JP2017075468A - Water-permeable concrete mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water-permeable concrete mold that enhances concrete quality, reduces air bubbles on a concrete surface and helps improve appearance of the concrete by draining excess water in raw concrete, the concrete mold being compatible with an increase in size and a complicated form, as well as with processing work at a site as with a mold made of urethane-coated plywood, even when a water permeable layer is formed.SOLUTION: A mold 1 is capable of draining excess water and air bubbles contained in cast concrete outside of the mold 1, and combines a plate-form mold body 10 and a board-form water-permeable layer 2 placed on a concrete casting surface of the mold body 10. The mold body 10 has a plurality of drain holes 11 formed that pierce through front and rear surfaces. The board-form water-permeable layer 2 comprises a porous water-permeable board formed by a matrix fiber having a three-dimensional entanglement structure of short fibers and a binding material fixing the short fibers constituting the matrix fiber to each other.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a water permeable form for concrete in a concrete form used for making a concrete structure and having water permeability.

  As concrete formwork, wooden, steel, resin, etc. are widely used in general, but no matter which formwork is used, when concrete is poured into the formwork to make a concrete structure, concrete It has been known for a long time that bubbles (also referred to as avatars) and junkers (aggregate parts where cement and aggregates in concrete are not sufficiently mixed) are generated on the surface. In particular, the upper surface side of the concrete which has an inclined structure and is not subjected to the side pressure of the concrete is not easily filled with concrete, and air in the concrete is discharged to the upper formwork side, so bubbles and jumpers are likely to occur. This not only deteriorates the appearance, but also causes a decrease in strength due to insufficient concrete density, acceleration of neutralization, intrusion of salt, deterioration due to freezing and thawing, etc., and impairs the reliability of concrete. . Therefore, by giving water permeability to the concrete formwork, the excess water in the concrete is discharged out of the formwork, reducing the bubbles and jumpers on the concrete surface, improving the appearance of the concrete, and by densifying the concrete There is a demand for improving the quality of concrete.

  Conventionally, as a water-permeable concrete formwork, a water-permeable sheet that allows air bubbles and excess water in concrete to permeate through a plywood or steel formwork body, and a drainage sheet that discharges the permeated air bubbles and water out of the formwork (Patent Documents 1, 2, and 3). As the water-permeable sheet, for example, a polyester woven fabric (sheet made by weaving polyester fibers into a cloth shape), a perforated polyethylene sheet, or the like is used, and as a drainage sheet, for example, a polyethylene net or a nonwoven fabric is used.

Japanese Patent Laid-Open No. 7-34660 JP-A-5-16126 JP-A-1-158179

Even in the above-mentioned concrete permeable form, various performances are required as in the case of wooden, steel, resin, and the like.
Conventional water-permeable formwork for concrete is composed of a water-permeable sheet such as polyester woven cloth and a drainage sheet such as polyethylene net, and is combined with the mold body. It is wound around the back side (the outside surface that is not the concrete placement surface) and fixed with staples. However, when attaching a water-permeable sheet or a drainage sheet to the formwork body, it is difficult to fix and tighten sufficiently without making wrinkles. Especially when the formwork is large or the shape is complicated, it is difficult to fix the water-permeable sheet and drainage sheet without wrinkling, and it is almost impossible to handle large formwork and complicated shape formwork. It was the current situation. In addition, there are problems such as elongation of the water-permeable sheet and drainage sheet when concrete is poured, and appearance deterioration of the concrete surface due to wrinkles, and the need to repair the concrete surface. Unless these problems were solved, it was impossible in practice to repeatedly use the formwork. Further, the concrete formwork often requires drilling or cutting, and in the method of pulling the water-permeable sheet and drainage sheet from the back side of the concrete formwork and fixing them with staples, the water-permeable sheet is processed by drilling or cutting. As a result, there is a problem that cannot be dealt with both in the factory and on-site processing.

  The object of the present invention is that even if a water-permeable layer is formed, it can be applied to processing operations as in the case of wooden, steel, resin, etc., and excess concrete water is discharged to improve the quality of the concrete. An object of the present invention is to provide a water permeable form for concrete that contributes to improving the appearance of concrete by improving air bubbles on the surface of the concrete while improving.

The water-permeable formwork for concrete according to the present invention is
A formwork that can discharge excess water and air bubbles in the cast concrete to the outside of the formwork,
The plate-shaped formwork body and the board-shaped water permeable layer arranged on the concrete placement surface of the formwork body are combined,
The mold body is formed with a plurality of drain holes penetrating the front and back,
The board-like water-permeable layer is composed of a porous water-permeable board formed from a matrix fiber in which short fibers form a three-dimensional entangled structure and a binder that fixes the short fibers constituting the matrix fiber to each other. It is.

  With the above configuration, surplus water and bubbles in the placed concrete can be discharged from the drainage hole of the mold body to the outside of the mold frame through the board-like water permeable layer. Therefore, the excess moisture in the concrete is discharged to form dense concrete with a small water / cement ratio, improving the quality of the concrete, and the bubbles in the concrete are also discharged together with the excess water to the outside of the formwork. Smooth and precise with few bubbles.

  In addition, the water-permeable board that becomes the board-like water-permeable layer is self-supporting and has a rigidity that does not break or wrinkle. For example, the water-permeable board and the formwork body are cut into the same shape and overlapped to form a staple. A water-permeable mold can be easily obtained by combining with an adhesive or an adhesive, and the work process of combining the board-shaped water-permeable layer with the mold body is significantly simplified. Therefore, the difficulty of the manufacturing process of the water-permeable formwork that sufficiently stretches the sheet material such as the woven cloth and drainage net as in the past and staples to the formwork body, Application to complex formwork is also possible.

  At the same time, a board-like permeable layer composed of this rigid permeable board is formed in close contact with the main body of the formwork, resulting in poor appearance due to “elongation”, “wrinkle”, and “unevenness” due to concrete placement. This eliminates the need for repair and makes it possible to improve the quality of the concrete and the appearance of the concrete.

  Furthermore, with this water-permeable formwork for concrete, the board-like water-permeable layer does not open even if cutting, drilling, or other processing is performed. However, it can be performed using existing equipment and tools, and the ease of use of the water-permeable form can be dramatically improved. In addition, if the water-permeable formwork for concrete is formed to basic dimensions in advance, distribution as a water-permeable formwork material becomes possible, and it becomes possible to produce a water-permeable formwork by the same processing as a normal formwork material, It becomes possible to dramatically increase the spread of water-permeable formwork.

