Floatable concrete block structure and method for manufacturing same

A method of manufacturing a floatable concrete block structure, the method comprising:

• a first concrete block fabrication step of fabricating a first concrete block comprising a first concrete block body in which a buoyancy-chamber bottom surface is formed on an upper surface thereof, and a first watertight packing disposed on the upper surface of the first concrete block body in a form surrounding the buoyancy-chamber bottom surface, wherein the first concrete block further comprises a plurality of column rebar assemblies, each of which extends vertically from the first concrete block body and protrudes upward from the upper surface of the first concrete block body;
• a second concrete block fabrication step of fabricating a second concrete block comprising a second concrete block body in which a second buoyancy chamber having an open lower surface and a plurality of first column through holes extending vertically are formed;
• a first concrete block installation step of installing the first concrete block by submerging the first concrete block in water after the first concrete block fabrication step;
• a second concrete block installation step of installing the second concrete block such that a concrete block assembly is formed by installing the second concrete block on the first concrete block after the second concrete block fabrication step and the first concrete block installation step, an assembly buoyancy chamber having a closed lower end is formed in the concrete block assembly by the second buoyancy chamber of the second concrete block and the buoyancy-chamber bottom surface of the first concrete block, and the first watertight packing is located between the first concrete block and the second concrete block and prevents water from being introduced into the assembly buoyancy chamber from the outside, wherein the second concrete block is installed on the first concrete block such that each of the column rebar assemblies of the first concrete block is inserted into each of the first column through holes of the second concrete block, and concrete-column through holes each having a closed lower end are formed in the concrete block assembly by the first column through holes of the second concrete block being covered by the upper surface of the first concrete block body;
• a column drainage step of removing water contained inside the concrete-column through holes in which the column rebar assemblies are inserted after the second concrete block installation step;
• a concrete column formation step of forming concrete columns coupling the first concrete block and the second concrete block to each other along each of the first column through holes after the second concrete block installation step so as to form a concrete block structure having the first concrete block and the second concrete block coupled to each other by the concrete columns, wherein by pouring concrete into the concrete-column through holes after the column drainage step, the concrete columns having the column rebar assemblies and the poured concrete integrated with each other are formed;
• and
• an assembly buoyancy chamber drainage step of draining water contained in the assembly buoyancy chamber after the concrete column formation step so that the concrete block structure is floated to a water surface by the buoyancy of the assembly buoyancy chamber.