JP7482834B2 - Method for constructing concrete joint formwork and method for constructing concrete members - Google Patents

Description

The present invention relates to the construction of concrete structures, and in particular to a method of constructing formwork suitable for constructing horizontal members such as beams and floors that require pouring joints, and to a method of constructing concrete members using this construction method.

When constructing a reinforced concrete building, horizontal and vertical pouring joints can be made in various places on the structure. When pouring concrete for beams, it is common to create pouring formwork using wire mesh or cut plywood, but as this needs to be processed on-site to match the reinforcement arrangement, assembly and disassembly takes time and effort. Patent Document 1 describes how using hollow materials in the pouring formwork makes it easier to control the temperature when curing the poured concrete, improving the quality of the structure, but does not mention the problems that occur when pouring concrete as described above.

It is difficult to completely prevent sludge from leaking through gaps in lath formwork or loose board formwork, and if sludge or laitance remains, it can form a weak surface (layer) and become a structural weakness. Such defects in the joints can cause water leakage and accidents in which the concrete at the bottom of the beams spalls off, causing problems with the quality of the structure. Patent Document 2 discloses a partition for joint construction that has through holes that match the reinforcement. It is thought that the use of such partitions can reduce the effort required to place partitions for joint construction, but since there is always a gap between the through holes and the reinforcement, it is difficult to completely prevent sludge from leaking, as mentioned above.

Patent Document 3 describes using a thermoplastic material as the formwork material, but because the shape is formed by pouring, it is difficult to apply this to pouring formwork that does not have a base material.

JP 2018-3355 A JP 2015-158073 A JP 2000-185310 A

The present invention aims to provide a method for constructing joint formwork that can solve the above problems, prevent slag leakage from joint surfaces, and reduce the labor required for installing and assembling the joint formwork, as well as a method for constructing concrete members using this construction method.

The construction method of the joint formwork according to the present invention for achieving the above-mentioned object is a construction method of the joint formwork installed in the joint of the concrete member, and is characterized by having a heating process for softening a thermoplastic material that hardens at a temperature equal to or lower than the temperature generated in the vicinity of the joint formwork when curing the concrete after pouring, and a shape forming process for forming a shape that conforms to the forming surface of the concrete member by stacking the softened thermoplastic material along a backing plate arranged along the desired shape.

In addition, in the construction method of the joint formwork having the above-mentioned characteristics, the thermoplastic material is laminated adjacent to the general formwork material, and the joint formwork is constructed by combining the thermoplastic material and the general formwork material. By having such characteristics, it is possible to construct the joint formwork in a short time compared to constructing the joint formwork with thermoplastic material alone.

Furthermore, in the construction method for a joint formwork having the above-mentioned characteristics, the thermoplastic material is arranged in layers around the reinforcement that penetrates the joint formwork. By having such characteristics, it is possible to efficiently seal areas where sludge leakage is predicted.

The method for constructing a concrete member to achieve the above-mentioned objective is characterized by having a pouring process for pouring concrete into a mold area including a joint formwork constructed using the above-mentioned joint formwork construction method, and a demolding process for softening the thermoplastic material by heating the joint formwork after the concrete has hardened and demolding it.

The construction method for joint formwork with the above-mentioned characteristics can prevent slag leakage from the joint surface and improve the quality of the structure. It can also reduce the labor required for installing and assembling the joint formwork.

In addition, the method for constructing concrete members with the above-mentioned characteristics can prevent spalling caused by slag leakage from the joint surface, improving the quality of the product.

