Effect of corrosion-induced cracking on bond performance of thermo-mechanically treated rebars in concrete

Corrosion of steel reinforcement is a leading cause of deterioration in reinforced concrete (RC) structures, reducing their structural capacity and service life. The bond performance of thermo-mechanically treated rebars in concrete was investigated using pull-out specimens subjected to accelerated corrosion, aiming to identify reliable predictors of bond deterioration. A total of 100 specimens were tested, incorporating variations in concrete compressive strength (21–35 MPa), bar diameter (12–19 mm), concrete cover (20–94 mm), water/cement (w/c) ratio and corrosion level (0–18.5%). Corrosion-induced bond deterioration was found to be governed more strongly by crack width than by the degree of corrosion, with the crack width emerging as a consistent and sensitive indicator of residual bond strength across all specimens. Bond degradation rates ranged from 4% to 9% per 0.1 mm increase in crack width, while concrete strength, bar diameter, w/c ratio and concrete cover influenced the rate of degradation. A reduced concrete cover significantly increased the rate of bond strength loss. A new analytical method for estimating bond strength loss at a given crack width is proposed, which enables more accurate predictions of service-life performance and supports durability-based design of RC structures.