AIM:-
- To determine the free swell index of soil as per IS: 2720 (Part XL) - 1977.
PRINCIPLE:-
- 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.
APPARATUS:-
- IS Sieve of size 425µm
- Oven
- Balance, with an accuracy of 0.01g
- Graduated glass cylinder- 2 nos., each of 100ml capacity
PROCEDURE:-
- Take two specimens of 10g each of pulverised soil passing through 425µm IS Sieve and oven-dry.
- Pour each soil specimen into a graduated glass cylinder of 100ml capacity.
- Pour distilled water in one and kerosene oil in the other cylinder upto 100ml mark.
- Remove entrapped air by gently shaking or stirring with a glass rod.
- Allow the suspension to attain the state of equilibrium (for not less than 24hrs.).
- Final volume of soil in each of the cylinder should be read out.
REPORTING OF RESULTS:-
- where, Vd = volume of soil specimen read from the graduated cylinder containing distilled water.
- Vk = volume of soil specimen read from the graduated cylinder containing kerosene.
