Post-Tech® Corrosion Evaluation
Post-Tech® Corrosion Evaluation
As part of an overall condition assessment of post-tensioned structures, a Post-Tech® Corrosion Evaluation can determine the cause and extent of corrosion risk and assist owners and engineers in preparating an effective and economical corrosion mitigation strategy.
Post-Tech® Corrosion Evaluation is a non-destructive test method that determines the degree of wetness inside a post-tensioned cable sheath by injecting a dry gas and measuring the moisture content in the exhaust from the venting ports. This test can be conducted on a subset of cables as pilot sample before commissioning a complete full-scale evaluation of all cables.
Post-Tech® Cable Break Detection utilizes a magnetic field to detect cable breaks and defects in post-tensioned and prestressed concrete structures. After the cables are magnetized, breaks are detected with sensors and state-of-art software.
-crop_custom_3600x3600_at_0.0-0.0-scale_1000x1000.jpg)
Evaluation Process
- A central test pit, located on the underside of the slab is often used in Full-Scale testing. This serves well for visual inspection and future corrosion mitigation.
- Two small holes (approx. 5/8in (16 mm) diameter) are drilled into the structure to access the post-tensioned strand's sheath near the end anchorages.
- Air ports are inserted and secured.
- Dry gas is injected at low pressure through the cable sheath.
- Measurements of the relative humidity and temperature of the air escaping from each of the “out” ports are taken using a calibrated Relative Humidity & Temperature (RH & T) sensor.
- The degree of wetness of each strand is assessed by grading the moisture content of the escaping air using the Post-Tech three-point system.
Research has demonstrated excellent correlation between the Post-Tech® Corrosion Evaluation grade and the observed corrosion on cables removed for inspection. If a site-specific correlation is required, a small percentage of tendons which are representative of the different construction pours and moisture levels within the structure, can be removed and inspected.
Results
The Post-Tech® Corrosion Evaluation results are depicted both graphically and on color-coded drawings. Each section of cable tested is color-coded to indicate the probable corrosion condition. This system permits ready evaluation of the test results for individual cables, for select areas of the structure, and for the structure as a whole. Permanent identification of all cables in a structure facilitates future inspection, repair, and preventative maintenance.
Once the Post-Tech® Corrosion Evaluation has determined the potential for corrosion, a mitigation plan can be put into place using the Post-Tech PT Cable Drying system and PT Grease Injection to extend the service life and integrity of post-tensioned structures at a fraction of the cost of other repair methods.
The Post-Tech® range of corrosion solutions is used as part of an overall strategy for the evaluation, identification, and protection of post-tensioned concrete structures. Structural assessments should be conducted by a qualified structural engineer.
Applications
- Unbonded post-tensioned slabs or beams in parking structures
- Unbonded post-tensioned building slabs
Technical Documents
Select a document to download product information. For CAD drawings in DWG format please Contact Us.
Technical Data Sheet
Market Segments
This product has been used to solve corrosion problems across these markets.