Enhancing high-strength geopolymer concrete with recycled granite aggregate using sugarcane bagasse ash and steel fibers

This study investigates the effects of sugarcane bagasse ash (SCBA) and steel fibers on enhancing the mechanical properties and durability of high-strength geopolymer concrete (HSGC) made with recycled granite aggregate. Recycled granite waste from stone quarries was used to completely replace natural fine aggregates, aiming to reduce reliance on natural sand. To further improve the concrete performance, SCBA from biomass power plants was incorporated at dosages of 0–5 % by weight of fly ash, while steel fibers were added at 0–1 % by concrete volume. The results showed that 1 % SCBA optimally improved the microstructure of HSGC, promoting a more homogeneous geopolymer matrix and significantly enhancing both mechanical and durability properties. The combination of 1 % SCBA and 1 % steel fibers resulted in a 28 % increase in compressive strength and a 25 % increase in elastic modulus compared to plain geopolymer concrete. Flexural toughness also improved by 90 %. In terms of durability, adding 1 % SCBA mitigated the micro-porosity commonly induced by steel fibers, resulting in a 10 % improvement in chloride resistance due to matrix densification. Notably, the mixture containing 1 % SCBA and 0.5 % steel fibers demonstrated the most balanced performance in terms of mechanical strength, environmental impact, and cost-effectiveness, suggesting it as a suitable option for practical applications.