Lightweight concrete floor slab and method for constructing lightweight concrete floor slab

Abstract

To provide a lightweight concrete floor slab which is reduced in weight without requiring the use of lightweight concrete as an essential condition, and a construction method for the lightweight concrete floor slab which reduces construction labor and costs.SOLUTION: In the lightweight concrete floor slab, a plurality of hollow molded bodies 10 are embedded in concrete in which a rigid long member is arranged, and through shafts 52 arranged in parallel or perpendicular to the surface direction of the lightweight concrete floor slab and penetrating the hollow molded bodies are provided, the hollow molded bodies have through holes 54 for penetrating the through shafts, and the arrangement positions of the hollow molded bodies are positioned by penetrating the through shafts into the through holes. The hollow molded body includes at least a first part side 10a and a second part side 10b that can be separated from each other, and the through-hole includes a first cutout portion side 55A and a side 55B provided at a predetermined outer edge of the first part, and a second cutout portion side 56A and a side 56B provided at a predetermined outer edge of the second part.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present invention relates to a concrete slab, and more particularly to a lightweight concrete slab and a lightweight concrete slab construction method that are designed to be lightweight. [Background technology]

[0002] Concrete slabs are known to be used in the floor structures of buildings. Concrete slabs are heavy because they use a large amount of concrete, which places a heavy load on the structure or ground below. Therefore, attempts are being made to reduce the weight of concrete slabs.

[0003] For example, conventionally, attempts have been made to use lightweight concrete in order to reduce the weight of slabs in buildings.

[0004] The following Patent Document 1 discloses a construction method in which, when pouring slab concrete onto a formwork, ordinary concrete is first poured into the column positions, and then the poured ordinary concrete is joined to the ordinary concrete while it is still fresh, and lightweight concrete is poured into the inter-column band positions. This construction method is explained as a technology that uses ordinary concrete in the floor parts corresponding to the column band positions to ensure strength, and uses lightweight concrete in other parts to reduce the weight of the entire floor slab. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 11-182043 Summary of the Invention [Problem to be solved by the invention]

[0006] However, although the construction method disclosed in Patent Document 1 states that strength is ensured by using ordinary concrete at the column position, with this construction method, the strength of the areas other than the column position where lightweight concrete is used may be lower than when conventional ordinary concrete is used, which is particularly problematic when the load of the structure being supported is large.

[0007] The present invention has been made in view of the above-mentioned problems. That is, the present invention provides a lightweight concrete slab that is lightweight without requiring the use of lightweight concrete, and a construction method for a lightweight concrete slab that reduces the labor and cost of construction. [Means for solving the problem]

[0008] The lightweight concrete slab of the present invention is characterized in that a plurality of hollow molded bodies are embedded inside concrete reinforced with rigid elongated members, and are provided with through shafts that pass through the hollow molded bodies and are arranged parallel or perpendicular to the surface direction of the lightweight concrete slab, the hollow molded bodies have through holes for passing the through shafts, and the placement position of the hollow molded bodies is determined by passing the through shafts through the through holes, the hollow molded bodies have at least a first part and a second part that are separable from each other, and the through hole is constituted by a first notch portion provided on a predetermined outer edge of the first part and a second notch portion provided on a predetermined outer edge of the second part.

[0009] Furthermore, the lightweight concrete slab construction method of the present invention is characterized by sequentially carrying out a lower layer reinforcement process in which reinforcement is arranged in the lower layer, a hollow molded body placement process in which hollow molded bodies are placed above the lower layer, and an upper layer reinforcement process in which reinforcement is arranged in the upper layer located above the lower layer, followed by a pouring process in which concrete is poured. [Effects of the Invention]

[0010] The lightweight concrete slab and construction method of the present invention secures space inside by burying multiple hollow bodies inside concrete in which rigid long members such as reinforcing bars are arranged. This makes it possible to reduce the weight of concrete floor slabs such as concrete slabs by a simple and low-cost means without making the use of lightweight concrete an essential condition. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic top view of a lightweight concrete floor slab according to a first embodiment of the present invention. FIG. [Figure 2] 2 is a cross-sectional view of the lightweight concrete slab shown in FIG. 1 along line II-II. [Figure 3] (3A) is a schematic top view of the lower layer reinforcing bar in the first embodiment, (3B) is a schematic top view of the middle layer reinforcing bar with the hollow molding body installed in the first embodiment, and (3C) is a schematic top view of the upper layer reinforcing bar with the hollow molding body installed in the first embodiment. [Figure 4] FIG. 4A is a schematic top view of a lightweight concrete slab according to a second embodiment of the present invention, and FIG. 4B is a cross-sectional view taken along the line IV-IV of FIG. 4A. [Figure 5] FIG. 5A is an exploded perspective view of a hollow molded body used in a third embodiment of the present invention, and FIG. 5B is a perspective view of the hollow molded body shown in FIG. 5A with a through shaft passing through it. [Figure 6] FIG. 10 is a cross-sectional view in the thickness direction of a third embodiment of the present invention. [Figure 7] (7A) is a schematic top view of the lower layer reinforcing bar in the third embodiment, (7B) is a schematic top view of the middle layer with the second part installed in the third embodiment, and (7C) is a schematic top view of the upper layer reinforcing bar with the hollow molding body installed in the third embodiment. [Figure 8] 8A is an exploded perspective view of a hollow molded body used in a fourth embodiment of the present invention, and FIG. 8B is a perspective view of the hollow molded body shown in 8A with a through shaft passing through it. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings, similar components are designated by the same reference numerals, and duplicated descriptions will be omitted where appropriate. The various components of the present invention do not necessarily have to be independent entities; multiple components may be formed as a single member, one component may be formed from multiple members, one component may be part of another component, or a portion of one component may overlap with a portion of another component. In the illustrated embodiments of the present invention, certain components may be shown relatively large or small relative to the overall structure for ease of understanding, but neither of these represents a limitation on the dimensional proportions of each component of the present invention. Furthermore, the lightweight concrete slabs shown in the drawings do not represent a limitation on the number or placement of hollow molded bodies to be placed, the number of long members such as reinforcing bars used, or the size of the slab. In relation to the present invention or the description of this specification, unless otherwise specified, the up-down direction refers to the top-to-bottom direction when the concrete slab is installed.

