08398 - Detection of Corrosion of Post-tensioned Strands in Grouted Assemblies

The feasibility and sensitivity of electrochemical noise (EN), electrochemical impedance spectroscopy (EIS), and linear polarization resistance (LPR) for detection of corrosion in post-tensioning (PT) components was investigated. The use of the electrical resistance (ER) technique, as well EIS and LPR, to detect air space corrosion at the grout voids was also explored. The results showed that high sensitivity noise measurements (in the μV range) are feasible for the strand-anchorage systems. The potential and galvanic current trends for the assemblies suggest the presence of activation-passivation cycles linked to each water ingress event. The EN method was adequate to identify only one modality of corrosion, and failed to detect other potentially important forms of corrosion despite the presence of significant macrocell current. In contrast, the EIS and LPR methods more reliably detected ongoing corrosion. The ER method could sensitively detect the deterioration of grouted and bare steel strands exposed to a high humidity environment as in the air space of a grout void. The air space corrosion experiments showed that an aggressive environment may evolve in the grout void, resulting in appreciable corrosion rates.