The effect of sulfate ions on steel corrosion in carbonated concrete

Please check whether enrolling in this project is possible by directly contacting the responsible supervisor(s) indicated below as soon as possible. Note that although we announce many topics, we won't be able to offer all of them simultaneously due to limited lab capacity.

In reinforced concrete structures, carbonation-induced corrosion is a common issue that leads to degradation. This is particularly relevant for environmentally friendly blended cements, which are more susceptible to carbonation. Therefore, it is essential to better understand the corrosion process of steel in carbonated concrete.

The composition of the concrete pore solution plays a significant role in the corrosion kinetics of steel. The passive film formed on steel in alkaline concrete might be destabilized by the low pH 8-9 of carbonated concrete, while carbonate ions might lead to the formation of a new partially protective layer on the metal surface.

Besides, slag-blended cements have larger contents of sulfate ions than traditional Portland cements. The sulfate ions also interact with steel and add more complexity to the corrosion mechanisms in carbonated systems. It is the case of the precipitation of corrosion products – probably a complex of iron and sulfate species – on the metal surface.

This project aims to investigate the corrosion kinetics of steel in carbonated systems, particularly focusing on the role of sulfate ions. Electrochemical methods will be applied to determine the corrosion rates, impedances, and polarization curves. The corrosion products formed on the metal surface can also be characterized by microscopy analysis and Raman.

Students who take on this project will gain valuable theoretical and practical knowledge in electrochemistry and surface characterization techniques. If you are interested, please feel free to contact the project supervisors for an informal discussion.

Figure 1: Electrochemical study of the effect of sulfate ions on steel corrosion in carbonated pore solutions.

Figure 2: Corrosion products formed on the steel surface when immersed in carbonated pore solutions with sulfate ions.