Effect of rebar coating on corrosion resistance and bond strength of reinforced concrete

The objective of this study is to assess the corrosion resistance of zinc-coated and coating effect on the bond strength between concrete and reinforcing steel. Potentiodynamic polarization method was utilized to determine the corrosion rates of carbon steel and zinc in both pH 12 solution and 3.5 wt% NaCl solution. In addition, cylindrical specimens were cast and exposed to 3.5% NaCl solution and a direct current density (0.5 mA/cm²) was applied to accelerate the corrosion process. Open circuit potential (OCP), direct current polarization resistance were obtained to evaluate the rebar corrosion.Potentiodynamic polarization curves show that the corrosion rate of zinc is higher than carbon steel in pH 12 solution but lower in 3.5% NaCl solution. The bond strength of uncoated rebar is 5–10% less than zinc-coated rebar before aqueous immersion test. The bond strength decreases with an increase in corrosion rate for uncoated rebar and zinc-coated rebar. After 14-days accelerating corrosion process, the reduction ratio of bond strength for zinc-coated rebar is less than uncoated rebar.