Report on Corrosion and Repair of Grouted Multistrand and Bar Tendon Systems

Description

This report is intended to provide general information on the corrosion and repair of grouted multistrand and bartend on systems. The information is intended to represent the state of knowledge of the committee in the areas of corrosion prevention in grouted tendons, as well as evaluation and repair. It is not intended as a standard or recommended practice. A strong background in durability of grouted post-tensioning systems, including practical experience and training, is recommended before designing, constructing, evaluating, or repairing these structures. This report focuses on the unique materials and hardware associated with grouted post-tensioning tendons. General corrosion theory for metals in structural concrete systems isnot within the scope of this report. Information on corrosion theory and mechanisms can be found in ACI 222R-01 and ACI 222.2R-01.

The use of grouted high-strength wire, strand, and bar post-tensioning tendons as a viable construction technique began inNorth America in the 1950s. Components of the standardsystem have changed significantly over the last half-centuryfrom shimmed button-head wire-type systems to bundles ofseven-wire strand systems with wedges (Post-TensioningInstitute 2006). Post-tensioning bars may also be used ingrouted systems, although they have not changed significantlysince their first introduction. The latest generation of post-tensioning systems includes multiple layers of corrosionprotection due to an increased awareness of the importance ofa durable system.