Factors Affecting Bond in Multi-Strand Post-Tensioning Tendons Including the Effect of Emulsifiable Oils

Recent corrosion problems worldwide have brought increased attention to the issues of durability and corrosion resistance of post-tensioned tendons. While the overall experience in the United States has been good, there is a desire to implement further measures to ensure the adequate protection of post-tensioning systems.

This thesis is part of a broad research program evaluating both temporary and long-term corrosion protection solutions. In particular, this thesis addresses the effect of emulsifiable oils used for temporary corrosion protection on bond in multi-strand post-tensioning tendons. The effect of duct type on bond behavior is also investigated.

Overall findings indicate that while the force developed by oiled strands is satisfactory, the reduced adhesion between the steel and the grout results in excessive slip. Additionally, galvanized steel pipes tended to allow the grout to slip relative to the duct or the duct to slip relative to the concrete at significantly reduced loads. Corrugated ducts eliminated the slip. Of the corrugated ducts, galvanized metal ducts provided somewhat better bond performance than high density polyethylene ducts.