In this study, the bond behavior of corroded reinforced concrete was investigated by conducting pull‐out tests on concrete specimens with variable induced crack widths and different splitting modes. To simulate cracks due to corrosion and focus on their effect on bond strength degradation, a novel method using expansion agent filled pipes is proposed. With the increase of the crack width over elapsed time from filling the aluminum pipe with an expansion agent, a target crack width was obtained. The results confirm that the type of splitting greatly influences the reduction in bond strength with deterioration of bond strength more severe in “Side‐split” than in “Single‐split.” Furthermore, using the surface crack width as a variable, empirical formulas to predict bond strength degradation due to corrosion of rebar are proposed. These prediction models give a good correlation when compared to the available literature.

Corrosion of the reinforcement affects more than the cross-sectional area of the rebar. The volume of steel also increases due to expansive corrosion products, leading to the cracking, delamination, and spalling of concrete. As a result, the bond capacity between concrete and rebar is affected. Researchers have extensively examined the impact of corrosion on the bond strength between concrete and rebar to propose empirical, theoretical, or numerical predictive models. Therefore, research programs on this topic have increased rapidly in recent years. This article presents a systematic literature review to explore experimental methods, outcomes, and trends on this topic. The Web of Science search collected 84 relevant research articles through a rigorous selection. Key factors that affect bond strength degradation, including concrete cover, concrete strength, and stirrups, have been documented. However, a general model is still unavailable due to discrepancies caused by differences in testing methods to evaluate the effect of corrosion on bond strength. Furthermore, researchers attempted to clarify the degradation mechanism of bond strength affected by corrosion. As a result, new alternatives have been proposed to build a practical model to assess the bond strength deterioration of corroded structures.

The corrosion of rebars in reinforced concrete structures cracks the concrete, which leads to the degradation of the bond strength between the rebar and concrete. Since bond deterioration can menace structural safety, bond strength evaluation is essential for proper maintenance. In this study, the authors investigated bond strength degradation by conducting pull-out tests on concrete specimens, with induced crack width and stirrups ratio being the principal parameters. An expansion agent-filled pipe (EAFP) simulates cracks due to the volumetric expansion of the corroded rebar. One advantage of this method is that it allows one to focus on the single effect of an induced crack. The pull-out tests on 36 specimens show that stirrups’ confinement significantly influences the bond degradation due to induced cracks. The authors proposed an empirical model for the degradation of bond strength, considering the impact of induced crack width. The result shows that the induced crack by EAFP can quantify the exclusive consequence of corrosion on bonds. Furthermore, the coefficient of variation is 12% for specimens without stirrup from Law et al. For specimen without and with stirrup from Lin et al., the coefficients of variation are 14% and 17%. The proposed model can predict the corroded specimen from the literature with reasonable accuracy.

No abstract