Specific Gravity of Soil as per IS: 2720 Part-3 (1980) with Procedure, Lab Report, Formula

SPECIFIC GRAVITY OF SOIL, IS: 2720 Part-3/: (1980)

Scope: To determine specific gravity of soil sample.

What is specific gravity of soil ?

The specific gravity of soil is an important weight-volume property that is helpful in classifying soils and in finding other weight-volume properties like void ratio, porosity, and unit weight. The specific gravity of soil is the ratio of the unit weight of solid particles in the soil to the unit weight of water at equal volume.

The values of specific gravity soil particles lie within the range of 2.65 to 2.85. Soils containing organic matter and porous particle may have specific gravity values below 2.0 while soils containing heavy substances may have values above 3.0.

IS Code For Determination of Specific Gravity of Soil Sample :-

• lS: 2720 (Part-3/Sec-1): 1980

APPARATUS REQUIRED FOR THE TEST :-

• Specific gravity bottle of 50ml capacity.
• Desiccator
• Electronic weighing balance with accuracy 0.001 g.
• Oven–to maintain the temperature at 105ºC to 115ºC.
• Wash bottle
• 2mm lS sieve
• Air free Distilled water

Specific gravity bottle for soil test

Dessicator

Digital Oven

PROCEDURE OF THE TEST :-

1. The complete density bottle with stopper, shall be dried at 105ºC to 115ºC, cooled in the desiccators and weighed to the nearest 0.001 g (M₁).
2. Take 50 g of oven dried sample and pass it through 2-mm IS test sieve.
3. Weigh 5g to 10g of sample passing through 2 mm IS sieve and transfer it to the density bottle.
4. The bottle and contents together with the stopper shall be weighed to the nearest 0.001g (M₂).
5. Sufficient air-free distilled water shall be added so that the soil in the bottle is just covered. Shake the bottle and the entrapped air is removed by heating the density bottle placed on a water-bath.
6. The bottle and contents shall then be placed in the desiccators and the liquid is added until the bottle is full.
7. The stopper shall then be inserted and the weight is taken in g (M₃).
8. The- bottle is completely filled with air free distilled water, insert the stopper, and weigh it in g (M₄).

CALCULATION :-

Where,

G = Specific gravity of the soil sample,

Gl = Specific gravity of the liquid used, at the constant temperature

M₁ = mass of empty density bottle in g

M₂ = mass of density bottle with dry soil in g

M₃ = mass of density bottle, soil and liquid in g

M₄ = mass of bottle when full of liquid only in g

REPORT :-

The average of the values obtained shall be taken as the specific gravity of the soil particles and shall be reported to the nearest 0.01. If the two results differ by more than 0.03 the tests shall be repeated.