Durability of Geopolymer Concrete Under Chemical Attack: A Review of Acid, Sulfate, Chloride, and Multi-Exposure Resistance

Abstract

The durability of concrete in chemically aggressive environments remains a major concern for marine structures, wastewater systems, industrial facilities, pavements, and foundations exposed to sulfate-bearing soils. Geopolymer concrete has attracted increasing attention as a lower-carbon alternative to ordinary Portland cement concrete because its aluminosilicate-rich reaction products, reduced portlandite content, and adjustable precursor–activator chemistry may enhance resistance to various chemical attack mechanisms. However, its durability is strongly governed by mixture composition and exposure regime, and therefore cannot be generalized across all geopolymer systems. This review provides a systematic and critical synthesis of the chemical attack resistance of geopolymer concrete, focusing on acid, sulfate, chloride, marine, wastewater, and combined aggressive exposures. The effects of precursor chemistry, calcium content, activator composition, curing regime, additives, fibers, aggregate type, recycled materials, and environmental coupling are examined in relation to degradation mechanisms and durability indicators. A PRISMA-informed methodology was used to identify, screen, verify, and synthesize primary experimental and modeling studies. The reviewed evidence indicates that low-calcium and well-polymerized geopolymer systems often exhibit favorable sulfate resistance due to the reduced availability of calcium-bearing phases that form expansive products, whereas chloride resistance is primarily governed by pore refinement, chloride transport, binding capacity, pore–solution alkalinity, and reinforcement corrosion behavior. In contrast, acid resistance remains more variable, depending on acid type, pH, exposure duration, solution renewal, calcium content, and the stability of protective silica-rich layers. Additives and alternative aggregates can enhance durability by refining the pore structure, improving the interfacial transition zone, or controlling cracking, but excessive or incompatible dosages may have adverse effects. Overall, geopolymer concrete offers strong potential for chemically aggressive infrastructure when designed through performance-based criteria and validated under realistic multi-exposure conditions.