Low-carbon geopolymer concrete for sustainable pavement applications: Materials, performance, and sustainability

The increasing demand for low-carbon and resource-efficient infrastructure has accelerated interest in Geopolymer Concrete (GPC) as a sustainable alternative to Ordinary Portland Cement (OPC) concrete. Produced through the alkali activation of aluminosilicate precursors such as Fly Ash (FA), Ground Granulated Blast Furnace Slag (GGBS), Metakaolin (MK), and other industrial by-products, GPC has the potential to reduce CO₂ emissions while providing competitive engineering performance, although the magnitude of these benefits depends on material composition, activator system, curing conditions, and assessment boundaries. This review critically assesses recent advances in GPC for sustainable pavement applications, focusing on constituent materials, alkaline activator systems, engineering performance, durability, microstructural characteristics, and sustainability. Particular emphasis is placed on precursor composition, activator chemistry, Recycled Concrete Aggregates (RCA), and low-carbon activators. FA–GGBS blends have generally been reported to provide a favorable balance of workability, strength, durability, and sustainability under the conditions investigated. The incorporation of RCA and other waste-derived materials further improves resource efficiency and supports circular economy principles. Current challenges, including precursor variability, standardized mix design, and field implementation, are discussed, and future research directions are proposed to accelerate the adoption of GPC in sustainable pavement infrastructure.