  As mentioned above, according to the water-permeable formwork for concrete according to the present invention, it is possible to simplify the manufacturing process, support for large formwork and shape complex formwork, support for on-site processing work, etc. Furthermore, it is possible to improve the appearance of the concrete by discharging excess water from the ready-mixed concrete to improve the quality of the concrete and reducing bubbles on the concrete surface.

It is sectional drawing which shows the water-permeable form for concrete of this invention. It is a top view which shows the formwork main body in which the drainage hole was formed. It is a side view which shows the apparatus which measures water permeability time in order to confirm the water permeability of a water-permeable form. It is a perspective view which shows the mold form for the concrete for forming a concrete structure. It is a figure which shows the formwork for large-sized concrete for forming the large-sized concrete structure which has an inclined surface, The figure (a) is a side view, The figure (b) is the front from an inclined surface side. FIG. It is a figure which shows the water-permeable formwork for concrete used for the formwork for large-sized concrete, The figure (a) is a top view of the water-permeable formwork arrange | positioned to the vertical surface side, The figure (b) is an inclined surface. It is a top view of the water-permeable type | mold form arrange | positioned on the side.

Embodiment of the water-permeable formwork 1 for concrete of this invention is described below.
As shown in FIG. 1, the water-permeable formwork 1 for concrete according to the embodiment includes a plate-like formwork body 10 having a plurality of drain holes 11 communicating with the front and back sides, and a concrete casting surface side of the formwork body 10. The surplus water and air bubbles in the placed concrete ooze out through the board-like water permeable layer 2 and drain holes 11 of the mold body 10. Is discharged out of the formwork.

The mold body 10 is made of wood, steel, resin, or a composite material thereof. As the mold body 10, one used for the mold itself may be used. For example, a urethane-coated plywood having a urethane coating applied to its surface can be used. The mold body 10 is provided with a plurality of drain holes 11. Excess water and bubbles in the concrete that have oozed out of the board-like permeable layer 2 through these drain holes 11 are discharged out of the mold frame. The surplus water in the concrete oozes out from the entire surface of the board-shaped water permeable layer 2 and is supplied to the entire surface of the mold body 10, so that the drain holes 11 of the mold body 10 are finely and densely provided, It is not necessary to increase the drainage capacity of the individual drainage holes 11 and to prevent the mold body 10 from being clogged with cement particles and the strength of the mold body 10 is not impaired. For example, it is preferable that the drainage holes 11 provided in the mold body 10 have a diameter of 3 mm to 20 mm and are formed about 10 to 125 per 1 m ² . That is, if the diameter is 3 mm to 20 mm and the number is less than 10 per 1 m ² , it is difficult to sufficiently drain the surplus water in the concrete that has passed through the board-like permeable layer 2, and the drain hole 11 may be blocked by repeated use. is there. On the other hand, if there are more than 125 drain holes 11 having a diameter of 3 mm to 20 mm per 1 m ² , the strength of the mold body 10 may not be ensured. In addition, the arrangement | positioning form of the drain hole 11 does not have a restriction | limiting in particular, such as a square arrangement | positioning and a plover arrangement | positioning.

  As the board-like water permeable layer 2, a continuous porous water permeable board having a large number of pores communicating with the front and back is used. The board-like water permeable layer 2 has excessive water permeability when the amount of porous pores (void amount) is too large, and moisture in the concrete is rapidly removed from the formwork during concrete placement or compaction (vibration treatment). As a result, the workability (workability) of the concrete is reduced and the concrete cannot be filled enough into the formwork, or the concrete is stiff on the surface of the permeable formwork 1 and the formwork of excess water and bubbles 1 The discharge to the outside is hindered, and the concrete is not densified, leading to an increase in bubbles on the concrete surface. In addition, if the porous pore diameter is too large, cement particles can easily enter and cause clogging, resulting in insufficient discharge of excess water in the concrete for repeated use. The unevenness increases and the appearance of the concrete surface becomes worse. On the other hand, if the amount of porous pores is too small, the water permeability will be reduced, and the excess water in the concrete will not be sufficiently leached, resulting in the improvement of the quality of concrete and the discharge of water in the concrete out of the formwork. Removal of bubbles on the surface of the formwork and improvement in appearance cannot be expected. Accordingly, the board-like permeable layer 2 as the concrete permeable form 1 for concrete is less likely to be clogged with concrete, has a continuous porosity with good water permeability, and has a flat surface with few irregularities. It is important to have excellent demoldability. According to the measurement method shown in the “water permeability performance of the water permeable mold” in the examples described later, the water permeability time is preferably 40 seconds to 231 seconds as the water permeability performance of the water permeable mold 1 for concrete. Further, it is more preferably 51 seconds to 220 seconds.

Below, the detail of the board-shaped water-permeable layer 2 is demonstrated.
The board-like water permeable layer 2 is constituted by a porous water permeable board in which matrix fibers and a binder are mixed. The board-like water permeable layer 2 is required to have moderate water permeability, and cement particles having an average of about 10 μm and a minimum of about 0.1 μm do not block the voids of the board-like water permeable layer 2. In order to solve this proposition, it is preferable to disperse short fibers randomly as matrix fibers from the viewpoint of freedom of fiber selection, random dispersibility, controllability of fiber orientation, and the like.

  The matrix fiber is not particularly limited as long as the fiber can be entangled three-dimensionally to form a porous board, and various kinds of generally distributed fibers can be used. Specifically, natural fibers such as hemp, kenaf and cotton, chemical fibers such as polyester, acrylic, polyolefin, nylon, rayon and urethane, inorganic fibers such as glass and carbon, and recycled fibers made from these fibers are recycled. These can be used alone or in combination of two or more.

  As for the length of the fibers constituting the matrix fiber (strictly speaking, aspect ratio), if the fibers are long, the effect of eliminating the volume of the fibers becomes effective when forming the board, and the board-like permeable layer 2 having a low fiber density is formed. Is getting bigger. As for the fiber thickness, if the fiber aggregate structure and the properties of the fiber itself are constant, the pore diameter of the board-like water permeable layer 2 increases as the fiber thickness increases, increasing the risk of intrusion of cement particles. On the contrary, when the fiber thickness is reduced, the pore diameter of the board-like water permeable layer 2 is reduced and the water permeability is lowered. From this, in order to obtain the board-shaped water permeable layer 2 suitable for the water permeable form 1 for concrete, the fiber length of the matrix fiber is 5 mm to 60 mm from the viewpoint of opening, dispersing, fixing, and holding the matrix fiber. The fiber thickness of the matrix fibers is preferably about 5 μm (about 0.5 dtex) to about 50 μm (about 25 dtex), but is not limited thereto. The fiber thickness is often expressed by the fineness (dtex = weight g at a length of 10 km) for chemical fibers and by the diameter for other fibers. Furthermore, this matrix fiber can adjust water permeability, intensity | strength, rigidity, etc. by mixing the short fiber from which a material, thickness, and length differ.

