Evaluation of uniaxial compression and point load tests for compacted bentonites

A compacted bentonite buffer is one of the most important components in engineered barrier systems for the disposal of high-level radioactive waste produced by nuclear power generation. The compacted bentonite buffer contributes significantly to the protection of the disposal canister against the external impact and penetration of groundwater. Therefore, it must satisfy thermo-hydraulic-mechanical requirements. Although thermal-hydraulic properties have been investigated extensively, the mechanical properties of compacted bentonite buffers have not been comprehensively evaluated. Therefore, a series of uniaxial compression and point load tests were conducted in this study. The mechanical properties of Korean compacted bentonite specimens with varying water contents and dry densities, such as uniaxial compressive strength, elastic modulus, and point load index, were obtained. As the dry density increased, the uniaxial compressive strength, elastic modulus, and point load strength index increased, whereas Poisson's ratio decreased slightly. This indicates that the uniaxial compressive strength, elastic modulus, and point load strength index are proportional to the dry density. However, the mechanical properties and water content do not exhibit a significant correlation.