Swelling Behaviour of GMZ Bentonite

Gaomiaozi (GMZ) bentonite has been chosen as a matrix material of buffer/backfill materials in the deep geological disposal to isolate the high level radioactive waste in China. Swelling characteristics of GMZ bentonite and its mixtures with sand wetted with water were studied by experimental methods. The tests result shows that the relation between void ratio and the swelling pressure of compacted GMZ bentonite-sand mixtures at full saturation is independent on the initial conditions such as initial dry density and water content, and dependent on the ratio of bentonite to sand. An empirical equation is proposed to predict the swelling deformation and pressure of the mixtures with different densities and bentonite/sand ratios.