To provide hollow forms for a concrete long-sized body at a low cost having a lightweight and a high strength and being gentle to an environment.
The hollow forms 10 are buried in the long-sized body 40 when concrete is placed in the concrete long-sized body 40 with a hollow section 11b. In the hollow forms 10, the forms 10 have a polygonal sectional cylinder 11 formed by bending a corrugated plate 5 made of paper. A plurality of stage of the corrugated plates 5 are laminated and joined under the state, in which the irregularities of corrugated boards 3, in which liners 2 are fixed on the surfaces of the corrugated panels 1, are directed in the thickness direction of the plates 5, and sheets 4 are joined on the main surfaces and backsides of the plates 5.
HIKASA YOSHITOKU
PS MITSUBISHI CONSTRUCTION CO
Masashi Noda
Kenro Tsutsumi