Sustainable shotcrete production with waste glass aggregates

This study employs statistical and experimental procedures to assess the applicability of crushed waste glass to replace natural sand in shotcrete production for use in tunneling, mining and excavation industries as a support system. Mechanical strength under different uniaxial and biaxial load combinations, fracture properties, and ultra-high-speed photography of the crack growth mode in the newly developed shotcrete mixes were studied and compared against the control mix at 0% waste glass inclusion. Results suggest that shotcrete mixes containing synthetic glass aggregates exhibit similar or higher strength properties (compared with conventional shotcrete with natural aggregates) at early and late ages in both fresh and hardened shotcrete samples. Under biaxial stress conditions, in particular, the new glass shotcrete designs demonstrate a higher load-bearing capacity of up to 35% increase. Compared to conventional shotcrete, replacing sand with recycled glass aggregates further exhibited the need for less water and binder consumption owing to the glass water-reducing effect. This in return could leave more water available for improved workability in the mixture hence producing a more cost-effective and eco-friendly shotcrete product. From the results, no impairment of performance was recorded by substituting sand with crushed waste glass even at a high substitution percentage of up to 100%; suggesting high improvement potential of crushed waste glass re-use in the shotcrete industry.