Clas8..G.!^.=5/.6i. Book E.I.Z.G... Accession...S.*d.'^../..2^ PRACTICAL CONCRETE-BLOCK MAKING A SIMPLE PRACTICAL TREATISE FOR THE WORKMAN EXPLAINING THE SELECTION OF THE MATERIALS AND THE MAKING OF SUBSTANTIAL CONCRETE BLOCKS AND CEMENT BRICK TOGETHER WITH RpST ARCHITECTURAL EFFECTS BY CHAELES PALLISEE Author of " Modern Cement Sidewalk Construction," " Useful Details," "American Architecture," etc., etc. FULLY IlL,LUSTRA.TEr> NEW YORK INDUSTRIAL PUBLICATION COMPANY 1908 OOA/S Ml (9 off PEACTICAL CONCRETE-BLOCK MAKING Copyright secueed 1908 BY INDUSTRIAL PUBLICATION COMPANY CONTENTS PAGE Imtroductory . 7 clement and concrete 8 BiLocKs, Molds, and Machines 9 Dhrections for Manufacturing Concrete Blocks . 14 General Hints and Suggestions 25 P(ORTLAND Cement-Sand Brick 35 Wooden Molds 38 Aire Architects and Builders Against the Use of the Common Concrete Block, and Why? . . 47 Sttandard Specifications for Blocks 53 Tiesting Hollow Concrete Blocks 63 Imdex 67 3 03 / a PREFACE THE rapid advance in the use of concrete blocks for building has tempted many to go in the business of manufacturing blocks for a Uving, and unfortu- nately many have entered the field who are ignorant of how a block should be made, and in consequence they turn out bad blocks which soon crumble. If the blame for such poor work was put on the maker, who> is at fault, we would have nothing to say, but the ver- dict is usually against concrete blocks, thus making them unp'opular. In this little book the writer has tried to put in simple language directions for making blocks, based upon an expcerience of thirty years in concrete work. Iff this book will be a guide to the workman, enabling him to turn out a good, substantial, concrete block, it will fulfill the wish of The Author. Elberon, N. J., October 1, 1908. PRACTICAL CONCRETE=BLOCK MAKING THE fast extending employment of concrete com- pressed into the form of stone blocks for building work of all descriptions promises to make a new sty le of architecture, and the success or failure of the same will depend in large measure on what the architects accept or reject in their drawings and specifications as the best form of block, or the putting together of this material and the appearance given to its face finish. The architects' designs and details must govern these matters, and they, and they alone, must be the educators of the public in such matters of taste and art, and not the block-machine men, or the ma.nufacturer of stone, or the contractor; but so far it wonild appear that the architects have in many sections been rather slow in coming forward and the other gentle- men have gone way ahead in this all-important matter. It is high time that the architects and building superin- tendents of the country were alive to the situation, and wh^erever they have been so, they have on hand far more wojk than they can attend to. 8 PRACTICAL CONCRETE-BLOCK MAKING Concrete and other fireproof-building materials, when not fashioned aright, produce too much monotony, but it is absolutely true that in the hands of those who are practical and skilled in design and construction, these materials can be made to- yield architectural effects of the greatest variety and beauty, as they are susceptible of being produced in any design of face, color, mold, or shape, and in durability are far better than any sandstone, lime- stone, or low-grade marble. CEMENT AND CONCRETE CONCRETE is the name given to a compact mass of broken stone, gravel, cinders, shells, or other suitable material joined together with mortar and allowed to harden. To prevent air spaces forming, the concrete is firmly squeezed or rammed down or "tamped," as it is called. The mortar used is generally composed of cement and sand mixed with water. CEMENT is a preparation of clay and limestone, or their equivalents, which has been placed in an oven or kiln and subjected to an intense heat, the clay and lime- stone thereby being reduced to a crumbling mass which is ground in a. mill to make it a uniform powder, when it is known as cement. It possesses the property of harden- ing into a solid mass when moistened. The solid mass being composed of many small crystals, hence it is often PRACTICAL CONCRETE-BLOCK MAKING 9 mentioned about cement crystallizing or "set," as it is called. When a definite quantity of concrete is made at one mixing, it is called a "batch." When concrete is tamped or rammed, it tends to close the spaces between the stones or whatever else is used for the " aggregate," and this would bring the water to the surface When concrete is mixed with so little water that very hard ramming is required to flush the water to the surface, it is called a ''dry mix," and likewise when enough water is used so that little or no ramming is needed to have it flooded, it is called a ''wet mix." BLOCKS, MOLDS, AND MACHINES IN making concrete blocks the mixture of concrete is placed in a mold, so as to give the concrete shape and make it into a block. The simplest arrangement is to have a common box into which the concrete is placed and tamped down, so that there will be no air holes, the concrete thus forming a thor- oughly soUd block. After the concrete has been in the box for a week or ten days it is removed from the box or mold, and the result is a block of artificial stone or, as it is called, a "concrete block." ^ ... If it simply depended on making a number of plain con- crete blocks, the above method would be sufficient. 10 PRACTICAL CONCRETE-BLOCK MAKING The item for making molds would amount to quite a good deal, hence one mold must do service for making a large nurhber of blocks. The molds must be substantial and easily taken apart without jarring the concrete block Fig. 1 (which would be likely to make it crack), so that they can be used again in a short time for the manufacture of the next block. Wooden molds are the simplest to make and they are always used when anything out of the ordinary is called PRACTICAL CONCRETE-BLOCK MAKING 11 for. For common blocks, cast-iron molds are used, as they stand hard, continuous usage. These are made so that the sides may be opened and the block easily removed. There are many different kinds of these iron molds in the market, and they are known as "concrete-block machines," some being arranged with devices to do the tamping by Fig. 2 pressure and the sides opening so that the block may be easily removed. Fig, 1 shows one of these machines, and this shows the general principle on which all of the machines are constructed. Concrete blocks are usually made of large size, so that the labor of building with them is lessened when compared 12 PRACTICAL CONCRETE-BLOCK MAKING with brick. The most popular machines have adopted the standard length of 16 and 24 inches, a height of 9 inches, and a thickness of 8, 10, and 12 inches. Small, solid concrete blocks, the size of brick, are also made, these being used the same as brick. A machine for making " cement brick," as they are called, is shown in Fig. 2. This machine is also used for the making of " sand-lime " brick. Full particulars about the various machines can be had from the manufacturers, whose advertisements will be found in the various building and cement papers; therefore we will not give descriptions of machines, but instead will 'give directions for making wooden molds, as often special designs are wanted, and the concrete-block manufacturer should know how to make the molds, so that he can turn out something more than just a mere plain block which he makes on his " machine." It is a well-known fact that a dead air space is a poor conductor of heat, and this fact has been taken advantage of in the manufacture of blocks by making them hollow, as in that way they also use less material and, being lighter in weight than a solid block, are more easily handled. Various forms of hollow blocks are shown in Fig. 3. Prac- tically every form is made by a certain machine, and each manufacturer declares some special advantages over all others for his particular form of block. Any one reading the remarks in this book will have no trouble in selecting a machine suitable for his own class of work. Select a machine with a good reputation and you will be sure to get one that will give satisfaction. PRACTICAL CONCRETE-BLOCK MAKESTG 13 14 PRACTICAL CONCRETE-BLOCK MAKING DIRECTIONS FOR MANUFACTURING CONCRETE BLOCKS THE following specifications for the manvifacture of concrete blocks have in general been accepted. SAND. — Such as will pass a screen of J-inch mesh and is retained by a screen of No. 40 mesh. This appHes to bank, river, or beach sand, and to crusher dust. GRAVEL. — Such as comes from a bank, river, or beach, of such size as is retained by a screen having J-inch mesh. CRUSHED STONE.— Such stone as is retained by a J-inch screen. BANK GRAVEL.— Such as is obtained from a pit, cel- lar, river, or beach, containing both sand and gravel. AGGREGATE. — Any material, as broken stone, gravel, or such fragments used with Portland cement and sand mortar in making concrete for the purpose of reducing the cost and adding to the density and strength. VOIDS. — Space existing between particles of sand, crushed stone, or- -other materials of which an aggregate is composed. CEMENT. — Any Portland cement, American or foreign, that will pass the tests required by the American Society for Testing Materials. " QUALITY OF . SAND.— Must not be. finer than .^bove described, and must contain no clay or other soluble mat- ter. Crushed stone or gravel to be free from dirt, loam, or other foreign substance or rotten stone. PRACTICAL CONCRETE-BLOCK MAKING 15 AMOUNT OF CEMENT. — A correct concrete should consist of sand and gravel or crushed stone, or a combina- tion of same, with an amount of cement equal to the voids, or, in other words, the interstices to be filled with cement. Some bloclcs are made only with sand and cement; these, properly speaking, cannot be called concrete blocks, as they are "sand-cement blocks." If the concrete is of sand and gravel, such portion of cement shall be used with the sand that is equal to the voids in the sand, and such quantity of this mortar mix- ture shall be used with the crushed stone or gravel as will fill all voids in the latter. The cement is to fill the voids in the sand, and the mor- tar resulting is to fill the voids in the aggregate. DETERMINATION OF VOIDS.