Improvement of Soft Clays by High-Voltage Electrokinetics

Abstract

The theory of high-voltage electrokinetics in clay-water-electrolyte systems was developed. Upon application of a nonuniform high-voltage direct-current (DC) field to a clay-water-electrolyte system through electrically insulated electrodes, electrophoretic and dielectrophoretic forces are generated and imposed on clay particles. The former are induced by the interaction of a DC field with negatively charged clay particles, whereas the latter are induced by the interaction of the electrical diffuse double layer in a nonuniform electric field. The effects of high-voltage electric fields to the properties of a disturbed marine sediment were investigated in an experimental program. The primary experimental data indicate that high-voltage electrokinetics increased undrained shear strength of a marine sediment up to 267% and the pullout resistance of steel plates up to 88%. The effect of high-voltage electrokinetics was irreversible even long after withdrawal of the electric fields. The treatment was energy efficient and had minimal electrochemical reactions due to insulation of the electrodes.