Anodes are critical component of cathodic protection systems. As part of this effort, three different anodes were tested in a cathodic protection system that was designed and constructed to prevent further corrosion of reinforced concrete. This anodic system includes an electrically conductive coating composition applied in fluid form over an outer surface of the concrete mix. The composition further includes a predetermined amount of electrically conductive carbon material (coke, carbon black, graphite) uniformly distributed in the epoxy resin (as a binder) whereby the coating composition has a predetermined value of resistively. This investigation attempts to find the best type and optimum content of conductive carbon filler in poxy coating, to ensure optimal anode working parameters for marine environments (basically marine and sewer environments) and if any of the coating systems tested in this study excel over the other. In this study, electric and electrochemical parameters of three layer (with average coating thickness of 300µm) coke-epoxy, carbon black-epoxy and graphite-epoxy conducting paints (with different amount of filler) have been determined during long-term anodic polarization (70 days) in a seawater solution. During this test, on the basis of impedance measurements, the electrical resistances of these coatings have been calculated every 14 days. if conductive paints exhibit good electric and electrochemical stability, they will be attractive for cathodic protection of reinforced concrete.

Keywords: Conductive coating, Epoxy, Reinforced concrete, impedance, Anodic polarization