To determine the specific gravity of fine-grained soil by density
bottle method as per IS: 2720 (Part III/Sec 1) - 1980.
Specific gravity is the ratio of the weight in air of a given volume
of a material at a standard temperature to the weight in air of an
equal volume of distilled water at the same stated temperature.
i) Two density bottles of approximately 50ml capacity
ii) Constant temperature water bath (27.0 + 0.2 °C)
iii) Vacuum desiccator
iv) Oven, capable of maintaining a temperature of 105 to 110 °C
v) Weighing balance, with an accuracy of 0.001 g
PREPARATION OF SAMPLE
The soil sample (50 g) should if necessary be ground to pass
through a 2 mm IS Sieve. A 5 to 10 g sub-sample should be
obtained by riffling and oven-dried at a temperature of 105 to
i) The density bottle along with the stopper, should be dried at
a temperature of 105 to 110 °C, cooled in the desiccator and
weighed to the nearest 0.001 g (W1).
ii) The sub-sample, which had been oven-dried should be
transferred to the density bottle directly from the desiccator
in which it was cooled. The bottles and contents together
with the stopper should be weighed to the nearest 0.001 g
iii) Cover the soil with air-free distilled water from the glass
wash bottle and leave for a period of 2 to 3 hrs. for soaking.
Add water to fill the bottle to about half.
iv) Entrapped air can be removed by heating the density bottle
on a water bath or a sand bath.
v) Keep the bottle without the stopper in a vacuum desiccator
for about 1 to 2 hrs. until there is no further loss of air.
vi) Gently stir the soil in the density bottle with a clean glass
rod, carefully wash off the adhering particles from the rod
with some drops of distilled water and see that no more soil
particles are lost.
vii) Repeat the process till no more air bubbles are observed in
the soil-water mixture.
viii) Observe the constant temperature in the bottle and record.
ix) Insert the stopper in the density bottle, wipe and weigh
x) Now empty the bottle, clean thoroughly and fill the density
bottle with distilled water at the same temperature. Insert the
stopper in the bottle, wipe dry from the outside and
weigh (W4 ).
xi) Take at least two such observations for the same soil.
REPORTING OF RESULTS
The specific gravity should be calculated at a temperature of
27 °C and reported to the nearest 0.01. If the room temperature is
different from 27 °C, the following correction should be done:-