Investigation on the electrochemical and mechanical performance of CFRP and steel-fiber composite bar used for impressed current cathodic protection anode

Abstract

Impressed current cathodic protection (ICCP) has been proved to be an effective method to inhibite steel corrosion. Combined with ICCP technique, a new system has been proposed in this paper with carbon fiber reinforced polymer (CFRP) as dual-functional material: auxiliary anode and partial reinforcement simultaneously. The electrochemical and mechanical performances of CFRP in the new ICCP system were investigated experimentally with two kinds of reinforcement bar: CFRP bar and steel-fiber composite bar (SFCB). First, the accelerated anodic polarization test and electrochemical impedance spectroscopy (EIS) measurement were carried out for CFRP bar and SFCB to verify the electrochemical performances. Then, the mechanical performance and underlying degradation mechanism were identified for CFRP bar and SFCB based on the uniaxial tensile test and scanning electron microscopy (SEM). Finally, the service life of CFRP bar and SFCB has been evaluated to confirm the fesibility of the proposed system in practical engineering. Results showed that CFRP bar and SFCB possess excellent electrical conductivity and low electrical resistance as the anode in ICCP system. Compared with SFCB, CFRP bar is more promising as an anode material with a stronger polarization resistance capability, an acceptable degradation of the mechanical property and a longer service life. With a current density of 20 mA/m2, the service life was evaluated as 62 years for CFRP bar while 7 years for SFCB. To improve the application of SFCB in ICCP system effectively, some modifications are necessary, such as replacing the inner steel bar with stainless steel bar or adding a protective layer between the steel bar and fiber layer. Furthermore, the proposed system shows great potential for marine RC structures and the comprehensive study of this system will be carried out in future work.