Thermal‐regime‐dependent uniaxial tensile behavior of engineered geopolymer composites reinforced with multiscale fibers

Abstract This study investigates the uniaxial tensile behavior, microstructural evolution, and thermal resistance of engineered geopolymer composites reinforced with multiscale fibers (PVA, steel, and MWCNTs) under elevated temperatures. Mass loss increased progressively with temperature, reaching 15.2% at 800°C, primarily due to dehydration and decomposition of calcium‐bearing phases. Tensile strength improved slightly at 200°C due to matrix densification, but decreased significantly at ≥400°C due to PVA fiber melting and pore formation. Microstructural analysis revealed strong fiber–matrix bonding at 200°C and a transition to brittle failure at higher temperatures. The interconnected pore network formed at elevated temperatures helped prevent explosive spalling. These findings provide insights into the temperature‐dependent roles of multiscale fibers in EGC tensile performance.