Performance Evolution of CFRP Strip Anodes in Concrete: An Integrated Electrochemical and Mechanical Study.

Abstract

Impressed current cathodic protection (ICCP) is one of the most effective techniques in preventing steel corrosion in concrete structures. Based on the exceptional electrical conductivity and mechanical properties of carbon fiber reinforced polymers (CFRP), a novel structural system employing ICCP is proposed in this paper, in which CFRP strips are used as both concrete stirrups and as an auxiliary anode for cathodic protection. To further verify the dual functions of CFRP strips for this new system, the electrochemical and mechanical behaviors of the CFRP strip anode are investigated experimentally in this study through the anodic polarization test, electrochemical impedance spectroscopy test, uniaxial tensile test, and interfacial acidification test. The effects of concrete type and anode current density on the properties of CFRP strip anodes are identified. The results show that the CFRP strip anode possesses satisfactory electrical conductivity and relatively low output resistance, and the ultimate strength of the CFRP strip after polarization is reduced as the current density increases due to the gradual degradation of the CFRP anode. The mechanical properties of CFRP strips in Engineered Cementitious Cement (ECC) concrete and geopolymer concrete outperform those of ordinary concrete, and the degradation rate of CFRP strips subjected to anodic polarization in ECC concrete is lower than that of geopolymer concrete. The cathodic protection mechanism of CFRP strips as an anode is further revealed via numerical analysis. In addition, the prediction model of the service life is constructed for the proposed novel concrete structural system. The predicted service life of the system decreases as the reinforcement ratio increases, and it increases as the stirrup ratio increases. The predicted service life of the ICCP system in ECC concrete is significantly longer than that in geopolymer concrete and ordinary concrete.