Manufacturing method of concrete blocks

Abstract

The present invention provides a method for manufacturing concrete blocks that can effectively suppress concrete leakage during placement and suppress an increase in work hours after demolding. [Solution] Reinforcing bars are embedded inside the L-shaped block, and the reinforcing bars include protruding reinforcing bars 66 that partially protrude outwards. The formwork 70 for forming the L-shaped block is provided with holes 81 through which the protruding reinforcing bars 66 pass. When manufacturing the L-shaped block, first the reinforcing bars are placed inside the formwork 70, and the protruding reinforcing bars 66 are passed through the holes 81 in the formwork 70. Next, a rubber stopper 90 is fitted onto the outer circumference of the protruding reinforcing bar 66 through a notch 92, so that the protruding reinforcing bar 66 passes through the through-hole 91 of the rubber stopper 90. After that, with the protruding reinforcing bar 66 passing through the through-hole 91, the rubber stopper 90 is pushed into the hole 81, so that the outer surface of the rubber stopper 90 and the inner surface of the hole 81 are in close contact, and the inner surface of the through-hole 91 and the outer surface of the protruding reinforcing bar 66 are in close contact.

Description

Technical Field

[0005] , ,

[0001] The present invention relates to a method for manufacturing concrete blocks.

Background Art

[0002] For large concrete products such as box culverts, there are split-type products that are constructed by combining concrete blocks manufactured (precast) in a factory at the site in order to improve the efficiency of transportation and construction. In such split-type concrete products, protruding reinforcing bars are provided in any one of the plurality of concrete blocks constituting the concrete product (see, for example, Patent Document 1). The protruding reinforcing bar is a reinforcing bar in which a part of the reinforcing bar embedded in the concrete block is provided in a state of protruding outward. The protruding reinforcing bar functions as a connecting portion connected to other concrete blocks or the like.

[0003] When forming a concrete block provided with a protruding reinforcing bar using a mold, a hole for passing the protruding reinforcing bar is provided in the mold. Then, concrete is placed in a state where the protruding reinforcing bar passes through the hole of the mold. Further, at the time of this placement, in order to prevent the concrete from leaking out from around the protruding reinforcing bar in the hole, for example, the periphery of the protruding reinforcing bar in the hole is blocked with a sponge material.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Incidentally, sponge material is a highly flexible (compressible) material. Therefore, when filling the area around a protruding reinforcing bar in a hole with sponge material, there is a risk that the protruding reinforcing bar may shift radially while compressing the sponge material. In that case, this shifting will increase the gap between the protruding reinforcing bar and the inner surface of the hole on the opposite side of the shift. As a result, the compression of the sponge material will weaken in the area where the gap has increased, and concrete may be more prone to leaking.

[0006] Furthermore, because the sponge material has a porous structure, it is anticipated that concrete may seep into the small pores of the sponge material during concrete placement. In that case, once the concrete hardens, the sponge material will adhere to the hardened concrete, requiring the removal of the sponge material from the concrete after demolding. This removal process may involve peeling the sponge material from the concrete or chipping away at the concrete, potentially leading to an increase in labor costs.

[0007] The present invention has been made in view of the above circumstances, and its main objective is to provide a method for manufacturing concrete blocks that can effectively suppress concrete leakage during placement and suppress an increase in the number of work steps after demolding. [Means for solving the problem]

[0008] In order to solve the above problems, the present invention provides a method for manufacturing concrete blocks. A method for manufacturing a concrete block in which reinforcing bars are embedded inside, and the reinforcing bars include protruding reinforcing bars that partially protrude outwards, The formwork for shaping the concrete block is provided with holes for passing the protruding reinforcing bars. A rebar placement step involves arranging the reinforcing bars within the formwork and passing the protruding reinforcing bars through the holes in the formwork, A preparation step of preparing a columnar rubber stopper having a circular cross-section, wherein the rubber stopper has a through hole that penetrates the rubber stopper in the axial direction and a notch cut from the inner circumferential surface of the through hole to the outer circumferential surface of the rubber stopper, After the reinforcement placement process and the preparation process, the rubber stopper is fitted onto the outer circumference of the protruding reinforcing bar through the notch, and the protruding reinforcing bar is passed through the through hole in a passing process. A pressing step in which the rubber stopper is pushed into the hole with the protruding reinforcing bar passed through the through hole, so that the outer surface of the rubber stopper is in close contact with the inner surface of the hole, and the inner surface of the through hole is in close contact with the outer surface of the protruding reinforcing bar, After the pressing step, a pouring step is performed in which concrete is poured into the formwork, It is equipped with. [Effects of the Invention]

[0009] According to the present invention, after passing the protruding reinforcing bar through the hole in the formwork, a rubber stopper is fitted onto the outer circumference of the protruding reinforcing bar through a notch, so that the protruding reinforcing bar passes through the through-hole of the rubber stopper. Then, the rubber stopper is pushed into the hole, so that the outer surface of the rubber stopper and the inner surface of the hole are in close contact, and the inner surface of the through-hole and the outer surface of the protruding reinforcing bar are in close contact. The rubber stopper is harder than sponge material and is difficult to compress. Therefore, in this case, displacement of the protruding reinforcing bar in the radial direction can be suppressed, and as a result, localized leakage of concrete due to such displacement can be suppressed. This effectively suppresses concrete leakage during concrete placement.

