Concrete blow-up prevention jig and construction method for vertical step sections using the jig

Abstract

To simplify the work required to prevent concrete from overflowing. [Solution] After pouring ready-mix concrete up to a predetermined top surface height position on the lower part 22 of the step, a jig 5 equipped with a base plate 51, bracing plates 52A, 52B, and connecting members 53A to 53D is installed on the top surface 22a of the lower part 22 of the step. In this state, ready-mix concrete is poured into the construction area T1 of the upper part 21 of the step to pour the ready-mix concrete up to a predetermined top surface height position on the upper part 21 of the step. When a blowing force F2 of the ready-mix concrete acts from the top surface 22a of the lower part 22 to the base plate 51, this blowing force F2 of the ready-mix concrete is converted into a bracing force F4 directed by each bracing plate 52A, 52B toward the inner surfaces of the vertical walls 31, 31 of the formwork 3, thereby preventing the ready-mix concrete from blowing up.

Description

Technical Field

[0001] The present invention relates to a tool for preventing fresh concrete from splashing and a construction method for a rising step portion using the tool. In particular, the present invention relates to a measure for simplifying the work to prevent fresh concrete from splashing during the construction of a rising step portion.

Background Art

[0002] Generally, the foundation of a building such as a house is formed by placing fresh concrete in a formwork. In addition, there is a known foundation having a rising step portion. When constructing this rising step portion, for example, as disclosed in Patent Document 1, a partition plate is attached to the step boundary portion (the boundary portion between the construction range of the lower part of the step and the construction range of the upper part of the step) of the rising step portion in the formwork, and fresh concrete is placed up to the height position of the top end of the lower part of the step. Then, by placing fresh concrete in the construction range of the upper part of the step, the fresh concrete is blocked by the partition plate, and the upper part of the step is formed.

[0003] By the way, in order to place fresh concrete densely in the formwork, it is necessary to vibrate the fresh concrete poured into the formwork using a vibrator or the like. FIG. 7 is a view seen from a direction along the width direction of the foundation in a state where vibration is being applied using a vibrator b during the construction of the upper part a of the step.

[0004] When vibration is applied using vibrator b in this manner, the still-insufficiently hardened fresh concrete c becomes fluid and flows beyond the partition plate d into the construction area of ​​the lower part of the step e, potentially causing the fresh concrete c to blow up at the top surface e1 of the lower part of the step e (indicated by the symbol f in Figure 7). If this blow-up f occurs, the excess fresh concrete that has blown up must be scooped up and disposed of as a subsequent treatment. In other words, the scooped-up fresh concrete must be moved to another location or disposed of. This increases the labor required to construct the rising step section and leads to increased construction costs. Furthermore, if compaction using vibrator b is not performed sufficiently due to concerns about the fresh concrete blowing up, quality defects such as honeycombing and cold joints may occur. Thus, suppressing the blow-up of fresh concrete and suppressing quality defects are inversely related.

[0005] Furthermore, the aforementioned bloating of ready-mix concrete can occur not only when constructing the stepped sections of a building's foundation, but also in various other construction projects involving stepped sections, such as the construction of walls with stepped sections in reinforced concrete (RC) buildings, or the construction of fences with stepped sections in the exterior of houses.

[0006] Patent Document 2 proposes measures to prevent the blow-up of ready-mix concrete. Patent Document 2 discloses a partitioning device comprising a partitioning member and a suppressing member. The partitioning member has a mounting portion attached to the upper end of the formwork, and a flat plate-shaped partitioning portion that extends downward from the mounting portion and whose main surface widens in a direction perpendicular to the inner surface of the formwork to partition the upper part inside the formwork. The suppressing member has a mounting portion attached to the upper end of the formwork, a connecting portion that extends downward from the mounting portion, and a flat plate-shaped suppressing portion that extends horizontally from the lower end of the connecting portion. By attaching the suppressing member to the upper end of the formwork so that the suppressing portion is at the height of the top surface below the step, the blow-up of ready-mix concrete is suppressed by the suppressing portion of the suppressing member. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2002-97790 [Patent Document 2] Japanese Patent Publication No. 2023-1675 [Overview of the project] [Problems that the invention aims to solve]

[0008] In the partition device disclosed in Patent Document 2, the restraining member is attached to the upper end of the formwork (for example, by means of bolts), so work is required for attachment and removal. Therefore, there is room for improvement in order to simplify the work to prevent the blowing up of fresh concrete and shorten the working time.

