UNIAXIAL COMPRESSION TEST OF BENTONITE UNDER VARIOUS CONDITIONS

Abstract

At present, underground geological disposal at depths greater than 300 m are 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 capability and low
permeability characteristics. Bentonite buffers are generally mixed with silica sand to improve workability and
reduce costs. 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. In this study, uniaxial
compression tests were carried out on specimens made of a mixture of bentonite and silica sand. The purpose of
this study is to clarify the mechanical properties of bentonite silica sand mixed specimens by comparing the results
of this study with those of the previous study [1~5]. In addition to using the temperature change by water tank
curing, as carried out in the previous study, the uniaxial compression test was also carried out while continuously
applying temperature to the specimen. As a result of the test, it was confirmed that the maximum compressive
strength tended to decrease with increasing temperature, and it was indicated that the bentonite mixed with silica
sand had temperature dependence