Jig and molding method of precast concrete member

Abstract

To provide a jig in which molding defects are hard to be generated when forming a steel bar insertion hole, and a molding method of a precast concrete member.SOLUTION: A jig 20 is arranged in a mold into which concrete is placed, and forms a steel bar insertion hole into which a steel bar is inserted at an end surface of a precast concrete member. The jig 20 includes: a bag-shaped member 22 becoming a bar-like shape forming the steel bar insertion hole in a bulged state where air is injected to allow it to be pulled out from the steel bar insertion hole in a state where air is released; and a hook part (concave-convex part 30A) formed projecting outside of an outer peripheral part of the bag-like member 22 in at least a part of the outer peripheral part.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a jig and a method for molding a precast concrete member.

Background Art

[0002] Patent Document 1 below describes a technique for producing a formwork material for a reinforcing bar insertion hole using a synthetic resin flexible electric wire conduit, and forming a reinforcing bar insertion hole having unevenness corresponding to the unevenness of the synthetic resin flexible electric wire conduit on the inner peripheral surface of a precast member.

Prior Art Document

Patent Document

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The synthetic resin flexible electric wire conduit shown in Patent Document 1 above can be removed from the precast member by making a cut. However, if such a cut is provided, there is a risk that uncured concrete may penetrate into the inside of the synthetic resin flexible electric wire conduit from the cut. In such a case, molding defects of the precast member may occur.

[0005] In consideration of the above facts, an object of the present invention is to provide a jig and a method for molding a precast concrete member in which molding defects are less likely to occur when forming a reinforcing bar insertion hole.

Means for Solving the Problems

[0006] The jig according to claim 1 is disposed within a formwork into which concrete is placed, and is a jig for forming a reinforcing bar insertion hole into which a reinforcing bar is inserted in an end face of a precast concrete member. The jig has a rod-like shape that forms the reinforcing bar insertion hole in a state where air is injected and inflated, and a bag-shaped member that can be extracted from the reinforcing bar insertion hole in a state where air is removed. The jig further includes a hooking portion formed to protrude outward from the outer peripheral portion of the bag-shaped member at at least a part of the outer peripheral portion thereof.

[0007] The jig according to claim 1 is disposed within a formwork into which concrete is placed. After the concrete hardens and the reinforcing bar insertion hole is formed, air is discharged from the bag-shaped member to reduce the volume, so that the jig can be extracted from the reinforcing bar insertion hole. Thereby, the jig can be reused. For this reason, the number of members for forming the precast concrete member is reduced as compared with the case where a sheath pipe is used to form the reinforcing bar insertion hole.

[0008] In addition, since the bag-shaped member is disposed in the concrete in a state where air is injected and inflated, concrete does not flow into the inside of the bag-shaped member. For this reason, it is difficult to cause molding defects in the precast concrete member.

[0009] Further, the bag-shaped member is formed with a hooking portion that protrudes outward from the outer peripheral portion. Thereby, as compared with the case of forming a reinforcing bar insertion hole having the same hole diameter over the entire length, the adhesion strength and the shear strength between the grout filled after inserting the reinforcing bar into the reinforcing bar insertion hole and the precast concrete member are increased.

[0010] The jig according to claim 2 is the jig according to claim 1, wherein the hooking portion includes uneven portions formed over the outer peripheral portion.

[0011] According to the jig of claim 2, uneven portions are formed over the outer peripheral portion of the bag-shaped member. For this reason, concave portions are formed over the inner wall of the reinforcing bar insertion hole. Thereby, as compared with the case of using a jig in which an emboss is formed only on a part of the outer peripheral portion, the adhesion strength between the grout and the concrete is increased.

[0012] The jig according to claim 3 is the jig according to claim 2, wherein the engaging portion includes a diameter-expanded portion where the outer peripheral portion expands in diameter toward the tip or the rear end, a protrusion formed on the outer peripheral portion and having a larger protruding width than the uneven portion, or a spiral ridge formed on the outer peripheral portion.

[0013] According to the jig of claim 3, uneven portions are formed across the outer peripheral portion of the bag body. Further, a diameter-expanded portion, a protrusion, or a ridge is formed on the outer peripheral portion. Thereby, compared with the case where only uneven portions are formed, the adhesion strength between the grout and the concrete is increased.

[0014] The jig according to claim 4 is the jig according to claim 1, wherein the bag-shaped member is formed in a cylindrical shape having a hollow portion, and includes a core material that can be fixed to a formwork for forming the precast concrete member in a state of being inserted into the hollow portion.

