EXAMPLE PROBLEM: Using the mix design determined previously in this chapter, determine the total amount
of materials needed to construct the retaining wall shown in Figure 2-9. The 1-cubic-yard mix design is recapped
below.
Cement
= 7.05 sacks (Type IA)
Water
= 38.6 gallons
CA
= 17.0 cf or 1,768 lb/cy
FA
= 10.5 cf or 1,083 lb/cy
Air content
= 5 percent
Figure 2-9. Retaining wall.
Step 1. Determine the total volume of concrete required. An easy way to do this is to break the project up into
simple geometric shapes. Divide the retaining wall into two sections, the wall portion and the footing. A close
examination of Figure 2-9 shows the wall cross section is a trapezoid, which is 14 feet 9 inches high, 8 inches
wide on one end, and 1-foot wide on the other.
EN5466
2-24
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