0.46 by weight satisfies the strength requirements. To meet both specifications, you would select a w/c ratio of
0.46. Since the maximum size of coarse-aggregate must not exceed one-fifth the minimum wall thickness nor
three-fourths of the space between the reinforcement and the surfaces, the maximum size of coarse-aggregate you
will choose is 1 1/2 inches. Because of the severe exposure conditions, the concrete could contain entrained air.
Table 1-5, page 1-18, shows that the recommended air content is 5.5 ƒ 0.5 percent. Assuming that vibration will
consolidate the concrete, Table 2-4 indicates a recommended slump ranging from 1 to 3 inches. The trial batch
proportions are now determined. Choosing a batch containing 20 pounds of cement for convenience, the mixing
water required is 20 x 0.46 = 9.2 pounds. Select and weigh representative samples of fine and coarse aggregates
and record their weights in column (2) of Figure 2-1 on page 2-8.
2-7
EN5466
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