This document describes the procedure for determining the free swell index of soils. The test involves taking a soil sample, drying it in an oven, sieving it to remove particles larger than 425 microns, and placing 10g of the remaining soil in each of two 100ml flasks. Kerosene is added to one flask and distilled water to the other, and both are stirred and allowed to settle for at least 24 hours. The free swell index is calculated as the percentage increase in volume of the soil-water mixture over the soil-kerosene mixture. At least three readings should be taken and averaged to obtain the final result.

1. DETERMINATION OF FREE SWELL
INDEX OF SOILS
PRESENTED BY- DAVINDERPAL SINGH
ASSISTED BY- AKHILESH KAUSHAL

2. ABOUT TEST
 IT IS A TEST OF SOIL AND COMES UNDER
SOIL MECHANICS TESTS. (GEOTECHNICAL
ENGINEERING)
 CODE USED IS:2720 (PART 40)-1977

3. APPARATUS
 IS SIEVE 425 micron (IS:460)
 100 ml CAPACITY FLASK (IS:878) TWO ARE
REQUIRED
 STIRRER (THIN ROD, CAN BE GLASS ROD)
 OVEN
 ENAMEL TRAY
 WEIGHING BALANCE (accurate upto 0.01 g)

4. PROCEDURE
 Soil sample upto 500 gram is taken from desired site and kept
in oven for 24 hours at (100-110)0C, so that sample becomes
oven dried.
 Then sample is sieved through 425 micron IS SIEVE and
sample passed is taken.
 Sample finer than 425 micron is taken in two flask of 100 ml
capacity, 10 gram in quantity in each flask.

8. PROCEDURE
 In first flask already filled with 10 gram oven dried sample
finer than 425 micron, kerosene oil is added upto 100 ml
mark.
 In second flask which is also filled with 10 gram oven-dried
sample finer than 425 micron, distilled water is added upto
100 ml mark of flask.
 Then sample are stirred well by a stirrer to remove entrapped
air in it.

10. PROCEDURE
 Then two flasks are kept ideal for not less than 24 hours
time allowing sample to swell and settle.
 Atleast Three Readings are taken and their average is
given as a result.

12. FORMULA

13. RESULT
 FREE SWELL INDEX=((VW – VK) / (VK))*100 = ((9 -8) / (8))*100 =
12.5%
 TAKE FURTHER TWO READINGS AND TAKE THEIR
AVERAGE.