JP3228357B2 - Water-permeable sheet for formwork and water-permeable formwork - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water-permeable sheet for a formwork and a water-permeable formwork which is used by being attached to a formwork for forming a concrete casting space in construction and civil engineering work.

[0002]

2. Description of the Related Art In a so-called "formwork method", a conventional formwork is used to define the structure of a structure to be constructed, and to cast concrete into the space to construct the structure. Avoid the formation of so-called "avatars", which occur in the concrete poured into the concrete, but migrate to the concrete-form interface, but cannot be released to the outside air and migrate and concentrate at the interface. Could not be done.

Further, it is necessary to discharge surplus water added in order to secure workability suitable for pumping concrete into a formwork.
No. 6 proposes that “a hole is made throughout the entire surface of the weir plate constituting the formwork, and air and water contained in the concrete pass through the surface of the weir plate that comes into contact with the concrete, but the solid content such as cement particles is Pasting a sheet that does not allow permeation, removing air bubbles and excess water, preventing avatar generation, and improving concrete strength and durability ”so-called“ water-permeable formwork method ”. Indeed, a number of improved methods have been proposed, and we aim to solve the problems.

That is, from the filing of Japanese Patent Application Laid-Open No. 52-137136 (filing date: May 12, 1978), by the end of 1990, more than 60 related patents have been filed. It shows how highly it is necessary to develop a construction method to prevent the occurrence of avatars during concrete construction and improve the surface strength and durability of the construction.

However, the technical contents disclosed by these application patents do not fall outside the scope of the technology disclosed in Japanese Patent Application Laid-Open No. 52-137136, and the function of the filter medium layer, which determines the performance thereof, is described as follows. There is hardly any specification of the required function of the filter medium layer other than `` penetration of such particles is not passed '', and when removing the form after concrete casting, which is essential for practical use as a permeable form method Many of them do not have any provisions regarding the functions relating to the releasability and the functions such as the tensile elastic modulus and the tensile strength of the fiber filter medium layer which determine the feasibility and durability of folded use.

[0006] That is, in the method disclosed in the prior art, the required function of the filter medium layer which determines the performance has not been confirmed and a proper product design has not been performed. A filter medium of a level that allows water to pass but does not allow particles such as cement to pass through is sufficient.Since the material of the filter medium is not specified, it is not possible to peel off the water-permeable form sheet from the structure after casting in practical use. At the present time, the situation is extremely difficult, there is no reusability, and the situation is virtually impossible.

[0007] For this reason, although the idea was an effective method of construction, the basic problems to be overcome remain in the practical application, and the method has not been put to practical use as a practical method. In the following publications, to solve these basic problems, some ideas have been found to improve the releasability and reusability by using a special woven filter medium.

[0008] However, even in the method of using a special woven fabric in which this measure is taken, an effective measure for essentially improving the peeling property is not taken, but only the area where the sheet breaking resistance at the time of peeling is improved is taken. Because it is a thing, sheet destruction at the time of peeling can be avoided and reuse is also possible, but in order to withstand peeling, an extremely high-strength special fabric is required, and the economic burden is large and generalization is hindered, In addition, since the filter medium is made of woven fabric, it is difficult to avoid defects where cast concrete penetrates the woven fabric structure and require a large peeling stress, and the woven fabric pattern is transferred to the concrete surface after peeling. Problems were included.

The method disclosed in Japanese Patent Application Laid-Open No. 52-137136 defines a structure of a structure to be constructed using a formwork, and casts concrete into the space to construct a concrete structure. In principle, in order to prevent the occurrence of "avatars" and to improve the hardness, strength, durability, etc. of the construction surface, we propose an innovative measure,
Unfortunately, it has not been functionally analyzed and defined so as to satisfy the functions required for the practical use and general use, especially for the filter medium layer, and it has not been possible to put it to practical use.

That is, in order to implement the method specified in Japanese Patent Application Laid-Open No. 52-137136 and achieve the desired effect,
As disclosed in this patent publication, simply using a form attached to a sheet that allows air and water contained in concrete to pass through to the surface of the weir plate that contacts concrete, but does not allow solids such as cement particles to permeate It is impossible at all with the `` method of construction '' alone, and the concrete cast at the time of mold release can not be separated firmly with the filter medium and can not be peeled off. Part of the bitten filter media remains, and it is not possible to obtain a uniform and smooth cast concrete surface with improved dense surface hardness and strength.On the other hand, the filter media is also damaged by peeling work and cannot be used again. Unless the filter medium layer is provided with a function capable of achieving the object, the object and effect indicated in the publication cannot be achieved.

