Christoph Kohl

COMPLEMENTARY APPLICATION OF RADAR, IMPACT-ECHO, AND ULTRASONICS FOR TESTING CONCRETE STRUCTURES AND METALLIC TENDON DUCTS

Nondestructive testing of concrete structures plays an increasing role in civil engineering, although until now the full potential of such techniques has not been tapped. For posttensioned structures, the investigation of tendon ducts is one of the most essential testing problems. The location of tendon ducts, the determination of concrete cover and, especially, the detection and quantification of ungrouted areas inside the ducts are the relevant questions. Recent developments and opportunities of radar, impact-echo, and ultrasonics for the investigation of tendon ducts are presented. Although the obtained results on positioning and concrete cover determination are sufficient, the location of ungrouted areas is still a matter of research. Thus, new approaches for this testing problem have to be considered. Additionally, the combined use of complementary techniques offers a high potential to increase the reliability of results. Data will be displayed on the combined application of acoustic and electromagnetic impulse-echo methods and of data fusion related to the investigation of tendon ducts.

Combining the results of various non-destructive evaluation techniques for reinforced concrete: data fusion

Abstract: For the investigation of various testing problems on reinforced concrete bridges, which are a major part of the ageing infrastructure, efficient combinations of non-destructive testing (NDT) methods are urgently required. Among these, data fusion has been developed rapidly during the past few years enabling an efficient understanding and interpretation of complementary and redundant data. It is demonstrated how the pixel-wise fusion of data sets recorded on-site by various methods along the same area of structural concrete elements (concrete bridges) enhances the information content in the fused data set. The varying approaches employed by data fusion algorithms are discussed. The results of these investigations show the high potential of reconstruction and data fusion for the improvement and simplification of the analysis and visualisation of large data sets measured with impulse–echo methods.

Radar and Fusion for Concrete Elements

Radar measurements are nowadays widely used for non-destructive testing of concrete structures [1]. Nevertheless mainly profiles are measured and interpretation is done by examination of raw data only.