Embedding ultrasonic transducers in concrete: A lifelong monitoring technology

This paper deals with lifelong monitoring of concrete structures using embedded piezoelectric transducers. Thanks to such transducers, monitoring of the concrete can be automated both at the early age, light after the concrete is cast, and over the long term, until the end of the lifetime of the structure. For long term monitoring, the wave velocity variations introduced by operational factors effects should be filtered out. In the present study, we introduce a new technique called the Direct Wave Interferometry (DWI) which uses time stretching only on the early part of the recorded wave. This appears to be a good tradeoff between the high resolution of the Coda Wave Interferometry (CWI) for low velocity variations and the reliability of the measurement of the time of flight (TOF) for large velocity variations. (C) 2018 Elsevier Ltd. All rights reserved.