
 The high results obtained with burnt clay (^) might probably 
 be due to its acting as a pozzolana with the free lime in the 
 cement. Mortar made with this substance was very coherent, 
 and resisted the washing action of water when green better 
 than any other ; but the bulk of mortar produced from a given 
 quantity of material was very small, and it had the disadvantage 
 of cracking and shrinking if allowed to dry before it was well set. 
 The low result got with the coal ashes was unexpected, and might 
 have been due to its containing a good deal of unburnt coal-dust ; 
 this admixture, however, was not uncommon. 
 
 The two remaining Tables showed the results of experiments 
 on the effect of coarseness of grain on the properties of cement. 
 
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161 
 
 THE STRENGTH OE CEMENT. 
 
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THE STRENGTH OF CEMENT. 
 
 165 
 
 Table II. (p. 166) showed the strength at three and six months, 
 and with from 0 to 3 parts of sand, of mortars made from cement 
 of three degrees of fineness, viz. as received from the manu- 
 facturer, and the same after being passed through sieves of 
 1300 and 2500 meshes per square inch, which rejected about 
 20 and 30 per cent, respectively. The weight per bushel and 
 the strength of the neat cement were both diminished by sifting, 
 the coarsest being heaviest and strongest and the finest lightest 
 and weakest ; but when gauged with one or more parts of sand 
 the order of strength was reversed, the fine cement giving the 
 best results. With three parts of sand and at six months the 
 finest cement attained '47, whilst the coarsest attained only '29 
 of their respective strengths neat at the same age. 
 
 Table III. (p. 167) showed the strength at three and six months 
 of neat cement varying in fineness from what would all pass 
 through a sieve of 2500 meshes per square inch down to that of 
 which 70 per cent, would be rejected. The same cement was 
 used for all, being first sifted and then re-mixed in the propor- 
 tions given. At three months the strength increased with the 
 quantity of coarse grains up to 40 per cent, of the latter ; when 
 the cement contained more than this proportion the results, 
 though high, were variable ; at six months the strength increased 
 with the quantity of coarse grains up to the highest proportion 
 tried ; viz. 70 per cent. Had it not been expected that the 
 maximum strength would have been reached with a much 
 smaller or no proportion of cOarse grains, higher proportions 
 would have been tried, but there would have been considerable 
 difficulty in gauging the coarse cement freed or nearly so from 
 the fine, as it was as harsh and incoherent as so much gravel. 
 
 Supposing the results given in Tables II. and III. to be trust- 
 worthy, they would seem to indicate a necessity for modifying 
 the present weight test and adding one for fineness, for the 
 heaviest cements were also the coarsest (heavy cement often 
 contained 30 per cent, of grains upwards of one-fiftieth of an 
 inch in diameter), and coarse cement, though it gave a high 
 tensile strength neat, did not bear sand well ; so that a cement 
 giving good results with the usual weight and strength tests 
 might give a weaker mortar when used (as it almost always 
 was) with sand, than one not passing the tests so well. This 
 had an important bearing on what had been remarked on as to 
 
THE STRENGtTH OF CEMENT. 
 
 167 
 
 .as. 
 
 ^3 ni3 ^3 *^ 
 
 -2 -2 
 
 CO « IX) 
 
168 
 
 THE STRENGTH OP CEMENT. 
 
 the doubtful advantage of a cement stronger than the building 
 material ; the advantage of such a cement should be its capacity 
 for sand, but much of this was lost by coarseness of grain. 
 
 A specific gravity test would probably be better than the 
 common weight test, if some convenient method of applying it 
 were devised ; or if the weight test were retained it might be 
 applied to a sample passed through a sieve of some fixed degree 
 of fineness ; the standard would probably in such a case have to 
 be reduced, as it seemed doubtful whether it would be possible 
 to manufacture a fine cement of the high weight per bushel 
 now thought necessary, though of equally fine cements the 
 heaviest would doubtless be the best. 
 
 Mr. G. H, Phipps said he could not subscribe to the argu- 
 ment that there was no use in having a cement stronger than 
 the materials to be held together, as he thought there were 
 many cases where a material possessing that property was ex- 
 ceedingly useful. For instance, in brick abutments for arched 
 bridges it was always an important matter to secure the courses 
 from sliding horizontally upon each other at the base of the 
 sbewbacks at the springing of the arch. This, he thought, 
 could be better secured with a cement of high cohesive power, as 
 when considered in relation to the cross joints, as well as the 
 horizontal ones, any fracture had to pass through a considerable 
 quantity of the cement itself, as well as to strip it off the bricks. 
 He thought it a great advantage to be possessed of a material 
 combining the properties of great adhesion and cohesion, and 
 which at the same time when reduced in strength by various 
 admixtures of sand, could be brought down nearly to the cost of 
 common mortar. 
 
