Innovative Electrokinetic Treatment of Expansive Soils: Evaluating MgCl 2 and CaCl 2 as Stabilizing Agents

Expansive soils, known for their tendency to swell and shrink with moisture fluctuations, pose significant challenges in geotechnical engineering. These volume changes can generate substantial stresses on infrastructure, leading to foundation cracking and persistent pavement distress. This study investigates a non-destructive electrokinetic treatment method utilizing MgCl2 and CaCl2 to improve the engineering behavior of expansive soils. A 1% MgCl2 or CaCl2 solution and an applied electric potential of 15 V over 7 days were used in all tests. Comprehensive analysis of moisture distribution, pH variation, unconfined compressive strength, and swelling behavior revealed distinct treatment mechanisms between the two salts. MgCl2 treatment produced significant spatial heterogeneity, characterized by dehydration near the anode and moisture accumulation at the cathode, resulting in substantially enhanced soil strength (up to 300% increase near the anode) but variable swelling behavior across the specimen. In contrast, CaCl2 treatment yielded elevated moisture content throughout the specimen with more spatially homogeneous mechanical properties and less pronounced strength improvements. The divergent behavior of swell strain and moisture distribution can be attributed to differences in cation mobility, hydrated radius, and their specific interactions with clay particles, which influence electroosmotic flow and diffuse double-layer compression.