Electrokinetic stabilisation: an overview and case study.

This paper describes work currently underway at the University of Birmingham concerning the application of electrokinetic stabilisation to clay soils. Electrokinetic stabilisation combines the processes of electroosmosis and chemical grouting, and is most effective in silty and clayey soils where the hydraulic conductivity is low. This paper introduces electroosmotic theory and an overview of the research performed to date. Field trials are reported in which electrokinetic stabilisation is performed in a silty clay to a depth of 1.1 m below ground level. The electrodes were perforated steel tubes driven into the ground at a spacing of 2.5 m. Sodium silicate and calcium chloride solutions were introduced at the cathode and anode respectively. The results indicated significant increases in the pore water pressure close to the anode and reductions generally in the pH along the test section. However, the pH was significantly raised close to the cathode, thereby potentially creating the conditions for traditional stabilisation reactions to occur. The pore water flow was sufficiently great to inhibit the migration of silicate ions from the cathode, and only when the silicate solution was injected between the two electrodes did it enter the ground. There was an increase in plastic limit midway between electrodes after 16 days, whereas closer to the anode there was a reduction, possibly as a result of electrode degradation. [ABSTRACT FROM AUTHOR]