JP2005054444A - Precast concrete plate, concrete slab using the same, and its construction method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a precast concrete board which can be constructed in a factory or at a construction site and can impart a camber to a slab though it is a concrete permanent form and ready-made, a concrete slab using this board and its construction method. <P>SOLUTION: The permanent form 12 is made by fastening each precast concrete board 11 by wires 13, a reinforcement holder 15 is bound by horse bands 16 on the wires 13, and reinforcements 20 are arranged in the reinforcement holder 15. Thereafter, concrete is placed on the permanent form 12 to cure it. As a result, the concrete slab 10 can be made not only in a factory but also in a construction site. Further, the precast concrete board 11 can be ready-made and also a camber can be given to a concrete slab 10 althrough it has a concrete permanent form 12. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a precast concrete plate formed by dividing a discarded form for a concrete slab, a concrete slab using the precast concrete plate, and a construction method thereof.

  A flat slab construction method is known as a construction method of a flat roof slab or floor slab without a beam. At the time of this construction, first, a wooden plywood slab casting formwork is installed between the beams, and reinforcing bars are placed on the formwork. Next, a support washer was applied to support the formwork with a large number of pipe-made struts to support the concrete load poured into the formwork. For this reason, the work up to the placing of the concrete is complicated, and after the construction, the work of removing the formwork and the support column, which are the construction materials, is also necessary.

Therefore, as conventional techniques for solving these problems, (1) a slab method using a floor reinforcing bar truss form described in Non-Patent Document 1, and (2) an slenoid void type described in Non-Patent Document 2 Synthetic slab construction methods with frames have been developed.
(1) According to the construction method of Non-Patent Document 1, first, a floor reinforcing bar with a truss structure is arranged at a fixed pitch on a metal panel-made formwork in the field. Thereafter, the concrete is poured into a discarded formwork, which is cured and slabs are placed. In this way, since the metal panel-made formwork is used, the slab can be peeled in consideration of the deflection due to the construction load in advance.

  (2) According to the method of Non-Patent Document 2, first, the upper end of the slab is placed on the omni-void slab plate in the factory. Thereafter, the concrete is poured onto the omni-void slab plate, cured, and a hollow slab is placed. The omnia void plate is a plate material in which an omlenoid frame made of foamed styrene for forming a hollow portion is attached to an omni plate (precast reinforced concrete plate) also serving as a mold frame with the omni truss as a part of the main reinforcement. In the construction method of Patent Document 2, hollow voids can be formed inside the slab by the slenoid void form, and the weight of the concrete floor can be reduced.

Fujiaki Co., Ltd., “FERRO DECK” catalog P3, “Fellow deck guide” (revised in April 1991) Takamura Construction Co., Ltd., Omnia Slab Design and Construction Guideline Using Eslenvoid Form P1, “1 Purpose of Establishing Omnia Slab Design and Construction Procedure Using Eslenvoid Form” (November 1988 version)

  However, according to the construction method of Non-Patent Document 1, a mold for forming a hollow portion such as the eslenoid mold is not used. Therefore, there is no hollow void in the slab, and the concrete floor cannot be reduced in weight. Moreover, it was limited to the construction method which produces a slab in a factory.

Moreover, according to the construction method of Non-Patent Document 2, the omni board which constitutes the discarded mold is a concrete board. Therefore, it was impossible to peel off the slab after placing. Further, as in the case of Non-Patent Document 1, it is limited to the production of a slab in a factory. By forming the hollow void inside, the slab is reduced in weight. Therefore, it is possible to produce a large slab, but in that case, a large work space is required in the factory.
Further, the slabs to be placed are placed one by one according to the size of each room of the building. For this reason, the production was made according to the order, and it was not possible to make it in advance.

The present invention is a precast concrete board that can be applied not only in a factory but also on site, and can peel off a slab while having a concrete formwork, and can be further built. The purpose is to provide a concrete slab using slab and its construction method.
Another object of the present invention is to provide a concrete slab capable of reducing the weight of the produced slab and a method for constructing the concrete slab.
Furthermore, this invention aims at providing the construction method of the concrete slab which can place concrete slab by utilization of a joist even when the wide working space for placing the slab on the spot cannot be secured. .