[0009] The present invention has been made in view of the above, and its purpose is to provide a ready-mix concrete blow-up prevention jig that can simplify the work required to prevent ready-mix concrete from blowing up, and a method for constructing a raised step section using the jig. [Means for solving the problem]

[0010] The present invention provides a solution for achieving the above objectives, which is a jig for preventing the upflow of ready-mixed concrete used when constructing a raised step section having a lower step section and an upper step section with different top surface heights, and after pouring ready-mixed concrete up to a predetermined top surface height position of the lower step section, pouring ready-mixed concrete into the construction area of ​​the upper step section separated by a partition plate. Furthermore, this ready-mix concrete blow-up prevention jig comprises a base plate installed on the top surface of the lower part of the step at the boundary between the construction area of ​​the lower part of the step and the construction area of ​​the upper part of the step, a pair of bracing plates that abut against the inner surfaces of the opposing vertical walls of the formwork, and a conversion means disposed between the base plate and each of the bracing plates, which converts the pressure (ready-mix concrete blow-up force) caused by the blow-up of ready-mix concrete (hereinafter referred to as "ready-mix concrete blow-up force") acting on the base plate from the top surface of the lower part of the step when ready-mix concrete is poured into the construction area of ​​the upper part of the step into a bracing force directed toward the inner surface of the vertical wall of the formwork by each of the bracing plates. The conversion means is composed of a connecting member, one end of which is rotatably attached to the bottom plate and the other end of which is rotatably attached to the bracing plate. It is characterized by the following:

[0011] Due to this specific requirement, when pouring ready-mix concrete into the construction area above the step, a ready-mix concrete blow-up prevention jig (more specifically, the bottom plate of the ready-mix concrete blow-up prevention jig) is installed on the top surface below the step. When ready-mix concrete is poured into the construction area above the step, if a blow-up force is generated from the top surface below the step to the bottom plate, this blow-up force is converted by a conversion mechanism into a bracing force directed towards the inner surface of the vertical wall of the formwork by each bracing plate. As a result, the frictional force between each bracing plate and the inner surface of the vertical wall of the formwork increases, and the position of each bracing plate is maintained to some extent, and therefore the height position of the bottom plate connected to these bracing plates is also maintained to some extent. In other words, the bottom plate presses down on the top surface below the step, preventing the ready-mix concrete from blowing up below the step. Thus, since it is possible to prevent the uplift of ready-mix concrete by simply installing a jig to prevent uplift of ready-mix concrete on the top surface of the lower part of the step, the work required to prevent uplift of ready-mix concrete can be simplified, and the working time can be reduced.

[0013] Also The bracing plates can rotate so that their entire surface can come into contact with the inner surface of the vertical wall of the formwork. As a result, sufficient frictional force can be obtained between these bracing plates and the inner surface of the vertical wall of the formwork, thereby fully demonstrating the effect of preventing the ready-mix concrete from blowing up.

[0014] Furthermore, in the bracing plate, the surface that contacts the inner surface of the vertical wall of the formwork is made of a material that increases frictional force.

[0015] This allows for a higher frictional force between the bracing plate and the inner surface of the vertical wall of the formwork, thereby fully demonstrating the effect of preventing the ready-mix concrete from blowing up.

[0016] Furthermore, the bottom plate is Light that allows the state of the underside of the bottom plate at the top of the step to be visually observed through the bottom plate. It is made of a permeable material.

[0017] According to this, when pouring ready-mix concrete into the construction area at the top of the step, the condition of the underside of the bottom plate at the top of the step can be visually inspected by passing through the bottom plate. For example, it is possible to check the quality of construction, such as whether there are any depressions or other defects at the top of the step. If deterioration of construction quality is confirmed by passing through the bottom plate, measures can be taken such as immediately removing the ready-mix concrete blow-up prevention jig after the completion of pouring ready-mix concrete into the construction area at the top of the step (removing it before the ready-mix concrete hardens) and repairing the top of the step, or extending the working time of the work using a vibrator or the like without removing the ready-mix concrete blow-up prevention jig (extending the working time to resolve the deterioration of construction quality). In other words, the bottom plate light By constructing them from permeable materials, it can be helpful in determining the necessity of these countermeasures.

[0018] Furthermore, the construction method for a rising step section using the aforementioned ready-mix concrete blow-up prevention jig also falls within the scope of the technical concept of the present invention. In other words, the construction method for a rising step section is characterized by including the steps of: pouring the ready-mix concrete up to a predetermined top surface height position at the lower part of the step; installing the ready-mix concrete blow-up prevention jig on the top surface of the lower part of the step at the boundary between the construction area at the lower part of the step and the construction area at the upper part of the step; pressing the bracing plate of the ready-mix concrete blow-up prevention jig against the inner surfaces of the opposing vertical walls in the formwork; and pouring ready-mix concrete into the construction area at the upper part of the step, which is partitioned by the partition plate, to pour the ready-mix concrete up to a predetermined top surface height position at the upper part of the step.