[0011] A large number of subsequently filed patents, other than patents specifying that a small number of special fabrics are used for the filter medium layer, will not fall within the imitation range of the method specified in JP-A-52-137136. At least, the function of the filter medium layer is analyzed, and none is designed so as to satisfy the essential conditions.

Furthermore, a non-woven fabric for water absorption and drainage used for a concrete form has been proposed (Japanese Patent Laid-Open No. 2-12).
8802). This nonwoven fabric for water absorption / drainage has a smooth surface layer, an intermediate layer having a relatively high density composed of a fiber layer and a base cloth, and a back surface of an adhesive surface formed by integrating the fiber which has appeared on the back side of the base cloth with the base cloth surface by heat treatment. , The total air permeability is 0.5 to 2.0 cc / (cm ² · second), the vertical permeability is 10 ^-2 to 10 ^-4 cm / second, and the surface layer is made of cement. It has small holes or fiber gaps that do not allow the solid content of the paste to pass through.

However, the nonwoven fabric for water absorption / drainage has a low air permeability, so that moisture is hardly evaporated as a whole, and therefore avatars are easily formed. Also, since the vertical water permeability is small, water moves in the thickness direction of the concrete. It is considered that there is a drawback that the strength of the concrete surface tends to be low, and the strength of the concrete in the longitudinal direction varies because the cement is easily applied to the root of the concrete.

[0014]

DISCLOSURE OF THE INVENTION The present invention solves these basic problems, and discharges air and surplus water contained in concrete to the outside of the system at the time of placing concrete to prevent "avatars" from occurring. A water-permeable sheet for a mold and a water-permeable mold capable of forming a concrete structure intended for the original purpose having high smoothness and high density and having a high surface hardness and strength, and which can be easily peeled off when the mold is released from the mold. It is an object to provide

[0015]

The present invention adopts the following means in order to solve such problems. That is, the present invention relates to a water-permeable sheet used for a formwork for forming a concrete casting space by a formwork and casting a concrete in the space to construct a structure, which is included in the castable concrete. Layer (I) made of a non-woven fabric which is densified and heat-sealed and which does not allow the penetration and intrusion of fine particles such as cement and sand. The air-permeable and water-permeable layer (II) made of non-woven fabric that discharges incoming air and excess water to the outside of the system is integrated, and the air permeability is 9 cc / (cm ² · sec) or more as a whole, and the vertical water permeability is The present invention uses a water-permeable sheet for a formwork, which is at least 0.1 cm / sec.

In the present invention, the filtration layer (I) and the air-permeable and water-permeable layer (II) are integrated by needle punching or hydroentanglement, and the filtration layer (I) has a crossing point of the constituent fibers. are fused is intended to means a water-permeable sheet mold according to claim 1 which is densified to 0.15 g / cm ³ or more (claim 2).

Further, in the present invention, the water-permeable sheet for a formwork according to claim 1 or ² , wherein the filtration layer (I) and the ventilation / water-permeable layer (II) are made of a nonwoven fabric having a basis weight of 50 to 300 g / m ^2. (Claim 3).

The present invention also relates to a formwork in which a concrete casting space is formed by a formwork and concrete is poured into the space to construct a structure. In addition, a water-permeable formwork to which the water-permeable sheet for formwork according to claim 1, 2, or 3 is attached is used as a means (claim 4).

Further, the present invention relates to a formwork for forming a concrete placing space by a formwork, casting concrete in the space and constructing a structure.
The water-permeable sheet for formwork described in 1 above is tightly fixed to the weir plate with the filter layer (I) on the cast concrete side and the ventilation / permeable layer (II) on the weir plate side of the formwork. A sex mold is used as a means (claim 5).

The present invention also relates to a water-permeable sheet for formwork according to claim 1, 2 or 3, wherein the air-permeable and water-permeable layer (II) is thermo-compressed onto a weir plate via a hot-melt adhesive layer. A water-permeable mold formed as a means is used as a means (claim 6).

Hereinafter, the present invention will be described in detail. The water-permeable sheet for formwork of the present invention is a filter layer made of a non-densified nonwoven fabric that transmits air and surplus water contained in cast concrete, and does not allow penetration or penetration of fine particles such as cement and sand. (I) and an air / water permeable layer (II) made of a nonwoven fabric for discharging air and excess water permeating the filtration layer (I) out of the system. The reason why they are integrated is to improve the delamination resistance between the two, and to prevent the water-permeable sheet for formwork from being damaged during the separation. As means for integration, needle punching or hydroentanglement may be used.

