Compression Behavior of Bentonite Powder/Pellet Mixture
This study deals with the hydro-mechanical behavior of bentonite-based materials used as sealing materials in high-level radioactive waste repositories. Many studies have been done recently on bentonite-based materials, such as the mixture of bentonite and crushed Callovo-Oxfordian (COx) claystone, pre-compacted disks of MX80 bentonite/sand mixture and MX80 bentonite pellets/powder mixture. In this study, the hydro-mechanical behavior of the mixture of MX80 bentonite powder and pellets with a proportion of 20/80 was investigated. Compared to other sealing plugs, this mixture has some operational advantages such as a lower compaction effort and reduction of technological voids between rock and seal. The compression behavior was investigated by performing suction controlled oedometer tests. Results show that the yield stress (σv) increases with suction increase; however, this effect is not obvious for suctions ranging from 9 to 138 MPa, suggesting a significant effect of soil microstructure mainly governed by the assembly of pellets.
KeywordsHydro-mechanical behavior MX80 pellet/powder mixture Suction controlled oedometer test
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