Tensile behavior of crack-repaired ultra-high-performance fiber-reinforced concrete under corrosive environment

This study aims to evaluate the influence of crack repair using epoxy sealing on the tensile response of ultra-high-performance fiber-reinforced concrete (UHPFRC) under corrosive environments. Three different crack widths, i.e., 0.1, 0.3, and 0.5 mm, and two different corrosion durations, i.e., 4 and 10 weeks, were considered. The test results indicated a minor change in the tensile performance of UHPFRC with the smallest crack width of 0.1 mm under corrosive environments for up to 10 weeks. This is due to the restriction of ferric oxide formation at the densified fiber–matrix interface. A wider crack width accelerated the steel fiber corrosion and noticeably influenced the post-cracking tensile behavior. Considering the corrosion duration of 4 weeks, the tensile strength of cracked UHPFRC with a width of 0.3 mm or greater increased by approximately 12–17% owing to the moderate steel fiber corrosion. However, the tensile strength decreased during the longer corrosion duration of 10 weeks by ruptures of excessively corroded steel fibers. Crack repair using epoxy sealing increased the tensile strength of cracked UHPFRC by approximately 10% and effectively prevented further corrosion of steel fibers at the crack location, leading to higher tensile strength even after 10 weeks of corrosion.