— To determine the voids in the sand, or the material used as an aggregate, the "water test" is employed. The sand or gravel used must be bone dry. A receptacle holding a known amount, such as a gallon jar, is filled with the materials to be tested, and into this vessel is poured as much water as the sand or other mate- rial will absorb. Measure the water, and the amount of water absorbed indicates the voids, and also indicates the exact amount of cement which it is necessary to use in order to produce a dense, solid stone. In making hollow blocks, if no gravel or broken stone is used, this test gives the proportions of sand and cement to be used. Average sand will absorb about 33^% of water, indicating that amount of voids, also that a propor- IG PRACTICAL CONCRETE-BLOCK MAKING tion of 1 part of cement to from 3 to 5 parts sand are required to make a solid block. The proper selection of sand and aggregate is impor- tant, and the particles should vary in size so as to reduce the voids to the smallest amount possible. With care in this selection, the amount of cement needed to produce best results is greatly lessened, provided that in the defin- ing of the proportion of cement is meant a given measure of cement as one portion, and that multiple of that meas- ure of aggregates as properly combined, under the water test, shall determine the proportion. If found under the test that 5 parts crushed stone or gravel will take 3 por- tions of sand to fill the voids without increasing the bulk, and that 1 portion of cement shall fill the remaining voids, this proportion shall be a 1-3-5 mixture. MIXING. — After selecting the materials, mix them together dry, until of a uniform color; then apply water and repeat the thorough mixing, the amount of water to be as great as possible. More care of the face plates of any machine will enable the worker to use a wetter concrete than is usually em- ployed. Only such size of batch shall be mixed as can be used up in 30 minutes from the time the water is added. MANUFACTURING.— The concrete should be placed in small quantities, and tamping begun immediately and continued until the mold is full. A small-faced tamper should be used, and short, quick, sharp blows should be struck. If faced blocks are made, use 2 parts sand and 1 part cement for facing. Tamp the concrete well into the PKACTICAL CONCRETE-BLOCK MAKING 17 facing, so as to effect a bond to prevent its peeling off. In the wet process, the amount of water used is such as will produce a plastic or flowing condition in the concrete, but not enough to wash the cement from the other mate- rial. When placing this material in the molds, fill the Fig. 4 entire mold with one pouring. It is well to cover the face of the mold with shellac, crude oil, or a solution of gasoUne and paraffin, so that the block may be easily removed from the face of the mold without injury, as when the cement is mixed with a generous supply of water, it becomes quite sticky. 18 PRACTICAL CONCRETE-BLOCK MAKING Through the kindness of the Miracle Pressed Stone Company of MinneapoUs, Figs. 4, 5, 6, and 7 are given, Fig. 5 which show the operations very clearly. Concrete blocks are most economically made by employ- PRACTICAL CONCRETE-BLOCK MAKING 19 ing three men, one to do the mixing and the other two to attend to the making of the block. However, the process is simple enough, so that two or even one man can do the job. The mixture is shoveled into the mold as shown in Fig, 4, and tamped as shown in Fig. 5. As soon as the mold is full, it is floated off, that is, all the surplus material is pushed off as shown in Fig. 6, so that the top is level. After this operation the block has set enough so as to keep its shape if it is not jarred; hence it is carefully 20 PRACTICAL CONCRETE-BLOCK MAKING removed from the mold. To do this the cores and sides are removed and the block allowed to rest on the bottom. Fig. 7 The sides are then formed together again and placed on a new bottom, and the process repeated for the next block. PRACTICAL CONCRETE-BLOCK MAKING 21 In the pictures the Miracle mold is shown, and this has an iron bottom, the blocks being turned upside down while in the mold on a tray or pallet made of boards of the proper width and with two cleats to keep it in shape, and which also allow sufficient room for the fingers, so that when putting it down it need not drop the least bit. This pallet can be used to level the mixture in the mold, as shown in Fig. 6, and then held in position while the mold is being turned until the block rests on the pallet, and the mold removed, and the block can then be carried away, as shown in Fig. 7. Should any crack or defect appear in moving the "green" (freshly made) stone, throw the material back into the batch and mix it over again. CURING. — After the block is made as above described, it is important that it be properly cured, that is, dried. This is a process that takes time, as the concrete takes time to get its full strength. The time needed is about as follows: 50% of strength in 7 days 65% " 30 95%" " " 6 months 100%" " " lyear Blocks should be made under cover and kept under cover for at least 10 days, and protected from the sun and dry currents of air, which would tend to dry the out- side of the block first, causing unequal drying, which will make a block the inside of which will be in a poor condi- tion. No matter how good a block is made, if it is poorly cured, it is worthless. PRACTICAL CONCRETE-BLOCK MAKING To prevent this rapid drying of the outside of the block (which prevents the proper crystallization of the cement), they should be kept moist by gentle sprinkhng, which should be commenced as soon as the blocks will bear it without falling apart; that is, wait until the cement has set enough, so that it will prevent washing. On a warm, dry day, they need moisture sooner than on a rainy day. To know just exactly how long to wait will be learned by experience with the first few blocks. They should be kept wet for about 10 days at least, as it gives time for the proper crystaUization of the cement. When cement drys too quickly, the crystals are in the form of little balls, and, for the most strength, they should be of the needle form, which process needs moisture and slow drying. Blocks should not be used unless they are at least one month old, and where they are subjected to any consider- able weight, it is best to have a block six months old. This subject of curing is an important one, and if you haven't the cash or credit to keep a three months' supply, you had best not start in the business, for you can be cer- tain of one thing, and that is, if you don't turn out a good, reliable block, you will go out of business after a short time. Proper storage room should be provided for the blocks, so that they will be protected from the sun and dry winds for the first few weeks of curing. Blocks can be safely removed from the pallets in about three or four days. It is necessary to have a good supply of the pallets on hand. PRACTICAL CONCRETE-BLOCK MAKING 23 PLACING— In placing cement stone in the wall, a soft mortar composed of cement and medium-screened sand should be used— a mortar that will work greasy under the trowel, spread evenly on the bed, and butter the ends of blocks, so as to make a solid and full set in all joints. These stones must be evenly and solidly set all round, so as to have close bearings and contact. COLORING.— In using coloring matter, the color should always be mixed with the cement dry, before any sand or water is added. This mixing must be thorough, and thfe color uniform. After being mixed dry, use in the same way as clear cement. QUANTITY OF COLORING MATTER PER SACK OF 100 POUNDS OF PORTLAND CEMENT Color. Blue slate. . . . Black slate. . . Gray Brown Red Bright red. . . Yellow or buff. Dry Material Used. Ultramarine blue Excelsior carbon black Lampblack Roasted iron oxide. . . . Raw iron oxide Porapeiian red Yellow ochre Weight op Color. 4 lbs. 2 " h lb. 6 lbs. 6 to 10 lbs. 6 lbs. 6 to 10 lbs. BONDING.— For bonding together the inner and outer wall of the hollow block, use a material that will in nowise be a conductor of the moisture from the outside to the inside; concrete will not do under any circumstances. The only practical material is galvanized iron. Of course if concrete is used for the tie, then no claims can be made 24 PRACTICAL CONCRETE-BLOCK MAKING that the inner wall will be moisture-proof, and it must be first studded off and then lathed before the plastering can be done. In cases where the moisture (caused by the rain beating against the sides of the house) cannot penetrate to the inner wall, the plastering can be done directly on the blocks. WATERPROOFING.— To prevent the moisture, the faces of the block and mortar are painted over with a waterproofing solution. A good one, called the Sylvester Process of Waterproofing, is as follows : Wash the surface with a solution of three-quarters of a pound of castile soap to every gallon of water. Apply the solution hot, with a flat brush, to the wall, which must be clean and dry. Let this remain twenty-four hours and apply a solution of a half-pound of alum to four gallons of water; this wash must also be appUed hot. If at the end of another twenty-four hours the wall absorbs mois- ture, repeat the two coats as before. Care should be taken not to have the soap solution froth while applying. The use of milk of hydrated lime has been advocated for concrete facing and mixing, and is said to materially add to the strength and waterproofing qualities. Quick- Hme is also advocated. It must be thoroughly slaked with water and remain in the water for a day or two, so that all particles will dissolve. It is then called milk of lime and, after being poured through a very fine screen, can be readily used in the place of clear water for mixing the facing, and will make the color of the stone whiter and PRACTICAL CONCRETE-BLOCK MAKING 25 more water-proof, but this must be very carefully used, otherwise it will have a tendency to weaken the facing. The principal essential in making stone water-proof is to make it good and to use a richer material as a facing. Hydrate of lime, la Forge non-staining cement, shell lime and marble dust, white cement, and Blanc, are all used for facing concrete blocks. GENERAL HINTS AND SUGGESTIONS IN the manufacture of concrete blocks, the greatest cani should be exercised in the selection of the very best brand of Portland cement that can be obtained, and clean, coarse sand or screened gravel, and equal careful methods of grading, mixing, and curing must be observed. The quality and amount of sand and gravel to be mixed with the cement must receive equal careful attention, as well as the water employed for softening the mixture. Two screens should be used, the upper one being the coarser, and the one below being fine, to allow the fine sand to go through that is too fine to use in the highest- grade work, as the particles to be used should be coarse and also uniform, while that retained by the upper screen is too coarse, or, in other words, the material that is to be used must pass through the first screen and be retained on the second screen. Sufficient water must be used to bring the mix to a con- sistent paste, so that it will unite with the screened sand 26 PRACTICAL CONCRETE-BLOCK MAKING and form a stiff, homogeneous mass; the bringing of the mixture to the proper consistency is of great importance. In all instances the exact portions of cement, sand, gravel or stone, and water should be ascertained and decided on in