The Combined Effect of Chloride and Temperature on Corrosion Rates for Carbon Steel Reinforcement within Natural Aerated Synthetic Concrete Pore Solution

Abstract

Corrosion of the reinforcing steel is the most significant cause of the short-term deterioration of reinforced concrete. However, good steel with good concrete has been protected against corrosion by a passive film formed by the iron reacting with the alkaline pore solution within the concrete. Aggressive substances from the surrounding environment may attack this protective film. This research aims to investigate the combined effect of temperature and chloride ions on the corrosion resistance of carbon steel rebar in a synthetic concrete pore (SCP) solution. For this investigation, carbon steel of grade 60 (with minimum yield strength of 420MPa) was selected as specified by ASTM A615-16. In this study, Tafel polarization plots were utilized and conducted at two temperatures of (24 and 45°C). in addition, the (SCP) solution was contaminated with sodium chloride with additions of (0.5, 1.0, 1.5, and 2.0% wt.) as mass fractions. The results showed that at both temperatures, the corrosion rates increased gradually with chloride addition (up to about 1% NaCl) and then decreased because the pH value, electrical conductivity, and dissolved oxygen greatly affected this behavior. However, the corrosion rates at 45°C are increased to about ten times than 24°C because the protective layer is less stable and more iron dissolution occurs.