[0015] According to the jig of claim 4, a core material is inserted into the hollow portion of the bag-shaped member. This core material can be fixed to a formwork for forming precast concrete. Thereby, it is possible to prevent the bag-shaped member from being deformed or displaced due to the pressure of the precast concrete before curing.

[0016] The jig according to claim 5 is the jig according to claim 1, and includes a sheath tube that can be fixed to a formwork for forming the precast concrete member in a state where the other end portion of the bag-shaped member is inserted.

[0017] According to the grout filling hole forming jig of claim 5, the other end portion of the bag body is inserted into the sheath tube, and this sheath tube is fixed to a formwork for forming precast concrete. Thereby, it is possible to prevent the bag-shaped member from being displaced due to the pressure of the precast concrete before curing.

[0018] The method for forming a precast concrete member according to claim 6 includes a step of injecting air into the bag-shaped member according to claim 1, a step of placing the bag-shaped member filled with air in a mold for forming a precast concrete member with one end protruding, a step of placing concrete in the mold, and a step of discharging air from the bag-shaped member and removing the jig after the concrete has hardened.

[0019] In the method for forming a precast concrete member according to claim 6, a jig is placed in the mold into which the concrete is placed. After the concrete has hardened and a reinforcing bar insertion hole is formed, air is discharged from the bag-shaped member to reduce its volume, so that it can be withdrawn from the reinforcing bar insertion hole. As a result, the jig can be reused. Therefore, compared with the case of forming a reinforcing bar insertion hole using a sheath pipe, the number of members for forming the precast concrete member is reduced.

[0020] In addition, since the bag-shaped member is placed in the concrete in a state where air is injected and it is inflated, concrete does not flow into the inside of the bag-shaped member. Therefore, it is difficult for molding defects to occur in the precast concrete member.

[0021] In addition, a hook portion protruding outward from the outer peripheral portion is formed on the bag-shaped member. As a result, compared with the case of forming a reinforcing bar insertion hole having the same hole diameter over the entire length, the adhesion strength and shear strength between the grout filled after inserting the reinforcing bar into the reinforcing bar insertion hole and the precast concrete member are increased.

Advantages of the Invention

[0022] According to the present invention, molding defects are less likely to occur when forming a reinforcing bar insertion hole.

Brief Description of the Drawings

[0023]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Best Mode for Carrying Out the Invention

[0024] Hereinafter, a jig and a method for molding a precast concrete member according to an embodiment of the present invention will be described with reference to the drawings. Components denoted by the same reference numerals in each drawing mean the same components. However, unless otherwise specified in the specification, each component is not limited to one, and a plurality of components may exist.

[0025] In addition, descriptions of overlapping configurations and reference numerals in each drawing may be omitted. Note that the present disclosure is not limited to the following embodiments, and appropriate changes can be made and implemented, such as omitting configurations, replacing them with different configurations, and combining one embodiment and various modification examples within the scope of the object of the present disclosure.

[0026] <Precast Concrete Member> 1(A) and 1(B) show an overview of a precast concrete member 10B having a reinforcing bar insertion hole 14B and a precast concrete member 10C having a reinforcing bar insertion hole 14C, which are formed using a jig 20 (see FIG. 2) according to an embodiment of the present invention.

[0027] As shown in FIG. 1(A), a reinforcing bar 12 protruding from a precast concrete member 10A is inserted into a reinforcing bar insertion hole 14B of a precast concrete member 10B. The reinforcing bar insertion hole 14B is a bottomed hole, and in a state where the reinforcing bar 12 is inserted, a grout material is filled inside.

[0028] Also, as shown in FIG. 1(B), the reinforcing bar 12 protruding from the precast concrete member 10A can also be inserted through a reinforcing bar insertion hole 14C of the precast concrete member 10C. The reinforcing bar insertion hole 14C is a through hole, and in a state where the reinforcing bar 12 is inserted therethrough, a grout material is filled inside.

[0029] In FIGS. 1 to 3, illustration is omitted and will be described in detail later. At least a part of the inner circumferential surfaces of the reinforcing bar insertion holes 14B and 14C are formed with engaging portions that protrude outward from the inner circumferential surface. The engaging portions are recesses in the concrete and are formed by the uneven portions 30A, 30B (see FIG. 4), the diameter-expanded portions 40A to 40C, the protrusions 42A, 42B, and the protrusion strips 42C (see FIG. 5) of the jig 20.