[0019] In the construction method of the rising step part using this fresh concrete blow-up prevention jig, it is only necessary to perform simple operations such as installing the fresh concrete blow-up prevention jig on the top edge of the lower part of the step and pressing each stay plate against the inner surface of each vertical wall of the formwork. Since it is possible to prevent the fresh concrete from blowing up, it is possible to simplify the work for preventing the fresh concrete from blowing up and shorten the working time.

Effect of the Invention

[0020] In the present invention, when placing fresh concrete in the construction range of the upper part of the step, when the fresh concrete blowing-up force from the top edge of the lower part of the step acts on the bottom plate, the fresh concrete blowing-up force is converted into a tension force directed toward the inner surface of each vertical wall of the formwork, and the height position of the bottom plate is substantially maintained. As a result, the bottom plate presses against the top edge of the lower part of the step to prevent the fresh concrete from blowing up. Therefore, it is possible to prevent the fresh concrete from blowing up only by performing a simple operation of installing the fresh concrete blow-up prevention jig on the top edge of the lower part of the step, and it is possible to simplify the work for preventing the fresh concrete from blowing up and shorten the working time.

Brief Description of the Drawings

[0021] [Figure 1] Fig. 1(a) is a perspective view showing the rising step part of the foundation, and Fig. 1(b) is a perspective view showing the formwork of the construction part of the rising step part. [Figure 2] It is a perspective view showing a fresh concrete blow-up prevention jig. [Figure 3] It is a perspective view showing a state where fresh concrete is placed up to the height position of the top edge of the lower part of the step during the construction of the rising step part. [Figure 4] It shows a state where a fresh concrete blow-up prevention jig is installed in the lower part of the step during the construction of the rising step part. Fig. 4(a) is a perspective view, and Fig. 4(b) is a view seen from a direction along the longitudinal direction of the foundation. [Figure 5] It is a view seen from a direction along the width direction of the foundation, showing the state where a fresh concrete blow-up prevention fixture is installed at the lower part of the step. [Figure 6] When constructing the rising step part, it shows the state where the fresh concrete is placed up to the top height position of the upper part of the step. Fig. 6(a) is a perspective view, and Fig. 6(b) is a view seen from a direction along the longitudinal direction of the foundation. [Figure 7] It is a view seen from a direction along the width direction of the foundation, showing the case where blow-up of fresh concrete occurs in the prior art.

Embodiments for Carrying out the Invention

[0022] Hereinafter, embodiments of the present invention will be described based on the drawings. This embodiment describes the case where the present invention is applied as a fresh concrete blow-up prevention fixture used during the construction of the foundation of a building such as a house (during the construction of the rising step part). In the following description, the fresh concrete blow-up prevention fixture may sometimes be simply referred to as a fixture.

[0023] -Explanation of the rising step part of the foundation- Before explaining the fixture, the rising step part of the foundation constructed using the fixture will be explained. Fig. 1(a) is a perspective view showing the rising step part 2 of the foundation 1, and Fig. 1(b) is a perspective view showing the formwork 3 of the construction part of the rising step part 2. In this Fig. 1(b), the shape of the rising step part 2 after construction is shown by a virtual line. In the following description, the extending direction of the foundation 1 is taken as the X direction, and in this direction, the lower left direction of Figs. 1(a) and (b) is called the X1 direction, and the upper right direction is called the X2 direction. Also, the width direction of the foundation 1 is taken as the Y direction, and in this direction, the upper left direction of Figs. 1(a) and (b) is called the Y1 direction, and the lower right direction is called the Y2 direction. Also, the height direction of the foundation 1 is taken as the Z direction, and in this direction, the upper direction of Figs. 1(a) and (b) is called the Z1 direction, and the lower direction is called the Z2 direction.

[0024] As shown in Figures 1(a) and 1(b), the rising step section 2 comprises an upper step section 21 and a lower step section 22. In the configuration shown in Figures 1(a) and 1(b), the lower step section 22 is located on the X1 side of the upper step section 21.

[0025] The lower part of the step 22 has a top surface 22a set at a predetermined height. The upper part of the step 21 has a top surface 21a set at a predetermined height position higher than the top surface 22a of the lower part of the step 22, and also has a vertical surface 21b that extends vertically (in a direction perpendicular to the X direction) from the X1 direction end of this top surface 21a to the X2 direction end of the top surface 22a of the lower part of the step 22.

[0026] Foundation 1 is formed by pouring ready-mix concrete into the internal space of the steel formwork 3 shown in Figure 1(b). The formwork 3 has a pair of opposing vertical walls 31, 31 spaced apart. Since ready-mix concrete is poured between these vertical walls 31, 31 to form Foundation 1, the distance between these vertical walls 31, 31 becomes the width dimension (Y-direction dimension) of Foundation 1. The upper ends of each vertical wall 31, 31 have upper ends 31a, 31a that extend horizontally for attaching partition plates 4 (see Figure 3), which will be described later. For example, although not shown, bolt holes for attaching partition plates 4 are provided in these upper ends 31a, 31a. The construction method for the building's foundation 1 can be any concrete construction method using steel formwork 3. The construction method for the building's foundation 1 can be, for example, a strip foundation or a raft foundation.