advance, and the same quantities used in making each and every batch for bricks or blocks; otherwise there will be a variation in the color and durability of the walls con- structed. These mixes vary in formula from 1 to 4 to 1 to 5, but the greater the amount of Portland cement added, the stronger will the bricks or blocks prove when cured. The mixing and tamping must be thorough, but a rake is the best tool to use to get the color uniform, and this work can best be done by experts. No exact rules can be given which would help one to understand just when the ingredients are sufficiently incorporated, one with the other, but the mixing should be done to secure a perfect uniformity of material, and water should be added until the mass is plastic enough to work without sticking or sag- ging when released and taken out of the mold or machine. An enterprising manufacturer of stone machinery has the following to say in his circular: "Concrete is not the coming age. It is here. Port- land cement has made such vast strides in the last few years, and has been used in the work of the greatest impor- tance so extensively and with such satisfaction, that its many valuable qualities are now known to everybody. We find it towering in the air, tunneling the earth, and, like Gibraltar, holding the sea at bay. And why not? It is as readily molded as wax; limited in form, color, anc^ PRACTICAL CONCRETE-BLOCK MAKING 27 design only by the imagination of the architect, and pos- sesses the endurance of the pyramids. For building pur- poses it is unsurpassed, unequaled." Then he goes on to tell of his machine, and it is certainly the real thing and a corker, and every builder can afford to own one, and he gives facts and figures that are cer- tainly convincing. He further says that it is impossible to anticipate all the requirements of the modern architect, but directions are sent with each machine, so that any carpenter can quickly improvise plates for special shapes or designs. Among some of the advantages of hollow-concrete con- struction, he mentions the following: Artistic appearance. Cheapness of construction. Buildings warm in winter and cool in summer. Dry, ventilated walls, fire- and frost-proof. Insurance is cheaper. Requires no painting or repairs. Blocks can be laid in the wall rapidly, and require but little mortar. Plastering may be done on the back of the stone, saving lathing. Free from rats, mice, and vermin. Perfectly sanitary. Resists rain and dries quickly, while soUd walls remain damp. Can be molded into the most elaborate designs conceived by the architect; all that is required is the carpenter to carry it out. 28 PRACTICAL CONCRETE-BLOCK MAKING The stone is thoroughly durable, becoming harder with age. He has the following to say about Portland cement : When Portland cement began to be used so extensively and by so many persons totally ignorant of its properties, and working without direction, there was much uncer- tainty as to its proper use, and particularly so, as some- times good results were obtained with totally incorrect methods of handUng. This proved only that "accidents will happen," or possibly that cement is Hke a hen— when it wants to set, it sets. The question is not merely to get cement to set— it will do that anyway if it gets into contact with dampness. The question is one of economy and intelligence— to get the best possible results with the least possible expense. The foremost chemists and engineers of the world have made thousands of tests with the most accurate instru- ments and careful handling, have compared notes and verified results till we now have certain well-recognized "laws" to guide us, the most important of which are as follows: 1. Portland cement should have only enough water ?t first to start crystaUization. Too much water "drowns" cement. 2. Water should be fed to the stone as crystalliza- tion requires. 3. Concrete continues to harden with increasing age, and the slower the crystals form, the larger and Stronger they will be. PRACTICAL CONCRETE-BLOCK MAKING 29 4. Concrete should be made compact, the grains of sand being worked till they thoroughly weld themselves into each other and close all the pores. 5. This is best accomplished by frequent but not too hard tamping. Very hard tamping with a small-faced tamp jars and bounces the material without packing it at all. 6. Pressure will not make a good stone, the reason being that when pressure is applied, the concrete is at once made compact at the top and bottom in thin layers. These layers ejffectually form a seal and prevent the air on the inside from escaping, and the air is compressed as the pressure is applied. As soon as the pressure is removed, the air expands, forces the grains of sand apart, and makes a stone that is weak and porous, and therefore easily subject to disintegration. On the contrary, light but frequent tamping works the air out and packs the grains together. 7. Concrete when first made has no more strength than so much damp sand. If a crack is started while in this condition, it will not reunite, but forms a permanent element of weakness; there- fore concrete should not be disturbed or jarred after it has been molded or while it is setting. No nails should be used in making forms. He further says that his machine embraces all of these fundamental principles, and is the only machine made with which an observance of all of them is possible. 30 PRACTICAL CONCRETE-BLOCK MAKING Then he gives the cost of making stone blocks as follows: The cost to make the blocks naturally varies in different countries and in different parts of the same country. In the northern part of the United States, the standard-size blocks usually cost from 6 to 8 cents each. We give below an itemized cost based on present prices in our stone factory. These figures may be changed to meet local conditions. 14 yds. sand and gravel at .$ . 50 $ 7.00 14 bbls. Portland cement at 1.50 21.00 4 laborers (3 molders and 1 mixer) at.. 1.50 6.00 Allowance for water and sundries 2.00 $36. 00 Dividing the total of $36.00 by 600, which is the num- ber of blocks the above materials will produce and the four men make and take care of, gives the cost at 6 cents per block. When the blocks are made in large enough quantities to justify a concrete mixer, this cost can be con- siderably reduced. Delivery of the blocks usually costs about 1 cent per block. Seventy of them can be hauled at a load. The usual selling price is from 16 to 20 cents, so that there is a very handsome profit in their manufacture. Frequently they are made on the premises from the sand taken from the cellar, and then used in the walls of the building, thus saving hauling the sand away as well as delivery of the blocks. He has the following to say about rock 'facing and coloring: TRACTICAL CONCRETE-BLOCK MAKING 31 At a small additional expense the blocks may be molded 2 inches larger than they are to be in the finished wall. After the stones have partially set, this extra 2 inches is rocked off with a stone-cutter's pitching tool, making every block different, and presenting an effect in the wall that is strikingly artistic. For churches, store fronts, and handsome residences, there is nothing that will equal it. By using different-colored sands, crushed, white lime- stone, crushed granite or quartz, almost any natural stone may be dupUcated so as to deceive even the experienced. With the aid of different mineral colors, the stones may be made of almost any color, either solid, mottled, or stratified. There is apparently no great necessity for a man who builds just one house to go and purchase a machine, as his carpenter will build the molds and be the pattern- maker. The Allen G. Thurman house at Columbus, Ohio, a remarkably fine-appearing house to-day, constructed in 1885, shows that years ago some one had an idea of a "cut-stone" house without the cut stone, and it certainly is a rational and perfect example; no freakish, stamped sheet-metal face about it. The blocks were cast in a mold and faced to resemble stone work, plain, pure, and simple; they are absolutely water-proof and perfect, though they were not made on a machine. Another example is located at Portchester, N. Y., built man}^ years before the above, only it is concrete throughout, even to the stairs, par- titions, etc.; and also the old house on Staten Island, ■ 32 PRACTICAL CONCRETE-BLOCK MAKING also built of made stone. They all testify that the block- machine man is an innovation, but any one who goes into the stone-making business needs just such a machine as is described in this book, and it certainly appears to be a money maker. There is only one feature about it that I do not approve of, and that is, it makes a stone that is tied together with the same material as that which it is made of, and cannot, therefore, possibly be damp-proof and fit to plaster directly on the back, because concrete or the mortar between made stone, brick, or stone work is unquestionably a water con- ductor. All walls should be constructed so that they will have a continuous air space between the inner and the outer wall, and these are the only walls that will give an even temperature summer and winter. I see no reason why my esteemed friend, the manu- facturer of the block machine here referred to, does not so adjust his machine to this idea and tie the inner and outer face of the block together, on a different plan, and with a material that will not make it a conductor of damp- ness; then it would certainly fill the bill completely. He should do this at once, or else throw his machine in the scrap heap, as it is simply a lie, and he is claiming for it what it is in no way entitled to in this respect. Framed structures are doomed; wood is too costly to build with, and is a constant source of expense to main- tain. Brick and natural-stone buildings will be erected for PRACTICAL CONCRETE-BLOCK MAKING 33 a few more years, but they too are doomed for many rea- sons, and just as soon as the now material, American Port- land-cement concrete, is thoroughly understood and its full possibilities reached. The recent seismic disturbance on the Pacific coast has proven conclusively that Portland cement, when it will be fully developed and thoroughly understood, will even be proof against such things as earthquakes, as it is now already proof against many other things. Among the many advantages of hollow concrete-stone construction may be mentioned the following: Hollow manufactured-stone construction effects a saving of material over solid brick or stone masonry, requires no wooden furrings, and therefore makes an absolutely fire- proof wall or partition. The cost of laying stone blocks is less than for brick- work, due to the fact that each block takes the place of 18 to 42 brick, requiring much less mortar in joints and less labor in setting. A wall or partition made of the best of this manufac- tured material is stronger than an A No. 1 hard-burned brick wall of equal