This is an oblique view of the state in which a pouring formwork is placed on the formwork used to construct a beam. This is a side view of the formwork used to construct a beam with a pouring formwork placed on it. FIG. 13 is a diagram showing the initial state in which thermoplastic material is laminated from the bottom form using a backing plate. FIG. 13 shows the intermediate stage in which thermoplastic material is layered from the bottom form using a backing plate. This is a diagram showing the state in which concrete has been poured into an area partitioned off by a pouring formwork. This is a diagram showing the state after the pouring formwork made of thermoplastic material has been removed. This is a diagram showing how concrete is poured while a pouring formwork made of thermoplastic material is supported by wooden supports. FIG. 1 is a diagram showing the process of pouring concrete while a pouring formwork made of thermoplastic material is supported by a supporting material made of steel bars. FIG. 13 is a diagram showing an example of placing thermoplastic material along a scrap board to form a joint formwork. This is a diagram showing the state in which thermoplastic material is layered in the lower reinforcement portion when a pouring formwork is constructed by combining thermoplastic material and general formwork material. This figure shows the state in which a general formwork material is placed on top of a layered thermoplastic material when a pouring joint formwork is constructed by combining thermoplastic material and general formwork material. This is a diagram showing the state in which thermoplastic material is layered in the upper reinforcement portion when a pouring formwork is constructed by combining thermoplastic material and general formwork material.

Below, the embodiment of the present invention relating to the construction method of the joint formwork and the construction method of the concrete member will be described in detail with reference to the drawings. Note that the embodiment shown below will be an example of the joint formwork used when constructing a beam.

[First embodiment]
First, a construction method of the joint formwork according to the first embodiment and a construction method of a concrete member will be described with reference to Fig. 1 to Fig. 6. Fig. 1 is a perspective view of the joint formwork placed on the formwork for constructing a beam, and Fig. 2 is a side view of the same. Fig. 3 is a view showing the initial state in which thermoplastic material is layered from the bottom formwork using a backing plate, and Fig. 4 is a view showing the intermediate state. Fig. 5 shows the state in which concrete has been poured, and Fig. 6 is a view showing the state in which the joint formwork made of thermoplastic material has been removed (removed from the formwork).

The joint formwork 10 according to this embodiment is a formwork placed in a formwork covered by a bottom formwork 54 and a sidewall formwork 56 arranged around the main reinforcement 50 and rib reinforcement 52 that constitute the beam, and other reinforcement (e.g., abdominal reinforcement (not shown)) as shown in FIG. 1. The joint formwork 10 according to this embodiment is made of a thermoplastic material and is arranged in a formwork covered by the bottom formwork 54 and the sidewall formwork 56 so as to form a wall surface through which reinforcement such as the main reinforcement 50 penetrates. Below, a construction method for the joint formwork 10 configured in this way and a construction method for a concrete member 58 (see FIG. 6) using the joint formwork 10 constructed by this construction method will be described.

[Heating process]
First, the thermoplastic material 12 is heated to soften it. The softening temperature of the thermoplastic material 12 may be any temperature that hardens at or below the temperature that occurs in the vicinity of the joint formwork 10 when curing the poured concrete 58a (see FIG. 5). The softening may be a hardness that allows the material to easily deform when a force is applied while maintaining a three-dimensional shape by itself. The softening temperature may be appropriately controlled according to the characteristics of the thermoplastic material 12.

Thermoplastic materials 12 include thermoplastic resins such as polyamide (PA), polycarbonate (PC), polypropylene (PP), EVA resin (EVAC), and PET resin (PET), which have a relatively high hardness when cured, as well as thermoplastic elastomers that retain elasticity even when cured (e.g., styrene-based (ABC), olefin-based (TPO), polyvinyl chloride-based (TPVC), and urethane-based (PU)). Specific examples of commercially available products include T-Fab Works' Hand-Made Plastic, JXE JXO's Hand-Made Plastic Oyumaru, workplus's Soft Plastic, and Pipit's Free Craft Hardening Plastic.

[Shape forming process]
Next, the softened thermoplastic material 12 is layered to form the joint formwork 10. The thermoplastic material 12 is layered along the plate surface of the backing plate 14 arranged on the side where the concrete 58a is poured, as shown in Figs. 3 and 4. Specifically, as shown in Fig. 3, the backing plate 14 is first arranged, and the softened thermoplastic material 12 is arranged along the bottom formwork 54 and the backing plate 14. In addition, the thermoplastic material 12 is arranged so as to be in close contact with the side wall formwork 56 at both ends in the width direction. This makes it possible to prevent the bottom formwork 54 and the side wall formwork 56 from being in close contact with the thermoplastic material 12, and to prevent gaps from occurring at the bottom and sides of the joint formwork 10. This makes it possible to prevent slag leakage from the gaps.

