The exfoliation and falling of concrete linings due to material deterioration or defective work has become a problem. Hammering inspection has been commonly applied to check concrete structures for defects. However, since there are a very large number of concrete structures that need to be checked, the inspectors have a significant burden. RTRI has developed a diagnostic system that permits the accurately judging of the conditions of anomalies of concrete structures by the combination of images obtained by an infrared camera and a CCD camera. The system offers a new inspection method that is more efficient than hammering inspections. The system consists of an infrared camera, a CCD camera, a laser range finder and an angle meter (for measuring angle of elevation and angle of deviation). It allows for high-accuracy image processing through integration of the positional information obtained by the range finder and angle meter, the pre-registered information about the infrared camera/CCD camera lenses (aberration and parallax of each lens), etc. For structures in an open section, such as elevated rigid-frame bridges, the high-sensitivity infrared camera permits checking by a day's change in outdoor temperature alone. In addition, when this system is employed in active infrared thermography, it significantly widens the scope of application of the technique.

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