Cement structure

Abstract

To provide a cement structure with enough strength against external force.SOLUTION: A joint structure (100) includes connectors (12, 22), a flat pipe (5), a fiber-reinforced cement mortar (30), wherein the connector (12) includes a connector shaft part (121), and a first nut (122), and the connector shaft part separates from the first nut when axial tensile force equal to or more than the prescribed value is applied between the connector shaft part and the first nut.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a cement structure.

Background Art

[0002] Conventionally, a joint structure (cement structure) for connecting the floor slabs of adjacent structures (for example, abutments and bridge girders) in a bridge with reinforced concrete has been proposed. The joint structure is constructed by excavating the floor slabs of adjacent structures to form recesses, fixing reinforcing bars (reinforcing members) to the floor slabs in the recesses, and driving a cement-based mixture thereinto. Further, an expansion joint for absorbing the expansion and contraction of the bridge due to temperature changes can be provided in the joint structure. The expansion joint is fixed to the reinforcing bar by welding or the like.

[0003] In addition, a method of facilitating the collective removal of reinforced concrete by previously embedding a flat pipe between the reinforcing member and the floor slab is known. In this method, the flat pipe is expanded vertically to break the reinforcing member and separate the reinforcing member from the floor slab, thereby removing the reinforced concrete. Patent Documents 1 and 2 describe replacing the expansion joint by such a method of removing reinforced concrete.

[0004] Patent Document 2 describes a configuration for separating the reinforcing member from the floor slab. Specifically, Patent Document 2 discloses a separating device including a connector and a bolt attached to the connector. The skirt portion of the connector includes a sleeve surrounding the head of the bolt and a flange for preventing the bolt from separating from the connector. The bolt is screw-connected to a support member fixed to the floor slab. The connector is connected to an anchor bolt or a reinforcing bar (reinforcing member). And in the separating device, when an axial tensile force of a predetermined value or more is applied between the connector and the bolt, the flange is deformed or broken, so that the connector can be separated from the bolt (that is, the reinforcing member can be separated from the floor slab).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, in the above-described technology, due to external forces received from a building (for example, the shaking of a building caused by an earthquake or the like), the concrete filling the recess may break, and the joint structure may be damaged. Replacing such a joint structure would require a great deal of time.

[0007] One aspect of the present invention has been made in view of the above problems, and an object thereof is to provide a cement structure having sufficient strength against external forces.

Means for Solving the Problems

[0008] To solve the above problems, a cement structure according to one aspect of the present invention includes a connector used for connecting a foundation structure and the cement structure, a flat pipe capable of separating the cement structure from the foundation structure by expanding, and fiber-reinforced cement mortar filled around the connector and the flat pipe. The connector includes a connector shaft portion that can be coupled to a reinforcing member disposed in the cement structure, a first nut that can be fastened to an anchor bolt driven into the foundation structure, a housing portion that is located on one side in the axial direction of the connector shaft portion with respect to the connector shaft portion and houses the first nut, and an extension portion that extends radially inward from an edge of the housing portion to prevent the first nut from coming out of the housing portion. When an axial tensile force equal to or greater than a predetermined value is applied between the connector shaft portion and the first nut, the connector shaft portion is separated from the first nut by deformation or breakage of the extension portion.

Effects of the Invention

[0009] According to one aspect of the present invention, a cement structure having sufficient strength against external forces can be provided.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Modes for Carrying Out the Invention

[0011] 〔Embodiment 1〕 (Schematic Configuration of Joint Structure 100) FIG. 1 is a cross-sectional view showing the configuration of a joint structure 100 (cement structure) of a bridge according to Embodiment 1. The joint structure 100 connects the floor slabs (foundation structures) of adjacent structures in the bridge. That is, the joint structure 100 connects the floor slab 2A of the first structure 1A and the floor slab 2B of the second structure 1B. The joint structure 100 is provided in a recess 4 formed by excavating the upper surfaces of the floor slab 2A and the floor slab 2B in the vicinity of the gap 3 between the first structure 1A and the second structure 1B. The joint structure 100 is constructed by fixing reinforcing bars (reinforcing members) to the floor slabs 2A and 2B in the recess 4 and driving a cement-based mixture M (for example, concrete, high-toughness jet mortar, etc.) thereinto. Hereinafter, the side where the first structure 1A is located in the bridge will be described as the front, the side where the second structure 1B is located as the rear, the left side toward the rear as the left side, and the right side as the right side.

