Concrete Structure

Abstract

To provide a concrete structure where bamboo reinforcement bars are used allowing bond strength between the reinforcement bars and concrete to be improved.SOLUTION: A concrete structure is provided with: a concrete part 1; and reinforcement bars 3 buried in the concrete part 1, wherein the reinforcement bar 3 is provided with a bamboo bar 3A made of bamboo cut in a fiber direction of a pole; and a bamboo piece 3B (projected member) fixed on the bamboo bar 3A. The bamboo bar 3A comprises a strip part 31 which is a pole part, and a plurality of convex parts 32 which are node parts, and the bamboo piece 3B is fixed between adjacent convex parts 32, 32.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to concrete structures. [Background technology]

[0002] In recent years, efforts to achieve the Sustainable Development Goals (SDGs) have been underway in various fields, and in the concrete sector as well, there is a demand for technologies that reduce the environmental impact. Patent Document 1 discloses a secondary concrete product that uses bamboo, a renewable resource, as a core material. The use of such a secondary concrete product can reduce the environmental impact. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2010-196345 A Summary of the Invention [Problem to be solved by the invention]

[0004] When using bamboo as a reinforcing material for concrete structures, it is desirable to increase the adhesive strength to the concrete, as in the case of reinforcing bars. In the secondary concrete product of Patent Document 1, high-fluidity concrete is used to increase the adhesive strength between the concrete and the bamboo, but the use of high-fluidity concrete limits the range of application and may increase the material cost. From this perspective, the objective of the present invention is to provide a concrete structure reinforced with bamboo reinforcing bars, which can increase the bond strength between the reinforcing bars and the concrete. [Means for solving the problem]

[0005] The present invention, which solves the above-mentioned problems, is a concrete structure comprising a concrete portion and a reinforcing bar embedded in the concrete portion, the reinforcing bar being made of a bamboo rod cut along the fiber direction of the bamboo rod and a protrusion fixed to the bamboo rod. Materials and The present invention is characterized in that it is provided with:

[0006] According to the present invention, the protrusion Material This creates more unevenness on the surface of the reinforcing bar, which increases the adhesion strength (pull-out resistance) between the reinforcing bar and concrete. Moreover, bamboo, a renewable resource, is used to form the reinforcing bars, which are then embedded in the concrete, allowing carbon dioxide to be stored (fixed) within the concrete structure, thereby contributing to reducing the burden on the environment. Furthermore, bamboo poles can be obtained simply by cutting along the direction of the fibers, which is expected to reduce energy consumption (carbon dioxide emissions) during component manufacturing. Furthermore, by using bamboo, which grows quickly and is easy to obtain, material costs can be reduced, and the project can also contribute to expanding the distribution of bamboo, thereby helping to revive the devastated Satoyama environment. Furthermore, since the reinforcing bars themselves are lightweight, they are easy to handle on-site. In addition, the protruding member may be made of wood, resin, steel, etc., in addition to bamboo.

[0007] It is preferable that the bamboo stick has a belt-shaped portion which is a shaft portion and a plurality of protruding portions which are joint portions. In this case, the protruding portion is provided between the adjacent protruding portions. Materials It is preferable to place By doing this, the bamboo sticks can be attached to the protruding parts (nodes) as well as the protruding parts. Material This creates more unevenness on the surface of the reinforcing bar, which increases the adhesion strength (pull-out resistance) between the reinforcing bar and concrete.

[0008] If the protruding members are fixed to the bamboo sticks using nails or screws, there is a possibility that the bamboo sticks may crack, and therefore it is preferable that the protruding members are glued to the bamboo sticks.

[0009] The protruding members are preferably plate-shaped bamboo pieces or rod-shaped bamboo pins. Using bamboo protruding members can further contribute to reducing the environmental impact. Since the bamboo sticks formed from the bamboo shafts have an arc-shaped cross section, when cutting the bamboo shafts to form plank-shaped bamboo pieces, it is preferable to arrange the bamboo pieces so that their fibers are in the same direction as the fibers of the bamboo sticks. In this way, the adhesive surface of the bamboo pieces will fit along the adhesive surface of the bamboo stick, which has an arc-shaped cross section, making it easier to glue the two together. In addition, when cutting bamboo stalks to form rod-shaped bamboo pins, it is preferable to fit the pins into holes formed in the bamboo sticks. This makes it easier to fix the bamboo pins to the bamboo sticks. Effect of the Invention