[0010] Furthermore, because the rubber stopper is not porous like a sponge, even if the rubber stopper adheres to the concrete (concrete block) as the concrete hardens, only the surface of the rubber stopper will adhere, and it will not adhere firmly. As a result, the rubber stopper can be easily removed after demolding, and consequently, the increase in work time after demolding can be suppressed. [Brief explanation of the drawing]

[0011] [Figure 1] A front view showing the box culvert in the first embodiment divided into upper and lower sections. [Figure 2] A cross-sectional view showing the reinforced concrete structure inside the formwork. [Figure 3](a) is a perspective view showing a formwork member constituting a formwork, and (b) is a perspective view showing a state where a pushing jig is set inside the formwork member. [Figure 4] (a) is a cross-sectional view showing the periphery of a hole of a formwork member, and (b) is a perspective view showing a collar. [Figure 5] Cross-sectional view for explaining a manufacturing method of a lower block. [Figure 6] Cross-sectional view for explaining a manufacturing method of a lower block. [Figure 7] (a) is a perspective view of a rubber plug, (b) is a front view of the rubber plug, and (c) is a side view of the rubber plug. [Figure 8] Perspective view showing a pushing jig. [Figure 9] Perspective view for explaining a step of pushing each pushing jig with a long member. [Figure 10] Cross-sectional view showing a water channel in a second embodiment. [Figure 11] Cross-sectional view showing a state where reinforcing bars are arranged inside a formwork. [Figure 12] Cross-sectional view for explaining a manufacturing method of an L-shaped block. [Figure 13] Cross-sectional view for explaining a manufacturing method of an L-shaped block. [Figure 14] (a) is a plan view of a rubber plug, and (b) is a front view of the rubber plug. [Embodiments for Carrying Out the Invention]

[0012] (First Embodiment) Hereinafter, an embodiment embodying the present invention will be described with reference to the drawings. In this embodiment, the manufacturing method of the concrete block in the present invention is embodied as the manufacturing method of the lower block constituting the box culvert. FIG. 1 is a front view showing a state where the box culvert is divided vertically.

[0013] ]> As shown in Figure 1, the box culvert 11 is formed in a rectangular tubular shape and comprises a lower block 12 and an upper block 13, which are divided into upper and lower sections. Each block 12 and 13 is made of precast concrete and manufactured in a manufacturing plant. Each block 12 and 13 is formed with a U-shaped cross-section. The lower block 12 has a base plate 14 and a pair of side wall sections 15 extending upward from both ends of the base plate 14 in the width direction. The upper block 13 has a top plate 16 and a pair of side wall sections 17 extending downward from both ends of the top plate 16 in the width direction.

[0014] Multiple reinforcing bars are embedded inside each block 12 and 13. The reinforcing bars consist of deformed bars. The reinforcing bars are arranged in a double reinforcement configuration within each block 12 and 13 (see also Figure 3).

[0015] Multiple reinforcing bars 21 embedded in the lower block 12 include protruding reinforcing bars 22 that partially protrude upward from the upper end surface 15a of the side wall portion 15. Multiple protruding reinforcing bars 22 are provided in each side wall portion 15 of the lower block 12. On the other hand, multiple tubular sleeves 23 into which the protruding reinforcing bars 22 are inserted are embedded in the upper block 13 at the lower end of each side wall portion 17. The lower block 12 corresponds to a "concrete block," and the upper end surface 15a of the side wall portion 15 corresponds to a "predetermined surface of the concrete block."

[0016] At the installation site, the lower block 12 and the upper block 13 are installed with their grooves facing each other vertically. In this case, each protruding reinforcing bar 22 of the lower block 12 is inserted from below into each sleeve 23 of the upper block 13, and in this state, a hardening agent is filled around the protruding reinforcing bars 22 within each sleeve 23. As a result, the side walls 15 and 17 of both blocks 12 and 13 are joined, and the box culvert 11 is constructed.

[0017] Next, the manufacturing method of the lower block 12 produced in the manufacturing plant will be described. The lower block 12 is formed using a formwork 25 for precast concrete. First, the structure of this formwork 25 will be described based on Figures 2 to 4. Figure 2 is a cross-sectional view showing the reinforcing bars 21 arranged inside the formwork 25. Figure 3 is a perspective view in which (a) shows the formwork members 30 that make up the formwork 25, and (b) shows the state in which the pressing jig 50, which will be described later, is set inside the formwork members 30. Figure 4 is a cross-sectional view in which (a) shows the area around the hole 38 of the formwork member 30, and (b) is a perspective view in color.

[0018] As shown in Figure 2, the formwork 25 is composed of a plurality of formwork members 28 to 30. Each of the formwork members 28 to 30 includes a formwork member 30 that forms the upper end surface 15a of the side wall portion 15 of the lower block 12. The formwork member 30 is formed to a size corresponding to the upper end surface 15a of the side wall portion 15.

[0019] As shown in Figure 3, the formwork member 30 is formed in the shape of a long box with one side open. The formwork member 30 has a long, flat plate portion 31, a plurality (specifically four) of side plate portions 32 that are erected from the plate portion 31, and a plurality of inner plate portions 33 that are provided spanning across each of the side plate portions 32 on the long side. The plate portion 31, each side plate portion 32, and each inner plate portion 33 are made of metal and are integrated by welding to each other.

[0020] Multiple circular holes 35 are formed in the plate portion 31. As shown in Figures 4(a) and (b), a metal collar 37 is provided for each hole 35 in the plate portion 31. The collar 37 is formed in an annular shape and is welded to the inner surface of the plate portion 31. The inside of the collar 37 is a hole 37a, and the diameter of this hole 37a is the same as that of the holes 35 in the plate portion 31. Furthermore, the collar 37 is positioned such that its hole 37a is coaxial with the holes 35. In this case, the holes 35 and 37a are continuous, and these holes 35 and 37a form a hole 38 through which the protruding reinforcing bar 22 passes. The hole 38 is a circular cross-section hole with a constant diameter. Note that the hole 38 corresponds to the "hole" described in the claims. Also, the inner circumferential corner of the collar 37 on the side opposite the plate portion 31 is chamfered.

[0021] As shown in Figure 2, the formwork member 30 is installed with the plate portion 31 facing the inside (internal space) of the formwork 25. In this case, each side plate portion 32 and each inner plate portion 33 of the formwork member 30 protrudes outward from the formwork 25 relative to the plate portion 31. The plate surface of the plate portion 31 that faces the inside of the formwork 25 is the molded surface 31a that forms the upper end surface 15a of the side wall portion 15 of the lower block 12.

