Concrete member construction method and box-cut material

Abstract

This invention provides a method for constructing concrete members that facilitates the creation of recesses on the top surface of concrete. [Solution] When constructing a concrete member, the following steps are performed: attaching a box-shaped member 1 having a slit 11 to the upper chord 21 of the truss reinforcement 2 which is positioned horizontally above the bottom formwork by passing the upper chord 21 through the slit 11; pouring concrete on top of the bottom formwork and embedding a portion of the box-shaped member 1 that does not include the slit 11 into the concrete; and rotating the box-shaped member 1 around the axis of the upper chord 21 so that the slit 11 faces the bottom formwork, and removing the box-shaped member 1 from the concrete and the upper chord 21 to form a recess on the upper surface of the concrete.

Description

Technical Field

[0001] The present invention relates to a method for constructing a concrete member and a void former.

Background Art

[0002] When constructing a concrete member, a recess may be formed by coring out the upper surface of the concrete. While the purposes of this are various, Patent Document 1 describes that when constructing a concrete foundation by separately placing concrete for a base portion and a rising portion above the base portion, a recess is formed on the upper surface of the concrete at the peripheral edge of the base portion for the purpose of hiding the construction joint below the ground line.

[0003] In Patent Document 1, a spacer made of a foamable material is used as a void former for forming a recess on the upper surface of concrete. The spacer is arranged at a position corresponding to the upper surface of the concrete, concrete is placed, and after the concrete is placed, the spacer is removed to form a recess on the upper surface of the concrete.

Prior Art Literature

Patent Literature

[0004]

Patent Document 1

Summary of the Invention

Problem to be Solved by the Invention

[0005] In order to prevent lifting during concrete placing, the spacer of Patent Document 1 is arranged in a compressed state between the formwork and the reinforcing bar, and is fixed between the formwork and the reinforcing bar by its restoring force. When removing the spacer from the concrete, it is necessary to further compress the compressed spacer by, for example, pinching it by hand to peel the spacer off the concrete, which makes removal difficult.

[0006] This invention has been made in view of the above-mentioned problems, and aims to provide a method for constructing concrete members that facilitates the process of forming recesses on the upper surface of concrete. [Means for solving the problem]

[0007] The first invention for solving the above problems is a method for constructing a concrete member, characterized by comprising the steps of: attaching a box-shaped member having a slit to a rod-shaped support member positioned horizontally above a bottom formwork by passing the support member through the slit; pouring concrete on top of the bottom formwork and embedding a portion of the box-shaped member that does not include the slit in the concrete; and rotating the box-shaped member around the axis of the support member so that the slit faces the bottom formwork, and then removing the box-shaped member from the concrete and the support member to form a recess on the upper surface of the concrete.

[0008] In this invention, by passing the support material through the slit of the box-shaped material, the box-shaped material can be easily attached to the support material, and resistance to lifting during concrete pouring can be achieved. Furthermore, after concrete pouring, by rotating the box-shaped material around the axis of the support material so that the slit faces the bottom formwork side, the box-shaped material can be removed from the concrete and support material without compression, making it easy to form a recess on the top surface of the concrete.

[0009] The box-shaped material is preferably made of urethane, the cross-section of the box-shaped material is perfectly circular, and the slit is preferably formed from the outer circumference of the cross-section toward the center. This allows the box-cut material to be easily rotated around the axis of the support material, and also suppresses disturbance of the concrete surface when the box-cut material is rotated. Furthermore, by using easily processable urethane for the box-cut material, it can be manufactured and used in various sizes depending on the application.

[0010] The second invention is a box-cutting material used to form a recess on the upper surface of concrete poured on a bottom formwork, by being attached to a rod-shaped support material positioned laterally above the bottom formwork, and characterized in that it has a slit for passing the support material through. [Effects of the Invention]

[0011] The present invention provides a method for constructing concrete members that facilitates the process of forming recesses on the upper surface of concrete. [Brief explanation of the drawing]

[0012] [Figure 1] A diagram illustrating the construction method of concrete members. [Figure 2] A diagram showing box-cut material 1. [Figure 3] A diagram showing the installation state of box-cut material 1. [Figure 4] A diagram illustrating the removal of box-cut material 1. [Figure 5] An example of using a sphere 10 when constructing a concrete member. [Modes for carrying out the invention]

[0013] Preferred embodiments of the present invention will be described in detail below with reference to the drawings.

[0014] (1. Method of constructing concrete members) Figure 1 is a diagram illustrating a method for constructing a concrete member according to an embodiment of the present invention. In this embodiment, a floor half-precast member is constructed as the concrete member. First, as shown in Figure 1, truss reinforcement bars 2 and reinforcing bars 3 are placed inside the formwork 4, and the box-out member 1 is attached to the truss reinforcement bars 2.