  The binder is not particularly limited as long as the matrix fiber is fixed and the rigid board-like water permeable layer 2 is formed, but a thermoplastic resin fiber or powder lower than the melting point or softening point of the matrix fiber is used. Is convenient. This is because by lowering the melting point than the matrix fiber used as a three-dimensional entangled structure in order to achieve water permeability, only the portion that comes into contact with the binder serving as the binder is fused to ensure water permeability. is there.

  Furthermore, in order to maintain the strength to withstand concrete placement and demolding while ensuring uniform water permeability, and to suppress the fluffing of matrix fibers, the form of the binder is fibrous, chip-like, powdery, etc. Can be used, but it is preferable to use matrix heat-bonded fibers that are easily dispersible in a three-dimensional manner. Further, it is desirable that the heat-fusible fiber used as the binder is stably fixed by increasing the number of intersections with the matrix fiber, and for that purpose, it is preferable that the fiber is not more than the fineness or length of the matrix fiber. As this heat-sealable fiber, for example, short fibers having a heat-seal function, such as polyester, polyethylene, polypropylene, and polyamide, are preferably used. Among them, it is preferable to use a heat-sealable fiber combined with a core-sheath type. The core-sheath type heat-fusible fiber is preferably a combination having a high melting point polymer in the core part and a low melting point / low softening point polymer in the sheath part, and the sheath part is below the melting point of the core part. Dissolves and functions as a binder. As a result, while maintaining the three-dimensional entanglement structure formed by the matrix fibers, the intersections of the binder with the heat fusion fibers are thermally fused, and the matrix fibers are strongly fixed and stable board-like water permeable layer. 2 is formed.

  For example, the heat-fusible fiber as the binder has a melting point higher than that of the matrix fiber from the viewpoint of the water permeability of the board-like water permeable layer 2 as the water permeable form 1 for concrete, the strength and rigidity of the board, and the fixation of the matrix fiber. It is preferable to use a heat-melting fiber having a low melting point of about 100 ° C. Specifically, as a combination of a matrix fiber and a heat-sealing fiber (binding material), the matrix fiber is a polyester fiber (melting point 260 ° C.), a nylon fiber (melting point 210 ° C.), an acrylic fiber (softening point 220 ° C.), rayon. One or more combinations of fiber (no melting point), hemp (no melting point), kenaf (no melting point), cotton (no melting point), glass fiber (softening point 750 ° C.), carbon fiber (no melting point), etc. In this case, the heat-fusible fiber (binding material) is a core-sheath type polyester fiber (melting point of sheath polyester is 110 to 150 ° C.), core-sheath type polyethylene fiber (melting point of sheath polyethylene is 130 ° C.), polypropylene fiber (melting point) 140-170 degreeC) etc. can be selected.

Furthermore, in order to obtain appropriate water permeability and strength, the board-like water permeable layer 2 of the water permeable mold 1 for concrete has a bulk density of the board-like water permeable layer 2 of 0.3 g / cm ^{3 to} 0.9 g / cm ^3. The weight ratio (wt%) of the matrix fiber and the binder is preferably 80:20 to 50:50, and the thickness of the board-like water permeable layer 2 is preferably 1 mm to 10 mm. In this case, good water permeability and concrete appearance Is obtained.

  That is, when the matrix fiber exceeds 80% by weight, the adhesion between the fibers becomes insufficient and the water permeability becomes excessive, the air bubbles on the concrete surface increase, the fluffing of the board-like water permeable layer 2 occurs, and the concrete fiber There is a risk of fiber biting. Further, if the binder exceeds 50% by weight, the water permeability is remarkably reduced, excess water in the concrete is not discharged, the concrete becomes insufficiently densified, and the air bubbles on the concrete surface may increase. .

Even if the ratio between the matrix fiber and the binder is constant, if the bulk density of the board-like water permeable layer 2 is less than 0.3 g / cm ³ , the water permeability becomes excessive, and concrete placement or compaction (vibration treatment) ), The moisture in the concrete is rapidly discharged out of the mold and may inhibit the densification of the concrete. On the other hand, if the bulk density of the board-like permeable layer 2 exceeds 0.9 g / cm ³ , the concrete There is a risk that the excess water inside will be insufficiently discharged, resulting in an increase in bubbles and irregularities on the concrete surface and a deterioration in the appearance of the concrete surface.

  Further, the thickness of the board-like water permeable layer 2 is preferably 1 to 10 mm from the viewpoint of water permeability, strength to withstand concrete placement and mold washing, and handling properties. If the thickness is less than 1 mm, the concrete is repeatedly cast. The board-like water permeable layer 2 may be damaged, and if the thickness exceeds 10 mm, the water permeability may deteriorate or the handling property may decrease due to an increase in the formwork weight.

Next, the manufacturing method of the water-permeable board which comprises the board-shaped water-permeable layer 2 is demonstrated.
A water-permeable board can be produced by a method in which the matrix fibers described above are used alone or in combination, and a resin is mixed or sprayed thereon as a binder, followed by heat pressing. Moreover, a water permeable board can be manufactured using the airlaid method which is one of the nonwoven fabric manufacturing methods in which a matrix fiber and the heat-fusion fiber which is a binder are uniformly opened and mixed to be entangled three-dimensionally. The method for producing the water-permeable board may be produced by an appropriate method according to the combination of the matrix fiber and the binder, and is not particularly limited. However, the air laid method is most convenient. The airlaid method is, for example, a method in which short fibers are blown onto a net together with an air flow from a blowing device at the top of a porous net conveyor and sucked by a suction device installed at the bottom of the net conveyor to form a fiber web.

  And as a method of heating and compressing the fiber web, there is a method using a press roller or a press machine. The press roller can be continuously pressed and has excellent productivity, and the productivity of the press machine is lower than that of the press roller. There are advantages such as laminating and uniform melting of the binder by long-time pressing. In the water-permeable board used for the water-permeable formwork 1 for concrete, the method of pressing the fiber web is not limited, but in order to increase the board thickness to 1 to 10 mm, the fiber web is laminated, A hot press using a hot press machine that can take temperature and pressure with sufficient hot press time is desirable.

