SPECIFIC GRAVITY OF SOIL, IS: 2720 Part-3/: (1980)
Scope: To determine specific gravity of soil sample.
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.
- 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 :-
- 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).
- Take 50 g of oven dried sample and pass it through 2-mm IS test sieve.
- Weigh 5g to 10g of sample passing through 2 mm IS sieve and transfer it to the density bottle.
- The bottle and contents together with the
stopper shall be weighed to the nearest 0.001g (M₂).
- 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.
- The bottle and contents shall then be placed in the desiccators and the liquid is added until the bottle is full.
- The stopper shall then be inserted and the
weight is taken in g (M₃).
- 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.