Rehabilitation of concentric reinforced concrete columns pre-damaged by corrosion using advanced composites

Reinforced concrete (RC) columns in aggressive environments are prone to corrosion-induced deterioration, leading to substantial loss in load-carrying capacity. Seven circular RC columns with up to 27 % and 45 % corrosion in the longitudinal and transverse steel, respectively, were tested in this study to evaluate the effectiveness of carbon fiber-reinforced polymer (C-FRP) and carbon fabric-reinforced cementitious matrix (C-FRCM) in repairing such corroded RC columns. The results demonstrated that corrosion of reinforcement reduced the column's axial strength by up to 40 %, but both repair systems restored the original capacity. The C-FRP repair technique provided superior strength enhancement (118 %–131 % increase) compared to that of C-FRCM (51 %–71 % increase) due to better confinement effectiveness. However, the columns repaired with C-FRCM exhibited a more gradual post-peak degradation, contributing to improved ductility. A new analytical model was proposed and validated against test results to predict the axial strength of the columns before and after repair. The model accounts for corrosion effects and the interaction between the internal steel tie confinement and external composite wrapping, providing a comprehensive and realistic assessment of the column's strength. The findings support the use of advanced composites in the practical rehabilitation of corrosion-damaged RC columns.