Volumetric deformability and water mass exchange of bentonite aggregates

A constitutive model of the volumetric behaviour of bentonite aggregates is proposed. The model is based on a state function to define the inter-aggregate (microstructural) void ratio and on a mass transfer function to calculate the mass exchange between macrostructural and microstructural water. Although both functions have been used previously for clay soils, their application beyond the range for which they were derived is proposed. To evaluate whether this extrapolation is valid, data on the swelling of individual bentonite aggregates are analysed. This novel aspect of this study is significant because it is not common to analyse microstructural data directly without introducing any hypothesis about the behaviour of the macrostructure. Despite the lack of a more intensive validation, which will be conducted when more experimental data become available, the results obtained have been satisfactory.