Temporal and spatial evaluation of grout failure process with PC cable breakage by means of acoustic emission

Corrosion-induced cables' breakage is reported frequently in post-tensioned PC structures, leading to eventual failure in the worst case. However, the specific failure mechanism as well as deterministic investigation techniques for cables' breakage have yet to be clarified. In this research the cables' breakage and subsequent failure processes are studied by acoustic activity. When the cable is ruptured, elastic energy is released accompanying elastic waves namely acoustic emission (AE). Identification of the breakage could be carried out by this AE activity, followed by specifying the source location. While as for the existent PC breakage, the area of breakage could be determined by examining secondary AE activity generated due to the friction between fractured grout agent and tendons, which is resulted from re-anchoring around the breakage. In this paper, these AE activities are experimentally produced using a full scale PC beam being subjected to four-point bending, where the cables' breakages are simulated by stress reduction of each of PC cables in turn and the breakage areas as well as the failure areas of grout material are quantitatively identified with AE activities. As a result of careful observation of AE activity in terms of failure types, it became obvious that the failure progress due to cables' breakage and following re-anchoring were readily identified by the AE activity. In addition, the existent breakage with re-anchoring area could be specified by AE sources as they had peculiar frequencies than others. (C) 2013 Published by Elsevier Ltd.