An evaluation of rust conversion coatings in simulated reinforced concrete pore solutions

Abstract

The performance of reinforcing steel bars (rebars) coated with two different rust conversion coatings was analysed by means of electrochemical methods. Two exposure conditions were investigated, immersion in a pH 14 solution simulating pores in standard concrete, and immersion in a pH 9 solution simulating pore environments in carbonated concrete. The rebar corrosion potential (Ecorr), the corrosion rate (CR) and the electrochemical impedance (Z) were measured over 3 weeks. None of the products investigated helped to improve the resistance of steel against corrosion. Some parameters even indicated a detrimental action, particularly as the alkalinity of the solutions increased. Therefore, the application of this type of coating cannot be recommended during repair procedures of reinforced concrete structures due to the extremely alkaline environment provided by concrete.