 Mr. B. Latham observed, through the Secretary, that in con- 
 sidering the question of the strength and durability of cement 
 or mortar the attention of Engineers should be directed not only 
 to the necessity of providing a material of great cohesive 
 strength, but also one which, when applied in certain positions, 
 should resist the influence of certain chemical forces tending to 
 destroy it, when the inevitable result would be a failure in the 
 work executed. During the last two or three years he had 
 found that sewers which had been constructed for about seven- 
 teen or eighteen years, the brickwork of which was set in 
 various kinds of lime and cement, and in some cases in a 
 
THE STEENGTH OF CEMENT. 
 
 169 
 
 mixture of both, were failing, and many yards of such sewers 
 had fallen in. On examination of those defective sewers he had 
 found that every particle of cement or lime which had been 
 used in the mortar had disappeared from the joints, leaving 
 nothing but the sand to hold the work together. This failure 
 was due to the fact that sewer-water contains a certain per- 
 centage of ammonia ; the ammonia, when brought into contact 
 with ordinary lime, was. converted into nitrous and nitric acid, 
 which, in its turn, attacked the lime, forming nitrates and 
 nitrites, which were extremely soluble, and which were washed 
 out either by the sewage or by the infiltration of subsoil water 
 into the sewers, leaving nothing but the sand in the joints. 
 Cements and limes, intended to be used in such a position as to 
 be exposed to chemical influence, should, in addition to the tests 
 recommended by Mr. Grant, be subjected to a standard solution 
 of nitric acid, in order to ascertain whether or not the material 
 was suitable for the particular class of work for which it was 
 required. Portland cement was the best material for resisting 
 the chemical action of sewage ; on the other hand, lime made 
 from chalk was the worst. Therefore there was a possibility of 
 carrying the manufacture of Portland cement to such a point 
 that, in order to secure a great tensile strength, so much chalk 
 might be used in its manufacture as to render it unsuitable to 
 resist the chemical action of the matters with which it might 
 be brought into contact. He had some years ago adopted the 
 mode of constructing sewers recommended by Mr. Grant, viz. 
 with an internal ring of brickwork, the external portion of the 
 sewer being formed in concrete ; and during the last six or 
 seven years he had constructed several miles of such sewers, 
 and could bear testimony not only to their efficiency, but to 
 their great strength and durability, and to the cheapness of 
 their construction. In the case of a sewer at Croydon, which 
 was 4 feet in internal diameter, the inner circle being formed of 
 a 4i-inch ring of brickwork, and the external portion of the 
 sewer consisting of 6 inches of concrete, the sewer was con- 
 structed at 40 per cent, less cost than would have been the case 
 had the whole work been executed in 9-inch brickwork. 
 
 Mr. J. Gkant, in reply upon the discussion, observed that 
 Mr. Towle, Colonel Scott, and others contended that it did not 
 follow that cement of great cohesive was necessarily of great 
 
170 
 
 THE STRENGTH OF CEMENT. 
 
 adhesive strength ; in fact, that no advantage was gained by- 
 making cement of a strength exceeding that of the materials to 
 be cemented together. It was with the object of settling this 
 point that the B Series of experiments was made. In the Tables 
 relating to that series it would be seen that the cohesive varied 
 directly as the adhesive strength of cement ; that in fact neat 
 cement was from three to four times the adhesive strength of 
 any mixture of it with four or five times its bulk of sand ; and 
 on this account he was prepared to state, in general terms, that 
 cohesive and adhesive strength might be taken as equivalent to 
 each other. For the purpose of cementing together various 
 materials, he need hardly point out that to have strong cement 
 or mortar was not the only thing necessary. For instance, two 
 cubes of glass could not be cemented together, however strong 
 the cement, so that they should adhere with the same tenacity 
 as two bricks or blocks of stone of a porous character, and 
 rough on their faces. It would not be possible, for example, to 
 take such bricks as were recently used for lining the subway 
 from the Houses of Parliament to the adjoining railway station, 
 and to cement their highly glazed china faces together so that 
 it would require the same pull to separate them as it would to 
 separate two stocks, wire-cut gault, Fareham red, or other 
 porous bricks, capable of absorbing about one-fifth part of their 
 weight of water. Whilst on this point he might state that only 
 second in importance, if second, to the strength of the cement 
 was that of seeing that the bricks or stone to be cemented 
 together were thoroughly saturated with water. In hot climates 
 like that of India, any work being built with cement should be 
 kept wet, and if possible under shelter during its progress and 
 for some time afterwards. Two bricks might be put together 
 dry as they came from the kiln with the strongest cement that 
 could be made, and if not previously soaked in water, these 
 bricks might be separated without the least difficulty, the joint 
 being very little better than if made of dry sand. With bricks 
 which absorbed from 1 lb. to 1 J lb. of water, it was evident that 
 if left to absorb this moisture from the mortar with which they 
 were cemented, they took away that which was necessary for 
 crystallizing or setting the cement. 
 