[0030] <Jig> The jig 20 shown in FIG. 2 includes a bag-shaped member 22 and a valve 24. The bag-shaped member 22 is formed using a flexible material. The bag-shaped member 22 has, for example, a three-layer structure and includes an inner layer formed using a urethane-based material, a middle layer formed using a stretch-preventing material such as nylon strong yarn, and an outer layer formed using a tarpaulin with a strong yarn specification that is difficult for concrete to adhere to.

[0031] The valve 24 is formed at the end of the bag-shaped member 22. Air can be injected into the bag-shaped member 22 from the valve 24 using an air gun or the like. As a result, the bag-shaped member 22 expands and becomes a rod-shaped (cylindrical) shape that forms the reinforcing bar insertion holes 14B and 14C shown in FIG. 1.

[0032] Also, by rotating the valve, air can be discharged from the inside of the bag-shaped member 22. The bag-shaped member 22 deforms in a state where the air is removed and can be removed from the reinforcing bar insertion holes 14B and 14C.

[0033] Note that the jig 20 is a general term for the jigs 20A and 20B described later. When there is no need for particular distinction, these are referred to as the jig 20.

[0034] Aspects of forming the precast concrete member 10B having the bottomed reinforcing bar insertion hole 14B (see FIG. 1) are shown in FIGS. 3(A) and (C). In this aspect, the end portion (the end portion opposite to the valve 24) of the jig 20A is disposed inside the mold 30.

[0035] In the example shown in Fig. 3(A), an opening 30H is formed in the lower end surface of the formwork 30, and the jig 20A is inserted through this opening 30H for positioning. In this case, the valve 24 is disposed below the formwork 30.

[0036] On the other hand, in the example shown in Fig. 3(C), the jig 20A is held at the upper part of the formwork 30. In this case, the positioning member 32 is used. The positioning member 32 is provided with an opening 32H, and the jig 20A is inserted through this opening 32H for positioning. In this case, the valve 24 is disposed above the formwork 30.

[0037] Also, embodiments of forming the precast concrete member 10B provided with the reinforcing bar insertion hole 14C (see Fig. 1(B)), which is a through hole, are shown in Figs. 3(B) and (D). In this embodiment, the end portion (the end portion on the side opposite to the valve 24) of the jig 20 is disposed outside the formwork 30.

[0038] In the example shown in Fig. 3(B), an opening 30H is formed in the lower end surface of the formwork 30, and the jig 20B is inserted through this opening 30H for positioning. Although this figure shows an example in which the valve 24 is disposed below the formwork 30, as shown in Fig. 3(D), the valve 24 may be disposed above the formwork 30. Also, in the examples shown in Figs. 3(B) and (D), the positioning member 32 can be used.

[0039] In addition, when forming the precast concrete member 10B provided with the reinforcing bar insertion hole 14C (see Fig. 1(B)), which is a through hole, valves 24 may be formed at both end portions of the jig 20.

[0040] (Hooking portion) At least a part of the outer peripheral portion of the bag-shaped member 22 is formed with a hooking portion that protrudes outward from the outer peripheral portion. As an example, as shown in Fig. 4(A), the bag-shaped member 22 is formed with uneven portions 30A as hooking portions across the outer peripheral portion. The uneven portions 30A are embossed portions formed in the material forming the bag-shaped member 22, and are formed, for example, by thick and thin portions of the thickness of the tarpaulin forming the outer layer.

[0041] In addition, as shown in FIG. 4(B), uneven portions 30B with a constant thickness of the material forming the bag-shaped member 22 may be formed.

[0042] Further, as shown in FIGS. 5(A) to 5(C), the bag-shaped member 22 may have enlarged-diameter portions 40A to 40C formed on the outer peripheral portion as engaging portions.

[0043] The enlarged-diameter portion 40A in FIG. 5(A) is formed across the longitudinal direction of the bag-shaped member 22 and is a portion where the diameter gradually increases toward the valve 24 side. In other words, the bag-shaped member 22 has a tapered shape from the valve 24 side toward the opposite end.

[0044] The enlarged-diameter portion 40B in FIG. 5(B) is formed across the longitudinal direction of the bag-shaped member 22 and is a portion where the diameter gradually decreases toward the valve 24 side. In other words, the bag-shaped member 22 has a tapered shape from the end opposite to the valve 24 toward the valve 24 side.

[0045] The enlarged-diameter portion 40C in FIG. 5(C) is formed at the central portion in the longitudinal direction of the bag-shaped member 22 and is a portion where the diameter gradually increases toward the valve 24 side. Although not shown, the enlarged-diameter portion 40C may be formed such that the diameter gradually increases toward the side opposite to the valve 24. Further, the enlarged-diameter portion 40C may be provided at a portion other than the central portion in the longitudinal direction of the bag-shaped member 22, or a plurality of enlarged-diameter portions 40C may be provided in the longitudinal direction of the bag-shaped member 22.

