Effect of Cooling Method on Physical and Mechanical Properties of PVA Fiber-Reinforced High-Strength Concrete Exposed to High Temperature.

High-strength concrete (HSC) boasts excellent compressive strength and durability, making it a popular choice in various engineering applications. However, under the impact of high temperatures, HSC tends to crack easily, so it is combined with polyvinyl alcohol fiber (PVA fiber) to explore its engineering application prospect. This paper investigated the physical and mechanical characteristics of HSC reinforced with PVA fibers subjected to different heating temperatures and cooling techniques. The experimental results reveal a correlation between rising temperatures and observable changes in the specimens: a progressively lighter surface hue, an augmented frequency of cracking, and a considerable escalation in the mass loss rate, particularly after the temperature exceeds 400 °C. Regarding mechanical properties, the dynamic elastic modulus and compressive and flexural strength all decrease as the heating temperature increases. As the amount of PVA fiber rises while maintaining a steady temperature, these measurements initially show an increase followed by a decrease. The fiber contents yielding the best compressive and flexural strength are 0.2% and 0.3%, in that order. Considering the influence of cooling methods, water spray cooling has a greater impact on physical and mechanical properties than natural cooling. Furthermore, SEM was employed to scrutinize the microstructure of HSC, enhancing comprehension of the alterations in its physical and mechanical characteristics. The findings of this research offer significant information regarding the high-temperature behavior of HSC, serving as a valuable resource for guiding the design, building, and upkeep of structures that incorporate HSC. Additionally, this study will aid in advancing the progress and utilization of HSC technology.