Concrete Bond Durability of CFRP Sheets with Bioresins Derived from Renewable Resources

Abstract

AbstractBond strength durability of carbon fiber–reinforced polymer (CFRP) to concrete is investigated for two bio-based resins and compared with conventional epoxy (E). The first is an epoxidized pine oil blend (EP) and was used for wet layup installation. The second is a furfuryl alcohol resin derived from corn cobs and sugar cane (FA), and was used to prefabricate CFRP plates, which were installed using an epoxy paste. A total of 137 concrete prisms with a midspan half-depth saw cut were tested. Specimens were conditioned in a 3.5% saline solution at 23, 40, or 50°C for up to 240 days before testing for bond strength. Short-term bond strengths were 3.9, 4.3, and 5.5 MPa for the E, EP, and FA resins, respectively, using a 33 MPa concrete. Reductions in bond strength over the 240 days of conditioning did not exceed 15%. Bond failures of E-CFRP (EC) and EP-CFRP (EPC) were predominantly adhesive-based, where a thin layer of cement paste remained attached to CFRP, while that of FA-CFRP (FAC) was cohesive-ba...