Relationship Between Microstructure and Electrical and Hydraulic Properties of Sand-Clay Mixtures

摘要

A series of laboratory experiments were performed on saturated sand-clay mixtures, including electrical properties, permeability and porosity. Different mixtures and configurations of quartz sand and 0 to 10% Na-montmorillonite clay saturated with solutions of CaCl(sub 2) and deionized water were investigated. The electrical properties were dependent on clay content, fluid conductivity, and microstructure in a complex fashion. Two main regions of conduction exist: a region dominated by surface conduction and a region where the ionic strength of the saturating fluid controlled conduction. For low fluid conductivities, the sample geometry was found to greatly affect the magnitude of the surface conductance. The influence of the microstructural properties on the electrical properties was quantified by estimating formation factors,(Lambda)-parameters, and surface conductances. We suggest that high and low bounds on the expected surface and bulk conductance of natural systems can be derived from the measurements on these artificial configurations.