[0012] As shown in FIG. 1, the joint structure 100 includes a plurality of first anchor portions 10A embedded in the floor slab 2A, a plurality of second anchor portions 10B and a plurality of third anchor portions 10C embedded in the floor slab 2B. The plurality of first anchor portions 10A are provided in the floor slab 2A at a predetermined pitch along the left-right direction. Similarly, the plurality of second anchor portions 10B and the plurality of third anchor portions 10C are each provided in the floor slab 2B at a predetermined pitch along the left-right direction. Hereinafter, when there is no need to particularly distinguish between the plurality of first anchor portions 10A, the plurality of second anchor portions 10B, and the plurality of third anchor portions 10C, they will simply be referred to as anchor portions 10.

[0013] Each anchor portion 10 has a reinforcing bar (reinforcing member 13) extending in the front-rear direction. Specifically, the plurality of first anchor portions 10A have reinforcing bars extending rearward. Also, the plurality of second anchor portions 10B and the plurality of third anchor portions 10C have reinforcing bars extending forward. The reinforcing bar extending rearward of each first anchor portion 10A and the reinforcing bar of the corresponding second anchor portion 10B are connected by an arbitrary connection method (e.g., tying with a binding wire, welding, etc.). Similarly, the reinforcing bars of the plurality of second anchor portions 10B and the reinforcing bars of the plurality of third anchor portions 10C are connected. Thereby, the floor slabs 2A, 2B of adjacent buildings are connected by the reinforcing bars, and the strength of the joint structure 100 against external forces in the front-rear direction can be improved. Also, compared with the case where the floor slabs 2A, 2B are connected by a single (U-shaped) reinforcing bar, the above-described configuration of connecting the L-shaped reinforcing bars fixed to the floor slab 2A and the floor slab 2B respectively can absorb the expansion and contraction in the front-rear direction of the first building 1A and / or the second building 1B.

[0014] The joint structure 100 further includes a flat pipe 5, an upper reinforcing bar 6 for pipe fixing, and a lower reinforcing bar 7 for pipe fixing. The flat pipe 5 is a pipe that can separate the joint structure 100 from the floor slabs 2A, 2B by expanding. For example, by injecting a liquid into the flat pipe 5, the flat pipe 5 expands in the vertical direction. The injection port for injecting the liquid into the flat pipe 5 is arranged near the road surface. The flat pipe 5 is provided so as to pass through near the boundary between the connector 12 (see FIG. 2) of the anchor portion 10 and the anchor bolt 11 (see FIG. 2). Also, the upper reinforcing bar 6 for pipe fixing and the lower reinforcing bar 7 for pipe fixing fix the height position of the flat pipe 5 so that the flat pipe 5 is located near the above boundary. For example, the lower reinforcing bar 7 for pipe fixing is fixed to the flat plate member 14 (see FIG. 2) of the anchor portion 10 by an arbitrary connection method below the flat plate member 14. The flat pipe 5 is placed on the upper side of the lower reinforcing bar 7 for pipe fixing so as to pass through near the anchor portion 10. The upper reinforcing bar 6 for pipe fixing is placed on the upper side of the flat pipe 5 and fixed to the lower reinforcing bar 7 for pipe fixing by an arbitrary connection method. Thereby, the flat pipe 5 is sandwiched between the upper reinforcing bar 6 for pipe fixing and the lower reinforcing bar 7 for pipe fixing near the above boundary.

[0015] The joint structure 100 may further include a plurality of left - right direction reinforcing members 8 extending in the left - right direction. The plurality of (five in the example shown in FIG. 1) left - right direction reinforcing members 8 are arranged side by side along the front - rear direction. The plurality of left - right direction reinforcing members 8 are disposed below the second straight portion 133 of the reinforcing member 13 and are fixed to the reinforcing member 13 by an arbitrary connection method. The plurality of left - right direction reinforcing members 8 can improve the strength of the joint structure 100 against external forces in the left - right direction.

[0016] Note that the configuration shown in FIG. 1 is only an example of the joint structure 100. For example, the plurality of third anchor portions 10C in the joint structure 100 may be omitted.

[0017] (Configuration of the anchor portion 10) FIG. 2 is a cross - sectional view showing the configuration of the anchor portion 10. As shown in FIG. 2, the anchor portion 10 includes an anchor bolt 11, a connector 12, and a reinforcing member 13. The anchor portion 10 is installed in the recess 4 by driving the anchor bolt 11 into the floor slabs 2A, 2B and attaching the reinforcing member 13 to the anchor bolt 11 via the connector 12. In FIG. 2, the anchor portion 10 assembled in this way is illustrated.

[0018] The anchor bolt 11 is a bolt fixed to the floor slabs 2A, 2B. The anchor bolt 11 extends upward (vertically upward) from the upper surface of the floor slabs 2A, 2B.

