Corrosion of unbounded tendons is common for post-tension structures exposed to aggressive environments. Insufficient cover over the tendons and lack of corrosion protection at anchorages combined with exposure to chlorides through deicing materials and coastal air lead to the corrosion of post-tension systems. Barrier cables used in parking garages are similar to post-tension cables in concrete slabs and are subject to similar deterioration mechanisms. In some cases the failures occur quicker since the cables are directly exposed to the elements and do not have the added protection provided by concrete cover. Replacing barrier cables and anchors requires the same expertise as repairing post-tension tendons.
Repairs to post-tension systems fall into two categories:
These repairs address system failures. Signs of structural post-tension system distress disclosed in the inspection can include the following and will require immediate repairs to restore strength and integrity to the structure:
Regular inspection of strand systems for signs of distress is one of the best ways for a building owner to prevent costly repairs. Items to be considered in the inspection of post-tension structures: