Pullout Behavior of Straight Steel Fiber Reinforced UHPC Subjected to Single Cryogenic to Elevated Cycle

This paper aims to reveal the performance characteristics of steel fiber reinforced concrete under extreme temperature environments, and provide possibilities for concrete engineering applications under extreme temperature environments. In this study, herein, pullout characteristics of straight steel fiber embedded in unreinforced Ultra High-Performance Concrete (UHPC) within the temperature range of -170 degrees C similar to 200 degrees C were evaluated. The results showed that, in the single cryogenic-elevated cycle, the bond strength and pullout energy of UHPCs enhanced at -170 degrees C, and recovered to the same value as ambient temperature after the cryogenic-ambient freeze-thawcycle. The pullout performance of UHPCs decreased at 200 degrees C, and had an obvious improvement after a complete cryogenic-elevated cycle. Within the large-span temperature variation, the characteristics of the matrix and the thermal expansion between the matrix and the steel fibers are the reasons for the change in the bonding performance of UHPCs.