Partially Compacted Weight of Concrete as a Measure of Workability.

A study of the compacting-factor method of measuring workability of small-aggregate concrete (1½ in.) indicated that: (a) the degree to which concrete heaps when a mold is allowed to overfill from the discharge of a mixer reaches a maximum at an intermediate workability and decreases as the mixture gets either drier or wetter; and (b) the net, loose weight of concrete in a mold after strike off increases with increasing workability. The net, loose weight of concrete in a mold filled to overflowing and then struck off could form the basis for controlling workability of mixtures having a slump not greater than 3 in. Studies using mixtures with 6-in. aggregate indicated that heaping weight, struck-off weight, and compacting factor increase with increased water content until the slump reaches from 1½ to 3 in. and then they decrease. Routine determinations of heaping weight or struck-off loose weight might be used to detect batches of excessive or deficient water content which could be rejected before delivery to the forms. [ABSTRACT FROM AUTHOR]