Page 42 - Masonry and Concrete

Concrete Construction Techniques
41
CONCRETE CONSTRUCTION TECHNIQUES

SEVERE
MODERATE
MILD
FIGURE 3-2
Continued

needed to produce one cubic foot of concrete. Multiply each ingredi-
ent weight times the total cubic footage of concrete required to figure
out how much of each ingredient is needed. The standard weights of
each ingredient are shown below the table. The calculated weights of
each material will have to be converted to appropriate units such as
gallons, cu. ft., bags of cement, and so on. If you are mixing by hand,
1-cubic-foot batches are a good size to work with. If you are using a
mixing machine, multiply each ingredient by the capacity of the mixer
to determine the amount of materials per batch. For example, multiply
each ingredient by three for a 3-cu.-ft. mixer.
Table B in Figure 3-3 is based on a proportional volume mix. The
2
volume of the concrete is equal to about 3 the sum of the volumes of
the individual ingredients because the sand particles and cement
paste fill in the voids between the coarse aggregate. For job-site mix-
ing, it is usually easier to proportion by volume rather than by weight

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