Effect of salinity on the effective stress of compacted bentonites

Adopting a double-porosity macroscopic modelling framework, a general formulation of the effective stress in compacted bentonites is derived from basic thermodynamic principles. The formulation indicates that, when there is equilibrium between macrostructural and microstructural water, the effect of salinity is affected by a factor that is equal to the ratio of the overall bulk modulus of the soil to that of the aggregates. The analysis of many well-tested salinisation experiments has shown that it is advisable to account for this factor. In double porosity systems, this factor represents how the effect of salinity is attenuated as the increment of intra-aggregate porosity stabilises, and the increase in total porosity becomes almost equal to the increase in macrostructural porosity.