[0013] The lightweight concrete slab of the present invention is constructed by embedding a plurality of hollow molded bodies inside concrete reinforced with rigid long members. By replacing part of the concrete with hollow molded bodies in this way, the present invention can effectively reduce the weight of the concrete slab. Although the present invention does not prohibit the use of lightweight concrete, it is not necessary to use lightweight concrete for weight reduction. In a more desirable embodiment, the present invention has a hollow molded body inside, the position of which is constrained by an internal structure such as a reinforcement structure or a through shaft in which a rigid long member is arranged. This prevents the hollow molded body from floating up or shifting out of position when concrete is poured after the long member has been reinforced and the hollow molded body has been placed. This allows space to be secured inside the concrete slab according to the design.

[0014] The concrete floor slab of the present invention refers to a flat, extending concrete structure that has been given strength by the placement of rigid, long members such as steel bars inside it, and includes not only so-called concrete slabs but also concrete floors. Here, the term "slab" refers to a structure that can support the weight of people, objects, buildings, etc. A concrete slab is a structure that has been structurally calculated to provide sufficient support without relying on the bearing capacity of the ground, while a concrete floor is a structure whose fulcrum is the ground.

[0015] In the present invention, a rigid elongated member is a member that can add the strength required for a concrete slab and that can be arranged in a predetermined space before concrete is poured. Examples of rigid elongated members include, but are not limited to, reinforcing bars arranged inside slab concrete or concrete floors.

[0016] There are many patterns for arranging reinforcement in long members to add strength to concrete deck slabs, but the most commonly used pattern is one that has at least two or more layers of lattice-like layers made of rigid long members such as rebar arranged vertically and horizontally. In the following explanation, the relatively lower layer of these two or more lattice-like layers will be referred to as the lower layer, and the relatively upper layer will be referred to as the upper layer, as appropriate. The layer between the upper and lower layers will also be referred to as the middle layer. In order to prevent the hollow molded body of the present invention from floating up to the top surface of the concrete slab when concrete is poured, it is preferable that the hollow molded body be placed below the upper layer, and also to ensure that concrete is poured on the underside of the hollow molded body, it is preferable that the hollow molded body be placed above the lower layer. In other words, in the present invention, it is a preferred embodiment that the hollow molded body be placed between the lower and upper layers of a lattice-like layer made of elongated members. However, the present invention does not exclude concrete slabs in which the above-mentioned lattice-like layer is a single layer.

[0017] The hollow molded body used in the present invention broadly includes molded bodies having a wall separating the inside from the outside and a hollow interior. The material constituting the wall may be any material strong enough to withstand the weight of the concrete when poured, such as resin materials, wood, or metal materials such as stainless steel. However, resin materials are preferred from the viewpoint of ease of molding and excellent strength and light weight. The resin referred to here is not particularly limited and may be any resin capable of molding a hollow molded body, but preferred examples include one or more resins selected from polystyrene-based resins, polypropylene-based resins, polyethylene-based resins, etc. The wall does not have to be made of a single material, but may be made of a combination of two or more materials. For example, an elastic sheet or the like may be attached to the outer peripheral surface of the hollow molded body (especially the outer peripheral surface that is expected to come into contact with the elongated member) to exert friction. In a hollow molded body, the inside (hollow portion) is separated from the outside by a wall, but the hollow portion does not need to be completely sealed, and it is not a problem if there is a gap anywhere in the wall that is large enough to prevent poured concrete from flowing into the inside. The present invention will be described in more detail below using several concrete slab embodiments. In addition, in the description of these embodiments, the concrete slab construction method of the present invention (hereinafter simply referred to as the construction method of the present invention) will also be described as appropriate. Note that the following embodiments will be described using reinforcing bars as rigid long members, but this does not limit the long members of the present invention in any way.

[0018] First Embodiment A first embodiment of the lightweight concrete slab of the present invention will be described below with reference to Figures 1 to 3. This embodiment is an example in which the placement position of the hollow molded body is restricted by a reinforcement structure, and the design of the reinforcement is changed according to the dimensions of the hollow molded body. FIG. 1 is a schematic top view of a lightweight concrete slab 110 according to a first embodiment of the present invention. In addition to the concrete 50 visible in the top view, FIG. 1 also shows the internal upper layer reinforcing bars 24 and hollow molded bodies 10 in dashed lines for ease of understanding. FIG. 2 is a cross-sectional view II-II of the lightweight concrete slab 110 shown in FIG. 1. The II-II cross-sectional view shows a cross section of the lightweight concrete slab 110 cut in the thickness direction. The intermediate main reinforcement 31 shown in dashed lines is a reinforcing bar that intersects with the intermediate distribution reinforcement 32 and is positioned behind the hollow molded body 10 on the paper. FIG. 3A is a schematic top view of a lower layer reinforcing bar 44 in the first embodiment. 3B is a schematic top view of the middle layer reinforcing bar 34 with the hollow molding body 10 in the first embodiment installed, and FIG. 3C is a schematic top view of the upper layer reinforcing bar 24 with the hollow molding body 10 in the first embodiment installed.

[0019] As shown in FIGS. 1 and 2, the lightweight concrete slab 110 includes a layer in which reinforcing bars, which are rigid long members, are arranged, and the hollow molded bodies 10 are embedded inside the concrete 50. As shown in Fig. 2, in this embodiment, the layers in which reinforcing bars are arranged include lower-layer reinforcing bars 44 and upper-layer reinforcing bars 24 located above them, and the hollow molded body 10 is arranged between the lower-layer reinforcing bars 44 and the upper-layer reinforcing bars 24. The lower-layer reinforcing bars 44 are a layer in which lower-end main reinforcing bars 41 and lower-end distribution bars 42 are arranged in a grid pattern, and the upper-layer reinforcing bars 24 are a layer in which upper-end main reinforcing bars 21 and upper-end distribution bars 22 are arranged in a grid pattern. Note that both the lower-layer reinforcing bars 44 and the upper-layer reinforcing bars 24 have the same configuration as reinforcing bars in a general concrete slab, but the distinction between main reinforcing bars and distribution bars is not particularly strict in the present invention, and either or both of the upper-layer reinforcing bars 24 and the lower-layer reinforcing bars 44 may be a layer in which, for example, one main reinforcing bar and another main reinforcing bar are arranged in a grid pattern.

