The bulk density or unit weight of concrete gives valuable information about the specific gravity and angular shape of concrete.actually bulk density is a ratio,how the aggregate fill of a given specimen.it's measure by filling a container of known volume in a standard manner.the bulk density depend on the specific size of aggregate particle .thus if the bulk density of aggregate is high then the amount of void is more contains in this aggregate when it's use for concrete.earlier the bulk density of concrete was a important for designing concrete.if the bulk density of concrete is low then the void is low and need not more sand or cement for fill the gap and it will be good for concrete.
