## Specific Gravity(G)

**Specific gravity** is defined as the ratio of the weight of a given volume of soil solids at a given temperature to the weight of an equal volume of distilled water at that temperature, both weights being taken in air.

**In other words**, it is the ratio of the unit weight of soil solids ( [latex] \gamma_{s} [/latex] ) to the unit weighs of water ( [latex] \gamma_{w} [/latex] ).

Thus, [latex] G = \frac{\gamma_{s}}{\gamma_{w}} [/latex]

The Indian Standard specifies 270° C as the standard temperature for reporting the specific gravity

## Mass or Apparent or Bulk Specific Gravity

It is the ratio of the bulk unit weight of soil mass (𝛾) to the unit weight of water ( [latex] \gamma_{w} [/latex] ).

Thus, [latex] G_{m} = \frac{\gamma}{\gamma_{w}} [/latex]

## Air Content

The **air content** is defined as the ratio of the volume of air voids (Va) to the volume of voids (Vv).

Thus, [latex] a_{c} = \frac{V_{a}}{V_{v}} [/latex]

## Percentage of Air Voids

The **percentage of air voids** are defined as the ratio of the volume of air voids (Va) to the total volume (V) of the soil mass. It is expressed as percentage.**Thus, **[latex] n_{a} = \frac{V_{a}}{V } \times 100 [/latex]

**Read Also:**

**What is Porosity, Void Ratio, Water or Moisture Content And Degree of Saturation of Soil**

**What is Bulk, Submerged, Dry and Saturated Density of Solids of Soil**