Analysis of microstructural properties and durability characteristics of geopolymer mortars with mining waste

The growing environmental concerns over resource depletion and carbon emissions from cement production have accelerated the search for sustainable alternatives to conventional concrete. In this context, geopolymers have emerged as promising binders, particularly through the utilization of aluminosilicate-rich industrial wastes to reduce environmental impact and support waste recycling. This study examines the mechanical and durability properties of geopolymer mortars produced by partially replacing ground granulated blast furnace slag (GGBFS) with mining waste (MW) at ratios of 0%, 10%, 20%, and 30%. The mixtures were activated using 10 M sodium hydroxide and sodium silicate under standard water curing conditions. Mechanical strength, ultrasonic pulse velocity (UPV), freeze–thaw resistance, and sulfate durability were evaluated. The optimum performance was obtained with 20% MW, which achieved a 30.4% increase in flexural strength and 18% in compressive strength at 7 days. This mixture also showed the lowest mass (10.69%) and strength loss (18.36%) after 50 freeze–thaw cycles. Scanning electron microscopy analysis confirmed enhanced gel formation and microstructural densification. The findings demonstrate that controlled use of MW not only improves durability but also promotes sustainable binder development in geopolymer technology.