Characterization of steel corrosion processes in various blended cements by means of coupled multi-electrode arrays

Supplementary cementitious materials can affect the porosity of concrete, pore solution pH and chloride binding, all of which influence the type and magnitude of corrosion damage. Advanced corrosion monitoring techniques are needed to follow the development of corrosion on steel embedded in concrete across space and over time. In this study, coupled multi-electrode arrays (CMEAs) were used to characterise corrosion processes in OPC and three blended cements. Cyclic wetting with chlorides was undertaken to initiate corrosion. The results showed three distinct types of corrosion: localised corrosion (CEM I), localised corrosion that expanded over time (CEM II), and a combination of localised and general corrosion (CEM III and CEM IV). Cathodic locations were also monitored successfully, and the corrosion behaviour was related to total porosity and pH of the pore solution. MicroCT was used to quantify the volume of corroded material, which agreed well with results calculated from the CMEA measurements.