JPH0516131A - Manufacturing method of precast concrete members - Google Patents

Abstract

(57) [Summary] [Purpose] To manufacture a precast concrete member that also has a hollow portion or a groove portion on the inner surface and also serves as a formwork, ensuring uniform thickness and high productivity. [Structure] Inside the outer formwork with hoop reinforcements, etc., insert the inner formwork with a rigid flat plate on the four sides and a square elastic membrane at the four side corners, and a rectangular cross section. Gas is press-fitted into to form a rectangular cross-section with a predetermined size, concrete is placed between the inner and outer molds, and after hardening, the inner gas is discharged to reduce the cross-sectional size of the inner mold and demold.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a precast concrete member having a hollow section having a square cross section or a U-shaped groove section which also serves as a mold.

[0002]

2. Description of the Related Art As a method of manufacturing a column precast member having a thin hollow portion having a rectangular cross section or a beam precast member having a thin groove portion having a U-shaped cross section, conventionally, an inner frame having irregularities is used. To use. Buried using metal lath etc. Centrifuge molding. There have been means such as using an elastic body form such as a rubber tube.

However, the above-mentioned conventional method has the following problems. When using an inner mold, it becomes difficult to remove the mold. In particular, if the inner mold has irregularities, it becomes very difficult. If metal lath is used, slag leaks during manufacturing, which is a problem in ensuring quality. In addition, the cost is high because it is buried.
Centrifugal molding requires large-scale equipment and cannot be easily manufactured. When an elastic body form is used, the cross-section is rounded in order to inflate the gas and inflate it, and even if restrained by a hoop muscle or the like, the roundness remains and the wall thickness is not uniform. If the wall thickness is not uniform, bar arrangement work cannot be performed accurately and the condition is not good.

The present invention has been made in view of the above problems. An object of the invention is to propose a method for manufacturing a precast concrete member having a hollow portion or a groove portion, which also serves as a formwork, with a uniform thickness and a high productivity.

[0005]

This precast concrete member is manufactured by a hollow section having a rectangular cross section or a U section.
In a method of manufacturing a precast concrete member that also serves as a formwork with a groove-shaped part, a square cross section is used, four sides are rigid flat plates, and four corners are a closed inner formwork made of flexible material Insert the gas inside the rebar inside the frame, press the gas into the inner mold to make it have a predetermined cross-sectional dimension, place concrete between the inner and outer molds, and then discharge the gas from the inner mold to make the corner angle. It is characterized by shrinking the part and making the inner formwork dimension small and releasing from the mold.

[0006]

[Function] When gas is pressed into the inner mold, the four sides are rigid flat plates, so it does not become round and its cross section is square, and it is restrained by the surrounding hoop or stirrup stirrup arranged in the outer mold. Therefore, a rectangular cross section having a predetermined size can be obtained. Therefore, it is possible to manufacture a member having a uniform wall thickness and an uneven inner surface with high accuracy, and it is possible to make the member thin. By discharging the gas in the inner mold or exhausting it under reduced pressure, the flexible material at the corners of the four sides is shortened, the cross-sectional dimension is made small, and the concrete surface and the inner mold surface are separated, making it easy. Since it can be removed from the mold, productivity can be increased.

[0007]

EXAMPLES FIGS. 1 and 2 show an inner formwork 1 used in Examples.
It has a rectangular cross section and is of a hermetic type, and is provided with an inlet / outlet port 2 for injecting and discharging gas at one end. The four sides of the inner mold 1 are made of a rigid plate 3, and on the surface thereof are a large number of rectangular parallelepiped projections 4. The projection 4 is for ensuring the integrity with the post-cast concrete, but may be omitted if it is not necessary in design. The corners of the four sides are composed of a rubber elastic film body 5 which is a flexible material. The elastic film body 5 is bonded and laminated to the lower surfaces of the rigid flat plates 3 on the four sides to form a continuous inner surface on the four sides of the inner mold.

