Geochemical, Geotechnical, and Microbiological Changes in Mg/Ca Bentonite after Thermal Loading at 150 °C

Bentonite buffers at temperatures beyond 100 °C could reduce the amount of high-level radioactive waste in a deep geological repository. However, it is necessary to demonstrate that buffer surrounding canisters withstands such elevated temperatures, while maintaining its safety functions (regarding long-term performance). For this reason, an experiment with thermal loading bentonite powder 150 was arranged. The paper presents changes Czech Mg/Ca underwent during heating for one year. These were examined by X-ray diffraction (XRD), analysis evolved gas (TA-EGA), aqueous leachates, Cs sorption, cation exchange capacity (CEC), specific surface area (SSA), free swelling, saturated hydraulic conductivity, water retention curves (WRC), quantitative polymerase chain reaction (qPCR), and next-generation sequencing (NGS). It concluded montmorillonite partially altered, terms magnitude charge density particles, based on measurement interpretations CEC, SSA, sorption. Montmorillonite alteration towards low- or non-swelling clay structures corresponded well significantly lower swelling ability uptake ability, higher conductivity thermally loaded samples. Microbial survivability decreased time, but not completely diminished, even samples heated