Experimental study of mechanical behaviour of compacted Czech Bentonite 75

Compacted bentonite is often planned as an engineered barrier material between host rock and canister in nuclear waste disposal repositories thanks to its favourable swelling characteristics and low permeability. This study deals with the effects of initial dry density and vertical stress on the swelling behaviour of compacted bentonite under distill water infiltration. Conventional oedometer tests were carried out on bentonite from Czech Republic named Czech bentonite 75 (B75). One-dimensional swelling tests were performed on compacted bentonite with various initial dry densities to explore the influence of vertical stress and initial dry density on swelling strain. Results show that, for all the swelling deformation tests, the swelling strain decreases with increase of vertical load and decrease of initial dry density. The coefficient of primary and secondary swelling decrease with the increase of vertical stress. The swelling pressure determined by the swell-consolidation method is higher than that by constant volume method