Consolidation and creep phenomena in a sand-bentonite mixture under controlled suctions

Investigating the creep of expansive unsaturated soils is necessary to simulate the long-term deformations that can cause structural failures. Hence, this paper presents a laboratory investigation of the consolidation and creep of an artificially prepared sand-bentonite mixture consisted of 40% commercial bentonite at controlled suction levels of zero, 100 kPa, 200 kPa, 400 kPa, and 800 kPa. A modified osmotic oedometer was utilised to apply vertical net stress and the desired matric suctions. After conducting the consolidation tests on samples, the last loading step was kept for extra 72 h to assess the creep behaviour of expansive unsaturated samples, and the creep coefficients (C-alpha) at different suctions were calculated. The results showed that the swelling index (C-s) gradually decreased with an increase in the amount of suction and a negligible value of the parameter is observed at higher levels of suction. Also, the creep coefficient decreased with an increase in the amount of suction value.