Agro-industrial waste utilization in air-cured alkali-activated pavement composites: Properties, micro-structural insights and life cycle impacts

Abstract

This study investigates the development and performance of agro-industrial waste-based air-cured alkali-activated concrete composites (AC) for sustainable high-strength rigid pavement applications. The calculated amounts of liquid sodium silicate and sodium hydroxide flakes were used with an adequate quantity of water to prepare the alkali-activator solution. Agro-Industrial by-products, including ground granulated blast furnace slag (GGBS), construction and demolition (C&D) waste, and sugarcane bagasse ash (SBA), were utilized to develop AC mixes and the mechanical properties, micro-structural behaviour, and life cycle impacts were studied. Optimized AC mixes containing 50% recycled aggregates (RCA) (with 50% natural coarse aggregates) and 15% SBA (with 85% GGBS) demonstrated superior compressive, splitting-tensile, and flexural strength, while significantly reducing embodied energy and carbon emissions. Microstructural analysis through XRD, SEM, EDAX, and TGA confirmed the formation of stable alumino-silicate hydrate phases, contributing to enhanced mechanical strength performances. The life cycle analysis results indicated considerable environmental benefits compared to traditional Portland Cement based pavement concrete counterparts. This research presents a sustainable solution for pavement infrastructure, aligning with circular economy principles by promoting the reduction of resource consumption and greenhouse gas emissions.