There has been a long history of bonded post-tensioning (PT) in reinforced concrete structures. Generally, these structures have performed well except when bonded PT tendons have suffered from corrosion as a result of grout deficiencies.
For many years cement – water grout was used for grouting PT tendons. Cement – water grouted tendons are likely to have voids in the grout due to the propensity of cement – water grouts to bleed. Prepackaged grouts are generally more robust but they may segregate in certain circumstances. Segregated prepackaged grouts have also contributed to PT strand corrosion.
Evaluation of existing post-tensioned structures is important to determine if defects exist in the grout.
If grouting defects are identified an impregnation system can be used to mitigate corrosion and extend the service life of PT tendons installed in deficient grout.
This paper discusses the evaluation of PT structures and the PT impregnation technique which has been developed to mitigate corrosion of grouted PT tendons. Project case studies and laboratory research will be presented to demonstrate the technique and its effectiveness.