  The precast concrete board according to claim 1 is a precast concrete board comprising a plurality of abandoned formwork, penetrating through an end face abutted on an adjacent precast concrete board and an end face on the opposite side. In addition, an insertion hole for a bendable fastening wire that fastens each precast concrete plate constituting the discard mold is formed, and a part of the surface on the concrete placing side is in communication with the insertion hole so that a reinforcing bar is provided. It is the precast concrete board in which the notch part which fixes the base part of the reinforcing bar holder to hold | maintain to the said fastening wire was formed.

  According to the first aspect of the present invention, first, a plurality of precast concrete plates are abutted against each other between adjacent precast concrete plates at the end face on the side where each insertion hole is formed. Thereafter, a fastening wire is inserted into each insertion hole, and each precast concrete board is fastened with the fastening wire to produce one discarded mold. In that case, the base part of a reinforcing bar holder is inserted in a predetermined notch part, and the base part of this reinforcing bar holder is fixed to a fastening wire. Thereafter, the reinforcing bar is held in the reinforcing bar holder, and then, for example, concrete is discarded and poured into a mold to be hardened, and a concrete slab is placed. Or, for example, a pair of abandoned molds are spaced apart so as to define a concrete casting void for pouring concrete, and then concrete is poured into the concrete casting void and hardened to separate the concrete wall from the slab. Placing concrete structures such as

  This makes it possible to construct a concrete structure including a slab not only at the factory but also at the site. Moreover, a precast concrete board can be pre-made. Furthermore, when the cast object is a concrete slab, the concrete slab can be peeled off while having a concrete formwork by adjusting the fastening force of each precast concrete plate by the fastening wire. .

The usage of the discarded formwork is not limited. For example, slabs, walls, pillars, foundations, etc. can be employed.
The shape of the discarded mold is appropriately changed according to the concrete structure to be placed. The number of precast concrete plates constituting the discarded form is not limited as long as it is two or more. The discarded formwork is produced by connecting the precast concrete plates to be used in a state where the end surfaces on the side where the respective insertion holes are formed are sequentially abutted with each other.
The material, shape, and size of the precast concrete board are not limited. For example, a concrete panel made of a high-pressure press of, for example, 100 t / cm ² may be used in which concrete is added with predetermined amounts of reinforcing synthetic resin fibers, blast furnace slag, and stone powder.
The cross-sectional shape of the insertion hole is not limited. For example, a circle, an ellipse, a triangle, or a polygon more than a quadrangle can be employed. Further, the size of the insertion hole is not limited. Further, the number of insertion holes may be one or two or more.

Various wires (steel strands) can be adopted as the fastening wire. In addition, for example, a synthetic resin rope or the like can be used.
The method of fixing the base part of the reinforcing bar holder to the fastening wire is not limited. For example, welding may be used, or fastening using a wire, a metal or synthetic resin fastening string, or the like may be used.
The shape and size of the notch are not limited. What is necessary is just to be able to insert the base of the reinforcing bar holder.
The material, shape, and size of the reinforcing bar holder are not limited. For example, a steel wire may be bent into a substantially V shape. The reinforcing bar holder is provided with a reinforcing bar holding part for holding the reinforcing bar. The material, shape, size, and number of formation of the reinforcing bar holding part are not limited.

  The concrete slab according to claim 2 is inserted in series with respect to a plurality of precast concrete plates according to claim 1 and the insertion holes of each precast concrete plate, and the precast concrete plate is fastened to form a discarded formwork. A bendable fastening wire to be produced, a reinforcing bar holder according to claim 1, a reinforcing bar held by the reinforcing bar holder, and a fixing jig for fixing a base portion of the reinforcing bar holder to the fastening wire inserted through the insertion hole. And a hollow void forming body that is disposed on the upper surface of the discarded mold frame and forms a hollow void in the concrete slab after placing, and a concrete body that has been poured and cured on the discarded mold frame. It is a concrete slab.

