CORROSION PROPERTIES OF DIFFERENT FORMS OF CARBON STEEL IN SIMULATED CONCRETE PORE WATER

Carbon steel, such as concrete-reinforcing steel, tends to undergo corrosion processes when exposed to certain environmental actions. These are the carbonation of concrete and the ingress of chlorides into the concrete from the environment. Many times, the carbonation and chloride contamination are simultaneous processes leading to a harsh corrosion environment and subsequent corrosion problems. Monitoring the state of corrosion is thereby a very useful and powerful tool for following and evaluating the lifetime of reinforced concrete structures. Electrochemical measurements were performed to investigate different forms of carbon steel in simulated concrete pore water at different pH values with and without the presence of chlorides. Morphological characteristics of three different types of carbon steel were studied and SEM/EDX and Raman analyses of the corrosion products were performed. It was found that steel in the form of a sheet has a higher corrosion resistivity than a steel wire and a steel rod, and that the steel rod has a higher corrosion resistivity than the steel wire. The corrosion layer on carbon steel is very diverse; several morphologies were found and analyzed.