[0046] Further, as shown in FIGS. 6(A) to 6(C), the bag-shaped member 22 may have protrusions 42A, 42B and ridges 42C formed on the outer peripheral portion as engaging portions.

[0047] The protrusion 42A in FIG. 6(A) is a spherical portion formed in plurality in the longitudinal direction of the bag-shaped member 22. Only one protrusion 42A may be provided. The protrusion 42B in FIG. 6(B) is a spherical portion formed in plurality so as to cover the surface of the bag-shaped member 22. The ridge 42C in FIG. 6(C) is a portion formed in a spiral shape on the surface of the bag-shaped member 22.

[0048] The protruding widths of the diameter-expanded portions 40A to 40C, the protrusions 42A and 42B, and the rib 42C are larger than the protruding widths of the uneven portions 30A and 30B. Further, the diameter-expanded portions 40A to 40C, the protrusions 42A and 42B, and the rib 42C can be used in combination with the uneven portion 30A or 30B. As an example, FIG. 7 shows an enlarged partial cross-sectional view of a portion in which the uneven portion 30A and the protrusion 42A are combined.

[0049] When providing the uneven portion 30A or 30B, it is not necessary to form the diameter-expanded portions 40A to 40C, the protrusions 42A and 42B, and the rib 42C. On the other hand, when providing the diameter-expanded portions 40A to 40C, the protrusions 42A and 42B, and the rib 42C, it is not necessary to form the uneven portion 30A or 30B.

[0050] <Method for molding a precast concrete member> When molding the precast concrete member 10B or 10C shown in FIG. 1 using the jig 20, first, air is injected into the inside of the jig 20 to mold the bag-shaped member 22 into a rod shape.

[0051] Then, as shown in FIG. 3, the bag-shaped member 22 filled with air is disposed in the mold 30. At this time, the bag-shaped member 22 is disposed in a state where the end portion on the valve 24 side protrudes from the mold 30. Note that air may be injected into the inside of the bag-shaped member 22 after the bag-shaped member 22 is disposed in the mold 30.

[0052] Next, concrete is placed in the mold 30. After the concrete hardens, air is discharged from the bag-shaped member 22 and the jig 20 is removed. Thereby, the precast concrete member 10B or 10C is molded.

[0053] <Function and effect> As shown in Fig. 3, the jig 20 is disposed within the formwork 30 into which concrete is placed. After the concrete hardens and the reinforcing bar insertion holes 14B or 14C are formed, air is evacuated to reduce the volume of the bag-shaped member 22. Thereby, the jig 20 can be withdrawn from the reinforcing bar insertion holes 14B or 14C. This jig 20 can be reused. For this reason, compared with the case of forming the reinforcing bar insertion holes using sheath pipes, the number of members for forming the precast concrete members 10B or 10C is reduced.

[0054] Further, since the bag-shaped member 22 is disposed within the concrete in a state where air is injected and inflated, concrete does not flow into the interior of the bag-shaped member 22. For this reason, it is difficult for molding defects to occur in the precast concrete members 10B or 10C.

[0055] Further, the bag-shaped member 22 is formed with engaging portions that protrude to the outside of the outer peripheral portion, such as uneven portions 30A, 30B (see Fig. 4), diameter-expanded portions 40A to 40C, protrusions 42A, 42B, and ridges 42C (see Fig. 5).

[0056] Thereby, compared with the case where there are no engaging portions, that is, when forming reinforcing bar insertion holes having the same hole diameter over the entire length, the adhesion strength and shear strength between the grout filled into the reinforcing bar insertion holes 14B or 14C and the precast concrete members 10B or 10C are increased.

[0057] Further, as shown in Fig. 4, the jig 20 is formed with uneven portions 30A or 30B over the outer peripheral portion of the bag-shaped member 22. For this reason, recesses are formed over the inner wall in the reinforcing bar insertion holes 14B or 14C shown in Fig. 1. Thereby, compared with the case of using a jig in which an emboss is formed only on a part of the outer peripheral portion, the adhesion strength between the grout and the concrete is enhanced.

[0058] Furthermore, the jig 20 is formed with diameter-expanded portions 40A to 40C, protrusions 42A, 42B, and ridges 42C (see Fig. 5). Thereby, compared with the case where only the uneven portions 30A or 30B are formed, the adhesion strength between the grout and the concrete is enhanced.

