Unsaturated Hydraulic Conductivity of Highly Compacted Sand-GMZ01 Bentonite Mixtures Under Confined Conditions

Highly compacted sand-bentonite mixtures are commonly recognized as potential buffer/backfill materials using in deep geological repository for high-level radioactive waste disposals. After water retention curve was determined, instantaneous profile method was employed in this paper for measuring unsaturated hydraulic conductivity of highly compacted GMZ01 bentonite and quartz sand mixture (7:3), with a dry density of 1.90 g/cm3, under confined conditions. Results show that, as suction decreased from 60 MPa to zero, the measured unsaturated hydraulic conductivity firstly decreased and then turned to increase. This phenomenon can be explained in terms of microstructure changes during hydration under constant-volume conditions.