| 摘要 |
PURPOSE:To enable detection of even an invisible fine cracking, by applying a transparent fluorescent liquid on the surface of concrete in a uniform film to irradiate an ultraviolet black light to the surface thereof after a required time passes. CONSTITUTION:When ultraviolet black light is irradiated before a fluorescent liquid 3 is absorbed into concrete 1, it looks bright in bluish green at a sound portion 4 thereof without cracking. By contrast, the film of the fluorescent liquid 3 breaks on the edge of the cracking 5 at a portion with a relatively broad cracking 5 because of weak capillarity; it fails to light, looking dark even by the ultraviolet black light and hence, the cracking can be detected clearly. On the other hand, at a fine cracking 6 portion, intense capillarity causes the ambient fluorescent liquid 3 to be absorbed into the concrete 1. It looks dim in an intermediate range between the sound portion 4 and the cracking portion 5, hence visually recognized. Thus, the sound portion 4 and cracking portions 5 and 6 are visually recognized thereby enabling detection thereof.
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