| 摘要 |
PROBLEM TO BE SOLVED: To provide a hollow cylindrical body which determines easily and quickly whether concrete is filled sufficiently in a lower area of the hollow cylindrical body or not, when forming a composite floor plate structure by a cylindrical composite floor plate form using the hollow cylindrical body.SOLUTION: This hollow cylindrical body 1 is used in the cylindrical composite floor plate form, is provided with the first perspective window 3-1 in at least one part S1 in the body 2 of the hollow cylindrical body 1, and is provided with the second perspective window 3-2 in a portion S2 opposed, in a diametric direction of the hollow cylindrical body 1, to a portion provided with the first perspective window 3-1 in the body 2 of the hollow cylindrical body 1, and in the portion overlapped with an arranging position of the first perspective window part 3-1 in a longitudinal direction of the hollow cylindrical body 1. |