In the same way, the thermoplastic material 12 is stacked on top of the thermoplastic material 12 placed in the lower tier, so as to follow the plate surface of the backing plate 14. In this way, the thermoplastic material 12 is stacked up to the height required for the joint formwork 10 to form the joint formwork 10. If the height of the backing plate 14 is insufficient, the position of the backing plate 14 can be shifted upward as shown in Figure 4. By reducing the width (height) of the backing plate 14, the area of close contact with the thermoplastic material 12 is reduced, making it possible to peel it off from the thermoplastic material 12 with less force.

[Pouring process]
After constructing the joint formwork 10 using the thermoplastic material 12, concrete 58a is poured into the area on the side where the backing plate 14 has been placed and the surface has been exposed, i.e., the mold area including the joint formwork 10 (see Figure 5).

[Mold removal process]
After the poured concrete 58a hardens, the joint formwork 10 is heated and removed. The joint formwork 10 according to the present embodiment is made of thermoplastic material 12, and therefore softens when heated, and the intimate contact with the surface of the concrete member 58 is eliminated, making it possible to easily remove the formwork.

[Action and Effects]
When the joint formwork 10 is constructed in this manner, the thermoplastic material 12 constituting the joint formwork 10 can be in close contact with the bottom formwork 54, the side wall formwork 56, and the reinforcement such as the main reinforcement 50. This prevents slag from leaking from the joint surface. This improves the quality of the constructed concrete member 58 (the quality of the building frame). Furthermore, since there is no need to drill holes or adjust the formwork material, the labor required for installation and assembly of the joint formwork 10 can be reduced. In addition, the thermoplastic material 12 can be softened and melted by heating, so it can be reused as a formwork material.

[Application example]
In the above embodiment, the joint formwork 10 is described as having walls made of a single thermoplastic material 12, which is used as a formwork. However, if the filling pressure when pouring the concrete 58a is high, a support material 16 made of wood or the like may be arranged to support the joint formwork 10 made of the thermoplastic material 12, as shown in Fig. 7. It goes without saying that the support material 16 may be made of a material other than wood, such as reinforcing bars, as shown in Fig. 8.

When stacking the thermoplastic material 12, as shown in FIG. 9, a scrap board 18 may be placed on the opposite side of the backing board 14 through the thermoplastic material 12, and the thermoplastic material 12 may be stacked between the backing board 14 and the scrap board 18. By adopting such a method, the thermoplastic material 12 can be stacked efficiently and the thickness of the pouring formwork 10 can be made uniform.

In the above embodiment, the side surface of the joint formwork 10 on which the concrete 58a is poured is shown as being flat. However, unevenness may be provided on the contact surface of the backing plate 14 with the thermoplastic material 12, so that the side surface on which the concrete is poured of the joint formwork 10, which is formed by arranging the thermoplastic material 12 in a layered manner, has unevenness.

In addition, since the thermoplastic material 12 softens when heated, after constructing the joint formwork 10, it may be partially softened by reheating, and the pouring side surface may be processed. Specifically, an uneven surface is formed by pressing an uneven plate against it or by using a comb or the like to pull it. By forming an uneven surface on the pouring side surface of the joint formwork 10, unevenness appears on the pouring surface of the concrete member 58. This makes it possible to prevent poor joints.

[Second embodiment]
Next, a construction method for a joint formwork according to the second embodiment will be described with reference to Fig. 10 to Fig. 12. The construction method for a joint formwork according to this embodiment has the same basic steps as the construction method according to the first embodiment.

