Post Tension Repair for Concrete Structures

Post tensioned structures — bridges, parking garages, and buildings — are used by masses of people every day. Therefore, maintaining them and keeping them safe for ongoing, high traffic use, is essential.

Post tensioned structures need to be regularly evaluated, repaired and protected to ensure they maintain their integrity.  Due to their unique construction, these concrete structures deteriorate in a number of ways. And understanding their vulnerabilities and is essential to maintaining them.

They are susceptible to corrosion caused by the ingress of water, voids, and grouting problems, for example.  Special techniques are necessary for evaluating the unique types of corrosion (such as chloride induced pitting corrosion, hydrogen embrittlement, and stress corrosion cracking) in enclosed post tensioning systems.

These techniques include a visual inspection that identifies defects that could be symptoms of a larger problem. A skilled team of inspectors can see the signs — visual clues like spalling and delaminated concrete, tell-tale cracking patterns, efflorescence, excessive deflection, tendon eruption, and rust staining.

Earlier unbonded post tensioned structures were especially susceptible to corrosion. And not all evaluation techniques commonly used on conventionally reinforced concrete will work on these post-tensioned structures, where corrosive damage is hidden within the encapsulated system.  An innovative solution for post tensioned structure evaluation is a corrosion evaluation that quantifies moisture inside the system.

Once we identify the areas that need to be repaired, the Vector team uses advanced post-tensioning repair techniques such as shoring, tendon splicing, epoxy and urethane injection, repairing and sealing expanding joints, void grouting, and strand replacement, as well as routing and sealing cracks.  Bonded post-tensioning with voids and corrosion can be protected using innovative impregnation technology.  Unbonded post tensioned structures with missing grease and elevated moisture levels can be fixed with post tension cable drying and grease injection.

These solutions are both practical and long lasting, allowing these busy concrete structures to keep doing their jobs well into the future with a minimum of down time.