Effect of PVA fiber and basalt fiber on residual mechanical and permeability properties of ECC after elevated temperatures

At present, the incorporation of high-temperature resistant basalt fibers (BFs) as reinforcement in engineered cementitious composites (ECC) is not commonly practiced. This study investigated the high-temperature performance of ECC, with particular emphasis on the impact and contribution of polyvinyl alcohol (PVA) fibers and BFs. PVA-ECC and BF-ECC were subjected to testing at five target temperatures (23°C, 100°C, 200°C, 300°C, and 400°C) to evaluate their residual mechanical properties, permeability performance, and microstructural characteristics. The mechanical properties and permeability of both PVA-ECC and BF-ECC, such as strength, ductility, and resistance to chloride ion penetration, exhibited a gradual decline with rising temperature, except for the 100℃ condition. The PVA fibers displayed a relatively lower thermal resistance, with notable reductions in strength and ductility occurring primarily at 200℃. In contrast, BF-ECC exhibited a lower degree of deterioration throughout the high-temperature conditions. Microscopic analysis using mercury intrusion porosimetry and scanning electron microscopy techniques highlighted that matrix cracking, coarsening of pores, and diminished fiber-bridging capability are the main causes of high-temperature damage in ECC.