[0019] The connector 12 includes a connector shaft portion 121 having a substantially cylindrical shape extending in the vertical direction, and a first nut 122 accommodated in a housing portion 124a formed on the lower side of the connector shaft portion 121. A screw hole 121a (second screw hole) is formed at the upper end (end face on the other end side) of the connector shaft portion 121. The L - shaped reinforcing member 13 described later is coupled to the screw hole 121a. The first nut 122 is fastened to the anchor bolt 11.

[0020] The connector 12 is a member that connects the reinforcing member 13 to the anchor bolt 11 and can disconnect the reinforcing member 13 from the anchor bolt 11 when an axial tensile force equal to or greater than a predetermined value is applied. In other words, the connector 12 is a member that connects the joint structure 100 to the floor slabs 2A and 2B and can remove the joint structure 100 from the floor slabs 2A and 2B when an axial tensile force equal to or greater than a predetermined value is applied. The specific configuration of the connector 12 having such a function will be described later with reference to FIGS. 3 to 5.

[0021] The reinforcing member 13 is an L-shaped reinforcing bar having a gently bent curved portion 132. That is, the reinforcing member 13 has a first straight portion 131, a curved portion 132, and a second straight portion 133. The reinforcing member 13 is threaded at the first straight portion 131 and fastened to the threaded hole 121a of the connector shaft portion 121. The first straight portion 131 extends upward from the connector 12. The curved portion 132 is bent by 90 degrees with respect to the first straight portion 131. The second straight portion 133 extends in the lateral direction and is connected to the second straight portion 133 of another anchor portion 10 by an arbitrary connection method (see FIG. 1). For example, the second straight portion 133 in the first anchor portion 10A extends rearward, and the second straight portion 133 in the second anchor portion 10B extends forward. Then, the second straight portion 133 in the first anchor portion 10A and the second straight portion 133 in the second anchor portion 10B are connected. Thereby, the floor slabs 2A and 2B of adjacent buildings can be connected by an inverted U-shaped reinforcing bar, and the strength of the joint structure 100 against external forces in the front-rear direction can be improved. Note that the reinforcing member 13 extends upward from the connector 12 so that the second straight portion 133 is disposed at least above the upper reinforcing bar 6 for pipe fixing (see FIG. 1).

[0022] The anchor portion 10 may further include a flat plate member 14 and a second nut 15. The flat plate member 14 is located below the connector 12 and is provided between the first nut 122 of the connector 12 and the second nut 15 described later. Further, the flat plate member 14 is connected to the lower reinforcing bar 7 for pipe fixing located below it. Thereby, the flat pipe 5 sandwiched between the upper reinforcing bar 6 for pipe fixing and the lower reinforcing bar 7 for pipe fixing can be arranged near the boundary between the connector 12 and the anchor bolt 11 (see FIG. 1). The flat plate member 14 may be a plate member having a hole or notch through which the bolt passes, such as a square washer. The second nut 15 is fastened to the anchor bolt 11 below the first nut 122. The second nut 15, together with the first nut 122, sandwiches and fixes the flat plate member 14.

[0023] (Configuration of Connector 12) FIG. 3 is a front view showing the configuration of the connector 12. FIG. 4 is a cross-sectional view showing the configuration of the connector 12 before the caulking portion 124 is caulked. FIG. 5 is a cross-sectional view showing the configuration of the connector 12 after the caulking portion 124 is caulked. As shown in FIGS. 3 to 5, the connector 12 includes a connector shaft portion 121, a first nut 122, a head portion 123, and a caulking portion 124. With reference to FIGS. 3 to 5, the specific configuration of the connector 12 will be described below.

[0024] As shown in FIG. 3, a head portion 123 is provided at the lower end of the substantially cylindrical connector shaft portion 121. The head portion 123 has a diameter larger than that of the connector shaft portion 121 so as to engage with a tool (such as a hexagon wrench) for fastening the connector 12 to the anchor bolt 11, and has a non-circular (such as hexagonal) cross-section. At the lower end of the head portion 123, a substantially cylindrical caulking portion 124 is provided. The lower portion 124b of the caulking portion 124 is formed with an outer diameter smaller (that is, a thickness smaller) than the other portions.

[0025] As shown in FIGS. 4 and 5, an accommodation portion 124a for accommodating the first nut 122 is formed inside the caulking portion 124. That is, an accommodation portion 124a for accommodating the first nut is formed on the lower side (one side in the axial direction) of the connector shaft portion 121. The caulking portion 124 has an inner diameter slightly larger than the outer diameter of the off-the-shelf first nut 122. Further, the caulking portion 124 is formed higher than the height of the off-the-shelf first nut 122. Further, the caulking portion 124 is formed such that the lower end of the accommodated first nut 122 reaches the lower portion 124b of the caulking portion 124. The accommodation portion 124a may be a cylindrical recess or a hexagonal prism-shaped recess that matches the shape of the first nut 122.