  In addition, by laminating the fiber web, it is possible to appropriately set the water permeability and strength in the thickness direction by changing the lamination form such as uniform water permeability of the board-like water permeable layer 2 and blending the fiber web material and bulk density. become. For example, the board-like water permeable layer 2 on the concrete placing surface side is formed by increasing the bulk density, reducing the fiber diameter of the fiber material, or shortening the fiber length of the fiber material in order to prevent intrusion of cement particles. The pore diameter is small and convenient. It is an advantage of the hot press that the hole diameter and the bulk density in the thickness direction of the board-like water permeable layer 2 can be suitably set as described above.

  Unlike the woven fabric, the board-shaped water permeable layer 2 manufactured under such conditions can be self-supporting when placed vertically with the lower part supported, and can be easily applied to the mold body 10 with staples or resin without tension. In addition, it is possible to cope with large formwork and complicated formwork. At the same time, cutting and drilling at factories and sites are possible with conventional equipment. In addition, the board-like permeable layer 2 has high retention and shape retention by matrix fibers and is excellent in rigidity and strength, so that there is no generation of wrinkles when placing concrete, and the permeable mold 1 or It can be used for repeated placement of concrete and high-pressure washing of formwork.

  In addition, this invention is not limited to the said embodiment, A various change is possible within the range of the summary of this invention.

Hereinafter, the water-permeable mold according to the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.
(Examples 1 to 22)
(A) Fabrication of formwork Polyester short fibers as matrix fibers and core-sheath type polyester fibers as heat-bonding fibers (binding material) are blended at a predetermined ratio, and the basis weight of the basis weight is targeted by the airlaid method. A fiber web having a three-dimensional entangled structure of 1/2 was formed, and two of these fiber webs were laminated, and the heat press temperature (mold surface temperature) was 150 to 230 ° C., the press pressure was 0.49 MPa, the heat press A water permeable board was manufactured by performing a heat press under the condition of 3 minutes. Then, as shown in FIG. 2, this water-permeable board has a 5 mm diameter drainage hole 11 as shown in FIG. 2 (vertical 75 mm length, horizontal 75 mm position (L1, L1), hole pitch 150 mm (L2)). A water-permeable mold 1 in which a board-like water-permeable layer 2 was formed by superimposing on one side of a urethane-coated plywood (300 mm long, 300 mm wide, 12 mm thick) formed on the surface and fixed with staples was produced. Table 1 shows the configuration of the board-like water permeable layer 2.

The characteristics of the matrix fiber and the heat-sealing fiber (binding material) used for the board-like water permeable layer 2 are as follows.
<Matrix fiber>
Polyester short fiber: melting point 260 ° C., fineness 6.6 dtex, fiber length 51 mm
<Binder>
Core-sheath type polyester fiber: The core part is polyester with a melting point of 260 ° C., the sheath part is polyester with a melting point of 110 ° C., the fineness is 4.9 dtex, and the fiber length is 51 mm.
(Comparative Example 1)
In the mold 100 of Comparative Example 1, a urethane-coated plywood (length 300 mm, width 300 mm, thickness 12 mm) was used as the mold 100 as it was without providing the drain holes 11.

(B) Water-permeable performance of water-permeable mold 1 As shown in FIG. 3, the resin-made transparent pipe (outer diameter 43 mm, inner diameter 38 mm, length 300 mm) with respect to the water-permeable mold 1 of Examples 1-22. Is placed in the center of each drainage hole 11 position of the water-permeable mold 1 placed flat with the surface side of the board-like water-permeable layer 2 as the upper surface, and a gap between the transparent pipe and the surface of the water-permeable mold 1 is sealed with a sealing material ( Sealed with clay), filled the transparent pipe with water, measured the water passage time until the water level became 180 mm to 92 mm, and calculated the average value of the water passage time at the four drainage hole 11 positions. Was defined as the water permeability of the water-permeable mold 1. That is, the water permeation performance is a water permeation time required for 100 mL of water to permeate under a water pressure of 180 mmH ₂ O to 92 mmH ₂ O. The water permeation time is shown in Table 1.

As a precaution, the water permeation performance of the water permeable form 1 in which the water permeable board was adhesively stopped was confirmed. That is, the examples except that the room temperature curable urethane adhesive was brush-coated on the urethane coated plywood to be the mold body 10 so as not to block the drain holes 11, and the urethane coated plywood and the water permeable board were bonded and combined. A water-permeable mold 1 having the same configuration as that of No. 3 was produced, and the water permeability time was measured. As a result, the water permeability time of the adhesive-carrying mold 1 is 74 seconds, which is not significantly different from the water permeability time 69 seconds (see Table 1) of the stapled water-permeable mold 1 of Example 3. It was confirmed.
In addition, the formwork 100 of the comparative example 1 does not have the drainage hole 11, and does not have water permeability.

(C) State of the concrete surface As shown in FIG. 4, the water-permeable mold 1 of Examples 1 to 22 is disposed on one side of the box shape with the top opened, and the other three side surfaces and the bottom surface are thick. Place a 12mm thick urethane coated plywood formwork 100 (without drainage hole 11) and place the concrete into a concrete shape with a width (W) of 300 mm, a depth (D) of 150 mm, and a height (H) of 300 mm. The frame was assembled. In addition, for comparison, a concrete casting form in which the urethane-coated plywood form 100 of Comparative Example 1 was arranged instead of the water-permeable form 1 of Examples 1 to 22 was similarly assembled.

Then, in each of the concrete casting molds of Examples 1 to 22 and Comparative Example 1 in which the mold assembly was completed, a mold release agent (mineral oil type: Toyokuni Oil Co., Ltd. Xebecould 8) was applied to the casting surface with a brush. After that, ready-mixed concrete is poured from the upper opening in two steps of 150 mm in the height direction, and is vibrated with an electric vibrator, filled, defoamed, cast concrete, and demolded the next day. The surface was observed.
The concrete placed above has a composition of cement 318 kg / m3, sand 740 kg / m3, gravel (Gmax, 20 mm) 1072 kg / m3, water 191 kg / m3, W / C = 60%, and slump 15 cm was used. .

