Metrological Validation of Non-Destructive Testing Techniques for Assessing the Condition State of Pre-Stressing Systems

Abstract

The number of prestressed reinforced concrete bridges exceeding their expected lifespan is constantly increasing, leading to a growing interest by infrastructure managers and control authorities in monitoring and maintaining them. Accurate knowledge about the general degradation of bridges is necessary for effective planning and prioritization of maintenance intervention and structural monitoring. The prestressing system of a bridge is a particularly sensitive component; its condition state plays a central role in risk assessment and bridge maintenance. Non-destructive, semidestructive, and destructive tests are recommended to evaluate the prestressing system's condition state by many guidelines. Several innovative investigation techniques are currently available on the market; however, their actual effectiveness is still debated and requires further investigation. This work aims to verify the effectiveness of the following non-destructive tests (NDTs): Digital Radiography, Ground Penetration Radar, and Reflectometric Impulse Measurement Test. These NDTs have been performed on the Alveo Vecchio viaduct, which is a decommissioned highway bridge now used as an open-air laboratory. These NDT’s effectiveness is studied through correlation analyses performed by cross-referencing the NDT outcomes and the corresponding intensity levels of defects directly observed during a controlled demolition of the deck beams. This study provides significant insight into the accuracy level of non-destructive tests and is part of an extensive experimentation campaign.