Durability of Natural Fiber-Reinforced Geopolymer and Alkali-Activated Composites: A Systematic Review of Degradation Mechanisms and Design Controlling Factors

Le résumé fourni par la source

Natural fiber-reinforced geopolymer and alkali-activated composites have emerged as promising alternatives for reducing the environmental impact of cement-based materials; however, their long-term durability remains insufficiently understood. This systematic review evaluates the durability behaviour of natural fiber-reinforced geopolymer and alkali-activated composites based on 42 studies published between 2017 and 2025, identified from 356 records retrieved from Scopus and Web of Science following the PRISMA methodology. The literature analysis reveals a significant increase in research activity in recent years, with 12 studies published in 2025 alone, indicating a growing transition from mechanical-performance evaluation toward durability-oriented design. The reviewed studies investigated multiple degradation environments, including moisture cycling, freeze–thaw exposure, chemical attack, carbonation, and thermal ageing. Across the evidence base, durability performance was mainly governed by the interaction among binder chemistry, pore structure, curing conditions, fiber characteristics, surface treatments, and exposure severity. Notably, the intrinsic surface properties of different natural fibers, including hydrophilic character, surface chemistry, and surface roughness, were found to strongly influence moisture absorption, fiber–matrix adhesion, and susceptibility to alkaline degradation, thereby contributing to distinct durability outcomes among fiber types. Fiber modification strategies and optimized matrix designs were frequently associated with improved interfacial stability and mechanical retention after ageing, whereas excessive fiber contents and poorly controlled moisture transport were recurrent factors contributing to degradation. Despite these advances, the review identified significant methodological limitations, particularly the lack of standardized durability protocols and long-term exposure assessments. Future research should prioritize harmonized testing approaches and integrated durability-based design frameworks to enable reliable prediction of service performance in natural fiber-reinforced alkali-activated composites.

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