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CORNELL 
 
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Cornell University Library 
 TH 1461.W31 
 
 Concrete construction for mill buildings 
 
 3 1924 015 348 331 
 
 Concrete Construction 
 for Mill Buildings 
 
 By Leonard C. Wason, C. E. 
 
Cornell University 
 Library 
 
 The original of tinis 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/cu31924015348331 
 
Concrete Construction 
 for Mill Buildings 
 
 A Paper Read Before The National Association of 
 
 Cotton Manufacturers at its Ninety-eighth Meeting, 
 
 Boston, Mass., April 29, 1915. 
 
 Leonard C. Wason, 
 
 President 
 
 Aberthaw Construction Company 
 
 Boston, Mass. 
 
^ 
 
 -\T. =.:>* 
 
 
Concrete Construction 
 for Mill Buildings. 
 
 Leonard C. Wason, C. E., President, Aberthaw Construction Company, 
 
 and President, American Concrete Institute, 
 
 8 Beacon Street, Boston, Mass. 
 
 It is tlie desire of the writer to present to you, without tedious 
 detail, the advantages of concrete, plain and reenforced, as 
 applied to the cotton industry. He wishes also to point out 
 some of the safeguards necessary, and to suggest a few uses to 
 which it is not so perfectly adapted as some other material may 
 be. The literature on the subject is very extensive, going into 
 much detail as regards strength of materials, methods of design, 
 €tc. Those who wish can find literature covering almost any 
 special point on which detailed information is desired. 
 
 In preparing this paper the writer has endeavored to answer 
 very briefly those questions which are naturally asked by an 
 executive who is considering construction work. Many of these 
 arc answers to actual questions. They are given without any 
 attempt at detail, or any attempt to indicate the steps leading 
 tip to them. 
 
 THE CONCRETE BUILDING HAS PLENTY OF LIGHT. 
 
 The first use which comes to mind is the larger buildings of 
 a manufacturing plant. One advantage of reenforced concrete 
 in the construction of the principal mills is that small wall 
 columns can be used, permitting very large window areas, so 
 that light is uniformly distributed throughout the length and 
 width of the rooms. The usual design today is the girderless 
 floor, which gives a flat ceiling so that there is no obstruction to 
 
light, and the wall beams are above the floor line instead of 
 below. This permits the window frames to reach the ceiling, so 
 that the glass may be within an inch and a half of the ceiling 
 level. The wall beam forms in part the curtain wall between the 
 floor line and the window-sill. As daylight is cheaper than 
 artificial light, and as metal framed windows with wire glass are 
 as cheap as masonry curtain walls, there is a saving in first cost 
 
 FIGURE 1. — MUSHROOM FLOORS, ALSO METHOD OF ATTACHING 
 
 PIPING TO CEILING BY MEANS OF INSERTS, ALSO LOCATION 
 
 OF WINDOWS CLOSE TO CEILING. 
 
 of construction, and a saving in operation, due to the illumina- 
 tion. While there is more radiation of heat from the glass area^ 
 there is less leakage, due to the tightness of the metal sash, and 
 probably not much difference in cost of heating the building. 
 
 FREEDOM FROM VIBRATION. 
 
 In buildings where there is reciprocating machinery, like 
 looms, all working together, and whose moving parts have a 
 uniform speed, there is a large advantage in concrete, because 
 the greater solidity and rigidity of this floor over that of any other 
 
type absorbs this vibration in the same way that a heavy founda- 
 tion absorbs that of a horizontal reciprocating engine. Aside from 
 freedom from damage to the building by this vibration are the 
 stability and free running qualities of the machines themselves. 
 This adds to their life and reduces the possibility of breaking the 
 threads, which affects the cost of operating and the quality of 
 the product. It has been found by some manufacturers that 
 
 FIGURE 2. —THE WOOD FLOOR OF THIS WEAVE SHED IS LAID ON 
 
 A HEAVY CONCRETE FLOOR. THE RIGID CONSTRUCTION HAS 
 
 MADE IT POSSIBLE TO RUN THE LOOMS AT HIGH SPEED. 
 
 looms can be run 15 percent, faster on a solid concrete floor 
 than on a wooden floor subject to vibration. It has also been 
 found that, due to the rigidity of the floor, there is a distinct 
 saving in power. 
 
 This makes concrete very advantageous for the weave 
 sheds, and the construction of a concrete sawtooth roof, when 
 properly studied out, is not much more expensive than one of 
 wood, while it has advantages over wood besides that of fire- 
 
proofness. The additional material necessary in building a floor 
 for a heavy load, over the minimum which must be used in 
 even a light floor, is relatively small ; so that floors carrying 
 heavy loads, as in a storehouse, are cheaply obtained. It is also 
 an easy matter to render the floors and walls so dense, by the 
 proper proportioning and placing of the concrete, as to be 
 waterproof. This makes the material admirably adapted for use 
 
 5| llL.^>:'<df 
 
 FIGURE 3. — CONCRETE SAWTOOTH ROOF IN PACIFIC MILLS, ALSO 
 CONCRETE COLUMNS AND GIRDERS. THIS SHOWS BOLTS LEFT 
 IN CONCRETE COLUMNS FOR FASTENING WOOD INTER- 
 MEDIATE TIMBERS, ALSO PIPING AND SHAFTING. 
 
 in such wet places as dyehouses, where water and steam are 
 freely used. It is an easy matter and relatively inexpensive to 
 make the floors water-tight and to pitch them to drains, so that 
 water can quickly be removed from their surface and the floor 
 below guaranteed against damage from leakage. 
 
