Zinc-Rich Paint As Anode for Cathodic Protection of Steel in Concrete

This paper describes the findings of the experimental works undertaken to investigate the performance of zinc-rich paint (ZRP) to provide cathodic protection to chloride-contaminated RC structures. The program of experimental works was designed and conducted to assess four principal properties, viz (1) conductivity, (2) adhesion with concrete (short term and long term), (3) durability, and (4) electrochemical polarization. These properties considered together define the ability and effectiveness of the materials to act as an anode for impressed current cathodic protection. The research findings indicated that a specific proprietary ZRP product showed that optimum conductance was obtained with three coats producing a 280–320 μm thickness, with good adhesion to the concrete substrate, in which values obtained ranged between 1.65 and 3.5 MPa with and without applied current. It was capable of withstanding/supporting high levels of current, i.e., more than $300\mathrm{mA}/{\mathrm{m}}^2$, and the service life of the ZRP coating was estimated to be well in excess of 20 years at an applied current density of $10\mathrm{mA}/{\mathrm{m}}^2$.