STRESS-PATH TESTING OF EXPANSIVE COMPACTED SOILS

Two expansive materials: compacted Madrid grey clay and a mixture of sand and Madrid clay have been tested in suction controlled oedometer cells. Stress and suction reversals have been applied in order to distinguish reversible and irreversible strain components. Measured results can be interpreted in terms of a swelling microstructure and its interaction with a macrovoid structure which may either expand or collapse. Macrostructural plastic swelling deformations decrease continuously with confining stress and may reach negative values (irreversible collapse) beyond a certain confining stress which is lower than the current yield isotropic stress. (A) For the covering abstract see IRRD 881647.