A Comparative Study of Ground Granulated Blast Furnace Slag and Bagasse Ash Incorporation on Enhancing Mechanical Properties of Expansive Soil

Abstract

Expansive soils swell when wet and shrink when dry, causing differential settlements that can lead to structural failures in roads and buildings. In cases where these soils cannot be avoided, improving their stability is essential. This study investigates the use of two binders, ground granulated blast-furnace slag (GGBS) and bagasse ash (BA), byproducts of steel and sugarcane processing, respectively, to reduce soil swelling and enhance stability by assessing the mechanical behavior of reinforced expansive soil. To evaluate the behavior of reinforced expansive soils, tests such as Atterberg limits, compaction, swelling potential, and direct shear were conducted. Results indicated that as reinforcement levels increased to an optimal threshold (3% GGBS and 12% BA), the optimum moisture content rose, while maximum dry unit weight generally decreased. A 15% increase in moisture content and a 3.16% decrease in maximum dry unit weight were observed with reinforcement. Cohesion decreased by 27% in soaked conditions and 31% in unsoaked, while the angle of internal friction rose by 106% and 111%, respectively, at the maximum reinforcement threshold. These additives also improved shear strength, reduced swelling potential, and lowered plasticity index, shifting the soil behavior from clay-like to silty. The results show that bagasse ash and GGBS effectively enhance soil properties and provide a sustainable solution for soil stabilization in construction.