Further, the surface of the filtration layer (I), that is, the side facing the cast concrete, must be densified to have a predetermined air permeability. This is because the surface density is increased and the pore size is reduced to prevent a decrease in the releasability due to the penetration of the cast concrete and to secure the surface smoothness.

The density of the filtration layer (I) is 0.15 g / cm
³ or more, preferably 0.15 to 0.7 g / cm ³
Is preferable, and especially 0.2 to 0.5 g / cm ³ is preferable. The density here refers to the apparent density of the filtration layer (I). When the density is less than 0.15 g / cm ³ , avatars are easily formed, which is not preferable.

In order to prevent the occurrence of avatars, the pore size is set at a ventilation rate of 9 cc / cm ² · sec) or more, preferably 1
0 (cc / cm ² · second) or more, more preferably 10
50 cc / (cm ² · second). 9cc / (cm ²・
When the time is less than (seconds), it is not preferable because water hardly evaporates as a whole and avatars are easily formed.

It is preferable that the surface of the filtration layer (I) is not a perfect film. It is preferable that the constituent fibers of the nonwoven fabric forming the filtration layer are heat-sealed at their intersections,
This is to prevent a peeling phenomenon from occurring in the water-permeable sheet at the time of peeling.

Next, the vertical permeability is 0.1 cm / sec or more, preferably 0.1 to 1.0 cm / sec, and more preferably 0.1 cm / sec.
~ 0.7 cm / sec is preferred. If the rate is less than 0.1 cm / sec, the water does not easily move in the thickness direction, so that the strength of the concrete surface tends to be low, and the strength of the concrete in the longitudinal direction tends to vary, which is not preferable. Conversely, if the vertical hydraulic conductivity is too large, the surface hardness, surface strength, and surface density of concrete will not be sufficiently improved, which is not preferable.

It is preferable that the constituent fibers of the filtration layer (I) are heat-sealed at the intersections. Specifically, the fibers are formed by non-woven fabric and calendering.

The nonwoven fabric constituting the filtration layer (I) is a composite fiber of a fiber-forming synthetic polymer compound and a heat-fusible fiber-forming synthetic polymer compound having a melting point of 20 ° C. or lower, for example, a sheath. A core or side-by-side type composite fiber is mentioned, and the ratio of the sheath core is preferably 1/9 to 4/6, and the sheath is preferably a polyolefin such as polyethylene or polypropylene, and the core is preferably a synthetic fiber such as polypropylene, polyamide or polyester.

It is to be noted that a mixed fiber nonwoven fabric having a mixing ratio of 9/1 to 5/5 of a synthetic fiber and a heat-sealable synthetic fiber having a melting point lower than 20 ° C. instead of the composite fiber is used. May be. The web may be formed by blending short fibers of conjugate fibers and ordinary short fibers at a ratio of 2/10 to 8/10: 8/10 to 2/10. Heat-fusible fibers having a melting point lower than 20 ° C. by 2/8 to 8
The web may be mixed at a ratio of / 2.

However, in any case of the nonwoven fabric, the basis weight is preferably 50 to 300 g / m ² . 50g /
When it is less than m ^2, damage due to tearing at the time of peeling occurs,
If it exceeds 300 g / m ² , on the other hand, if it exceeds 300 g / m ² , the amount of filtration is extremely reduced and the hardening of concrete is delayed, which is not preferable.

The air-permeable and water-permeable layer (II) discharges air and surplus water permeating the filtration layer (I) to the outside of the system, but also has an effect on the reuse of the water-permeable sheet. It is preferable to use a long-fiber non-woven fabric because it is excellent in cost in addition to improving sheet reusability. Incidentally, the basis weight of the nonwoven fabric of the ventilation / water permeable layer (II) is preferably 50 to 300 g / m ² . 50g / m
^If it is less than ² , tearing or tearing due to insufficient sheet strength occurs during construction, which is not preferable. On the other hand, 300g
/ M ² , the ventilation rate is less than 10 cc / cm ² · second, which is not preferable because of delay in hardening of concrete.

It is preferable that at least 80% or more of the low melting point fibers of the nonwoven fabric constituting the filtration layer (I) are heat-sealed. This is to prevent the occurrence of avatars.

In the case of the filter layer (I), the nonwoven fabric constituting the filtration layer (I) and the air / water permeable layer (II) preferably has a fiber thickness of 0.5 to 5 d. In the case of II), 1d to 10d are preferable. This is to make the nonwoven fabric excellent in practicality.

