Void forming core formwork for concrete beam

摘要

To render a formwork ( 10 ), having a hollow ( 11 b) defined therein and embedded in the elongated concrete member ( 40 ) during casting of a concrete material, to be lightweight, environmentally friendly and inexpensive and to have a sufficient strength, the formwork ( 10 ) includes a tubular member ( 11 ) formed by bending an oblong plate of corrugated cardboard ( 5 ) made of paper. The corrugated cardboard plate ( 5 ) includes a plurality of corrugated cardboards ( 3 ) laminated together and each formed by bonding liner sheets ( 2 ) to surfaces of a corrugated sheet ( 1 ). The corrugated cardboards ( 3 ) are laminated together with flutes of the corrugated cardboards ( 3 ) oriented in a direction (P) across a thickness of the corrugated cardboard plate ( 5 ), and a sheet ( 4 ) is bonded to front and rear major surfaces thereof.