[0020] The concrete 50 in the lightweight concrete slab 110 reaches below the lower layer reinforcing bars 44 and above the upper layer reinforcing bars 24, with the hollow molded body 10 located in the middle in the thickness direction. The hollow molded body 10 in this embodiment is a hollow columnar body having an internal hollow portion 12. Although the drawings show the hollow molded body 10 as a quadrangular column (i.e., a rectangular parallelepiped), the hollow columnar body 10 may also be a polygonal column or a cylinder other than a quadrangular column. Because the columnar body has a substantially flat bottom surface and a substantially flat top surface, it can be stably placed relative to the lower layer reinforcing bars 44 and the upper layer reinforcing bars 24. Furthermore, the hollow molding body 10, which is a hollow columnar body in this embodiment, has a rounded outer shape with chamfered corners 14 on the outer periphery. Chamfering the corners 14 is preferable because it makes it less likely that gaps will form around the periphery of the hollow molding body 10 due to poor flow of the concrete 50 when concrete 50 is poured into a formwork (not shown) after the reinforcing bars and hollow molding body 10 are placed.

[0021] In this embodiment, as described above, there are at least two layers (upper layer reinforcing bars 24 and lower layer reinforcing bars 44) in the vertical direction, in which long steel bars are arranged in a grid pattern so that they cross vertically and horizontally in the surface direction, and a hollow molded body 10 is placed on the upper surface of the lower of these two layers (lower layer reinforcing bars 44). Here, in order to allow the hollow molding body 10 to be easily and stably positioned relative to the lower layer reinforcing bars 44, the area of ​​the bottom surface of the hollow molding body 10 is designed to be larger than the area of ​​one lattice 45 (see Figure 3C) formed by the long members (lower end main bars 41, lower end distribution bars 42) in the lower layer (lower layer reinforcing bars 44) when viewed from above. Furthermore, the upper layer reinforcing bars 44 installed above the hollow molded bodies 10 are also designed so that the area of ​​the upper surface of the hollow molded bodies 10, when viewed from above, is larger than the area of ​​one lattice 45 (see FIG. 3A) formed by the long members (upper end main reinforcing bars 21, upper end reinforcing bars 22) in the upper layer (upper layer reinforcing bars 24). Therefore, when concrete 50 is poured, the hollow molded bodies 10 are prevented from floating up due to their buoyancy and penetrating the upper layer reinforcing bars 24 to be exposed on the upper surface of the concrete floor slab. In this embodiment, the upper layer reinforcing bars 24 and the lower layer reinforcing bars 44 have the same reinforcing pitch, and are configured so that they overlap when viewed from above. The upper layer reinforcing bars 24 and the lower layer reinforcing bars 44 are arranged regularly, with a grid 45 continuously formed at a substantially uniform pitch. However, the present invention is not limited to this, and includes configurations in which the upper layer reinforcing bars 24 and the lower layer reinforcing bars 44 have different pitches, or in which they do not overlap when viewed from above.

[0022] By restraining the hollow molding body 10 from the top and bottom with the upper layer reinforcing bars 24 and the lower layer reinforcing bars 44 described above, it is possible to prevent the hollow molding body from shifting from its position when the concrete 50 is poured. In this embodiment, however, in order to further effectively restrain the position of the hollow molding body 10, a middle layer reinforcing bar 34 is provided to ensure space within the reinforcement structure for the hollow molding body 10 to be placed. The middle layer reinforcing bars 34 are a layer of reinforcing bars located between the upper layer reinforcing bars 24 and the lower layer reinforcing bars 44. As shown in Fig. 3B, the middle layer reinforcing bars 34 are arranged in a lattice pattern so that the middle main reinforcements 31 and the middle distribution reinforcements 32 cross each other vertically and horizontally in the planar direction, and some of the middle main reinforcements 31 and the middle distribution reinforcements 32 are thinned out at predetermined positions to form spaces 36 through which the hollow molded body 10 can pass. The hollow molded body 10 placed in the reinforcement structure having such middle layer reinforcing bars 34 is not only restrained from moving up and down by the lower layer reinforcing bars 44 and the upper layer reinforcing bars 42, but is also restrained from moving laterally by the middle main reinforcements 31 and middle distribution reinforcements 32 that define the spaces 36 provided in the middle layer reinforcing bars 34. Therefore, the hollow molded body 10 is well maintained in its position when concrete 50 is poured.

[0023] The lightweight concrete slab 110 described above can be constructed by the construction method of the present invention. That is, the construction method for constructing the lightweight concrete slab 110 includes steps of forming a formwork for pouring concrete as appropriate, followed by a lower layer reinforcing bar arrangement step of arranging reinforcement for the lower layer (lower layer reinforcing bars 44), a hollow molded body arrangement step of arranging hollow molded bodies 10 above the lower layer (lower layer reinforcing bars 44), and an upper layer reinforcing bar arrangement step of arranging reinforcement for the upper layer (upper layer reinforcing bars 44) located above the lower layer (lower layer reinforcing bars 44), in that order; and after the upper layer reinforcing bar arrangement step is performed, a pouring step of pouring concrete 50 is performed. Of these steps, the lower layer reinforcing bar arrangement step, upper layer reinforcing bar arrangement step, and pouring step can be performed in accordance with conventional construction methods for concrete slabs. When intermediate layer reinforcing bars 34 are to be provided, an intermediate layer reinforcing bar arrangement step is further carried out. Hereinafter, a construction method for constructing the lightweight concrete slab 110 including the intermediate layer reinforcing bar arrangement step will be described with reference to FIG.