thickness, as laid at the present time. What about the soft and half-burned bricks that go into walls and disintegrate from dampness and freezing every winter; what of the fireproof quaUties of such brick? They are not fireproof, as I have good reason to know. Last winter some boys built a fire on Election night against the gable end of a very fine, expensive stable situated at 56 E. 88th Street, New York City, belonging to a million- 34 PRACTICAL CONCRETE-BLOCK MAKING aire, and the hard-burned bricks were spoiled, crumbled, and disintegrated, and the Insurance Company had to make it good with new brick, and about 2,000 new bricks had to be put in at considerable cost. Brickwork done to-day is not what it used to be 30 or 35 years ago, Avhen I have had brick walls and partitions built 60 feet high and 8 inches thick in the finest kind of buildings, and they are standing as solid to-day. Natural stone, much of which, though apparently good when quarried, has to be dressed or broken to shape by stone masons at great expense, after it has l^een set for the facing of walls, crumbles or is washed away by the weather, while made stone, being easily molded to any desired form, will prove to be a far more economical build- ing material than stone, and the most durable if properly made. Hollow walls of molded stone give a dead air space, and therefore tend to prevent sudden temperature changes within a building, rendering it cool in summer and more easily warmed in winter. The hollow spaces may also be utilized for ventilation and other purposes. STAIN. — To make a rich red-brown color for brown or red stone effect, or to renovate old stonework or brick- work, to fill up cracks, etc., use a thick wash made of the following: 4 ounces of white copperas cut in alcohol; 5 pounds of Prince's metallic dry; 3 gallons of sour lager beer; 2 good shovelfuls of Portland cement. Practical concrete-block making 35 Let one man keep stirring it continually, while another man brushes it on. Soak the concrete or stone wall and wash it thoroughly with water before applying the stain: Two coats are usually required on concrete, while one is generally sufficient on old stone or brickwork. If any- thing more is necessary to bring out the color effect, apply over it an ordinary brush coat of linseed oil. When dry you will not be able to either scrape or cut the color off without taking the wall with it, and it will wear, from my knowledge and experience with it, 25 years. This stain is excellent for chimney tops, old or new. Before applying, the dirt should always be washed off and joints pointed up with Portland-cement mortar 1 to 3, and colored. Add Venetian red if extra-rich brick-red is wanted. PORTLAND CEMENT=SAND BRICK HE manufacture of Portland cement-and-sand brick is far different from that of clay. Very small ^ expense is required in curing the product. Upon being made, they are allowed to remain on the pallets overnight, and the next day they are piled up, protected from the rays of the sun, and kept wet for 10 days, after which they are soon ready for the market and the build- ing operation. Clay and also sand-lime brick require a longer period of time, and a lot of heat, labor, and expense before they are 36 PRACTICAL CONCRETE-BLOCK MAKING fit to be placed in the wall ; besides an enormous outlay of money is required to equip such plants, while the expense incurred in instalhng a cement-sand brick plant, making six to ten bricks at each operation, may be from $100.00 up, and a small one can be operated in a cellar or basement, where I have known one to be run successfully, making 700 to 1,000 bricks daily by hand. There is a plant located in a city in northern New York, where also a high-grade Portland cement is likewise manu- factured. One brick machine is in operation (there are altogether about 25 similar plants in the United States and Canada), and I have gleaned the following particulars as to what is being accomplished there: 25,000 to 28,000 bricks are made daily, and the plant cost $15,000.00; the pressure applied to each brick in the press is 180 tons, and each thousand brick costs, to manufacture, all charges of every kind whatsoever included, as follows: Portland cement, H bbls. @ $1.30 $1.95 Sand, li yards 1.00 Labor, power, rent, and interest on cash investment 90 Total cost per 1,000 bricks $3.85 After expense of delivery, salesmen, and office staff, etc., has been allowed for, this plant earns a clear profit of $55.00 a day and sells all its product in the locality where it is established. One machine operating down on the Jersey coast, where the sand does not freeze and costs practically nothing, the PRACTICAL CONCRETE-BLOCK MAKING 37 plant heated in winter and running 300 days a year, making 25,000 bricks daily, would turn out 7,500,000 bricks which, if sold at the price of common stock brick, would net $3.00 to $4.00 per thousand, or $22,500.00 to $30,000.00 for the year's work; besides these bricks are classed with the best-pressed brick and would sell at a much higher price than the Jersey, red, half-baked, common, rotten brick Fig. 8 that there is so much trouble with every winter in the walls of a naturally very damp sea-air atmosphere, and especially when walls have been plastered with cement stucco for the outside. I have seen it time and again, and the brick were graded and sold for A No. 1 all hard-burned. What does common hard-burned clay brick and what does pressed brick cost you, and what does sand and also Portland cement cost you per barrel (car lots)? 38 PRACTICAL CONCRETE-BLOCK MAKING Molded and every shape and style of brick can be made for interior decorations, fireplaces, tiles, also for floors, etc. Colors can be used and they can also be made absolutely impervious to moisture by a little extra trouble in their manufacture, besides for facing up a concrete building to give a clear air space between them and the concrete wall, or for veneering a stud-frame concrete-filled structure, or otherwise, nothing can be better or more reasonable. There are vast architectural possibilities in this mate- rial in combination with concrete construction of founda- tion, cellar walls, underpinning, watertable, sills, hntels, quoins, voussoirs, door and window dressings, belt courses, friezes, cornices, columns, rails, steps, etc. Fig. 8 shows various forms of cement brick; an examination of these will show any one the possibiHties of effective combinations that can be had. WOODEN MOLDS WOODEN MOLDS that are to be used to make a number of blocks should be strongly made; they must be substantial enough to resist the pressure exerted by the tamping. The joints should be so arranged that the mixture will not leak out. Fig. 9 shows a view of a form of mold that will answer for nearly all purposes. It is constructed of wood 2 inches thick, and by removing the bolts, all the side pieces may PRACTICAL CONCRETE-BLOCK MAKING 39 be removed. Fig. 10 shows how the side pieces are framed and locked together by the bolt. When a wooden mold is to be used a number of times, it should be well painted, so as to prevent the moisture from warping the wood. A good paint for this purpose is made of § linseed oil and J paraffin oil. This not only preserves the mold, but allows the block to leave the mold more easily. To save material the blocks may be made hollow by inserting cores which are also made of wood. In using Fig. 9 cores be careful to always use rounded corners, as a crack is more likely to start from a square corner. The core should be slightly tapered, so that it may be easily with- drawn. So much for the plain mold, which is but seldom used for making common blocks. Now if it is desired to have a molding like Fig. 11, this could be easily cast in a mold in which plain pieces of wood and molding (protected with the paint already mentioned) are so arranged as to give 40 PRACTICAL, CONCRETE-BLOCK MAKING the required shape. These pieces of wood can be nailed to one side, so that it can be easily removed. An exami- nation of Fig. 12 will show the idea. In the case of lintels to place over window openings, the molding is returned at each end to the wall end. In cases of this kind the mold is made of the required size and the molding mitred, so as to make the proper form. The block-maker should keep on hand different kinds of moldings, so that he will be prepared to make up a variety of designs, and if he will turn out good, honest Fig. 10 work, and use a little ingenuity in preparing the molds, as outlined above, he will make a reputation for himself and his products, and will find himself recommended by archi- tects who want a good job done. Artistic effects can be had by making the blocks with plain faces on which raised festoons or other designs appear. Figs. 13, 14, and 15 will show a few examples of blocks with such designs. Ornamental blocks of this sort can be very easily made PRACTICAL CONCRETE-BLOCK MAKING 41 by having in stock a few stamped, galvanized-iron orna- ments, such as are used by cornice-makers, and which can be had quite cheaply. Pieces of wood a Uttle thicker than the depth of the Fig. 11 ornament are placed at the bottom of the mold, so as to leave a little more than the height of the ornament. The central portion is to be filled flush with plaster of Paris, Fig. 12 and the ornament placed in it downwards, thus forming a mold of the ornament. When the plaster has set, the Ornament is withdrawn and the mold is complete. To prevent the stamped, iron ornament from falling Fig. 15 PRACTICAL CONCRETE-BLOCK MAKING 43 too deep in the plaster, it should be nailed to a piece of board, as shown in Fig. 16. The ornament should be oiled to prevent its sticking to the plaster. The plaster should be allowed to harden thoroughly before the con- crete is placed in the mold. In practically every case the plaster mold will be found stuck to the cast, but this can be very easily dampened and scraped away. Of course with this method it is necessary to make a new mold of plaster for every block, as the plaster will last for only one casting. This, however, is a simple matter, as the molds are so easily made. a = handle, b = board, c= ornament, d= plaster. - Fig. 1G Many friezes and moldings that are suitable for concrete are made in stamped metal, and even if the block-maker has only a few of these, he can make unUmited designs by using them in different combinations. Of course these sheet-metal designs will not last like the cast-iron molds which the block-machine people fur- nish, but if they are backed up with a cement-and-sand mixture, so that they will not be crushed out of shape by the tamping, they will last long enough to turn out a number of creditable and original jobs. Fig. 17 46 practic;al concrete-block .making This suggestion of using stamped metal for forms will be a new one to most block-makers, but it is one worthy of thought, as it will enable one to create something dif- ferent. There has been too much sameness about