JP2015208862A - Production method of half-precast slab and half-precast slab - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a production method of a half-precast slab which fixes spherical voids preliminarily to a half-precast slab and a half-precast slab.SOLUTION: A production method of a half-precast slab comprises forming a void containing part 21 in which voids A are arranged preliminarily on the surface of a half-precast constituent material 2 produced in a factory, putting a net body 8 on the voids each arranged in the void containing part 21 and pressing down the net body 8 with the horizontal reinforcement of lattice bodies s2 assembled vertically and laterally with steel bars so as to fix the voids A. In the field, a vertical reinforcement is arranged and bound to the lateral reinforcement, and then ready mixed concrete is placed. The fixation of the voids A suppresses floating of the voids A in placing of ready mixed concrete, and the ready mixed concrete can be hardened while keeping the voids A at proper positions with respect to steel bars.

Description

  The present invention relates to a half precast plate manufacturing method and a half precast plate.

  Conventionally, a concrete slab in which a molded product called a void formed in a rectangle, a sphere, or the like made of foamed styrene or the like is embedded in a concrete slab is known. This concrete slab is advantageous in that it is reduced in weight by voids and can take up a large area of floor slack.

In such a concrete slab, the following points should be noted.
1) In order to maintain the strength of the slab, there must be enough concrete around the reinforcing bars, and the distance between the void surface and the reinforcing bars must be more than a predetermined distance. It must be set correctly.
2) Since the specific gravity of voids against raw concrete is extremely small, buoyancy acts on the voids when placing concrete. For this reason, when placing concrete, it is necessary to securely fix the position of the void against buoyancy so that the void does not move.

On the other hand, in order to save labor in concrete slab construction, half precast concrete plates manufactured at the factory are placed as dual-use formwork at the site, top end reinforcement is placed on the top surface, and concrete cast slabs are constructed by placing cast-in-place concrete. There is a construction method. In such a half precast method, a type in which a void is previously installed on a half precast concrete plate has been proposed. However, spherical voids that have been installed in half precast concrete slabs have not been implemented in Japan. The reason is that, in order to ensure the void ratio, it is necessary to embed approximately 10 to 20 mm in the half precast plate, which may cause a large manufacturing cost and is substantially difficult. In addition, it has been difficult to cope with joining bars or the like for ensuring the integrity of the half precast plate and the top concrete.
On the other hand, as described in Patent Document 1, in the half precast plate, a structure in which voids are pushed into the ready-mixed concrete when the ready-mixed concrete is placed, and the voids are fixed with solidified concrete has been proposed. Yes.

Patent No. 5156227

  However, as mentioned in the above notes, it is not easy to harden the ready-mixed concrete while keeping the individual spherical voids immersed in the ready-mixed concrete while resisting buoyancy. Furthermore, in the technique described in Patent Document 1, a configuration in which a void is forcibly pushed into the ready-mixed concrete with an apparatus that holds a void is disclosed, but the apparatus becomes a large-scale apparatus and the initial cost is high. There was a problem.

  The present invention provides a method for producing a half precast plate and a half precast plate which can be inexpensively improved in work efficiency by providing a spherical void containing portion for positioning the spherical void on the surface of the half precast plate. It is in.

The present invention for solving the above problems has the following configuration.
(1) a placing process for placing ready-mixed concrete in a formwork;
A recess forming step of forming a concave void housing portion at a position where a plurality of voids are disposed;
After the ready-mixed concrete is hardened, a void placement step of placing the voids in the void accommodating portions,
A mesh body covering step of covering a void with a mesh body having a mesh smaller than the size of the void;
A half precast plate manufacturing method comprising: a net body fixing step of fixing a covered net body to a hardened concrete side.

(2) The mesh body fixing step includes a reinforcing bar placement step of placing the reinforcing bars placed between the voids on the mesh body,
A reinforcing bar fixing process for fixing the arranged reinforcing bars to the hardened concrete side;
The method for producing a half precast plate according to (1), further comprising a step of fixing the net body to the fixed reinforcing bar.

