Corrosion-resistance evaluation of coated and specialty bars

Abstract

The reduction in service-life of reinforced concrete structures caused by corrosion of reinforcing steel is a major problem to the construction industry. The use of specialty steels is one of the strategies suggested to minimize this deterioration phenomenon. In this study, the corrosion-resistance of epoxy-coated and selected specialty steel bars embedded in concrete and exposed to chloride environment was evaluated. The specialty bars considered included two types of epoxy-coated bars with varying degrees of damage, stainless steel bars, stainless clad bars, and a low-carbon chromium steel bar. The corrosion resistance of the investigated reinforcing bars was investigated by measuring corrosion potentials and corrosion current density over a period of about 32 months. As expected, the corrosion resistance of specialty bars was better than that of the black (normal) bars. The corrosion resistance of the epoxy-coated bars decreased with the degree of surface damage. Further, the corrosion-resistance of epoxy-coated bars with up to 1% damage was better than that of the other specialty bars. Additionally, the low corrosion rate noted in the epoxy-coated bars suggests longer service-life of structures built with these bars compared to structures incorporating specialty steel bars considered in the study. The relatively low initial cost of epoxy-coated bars, compared to other specialty steel bars, and their longer life results in a considerable cost saving. Also, the decreased corrosion damage of concrete results in technical (long service-life and safety), environmental (aesthetics) and economic (less overall cost of construction) benefits.