The above examples and comparative examples were evaluated by the following methods.
(1) As for the number of bubbles on the concrete surface in Examples and Comparative Examples, the number of bubbles or recesses having a diameter of 1.0 mmφ or more was measured.
(2) The appearance of the concrete surfaces in Examples and Comparative Examples was evaluated according to the following criteria.
A: The number of bubbles is 20 or less, and the concrete surface has no irregularities and is in a very smooth surface state.
A: The number of bubbles is 21 or more and 30 or less, and the concrete surface is smooth and has no irregularities.
Δ: The number of bubbles is 31 or more and 55 or less, and the concrete surface is smooth but somewhat uneven.
X: The number of bubbles is 56 or more, and clear irregularities are observed in places on the concrete surface.
(3) The rigidity of the board-like permeable layer 2 in the permeable mold 1 of the embodiment is vertically placed with a permeable board (before being combined with the mold body 10) cut to 300 mm in length and 300 mm in width supported vertically. We evaluated by whether we can be independent.
(4) It was confirmed that the water-permeable mold 1 of the example was wrinkled, deformed, broken or the like in the board-shaped water-permeable layer 2 when the concrete casting mold was removed.
The above results are shown in Table 1.

From Table 1, in the state of the concrete surface of the structure, in Comparative Example 1, the number of bubbles was 57, the surface irregularities were large, and the appearance of the concrete surface was poor.
On the other hand, in Examples 1 to 22, the number of bubbles on the concrete surface is 8 to 55, and in all Examples, the number of bubbles is smaller than that of Comparative Example 1, and the surface irregularities are also small and smooth. As a result, a good concrete surface appearance was obtained. Therefore, according to the water-permeable form 1 of an Example, it turned out that the concrete surface becomes dense and the concrete quality is improved by reducing the number of bubbles.

  In particular, in Examples 2, 3, 4, 5, 8, 9, 10, 13, 14, 15, 20, and 21, the number of bubbles on the concrete surface is 30 or less, and the number of bubbles in Comparative Example 1 is 57. 47% or more could be reduced. From this, in order to reduce the number of bubbles to about 30 or less, the water permeability of the water-permeable mold 1 is preferably a water permeability time in the range of 40 seconds to 231 seconds, and more preferably. Is in the range of 51 seconds to 220 seconds (Examples 2, 3, 4, 8, 9, 13, 14, 21). In this case, 71% to 86% of 57 bubbles in Comparative Example 1 is reduced. It was confirmed that a good concrete appearance was obtained, and excess water in the concrete was discharged together with the air in the concrete, forming a dense concrete surface with a small water-cement ratio. . That is, when the water permeation time of the water permeable mold 1 is approximately 32 seconds or less (Examples 11, 12, 17, 18, 19), the drainage from the placed concrete becomes excessive and the fluidity of the concrete is hindered. There is a risk that stiffness will occur, or early release of the concrete will occur on the surface of the water-permeable mold 1 and there will be a phenomenon that bubbles on the concrete surface will increase, and the water permeability will be approximately 243 seconds or more (Example) 1, 6, 7, 16, and 22), the water permeability is lowered and sufficient drainage from the drain hole 11 is not possible, the bubbles on the concrete surface increase, the appearance is deteriorated, and the normal plywood formwork is formed. There is a risk that it will not be different from the concrete surface due to.

In addition, the board-shaped water permeable layer 2 has good water permeability and concrete appearance when the following conditions are used as a rough guide.
(A) Mixing ratio of matrix fiber and heat-sealing fiber (binding material) From Examples 1 to 5 in which only the mixing ratio of matrix fiber and heat-sealing fiber was changed, the mixing ratio of matrix fiber and heat-sealing fiber The ratio is preferably a matrix fiber: heat-bonded fiber = 80: 20 to 50:50 weight ratio (wt%) (Examples 2 to 5). Among them, the case of the weight ratio (wt%) 60:40 between the matrix fiber and the heat-sealing fiber of Example 3 was optimal. In Example 1, the water permeability of the water-permeable mold 1 was as long as 1035 seconds, and the drainage from the upper one of the four drain holes 11 of the concrete casting mold was reduced. Therefore, it is preferable that the weight ratio of the heat-sealing fibers constituting the board-shaped water permeable layer 2 is not more than 60 wt% (Example 1).

(B) Weight per unit area, bulk density From Examples 6 to 11, when the thickness of the water-permeable board is 3 mm and the weight ratio of the matrix fiber and the heat-fusion fiber is constant (60:40), the board-like water-permeable layer 2 amount of weight per unit area ^{1000g / m 2 ~2500g / m 2} , a bulk density in the range of 0.33g ^/ cm ³ ~0.83g ^/ cm 3 is preferred (examples 8-10). In Examples 6 and 7 having a large basis weight and bulk density, the water permeable time of the water permeable mold 1 is as large as 2712 seconds and 1201 seconds, respectively, and among the four drain holes 11 of the concrete casting mold. In Example 6, the drainage performance from the two upper locations was reduced, and in Example 7, the drainage performance from all four locations was reduced. Therefore, the basis weight of the board-like permeable layer 2 exceeded 3000 g / m ² , and the bulk density was 1 It is preferable not to exceed 0.000 g / cm ³ (Example 7).

(C) Thickness From Examples 12 to 16, the weight ratio between the matrix fiber and the heat-sealing fiber is constant (60:40), and the bulk density of the board-shaped water permeable layer 2 is constant (0.50 g / cm ³ ). In this case, the thickness of the board-like water permeable layer 2 is preferably in the range of 1 to 10 mm (Examples 13 to 15). In addition, when the thickness of the board-shaped water permeable layer 2 becomes thinner than 0.5 mm (Example 12), the water permeability becomes excessive and deformation occurs in the board-shaped water permeable layer 2 when the concrete casting form is removed. In addition, if the thickness of the board-shaped water permeable layer 2 is greater than 15 mm (Example 16), the water permeability is lowered and the weight of the water permeable board is increased, and the handling property may be impaired.

(D) Heat press temperature From Examples 17-22, the board-like water-permeable layer 2 is comprised with a polyester short fiber (melting point 260 degreeC) and a core sheath type polyester fiber (melting point 260 degreeC of a core part, melting | fusing point 110 degreeC of a sheath part). When it does, the range whose heating press temperature of a fiber web is 200-220 degreeC is preferable (Examples 20 and 21). That is, if the heating press temperature is in the range of 200 to 220 ° C., an appropriate void is formed by heat fusion of the core-sheath polyester heat-bonded fiber (binding material) without melting the polyester short fiber (matrix fiber). It acts to form and ensures good water permeability. When the heating temperature of Examples 17 to 19 is low, heat fusion by the binder does not sufficiently act, and water permeability becomes excessive and bubbles tend to increase. Of course, the heating press temperature and the heating time may be adjusted according to the melting point and softening point of the heat-sealing fiber used as the binder, and are not particularly limited.

