Performance of MX-80 bentonite seal materials in a brine environment

Abstract of the technical paper/presentation presented at:
NWMO Geoscience Seminar
June 7–8, 2017

Prepared by:
Grant Su
Canadian Nuclear Safety Commission

Abstract

MX-80 bentonite is considered as a reference bentonite for buffer and seals in geological disposal of radioactive wastes in Canada. The performance of the bentonite in a brine environment of Canadian sedimentary rocks was investigated through a laboratory program. The presentation summarizes the experiment results obtained to date. The results show that MX-80 bentonite and bentonite/sand mixture are less compressible when hydrated with brine model water; the measured swell pressure of MX-80 bentonite and bentonite/sand mixture when hydrated with brine model water is suppressed by high pore-water salinity. Different ratios of initial micro- and macro-pore volumes resulted in different levels and patterns of swelling. The retention behaviour of MX-80 bentonite is different when it is hydrated with deionized water and model water.

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