(3) The net body fixing step includes a net body attaching step of sandwiching the net body between the vertical and horizontal stripes arranged so as to be arranged between the voids, and
A reinforcing bar arrangement step of arranging the vertical and horizontal bars to which the mesh body is attached, so that voids are located in the grid of the lattice constituted by the vertical and horizontal lines;
A half precast plate manufacturing method according to the above (1), further comprising a reinforcing bar fixing step of fixing the arranged reinforcing bars to the concrete side.

(4) The surface of the ready-mixed concrete in which the recessed portion forming mold having the shape of the recessed portion formed on the surface of the half precast plate is placed with a sheet material disposed at a position corresponding to the recessed portion forming position. A sheet material covering step to be covered with,
A half precast plate manufacturing method according to any one of (1) to (3), further comprising a suction step of sucking excess water from the ready-mixed concrete.

(5) a first reinforcing bar embedded in concrete;
A plurality of concave void housing portions formed at positions corresponding to the gaps between the reinforcing bars;
A plurality of voids housed in the void housing portion;
A mesh body overlaid on the plurality of voids, the mesh body having a mesh smaller than the size of the voids;
On the opposite side to which the void is sandwiched with respect to the first reinforcing bar, the second reinforcing bar is disposed between the voids and the mesh body is fixed,
A half precast plate comprising a fixture for fixing the second rebar to hardened concrete.

  According to the first aspect of the present invention, since the rise of the void at the time of placing the concrete is suppressed by the net body, an apparatus for pushing the void into the ready-mixed concrete becomes unnecessary. Further, since the void can be fixed only by the work of covering the net body as a structure for holding the void, the construction period can be shortened and the initial cost can be reduced.

  According to the second aspect of the present invention, the mesh body is suppressed by the reinforcing bars arranged from above the mesh body, and the reinforcing bars are supported by the mesh body at a desired height. Can be pressed against the void.

  According to invention of Claim 3, the process of supporting a net | network body can be advanced simultaneously during a ready-mixed concrete hardening process by previously pinching | interposing a net | network between a vertical line and a horizontal line, Work efficiency is improved. improves.

  According to the invention of claim 4, the sheet material is pressed against the surface of the ready-mixed concrete by the action of atmospheric pressure by covering and sucking the ready-mixed concrete with the sheet material. It is pushed in and a recessed part can be formed reliably. Conventionally, the removal of the recess forming mold needs to wait for 5 to 6 hours or more after the implantation, but the recess forming mold is removed in a short time by suction of excess water and pressurizing action by atmospheric pressure. be able to.

  According to the fifth aspect of the present invention, by arranging the voids in the void accommodating portions formed in advance in the concrete slab constituent material, it is easy to optimally position with respect to the lattice-shaped first and second reinforcing bars. Can be placed. Since the movement of the void due to buoyancy is suppressed by the net provided between the arranged void and the second reinforcing bar, the void can be held at an appropriate position. Moreover, since the void fixing structure can be easily configured by covering the net body, it is not necessary to provide a void fixing structure, and the cost can be reduced and the construction period can be shortened.

It is a fragmentary perspective view of a half precast constituent material. It is a fragmentary perspective view of the formwork which produces | generates a half precast structural material. It is a fragmentary sectional view of a sheet material. It is a front sectional view of a half precast constituent material formed in a formwork. It is a disassembled perspective view of a half precast plate. It is a partial expanded sectional front view of a half precast plate. It is a partial top view of a half precast plate. It is a perspective view which shows the arrangement | positioning state of a half precast plate. It is a partial expanded sectional front view of the half precast plate in the state where the main reinforcement is arranged. It is a partial top view of the half precast plate in the state where the main reinforcement is arranged. It is a perspective view of the half precast plate in the state where the main reinforcement is arranged. It is a cross section which shows the state by which the half precast plate was constructed by the beam.

  Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a partial perspective view of a half precast component 2, and FIG. 2 is a partial perspective view of a mold showing a state in a mold before placing ready-mixed concrete on the mold.

