Review of factors affecting bond between ultra high performance concrete and steel fibers

Abstract

Novel materials such as ultrahigh-performance concrete (UHPC) have advanced over conventional concrete but suffer from brittleness owing to their high strength. The addition of steel fibers significantly overcomes this limitation by acting as a stress-transferring bridge between the matrix and the fibers, which enhances the durability and mechanical performance of the mix. This study compiles data from several previous research studies, offering a comprehensive understanding of the varying factors influencing the pullout behavior and bonding characteristics between the UHPC matrix and steel fibers. The findings of this study reveal that deformed steel fibers embedded at 30° and 45° exhibited significantly greater loading rate sensitivity on the pull-out energy under quasistatic and seismic loading rates when compared to straight steel fibers. Steel fibers with large aspect ratio (i.e., 125) exhibit 77%, 40%, and 10% higher strain capacity, energy absorption capacity, and post-cracking strength, respectively than fibers with a low aspect ratio (i.e., 62.5) under impact loading. The possible factors in the domain of fiber–matrix interactions of fiber-reinforced concrete are covered and discussed.