[0024] [Construction method for lightweight concrete slab 110] First, a formwork for pouring concrete (not shown) is formed. 3A, the lower layer reinforcement step is carried out by arranging the bottom end main reinforcements 41 and bottom end distribution reinforcements 42 in a grid pattern at equal intervals, thereby forming the lower layer reinforcing bars 44. Next, the middle layer reinforcement arrangement process is carried out. In the middle layer reinforcement arrangement process, the middle main reinforcements 31 and the middle distribution reinforcements 32 are arranged in a grid pattern in the surface direction at a predetermined height from the top surface of the lower layer reinforcing bars 44, and the pitch of the arrangement of the middle main reinforcements 31 and the middle distribution reinforcements 32 is changed at predetermined positions to ensure multiple spaces 36. This forms the middle reinforcing bars 34. In this embodiment, multiple spaces 36 are formed in an orderly arrangement as shown in FIG. 3B to ensure that the strength of the concrete floor slab 110 is uniform in the surface direction. However, in areas where structures such as columns are to be constructed above, the formation of spaces 36 may be refrained from as appropriate so that the hollow molded bodies 10 are not placed therein. Next, a hollow molded body arrangement step is carried out. Specifically, the hollow molded body 10 prepared in advance is arranged by being inserted into the space 36 provided in the intermediate reinforcing bars 34 formed in the intermediate layer reinforcing bar arrangement step. The dimensions and shape of the space 36 should be adjusted to be slightly larger than the dimensions and shape of the bottom of the hollow molded body 10 so that the hollow molded body 10 does not move inside the space 36. After the hollow molded body 10 is placed as described above, the upper layer reinforcement step is carried out. Specifically, the upper end main reinforcements 21 and the upper end distribution reinforcements 22 are arranged in a grid pattern at equal intervals in the surface direction so as to cover the upper surface of the hollow molded body 10. From the viewpoint of preventing the hollow molded body 10 from floating up when concrete is poured, the lower surface of the upper layer reinforcing bars 24 and the upper surface of the hollow molded body 10 are arranged in a grid pattern. The distance between the electrode and the substrate is preferably about 0 cm or more and 10 cm or less, and more preferably substantially 0 cm. As a result of the above, the hollow molding body 10 placed in the hollow molding body placement process is restrained from moving up and down and sideways by the lower layer reinforcing bars 44, the middle main reinforcements 31 and middle distribution reinforcements 32 that define the space 36, and the upper layer reinforcing bars 24. Next, a concrete pouring step is carried out to pour concrete 50 so that it extends from below the lower layer reinforcing bars 44 to a height that fully covers the upper layer reinforcing bars 24. The poured concrete is allowed to fully harden, thereby completing the lightweight concrete deck 110. The lightweight concrete slab 110 constructed in this manner is lightweight because multiple hollow molded bodies 10 are embedded inside, and the use of lightweight concrete is not a mandatory condition. However, the present invention does not exclude the use of lightweight concrete as the concrete 50 as appropriate, provided that it meets the bearing capacity expected of the lightweight concrete slab 110.

[0025] While the present embodiment has been described with reference to an aspect in which the middle layer reinforcing bars 34 are provided, the present invention does not have the middle layer reinforcing bars 34, and instead arranges the upper layer reinforcing bars 24 so that the upper end reinforcing bars 22 and the upper end main reinforcements 21 are firmly pressed against the upper surface of the hollow molded body 10 placed on the upper surface of the lower layer reinforcing bars 44. This makes it possible to restrain the hollow molded body 10 from moving not only vertically but also horizontally, and to maintain the hollow molded body 10 in the designed position even when concrete 50 is poured. In this case, the middle layer reinforcing bar arrangement step may be omitted from the construction method of the present embodiment. Furthermore, in the first embodiment, a configuration is shown in which lower layer reinforcing bars 44, middle layer reinforcing bars 34, and upper layer reinforcing bars 24 are provided, but for example, an additional layer of reinforcing bars may be provided at any position relative to these three layers, and more specifically, for example, an additional layer may be provided further below the lower layer reinforcing bars 44, or an additional layer may be provided further above the upper layer reinforcing bars 24.

[0026] Second Embodiment A second embodiment of the present invention will be described below with reference to Fig. 4. This embodiment is an example in which the arrangement position of a hollow molded body is restricted by a reinforcement structure, and the dimensions and shape of the hollow molded body are adjusted to fit the normal space (space between long members) of a general reinforcement structure. Fig. 4A is a top view of a lightweight concrete slab 120 according to a second embodiment of the present invention, and Fig. 4B is a cross-sectional view taken along line IV-IV of Fig. 4A. The upper end main reinforcement 21, the middle main reinforcement 31, and the lower end main reinforcement 41 shown by dashed lines in Fig. 4B are reinforcing bars that intersect with the upper end distribution reinforcement 22, the middle distribution reinforcement 32, and the lower end main reinforcement 42, respectively, and are arranged behind the hollow molded body 10 on the paper.

[0027] In this embodiment, a hollow molded body 10 that is a hollow cone will be described. In the present invention, a hollow cone includes a cone or a frustum having a hollow portion 12 therein. The above-mentioned cone refers to a circular cone, a polygonal pyramid, or the like. The above-mentioned frustum refers to a shape obtained by cutting a cone transversely at a midpoint between its apex and its base, excluding the apex side, and the top surface formed by the cut may or may not be parallel to the base. In the lightweight concrete floor slab 120 of the second embodiment described below, the hollow molded body 10 which is a hollow truncated cone will be described as an example.

[0028] The lightweight concrete slab 120 is configured in the same manner as the lightweight concrete slab 110 of the first embodiment, except for the shape of the hollow molded bodies 10 and the fact that middle layer reinforcing bars 35 are used instead of the middle layer reinforcing bars 34. Therefore, in this embodiment, these differences from the first embodiment will be described in detail, and for other configurations, the description of the first embodiment will be referred to as appropriate.

[0029] In this embodiment, the middle layer reinforcing bars 35 are arranged at the same pitch as the lower layer reinforcing bars 44 and the upper layer reinforcing bars 24. It is constructed by arranging the intermediate main reinforcement 31 and the intermediate distribution reinforcement 32. In this way, in this embodiment, reinforcement can be arranged without changing the construction method of the conventional concrete slab, and therefore construction is easy.

[0030] The truncated cone hollow molded body 10 used in this embodiment has an upper surface 15 and a bottom surface 16, and its position within the concrete 50 is a combination of a normal position where the upper surface 15 faces upward, and an inverted position where the upper surface 15 faces downward, as shown in Fig. 4. However, as a modified example, all of the hollow molded bodies 10 may be in either a normal position or an inverted position.

[0031] In the properly placed hollow molded body 10, the area of ​​the upper surface 15 is smaller than the area of ​​the lattice 45, and when placed on the upper surface of the lower layer reinforcing bars 44, the upper surface 15 penetrates the lattice 45 of the middle layer reinforcing bars 34 and is located between the middle layer reinforcing bars 35 and the upper layer reinforcing bars 24. With this configuration, the lower surface of the hollow molded body 10 is restrained from moving downward by the lower layer reinforcing bars 44, and the middle portion of the hollow molded body 10 is restrained from moving laterally and upward by the middle main reinforcements 31 and middle distribution reinforcements 32 that constitute the lattice 45 of the middle layer reinforcing bars 35 through which the upper surface 15 penetrates. Therefore, the properly placed hollow molded body 10 is less likely to shift its position when concrete 50 is poured.