  Half precast constituent material 2 has lattice body s1 inside. The lattice body s1 is constituted by a main bar lower end reinforcing bar 5a arranged in parallel to each other and a distribution bar lower end reinforcing bar 4a arranged in parallel to each other orthogonally combined in a lattice shape. In the lattice body s1 configured in this way, a large number of grids are configured by the two adjacent main reinforcing bar lower reinforcing bars 5a and the two adjacent reinforcing bar lower reinforcing bars 4a. As shown in FIG. 2, the half precast component 2 includes a plurality of spacers SP arranged at predetermined intervals on the bottom of a mold 9 having a rectangular inner shape, and the lattice body is placed on the spacers SP. It is made by placing s1 and placing ready-mixed concrete. After placing the ready-mixed concrete, the surface of the ready-mixed concrete in the mold 9 is covered with the sheet material 6 on which the mold is attached, and moisture is sucked from the ready-mixed concrete by a vacuum dehydration method. Due to the suction, the surface of the ready-mixed concrete is pressed by the air pressure through the sheet material 6, the mold provided in the sheet material 6 is pressed against the surface of the ready-mixed concrete, and matches the shape of the mold after the surface of the ready-mixed concrete is dehydrated. The recessed portion thus formed is formed on the surface of the half precast component 2.

  The mold attached to the sheet material 6 is a mold (void mold 61) that matches a part of the outer shape of the void A, which will be described later, and a half-precast component 2 and a cotter having a shear transmission function of the top concrete that is post-cast. And a cotter mold 62 for forming a concave portion. The void mold 61 is arranged on the sheet material 6 so as to match the center position of the grid of the lattice body s1 when the sheet material 6 is laid out in the form of ready-mixed concrete. Accordingly, the concave portion formed by the void mold 61 is a concave portion having a concave spherical surface that matches the outer shape of the void A. When the void A is installed, the void A is not formed between the void A and the concrete. Can be held. Thus, the void accommodating part 21 is comprised by the recessed part by which the cross section was comprised by circular arc shape. Similarly, a cotter recess 22 is formed on the surface of the half precast component 2 by the cotter mold 62.

  As shown in FIG. 1, the cotter recesses 22 are arranged between the void accommodating portions 21 arranged at equal intervals in the vertical and horizontal directions, and are similarly arranged in the vertical and horizontal directions. In this embodiment, one cotter recess 22 is formed for each of the four void accommodating portions 21. The cotter recess 22 has a quadrangular cross section in order to integrate the half precast component 2 and the top concrete to ensure shear resistance. That is, since the cotter recess 22 suppresses slippage at the boundary surface, the shape of the recess is preferably rectangular rather than spherical. The void accommodating part 21 is arrange | positioned so that it may correspond to the center position of the grid of the grid | lattice body s1.

  FIG. 3 is an enlarged cross-sectional view of the sheet material 6. The sheet material 6 includes an airtight layer 643, a first water permeable layer 641, and a second water permeable layer 642. A cylindrical suction connection portion 65 is provided at a substantially central portion of the sheet material 6, and the opening 651 of the suction connection portion 65 communicates with the second water permeable layer 642. The opening 651 is connected to suction means such as a vacuum pump.

  The airtight layer 643 is made of a material that does not allow gas or liquid to pass therethrough, and the first water permeable layer 641 and the second water permeable layer 642 are layers through which liquid passes. The 1st water permeable layer 641 is arrange | positioned at the ready-mixed concrete side, and the 2nd water permeable layer 642 is located in the airtight layer 643 side. The material which comprises a 1st and 2nd water-permeable layer is a material which has a crevice which can pass water, such as a textiles and a foam. The first water permeable layer 641 has a filtration function, and has finer gaps than the second water permeable layer 642. With such a configuration, cement particles and the like are suppressed from entering the eyes of the water permeable layer during the suction treatment. By adopting such a configuration, inconveniences such as the sheet material 6 sticking to the concrete after the surplus water suction treatment and cannot be peeled off, or the sheet material 6 peels off the surface concrete when peeled off are suppressed.

