Monitoring corrosion rate for ordinary portland concrete (OPC) and high-performance concrete (HPC) specimens subjected to chloride attack

Abstract

This paper presents the results and the applicability of an electrochemical technique, the Tafel plot method, for determining the corrosion rate of reinforcing steel embedded in laboratory ordinary portland concrete (OPC) and high-performance concrete (HPC) specimens. Fifty-two OPC and 52 HPC concrete cylinders, each with a single embedded reinforcing steel rod, have been subjected to various laboratory conditions, and the corrosion rate of each specimen has been monitored. Results indicate that HPC specimens performed much better than OPC specimens in terms of resisting corrosion, as the corrosion rates were far lower for the HPC specimens than for the OPC specimens. Sodium chloride concentration played an important role in the propagation of corrosion: the higher the NaCl concentration, the higher the corrosion rate. In addition, different cycles of wetting and drying of concrete specimens had different impacts on corrosion rates. Results for the chloride concentration based on the American Society for Testing and Materials (ASTM) destructive testing method C1218 were in agreement with the corrosion rate results from the Tafel plot method used in the study.Key words: corrosion, electrochemical, reinforced concrete, Tafel method, high-performance concrete.