Anodic behaviour of carbon steel bars in realkalised concrete: potentiodynamic and potentiostatic tests in solution

Electrochemical realkalisation is a technique used for the repair of reinforced concrete structures suffering carbonation-induced corrosion. It aims at restoring high levels of pH through the application of a temporary cathodic current. Although this technique was introduced in the 1980s and has been used since then, there are still some aspects connected with its application that need investigation. In particular, it is not clear whether the usual techniques for measuring the corrosion activity of steel after the treatment can be considered reliable. This paper presents an experimental study on the anodic potentiodynamic and potentiostatic behaviour of steel in solutions simulating realkalised concrete and, for comparison, in solutions simulating alkaline and carbonated concrete. Results showed that in the alkaline solution used in the treatment steel bars are characterised by passivity, in spite of the high values of corrosion rate measured with linear polarisation technique.