[0022] Next, the manufacturing method of the lower block 12 will be explained based on Figures 5 and 6, in addition to Figure 2. Figures 5 and 6 are cross-sectional views illustrating the manufacturing method of the lower block 12.

[0023] First, as shown in Figure 2, a reinforcement step is performed in which each reinforcing bar 21, including multiple protruding reinforcing bars 22, is placed inside the formwork 25. In the reinforcement step, as shown in Figure 5(a), each protruding reinforcing bar 22 is passed through the hole 38 of the formwork member 30. As a result, a portion of each protruding reinforcing bar 22 protrudes to the outside of the formwork 25. In this case, the protruding portion of each protruding reinforcing bar 22 is located inside the formwork member 30, surrounded by each side plate 32.

[0024] Next, a preparation step is performed to prepare rubber stoppers 40 to seal the holes 38 in the formwork member 30. The structure of the rubber stoppers 40 will be explained here with reference to Figure 7. Figure 7 shows (a) a perspective view of the rubber stopper 40, (b) a front view of the rubber stopper 40, and (c) a side view of the rubber stopper 40. Note that the preparation step may be performed before the reinforcement step.

[0025] As shown in Figures 7(a) to 7(c), the rubber stopper 40 is formed in a cylindrical shape. The rubber stopper 40 is made of a non-foaming rubber material, such as chloroprene rubber (CR rubber). The rubber stopper 40 is solid and does not contain air bubbles inside. The material of the rubber stopper 40 does not necessarily have to be chloroprene rubber; for example, it may be silicone rubber, soft PVC, or thermoplastic elastomer (e.g., TPE, TPV, etc.).

[0026] The rubber stopper 40 has a through hole 41 that penetrates the rubber stopper 40 in the axial direction, and a notch 42 that is cut from the inner circumferential surface of the through hole 41 to the outer circumferential surface of the rubber stopper 40. The through hole 41 is formed in the center of the rubber stopper 40 and serves as a through hole for passing the protruding reinforcing bar 22 through. The diameter of the through hole 41 is constant, and its diameter is the same as or slightly smaller than the outer diameter of the protruding reinforcing bar 22. As mentioned above, the protruding reinforcing bar 22 is made of deformed reinforcing bar, so the outer diameter of the protruding reinforcing bar 22 refers to the diameter of the thickest part of the reinforcing bar, including the ribs of the deformed reinforcing bar. The notch 42 is cut over the entire axial area of ​​the rubber stopper 40. The notch 42 functions as a passage for guiding the protruding reinforcing bar 22 into the through hole 41 of the rubber stopper 40.

[0027] The rubber stopper 40 has a first portion 45 and a second portion 46 aligned in the axial direction. Both the first portion 45 and the second portion 46 have a constant outer diameter. The outer diameter D2 of the second portion 46 is smaller than the outer diameter D1 of the first portion 45. More specifically, the outer diameter D2 of the second portion 46 is slightly smaller than the outer diameter D1 of the first portion 45, for example, by 0.5 to 3 mm. Also, the axial length L1 of the first portion 45 is shorter than the axial length L2 of the second portion 46, more specifically, it is less than half the axial length L2 of the second portion 46.

[0028] Next, as shown in Figure 5(b), outside the formwork 25, a through-hole process is performed in which the rubber stopper 40 is fitted onto the outer circumference of the protruding reinforcing bar 22 through the notch 42 (see Figures 7(a) and (b)), thereby passing the protruding reinforcing bar 22 through the through-hole 41 of the rubber stopper 40. In this process, the notch 42 is opened and the rubber stopper 40 is fitted onto the outer circumference of the protruding reinforcing bar 22 from the side. Also in this process, the rubber stopper 40 is fitted onto the protruding reinforcing bar 22 with the first portion 45 of the rubber stopper 40 facing the hole 38 of the formwork member 30.

[0029] Next, with the protruding reinforcing bar 22 passed through the through hole 41 of the rubber stopper 40, a pushing process is performed in which the rubber stopper 40 is pushed into the hole 38 of the formwork member 30. In this process, the rubber stopper 40 is pushed into the hole 38 from outside the formwork 25. Note that the pushing process and the preceding passing process are performed for each hole 38 of the formwork member 30, respectively.

[0030] The pressing process involves a preliminary pressing step in which the rubber stopper 40 is partially pressed into the hole 38, and a final pressing step in which the partially pressed rubber stopper 40 is further pressed into the hole 38. In the preliminary pressing step, the worker manually pushes the rubber stopper 40 partway into the hole 38 (preliminary pressing). When the rubber stopper 40 is partially pressed in, a portion of the rubber stopper 40 protrudes from the hole 38 to the outside of the formwork 25 (the state shown in Figure 5(c)).

[0031] In this pressing process, the rubber stopper 40 is pushed into the back of the hole 38 using a pressing jig 50. The configuration of the pressing jig 50 will be described below with reference to Figure 8. Figure 8 is a perspective view showing the pressing jig 50. As shown in Figure 8, the pressing jig 50 has a cylindrical main body 51 and an annular plate-shaped contact portion 52 provided at the tip of the main body 51. An insertion hole 54 for inserting the protruding reinforcing bar 22 is formed on the inside of the main body 51.

[0032] The contact portion 52 is the part that contacts the rubber stopper 40, and its outer diameter is larger than the outer diameters D1 and D2 of the rubber stopper 40. Therefore, when the contact portion 52 contacts the rubber stopper 40, its peripheral edge 52a protrudes from the rubber stopper 40. Specifically, the outer diameter of the contact portion 52 is approximately the same as the outer diameter of the collar 37 of the formwork member 30.

[0033] As shown in Figure 5(c), after the temporary pressing process, a jig setting process is performed in which the pressing jig 50 is set with the protruding reinforcing bars 22 inserted through the insertion holes 54 and the contact portion 52 in contact with the rubber stopper 40 (more specifically, the outer surface of the formwork 25 on the rubber stopper 40).

