Durability Degradation Mechanisms and Coupled Deterioration Behaviors of Geopolymer Concrete Under Multi-Hazard Service Environments: A Critical Review.

Geopolymer concrete (GPC), here defined primarily as concrete based on low-calcium alkali-activated aluminosilicate binders, exhibits durability responses that depend strongly on precursor chemistry, gel assemblage, pore structure and exposure conditions; high-calcium or slag-rich systems are therefore discussed separately as related alkali-activated material (AAM) systems. This critical review synthesizes representative peer-reviewed evidence on freeze-thaw cycling, drying and autogenous shrinkage, elevated-temperature/fire exposure, chloride, sulfate and acid attack, carbonation, reinforcement corrosion and coupled multi-hazard deterioration. The evidence indicates that freeze-thaw damage is governed by pore-water phase change, cracking and transport-pathway formation, while chemical attack involves ion ingress, dealkalization, dealumination/decalcification and elemental leaching. Direct coupled evidence is strongest for freeze-thaw combined with chloride/salt or sulfate exposure; shrinkage-transport interactions are mainly correlation-supported, whereas carbonation-chloride-freeze-thaw-related corrosion remains largely a mechanism-based inference. Future work should prioritize standardized sequential multi-hazard protocols, chemistry-specific parameter databases and field-calibrated transport/corrosion models to support reliable service-life prediction and engineering design.