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 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. Owing to their varying size, RTSF is capable of arresting micro-cracks and lessening the chloride penetration in concrete. In this study, first, experiments were conducted to examine the mechanical performance of concrete containing RTSF-only and compare the results with engineered steel fiber (ESF) incorporating mix. Second, the effect of RTSF-only, ESF-only and their hybrid utilization on the corrosion development on embedded steel rebars is surveyed. Finally, the flexural performance of corroded fiber reinforced concrete (FRC) beam with different corrosion rates (0, 2, 5, 7, and 10%) were evaluated upon a three-point bending test setup. According to the results, higher compressive strength (about 37%) was obtained by RTSF inclusion in concrete mix, while the tensile and post-cracking strength attributed to blending RTSF and ESF showed more promising results. The residual strength of FRC mix at both service and ultimate load was improved by the hybrid utilization of both RTSF and ESF by 25-120%. Measuring the mass loss of corroded rebars embedded in different FRC mix, when RTSF incorporated in concrete mix compared to the ESF containing mix, there is a declining trend in corrosion rate. For uncorroded FRC samples, the RTSF incorporation improved the shear capacity of the plain RC beam by 25%. Corrosion of embedded rebars up to 8% slightly reduced the rotation capacity of FRC beams.