[0027] -Partition plate configuration- Next, the configuration of the partition plate 4 will be explained. This partition plate 4 is positioned at the boundary between the construction area of ​​the upper part of the step 21 (area T1 in Figure 3) and the construction area of ​​the lower part of the step 22 (area T2 in Figure 3), which are the step boundary of the rising step section 2, and separates the construction area T1 of the upper part of the step 21 from the construction area T2 of the lower part of the step 22. As a result, after pouring ready-mix concrete up to the height position of the top surface 22a of the lower part of the step 22 (a predetermined height position), ready-mix concrete is poured into the construction area T1 of the upper part of the step 21, and the ready-mix concrete is dammed up by the partition plate 4, so that the upper part of the step 21 is formed (see Figure 6(a)).

[0028] As shown in Figure 3, the partition plate 4 has mounting parts 41, 41 attached to each upper end 31a, 31a of the formwork 3 (shown by dashed lines in Figure 3), connecting parts 42 connecting the mounting parts 41, 41 to each other, and a partition part 43 located between the mounting parts 41, 41 and extending downward from the connecting part 42, with its main surface expanding in a direction perpendicular to the inner surface of the formwork 3 to partition the upper part inside the formwork 3. Each mounting part 41, 41 consists of a rectangular plate portion extending in a horizontal direction perpendicular to the Z direction (along the X direction). The connecting part 42 also consists of a rectangular plate portion extending in a horizontal direction perpendicular to the Z direction (along the Y direction). The partition part 43 consists of a rectangular plate portion extending in a direction perpendicular to the X direction. The lower part of this partition part 43 is curved in a J shape toward the construction area T2 of the lower step 22 (towards the X1 direction). Furthermore, the height dimension of the partition portion 43 is set such that, when the mounting portions 41, 41 are attached to the upper ends 31a, 31a of the formwork 3, the position of the lower end of the partition portion 43 is approximately the same as the height of the top surface 22a of the lower step portion 22. In this embodiment, the position of the lower end of the partition portion 43 is designed to be slightly higher than the height of the top surface 22a of the lower step portion 22 (higher by the thickness dimension of the bottom plate 51 of the jig 5, which will be described later).

[0029] -Jig configuration- Next, the configuration of the jig (concrete blow-up prevention jig) 5 used in the construction of the rising step section 2 will be explained. The jig 5 is used when pouring ready-mix concrete into the construction area T1 of the upper step section 21 after pouring the lower step section 22, in a state where the mounting parts 41, 41 of the partition plate 4 are attached to the upper ends 31a, 31a of the formwork 3 (a state in which ready-mix concrete can be dammed up in the construction area T1 of the upper step section 21 by the partition plate 4), and has the function of preventing ready-mix concrete from blowing up at the top surface 22a of the lower step section 22.

[0030] Figure 2 is a perspective view showing the jig 5. As shown in Figure 2, the jig 5 is composed of a base plate 51, a pair of bracing plates 52A and 52B, and four connecting members 53A, 53B, 53C, and 53D which serve as conversion means in this invention.

[0031] The base plate 51 is made of a roughly rectangular plate. This base plate 51 is made of a permeable material. For example, it is made of a glass plate or an acrylic plate. However, in this invention, it is not essential that the base plate 51 be permeable, and the base plate 51 may be made of an opaque resin, wood, or metal. The length dimension in the Y direction of the base plate 51 is set to be approximately the same as the width dimension (length dimension in the Y direction) of the foundation 1. For example, the length dimension in the Y direction of the base plate 51 is set to be slightly shorter (about 10 mm shorter) than the width dimension of the foundation 1. Also, the length dimension in the X direction of the base plate 51 is set to be the same as or slightly longer than the length dimension in the X direction of the area where there is concern about the upwelling of fresh concrete. This length dimension in the X direction of the area where there is concern about the upwelling of fresh concrete can be obtained empirically or by simulation. As an example of the specific dimensions of this base plate 51, the length dimension in the Y direction is 240 mm and the length dimension in the X direction is 300 mm, relative to the width dimension of the foundation 1 of 250 mm. These dimensions are not limited to these. Generally, there are multiple standards for the width dimension of the base 1 (for example, there are standards of 160 mm and 250 mm), so in particular, the length dimension in the Y direction of the base plate 51 will be set in accordance with these standard dimensions.