  The second water permeable layer 642 is configured to have a water permeability larger than that of the first water permeable layer 641, and the water that has passed through the first water permeable layer 641 and reached the second water permeable layer 642 is along the airtight layer 643. The inside of the second water permeable layer 642 moves toward the suction connection portion 65. In this embodiment, the first water permeable layer 641 is configured by a second water permeable layer 642 having a mesh, and the first water permeable layer 641 has a finer mesh than the second water permeable layer 642. As another example, the 1st water permeable layer and the 2nd water permeable layer may be comprised by fiber assemblies, such as a woven fabric and a nonwoven fabric.

  FIG. 4 is a front cross-sectional view showing a state in which ready-mixed concrete is placed on the mold 9 and the sheet material 6 is covered. A lattice body s1 is embedded in the ready-mixed concrete, and a sheet material 6 is put on the ready-mixed concrete. In this state, the suction port of the vacuum pump is connected to the suction connection portion 65 of the sheet material 6 and the excess water is sucked. At this time, it is preferable that a gap SA is provided between the edge of the sheet material 6 and the inner edge of the mold 9. The gap SA is, for example, about 1 to 10 cm, preferably about 2 to 5 cm. The removal of the recess-forming mold from the ready-mixed concrete is facilitated by the suction of moisture from the suction connection portion 65. After the suction / pressurization treatment for about 4 to 6 minutes, the sheet material 6 is peeled off, and the mold 9 is removed, whereby the half precast component 2 is made.

  An embedded member 23 having a female screw as a locking member is provided in the mold 9 before placing the ready-mixed concrete. After the cast concrete is hardened, the opening of the female screw is located on the boundary surface side. Before the ready-mixed concrete is placed, this opening is covered with a lid to prevent the ready-mixed concrete from entering the screw and removed after the ready-mixed concrete has hardened. In this embodiment, one burying member 23 is arranged for the four void accommodating portions 21. However, the number and arrangement may be determined corresponding to the buoyancy. A base end of a connecting member described later is screwed into the embedded member 23. The embedded member 23 is formed in a columnar shape or a prismatic shape, and the lower end portion is configured to have a larger cross-sectional diameter than other portions. This is to prevent the concrete from coming out of the concrete after the concrete is hardened. For the same reason, it may be a cone shape or a pyramid shape whose cross-sectional area increases toward the lower end.

  As shown in FIG. 5, a spherical void A is disposed in each void accommodating portion 21 of the half precast component 2 configured as described above. The mesh body 8 is covered on the void A, and the distribution reinforcing bar upper end reinforcing bar 4b is disposed on the mesh body 8. The distribution reinforcing bar upper end reinforcing bars 4b are respectively arranged between the arranged voids A, and are supported on the half precast constituent material 2 by the nets 8 bridged over the voids A. A fixing tool 7 for fixing the distributing bar upper end reinforcing bar 4b, the net 8 and the void A to the half precast component 2 side is attached to the arranged reinforcing bar upper reinforcing bar 4b.

  FIG. 6 is a partially enlarged cross-sectional front view of the half precast plate 1. The fixture 7 includes an embedded member 23, a connection member 71, a receiving member 72, and a locking member 73 provided in the half precast constituent material 2. The connection member 71 is formed with male screws at both ends, and the male screw at one end is screwed into the female screw of the embedded member 23. The bolt which is the locking member 73 is screwed into the male screw at the other end. A hole through which the connection member 71 is inserted is formed in the center of the plate-shaped receiving member 72, and the locking member 73 is screwed to the other end of the connection member 71 protruding from the hole. The receiving member 72 is configured to press the distribution bar upper end reinforcing bar 4b toward the half precast component 2 by abutting the distribution bar upper reinforcing bar 4b and tightening the locking member 73.

  In this way, the fixture 7 suppresses the mesh bar 8 that supports the reinforcing bar upper reinforcing bar 4b by suppressing the reinforcing bar upper reinforcing bar 4b, and further half-precasts the plurality of voids A covered by the mesh body 8. It has the effect | action fixed to the component 2 side. Since a plurality of fixtures 7 are arranged on the half precast component 2 at a uniform interval, all the voids A can be fixed by uniformly fastening the locking members 73 of the fixtures 7. As described above, the half precast plate 1 is configured by fixing the plurality of voids A, the net body 8, and the reinforcing bar upper end reinforcing bars 4b to the half precast constituent material 2.