 He thought it must be self-evident that for making concrete 
 strong cement was much to be preferred to weak. Concrete 
 
THE STBENGTH OF CEMENT. 
 
 171 
 
 made of absorbent material, such as broken bricks, stone, or pot- 
 tery, was much stronger than concrete made of Thames ballast 
 or any other slightly absorbent material. In the D Series of 
 Tables it would be found that concrete made of Thames ballast 
 was only from half to two-thirds the strength of concrete made 
 of broken bricks, stone, or pottery. It would be found also that 
 bricks of a somewhat porous character, like the red bricks or the 
 wire-cut gault bricks, and the other varieties shown in Table B, 
 adhered together with a strength double that of bricks like the 
 Staffordshire blue bricks without a frog, or bricks that had a 
 smooth or glazed surface. 
 
 On the point of strength it had been pointed out clearly five 
 years ago, and again on the present occasion, that the strength 
 of cement could always be reduced by mixing sand in any pro- 
 portion. 
 
 With respect to the cement or lime mentioned by Colonel 
 Scott, he had the pleasure of going over part of the works at 
 South Kensington, and had also an opportunity of testing the 
 cement in one of the large sewers where it was used in the arch ; 
 but he was sorry to say it did not answer the purpose, and was 
 much inferior to lias lime. On a later occasion he made a 
 number of briquettes or moulds of it, as in the case of cement ; 
 but it was so weak that it would not bear winding up in the 
 machine. Thus either Colonel Scott was not fortunate enouo'h 
 to have made his comparisons with Portland cement of a good 
 quality or he had himself been unfortunate enough to meet 
 with an inferior sample of the lime or cement referred to. The 
 objections raised by Mr. Parkes as to the comparative strength 
 of cements of different specific gravities might be valid if the 
 time allowed for the heavier cement was short; in fact, the 
 heavier the cement the longer time it was necessary to give it 
 to set. For experimental purposes with heavy cements a month 
 was fairer than a week. For practical purposes, in works carried 
 on in the streets of London, a week was a more convenient time ; 
 but for experimental purposes with different weights of cement 
 the longer time was much more satisfactory. 
 
 As to the strength of cements generally, if it could be made 
 of a high quality it might at any time, as he had stated, be 
 reduced in strength. It was not unlikely at some future, though 
 it might be far distant, time that many of the sandy districts of 
 
172 
 
 THE STBENGTH OF CEMENT. 
 
 Africa and other parts of the world might be irrigated by- 
 aqueducts, for the construction of which all the materials neces- 
 sary would be comparatively small quantities of cement in a 
 concentrated form, to reduce the bulk and cost of freight, mixed 
 with the sand upon the spot. 
 
 Mr. YiGNOLES, President, said there was not time for him to 
 express fully his individual opinion on this subject, and he must 
 content himself with observing that he did not concur in all 
 that Mr. Bazalgette and Mr. Grant had propounded, and that 
 there was much to be said upon what had been advanced by 
 Colonel Scott with regard to having too strong an adhesive 
 material. He thought the subject had yet to be considered 
 more fully. 
 
 tONDON : PRINTED BT W. CLOWES AND SONS, STAMFORD STREET AND CHARING CROSS. 
 
PLATE 2. 
 
 MOULD PROPOSED TO BE USED IN 
 FUTURE EXPERIMENTS. 
 
 SECTION AT Y. Y. &. Z . Z 
 
 ELE.VAT I ON 
 
 SCALE, QUARTER FULL SIZE. 
 
 JOmr GKAUT. BELT. 
 
 Tho? Kdl, lidi, LoTukm . 
 
PLATE 3 . 
 
 JOHN GRANT. DECT- 
 
 TliD?KellJiii,Laiulm. 
 
JOHN GSAUTf, BF.LT- 
 
 Tho? Kai,T.i{K;LoRaoTv. 
 
PLATE 5. 
 
 DIAGRAM TO ILLUSTRATE TABLE. V. SHEWING TH£ AVERAGE BREAKING WEIGHT AND THE 
 TOTAL QUANTITY OF CEMENT SUPPLIED TO EACH CONTRACT, 
 MAIN DRAINAGE OF LONDON, SOUTH SIDE. 
 
