Behavior of Bentonite-Sand Mixtures Subjected to Cyclic Drying and Wetting Paths

Soils are naturally subjected to cyclic and strong drying and wetting paths due to atmospheric conditions. Clayey soils subjected to these processes develop swelling and shrinkage deformations, which give rise to the accumulation of expansion or compression strains during suction cycles. In order to study the main features of these processes, a systematic experimental programme was performed on an artificially prepared bentonite-sand mixture using an oedometer cell. Several controlled-suction wetting-drying cycles with suction ranging between 130 MPa and 4 MPa were applied using vapour equilibrium technique. Tests were performed at different vertical net stresses. Along the successive cycles, the tested samples showed cumulative shrinkage strains at increasing vertical net stresses. Test results were interpreted and simulated using the suction-dependent elastoplastic model.