Density is an important parameter for aggregate. For aggregates, density is determined by multiplying the relative density (specific gravity) of the aggregate times the density of water.

### Bulk Density of Aggregate ^{[1]}

The **bulk density or unit weight of an aggregate** is the mass or weight of the aggregate that required to fill a container of a specified unit volume.

Bulk Density = ^{Mass}/_{volume}

**Key Features:**

- If the volume is unit then, Bulk Density= Mass.
- Unit in kg/m
^{3}or lb/ft^{3}. ^{}In this definition, the volume is that contains both the aggregates and the voids between aggregates particles.- The approximate bulk density of aggregate that is commonly used in normal-weight concrete is between
**1200-1750 kg/m**.^{3}(75-110 lb/ft^{3}) - Here, the Standard test method for determining the bulk density of aggregates is given in ASTM C 29 (AASHTO T 19).
^{[2]}

### Relative Density of Aggregate ^{[1]}

The **relative density (specific gravity)** of an aggregate is the ratio of its mass to the mass of an equal volume of water.

Relative Density = ^{Mass of the Aggregate}/_{Mass of equal volume of water}

**Key Features:**

- Most aggregates have a relative density between
**2.4-2.9**with a corresponding particle (mass) density of**2400-2900 kg/m**.^{3}(150-181 lb/ft^{3}) - Here, for coarse aggregates, the standard test method has been explained in ASTM C 127(AASHTO) and for fine aggregates, the standard test method has been explained in ASTM C 128 (AASHTO).
^{[3]} - The relative density of an aggregate can be determined on an oven-dry basis or a saturated surface-dry (SSD) basis.

#### References

- Aggregates in Concrete [Design and Control of Concrete Mixtures _ EB001]
- ASTM C29 / C29M - 17a Standard Test Method for Bulk Density (“Unit Weight”) and Voids in Aggregate
- ASTM C127 - 15 Standard Test Method for Relative Density (Specific Gravity) and Absorption of Coarse Aggregate