This standard ( Part XL) covers a test for the determination of free swell index of soil which helps to identify the potential of a soil to swell which might need further detailed investigation regarding swelling and swelling pressures under different field conditions.
IS 2720 Pt.40-1977 history
1978IS 2720 Pt.40-1977 Soil Test Methods Part XL Determination of Soil Free Swell Index