Factors affecting the bond behavior of corroded rebars embedded in ultra-high-performance concrete

Corrosion effects on bond behavior are important due to the changes they cause in the nonlinear performance of structures. An experimental program was carried out to compare the effect of concrete, rebars, bond length, and rebar diameter as the effective parameters on the bond behavior of corroded rebars in concrete. Results showed that low corrosion improved bond strength for ultra-high-performance concrete (UHPC) with higher rate than the normal strength concrete (NSC). As the corrosion level increased, the bond strength was reduced at a higher rate for UHPC than NSC. The reduced confinement due to corrosion-induced cracking had a higher effect on damaging the bond behavior than the reduction of rebar cross-section surface and tread height, the adverse effect of which was more severe for UHPC. The reduced mass of rebar per unit length embedded into concrete is a more appropriate criterion to measure and present the corrosion level. Finally, some equations were proposed for predicting the maximum bond strength accounting the corrosion effect.