Engineering of alkali-activated permeable pavement composites with agro-industrial wastes

This study investigates the development of alkali-activated pervious concrete (PC) composites using industrial and agro-waste as primary constituents. The binder was activated with sodium silicate and sodium hydroxide at an activator modulus (Ms) of 1.25, maintaining a sodium oxide dosage of 4.0% relative to the total binder at a water-to-binder ratio of 0.40. Slag and bagasse ash were used as binders, recycled coarse aggregates (from construction and demolition waste) partially replaced crushed granite and waste-foundry sand served as fine aggregates. Mix proportions were optimised for hydraulic conductivity and compressive strength after 28 days of air curing. Four selected mixes were further evaluated for total porosity, splitting-tensile strength, static flexural strength and flexural fatigue performance. Optimal mechanical properties were observed for the corresponding PC mixes at 10% bagasse ash and 50% recycled aggregates. Statistical analyses of flexural fatigue, including S-N curves and two-parameter Weibull distribution, were conducted, along with Kolmogorov-Smirnov analysis and survival probabilities (95%, 50% and 5%). The findings contribute to understanding the engineering behaviour of alkali-activated PCs, supporting the development of permeable concrete pavement systems through effective utilisation of agro-industrial wastes, thereby promoting sustainability and environmental conservation.