Nano-Enhanced Electrokinetic Conditioning of Expansive Soils Using MgO Nanoparticles

This study evaluated the stabilization of expansive soils using a three-phase approach combining nanoconditioning and electrokinetics. Phase 1 assessed the effects of nanoconditioning through lab tests, comparing MgO and SiO2 nanoparticles (NPs) at varying concentrations. At 3% MgO NPs, the plastic limit increased by 43.25%, and the plasticity index decreased by 22.78%. Additionally, vertical swell strain was nearly eliminated. The MgO-treated soil also exhibited enhanced air entry and residual suction values, mainly due to pore network modifications from nanoparticle void-filling. In contrast, SiO2-treated samples showed modest improvements and some reduction in swell strain; however, they also exhibited a rise in plasticity index at higher concentrations, likely due to their strong water absorption capacity. Given the superior performance and more consistent behavior of MgO NPs, MgO NPs was selected as the sole nanoparticle in subsequent phases of the study. Phase 2 then explored the effects of electrokinetics alone under varying electric potentials (10, 15, and 25 V), focusing on the independent impact of electrokinetic treatment on soil plasticity, strength, and swell potential. Results showed systematic soil property improvements, with unconfined compressive strength increasing to 175.43 kPa (a 190.93% increase) near the anode at 25 V, while the plasticity index reduced from 31.04% to 24.24% near the cathode due to enhanced electrokinetic transport. In Phase 3, combining electrokinetics and MgO NPs treatments achieved significant gains, including a 28.26% reduction in swell strain near the anode and a 221.39% increase in unconfined compressive strength near the cathode at a MgO NPs-to-water ratio of 1∶10. X-ray fluorescence confirmed MgO NPs distribution within the soil matrix, highlighting the combined treatment’s efficacy. The findings demonstrate the potential of combining nanoconditioning and electrokinetics as a viable method for stabilizing expansive soils, offering practical applications for infrastructure development and soil stabilization projects.