[0032] Each bracing plate 52A and 52B is made of a roughly rectangular board (for example, a wooden board). For convenience, the bracing plate located on the left side in Figure 2 will be called the first bracing plate 52A, and the bracing plate located on the right side in Figure 2 will be called the second bracing plate 52B. These bracing plates 52A and 52B will be in contact with the inner surfaces of the opposing vertical walls 31, 31 in the formwork 3. The first bracing plate 52A will be in contact with the inner surface of the vertical wall 31 located on the Y1 side, and the second bracing plate 52B will be in contact with the inner surface of the vertical wall 31 located on the Y2 side. As an example of the specific dimensions of each bracing plate 52A and 52B, the length in the X direction is 200 mm and the length in the Z direction is 90 mm. These dimensions are not limited to these.

[0033] Furthermore, the surfaces of each bracing plate 52A, 52B that abut against the inner surfaces of the vertical walls 31, 31 of the formwork 3 (hereinafter also referred to as the "contact surface") are made of a material that increases friction. In this embodiment, rubber plates 54A, 54B are attached to the contact surfaces of each bracing plate 52A, 52B by means of adhesive or other means. Other examples of making the contact surface of a material that increases friction include installing a material with a high coefficient of friction other than rubber plates on the contact surface, or applying a surface treatment to the contact surface to increase friction. In addition, the surface of these rubber plates 54A, 54B (the surface that abuts against the inner surfaces of the vertical walls 31 of the formwork 3) is corrugated in shape to increase friction. Note that the shape of the surface is not limited to a corrugated shape; for example, it may be a shape with irregularities that increase friction. This ensures that a high frictional force is obtained between the rubber plate and the inner surfaces of the vertical walls 31, 31 of the formwork 3.

[0034] The connecting members 53A, 53B, 53C, and 53D are members that connect the base plate 51 and the bracing plates 52A and 52B, and are made of wooden square timbers having a predetermined length. In the jig 5 according to this embodiment, four connecting members 53A to 53D are provided. Specifically, there are two connecting members 53A and 53B that connect the base plate 51 and the first bracing plate 52A, and two connecting members 53C and 53D that connect the base plate 51 and the second bracing plate 52B. For convenience, the two connecting members 53A and 53B that connect the base plate 51 and the first bracing plate 52A will be collectively referred to as the first connecting member pair, and the two connecting members 53C and 53D that connect the base plate 51 and the second bracing plate 52B will be collectively referred to as the second connecting member pair.

[0035] The ends of the two connecting members 53A and 53B constituting the first connecting member pair on the Y2 direction are connected via hinges 55A and 55B that are rotatable around a pivot axis along the X direction, to a position closer to the Y2 direction than the center of the upper surface of the bottom plate 51. In addition, the ends of the two connecting members 53A and 53B constituting this first connecting member pair on the Y1 direction are connected via hinges 56A and 56B that are rotatable around a pivot axis along the X direction, to a position approximately in the vertical center of the first bracing plate 52A.

[0036] Similarly, the Y1-direction ends of the two connecting members 53C and 53D constituting the second connecting member pair are connected via hinges 55C and 55D that are rotatable around a pivot axis along the X direction, to a position closer to the Y1 direction than the center of the upper surface of the bottom plate 51. Furthermore, the Y2-direction ends of the two connecting members 53C and 53D constituting this second connecting member pair are connected via hinges 56C and 56D that are rotatable around a pivot axis along the X direction, to a position approximately in the vertical center of the second bracing plate 52B.

[0037] The length dimensions of each connecting member 53A to 53D, and the connection positions to the bottom plate 51 and the bracing plates 52A and 52B can be set arbitrarily. However, when the bottom plate 51 is installed on the top surface 22a of the lower part of the step 22, and the bracing plates 52A and 52B are in contact with the inner surfaces of the vertical walls 31, 31 of the formwork 3, it is preferable that the inclination angle of each connecting member 53A to 53D is small (an inclination angle close to the horizontal). This design takes into consideration the following points: ensuring that the entire surface of the bracing plates 52A and 52B abuts against the inner surface of the vertical walls 31, 31 of the formwork 3 (avoiding the upper portion of the bracing plates 52A and 52B not abutting against the inner surface of the vertical walls 31, 31 of the formwork 3); and preventing the bracing plates 52A and 52B from sliding against the inner surface of the vertical walls 31, 31 of the formwork 3 when the blowing force of the fresh concrete described later is applied (if the vertical component of the force acting along the longitudinal direction of each connecting member 53A to 53D is large, there is a possibility that the bracing plates 52A and 52B may slide against the inner surface of the vertical walls 31, 31 of the formwork 3). An example of the specific dimensions of each connecting member 53A to 53D is that the length in the longitudinal direction is 180 mm and the length in the width direction (X direction) is 25 mm. These dimensions are not limited to these. Based on the dimensions of each component described above, the inclination angle when the bracing plates 52A and 52B are in contact with the inner surfaces of the vertical walls 31, 31 of the formwork 3 is set to, for example, 35°. This angle is not limited to this.

