Strengthening and repair of non-uniformly corroded RC columns by ECC or CFRP jacketing: Bond performance evaluation

This study investigates the bond performance of non-uniformly corroded reinforced concrete (RC) repaired with either Engineered Cementitious Composites (ECC) or Carbon Fiber-Reinforced Polymer (CFRP) jacketing. While previous studies have explored repair methods for uniformly corroded or uncorroded members, limited research has examined the effects of non-uniform corrosion and post-repair secondary corrosion on bond behavior. To fill this gap, a novel auxiliary electrode-based accelerated corrosion method was used to induce non-uniform rebar corrosion in 78 specimens. The repair strategy involved applying ECC or CFRP jacketing after an initial corrosion stage, followed by a second-stage corrosion period to simulate continued deterioration after repair. This allows for a realistic evaluation of post-repair durability and bond performance. The influences of initial corrosion rate, ECC repair thickness (10 mm vs. 15 mm), CFRP confinement, and secondary corrosion duration were systematically evaluated through pull-out testing. The results show that ECC repair changed the failure mode from brittle splitting to ductile pull-out and improved bond strength by up to 44.04 %. CFRP jacketing achieved the highest bond strength increase of 70.35 %, although with a more brittle failure response. Notably, the bond strength in ECC-repaired specimens improved progressively with corrosion duration when using a 10 mm layer, while a 15 mm layer provided more stable performance. This study offers new insights into realistic corrosion scenarios and provides quantitative guidance for selecting and designing effective repair strategies for deteriorating reinforced concrete (RC) structures.