Physical and Chemical Properties of Bentonite Modified by Electrochemical Treatment

Abstract

Expansive soils are characterized by significant swelling and shrinkage due to changes in water content, which could threaten the safety of buildings. In this study, an electrochemical treatment method was used to modify bentonite, with subsequent analysis focused on evaluating the alterations in its physical and chemical properties. The electrical resistance between the soil and the electrodes was significantly reduced by injecting a CaCl2 solution, leading to a substantial decrease in voltage loss at the anode. The thickness of the electrical double layer decreased as the Na+ cations adsorbed by smectite particles were exchanged by Ca2+ ions, which significantly decreased the water adsorption and free swelling ratio. The electrochemical treatment method removed more pore water from soil samples than the electroosmotic consolidation method. Furthermore, the results indicated that the injection of a CaCl2 solution could be effective in restraining the swelling potential of bentonite. The most suitable concentration for CaCl2 solution to modify bentonite by electrochemical treatment method might be 1 mol/L, and the injection volume could be 125 mL/L of soil. The results indicated that the electrochemical treatment method could be a promising in situ technique for modifying expansive soil.