Mechanical and environmental characteristics of geogrid-reinforced waste foundry sand beds

Different waste materials, such as fly-ash and bottom-ash, slag waste and construction and demolition waste have been extensively studied to replace depleting natural granular materials for fill applications. Waste foundry sand (WFS), a by-product from the aluminium metal-casting industry, is one such waste material that can be a viable fill material. In the current study, extensive large-scale model experimental tests were carried out on geogrid-reinforced WFS beds to understand their load–settlement behaviour. Basic characterisation studies on WFS included gradation, specific gravity, morphology, chemical composition and compaction testing. During large-scale model experimental  testing, the geogrid reinforcement was placed at an optimum placement depth, and the maximum improvement in the load-carrying capacity of the footing resting on the reinforced WFS layer was quantified in terms of bearing capacity ratio (BCR). The BCR of reinforced WFS beds was found to be in the range of 1.3–2.0 based on the test conditions considered in the study. The reduction in the settlement of footing on reinforced WFS beds was also quantified. Additionally, the environmental impact of using WFS in reinforced foundation beds was assessed through leachate tests. The dissolved metal concentrations from leachate studies were found to be within permissible limits.