con- crete blocks. It will be found that even if a small selection of the stamped, iron ornaments and borders are kept on hand, Fig. 19 they will open a field to the ambitious block-maker to carry out the original ideas of architects, which under ordinary conditions would be impracticable. Fig. 17 gives designs of a few ornaments which cajti be had in stamped metal, and Fig. 18 gives some suitable borders. When large ornamental pieces like Fig. 19 are cast, it is well to reinforce them. A simple and good way is to PRACTICAL CONCRETE-BLOCK MAKING 47 use a mesh wire screen cut to the shape of the casting and well imbedded. A design similar to Fig. 19 (size about 16'''X29") can be had for a few dollars and can be cast without much trouble in the manner just described. The architectural value of such an ornament in a large unbroken wall of blocks needs no further mention, as it speaks for itself, turning a dull, monotonous expanse of rectangular block wall into a suitable background, and forming an object of beauty. A little ornament used with taste goes a very long way. ARE ARCHITECTS AND BUILDERS AGAINST THE USE OF THE COMMON CONCRETE BLOCK, AND WHY? SINCE the concrete block is more convenient, more efficient, and cheaper than other building material, it would naturally follow that it should rapidly jump into favor, taking the place of wood, brick, and stone, and be generally adopted for all ordinary construc- tion. The growth of the block industry has indeed been phenomenal, pushed mushroom-like by the machine manu- facturers, but it is not a healthy growth — too much slash- ing and cutting — and even yet it plays but a small part in the building operations of the country. It is quite evident oh all sides that concrete blocks meet with opposi- tion and suspicion on the part of architects and builders. 48 PRACTICAL CONCRETE-BLOCK MAKING and in consequence are much less generally adopted than their merits would appear on the surface to warrant. It is neither just nor expedient to attribute this opposition to prejudice against a new material, as it is not a new material, as I have already shown. The machine manu- facturers and the block-makers must get down to busi- ness and remove the real grounds on which the opposition is based to the common-style concrete block as now pro- duced. Architects and engineers have no prejudice against concrete, but, on the contrary, welcome it as a building material by means of which they can obtain results never before within their reach. They are also keenly watching the block industry, and are ready to adopt block con- struction as soon as they can secure a product which meets their ideas as to utility and beauty. Fortunately no material is so elastic in its capabilities as concrete, and' no other can with so little efTort be adapted to produce any effect desired. It is hardly expected that the block of the present day will be the block of the future; the type which is most economical, practical, and artistic will gradually come to the front, and that which is costly, clumsy, and ugly will become a thing of the past. To make a success the manufac- turer must study the wants of cultivated taste also, and must not hesitate to throw the old block machines into the scrap heap, and get up to date, with the latest ideas, processes, and machinery. Of course this seems like throw- ing good money away, but the greater sales due to an improved block will make it a paying proposition. BSlii PRACTICAL CONCRETE-BLOCK MAKING 49 The objections which, architects and builders make to blocks now on the market are chiefly the following: 1st. Poor materials and workmanship. 2d. Fixed and monotonous dimensions. 3d. Too heavy for ease of handling. 4th. Inartistic appearance in the wall. With reference to material and work, shoddy, weak, and crumbling blocks are far too often met with. Good concrete should be hard and dense, and should ring like metal when struck with a hard substance. If the blocks sound dead when struck and break easily with an earthy fracture, the mixture has been too poor, or the working too dry. It don't pay, for the sake of low, factory cost, to turn out work of this kind. You may be certain of one thing, and that is, if there is any money to be made in the concrete-block business, it will be made by supplying only a first-class article at a living price, and not in any other way. Will any one argue that it pays to make rotten blocks at a factory cost of a cent or two less than good ones? A man will soon be known by the blocks he makes, and if they are rotten, he will soon be down and out. As to fixed dimensions of blocks, the standard length of 32 inches, divided into halves, thirds, and quarters, is very convenient, and is generally conformed to, even by architects, for simple work, without great objection. To be fully successful, however, and to overcome all prejudice, the block-maker must be ready to furnish any size or shape that may be called on to suit architectural work. 50 PRACTICAL CONCRETE-BLOCK MAKING It would be very nice for the block-maker if he could confine himself to a size and let customers "take it or leave it." But such an attitude bars the way to any wide use of blocks in varied and attractive buildings, and can- not long be maintained without loss of trade. Architects also want courses of greater or less height than the 9-inch standard, and all manner of copings, water- tables, sills, belts, cornices, columns, balustrades, and capi- tals. All this may frighten the timid and conservative block-maker, but it is in that direction that success lies, and the production of these special shapes and sizes requires only ingenuity, courage, and mechanical skill. Until the architect can design whatever he desires to, knowing it will be produced, he will be shy of the block-maker and his product. He will, of course, readily appreciate that special shapes cost more than standard, and if he knows he can get just what he wants, he will be more likely to accept, as far as possible, what can be conveniently and cheaply furnished. Preference should be given, therefore, by the block- maker, to the machinery or appliances which will permit of the greatest variety of manufacture; and the greatest business success is most likely to come to him who shows the least inclination to get into a rut, and is most ready to adapt his product to the wants of his patrons. The objection to the weight of one-piece block comes chiefly from masons and contractors. Hoisting 12"X32" blocks weighing 180 lbs. to the upper stories of a building, and placing them in the wall, is a considerable task, and it PRACTICAL CONCRETE-BLOCK MAKING 51 is largely on this account that the half-block of the two- piece system, 24 inches long, weighing only 64 lbs., is received with so much favor. It must be remembered, however, that the two-piece blocks make a wall with over 50% opening, and a one-piece block of the same thickness of surfaces — 2J inches — would also be light to handle, and doubtless very popular. The one-piece block of the future should be 24 inches long, with a thickness of surfaces of not over 3^ inches. Such a block, 12 inches wide and 9 inches high, will weigh about 100 lbs., and if well and strongly tied with light material and honestly made, will bear required handling and stress. But it is to the appearance of concrete blocks, as regu- larly made and used, that architects and others of taste and sound judgment in such matters make the greatest objection. Anything that savors of imitation, that pre- tends to be what it is not, will always be condemned by those who know the difference between the good and the bad in architecture. The common concrete block is an attempt at imitation of rock-faced quarry stone; no two natural stones will break alike on the face, so the block machine furnishes a few different rock-faced plates of the same size of block, while the great beauty of a rock-faced stone ashlar is the irregularity in the sizes, etc., of the whole, with the exception of level beds and plumb-cut joints. And the block-maker strives as best he can to shuffle up his product from his different face plates, but his labor and shuffling are in vain. It is surprising how unerringly the eye will pick out the spots where two of a 52 PRACTICAL COxsCi^KTE-BLOCK MAKING kind will have flocked together in the wall, and not as the Dutchman had it— "Birds of a feather go one by himself." Something wrong is quickly detected. It is an eyesore, and very objectionable bad art. The ''rock-faced galvanized iron" of our village and town store fronts is a no more glaring fraud. The imita- tion rock-faced block has been weighed in the balance and has been found to be sadly wanting, and the verdict is, "It must go!" The fine-brick manufacturers make rock-faced brick in a rational way that have not the above objections. Why did the concrete-block man not follow in his steps if he was called on to produce such material by the archi- tectural fraternity, which I very much doubt? No, it is the machine man and those who have no taste in matters of art who are responsible for this monstrosity. Now let us inquire what is imitation, and how concrete may be made to stand on its merits and look like what it really is — a cast, artificial stone, which cannot help look- ing like natural sandstone or hmestone made up of the same materials, bound together by carbonate of lime or soluble siUcates slowly deposited in its pores. We need never be afraid that concrete will be condemned for its stony look, since that is its nature. All one need avoid is giving the work an appearance which is unnatural, such as the rock-face. Smooth, rough, ribbed, and paneled surfaces are also good ornamental patterns for friezes or belt courses, and are entirely legitimate and equally char- acteristic of terra cotta or concrete. Follow terra cotta and PRACTICAL CONCRETE-BLOCK MAKING 53 you will be right, but keep shy of galvanized iron and the metal designs and tin cornices, etc., etc. The thing to be avoided is pretense — the attempt to deceive the observer into the belief that the material he sees is something dif- ferent from what it really is. "All things are not what they seem." The surface that best satisfies the eye of the architect and critic is a rough and varied one, rather than the very smooth, glassy, and dead look which rich cement mixtures have. The film of cement which coats the face of the work is certainly monotonous and unattractive; besides it is very liable to hair crack. This film can readily be removed, and very beautiful effects are thus obtained, especially when crushed stone or beach gravels containing pebbles of various colors have been used. STANDARD SPECIFICATIONS FOR BLOCKS MANY failures of buildings of concrete blocks have occurred, due to the ignorance of the makers, and the fault is blamed on concrete rather than on the makers, who are at fault. The National Association of Cement Users, realizing the above facts, appointed a committee to investigate the industry, and to make experiments and investigations. The results of their experience were embodied in a stand- ard form of specifications. These specifications are prac- 54 PRACTICAL CONCRETE-BLOCK MAKING tically the same as the directions previously given, but it will be of interest to have them for reference in this book. The specifications are as follows: Concrete hollow blocks made in accordance with the following specifications, and meeting the requirements thereof, may be used in building construction, subject to the usual form of approval required of other materials of construction by the Bureau of Building Inspection. 