[0015] The truss reinforcement 2 is provided to impart rigidity and the like to the floor half-precast member. The truss reinforcement 2 comprises a top chord member 21, diagonal members 22, and a bottom chord member 23. The top chord member 21 and the bottom chord member 23 are bar-shaped reinforcing bars arranged in a lateral direction, and the diagonal members 22 are reinforcing bars arranged in a triangular wave shape. The "lateral direction" refers to the direction along the top surface of concrete to be placed later, and the top chord member 21 is arranged at a portion above the position where the top surface will be formed. The truss reinforcement 2 has a configuration in which the top chord member 21 and each of the pair of bottom chord members 23 are connected by the diagonal members 22, but the configuration is not limited thereto.

[0016] In the present embodiment, for the purpose of hooking the hook of a crane sling onto the top chord member 21 of the truss reinforcement 2 to lift the floor half-precast member, the box-out member 1 is used to form a recess in the top surface of the concrete below the top chord member 21. This ensures a gap of sufficient size for inserting the hook below the top chord member 21.

[0017] The reinforcing bars 3 are reinforcing reinforcements for reinforcing the floor half-precast member, and are provided in a grid shape.

[0018] FIG. 2 is a view showing the box-out member 1 according to the embodiment of the present invention. As shown in FIG. 2, the box-out member 1 is a short cylindrical member, and a cross section orthogonal to the axial direction thereof (hereinafter simply referred to as cross section) is a perfect circle. The box-out member 1 is made of an elastic resin material. In the present embodiment, easily processable urethane is used for the box-out member 1. The box-out member 1 can be manufactured in various shapes, dimensions, etc., according to application scenarios.

[0019] A slit 11 is provided in the box-out member 1. The slit 11 is formed from the outer periphery of the cross section of the box-out member 1 toward the center thereof.

[0020] Fig. 3(a) is a diagram showing the mounting state of the box-out material 1 along a cross-section of the box-out material 1. The truss reinforcement 2 is arranged above the bottom formwork 41 on which concrete is to be poured, and the top chord 21 thereof functions as a support member for the box-out material 1. The box-out material 1 is attached to the truss reinforcement 2 by passing the top chord 21 through the slit 11. The top chord 21 is arranged at the center of the cross-section of the box-out material 1.

[0021] In the present embodiment, the width W of the slit 11 is slightly smaller than the diameter of the top chord 21. By forming the box-out material 1 from urethane having elasticity, the width W of the slit 11 can be expanded to arrange the top chord 21 at the center of the cross-section of the box-out material 1, and the box-out material 1 can be fixed to the top chord 21 by the restoring force of the slit 11 that tends to return to its original shape.

[0022] The orientation of the slit 11 of the box-out material 1 is determined so as to prevent concrete from entering the slit 11 during concrete pouring described later. In the example of Fig. 3(a), the orientation of the slit 11 is horizontal, but the orientation is not limited thereto. For example, the outer end 111 of the slit 11 may be positioned above the center of the cross-section of the box-out material 1.

[0023] Thereafter, as shown in Fig. 3(b), concrete 5 is poured onto the bottom formwork 41, and a part of the box-out material 1 not including the slit 11 is embedded in the concrete 5. Since the box-out material 1 is attached to the top chord 21 inside the slit 11, it can resist lifting during concrete pouring.

[0024] When the concrete 5 has hardened to a certain extent, as shown in Fig. 4(a), the box-out material 1 is rotated around the axis of the top chord 21 such that the slit 11 faces toward the bottom formwork 41 side. Since the cross-section of the box-out material 1 (the cross-section orthogonal to the axial direction of the top chord 21) is a perfect circle, the box-out material 1 can be rotated easily, and the upper surface of the concrete 5 is not disturbed even after rotation.

[0025] After rotating the box-cut member 1, pull it upward and remove it from the concrete 5 and upper chord member 21 as shown in Figure 4(b). By removing the box-cut member 1, a recess 51 is formed on the upper surface of the concrete 5, and the floor half-precast member is constructed. A hook (not shown) of a crane lifting device can be inserted between the upper chord member 21 and the recess 51, and the hook can be attached to the upper chord member 21 to lift the floor half-precast member upward.

[0026] As described above, in this embodiment, a box-shaped material 1 is used to form a recess 51 on the upper surface of the concrete 5. In this case, by passing the upper chord material 21 through the slit 11, the box-shaped material 1 can be easily attached to the upper chord material 21 to resist the uplift caused by the pouring of the concrete 5.

