Authors: Owoyemi, O.O., Ejikunle, O.B. and Afolagboye, L.O.
Abstract
Recycling waste glass for subgrade soil improvement not only contributes to the development of sustainable and resilient highways but also mitigates the environmental impact of the vast quantities of glass generated daily. This study examines the potential of using waste glass to enhance the geotechnical properties of soil intended for highway subgrade applications. Soil sample was obtained from a borrow pit in Oyun, Southwestern Nigeria, where lateritic soils are quarried for construction purposes. The mineralogical and geochemical properties of the natural soil were analyzed using X-ray diffraction (XRD) and X-ray fluorescence (XRF). Pulverized waste glass underwent grain size distribution analysis, and the soil samples were mixed with waste glass in proportions of 0.5%, 1%, 1.5%, and 2% by weight. The impact of waste glass powder addition on Atterberg limits, linear shrinkage, compaction parameters, swell potential, and both soaked and unsoaked California Bearing Ratio (CBR) was investigated. The aging effect on the CBR of the stabilized samples was assessed by repeating the soaked CBR tests after 7, 14, and 21 days. Results indicated that the liquid limit, plastic limit, plasticity index, linear shrinkage, swell potential, and of the stabilized soils decreased with increasing glass content. Conversely, the maximum dry density and both soaked and unsoaked
CBR values increased, while the optimum moisture content decreased with higher glass content. The stabilized soils maintained their strength even after 21 days of soaking. Waste glass, even at a 0.5% inclusion by weight, acts as an effective cementing agent, improving soil properties for highway foundations.