ngmeers Haiidn fytmll Hmuraitg jilrwg THE GIFT OF 3.*>^M^£JLUy_ J^i SV.t .s\ .: yi \x W Cornell University Library TA 444.A51 Handbook and cataqoue of concrete reinf 3 1924 021 907 252 Cornell University Library The original of this book is in the Cornell University Library. There are no known copyright restrictions in the United States on the use of the text. http://www.archive.org/details/cu31924021907252 American Steel & Wire Co. Handbook and Catalogue °f \ UlSKIl 1 Concrete Reinforcement it EVi Utrfti ' ■ ;l I lit: ARV PRICE $2.00 copyrighted by American Steel & Wire Co. February 3rd, 1908 a> CONTENTS Page. INTRODUCTION 3 to 5 REINFORCED CONCRETE 6 "HOW GOOD IS CONCRETE," by Walter Loring Webb, C. E 6 to 14 ECONOMIC USE AND PROPERTIES OF REINFORCED CON- , CRETE, from "Reinforced Concrete," Buel & Hill 15 to 27 ; GO,ST|S 28 APPROXIMATE COST OF CONCRETE, from "Concrete Plain and Reinforced," Taylor & Thompson 28, 29 STEEL FOR REINFORCING 32 to 34 PROTECTION OF STEEL OR IRON FROM CORROSION 35 to 38 FIRE PROTECTION, from "Concrete Plain and Reinforced," Taylor & Thompson 39 to 42 MODULUS OR COEFFICIENT OF ELASTICITY 43 to 45 BONDING OLD AND NEW CONCRETE, from "Concrete Plain and Reinforced," Taylor & Thompson 46 EFFECTS OF FREEZING, from "Concrete Plain and Rein- forced," Taylor & Thompson 47 CLASSIFICATION OF CEMENTS, from "Concrete Plain and Reinforced," Taylor & Thompson 48 to 54 FINISHING SURFACES OF REINFORCED CONCRETE 55 FACING AND FINISHING EXPOSED CONCRETE SURFACES, from "Reinforced Concrete," Buel & Hill 55 to 65 QUANTITIES OF MATERIALS .''. 66 to 73 SAFE LOADING AND REINFORCEMENT FOR STONE CON- CRETE BEAMS, Taylor & Thompson 74 TABLES OF WEIGHTS, AREAS, SIZES, TRIANGULAR AND SQUARE MESH REINFORCEMENT 75 to 81 TABLES AND DIAGRAMS OF SAFE BENDING MOMENTS, WEIGHTS, AND THICKNESS OF SLABS, AREAS OF STEEL, ETC 83 to 93 TABLES OF WEIGHTS AND AREAS OF ROUND AND SQUARE BARS 94 to 97 ILLUSTRATIONS OF USES OF REINFORCED CONCRETE 98 to 130 INTRODUCTION IN preparing and presenting to the public this Catalogue on Re- inforcement for Concrete, our effort has been to offer a book containing facts, not only regarding the reinforcement of concrete, but concrete itself. The data contained herein is not only the result of careful study of our own engineering department, but also that of some of the best known engineers of the country. Many paragraphs and chapters dealing with reinforced concrete are selected and reprinted by permission, from "Concrete Plain and Reinforced," by Taylor & Thompson; "Reinforced Concrete", by Buel & Hill, and others. We are presenting two distinct designs or types of Steel Wire Reinforcement — Triangular and Square Mesh. Our Triangular Mesh is built up of either stranded or solid longitudinal or tension members, with the cross or bond wires arranged or running diagonally across the widtht of fabric. This arrangement not only affords the most even distribution of the steel, reinforces in every possible direc- tion, and provides the most ideal mechanical, as well as adhesive bond between the steel and concrete. Tables of weights, areas, bending moments and Tensil strengths of this Triangular Reinforcement are shown on Pages 76, 77, 78, 79. Our Square Mesh type of reinforcement is similar to that made by other manufacturers of this style, the longitudinal or tension mem- bers being solid or single wires — evenly spaced, one from the other — with the cross or bond wires running at right angles with the tension members. This style being also an excellent reinforcement for con- crete. Tables of weights, areas, etc., of this Square Mesh are shown on Pages 80, 81. Tables are given showing the weight per square foot, number, sizes, spacings, and areas of wires and longitudinal strands; also, tables and diagrams giving moments for usual thickness of slabs, by the aid of which a suitable fabric, used with or without bars, may be selected for all kinds of loads, spans, and conditions met with in the construction of buildings, bridges, and reinforced concrete in general. It may be found that two or more fabrics will have an area corresponding to the required bending moment. In this case, the comparative listed price, weight per square foot, and the design of the building must decide which is the most efficient type. The formula used in calculating the table of moments is based on the tests made by A. N. Talbot, reported in the proceedings of the American Society for Testing Materials. These v/e believe to be the most reliable and complete tests, involving no theoretical assumptions. 4 AMERICAN STEEL & WIRE CO. We feel that the tables of strengths we are offering are the best, and are perfectly safe and reliable. Having adopted a working stress of 16,000 pounds per square inch, which is allowed by the buildings laws of most large cities. This is about one-quarter of the strength of ordinary mild steel wire, and if our formulas and tables are used, the concrete will not be strained so as to cause cracks in the tension side, if reinforcement and concrete are properly placed and selected. While we recommend the use of our ordinary mild steel fabric such as covered by our tables, there are cases when a structure may be subjected to uncertain and fluctuating loads which may cause cracks in the concrete. In such cases, we recommend fabric made of wire having a much higher tensile strength. We can furnish fabric composed of steel wire having a tensile strength of two or three times that of the steel specified in the tables, the elastic limit of which may reach as high as 120,000 pounds. With a factor of safety of 4, we can therefore allow stress of 30,000 pounds per square inch, instead of 16,000 pounds. In fact, we are prepared to furnish any grade of steel desired; this because the amount of carbon or the hardness of the steel does not interfere with the proper construction of our fabric. In our tables we have assumed an average composition of con- crete, using high grade Portland cement in the proportion of 1, 2-%, and 5. This we have found to be an average composition of all concrete, which has given the best results, and which may be recom- mended for all floors or other structures subjected to high stresses. In both our Triangular and Square types, we can make the longitudinal members of either single wires or strands. Although we believe that there is actually no slipping possible between the steel and the concrete, and that our single-wire types meet all possible con- ditions for ordinary loads and spans, we find that the twisted longi- tudinal strands embody all the features and advantages claimed for the twisted or corrugated bar systems. Besides, a strand exposes more surface in relation to the area for the adhesion to the concrete, which we believe is a decided advantage as well as a most perfect mechanical bond. Fully convinced that our Triangular type is far superior to any metal reinforcement heretofore used, we wish to call attention to the special features. It is impossible for the cross wires to slip without breaking, and our method of making the joint between the continuous cross wire and the longitudinals makes this type especially desirable for such constructions which are subjected to great variations in temperature, or to prevent cracks due to shrinkage in concrete cover- ing large areas. It has all the desirable features of the expanded metal, but of course, reprints an entirely different article when strength is AMERICAN STEEL & WIRE CO. 5 considered. This is owing to the straight continuous longitudinals which take the main portion of the load, and can be made with almost any desired capacity. Another advantage is that in breaking con- crete reinforced by our Triangular Reinforcement, the diagonal cross wires must also be sheared or pulled apart; hence, they add to the strength of the reinforcement, which is not the case with a square mesh. 6 AMERICAN STEEL & WIRE CO. REINFORCED CONCRETE. The uses of reinforced concrete are daily increasing. Results are being obtained with this material which are not only more prac- tical, but more economical than that of materials previously employ- ed. As a fire proofing it has no equal. The article below "How Good is Concrete," by Walter Loring Webb, C. B., reprinted by permission from the March issue of the Technical World Magazine, Chicago, is one of the best illustrations of its uses and value, and cannot be over- looked, coming from one having so wide experience with concrete: HOW GOOD IS CONCRETE? A building material that will not rust or decay and that will not be subject to the attacks either of insects or of atmospheric acids; that will be fireproof and earthquake.-proof and capable of supporting heavy loads over long spans — a material that has all these virtues and still is not prohibitively costly — such a material would be close to ideal. And the material that most nearly meets these essential requirements and that is daily undergoing tests with credit is rein- forced concrete. The usual building materials fall far short of the above ideal. Wood, in spite of its many advantages, is subject to decay and the ravages of the teredo navalis if it is placed in seawater; it must be frequently repainted and it is highly combustible. Steel, in spite of constant repainting, will rust unless it is thoroughly protected by concrete. Unless it is thoroughly fireproofed, the heat usually de- veloped by a conflagration is so great that the steel will soften and yield, thus causing the whole structure to collapse. Although stone in the form of building blocks has the great advantage of architectural beauty, it cannot withstand fire and especially the frequent combination of the great heat of a conflagration and the sudden application of a stream of cold water. The carbonic acid of the atmosphere will speedily affect marble and limestone fronts. Stone is useler3 for long spans except in the form of expensive arches which must have a con- siderable rise in proportion to the span and this renders its use inap- plicable for all except a limited class of expensive structures. The re- cent destruction of San Francisco by Earthquake shows how helpless the ordinary stone or brick structure is under such circumstances. Brick has nearly all of the disadvantages of stone except in degree. A good quality of brick will withstand fire far better than stone, and is unaffected by frost or the carbonic acid in the atmosphere, but its use is absolutely limited to supplying compressive resistance. The very expensive method of floor construction, using steel I-beams with small arches of brick or hollow tile, which a few years ago was considered to be the only method which deserved the name of fireproof, has been found to be only relatively fireproof and in fact it affords but little protection against a hot Are. It was one of the AMERICAN STEEL & WIRE CO. 7 compensations of the Baltimore fire that it furnished a very convincing test of the relative methods of the various systems of fireproofing which have been devised. The old-fashioned floors constructed of steel I-beams, connected by brick or by hollow tiles, provided little or no protection to a building against its almost complete destruction by the flames. On the other hand, the few existing floods of reinforced con- crete were structurally unharmed during that trial. In strong comparison with the qualities of the various building materials enumerated above is the statement of the corresponding qualities of reinforced concrete. It is in no sense subject to decay and when it is used in seawater for the foundation of a pier or wharf it is unaffected by the teredo, which so quickly destroys timber. It is not affected by rust nor by the carbonic acid in the atmosphere. When properly constructed, it requires no maintenance charge for painting or for any other kind of protective treatment. The various tests, which have been made by the building bureaus of great cities, as well as by the involuntary test of great conflagrations, have shown that its power for resisting fire — and even a combination of fire and water — is greater than that of any other known type of building construction. Although the lower layer of concrete will probably be calcined during a fire, the lower layer will of itself act as a fire-proofing material which will prevent injury to the upper layers. Since the area of the lower layer is always regarded in computing the strength of the reinforced concrete, it is always possible after such a fire to scrape off the injured concrete and to replace it with a layer of other material which will again act as a fire-proofing material. Structurally the floor will be uninjured. A brief description of one of these tests will show the re- markable resistance of reinforced concrete to fire. During November, 1905, a building was constructed near New Brunswick, New Jersey, for the special purpose of the test. The roof consisted of a four-inch slab of reinforced concrete supported on con- crete beams. The side walls of the building were made of concrete. A grate of iron bars was built across the entire floor area and ample provision was made for draft. When the concrete had become suffi- ciently hard, the roof was loaded with a dead load of pig iron to the amount of 150 pounds per square foot. On December twenty-sixth, the structure was tested. A fire was built and fed with cordwood until an electric pyrometer indicated a temperature of 1,700° F. This temperature, with small flunctuations above and below, was main- tained for four hours. Then the firedoors were opened and a stream of water, having a pressure of ninety pounds per square inch at the pumps was played on the under surface of the roof for ten minutes. As was expected, the lower layer of concrete, which had been calcined by the heat, was swept off by the mechanical action of the powerful stream, but the roof still held its load of pig iron. On the following day, the concrete having cooled off and having recovered a large part of its deflection during the fire, still more pig iron was loaded on until the load amounted to 600 pounds per square foot, and even at such a 8 AMERICAN STEEL & WIRE CO. load, the four inch slab, which had been subjected to such a severe alternation of intense heat and rapid cooling, was not broken down. The one fact that the structure was sufficiently elastic to recover, while cooling, a large proportion of its deflection during the intense heat shows a very remarkable quality of this material. There was also a, compensation in the San Francisco disaster when it was demonstrated that the few instances of reinforced concrete work which were located within the area of the disturbance were structur- ally uninjured by the earthquake. The monolithic character of these buildings prevented their disintegration when adjoining buildings, con- sisting of brick and stone joined by mortar joints having little cohesive strength, were rapidly disintegrated by the earthquake shocks. Owing to the limitations of the building laws there were no buildings in San Francisco itself which were constructed entirely of reinforced con- crete, although there were many floors of this material. An official inspection of all injured buildings was made by an expert for the Board of Underwriters. His report on the injury to reinforced con- crete floors was almost monotonously "no structural damage." The very few cases of reported injury were invariably accompanied by the statement that the supports of the flooring had given away. Perhaps the most remarkable characteristics of reinforced concrete construction is the fact that girders, beams and floor slabs, having a very considerable span and comparatively little vertical depth, may be built so as to carry the heaviest working loads desired by modern conditions. This characteristic only becomes possible on account of its power of resistance to transverse bending. Such resistance depends on the ability of the material to resist tensile stresses . This tensile strength is furnished by the steel which is so proportioned and placed that it will furnish the desired resistance . It is not very many years since an engineer would have been considered foolish to have predicted that two such dissimilar materials as concrete and steel could be com- bined into a composite structure and that they would mutually rein- force each other and each supply the qualities the other lacked. The tensile strength of concrete is usually very small. Although some specimens have required a pull of 300 or 400 pounds per square inch and even more to break them, the breaking strength is usually not more than 200 pounds per square inch, which is so small that it becomes prac- tically useless to depend on such strength for transverse stresses of any magnitude. It may be easily demonstrated by practice as well as by theory that a concrete beam, whose span compared with its depth is comparatively large, will not even support its own weight, to say nothing of carrying a live load. It is not considered safe practice to depend on a working tensile stress of more