According to the second aspect of the present invention, the discard mold is produced by connecting a plurality of precast concrete plates and fastening the precast concrete plates with fastening wires. In that case, the base part of a reinforcing bar holder is inserted in a predetermined notch part, and the base part of a reinforcing bar holder is fixed to a fastening wire with a fixing jig. Then, while holding a reinforcing bar in a reinforcing bar holder, a hollow void formation body is arrange | positioned on the upper surface of a discard mold. Thereafter, the concrete is discarded and poured onto a formwork, which is hardened and a concrete slab is placed.
As a result, it is possible to construct a concrete slab not only at the factory but also at the site. Moreover, a precast concrete board can be pre-made. In this case, it is possible to make a discarded formwork. When the design of the discarded formwork is changed, the fastening of the fastening wire may be released and the number of precast concrete plates constituting the discarded formwork may be changed. Further, by adjusting the fastening force of the fastening wire to each precast concrete plate, it is possible to peel off the concrete slab while having a concrete formwork. Furthermore, since the hollow void is formed in the concrete slab, the concrete slab can be reduced in weight.

The connection of the base part of the reinforcing bar holder to the fastening wire may be performed using a fixing jig. The material, structure, and size of the fixture are not limited. For example, an iron or stainless steel hose belt, a wire, a plastic string, or the like can be employed.
The material, shape, and size of the hollow void forming body, the installation area on the upper surface of the discarded formwork, the number used, etc. are not limited.
As a raw material of the hollow void forming body, for example, various synthetic resins such as styrene foam, various metals, and the like can be employed. The hollow void forming body is fixed to a part of a reinforcing bar or a part of a reinforcing bar holder using, for example, a wire clip.

  According to a third aspect of the present invention, there is provided a method for constructing a concrete slab, wherein a plurality of precast concrete plates according to claim 1 are abutted against each other, and a temporary disposal temporary frame forming step for temporarily disposing a single disposable mold frame, Insert a bendable fastening wire into the insertion hole, and then fasten each precast concrete plate with the fastening wire, and prepare a discarded mold frame, and a concrete casting side of each precast concrete plate A holder connecting step of connecting a base part of a reinforcing bar holder holding a reinforcing reinforcing bar to the fastening wire through a notch part formed in part of a surface in communication with the insertion hole; and A reinforcing bar holding step for reinforcing bars and a hollow void forming body for forming hollow voids in the concrete slab after placing on the upper surface of the discarded formwork And de securing step, pouring concrete on the upper surface of the discarded formwork, then, is a method for constructing a concrete slab and a slab striking setting step of pouring a concrete slab and cured.

According to the invention of claim 3, the discarded form frame is produced by connecting a plurality of precast concrete plates in a butted state and fastening each precast concrete plate with a fastening wire. In that case, the base part of a reinforcing bar holder is inserted in a predetermined notch part, and the base part of a reinforcing bar holder is fixed to a fastening wire. Subsequently, while holding a reinforcing bar in a reinforcing bar holder, a hollow void formation body is arrange | positioned on the upper surface of a discard mold. Then, the concrete is thrown away onto the formwork, hardened, and a concrete slab is placed.
As a result, it is possible to construct a concrete slab not only at the factory but also at the site. Moreover, a precast concrete board can be pre-made. In addition, the concrete slab can be peeled off while having a concrete formwork. Furthermore, since a hollow void is formed in the concrete slab, the weight of the concrete slab can be reduced.

The concrete slab construction method according to claim 4 is the concrete slab construction method according to claim 3, wherein the bar arrangement step is performed by spot welding of the reinforcing bar holder and the fastening wire in a factory.
According to the invention of claim 4, in the factory, the reinforcing bar holder and the fastening wire can be firmly connected in a short time by spot welding.

The method for constructing a concrete slab according to claim 5 is the method for constructing a concrete slab according to claim 3, wherein the bar arrangement step is performed by fastening with a fastening jig between the reinforcing bar holder and the fastening wire at the site. is there.
According to the invention of claim 5, the reinforcing bar holder and the fastening wire are fastened by the fastening jig not at the factory but at the site. Thereby, on-site construction of a concrete slab becomes possible.

