Volumetric behaviour of compacted London Clay during wetting and loading

In this study, the mechanical behaviour of a compacted clay in equilibrium with the atmospheric pressure was investigated. Samples of London Clay were compacted to the same initial conditions, corresponding to dry of optimum moisture content on a Proctor plot, and were taken along complex stress paths, involving wetting under a constant vertical stress, wetting under a condition of zero volumetric strain, and loading and unloading at a constant value of matric suction. Tests were performed with a combination of standard and osmotic oedometers-the latter developed specifically at Imperial College London to test unsaturated soils under atmospheric conditions. Samples taken along different hydration paths displayed similar post-yield behaviour when loaded at a constant suction, suggesting that common yield surface in the e: s: sigma(v) space (where e denotes void ratio, s is the matric suction, and sigma(v) is the vertical stress) controls the plastic volumetric behaviour of unsaturated London Clay during loading following monotonic hydration.