Bond behavior of steel reinforcement in high-performance fiber-reinforced cementitious composite flexural members

High-performance fiber-reinforced cementitious composites (HPFRCCs) exhibit a pseudo strain hardening behavior in tension, and increased damage tolerance when loaded in compression. The unique properties of HPFRCC materials make them a viable material for increasing structural performance under severe loading conditions. In this paper, the bond performance of mild steel reinforcement embedded in HPFRCC beams is presented. Beam specimens with lap splices were tested in four-point bending to examine the bond strength and bond-slip behavior of steel reinforcement embedded in HPFRCC materials. Specimens made with three different HPFRCC mixtures, as well as a traditional normal weight concrete were tested in four point bending. The parameters investigated were the amount of concrete cover and the presence of steel confinement in the lap splice region. Experimental results show that HPFRCC normalized bond strengths increased by 37 %, on average, when compared to concrete. Furthermore, the bond-slip behavior of reinforcement in HPFRCCs had a higher toughness than observed for concrete specimens. Test results are compared with existing bond-slip models for fiber reinforced concrete from beam tests and HPFRCCs from pullout experiments, and a recommendation to modify the ascending branch of an existing bond-slip model applicable to ductile HPFRCCs is proposed.