Stress path dependence of hydromechanical behaviour of compacted scaly clay in wetting and drying suction controlled oedometer tests at constant vertical net stress

The results are presented of an experimental programme devoted to investigating the volumetric strain and water ratio (volume of water to volume of solids) evolution of a compacted scaly clay stressed by wetting and drying cycles in suction-controlled oedometer tests. The stress paths applied included loading and unloading cycles at constant matric suction and suction controlled wetting-drying cycles at constant vertical net stress. The test results show that during wetting and drying cycles the samples experienced irreversible shrinkage or swelling strains depending on the stress path applied. Irreversible water ratio increases were always observed in these cycles. However, a quasi-reversible response both in terms of volumetric and hydraulic behaviour was approached as the number of cycles increased. The main characteristics of material behaviour are delineated and discussed