Efficacy of CFRP/BFRP laminates in flexurally strengthening of concrete beams with corroded reinforcement

This paper aimed at quantifying the effect of reinforcement corrosion level on the deformability and the flexural strengthening performance of Carbon and Basalt-Fibre-Reinforced Polymers (CFRP and BFRP) sheets on fifteen large-scale reinforced concrete (RC) beams. The main investigated parameters included reinforcement corrosion levels (0–30% by mass), FRP types and numbers of FRP layers (0–4 layers). The test results showed that the CFRP/BFRP laminates substantially reduced the crack width by up to 89%/85%. The flexural resistance of the corroded beams was, thus, improved by up to 103%/41%. By increasing the flexural resistance of corroded beams up to 41%, the BFRP laminates were a cost-effective strengthening option. Corrosion of the steel reinforcement resulted in the more effective mobilisation of the CFRP/BFRP laminates. This led to an increase in the strengthening effectiveness (improvement of beam flexural resistance) of the CFRP/BFRP laminates in the corroded beams by 14%/6% on average compared to the non-corroded beams. This increase tended to be more pronounced with a higher reinforcement corrosion level. In this paper, the authors propose an empirical formula to include the effect of reinforcement corrosion levels on FRP debonding strain. The proposed formula was verified showing an acceptable agreement with the experimental data from this study and other previous studies.