Scope a non-destructive inspection protocol for grouted post-tensioned tendons in an existing parking structure

Steps

1. Obtain the original PT shop drawings/tendon layout if available to plan access locations and understand tendon profile, anchorage locations, and grouting method used at construction.
2. Use impact-echo (IE) testing to screen for grout defects such as voids or soft grout along accessible tendon runs, since IE detects changes in the duct's acoustic resonant frequency caused by grout defects.
3. Where IE flags a suspect location, drill a small access opening into the tendon duct for borescope inspection to visually confirm void extent and tendon/wire condition with minimal physical disturbance to the tendon.
4. For moisture/corrosion-risk screening along tendon runs, consider a proprietary dry-gas injection moisture-content method (commercially available, e.g., a vendor-branded PT corrosion evaluation service) that measures moisture at distant vent ports to infer corrosion risk — confirm current vendor offerings and methodology directly with the provider rather than assuming a generic industry standard governs the technique.
5. Where defects are confirmed, extract grout samples for chloride content and pH/carbonation testing to determine whether the tendon environment is actively corrosive.
6. Have a structural engineer experienced in PT systems evaluate findings before any tendon is de-stressed, cut, or repaired, given the stored-energy hazard unique to post-tensioned members.