[0010] According to the present invention, the adhesive strength between reinforcing bars made of bamboo and concrete can be increased, thereby expanding the range of applications and contributing to reducing the environmental burden. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a cross-sectional view showing a concrete structure according to an embodiment. [Diagram 2] FIG. [Diagram 3] 13(a) and 13(b) are perspective views showing joints of reinforcing bars. [Figure 4] 1(a) and (b) are diagrams illustrating a method for constructing a concrete structure according to an embodiment. [Diagram 5] 5(a) and 5(b) are cross-sectional views showing modified examples of the concrete structure according to the embodiment. [Figure 6] FIG. 13(a) is a cross-sectional view showing a modified example of the reinforcing bar, and FIG. 13(b) is a perspective view showing another modified example of the reinforcing bar. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] A concrete structure C according to an embodiment of the present invention constitutes a crest (frame) formed on a cut slope or a natural slope, and as shown in Fig. 1, comprises a concrete part 1, and a void-forming material 2 and a reinforcing bar 3 embedded in the concrete part 1. Since the crest receives force from the natural ground, the natural ground side of the neutral axis becomes a compression region (region where compressive stress occurs). In this embodiment, the concrete structure C is applied to a crenellation frame, but there is no limitation on the use or shape of the concrete structure C, and it can be applied to rod-shaped (beam or column) structures, plate-shaped (slab or wall) or block-shaped structures, etc. In addition, in this embodiment, the concrete structure C is formed by cast-in-place concrete, but it may be a precast concrete structure.

[0013] The concrete portion 1 is made of concrete containing cement, aggregate, admixture, water reducing agent, etc. There is no limitation on the type and mixture of materials used.

[0014] The void forming material 2 includes a bamboo cylinder 20. Inside the void forming material 2, a hollow portion V is formed. There is no limit to the type of bamboo that can be used to make the bamboo tube 20; madake, moso bamboo, atadake, mechidake, etc. can be used, but madake and moso bamboo are preferred because they are widely distributed throughout the country and can be procured at low cost. The bamboo tube 20 is made by cutting bamboo into rings, and has a bamboo stick 21 and at least one node 22. It is preferable that the node 22 is left as it is in its natural state without being drilled or cut. Two or more nodes 22 may be left on one bamboo tube 20.

[0015] The void-forming material 2 of this embodiment is composed of two bamboo tubes 20, 20. In this embodiment, it is composed of two bamboo tubes 20, 20, one large and one small, with different outer diameters, and one bamboo tube 20 (the upper bamboo tube 20 in FIG. 1) is inserted into the rod 21 of the other bamboo tube 20 (the lower bamboo tube 20 in FIG. 1). In this embodiment, only the rod 21 of the other bamboo tube 20 is inserted into the one bamboo tube 20, and the gap between the inner peripheral surface of the rod 21 of the one bamboo tube 21 and the outer peripheral surface of the other bamboo tube 21 is sealed with a caulking material. The node 22 of the other bamboo tube 20 may be disposed inside the one bamboo tube 20. The node 22 of the other bamboo tube 20 may also be abutted against the open end of the one bamboo tube 20. In this case, it is preferable to seal the gap between the open end of the one bamboo tube 20 and the node 22 of the other bamboo tube 20. In this embodiment, the bamboo tube 20 with a larger outer diameter is placed on the lower side, but the bamboo tube 20 with a smaller outer diameter may also be placed on the lower side.

[0016] The void-forming material 2 of the present embodiment has two nodes 22, 22. One of the nodes 22 is disposed in a region of the concrete part 1 where compressive stress occurs (in the present embodiment, a region closer to the natural ground than the neutral axis of the concrete structure C).

[0017] The overall length (total height) of the void forming material 2 is set appropriately according to the dimensions and shape of the concrete structure C. When adjusting the overall length of the void forming material 2 on-site, the rod 21 may be cut or the amount of one bamboo tube 20 inserted into the other bamboo tube 20 may be adjusted.

[0018] The reinforcing bars 3 bear the tensile stress generated in the concrete section 1, and as shown in Fig. 2, are made up of bamboo sticks 3A and bamboo pieces 3B fixed to the bamboo sticks 3A. There are no restrictions on the type of bamboo that can be used to make the reinforcing bars 3, and an appropriate one can be selected from madake bamboo, moso bamboo, atsushi bamboo, mechi bamboo, etc. depending on the required tensile strength, but madake bamboo and moso bamboo are preferred because they are widely distributed throughout Japan and can be procured at low cost.

[0019] The bamboo stick 3A is made by cutting the bamboo along the fiber direction (longitudinal direction of the bamboo) and has a belt-like part 31 which is the shaft part and a protruding part 32 which is the node part. The belt-like part 31 is made by splitting a cylindrical bamboo vertically, so it has an arc-shaped cross section. The protruding part 32 may be made by using the node remaining in the split bamboo as it is, or it may be made by cutting off a part of the node and shaping it into an appropriate shape.