Moreover, as the rigidity of the board-shaped water permeable layer 2, the water permeable board (300 mm long, 300 mm wide, 0.5 to 15 mm thick) before being formed on the mold body 10 is self-supporting by fixing the lower part in all the examples. It had the rigidity to do. In addition, the board-like water permeable layer 2 of the water-permeable mold 1 that was removed from the mold had no wrinkles, deformation, or breakage in any of the examples except for a part of the example 12 modified.
For example, in the case where a sheet of woven fabric, nonwoven fabric, fiber film, etc. that cannot stand independently is used as the water permeable layer of the water permeable formwork, the fiber of the sheet is opened by cutting or punching. Can be cut with scissors, rolled into the main body of the formwork and fixed with staples on the back side of the concrete placement surface, and the water-permeable formwork cannot be processed in the field. However, a large formwork has a problem that a sheet such as a woven fabric is bent and wrinkled to require repair of the concrete surface.

  On the other hand, since the water-permeable board of the embodiment has a rigidity capable of being self-supporting, there is no need to be strained when compounding with the mold body 10, and the mold body 10 can be easily applied to a large formwork or a complicated shape. In addition, in the permeable mold 1 combined with the permeable board alone and the mold body 10, processing such as drilling and cutting can be easily performed with existing equipment without fiber opening. It is possible and can be processed at a factory or on site, and has a great feature not found in sheet materials such as woven fabrics. Furthermore, since the board-like water-permeable layer 2 of the water-permeable mold 1 that has been demolded is in a beautiful state without any damage such as cracks, it can be used repeatedly and is advantageous over a sheet.

(Examples 23 to 26)
In Examples 23 to 26, the board-shaped water permeable layer 2 was manufactured using various matrix fibers and heat-bonding fibers (binding materials). That is, the board-like water permeable layer 2 was formed in the same manner as in Example 3 except that the matrix fibers and heat-sealing fibers described below were changed to the combinations and blending ratios shown in Table 2 and the heating press temperature. The water-permeable mold 1 was manufactured, and water permeability and concrete appearance were evaluated. The results are shown in Table 2.

<Matrix fiber>
(1) Hemp: no melting point, thickness 13-31 μm, length 20-30 mm
(2) Kenaf: No melting point, thickness 16-22μm, length 45mm
(3) Sisal: no melting point, thickness 10-20 μm, length 3-10 mm
(4) Polyester fiber: melting point 260 ° C., fineness 6.6 dtex, fiber length 51 mm
<Binder>
(5) Core-sheath type PET fiber: The core part is polyester and has a melting point of 260 ° C., the sheath part is polyester and the melting point is 110 ° C., the fineness is 4.9 dtex, and the fiber length is 51 mm.
(6) Core-sheath type PE fiber: The core part is polyester with a melting point of 260 ° C., the sheath part is polyethylene with a melting point of 130 ° C., a fineness of 2.2 dtex, and a fiber length of 51 mm.
(7) PP: Polypropylene fiber, melting point 165 ° C., fineness 6.7 dtex, fiber length 25 mm

  From Table 2, in Examples 23 to 26, the number of bubbles on the concrete surface is 17 to 31 and can be reduced by 46% to 70% of 57 in Comparative Example 1, and the concrete surface is also reduced. Smooth and good concrete appearance was obtained. Regarding water permeability, in Examples 23 to 26, the water permeability of the water permeable mold 1 is 43 seconds to 147 seconds, which is within the preferable water permeability time range obtained in Examples 1 to 22, and is good. It was permeable. In Examples 23 to 26, drainage was confirmed from all four drain holes 11 of the water-permeable mold 1 during concrete placement, and the water-permeable mold 1 functioned well.

  From the above results, polyester fibers were used as matrix fibers in Examples 1 to 22, but natural fibers such as hemp, kenaf, and sisal were used in Examples 23 to 25. Therefore, even when natural fibers are used as the matrix fibers, good water permeability can be obtained as in the case of using polyester short fibers as in Examples 1 to 22, and air bubbles on the concrete surface in placing concrete can be obtained. It was confirmed that it contributed to the densification of the concrete surface by decreasing the amount.

  Moreover, in Examples 1-22, the core-sheath-type polyester fiber was used as the heat-fusible fiber (binding material), but in Examples 23 and 26, the core-sheath-type polyethylene fiber was used. Then, a single polypropylene fiber was used instead of the core-sheath type. Therefore, even when a core-sheath type polyethylene fiber or a single polypropylene fiber is used for the heat-sealing fiber, good water permeability is obtained as in the case of using the core-sheath type polyester fiber as in Examples 1 to 22. It was confirmed that the air bubbles on the concrete surface during concrete placement also decreased and contributed to the densification of the concrete surface.

  In Examples 23 to 26, the heat-fusible fiber used had a melting point lower than the melting point of the matrix fiber by about 100 ° C. or more (in the case of the core-sheath type, the melting point of the sheath portion). In this case, it is possible to adjust the heating press temperature at which the fiber web is heated and pressed by the melting point of the heat-sealing fiber without considering the melting of the matrix fiber, and the temperature management is easy and the water-permeable board can be easily manufactured. In addition, it was confirmed that the manufactured water-permeable mold 1 can be sufficiently used as the water-permeable mold 1 having good water permeability.

  In addition, the water-permeable boards of Examples 23 to 26 also have a self-supporting rigidity and can be easily combined with the mold body 10 in a large formwork or a complicated form, as in Examples 1 to 22. It can also be processed in the factory or on-site without any fiber opening even when drilling or cutting, and the board-like water permeable layer 2 after demolding is not damaged and is used repeatedly. It was possible.

(Examples 27 to 31)
In Examples 27 to 31, the board-like water permeable layer 2 was manufactured by mixing the fibers having different fineness and fiber length with the matrix fiber and the heat-sealing fiber (binding material). That is, the water-permeable form which formed the board-like water-permeable layer 2 similarly to the case of Example 3 except having made the matrix fiber and the heat-fusion fiber mentioned below into the combination and blending ratio shown in Table 3. 1 was manufactured and water permeability and concrete appearance were evaluated. The results are shown in Table 3.

<Matrix fiber>
(1) Polyester short fiber: Fineness 0.55dtex, fiber length 10mm
(2) Polyester short fiber: Fineness 6.6 dtex, fiber length 25 mm
(3) Polyester short fiber: Fineness 20dtex, fiber length 25mm
<Binder>
(4) Core-sheath type polyester fiber: The core part is polyester and has a melting point of 260 ° C, the sheath part is polyester and the melting point is 110 ° C, the fineness is 1.4 dtex, and the fiber length is 5 mm.
(5) Core-sheath type polyester fiber: The core part is polyester and has a melting point of 260 ° C. The sheath part is polyester and the melting point is 110 ° C. and the melting point is 110 ° C., the fineness is 2.2 dtex, and the length is 25 mm.
(6) Core-sheath type polyester fiber: The core part is polyester and has a melting point of 260 ° C. The sheath part is polyester and the melting point is 110 ° C. and the melting point is 110 ° C., the fineness is 4.9 dtex, and the length is 25 mm.

