International practice using NDE for the inspection of concrete and masonry arch bridges

Abstract

This paper reviews international practice in the inspection of bridges, and looks at the NDE of post-tensioned concrete and masonry arch bridges. Key continental European practice is compared with the United Kingdom and the United States. Given the wide range of languages and cultural backgrounds, there is remarkable similarity between procedures for bridge inspection. However, there is no one standard database used worldwide, which might give the opportunity to spot international trends in bridge type behavior. Non-destructive evaluation is growing into an established tool for the special investigation of concrete and masonry arch bridges. These trends are driven by Advisory notes from the Highways Agency, London, U.K., and by the American Concrete Institute. In this paper, many key problem areas of concrete and masonry arch bridges are identified and appropriate NDT techniques discussed. Some of the techniques used on concrete are capable of being transferred to new masonry, but not necessarily to old stone masonry arch bridges, with their special features such as large stone block size and the use of lime mortar. For stone masonry arch bridges, it has been shown that the most useful techniques are low frequency sonic echo, sonic transmission, and sonic tomography. Ground penetrating radar (GPR) also has a role in the evaluation of masonry arch bridges. In the case of concrete bridges, the techniques of ultrasonic tomography, impact echo, impulse response, and GPR are particularly relevant. GPR has only a limited role in the investigation of post-tensioned concrete bridges, where the tendon ducts are metallic. Examples of NDE practice are given in the paper.