While inspection is not a cure-all, it goes a long way in eliminating jobsite problems and assuring quality construction. The owner can frequently save money when post-tensioning is properly used. However, these potential savings may disappear if the structure is inadequately constructed. Completion delays and repair costs associated with improper construction sequence, tendon elongation discrepancies, and concrete distress are avoidable with proper quality control and inspection at the site.
Many times, rework of post-tensioning material is the source of tensioning problems. Installation of post-tensioning material is not necessarily difficult, but repair after a concrete pour usually is. The first line of quality control is the contractor's own quality assurance program. In addition to the contractor's review, the local municipality may require a final inspection of the embedded steel before any concrete pour. If it does not, the owner who appraises the risks associated with lack of inspection may want to retain a qualified inspection service. The obvious question becomes: Who is qualified to review post-tensioning installation?
To insure a quality review, the following should be required of the inspection team: Understanding of the most common post-tensioning systems and components; knowledge of the post-tensioning design process and basic principles; experience in major phases of field installation and plant fabrication; and experience inspecting conventionally reinforced concrete structures. The three phases that are involved for inspection of all post-tensioning systems are material manufacturing, tendon installation, and tendon stressing.