[0034] Next, as shown in Figure 6(a), the main pressing process is performed in which the rubber stopper 40 is pressed into the hole 38 using the set pressing jig 50. In this process, the rubber stopper 40 is pressed with the pressing jig 50 until the peripheral edge of the contact portion 52 of the pressing jig 50 contacts the collar 37. Here, the axial length of the rubber stopper 40 is the same as the axial length of the hole 38 of the formwork member 30. Therefore, as described above, when the rubber stopper 40 is pressed in until the peripheral edge 52a of the contact portion 52 of the pressing jig 50 contacts the collar 37, the inner end face 40a of the rubber stopper 40 on the formwork 25 side becomes flush with the molded surface 31a of the formwork member 30. Note that the collar 37 corresponds to the "periphery of the hole in the formwork".

[0035] When the rubber stopper 40 is pushed into the hole 38 by this pushing process, the outer surface of the rubber stopper 40 (specifically the first part 45) and the inner surface of the hole 38 come into close contact, and the inner surface of the through hole 41 of the rubber stopper 40 comes into close contact with the outer surface of the protruding reinforcing bar 22 (specifically, the outer surface of the rib of the protruding reinforcing bar 22). As a result, the hole 38 is sealed by the rubber stopper 40. In addition, when the rubber stopper 40 is pushed into the hole 38, the notch 42 of the rubber stopper 40 is closed. In other words, the opposing surfaces of the rubber stopper 40 that are separated by the notch 42 are in close contact.

[0036] As described above, the pressing process is carried out in the following order: preliminary pressing process → jig setting process → final pressing process.

[0037] Furthermore, during the main pressing process, there is also a method in which the rubber stoppers 40 are fully pressed into each hole 38 at once. This method will be explained with reference to Figure 9. Figure 9 is a perspective view illustrating the process of pressing each pressing jig 50 using a long material 59.

[0038] First, the rubber stoppers 40 are temporarily pushed into each hole 38. Then, as shown in Figure 3(b), a jig setting process (see Figure 5(c)) is performed for each rubber stopper 40. After that, as shown in Figure 9, a long material 59 (for example, an angle material) is placed across the base ends of each pushing jig 50 arranged in a row, and the long material 59 is fastened to the formwork member 30 with bolts or the like. In this case, as it is fastened, the long material 59 is displaced toward the side that pushes each pushing jig 50. As a result, as the long material 59 is fastened, each pushing jig 50 is pushed by the long material 59, and as a result, each rubber stopper 40 is pushed into the back of the hole 38 by each pushing jig 50. In this case, the final pushing of each rubber stopper 40 can be done all at once, so the efficiency of the pushing work can be improved.

[0039] Next, as shown in Figure 6(b), a concrete pouring process is performed in which concrete 58 (ready-mix concrete) is poured into the formwork 25. In this case, since each hole 38 of the formwork member 30 is sealed with rubber stoppers 40, leakage of concrete 58 to the outside of the formwork 25 through the holes 38 is suppressed. After a predetermined time has elapsed since the concrete 58 was poured, the concrete 58 hardens and the lower block 12 is formed.

[0040] Next, a demolding process is performed to remove the formwork 25. In this process, each formwork member 28 to 30 that makes up the formwork 25 is removed. Here, with the rubber stopper 40 pressed into the hole 38 of the formwork member 30 (see Figure 6(b)), the first part 45 of the rubber stopper 40 is located on the inside side of the formwork 25, and the second part 46 is located on the outside side of the formwork 25. Also, as described above, since the outer diameter D2 of the second part 46 is smaller than the outer diameter D1 of the first part 45, the outer circumferential surface of the first part 45 is in close contact with the inner circumferential surface of the hole 38, while the outer circumferential surface of the second part 46 is spaced apart from the inner circumferential surface of the hole 38.

[0041] In the above configuration, for example, compared to a case where the rubber stopper is formed with a constant outer diameter and the entire outer surface of the rubber stopper is in close contact with the inner surface of the hole 38, the rubber stopper 40 is easier to remove from the hole 38. Therefore, in the demolding process, as shown in Figure 6(c), when removing the formwork member 30, the rubber stopper 40 can be easily detached from the hole 38 towards the lower block 12 as it is removed. This reduces the troublesome task of removing the rubber stopper 40 from the hole 38 after demolding.

[0042] Afterward, subsequent processes such as removing the rubber stopper 40 from the lower block 12 are carried out. This completes the series of operations.

[0043] As described in detail above, the configuration of this embodiment provides the following excellent effects.

[0044] After passing the protruding reinforcing bar 22 through the hole 38 of the formwork 25 (specifically, the formwork member 30), the rubber stopper 40 was fitted onto the outer circumference of the protruding reinforcing bar 22 through the notch 42, so that the protruding reinforcing bar 22 was passed through the through hole 41 of the rubber stopper 40. Then, with the protruding reinforcing bar 22 passed through the through hole 41, the rubber stopper 40 was pushed into the hole 38, so that the outer surface of the rubber stopper 40 and the inner surface of the hole 38 were in close contact, and the inner surface of the through hole 41 and the outer surface of the protruding reinforcing bar 22 were in close contact. The rubber stopper 40 is harder than sponge material and is difficult to compress. Therefore, in this case, radial displacement of the protruding reinforcing bar 22 can be suppressed, and as a result, localized leakage of concrete 58 due to such displacement can be suppressed. This effectively suppresses concrete leakage during pouring.

[0045] Furthermore, since the rubber stopper 40 is not porous like a sponge, even if the rubber stopper 40 adheres to the concrete (lower block 12) as the concrete 58 hardens, only the surface (end face 40a) of the rubber stopper 40 adheres, and it does not adhere firmly. As a result, the rubber stopper 40 can be easily removed after demolding, and as a result, the increase in work hours after demolding can be suppressed.

