Assessing the synergistic effects of GGBS and glass fiber on expansive soil behavior using response surface methodology

Numerous techniques are available to improve soils characterized by inadequate shear strength, bearing capacity, and other swelling parameters, which can jeopardize the stability of several infrastructure projects. This study explores the potential of sustainable utilization of ground granulated blast furnace slag (GGBS) and glass fibres (GF) with varying quantities and aspect ratios. A unique approach was formulated to optimize additive dosages, incorporating a central composite design within the framework of Response Surface Methodology. This methodology was validated through both experimental outcomes and analysis of variance (ANOVA). Subsequently, the stiffness behaviour of the soil was assessed by conducting a cyclic triaxial test to determine the resilient modulus of both untreated and stabilized soil. The formulated methodology employs input parameters ranging from 0 to 30% for GGBS, 0–2% for GF, and 300 to 750 for GF aspect ratio, while the output response is characterized by unconfined compressive strength (UCS). Though the soil exhibited an increase in strength with GGBS, it also revealed an increased brittleness, which was proportional to the amount of GGBS added. The inclusion of GF was intended to counteract the brittleness resulting from the incorporation of GGBS into the soil, and the improved stress-strain response was evident in experimental outcomes of soil treated with both GGBS and GF. The formulated approach revealed the optimal values to be 24% GGBS and 0.78% GF, along with an aspect ratio of 512. The utilization of the optimal GGBS and GF-treated soil resulted in a significant 72% enhancement in unconfined compressive strength while indicating an approximately threefold increase in resilient modulus compared to the natural soil.