 The resonance of a concrete floor is sometimes a matter of 
 importance, though modern design has practically done away 
 with it. In some of our earlier beam and girder construction 
 
very thin sections were used. In one building there were three- 
 inch floors and three-incji landings on the stairs — both about 
 as resonant as a drum head. Today much heavier sections 
 are used, with wider spacing of beams, and the greater mass 
 absorbs the sound. Instead of three-inch thickness, it is becom- 
 ing the custom to use five or six inches. If something must be 
 especially sound-proof, there are various methods of building a 
 dead air space. 
 
 Concrete is, however, a better conductor of heat than wood, 
 so that for external walls or roof of a dye-house it is desirable to 
 have a dead air space or some other form of non-conductor to 
 prevent condensation. To prevent condensation on windows, it 
 is desirable to have a double-glazed sash and sometimes a triple 
 thickness. But the design of the sash or frames should permit 
 the separation of the sash for cleaning the glass, as it has been 
 found impossible to fit these so tightly together as to prevent 
 ultimate clouding of the glass in the space. 
 
 Because of the conductivity of concrete, it is often necessary 
 in dyehouses, and other places where condensation is bad, to 
 use insulation. This is sometimes felt quilting made of seaweed 
 paper; sometimes it is porous cinders, sometimes cinder con- 
 crete or hollow tile. Some device of this kind, when necessary, 
 is not expensive. 
 
 CONCRETE FOR BOILER FOUNDATIONS. 
 
 In the steam power plant, concrete can also be used to very 
 good advantage, not only in the building itself, but for boiler 
 foundations. Especially where the ground is soft and of uneven 
 bearing capacity, concrete is unexcelled, because a reenforced 
 mat can be put over the whole area, so that the boilers are 
 practically floated on their foundations. It is not advisable, 
 however, to use concrete higher up for a boiler setting, although 
 in isolated cases this has been done. Brick is better adapted to 
 this purpose. Concrete is liable to shrink and open large 
 cracks through the setting, which would permit the escape of 
 gases. These cracks, being difficult to fill thoroughly and per- 
 manently, are objectionable. 
 
Although concrete will withstand for an indefinite period a 
 temperature of 500 degrees Fahrenheit, a temperature of 800 
 degrees or more will ultimately disintegrate it. It is thus not a 
 proper material to be used in the fire box, or where tempera- 
 tures are high. The writer knows of special cases where con- 
 crete, using crushed fire brick for coarse aggregate, and as 
 'sand the finer particles of fire brick, has been in use in furnace 
 
 
 FIGURE 4. — INTERIOR OF 10,000 TON COAL POCKET AT 
 PACIFIC MILLS. 
 
 construction for several years without deterioration. He does 
 not consider, however, that a few isolated examples of this are 
 sufficient to prove its general adaptablity for such purposes. 
 
 CONCRETE CHIMNEYS. 
 
 By the time the burning gases from a boiler reach the chimney, 
 however, the temperature is such that no damage is likely to 
 ensue, and chimneys can be easily and cheaply built of reen- 
 forced concrete. Instead of a heavy gravity construction as is 
 
FIGURE 5.— CONCRETE COAL POCKETS, HOLDING 10,000 TONS OF 
 COAL, PACIFIC MILLS, LAWRENCE, MASS. 
 
 used with brick, the 'design is that of a broad base and vertical 
 shaft, tied rigidly together so as to be a unit. Thus the chimney 
 might be compared to a candle, which by itself is unstable, but 
 when set in a candlestick the combination cannot be readily 
 tipped over. 
 
 Chimneys are built with various details of design, all of which 
 have proved stable and durable. For ease of construction, the 
 shaft is made of a uniform diameter from bottom to top, which 
 gives the chimney a somewhat top heavy appearance as com- 
 pared to the tapering brick chimneys with which we are so 
 familiar, and to which our eye is educated. This type of 
 chimney can be built more quickly than one of brick, and can 
 be put into service as quickly after its completion. The reason 
 so many are built of concrete is their low first cost. Some con- 
 crete chimneys have failed, due to the use of dry concrete. 
 Those made with wet concrete have proved satisfactory. 
 
 COAL POCKETS OF CONCRETE. 
 
 Another use in the power plant is for coal pockets. There 
 are a number of elevated pockets holding a depth of 40 feet 
 
10 
 
 of coal, a pressure of over a ton to the square foot, and the 
 material can be economically designed to carry these loads. 
 Even should spontaneous combustion occur in a compartment, 
 it need not necessarily destroy the pocket. Though the burning 
 ■coal creates a considerable heat, it can either be drawn out or 
 flooded with water before injury to the pocket occurs, while a 
 wooden pocket would be wholly destroyed. From past experi- 
 ence, the writer has found that the first cost of such a pocket is 
 
 FIGURE 6. — REENFORCED CONCRETE COAL POCKETS CARRYING 
 RAILROAD TRACK OVERHEAD, JACKSON CO., NASHUA, N. H. 
 
 about ten percent, more than that of a wooden one. Its life is 
 much longer. 
 
