Estimation of Crack Depth in Concrete Using Diffuse Ultrasound: Validation in Cracked Concrete Beams

The objective of this paper is to experimentally validate the previously proposed diffuse ultrasonic technique for measuring crack depth in concrete structures. The validation ultrasonic measurements are performed on real cracks that are formed in full scale reinforced concrete beams. Three reinforced concrete beams are designed and manufactured, and then placed under four point bending to create vertical cracks on the top surface of the beams. Diffuse ultrasonic measurements are conducted on these cracks using the procedure and instrumentation developed in the previous research. The measured crack depth results are compared with the results of side-surface visual inspection and direct stereo-microscopy measurements on cores extracted from the cracked areas. In all cases considered, the crack depths measured by the diffuse ultrasonic method appear to deviate by about 1 cm when compared to those of the core results. The possible causes of this deviation are discussed. However, the overall results show that the diffuse ultrasonic method provides consistent and reasonably accurate crack depth measurement in concrete beams.