1. CEMENT. — The cement used in making sand blocks shall be Portland cement, capable of passing the require- ments as set forth in the "Standard Specifications for Cement " by the American Society for Testing Materials. 2. SAND. — The sand used shall be suitable siliceous material, passing the one-fourth-inch-mesh sieve, clean, gritty, and free from impurities. 3. STONE OR COARSE AGGREGATE.— This material shall be clean, broken stone, free from dust, or clean, screened gravel passing the three-quarter-inch- and refused by the one-quarter-inch-mesh sieve. 4. UNIT OF MEASUREMENT.— The barrel of Port- land cement shall weigh 380 pounds net, either in barrels or subdivisions thereof, made up of cloth or paper bags, and a cubic foot of cement shall be called not to exceed 100 pounds or tjie equivalent of 3.8 cubic feet per barrel. Cement shall be gauged or measured either in the original package as received from the manufacturer, or may be weighed and so proportioned; but under no circum- stances shall it be measured loose in bulk. 5. PROPORTIONS.— For exposed exterior or bear- PRACTICAL CONCRETE-BLOCK MAKING 55 ing walls: (a) Concrete hollow blocks, machine made, using semi-wet concrete or mortar, shall contain one (1) part cement, not to exceed three (3) parts sand, and not to exceed four (4) parts stone, of the character and size before stipulated. When the stone shall be omitted, the proportions of sand shall not be increased, unless it can be demonstrated that the percentage of voids and tests of absorption and strength allow in each case of greater proportions, with equally good results. (6) When said blocks are made of slush concrete in individual molds and allowed to harden undisturbed in same before removal, the proportions may be one (1) part cement to not to exceed three (3) parts sand and five (5) parts stone, but in this case also, if the stone be omitted the proportion of sand shall not be increased. 6. MIXING.— Thorough and vigorous mixing is of the utmost importance. (a) Hand Mixing— The cement and sand in correct proportions shall first be perfectly mixed dry; the water shall then be added carefully and slowly in proper propor- tions, and thoroughly worked into and throughout the resultant mortar; the moistened gravel or broken stone shall then be added, either by spreading same uniformly over the mortar, or by spreading the mortar uniformly over the stones, and then the whole mass shall be vigorously mixed together until the coarse aggregate is thoroughly incorporated with and distributed throughout the mortar. (h) Mechanical Mixing— Preference shall be given to mechanical mixers of suitable design, and adapted to the 56 PRACTICAL CONCRETE-BLOCK MAKING particular work required of them; the sand and cement, or sand and cement and moistened stone shall, however, be first thoroughly mixed before the addition of water, and then continued until the water is uniformly distributed or incor- porated with the mortar or concrete, provided, however, that when making slush or wet concrete (such as will quake or flow), this procedure may be varied with the consent of the Bureau of Building Inspection, architect or engineer in charge. 7. MOLDING.— Due care shall be used to secure density and uniformity in the blocks by tamping or other suitable means of compression. Tamped blocks shall not be finished by simply striking off with a straight-edge, but, after strik- ing off the top surfaces, shall be troweled or otherwise finished to secure density and a sharp and true arris. 8. CURING.— Every precaution shall be taken to pre- vent the drying out of the blocks during their initial set and first hardening. A sufficiency of water shall first be used in the mixing to perfect the crystaUization of the cement, and, after molding, the blocks shall be carefully protected from wind currents, sunlight, dry heat, or freez- ing, for at least five (5) days, during which time additional moisture shall be supphed by approved methods, and occasionally thereafter until ready for use. 9. AGING.— Concrete hollow blocks in which the ratio of cement to sand be one-third (J) (1 part cement to 3 parts sand) shall not be used in the construction of any building in the (City) of ^ until they have attained the age of not less than three (3) weeks. PRACTICAL CONCRETE-BLOCK MAKING 57 Concrete hollow blocks in which the ratio of cement to sand be one-half (J) (1 part cement to 2 parts sand) may be used in construction at the age of two (2) weeks, with the special consent of the Bureau of Building Inspection and the architect or engineer in charge. Special blocks of rich composition, required for closures, may be used at the age of seven (7) days, with the special consent of the same authorities. The time herein named is conditional, however, upon maintaining proper conditions of exposure during the curing period. 10. MARKING. — All concrete blocks shall be marked for purposes of identification, showing name of manufac- turer or brand, date (day, month, and year) made, and composition or proportions used, as, for example, 1-3-5, meaning 1 cement, 3 sand, and 5 stone. 11. THICKNESS OF WALLS.— The thickness of bear- ing walls for any building where concrete hollow blocks are used may be ten (10) per cent less than is required by law for brick walls. For curtain walls or partition walls, the requirements shall be the same as in the use of hollow tile, terra-cotta, or plaster blocks. 12. PARTY WALLS.— Hollow concrete blocks shall not be permitted in the construction of party walls, except when filled soHd. 13. WALLS, LAYING OF.— Where the face only is of hollow concrete block, and the backing is of brick, the facing of hollow block must be strongly bonded to the brick either with headers projecting four (4) inches into 58 PRACTICAL C0NCRP:TE-BL0CK MAKING the brickwork, every fourth course being a heading course, or with approved ties; no brick "backing to be less than eight (8) inches. Where the walls are made entirely of concrete blocks, but where said blocks have not the same width as the wall, every fifth course shall extend through the wall, forming a secure bond, when not otherwise suf^ ficiently bonded. All walls, where blocks are used, shall be laid up with Portland-cement mortar. 14. GIRDERS OR JOISTS.— Wherever girders or joists rest upon walls so that there is a concentrated load on the block of over two (2) tons, the blocks supporting the girder or joists must be made solid for at least eight (8) inches from the inside face. Where such concentrated load shall exceed five (5) tons, the blocks for at least three courses below, and for a distance extending at least eighteen (18) inches each side of said girder, shall be made solid for at least eight (8) inches from the inside face. Wherever walls are decreased in thickness, the top course of the thicker wall shall afford a full, sohd bearing for the webs or walls of the courses of blocks above. 15. LIMIT OF LOADING. — No wall, nor any part thereof, composed of concrete hollow blocks, shall be loaded to an excess of eight (8) tons per superficial foot of the area of such blocks, including the weight of the wall, and no blocks shall be used in bearing walls that have an aver- age crushing strength of less than 1,000 pounds per square inch of area, at the age of twenty-eight (28) days; no deduction to be made in figuring the area for the hollow spaces. 16. SILLS AND LINTELS.— Concrete sills and lintels PRACTICAL CONCRETE-BLOCK MAKING 59 shall be reinforced by iron or steel rods in a manner satis- factory to the Bureau of Building Inspection and the archi- tect or engineer in charge, . and any hntels spanning over 4 feet, 6 inches shall rest on block solid for at least 8 inches from the face next to the opening and for at least three courses below the bottom of the lintel. 17. HOLLOW SPACE.— The hollow space in building blocks used in bearing walls shall not exceed the percentage given in the following table for different -height walls, and in no case shall the walls or webs of the block be less in thickness than one-fourth their height. The figures given in the table represent the percentage of such hollow space for different-height walls. Stories. 1st. 2d. 3d. 4th. 5th. 6th. 1 and 2 33 33 3 and 4 25 33 33 33 5 and 6 20 25 25 33 33 33 18. APPLICATION FOR USE.— Before any such mate- rial be used in buildings, an application for its use and for a test of the same must be filed with the Bureau of Build- ing Inspection, In the absence of such a Bureau, the application shall be filed with the chief of any department having such matters in charge. A description of the mate- rial and a brief outline of its manufacture and proportions used must be embodied in the application. The name of the firm or corporation, and the responsible officers thereof, shall also be given, and changes in same thereafter promptly reported. 60 PRACTICAL CONCRETE-BLOCK MAKING 19. PRELIMINARY TEST.— No hollow concrete blocks shall be used in the construction of any building unless the maker of said blocks has submitted his product to the full tests required herein, and placed on file with the Bu- reau of Building Inspection, or other duly authorized official, a certificate from a reliable testing laboratory, showing that representative samples have been tested and success- fully passed all requirements hereof, and giving in detail the results of the tests made. No concrete blocks shall be used in the construction of any building until they have been inspected and approved, or, if required, until representative samples be tested and found satisfactory. The results of all tests made, whether satisfactory or not, shall be placed on file in the Bureau of Building Inspection. These records shall be open to inspection upon application, but need not necessarily be pubUshed. 20. ADDITIONAL TESTS.— The manufacturer and user of such hollow concrete blocks, or either of them, shall at any and all times have made such tests of the cements used in making such blocks, or such further tests of the completed blocks, or of each of these at their own expense, and under the supervision of the Bureau of Building Inspec- tion, as the chief of said Bureau shall require. In case tlje result of tests made under this condition should show that the standard of these regulations is not maintained, the certificate of approval, issued to the manu- facturer of said blocks, will at once be suspended or revoked. 