Physico-chemical effects on clay due to electromigration using stainless steel electrodes

Abstract

The physico-chemical changes in clay soils due to the application of electrokinetics are difficult to predict with accuracy because of the very wide range of parameters interacting. The effects of the application of an electrical gradient across controlled specimens of a pure form of kaolinite using stainless steel electrodes and a deionised water feed to the electrodes, to mimic electrokinetic stabilisation without the stabiliser added, are reported. The specimens in which electrical and chemical changes were induced over different time periods (3, 7, 14 and 28 days) were subsequently tested for Atterberg limits, undrained shear strength, water content, pH, conductivity, Fe concentration and zeta potential. Changes in strength and plasticity indices were attributed to electrolysis, electro-osmosis, electrode degradation, clay mineral dissolution, ion movement due to electromigration, cation exchange reactions and precipitation of reaction products.