[0046] Furthermore, if the hole 38 is sealed with sponge material, after casting, the sponge material will adhere firmly to the upper end surface 15a of the side wall portion 15 of the lower block 12, requiring removal of the sponge material by peeling it off or chipping away at the upper end surface 15a. In that case, the appearance around the protruding reinforcing bar 22 on the upper end surface 15a of the lower block 12 may become unsightly. In this respect, by sealing the hole 38 with a rubber plug 40, even if the rubber plug 40 adheres to the upper end surface 15a of the lower block 12, the rubber plug 40 can be removed without chipping away at the upper end surface 15a. Therefore, it is possible to suppress the unsightly appearance of the upper end surface 15a.

[0047] The formwork member 30 has a molded surface 31a that forms the upper end surface 15a of the lower block 12. When the rubber stopper 40 is pushed into the hole 38, if the end surface 40a of the rubber stopper 40 on the inside side of the formwork 25 is misaligned with the molded surface 31a of the formwork member 30 in the pushing direction, a step will be created around the protruding reinforcing bar 22 on the upper end surface 15a of the lower block 12 that is formed after casting. In that case, the appearance of the upper end surface 15a of the lower block 12 will be poor. In this embodiment, the rubber stopper 40 is pushed into the hole 38 so that the end surface 40a of the rubber stopper 40 is flush with the molded surface 31a of the formwork member 30. This prevents the above-mentioned step from occurring on the upper end surface 15a of the lower block 12, and as a result, prevents the appearance of the upper end surface 15a from being poor.

[0048] The lower block 12 employs a double reinforcement structure, resulting in a large number of reinforcing bars 21 being placed within the formwork 25. This may make it difficult to push the rubber stopper 40 into the hole 38 from inside the formwork 25. In this embodiment, however, the protruding reinforcing bar 22 is passed through the through-hole 41 of the rubber stopper 40 outside the formwork 25, and the rubber stopper 40 is then pushed into the hole 38 from outside the formwork 25. This makes it easy to push the rubber stopper 40 in, regardless of the conditions inside the formwork 25 (for example, the number of reinforcing bars 21).

[0049] The rubber stopper 40 was pushed into the hole 38 using a pushing jig 50. Specifically, the rubber stopper 40 was pushed in with the pushing jig 50 until the peripheral edge 52a of the contact portion 52 of the pushing jig 50 contacted the collar 37 of the formwork member 30. Furthermore, the axial length of the rubber stopper 40 was set so that when the rubber stopper 40 was pushed in by the pushing jig 50 until the peripheral edge 52a of the contact portion 52 contacted the collar 37, the end face 40a of the rubber stopper 40 was flush with the molded surface 31a of the formwork member 30.

[0050] In this configuration, when the rubber stopper 40 is pushed in by the pushing jig 50 until the peripheral edge 52a of the contact portion 52 contacts the collar 37, the end face 40a of the rubber stopper 40 becomes flush with the molded surface 31a of the formwork member 30. As a result, even when the rubber stopper 40 is pushed in from outside the formwork 25, it is possible to suppress the occurrence of a step around the protruding reinforcing bar 22 on the upper end surface 15a of the lower block 12 after casting, and as a result, it is possible to suppress the appearance of the upper end surface 15a.

[0051] - The outer diameter D2 of the second portion 46 of the rubber stopper 40 is made smaller than the outer diameter D1 of the first portion 45, and the axial length L2 of the second portion 46 is made longer than the axial length L1 of the first portion 45. This makes it easier to detach the rubber stopper 40 from the hole 38 of the formwork member 30 towards the lower block 12 when removing the formwork member 30. Therefore, the troublesome work of removing the rubber stopper 40 from the hole 38 after demolding is further reduced.

[0052] (Second embodiment) In this embodiment, the method for manufacturing concrete blocks according to the present invention is embodied as a method for manufacturing L-shaped blocks that constitute a waterway. Figure 10 is a cross-sectional view showing the waterway.

[0053] As shown in Figure 10, the waterway 61 is formed in a U-shape with an upward-opening cross-section. The waterway 61 comprises a pair of L-shaped blocks 62 with an L-shaped cross-section. The L-shaped blocks 62 are made of precast concrete and are manufactured in a manufacturing plant. The L-shaped blocks 62 have a base plate portion 63 and side wall portions 64 that rise upward from the base plate portion 63.

[0054] Multiple reinforcing bars 65 (see also Figure 11) are embedded inside the L-shaped block 62. The reinforcing bars 65 consist of deformed reinforcing bars and are arranged in a double reinforcement configuration. Among the multiple reinforcing bars 65 are protruding reinforcing bars 66 that partially protrude laterally from the front surface 63a of the base plate portion 63 of the L-shaped block 62. Multiple protruding reinforcing bars 66 are provided on the base plate portion 63. Note that the L-shaped block 62 corresponds to a "concrete block," and the front surface 63a of the base plate portion 63 corresponds to a "predetermined surface of the concrete block."

[0055] At the installation site, each L-shaped block 62 is installed with its base slab 63 facing each other. The base slabs 63 of each L-shaped block 62 are spaced apart, and cast-in-place concrete is poured between these base slabs 63. Once the cast-in-place concrete hardens, each L-shaped block 62 is integrated through the hardened concrete slab 68. For convenience, in Figure 10, the concrete slab 68 is shown as a dashed line.

[0056] Next, the manufacturing method of the L-shaped block 62 produced in the manufacturing plant will be described. The L-shaped block 62 is formed using a formwork 70 for precast concrete. First, this formwork 70 will be described with reference to Figure 11. Figure 11 is a cross-sectional view showing the state in which reinforcing bars 65 are arranged inside the formwork 70. In this embodiment, the L-shaped block 62 is formed so that the protruding reinforcing bars 66 protrude downwards.

[0057] As shown in Figure 11, the formwork 70 is composed of a plurality of formwork members 71 to 73. The plurality of formwork members 71 to 73 include a formwork member 73 that forms the front end surface 63a of the bottom plate portion 63 of the L-shaped block 62. The formwork member 73 is formed from a long material having a U-shaped cross-section and has a plate portion 74 that forms the front end surface 63a and a pair of plate portions 75 that extend from both ends of the plate portion 74 in the width direction.