21. CERTIFICATE OF APPROVAL.— Following the PRACTICAL CONCRETE-BLOCK MAKING 61 application called for in clause No. 18, and upon the satis- facLory conclusion of the tests called for, a certificate of approval shall be issued to the maker of the blocks by the Bureau of Building Inspection. This certificate of approval will not remain in force for more than four months, unless there be filed with the Bureau of Building Inspection, at least once every four months following, a certificate from some reliable physical testing laboratory, showing that the average of at least three (3) specimens tested for com- pression, and at least three (3) specimens tested for trans- verse strength, comply with the requirements herein set forth. The said samples to be selected by a building inspec- tor, or by the laboratory, from blocks actually going into construction work. 22. TEST REQUIREMENTS.— Concrete hollow blocks must be subjected to the following tests— transverse, com- pression, and absorption — and may be subjected to the freezing and fire tests, but the expense of conducting the freezing and fire tests will not be imposed upon the manu- facturer of said blocks. The test samples must represent the ordinary commercial product of the regular size and shape used in construction. The samples may be tested as soon as desired by the appli- cant, but in no case later than sixty days after manufac- ture. Transverse Test. — The modulus of rupture for concrete blocks at 28 days must average one hundred and fifty, and must not fall below one hundred in any case. Compression Test. — The ultimate compressive strength 62 PRACTICAL CONCRETE-BLOCK MAKING at 28 days must average one thousand (1,000) pounds per square inch, and must not fall below seven hundred in any case. Absorption Test. — The percentage of absorption (being the weight of water absorbed, divided by the weight of the dry sample) must not average higher than 15%, and must not exceed 22% in any case. 23. CONDEMNED BLOCK.— Any and all blocks, sam- ples of which, on being tested under the direction of the Bureau of Building Inspection, fail to stand at twenty- eight (28) days the tests required by this regulation, shall be marked condemned by the manufacturer or user, and shall be destroyed. 24. CEMENT BRICK.— Cement brick may be used as a substitute for clay brick. They shall be made of 1 part cement to not exceeding 4 parts clean, sharp sand, or 1 part cement to not exceeding 3 parts clean, sharp sand and 3 parts broken stone or gravel passing the one-half- inch and refused by the one-quarter-inch-mesh sieve. In all other respects cement brick must conform to the require- ments of the foregoing specifications. The foregoing specifications, together with previous direc- tions, cover practically the whole subject of the making of concrete blocks. To be successful in this line of manufac- turing, you must produce a first-class block, and this can be done by strictly following these rules and directions. Show that you have faith in blocks by building your office with them. Be enthusiastic and you will succeed. PRACTICAL CONCRETE-BLOCK MAKING 63 TESTING HOLLOW CONCRETE BLOCKS ON important work, especially for factories and warehouses which are to carry heavy loads on the floors, it is a good plan to test the blocks. The rules adopted by the National Association of Cement Users are good ones to follow; they are as follows: 1. All tests required for approval shall be made in some laboratory of recognized standing, under the supervision of the engineer of the Bureau of Building Inspection, or the architect or engineer in charge, or all of these. The manufacturer may be present or represented, during said tests, if he so desires. Approval tests are made at the expense of the applicant. 2. For the purposes of the tests, at least twelve (12) samples or test pieces must be provided. Such samples must represent the ordinary commercial product and may be selected from stock by the Bureau of Building Inspec- tion, or in the absence of such a Bureau, by the architect or engineer in charge. In cases where the material is made and used in special shapes or forms too large for testing in the ordinary machines, smaller-sized specimens shall be used, as may be directed. 3. In addition to the tests required for approval, the weight per cubic foot of the material must also be obtained and recorded. 64 PRACTICAL CONCRETE-BLOCK MAKING 4. Tests shall be made in series of at least three (3), except that in the fire tests a series of two (four samples) are sufficient. Transverse tests shall be made on full-sized samples. Half samples may be used for the crushing, freezing, and fire tests. The remaining samples are kept in reserve in case duplicate or confirmatory tests be required. All sam- ples must be marked for identification and comparison. 5. The transverse test shall be made as follows: The samples shall be placed flatwise on two rounded knife- edge bearings set parallel 7 inches apart. A load is then applied on top, midway between the supports, and trans- mitted through a similar rounded knife edge, until the sample is ruptured. The modulus of rupture shall then be determined by multiplying the total breaking load in pounds by twenty-one (three times the distance between supports in inches), and then dividing the result thus obtained by twice the product of the width in inches by the square of the depth in inches: 3WL ^ 2hd?' No allowance should be made in figuring the modulus of rupture for the hollow spaces. 6. The compression test shall be made as follows: Sam- ples must be cut from blocks so as to contain a full web section. The sample must be carefully measured, then bedded flatwise in plaster of Paris, to secure a uniform bearing in the testing machine, and crushed. The total PRACTICAL CONCRETE-BLOCK MAKING 65 breaking load is then divided by the area in compression in square inches. No deduction is to be made for hollow spaces; the area will be considered as the product of the width by the length. 7. The absorption test shall be made as follows: The sample is first thoroughly dried to a constant weight, at not to exceed 212° F. The weight must be carefully recorded. It is then placed in a pan or tray of water, face downward, immersing it to a depth of at least 2 inches. It is again carefully weighed at the following periods: 30 minutes, 4 hours, and 48 hours, respectively, from the time of immersion, being replaced in the water in each case as soon as the weight is taken. Its compressive strength while still wet is then determined at the end of the 48-hour period, in the manner specified in section 6. 8. The freezing test shall be made as follows: The sam- ple is immersed, as described in section 7, for at least 4 hours, and then weighed. It is then placed in a freezing mixture or a refrigerator, or otherwise subjected to a tem- perature of less than 15° F. for at least 12 hours. It is then removed and placed in water, where it must remain at least 1 hour, the temperature of which is at least 150° F. This operation is repeated ten (10)' times, after which the sample is again weighed while still wet from the last thaw- ing. Its crushing strength should then be determined as called for in section 6. 9. The fire test is made as follows: Two samples are placed in a cold furnace in which the temperature is grad- ually raised to 1,700° F. The test piece must be sub- 66 PRACTICAL CONCRETE-BLOCK MAKING jected to this temperature for at least 30 minutes. One of the samples is then plunged in cold water (about 50° to 60° F.) and the results noted. The second sample is permitted to cool gradually in air, and the results noted. 10. The following requirements must be met to secure an acceptance of the materials: The modulus of rupture for concrete blocks at 28 days old must average one hun- dred and fifty and must not fall below one hundred in any case. The ultimate compressive strength at 28 days must average one thousand pounds per square inch and must not fall below seven hundred in any case. The percentage of absorption (being the weight of water absorbed divided by the weight of the dry sample) must not average higher than 15% and must not exceed 22% in any case. The reduction of compressive strength must not be more than 33J%, except that when the lower figure is still above one thousand pounds per square inch, the loss in strength may be neglected. The freezing and thawing process must not cause a loss in weight greater than 10%, nor a loss in strength of more than 33J%, except that when the lower figure is still above one thousand pounds per square inch, the loss in strength may be neglected. The fire test must not cause the material to disintegrate. INDEX A PAGE Absorption test 61, 65, 66 Advantages of concrete 27 Advantages of concrete construction 33 Aggregate 9, 14, 54 Aging 56 Air space 12, 34, 59 Appearance of blocks 51, 53 Architects attitude towards blocks 47 Artificial stone 52 B Bank gravel 14 Batch 9 Blocks, different forms of 13 Blocks, directions for manufacturing 14 Blocks, facing : 16 Blocks, ornamental 42 Blocks, sand-cement 15 (67) 68 INDEX PAGE Blocks, to make economically 18 Blocks, where they should be made 21 Bonding 23 Borders 18 Brick, art in cement 36 Brick, cement-sand 12, 35, 62 Brick, faUing apart 33 Brick, forms of cement 37 Brick, sand-lime 12 Brickwork 34 Builders' attitude towards blocks 47 Building with blocks 23 C CapabiUties of concrete 48 Cast stone 52 Cement 8, 14, 54 Cement, amount of 15 Cement brick 12, 35, 62 Cement bricks, cost of 36 Cement bricks, forms of 37 Cement, cr3^stanization of 9, 22 Cement, weight of a barrel of 54 Coloring 23, 31 Compression test 61, 64, 66 Concrete 8 Concrete-block machines 11, 12 Concrete blocks 7, 9 INDEX 69 PAGE Concrete, strength of fresh 29 Condemned block 62 Cores 39 Cost of making blocks 30 Cost of making brick 36 Crushed stone 14 Crystallization of cement, proper time for 22 Crystallizing of cement 9 Curing 21, 56 D Damp-proof blocks 32 Dimensions of blocks 49 Disintegration 66 Disintegration of bricks 33 Drying 21 Drying, to prevent rapid 22 Dry mix 9 E Economy in making blocks 18 F Faced blocks 16 Festoons 44 Fining molds 17 Fire test. ; 65, 66 Freezing test. . . .•. . ;% . \\: w' j • ••• • •:• •65i* $6: * 70 INDEX G FAQE Galvanized-iron effects 53 Galvanized-iron ornaments 41 Girders 58 Good blocks 49 Gravel 14 Green stone 21 H Hand mixing 55 Hardening 28 Hardening of blocks 21 Hints 25 Hollow blocks 12 Hollow spaces 59 Hollow walls 34 I Ignorance in using concrete 28 Imitations 51, 52 J Joists 58 L Laying of walls 57 Lintels. . . ^ 40, 58 : *Li)a3i pri w^lj.*.* • !• • ;•*:• :• • •:• ); j-f /A- V:- 58 INDEX 71 M PAGE Machine, selecting a 12 Manufacturing 14 Marking blocks *. 