A compacted mixture of Kunigeru Vi bentonite and D-sand is being considered for use as an engineered barrier in low-level radioactive waste disposal facilities in Japan. An important issue is the maintenance of hte retardation property of the mixture during shear that might be induced in such barriers by earthquakes and/or gradual tectonic deformations occurring over the design life of the facility. To investigate this issue, comparative tests on a bentonite-sand mixture and kaolin-sand mixture were ocnducted by means of a recently-developed coupled shear and permeability testing apparatus under temperature controlled condition. In addition to permeability, the specific storage of bentonite-sand specimen during shear is also systmeatically evaluated with the new analytical theory for the constant flow permeability test. The present study reveals that 1) temperature control is preferred for measuring the permeability of extremely-low permeability materials with the constant-flow pump method; 2) both the permeability and specific storage of the mixture of Kunigeru Vi bentonite and D-sand (bentonite to sand weight ratio = 15.85) were not significantly influenced by shear strains up to 3
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