Oedometric and water-retention behaviour of highly compacted unsaturated smectites

This paper summarizes the findings from an experimental program concerning the hydromechanical behavior of two smectite clays tested under high stress es. Increasing axial stress on the smectite samples under controlled relati ve humidity (suction) leads to collapse in the soil structure and increases the degree of saturation. Irreversible volume change is observed in sample s tested under cyclic suction with constant axial load. Water-retention (ad sorption and desorption) behavior of the smectite clays tested in this stud y is affected by particle size, initial void ratio, and confinement conditi ons during the tests. Laponite, which has a large specific surface area, te nds to hold more water than hectorite at a given relative humidity. More wa ter is adsorbed by samples compacted at lower axial stress.