Size:The size of coarse aggregate depends on the use to which the concrete is to be put.

For ordinary construction of residential or other building, 20mm is the maximum size that will be used.

Shape: The shape of aggregate is an important characteristic as it affects the workability of concrete. Angular aggregate shows better interlocking effect, which gives a superior concrete.

Surface texture: The surface of the aggregates may be smooth, polished, rough or dull. A rough surface provides more area for bonding with cement paste and gives more strength. Rounded aggregate with smooth surface will require less cement paste and hence increase the yield per bag.

Water absorption: The water absorption of coarse aggregate is measured by the percent increase in weight of an oven dry sample after immersion in water for 24 hours. This gives more realistic result. Water absorption will decrease the water content in concrete and the concrete will require a higher/ cement ratio. The water absorption will depend upon the porosity of aggregate, and more water absorption will affect both workability and durability of the concrete.

Soundness: Soundness to the resistance offered by the aggregates, to any type of volume change. The change may be in temperature, alternate wetting and drying in potable water. The soundness measured by immersing the aggregate in either sodium or magnesium sulphate and oven drying it under specified conditions.

Specific gravity: It is ratio of dry weight of aggregate to the weight of equal volume of water. The specific gravity of aggregate is determined along with the water absorption as specified in IS 2386 part lll 1963.

Bulk density: The ratio of net weight of aggregate to the volume of aggregate given bulk density. The bulk density is generally expressed as kg/ liter .