Why are post-tensioned tendons at risk for corrosion?
The basic problem with all parking structures is deterioration due to corrosion accelerated by heavy use of road salts. Unlike rebar where corrosion starts at the bars near the top surface, post-tensioned tendons can start corroding at any point along the drape of the tendon. Since, in all but the newer garages, the tendon sheathing is not watertight, water seeping through the concrete will pick up chloride ions readily available in the concrete and enter the tendon wrapping. This water can settle at the low point of the tendon profile and corrode the tendon.