[0038] -Construction of the rising step section- Next, the construction of the raised step section 2 using the jig 5 configured as described above will be explained. The construction process for this raised step section 2 involves, in order, the installation of the partition plate 4, the construction of the lower part of the step 22, the installation of the jig 5, the construction of the upper part of the step 21, and the removal of the jig 5.

[0039] In the process of installing the partition plate 4, as shown in Figure 3, the mounting portions 41, 41 of the partition plate 4 are attached to the upper ends 31a, 31a of the formwork 3 by means of bolting or other means. At this time, taking into consideration the installation of the jig 5, the lower part of the J-shaped curved partition portion 43 may be adjusted to be slightly higher than the predetermined height position of the top surface 22a of the lower step portion 22.

[0040] In the construction of the lower part 22 of the step, as shown in Figure 3, ready-mixed concrete is poured up to the height of the top surface 22a of the lower part 22 (a predetermined height). As a result, ready-mixed concrete is poured up to the predetermined height (the height that becomes the top surface 22a of the lower part 22) in both the construction area T1 of the upper part 21 and the construction area T2 of the lower part 22 of the step.

[0041] Figure 4 shows the jig 5 installed on the top surface 22a of the lower part 22 of the step. Figure 4(a) is a perspective view, and Figure 4(b) is a view from a direction along the longitudinal direction of the foundation 1. In Figure 4(a), the formwork 3 is shown with dashed lines to make the installation of the jig 5 easier to understand.

[0042] As shown in these figures, in the process of installing the jig 5, the bottom plate 51 of the jig 5 is installed on the top surface 22a of the lower step 22 at the boundary between the construction area T1 of the upper step 21 and the construction area T2 of the lower step 22. More specifically, as shown in Figure 5 (a view of the state in which the jig 5 is installed on the lower step 22, viewed from a direction along the width direction of the foundation 1), one end portion of the bottom plate 51 (the end on the X2 direction side) is inserted under the lower part of the partition portion 43, which is curved in a J shape (inserted between the lower part of the partition portion 43 and the top surface 22a of the lower step 22).

[0043] Furthermore, prior to the step of installing this jig 5, it is preferable to remove dust, dirt, concrete residue, etc., from the inner surfaces of the vertical walls 31, 31 of the formwork 3.

[0044] After the jig 5 is set up in this manner, the bracing plates 52A and 52B are pressed against the inner surfaces of the vertical walls 31, 31 of the formwork 3. This process involves the worker applying a downward force to each connecting member 53A to 53D (see arrows F1, F1 in Figure 4(b)) so that each bracing plate 52A and 52B is pressed against the inner surfaces of the vertical walls 31, 31 of the formwork 3. At this time, since each connecting member 53A to 53D is rotatably attached to the bottom plate 51 and the bracing plates 52A and 52B via hinges, the entire surface of the bracing plates 52A and 52B can come into contact with the inner surfaces of the vertical walls 31, 31 of the formwork 3.

[0045] In the construction of the upper part 21 of the step, as shown in Figures 5 and 6(a), ready-mixed concrete is poured into the construction area T1 of the upper part 21 of the step, and the ready-mixed concrete is dammed by the partition portion 43 of the partition plate 4, so that the ready-mixed concrete is poured up to the height of the top surface 21a of the upper part 21 (a predetermined height). In addition, in order to pour the ready-mixed concrete densely into the formwork 3, a vibrator is used to vibrate the ready-mixed concrete poured into the formwork 3.

[0046] In conventional techniques, when vibration is applied using a vibrator, as explained in Figure 7, the still-unhardened fresh concrete c becomes fluid, and there is a possibility that the fresh concrete will blow up f at the top surface e1 of the lower part e of the step. This requires work such as scooping up and disposing of the excess fresh concrete that has blown up, which increases the effort required to construct the rising step section and leads to increased construction costs.

[0047] In contrast, in this embodiment, when vibration is applied using this vibrator, if a concrete-blowing force (see arrow F2 in Figure 6(b)) is generated acting from the top surface 22a of the lower step 22 to the bottom plate 51 of the jig 5, this concrete-blowing force is converted by the connecting members 53A to 53D into a bracing force (see arrows F3 and F4 in Figure 6(b)) that directs each bracing plate 52A and 52B toward the inner surface of the vertical walls 31 and 31 of the formwork 3. As a result, the frictional force between each bracing plate 52A and 52B and the inner surface of the vertical walls 31 and 31 of the formwork 3 increases, and the position of each bracing plate 52A and 52B is maintained to some extent. Consequently, the height position of the bottom plate 51, which is connected to these bracing plates 52A and 52B via the connecting members 53A to 53D, is also maintained to some extent. In other words, the base plate 51 presses down on the top surface 22a of the lower part of the step 22, preventing the fresh concrete from blowing up at the lower part of the step 22. The bracing force can be increased as the force of the fresh concrete blowing up increases, and the force with which the base plate 51 presses down on the top surface 22a of the lower part of the step 22 (the reaction force against the force of the fresh concrete blowing up) will be increased.

