Pitting morphology of prestressing strands subjected to naturally chloride environment

Corrosion of strands is worldwide considered one of the main risks to the safety of prestressed concrete structures, with pit depth often representing the most influencing parameter. In this work, seven-wire prestressing strands coming from naturally corroded beams of a thermal power plant exposed to 10 years of wetting and drying cycles with marine water, are analysed by using X-ray tomography. This allows for an in-depth investigation of the morphology of corrosion pits for each external wire and internal one, evaluating the maximum penetration depth and section loss for the most corroded areas, together with the evaluation of the pitting factor. The findings suggests that external wires are more prone to intense, localized corrosion, whereas the internal wire is characterized by a different morphology, showing milder, more uniform degradation. The data will aid in the calibration of existing models and the development of new methods for evaluating corrosion effects.