Novel Non-destructive Technique of Internal Deterioration in Concrete Deck with Elastic Wave Approaches

Abstract

An innovative technique to visualize internal defects in concrete bridge decks has been developed. To achieve visualization of internal damage, acoustic emissions (AE) using the two following analysis methods is employed. Firstly, based on the data detected by AE sensors, the location of the AE sources is estimated assuming the unique elastic wave velocity over the measured concrete. Then, velocity distributions in the concrete are evaluated by an advanced ray-tracing method. The technology can be applied from the bottom surface of the deck without closing bridges and stopping traffic. We have successfully verified the effectiveness of this advanced technique through the application to an in-service bridge. The comparison between the analysis result and core samples taken from the slab revealed the high validity of this technology. Accordingly, the internal damage of concrete deck can be evaluated quantitatively by applying a simple procedure using two evaluation axes, that are AE source density and propagation velocity of AE wave in the concrete. Thus, the local deterioration of the concrete deck can be classified into several stages that represent the damage levels of internal defects.