Electrokinetics to deal with salinity impacts on urban and rural infrastructure : a laboratory investigation

In this project, an in-situ soil treatment technique based on electrokinetics was tested in order to identify the potential of this approach to modify the engineering properties of salt affected soils. Two soils, a clay and a silty loam, collected from salt affected regions in central Victoria, Australia, were compacted in glass tanks in the laboratory to represent in-situ field density and in-situ water content. Using electrodes inserted into the soil, a direct current was passed across the soil under a voltage gradient of 0.5 V/cm for a period of 20 days. The results showed that after electrokinetic processing soil sodicity (measured as ESP - Exchangeable Sodium Percentage) decreased by 90%. The liquid and plastic limits decreased towards the cathode and increased around the anode for the clay soil. Both the linear shrinkage and free swell index decreased by 70% around anode and by 50% or more around cathode indicating the reduction in the potential for volumetric changes in the soils. The unconfined compressive strength of the soils increased at least by 30% while in some locations the strength increase was in excess of 100%. These results suggest the potential of developing this technique to deal with saline soil more effectively and efficiently, in particular in the remediation of salt affected land for infrastructure development.