When gas is pressed into the inner formwork 1 from the injection / exhaust port 2, the elastic body 5 at the corner portion expands to form a rectangular cross section having a predetermined size as shown in FIG. Exhaust the gas in the inner formwork 1,
Alternatively, when the pressure is reduced, as shown in FIG. 3, the elastic film body 5 at the corner portion contracts or bends and the corner portion contracts, and the cross-sectional dimension becomes small.

In order to manufacture a precast concrete member for a column having a hollow section having a square section by this manufacturing method, as shown in FIG. 4, a main bar 7 and a hoop are provided in a peripheral section of an outer mold section 6 having a rectangular section. The muscle 8 is arranged, and the inner formwork 1 is inserted inside the muscle 8 in a contracted state. When gas is pressed into the inner mold 1 after insertion, the rigid flat plates 3 on the four sides of the inner mold are constrained by the hoop muscles 8 to form a rectangular cross section of a predetermined size. In this state, concrete 9 is placed between the inner and outer molds 1 and 6 to cure the concrete 9, and the inner mold is contracted and demolded as shown in FIG. Although FIG. 4 shows a manufacturing example in which concrete is poured in the axial direction, it is also possible to open one of the outer molds and pour concrete from the open surface as shown in FIG. Figure 6
Has a hollow portion 10 of the obtained rectangular cross section, and the inner surface has irregularities 1
1 is a precast concrete member for a column.

Similarly, an outer mold 6'having a U-shaped cross section shown in FIG.
After arranging the main reinforcements 7 and the stirrup 12 reinforcements inside, the inner formwork 1 is inserted into the inner formwork, and concrete is placed between the inner and outer formwork 1 and 6'and demolded, as shown in FIG. It is possible to make a precast concrete member for a beam that has a grooved portion 13 having a U-shaped cross section and has unevenness 11 on the inner surface.

Further, as shown in FIG. 9, it is possible to pour concrete by turning the precast member upside down.

In the above embodiment, the main muscles of the outer periphery of the inner mold and the hoop muscles or the stirrup muscles are arranged. However, the main muscles may be omitted and only the hoop muscles or the stirrup muscles may be arranged.

[0013]

The present invention is as described above, and by this manufacturing method, it is possible to manufacture a precast concrete member having a hollow portion or a grooved portion which also serves as a formwork, with high accuracy and high productivity.

[Brief description of drawings]

FIG. 1 is a perspective view of an inner mold.

FIG. 2 is a cross-sectional view showing a state in which gas is pressed into the inner mold to inflate it.

FIG. 3 is a cross-sectional view showing a state in which gas in the inner mold is discharged and contracted.

FIG. 4 is a cross-sectional view showing a state in which concrete is cast in the inner and outer molds to produce a precast concrete member for a pillar.

FIG. 5 is a cross-sectional view showing another embodiment example of manufacturing a precast concrete member for a pillar.

FIG. 6 is a perspective view of a manufactured precast concrete member for a pillar.

FIG. 7 is a perspective view of an outer mold for manufacturing a precast concrete member for a beam.

FIG. 8 is a perspective view of the manufactured beam precast concrete member.

FIG. 9 is a cross-sectional view showing another embodiment example of manufacturing a precast concrete member for a beam.

[Explanation of symbols]

1 ... inner form, 2 ... injection / exhaust port, 3 ... rigid plate, 4 ... projection,
5 ... Elastic film body, 6 ... Outer form, 7 ... Main bar, 8 ... Hoop bar,
9 ... Concrete, 10 ... Hollow part, 11 ... Unevenness, 12 ...
Stirrup streak, 13 ... Groove.

Claims (1)

Claim: What is claimed is: 1. A method of manufacturing a precast concrete member that also serves as a formwork, having a hollow section with a rectangular cross section or a groove section with a U section. For the corners, insert a closed inner mold made of flexible material inside the outer mold, and press the gas into the inner mold to make it have a predetermined cross-sectional dimension. A method for producing a precast concrete member characterized by discharging gas in an inner formwork to reduce the corners and reducing the inner formwork size after the concrete is poured.