This work investigates the mechanisms of propagation of corrosion of 7-wire, prestressed steel strands in concrete. The flower-like cross-section with interstitial spaces between the 7-wires makes the strand corrosion propagation complex and insidious. Results from a long-term study on chloride-induced corrosion of prestressed/pretensioned concrete specimens are presented. Corrosion profile and other studies on (1) strands in pretensioned concrete prisms exposed to chlorides and (2) broken strands from a 12-year-old grouted, post-tensioned bridge anchorage experiencing chloride-induced corrosion and stress-corrosion cracking at/near the corrosion pits are presented. This information reinforces the need to consider a short (rather negligible) corrosion propagation period for strands in prestressed concrete systems, especially when made with ordinary Portland cement and chloride-induced corrosion, which is a threat.