The construction method according to this embodiment differs from the construction method according to the above embodiment in that a pouring formwork 10 is constructed by combining a thermoplastic material 12 with a general formwork material 20. Here, the general formwork material 20 is basically a plate-like material such as a loose plate, and also includes a lath net and an air fence.

In the construction method of the joint formwork 10 according to this embodiment, in the shape forming process in which the thermoplastic material 12 is layered, the general formwork material 20 is placed in the part other than the part where the main reinforcement 50 and other reinforcing bars penetrate. That is, as shown in FIG. 10, the thermoplastic material 12 is layered using the backing plate 14 as a guide. After the thermoplastic material 12 is layered up to the position where there is no reinforcing bar such as the main reinforcement 50, the general formwork material 20 is placed on top of the thermoplastic material 12 as shown in FIG. 11. Here, it is preferable to arrange the thermoplastic material 12 so that no gap is generated between the general formwork material 20 and the thermoplastic material 12 at the end of the general formwork material 20. Furthermore, in the part where the reinforcing bar such as the main reinforcement 50 exists, the thermoplastic material 12 is layered on top of the general formwork material 20 as shown in FIG. 12, so that no gap is generated between the reinforcing bar and the thermoplastic material 12, thereby forming the joint formwork 10. Although not shown in the figure, it is also desirable to place thermoplastic material 12 in the area adjacent to the side wall formwork 56 and the general formwork material 20.

When this method is adopted, the general formwork material 20 and the thermoplastic material 12 can be placed adjacent to each other in a close contact state. This makes it possible to prevent gaps from occurring between the two. In addition, the thermoplastic material 12 is placed in the area where the main reinforcement bars 50 and other reinforcing bars penetrate the joint formwork 10, making it possible to create a state in close contact with the reinforcing bars. This makes it possible to prevent slag leakage from the penetration areas of the reinforcing bars and adjacent areas.

In addition, by using plate-shaped general formwork material 20, the effort of stacking thermoplastic material 12 can be eliminated, making it possible to reduce the effort and time required to construct joint formwork 10. It goes without saying that even when this method is adopted, support material 16 (see Figures 7 and 8) and scrap boards 18 (see Figure 9) can be used.

When the joint formwork 10 is constructed by combining the general formwork material 20 and the thermoplastic material 12, the thermoplastic material 12 may be placed only around the reinforcement that penetrates the joint formwork 10. This is because, when such a method is adopted, it is possible to efficiently seal areas where leakage of concrete 58a is expected.

In the above embodiment, the construction method for joint formwork is applied to the case of forming beams. However, the construction method for joint formwork according to the present invention can be applied to all reinforced concrete members in which joints are formed. Therefore, the application also includes slabs and wall surfaces.

10: Casting formwork, 12: Thermoplastic material, 14: Backing plate, 16: Support material, 18: Backing plate, 20: General formwork material, 50: Main reinforcement, 52: Ribs, 54: Bottom formwork, 56: Side wall formwork, 58: Concrete member, 58a: Concrete.

Claims (4)

A method for constructing a joint formwork installed at a joint of a concrete member, comprising:
A heating step of softening a thermoplastic material that hardens at a temperature equal to or lower than the temperature generated in the vicinity of the joint formwork when curing concrete after pouring;
and a shape forming process in which the softened thermoplastic material is layered along a backing plate arranged along the desired shape to form a shape that conforms to the forming surface of the concrete member. The construction method for joint formwork described in claim 1, characterized in that the thermoplastic material is laminated adjacent to the general formwork material, and the joint formwork is constructed by combining the thermoplastic material and the general formwork material. The construction method for a joint formwork according to claim 2, characterized in that the thermoplastic material is layered around the reinforcement that penetrates the joint formwork. A pouring step of pouring concrete into a mold area including a pouring formwork constructed using the construction method for a pouring formwork according to any one of claims 1 to 3;
A method for constructing a concrete member, comprising: a demolding process in which, after the concrete has hardened, the thermoplastic material is softened and demolded by heating the pouring formwork.

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