Cathodic Protection for Steel Beams Strengthened with CFRP Sheets

Abstract

This paper presents the potential of cathodic protection for steel beams strengthened with carbon fiber reinforced polymer (CFRP) sheets. A conceptual experimental program is conducted with 19 strengthened beams. Sacrificial anodes are employed to mitigate the initiation and progression of corrosion, which lead to three test categories: unprotected, protected with zinc coins, and protected with zinc spray. A comparative assessment is reported on the behavior of the beams subjected to an accelerated corrosion protocol with an NaCl-based electrolyte solution for up to 144 h, including an unconditioned control beam. Material testing indicates that the strength of the epoxy adhesive bonding the CFRP to steel substrates is preserved, whereas the fiber-resin interface of the CFRP is deteriorated by the electrolyte. The cathodic protection improves the flexural behavior of the conditioned beams in terms of load-carrying capacity, yield characteristics, and ductility. Protection limits beyond which the efficacy of the zinc anodes diminishes are noticed. According to reliability investigations, the safety index of the strengthened beams is reduced due to corrosion damage (the accelerated corrosion degrades the CFRP-steel interface); however, the presence of cathodic protection retards the degree of reduction. A fuzzy-logic model is developed to address the intrinsic uncertainty of corrosion and is used to propose design recommendations for CFRP-strengthened steel beams with cathodic protection.