[0032] Furthermore, the area of ​​the bottom surface 16 of the inverted hollow molded body 10 is larger than the area of ​​the lattice 45, the area of ​​the top surface 15 is smaller than the area of ​​the lattice 45, and its height is larger than the distance between the middle reinforcing bars 35 and the upper layer reinforcing bars 24. Therefore, the bottom surface 16 of the inverted truncated cone hollow molded body 10 is restrained from moving upward by the upper layer reinforcing bars 24, and the middle part of the hollow molded body 10 is restrained from moving laterally and downwardly by the middle main reinforcements 31 and middle distribution reinforcements 32 that constitute the lattice 45 of the middle layer reinforcing bars 35 through which the top surface 15 penetrates. Therefore, the inverted hollow molded body 10 is less likely to shift its position when concrete 50 is poured.

[0033] Next, the construction method of this embodiment will be described. When arranging the hollow molded body 10, which is a hollow cone, in a normal position, it is advisable to carry out the following in this order: a lower layer reinforcement process for arranging the lower layer reinforcement 44; a hollow molded body normal placement process for placing the hollow molded body 10 in a predetermined position on the lower layer reinforcement 44 with the bottom surface 16 facing downwards; a middle layer reinforcement process for arranging the middle layer reinforcement 35; and an upper layer reinforcement process for arranging the upper layer reinforcement 24. On the other hand, when placing the hollow molded body 10, which is a hollow cone, in an inverted position, it is advisable to carry out the following steps in this order: a lower layer reinforcement process for arranging the lower layer reinforcement 44; a middle layer reinforcement process for arranging the middle layer reinforcement 35; a hollow molded body inverted placement process for arranging the hollow molded body 10 by inserting the upper surface 15 of the hollow molded body 10 into the specified lattice 45 of the middle layer reinforcement 35; and an upper layer reinforcement process for arranging the upper layer reinforcement 24. In an embodiment including both normal and reverse placement as shown in FIG. 4, the lower layer reinforcement step, hollow molded body normal placement step, middle layer reinforcement step, hollow molded body reverse placement step, and upper layer reinforcement step may be carried out in this order.

[0034] Third Embodiment A third embodiment of the present invention will be described below with reference to Figures 5 to 7. In this embodiment, an aspect will be described in which the placement position of the hollow molded body 10 is restricted by passing a through shaft through the hollow molded body 10. In the following description, passing a through shaft through the hollow molded body may be expressed as "attaching the hollow molded body to the through shaft." Fig. 5A is an exploded perspective view of a hollow molded body 10 used in a third embodiment of the present invention, and Fig. 5B is a perspective view of the hollow molded body 10 shown in Fig. 5A with a through shaft 52 passing through it. Fig. 6 is a cross-sectional view of a lightweight concrete slab 130 according to the third embodiment of the present invention, cut in the thickness direction along the through shaft 52. Fig. 7A is a schematic top view of a lower layer reinforcing bar 44 according to the third embodiment, and Fig. 7B is a schematic top view of a middle layer 37 with a second part 10b according to the third embodiment installed. 7C is a schematic top view of the upper layer reinforcing bar 24 in a state where the hollow molded body 10 according to the third embodiment is installed.

[0035] As shown in FIG. 6 , the lightweight concrete slab 130 has lower layer reinforcing bars 44 provided, and the hollow molded bodies 10 embedded on top of the lower layer reinforcing bars, with the upper layer reinforcing bars 24 provided above the hollow molded bodies 10. In this embodiment, a middle layer 37 is provided between the lower layer reinforcing bars 44 and the upper layer reinforcing bars 24. The middle layer 37 has a through shaft 52. The hollow molded bodies 10 are attached to this through shaft 52. Concrete 50 is filled below the lower layer reinforcing bars 44, above the upper layer reinforcing bars 24, and between them, and a plurality of hollow molded bodies 10 are arranged in the middle of the concrete 50 in the thickness direction.

[0036] 5B, the hollow molded body 10 used in this embodiment has a through hole 54 in the side surface for passing through the through shaft 52. Two through holes 54 are provided at positions facing each other to form one through hole set, which allows the through shaft 52 to pass through the hollow molded body 10. The through shaft 52 is an elongated member arranged parallel to or perpendicular to the surface direction of the lightweight concrete floor slab 130. In this embodiment, a specific description will be given of an aspect that includes the through shaft 52, which is an elongated member arranged parallel to the surface direction of the lightweight concrete floor slab 130, and the hollow molded body 10, in which a through hole 54 is provided on a lateral side surface to allow the through shaft to pass through. When using the through shaft 52 arranged perpendicular to the surface direction of the lightweight concrete floor slab 130, it is sufficient to provide mutually opposing through holes 54 on the upper surface (top surface) and lower surface (bottom surface) of the hollow molded body. By having the through shaft 52 pass through the through hole 54, the position of the hollow molded body 10 is prevented from shifting in at least a direction other than the extending direction of the through shaft 52.

[0037] In order to prevent the position of the hollow molded body 10 from shifting in the extension direction of the through shaft 52, for example, the diameter of the through shaft 52 and the diameter of the through hole 54 may be formed to be approximately the same size, and the inner surface of the through hole 54 may be brought into contact with the outer circumferential surface of the through shaft 52 to apply frictional force therebetween, thereby restricting movement of the hollow molded body 10 in the extension direction. Any other restricting means for preventing movement of the hollow molded body 10 in the extension direction of the through shaft 52 may also be used as appropriate. Alternatively, to further stabilize the position of the hollow molding body 10 with the through shaft 52 passing through it, it is preferable that the bottom surface of the hollow molding body 10 abuts against the upper surface of the lower-layer reinforcing bar 44, as shown in Fig. 6, and it is even more preferable that the upper surface of the hollow molding body 10 abuts against or is located close to the lower surface of the upper-layer reinforcing bar 24 in this state. In particular, by abutting the hollow molding body 10 against the lower-layer reinforcing bar 44 and the upper-layer reinforcing bar 24 to the extent that friction occurs between the reinforcing bars and the hollow molding body 10, it is possible to prevent the hollow molding body 10 from shifting in the extension direction of the through shaft 52.