[0048] Furthermore, since the bottom plate 51 of the jig 5 is made of a permeable material, when pouring ready-mix concrete into the construction area T1 of the upper part 21 of the step, the worker can visually inspect the condition of the underside of the bottom plate 51 at the top surface 22a of the lower part 22 by passing through the bottom plate 51. For example, the worker can check the quality of the construction, such as whether there are any depressions or other defects on the top surface 22a of the lower part 22. If deterioration of the construction quality is confirmed by passing through the bottom plate 51, measures can be taken such as immediately removing the jig 5 after the completion of pouring ready-mix concrete into the construction area T1 of the upper part 21 (before the ready-mix concrete hardens) and repairing the top surface 22a of the lower part 22, or extending the working time of the work using a vibrator to apply vibration without removing the jig 5 (extending the working time to resolve the deterioration of the construction quality).

[0049] Once the construction of the upper part 21 of the step is complete, the jig 5 is removed. At this time, one end of the bottom plate 51, which is inserted between the lower part of the partition portion 43 of the partition plate 4 and the top surface 22a of the lower part 22 of the step, is pulled out horizontally. However, since the lower part of the partition portion 43 is curved in a J shape, the upper surface of the bottom plate 51 and the lower part of the partition portion 43 are in line contact, so the sliding resistance when pulling it out is small (the sliding resistance is small compared to when the bottom plate 51 and the lower part of the partition portion 43 are in surface contact), and it can be easily pulled out, ensuring good workability for the removal of the jig 5.

[0050] -Effects of the embodiment- As explained above, in this embodiment, the only work required to prevent the ready-mix concrete from boiling up is to install the jig 5 on the top surface 22a of the lower part 22 of the step. Therefore, the work required to prevent the ready-mix concrete from boiling up can be simplified, and the working time can be shortened.

[0051] Furthermore, if a blowing force occurs due to the ready-mix concrete, the base plate 51 may move slightly upward, but this is unlikely to cause any problems during construction. Generally, during the construction of foundation 1, some leveling work is performed on the top surface of the ready-mix concrete after it has been poured, so a slight shift in the top surface of the ready-mix concrete due to a slight lifting of the base plate 51 does not pose any particular problem.

[0052] -Other Embodiments- Furthermore, the present invention is not limited to the embodiments described above, and all modifications and applications are possible within the scope of the claims and equivalents thereof.

[0053] For example, the above embodiment described an application of the present invention as a concrete blow-up prevention jig 5 used during the construction of the foundation 1 of a building such as a house (during the construction of the rising step section 2). The present invention is not limited to this, and can be applied to the construction of various rising step sections, such as the construction of walls with rising step sections in reinforced concrete buildings, or the construction of fences with rising step sections in the exterior of houses.

[0054] Furthermore, in the above embodiment, each bracing plate 52A, 52B and connecting members 53A to 53D were made of wood. However, the present invention is not limited to this, and may be made of metal, resin, etc., and is not particularly limited by material.

[0055] Furthermore, although the above embodiment described a case in which four connecting members 53A to 53D are provided, this number is not limited to this. Any number of connecting members 53A to 53D may be provided, as long as their arrangement and number are set to take into account the tilt when the jig 5 is installed. For example, there may be two or five or more. However, from the viewpoint of suppressing the tilt when the jig 5 is installed, it is desirable to provide four or more connecting members 53A to 53D.

[0056] Furthermore, the conversion means (the conversion means that converts the blowing force of the fresh concrete into the bracing force) is not limited to connecting members 53A to 53D made of square timber. In other words, any means that can convert the blowing force of the fresh concrete into a bracing force is acceptable.

[0057] Furthermore, the embodiments and other matters disclosed herein can also be understood as the technical concepts described in the following appendix.

