The amount of concrete formed a concrete mix depends on various factors such as water-cement ratio, size of aggregates, compaction, etc. But a rule-of-thumb, as given below, may be used to find out the approximate yield of concrete from a given concrete mix.
If the proportion of concrete is a:b:c i.e. If a parts of cement, b parts of sand and c parts of coarse aggregates are mixed by volume, the resulting concrete will have a volume of 2/3(a+b+c).
The yield of concrete can be determined more accurately by considering the absolute volumes of various components of concrete plus the volume of entrapped air. In well compacted concrete, the volume of entrapped air is less than 1 per cent and therefore it can be neglected.
Let w, a, b and c be absolute volumes of water, cement, fine aggregate and coarse aggregate respectively. Then, w+a+b+c=1. The value of absolute volume can be obtained by the relation:
Absolute volume = Weight of the materials/(Apparent sp.gr.) x (unit wt of water)