Effect of Kaolin Addition on Electrochemical Corrosion Resistance of Duplex 2205 Stainless Steel Embedded in Concrete Exposed in Marine Environment

As steel reinforced concrete is exposed to marine environments, chloride ions penetrate the concrete structures and lead to corrosion of the reinforced bars, which causes serious destruction of the bridge structures. In order to decrease the cost of repairs and the durability of reinforced bars, use of admixtures in concrete structures has attracted the attention of engineers and researchers around the world. In this work, the effect of Kaolin admixtures as partial replacement of ordinary Portland cement on the corrosion resistance of duplex 2205 stainless steel rebar were considered by open circuit potential, electrochemical impedance spectroscopy and polarization analysis after immersion to the marine environment. The electrochemical results indicated that the specimen with 8 kg/m3 Kaolin had higher corrosion resistance and potential than all the others. The surface morphologies of the samples revealed that corrosion products on the surface of DS steel rebar were reduced by addition of Kaolin. The results show that the Kaolin as additives enhance the durability of the concrete and prevent corrosive ions from reaching the surface of metal rebars, which may be an alternative material for development of the construction industry.