Contractors' Supply & Equipment Co., Chicago, Ill.
| Mixer number. | No. 0. | No. 1. | No. 2. | No. 2½. | No. 4. | No. 5. |
| Stand. charge cu. ft. Cement | 1 | 1 | 2 | 2 | 3 | 4 |
| " " " Sand | 2½ | 4 | 6 | 7½ | 10½ | 14 |
| " " " Stone | 5 | 8 | 12 | 15 | 21 | 28 |
| Total unmixed per batch, cu. ft. | 8½ | 13 | 20 | 24½ | 34½ | 46 |
| Mixed material per batch (loose), cu. ft. | 6 | 9 | 13½ | 16½ | 22 | 30 |
| Cubic yards mixed per hour, up to | 9 | 20 | 30 | 39 | 46 | 62 |
| Power required—H.P. | 4 | 6 | 8 | 10 | 15 | 19 |
| Revs. per minute of driving pulley | 218 | 180 | 173 | 162 | 160 | 125 |
| Diameter and face of driving pulley, ins. | 20×4½ | 24×5½ | 28×5½ | 28×6½ | 36×6½ | 48×7½ |
| Weight on skids with pulley only, lbs. | 1,740 | 2,500 | 3,600 | 4,400 | 6,200 | 7,900 |
| Weight on truck with pulley or gears, lbs. | 2,200 | 3,650 | 4,750 | 5,500 | 7,400 | .... |
| Weight on truck with steam eng. & boil., lbs. | 3,750 | 5,600 | 7,200 | 8,600 | 11,400 | .... |
| Weight on truck with gasoline engine, lbs | 4,000 | 5,100 | 7,400 | 9,300 | .... | .... |
Table XXXII—Sizes, Weights and Capacities of Polygon Mixer.
Waterloo Cement Machinery Co., Waterloo, Iowa.
| Mixer number. | No. 4. | No. 5. | No. 6. | No. 7. |
| Maximum charge, cu. ft. | 6 | 10 | 12 | 16 |
| Cubic yards mixed per day (10 hrs.) up to | 60 | 190 | 130 | 180 |
| Weight on skids with pulley (approx.) | 1,600 | 2,200 | 3,500 | 4,000 |
| Weight on skids with steam engine and boiler (approx.) | 3,100 | 3,900 | 5,500 | 6,200 |
| Weight on skids with gasoline engine (approx.) | 2,900 | 3,900 | 5,100 | 5,700 |
| Weight on trucks with steam engine and boiler (approx.) | 3,600 | 4,600 | 6,000 | 7,000 |
| Weight on trucks with gasoline engine (approx.) | 3,400 | 4,650 | 5,700 | 6,750 |
DATA FOR ESTIMATING THE WEIGHT OF STEEL IN REINFORCED CONCRETE.—Architects' and engineers' plans record the steel used in reinforced concrete in various ways. Sometimes complete schedules of shapes, dimensions and weights of the various reinforcing elements are drawn up and submitted to bidders with the plans. In such cases the estimating is usually a simple problem for the contractor. In other cases the amount of steel that will be required is stated as a percentage of the volume of the concrete. In still other cases the detail drawings merely show the number, location and dimensions of the reinforcing bars, stirrups, etc., and the contractor has to compile from them his own schedule of quantities. The following tables and discussion will aid the contractor in making his estimates. Before proceeding with these data, however, the authors would strongly advise that to facilitate rapid estimating the contractor should keep accurate records of all reinforced concrete structures in such form as to show the percentages of steel used. In doing this, however, he should be careful to separate the foundations, etc., which are not reinforced from the superstructure which is reinforced. A reinforced concrete arch bridge, for example, usually rests on piers and abutments which are not reinforced. Do not lump together all the concrete in recording the weight of reinforcement used, but separate the reinforced arch from the unreinforced portions.
Method of Computing Weight from Percentage of Volume.—In a cubic yard of concrete there is 1 per cent. of 27 cu. ft. or 0.27 cu. ft. of steel if the reinforcement is 1 per cent. Now a cubic foot of steel weighs 490 lbs., but for all practical purposes we can call it 500 lbs. Hence reinforced concrete containing 1 per cent. of steel has 0.27 × 500 = 135 lbs. per cubic yard. Table XXXIII has been computed in this manner; knowing the price of steel it is a matter of simple multiplication to estimate from the table the cost of steel for any percentage of reinforcement.
Weights and Dimensions of Plain and Special Reinforcing Metals.—Steel for reinforcement is used in the shape of plain round and square bars, deformed bars, woven and welded netting and metal mesh of various sorts. Tables XXXIV to XXXVII show the weights, dimensions, etc., of these various metals.