than 50 pounds per square inch in concrete. On the other hand, even a low-carbon steel will usually have an ultimate tensile strength of 55,000 to 60,000 pounds per square inch and a high-carbon steel, such as is frequently used in reinforced concrete, has an ultimate tensile strength of about 100,000 pounds per square inch. Even if we only allow a working AMERICAN STEEL & WIRE CO. 9 stress of 16,000 pounds per square Inch in the steel, we are using a working stress which is 320 times as great as that which is permissible in the concrete. A cubic foot of steel weighs about 490 pounds. At three cents per pound this is worth J14.70. On the other hand, a cubic foot of concrete is worth perhaps 20 cents or, let us say, 1-7 5 th of the cost of steel. But if the steel is 320 times as strong as the concrete we can afford to pay 75 times as much for the unit area of steel as for the unit area of concrete and even then the steel is more than four times as cheap as the concrete, considering what it will accomplish. On the other hand, with a good grade of concrete we may safely use a working stress of 500 pounds per square inch in com- pression. We cannot safely use more than 16,000 pounds per square inch as the working tension for steel. This is only 32 times the allowable working stress in the concrete, and since the steel costs about 75 times as much as the concrete, the concrete is far cheaper as a material with which to withstand compression. It should be realized that the real test is the actual cost of obtaining so many pounds of tension or compression, almost regardless of the kind of material which furnishes it. Although the above unit values of con- crete and steel may be varied, both actually and relatively, they are substantially correct and will never be modified so greatly as to alter the general conclusion that by constructing our beams and slabs by such a method that the tension is furnished by steel and the compres- sion by- concrete, we have the most economical combination of mater- ials. Of course there is far more to the theory of reinforced concrete than the mere placing of steel in the tension side of a beam or slab. Every ounce of tension in the steel is only effective as it is transferred to the concrete. In the case of a plain beam with free ends, there is no stress in the steel at the ends while the maximum tension is usually at or near the center of the beam. The entire amount of this tension must be gradually transferred from the steel to the concrete. In the earlier designs the adhension of the concrete to the steel was relied on to permit the transfer of this stress from one material to the other. Elaborate tests have been made to determine the amount of this ad- hesion. Although the experimental values vary, as was to be expected, there was sufficient uniformity apparently to indicate a fairly con- stant safe working value. A great deal of reinforced concrete work has been done — and is still being done — on the basis of the perma- nency of this adhesion. But it is now being realized that this adhesion is not permanent and that, regardless of its value in comparatively new and fresh test specimens, the adhesion is very greatly reduced with age and under certain unfavorable conditions, such as continued soak- ing of the concrete in water, long continued vibration, etc. Failures of floors have already occurred, due to loss of the adhesion after they have successfully supported heavy loads for many years. On this account "deformed" bars, which have an irregular surface and which furnish a "mechanical bond" are now being extensively and even exclusively 10 AMERICAN STEEL & WIRE CO. employed by many engineers. Some of these bars require to pull them^ out of concrete more than twice the force that is required by plain bars of the same cross-section. This shows that even if the adhesion were entirely destroyed, the mechanical bond will still furnish as much resistance to slipping as will be furnished by adhesion alone under the most favorable circumstances. Such a union between the concrete and steel at all points along its length in an absolute essential to the stability of such structure. It is said that a florist first conceived the idea of combining metal and cement, in making flower pots. He found that they could be made more tough, and less liable to break by imbedding wire netting in the concrete. The success of these flower pots encouraged the extension of the principle of combining steel and concrete. One of the most economical applications of reinforced concrete lies in the construction of retaining walls. Although there is some variability and uncertainty as to the amount of the actual lateral pressure of earthwork, the proper design of solid masonry retaining wall becomes an exact problem when we have once assumed the direc- tion, point of application and amount of the earth pressure. This usual- ly requires, a very large cross section of masonry, which is corres- pondingly expensive. The reinforced concrete method employes a comparatively thin vertical curtain Wall and a large base plate which is as wide and perhaps a little wider than the ordinary plain retaining wall, the base plate being tied to the thin face wall by buttresses spaced at frequent intervals. The face wall and base plate are both capable of withstanding transverse stresses, while the stress in the but- tresses is usually that of tension. Since reinforced concrete is the one form of masonry which can withstand any considerable amount of transverse and tensile stresses, the above form of construction can only be made in reinforced concrete. Of course, the same form could be adopted if we used steel or wood, but the durability of either material would be so little that it would not pay to construct a retaining wall of such materials. Another remarkable application of reinforced concrete is the pos- sibility of making columns which are much stronger than plain con- crete columns and yet which do not employ a core of steel to take the most of the compression. A column whose length is 20 or 25 times its diameter will probably fail by buckling, in which case the steel on the convex side of the column would be subject to tension rather than compression. But a "short" column must fail by compression, if sub- jected to sufficient stress. Even in this case, steel may be employed to furnish strength on account of its resistence to tension. Although the explanation is not theoretically exact, the principle mighth be ex- plained by an illustration of filling a stove pipe with sand and subject- ing it to compression. The sand alone, especially if dried, would not sustain its own weight as a column. When confined by the stove pipe the compression of the sand will' cause a bursting pressure on the pipe. If the pipe were filled with a liquid instead of sand and if a piston. AMERICAN STEEL & WIRE CO. H which fitted the pipe tightly, were placed on top of the liquid so that a load could be placed on the piston, the resulting bursting pressure on the pipe would be a perfectly definite mathematical quantity depending on the load which was placed on the piston and also on the weight of the liquid. When we use sand instead of the liquid, the grains of sand will tend to lock themselves together and the load on the sand would need to be proportionately far greater to produce any given tension in the pipe. Using concrete instead of sand the resistance to the "flow" of the material will be still greater, which practically means that a comparatively small amount of tensile strength in the pipe will produce a very much added resistance to compression. In practice, in- stead of using an actual pipe of metal, a series of rings are made of light bars and spaced a few inches apart are bent around a few lon- gitudinal bars whose chief function is to form a framework on which to fasten the horizontal rings and prevent them from becoming displaced during the laying and tamping of the concrete. Such compression members are used" not only for vertical columns, but also as the com- pression members of truss bridges, of which several have been con- structed. Tests of such columns have required a compression of over 6,000 pounds per square inch to cause failure. Although the construc- tion of trussed forms in reinfroced concrete is not common, the rein- forcement of vertical columns in such a manner that they may be safely subjected to greater loads than should be placed on plain concrete columns of equal size, is now recognized as safe engineering practice. Another useful application of reinforced concrete lies in the build- ing of structures which are especially subject to the fumes arising from the stacks of locomotives. This applies not only to engine houses and coaling stations, but also to over-head highway bridges, which cross railroads- The concentrated gases of combustion have a corrosive action on steel .which wears it away in the course of a few years. No matter how much the steel may be protected by paint, even the paint will be worn off by the mechanical action of the fine cinders which are blown out by the exhaust and which act as a very effective form of sand blast. Probably most kinds of paints are chemically affected more or less but the combination of chemical action and mechanical wear will destroy any protective covering in a comparatively short time. Rein- forced concrete is absolutely unaffected chemically while the mechan- ical sand-blast action of the exhaust is so utterly insignificant that it need not be considered. Although a wooden structure is not seriously affected by the exhaust, its lack of durability, its danger from de- struction by fire and the recent very great increase in the price of lumber, have combined to render wood an unsatisfacbtory and un eco- nomical material for such structures. The advantages of reinforced concrete in the construction of coal- ing stations also is now being recognized. A frame work of structural steel, with steel plates for the floors and sides of the pockets, has been tried in order to obtain a non-combustible structure. But the sulphuric acid, always present in the ooal, corrodes the steel very rapidly and the 12 AMERICAN STEEL & WIRE CO. life of such a structure is short. If the steel is adequately protected against corrosion by concrete, the cost is considerably in excess of a steel structure, but far greater permanence is secured. In its application to the construction of masonry dams, reinforced concrete has entered another field. A solid masonry dam is usually constructed on the gravity principle, which means practically that the volume of its masonry is so great and so heavy that it is supposed to be safe against .over-turning, but the cost of such a construction is so great that the cross section of the dam is usually reduced to the lowest limit which is considered permissible. The upper face of such a dam usually makes an angle considerably greater than 45° with the hori- zontal and, under such conditions, a flood over the dam will raise the line of pressure and decrease the factor of safety. The higher the flood, the greater the danger. Under such conditions, a weakening of the foundation or an unsuspected washing out of the sub-soil may cause a settlement and a shifting of the line of pressure until the fac- tor of safety, which for the sake of "economy" has been made very low, is wiped out and the result is a disaster which perhaps spreads destruction through a valley. Another type of dam is illustrated in an old fashioned timber dam which is always constructed with a comparatively flat up-stream face, the angle of the upper face with the horizontal being less than 4 5°. Even the line of the resulting water pressure lies inside the base of the dam. There is never any tendency to over-turn and a flood only increases the pressure of the dam on its foundation. As long as such a dam is kept tight, so that there is no flow of water through the dam to disintegrate the foundation, the dam is usually safe, but, being con- structed of timber which is usually alternatly wet or dry, the life of such a dam is exceedingly limited, and, considering the present price oi lumber, is not even economical. A reinforced concrete hollow dam combines all of the safe prin- ciples and advantages of a timber dam with the indefinite durability of first class masonry construction. The up-stream face of a concrete dam is made with a comparatively flat slope, usually less than 45° with the horizontal. Hydraulic pressure being a perfectly definite quantity, it enables the engineer to design such a dam with a full knowledge of the stresses to which it will be subjected. These stresses are such that they may be easily provided for by the skeleton construc- tion which is adopted for these dams. The dams consist essentially of an up-stream "deck" whose chief duty is to withstand the direct and definite pressure of the water above it. This deck is supported at in- tervals by vertical walls which are parallel with the line of the stream and which transfer the pressure to the foundation of the dam. One great advantage in the method of construction is that, the dam being hollow, it is possible to detect any leaks which might develop and usually they can even be repaired without emptying the reservoir. The broad base of these dams permit them to be placed on sub-soils which ordinarily would be considered too soft for any masonry dam, AMERICAN STEEL & WIRE CO. 13 uul which can sustain on such a broad base all the pressure which can possibly come on them. Concrete dams are constructed very rapidly and at such a reduc- tion of cost below that of ordinary masonry dams that such designs have rendered practicable the utilization of water powers which would not financially justify the construction of an ordinary stone masonry dam. The construction of these hollow concrete dams has even per- mitted the utilization of the space within them for gates and even for the location of water wheels and dynamos, thus permitting a very great reduction in the cost of the entire plant. Such a dam may even con- tain a passageway which will permit crossing the river in times of the highest floods, and thus save the construction of a bridge at that point. The dam recently constructed at Schuylervi'lle, New York, is an illus- tration of this feature. Another remarkable characteristic of reinforced concrete construc- tion is the possibility of avoiding expansion joints in continuous struc- tures, no matter what may be the length. For example, if it were de- sired to construct a retaining wall with a length of a mile or more it can be done without employing expansion joints such as would be ab- solutely necessary with any other form of masonry construction. Many engineers are still skeptical on this point but the ultimate proof of such a theory lies in practice and it is indisputable that there are many examples of structures built of reinforced concrete which would un- questionably have shown temperature cracks if they had been built of ordinary masonry, but which, although built for several years — long enough for such cracks to have developed — have not shown any evidence of cracking. The only apparent rational explanation of what appears now to be an undoubted fact is, practically, the same as that which permits a re- inforced concrete beam to be deflected for a very considerable percent- age of its span without showing any cracks on the stretched side. It is well-known that plain concrete cannot be stretched more than a very minute fraction of its length without cracking. A very long monolith of plain concrete will nearly always develop cracks which are caused by a concentration of the stretching at the weakest points in the con- crete and since the proportional amount at which concrete may be stretched without rupture is very small, a concentration of the exten- sion at one place will cause rupture at that point. If the metal is prop- erly imbedded in the concrete, so that the concrete and the metal will stretch together, then the deformity of the concrete by stretching will be distributed uniformly throughout its length instead of being con- fined to a few points. Objection is sometimes made to the policy of not using expanded joints on the ground that there have been several instances of mono- lithic reinforced concrete structures in which temperature cracks have developed. In such cases it is easily demonstrable that the metal was not well distributed through the body of the concrete. The effectual prevention of cracks is only accomplished by such an intimate union of 14 AMERICAN STEEL & WIRE CO. the concrete and the steel that they must act together under all circum- stances and conditions of temperature. It is not an easy matter to compute theoretically just what proportion of metal will be needed to insure a wall against cracking. It is probably true that the metal which will ordinarily be needed for reinforcement will also be able to take care of such stresses and it is certainly true that the uniform distri- bution of the metal is of