[0058] Multiple holes 76 are formed in the plate portion 74. A metal collar 77 is attached to each hole 76. The collar 77 is formed in an annular shape and is welded to the plate portion 74 while positioned within the hole 76. In this case, the inner end face 77a of the collar 77 and the inner plate surface 74a of the plate portion 74 are flush. The flush end face 77a of the collar 77 and the plate surface 74a of the plate portion 74 form a molded surface 79 that forms the front end surface 63a of the base plate portion 63.

[0059] A hole 81 is formed on the inside of the collar 77 for passing the protruding reinforcing bar 66 through. The hole 81 has a circular cross-section. The inner circumferential surface of the hole 81 includes a tapered surface 82 and a non-tapered surface 83. The tapered surface 82 is formed in a tapered shape such that the diameter of the hole 81 decreases toward the outside of the formwork 70.

[0060] The non-tapered surface 83 is located on the interior side of the formwork 70, and is continuous with the tapered surface 82. The diameter of the holes 81 in the non-tapered surface 83 is constant, and its diameter is the same as the maximum diameter of the holes in the tapered surface 82. Furthermore, the axial length of the non-tapered surface 83 is less than or equal to 1 / 3 of the axial length of the tapered surface 82. The corners between the inner circumferential surface of the holes 81 in the collar 77 and the outer surface of the formwork 70 are chamfered.

[0061] Next, the manufacturing method of the L-shaped block 62 will be explained based on Figures 12 and 13, in addition to Figure 11. Figures 12 and 13 are both cross-sectional views illustrating the manufacturing method of the L-shaped block 62.

[0062] First, as shown in Figure 11, a reinforcement step is performed in which each reinforcing bar 65, including multiple protruding reinforcing bars 66, is placed inside the formwork 70. In the reinforcement step, as shown in Figure 12(a), each protruding reinforcing bar 66 is passed through the hole 81 of the formwork member 73. As a result, a portion of each protruding reinforcing bar 66 protrudes to the outside (downward) of the formwork 70.

[0063] Next, a preparation step is performed to prepare the rubber stopper 90. Here, the structure of the rubber stopper 90 will be explained based on Figure 14. Figure 14 shows (a) a plan view of the rubber stopper 90 and (b) a front view of the rubber stopper 90. Note that the preparation step may be performed before the reinforcement step.

[0064] As shown in Figures 14(a) and (b), the rubber stopper 90 is formed in a columnar shape with a circular cross-section. The rubber stopper 90 is made of a non-foaming rubber material, such as chloroprene rubber (CR rubber). The rubber stopper 90 is solid and does not contain air bubbles inside. The material of the rubber stopper 90 does not necessarily have to be chloroprene rubber; for example, it may be silicone rubber, soft PVC, or thermoplastic elastomer (e.g., TPE, TPV, etc.).

[0065] The rubber stopper 90 has a through hole 91 that penetrates the rubber stopper 90 in the axial direction, and a notch 92 that is cut from the inner circumferential surface of the through hole 91 to the outer circumferential surface of the rubber stopper 90. The through hole 91 is formed in the center of the rubber stopper 90 and its diameter is constant. The diameter of the through hole 91 is the same as or slightly smaller than the outer diameter of the protruding reinforcing bar 66. The notch 92 is cut over the entire axial area of ​​the rubber stopper 90.

[0066] The rubber stopper 90 has a tapered portion 94 and a non-tapered portion 95 arranged in the axial direction. The tapered portion 94 includes an end face 90a formed at one end of the rubber stopper 90 in the axial direction, and the non-tapered portion 95 includes an end face 90b formed at the other end of the rubber stopper 90 in the axial direction.

[0067] The tapered portion 94 is formed in a tapered shape such that its outer diameter decreases toward the end face 90a side (one end) in the axial direction. In other words, the tapered portion 94 is formed such that its outer diameter decreases as it moves away from the non-tapered portion 95. On the other hand, the outer diameter of the non-tapered portion 95 is kept constant. The outer diameter of the non-tapered portion 95 is the same as the maximum outer diameter of the tapered portion 94. In this case, the outer circumferential surface of the non-tapered portion 95 and the outer circumferential surface of the tapered portion 94 are continuous. Also, the axial length of the non-tapered portion 95 is 1 / 3 or less of the axial length of the tapered portion 94.

[0068] Next, as shown in Figure 12(b), a threading process is performed inside the formwork 70, where the rubber stopper 90 is fitted onto the outer circumference of the protruding reinforcing bar 66 through the notch 92 (see Figure 14(a)), thereby passing the protruding reinforcing bar 66 through the through hole 91 of the rubber stopper 90. In this process, for example, the inside of the formwork 70 is opened by removing one of the formwork members 71 or 72, and the rubber stopper 90 is fitted onto the outer circumference of the protruding reinforcing bar 66 inside the formwork 70 through the opened section. In the threading process, the rubber stopper 90 is fitted onto the protruding reinforcing bar 66 with the end face 90a side (in other words, the smaller diameter side of the tapered portion 94) facing the hole 81 of the formwork member 73.

[0069] Next, as shown in Figure 12(c), with the protruding reinforcing bar 66 passed through the through-hole 91 of the rubber stopper 90, a pushing process is performed in which the rubber stopper 90 is pushed into the hole 81 of the formwork member 73. In this process, the rubber stopper 90 is pushed into the hole 81 from the inside of the formwork 70 with its end face 90a side facing forward. Specifically, the rubber stopper 90 is pushed into the hole 81 so that the end face 90b on the inside side of the formwork 70 is flush with the molded surface 79 of the formwork member 73. The rubber stopper 90 may be pushed in by hand or using a dedicated pushing jig.

