Specific gravity and absorption capacity of fine and coarse aggregate

Aggregates generally contain pores, both permeable and impermeable, for which specific gravity has to be carefully defined. With this specific gravity of each constituent known, its weight can be converted into solid volume and hence a theoretical yield of concrete per unit volume can be calculated. Specific gravity of aggregate is also required in calculating the compacting factor in connection with workability measurements. This test method covers the determination of bulk and apparent specific gravity, 23/23⁰C (73.4/72.4⁰F) and absorption capacity of fine aggregate. This is used for i) calculation of the volume occupied by the aggregate of varying mixtures on an absolute volume basis, ii) the computation of voids in aggregate and iii) the determination of moisture in aggregate.

The specific gravity of a porous solid, when the volume of the solid as used in the calculation includes both the permeable and impermeable voids. Bulk Specific Gravity (also known as Bulk Dry Specific Gravity) is the ratio of the weight in air of a unit volume of aggregate at a stated temperature to the weight in air of an equal volume of gas free distilled water at the stated temperature.

Apparent specific gravity is the ratio of the weight in air of a unit volume of the impermeable portion of aggregate (does not include the permeable pores in aggregate) to the weight in air of an equal volume of gas-free distilled water at the stated temperature.