[0026] As shown in FIG. 5, the caulking portion 124 is caulked with the first nut 122 disposed in the accommodation portion 124a. Specifically, a portion (see FIG. 4) that extends downward from the accommodated first nut 122 in the lower portion 124b of the caulking portion 124 is bent radially inward. Thereby, an extension portion 125 is formed that extends radially inward from the edge of the accommodation portion 124a and prevents the first nut 122 from coming out of the accommodation portion 124a. Then, the lower portion 124b of the caulking portion 124 is deformed inward by a press or the like. As a result, a part of the inner surface of the caulking portion 124 (the inner surface of the accommodation portion 124a) adheres closely to the outer surface of the first nut 122. Therefore, the first nut 122 is accommodated in the accommodation portion 124a in a non-rotatable manner relative to the caulking portion 124. Note that the height of the caulking portion 124 and the length of the extension portion 125 are set so that the extension portion 125 does not block the screw hole 121a of the first nut 122.

[0027] By fastening the first nut 122 fixed by the caulking part 124 to the anchor bolt 11, the connector 12 is connected to the anchor bolt 11. Here, when an axial tensile force equal to or greater than a predetermined value is applied between the connector shaft part 121 and the first nut 122, the extension part 125 is deformed or broken, and the connector shaft part 121 is separated from the first nut 122. Thereby, when an axial tensile force equal to or greater than a predetermined value is applied between the connector shaft part 121 and the first nut 122, a configuration can be realized in which the reinforcing member 13 can be separated from the anchor bolt 11 (together with the connector 12 excluding the first nut 122). The thickness and material of the extension part 125 (that is, the lower part 124b of the caulking part 124) may be appropriately determined according to the above-mentioned predetermined value of the tensile force.

[0028] (Function and effect) According to the above configuration, a configuration can be realized in which the reinforcing member 13 can be separated from the anchor bolts 11 fixed to the floor slabs 2A and 2B by an axial tensile force equal to or greater than a predetermined value. That is, by expanding the flat pipe 5 in the vertical direction and applying an axial tensile force equal to or greater than a predetermined value between the connector 12 and the anchor bolt 11, the joint structure 100 can be separated from the floor slabs 2A and 2B. Therefore, when replacing the parts in the joint structure 100, the joint structure 100 made of reinforced concrete can be easily removed.

[0029] In the conventional joint structure, a bolt caulked to the connector and an anchor bolt driven into the floor slab are fixed by a long nut or the like longer than a normal nut, and the bolt caulked to the connector is fixed to the floor slab. With such a configuration, the reinforcing member connected to the connector can be separated from the floor slab. However, in order to connect the bolt and the anchor bolt to each other, a long nut longer than a normal nut is required. In addition, since it is necessary to connect the bolts to each other, the number of work steps increases and the workability is not good.

[0030] On the one hand, in the present embodiment, the first nut 122 fixed to the connector 12 is fastened to the anchor bolt 11, so that the first nut 122 fixed to the connector 12 is fixed to the floor slabs 2A and 2B. With such a configuration, the connector can be detached from the bolt. That is, in the present embodiment, a nut is used instead of a bolt having a head and a shaft portion, and a configuration in which the reinforcing member can be detached from the floor slab is realized. Thereby, the height of the joint structure can be reduced. Therefore, the depth of the recess 4 can be made shallower, and the amount of the cementitious mixture M filling the recess 4 can be reduced. In addition, since the depth of excavation can be made shallower, the joint structure 100 has good workability. Furthermore, since the connector 12 can be directly connected to the anchor bolt 11, the number of work steps can be reduced, and the workability is good.

[0031] In addition, the flat plate member 14 provided between the first nut 122 and the second nut 15 is connected to the lower reinforcing bar 7 for pipe fixing located below it. With such a configuration, the flat pipe 5 sandwiched between the upper reinforcing bar 6 for pipe fixing and the lower reinforcing bar 7 for pipe fixing can be arranged near the boundary between the connector 12 and the anchor bolt 11 (specifically, near the extending portion 125).

[0032] In addition, the reinforcing member 13 is threaded at the first straight portion 131 and fastened to the threaded hole 121a of the connector shaft portion 121. With such a configuration, instead of welding the reinforcing member 13 to the connector 12, the reinforcing member 13 can be easily connected to the connector 12 by screwing the reinforcing member 13 to the connector 12. Therefore, the welding work in the construction of the joint structure can be reduced. The strength of the welded portion decreases. In the joint structure 100 of the present embodiment, the strength can also be improved.