 For engine foundations, plain concrete is now almost univer- 
 •sally used. It has greater weight per cubic foot than brickwork, 
 it is more quickly and more cheaply placed, and both tests and 
 ■experience have proved that it is immune from deterioration by 
 the lubricating oil inevitably spilled upon it. 
 
11 
 
 SURFACE TREATMENT OF CONCRETE. 
 
 Before dropping the subject of buildings, attention should be 
 given to the treatment of exterior surfaces. The simplest and 
 cheapest treatment is to rub the surface, soon after the forms 
 are removed, with a coarse carborundum stone, cement, fine 
 sand and water. This fills up the voids, if any, and removes fins, 
 giving a uniform texture but not necessarily a color. On the 
 final cleaning down of the building, rubbing with carborundum 
 and water gives a uniform color, that of the cement, and there- 
 fore permanent. This is a clear gray and of itself is not very 
 pleasing. 
 
 A tint can be obtained by the addition of coloring matter 
 
 FIGURE 7. — ORNAMENTAL PIECES CAST SEPARATELY AND 
 PLACED IN BUILDING. 
 
12 
 
 which has a strong contrast with the cement itself, preferably a 
 lamp black or deep red in small quantities, and with colored 
 sand. A warm pleasing tint, such as is found in Indiana lime- 
 stone, can be obtained without very much expense. A color con- 
 trast by the use of red brick for curtain walls and for corner 
 piers makes a very attractive building. 
 
 Concrete can be tooled in various ways, as is the natural 
 stone, so as to expose the coarser aggregate of which the con- 
 crete is made ; and some types of mouldings can be made without 
 serious increment of expense. The cost of ornamentation comes 
 chiefly in the form work. Because the material is plastic, it is 
 easy to fill forms, whether they be plain or ornamental. A mill 
 built several years ago in an adjoining city had a very ornamental 
 front, with ornaments cast in individual moulds, and set, as. 
 natural stone would be, around the main entrance and in the 
 cornice above. The difference in cost between this design and 
 the conventional mill construction was less than 2 percent, 
 of the total cost of the mill. 
 
 CONCRETE DAMS AND RESERVOIRS. 
 
 Equally important with the use of concrete in connection with 
 steam power is its use in connection with water power develop- 
 ment. In the development of power from the fall of water in a 
 river, the integrity of the investment depends upon the stability 
 of the dam which impounds the water. The head that can be 
 secured and the nature of the foundations are the controlling 
 factors. Different types of dams have been designed, each of 
 which may be most advantageous in a given situation, but none 
 of which is recommended as being adapted for every position. 
 
 With any type of dam, the best time to begin construction 
 is usually in the middle of the winter. Transportation is less. 
 expensive over the snow ; the low condition of the river is usually 
 favorable to the building of the initial cofferdams; the necessary 
 preparation in the assemblingof construction tools and machinery,, 
 and the bringing together of the construction force, etc., can 
 better be done at this season. It should be noted that in every 
 hydraulic installation there is a great deal of work that is per- 
 
13 
 
 FIGURE 8. — SECTION OF SOLID WEGMAN DAM WITH APRON FOR 
 
 THROWING THE OVERFLOW WATER HORIZONTALLY INTO 
 
 THE LOWER PART OF THE RIVER. 
 
 formed outside of the river bed. If all this is done before the 
 spring floods have passed, the remainder of the season is usually 
 sufficient time for the completion of almost any structure, 
 excepting one of uncommon magnitude. 
 
 TYPES OF CONCRETE DAMS. 
 For a solid rock foundation with a 30-foot head or less, the 
 
 FIGURE 9. — SECTION OF AMBURSEN APRON DAM FOR ROCK 
 FOUNDATION AND HIGH HEAD. 
 
14 
 
 FIGURE 10. —AN EXAMPLE OF POWER HOUSE BUILT RIGHT INTO 
 
 THE DAM. 
 
 standard Wegman section of solid concrete, in which a large 
 amount of displacement stone may be used, is the prevailing 
 type, and is lowest in construction cost. When the head is as 
 great as 50 or 60 feet, some other type should be considered, 
 in view of economy. At a height of 100 feet, unless there are 
 other predominant factors, the solid section is the most expensive. 
 In the hollow cellular dam of reenforced concrete, the buttresses 
 or piers, spaced from 12 to 20 feet apart, are connected on the 
 upstream face with a flat slab of reenforced concrete, designed 
 to support the necessary load. This type minimizes the amount 
 of material used in construction, — an important factor when 
 the transportation of cement, stone and other materials is a 
 serious item of cost. 
 
 A third type, — another cellular dam, — combines the ideas of 
 the two described, namely, the wide spacing of the buttresses 
 and the arching of the upstream face, with the object of diminish- 
 ing the amount of material used. This is done by the introduc- 
 tion of a moderate amount of reenforcing steel, at the same time 
 diminishing the amount of construction work by the building of 
 fewer piers or buttresses. On a rock foundation, if the dam 
 is less that 30 feet high, the solid section Wegman type with dis- 
 placement stone usually costs less. At 50 feet a cellular gravity 
 dam will effect a saving of perhaps 10 percent; at 75 feet it 
 will perhaps cost 20 percent less, and at 100 feet the cellular 
 
15 
 
 dam will probably cost 30 percent, less than a solid section. 
 These figures are very approximate. 
 