In the method for constructing a concrete slab according to claim 6, the formwork temporary step is performed by horizontally placing each precast concrete plate between a plurality of joists arranged in parallel at a predetermined pitch on the site. It is a construction method of the concrete slab of any one of Claims 3-5.
According to the sixth aspect of the present invention, when a large work space for placing the slab on the site cannot be secured, the concrete slab can be placed using joists.
The number and size of joists used are not limited. The joist may be removed after placing the concrete slab or left as it is.

  According to the precast concrete board of Claim 1, a discard mold is produced by fastening a plurality of precast concrete boards with a fastening wire. On the other hand, the base part of the reinforcing bar holder is fixed to the fastening wire, and after the reinforcing bars are arranged in the reinforcing bar holder, the concrete is thrown into the formwork and is cured. As a result, the construction of the concrete structure including the concrete slab becomes possible not only at the factory but also at the site. Moreover, a precast concrete board can be pre-made. Further, when the produced product is a concrete slab, the concrete slab can be peeled while having a concrete formwork.

According to the concrete slab of claim 2 and the concrete slab construction method of claim 3, in addition to the effect of claim 1, hollow voids are formed in the concrete slab, so that the concrete slab is lightened. be able to.
Furthermore, according to the concrete slab construction method of the sixth aspect, even when a large work space for placing the slab on the site cannot be secured, the concrete slab can be placed using joists.

  Embodiments of the present invention will be described below with reference to the drawings. First, a precast concrete plate of Example 1 in which concrete is previously placed in a factory, a concrete slab using the same, and a construction method thereof will be described.

  1 to 5, reference numeral 10 denotes a concrete slab according to the first embodiment of the present invention. The concrete slab 10 is inserted through an end face that is abutted against an adjacent precast concrete plate 11 and an end face on the opposite side. A plurality of precast concrete plates 11 with holes 11a formed therein, a single mold 12 formed by connecting the plurality of precast concrete plates 11, and a through hole 11a of each precast concrete plate 11 in series. A bendable wire (fastening wire) 13 that is inserted and fastened to each precast concrete plate 11 to form a discarded mold 12 and a part of the concrete placing side surface that communicates with the insertion hole 11a. Reinforcing bar holder 15 in which the base part is inserted into the cutout part 14 and the base part of the reinforcing bar holder 15 are inserted into the insertion hole 11a. A hose band tool (fixing jig) 16 to be fixed to 13, a hollow void forming body 17 which is disposed on the upper surface of the discarded mold frame 12 and forms a hollow void in the concrete slab 10 after placement, and a discarded mold frame 12 and a concrete body 18 that has been poured and hardened.

The precast concrete board 11 is a concrete panel produced by using a high-pressure press of 100 t / cm ² of concrete added with predetermined amounts of reinforcing synthetic resin fibers, blast furnace slag, and stone powder. The discard mold 12 is formed by connecting several tens of precast concrete plates 11 in the vertical and horizontal directions. The shape of the precast concrete board 11 has a rectangular shape with a length of 600 mm, a width of 300 mm, and a thickness of 30 mm. The weight of the precast concrete board 11 is about 8 to 10 kg so that the operator can easily carry it.
The outer surface of the precast concrete board 11 is flat. On the other hand, a total of six ribs 19 extending in the panel width direction are formed at a predetermined pitch in the panel length direction on the inner surface (concrete casting surface) side of the precast concrete plate 11. By providing the rib 19, the integrity of the concrete poured into the concrete and the precast concrete plate 11 is increased. In each rib 19, an insertion hole 11 a (diameter 9 mm) of the wire 13 (diameter 6 mm) extending in the length direction of the rib 19 is formed.

