Vector Corrosion Blog
How is the Need for Post Tension Cable Repair Determined?June 14th, 2019
Bonded and unbounded post-tension structures present unique challenges for maintenance and repair. An understanding of the use and operation of post tension systems allows engineers and concrete professionals to effectively assess their current condition and recommend rehabilitation options.
Post-tensioned (PT) concrete deteriorates due to corrosion of post-tensioning strands. Corrosion can occur in grouted and ungrouted post-tension structures leaading to post-tension cable repair, in the presence of moisture and air in voids along the cable tendon.
Early identification and mitigation of corrosive conditions can significantly reduce the costs of major repairs and the risk of structural failure. Where previously, non-destructive tests and methods of corrosion protection were not available, Vector’s Post-Tech evaluation, drying, and grease injection systems of testing and protection can now be used.
Post-Tech® PT Corrosion Evaluation is a patented non-destructive test that identifies, and indirectly measures the extent of probable current or future corrosion deterioration in heat sealed or push-thorough cables exposed to a “wet” or potentially corrosive environment.
Post-Tech® PT Cable Drying is a corrosion mitigation process where the moist air from the PT cable is replaced by dry non-corrosive air. The process is monitored and the treatment is ended only when dry condition of the cable is confirmed. The PT cables that require this treatment are selected by the Post-Tech PT Corrosion Evaluation process.
Post-Tech® PT Grease Injection is a proven cost-effective process where special rust-inhibiting grease is injected under pressure into the PT cable sheath filling cable voids, cracks, and porous grouts along the PT cable. Post-Tech PT Grease Injection is performed right after the Post-Tech Cable Drying process to prevent or minimize further corrosion deterioration.
Post-Tech® Impregnation is designed to mitigate corrosion of grouted post-tension tendons, the process involves pushing an impregnation placed along the length of the tendon, leaving an anit-corrosion barrier film on the surface of the steel.
PT Repair and Replacement is the only option for PT cables that were identified as damaged during the post-tension evaluation process. The repair includes the replacement of entire deteriorated strands, the replacement and coupling of portions of strands, and anchorage repairs. Vector has the experience and capabilities to perform the repairs as well as provide the appropriate calculations for the tensioning of the strands.
Click here for more information about Post-Tensioned Concrete Corrosion Repair.