  From Table 3, in Examples 27-31, the number of bubbles on the concrete surface is 7-21, which can reduce 63% or more of 57 in Comparative Example 1, and the concrete surface is also smooth. And a good concrete appearance was obtained. Moreover, about Examples 27-31, in Examples 27-31, the water-permeable time of the water-permeable form 1 is 65 seconds-201 seconds, and is in the range of the preferable water-permeable time obtained in Examples 1-22, and is favorable. It was permeable. In Examples 27 to 31, drainage was confirmed from all four drain holes 11 of the water-permeable mold 1 during concrete placement, and the water-permeable mold 1 functioned well.

  Based on the above results and the results of Examples 1 to 22, polyester short fibers as matrix fibers have good water permeability and concrete appearance when the fineness is within the range of 0.55 to 20 dtex and the fiber length is within the range of 10 mm to 51 mm. It was confirmed that Further, it was confirmed that the core-sheath type polyester fiber as the heat-sealing fiber has good water permeability and concrete appearance when the fineness is in the range of 1.4 dtex to 4.9 dtex and the fiber length is 5 mm to 51 mm. .

  Further, from Examples 27 and 29, when two kinds of polyester short fibers having different fineness and fiber length are mixed as the matrix fiber, the matrix fiber having a fineness of 6.6 dtex and a fiber length of 25 mm is compared with a fiber having a small fineness and a short fiber length. However, better water permeability and appearance of the concrete were obtained by using the one with larger fineness and longer fiber length. In particular, in Example 29, the number of bubbles on the concrete surface was 7, and the concrete appearance was better than the number of bubbles of 8 when one kind of polyester short fiber shown in Example 3 was used as the matrix fiber. .

  Further, from Example 27, polyester fibers having a small fineness and a short fiber length were mixed as matrix fibers (polyester short fibers having a fineness of 6.6 dtex and a fiber length of 25 mm were mixed with polyester short fibers having a fineness of 0.55 dtex and a fiber length of 10 mm) ) Then, when concrete was cast and the formwork was removed, fiber fluff was slightly observed in the board-like water permeable layer 2, so that the matrix fiber had a fineness of less than 0.55 dtex or a fiber length of 10 mm. It turns out that it is better not to include many shorter ones. In addition, when both sides of the water-permeable board were held with both hands and the degree of bending was observed, the amount of bending was reduced and the rigidity of the board-like water-permeable layer 2 was improved by mixing matrix fibers having a large fineness as in Example 29. Was recognized.

  In addition, from Examples 3 and 28, when the fineness of the heat-bonding fiber is 4.9 dtex, there is no significant difference between the fiber length of 25 mm and 51 mm. On the other hand, from Examples 30 and 31, the heat-bonding fiber having a small fineness is mixed. As a result, there was no problem in practical use, but a tendency for water permeability to slightly decrease was recognized.

  In Example 27 (fineness of heat-bonded fiber: 4.9 dtex), the fuzz of fibers was slightly observed in the board-like water permeable layer 2 at the time of demolding. Although it is more convenient to include small ones, there is no significant difference and the selection may be made from the viewpoint of fiber opening and dispersion.

  In addition, the permeable boards of Examples 27 to 31 also have a self-standing rigidity and can be easily combined with the mold body 10 in a large formwork or a complicated form, as in Examples 1 to 23. It can also be processed in the factory or on-site without any fiber opening even when drilling or cutting, and the board-like water permeable layer 2 after demolding is not damaged and is used repeatedly. It was possible.

(Example 32)
In Example 32, the board-shaped water permeable layer 2 was manufactured using polyethylene resin powder as a binder. That is, 70% by mass of polyester short fibers (melting point 260 ° C., fineness 4.9 dtex, fiber length 51 mm) as matrix fibers, and 30% by mass of polyethylene resin powder (melting point 120 ° C., average particle size 10 μm) as binders. After mixing and opening, using a mat forming machine, a mat having a thickness of 20 mm and a basis weight of 750 g / m ² is manufactured, and two mats are laminated and heated and pressed at a heating press temperature of 220 ° C. to obtain a basis weight of 1500 g / Except for producing a water-permeable board with m ² , bulk density of 0.5 g / cm ³ and thickness of 3 mm, the water-permeable form 1 was produced in the same manner as in Examples 1 to 22, and the water permeability and concrete appearance were evaluated. did. The results are as follows.
・ Water permeability time of water-permeable mold 1: 55 seconds ・ Concrete surface appearance: ◎
・ Number of bubbles on concrete surface: 17

  From this result, the number of bubbles on the concrete surface was 17, and 70% of 57 in Comparative Example 1 could be reduced, and the concrete surface was smooth and a good concrete appearance was obtained. The water permeation time of the water permeable mold 1 was 55 seconds, which was within the range of the preferable water permeation time obtained in Examples 1 to 22, and had good water permeability. Therefore, even when resin powder is used as the binder, good water permeability can be obtained as in the case of using the heat-bonding fiber, and the air bubbles on the concrete surface when the concrete is placed is reduced, and the concrete surface is dense. It was confirmed that it contributed to the conversion.

  Also, in the permeable board of Example 32, as in Examples 1 to 22, it has a self-supporting rigidity and can be easily combined with the mold body 10 even in a large formwork or a complicated formwork, In addition, fibers can be processed in the factory or on-site without drilling or cutting, and the board-like water permeable layer 2 after demolding can be used repeatedly without being damaged. Met.

(Example 33)
Next, the performance of the water-permeable mold 1 of the present invention was confirmed assuming a concrete retaining wall as large-sized concrete placement.
As shown in FIGS. 5 (a) and 5 (b), the large concrete casting form has a concrete cross-sectional dimension of 150m for the upper side (D1) and 350mm for the lower side (D2) as a concrete retaining wall of the building. The upper surface is opened so that the length of the surface (H1) is 900 mm, the length of the inclined surface having an inclination angle of 77 ° (H2) is 922 mm, and the lateral width (W + W) is 1780 mm. Assembled. This large concrete casting form is provided with a 12 mm thick urethane coated plywood form on the surfaces other than the vertical and inclined surfaces, and the vertical and inclined surfaces have the same width of 890 mm. The width permeable mold 1 of Example 33 and the urethane-coated plywood mold 100 of Comparative Example 2 are arranged side by side, and the same type of mold (1 and 1, 100 and 100) between the vertical plane and the inclined plane. Were arranged so as to face each other, and the outer surface was reinforced with a pier.