  FIG. 7 is a partial plan view of the half precast plate 1. The net body 8 covered from the upper side of the void A is a net-like structure constituted by a vertical line 81 and a horizontal line 82, and a pitch at which each void A is positioned at the center of the grid 83 of the grid. A combination of vertical lines 81 and horizontal lines 82 is used. The interval between the vertical line 81 and the horizontal line 82 is assumed to be smaller than the diameter of the void A. The vertical line 81 and the horizontal line 82 are brought into contact with the upper surface of the void A to press the void A. By adopting such a configuration, the void A floats through the mesh of the mesh body 8 when placing the ready-mixed concrete. You can avoid it. The mesh body 8 may be finer, but it is necessary to have a size that allows ready-mixed concrete to easily flow down to the lower side of the mesh body 8 when placing the ready-mixed concrete. For example, it is preferable that the mesh is larger than a mixture (for example, gravel grains) contained in ready-mixed concrete. Further, the constituent material of the mesh body 8 may be plastic, other resin, fiber, etc. in addition to metal.

  After transporting the half precast plate 1 configured as described above to the construction site, it is bridged on the beam. FIG. 8 is a perspective view showing a state in which the half precast plate 1 is installed between a pair of beams. The half precast plate 1 is arranged on the beam 3 in order. Between the adjacent half precast plates 1, the connecting member 41 b is bridged between the ends of the reinforcing bar upper end reinforcing bars 4 b that are abutted to each other, and the ends of the adjacent reinforcing bar upper end reinforcing bars 4 b are connected to each other. . As a connection method, for example, there is a method of binding with a binding wire.

  Next, the receiving member 72 and the locking member 73 are removed from the upper end portion of the connecting member 71, and the main reinforcing bar upper end reinforcing bar 5b is placed at the position of the gap between the voids A in the direction orthogonal to the distribution reinforcing bar upper end reinforcing bar 4b. . The intersecting portion of the main reinforcing bar upper reinforcing bar 5b and the distribution reinforcing bar upper reinforcing bar 4b is bundled, and the receiving member 72 and the locking member 73 are reattached to the upper end of the connecting member 71 and tightened as shown in FIG.

  FIG. 10 is a plan view showing a state in which the upper lattice body s2 is configured by arranging the main reinforcing bar upper end reinforcing bars 5b. The fixture 7 is arranged at the intersection of the main reinforcing bar upper reinforcing bar 5b and the distribution reinforcing bar upper reinforcing bar 4b, and the receiving member 72 is configured to suppress the main reinforcing bar upper reinforcing bar 5b and the distributing reinforcing bar upper reinforcing bar 4b at the same time. . The main reinforcing bar upper reinforcing bar 5b and the distribution reinforcing bar upper reinforcing bar 4b are placed on the mesh body 8. The mesh 8 has a mesh width Wp 1, Wp 2 that holds both sides of the void A and a mesh width Ws 1, Ws 2 between the voids A so that the distance from the void A can be changed. It becomes easy to fix to an appropriate position.

  FIG. 11 is a perspective view showing the half precast plate 1 installed on the beam 3, and FIG. 12 is a cross-sectional view showing a state of the beam 3 on which the end of the half precast plate 1 is placed. The end of the main reinforcing bar upper reinforcing bar 5b is a bent portion 51b bent downward, and the tip of the bent portion 51b extends to the inside of the beam 3. By connecting the tip of the main reinforcing bar upper reinforcing bar 5b to the inside of the beam 3 in this way, the bonding strength between the half precast plate 1 and the beam 3 can be increased.

