Use of Nano-Level Constitutive Model to Predict the Volume Change Behavior of the Treated Expansive Clays

Expansive clay soils containing active clay minerals are considered to be among one of the most problematic soil types. As their overall behavior is controlled by the molecular level processes and interactions, a behavior model encompassing the contributions from these interactions is required. This interaction becomes increasingly complex for natural expansive clays where a complex composition of clay and non-clay minerals exists. The authors developed a nano level constitutive model for the natural expansive clays through a three-phased study consisting of macro level swell potential testing, micro investigation of the pre and post swell specimens, and molecular level modeling through molecular mechanics, molecular dynamics, and Monte Carlo techniques. In this paper, this nano level constitutive model, incorporating all the major contributing factors such as moisture content, density, cation exchange capacity, exchangeable cations, and interaction of clay minerals with non-clay minerals have been used to predict the swell behavior of the treated expansive clays.