Electro-osmotic enhancement of bentonite with reactive and inert electrodes

Abstract

Electro-osmosis can be a potential improvement technique for expansive soils. One-dimensional column experiments were conducted to comprehend the impact of electro-osmosis on the consolidation behavior and the geotechnical properties of a sodium bentonite with different electrode materials, including two reactive electrodes (copper and iron) and two inert electrodes (graphite and stainless steel). The change in drainage rate, electric current and voltage loss close to the anode were similar for the four electrodes, with a rapid change stage in the first 2h followed by a slow change stage in the next 6 to 8h and finally a stable stage. The rapid voltage loss in the first stage was caused by soil cracking near the anode due to severe volume shrinkage and gas generation. Soil properties, including plasticity, swelling potential, zeta potential, and cation exchange capacity decreased emarkably in the vicinity of the anode. During electro-osmosis, the reactive electrodes caused more significant change in soil properties than the inert ones. Electro-osmosis technique can reduce the swelling potential of the bentonite, however, the zone of influence is restrained.