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Parameters for the quantitative assessment of ultrasonic imaging for concrete elements

: Streicher, D.; Krause, M.; Kohl, C.; Schickert, M.; Kroggel, O.; Müller, W.

Wiggenhauser, H. ; Bundesanstalt für Materialforschung und -prüfung -BAM-, Berlin; Deutsche Gesellschaft für Zerstörungsfreie Prüfung e.V. -DGZfP-, Berlin:
Non-Destructive Testing in Civil Engineering 2003. CD-ROM : NDT-CE, Berlin, September 16-19, 2003
2003 (DGZfP-Berichtsbände 85-CD)
ISBN: 3-931381-49-8
International Symposium on Non-Destructive Testing in Civil Engineering (NDT-CE) <2003, Berlin>
Conference Paper
Fraunhofer IZFP ()
concrete; ultrasonic imaging; SAFT

Ultrasonic investigation is an established non-destructive testing method for detection of defects and material characterisation. In the last years scanning ultrasonic echo methods were developed especially for the application in civil engineering.
The different scanning ultrasonic echo methods are modified with respect to the type of the transducer applied, the number and the arrangement of transducers and the frequency used. Also different algorithms are used to analyse the measured data, for instance SAFT (Synthetic Aperture Focusing Technique) reconstruction. The results are typically presented as B- and C-scans, obtained from raw data or the SAFT reconstructed data.
Since 2001 several German research institutes co-operate within the scope of the research initiative Non-destructive Evaluation of Concrete Structures Using Acoustic and Electromagnetic Echo-Methods (FOR 384) supported by the Deutsche Forschungsgemeinschaft (DFG). One of the tasks is to investigate these ultrasonic echo methods for special applications like the detection of cavities in concrete structures or faults in tendon ducts.
Concrete test specimens with intentional faults have been manufactured and investigated. Parameters were defined to assess the results more objectively. Currently three parameters -signal/noise-ratio, lateral edge resolution and uniformity- are considered. For the first time results of different working groups on the same imaged objects are compared quantitatively. It should help to get more knowledge about the ultrasonic inspection of typical faults in civil engineering structures.