Electrochemical behavior of steel-reinforced concrete during accelerated corrosion testing

Corrosion of reinforcing steel presents a major durability issue worldwide and is the focus of much research activity. The long time periods involved in replicating reinforcement corrosion within laboratories has resulted in a number of accelerated test methods being developed. The basis of the research presented in this paper was to examine the impressed current technique often used to induce reinforcement corrosion. The suitability of the technique to model chloride-induced corrosion was investigated by examining the electrochemical nature of the test method. Corrosion was induced in prisms of differing characteristic strengths and cover thicknesses by applying a current between 3 days and 17 days. The acoustic emission (AE) technique detected the onset of corrosion. The gravimetrical and theoretical mass losses are compared and a modified expression based on Faraday's law relating the electrical current to the mass loss is also proposed. which accounts for the localized nature of chloride-induced corrosion. This improved method is dependent upon a reliable method of detecting the onset of corrosion. which can be achieved by AE. On balance, the impressed current technique appears suitable to simulate reinforcement corrosion.