far greater importance than its amount. The Harvard stadium has a length of fourteen hundred .feet and was con- structed without expansion joints. It has already experienced three northern winters. No cracks have developed in this structure except at a point where the straight portion joins the semi-circular end and even here the cause of the crack is not considered due to changes of temperature. * Reinforced concrete has even invaded the realm in which stone masonry has been considered from ancient times the best building ma- terial and is now strongly competing with it in the construction of arch bridges both because it is cheaper and also better. Stone arch bridges have been built for many hundreds of years. Some of them have been built by men who probably had no knowledge of the theoretical me- chanical principles now used in designing such arches. And yet these men constructed arches of long span which had comparatively little rise. But since the stone arch depends purely on compressive stresses the design has very definite limitations. It is almost invariably found that the dead weight of a stone arch is several times the maximum live load may be safely placed on it and that even a portion of this load if placed near one end of the arch, may test it more severely than the full load uniformly distributed. The ability of a reinforced concrete arch to' withstand transverse stresses furnishes a large element of safety which is wholly unobtainable with plain stone masonry and actually permits dimensions and proportions which would be unsafe in a stone arch. Although a reinforced concrete arch is usually designed so that the "line of pressure" for full loading will pass nearly through the center of the arch which means that every portion of the arch is under compression, yet the arch will not necessarily fail if, for an eccentric loading, the line of pressures should pass entirely outside of the arch ring. In such a case, its stability would depend on the transverse strength of the arch section. A plain stone arch with the same dimen- sions and loaded in the same way would necessarily fail. Reinforced concrete is superior for such a purpose. AMERICAN STEEL & WIRE CO. 15 In dealing further with the uses and properties of rein- forced concrete, we reprint, by permission, Chapter I, from "Rein- forced Concrete," by Buel & Hill: CHAPTER I. — ECONOMIC USE AND PROPERTIES OF REIN- FORCED CONCRETE. Concrete alone, considered as a building material, is nothing more nor less than a kind of masonry. The distinguishing features between rubble masonry and concrete are really confined to the methods of mixing and placing the materials. The results obtained with rubble masonry made of very small stone and with concrete made of large stone would be practically identical . The old Roman concrete was made with large stones, and may be classified either with rubble or concrete masonry. The value of either rubble or concrete as a ma- terial for construction depends largely on the quality of the cement used and the care exercised in the mixing and placing. Examples of masonry structures composed of large stones reinforced or tied to- gether with iron rods and bars are found in the works of all periods, but usually only in connection with cut-stone masonry. The cost of such reinforcement was very great compared with the additional strength secured, and with rubble masonry the mechanical difficulties involved and the comparative cost render it impracticable. Reinforced Concrete.. — With the advent of modern concrete the facilities with which reinforcing rods or bars of metal may be em- bedded anywhere in the mass of the masonry was soon seen and taken advantage of. The compressive resistance of concrete is about ten times its tensile resistance, while steel has about the same strength in tension as in compression. Volume for volume steel costs about fifty times as much as concrete. For the same sectional areas steel will support in compression thirty times more load than concrete, and in tension three hundred times the load that concrete will carry. There- fore, for duty under compression only, concrete will carry a given load at six-tenths of the cost required to support it with steel. On the other hand, to support a given load by concrete in tension would cost about six times as much as to support it with steel. These eco- nomic ratios are the raison d'etre of reinforced concrete . If the vari- ous members of a structure are so designed that all of the compres- sive stresses are resisted by concrete and steel is introduced to resist the tensile stresses, each material will be serving the purpose for which it is the cheapest and best adapted and one of the principles of economic design will be fulfilled. Other important advantages secured in the combination of concrete and embedded steel are that the protection of' the metal elements from corrosion is practically perfect; that, with properly selected ingredi- ents, the fire and heat resisting qualities are very high, perhaps sur- passed by no other building material except fire-brick; and, in many 16 AMERICAN STEEL & WIRE CO. cases, that the substantial appearance of a masonry structure is ob- tained at about the cost of a more or less temporary unprotected steel structure. When intelligently reinforced with steel, concrete becomes a material suitable and economical for beams, floors, and long col- umns, tanks, reservoirs, conduits, and sewers; admirably adapted to arch construction, and often economical for dams and retaining-walls. Even in concrete that is not subjected to tension or flexure it is often desirable to introduce steel reinforcement to prevent the occurrence of cracks due to shock or settlement, or other causes. Properties of Concrete. — A knowledge of the properties of mater- ials is the first requisite for safe and economic designing of structures. The properties of reinforced concrete comprise not only those of the concrete and of the steel elements considered separately, but may be said to include those properties or characteristics of the composite mass that control the distribution of stresses between the elements of the combination of units and determine the nature of their inter- relation. Such properties as are required by the practical engineer or architect in intelligent designing are here assembled in concise form, with values assigned to them that are considered to be safe and con- servative deductions from the most recent experiments accessible. The scope and purpose of this work does not permit of an elaborate exposition of all the recent experiments nor of an exhaustive discus- sion of the deductions to be drawn therefrom. Portland-cement concretes only will be considered. Concrete made with natural slag, or Puzzolanic cements, although adapted to many uses, do not possess the qualities desirable for reinforced concrete structures, and all the experiments known to the writer, on which the theories of reinforced concrete are based, have been with Port- land-cement concretes. The object of reinforcing concrete with steel is to secure greater strength or safety, or both, than can be attained with concrete alone; and excepting a few special cases where the concrete is used principally for a filling or to add mass to the con- struction, concrete made with Portland cement will generally be found the most economical for equal strength, safety and durability. The properties of concretes vary with their age and with the pro- portions and quality of the ingredients. The values given here are for concretes made with (1) true Portland cement having a tensile strength per square inch neat, in 7 days of 450 to 650 lbs., and in 28 days of 540 to 750 lbs.; (2) silica sand, not necessarily sharp nor coarse, but absolutely clean, and preferably a mixture of fine and coarse; and (3) good, hard, screened broken stone or clean gravel. The proportions of cement to sand generally used in the mortar or matrix, and for which there are reliable experimental data, vary from 1 of cement to 1 of sand up to 1 of cement and 6 of sand; and the proportion of mortar or matrix to the aggregate (broken stone or gravel) is from 100 to 110 per cent of the voids of the latter. This method of specifying the proportions, by cement to sand in the mortar or matrix and by mortar or matrix to voids in the aggregate, AMERICAN STEEL & WIRE CO. 17 is here adopted because it is believed that the ratio of matrix to ag- gregate, where the latter is good clean material, does not affect the strength of the concrete, except in so far as sufficient matrix should be provided to fill the voids in the aggregate. Other things being equal, the strength of the conorete will be proportional to the strength of the mortar, and the maximum strength for a given matrix or mor- tar will be attained when all voids are filled . In practice this re- quires a volume of matrix about 10 per cent, in excess of the voids in the aggregate. Thus, if by mixing several sizes of broken stone or gravel, the proportion of voids to be filled is reduced from 45 per cent, or 50 per cent, down to 30 per cent., the proportion of matrix, cement and sand, to aggregate may be considerably reduced without reducing the strength of the concrete or affecting its properties. Where cement or sand are dear and stone and gravel are cheap ad- vantage may be taken of this method to reduce the cost of the con- crete very materially. The values here given are for concretes seven days, and one, three, and six months old. Those values should be used which correspond to the age at which the structure may be subject to its full load. Compressive Strength. — Concrete is more often used in compres- sion than in any other way, since it is more economical and has here- tofore been considered more reliable under compressive strains than under transverse or tensile strains. Until very recent years engineers and architects hardly gave serious consideration to the value of con- crete as a material to resist bending or tensile stresses, but at the pres- ent time comparatively few hesitate to use it in beams and similar situ- ations where it is partly subjected to tensile stress, and considerable number of eminent members of both professions have constructed works where the tensile strength of the concrete is taken advantage of. The best practice, where any tensile strains can occur, is to rein- force the section with steel. The two chief factors that determine the compressive strength of a concrete are its age and the proportion of sand to cement in the matrix. The quality of the cement, sand, and aggregate have more or less influence on the resulting concrefe, but with any good bi'and of modern high-burned Portland cement, clean sand, and clean, hard stone, substantially the same results may be secured. Factors of far greater weight are the manner and conditions of mixing and placing, and the personal equation of the operator. On this account it is extremely difficult to harmonize or draw conclu- sions from the large number of isolated tests that have been made by independent investigators under widely varying conditions and often with different objects in view. A set of experiments made at the Watertown Arsenal for Mr. George A. Kimball, Chief Engineer of the Boston Elevated R. R., in 1899, are the most homogeneous and systematic set of tests that have as yet been published, and are given in Table I. From these tests Mr. EdWin Thatcher has deduced formulas for the ultimate strength of concretes. They give results that agree with 18 AMERICAN STEEL & WIRE CO. the average of the experiments and can be entirely relied upon for con- cretes carefully made from good materials. They are as follows. The ultimate compressive strength in pounds per square inch of con- crete: 7 days old =1,800—200 1 month old =3,100 — 350 3 months old=3,820 — 460 6 months old=4,900 — 600 / volu me of sand \ \ volume of cement^ ( do. )■ ( do. ) . ( do. ) , These formulas give the results shown in Table II. Tensile Strength.— The tensile strength may be safely placed at one-tenth of the compressive strength, and the modulous of transverse rupture, f=M at about lft that of the tensile strength. Tetmajer gives the ratio as follows for Portland-cement mortars consisting of 1 of cement to 3 of sand by weight: (compres sive strength \ 8.64+1.8 log. of age in months/ Shearing Strength. — M. Mesnagen states that the shearing strength of concrete is from 1.2 to 1.3 times the tensile strength. Bauschinger gives the shearing strength of concrete four weeks old at 1.2 5 times the tensile strength, and at two years old 1.5 times the tensile strength. A paper on the "Shearing Resistance of Reinforced Concrete," by S. Zipkes, translated by Mr. Leon S. Moisseiff, in "Cement," for March, 1906, gives the average shearing strength, at the appearance of the first cracks, at 81 lbs. per square inch. At the time of rupture, he found the average to be 357 lbs. per square inch. Prof. Moersch ("Cement", July, 1893) obtained an average shearing resistance of 400 to 440 lbs. per square inch. Prof. Moersch's beams were tested at three months old, whereas Mr. Zipkes' specimens were all tested at an age of 50 days. Considering the difference in the age of the specimens, the agreement is fair. Table' I. — Showing Compressive Strength of Concrete as Determined by Tests Made at Watertown Arsenal in 1899. Mixture 1:2:4. Brand of Cement. Compressive Strength, Pounds per Square Inch. 7 Days . 1 Month. 3 Months. 6 Months. Alpha Germania 1,387 904 2,219 1,592 2,428 2,420 2,642 2,269 2,966 3,123 3,082 2,608 3,953 4,411 3,643 3,612 Average 1,525 2,440 2,944 3,904 AMERICAN STEEL & WIRE CO. Mixture 1:3:6. 19 Compress ve Strength, Pounds per Square Inch. Brand of Cement. 7 Days. 1 Month. 3 Months. 6 Months. 1,050 892 1,550 1,438 1,816 2,120 2,174 2,114 2,538 2,355 2,486 2,349 3,170 2,750 2,930 3,026 1,232 2,063 2,432 2,969 Mixture 1 6:12. Brand of Cement. Compressive Strength, Pounds per Square Inch. 7 Days. 1 Month. 3 Months. 6 Months. 594 564 759 417 1,090 1,218 987 873 1,201 1,257 963 844 1,583 1,532 815 1,323 Average 583 1,042 1,066 1,313 Table II.— Showing Ultimate Compressive Strength of Concrete as Determined by Thacher's Formulas. Mixture. Age. 7 Days. 1 Month. 3 Months. 6 Months. 1:1 :3 1,600 2,750 3,360 4,300 1 2 1,400 2,400 2,900 3,700 1 2 V? 5 1,300 2,225 2,670 3,400 1 3 6 1,200 2,050 2,440 3,100 1 3 V? 1,100 1,875 2,210 2,800 1 4 8 1,000 1,700 1,980 2,500 1 5 10 800 1,350 1,520 1,900 1 6 12 600 1,000 1,060 1,300 Table III.— Showing Modulus of Elasticity of Concrete as Deter- mined by Tests at Watertown Arsenal in 1899. Mixture 1:2:4. Modulus of Elasticity between Loads of 100 to 600. 7 Days. 1 Month. 3 Months. 6 Months. Atlas Alpha Gerraania . . Alsen 2,778,000 2,500,000 2,500,000 3,125,000 2,083,000 2,778,000 4,167,000 4,167,000 3,571,000 2,778,000 3,125,000 3,125,000 4,167,000 4,167,000 Average . . 2,592,000 2,662,000 3,070,000 3,G40,000 20 AMERICAN STEEL & WIRE CO. Mixture 1:3:6. Modulus of Elasticity between Loads of 100 to 600. Brand of Cement. 7 Days. 1 Month. 3 Months. , 6 Months. Atlas Germania . . Alsen 1,677,000 2,273,000 1,667,000 3,125,000 2,083,000 2,273,000 2,273,000 2,778,000 3,571,000 2,778,000 2,778,000 3,571,000 4,167,000 3,125,000 3,571,000 Average . . 1,869,000 2,438,000 2,976,000 3,008,000 Mixture 1 : 6 : 12. Modulus of Elasticity between Loads of 100 to 600. 7 Days. 1 Month. 3 Months. Months. Alpha Germania Alsen 1,316,000 1,667,000 961,000 1,562,000 1,136,000 1,786,000 2, 083, 000 1,562,000 1,786,000 1,923,000 1,786,000 1,786,000 1 1,376,000 1,642,000 1,820,000 Modulus of Elasticity. — It has been said that no property of ma- terials of construction is as uniform and reliable as the modulus of elasticity. This may be true of the modulus of elasticity of concrete, but the great variation in its value, as determined by the experiments heretofore published, has left the matter very much in the dark. Its value has been stated all the way from 750,000 to 5,000,000. This has been a discouraging condition for conservative constructors, and, no doubt, has greatly retarded the introduction of reinforced concrete in important works. The Watertown Arsenal tests in 1899 give values for the modulus of elasticity E of concrete as shown in Table III. Prom Table III the following formulas have been deduced, giving values very close to the averages of the experiments and sufficiently exact for all practical purposes. For concrete: 7 days old, .£=2,600,000— 700,000 ( 1 month old, .£=2,900,000—300,000 ( 3 months old, .£=3,600,000—500,000 ( G months old, £=3,600,000—600,000 ( volume of cement^ —£• do. -1), do. -2), do. -3), If the term / vol \volu volume of sand or less than zero e 1. I IS 7 ume of cement / (negative), the entire term is to be considered zero. In other words, all negative values must be considered as zero. Table IV shows the moduli of elasticity as determined by the above formulas. These values are sufficiently reliable for all ordinary purposes, and are probably as AMERICAN STEEL & WIRE CO. 21 near to the truth as any that can be deduced from the experiments at present available. A large number of carefully executed experiments will be required to determine these values with greater precision. Table IV. — Showing Moduli of Elasticity of Concrete as Determined by Formulas. Age. 7 Days. 1 Month. 