Electrochemical characterization of early corrosion in prestressed concrete exposed to salt water

Abstract

Five large-scale concrete specimens reinforced with bonded seven-wire steel strands and representative of portions of bridge piles were exposed to salt water wet/dry cycles for 1 year, simulating tidal action. Corrosion of multi-wire steel strands was facilitated by minimizing the concrete cover. Half-cell potential and polarization resistance measurements were routinely performed to assess early corrosion. Supporting visual evidence of pitting and crevice corrosion was collected from strands removed from decommissioned specimens. It is shown that corrosion can be assessed based on polarization resistance thresholds. Tafel slopes were numerically estimated for passive and corroding strands from ±20 mV polarization curves, and used to gain a preliminary insight into the evolution of the Stern–Geary parameter and the associated corrosion intensity. These results suggest that the Stern–Geary parameter increases upon depassivation of the strands, different from deformed bars in reinforced concrete.