Experimental study of swelling deformation for compacted bentonite-sand mixture as buffer material

GMZ001 bentonite is chosen as the main buffer material in high level radioactive waste(HLW) geological disposal.Laboratory swelling test was conducted on compacted mixture of GMZ001 bentonite and quartz sand in different addition of 0,10%,20%,30%,40% and 50%.Test results show that the swelling strain of the mixture is exponentially increased with lapse of time.The maximal swelling strain shows a linear increase with initial dry density;while it increases with sand addition presents a parabola.By the use of the concept bentonite filled density,an optimum model has been established to describe the relationship between maximal swelling strain with sand addition percentage and initial dry density,which provides a useful tool for predicting and controlling the swelling behavior of bentonite-sand mixture in HLW geology disposal.