Impact resistance of ultra-high-performance fiber-reinforced concrete with different steel fibers

Abstract

In this study, the flexural behavior of ultra-high-performance fiber-reinforced concrete (UHPFRC) beams under drop weight impact loading was investigated. The experimental parameters included fiber aspect ratio and type. Two different aspect ratios of 65 and 100 for straight steel fibers, indicating S65 and S100, respectively, and one aspect ratio of 100 for twisted steel fiber, indicating T100, were considered. Test results indicated that the use of straight steel fibers with a higher aspect ratio (S100) and twisted steel fibers (T100) was effective in improving the flexural performance including flexural strength and energy absorption capacity under both quasi-static and impact loadings. The static flexural strength was insignificantly affected by the fiber type at an identical aspect ratio of 100, whereas the specimen T100 provided a higher deflection capacity with more micro-cracks than its counterpart (S100). On the other hand, the specimen S100 exhibited higher energy absorption capacity and better post-cracking response under impact loading, compared to that of T100. Therefore, the order of impact resistance was determined as S100 ˃ T100 ˃ S65.