Mechanical and Microstructure Behavior of Expansive Soil Treated by Lime-Activated Granulated Blast Furnace Slag

Swelling soil deposits present significant environmental hazards, including space occupation, erosion and mudflows. Granulated blast furnace slag (GBFS) has been effective in improving their mechanical and physical properties. However, limited attention has been given to the use of GBFS as a granular aggregate despite its cost and energy advantages. This study investigates the impact of lime-activated GBFS on high-swelling clayey soil composed of 35% of bentonite and 65% of silty sand. Samples were mixed progressively replacing the silty sand by GBFS while maintaining a constant swelling fraction. In order to do a reliable study, various laboratory tests were conducted including sieve analysis, consistency limits, methylene blue value, modified proctor, California bearing ratio (CBR), direct shear, scanning electron microscopy analysis (SEM) and energy-dispersive X-ray spectroscopy (EDS). Results showed that GBFS increased the California bearing ratio by 3755%, reduced swelling potential and swelling pressure by 64–67% respectively, decreased plasticity index by 30% and improved soil microstructure. The optimum GBFS content for improving swelling soil properties was found to be 15%. These findings suggest that GBFS stabilization is suitable for road embankments or infrastructure projects.