3 Months. 6 Months. 1:1 1:2 1:2% 1:3 1:3% 1:4 1:5 1:6 3 4 5 6 7 8 10 12 2,600,000 2,600,000 2,250,000 1,900,000 1,550,000 1,200,000 500,000 2,900,000 2,600,000 2,450,000 2,300,000 2,150,000 2,000,000 1,700,000 1,400,000 3,600,000 3,600,000 3,350,000 3,100,000 2,850,000 2,600,000 2,100,000 1,600,000 3,600,000 3,600,000 3,600,000 3,360,000 3,300,000 3,000,000 2,400,000 1,800,000 Mr. W. H. Henby has given forty-eight determinations of the modulus of elasticity under tensile stress and eighteen under compres- sive stress, but the conditions were varied so that they can only be compared in groups of two or three tests with constant conditions, and as would naturally be expected, the results were very erratic and are not conclusive. Prof. Wm. H. Burr concludes that the same values may safely be used for the modulus of elasticity in tension as in compres- sion. The values of E are only given for loads between 100 and 600, since these limits include the practical range of safe working stresses per square inch. For purposes of computing the ultimate strength, which would be for loads from 600 to 4,000 lbs., E would have con- siderably lower values. For loads between 1,000 and 2,000 lbs. the values would be from one-half to two-thirds of those given for loads between 100 and 600 lbs. For loads over 2,000 lbs. satisfactory data are not known to the writer. Table V gives values of the modulus of elasticity for stresses up to 2,000 lbs. per square inch as determined at the Watertown Arsenal in the series of tests made for Mr. Geo. A. Kim- ball, Chief Engineer of the Boston Elevated Railroad, in 1899. These determinations show that the modulus of elasticity is very much less at stresses between 1,000 and 2,000 lbs. per square inch than between 100 and 600 and 1,000 lbs. per square inch, but they are not suffi- ciently comprehensive to form the basis of any satisfactory rule or formula for the ratio of the modulus of elasticity to the stress per square inch. 22 AMERICAN STEEL & WIRE CO. Table V. — Showing Reduction in Value of E c with Increasing Loads. Values Given are the Mean op Those for Several Experiments with Several Standard Brands of Portland Cement. Age. Concrete 1.2.4. Concrete 1.3.6. 100-600 100-1,000 1,000-2,000 100-600 100-1,000 1,000-2 000 3 mos 6 mos 2,592,000 2,662,000 3,670,000 3,646,000 2,053,000 2,444,000 3,170,000 3,567,000 1,351,000 1,462,000 2,157,000 2,581.000 1,869,000 2,438,000 2,976,000 3,608,000 1,529,000 2,135,000 2,656,000 3,503,000 1,219,000 1,805,000 1,868,000 Professors Boeck and Melan found a value of E at about 750,000 in connection with the Austrian experiments, where a number of arches were tested to destruction. In calculations of ultimate strength by formulas, assumed values of E ranging from 1,500,000 to 750,000, according to the mixture, age, and the ultimate load per square inch, would seem to agree more nearly with the average of previous experi- ments than values of E corresponding to loads much less than the ul- timate strength. Two important points to be noted in connection with this subject are that the elastic limit of concrete, so far as it has been determined, is very close to the ultimate strength, and that its stress-strain dia- gram is a curve, instead of being practically a straight line as it is with steel inside of the elastic limit . The nature of this curve cannot be determined from the limited number of determinations that have been published. Working Loads. — In Table VI are given what are considered safe working loads, in pounds per square inch, and properties for concretes in which the mortar or matrix is 1 of cement to 2 of sand and 1 of cement to 3 of sand, and in which all the voids in the aggregate are filled. According to present practice, these mixtures will about cover the range for reinforced concrete. Properties of Steel. — The following properties of steel for use in computing reinforced concrete sections, with the values assigned to them, will be used herein. These values are believed to be safe, but may be varied as conditions require, according to the Judgment of the designer: Ultimate strength, 58,000 to 66,000 lbs. per square inch. Elastic limit, 55 per cent, of the ultimate strength. Modulus of elasticity, 2 9,000,000. Working stress, factor of 4, 15,000 lbs. per square inch. Working stress, factor. of 5, 12,000 lbs. per square inch. Rate of expansion per degree Fahrenheit, 0.00000648 to 0.0000068G. Relations Between Concrete and Steel.— The character of the rela- tions that exist between the concrete and steel elements of reinforced concrete combinations depends first on the design of the section. If the AMERICAN STEEL & WIRE CO. 23 two elements act independently in resisting the stresses, so that either the one or the other might carry all the load, it may be called a composite design. If some of the forces are resisted entirely by the steel and other forces resisted entirely by the concrete, so that if the element resisting one force failed the entire section would fail, it may be called a combination design. If the disposition of the steel and the concrete in the section is such that the two elements act as a single unit, all stresses being divided between the concrete and the steel, where the latter occurs, and that the entire omission of the steel would only result in reducing the strength of the section, it may be called a true monolithic design. While many composite designs have been loosely classed with "con- crete-steel," they really have little in common with the combination and monolithic designs. Since the concrete and the steel are inde- pendent of each other, and either one may carry all the load, it is clear that each element should be calculated independently and like an all- concrete or an all-steel section, as the case may be. This is not to Table VI. — Showing -Safe Working Stresses for Concrete. Mixture. 1 to 2 Matrix. 1 to 3 Matrix. Age. 1 Month 6 Months. 1 Month. 6 Months- Safety factor .... Compression, lbs.*. f= M 6 400 40 64 50 5 SOO 50 80 62 6 600 60 96 75 5 700 70 112 87 5 340 35 56 44 5 400 40 64 50 5 500 50 80 62 5 600 60 S Shearing 75 E 2,600,000 3,600,000 2,300,000 3,360,000 Rate of expansion ) (Clark) 0000079S per degree Fah- >• (Rae and Dougherty) 0000065S for 1 : 3 : S concrete renheit ) . (Rae and Dougherty) 00000S61 for 1 : 2 mortar A or e s S te°eI metaTic I ( Bauschinger) 570 to 640 pounds per square inch surface, ultimate j (Hatt ) 636 to 7S6 pounds per square inch Safe working adhesion 60 to 100 pounds per square inch * These values for compression are intended for use with the straight-line for- mulas only. For the formulas of the parbolic type they should be reduced, as the latter give larger moments of resistance (Mo ) than the straight-line formulas for the same value of compression in the extreme fibers (f c ') . Note. — Prof. Hatt also found that the friction of smooth round rods embedded in concrete after they started to slip was from SO per cent, to 70 per cent, of the adhesion. For concrete not reinforced with steel, use two-thirds the values given in the tables for tension and f=M^- S. 24 AMERICAN STEEL & WIRE CO. imply that the concrete may not stiffen the steel and prevent it from buckling, but as they do not act together as a combination or unit, and as the steel does not reinforce the concrete, except in the manner that any additional and independent section may reinforce another, de- signs of this type should scarcely be classed with concrete steel or re- inforced concrete. Combination designs include concrete-steel beams after the con- crete on the tension side has been strained beyond the point of rupture, which will occur in a well-designed beam long before the ultimate strength of the beam is reached. Concrete beams reinforced with steel, under loads that produce maximum tensile stresses in the con- crete less than the ultimate strength, act as a single unit and may be classed as monolithic. The most important characteristics or properties required to deter- mine the distribution of stresses between the concrete and steel are the relations existing between the following: - u c w N N 3 a. V E Li r id COMMON LIME 1-1 IS AMERICAN ENGL'H FRENCH E » V Is in « « O U4K CO V If > « M > •a V) u CJ 'E. a (5 E -J "in V c M S Silica Si Go 21.31 21.93 18.38 20.42 25.48 22.60 26.5 28.95 21.70 1.03 1.12 Alumina Alo G 3 6.89 5.98 1 f 4.76 10.30 8.90 2.5 11.40 3.19 1 f 0.68 Iron Oxide Fe2 Og 2.53 2.35 M5.20^ 3.40 7.44 5.30 1.5 0.54 0.66 M Calcium Oxide Ca O 62.89 62.92 35.84 46.64 44.54 52.69 63.0 50.29 60.70 97 02 58.51 Magnesian Oxide Mg O 2.64 1.10 14.02 12.00 2.92 1.15 1.0 2.96 0.85 0.68 39.69 Sulphuric Acid S O3 1.34 1 54 0.93 2.57 2.61 3.25 0.5 1.37 0.60 Loss on Ignition 1.39 2.91 3.73 6.75 3.68 6.11 5.0 3.39 12.20 Other constituents 0.75 11.46 3.74 1.46 0.30 0.10 » W. F. Hillebrand, Society of Chemical Industry, 1902, Vol. XXI. !W. F. Hillebrand, Journal American Chemical Society, 1903, 25, 1180. • Clifford Richardson, Brickbuildir. 1897, p. 229. «Staneer & Blount, Mineral Industry, Vol. V., p. 69. ECandlot, Ciments et Chaux Hydrauliques, 1898, p. 174. e Le Chatelier, Annales des Mines, September and October, 1893, p. 36. 'Report of the Board of U. S. Army Engineers on Steel Portland Cement, 1900, p. 52. 8 Candlot, Ciments et Chaux Hydrauliques, 1898. p. 24. 9 Rockland Rockport Lime Co. 10 Western Lime and Cement Co. PORTLAND CEMENT. Portland cement is defined by Mr. Edwin C. Eckel of the TJ. S. Geological Survey as follows: "By the term Portland cement is to be understood the material obtained by finely pulverizing clinker produced by burning to semi-fusion an intimate artificial mixture of finely ground calcareous and argillaceous materials, this mixture consisting approxi- mately of 3 parts of lime carbonate to 1 part of silica, alumina and iron oxide." The definition is often further limited by specifying that the finish- ed product must contain at least 1.7 times as much lime, by weight, as of silica, alumina, and iron oxide together. The only surely distinguishing test of Portland cement is its chem- ical analysis and its specific gravity. (See pp. 64 and 65.) In the field it may often be recognized by its cold bluish gray color (see p. 113), although the color of Puzzolan and of some Natural cement is so similar that this is by no means a positive indication. The term Natural Portland Cement arose from the discovery in Boulogne-sur-Mer, France, as early as 1846, of a natural rock of suita- ble composition for Portland cement. A similar discovery in Pennsyl- vania gave rise to the same term in America, but the manufacturers 50 AMERICAN STEEL & WIRE CO. soon found it necessary to add to the cement rock a small percentage of purer limestone. Since the chemical composition of Portland cement, as defined above, is substantially uniform regardless of the materials from which it is made, in the United States the terms "natural" and "artificial" are meaningless. In France, cements intermediate between Roman and Portland are called "natural Portlands."* Sand Cement.: Sand or silica cement is a mechanical mixture of Portland cement with a pure, clean sand very finely ground together in a tube mill or similar machine. For the best grades the proportions of cement to sand are 1 : 1, although as lean a mixture as 1 : 6 has been made to compete with Natural cements. The coarser particles in any Portland cement have little cementitious value, hence if a portion of the cement is replaced by inert matter and the whole ground extremely fine, its advocates maintain that the product is scarcely inferior to the un- adulterated article. As made in the United States, the mixture is ground so fine that 95 per cent of it will pass through a sieve having 200 meshes to the linear inch, and all of the 5 per cent residuum is said to be sand. In other words, all of the cement passes a No 200 sieve. NATURAL CEMENT. Natural cement is "made by calcining natural rock at a heat below incipient fusion, and grinding the product to powder."* Natural cement contains a larger proportion of clay than hydraulic lime, and is consequently more strongly hydraulic. Its composition is extremely variable on account of the difference in the rock used in manufacture. Natural cements in the United States in numerous instances bear the names of localities where first manufactured. For example, Rosen- dale cement, a term heard in New York and New England more fre- quently than Natural cement, was originally manufactured in Rosen- dale, Ulster County, N. Y. Louisville cement first came from Louisville, Ky. The James River, Milwaukee, Utica, and Akron are other Natural cements named for localities. The United States produces a few brands of "Improved Natural Hydraulic Cement," intermediate in quality between Natural and Port- land, by mixing inferior Portland cement with Natural cement clinker. In England the best known Natural cement is called Roman cement. Occasionally one hears the term Parker's cement, so called from the name of the discoverer in England. LE CHATELIER'S CLASSIFICATION OF NATURAL CEMENTS. In France there are several classes of natural cement. Mr. H. Le Chateliert classifies Natural Cements as those obtained "by the heating of limestone less rich in lime than the limestone for hydraulic lime. They may be divided into three classes: *Candlot's Ciments et Chaux Hydrauliques, 1898, p. 164. •Professional Papers, No. 28, U. S. Army Engineers, p. 33. tProcedes d'Essai des Materiaux Hydrauliques, Annales des Mines, 1893. AMERICAN STEEL & WIRE CO. 51 "Quick-setting cements, such as Vassy and Roman (Ciments a prise rapide, Vassy, romain); "Slow-setting cements (Ciments a prise demi-lente) ; "Grappiers cement (Ciments de grappiers). "Vassy Cements are obtained by the heating of limestone contain- ing much clay, at a very low temperature, just sufficient to decar- bonate the lime. They are characterized by a very rapid set, followed afterwards by an extremely slow hardening, much slower than that of Portland cements." "They differ from Portland cements by containing a much higher percentage of sulphuric acid, which appears to be one of their essen- tial elements, and a much lower percentage of lime. "Slow Setting Cements, by the high temperature of calcination, approach Portland cements, but the natural limestones never possess the homogeneity of artificial mixtures, so that it Is impossible to avoid in these cements the presence of a large quantity of free lime." The composition of these products varies from that of the Vassy cements to that of the real Portlands. "Grappiers Cements are obtained by the grinding of particles which have escaped disintegration in the manufacture of hydraulic limes. These grappiers are a mixture of four distinct materials, two of which, completely inert, are unburned limestone and the clinkers formed by contact with the siliceous walls of furnaces, and two of which, strongly hydraulic, are unslacked lime and true slow-setting cement. It is nec- essary that the latter should predominate in the grappiers for their grinding to give a useful product. The grappier of cement is obtained regularly only by the heating of a limestone but slightly aluminous and containing about three equivalents of carbonate of lime for one of silica; its production necessitates a heating at high temperature. "These grappiers cements are even more apt to contain free lime than the Natural cements of slow set which are obtained by the heating of limestone containing much more alumina. Because of their con- stitution, also, the grappiers cements may vary greatly in composition since they are produced by the grinding of a mixture of grains of cement and of various inert materials. The cement grains have very nearly the composition of tricalcium silicate (Si0 2 3 CaO)." PUZZOLAN OR SLAG CEMENT. Puzzolan cement is the product resulting from mixing and grind- ing together in definite proportions slaked lime .and granulated blast furnace slag or natural puzzolanic matter (such as puzzolan, santorin earth, or trass obtained from volcanic tufa). The ancient Roman cements belonged to the class of Puzzolans. They were made by mechanically mixing slaked lime with natural puzzolana formed from the fusion of natural rock found in the volcanic regions of Italy. In Germany, trass, a volcanic product related to Puzzolan, has been used with lime in the manufacture of cements. 52 AMERICAN STEEL & WIRE CO. Blast furnace slag is essentially an artificial puzzolana, formed by the combustion in a blast furnace, and the puzzolan or slag cements of the United States are ground mixtures of granulated blast furnace slag, of special composition, and slaked lime. A Board of Engineers officers, U. S. A., presented in 1901 the fol- lowing conclusion, * based, undoubtedly, on the exhaustive studies upon the subject made by a previous Board-t- having the same chairman, Major W. L. Marshall: This term (slag or Puzzolan cement) is applied to cement made by intimately mixing by grinding together granulated blast-furnace slag of a certain quality and slaked lime, without calcination subsequent to t!