Synergistic Stabilization of Clay Soil Using Magnesium Chloride and Saw Dust Ash: A Strength Behavior Study

Abstract

Soil stabilization remains a critical concern in geotechnical engineering particularly for clay soils exhibiting low shear strength and high compressibility. This study investigates the synergistic effects of magnesium chloride (MgCl₂) and saw dust ash (SDA) on the strength behavior of clay soil. An experimental program was conducted on clay soil samples treated with varying dosages of MgCl₂ (7%, 8%, and 9% by weight) combined with SDA (2%, 4%, 6%, 8%, and 10% by weight). Physical characterization included particle size distribution, Atterberg limits, specific gravity, linear shrinkage, and free swell index were determined according to British Standard (BS) and American Society for Testing and Materials (ASTM). Compaction characteristics were evaluated using standard proctor methods while strength behavior was assessed through California bearing ratio (CBR) which was conducted to measure a soil's ability to support loads. Unconfined compression strength (UCS) was carried out to determine the compressive strength of soil and direct shear box testing was conducted to determine the shear strength of soil. Together, they related to the soil's strength performance under different conditions. The 8% MgCl₂ treatment consistently outperformed both 7% and 9% treatment across all strength parameters. Results showed a very high correlation between CBR, UCS and cohesion. The analysis revealed a strong positive correlation with an R² value of 0.8296 (CBR=0.0114 and UCS=0.2235), 0.8728 (cohesion=0.0747 and UCS=-10.955) as well as 0.9153 (CBR=0.1495 and cohesion=1.9479). The study confirms that the cohesion shows the strongest and most consistent strength performance. Thereby, this practical approach is cost-effective and environmentally friendly.