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Air-coupled impact-echo scanner: Fast and contactless nondestructive testing of concrete pavements

The remaining useful life of concrete highway pavements is adversely affected by horizontal cracks or delaminations occurring within the pavement. This damage is not visible from the surface but poses an extreme danger to traffic if a spontaneous and massive expansion of these defects occurs due to variations in temperature. To prevent serious traffic restrictions or even accidents, a method to efficiently and quickly locate and evaluate defects is required so repairs can be planned and completed in a timely manner. The air-coupled impact-echo scanner presented in this paper was developed at the Technical University of Munich. This new scanner fulfills the major challenges for a non-destructive pavement testing system to be able to examine long stretches of pavements with a high acquisition speed and high detection probability. An optimized sensing concept in combination with a multiple excitation strategy was developed to minimize signal to noise ratio. The test equipment was tested and proven for routine use on highway pavements.