Effect of the chloride environmental exposure on the flexural performance of strengthened RC beams with self-anchored prestressed CFRP plates

Abstract

Carbon fibre-reinforced polymer (CFRP) plates are widely used to strengthen reinforced-concrete (RC) structures. At present, most studies focused on the short-term performance of strengthened RC beams with a prestressed CFRP plate, and very limited information is available on their durability, which is of importance in certain cases, such as high-piled wharfs and bridges in marine environments. This study investigates the effects of chloride environment exposure on the flexural performance of strengthened RC beams with self-anchored prestressed CFRP plates. In total, seven RC beams, four of which were strengthened by a self-anchored prestressed CFRP plate, were fabricated and tested under three-point bending. The testing parameters included 25% and 40% prestress level of the ultimate tensile strength of the CFRP plate, 5% and 10% tensile steel rebar corrosion ratio of mass loss and 10% and 20% anchor corrosion ratio in the chloride environment. The evolution of time-dependent prestress losses in the strengthened beam was determined, and the flexural behaviour of the strengthened beams was analysed. A theoretical model is proposed to predict the flexural strength of prestressed CFRP strengthened RC beams in a chloride environment. The experimental results indicated that the coupling of the corrosion expansion of the metal anchor and rebar in the chloride environment had a large negative effect on the flexural performance of the beams strengthened by the self-anchored prestressed CFRP plates. After exposure to the chloride ion solution, the failure mode of the RC beams strengthened by the prestressed CFRP changed from concrete crushing in the compression section to anchor pullout. The proposed model, which considered the effect of a chloride environment to predict the flexural strength of the strengthened beams, agreed well with the test results.