[0033] 〔Embodiment 2〕 Another embodiment of the present invention will be described below. For the sake of convenience of explanation, members having the same functions as the members described in the above embodiment are given the same reference numerals, and the description thereof will not be repeated.

[0034] FIG. 9 is a cross-sectional view showing the configuration of a joint structure 101 (cement structure) of a bridge according to Embodiment 2. FIG. 10 is a top view showing the configuration of the joint structure 101. FIG. 6 is a cross-sectional view showing the configuration of an anchor portion 20 of the joint structure 101. As shown in FIGS. 6, 9, and 10, the anchor portion 20 is different from the anchor portion 10 in that it includes a connector 22 and a reinforcing member 23 instead of the connector 12 and the reinforcing member 13 in the anchor portion 10, respectively.

[0035] The connector 22 includes a connector shaft portion 221, a first nut 122, and a caulking portion 124. That is, the connector 22 is different from the connector 12 in that it includes a connector shaft portion 221 instead of the connector shaft portion 121 in the connector 12 and does not include the head portion 123 in the connector 12.

[0036] The connector shaft portion 221 is a member having a substantially prism shape (for example, a quadrangular prism shape) that extends upward on the other side in the axial direction. A screw hole 221a (first screw hole) is formed on the side surface of the connector shaft portion 221. A reinforcing member 23 extending in the lateral direction is coupled to the screw hole 221a. The reinforcing member 23 is a straight reinforcing bar, and one end thereof is threaded. The reinforcing member 23 is connected to the reinforcing members 23 of other anchor portions 20 by an arbitrary connection method.

[0037] Note that the connector shaft portion 221 only needs to extend at least above the upper reinforcing bar 6 for pipe fixing (see FIG. 1). Then, the screw hole 221a may be provided at a position above the upper reinforcing bar 6 for pipe fixing so that the reinforcing member 23 is disposed at least above the upper reinforcing bar 6 for pipe fixing (see FIG. 1).

[0038] (Function and effect) According to the above configuration, the reinforcing member 23 can be a linear reinforcing bar. Therefore, when the L-shaped reinforcing member 13 is screwed to the connector shaft portion 121, a space for the second straight portion 133 to rotate is required, while when the linear reinforcing member 23 is screwed to the connector shaft portion 221, such a space is not required. Accordingly, the workability when screwing to the connector shaft portion can be improved.

[0039] Further, instead of the L-shaped reinforcing member 13 that requires bending processing that reduces strength, by using the linear reinforcing member 23, the strength of the reinforcing member 23 can be improved.

[0040] Also, since the connector shaft portion 221 is a substantially prismatic member, screw hole machining in the connector shaft portion 221 becomes easy. Further, since the cross section of the connector shaft portion 221 is non-circular, it is not necessary to provide a head that engages with a tool for fastening the connector 12 to the anchor bolt 11. Note that the connector shaft portion 221 may be a substantially cylindrical member. In that case, the connector 22 may or may not include the head 123.

[0041] (Supplementary Notes) Note that the lower reinforcing bar 7 for pipe fixing may be omitted. For example, the lower reinforcing bar 7 for pipe fixing may be omitted, and the flat pipe 5 may be fixed by sandwiching it between the upper reinforcing bar 6 for pipe fixing and the flat plate member 14. The flat plate member 14 may be a rectangular plate member that extends so as to overlap the flat pipe 5. Thereby, the lower reinforcing bar 7 for pipe fixing can be omitted, and the workability can be improved.

[0042] In the above embodiment, an example in which the connectors 12 and 22 are applied to the joint structures 100 and 101 of the bridge has been described, but the application examples are not limited to this. For example, the connectors 12 and 22 may be used as members that connect a foundation concrete (foundation structure) in a factory or the like and a pedestal (cement structure) on which a machine is placed. In this case, by applying an axial tensile force of a predetermined value or more to the connector (for example, due to the expansion of a flat pipe embedded in the pedestal), the pedestal can be easily removed from the foundation concrete.

[0043] 〔Embodiment 3〕 Other embodiments of the present invention will be described below. For convenience of explanation, members having the same functions as those described in the above embodiments are denoted by the same reference numerals, and the description thereof will not be repeated.

[0044] In the present embodiment, fiber-reinforced cement mortar 30 as an example of the cement-based mixture M of the joint structures 100 and 101 described in the above embodiment will be described. That is, in the present embodiment, the joint structures 100 and 101 include the connectors 12 and 22, the flat pipe 5, and the fiber-reinforced cement mortar 30 filled around the connectors 12 and 22 and the flat pipe 5. The fiber-reinforced cement mortar 30 is a material in which reinforcing fibers are blended in the cement mortar 31. For example, in the present embodiment, the fiber-reinforced cement mortar 30 is a material that significantly enhances the reinforcing fiber function performed by the reinforcing fibers blended in the cement mortar 31.