57 Mechanical mixing 55 Mix, dry 9 Mix, wet 9 Mixes 26 Mixing 16, 55 Moistening 22 Molding 56 Molds 9 Molds, fining 17 Molds, oiling • 39 Molds, plaster 41 Molds, wooden 38 Monotonous appearance 53 Moulding, making up original 40 Mouldings 18 Mouldings, molds for 39 O Objections to blocks 49 Ornamental blocks 42 Ornaments • 41 > Orn?niients, reinforced 46 72 INDEX P Pallet, Party walls 57 Placing 23 Plaster molds 42 Poor work Pressure 29 Profits in blocks 3O Proportions 26 Proportions of aggregate 54 R Renovating old walls, 34 66 31 Requirements of blocks, Rock facing S Sand Sand, cement blocks. 14, 54 15 14 25 12 28 22 49 58 49 Sand, quality of. Sand, screening. •Selecting a machine Set Set, proper time to Shoddy work, Sills, Sound of blocks. INDEX 73 PAGE Specifications 53 Sprinkling 22 Stain 34 Standard specifications 53 Stone, artificial cast 52 Stone, crushed 14 Stone, natural 34 Storing 22 Strength of blocks 21 Strength of fresh concrete 29 Success in concrete work 48 Suggestions 25 Sun, protection from 21 Surfaces 52 T Tamping 26, 29 Terra cotta 52 Test requirements 61 Tests 60, 63 Thickness of walls 57 Ties 32 Transverse test 61, 64 Tray 21 U Unnatural blocks 52 Using fresh blocks 22 74 INDEX V PAGE Voids 14 Voids, determination of 15 W Walls, hollow 34 Walls, laying of 57 Walls, load on 58 Walls, party 57 Walls, thickness of 57 Water absorbed by sand. .> 15 Water, too much 28 Water used for mixing 25 Waterproof block 32 Waterproofing • • 24 Weight of blocks 50 Wet mix ^ Wet process 1'' Wetting 22 Wooden molds 38 Wooden molds, painting 40 Modem Cement Sidewalk Construction A PRACTICAL TREATISE FOR THE WORKMAN By Chawrles Pes.lliser 64 Pages (5x7 inches) Fully Ill\;strated Handsomely bound in cloth PRICE, 50 CENTS Sent post-paid oo receipt of price Your money back if you are not pleased -•■THE construction of cement sidewalks, curbs and gutters ill is thoroughly explained in this book, full directions being given regarding the selection and testing of the cement, sand, stone, gravel, etc.; the special tools used; the laying, finishing, seasoning, coloring, etc. ; together with ad- vice on dealing with customers, and data regarding the actual cost of several jobs, with the complete specifications of each. The methods of work have been tried over and over again by the author in his many years of experience and always with success ; and anyone following these directions will be able to lay a cement sidewalk that will last for years without rearing up, cracking or crumbling. The simplest language has been used throughout the book, all technical terms, etc., being fully explained. Contains many valuable pointers for the experienced cement-mason as well as the beginner. INDUSTRIAL PUBLICATION CO. 16 Thomas Street New York 15he STEEL SQUARE AS A CaLlculating Machine BY ALBERT FAIR 81 Pa.ges: IllustraLted ; Handsomely Bound in Cloth PRICE 50 CENTS, POSTPAID THE ordinary steel square is generally looked upon as a tool peculiar to the kit of the carpenter, and used solely for laying out work, mark- ing off cuts and angles and "squaring up." By most other trades it is used chiefly for testing the "squareness" of their work. It has been found, however, that a well-made square, with the edges accurately graduated or divided into inches or parts of an inch, may be used for making calculations which, if performed by figures on paper by means of a pencil, would take hours, whereas by the Steel Squar.i they may be solved in minutes without any calculation whatever. And it is a well known fact that very few mechan- ics are able to make complicated calculations involving questions of square and cube roots, values, etc. But by means of the Steel Square and a simple Index-guide which is clearly described in this book, and which any mechanic can make for himself in a few minutes, many of the most important problems may be solved instantly and accurately, while the methods by which the work is done are so simple and so easily learned that as soon as the use of the grad- uated square for this purpose becomes known, no machinist, plumber, electri- cian, steam-user or other practitioner of any of the higher mechanical trades will feel that he can afford to be without oue, for it is safe to say that any in- telligent mechanic who owns a good square and this book will find that on two or three ordinary jobs they will save him, in time and worry, more than ten times their cost. While this has been known for a long time, yet thus far and up to the pub- lication of the present volume there has been no text-book in which the prin- ciples according to which these calculations might be made were explained. In this volume, however, the author gives not only clear and accurate explan- ations of these principles, but simple and easily followed directions for putting them in practice. The book is written in the very simplest language ; no X y — z formulae, and no such expressions as " cos diedral miter = rise cos half -corner angle c" to confuse the workman. IndustridLl Pxiblicattion Co. 16 Thomas Street New Vork A NEW BOOK ON THE SQUARE The Steel Square Pocket Book A Practica.1 and Handy Treatise Giving the Best Methods of Using the Carpenter's Steel Square By D. L. STODDARD 109 PaLges: 112 Illustra^tions ; Cloth Bound Price 50 cents, postptvid The size of this book enables it to be carried in the pocket, hence the carpenter can always refer to it for the method of finding the different cuts used in roof framing, stair work, hoppers, towers and bicycle tracks ; also directions for de- scribing hexagons, octagons and other polygons, circles, ovals, ellipses, brace measurement, dividing a cone, facia and frieze cuts, besides directions in clear language for solving other knotty problems by the use of the square. This book is thoroughly original ; every cut is new and specially made for it. One new feature which will commend itself to mechanics is the absence of reference letters on the illustrations, therefore the reader will have no trouble in look- ing for the various A, B, C's, etc, which are sometimes con- fusing to beginners. Instead of having to hunt for letters, the reader will find an exact engraving of the square itself laid on the work so as to give the points, lengths and quantities sought. This is a boiled-down compendium of information about the square which can be referred to quickly, having a thorough index. Industria-l PublicaLtion Co. 16 ThomaLS Street. New York Short Cuts in Carpentry A COLLECTION OF NEW AND IMPROVED METHODS OF LAYING OUT AND ERECTING CARPEN- TERS' AND JOINERS' WORK By ALBERT FAIR 80 PAGES (5x7 inches) 75 ILLUSTRATIONS Handsomely bound In Cloth PRICE, 50 CENTS Sent post-paid on receipt of price Your money bacic if you are not pleased ^-rO LAY OUT and erect carpenters' work accurately and IH quickly is an accomplishment desired by all progressive ^ carpenters. In this book, not only the simple rules for the short cut are given, but also the "reason why," so that the carpenter can apply his knowledge to many problems besides those given in this book. The book contains remarks about the carpenter and his work, a large folding plate showing the interior of a house with each part named, the use of geometry, mitreing, mitre boxes, mitres for curved moldings, various kinds of molding, bending moldingsaround circles, rake moldings, kerfing, brackets for coves, use of the steel square, use of 2-foot rule, use of glue working hardwood, blind nailing, setting door jambs, hanging doors, fitting doors and windows, framing, siding, shingling framing a floor with short timbers, building up a beam, laying floors, wood carpet, dished floors, veneering, inlaying, roof framing simply explained, braces, hoppers, wheat bins, 'fence posts, shaping a flag pole, bevel of tank staves, well curbs etc etc. ' INDUSTRIAL PUBLICATION CO. 16 Thomas Street New York DON'T CUT AND TRY ? ^ But Lay Out Your Work Accurately by Up-to-Date Methods ^ 5 ^ ? ROOF FRAMING MADE EASY A Practical and Easily-Ujiderstood System of Laying Out and Framing Roofs Adapted to Modern Building Construction. The Methods ara Made Clear by Nearly 100 Large & Clear Engravings By OWEN B. MAGINNIS. Architect Inspector of Buildings of the City of New York Author of *' How to Frame a House," " Hotv to Measure Up Woodtuork for Buildings,^'' '"Bricklaying,^^ etc., etc. Second Edition. Revised and Greatly Enlarged. Now Ready ? ? Over 160 Octavo Pages, Handsomely Bound In Cloth 9 ) PRICE $1.00 PREPAID THE carpenter or builder who will study the methods de- scribed in this book will realize the constructive value of every piece of timber which enters into a framed roof and will understand how to lay out every piece of timber used without wasting valuable time and material cutting and trying. The language used is that of the practical workman — scien- tific phrases and confusing terms have been avoided where possible — and everything has been made so plain that any one who will faithfully study the book will understand it from be- ginning to end. In fact, every problem in the book was " tried" on a boy who had had no experience in building work, and he understood every problem with a little study. This will show that the book is valuable to the beginner as well as the ad- vanced workman. Any intelligent mechanic will be able to save at least ten times the cost of this book in time and material during the first few weeks that he has it in use. INDUSTRIAL PUBLICATION CO. p. o. Box 1852 16 Thomas Street, N. Y. HOW TO READ PLANS A VALUABLE NEW BOOK By Charles G. Peker 60 PAGES (5x7 Inches) 43 DRAWINGS IN TEXT 8 LARGE FOLDING PLATES Handsomely Bound in Cloth PRICE, 50 GENTS Sent post paid on receipt of pric Your money back if you are not pleased. ANY building mechanics are handicapped from getting u/jr/ more pay because they are unable to read plansand work from a drawing. Of course the best way is to learn how to draw ; but many mechanics cannot afford the time for the necessaiy practise. It is for these men that this book was prepared, as the author simply explains the meaning of the various lines, plans, views, elevations, sections, scales, blue prints, devices, symbols, etc., to be found on a set of plans. Each subject is taken up and explained and illustrated separately, and then a full complete set of architect's plans for a frame house is taken up and explained so that the reader will be sure to understand how to read plans. The book is finely illustrated by 43 illustrations in the text, and 8 large folding plates giving the full plan of a 6 room frame house. This set of plans alone is worth many times the cost of the book ; an architect would charge at least $25 for their equal. The useful suggestions, hints, etc., in this book will make it of value to even those who understand how to draw as well as those who do not. It is one of the most valuable books ever got out for build- ing mechanics, as its information means increasing a man's salary. It is pretty safe to say that to the man who cannot read a drawing now this book will mean at least $50 more pay during the first year he has it. Industrial Publication Co. 16 Tkomas Street ( Over) New York