To determine the free swell index of soil as per IS: 2720
(Part XL) - 1977.
Free swell or differential free swell, also termed as free swell
index, is the increase in volume of soil without any external
constraint when subjected to submergence in water.
i) IS Sieve of size 425µm
iii) Balance, with an accuracy of 0.01g
iv) Graduated glass cylinder- 2 nos., each of 100ml capacity
i) Take two specimens of 10g each of pulverised soil passing
through 425µm IS Sieve and oven-dry.
ii) Pour each soil specimen into a graduated glass cylinder of
iii) Pour distilled water in one and kerosene oil in the other
cylinder upto 100ml mark.
iv) Remove entrapped air by gently shaking or stirring with a
v) Allow the suspension to attain the state of equilibrium (for
not less than 24hrs.).
vi) Final volume of soil in each of the cylinder should be read
REPORTING OF RESULTS