Integrated visualization for reinforced concrete using ultrasonic tomography and image-based 3-D reconstruction

• Contactless system provides high quality signal data and enable rapid data collection.
• Ultrasonic tomograms detect embedded defects with high volumes of steel reinforcement.
• Computer vision images provide information on surface condition and geometrical deviation.
• Integrated visualization offers deep understanding of the tested sample.
• Integrated visualization reported here has not yet been reported for structural inspection.

A comprehensive visualization scheme to characterize reinforced concrete structures, based on integrated ultrasonic tomography and 3-D computer vision, is presented. A recently developed hybrid air-coupled/contact ultrasonic transducer system enables the generation of internal tomographic images that characterize the interior condition, for example the presence of voiding defects, of full-scale reinforced concrete elements. Based on tomographic cross-sectional slice images, 3-D volumetric internal images are built up to obtain full stereoscopic analysis. An automated image-based 3-D reconstruction technique is applied to the same structure to visualize external condition. Both internal and exterior visualizations of full-scale concrete column are integrated in a single three-dimensional image. The approach is demonstrated on a reinforced concrete column sample that exhibits exterior geometric inconsistency with the original design and also includes controlled internal defects. The experimental results demonstrate that the proposed integrated visualization technique provides holistic characterization of the interior and exterior of the test sample and thus demonstrates great potential for facilitating inspection of existing structures in the field.