38 BULLETIN 1077, U. S. DEPARTMENT OF AGRICULTURE. 
boxes. Bulk cement is usually shipped in open-top cars, covered 
with tarpaulins for protection from the weather. It may 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 approximately 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. Wheelbarrows are most commonly 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 long 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 must be very 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 
