Detection of bridge-deck delamination using full ultrasonic waveform tomography

A two-dimensional (2D) time-domain waveform tomography technique is presented for detection of delamination in concrete bridge decks. Measured ultrasonic surface wave fields were inverted using a full waveform inversion (FWI) technique, based on a finite-difference solution of 2D elastic wave equations and Gauss-Newton inversion method. The FWI was applied to both synthetic and real experimental data sets. The real experimental data set was collected on a validation concrete slab using an ultrasonic shear-wave tomography system. The inversion results showed that the waveform analysis was able to delineate delamination zones, including a real delamination at a depth of 80 mm.