FREE SWELL INDEX TEST.( IS : 2720 – PART – 40 )

FREE SWELL INDEX TEST.

( IS : 2720 – PART – 40 )

Object:

To determine the free swell index of soils.

Apparatus:

1) 425 micron IS sieve

2) Glass graduated cylinders – 2 nos 100ml capacity

3) Distilled water and kerosene.

Procedure:

Take two 10 grams soil specimens of oven dry soil passing through 425-micron IS sieve. Each soil specimen shall be poured in each of the two glass graduated cylinders of 100ml capacity. One cylinder shall then be filled with kerosene oil and the other with distilled water up to the 100ml mark. After removal of entrapped air the soils in both the cylinders shall be allowed to settle. Sufficient time (not less than 24 hours) shall be allowed for the soil sample to attain equilibrium state of volume without any further change in the volume of the soils. The final volume of soils in each of the cylinders shall be read out.

Calculations:

The level of the soil in the kerosene-graduated cylinder shall be read as the original volume. The soil samples, kerosene being a non-polar liquid does not cause swelling of the soil. The level of the soil in the distilled water cylinder shall be read as the free swell level. The free swell index of the soil shall be calculated as follows:

                                                      (Vd – Vk)

Free swell index, percent       =      ----------- X 100

                                                            Vk

Where,       Vd =           the volume of soil specimen read from the graduated cylinder  

                                    containing distilled water.

                   Vk =           the volume of soil specimen read from the graduated cylinder 

                                    containing kerosene.