Degradation behavior of multifunctional carbon fabric-reinforced cementitious matrix composites under anodic polarization

Abstract

A sustainable repair method that combines impressed current cathodic protection (ICCP) and structural strengthening (SS), called ICCP-SS, has been proposed for reinforced concrete structures suffering from steel corrosion. The key component in an ICCP-SS system is a multifunctional carbon fabric-reinforced cementitious matrix (MCFRCM) composite that simultaneously functions as a tensile reinforcement and an impressed current anode. The MCFRCM composite is investigated in terms of its electrochemical performance and interfacial performance and the degradation caused by anodic polarization in alkaline solution. The results show that a relatively stable electrochemical performance can be maintained for composites polarized at a current density up to 125 mA/m2, while an exponential increase in cell voltage can be seen at higher current densities. The charge density corresponding to the occurrence of the exponential increase in cell voltage is nearly the same for all composites polarized above 125 mA/m2. Besides, the composite shows a decreased maximum pullout force and a failure mode conversion from partial rupture to complete rupture of the carbon fabric with increasing current density. The composite is degraded by the dissolution of carbon filaments due to the anodic oxidation of hydroxyl ions from the pore solution in the matrix, which results in changes in the chemical composition and morphology of the filaments. The degradation of the composite can be further correlated with the electrochemical performance and interfacial performance.