Strength and Volume Change Characteristics of a Sand-Bentonite Buffer

Abstract

Geotechnical tests have been performed on a potential sand-bentonite buffer for nuclear waste containment at mean effective pressures up to 1 MPa. The material exhibits the strong tendency of smectite clays to expand and its properties are time dependent. The strength of the buffer is dominated by the bentonite and in the long term the material is expected to be strain hardening. Pseudo-elastic normalized shear moduli depend on the stress level whereas the normalized shear moduli do not. The data support a conceptual model for buffer behaviour based on Critical State Soil Mechanics.