WATER RETENTION AND SWELLING PRESSURE OF CLAY SOILS

Water retention curves for three clay soils are compared with the best available estimates of swelling pressure to determine whether the expected equivalence is obtained. Between pF 3 and 4 swelling pressures show agreement with water retention forces. Above pF 4, the clays become unsaturated; below pF 3, forces of attraction not accounted for in the swelling pressure estimates make water retention lower than swelling pressure.A method for calculating theoretical swelling pressures is outlined.