Detection of voids in grouted ducts using the impact-echo method N.J.CARINO National Institute of Standards and Technology, Gaithersburg, MD, USA M. SANSALONE Cornell University, Ithaca, NY, USA

Abstract The impact-echo method was used to detect simulated voids in grouted post-tensioning tendon ducts cast in a 1-m thick concrete wall specimen The study was part of a program to evaluate nondestructive test methods based on stress wave propagation. The locations of the voids in the ducts were not known by the authors until after their results had been reported to the principal investigator of the project. The impact-echo method was successful in locating the voids. However, the study showed that additional research is needed to gain a complete understanding of the interaction of stress waves with voids in cylindrical ducts.