Evaluation of strand bond properties along the transfer length of prestressed lightweight concrete members

This paper presents the results of an experimental program developed to study the feasibility of producing prestressed concrete girders using lightweight concrete. During the experimental campaign, bond tests were performed in push-in (TL bond test) and pull-out (FB bond test) types of specimens. To-scale prestressed concrete elements were produced, implemented, and tested. The variables studied were the type of concrete, the test age, and the delayed effects of bond. The TL bond test allowed the behavior of the transfer length to be characterized, governed by the Hoyer effect. Equations have been calibrated to identify the upper and lower transfer lengths using the experimental results of this trial. The proposed equations delimit the safety boundaries of the experimental transfer length values obtained in the experiments performed on the beams. The results obtained in the experimental phase discourage the use of the studied lightweight concrete for producing pre-tensioned concrete elements.