Effective Repair Grouting Methods and Materials for Filling Voids in External Posttensioned Tendons

Abstract

Recent inspections of segmental posttensioned (PT) bridges reported the presence of large voids in ducts that contain PT strands. Corrosion of the strands was observed in these voids, which are believed to be a result of poor grouting. Corrosion of the PT strands can result in structural failure. Controversy exists on how best to protect PT tendons from corrosion; filling these voids with grout is one option. An optimized grouting procedure for repairing these voids is needed to protect the strands from corrosive environments. This research investigates three grouting methods for efficiently repairing the voids in PT duct systems: vacuum grouting (VG), pressure grouting (PG), and pressure–vacuum grouting (PVG). Each method is evaluated for filling capability, filling performance, and economic feasibility. Also, three prepackaged grouts for repair are assessed in this research to propose the most suitable material for repairing voids in the PT ducts. The results indicate that the PG and PVG methods are more constructible and likely to be more economical than the VG method. However, the PVG and VG methods seem to be more effective than the PG method in filling the voids. As a result of these tests, the PVG method is recommended for filling voids in tendons. The results also show that Classes C-1 and C-2 grouts have better filling capability than Class C-3 grout.