>.e mixing. This is the only cement of the Puzzolan class to be found in our markets (often branded Portland), and as true Portland cement is now made having slag for its hydraulic base, the term "slag cement" should be dropped and the generic term Puzzolan be used in advertise- ments and specifications for such cements. Puzzolan cement made from slag is characterized physically by its light lilac color; the absence of grit attending fine grinding and the extreme subdivision of its slaked lime element; its low specific gravity (2.G to 2.8) compared with Portland (3 to 3.5); and by the intense bluish green color in the fresh fracture after long submersion in water, due to the presence of sulphides, which color fades after exposure to dry air The oxidation of sulphides in dry air is destructive of Puzzolan cement mortars and concretes so exposed. Puzzolan- is usually very finely ground, and when not treated with soda sets more slowly than Portland. It stands storage well, but cements treated with soda to quicken setting become again very slow setting, from the carboniza- tion of the soda (as well as the lime) element after long storage. Puzzolan cement properly made contains no free or anhydrous lime, does not warp or swell, but is liable to fail from cracking and shrinkage (at the surface only) in dry air. Mortars and concretes made from Puzzolan approximate in tensile strength similar mixtures of Portland cement, but their resistance to crushing is less, the ratio of crushing to tensile strength being about C to 7 to 1 for Puzzolan, and 9 to 11 to 1 for Portland. On account of its extreme fine grinding Puzzolan often gives nearly as great tensile strength in 3 to 1 mixtures as neat. Puzzolan permanently assimilates but little water compared with Portland, its lime being already hydrated. It should be used in com- paratively dry mixtures well rammed, but while requiring little water for chemical reactions, it requires for permanency in the air constant or continuous moisture. Puzzolanic material has been suggested by Dr. Michaelis, of Ger- many, and Mr. R. Feret, of France (see Chapter XVIII), as a valuable addition to Portland cement designed for use in sea water. ♦Professional Papers No. 28, p. 28. tReport of the Board of U. S. Army Engineers on Steel Portland Cement, 1900, p. 52. AMERICAN STEEL & WIRE CO. 53 HYDRAULIC LIME. The hydraulic properties of a lime, — its ability to harden under water, — are due to the presence of clay, or, more correctly, to the silica contained in the clay. Hydraulic lime is still used to quite an extent in Europe, especially in Prance, as a substitute for hydraulic cement. The celebrated lime-of-Teil of France is a hydraulic lime. Mr. Edwin C. Eckel states * that theoretically the proper composi- tion for a hydraulic limestone should be calcium carbonate 80.8% silica 13.2%. The hydraulic limestones in actual use, however, usually carry a much higher silica percentage, reaching at times to 25%, while alumina and iron are commonly present in quantities which may be as high as 6%. The lime content of the limestones commonly used varies from 55% to 65%." Although the chemical composition of hydraulic lime is similar to Portland cement, its specific gravity is much lower, lying between 2.5 and 2.8.-J- In the manufacture of hydraulic lime the limestone of the required composition is burned, generally in continuous kilns, and then sufficient water is added to slake the free lime produced so as to form a powder without crushing. COMMON LIME. The commercial lime of the United States is "quicklime," which is chiefly calcium oxide (CaO). Lime is now manufactured by a continuous process. Limestone of a rather soft; texture, so as to be as free as possible from silica, iron and alumina, is charged into the top of the kiln which may be, say, 40 ft. high by 10 ft. in diameter. The fuel is introduced into combustion chambers near the foot of the shaft, and the finished product is drawn out from time to time through another opening in the bottom of the shaft. The temperature of calcination may range from 1400° Pahr. (760° Cent.) to, at times, 2,000° Fahr. (1,090° Cent.). The product (see analysis, p. 47), in ordinary lime of the best quality, is nearly pure calcium oxide (CaO). Upon the addition of water the lime slakes, forming calcium hydrate (CaH 2 2 ), and, with the continued addition of water increases in bulk to twice or three times the original loose and dry volume of the lump lime as measured in the cask. In this plas- tic condition it is termed by plasterers "putty" or "paste." The setting of lime mortar is the result of three distinct processes which, however, may all go on more or less simultaneously. First, it dries out and becomes firm. Second, during this operation, the calcic hydrate, which is in solution in the water of which the mortar is made, crystalizes and binds the mass together. Hydrate of lime is soluble in 831 parts of water at 78° Fahr; in 759 parts at 32° and in 1136 parts at 140°. Third, as the per cent, of water in the mortar is reduced and reaches five per cent., carbonic acid begins to be absorbed from the *American Gtohsist, March, 1902, p. 152. fCandlot s Ciments et Chaux Hydraulique, 1898, p 26. 54 AMERICAN STEEL & WIRE CO. atmosphere. If the mortar contains more than five per cent, this ab- sorption does not go on. While the mortar contains as much as 0.7 per cent, the absorption continues. The resulting carbonate probably unites with the hydrate of lime to form a sub-carbonate, which causes the mortar to attain a harder set, and this may finally be converted to carbonate. The mere drying out of mortar, our tests have shown, is sufficient to enable it to resist the pressure of masonry, while further hardening furnishes the necessary bond.* Magnesian Limes evolve less heat when slaking, expand less, and set more rapidly than pure lime. A typical analysis is given an page 47. Hydrated Lime is a powdered slaked lime (calcium hydrate). It is manufactured by treating finely ground common lump lime with water of a certain temperature, and then cooling and screening it through a very fine screen. ♦The author's are indebted to Mr. Clifford Richardson for this paragraph. AMERICAN STEEL & WIRE CO. 55 FINISHING SURFACES OF REINFORCED CONCRETE. Objections are often heard as to the unsightly appearance of con- crete buildings when finished. With a little care concrete structures may be made as beautiful to the eye as buildings built of any other ma- terial. The following chapter, XVII, reprinted from Buel & Hill's volume, "Reinforced Concrete," will be found most interesting on this subject, dealing with the numerous finishes which may be applied at very little cost. CHAPTER XVII.— FACING AND FINISHING EXPOSED CONCRETE SURFACES. The difficulty of securing an even-grained surface of uniform color on concrete work is one of the most annoying which builders of such work have to overcome. Concrete work is subject to various sorts of surface imperfection, but the two most common imperfections are roughness or irregular surface texture and variability of color or. dis- coloration. Either of these imperfections is capable of disfiguring an otherwise sightly structure, and the task of avoiding them is one which warrants serious attention from those undertaking work in re- inforced concrete. Unfortunately practice has not settled upon a solu- tion of the problem, hence its consideration here is rather a record of experience than a set of instructions which can be followed with the certainty that successful results will ensue. Causes of Roughness and Discoloration. — There are several con- ditions which may result in a concrete surface of uneven texture and with mechanical roughnesses, such as projections, bulges, ridges, pits, bubble-holes, and scales. One of these is imperfections in the molds. The use of rough lagging of uneven thickness and with open cracks and allowing the forms to become distorted and warped are certain to leave their impress upon the plastic concrete in the form of ridges, tongues, and bulges. Failure to pack the concrete filling tightly and evenly against the mold will result in rough places. Lack of homoge- neity in the concrete is another prolific cause of variation in the sur- face texture of concrete work. This lack of homogeneity may result from failure to mix the concrete materials thoroughly and evenly in the first place, or the segregation of the coarse and fine parts of the mixture during its deposition and ramming into place. In both cases the result is a material of alternate coarse and fine texture. Dirt or cement adhering to the molds will leave pits in the concrete surface, and the pulling away of the concrete in spots when it adheres to the molds when they are removed will cause similar roughness. Variations in the color of concrete surfaces probably result from a variety of causes. Some of these are obvious and others are difficult to determine with any exactness. Roughness or uneven surface tex- ture is a common cause of variation in color, since the alternate rough 56 AMERICAN STEEL & WIRE CO. and smooth parts weather differently and collect and hold dirt and soot in different degrees. Another cause of variation in color is the use of different cements in adjacent parts of the surface work. No two cements are of exactly the same shade of color, and the concrete made of them partakes of this variation. In a similar manner sand of different shades of color or of different degrees of cleanliness will cause a cloudy and streaky appearance in concrete . Dirt adhering to the molds will frequently stain the adjacent concrete surface. Even when the smoothness of the surface is satisfactory, however, and when there is no criticism possible as to the kind and quality of the aggregate's, their deposition and the cleanliness with which the work is done, concrete surfaces frequently vary in color and have a cloudy light and dark appearance. In many cases there seems to be good reason for attributing this to the leaching out of lime, com- pounds and their deposition in the form of an efflorescence on the con- crete surface. The extent of this efflorescence varies; at times the deposit is so thin as merely to give a lighter shade to the places where it appears, but it will often form an encrustation of considerable body * and thickness which may be readily scraped of as a white or yellowish- white powder. The nature of this discoloration and the preventive and remedial treatments which have been practiced in its cure are dis- cussed more fully in a succeeding paragraph. Construction of Forms. — Very slight imperfections in the face of the forms against which the concrete is molded are sufficient to leave an unsightly impression on the plastic mixture when it hardens. Even the grain of smoothly dressed timber will show on the surface of con- crete which has been deposited with a mortar facing. It is very diffi- cult to construct forms so that they will not leave slight impressions of this character, and it is generally better not to attempt the task in any but exceptional instances. In these a straight-grained, smoothly dressed timber, with its pores filled with soap or paraffine well rubbed in, or a rougher timber covered with sheet metal, can be used. Gen- erally speaking, all has been done that is practicable so far as the forms are concerned when the face-lagging is kept true to surface and has close-fitting joints. Grain-marks and similar minor impressions of the forms can usually be eliminated by rubbing the surface or float- ing it with grout, at less cost, than by attempting to perfect the molds beyond a reasonable measure. In fact many engineers experienced in concrete work prefer not to attempt to secure particularly perfect finish in the forms, but to dress the entire surface by some style of tooling or rubbing process after the forms have been removed. The most apparent imperfection in concrete surfaces is usually the joint- marks of the lagging-boards. These may be due either to slight differ- ences in the thickness of adjoining boards or to open joints. The rsmedy for the first cause is obvious, but it is not so easy to insure AMERICAN STEEL & WIRE CO. 57 smooth, tight joints and keep them smooth and tight when the boards swell from the moisture absorbed from the wet concrete. One of the most successful forms of joint is that shown by the sketch Fig. 78. In this construction tlje wedge edge presses into the edge of the adjoining board without distorting or bulging the lagging. Pointing the joints with hard soap or putty, packing them with oakum and covering them with pasted strips of cloth, are other means which have been practiced for preventing joint-marks on the concrete. A method of eliminating grain-marks, which was used with success in con- _ „ structing piers of the Prazer River Bridge in Brit- F1G.7B. ish Columbia, consisted in covering the tightly laid matched lagging with gloss oil and then blowing sand into the oil with hand-bellows. Mortar or Grout Facing., — One of the most frequently employed means for securing a smooth surface finish on concrete is to use a mortar or grout facing. This facing differs from plastering in being laid on as the concrete is deposited, thus forming a single piece with it. The thickness of mortar facing employed in practice varies from y 2 in. to 3 ins., but the usual practice is to make it 1 in. or l%ins. thick. A facing as thick as 3 ins. is rather unnecessary waste of mortar, while one which is much less than 1 in. thick is likely to be pierced by the stones in the concrete unless great care is taken in ram- ming the concrete filling behind the mortar facing. A mortar or grout facing shows' the impress of small roughnesses on tne mold more readily than does concrete, and particular care is necessary to secure a smooth surface in the mold when the mortar facing is adopted. The composition Of the facing mortar is usually specified as 1 part of Port- land cement to 2 or 3 parts of sand. These ingredients are mixed rather wet, since the paste must completely fill the facing-mold, but care must be had not to have so thin a paste that the stones from the concrete behind will be pushed through it during the subsequent filling and ramming. The following method of placing mortar facing is practiced by the Illinois Central R. R. and has gained wide adoption during the last few years. A sheet-iron plate 6 or 8 ins. wide and about 6 ft. long has riveted across it on one side 1 V2 -in. angles spaced about 2 ft. apart. One edge of this plate is provided with handles. This device is employed as a mold for the facing and is operated in the following manner: The plate is set up against the face of the form with its angle-ribs close against the timber and its handles upward. In this position of the plate there is between it and the form an open slot lVz ins. wide. This slot is filled with mortar which is tamped thoroughly, and immediately afterwards the concrete backing is de- posited behind the plate. When this has been done the plate is with- drawn by the handles and the backing and facing are rammed together to a close bond. The mortar facing is mixed in small batches as it is needed, and no delay is permitted in placing the concrete backing, the 58 AMERICAN STEEL & WIRE CO. essential principle and purpose of the method being to secure as nearly as is possible the simultaneous construction of the backing of concrete and its facing of mortar. Fig. 79 shows an excellent form of surface mold of the type just described. By varying the size of the angle-ribs any desired thickness of facing can be constructed, and the flare of the top edge facilitates the placing of the mortar, which is usually done with shovels. . In lieu of a steel plate, use is sometimes made of a board provided with furring-strips on one side. This is a more unwieldly device than the one illustrated, and it is objectionable because of the large crevice left upon withdrawal into which the mortar facing is likely to slough and which is less easily closed and bonded by the final ramming. In constructing mortar facing with either iron or board molds perfect success is secured only at the expense of great care. The mortar must be mixed in small batches and only as needed, and it must be thoroughly rammed and churned into the facing-mold. The concrete backing must be deposited behind the mold without delay and firmly rammed against it, and finally the ramming together of the facing and backing must be thorough. The following method of applying grout facing was employed with success in constructing the Atlantic Avenue subway for the Long Island R. R. in Brooklyn, N. Y. The concrete was deposited in 6-in. or 8-in. layers, and after ramming the concrete