[0070] When the rubber stopper 90 is pushed into the hole 81 during the pushing process, the outer surface of the rubber stopper 90 and the inner surface of the hole 81 come into close contact, and the inner surface of the through-hole 91 of the rubber stopper 90 comes into close contact with the outer surface of the protruding reinforcing bar 66 (more specifically, the outer surface of the rib of the protruding reinforcing bar 66). As a result, the hole 81 is sealed by the rubber stopper 90. More specifically regarding the contact between the outer surface of the rubber stopper 90 and the inner surface of the hole 81, the outer surface of the tapered portion 94 of the rubber stopper 90 comes into close contact with the tapered surface 82 of the hole 81, and the outer surface of the non-tapered portion 95 of the rubber stopper 90 comes into close contact with the non-tapered surface 83 of the hole 81. When the rubber stopper 90 is pushed into the hole 81, the notch 92 of the rubber stopper 90 is closed.

[0071] Furthermore, the pressing process and the aforementioned passing process are performed for each hole 81 of the formwork member 73, respectively. As a result, each hole 81 is sealed with a rubber stopper 90.

[0072] Next, as shown in Figure 13(a), a pouring process is carried out in which concrete 98 (ready-mix concrete) is poured into the formwork 70. In this case, since each hole 81 of the formwork member 73 is sealed with rubber plugs 90, leakage of concrete 98 to the outside of the formwork 70 through the holes 81 is suppressed. After a predetermined time has elapsed since the concrete 98 was poured, the concrete 98 hardens and the L-shaped block 62 is formed.

[0073] Next, a demolding process is performed to remove the formwork 70. In this process, each formwork member 71 to 73 that makes up the formwork 70 is removed.

[0074] Here, the tapered portion 94 of the rubber stopper 90 has a larger outer diameter towards the inside of the formwork 70 (in other words, towards the L-shaped block 62). Therefore, in the demolding process, as shown in Figure 13(b), when the formwork member 73 is removed, the rubber stopper 90 can be easily detached from the hole 81 towards the L-shaped block 62 as the formwork member is removed. This reduces the troublesome task of removing the rubber stopper 90 from the hole 81 after demolding.

[0075] Afterward, subsequent processes such as removing the rubber stopper 90 from the L-shaped block 62 are carried out. This completes the series of operations.

[0076] As described in detail above, the configuration of this embodiment provides the following excellent effects.

[0077] - By passing the protruding reinforcing bar 66 through the through-hole 91 of the rubber stopper 90 and then pushing the rubber stopper 90 into the hole 81 of the formwork 70 (specifically, the formwork member 73), the outer surface of the rubber stopper 90 and the inner surface of the hole 81 are brought into close contact, and the inner surface of the through-hole 91 and the outer surface of the protruding reinforcing bar 66 are brought into close contact. As a result, as in the first embodiment described above, concrete leakage during pouring can be effectively suppressed, and the increase in work hours after demolding can be suppressed.

[0078] The rubber stopper 90 was pushed into the hole 81 so that the inner end face 90b of the rubber stopper 90 on the formwork 70 was flush with the molded surface 79 of the formwork member 73. This prevents the formation of a step around the protruding reinforcing bar 66 on the tip surface 63a of the L-shaped block 62 after casting. As a result, the appearance of the tip surface 63a of the L-shaped block 62 can be prevented from becoming unsightly.

[0079] The rubber stopper 90 has a tapered portion 94 formed such that its outer diameter decreases toward the end face 90a side (corresponding to one end) in the axial direction. In addition, the inner circumferential surface of the hole 81 in the formwork 70 includes a tapered surface 82 formed such that the diameter of the hole 81 decreases toward the outside side of the formwork 70, corresponding to the outer circumferential surface of the tapered portion 94. Inside the formwork 70, the protruding reinforcing bar 66 is passed through the through hole 91 of the rubber stopper 90 with the end face 90a side facing the hole 81 side, and in that state, the rubber stopper 90 is pushed into the hole 81 from inside the formwork 70 with the end face 90a side facing the tip.

[0080] According to the above configuration, the rubber stopper 90 is less likely to fall out of the hole 81 to the outside of the formwork 70 when the concrete 98 is poured. In particular, in this embodiment, since the outside side of the formwork 70 is lower than the hole 81, it is considered that the rubber stopper 90 is likely to fall out downward from the hole 81 when the concrete is poured. However, according to the above configuration in which the rubber stopper 90 having a tapered portion 94 is pushed into the hole 81, it is possible to make it less likely for the rubber stopper 90 to fall out downward even in such a case.

[0081] The rubber stopper 90 has a non-tapered portion 95 on the end face 90b side (corresponding to the opposite side from one end) of the tapered portion 94, which has a constant outer diameter and is the same as the maximum outer diameter of the tapered portion 94. In this case, when pushing the rubber stopper 90 into the hole 81 of the formwork member 73, it is possible to prevent pushing the rubber stopper 90 too far into the hole 81. If the rubber stopper 90 is pushed too far in, there is a risk that a step (indentation) will occur around the protruding reinforcing bar 66 on the tip surface 63a of the L-shaped block 62 after molding. In this respect, the above configuration makes it less likely for such a step to occur, and as a result, it is possible to prevent the tip surface 63a of the L-shaped block 62 from looking bad.

[0082] (Other embodiments) The present invention is not limited to the embodiments described above, and may be implemented, for example, as follows.

[0083] In the first embodiment described above, the rubber stopper 40 was pushed into the hole 38 using the pushing jig 50, but the rubber stopper 40 may also be pushed directly into the hole 38 by hand.

[0084] In the first embodiment described above, the rubber stopper 40 may be formed with a constant outer diameter.

[0085] In the second embodiment described above, the outer diameter of the non-tapered portion 95 of the rubber stopper 90 may be larger than the maximum outer diameter of the tapered portion 94. In this case as well, it is possible to prevent the rubber stopper 90 from being pushed too far into the hole 81. In this case, the non-tapered surface 83 of the hole 81 of the formwork member 73 is made larger to correspond to the outer diameter of the non-tapered portion 95.

