Effect of Synthetic Geotextile on Stabilization of Expansive Subgrades: Experimental Study

Structures constructed on expansive soils experience higher upward pressure due to their swelling characteristics. Various conventional treatment methods developed to counteract swell–shrink characteristics of expansive soil are deemed time consuming and not feasible for use in pavement. Geotextiles (GTs) have been used as a filtration and separation medium; however, their effect on swell pressure and shear strength of expansive soil has not been well explored. This study aimed to address these issues by using GT to control swelling behavior, drain moisture content, and provide support at the soil interface. Swell pressure and shear strength were quantified by constant volume swell pressure and direct shear and unconfined compressive strength tests, respectively. The influence of single-layer, double-layer, and triple-layer GTs at varying depths was studied. The higher tensile strength of the GT layer restrained the swell pressure mobilized by resisting internal soil movements and facilitating in-plane drainage conditions. Additionally, soil–geotextile interfacial interactions were observed to contribute to improvement in shear strength. Comprehensive statistical analysis using one-way analysis of variance (ANOVA) was carried out on swell and strength properties. The present study ascertained the use of GT for the dual function (i.e., strength and swell control) of stabilizing expansive subgrades.