Water retention behaviour of compacted bentonites: experimental observations and constitutive model
1 University of Liege, Quartier Polytech 1, Allé de la Découverte 9, 4000 Liege, Belgium
2 Ecole Polytechnique Fédérale de Lausanne, Station 18, 1015 Lausanne, Switzerland
3 Commissariat à l’énergie atomique et aux énergies nouvelles (CEA), Centre de Saclay, Gif-sur-Yvette, 91191 cedex, France
4 Agence nationale pour la gestion des déchets radioactifs (ANDRA), rue Jean-Monnet 1/7, 92298 Châtenay-Malabry cedex, France
Bentonite-based materials are studied as potential barriers for the geological disposal of radioactive waste. In this context, the hydro-mechanical behaviour of the engineered barrier is first characterized by free swelling conditions followed by constant volume conditions. This paper presents an experimental study conducted in order to characterize the water retention behaviour of a compacted MX-80 bentonite/sand mixture. Then, based on observations of the material double structure and the water retention mechanisms in compacted bentonites, a new water retention model is proposed. The model considers adsorbed water in the microstructure and capillary water in the aggregate-porosity. The model is calibrated and validated against the experimental data. It is used for better understanding competing effects between volume change and water uptake observed during hydration under free swelling conditions.
© The Authors, published by EDP Sciences, 2016
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