Influence of FRP confinement on bond behavior of corroded steel reinforcement

This study investigates the bond behavior of corroded reinforcing steel confined with carbon fiber reinforced polymer (CFRP). Corrosion of steel reinforcement in reinforced concrete structural elements could pose a significant problem that may result in loss of structural capacity and even failure. Very few studies have investigated the performance of the bond in corroded confined specimens. The conclusions from these studies suggest that the confinement prevents the reduction of bond strength even after considerable deterioration. Results reported in this paper provide quantitative information regarding the effectiveness of CFRP confinement. Bond tests were conducted on pull-out specimens with 10, 13, 19, and 25 mm [#3, #4, #6, and #8] diameter steel bars corroded to various levels and confined with CFRP. The primary independent variables investigated were: four bar sizes, various levels of corrosion and number of CFRP layers used for confinement. The results indicate that confinement can be effectively used to prevent the degradation of bond strength even at the highest levels of corrosion (12% mass loss) evaluated in this study. The loss of strength for unconfined specimens reached as high as 80%. As expected, confinement was more effective in bars with larger relative rib area. Confinement was also effective in maintaining the ductility.