 !Note. 77i«/ f^r-tic.a-l/ 'fcctZe^ ipAww the'Tuxmben of Iba. oU> yvhzch^ tfve/ Garvervt/ bro^ce/, withy tx/ 
 tervsiie' SircUrv, on,ou >9ectiorvaZ' ccrva, o^' ) . S&uJiy X 7 .S inc/v^ 2. 2S Sgu^arze/ iruJvea. The- 
 ■weight of Caruervt/ wns 1^4-. 16 lbs. per- bu^hei'. 
 
 The/ HoT'iz^yrtXaL 'S'oaZe/ ■shei^vs the. TvumJ>ercfbvisfLels xijsecL XApon^ tlue, VVbr~/c^. 
 
 fiNSTITUTE. 
 
 SOUTHERN OUTFALL WORKS 
 
 S43 , G20 JixisJuda. 
 
 BERMONDSEV 
 BRANCH 
 (SEWER) 
 
 TS,4e2iiushjds. da.inB^ 
 
 <UJ 
 
 * ui 
 
 la 
 
 CO 
 
 LOW LEVEL SEWER 
 (SOUTH^ 
 
 220. SOS BvL^Tiels 
 
 J z 
 O 
 I - 
 
 60,4^ b¥- 
 
 HIGH LEVEL SEWER 
 (SOUTH^ 
 
 14S. 728 JBxieheLs. 
 
 OUTFALL SEWER SOUTH 
 
 331.4,06 Bushels 
 
 DEPTFORD 
 PUMPING 
 STATION 
 
 S3. 714. b¥- 
 
 6.m bV- 
 
 lOO.OOO 
 
 200,000 
 
 GOO, GOO 700,000 800,000 
 
 Scale, 1 IncK = lOO.OOOBushela. 
 
 1,000,000 
 
 1,200,000 
 
 1,800.000 
 
 1,400,000 
 
 JOHN GRAMT, DEL";- 
 
 Tho? Kell, litho. Itwdon. 
 
Back of 
 Foldout 
 Not Imaged 
 
DIAGRAM TO ILLUSTRATE TABLES XVII AND XXVII, SHEWING THE COMPARATIVE STRENGTH OF PORTLAND CEMENT 
 WITH SAND OF DIFFERENT KINDS, AND WITH DIFFERENT PROPORTIONS. AND OF 
 PORTLAND CEMENT AND ROMAN CEMENT OF DIFFERENT AGES. 
 
 PLATE 
 
 txny testa. The.vmffht'oftAf!- Cemervt yircuf />2 16^ buif/veL. 
 
 Ce^e^iu 112 lbs 
 
 -to 1 of CerrvmX/ 
 
 5 6 
 
 Scale, 1 Itieh. 1 MontK. 
 
 JOHN OHANT. D'ELT- 
 
 Tho? Tfrn, Liiho, Landcm. 
 
Back of 
 Foldout 
 Not Imaged 
 
DIAGRAM TO ILLUSTRATE TABLE XVIll. 
 
 PLATE 7. 
 
 3fot^. The, VertiMxL ScaZe^^hew^ the, rvumJ>er- of" Lbs. ajb tvhCch, tAe, CemjerU^ bi-okty wiOocutenjttlle' strainy, on^co SectLaruxZ areoy 
 of 7. 6m.. / / 6iny. =Z.ZS sgu^e. ineAe,9, ea^Ay r^tlt, le/j^ the ojireT^^e, cfvcny <erf6y. The, weight- d^thjv Ccrrvervt >»w 
 123 (As. per bushely. 
 
 ThtMirvsorUaZ ScaU,ahews tfu,agt,oetjKe, CerrverU UbulcU, if^vCcJvvtrr^ hif>i irvwaierditr-in^ iAe-wfwU time,. 
 
 012 3 lAfanflL 2 
 
 Scale, 1 Inch — 3Mcmths. 
 
 JOKif GPANT. DKr.T 
 
 Xho°. Kell.jLithr.i-.jniior 
 
Back of 
 Foldout 
 Not Imaged 
 
ILLUSTRATIONS OF ITS USE IN THE MAIN-DRAINAGE OF LONDON AND SOUTHERN THAMES EMBANKMENT. 
 
 s . g; 
 
 I'LATf, 
 
 CONCRETE SEWER. 
 
 JOHH CHliNT, DKr.T- 
 
 conGrete sewer 
 earl-deptford lower road. 
 
 ALBERT OR SOUTHERN EMBANKMENT. 
 
 l^aixfth' 43C0 Feet/. 
 
 Scale, for- Figf 12 £ 13 , (ffeel. = / Inc/L'. 
 
 TiyiLilK40.iecg St CoTOit GardovWC. 
 
Back of 
 Foldout 
 Not Imaged 
 
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