Quantitative evaluation of contactless impact echo for non-destructive assessment of void detection within tendon ducts

Owners of pre-stressed concrete structures must realize preventive maintenance in order to maintain structural safety and limit economic losses. Detection voids in tendon ducts, where corrosion could occur, is key in this effort. This paper focuses on the quantification of the performance of the impact echo method (IEM), applied using a new laser interferometer contactless robot, for duct void detection in a reinforced concrete wall. We show first the influence of the wall stiffness on the IEM (resonance) frequency. We use a probabilistic modeling to evaluate the IEM. We illustrate a way for accounting on-site uncertainties of NDT measurements.