[0045] (Configuration of Fiber-Reinforced Cement Mortar 30) FIG. 7 is an enlarged cross-sectional view schematically showing the fiber-reinforced cement mortar 30. As shown in FIG. 7, the fiber-reinforced cement mortar 30 is a material in which loose short fibers 32a as reinforcing fibers and converging fibers 33 formed by converging short fibers 32b are blended in the cement mortar 31. Specifically, the converging fibers 33 are formed by aligning a large number of short straight short fibers 32b in a straight line and bundling them, or by twisting them into a bundle and spirally winding and fusing binding fibers 34 around the peripheral surface of the bundle. The synergistic effect of the loose short fibers 32a and the converging fibers 33 can significantly improve the strength (such as tensile strength and bending strength) of the cement mortar 31.

[0046] As the reinforcing fibers, short fibers 32a and 32b and the binding fibers 34, polyethylene fibers, vinylon fibers, carbon fibers, aramid fibers, zylon fibers, and dyneema fibers are used.

[0047] The above Dyneema is a trademark of Toyobo Co., Ltd. (2-8, 2-chome, Dobutsuen-higashi, Kita-ku, Osaka-shi). This Dyneema is made of ultra-high molecular weight polyethylene, has ultra-high strength, high elastic modulus, is lightweight, and is excellent in fatigue resistance, impact resistance, light resistance, etc., and is a suitable material as a reinforcing fiber to be blended into fiber-reinforced cement mortar.

[0048] Also, the above Zylon is a trademark of the polyphenylene benzoxazole (PBO) fiber of the same Toyobo Co., Ltd. This fiber is a polybenzazole-based polymer, and is a fiber having a rigid and extremely linear molecular structure, rich in tensile strength, impact resistance characteristics, light resistance, etc., and is a suitable material as a reinforcing fiber to be blended into fiber-reinforced cement mortar.

[0049] In addition to the above polyethylene fiber and vinylon fiber, fibers such as carbon fiber, aramid fiber, Zylon fiber, and Dyneema fiber can be used in combination with each other.

[0050] Reference numeral A in Fig. 8 is an enlarged side view of the short fiber 32a blended in a dispersed state in the cement mortar 31. Reference numeral B in Fig. 8 is an enlarged side view of the convergent fiber 33 blended in a convergent state in the same cement mortar. Reference numeral C in Fig. 8 is an enlarged side view of the corrugated convergent fiber obtained by shaping the convergent fiber 33 into a corrugated shape.

[0051] As shown by reference numeral A in Fig. 8, the length L1 of the above-mentioned dispersed short fiber 32a is selected in the range of 6 to 12 mm, and the diameter R1 is selected in the range of 0.006 to 0.05 mm, respectively.

[0052] On the other hand, the length L2 of the above-mentioned convergent fiber 33 is selected in the range of 9 to 25 mm, the diameter R2 is selected in the range of 0.5 to 3 mm, the diameter of the short fiber 32b forming the convergent fiber 33 is selected in the range of 0.006 to 0.05 mm, and the number of the short fibers 32b is selected in the range of 200 to 5000. The above diameter R2 is determined by the number of the short fibers 32b.

[0053] The relative length of the above-mentioned loose short fibers 32a and the converging fibers 33 is selected within the above length range so as to be approximately 1:1 to 4. Preferably, when selecting the loose short fibers 32a with a fiber length of 9 mm, the converging fibers 33 of 12 mm are selected. Similarly, when selecting the loose short fibers 32a with a fiber length of 12 mm, the converging fibers 33 of 15 mm are selected. In this way, the short fibers 32a with a relatively short length and the converging fibers 33 with a relatively longer length than the short fibers 32a are mixed and incorporated into the cement mortar 31 (mortar containing all the ingredients other than the fibers 32a and 33) at 1 to 4 vol%. The preferred blending amount is 2 to 3 vol%.

[0054] More preferably, the length of the converging fibers 33 is about 2 to 5 mm longer than the length of the short fibers 32a, and the converging fibers 33 are used to exert the strength against the crack expansion after the fracture of the short fibers 32a.

[0055] The relative mixing ratio (weight ratio) of the above-mentioned loose short fibers 32a and the converging fibers 33 is selected within the range of 1 to 6:1 to 6. The preferred relative mixing ratio is approximately 1:1.