 It is where the foundation is not on solid rock that the 
 greatest variation in types of dams exists. Dams have been built 
 upon sand or clay, gravel or mud, and have successfully per- 
 formed their functions. Very seldom is it necessary to abandon 
 a site altogether, through inability to design a dam which will be 
 absolutely stable and sufficiently low in cost to justify the 
 investment. 
 
 Electrical engineers have so perfected the transmission line 
 that it is no longer necessary to build a mill by the site of a 
 dam. Neither is it necessary to have long flumes and canals, 
 unless to utilize the fall of the river below the dam and thus 
 obtain additional head, which sometimes cannot be secured 
 except by this method. 
 
 SECONDARY POWER OF A RIVER. 
 
 In the use or the sale of electrical energy, the secondary 
 power of a river is today a great advantage to the investment. 
 For that reason the power house constructed in the dam is today 
 provided with an excess of generating machinery, so that in 
 times of high water more of the power of the river can be utilized. 
 Studies of generating machinery and the economical load factor 
 of production have shown that, in some markets, generating 
 machinery used for only sixty days in the year well repays the 
 cost of the installation. For this reason, careful study of the 
 river flow, the number of floods or partial floods that may be 
 anticipated, the question of the further development of the river, 
 and the conservation of its head waters, all should be carefully 
 considered. Only then should the amount of the generating 
 machinery be determined upon, or all of the space in the power 
 house allotted, with no provision for further enlargement. 
 
 If possible, canals, flumes and penstocks should be avoided, 
 as they restrict the amount of water that can be utilized, and 
 usually confine the generation to the primary or minimum flow 
 of the river, whereas the secondary flow is often today of greater 
 importance. It has been demonstrated that a varied power 
 
16 
 
 market combining night and day users of electrical energy will 
 absorb practically all of the secondary generation. Many manu- 
 facturing firms that have installed a hydro-electric station merely 
 for their own use, have found that surplus power was not only 
 a source of added income, but an added means for the upbuild- 
 ing of the community. 
 
 The power house constructed in the dam can be designed to 
 utilize a large portion of the flow which would otherwise be 
 wasted. The power house at the end of a canal or flume can 
 use only the water which this canal conveys to it. There is a 
 nice balance between the amount of money to be invested in 
 canals and the proper conservation of the entire power of the 
 river; and the possibility of future storage has to be considered. 
 The powerhouse in the dam will usually be the most economical 
 
 FIGURE n.— DAM OF CELLULAR CONSTRUCTION, 135 FEET HIGH. 
 
17 
 
 in construction, as it minimizes both the amount of concrete and 
 the quantity of excavation. 
 
 The low head, open flume construction is most expensive, as 
 regards both the building and the generating machinery ; and 
 as a rule, the higher the head, the less the cost per kilowatt of 
 complete generating station (considered by itself). A great 
 advance has been made in the adoption of various types of tur- 
 bines under fluctuating heads and under low or high pressure, 
 and often the type of turbine determines the design of a power 
 house. It is manifestly out of place in a paper as brief as this 
 to discuss the design of various types of dams, power houses, 
 and of the generating machinery installed therein. 
 
 ■ CONCRETE FOUNDATIONS. 
 
 Big block stone is seldom' if ever used today for foundations. 
 Concrete, being strong and improving in strength in moist places 
 instead of deteriorating, has become practically universal. 
 Where the ground is firm, the problem is simple. Where the 
 ground is of moderate bearing capacity, it is very easy, by reen- 
 forcing, to spread the load over a wide area, with an increase in 
 depth of not over one-third the spread, thus materially saving in 
 excavation. The same is possible with interior piers, by reen- 
 forcing the footings in two or more directions. Where the 
 ground is too soft to carry this load, but for a short time will 
 hold its position without slumping, a special form of pier can be 
 used conveniently. A cylinder of thin sheet metal is sunk, the 
 material excavated inside it, and when the solid bearing stratum 
 is reached, the soil is scooped out horizontally so as to increase 
 materially the bearing area. The chamber thus formed is 
 immediately filled with concrete. 
 
 In a soil which would not stand more than a half hour by 
 itself, it is possible to increase the bearing area on the ground 
 ■sufficiently to develop the full strength of the concrete pier. 
 This method may be used for piers 15 inches and upwards in 
 diameter and of lengths up to 20 feet. Concrete piles of various 
 types have been used to good advantage. Some are cast in 
 place, having first driven a shaft to make a hole in the earth, and 
 
18 
 
 then used the earth as a form. Again, a steel core is driverr 
 with a thin sheet metal covering which is left in place and filled 
 with concrete. Some concrete piles are cast on the surface of the 
 ground, permitted to harden, and then driven like a wooden pile.. 
 
 The carrying capacity of a concrete pile is equal to three 
 wooden piles. Where the ground water level is low, which would 
 require cutting off wooden piles at a considerable depth below 
 the surface of the ground, capping them and building a pier 
 above, concrete piles can be used to good advantage and with 
 economy, because they are brought to the under side of the cellar 
 floor. They thus save in the excavation and masonry necessary 
 to cap the wooden pile. 
 
 If it is found desirable to add to the height of a building, and! 
 the foundations are inadequate to carry the additional load, they 
 can without much difficulty be underpinned in sections with 
 reenforced concrete. In this way a broad spread can be made 
 as previously described, and with very little excavation. When, 
 a short section has sufficiently set, an adjoining section can be 
 opened out and the process repeated, until the whole building is 
 reenforced, when the additional load can be placed upon it. 
 