The water-permeable mold 1 of Example 33 was cut out from the water-permeable board of Example 3 to obtain a board-like water-permeable layer 2. As shown in FIG. 6A, the mold body 10 has drain holes 11 having a diameter of 5 mmΦ, and the vertical permeable mold frame 1 has four corner drain holes 11 that are 70 mm wide (P1) from the corners (P1). P3) is provided at a position of 75 mm, and other drain holes 11 are provided at a pitch (P2, P4) of 150 mm. On the other hand, in the permeable form 1 of the inclined surface, as shown in FIG. The drainage holes 11 at the four corners were provided at positions of 70 mm in the horizontal direction (P1) and 86 mm in the vertical direction (P3) from the corner, and the other drainage holes 11 were provided at a pitch (P2, P4) of 150 mm. Next, the mold main body 10 and the board-shaped water permeable layer 2 were combined by fixing them with staples at positions where reinforcing bars were arranged on both the vertical and inclined surfaces.
As the urethane-coated plywood mold 100 of Comparative Example 2, the one of Comparative Example 1 was used.

  In addition, although the separator was installed in the field in order to fix the space | interval of the vertical surface and inclined surface of this large-sized formwork, when the formwork was opened on-site at this time, in the water-permeable formwork 1 of Example 33 It was confirmed that a beautiful opening treatment could be performed without opening the fibers of the board-like water permeable layer 2.

  When the large concrete casting form has been completed, the mineral oil release agent is sufficiently sprayed on the inner casting surface with a sprayer before placing the concrete, and then the raw material is produced from the upper opening. Concrete was poured in twice using a pump and vibrated with an electric vibrator for filling, defoaming, placing the concrete, curing for 2 days, and demolding. The cast concrete that was cast had a composition of cement 316 kg / m3, sand 725 kg / m3, gravel (Gmax, 25 mm) 1.135 kg / m3, water 174 kg / m3, W / C = 55.1%, slump 8 .5 cm was used.

  In addition, the molds 1,100 of Example 33 and Comparative Example 2 that were removed from the mold were washed with water at a pressure of 7.0 MPa using a cyclone jet nozzle of a high-pressure washer (Kacher JTK22), and adhered. Dirt and cement that had been removed were removed, and the mold 1100 after the washing was repeatedly used in the same manner as described above, whereby concrete was cast three times in total. The concrete surface after demolding in each round was observed.

  At the time of concrete pouring, the water-permeable mold 1 of Example 33 can confirm good drainage from all drainage holes 11 on the vertical and inclined surfaces, and the stiffness of concrete and the decrease in fluidity due to drainage can be confirmed. There was no problem with concrete filling and workability. Even in the urethane-coated plywood form of Comparative Example 2, no problem was found in placing concrete three times.

  At the time of demolding, both the molds 1 and 100 in Example 33 and Comparative Example 2 could be easily demolded with a hammer and a hand on both the vertical surface and the inclined surface, and the demolding property was good. In addition, the water-permeable mold 1 of Example 33 is in a form-molded state after demolding, and the board-like water-permeable layer 2 composited on the surface is wrinkled, stretched and damaged due to concrete placement three times. I was not able to admit.

  As for the number of bubbles on the concrete surface, the number of bubble marks or recesses having a diameter of 1 mmφ or more was counted on each of the vertical surface (900 mm × 890 mm) and the inclined surface (922 mm × 890 mm). The appearance of the concrete surface was evaluated in the same manner as in Examples 1-22. Table 4 shows the appearance of the concrete surface at each round.

  From Table 5, the concrete surface has a large number of avatars (bubbles) on the vertical surface and the inclined surface in the arrangement surface of the urethane-coated plywood mold frame 100 of Comparative Example 2, and is particularly inclined. Larger avatars (bubbles) with a diameter of 10 mmΦ or more are increasing toward the top of the surface or vertical surface, and some of the parts need repair. On the other hand, in the arrangement surface of the water-permeable mold 1 of Example 33, the avatar is small and around 10 in both the vertical surface and the inclined surface, and the surface is very smooth and very small. It was a beautiful finish. As described above, in the water-permeable mold 1 of Example 33, the number of bubbles is reduced to almost 1/10 or less compared to the urethane-coated plywood mold 100 of Comparative Example 2 both in the vertical plane and the inclined plane. It can be seen that the bubbles in the concrete were discharged together with the excess water.

  As described above, the water-permeable mold 1 of Example 33 has features that allow for on-site mold processing, and contributes greatly to densification of concrete surface, improvement of quality and durability, etc. However, it was confirmed that the water-permeable mold 1 of the present invention can sufficiently cope with use in a large mold. Moreover, in the water-permeable form 1 of Example 33, even if it used repeatedly for concrete placement, the damage of a water-permeable board was not recognized, but it has confirmed that the water-permeable form for concrete of this invention can be used repeatedly.

1 Water-permeable formwork for concrete 2 Board-like water-permeable layer (water-permeable board)
10 Formwork body 11 Drain hole

Claims (5)

A formwork that can discharge excess water and air bubbles in the cast concrete to the outside of the formwork,
The plate-shaped formwork body and the board-shaped water permeable layer arranged on the concrete placement surface of the formwork body are combined,
The mold body is formed with a plurality of drain holes penetrating the front and back,
The board-like water-permeable layer is a concrete composed of a porous water-permeable board formed of a matrix fiber in which short fibers form a three-dimensional entangled structure and a binder that fixes the short fibers constituting the matrix fiber to each other. Permeable formwork.   The said matrix fiber is a water-permeable form for concrete of Claim 1 comprised by one or more of a chemical fiber, a natural fiber, and an inorganic fiber.   The water-permeable form for concrete according to claim 1 or 2, wherein the binder is composed of heat-bonded fibers having a melting point lower than the melting point or softening point of the matrix fibers.   The water-permeable form for concrete according to claim 3, wherein the heat-sealable fiber is composed of a core-sheath type heat-sealable fiber having a sheath having a melting point lower than that of the core. The board-like water permeable layer has a bulk density of ^{0.3g / cm 3 ~0.9g / cm 3} , the weight ratio of the binder and the matrix fibers (wt%) is 80: 20-50: 50, thickness 1mm It is 10 mm, The water-permeable formwork for concrete of any one of Claims 1-4.

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