# Test of Specific Gravity | Properties of Soil | Soil Mechanics

Contents

## Test of Specific Gravity

• The specific gravity of soil can be computed using a 50 ml density bottle, 500 ml flask, or by pycnometer.
• The density bottle method is the most accurate among all & is suitable for all types of soil.
• Flask & Pycnometer is suitable to be used for coarse-grained soil &  If it is used for fine-grained soil then kerosene is used in the test instead of water  (  as kerosene is a better wetting reagent than water)
• In the density bottle, only kerosene is used.
• Steps of observation in all same.

Density bottle⇒all types of soil ⇒ only kerosene used.

• Coarse-Grained soil ⇒ Water /Kerosene.
• Fine-Grained soil ⇒Only Kerosene Used.

The process of determining specific gravity are same for a 50 ml density bottle, 500 ml flask, or Pycnometer. Here we use a pycnometer.

W1=Weight of the empty pycnometer.

W2= Weight of pycnometer + Dry soil.

W3= Weight of pycnometer + Dry soil + water.

W4= Weight of pycnometer + water.

$$\mathrm{G} / \mathrm{GS}=\frac{\text { Weight of solid of given soil }}{\text { weight of standard fluid of same volume }}$$

Standard Fluid=Water

$$G=\frac{Ws}{Ww orWk}$$ $$G=\frac{ρ_s}{ρ_w or ρ_k}$$ $$G=\frac{Ms}{Mw or Mk}$$

Mass of solids Ms = M1-M2 =Mass of dry soil =Md

Mass of water in stage 3 = M3-M2

Mass of water in stage 4 = M4-M1

(Mass of water having volume same as that of solids= Mass of water in stage 4 -Mass of water in stage in stage 3)

Mass of water having volume same as that of solids= (M4-M1)-(M3-M2)

=M4-M3+M2-M1

=M4-M3+Md

Or M4+M3-Md+Mw(whose volume is the same as that of solids )

Mw=M4-M3+Md

$$G=\frac{M2-M1}{M4-M3+M2-M1}$$

$$G=\frac{Md}{M4-M3+Md}$$  ***

G = Specific Gravity of solid.

Note: Kerosene is used instead of water for fine-grained soil. Then Specific Gravity is calculated as

$$G=\frac{M2-M1}{M4-M3+M2-M1}×Gk$$  ***

Gk = Specific Gravity of Kerosene.

 Subject Soil Mechanics Unit Soil Formation & Properties of Soil Topic Test of Specific Gravity Next Topic Test of Unit Weight of Soil Previous Topic Interrelationship Between the Properties of Soil