[0086] Alternatively, the rubber stopper 90 may not have a non-tapered portion, and the entire rubber stopper 90 may be made into a tapered portion.

[0087] In the first embodiment described above, the present invention was applied to the lower block 12 for the box culvert, and in the second embodiment described above, the present invention was applied to the L-shaped block 62 for the waterway. However, the present invention may also be applied to concrete blocks other than these blocks 12 and 62. In short, the present invention can be applied to any concrete block provided with protruding reinforcing bars. [Explanation of Symbols]

[0088] 12...Lower block (concrete block), 21...Reinforcement bar, 22...Protruding reinforcement bar, 25...Formwork, 31a...Molded surface, 38...Hole, 40...Rubber stopper, 41...Through hole, 42...Notch, 45...First part, 46...Second part, 50...Pushing jig, 52...Contact part, 54...Through hole, 62...L-shaped block (concrete block), 65...Reinforcement bar, 66...Protruding reinforcement bar, 70...Formwork, 79...Molded surface, 81...Hole, 90...Rubber stopper, 91...Through hole, 92...Notch, 94...Tapered part, 95...Non-tapered part.

Claims

1. A method for manufacturing a concrete block in which reinforcing bars are embedded inside, and the reinforcing bars include protruding reinforcing bars that partially protrude outwards, The formwork for shaping the concrete block is provided with holes for passing the protruding reinforcing bars. A rebar placement step involves arranging the reinforcing bars within the formwork and passing the protruding reinforcing bars through the holes in the formwork, A preparation step of preparing a columnar rubber stopper having a circular cross-section, wherein the rubber stopper has a through hole that penetrates the rubber stopper in the axial direction and a notch cut from the inner circumferential surface of the through hole to the outer circumferential surface of the rubber stopper, After the reinforcement placement process and the preparation process, the rubber stopper is fitted onto the outer circumference of the protruding reinforcing bar through the notch, and the protruding reinforcing bar is passed through the through hole in a passing process. A pressing step in which the rubber stopper is pushed into the hole with the protruding reinforcing bar passed through the through hole, so that the outer surface of the rubber stopper is in close contact with the inner surface of the hole, and the inner surface of the through hole is in close contact with the outer surface of the protruding reinforcing bar, After the pressing step, a pouring step is performed in which concrete is poured into the formwork, Equipped with, The rubber stopper has a tapered portion formed such that its outer diameter decreases toward one end in the axial direction. The inner circumferential surface of the hole includes a tapered surface formed in accordance with the outer circumferential surface of the tapered portion, such that the diameter of the hole decreases toward the outside of the formwork. In the aforementioned through-process, the rubber stopper is fitted inside the formwork so that one end faces the hole, and the rubber stopper is fitted onto the outer circumference of the protruding reinforcing bar. In the pressing step, the rubber stopper is pushed into the hole from inside the mold with one end facing the tip, thereby bringing the outer surface of the tapered portion and the tapered surface into close contact. A method for manufacturing a concrete block, wherein the rubber stopper has a non-tapered portion on the side opposite to the one end of the tapered portion in the axial direction, the non-tapered portion having a constant outer diameter and being the maximum outer diameter of the tapered portion.

2. A method for manufacturing a concrete block in which reinforcing bars are embedded inside, and the reinforcing bars include protruding reinforcing bars that partially protrude outwards, The formwork for shaping the concrete block is provided with holes for passing the protruding reinforcing bars. A rebar placement step involves arranging the reinforcing bars within the formwork and passing the protruding reinforcing bars through the holes in the formwork, A preparation step of preparing a columnar rubber stopper having a circular cross-section, wherein the rubber stopper has a through hole that penetrates the rubber stopper in the axial direction and a notch cut from the inner circumferential surface of the through hole to the outer circumferential surface of the rubber stopper, After the reinforcement placement process and the preparation process, the rubber stopper is fitted onto the outer circumference of the protruding reinforcing bar through the notch, and the protruding reinforcing bar is passed through the through hole in a passing process. A pressing step in which the rubber stopper is pushed into the hole with the protruding reinforcing bar passed through the through hole, so that the outer surface of the rubber stopper is in close contact with the inner surface of the hole, and the inner surface of the through hole is in close contact with the outer surface of the protruding reinforcing bar, After the pressing step, a pouring step is performed in which concrete is poured into the formwork, Equipped with, The aforementioned protruding reinforcing bar protrudes from a predetermined surface of the concrete block, The formwork has a molding surface that forms the predetermined surface, through which the hole is opened. In the aforementioned through-process, the rubber stopper is fitted onto the outer circumference of the protruding reinforcing bar outside the formwork. In the pressing step, the rubber stopper is pressed into the hole from outside the mold using a pressing jig. The pressing jig is cylindrical in shape, having an insertion hole through which the protruding reinforcing bar is inserted, and its tip is an annular contact portion that abuts against the rubber stopper. The contact portion is formed such that its peripheral edge protrudes from the rubber stopper. In the pressing step, the pressing jig is set with the protruding reinforcing bar inserted into the insertion hole and the contact portion in contact with the rubber stopper, and in this set state, the rubber stopper is pressed with the pressing jig until the peripheral edge of the contact portion contacts the peripheral edge of the hole in the formwork. A method for manufacturing a concrete block, wherein the length of the rubber stopper in the axial direction is set such that, when the rubber stopper is pressed by the pressing jig until the peripheral edge of the contact portion contacts the peripheral edge of the hole in the formwork, the end face of the rubber stopper on the inner side of the formwork is flush with the molded surface.

3. The rubber stopper has a first portion located on the inside of the formwork and a second portion located on the outside of the formwork when it is pushed into the hole by the pushing process. The first portion is the part whose outer surface is in close contact with the inner surface of the hole, The method for manufacturing a concrete block according to claim 2, wherein the second portion has an outer diameter smaller than the outer diameter of the first portion, and the outer surface is spaced apart from the inner surface of the hole.

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