 It is possible also to place concrete safely under water, even 
 at a great depth, if proper precautions are taken and the water 
 is kept still until the cement sets. 
 
 WATERPROOFING CONCRETE ROOFS. 
 
 The use of concrete for roofs has simplified the waterproofing 
 problem. Instead of using 5-ply roofing paper, 3-ply will be 
 found ample. The saving from this source often exceeds 2 
 cents per square foot, or $600 on a mill 75 by 400 feet. The 
 two extra plies used on a wood roof are needed to make a smooth 
 surface, but the concrete roof is already smooth. 
 
 For a picker room, concrete is especially well adapted. It 
 not only makes a room which is fireproof in itself; but it forms 
 a tight surface, through which lint cannot be blown by the 
 pressure of the fans. The contrast in this respect with a wood 
 floor is very marked, as those who have been annoyed by lint 
 hanging down from the ceiling of the room below the picker 
 room can well testify. 
 
19 
 
 MINOR TEXTILE USES OF CONCRETE. 
 
 Some of the minor uses for concrete in the cotton industry 
 are for tanks for holding clear water or liquors of various kinds. 
 It is an easy matter to make a tank of the size which is used in 
 wood, and guarantee it water tight in concrete. But it is neces- 
 sary to use great care in proportioning the sand, stone and cement 
 to get the maximum density, to use the right proportion of 
 water, and carefully to mix and place the materials. Then the 
 concrete is really water tight. 
 
 For tanks to hold chemicals or dye stuffs, the user must con- 
 sider whether or not these chemicals will attack the tank itself. 
 As the base of Portland cement is lime, acid will attack it. If 
 the concrete is porous, and the tanks are alternately emptied 
 and filled, even alkalies will destroy it, due to the crystallization 
 of the alkalies within the pores, which mechanically disintegrates 
 the concrete. Such cases have come within the writer's personal 
 
 FIGURE 12.— CONCRETE TANKS BELOW FLOOR; CONCRETE 
 
 COLUMNS; CONCRETE BEAM AND GIRDER SYSTEM 
 
 SUPPORTING CONCRETE ROOF. 
 
20 
 
 experience. When a tank is new there is a little free lime on the 
 inside surface, which may temporarily affect the solution in the 
 tank, because of the solubility of this lime, but this will disappear 
 after some weeks of service. This must be kept in mind if the 
 nature of the solution is such as to be injured by lime. 
 
 Other uses are for filter beds in the filtering of water for 
 manufacturing purposes, and for reservoirs for the storage of 
 water for fire and other uses. Standpipes, due to their size, are 
 
 FIGURE 13.— REENFORCED. CONCRETE STANDPIPE AT 
 WESTERLY, MASS. 
 
21 
 
 very difficult to make absolutely tight in reenforced concrete. 
 To accomplish this result, an impervious lining of some kind 
 must be used. 
 
 Another use to which concrete has been put to a limited 
 extent is for cloth pits in bleacheries. Here the result to be 
 obtained is a surface so smooth that no injury will be caused to 
 the most delicate fabrics, and yet so hard that no particle what- 
 soever will rub off and be mixed with the fabric, which later has 
 
 FIGURE 14. — CONCRETE GIRDERS, EIGHTY-FOOT SPAN, IN A 
 RUBBER GOODS STOREHOUSE. 
 
 to go through other processes, such as dyeing or printing. 
 This type of pit requires special construction to obtain these 
 results. In a recent plant of large size, a number of pits of this 
 type were used, even at considerable increase in cost over wood. 
 Except where heavy acid is used, these pits have proved very 
 satisfactory. Cement walls cannot be satisfactorily acid-proofed. 
 
 DESIGN OF CONCRETE STRUCTURES. 
 The subject of design will be briefly covered, and that in a 
 non-technical way. So many tests have been made of beams 
 
22 
 
 and girders in laboratory test specimens and in actual work that 
 the theory and practice of design have been thoroughly estab- 
 lished and engineers can guarantee results without hesitation. 
 Floors can be built with either beams and girders, beams close 
 together or far apart, as in wood mill design ; as well as in the 
 distinctive concrete methods of wide beams with a small panel 
 between, and the straight mushroom or girderless design. 
 
 An economical span for ordinary loads as found in the textile 
 industry is from 1 8 to 22 feet in each direction, making approxi- 
 
 KIGURE 15. —CONCRETE SAWTOOTH ROOF; ALSO CONCRETE OFFSETS 
 TO CARRY RAILS OF TRAVELING CRANE. 
 
 mately square bays. However, the spacing of columns can be 
 made anything which the conditions demand, from very close 
 together up to very long spans. The longest span ever called 
 to the writer's attention was 106 feet, and this was a roof with 
 1 5-foot galleries suspended from it along each side. The longest 
 span built by the writer is 80 feet. From 30 to 50 feet is rela- 
 tively common, although not as economical as the first named 
 standards. 
 
