A state-of-the-art review on frost resistance of fiber-reinforced geopolymer composites

Geopolymer represents a novel, environmentally sustainable cementing material. The adoption of geopolymers as a substitute for ordinal Portland cement facilitates the recycling of industrial solid waste. The high brittleness of geopolymers poses a significant limitation to their applications. Incorporating fibers is a common method for enhancing toughness and improving crack resistance of geopolymers. Research on fiber-reinforced geopolymer composites (FRGC) has achieved notable advancements in frost resistance. However, comprehensive summaries on the frost resistance of FRGC remain limited. In this work, the specific effects of steel fiber, polymer fiber, hybrid fiber and other fiber on mass loss, compressive strength loss, flexural strength loss, ultrasonic pulse velocity, and relative dynamic elastic modulus of geopolymers after freezing-thawing (F-T) cycles are briefly reviewed. The effect of fiber content, fiber type, and fiber size on frost resistance index was compared. Different fibers have different effects on geopolymers frost resistance indexes under different F-T cycles. Within a specific fiber content range, fibers positively influence the frost resistance of geopolymers. The uniform distribution of fibers is the key to improving the frost resistance of FRGC. The formation and growth of cracks are influenced by the bridging effect of fibers, which limits the penetration of free water and enhances frost resistance. Furthermore, this study utilizes VOSviewer software for visual analysis of the literature, identifying key factors influencing frost resistance and revealing trends and hotspots in the research field. The mechanism of FRGC subjected to F-T cycles was discussed and potential directions for future research on its frost resistance were outlined.