PROBLEM TO BE SOLVED: To provide a concrete structure for which casting sand fine powder, generated in a large amount in a casting production line, can be effectively used. SOLUTION: The concrete structure is formed by hydration-hardening of a concrete composition including fine aggregate and hydraulic cement comprising limestone and clay. All or a part of the clay and the fine aggregate in the concrete composition are replaced with the casting sand fine powder generated from the production line of casting selected from the group consisting of iron-based, zinc alloy-based or copper alloy-based castings. The structures 1A, 1B, 1C are used for seaweed beds and fish banks by sinking them to the water bottom of sea shore and the like. COPYRIGHT: (C)2013,JPO&INPIT