[0027] One method for forming a recess 51 on the upper surface of the concrete 5 is to place an elastic sphere 10 between the diagonal members 22 of the truss reinforcement 2 while slightly compressing it, as shown in Figure 5, and support it within the truss reinforcement 2 by its restoring force. However, in this case, when removing the sphere 10 to form the recess 51 after the concrete 5 has been poured, it is necessary to further compress the sphere 10 by pinching it by hand and remove it from the outside of the truss reinforcement 2, which is time-consuming. Also, the upper surface of the concrete 5 is easily disturbed, and shaping by plastering or other means is often necessary.

[0028] In contrast, the box-cutting member 1 of this embodiment can be rotated around the axis of the upper chord member 21 to orient the slit 11 toward the bottom formwork 41, and then easily removed from the concrete 5 and the upper chord member 21. Furthermore, because the cross-section of the box-cutting member 1 is perfectly circular, it is easy to rotate the box-cutting member 1, and it does not disturb the top surface of the concrete 5 when it is rotated.

[0029] As described above, the box-cut member 1 of this embodiment is easy to attach to and detach from the upper chord member 21, contributing to labor savings and increased productivity during the construction of concrete members. It also improves the quality of the concrete members. Furthermore, by using easily processable urethane for the box-cut member 1, it can be manufactured and used in various shapes and dimensions depending on the application.

[0030] However, the present invention is not limited to the above embodiments. For example, a release layer may be provided on the surface of the box-cut material 1 in advance to prevent adhesion with the concrete 5. This allows the box-cut material 1 to be easily rotated and removed even after the concrete 5 has hardened, and also facilitates the reuse of the box-cut material 1.

[0031] In this embodiment, the box-cut material 1 is cylindrical, but it may also be spherical or otherwise. Furthermore, if disturbance of the concrete 5 during the rotation of the box-cut material 1 is tolerable, the cross-section of the box-cut material 1 does not necessarily have to be perfectly circular.

[0032] In this embodiment, a resin material such as urethane is used for the box-cut material 1, but other elastic materials such as rubber may be used instead. Also, in cases where it is not necessary to widen the slit 11 when attaching it to the upper chord material 21, the box-cut material 1 may be formed from a hard material such as wood that does not have elasticity.

[0033] Furthermore, although this embodiment describes an example in which the box-cut material 1 is used when constructing a half-precast floor member, the application of the box-cut material 1 is not limited to this. For example, it may be used when constructing half-precast members other than floors, or when constructing concrete members by pouring concrete on-site. The use of the recess 51 is not limited to passing a crane lifting hook through it, as described above, but may also be formed to embed mounting hardware for the base of a handrail or the like in concrete.

[0034] Furthermore, the configuration of the formwork 4 is not limited, and the bottom formwork 41 into which the concrete is poured is also not particularly limited. For example, the bottom formwork 41 may be the existing concrete surface when a concrete member is constructed by pouring more concrete onto the existing concrete surface.

[0035] In this embodiment, the box-shaped member 1 is supported by the upper chord 21 of the truss reinforcement 2, but the support material for the box-shaped member 1 is not particularly limited as long as it is a rod-shaped member that can be passed through the slit 11. For example, the support material may be a temporary rod material provided separately from the reinforcing bars of the concrete member. The width and shape of the slit 11 in the box-shaped member 1 can also be determined according to the cross-section of the support material.

[0036] Preferred embodiments of the present invention have been described above with reference to the attached drawings, but the present invention is not limited to these examples. It will be obvious to those skilled in the art that various modifications or alterations can be conceived within the scope of the technical idea disclosed herein, and these will naturally also fall within the technical scope of the present invention. [Explanation of Symbols]

[0037] 1: Box-cut material 2: Truss reinforcement 3: Reinforcement bars 4: Formwork 5: Concrete 11: Slit 41: Bottom formwork 51: Recess

Claims

1. The process involves attaching a box-shaped support member having a slit to a rod-shaped support member positioned horizontally above the bottom formwork, by passing the support member through the slit, The steps include pouring concrete onto the bottom formwork and embedding a portion of the box-cut material that does not include the slit into the concrete, The process involves rotating the box-cutting material around the axis of the support material so that the slit faces the bottom formwork side, and then removing the box-cutting material from the concrete and the support material to form a recess on the upper surface of the concrete. A method for constructing a concrete member, characterized by having the following features.

2. The aforementioned box-shaped material is formed of urethane, The cross-section of the aforementioned box-cut material is perfectly circular. The method for constructing a concrete member according to claim 1, characterized in that the slit is formed from the outer circumference of the cross-section toward the center.

3. A box-cutting member used to form a recess on the upper surface of concrete poured on the bottom formwork, which is attached to a rod-shaped support member positioned horizontally above the bottom formwork, A box-shaped material characterized by having a slit for passing the aforementioned support material through.

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