UNIAXIAL COMPRESSION TEST WITH VARYING SILICA SAND CONTENT, PARTICLE SIZE AND TEMPERATURE

At present, underground geological disposal at depths greater than 300 m is considered a viable disposal option for high-level radioactive waste generated from the reprocessing of spent fuel used in nuclear power plants. In geological disposal, bentonite is employed as the primary component of buffer material filling gaps between waste and geologic rock. Bentonite has remarkable water absorption swelling and low permeability characteristics. Bentonite buffers are generally mixed with silica sand to improve workability and economy. However, specification details have yet to be completely determined. It is anticipated that the buffer material will be exposed to high temperature due to the heat generated by the vitrified solid. This study aims to understand the mechanical properties of bentonite buffer material by employing uniaxial compression tests after applying temperatures between 30 °C to 90°C to bentonite specimens with different silica sand contents and particle sizes. Results of the experiment confirmed that uniaxial compressive strength tends to decrease with higher blending ratios of silica sand greater particle sizes and temperatures.