PT duct grouting quality inspections in concrete bridges using FWI applied to ultrasonic data.

Ultrasonic testing for inspections of the grouting quality in post-tensioned (PT) ducts concrete bridge structures is complicated by the complexity of the received data. Scattering, attenuation, and reflections within the concrete make interpretation difficult. Traditional analysis depends on manual interpretation of amplitude, limiting reliability and consistency, particularly in aging or poorly documented infrastructure. W-Scan by Mondaic offers a data-driven alternative to infer high-resolution 3D models from physics- informed digital twins. By iteratively fitting simulated and measured A-Scans in both amplitude and phase, the method produces quantitative maps of the heterogeneous elastic properties within the structure allowing for localization and sizing of voids or other defects. A fully automated calibration procedure requires no prior structural information, enabling full waveform inversion (FWI) with minimal user input. This demonstration will show several case-studies evaluating grouting quality in post- tensioned (PT) ducts using FWI applied to ultrasonic data from several commercial instruments. The technique can stitch together a wide area digital twin by automatically merging adjacent scans. The result allows for consistent, operator-independent interpretation and offers a data-driven way for evaluating PT duct integrity.