at the face was pushed back from the form about 1 in. with an ordinary gardener's spade and a thick grout of 1 part cement and 2 parts sand was poured into the space. The forms used were tongued and grooved yellow pine painted with paraffine paint. In this work a good surface was invari- ably secured when the men did their work faithfully, but any care- lessness on their part evidenced itself in a rough spot when the forms were removed. As an indication of the susceptibility of mortar facing in taking impressions from the forms, it may be noted that even with the dressed and paraffined lagging the grain of the wood was shown perfectly on the mortar facing. Finishing Mortar Facing. — When mortar or grout facing is em- ployed as described in the preceding paragraphs the slightest imper- fections in the grain of smoothly dressed wood is clearly impressed on the plastic material. There will also be occasional rough spots, pit- tings, or bubble-holes even with the most careful construction. To get rid of these some method of surface finishing must be resorted to. A number of methods have been practiced. In recent concrete culvert work on the New York Central & Hudson River R. R. an excellent surface finish was obtained by the following procedure: The forms of 2-in. dressed and matched pine, after being put in place, were painted with a coat of thin soft soap, then as the layers of concrete were brought up the face was drawn back with a square-pointed shovel, the edges of which had been hammered flat. Mortar in the proportion of 1 part cement to 2 parts sand, mixed rather wet, was then poured in along the form and the layer rammed against it. Hard AMERICAN STEEL & WIRE CO. 59 soap was used to fill openings left by joints of the lagging. When the forms were removed and while the concrete was yet "green," the sur- face was carefully rubbed with a circular motion, with pieces of white firebrick or briquettes of 1 cement to 1 sand, made in molds about the size of a building brick, handles being pressed in while soft. The surface was then dampened and painted with a coat of grout of 1 cement to 1 sifted sand, and this was closely followed by a final rub- bing with a circular movement, using a wooden float. All edges were rounded with a Crafts edger, or with wood fillet, and the coping joints were struck with Crafts jointer. In the specifications for concrete presented by the special com- mittee of the Engineering and Maintenance of Way Association the following requirement for finishing was adopted: After the forms are removed, any small cavities or openings in the concrete shall be neatly filled with mortar if necessary. Any ridges due to cracks or joints in the lumber shall be rubbed down; the entire face shall then be washed with a thin grout Qf the consistency of whitewash, mixed in the proportion of 1 part of cement to 2 parts of sand. The wash should be applied with a brush. In the extensive concrete construction of the Aurora, Elgin & Chicago R. R. the exposed surfaces were all finished according to the following specifications: All walls when finished must present a smooth, uniform surface of cement mortar, and all disfigurements must be effaced, and if there are any open, porus places, they must be neatly filled with mortar of 1 cement and 2 sand, well rubbed in, which finishing must be done immediately upon the removal of the forms. Compensa- tion for all labor and material required in such finishing, including the mortar facing when required, with the finishing of bridge seats and other parts, is included in the price per cubic yard for concrete work. Mr. Edwin Thacher, in his general specifications for concrete-steel requires the following surface finish: For plain flat surfaces, the concrete may be rammed directly against -the molds, and, after the molds have been removed, all exposed sur- faces shall be floated to a smooth finish with semi-liquid mortar, com- posed of 1 part cement and 2 parts of fine, sharp sand, care being taken that no body of mortar is left on the face, sufficient only being used to fill the pores and give a smooth finish. A very effective finish is obtained by etching the mortar facing with acid. The method consists of using a facing mortar composed of Portland cement and finely crushed stone, the kind of stone depending upon the appearance desired. Thus any shade of red or gray granite, sandstone, etc., can be obtained, and special effects can be obtained by the use Qf sand, pigments, etc., in the mixture. This mortar is composed of about 1 part Portland cement to 2 or 3 parts of the finely crushed stone. The exposed surfaces are then treated by chemical or mechanical means to remove the cement matrix at the face, leaving 60 AMERICAN STEEL & WIRE CO. the granular particles of stone partly exposed. In general this is done by washing the surface with a weak acid solution, then with clean water, and finally with an alkiline solution' to neutralize any effects of the acid. In the finished work it is difficult to detect that the material is not natural stone, except by close inspection. The stone is crushed to pass through a sieve of 10 to 30 meshes per square inch according to the character of finish desired, and enough water is used to make a soft plastic mixture. Plastering. — Plastering as a method of finishing concrete surfaces deserve mention for the purpose alone of calling a warning against its adoption. It is practically impossible to apply mortar in thin layers to a concrete surface and make it adhere for any length of time, and when it once begins to scale off the result is a surface many times worse in looks than the unfinished concrete that it was intended to render more sightly. Pebble Dash Facing. — An effective surface finish for certain classes of concrete work can be secured by using large rounded pebbles in place of the usual aggregate for the surface layer of concrete, and then, while the concrete is soft, removing the mortar between the pebbles by wire brushing until approximately half the pebbles are exposed. The following specification for this style of facing was employed in constructing a small concrete road-bridge in the National Park at Washington, D. C. : The concrete, which will be in the exterior faces of the bridge and the parapet walls for a thickness of 18 ins., will be made of gravel and rounded stone varying in the concrete below the belting course between 1 % and 2 ins. in their smallest diameters. This gravel will be mixed in the concrete as aggregate instead of broken stone. The mixture will consist of 1 part Portland cement, 2 parts sand, and 5 parts of aggregate. The parapet walls will be made in a similar manner, with the aggregate composed of gravel not exceeding 1 in. in its smallest diameter. When the forms are removed the cement and sand must be brushed from around the face of the gravel with steel brushes, leaving approximately half of the gravel exposed. In this work it was found by test that at the age of 12 hours the concrete was not sufficiently set to hold the pebbles from being torn out by the brushing, and that at the age of 3G hours it was too hard to permit the brushing, to remove a sufficient depth of mortar without undue labor. At 24 hours' age the brushing proved most successful. Tooled Surfaces. — A method of finishing concrete surfaces which is preferred by many experienced engineers is to dress the concrete after it has hardened by means of hammers or pointed chisels. The process is exactly analogous to stone dressing, and any of the forms of finish employed for cut stone can be employed equally well for concrete. In connection with tooled surfaces it is common to mold the concrete to represent ashlar masonry by means of horizontal and vertical V-shaped depressions formed as shown by Fig. 80. This style of finish has been extensively employed by Mr. E. L. Ransome, who gives the following directions for securing it: In imitating rough- AMERICAN STEEL &■ WIRE CO. 61 dressed work the mold is removed from the concrete while it is yet tender, and with small light picks the face is picked over with great rapidity, an ordinary workman finishing about 1,000 square feet per day. For imitations of finer-tooled work the concrete should be left to harden longer before being spalled or cut, and the work should be done with a chisel. Most natural stone and especially granite makes excellent material for the face, but ordinary gravel will do. Whatever is used, let it be uniform in color and of even grade. When a very fine and close imitation of a natural stone is required take the same stone, crush it and mix it with cement colored to correspond. The finer the stone is crushed the nearer the resemblance will be upon close inspection; but for fine work it is generally sufficient to reduce the stone to the size of buckshot or fine gravel. Masonry Facing. — A facing of masonry is often employed on rein- forced-concrete arch bridges, and is a very satisfactory solution of the problem of surface finish for such structures. Masonry facing may be of any style of stonework which is used for true masonry arches, and coursed ashlar, random rubble, and boulder masonry facings have all been employed. Exactly the same care should be exercised in selecting stones and laying them up into arch ring and wall, cornice and parapet, as if the structure were entirely of masonry. Beyond this the most important feature to be observed is close bond- ing of the masonry facing to the concrete backing. To insure this there should be a liberal use of stretchers reaching well into the back- ing, and these can be supplemented with metal cramps to the advantage of the work in many instances. For facing the arch ring the stones should be cut to true voussoir shape, and laid quite as perfectly as if they were a part of a true voussoir arch ring. The soffit of the arch ring is not stone-faced. In place of stone a brick facing may be employed. The following specifications for stone and brick facing, which were prepared by Mr. Edwin Thacher, M. Am. Soc. C. E., to control work conducted by him, give a fair idea of the requirements of high-class work of this character: Stone Facing. — If stone facing is used, the ring stones, cornices, and faces of spandrels, piers, and abutments shall be of an approved quality of stone. The stone must be of a compact, texture, free from loose seams, flaws, discolorations, or imperfections of any kind, and of such a character as will stand the action of the weather. The spandrel-walls will be backed with concrete, or rubble masonry, to the thickness required. The stone facing shall in all cases be securely bonded or clamped to the backing. All stone shall be rock-faced with the exception of cornices and string courses, which shall be sawed or bush-hammered. The ring stones shall be dressed to true radial lines, and laid in Portland cement mortar, with % in. joints. All other stones shall be dressed to true beds and vertical joints. No joint shall exceed % in. in thickness and shall be laid to break joints at least 9 ins. with the course below. All joints shall be cleaned, wet, and neatly pointed. The faces of the walls shall be laid in true lines, and co the dimensions given on plans, and the corners shall have a 62 AMERICAN STEEL & WIRE CO. chisel draft 1 in. wide carried up to the springing lines of the arch, or string course. All cornices, moldings, capitals, keystones, brackets, etc., shall be built into the woru in the proper positions and shall be of the forms and dimensions shown on plans. Brick Facing with Concrete Trimmings. — The arch rings, cornices, string courses, and quoins shall be concrete-faced as described above, the arch rings and quoins being marked and beveled to represent masonry. The piers, abutments, and spandrels shall be faced with vitrified brick, as shown on plans. The brick facing shall be plain below the springing lines of the arches, and rock-faced above these lines. All rock-faced brick shall be chipped by hand from true pitch lines. All brick-facing shall be bonded as shown on plans, at least one-fifth of the face of the wall being headers. The brick must be of the best quality of hard-burned paving brick, and must stand all tests as to durability and fitness required by the engineer in charge. The bricks must be regular in shape and practically uniform in size and color They shall be free from lime and other impurities; shall be free from checks or fire cracks, and as nearly uniform in every respect as possible; shall be burned so as to secure the maximum hardness; so annealed as to reach the ultimate degree of toughness ;and be thor- oughly vitrified so as to make a homogeneous mass. The backing shall be carried up simultaneously with the face work, and be thoroughly bonded with it. The use of boulder facing will ordinarily be limited to structures of special character, and its success will depend very largely upon the care with which the stones are selected, their size, and their arrange- ment in the structure. In constructing a boulder-faced concrete avch at Washington, D. C, the following requirements were specified for the facing: The term boulder here is meant to cover loose rock, which shall be hard, durable, and of a quality to be approved by the engineer, whose edges have become weathered or water-worn, or both, and are more or less rounded. It is the intention to obtain a decidedly rustic effect on the facing, and to that end extreme care must be taken in the selec- tion of the stones, and only mechanics who show an aptitude for this class of work shall be employed. No tool marks or fresh fractures will be allowed on the showing faces. The boulder face of such stone shall project at least 2 ins. beyond the neat lines of the bridge, and this projection shall not excee'd 15 ins., nor shall it be greater than one-half the least horizontal dimension of the stone. All joints shall be scraped and brushed clear of mortar to the depth indicated by the engineer. The mortar shall consist of 1 part Portland cement and 2 parts sand. The backs of all boulders shall be plastered with a layer of mortar as specified, at least % in. thick, immediately before ramming the concrete against them. The arch-stones shall have a depth of between 3 and 4 ft., a width of not less than IS ins.-, nor more than 3G ins.; all dimensions to be measured exclusive of the projections beyond the neat lines. The joints shall be dressed so as not to exceed 1 Vz ins. at any point for at least two-thirds their depth and two-thirds their length, and as much more as the stones will admit. Each arch-stone shall be cramped to the adjacent steel girder by means of a wrought-iron cramp made from %X%-in. bar, the cramps to reach at least 2 ins. into each boulder, to be well cemented into them, and securely cramped to the top of the girder. The outside girders shall be cramped to the adjacent girders by 10 wrought-iron cramps made from %X%-in. bar (in con- struction we used %-in., as it bent cold without fracture). AMERICAN STEEL & WIRE CO. 63 No dressing will be required on the stones used in abutments, spandrels, and wing walls of the work, but only well-shaped boulders, laid on their broadest bed, will be allowed. Dressing will be per- mitted on such stones as cannot be properly bedded without it. The parapet walls will be a continuation of the spandrel and wing walls. The boulder stone must reach entirely through the wall. Cast Concrete Slab Veneer. — In constructing the arch bridge at Soissons, France, which is described on p. 244, the faces of the arch- ribs and the spandrel facing were formed of slabs of concrete-steel molded separately and set in place like stone veneer with the remainder of the concrete forming a backing. An essentially similar construc- tion was employed in Chicago, III., in 1902, in constructing a number of recreation buildings in one of the city parks. In the last example mentioned the slabs were cast face down in wooden molds; the mode of procedure being as follows: A layer of mortar composed of 1 part cement and 2 or 3 parts of finely crushed stone was first placed in the bottom of the mold to a depth of from % in. to 1 in.; on this bed of mortar a 1-2-4, concrete, with y 2 to % in. stone, was placed to the thickness desired and care- fully rammed. After hardening, the blocks were removed from the molds and set aside to season until they were placed in the structure. The construction of the slab veneer for the Soissons Bridge was as follows: For molding the arch-rib facing a smooth level platform or pavement of concrete was constructed on an adjacent level piece of ground. This molding platform was large enough to permit the arch-ribs to be delineated to full size on its surface. To prepare the mold the platform was covered smoothly with gunny cloth held down by battens, which also served to outline the extrados and intrados of the arch-rib. Radical strips of wood were then placed to divide the mold into voussoir-like sections. A thin bed of mortar was placed on the bottom of the mold and on this was laid four reinforcing-bars, one