A total of five notches having different shapes are formed at both ends of each rib 19, the center, and both sides near the center. The shape of each notch is such that the notch part 14a on the center side of the rib 19 is a long hole shape that is long in the length direction of the rib 19, the notch parts 14b on both sides near the center part are round holes, and both end sides of the rib 19 The notch portion 14 is long in the length direction of the rib 19, and has a short hole shape that is only about half the length of the notch portion 14 a on the center side of the rib 19. Among the cutout portions 14 of the two ribs 19 disposed on both ends in the long width direction of the precast concrete plate 11, the storage portion 14d of the hose band tool 16 is integrally formed with the cutout portion 14 on each one end side. Is formed. At the time of placing the concrete, a part of the concrete poured into the discarded mold 12 flows into the corresponding insertion holes 11a through the notches 14, and the precast concrete plate 11 and the wires 13 pierced through the insertion holes 11a. And unite.
Between each rib 19 on the inner surface side of each precast concrete plate 11, a recess 11b having a circular arc shape in cross section and a rectangular shape in plan view is formed. Recesses 11c for introducing the concrete poured from the outside in the length direction of the ribs 19 into the respective concave portions 11b are formed at both end portions in the length direction of the forming portions of the respective concave portions 11b.

  The reinforcing bar holder 15 is a frame member having a substantially right-angled triangle shape, and is mainly formed on a holder main body 15a bent into a substantially V-shape and ends on the bent side (upper side) of both sides constituting the holder main body 15a. There are two sets of short bars 15b that are horizontally mounted, and two long bars 15c that are horizontally mounted near the end of the opening side (lower side) of both sides. The holder body 15a is made of a steel wire having a diameter of 6 mm (the same applies to the short bar 15b and the long bar 15c). Both end portions (lower end portions) of the holder main body 15a are bent at right angles to the length direction of the holder main body 15a to form connection portions 15d. Each connecting portion 15 d is inserted into the cutout portion 14 and fastened to a part of the wire 13 via the hose band tool 16.

  When the reinforcing bar holder 15 is in use, one of the two sides is vertically disposed on the precast concrete plate 11, and the long bar 15 c constituting the short side is parallel to the inner surface of the precast concrete plate 11. Placed in. The long bar 15c and the short bar 15b are parallel. The lower rods of the long bar 15c and the short bar 15b have their respective one side end portions protruding outward. These protrusions 15e are bent toward the bent portion side of the holder body 15a. A pair of reinforcing bars 20 is held by the bent protrusion 15e. Further, the upper bars of the long bar 15c and the short bar 15b have end portions on one side projecting outwardly, and these projecting parts 15e are perpendicular to the direction perpendicular to the length direction of each bar. Is bent. A part of each reinforcing bar 20 is placed on each bent portion 15f. In the first embodiment, in the factory, the bent portions 15f and the reinforcing bars 20 are firmly connected by welding.

The hose band tool 16 has a main body socket 16a and a short metal band 16b attached to the main body socket 16a. A large number of small holes are formed in the band 16b at a predetermined pitch. Above the main body socket 16a, a head of a bolt 16c that adjusts a fastening force incorporated rotatably in the main body socket 16a protrudes. By rotating the bolt 16c in an arbitrary direction with a spanner or the like (not shown), the band 16b is squeezed or loosened by the band fastening structure built in the main body socket 16a.
The hollow void forming body 17 is a member made of expanded polystyrene similar to one side of the monaca skin having a square shape in plan view, and is disposed one by one at the center of each precast concrete plate 11. Each hollow void forming body 17 has a length of 400 mm, a width of 300 mm, and a height of 120 mm (for slab thickness of 250 mm) or 170 mm (for slab thickness of 300 mm). On the upper plate of each hollow void forming body 17, a cross-shaped recess is formed in a plan view connecting the middle of each side.
Each hollow void forming body 17 is attached to the precast concrete plate 11 using a large number of clips 21 obtained by bending thin piano wires into a substantially W shape. Specifically, one end portion of the clip 21 is hooked to the clip hole 17a formed at the opening side end portion of each corner of each hollow void forming body 17, and the other end portion of the clip 21 is attached to the long rod. It hooks on a part of the lower reinforcing bar 20 connected to 15c.

