JPH0868107A - Thin precast formwork and precast concrete board used for it - Google Patents

Abstract

PURPOSE: To increase the strength of a precast formwork and make it thin without requiring many auxiliary materials at the time of execution by integrally introducing a prestressed reinforcing material into the precast formwork. CONSTITUTION: Precast concrete boards are erected on the floor 4, they are combined to form a thin precast formwork 1, and it is supported by holding materials 3. A prestressed reinforcing material 2 is integrally introduced into the formwork 1. Compressive stress is applied to the tensile side concrete in advance at the time of no load. Concrete 5 is placed in it, and a concrete structural body is constructed while the formwork 1 is left as it is. Tensile stress is rarely generated on the concrete when a load is applied and the reinforcing bars on the tensile side are extended. The bending strength of the formwork 1 is sharply improved, and the auxiliary material supporting the formwork 1 can be sharply simplified.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a concrete formwork, and more particularly to a thin-walled precast formwork having improved strength and a precast concrete slab used therefor.

[0002]

2. Description of the Related Art In general, a concrete structure is assembled into a concrete formwork, and after the concrete is placed in the formwork, the formwork is removed. The formwork of the precast concrete slab is also used.

The precast formwork used for this purpose is preformed so as to be a part of a concrete structure such as a predetermined pillar, and assembled on site.

[0004]

Since a very large pressure acts on these precast forms during concrete pouring, they must be fixed so as to withstand them during construction. In particular, concrete is extremely weak against elongation, so care must be taken to prevent cracking.

However, when the precast mold is made of a relatively thin material, it is difficult to stand on its own, and in order to sufficiently reinforce the precast mold, a large number of auxiliary materials such as separators, pipes, etc. are provided around the precast mold. It is necessary to provide supporters and support them. This causes waste of materials and causes a delay in the construction period. In addition, a large number of occupations are required, resulting in high cost.

On the other hand, if a thick precast plate is used to reduce auxiliary materials, the form itself becomes large,
There is a risk that the difference between the cross-sectional size of concrete and the cross-sectional size of the structure after completion, that is, the so-called fluffy size, may increase. That is, the thickness of the formwork is added to the size of the structure, and the actual size of the structure becomes larger than expected. If the degree is large, various inconveniences occur.

Therefore, as a precast mold used for such an application, it is required that the precast mold has high strength and is thin, but there has been no suitable one in the past. The present invention has been made in view of the above matters, and since it has high strength and can be thinned, it is technically necessary to provide a thin precast formwork structure in which it is necessary to use a large amount of auxiliary materials during construction. It is an issue.

[0008]

In order to solve the above technical problems, the present invention has the following constitution. That is, it is a precast formwork which becomes a part of the concrete structure after the concrete is placed, and the prestressed reinforcing material is integrally introduced therein.

This formwork can be assembled by appropriately combining precast concrete slabs, in which case the prestressed reinforcing material is integrally introduced into these precast concrete slabs. (Prestressed Reinforcing Material) As the prestressed reinforcing material, PC steel wire, PC steel stranded wire, carbon fiber, synthetic resin fiber, and glass fiber can be used. The shape thereof may be a linear one or a net body. (Manufacturing method) Further, since this is mainly manufactured in a factory, it is preferable to process by a pretensioning method. That is, concrete is placed in a state where tension is applied to a PC steel wire or the like to manufacture a precast plate.

When the mold of the present invention is used, a holding material for supporting it is usually provided. This holding material is, for example, a stretchable rod, which is slanted between the floor and the precast mold 1 to press the precast mold 1 from the side surface. By carrying out this from all sides, the thin precast mold 1 can be supported easily and surely.

The present invention is mainly used in a pillar type, but is not limited thereto.

[0012]

In the present invention, since the prestressed reinforcing material 2 is integrally introduced into the precast mold 1, a compressive stress is applied to the tension side concrete in advance when no load is applied. When a load is applied and the reinforcing bars on the tensile side are extended, almost no tensile stress is generated in the concrete. Therefore, the bending strength of this form is significantly improved. Therefore, a simple auxiliary material for supporting the precast mold 1 is sufficient.

Further, since the precast mold 1 can be made thin, the completed structure will not be unnecessarily increased in size and the degree of freedom in design will be increased. If the prestressed reinforcing material is a net, the strength is improved against stress from all directions.