[0020] The bamboo pieces 3B are protruding members that increase the adhesive strength between the reinforcing bars 3 and concrete, and are adhered to the strip-shaped portion 31 of the bamboo stick 3A. The bamboo pieces 3B are positioned away from the protruding portions 32 (nodes) of the bamboo stick 3A. The bamboo pieces 3B are positioned between adjacent protruding portions 32, 32, with a gap between the protruding portions 32 and the other bamboo pieces 3B. It is preferable that the number of bamboo pieces 3B positioned between adjacent protruding portions 32, 32 (approximately 40 to 50 cm) be appropriately determined according to the adhesive strength required for the bamboo stick 3A.

[0021] The bamboo pieces 3B are formed by cutting the bamboo shaft into small pieces. The bamboo pieces 3B in this embodiment are plate-shaped. The bamboo pieces 3B arranged on the outside of the bamboo stick 3A (the outer peripheral surface side of the shaft) have a shape (arc-shaped cross section) that makes use of the cylindrical surface of the inner circumference of the shaft, and are glued to the outer surface of the bamboo stick 3A (the lower surface in FIG. 2) with adhesive, with the fiber direction of the bamboo pieces 3B and the fiber direction of the bamboo stick 3A aligned. The bamboo pieces 3B arranged on the inside of the bamboo stick 3A (the inner peripheral surface side of the shaft) have a shape (arc-shaped cross section) that makes use of the cylindrical surface of the outer circumference of the shaft, and are glued to the inner surface of the bamboo stick 3A (the upper surface in FIG. 2) with adhesive, with the fiber direction of the bamboo pieces 3B and the fiber direction of the bamboo stick 3A aligned. If the curvature of the adhesive surface of the bamboo stick 3A and the adhesive surface of the bamboo pieces 3B are significantly different, the curvatures may be matched by scraping one of the surfaces. In addition, at least one of the adhesive surface of the bamboo stick 3A and the adhesive surface of the bamboo piece 3B may be polished to increase smoothness.

[0022] When two bamboo sticks 3A, 3A are joined in the longitudinal direction, it is preferable to use a lap joint in which the ends of the bamboo sticks 3A, 3A are lapped together as shown in Figures 3(a) and 3(b). The length of the lap joint can be set appropriately depending on the magnitude of the tensile force acting on the bamboo stick 3B. A lap joint in which the two bamboo sticks 3A, 3A are simply lapped together is acceptable, but as shown in Figure 3(a), the outer surface (outer surface of the stick) of one strip 31 and the inner surface (inner surface of the stick) of the other strip 31 may be bonded together with an adhesive, or as shown in Figure 3(b), the side end surfaces of the strips 31, 31 may be bonded together with an adhesive.

[0023] All of the reinforcing materials arranged in the concrete section 1 may be bamboo reinforcing bars 3, or some of the reinforcing materials may be steel bars or steel frames.

[0024] 4(a)-(b) show an example of a construction procedure when constructing a concrete structure C, which is a slope reinforcement framework, on-site. When constructing a concrete structure C on-site, as shown in FIG. 4(a), first, a leveling concrete 4 is formed on the ground. After the leveling concrete 4 is cured, a formwork (not shown) is placed on the leveling concrete 4, and then, as shown in FIG. 4(b), a void-forming material 2 and a reinforcing bar 3 are placed on the leveling concrete 4. The void-forming material 2 and the reinforcing bar 3 may be placed separately, or a plurality of void-forming materials 2, 2, ... may be attached to the reinforcing bar 3 and installed together. When attaching the void-forming material 2 to the reinforcing bar 3, it is preferable to use a string made of plants such as bamboo skin processed into a string shape from the viewpoint of reducing the environmental load, but an adhesive, a wire, etc. may also be used. After that, the height of the void-forming material 2 is adjusted, and the gaps between the rods 21, 21 are sealed with a caulking material, and cast-in-place concrete is poured into the formwork (not shown).

[0025] The concrete structure C constructed in this way has a hollow portion V, which allows for weight reduction and a reduction in the amount of concrete. In addition, the void-forming material 2 and the reinforcing material 3 are also lightweight, which makes it easy to carry them in and install them. Furthermore, because the void-forming material 2 and reinforcing material 3 are made using bamboo, which absorbs carbon dioxide as it grows, carbon dioxide can be stored (fixed) in the concrete structure C. Furthermore, the components of the void-forming material 2 and reinforcing material 3 (bamboo tubes 20, bamboo sticks 3A, bamboo pieces 3B) can be obtained simply by cutting the bamboo to an appropriate length, so it is expected that the amount of energy consumed (carbon dioxide emissions) during component manufacturing will be reduced. Furthermore, by using bamboo, which grows quickly and is easy to obtain, material costs can be reduced, and furthermore, by contributing to the expansion of bamboo distribution, it will also be possible to contribute to the revival of the devastated Satoyama environment.

[0026] In this embodiment, at least one node 22 of the void-forming material 2 is arranged in the compression region (region where compressive stress occurs) of the concrete portion 1, so that the node 22 bears the compressive stress (including bending compressive stress) acting on the concrete portion 1, thereby preventing a decrease in the rigidity of the concrete structure C.

