Multistage fire resilience mechanisms of cementitious composite incorporating resin-coated glass fibers under post-fire water quenching: Experiment and numerical simulation

Recent advances in sustainable cementitious materials highlighted the potential of functional micro-reinforcements in enhancing fire resistance. This study investigates the multistage fire resilience mechanism of cementitious composites incorporating resin-coated glass fibers, particularly under rapid water quenching. During early fire exposure, the resin coating forms a more tortuous heat conduction network, reducing thermal conductivity by up to 33.6% with 50% sand replacement. Finite element simulations indicate that the fragmented fiber network disrupts vertical thermal gradients and delays heat propagation. XCT revealed that introducing resin-coated glass fibers reduced total pore volume and led to fewer but larger pores, disrupting thermal conductive bridges and improving resistance to microcracking and spalling under rapid cooling. As temperature increases, resin decomposition leads to the release of gaseous products, which influence carbonate phase evolution in cementitious systems, as suggested by TGA-DTG and XRD analyses. Following prolonged high-temperature exposure and subsequent rapid water quenching, resin-coated glass fibers remained structurally stable within the matrix, which was associated with improved microstructural integrity and retention of residual reinforcing effectiveness. The maximum residual strength improvement of 17.2% was achieved at a 50% sand replacement level after exposure to 300 °C followed by water quenching. These combined thermal and structural effects highlight the potential of resin-coated glass fibers for enhancing the fire resilience of sustainable cementitious systems. © 2026 Published by Elsevier Ltd.