Basic physicochemical and mechanical properties of domestic bentonite for use as a buffer material in a high-level radioactive waste repository

The physicochemical, mineralogical, hydraulic, swelling and mechanical properties of a domestic bentonite for use as the buffer material in a high-level waste repository have been measured. The bentonite is identified to be a Ca-bentonite, and the hydraulic conductivity of the compacted bentonite with the dry density higher than 1.4 Mg/m3 is lower than 10-11 m/s. When the dry densities are 1.4 to 1.8 Mg/m3, the swelling pressures are in the range of 6.6 to 143.5 kg/cm2. The unconfined compressive strength is about 94 kg/cm2, and the coefficient of volume change and the coefficient of consolidation are in the range of 0.00249 to 0.02142 m2/MN and 0.018 to 0.115 m2/year, respectively. (author)