38 BUKLETIN" 101*7, U. S. DEPAETMEXT OF AGEICIILTUEE. 



boxes. Biilk cement is usually shipped in open-top cars, covered 

 with tarpaulins for protection from the weather. It m_ay be un- 

 loaded with a clamshell bucket. Storage for cement should always 

 be provided at the unloading yard. The storage house should be 

 leak-proof and should be lined with roofing paper to prevent the 

 free circulation of air. The floor of the house should be elevated 

 above the ground. The necessary storage capacity will depend upon 

 the size of the job and the capacity of" the equipment, but for the 

 average small job of approximateh' 4 miles, storage capacity should 

 be provided for about 2,000 barrels of cement. Storage capacity 

 is especially desirable in case it should be necessary to hold the 

 cement until tests can be obtained or until the cement has aged suffi- 

 ciently to pass the soundness test. Where the materials are hauled 

 to the road separately, the cement may be hauled by any of the 

 methods previously described for hauling aggregates separately. 

 With this method of operation, some storage of cement on the road 

 is desirable. Cement stored on the road should be piled on boards, 

 or racks, at convenient intervals and shelter should be provided 

 for use in case of rain. 



Aggregate. — A number of methods may be employed for handling 

 the materials into the mixer. Where the aggregates are distributed 

 on the subgrade they may be handled into the mixer skip by wheel- 

 barrows or by a belt-conveyor loader as shown in Figure 1, Plate 

 III. Wlieelbarrows are most commonlj^ used, and, where labor is 

 plentiful and inexpensive, this method will prove economical. The 

 materials should be distributed in such manner that no unnecessary 

 labor and time will be consumed in wheeling the materials lon^ dis- 

 tances to the mixer. The belt-conveyor loader consists essentially 

 of a long, .steel frame, on traction wheels, operated by independent 

 power, on which low. bottom-dump measuring boxes are placed for 

 measuring the materials and discharging them upon the belt con- 

 veyor. A wide continuous belt carries the materials forward to the 

 loading skip. The principal advantage of the conveyor loader is 

 that it does away with the wheelers. Its disadvantages are that the 

 aggregates mu.st be vei'y accurately distributed on the subgrade for 

 efficient operation, and on roads of average width it is very difficult 

 to distribute the materials within the area of the subgrade so that 

 no shoveling of material is necessary in setting the forms. 



If the aggregates are stored in small .stock piles on the subgrade or 

 on the shoulders of the road, they are usually picked up by some 

 form of bucket elevator and loaded in the proper proportions into 

 batch boxes, light trucks, or carts in which they are hauled to the 

 mixer and discharged directly into the skip. If batch boxes are 

 used, they are hauled to the mixer by horse-drawn cars running on 



