Effects of graphene on slowing down deterioration of fabric reinforced cementitious matrix (FRCM) composites in impressed current cathodic protection (ICCP): Experiments and theoretical analysis

When the strengthening material - fabric-reinforced cementitious matrix (FRCM) composite is used as the anode in the impressed current cathodic protection (ICCP) for reinforced concrete structures, its long-term performance will be compromised due to anode acidification. Incorporating graphene into the matrix offers a means of mitigating interface deterioration by delaying the localized calcium leaching. This paper presents the results of a study to investigate the mitigation effects of graphene on the mechanical and electrochemical properties of FRCM composites. Direct tensile and pull-out tests were performed on graphene-enhanced FRCM (Gr-FRCM) composites subjected to different ICCP current densities and graphene dosages. The results reveal that graphene significantly reduces the deterioration in tensile and interfacial properties induced by long-term ICCP. The degradation factor for the ultimate tensile strain of FRCM composites under ICCP follows an exponential relation of total electrons, whereas the addition of graphene reduces this factor by more than half. Two constitutive models were developed to predict the key mechanical parameter, the effective strain of fibres, in the FRCM composite subjected to cathodic protection with and without graphene. These models were validated against beam test results and shown to be accurate for calculations of the flexural resistance of concrete beams strengthened using Gr-FRCM composites.