23 
 
 The loads which can be carried vary from a light load of 
 25 pounds for a roof, to a ton to the square foot. Columns 
 -can be made plain or reenforced. If the building is high and 
 the loads heavy, to save room it is often desirable to carry the 
 load on a structural steel core which is fireproofed with con- 
 ■crete. For buildings up to four stories, reenforced concrete 
 •columns will be found the cheapest; and the size is not objec- 
 tionable in the lower stories unless the loads are exceedingly 
 heavy. For six stories and more, if the lower story columns 
 are too large, structural steel may be substituted. It is not 
 necessary to use any horizontal structural steel members, as the 
 floors will be supported without difficulty from shelf angles 
 riveted to the steel members. Brackets for crane girders can be 
 •easily cast with the concrete columns, where necessary. 
 
 CONCRETE FLOOR FINISH. 
 
 An important detail of construction is the floor finish. The 
 •cheapest finish is granolithic, — a mixture of tough crushed 
 ■stone and cement, laid either as an integral part of the floor 
 construction or as a second coat following. There are reasons 
 for both types of construction, and the arguments for and 
 against are too long for the limits of this paper. Another very 
 general type is wood. There are various methods of laying 
 this. The first one is to embed sleepers in the cinder concrete 
 fill, to which a single floor is nailed, and sometimes a double 
 floor. Sometimes a plank underfloor is laid, either loose or 
 mopped down with asphalt, on which a finished floor is laid. 
 Another method is the laying of a porous concrete containing 
 cement, sand and asbestos, to which the floor is nailed direct, 
 the nails holding well in the lower coating. The merits and 
 ■demerits of the different methods are matters of argument. 
 
 On top of a concrete floor, the wood can be laid in whatever 
 direction is desired, whereas on wooden frame floor it can be 
 laid only in one direction, which is determined by the framing. 
 "The most serious of the objections which have been found with 
 wooden floors laid solid is that they swell and buckle. Some- 
 times they have risen 30 inches from place. To overcome this. 
 
24 
 
 sometimes bolts are embedded in the concrete construction at 
 sufficient intervals to hold the underfloor rigidly in place, and 
 sometimes slots are left to relieve the swelling. It has been found 
 that underfloors embedded solidly in asphalt rot out in a rela- 
 tively short time. 
 
 The most frequent objection to the granolithic floor comes 
 from the operatives, who claim that the floor is hard on their 
 feet and lames them. An extensive study made by the writer 
 some years ago led to the conclusion that the trouble was solely 
 with the fact that granolithic is a better conductor of heat than 
 wood. Operatives wearing thin shoes complained when their 
 feet became cold, and when standing in one place the circulation 
 was impaired and their legs became tired or lame. By the use 
 of heavy shoes, or by standing on a wooden grating, this diffi- 
 culty is overcome. Complaints are not received from operatives 
 who move about freely in the performance of their work. The 
 advantages of a clean, smooth floor, low in first cost and cheap 
 in maintenance, can thus be had without any objection from 
 operatives. 
 
 A dustless floor is one which wears ofT so slowly and so 
 smoothly that it does not noticeably cause disturbance. The 
 question of obtaining this floor is largely one of selection of the 
 aggregates. A thoroughly first-class aggregate, tough and 
 durable, will avoid most of the trouble caused by dusty floors. 
 The writer has not known any cases where dust has risen suf- 
 ficiently to be a serious disturbance to machinery. 
 
 If the aggregate is bad, not much can be done to correct it- 
 There are, however, various ways of reducing the dust, which 
 comes mostly from the cement, but partly from the stone. A 
 silicate of soda or boiled linseed oil will minimize the trouble. 
 One power-house, built about 1898, had a floor so dusty that, 
 with patience, probably an inch of it could have been swept 
 away. Two applications of boiled linseed oil laid the dust so 
 well that during the next six years of wear there was no trouble 
 whatsoever. The writer has not seen it since then, but presumes 
 it is still in good order. 
 
 There seems to be no material which can be put into the 
 
25 
 
 surface of a concrete floor and which, while still withstanding 
 wear, is resilient or soft to stand upon. The wear depends 
 upon the quality of the stone. Either one must expect a hard, 
 tough surface, or else use some other substance than Portland 
 cement. 
 
 ATTACHING MACHINERY OR PIPING TO CONCRETE FLOORS. 
 
 It is an easy matter either to embed inserts in the floor for 
 the attachment of shafting, piping, etc., in a pre-arranged method, 
 or to insert these so that timbers can be bolted to them and allow 
 an elastic method of attachment. Again it is fairly simple to 
 drill holes for the insertion of expansion bolts, where no previous 
 provision has been made. The cost of setting these inserts 
 varies with their style, but for material and labor may be said to 
 run between 5 and 10 cents each. They can be attached as 
 readily to corrugated iron, which is today very extensively used 
 for form work, as to the wooden panels which were used most 
 extensively some years back. Corrugated iron is much cheaper 
 to use for form work than wood panels, and the writer thinks it 
 makes a much better looking ceiling. 
 
 The question of relocating machinery can be taken care of 
 tmder modern conditions. In the weave shed, for instance, if 
 it becomes necessary to change the size of the looms or their 
 arrangement, either the individual motor drive can be adopted 
 or arrangements can be made to locate the new shafting in the 
 most advantageous position overhead. Fastening the machines 
 to the floor in the new arrangement is simply a matter of drill- 
 ing small holes and using expansion bolts. Cutting holes 
 through the floor for carrying belts from one story to another 
 might be serious, because it would be difificult to arrange the 
 holes in a way to escape cutting reenforcement. 
 