Next, with reference to FIGS. 1-5, the construction method of the concrete slab 10 of Example 1 is demonstrated.
First, the discard form 12 is assembled. A predetermined number of precast concrete plates 11 are brought into contact with the floor of the factory, and a single discarded form 12 is temporarily installed. The number of discarded molds 12 is appropriately selected depending on the size of the concrete slab 10 to be produced. The wires 13 are respectively inserted into the insertion holes 11a of the two ribs 19 arranged on both end sides of each precast concrete plate 11 in the long width direction. At that time, the hose band tool 16 is previously stored in the cutout portion 14 with each storage portion 14d. Thereby, in each hose band tool 16, the wire 13 is inserted into an internal passage formed by bending the band 16b in an annular shape.

Thereafter, the wires 13 are pulled outwardly at both ends in the lengthwise direction of the discarded mold 12 via the washers 22 and the fastening nuts 23 to fasten the precast concrete plates 11. Thereby, the discard mold 12 is produced. At this time, the tensile force of each wire 13 is adjusted, the deflection due to the construction load is taken into consideration in advance, and the predetermined form is given to the discard mold 12.
Then, the bent portion 15f on the base side of the reinforcing bar holder 15 is inserted into the internal passage of the hose band tool 16 between the adjacent cutout portions 14 with the storage portions 14d. Then, the head of each bolt 16 c is rotated to the fastening side by a spanner, and each rebar holder 15 is firmly fixed to the wire 13. Thereby, each reinforcing bar holder 15 is erected on the precast concrete board 11. At this time, each reinforcing bar holder 15 is planted with the protruding portion 15e side facing the adjacent precast concrete plate 11 side.
Next, in each reinforcing bar holder 15, the corresponding reinforcing bars 20 are respectively placed on the upper and lower protruding parts 15 e, and this state is maintained, and each protruding part 15 e and a part of the reinforcing bar 20 are spot welded. Although not shown, instead of spot welding, fastening with a hose band tool (fastening jig) 16 may be employed. If the hose band tool 16 is used, various welding facilities and welders are not required. Alternatively, it may be fastened with an inexpensive wire. After welding, another reinforcing bar 20 is arranged to be orthogonal to each reinforcing bar 20. The intersection between the reinforcing bars 20 may be spot welded or fastened with a wire or the like.

Thereafter, the hollow void forming body 17 is disposed on the upper surface of the discard mold 12. Each hollow void forming body 17 is arranged one by one at the center of the corresponding precast concrete plate 11. The method of fixing each hollow void forming body 17 to the precast concrete plate 11 is as follows. First, one end of the clip 21 is hooked in the clip hole 17a formed in each corner of each hollow void forming body 17, and then the clip 21 This is performed by hooking the other end of the lower end of the lower end of the lower rebar 20 connected to the long bar 15c.
Next, an amount of concrete having a thickness of 200 to 300 mm is poured into the upper surface of the discard mold 12 and cured. Thereby, the concrete body 18 which has a hollow void inside is laid. In this way, the concrete slab 10 is produced.

  In this way, a discarded mold 12 is prepared by fastening a large number of precast concrete plates 11 with wires 13, the reinforcing bar holder 15 is fixed to the wires 13, the reinforcing bars 20 are arranged on the reinforcing bar holder 15, and the concrete is Pour onto the throwing mold 12 to cure it. As a result, the concrete slab 10 can be constructed not only at the factory but also at the site. In addition, the precast concrete plate 11 constituting the discarded mold 12 can be made and placed. By increasing / decreasing the number of precast concrete plates 11, it is possible to produce a discarded mold 12 corresponding to the floor area. Furthermore, the concrete slab 10 can be peeled off by adjusting the fastening force (tensile force) of the wire 13 while having the concrete formwork 12 made of concrete. Moreover, since the hollow void is formed in the concrete slab 10, the weight of the concrete slab 10 can be reduced.

