Advancing Condition Assessment of Post-Tensioned Ducts Using Ultrasonic and Impact Echo Data

Post-tensioned (PT) girders are widely used in bridge construction, where the grout system serves two purposes: transferring the load between tendons and concrete and protecting the tendons against corrosion. However, environmental exposure and poor-quality construction practices can compromise the grout system quality, resulting in voids, soft grout, or corrosion. This study presents a comprehensive multi-modal nondestructive evaluation (NDE) methodology to assess the integrity of the grout system using ultrasonic testing, impact echo, GPR, and HRI. Instead of relying solely on the ultrasound magnitude, the phase and real part were incorporated as well to improve condition assessment. Additionally, impact echo signatures were established and compared with individual spectra to assess the grout condition. This approach demonstrates the effectiveness of integrating multiple technologies and analysis techniques to detect potential deficiencies in PT systems and support maintenance practices.