 Steam pipes are rarely embedded in the floor. The writer 
 has never known of a case personally. It is quite common, 
 however, to put in conduits for electric wires, and it would be 
 just as easy to insert pipes. The writer believes, however, that 
 the movement of the pipes, with changes of temperature, would 
 be likely to cause trouble, especially if there were bends in the 
 pipe rigidly embedded in the concrete. 
 
26 
 
 DETAILS OF CONCRETE BUILDINGS. 
 
 Window frames for large areas are made largely of rolled 
 steel sections, sometimes of a single piece and sometimes built 
 up. Both types have their advocates and their individual merits. 
 Actual fire tests have shown that while rolled steel shapes are 
 not as fire resisting as sheet metal formed into a box, yet it is 
 an excellent fire resistant, and unless the fire hazard from an 
 outside exposure is very bad, are good enough. Wire glass is 
 
 FIGURE 16. — MOTOR HUNG FROM CORRUGATED CEILING IN THE 
 MASSACHUSETTS COTTON MILLS' STOREHOUSE, LOWELL. 
 
 advisable if there is any risk from spreading of fire from story 
 to story, or if there is exposure from without. 
 
 Concrete stairs have long since replaced iron, or the combi- 
 nation of iron and stone treads, because they are lower in first 
 cost, non-slipping, and better protection against fire. If desired, 
 safety treads of various types can be permanently attached to 
 the treads, to reduce still further the possibility of slipping. 
 
27 
 
 DURABILITY OF CONCRETE STRUCTURES. 
 
 A few of the properties of the material may well be kept in 
 mind in connection with the designing. Steel embedded in 
 concrete is prevented from rusting if the cement is in hard contact 
 with the steel, even though the combination be permanently in 
 a wet place. Cement increases in strength with age. Tests have 
 been carried to seventeen years, which show a measurable 
 increment each year. Concrete settingin air shrinks somewhat, 
 and subsequent expansion due to heat never overcomes the 
 original shrinkage due to setting. Therefore cracks open and 
 remain open, and we shall speak of these as contraction, not as 
 expansion cracks. 
 
 By reference to the great conflagrations which have taken 
 place, it will be seen that if concrete is properly made it is one 
 of the best fire resistants which we have. As a resistant to heat, 
 the material of the aggregate is important. The stone should 
 be as near fireproof as possible. A trap is very much better 
 than granite. Doubtless you all know how well a concrete mill 
 storehouse withstood the great Salem conflagration, and the 
 experiences of the recent great fire in the Edison plant are fresh 
 in your minds. This latter developed, we think, the greatest 
 heat to which concrete buildings have ever been subjected, with 
 the greatest apparent injury to them ; but it has been found that 
 they could be restored to their original condition for about 13 
 percent, of their first cost. 
 
 A CONCRETE BUILDING IS TRULY MANUFACTURED. 
 
 Some attention should be given to methods of construction. 
 It should first be noted that the building of reenforced concrete 
 is a manufacturing proposition. Crude materials, sand, stone, 
 cement and water, are combined with each other, placed in forms 
 which are previously made to hold the plastic material, which is 
 poured around reenforcement previously set and secured in 
 position, and a new material is thus manufactured in place. This 
 is a more ditficut proposition than assembling. The building 
 of mill construction is largely that of assembling. One brick is 
 piled upon another with mortar between. Wood is put in place 
 
28 
 
 with very little change from its original form. For this reason, 
 a better type of builder is desirable for a reenforced concrete 
 building than for the other. A manufactured article is either 
 right or wrong ; there is no half way about it. If it is concrete 
 and if it is wrong, it must either be accepted as it is and remain 
 wrong, or else it must be torn down and done over. Hence the 
 great importance of doing it right the first time. 
 
 Modern building has become a scientific process, with a great 
 deal of detail in methods and operation, in order to obtain the 
 
 FIGURE 17.- 
 
 - TAPESTRY BRICK USED FOR EMBELLISHMENT 
 OF A MILL. 
 
 maximum of economy; and the day of the bright mechanic who 
 has worked up to be a general contractor is fast passing. The 
 general contractor for this type of work ought to be an engineer. 
 It is very desirable that his job superintendent is an engineer, 
 and many of them are. They should have an intimate knowledge 
 of the theory as well as the practice of design. Points often 
 come up during the day's work which have been overlooked by 
 the designing engineer, and which if not properly covered by 
 the superintendent from an engineering standpoint will fall short 
 of the best results. 
 
29 
 
 METHOD OF HANDLING A CONCRETE JOB. 
 
 To show briefly the intricacy to which it is necessary to go to 
 get economical results, the writer might mention that a good 
 builder in reenforced concrete today, after long study, has settled 
 upon a type of form which long experience has shown the men 
 can build quickly and economically. Plans of the forms are 
 made to fit the particular building with as much precision as 
 structural steel is laid out in a bridge shop. Panels for columns 
 and beams are drawn out, showing the number, width of boards, 
 the number of cleats, the position, and even the size and number 
 of nails. The first use is located and their second use, when 
 taken down, is planned from place to place through the building, 
 until finally it reaches the storage pile for removal from the site 
 of the finished structure. From these plans the bill of material 
 is scheduled, and when received the material is put in piles 
 pre-arranged, and shown on a ground plan of the lot. 
 