[0038] The penetration shaft 52 only needs to have a strength that prevents significant curvature, bending, or breakage when concrete 50 is poured with the penetration shaft 52 passing through the hollow molded body 10. Therefore, the penetration shaft 52 may be made of rebar similar to the rebar used for the upper layer rebars 24 and the lower layer rebars 44, or may be made of other hard members such as long resin members instead of rebars, or a rope or wire that can be fixed in a tightly tensed state may be used as the penetration shaft 52.

[0039] The extension direction of the through shafts 52 is not particularly limited, but in this embodiment, the through shafts 52 extend in a direction parallel to the upper layer reinforcing bars 24 and the lower layer reinforcing bars 44. The number of through shafts 52 is also not particularly limited, and can be determined appropriately depending on the area of ​​the lightweight concrete slab 130, the number of hollow molded bodies 10 to be buried, etc.

[0040] In this embodiment, as shown in FIG. 7B, the middle layer 37 has only a plurality of through axes 52 that are parallel to each other in the surface direction of the middle layer 37. However, from the viewpoint of further increasing the strength of the lightweight concrete slab 130, as a modified example not shown, reinforcing bars or the like may be provided in the middle layer 37 in a direction parallel to or intersecting the through axes 52.

[0041] The number of hollow moldings 10 attached to one through shaft 52 may be one or more, but as shown in Figures 6 and 7, in a lightweight concrete slab 130 having multiple hollow moldings 10 arranged in one direction, a common through shaft 52 passes through the through holes 54 provided in each of the multiple hollow moldings 10, which can be said to be one preferred embodiment of the present invention. For example, as shown in Figure 7B, when multiple hollow moldings 10 are arranged evenly in the vertical and horizontal directions, it is preferable to provide multiple through shafts 52 extending in one direction (the left-right direction on the paper in Figure 7B) and attach multiple hollow moldings 10 to each through shaft 52, as this simplifies construction.

[0042] 5A, the hollow molded body 10 in this embodiment is an assembled molded product that includes at least a first part 10a and a second part 10b that are separable from each other. Dividing the hollow molded body 10 into multiple parts in this manner improves transportability and handling, and also simplifies the attachment work to the through shaft 52. In hollow molded body 10 of this embodiment, through hole 54 is defined by first cutout portion 55 provided on a predetermined outer edge of first part 10a and second cutout portion 56 provided on a predetermined outer edge of second part 10b. In this embodiment, in which two opposing parts have cutout portions and through hole 54 is defined by aligning the cutout portions with each other, through shaft 52 is placed in the cutout portion of one part and then the other part is placed over the other part to form a combined molded product (i.e., hollow molded body 10). This easily achieves a state in which through shaft 52 passes through through hole 54, resulting in excellent ease of construction.

[0043] The means for combining and maintaining the first part 10a and the second part 10b described above is not particularly limited. Examples of suitable methods include adhesive bonding, such as applying an adhesive to opposing surfaces, and fastening using a fastening member such as a string. As shown in FIG. 5A , the hollow molded body 10 used in this embodiment preferably includes an engaging portion 60 in the first part 10a and the second part 10b that allows them to engage with each other. When the engaging portion 60 is engaged, the first notch 55 and the second notch 56 face each other, forming a through-hole 54. The engaging portion 60 is a means for engaging portions of the first part 10a and the second part 10b to maintain the combined state of the hollow molded body 10, which is a combined molded product. In this embodiment, the engaging portion 60 is a protrusion 62 provided on the first part 10a and a fitting hole 64 provided in the second part 10b at a position facing the protrusion 62. In this embodiment, the hollow molded body 10 can be constructed by a simple operation of simply fitting the projections 62 into the fitting holes 64 from above. In the present invention, other engaging means or mating means than the above-described projections 62 and mating holes 64 can be appropriately employed as the engaging portion 60.

[0044] The above description of the third embodiment does not limit the present invention in any way. For example, as a modification of this embodiment, the present invention includes an embodiment in which, in hollow molded body 10 having at least first part 10a and second part 10b, a hole for through hole 54 is formed in one part and the other part does not have through hole 54 or a notch for forming through hole 54, and an embodiment in which, instead of hollow molded body 10 that can be separated into multiple parts as described above, a hollow molded body 10 (not shown) that is an integrally molded product having hollow portion 12 therein and through hole 54 formed therein is used.

[0045] [Construction method for lightweight concrete slab 130] Next, a construction method for constructing a lightweight concrete floor slab 130 including a middle layer reinforcement step will be described with reference to Fig. 7. In the following description, an embodiment using a hollow molded body 10 consisting of a first part 10a and a second part 10b will be described as an example. First, a formwork for pouring concrete (not shown) is formed. 7A, the lower layer reinforcing bars 41 and the lower layer reinforcing bars 42 are arranged in a grid pattern at equal intervals, thereby forming the lower layer reinforcing bars 44. Next, a hollow molded body placement step is performed. Specifically, as shown in FIG. 7B , the second part 10b is placed at a predetermined position on the upper surface of the lower layer reinforcing bar 44, and the through shaft 52 is provided along the second cutout portion 56 of the second part 10b. Then, although not shown, the protrusion 62 on the first part 10a is engaged with the engagement hole 64 on the second part 10b to place the engagement portion 60 in an engaged state, and the hollow molded body 10 is placed on the upper surface of the lower layer reinforcing bar 44. As a result, the first cutout portion 55 and the second cutout portion 56 face each other to form the through hole 54, and the through hole 54 is penetrated by the through shaft 52. Next, the upper layer reinforcement step is carried out. Specifically, the upper end main reinforcements 21 and the upper end distribution reinforcements 22 are arranged in a grid pattern at equal intervals in the surface direction so as to cover the upper surface of the hollow molded body 10. To prevent the hollow molded body 10 from rotating around the penetration shaft 52 as the axis of rotation when concrete is poured, the distance between the lower surface of the upper layer reinforcing bars 24 and the upper surface of the hollow molded body 10 is preferably between 0 cm and 10 cm, and more preferably substantially 0 cm. Next, a concrete pouring step is carried out to pour concrete 50 so that it extends from below the lower layer reinforcing bars 44 to a height that fully covers the upper layer reinforcing bars 42. The poured concrete is allowed to fully harden, thereby completing the lightweight concrete deck 130.