After installing the half precast plate 1 as described above, ready-mixed concrete is placed. By placing the ready-mixed concrete, buoyancy acts on the void A, and the force to lift the void A works. However, since the void A is pressed against the half precast component 2 by the net body 8, it does not float, The ready-mixed concrete can be hardened while the distances between the voids A and the reinforcing bars constituting the lattice bodies s1 and s2 are maintained at appropriate distances. Here, the net body 8 may be sandwiched between the main reinforcing bar upper reinforcing bar 5b and the distribution reinforcing bar upper reinforcing bar 4b. In this case, when the main reinforcing bar upper reinforcing bar 5b and the distribution bar upper reinforcing bar 4b are assembled in a lattice shape, the mesh body 8 is incorporated in advance, and the lattice body s2 in which the mesh body 8 is integrated is placed on the void A. Overlapping.
As described above, the net body 8 is configured to be pressed so as not to be lifted by the upper lattice body s2 when the buoyancy of the void A is generated at the time of placing the ready-mixed concrete. Such an effect is exhibited if the net body 8 is positioned below either the reinforcing bar upper bar 4b or the main bar upper bar 5b constituting the upper lattice body s2. Moreover, as long as the net body 8 is fixed to the upper lattice body s2 by binding or the like, the mesh body 8 may be positioned on the upper side of the upper reinforcing bar 4b and the upper main reinforcing bar 5b. The shape of the void A in the configuration as described above is not limited to a spherical shape, and may be an elliptical sphere shape and a cylindrical shape whose upper and lower ends are dome (hemisphere) shapes.

2 Half-precast component 21 Void accommodating part 22 Recessed part (recessed part for cotter)
23 Embedded member 3 Beam 4a Alignment bar lower end reinforcement 4b Alignment reinforcement upper end reinforcement 5a Main reinforcement lower end reinforcement 5b Main reinforcement upper end reinforcement 6 Sheet material 61 Void mold 62 Cotter mold 7 Fixing tool 71 Connection member 72 Receiving member 73 Locking member 8 Net 81 Vertical line 82 Horizontal line A Void s1 Lower grid s2 Upper grid

Claims (5)

A placing process for placing ready-mixed concrete in the mold,
A recess forming step of forming a concave void housing portion at a position where a plurality of voids are disposed;
After the ready-mixed concrete is hardened, a void placement step of placing the voids in the void accommodating portions,
A mesh body covering step of covering a void with a mesh body having a mesh smaller than the size of the void;
A half precast plate manufacturing method comprising: a net body fixing step of fixing a covered net body to a hardened concrete side. The mesh body fixing step includes a reinforcing bar placement step of placing the reinforcing bars placed between the voids on the mesh body,
A reinforcing bar fixing process for fixing the arranged reinforcing bars to the hardened concrete side;
A half precast plate manufacturing method according to claim 1, further comprising a step of fixing the net body to the fixed reinforcing bar. The net body fixing step includes a net body attaching step of sandwiching the net body between the vertical and horizontal lines arranged so as to be arranged between the voids, respectively.
A reinforcing bar arrangement step of arranging the vertical and horizontal bars to which the mesh body is attached, so that voids are located in the grid of the lattice constituted by the vertical and horizontal lines;
A half precast plate manufacturing method according to claim 1, further comprising a reinforcing bar fixing step of fixing the arranged reinforcing bars to the concrete side. The recess forming step is a sheet in which a recess forming mold having a recess shape formed on the surface of the half precast plate covers a surface of the ready-mixed concrete placed with a sheet material arranged at a position corresponding to the recess forming position. A material coating process;
The half precast plate manufacturing method in any one of Claims 1-3 provided with the suction process which attracts | sucks excess water from ready-mixed concrete. A first rebar embedded in concrete;
A plurality of concave void housing portions formed at positions corresponding to the gaps between the reinforcing bars;
A plurality of voids housed in the void housing portion;
A mesh body overlaid on the plurality of voids, the mesh body having a mesh smaller than the size of the voids;
On the opposite side to which the void is sandwiched with respect to the first reinforcing bar, the second reinforcing bar is disposed between the voids and the mesh body is fixed,
A half precast plate comprising a fixture for fixing the second rebar to hardened concrete.

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