near and parallel to each edge of the voussoir being molded, so as to intersect at the corners. Under these bars at several points wire stirrups were looped with their fine ends projecting upward. The metal was then covered with a rich concrete of fine stone laid on the mortar-bed and compacted so that the total thickness was about 2 ins. ■When hardened, the product of the mold was a set of voussoir-shaped slabs with smooth faces and edges and a rough back with a number of projecting wires. In construction these facing slabs were set in place with mortar joints and backed with concrete. For the spandrel- wall facing the slabs were cast in rectangular molds in exactly the same manner. The engineers of the Soissons Bridge remark that the use of this cast concrete veneer enabled a considerable reduction of expense for forms and assured a surface finish of pleasing appearance. Moldings and Ornamental Shapes. — The finishing of concrete struc- tures in many instances comprehends the construction of moldings and ornamental shapes for cornices, corbels, medallions, key-stones, and other architectural parts. These may either be molded in place 64 AMERICAN STEEL & WIRE CO. by suitable construction of the stationary forms or they may be cast separately in portable molds and set in place in the structure as would be cut stone. Panels of simple form or plain cornice moldings can usually be molded in place without great trouble and expense, but in constructing corbels, complicated moldings, balusters, etc., particularly where one pattern is duplicated a number of times, time and expense will usually be saved by casting them separately or in sections, and afterwards erecting the separate pieces in the structure. The casting of ornamental shapes in concrete may be accomplished either in sand-molds or in rigid molds of wood, metal, or plaster of Paris. Some very handsome work has been recently performed by sand-molding. The mode of procedure followed in making concrete castings in sand varies somewhat in practice, but it is substantially as follows: A pattern of the shape to be cast is first made in wood and to the exact size required, since no allowance for shrinkage is necessary. The pattern is then molded in sand in flasks exactly as is done in casting iron. The mixture used usually consists of cement and finely crushed stone of about the consistency of cream, and this is poured into the mold by means of a funnel and T pipe. The excess water in the mixture soaks into the sand and serves to keep the cast- ing moist during setting. Generally the casting is left in the mold for three or four days, and is then removed and the projecting fins, if any, are cut off. The cast stone may be used immediately in the work, but it is preferable to let it season and harden for a fortnight or more before using. The product of these sand-molds has an un- usually attractive surface texture. Sand-molding is particularly ad- vantageous when balusters, corbels, medallions, and intricate moldings have to be cast, but for plain cornices and facing slabs it is generally as cheap and convenient to use wooden forms. Efflorescence. — The leaching out of certain lime compounds and their deposition on the surfaces of concrete work are quite frequently the cause of the uneven color of such surfaces. In relation to this source of discoloration Mr. Clifford Richardson, Director of the New York Testing Laboratory, says: It is primarily due to variations in the amount of water in the mortar of which the cement is composed. It will be readily under- stood that when any excess of water is used, segregation of the coarse and fine particles will take place, with a resulting difference in color. When a large amount of water is used the concrete is more porous and the very considerable percentage of free lime liberated from the Portland cement in the course of setting is more readily brought to the surface at such point. . . The amount of water In a concrete, the face of which is to be exposed, should be neither too small nor too large, but such a concrete should certainly not be dry or the exposed face will be honeycombed. . . Where the greatest care is used as to the amount of water added to the mortar and to prevent its loss, and where separation of the mortar from the broken stone is carefully avoided in depositing the concrete and in ramming it, the exposed sur- face, after the removal of the molds, is fairly uniform in color. . . . A more uniform color will always be obtained when some puzzolanic material is ground in with the cement such as slag or tross. This AMERICAN STEEL & WIRE CO. 65 hydrated silicious material combines with the lime which has been liberated and prevents it washing out on the surface. . . . Exact- ness in the amount of water used in the concrete, when the elimination of the stain caused by the free lime is considered desirable, the addition of some substance - containing silica in an active form are the two " steps to be taken to produce a concrete surface which should present a uniform color and a pleasing appearance. The measures whose adoption are recommended in the quotation just made are designed to prevent the occurrence of efflorescence by adopting certain precautions in the materials and workmanship of the original construction. Their adoption, however, if it gives the success that Mr. Richardson anticipates, is obviously the way to get at the root of the trouble, but such action involves a degree of skill and watchfulness in constructing concrete work which is difficult of attain- ment under ordinary conditions of engineering construction, and which if attained will add materially to the cost of construction. They have the further objection that a special mixture of cement is required about which our information is not entirely certain. In default of preventive measures, which recommend themselves to general use, the engineer who encounters the trouble of efflorescence must overcome it by remedial measures. There are a number of these available. The most practical ones are the washing of the discolored surfaces by solution, which will remove the incrustation, or the removal of the original surface by dressing it down with hammers cr tooling or some sort. The manner of dressing down concrete surfaces to eliminate sur- face imperfections is discussed in a previous paragraph. The follow- ing account of the method of cleaning a concrete-steel bridge at Wash- ington, D. C, gives instructive data as to this mode of procedure: The bridge in question had a mortar facing and after this was com- pleted a heavy rain caused the entire north facade to become dis- colored by efflorescence. This discoloration was not uniform, but in streaks and blotches of a white color, which after weathering a short time turned into a dirty yellow. To clean the bridge trial was first made of water and wire brushes, but after a little work this method was considered impracticable owing chiefly to its cost, which was esti- mated at $2.40 per square yard. Washes of dilute hydrochloric acid, of dilute acetic acid, and of dilute oxalic acid were then tried in con- junction with ordinary scrubbing-brushes. The hydrochloric-acid wash proved the best, and the acetic-acid wash came next in efficiency. The wash finally adopted consisted of a solution of 1 part hydrochloric acid and 5 parts water. This was applied vigorously with scrubbing- brushes, water being constantly played on the . work with a hose to prevent the penetration of the acid. One house-cleaner and five labor- ers were employed on the work, which cost 60 cents per square yard. This high cost was due largely to the difficulty of cleaning the balus- trades; it was estimated that the cost of cleaning the spandrel- and wing-walls did not exceed 2 cents per square yard. The cleaning was thoroughly satisfactory. Some of the flour removed by the brushes was analyzed and found to be silicate of lime. 66 AMERICAN STEEL & WIRE CO. -Q — - c s si is'iqqzi ra en £8 .2 8 3'iqq-fu 2 '-3 So D.01 S-3 8'iqq n DO C ,. S'lqq-foioJ O O .sir, ■zz « o .jd o fc.Q riqqoi oe ^i ^ 3*- •1 =%£ ■°T3 > a -° 5~.o c 'iqq8 n UJ LjJ DC (0 o ^ ai >- — 5^ c •o .o Ex ,. E « jqq-fz o o > 5 E 3 c rt 3 c « - ? 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JUse 40% columns for gravel or mixed stone and gravel. §Use these columns for scientifically graded mixtures. AMERICAN STEEL & WIRE CO. Reprinted by permission from Taylor &= Thompson's "Concrete Plain and Reinforced'' page 131 QUANTITIES OF MATERIALS FOR ONE CUBIC YARD OF RAMMED CONCRETE. BASED ON A BARREL OF 3.8 CUBIC FEET. (See important foot-notes, also p. 225.) PROPOR- TIONS BY PARTS PROPOR- .2 Sjw III PERCENTAGES OF VOIDS IN BROKEN STONE OR GRAVEL VOLUMES 50SS* i 455f!t 40$+" 30#? 20#? C OJ ■a ej u S ca oj 1,0 V WO 3 c ca Jig -tin a B V •X3 a a m a tn a B 0J -0 a rt a en c V E T3 a in 0J c 55 c CJ E aj C_> ■a c G 5) c a CJ ■a a CO C/l V c 35 c CO t/3 en bbl. CU. ft. CU. ft. % bbl. CU. yd. CU. yd. bbl. CU . yd. CU. yd. bbl. CU. yd. CU. yd bbl. CU. yd. CU yd. bbl. CU. yd. CU. yd. 1 2 3 1 1 1 3.8 7.6 11.4 94 51 36 5.09 3.67 0.72 1.03 4.90 3.48 ■3.69 0.69 0.9S 1.14 4.73 3.30 2.51 0.67 0.93 1.07 4.33 2.93 2.22 0.61 0.83 0.94 4.02 2.65 1.98 0.57 0.75 0.81 1 5 6 1 1 1 15.2 19.0 22.8 29 25 22 1.78 1.49 1.28 1.00 1.05 1.08 1.58 1.31 1.12 0.89 0.92 0.95 7 S 9 1 1 1 26.6 30.4 34.2 20 19 18 0.9S 0.S7 0.78 0.97 0.93 0.99 10 11 12 1 1 1 38.0 41.8 45.5 17 16 15 0.71 0.65 0.60 1.00 1.01 1.01 1 1 1 IVj 2 2% 1 1 1 3.8 3.S 3.8 5.7 7.6 9.5 99 75 i 61 3.19 2.85 2.57 0.45 0.40 0.36 0.67 0.80 0.90 3.08 2.73 2.45 0.43 0.38 0.34 0.65 0.77 0.86 2.97 2.02 2.34 0.42 0.37 0.33 0.63 0.74 0.82 2.78 2.43 2.15 0.39 0.34 0.30 0.59 0.68 0.76 2.62 2.2E 1.9£ 0.37 0.32 0.28 0.55 0.64 0.70 1 IV. 3 2 2V. 1 1 1 3.S 5.7 5.7 11.4 7.6 9.5 51 93 76 2.34 2.49 2.27 0.33 0.53 0.48 0.99 0.70 O.SO 2.22 2.40 2.18 0.31 0.51 0.46 0.94 0.68 0.77 2.12 2.31 8.09 0.30 0.49 0.44 0.90 0.65 0.74 1.93 2.16 1.94 0.27 0.40 0.41 0.82 0.61 0.68 1.71 2.0E 1.8C 0.25 0.43 0.38 0.75 0.57 0.63 1% IV. 3 3% 4 1 1 1 5.7 5.7 5.7 11.4 13.3 15.2 64 55 49 2.09 1.94 1.80 0.44 0.41 0.38 0.88 0.96 1.01 3.00 1.84 1.71 0.42 0.39 0.35 0.84 0.91 0.96 1.91 1.76 1.63 0.40 0.37 0.34 0.81 0.87 0.92 1.76 1.61 1.48 0.37 0.34 0.31 0.74 0.79 0.83 l.e: 1.4! 1.3( 0.84 0.31 0.2! 0.69 0.73 0.77 1% 1V4 2 4% 5 3 1 1 1 5.7 5.7 7.6 17.1 19.0 11.4 44 40 75 1.69 1.59 1.89 0.36 0.34 0.53 1.07 1.12 0.80 1.60 1.50 1.81 0.34 0.32 0.51 1.01 1.06 0.76 1.51 1.42 1.74 0.32 0.30 0.49 0.96 1.00 0.74 1.37 1.28 1.61 0.2£ 0.2" 0.4E 0.87 0.90 0.68 1.2E 1.1- 1.51 0.2( 0.2E 0.4S 0.79 0.83 0.63 2 2 2 3V. 4 4V. 1 1 1 7.6 7.6 7.6 13.3 15.2 17.1 65 57 51 - 1.76 1.65 1.55 0.49 0.46 0.44 0.87 0.93 0.98 1.68 1.57 1.48 0.47 0.41 0.42 0.83 0.S8 0.94 1.61 1.50 1.41 0.45 0.42 0.40 0.79 0.84 0.89 1.48 1.38 1.28 0.4! 0.3! 0.3( 0.73 0.7S 0.81 1.3! 1.2 1.1! 0.3! 0.3( 10.31 0.68 0.72 0.75 2 2 2 5 5Vj S 1 1 1 7.6 7.6 7.6 19.0 20.9 22.8 47 43 40 1.47 1.39 1.32 0.41 0.39 0.37 1.03 1.08 1.11 1.39 1.31 1.25 0.39 0.37 0.35 0.98 1.01 1.06 1.32 1.25 1.18 0.37 0.35 0.33 0.93 0.97 1.00 1.20 1.13 1.06 0.3 0.3! 0.3C 0.84 0.8? 0.8E l.K 1.0 0.9 10.31 i 0.2! r 0.3- 0.77 0.80 0.83 2% 2Vj 2V. 3 3Mj 4 1 1 1 9.5 9.5 9.5 11.4 13.3 15.2 87 75 66 1.72 1.62 1.52 0.61 0.57 0.54 0.73 O.SO 0.86 1.66 1.55 1.46 0.58 0.55 0.51 0.70 0.76 0.82 1.60 1.49 1.40 0.56 0.52 0.49 0.68 0.73 0.79 1.49 1.38 1.29 0.5S 0.4! 0.4E 0.6E 0.6S 0.7S 1.41 1.2 1.1< 10.4! )0.4. )0.4! 0.59 0.64 0.67 2% 2V. 4% 5 5V/ 1 1 1 9.5 9.5 9.5 17.1 19.0 20.9 60 54 49 1.44 1.37 1.30 0.51 0.48 0.46 0.91 0.96 1.01 1.37 1.30 1.23 0.48 0.46 0.43 0.87 0.92 0.95 1.31 1.24 1.17 0.46 0.44 0.41 0.83 0.S7 0.91 1.20 1.13 1.07 0.4S 0.4C 0.3S 0.71 0.8C 0.8S 1.1 1.0 0.9 10.3! 10.3- S 0.34 0.70 0.73 0.76 2% 2% 2V- 6 6V. 7 1 1 1 9.5 9.5 9.5 22.8 24.7 26.6 46 42 40 1.24 1.18 1.13 0.44 0.42 0.40 1.05 1.0? 1.11 1.17 1.12 1.07 0.41 0.39 0.38 0.99 1.02 1.05 1.11 1.06 1.01 0.39 0.37 0.36 0.94 0.97 0.99 1.01 0.96 0.91 0.3f 0.34 0.3! 0.8E 0.88 0.9C 0.9 0.8! 0.8, S0.3J 5 0.31 0.2! 0.73 0.80 0.82 3 3 3 4 PA 5 1 1 1 11.4 11.4 11.4 15.8 17.1 19.0 76 68 61 1.42 1.34 1.28 0.60 0.57 0.54 0.80 0.85 0.90 1.36 1.28 1.22 0.57 0.54 0.52 0.77 0.81 0.86 1.30 1.23 1.17 0.55 0.52 0.49 0.73 0.78 0.82 1.21 1.13 1.07 0.51 0.48 0.4E 0.6E 0.72 0.75 1.1! 1.0. 0.9! 0.4- >0.4J 0.4! 0.63 0.06 0.70 3 3 3 5% 6 6V. 1 1 1 11.4 11.4 11.4 20.9 22.8 24.7 56 52 48 1.22 1.16 1.12 0.52 0.49 0.47 0.94 0.98 1.02 1.16 1.11 1.06 0.49 0.47 0.45 0.90 0.94 0.97 1.11 1.05 1.01 0.47 0.44 0.43 0.86 0.89 0.93 1.01 0.96 0.92 0.4? 0.41 0.39 0.78 0.81 0.84 0.9. 0.8! 0.8< 0.3! 0.3- 0.3E 0.72 0.74 0.77 3 3 3 7 7% 8 1 1 1 11.4 11.4 11.4 26.6 28.5 30.4 45 42 40 1.07 1.03 0.99 0.45 0.44 0.42 1.05 1.09 1.11 1.01 0.97 0.93 0.43 0.41 0.39 0.99 1.08 1.05 0.96 0.92 0.88 0.40 0.39 0.37 0.95 0.97 0.99 0.87 0.83 0.80 0.37 0.35 0.34 0.86 0.88 O.90 0.8C 0.7( 0.7C 0.34 0.3! 0.31 0.79 0.80 0.83 4 4 4 5 6 7 1 1 1 15.2 15.2 15.2 19.0 22.8 26.6 76 64 55 1.13 1.04 0.96 0.64 0.59 0.54 0.80 0.88 0.95 1.08 0.99 0.92 0.61 0.56 0.52 0.76 0.84 0.91 1.04 0.95 0.88 0.59 0.54 0.50 0.73 0.80 0.87 0.96 0.87 0.80 0.54 0.49 0.45 0.68 0.73 0.79 0.91 0.81 0.74 0.51 0.4C 0.42 0.63 0.68 0.73 4 4 4 8 9 10 1 1 1 15.2 15.2 15.2 30.4 34.2 :,8.0 49 44 40 0.90 0.84 0.79 0.51 0.47 0.44 1.01 1.06 1.11 0.85 0.80 0.75 0.48 0.45 0.42 0.96 1.01 1.06 0.81 0.76 0.71 0.46 0.43 0.40 0.91 0.96 1.00 0.74 0.68 0.64 0.42 0.38 0.36 0.83 0.86 0.90 0.68 0.63 0.56 0.3S 0.35 0.33 0.77 0.80 0.83 5 6 10 12 1 1 19.0 22.8 38.0 45.5 47 46 0.73 0.62 0.52 0.52 1.03 1.01 0.69 0.58 9.49 0.49 0.97 0.98 0.66 0.5B 0.16 0.47 0.93 0.94 0.60 0.50 0.42 0.42 0.84 0.84 0.55 0.46 0.39 0.39 0.77 0.78 Note —Variations in the fineness of the sand and the compacting of the concrete may affect the quantities 10$ in either direction. *Use 50$ columns for broken stone screened to uniform size. tUse 45)! columns for average conditions and for broken stone with dust screened out. lUse 40jS columns for gravel or mixed stone and gravel. SUse these columns for scientifically graded mixtures. 70 AMERICAN STEEL & WIRE CO. Reprinted by permission from Taylor & Thompson's "Concrete Plain and Reinforced" page 232 QUANTITIES OF MATERIALS FOR ONE CUBIC YARD OF RAMMED CONCRETE. BASED ON A BARREL OF 4 CUBIC FEET. (See important foot-notes, also p. 225.) PROPOR- PROPOR- Hi "3 ■ 3 i PERCENTAGES OF VOIDS IN BROKEN STONE OR GRAVEL TIONS TIONS I5Y BY PARTS VOLUMES 50#* ! m%-\ 40#t 30#§ W%% ■£ = a a C3 a a C V E u X) a re c i/5 re i> C 8" §1 -4-n £8 cj S U •a c ca en c t/5 E re ■ ■Si cd. yu. O p m cu. yd. aj S 'J bbl. a m \n cu. yd. a c/5 cu. yd. QJ 6 U bbl •a c cd in cu. yd. c tr> u. d. /4 2 1 a 8 92 2.39 0.53 0.71 2.30 0.51 0.68 8.22 0.49 0.66 2.07 0.40 0.01 1.94 0.43 0.58 1 1% sy 2 1 a 10 74 2.18 0.4S 0.81 2.09 0.46 0.77 a. 01 0.45 0.74 1.86 0.41 0.69 1.73 0.38 0.64 1 Vk 3 1 6 12 62 2.01 0.45 0.89 1.91 0.42 0.85 1.83 0.41 0.81 1.68 0.37 0.75 1.56 0.35 0.69 1 1V4 3>/ 2 1 e 14 54 1.86 0.41 0.96 1.77 0.39 0.92 1.68 0.37 0.87 1.54 0.34 0.80 1.42 0.32 0.74 1 iy 2 4 1 6 10 48 1.73 0.38 1.03 1.64 0.36 0.97 1.56 0.35 0.92 1.42 0.32 0.84 1.30 0.29 0.77 1 1% m 1 18 43 1.62 0.36 1.0S 1.53 0.34 1.02 1.45 0.32 0.97 1.31 0.29 0.87 1.20 0.27 0.80 1 1% 5 1 6 20 39 1.52 0.34 1.13 1.43 0.32 1.06 1.35 0.30 1.00 1.22 0.27 0.90 1.11 0.25 0.82 1 2 3 1 S 12 74 1.81 0.54 0.80 1.74 0.52 0.77 1,67 0.50 0.74 1.54 0.48 0.68 1.44 0.43 0.64 1 2 3% 1 S 14 64 1.69 0.50 0.88 1.61 0.48 0,83 1.54 0.46 0.80 1.42 0.42 0.74 1.31 0.39 0.68 1 2 * 1 8 16 56 1.58 0.47 0.94 1.51 0.45 0.89 1.44 0.43 0.85 1.32 0.39 0.78 1.21 0.36 0.72 1 2 iVz 1 8 18 51 1.49 0.44 0.99 1.41 0.42 0.94 1.34 0.40 0.89 1.23 0.36 0.82 1.13 0.34 0.75 1 2 5 1 8 20 46 1.40 0.42 1.04 1.33 0.39 0.98 1.26 0.37 0.93 1.15 0.34 0.85 1.05 0.31 0.78 1 2 5Vt 1 8 22 42 1.33 0.39 1.03 1.26 0.37 1.03 1.19 0.35 0.97 1.08 0.32 0.88 0.98 0.29 0.80 1 2 1 8 24 39 1.26 0.37 1.12 1.19 0.35 1.06 1.13 0.34 1.00 1.02 0.30 0.91 0.93 0.28 0.33 1 2V2 3 1 10 12 86 1.65 0.61 0.73 1.59 0.59 0.71 1.53 0.57 0.68 1.42 0.52 0.63 1.33 0.49 0.59 1 2% 3>/2 1 1!) 14 75 1.55 0.57 0.80 1.48 0.5t> 0.77 1.42 0.52 0.74 1.32 0.49 0.68 1.23 0.46 0.64 1 2V2 4 1 10 10 66 1.46 0.54 0.S7 1.39 0.51 0.83 1.33 0.49 0.79 1.23 0.46 0.73 1.14 0.42 0.68 1 2% 4% 1 10 IS 59 1.38 0.51 0.92 1.31 0.48 0.87 1.25 0.46 0.83 1.15 0.43 0.77 1.06 0.39 0.71 1 2% 5 1 10 20 54 1.31 0.48 0.97 1.24 0.46 0.92 1.18 0.44 0.87 1.08 0.40 0.80 0.99 0.3? 