Revealing corrosion parameters of steel in alkali-activated materials

The long-term corrosion behaviour of reinforcing steel embedded in alkali-activated mortars (AAMs) prepared with three different binder compositions was monitored over a 360-day period by cyclic wetting/drying and spraying with chloride solution. Corrosion potential and polarisation resistance were determined by linear polarisation, individual resistance of mortar and steel by electrochemical impedance spectroscopy, and Tafel slopes by potentiodynamic anodic polarisation. The results were validated by correlating the electrochemical mass losses with the gravimetric mass losses. Based on the time evolution of the corrosion parameters, the study proposes new limits for passive and active corrosion conditions for reinforcing steel in AAMs.