Use of Flexible Filler in Post-Tensioned Bridges

Presented by Natassia Brenkus, The Ohio State University The use of flexible fillers – greases and waxes – as post-tensioning (PT) tendon filler materials is a new practice to U.S. bridge construction. The use of these materials, in lieu of the more-common cementitious grouts, has implications to construction practices, structural behavior and durability. The Florida Department of Transportation began moving towards the adoption of these materials in select applications in 2014, completing a large research investigation in 2017; follow-up research work is currently underway. The implementation of flexible fillers has progressed into industry, with injections of an approach slab and a bent cap; a training seminar has been developed to educate practitioners and injection personnel. This paper is a summary of efforts to-date. It briefly summarizes the first research effort encompassing proof-of-concept and structural testing conducted to-date, including PT injection mock-ups, flexural static and cyclic testing of members with both internal and external tendons, and fatigue testing of PT tendons in diabolo-type deviators. Recent examples of injections in full-size members will be provided. Lessons learned and changes made to standard grouting practice are highlighted and future work required for the successful implementation of flexible fillers is discussed.