0.73 1 2% 5% 1 10 22 49 1.24 0.46 1.01 1.18 0.44 0.98 1.12 0.41 0.91 1.02 0.38 0.83 0.93 0.34 0.76 1 2»/ 2 6 1 10 24 45 1.18 0.44 1.05 1.12 0.41 1.00 1.06 0.39 0.94 0.96 0.36 0.85 0.88 0.8S 0.78 1 2% 0% 1 10 26 42 1.13 0.42 1.09 1.07 0.40 1.03 1.010.37 0.97 0.92 0.34 0.89 0.84 0.31 0.81 1 2% T 1 10 28 39 1.08 0.40 1.12 1.02.0.38 1.08 0.96 0.36 1.00 0.87 0.32 0.90 0.79 0.2E 0.82 1 3 4 1 12 16 75 1.35 0.60 0.80 1.30 0.58 0.77 1.25 0.56 0.74 1.15 0.51 0.68 1.08 0.4E 0.64 1 3 4% 1 12 IS 67 1.28 0.57 o.so 1.23 0.55 0.82 1.18 0.52 0.79 1.08 0.48 0.72 1.01 0.4C 0.67 1 3 8 1 12 20 60 1.22 0.54 0.90 1.16 0.52 0.86 1.11 0.49 0.82 1.02 0.45 0.76 0.94 0.4S 0.70 1 3 5% 1 12 22 55 1.16 0.52 0.95 1.11 0.49 0.90 1.06 0.47 0.86 0.97 0.43 0.79 0.89 0.4C 0.72 1 3 1 12 24 50 1.11 0.19 0.99 1.06 0.47 0.94 1.01 0.45 0.90 0.92 0.41 0.82 0.84 0.37 0.75 1 3 G'/2 1 12 26 48 1.06 0.47 1.02 1.01 0.45 0.97 0.96 0.43 0.92 0.87 0.39 0.84 0.80 0.36 0.77 1 3 r 1 12 28 44 1.02 0.45 1.06 0.97 0.43 1.01 0.920.41 0.95 0.83 0.37 0.86 0.76 0.34 0.79 1 3 T/2 1 12 30 42 0.98 0.44 1.09 0.93 0.41 1.03 0.880.39 0.98 0.79 0.35 0.88 0.73 0.32 0.81 1 3 8 1 12 32 39 0.9J 0.42 1.11 0.89 0.40 1.05 0.84 0.37 1.00 0.76 0.34 0.90 0.69 0.31 0.82 1 i 5 1 10 20 75 1.08 0.64 0.80 1.03 0.61 0.76 0.99 0.59 0.73 0.92 0.55 0.68 0.86 0.51 0.64 1 ■4 1 10 24 63 0.09 0.59 0.88 0.95 0.56 0.84 0.91 0.54 0.81 0.83 0.49 0.74 0.77 0.4( 0.68 1 1 7 1 10 28 55 0.92 0.54 0.95 0.88 0.52 0.91 0.83 0.49 0.88 0.76 0.45 0.79 0.70 0.42 0.73 1 4 S 1 10 32 48 0.80 0.51 1.02 0.81 0.48 0.98 0.77 0.46 0.91 0.70 0.42 0.83 0.64 0.38 0.76 1 1 9 1 10 36 43 0.80 0.47 1.07 0.76 0.45 1.01 0.72 0.43 0.98 0.65 0.39 0.87 0.60 0.3C 0.80 0.81 1 i 10 1 10 40 40 0.75 0.44 1.11 0.71 0.42 1.05 0.67 0.40 0.99 0.81 0.36 0.90 0.55 0.33 1 5 10 1 20 40 47 0.70 0.52 1.04 0.66 0.49 0.98 0.63 0.47 0.93 0.57 0.42 0.84 0.52 0.38 0.77 0.78 1 8 12 1 2-1 48 40 0.59 0.52 1.05 0.56 0.50 1.00 0.53 0.47 0.94 0.48 0.43 0.85 0.41 0.39 NOTE.-Variations m the fineness of (lie sand and the compacting of the concrete may allect tho quantities by the Win either direction. * "'"- 1 - 1 l "e *Use 50$ columns for broken stone screened to uniform size. fUse 45$ columns for average conditions and for broken stone with dust screened out iUse 40$ columns for gravel or mixed stone and gravel. gUse these columns for scientifically graded mixtures. AMERICAN STEEL &■ WIRE CO. 71 Reprinted by permission from Taylor&T/iompson's "Concrete Plain and Reinforced" page 233 VOLUME OF CONCRETE BASED ON A B-VRREL OF 3.5 CUBIG FEET. (See important foot-notes, also p. 225.) PROPORTIONS BY PARTS PROPORTIONS BY VOLUME Volume of mor- tar in terms of percentage f volume of stone AVERAGE VOLUME OF RAMMED CONCRETE MADE FROM ONE BARREL CEMENT Percentages of Voids in Broken Stone or Gravel 13 01 c c Hi E 0) U •0 c Ctt cu. ft. c £ 503* 45*t 40St 30#§ 20#? U bbl. cu. ft. % cu. ft. cu.ft. cu.ft. cu. It. cu. ft. 1 2 3 1 1 1 3.5 7.0 10.5 101 54 39 5.1 7.0 5.3 7.4 9.5 5.5 7.S 10.0 6.0 8.7 11.5 6.4 9.6 18.8 4 5 6 1 1 1 14.0 17.5 21.0 31 27 84 14.2 17.0 19.7 16.0 19.2 22.4 7 S 9 1 1 1 24.5 2S.0 31.5 21 20 IS 85.6 28.8 32.0 10 11 12 1 1 1 35.0 3S.5 42.0 17 16 16 35.2 38.4 41.6 1 1 1 1% O 2V4 1 1 1 3.5 3.5 3.5 5.2 7.0 8.7 104 7S 64 S.O S.9 9.9 8.3 9.3 10.4 8.6 9.1 9.7 9.7 10.5 11.2 10.8 11.8 j 12.7 T 1% 3 1 1 1 3.5 5.2 5.2 10.5 7.0 S.7 54 95 7S 10. S 10.2 11.2 11.4 10.6 11.6 12.0 ' 13.1 ' 14.2 11.0 11.7 12.5 12.1 1 13.0 I 14.0 1% 1% 3 3% 4 1 1 1 5.2 5.2 5.2 10.5 12.2 14.0 65 56 50 12.1 13.0 14.0 12.7 13.7 14.8 13.8 ' 14.4 ' 15.5 14.4 15.7 17.0 15.5 | 17.0 | 18.5 1 ' 1% 1 ; 1% 1 2 4% 5 3 1 1 1 5.2 5.2 7.0 15.7 17.5 10.5 45 41 77 14.9 15.9 13.4 15.8 16.8 13.9 16.6 17. S 14.5 18.3 * 20.0 20.0 i 21.6 15.6 j 16.8 2 2 2 3% 4 4% 1 1 1 7.0 7.0 7.0 12.2 14.0 15.7 67 59 53 14 3 15.3 16.2 15.0 16.0 17.0 15.6 16.S 17.9 17.0 1 IS. 3 18.3 ! 19. S 19.6 1 21.3 1 2 1 2 1 2 5 5% 6 1 1 1 7.0 7.0 7.0 17.5 19.2 21.0 44 41 17.1 1S.1 19.0 18.1 19.1 20.2 19.0 20.2 21.3 20.9 1 22.8 22.2 24.3 23.6 j 25.8 2% 2V, 2i4 3 3% 4 1 1 1 S.7 S.7 8.7 10.5 12.2 14.0 90 73 6S 14.fi 15.6 16.5 15.2 16.2 17.3 15.8 16.9 18.0 16.9 ' 18.0 18.2 19.6 19.6 21.1 1 1 2% 1 1 2^4 1 2H 4% 5 514 1 1 1 8.7 S.7 S.7 15.7 17.5 19.2 61 55 51 17.5 IS. 4 19.4 1S.3 19.4 20.4 19.2 20.3 21.4 20.9 ! 22.6 22.2 : 24.1 23.5 1 25.6 2% 2% 2% 6 6% 7 1 1 1 S.7 S.7 S.7 21.0 22.7 24.5 47 44 41 20.3 21.2 82.2 21.4 22.5 83.5 22.6 23.7 24. S 24. S l 27.1 26.2 28.6 27.5 j 30.1 3 3 3 4 4% 5 1 1 1 10.5 10.5 10.5 14.0 15.7 17.5 77 69 62 17.8 18.7 19.7 18.5 19.6 20.6 19.3 20.4 21.6 20.8 ' 22.3 22.1 ! 23.8 83.4 j 25.3 3 3 3 5% 6 6% 1 1 1 10.5 10.5 10.5 19.2 21.0 22.7 57 53 49 20.6 21.6 22.5 21.7 22.7 23.7 22.7 23.8 25.0 24.S j 26.8 26.1 28.4 27.4 j 29.9 3 3 3 7 8 1 1 1 10.5 10.5 10.5 24.5 26.2 28.0 46 43 40 23.5 24.4 25.3 84.8 25.8 26.9 26.1 27.2 2S.4 28.7 30.1 31.4 31.4 32.9 34.4 4 4 4 5 6 7 1 1 1 14.0 14.0 14.0 17.5 21.0 24.5 77 65 56 22.2 24.1 26.0 23.2 25.8 27.3 24.1 26.4 28.6 26.0 28.6 31.3 87.9 30.9 33.9 4 4 4 8 9 10 1 1 1 14.0 14.0 14.0 2S.0 31.5 35.0 50 45 41 27.9 29.8 31.7 39.4 31.5 33.6 30.9 33.2 35.4 33.9 36.6 39.2 36.9 40.0 43.0 5 6 10 18 1 1 17.5 21.0 35.0 42.0 48 46 34.2 40.5 36.1 42.8 38.0 45.0 41.8 1 45.5 49.6 54.1 Note.— Variations in the fineness of the sand and the compacting of the concrete may affect the volumes bv 10;( in either direction. *Use 50iJ column for broken stone screened to uniform size. +Use 45)6 column for average conditions and for broken stone with dust screened out. lUse 40j< colums for gravel or mixed stone and gravel. tjUse these colums for scientifically graded mixtures. 72 AMERICAN STEEL & WIRE CO. Reprinted by permission from Taylor&Thompson's "Concrete Plain and Reinforced" page ?3t VOLUME OF CONCRETE BASED ON A BARREL OF 3.8 CUBIC FEET. (See important foot-notes, also p. 225.) PROPORTIONS PROPORTIONS « O o C AVERAGE VOLUME OF RAMMED CONCRETE BY BY o O t- S m S S CO 0> MADE FROM ONE BARREL CEMENT PARTS VOlu - ; •" " He's O CO CO ° Percentages of Voids in Broken Stone or Gravel c dj CO se Se G E CO S C3 o Volui tar i perc volu 50#* 46#t a^X 30#2 20#2 a TJ CO a U S5 5) ft) m M JO }U9U10pj 3JES3.C •apiM. q=ai auf) ttiesg e in Eajy l 3a lS looj iEaui] jad 3piA\ ipui auo ^ uiEaff}0)i|3i3A\ "« o 4_, C H * II CD « ^ ts . o \s. o OS o ^5 K oH C H c <=> "™ t— i>t-»f3 w in its ia>ao 000 000 uwin g^uisJ t^ui raopj 3053 uioj: ojdgi jjooo ragg ^,-* -#in 0-H 10 0-* c*i a co O -H (D co ■* ■* (S ■* CO MCSO O O OI rH rH Ohm co w co rH M CO cncS 00 CO CO «CO CO CO OC4 ^H Tjl «3 Q0«N m t- 00 WHO O TO -f rH O rH t- r- TO TO CO fflMN rH tM « CO CO -* CQIQ CO ^* «5 IO lOON CO 00 t-i co m rHi-t rH lACOO TOM"* O CO CO "* "* o C3TO -f CO O CO O O TO !-OM rH TO TO rH rH TO TO CO -* C3 CO HQQN CO CO 0C I- C« O HMf- TOCOO OTOG0 lOCOt- rHrHi— ( C4TOCO CO-T-^I ICJOO TO TO TO CO tO i-H CO ■* CO CO TO Ci :-. :: i-hto TO TO TO O TOO rHrH r-tr-lr-t TO TO CO -*CO 00 to r- H r-i ■*QN TO TO CO co m co ■WlQCO IO f- r-t t-COO inoc) i-H CO CO W TO N IO CI CO CO-* CO TO CO CO §8 C3-I" rH n TO 00 >n -* TO CO -* in ?— t- oot. rH tOOJ Oi O TO T— 1 1— 1 OiCO 00 HHH 00 TO H CM CO 00 H TO TO •* TO U3 CO CJ 10 CO CO ■* TO 00 CO rH rH TO IO CO KS CO TfUfS CQ CO 10 co 00 a> TOrH rH rH CO IO l-H rH rH »> O O H H TO TO CO CO CO CO -n TO TO CO TO -#H H 00 CO *t tM,-5 ■«* CO CO rHTO CO -* th a -ft Ui CO coco 00 O TO rH rH OHO.H ■* CO CR> rH rH rH CO ?"- TO H f CO TO TO TO -* CO 01 CI CO CO TO CO "* TO CO TO H m co OS O CO rH CO ■* CO i-H rH CO t^ r- rH CO IO XO CD CI 00 i— "* rH TOTO *"* TO TO CO TO -* TO CO CO T* ■* CO 00 (^^ CO ■* 10 TO 3 COCO CM -W IO J> O TO CO COCO IOCOH rH rHTO Ol ■«* C3 IO OS CO TO TO CO NOCO CO CO CD CO TH ■<*! 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CO a s- < CO a r- < U CO u < in' CO <1 CO 5-5 *- 3 O ~ N C ;« ^ t| if •s. or CMt-CMt-CMC-CM cot-cotr-coc-coc-coc-coe-co t-oot-cot-xc^oat-oot-ooN O'*O^O'*0^O'*O'*O i-i r-t rH 00 O in 1-4 CO 02 IN CO CD CO - CM CO CO IN ■<* in co CO t- cn in rH IN ^ en CO CO _. •<* CO o o t— m ■* - t- rH 05 rH CO O ^ O N CO 00 OS rH t- t- O IN C- C5 CO -<* 05 in m 00 c- o en 00 cm O) C- 10 rH IN 00 r-i CO 00 CO IN NC-Nt-cNt-eac- c- co c- 00 t- 00 t( o >» CO C- CO C- CO c- 00 c- 00 t— O ■* O -cf o 00 c- 00 m m r-t r-l lO 00 rH C- © CO IN < CM rH CO O 00 t> 00 C7S rH tr- CD -* Cft r-t O O CO OS CM IN (N ■* Oi in t- co O CM CO CO CO rH CM rH rH rH O O CM rH 00 CO CTj CO 00 rH CO O CM t- CM t- IN t- CD t- CD t- CD O C- 00 t- 00 C- 00 © -^< © -* © -^ CM C- CD t- t- 00 O Tf c i-h o o o o COCOt- CD t- 00 t- _ O ^P O ■<* O *^< O t- (M t> CM C- t> <& t- CD t> 0O t- CO t- 00 IN 00 o> f- 00 10 00 in Oi lO OJ h- 00 sjaquiaw IBUipniiSuoq r— IN CT> CM O in CO 10 7-f 10 IN Tf in m IN lO O ■* IX 1 CO Oi ■"* t~- IN rH CI T-t C- rH CO 10 CJ O (N i-\ O rH ri tfl cS C3 C3 CS cfl rt CD A -(-> z ■a 1 d is 3 +j l CD t-H CO CD CD 00 t- tH -HI 02 O CO l> CD m rf CO CO ft z O o CO CO 0) CQ o CO 0) re £> o a t> a; fc. fl Z a o UI 4-1 F o 13 HI •M d) (1 o CC o 3 O V u. 111 o 1 cc o UI p. ffl t- to en t> to m CO IN i-H c c- o t-H c- IN S8 to c <~ ■* IN O 00 to in CO 3: « p. 00 m IN l-H c- in CO I-t iH r-t 1-4 m en IN •& SI to t Tf m to CO o CM o % Tables of Diagrams of Safe Bending Moments, Weights and Thickness of Slabs, Areas of Steel, Etc. 84 AMERICAN STEEL & WIRE CO. TABLE No. I. SAFE BENDING MOMENTS, IN FOOT POUNDS PER FOOT WIDTH. MIXTURE I : 21/2 : 5. Area of Cross Section of Steel Fabric in Square Inches per Foot of Width. Total thick- ness of slab in inches 2.5 3.0 3.5 4.0 4.5 50 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0 9.5 10.0 10.5 11.0 11.5 12.0 .05 103 133 163 193 223 253 283 313 343 373 403 433 463 493 523 553 583 613 643 673 .10 203 263 323 383 443 503 563 623 683 743 803 863 923 983 1043 1103 1163 1223 1283 1343 .15 298 388 478 568 658 748 838 928 1018 1108 1198 1288 1378 1468 1558 1648 1738 1828 1918 3008 .20 390 510 630 750 870 990 1110 1230 1350 1470 1590 1710 1830 1950 2070 2190 2310 2430 2550 2670 .25 479 629 779 929 1079 1229 1379 1529 1679 1829 1979 2129 2279 2429 2579 2729 2879 3029 3179 3329 .30 743 923 1103 1283 1463 1643 1823 2003 2183 2363 2543 1723 2903 3083 3263 3443 3623 3803 3983 .35 .40 1064 1274 1484 1694 1904 2114 2324 2534 2744 2954 3165 3374 584 3794 4004 4214 4424 4634 1442 168 192 2162 2402 2642 2882 3122 3362 3602 3842 4082 4322 4562 4802 5042 5282 .45 187,i 2145 2415 2685 2955 3225 3495 3765 4035 4305 4575 4845 5115 5385 5655 5925 .50 2365 2665 2965 3265 3565 3865 4165 4465 4765 5065 5365 5665 5965 6265 6565 .55 2911 3241 3571 3901 4231 4561 4891 5221 5551 5881 6211 6541 6871 7201 60 3513 3873 4233 4593 4953 5313 5763 6033 6393 6753 7113 7473 7833 .65 4172 4562 4952 5342 5732 6122 6512 6902 7292 7682 8072 8462 .70 4887 5307 57^7 6147 6567 6987 7407 7827 8247 8667 9087 .75 5209 5659 6109 6559 7009 7459 7909 8359 8809 9259 9709 .80 6006 6486 6966 7446 7926 8406 9366 9846 10326 .85 6350 6860 7370 7880 8390 8900 9410 9920 10430 10940 Table No. 1 is based on the following formula: In which R=(.?-P/I5) x A x D x 1600O. R=Mbment of resistance in foot pounds. P— Ratio, per cent, of area of steel to area of concrete above the center of the reinforcement. A=Area of steel in one foot of width— square inches. D=Distance from top of slab to center of reinforcement in feet. It is assumed that the center of the reinforcement is placed % inch above bottom of slab. The bending moment, which must not be greater than the moment of resistance, may he obtained by the following formula: Moment=iV x (total load per sq. ft.) x (span in feet) 2 The total load=the superficial or live load plus the weight of the slab, which may be assumed as 12 x the thickness of the slab. The span may be taken as the clear distance between flanges of the supporting beams or girders. Example of the application of the tables: To find the proper reinforcement for a slab having a clear span of 8 ft. to carry a superficial load of 250 lbs. per sq. ft. Assuming a depth of 5 in the weight of slab=--5 x 12= 60 Live load— 250 Total load- 310 Moment=A * 310 x 8 2 =1984. (For slabs supported at each end only.) used. For panels supported on all four sides, formula z \ x LxSp 2 =bending moment, should be AMERICAN STEEL & WIRE CO. 85 o Z ui _l m < CO ui X o z z — in CO .. CO ri < ^ -J ?! CO T- li. Ill O DC ll HI 2 D 3 HI 1 s Z i Z Q LI Q Z Hi £ o o LU cc z < CO CM CM OlOO COOiH oooo OOOi-iiM oooioi-i IQO O OO loooioiomo co co OS oi o i-i oi owwooioioo CD£-00C5OO.-t-t-00000J01OOHHW(M t-H i-H i-l i-H 1-H i-H OlOlOOlQO^lOiOOOIOOlOlOC l0lC«0t-tr-00000J03OOOHHrHC T— I T— ( ^H i-H i-H tH t OOOWOlOOlfllOOlOOOOOl •^WC0^it>t-0000C001C»OOHHr llfiOO OiOlflOlOOlOlOOlOlOOlOlOO *<#-i>tr-OOOOOOC50iC50 OO woo O i-H i-( lOWOlOOWlOOlOlOOOlOlQipiCllO oo^ioiococotot^t-t^cooooooociosos lOOO OiOO lOOlOOlOWOlfllOOOlOlOOOlfllO oo-<*^pwiriifi(x»cDCDt>t-t^t-ooooooco ooo OlOOiOOOlOlOOOlfllOOOWlOlO COCO^^lOiOLOiOCDC0COC0C>t-[>-t>l>- OOlO 00 00* CO lOOiOOlfliflOOlOlOOOOiOlOlOO (NlCOCO^'^'^lOLOlOlOCDCOCOCDCOCDt- OOlO 10001000101010001010101000 (MOOCOCO'^^'<*'<*'^i010lOi010lOCDCO OOlO COC£) CD lOLOOOlOiOLOOOOlOlOiOOOOO (MCMOOCOCOCOCO-^^'^^'^'^lOlOlOlO lO lO lO lOLOLO 10101010000101010100000010 CnJoJwNMCO^COCOCOCO^^^^-^^ LOlOlO I010l0l0l0l0l0l0i00000000l0 NCSIWWCgtNCMCNlOvlCOOOCOCOCOCOCOCO 10 10 10 CO CO CO I0l0l0l0l0l0 10l0l0l0l0l0l0l0l0l0l0 WW(NNMWC^NCioq<>5C^CNi lO LO lO (NCNICM oooooooooooooooooooo 100100L00100L00100L00100L00100 iHi-iCMCMCOCO"^-^1010CDCDC-t-OOOOOi(J5 (03O $3 « B 53 » ii USE bt«§ S|a a> -. ^ •8 ° s S-9 U (0 ^ 2 » > c >*:= t." - b ® jSf- S ts a> « „ i-t o Xi p Space Piaster Partition Wall,. Wall Construction. AMERICAN STEEL & WIRE CO. 105 7b/Q of Po/e •Section e>/* Po/e- or-f- Tojo ■Section o-f /-^o/e gy/ Bo H-om /~er>ce /-■'osf Te/egrcr/oh £>o/e Concrete Reinforcement with Triangular 2-inch Mesh Woven Wire. 106 AMERICAN STEEL & WIRE CO. '/. V V- * ■— H *r* ,HHi .. .. .. .' ' .' 1 > V ■-* ^ ^ 1 '/. 1 IS y<: ;_V-V'V-V-'V ■■-- -*■— V- -N'~ -V— %< f: ;-*■_ _ r> ^_ __>.__> . T~ ,"*•"— - J<7 — -,"\ x^ i- p*" »v_- _-i<».-_ ViT^ViJ-r Stair Construction in Reinforced Concrete. AMERICAN STEEL & WIRE CO. 107 Winding Stairs in Reinforced Concrete. 108 .AMERICAN STEEL & WIRE CO. WSmatmrtrpr^ Reinforced Concrete Stairs. AMERICAN STEEL & WIRE CO. 109 ff+ Suggestions in Reinforced Concrete. 110 AMERICAN STEEL & WIRE CO. maw n i a n n > ; n fl n a on i 3 CB IT» ffl « }s &t m « in e, '"ElBlHffl *V BO s 3 O •a i Eh H « P -1 s .3 c w . S ™r £ A* -S.2 s o O =2 '53 6S.S 3 AMERICAN STEEL & WIRE CO. I 111 3 be c CS be c '% o j= w c o c o bo 3 P O 112 AMERICAN STEEL & WIRE CO. Eames & Young, Architects. ELY WALKER DRY GOODS CO. St. Louis, Mo. Triangular Mesh Reinforcement Used in Floors by The National Fire Proofing Co. ■ ''~i'(- AMERICAN STEEL & WIRE CO. 113 114 AMERICAN STEEL & WIRE CO. AMERICAN STEEL & WIRE CO. 115 mil lllHl ^ If ■ nrfSSiw ■Willi I ! IjPjSSr *! *3w *4L ^* ^ John Parkinson, Architect, Los Angeles. ALEXANDRIA HOTEL Los Angeles, Cal. Triangular Mesh Reinforcement Used in Floors by National Fire Proofing Co. 116 AMERICAN STEEL & WIRE CO. Whidden & Lewis. Architects CORBETT BUILDING, Portland, Oregon. Triangular Mesh Reinforcement Used in Floors. AMERICAN STEEL & WIRE CO. 117 bo c 2 '3 m O) o O « 3 bo C 118 AMERICAN STEEL & WIRE CO. AMERICAN STEEL & WIRE CO. 119 p. ft o a 120 AMERICAN STEEL & WIRE CO. AMERICAN STEEL & WIRE CO. 121 Baknett, Haynes & Barnett, Architects. ^ MARQUETTE HOTEL. St. Louis. Triangular Reinforcement Used in Floors by National Fire Proofing Co. 122 AMERICAN STEEL. & WIRE CO. AMERICAN STEEL & WIRE CO. 123 124 AMERICAN STEEL & WIRE CO. AMhKlLAN SlL-li'L & WIRE CO. 125 THE BAILARGEON BUILDING, SEATTLE, WASH., EMPLOYING TRIANGULAR MESH REINFORCEMENT. TRIANGULAR REINFORCEMENT IN THE BAILARGEON BUILDING, SEATTLE WASH. 128 AMERICAN STEEL & WIRE CO. USED IN COLUMNS AND FLOORS IN MACHINE SHOP. SECTION OF UNLOADING PENS. Triangular Reinforcement as used by Union Stock Yards and Transit Co. , Chicago. AMERICAN STEEL & WIRE CO. 329 AS USED IN RETAINING WALLS. COMPLETED PORTION OF PLATFORM AND PENS. Triangular Reinforcement as used by Union Stock Yards and Transit Co. , Chicago. 130 AMERICAN STEEL & WIRE CO. 'fiam 5 ^''' TRIANGULAR REINFORCED CONCRETE WATER TROUGHS. TRIANGULAR REINFORCEMENT AS USED IN FENCE BETWEEN, STOCK PENS. Triangular Reinforcement as used by Union Stock Yards and Transit Co. Chicago. AMERICAN STEEL & WIRE CO. 131 INDEX Page. ADHESION BETWEEN CONCRETE AND STEED 25 BALTIMORE FIRE 39 CAST CONCRETE SLAB VENEER 63 CAUSES OF ROUGHNESS AND DISCOLORATION 55 CINDER VERSUS STONE CONCRETE 41 COEFFICIENT OF EXPANSION 25 COMPRESSIVE STRENGTH 17 CONCRETE VERSUS TERRA COTTA 40 CONSTRUCTION OF FORMS 56 COST OF CEMENT 28 COST OF GRAVEL OR BROKEN STONE 29 COST OF LABOR 29 COST OF SAND 29 DIAGRAMS 86 to 93 EFFLORESCENCE 64 ELONGATION OR STRETCH IN CONCRETE 44 FINISHING MORTAR FACING 58 FIRE IN BORAX FACTORY 39 GRADE OF STEEL 34 GRAPPIERS CEMENT 51 HYDRATED LIME 54 ILLUSTRATIONS AND USES OF REINFORCED CONCRETE.. 98 to 139 MAGNESIAN LIME 54 MASONRY PACING 61 MODULUS OF ELASTICITY 20, 43 MOLDINGS AND ORNAMENTAL SHAPES 63 MORTAR OR GROUT FACING 57 PEBBLE DASH FACING 60 PLASTERING 60 PRESERVATION OF IRON IN CONCRETE 35 PROPERTIES OF CONCRETE 16 PROPERTIES OF STEEL 22 QUALITY OF REINFORCED STEED 32 REINFORCED CONCRETE 15 RELATIONS BETWEEN CONCRETE AND STEEL 22 132 AMERICAN STEEL & WIRE CO. INDEX— Continued Page. SAFE LOADING AND REINFORCEMENT FOR STONE CON- CRETE BEAMS 74 SAND CEMENT 50 SHEARING STRENGTH 18 SLOW SETTING CEMENTS 51 STONE FACING 61 TABLES OF BENDING MOMENTS 84 to 85 TABLE OF WEIGHTS AND AREAS OF ROUND AND SQUARE BARS 94 to 96 TABLES OF WEIGHTS, AREAS AND SIZES SQUARE MESH REINFORCEMENT 80 to 81 TABLES OF WEIGHTS, AREAS AND SIZES TRIANGULAR MESH 76 to 79 TENSILE STRENGTH 18 THICKNESS OF CONCRETE REQUIRED TO PROTECT METAL FROM FIRE 41 TOOLED SURFACES 60 TRIANGULAR AND SQUARE MESH REINFORCEMENT 3 TABLES OF QUANTITIES OF MATERIALS 66 to 73 VASSY CEMENTS 51 WORKING LOADS 22