[0027] The void-forming material 2 can be easily processed even by hand, making it easy to manufacture and adjust its dimensions.Furthermore, since it is configured by inserting one of two bamboo tubes 20, 20 into the other, the overall length of the void-forming material 2 can be easily adjusted.

[0028] Furthermore, if the reinforcing bars 3 are attached to the void-forming material 2 using bamboo bark or the like, it becomes easier to position the void-forming material 2 and it is possible to prevent the void-forming material 2 from shifting out of position when the concrete is poured.

[0029] In the reinforcing material 3 of this embodiment, the protrusions are formed by the bamboo pieces 3B, so the adhesive strength (pulling resistance) between the reinforcing bar 3 and concrete can be increased compared to when it is made of only the bamboo sticks 3A. Also, because the bamboo pieces 3B are bonded to the bamboo sticks 3A using adhesive, cracks are less likely to occur in the bamboo sticks 3A and bamboo pieces 3B compared to when the bamboo pieces 3B are fixed to the bamboo sticks using nails or screws.

[0030] In this embodiment, the void-forming material 2 formed by combining two bamboo tubes 20, 20 is exemplified, but as shown in FIG. 5, a void-forming material 2 formed by a single bamboo tube 20 may also be used. Also, as shown in FIG. 5(a), a void-forming material 2 may be provided so as to penetrate the concrete portion 1. 5(b), the length of the void-forming material 2 may be made smaller than the thickness of the concrete portion 1, and concrete may be filled above the joints 22. If the void-forming material 2 is open only on the lower surface of the concrete portion 1, water, soil, and the like are less likely to accumulate inside the void-forming material 2.

[0031] In this embodiment, plate-shaped bamboo pieces 3B are exemplified as protruding members for increasing the adhesive strength of the reinforcing bars 3, but rod-shaped bamboo pins 3C may also be fixed as shown in Fig. 6(a). The bamboo pins 3C are rod-shaped members formed by cutting a bamboo rod along the fiber direction. The bamboo pins 3C are preferably inserted into holes provided in the rod 31 of the bamboo rod 3A and protrude from the inner and outer surfaces of the rod 31. When inserting the bamboo pins 3C into the holes, adhesive may be applied to the circumferential surface of the bamboo pins 3C or the walls of the holes. In this embodiment, the protruding members are made of bamboo, but protruding members made of wood, resin, steel, or other materials other than bamboo may also be used.

[0032] Also, as shown in Fig. 6(b), the adhesive strength may be increased by providing a hole 31a in the bamboo stick 3A. The hole 31a is disposed between adjacent protrusions 32, 32. In Fig. 6(b), only one hole 31a is formed between adjacent protrusions 32, 32, but multiple holes 31a may be formed or may be used in combination with a protruding member. Although the hole 31a in FIG. 6(b) is a through hole, it may be a bottomed hole.

[0033] Although not shown in the drawings, a plurality of void-forming materials 2 may be bundled (closely packed) and arranged. For example, if a plurality of void-forming materials 2 are arranged in a honeycomb core shape, the proportion of hollow spaces in the concrete structure C increases, so that the weight of the concrete structure C can be reduced. Furthermore, if weight reduction is not required, the void-forming material 2 may be omitted. [Explanation of symbols]

[0034] C Concrete structure 1 Concrete section 2 Void forming material 20 Bamboo tube 21 Rod Verse 21 3 Reinforcement 3A bamboo stick 3B Bamboo piece (protruding member) 3C Bamboo pin (protruding part) 31a Hole

Claims

1. Concrete section, A concrete structure comprising a reinforcing bar embedded in the concrete portion, The reinforcing bar includes a bamboo rod cut along the fiber direction of the bamboo rod, and a protruding member bonded to the bamboo rod. The bamboo stick has a belt-shaped portion which is a shaft portion and a plurality of protruding portions which are joint portions, The protruding member is a plate-shaped piece of bamboo formed by cutting a bamboo stick, and is disposed between the adjacent protruding portions, A concrete structure characterized in that the bamboo pieces are arranged so that the fiber direction of the bamboo sticks is the same as the fiber direction of the bamboo pieces.

2. Concrete section, A concrete structure comprising a reinforcing bar embedded in the concrete portion, The reinforcing bar includes a bamboo rod cut along the fiber direction of the bamboo rod, and a protruding member bonded to the bamboo rod. The bamboo stick has a belt-shaped portion which is a shaft portion and a plurality of protruding portions which are joint portions, The protruding members are disposed between adjacent ones of the protruding portions, The bamboo stick has a through hole formed therein, A concrete structure characterized in that the protruding members are rod-shaped bamboo pins formed by cutting bamboo stalks and are inserted into the through holes.

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