[0014]

Embodiments of the present invention will be described with reference to FIGS. In this embodiment, a precast concrete slab is erected on the floor 4, and the precast concrete slab is combined to form a concrete thin precast mold 1 having a square cross section. afterwards,
Prestressed reinforcing material is placed inside the plate-shaped precast concrete plate that constitutes the thin precast mold 1 in which concrete 5 is cast inside and a concrete structure is constructed with the thin precast mold 1 left. 2 is molded integrally. In this embodiment, a PC steel wire is used as the prestressed reinforcing material 2, and as shown in FIG. 2, a total of 6 pieces are embedded along the longitudinal direction of the thin precast mold 1. These prestressed reinforcing materials 2 are processed by the pretensioning method.

As the prestressed reinforcing material 2, not only metal but also carbon fiber, synthetic resin fiber and glass fiber can be used. In addition to the linear shape, a net body can be used.

As shown in the drawing, the thin precast formwork 1 is formed by joining the side edges of the precast concrete slab. An anchor 6 is driven into one of the thin precast molds 1, and a bolt 7 is screwed into the anchor 6 through the other thin precast mold 1. Prior to screwing in, the rubber packing 9 and washer 8 are passed through the bolt 7 and then tightened. The purpose of providing the rubber packing 9 is to improve the adhesion between the thin precast molds, and even if the bolt 7 is loosened a little, a gap is not created between the thin precast molds.

At the bottom of the thin precast mold 1, an L angle 11 for preventing the concrete 5 from flowing out is closely attached, and a bolt 10 for finely adjusting the height of the thin precast mold 1 is provided. ing. The L angle 11 is fixed to the floor 4 with concrete nails 12. The bolt 10 is screwed into an anchor 6 that is previously driven into the bottom surface of the thin precast mold 1, and the head of the bolt 10 contacts the floor 4 to support the thin precast mold 1. The thin precast mold 1 can be finely adjusted up and down by turning the bolt 10 with a spanner.

The thin precast mold 1 is supported by a holding material 3. The holding material 3 is a bar that is expandable and contractible by a turnbuckle or the like, and is slanted between the floor 4 and the thin precast mold 1 to press the thin precast mold 1 from the side surface. By carrying out this from the four sides, the thin precast mold 1 is easily and surely supported.

After assembling the thin precast formwork 1, concrete 5 is placed inside to complete the columns. Since the prestressed reinforcing material is integrally molded in the thin precast mold as described above, the bending strength is significantly improved, and many auxiliary materials for supporting the thin precast mold 1 as in the conventional art are unnecessary. .

Further, since the thin precast mold 1 can be thinned, the size of the fluff can be greatly reduced, and the completed structure will not be unnecessarily enlarged. If the prestressed reinforcing material 2 is a net, the thin precast formwork 1 has improved bending strength from all directions, and the surface strength of the completed column can be improved.

[0021]

According to the constitution of claim 1 of the present invention, since the prestressed reinforcing material is integrally molded in the precast mold, the bending strength can be greatly improved. Therefore, the auxiliary material for supporting the thin precast mold can be greatly simplified, and the construction can be simplified. Moreover, since the formwork is thin, the completed structure will not become larger than necessary.

[Brief description of drawings]

FIG. 1 is a plan view of a thin precast mold according to an embodiment of the present invention.

FIG. 2 is a perspective view showing an embodiment of the present invention.

FIG. 3 is a sectional view of a corner portion of a completed thin precast mold according to an embodiment of the present invention.

FIG. 4 is a sectional view of a bottom portion of a completed thin precast mold according to an embodiment of the present invention.

[Explanation of symbols]

 1 ・ ・ Thin precast formwork, 2 ・ ・ Prestressed reinforcing material, 3 ・ ・ Holding material.

Claims (3)

[Claims] 1. A thin-walled precast formwork, which is a precast formwork that becomes a part of a concrete structure after placing concrete, and in which a prestressed reinforcing material is integrally introduced therein. 2. A precast concrete slab for a thin precast formwork, characterized in that a prestressed reinforcing material is integrally introduced therein. 3. The thin precast formwork according to claim 1, or the precast concrete slab according to claim 2, wherein the prestressed reinforcing material is a net.