 A routing department is established and the materials are 
 moved by written orders and taken to saw mill, where they are 
 cut according to written instructions and moved to benches. 
 Here they are made up from blueprints and are from there 
 taken by instructions to the building, where the experienced 
 carpenter foreman, who is now given freedom to do only that 
 for which he is specially trained, namely, directing his men, 
 sees that the men assemble the work in place with the fewest 
 possible motions and least effort. This seems and is elaborate, 
 but the results are what count. 
 
 Although lumber has doubled in price in the last fifteen 
 years, the cost of lumber per square foot of floors has not 
 increased ; and although labor has practically doubled in price 
 in fifteen years, the cost per square foot of floors, including all 
 the overhead of making plans, running a routing department, 
 etc., is less than half of what it used to be. This applies as well 
 to reenforcing metal as to forms, and somewhat to the placing of 
 concrete. The greatest savings are obtained where the men 
 work in small units, in pairs, as do carpenters, rather than in the 
 large units necessary in the mixing and placing of concrete. 
 
 It has been supposed that the laying of brick has been so well 
 
30 
 
 established that few if any savings could be made upon it. But 
 a study of methods during the past year or two, and applying 
 the principles of scientific management, and somewhat the task 
 and bonus, the cost of brickwork has been reduced several 
 dollars per thousand without the slightest sacrifice in quality. 
 This gives the very great advantage of planning the work to be 
 done at a certain speed and place, and enables all the other 
 trades and sub-contractors to co-ordinate their work to a definite 
 schedule, thus saving in time and expense. 
 
 COST-KEEPING SYSTEM IN CONCRETE WORK. 
 
 An accurate and detailed cost-keeping system is installed on 
 the job, and daily costs are prepared for the use of the job 
 superintendent. Before nine o'clock each day, he knows the 
 complete record of yesterday's costs, and immediately goes upon 
 the work to straighten out the cost of those items which may 
 be high. Charts are placed on the wall, where at a glance it is 
 seen whether the actual work is running above or below that 
 which it was estimated it should cost before the work started. 
 
 The sub-foremen and gang bosses take a keen interest in 
 watching these, which leads them to think and work for low 
 costs. The general superintendent encourages them in this, and 
 insists that there shall be no sacrifice of quality to obtain these 
 results. These methods have been amply justified. A dollar 
 spent in the drafting room or cost-accounting department has 
 saved many dollars outside, and the combination of the direct 
 and indirect cost is much lower than it used to be. This pre- 
 cision also saves in the time of construction. 
 
 SPEED OF BUILDING IN CONCRETE. 
 
 Assume the very common case where a manufacturer delays 
 an increase until the last moment, then wants his mill in the 
 shortest possible time. Frequently orders for a mill are placed 
 before a single plan is made for the building. In a week's time 
 the mechanical plant is collected, the general plans of the building 
 laid out, the details of the footings and foundations completed, 
 the general method of operation studied out, and a time study 
 
31 
 
 of operations made as far as the sweeping out of the finished 
 ■building. Material is scheduled, and ordered to be delivered in 
 a pre-arranged order and at times as wanted, and in a week from 
 receipt of order the organization starts on the ground. 
 
 In general, a four-story mill requires from three to four weeks 
 for foundation work, the frame will be erected at the rate of a 
 story a week, and in from four to six weeks from the casting of 
 the roof the job will be finished and delivered. Thus the whole 
 
 FIGURE 18. — CORRUGATED CEILING SHOWING USE OF CORRUGATED 
 
 STEEL FORMS. ALSO THE USE OF MUSHROOM FLOORS, 
 
 AND OF INSERTS TO CARRY PIPING. 
 
 undertaking can be put through economically in four months as 
 a general average. If greater speed is required it can be made 
 at the sacrifice of economy. Within a few months the writer has 
 ■erected one four-story and basement mill for occupancy in sixty- 
 two days, and another, under more trying circumstances in mid- 
 winter, in seventy-seven days. The ground area of the building 
 has little influence on the time of construction. This is governed 
 by the height, as one operation must follow another in height; 
 while on plan it is a question of one mixing plant or two or 
 TTiore, and of the number of men to operate them properly. 
 
32 
 
 COST OF CONCRETE CONSTRUCTION. 
 
 Lastly, in regard to relative cost of a reenforced concrete fire- 
 proof mill and one with brick walls and wooden floors, the 
 former used to cost about 15 per cent, more on the average. 
 As improved methods have been developed in the handling of 
 men and materials on reenforced concrete, the prices have more 
 nearly approached one another. In a number of cases they 
 meet, and in a few cases the reenforced concrete building is 
 cheaper in first cost, in addition to the other advantages above 
 enumerated. The destruction of our forests of southern pine 
 of large dimension, making this material more scarce and of 
 inferior quality, has been a marked element in the change. 
 
 WHY OWNERS DEMAND FIREPROOF BUILDINGS. 
 
 Perhaps the most important reason why manufacturers are 
 building of fireproof construction today is to insure a continuity 
 of their market. If, as many do, they sell under a special trade 
 mark, and this is off the market for a number of months, it is 
 difficult to recover the lost ground. The building and contents 
 may be insured ; the market cannot. 
 
Lithomount 
 
 Binders 
 Gaylord Bros. Inc. 
 
 Makers 
 
 Syiaousu, N. Y. 
 
 Pat. /an. 21, 1908 
 
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