Enhanced Performance Zinc Coating for Steel in Concrete

TRB's National Cooperative Highway Research Program (NCHRP) Innovations Deserving Exploratory Analysis (IDEA) Project 174: Enhanced Performance Zinc Coating for Steel in Concrete evaluates the performance of a reinforcing bar with a thermal zinc diffusion (TZD) coating to resist corrosion. The long-term performance of bridges and other department of transportation (DOT) structures exposed to deicing or marine salts requires improving the corrosion resistance of embedded steel as well as the performance of the concrete. Several stainless steel alloys are believed to have good performance, but the material costs are several times that of conventional black steel. In addition, though only the outer surface of the steel needs protection, the entire bar is made of alloys using premium raw materials. The product that was the focus of investigation is a reinforcing bar with a thermal zinc diffusion (TZD) coating, with and without a supplemental organic coating.