An experimental evaluation of electroosmosis treatment effect on the mechanical and chemical behavior of expansive soils

Expansive soils have a high sensitivity to water, such that their characteristics change completely by absorbing and losing water. The presence of these types of soils in a geotechnical project needs to be addressed due to some disadvantageous possibilities, such as swelling, shrinkage, and loss of strength, which may undermine the long-term performance of structures. However, expansive soils can be treated using electroosmosis technique, which is a new and effective treatment method. In this study, an expansive soil with a high swelling potential was compacted in a container and electroosmosis treatments under different voltage gradients of 0.46 V/cm, 0.92 V/cm, and 1.84 V/cm were applied for periods of 1 day, 2 days, 7 days, and 28 days. The results showed the improvement of soil around anode, where the swelling potential reduced by up to 83%, the pH reduced by up to 2.8, and the unconfined compressive strength increased by up to 800% in the best considered test. An electric field of 24 V, equivalent to the voltage gradient of 0.92 V/cm, applied for 7 days was considered as the optimum testing case to reduce the swelling potential. Chemical tests on samples taken from near anode and in-between the anode and cathode showed a decrease of pH due to the electroosmosis application. However, pH of the samples taken from near cathode increased. It was observed that the reduction of swelling potential of the highly expansive soil was attributed to the reduction of monovalent cations, especially sodium.