[0046] The construction method for the lightweight concrete slab 130 is not limited to the above description. For example, after the lower layer reinforcement step is performed, a hollow molded body placement step may be performed in which the through shaft 52 is first provided, and then the second part 10b is inserted below the through shaft 52, and the opposing first part 10a is engaged with the second part 10b to place the hollow molded body 10.

[0047] When an integrally molded product having a through hole 54 (not shown) is used as the hollow molded product 10, the hollow molded product arrangement step can be carried out by attaching a predetermined number of hollow molded products 10 to a long member constituting the through shaft 52 in advance, then attaching both ends of the long member in a stretched state to appropriate locations to provide the through shaft 52, and adjusting the positions of the hollow molded products 10 attached to the through shaft 52 as necessary. The steps other than the hollow molded product arrangement step can be carried out in the same manner as the steps in this embodiment described above. In addition, in this embodiment, an example has been shown in which a through shaft is placed in the middle layer and a hollow molded body is attached to it, but as a modified example not shown, the present invention can also be configured in which the layer reinforced using long members is a single layer, and an appropriately selected member from the long members that make up the single layer is used as a through shaft and a hollow molded body is attached to it.

[0048] <Fourth embodiment> A fourth embodiment of the present invention will be described below with reference to Fig. 8. The fourth embodiment is implemented in the same manner as the third embodiment, except for the number of through holes 54 in the hollow molded body 10 and the number of through shafts 52 passing through them. Therefore, the fourth embodiment will be described mainly focusing on the differences from the third embodiment, and the description of the third embodiment will be referred to for other explanations as appropriate. FIG. 8A is an exploded perspective view of a hollow molded body 10 used in a fourth embodiment of the present invention, and FIG. 8B is a perspective view of the hollow molded body 10 shown in FIG. 8A with a through shaft 52 passing through it.

[0049] The hollow molded body 10 of this embodiment has two or more through hole sets, each consisting of two opposing through holes. That is, as shown in Fig. 8B, the hollow molded body 10 of this embodiment has a through hole set consisting of opposing first through holes 54A, 54A through which a first through shaft 52A passes, and a through hole set consisting of opposing second through holes 54B, 54B through which a second through shaft 52B passes. When there is one through-hole set as in the third embodiment, one through-shaft 52 is passed through, but the hollow molded body 10 in this embodiment has two or more through-hole sets, so two or more through-shafts 52 can pass through the interior. A hollow molded body 10 having multiple through-shafts 52 passing through it is preferable from the viewpoint that the position of the hollow molded body 10 is that much more stable and the position of the hollow molded body 10 is well maintained even when the concrete 50 is poured.

[0050] In particular, in this embodiment, the first through axis 52A and the second through axis 52B passing through these two through hole sets intersect with each other in a top view. By providing two through hole sets at positions where the two through axes 52 can pass through so as to intersect with each other in this manner, the position of the hollow molded body 10 can be restricted in both the vertical and horizontal directions. In order to have the two through axes intersect in a top view, it is advisable to determine the positions of the first through holes 54A and the second through holes 54B so that the line connecting the first through holes 54A that constitute the first through hole set intersects with the line connecting the second through holes 54B that constitute the second through hole set in a top view.

[0051] For example, in the case of hollow molded body 10 composed of first part 10a and second part 10b, as shown in FIG. 8A , first part 10a may have opposing first cutouts 55A and opposing second cutouts 55B along a predetermined outer edge thereof. Similarly, second part 10b may have opposing first cutouts 56A and opposing second cutouts 56B along a predetermined outer edge thereof. When first part 10a and second part 10b are assembled to form hollow molded body 10, first through holes 54A and 54A are formed by aligning first cutouts 55A and first cutouts 56A facing each other, and second through holes 54B and 54B are formed by aligning second cutouts 55B and second cutouts 56B facing each other. This forms two sets of through holes, allowing the first through shaft 52A and the second through shaft 52B to pass through.

[0052] When a hard, long member such as a rebar having a significant diameter is used as the through shaft and the first through shaft 52A and the second through shaft 52B intersect in top view, the following points should be taken into consideration: That is, when the second through shaft 52B is made to pass above the first through shaft 52A as shown in Fig. 8B, the through hole (second through holes 54B, 54B) for passing the second through shaft 52B should be positioned higher than the through hole (first through holes 54A, 54A) for passing the first through shaft 52A. In order to position the second through hole 54B higher than the first through hole 54A, in this embodiment, as shown in Figure 8A, the cutout portion constituting the first through hole 54A has a lower cutout portion (second cutout portion 56A) that is deeper toward the bottom than the upper cutout portion (first cutout portion 55A), while the cutout portion constituting the second through hole 54B has an upper cutout portion (first cutout portion 55B) that is deeper toward the top than the lower cutout portion (second cutout portion 56B). As an example, it is preferable that the depths of the first cutout portion 55A and the second cutout portion 56B are approximately the same, and that the depths of the first cutout portion 55B and the second cutout portion 56A are approximately the same.

[0053] In the fourth embodiment described above, the first part 10a and the second part 10b are mainly included. Although the embodiment in which the hollow molded body 10 has two or more through-hole sets has been described, the present invention encompasses an embodiment in which the hollow molded body, which is an integrally molded product, has two or more through-hole sets.

[0054] In the above, the present embodiment has been described taking as an example an aspect in which the two through-shafts 52 intersect inside the hollow molded body 10 when viewed from above, but the present invention does not exclude, as a modified example, an aspect in which two or more through-shafts 52 penetrate the hollow molded body 10 so as not to intersect inside the hollow molded body 10. Here, "non-intersecting" includes both a case in which the two through-shafts 52 are parallel inside the hollow molded body 10 and a case in which the two through-shafts 52 are non-parallel but do not intersect inside the hollow molded body 10. By providing two or more through shafts 52 that are parallel to each other in a top view, it is possible to prevent the hollow molded body 10 from rotating around the through shafts as axes of rotation. In an embodiment in which the through shafts 52 are parallel to each other in a top view, the positions of the first through holes 54A and the second through holes 54B are preferably determined so that the line connecting the second through holes 54B is parallel to the line connecting the first through holes 54A that constitute the first through hole set. Furthermore, by having two or more through-shafts 52 that are non-parallel and non-intersecting with each other in top view, it is possible to prevent the hollow molded body 10 from rotating around the through-shafts 52 as the rotation axis, and also to prevent the position of the hollow molded body 10 from shifting in the extension direction of each through-shaft 52. In other words, when there are two or more through-shafts 52 that are non-parallel and non-intersecting with each other, the same effect as in the third embodiment can be achieved in terms of maintaining the position of the hollow molded body 10.

