DefinePK

Abstract

Essential additives, such as fibers, are widely used to improve the mechanical properties and performance of concrete. Fibers can be added to concrete in a mono or hybrid form of both metallic and non-metallic type. Although benefits of hybrid fibers addition to concrete are established in the literature, the bond stress slip response of embedded reinforcing steel in hybrid fiber reinforced concrete is not thoroughly studied. In this study, the bond stress-slip behavior of reinforcing steel bars embedded in concrete containing hooked end steel fibers and polypropylene fibers is assessed by carrying out pull-out tests. The variables considered in this study include polypropylene fiber volume (i.e. 0.1% and 0.2%), hooked end steel fiber volume (i.e. 0.5% and 1%), and the diameter of embedded reinforcement bars (i.e. 10 mm and 12 mm). The experimental results indicate that adding hybrid fibers of 0.1% polypropylene and 1% hooked end steel fibers yield the highest bond strength and hence the highest reduction in the embedded (development) length. The addition of hybrid fibers to concrete also improved the toughness of concrete and increased the slip measurements prior to failure of the bond between rebar and concrete.