Integrated Performance Assessment of Waste Glass Fiber-Reinforced Polymer (wGFRP) as a Sustainable Soil Reinforcement Material

The present study evaluated the potential of waste glass fiber-reinforced polymer (wGFRP) as a soil reinforcement material for geotechnical applications. Laboratory model footing tests and large-scale direct shear tests were carried out on sandy soils prepared at three relative densities (Dr = 40%, 65%, and 85%) and reinforced with four wGFRP contents (0.5%, 0.75%, 1.0%, and 1.5%) to evaluate bearing capacity, settlement behavior, and shear strength characteristics. Environmental characterization and a performance-based economic assessment were also conducted to assess environmental compatibility and identify the optimum reinforcement content from engineering and economic perspectives. The results showed that wGFRP improved sand performance under all investigated conditions. Optimum performance was achieved at 0.75% wGFRP, where the ultimate bearing capacity increased by up to 92%, settlement decreased by up to 79.2%, and the internal friction angle increased by up to 6.2%. Environmental characterization indicated compatibility under the investigated laboratory conditions, with negligible trace-element release and no significant physicochemical, microstructural, or chemical degradation. The economically optimum reinforcement content depended on the selected engineering objective and the initial relative density. The findings indicate that wGFRP has strong potential as a sustainable, environmentally compatible, and cost-effective soil reinforcement material, offering a high-value reuse pathway in geotechnical applications.