Chemical stability of montmorillonite buffer clay under repository-like conditions—A synthesis of relevant experimental data

Report on THMC Modeling of the Near Field Evolution of a Generic Clay Repository: Model Validation and Demonstration

“…Pusch et al (2010) summarized two of these kinds of studies. In one study, samples of MX-80 clay saturated with weakly brackish water were heated from one end through radiation and contacted at the other end with a solution that contained about 300 ppm Na + and 10 ppm K + .…”

“…There are several field scale experiments ongoing or having been accomplished such as the FEBEX project (ENRESA, 2000). A large-scale 5-year field experiment at SKB's underground laboratory at Äspö (Pusch et al, 2010) was one of these tests: it carefully evaluated the alteration of clay minerals in bentonite by comparing the hydrothermal treated and untreated samples. The test was…”

“…In comparison with the untreated bentonite, this sample has much higher hydraulic conductivity but almost the same swelling pressure. Pusch et al (2010) mentioned that the increase in hydraulic conductivity was probably caused by an alteration in micro-structural particle morphology.…”

“…Higher temperature is certainly one of the factors that could increase the corrosion rate. A high temperature could also result in chemical alteration of buffer and backfill materials (bentonite) within the EBS through illitization and cementation, which compromise the function of these EBS components by reducing their plasticity and capability to swell when wetting (Pusch and Karnland, 1996;Pusch et al, 2010;Wersin, 2007). The swelling capability of clay is important for sealing gaps between bentonite blocks, among related EBS components, and between EBS and surrounding host rock.…”

Generic Argillite/Shale Disposal Reference Case

“…Reviews of the performance of bentonite backfill at temperatures exceeding 100 o C (e.g., Wersin et al, 2007;Pusch et al, 2010), modeling Zheng et al, 2014a), and experiment studies (e.g. Pusch et al, 2003;Caporuscio et al, 2012;Cheshire et al, 2013;Cheshire et al, 2014) of the mechanical and chemical changes at temperature up to 300 o C showed little or moderate deterioration of bentonite.…”