Abstract
Cyclic potentiodynamic polarization (CPP) techniques were used to evaluate the influence of crevices present in stranded prestressing steels on the resistance to chloride-induced corrosion. Prestressing wire and strand specimens were exposed to simulated concrete pore solutions with chlorides added as sodium chloride (NaCl) up to 1.0 M. Stranding resulted in a 67% reduction in measured Cl−-induced corrosion resistance when compared with CPP experiments conducted on single prestressing wires. Forensic investigation of tested specimens showed that imperfections in as-received zinc phosphate (ZnPO4) surface coatings also played a role in corrosion initiation. Based on these data, a model has been developed to describe the influence of crevice corrosion mechanisms and surface imperfections on corrosion initiation in prestressing strand. When these reductions in corrosion resistance were applied to service life estimates of model concrete systems, reductions in time-to-corrosion were 28 to 36%.