[0058] (Note 1) A concrete blow-up prevention jig used when constructing a rising step section having a lower step section and an upper step section with different top surface heights, for pouring ready-mix concrete into the construction area of ​​the upper step section separated by a partition plate after pouring ready-mix concrete up to a predetermined top surface height position of the lower step section, A base plate is installed on the top surface of the lower part of the step at the boundary between the construction area of ​​the lower part of the step and the construction area of ​​the upper part of the step, A pair of bracing plates that abut against the inner surfaces of opposing vertical walls in the formwork, A ready-mix concrete blow-up prevention jig, characterized in that it is disposed between the base plate and each of the bracing plates, and comprises a conversion means that converts the pressure caused by the blow-up of ready-mix concrete acting on the base plate from the top of the lower part of the step when ready-mix concrete is poured into the construction area above the step into a bracing force directed toward the inner surface of the vertical wall of the formwork by each of the bracing plates.

[0059] (Note 2) In the concrete blow-up prevention jig described in Appendix 1, The concrete blow-up prevention jig is characterized in that the conversion means is composed of a connecting member, one end of which is rotatably attached to the bottom plate and the other end of which is rotatably attached to the bracing plate.

[0060] (Note 3) In the concrete blow-up prevention jig described in Appendix 1 or 2, A concrete blow-up prevention jig characterized in that the surface of the bracing plate that contacts the inner surface of the vertical wall of the formwork is made of a material that increases frictional force.

[0061] (Note 4) In the concrete blow-up prevention jig described in Appendix 1, 2, or 3, A concrete boil-up prevention jig characterized in that the bottom plate is made of a permeable material.

[0062] (Note 5) A construction method for a raised step section using a concrete blow-up prevention jig described in any one of the appendices 1 to 4, The process of pouring the ready-mixed concrete up to a predetermined top surface height position at the bottom of the step, The process of installing the concrete blow-up prevention jig on the top surface of the lower part of the step at the boundary between the construction area at the lower part of the step and the construction area at the upper part of the step, The steps include pressing the bracing plate of the concrete blow-up prevention jig against the inner surfaces of the opposing vertical walls in the formwork, A method for constructing a rising step, characterized by including the step of pouring ready-mix concrete into the construction area above the step separated by the partition plate, and pouring the ready-mix concrete up to a predetermined top surface height position above the step. [Industrial applicability]

[0063] The present invention is applicable to a jig for preventing the uplift of ready-mixed concrete used during the construction of stepped sections of the foundation of a building, and to a method for constructing stepped sections of stepped sections using the jig. [Explanation of symbols]

[0064] 1 Basics 2. Rising step section 21 Top of step 21a Top surface of the step 22 Lower part of the step 22a Top surface of the lower part of the step 3 Formwork 31 Vertical wall 4 partition plates 5. Jig (Jig to prevent concrete from overflowing) 51 Bottom plate 52A, 52B Tension board 53A~53D Connecting members (conversion means)

Claims

1. A concrete blow-up prevention jig used when constructing a rising step section having a lower step section and an upper step section with different top surface heights, for pouring ready-mix concrete into the construction area of ​​the upper step section separated by a partition plate after pouring ready-mix concrete up to a predetermined top surface height position of the lower step section, A base plate is installed on the top surface of the lower part of the step at the boundary between the construction area of ​​the lower part of the step and the construction area of ​​the upper part of the step, A pair of bracing plates that abut against the inner surfaces of opposing vertical walls in the formwork, The system is provided with a conversion means that is arranged between the base plate and each of the bracing plates, and when ready-mix concrete is poured into the construction area above the step, and pressure is applied to the base plate from the top of the lower part of the step due to the blowing up of the ready-mix concrete, the conversion means converts this pressure into a bracing force directed by each of the bracing plates toward the inner surface of the vertical wall of the formwork. The concrete blow-up prevention jig is characterized in that the conversion means is composed of a connecting member, one end of which is rotatably attached to the bottom plate and the other end of which is rotatably attached to the bracing plate.

2. In the ready-mix concrete blow-up prevention jig according to Claim 1, A concrete blow-up prevention jig characterized in that the surface of the bracing plate that contacts the inner surface of the vertical wall of the formwork is made of a material that increases frictional force.

3. In the ready-mix concrete blow-up prevention jig according to Claim 1 or 2, The concrete blow-up prevention jig is characterized in that the bottom plate is made of a light-transmitting material that allows the state of the underside of the bottom plate at the top surface of the step to be visually inspected by passing through the bottom plate.

4. A method for constructing a raised step section using the ready-mix concrete blow-up prevention jig described in Claim 1, The process of pouring the ready-mixed concrete up to a predetermined top surface height position at the bottom of the step, The process of installing the concrete blow-up prevention jig on the top surface of the lower part of the step at the boundary between the construction area at the lower part of the step and the construction area at the upper part of the step, The steps include pressing the bracing plate of the concrete blow-up prevention jig against the inner surfaces of the opposing vertical walls in the formwork, A method for constructing a rising step, characterized by including the step of pouring ready-mix concrete into the construction area above the step separated by the partition plate, and pouring the ready-mix concrete up to a predetermined top surface height position above the step.

Images