Next, with reference to FIG. 6, the construction method of the concrete slab of Example 2 of this invention is demonstrated.
The feature of the invention of the second embodiment is that, when the discarded formwork 12 is temporarily constructed when the concrete slab 30 is constructed, the discarded formwork 12 is assembled by using the joists 31 arranged in parallel at a predetermined pitch on the floor of the site. is there.
That is, first, the length direction of the precast concrete board 11 is directed between the joists 31 and the joists 31 in a direction orthogonal to the length direction of the joists 31, and the precast concrete boards 11 are respectively placed horizontally. In this way, a predetermined number of precast concrete plates 11 are brought into contact with each other, and one discarded mold 12 is temporarily installed. Thereby, even if it is not possible to secure a wide working space for placing the concrete slab 30 on site, the concrete slab 30 of the present invention can be easily placed using the joists 31.
In the second embodiment, it is not always necessary to fasten each precast concrete plate 11 with the wire 13.
Other configurations, operations, and effects are substantially the same as those of the first embodiment, and thus description thereof is omitted.

It is a perspective view which shows the use condition of the precast concrete board which concerns on Example 1 of this invention. It is a top view which shows the use condition of the precast concrete board which concerns on Example 1 of this invention. It is a principal part expanded sectional view of the concrete slab which concerns on Example 1 of this invention. It is a perspective view which shows the use condition of the fixing jig used for the concrete slab which concerns on Example 1 of this invention. It is a side view of the precast concrete board which concerns on Example 1 of this invention. It is a principal part expanded sectional view of the concrete slab which concerns on Example 2 of this invention.

Explanation of symbols

10 Concrete slab,
11 Precast concrete board,
11a insertion hole,
12 Abandoned formwork,
13 wire (fastening wire),
14 Notch,
15 Rebar holder,
16 Hose band (fixing jig),
17 Hollow void forming body,
18 Concrete body,
20 rebar,
31 Jouda.

Claims (6)

It is a precast concrete board composed of a single discarded formwork,
Through the end face that is abutted against the adjacent precast concrete board and the end face on the opposite side, an insertion hole for a bendable fastening wire material that fastens each precast concrete board constituting the discard mold is formed,
A precast concrete plate in which a notch portion is formed in a part of a surface on a concrete placing side, and is communicated with the insertion hole to fix a base portion of a reinforcing bar holder for holding a reinforcing bar to the fastening wire. A plurality of precast concrete boards according to claim 1;
A flexible fastening wire that is inserted in a series with respect to the insertion hole of each precast concrete plate, and that creates a discarded mold by fastening each precast concrete plate,
A reinforcing bar holder according to claim 1;
A reinforcing bar held by the reinforcing bar holder;
A fixing jig for fixing the base of the reinforcing bar holder to the fastening wire inserted through the insertion hole,
A hollow void forming body that is disposed on the upper surface of the discarded formwork and forms a hollow void in the concrete slab after being placed;
A concrete slab provided with a concrete body that has been poured into the discarded mold and hardened. Abandoned mold temporary installation step of matching a plurality of precast concrete plates according to claim 1 to temporarily install one discarded mold;
Inserting a bendable fastening wire into the insertion hole of each temporarily installed precast concrete plate, and then fastening each precast concrete plate with the fastening wire, and producing the discarded mold frame,
A base part of a reinforcing bar holder for holding a reinforcing steel bar is connected to the fastening wire through a notch part formed in part of the surface of the concrete casting side of each precast concrete plate in communication with the insertion hole. A holder connecting step;
A bar arrangement process for holding the reinforcing bar in the reinforcing bar holder;
A hollow void securing step of disposing a hollow void forming body for forming a hollow void in the concrete slab after placement on the upper surface of the discard mold,
A concrete slab construction method comprising: pouring concrete onto the upper surface of the abandoned formwork, then curing the concrete and placing a concrete slab.   The method for constructing a concrete slab according to claim 3, wherein the bar arrangement step is performed by spot welding of the reinforcing bar holder and the fastening wire in a factory.   The said bar arrangement process is the construction method of the concrete slab of Claim 3 performed by the fastening by the fastening jig | tool with the said reinforcing bar holder and a fastening wire material in the field.   The said formwork temporary installation process is performed by laying each precast concrete board horizontally between the plurality of joists arranged in parallel at a predetermined pitch on the site. Construction method of concrete slab as described in 4.

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