[0056] The reference sign B in FIG. 8 illustrates the converging means of the above-mentioned converging fibers 33. As shown in the figure, a large number of short straight short fibers 32b are aligned in a straight line and bundled, or twisted and bundled, and the binding fibers 34 are spirally wound around the peripheral surface of the bundle and fused to form the converging fibers 33.

[0057] As shown by the reference sign C in FIG. 8, the use of the corrugated converging fibers obtained by shaping the above-mentioned converging fibers 33 into a corrugated shape can improve the bonding effect with the cement mortar 31.

[0058] The spirally wound binding fibers 34, the loose short fibers 32a, and the short fibers 32b forming the converging fibers 33 use fibers of the same material and the same diameter of 0.006 to 0.05 mm. However, this embodiment includes cases where the binding fibers 34, the loose short fibers 32a, and the short fibers 32b forming the converging fibers 33 are each composed of different materials and different diameters.

[0059] (Mixing example of fiber-reinforced cement mortar 30) The mixing examples of fiber-reinforced cement mortar 30 will be described. Examples of the mixing amounts per cubic meter of fiber-reinforced cement mortar 30 are shown below as Mixing Example 1 to Mixing Example 3. Note that the mixing examples of fiber-reinforced cement mortar are not limited to those shown in Mixing Example 1 to Mixing Example 3. <Mixing Example 1... Fiber content 1.0 vol%> Water................................ 256.8 kg Portland cement........................ 1342.4 kg Expansion agent........................ 20.0 kg Silica sand.......................... 466.3 kg Silica fume.......................... 204.4 kg High-performance water reducer.......... 13.6 kg Foaming agent........................ 0.543 kg Dispersed short fibers (ex Dyneema)...... 8.327 kg (Length 6 - 12 mm, diameter 0.006 - 0.05 mm) Converging fibers (ex Dyneema)......... 1.388 kg (Length 9 - 25 mm, diameter 0.5 - 3 mm) <Mixing Example 2... Fiber content 2.5 vol%> Water................................ 324.6 kg Portland cement........................ 1368.4 kg Silica sand.......................... 273.7 kg Silica fume.......................... 241.4 kg High-performance water reducer.......... 8.046 kg Defoaming agent........................ 0.657 kg Dispersed short fibers (ex Dyneema)...... 12.144 kg (Length 6 - 12 mm, diameter 0.006 - 0.05 mm) Converging fibers (ex Dyneema)......... 12.144 kg (Length 9 - 25 mm, diameter 0.5 - 3 mm) <Mixing Example 3... Fiber content 4.0 vol%> Water................................ 393.4 kg Portland cement...................... 1367.7 kg Expansion agent..................... 20.0 kg Silica sand........................ 129.3 kg Silica fume......................... 208.1 kg High-performance water reducer....... 13.9 kg Foaming agent...................... 0.825 kg Discontinuous short fibers (ex Dyneema).. 9.7 kg (Length 6 - 12 mm, diameter 0.006 - 0.05 mm) Converging fibers (ex Dyneema)......... 29.1 kg (Length 9 - 25 mm, diameter 0.5 - 3 mm) In this embodiment, the cement mortar 31 includes those obtained by using Portland cement (hardening material) as the main material and blending aggregates such as sand and functional materials thereto, followed by adding water and kneading.

[0060] In the above Mixing Examples 1 to 3, water, Portland cement, aggregate (silica sand), functional materials (silica fume, high-performance water reducer, foaming agent), the discontinuous short fibers 32a, and the converging fibers 33 are put into a mixer, kneaded, and stirred to uniformly disperse both reinforcing fibers 5a and 6.

[0061] In this embodiment, the water / cement (including silica fume) ratio (W / C%) in Mixing Example 1 is 16.6%, in Mixing Example 2 is 20.1%, and in Mixing Example 3 is 24.9% for lean water addition, and it is a fiber-reinforced cement mortar 30 in which the discontinuous short fibers 32a and the converging fibers 33 cooperate to significantly enhance its strength.

[0062] In the above Mixing Examples 1 and 3, a foaming agent is blended to increase the volume by foaming and improve the sprayability. This foam is dissipated by spraying.

[0063] In addition, in Mixing Example 2, an antifoaming agent is added to form a fiber-reinforced cement mortar suitable for placing.

[0064] In addition, in Mixing Examples 1 and 3, an expansion agent is added. The expansion agent has the effect of effectively suppressing the shrinkage of the fiber-reinforced cement mortar after hardening.