[0059] <Other Embodiments> As shown in FIG. 8(A), the bag-shaped member 22 may be formed in a tubular shape having a hollow portion 26. The hollow portion 26 is formed across the longitudinal direction of the bag-shaped member 22 and is formed to penetrate between the ends of the bag-shaped member 22. In this case, as shown in FIG. 8(B), a core material 50 made of metal, wood, resin, or the like is inserted into the hollow portion 26 and used.

[0060] By using the core material 50 in this way, as shown in FIG. 9(A), when the jig 20B is arranged on the formwork 30, it is possible to suppress the deformation and displacement of the jig 20B due to the pressure of the concrete before curing. An opening 30H is formed in the lower end surface of the formwork 30, and the jig 20B is inserted through this opening 30H for positioning.

[0061] Also, a positioning member 32 may be arranged above the formwork 30. The positioning member 32 is provided with an opening 32H, and the core material 50 or the jig 20A is inserted through this opening 32H for positioning.

[0062] According to such an aspect, the core material 50 can be used for forming the precast concrete member 10C (see FIG. 1) provided with the reinforcing bar insertion hole 14C.

[0063] Note that, like the hollow portion 28 shown in FIGS. 8(B) and 8(C), the hollow portion of the present invention may not penetrate between the ends of the bag-shaped member 22. According to such an aspect, the core material 50 can be used for forming the precast concrete member 10B (see FIG. 1) provided with the reinforcing bar insertion hole 14B.

[0064] Also, as shown in FIG. 10, the jig 20 can also be used in combination with a sheath tube 60. The sheath tube 60 includes a plate-shaped base portion 60A and a tubular sheath portion 60B, and the bag-shaped member 22 is inserted into the sheath portion 60B.

[0065] As shown in Fig. 11, the sheath tube 60 is used by being fitted into the opening 30H of the formwork 30. Thereby, the jig 20 can be positioned inside the formwork 30. Also, it is possible to suppress the displacement of the bag-shaped member 22 due to the pressure of the precast concrete before hardening. Even in such an aspect, the positioning member 32 may be arranged above the formwork 30. Thus, the present invention can be implemented in various aspects.

Explanation of Signs

[0066] 10B Precast concrete member 10C Precast concrete member 12 Reinforcing bar 14B Reinforcing bar insertion hole 14C Reinforcing bar insertion hole 20 Jig 20A Jig 20B Jig 22 Bag-shaped member 26 Hollow part 28 Hollow part 30A Concavo-convex part (hooking part) 30B Concavo-convex part (hooking part) 40A Diameter-expanded part (hooking part) 40B Diameter-expanded part (hooking part) 40C Diameter-expanded part (hooking part) 42A Protrusion (hooking part) 42B Protrusion (hooking part) 42C Ridge (hooking part) 50 Core material 60 Sheath tube

Claims

1. A jig that is disposed within a formwork into which concrete is placed and forms a reinforcing bar insertion hole into which a reinforcing bar is inserted at an end face of a precast concrete member, a bag-shaped member that has a rod-like shape that forms the reinforcing bar insertion hole in a state where air is injected and inflated and can be removed from the reinforcing bar insertion hole in a state where the air is discharged, and a hooking portion formed to protrude outward from the outer peripheral portion at at least a part of the outer peripheral portion of the bag-shaped member, and the jig is provided with these.

2. The hooking portion, includes uneven portions formed across the outer peripheral portion, and the jig according to Claim 1.

3. The hooking portion, includes a diameter-expanded portion where the outer peripheral portion expands in diameter toward the tip or the rear end, a protrusion formed on the outer peripheral portion and having a larger protruding width than the uneven portion, or a spiral ridge formed on the outer peripheral portion, and the jig according to Claim 2.

4. The bag-shaped member is formed in a cylindrical shape having a hollow portion, and is provided with a core material that can be fixed to a formwork for forming the precast concrete member in a state where it is inserted into the hollow portion, and the jig according to Claim 1.

5. is provided with a sheath tube that can be fixed to a formwork for forming the precast concrete member in a state where the other end portion of the bag-shaped member is inserted, and the jig according to Claim 1.

6. A step of injecting air into the bag-shaped member of Claim 1, a step of disposing the bag-shaped member filled with air in a formwork for molding a precast concrete member with one end portion protruding, a step of placing concrete in the formwork, and a step of discharging air from the bag-shaped member and removing the jig after the concrete has hardened, and a method for molding a precast concrete member including these steps.

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