Series-parallel structure-oriented electrical conductivity model of saturated clays

A new series-parallel model for electrical conductivity of saturated clays that considers particles structure orientation is presented in this study. The new model introduces a simple approach to consider the effect of surface conductivity of clay particles on the electrical conductivity of saturated clays. The proposed approach considers the clay particle and its surrounding diffuse double layer, as a single unit called an effective clay particle, and assigns it an isotropic apparent electrical conductivity that can be determined using a simple experimental method. Therefore, the saturated clay can be considered as a two-phase material (binary mixture) namely, free pore water and effective clay particles. Considering the clay particles structure orientation, the proposed electrical conductivity model in this study geometrically configures the components of two-phase saturated clays in a series-parallel form to determine the electrical conductivity of clay. The proposed electrical conductivity model uses one parameter that can be determined experimentally and it reflects the anisotropic condition of the clay fabric. The validity of the proposed model is verified by comparing its results with the experimental results of three different clay types reconstituted at different dry density levels and particles structure orientations. The comparison shows the accuracy of the proposed model in predicting the electrical conductivity of saturated clays.