Performance comparison of different electrode materials for electro-osmosis treatment on subgrade soil

Abstract

During the service life of subgrade, the moisture content increase on compacted subgrade soil can lead to bearing capacity serious degradation of the soil and exaggerated deformation. Electro-osmosis drainage is an effective method in reducing the moisture content of soil, which also serves to improve the subgrade. However, in practice, the low corrosion resistance and poor contact condition of conventional electrode materials make their energy inefficient. And the insufficient understanding of unsaturated soil electro-osmosis also limits the further application of this method. In this paper, a new type of electro kinetic geosynthetics (EKG) electrode was designed and used in electro-osmosis tests on unsaturated soil which was sampled from a reconstruction field in comparison with graphite and iron electrodes. The energy consumption, effective voltage variations, current variations and change in moisture contents under different voltage gradients were analyzed. A one-month field mesoscale test was conducted to verify the feasibility and efficiency of the new EKG electrode. Test results indicated that electro-osmosis drainage performed well with three kinds of electrode materials and the moisture reduction had reached 8.5–15.4%. The contact resistance of iron electrode would reach 1.8–4.1 times that of the EKG and graphite electrodes due to material corrosion. The newly-designed EKG electrode could reduce contact resistance by 19.7–40.8% for the layered fiber structure could enlarge the contact area between soil and electrodes.