The effect of recycled-tire steel fiber and engineered steel fiber on rebar corrosion and shear behavior of corroded RC beam

The implementation of steel-fiber reinforced concrete (SFRC) can improve the durability of reinforced concrete structures exposed to corrosive environments. More recently, the recycled-tire steel fibers (RTSF) impressively boosted mechanical performance and post-cracking strength of plain concrete. Unlike the engineered steel fiber (ESF), RTSF is capable of arresting both micro- and macro-cracks. Micro-crack arresting via RTSF incorporation can reduce chloride penetration in SFRC. In this study, first, the influence of low dosage of RTSF and/or ESF on mechanical properties of concrete is explored. Second, the effect of RTSF, ESF and their hybrid utilization on the corrosion development on embedded steel rebars is surveyed. Artificial corrosion procedure was implemented for inducing corrosion in rebars embedded in reinforced concrete (RC) beam. Finally, the flexural performance of corroded SFRC beam with different corrosion rates (0%, 2%, 5%, 7%, and 10%) were evaluated upon a three-point bending test setup. According to the results, the compressive strength of plain concrete improved 37% by 40 kg/m3 RTSF incorporation. Moreover, the tensile and post-cracking strengths of concrete enhanced significantly by hybrid utilization of RTSF and ESF. The residual strength of SFRC mix at both service and ultimate load was improved by the hybrid utilization of both RTSF and ESF by 25-120%. For uncorroded RC beams containing SFRC mix, the RTSF incorporation improved the shear capacity of the plain RC beam by 25%. Among different types of fibers, RTSF was more effective in decreasing the actual corrosion rate of rebars embedded in RC beams. Additionally, corrosion of embedded rebars up to 8% slightly reduced the rotation capacity of FRC beams.