[0065] (Advantages of Fiber-Reinforced Cement Mortar 30) In the fiber-reinforced cement mortar 30 according to this embodiment, the discrete short fibers 32a and the convergent fibers 33, which are mixed as reinforcing fibers in the cement mortar 31, cooperate with each other to significantly increase the elongation from the occurrence of fine cracks to the point of failure, that is, the elongation that maintains the occurrence of shallow and fine cracks with little influence on strength. Therefore, the fiber-reinforced cement mortar 30 can significantly improve the tensile strength and flexural strength compared with conventional concrete.

[0066] By using such a fiber-reinforced cement mortar 30 in the joint structures 100 and 101, the following effects are obtained. That is, the fiber-reinforced cement mortar 30 can deform flexibly while maintaining the occurrence of fine cracks in response to external forces from the building. As a result, the joint structures 100 and 101 can have sufficient strength against the shaking of the building due to an earthquake or the like, or the expansion and contraction of the building due to temperature changes. Regarding the reinforcing bar portions (reinforcing members 13) of the joint structures 100 and 101, as described above, they are configured to connect L-shaped reinforcing bars fixed to the floor slabs 2A and 2B of adjacent buildings, respectively, and this is a configuration capable of absorbing external forces from adjacent buildings.

[0067] On the one hand, when a tensile force equal to or greater than a predetermined value is applied due to the expansion of the flat pipe 5, the fiber-reinforced cement mortar 30 breaks along a plane substantially orthogonal to the vertical direction including the flat pipe 5. Therefore, the fiber-reinforced cement mortar 30 can be easily removed from the recess 4. For this reason, in repair work, the deteriorated joint structures 100 and 101 can be easily removed, and a new joint structure can be constructed. Further, in the event of a disaster such as an earthquake, the joint structures 100 and 101 including the fiber-reinforced cement mortar 30 can maintain the structure without being completely damaged. On the other hand, when a part of the joint structures 100 and 101 is damaged, it can be easily removed and replaced by expanding the flat pipe 5.

[0068] As described above, the fiber-reinforced cement mortar 30 is extremely effective as a cement-based mixture M for filling the recess 4 of the joint structures 100 and 101 in that it ensures sufficient strength against external forces from the building and breaks appropriately against a tensile force equal to or greater than a predetermined value.

[0069] (Supplementary Notes) Examples of the aggregate such as the above sand include sand such as silica sand, and examples of the functional material include silica fume (hardening material), water reducing agent, foaming agent, etc. In this example case, cement and silica fume serve as hardening materials.

[0070] This embodiment includes a compounding example in which a polymer resin flow material made of a styrene-butadiene resin system, a polyacrylate resin system (acrylic resin system), an ethylene-vinyl acetate resin system, a vinyl acetate-veova resin system, etc. is compounded with the fiber-reinforced cement mortar in which the above-mentioned short bar fibers 32a and the convergent fibers 33 are compounded.

[0071] That is, it includes a compounding example in which the above polymer resin is compounded with the cement mortar composed of water, Portland cement, aggregate, and functional material in the compounding examples 1 to 3 to form a fiber-reinforced polymer cement mortar. In this case, the polymer resin is compounded in the range of 10 to 120 kg.

[0072] The fiber-reinforced cement mortar may contain at least one of the short fiber 32a and the convergent fiber 33 as a reinforcing fiber.

[0073] As described above, the numerical range indicated by "~" between the lower limit value and the upper limit value includes the lower limit value and the upper limit value, and represents all numerical values (integer values and decimal values) between the lower limit value and the upper limit value.

[0074] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention.

Explanation of Signs

[0075] 100, 101 Joint structure (cement structure) 2A, 2B Floor slab (foundation structure) 5 Flat pipe 11 Anchor bolt 12, 22 Connector 121, 221 Connector shaft portion 121a, 221a Thread hole 122 First nut 124a Accommodating portion 125 Extension portion 13, 23 Reinforcing member 14 Flat plate member 15 Second nut 30 Fiber-reinforced cement mortar

Claims

Claim 1 A connector used for connecting a base structure and a cement structure, A flat pipe capable of separating the cement structure from the base structure by expanding, Fiber-reinforced cement mortar filled around the connector and the flat pipe, comprising: The connector is A connector shaft portion that can be coupled to a reinforcing member disposed in the cement structure, A first nut that can be fastened to an anchor bolt driven into the base structure, A housing portion that is located on one side in the axial direction of the connector shaft portion with respect to the connector shaft portion and houses the first nut, A stretching portion that extends radially inward from the edge of the housing portion to the connector shaft portion to prevent the first nut from coming out of the housing portion, When an axial tensile force equal to or greater than a predetermined value is applied between the connector shaft portion and the first nut, the stretching portion is deformed or broken, whereby the connector shaft portion is separated from the first nut, a cement structure.

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