84 
CONCRETE SILOS 
tion of one sack of cement to 2 cubic feet of clean, coarse sand, and 3 
cubic feet of screened gravel, the latter to contain no particles smaller than 
3^ -inch, nor larger than one inch. The concrete must be thoroughly mixed 
with enough water to flow with slight agitation. The following table 
shows the thickness of floor, amount and spacing of reinforcing and the 
amount of materials needed for tank floors of various sizes. 
Materials and Reinforcing for Tank Floors 
Diam. 
of Silo 
and 
Tank 
in Feet 
Total 
Thickness 
of 
Floor 
Cement 
Required 
Barrels 
Sand 
Required 
Cubic 
Yards 
Gravel 
Required 
Cubic 
Yards 
Pounds of 
^'8-inch 
Round 
Reinforcing 
Rods 
Required 
Pounds of 
}^-inch 
Round 
Reinforcing 
Rods 
Required 
No. of 
Lengths 
Spacing of 
Reinforcing 
Rods 
(Inches apart) 
10 
7" 
2.4 
.87 
1.4 
205 
34-16' 
4" to 8" 
12 
83^" 
4.2 
1.52 
2.5 
439 
41-16' 
5" to 8" 
14 
10" 
6.7 
2.42 
3.9 
535 
50-16' 
5" to 8" 
16 
10" 
8.7 
3.17 
5.1 
771 
90-16' 
4" to 8" 
Before placing any of the concrete, reinforcing rods for the floor 
should be laid down upon the platform, as shown below. Begin to lay 
the rods at the center, at the closest spacing shown in the table, then 
lay the remaining rods running the same direction, working to the wall 
where the greatest spacing shown in the table may be used. The rein- 
forcing should then be placed in the other direction in the same manner, 
and wired at intervals of 2 or 3 feet with ordinary hay-baling wire. 
Showing the method of placing reinforcing rods in the bottom of the tank floor. 