[0055] In the third and fourth embodiments, an example was shown in which one through shaft was made of one reinforcing bar, but in the present invention, one through shaft can also be made of two or more elongated members. In other words, even if two or more elongated members such as reinforcing bars are inserted through one through hole, they can be considered to form one shaft.

[0056] The above embodiment encompasses the following technical ideas. (1) A lightweight concrete slab characterized by having multiple hollow molded bodies embedded inside concrete reinforced with rigid long members. (2) The lightweight concrete slab according to claim 1, wherein the hollow molded body is a hollow column or a hollow cone. (3) A lightweight concrete slab according to claim 2, wherein the corners on the outer periphery of the hollow columnar body or hollow cone are chamfered. (4) The long members have at least two layers in the vertical direction, each layer being reinforced in a lattice pattern so that they intersect vertically and horizontally in the surface direction, and a hollow molding is disposed on the upper surface of the lower layer of the two layers, 4. A lightweight concrete slab according to claim 1, wherein the area of ​​the bottom surface of the hollow molded body, when viewed from above, is larger than the area of ​​one lattice formed by the elongated members in the lower layer. (5) A through axis is disposed parallel or perpendicular to the surface direction of the lightweight concrete floor slab and penetrates the hollow molded body, The hollow molded body has a through hole for passing the through shaft therethrough, 5. The lightweight concrete slab according to claim 1, wherein the hollow molded body is positioned by passing the through shaft (reinforcing bar) through the through hole. (6) A plurality of the hollow molded bodies are arranged in one direction, 6. The lightweight concrete slab according to claim 5, wherein the through-holes provided in each of the plurality of hollow molded bodies are passed through by the common through-axis. (7) The hollow molded body has two or more through-hole sets each consisting of two opposing through-holes, 7. The lightweight concrete slab according to claim 5, wherein two or more of the through shafts pass through the hollow molded body. (8) The hollow molded body has at least a first part and a second part that are separable from each other, A lightweight concrete deck slab described in any one of claims 5 to 7, wherein the through hole is constituted by a first cutout portion provided on a predetermined outer edge of the first part and a second cutout portion provided on a predetermined outer edge of the second part. (9) The first part and the second part have engaging portions that can engage with each other, 9. The lightweight concrete slab according to claim 8, wherein the hollow molded body is formed by engaging the engaging portions. (10) A lightweight concrete slab construction method for constructing a lightweight concrete slab according to any one of claims 1 to 9, Lower layer reinforcement process, where reinforcement is arranged in the lower layer; a hollow molded body arranging step of arranging a hollow molded body above the lower layer; and An upper layer reinforcement step is carried out in order to reinforce the upper layer located above the lower layer, The lightweight concrete deck is then subjected to a pouring step of pouring concrete. [Explanation of symbols]

[0057] 10...Hollow molded body 10a...First part 10b...Second part 12...Hollow part 14 Corner 15...Top surface 16 Bottom 21...Top main reinforcement 22...Top distribution bar 24. Upper layer reinforcing bars 31. Middle main reinforcement 32. Intermediate distribution reinforcement 34, 35...Middle layer reinforcing bars 36... Space 37...middle class 41...Lower end main reinforcement 42...Lower end distribution bar 44 Lower layer rebar 45...lattice 50...Concrete 52...Through shaft 52A...First through shaft 52B...Second through shaft 54...Through hole 54A...First through hole 54B...Second through hole 55, 55A, 55B...First notch 56, 56A, 56B... Second notch 60 Engagement part 62...protrusion 64...Mating hole 110, 120, 130 Lightweight concrete deck

Claims

1. A plurality of hollow moldings are embedded in concrete reinforced with rigid long members, A through axis is disposed parallel or perpendicular to the surface direction of the lightweight concrete floor slab and passes through the hollow molded body, The hollow molded body has a through hole for passing the through shaft therethrough, The through shaft is inserted through the through hole, thereby determining the position of the hollow molded body. The hollow molded body has at least a first part and a second part that are separable from each other, A lightweight concrete deck slab characterized in that the through hole is composed of a first cutout portion provided on a predetermined outer edge of the first part and a second cutout portion provided on a predetermined outer edge of the second part.

2. 2. The lightweight concrete slab according to claim 1, wherein the hollow molded body is a hollow column or a hollow cone.

3. 3. The lightweight concrete slab according to claim 2, wherein corners on the outer periphery of the hollow columnar body or hollow cone body are chamfered.

4. The long members have at least two layers in the vertical direction, each layer being formed by arranging reinforcement in a lattice pattern so that the reinforcement crosses vertically and horizontally in the surface direction, and a hollow molded body is disposed on the upper surface of the lower layer of the two layers, 4. A lightweight concrete slab according to claim 1, wherein, when viewed from above, the area of ​​the bottom surface of the hollow molded body is larger than the area of ​​one lattice formed by the elongated members in the lower layer.

5. a plurality of the hollow molded bodies arranged in one direction; The lightweight concrete slab according to any one of claims 1 to 4, wherein a common through axis passes through the through holes provided in each of the plurality of hollow molded bodies.

6. the hollow molded body has two or more through-hole sets each consisting of two opposing through-holes, The lightweight concrete slab according to any one of claims 1 to 5, wherein two or more of the through shafts penetrate through the hollow molded body.

7. the first part and the second part have engaging portions that are engageable with each other, The lightweight concrete slab according to any one of claims 1 to 6, wherein the hollow molded body is formed by engaging the engaging portions.

8. A lightweight concrete slab construction method for constructing the lightweight concrete slab according to any one of claims 1 to 7, Lower layer reinforcement process, where reinforcement is arranged in the lower layer; a hollow molded body arranging step of arranging a hollow molded body above the lower layer; and An upper layer reinforcement step is carried out in order to reinforce the upper layer located above the lower layer, A lightweight concrete slab construction method characterized by carrying out a pouring step of pouring concrete.

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