| 摘要 |
PROBLEM TO BE SOLVED: To maintain the nonslip function of the surface of a metallic member for a time longer than the case of conventional metallic members because the metallic member is difficult to oxidize and an aggregate layer is difficult to peel. SOLUTION: In the surface-treatment structure of the metallic member, a zinc film layer is formed on the surface of the metallic member while the aggregate layer is formed on the external surface of the zinc film layer. In a frame body for an underground structure in which an inclined plane is formed on the outer periphery of an annular frame body, the zinc film layer is formed on the inclined plane while the aggregate layer is formed on the external surface of the zinc film layer. The peeling of an asphalt layer covering the inclined plane can be prevented for a time longer than the case of conventional metallic members. Cracks are difficult to develop even by the passage of cars and the asphalt layer is difficult to peel though the asphalt layer (a paving material) covering the inclined plane is thinned gradually towards the upper edge of the inclined plane. COPYRIGHT: (C)2004,JPO&NCIPI
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