Combining different controlled-suction techniques to study expansive clays

摘要

Artificially prepared expansive clays are commonly proposed as isolating materials in the construction of engineered barriers for radioactive waste repositories. The Engineered Barrier Emplacement Experiment at the Mont Terri Rock Laboratory (Switzerland) considered the use of bentonite-based granular material prepared at very low water content. An exhaustive experimental program was carried out to characterize the hydro-mechanical response of this artificially aggregated material. Due to the elevated initial suction, the characterization required the use of different controlled-suction techniques to cover the large suction range between the initial state and the saturated condition. This paper presents water retention properties and oedome-ter under constant volume results along wetting and drying paths combining two different controlled-suctio techniques; namely, vapor transfer and axis translation techniques. Material fabrication, equipment and experimental difficulties associated with the transition of the techniques along the hydraulic paths are commented. Finally, experimental results are interpreted in the light of a suction-dependent elastoplastic model.