Development of a Non-Destructive Testing (NDT) Tool for in-Situ Assessment of Prestressed Components

Prestressed/precast concrete girders are the most widely used superstructure system in highway bridges in Nebraska. Recently, the use of prestressed/precast concrete for deck construction have gained considerable attention of state officials to accelerate bridge construction and reduce maintenance cost. In all prestressed concrete systems, loss of prestress occurs immediately after production due to elastic shortening and during construction and operation due to shrinkage and creep of concrete and relaxation of prestressing steel, which are inevitable time-dependent phenomena. All of these effects reduce the pre-compression of the tension fibers of the concrete component and could significantly affect the component performance under service loads resulting in frequent cracking. The existing methods for measuring prestress loss require either installation of wired gauges inside the component during production or installation of surface gauges prior to prestress release to achieve a zero-stress reference, which are impractical. The objective of this research is to develop a self-referenced non-destructive testing (NDT) tool for in-situ stress evaluation of prestressed concrete bridge components.