Abstract
Disposal facilities of low-level radioactive waste facilities underground use a sand-bentonite mixture as the buffer material. Tests have been performed to see if this mixture materials can be compacted on site. This sand-bentonite mixture is in an unsaturated condition and takes several decades to become saturated by underground water. A triaxial compression apparatus with variable suction control was used on the sand-bentonite mixture compacted with the optimum water content and maximum dry density to perform a net mean principal stress load, unloading test and shear test to investigate the effect of suction on the shear characteristics of the mixture. Suction minimizes the volume change in the sand-bentonite mixture as well as providing evidence of reductions in volume by unloading suction during the net mean principal stress load test. An greater suction was found to increase the shear strength and stiffness.
