Effect of fiber reinforcement, mineral admixtures, and air entrainment on the fire performance of concrete in bridges: A review

High-performance concrete (HPC) and ultra-high-performance concrete (UHPC) are increasingly being employed in bridge repairs and accelerated bridge construction due to their desirable properties and numerous benefits over conventional concrete. Despite their immense advantages, high-performance concretes are vulnerable to bridge fire hazards and subsequent fire-induced deteriorations that are caused by physical and chemical phenomena that are instigated by fire exposure. This paper aims to understand and summarize the mechanisms and phenomena that are experienced by HPC and UHPC when they are exposed to elevated temperatures during bridge fire accidents. The contemporary literature on the fire performance of concrete is critically reviewed with the aim of understanding and quantifying the impacts of different types of mineral admixtures, fiber addition, and air entrainment on the fire behavior of concrete. The effects of these inclusions (mineral admixtures, fibers, and air entrainment) on the fire performance of concrete are summarized in terms of temperature-induced spalling behavior, residual compressive strength trends, residual tensile strength trends, and cracking and impermeability loss. The critical findings from the contemporary literature and future research needs are discussed towards the end, and these findings can help in formulating UHPC with improved fire performance and can also help in post-fire forensic investigations.