[0034]

【Example】

Examples 1-2, by conventional examples 1 to 3 a conventional method of spunbonded, made of polyethylene terephthalate 4d basis weight 255g / m ^2, 135g / m
The ^second nonwoven respectively prepared, using an embossing calender rolls 180 ° C., to produce breathable, permeable layer (II) subjected to pre-embossing at a linear pressure of 60 kg / cm. Next, using a sheath-core type composite fiber having a fiber length of 36 mm and a sheath of 2 denier made of polyethylene and a core made of polypropylene, a web having a basis weight of 95 g / m ² was produced in a usual nonwoven web production process. This web is wrapped with the above-mentioned ventilation / water permeable layer (I
I) layered on top of a needle FPD-
Using 1-40S, needling is performed at a needling depth of 13 mm and a needling density of 95 pene / cm ² , and then calendering is performed with a calender roll at 140 ° C. at a linear pressure of 60 kg / cm. I) and the ventilation / water permeable layer (II) are integrated.
g / cm ³ ). At the same time, the spunbonded nonwoven fabric forming the air-permeable and water-permeable layer was compressed by the back pressure of the cast concrete so that the thickness did not fluctuate significantly.

Further, a spunbonded nonwoven fabric made of 4d polyester filament by a conventional method (a basis weight of 300 g /
m ² ), and then passed through a calender roll controlled at a surface temperature of 220 ± 2 ° C. (conventional example 1).
the nonwoven m ² 95 penetrometer / cm ² of the needle ring density that needling with (conventional example 2), crates only ones to produce a (conventional example 3), the permeability properties of the sheet each in Table 1 Indicated.

[0036]

[Table 1]

The measurement in Table 1 was conducted by the following method. Weight (g / m ² ): The mass of a test piece 1 m × 1 m is measured. Thickness (mm): Pleated surf is 9 mm in diameter
Is measured with a load of 20 gf / cm ² using a measuring device of No. Tensile strength (kg / 5cm): JIS L-1096
According to the 6.12.1 strip method. Elongation (%): According to JIS L-10966 6.12.1 strip method. Tear strength (kg): JIS L-1096 6.15
・ Two single tongue method. Abrasion strength (class): JIS L-1096 6.17.3
Taber method Water absorption: JIS L-1096 6.26.1A method Air permeability [cc / (cm ² · second)]: JIS L1096
6.27.1 Peel strength (kg / 5cm): Test piece 5cm × 20cm
After peeling off the interface in advance to a length of 5 cm, the peeled pieces were gripped by a constant-speed elongation-type tensile tester, each of which was attached to the upper and lower sides as a gap of 10 cm. The value was represented by n = 3.

Vertical water permeability (cm / sec): JIS A-
1218. Number of avatars (ke / m ² ): The number of dents of 1 cm ² or more on the concrete surface is visually counted and converted to 1 m ² . Attachment of fibers to the finished surface (ke / m ² ): The number of fibers having a length of 1 cm or more attached to the concrete surface is visually counted and converted per m ² .

Examples 1 and 2 showed good surface finish without generation of avatars and adhesion of fibers even when concrete was cast. On the other hand, in the conventional example 1, although the amount of passage is small and the concrete is cast, the adhesion of the fiber is small, but the countless avatars (due to poor air removal of the air in the concrete) are generated on the concrete surface, which is not preferable. Was. Further, in Conventional Example 2, although the avatar is not generated even when the concrete is poured with a large amount of ventilation, short fiber debris remain uncountably on the concrete surface, which is not preferable. In Conventional Example 3, the number of avatars was three, and the number was infinite.

[0040]

The water-permeable sheet for a formwork and the water-permeable formwork of the present invention can be easily peeled when the mold is released from the mold, without being damaged at the time of peeling, and when the excess water permeates. Has good reusability because it is not subject to contamination and clogging by cement fine particles, etc.Moreover, it has high tensile elasticity and high strength, so it is difficult for the sheet to be distorted when the mold is released from the mold,
There is no obstructive element for re-use due to the lifting of the sheet or the generation of wrinkles, so that it can withstand repeated use and has a remarkable effect that avatars do not occur on the concrete surface.

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-3-130109 (JP, A) JP-A-2-128802 (JP, A) JP-A-1-190410 (JP, A) JP-A-3-130 96305 (JP, A) JP-A 1-1171615 (JP, U) (58) Fields surveyed (Int. Cl. ⁷ , DB name) B28B 7/36

Claims (6)

(57) [Claims] 1. A water-permeable sheet used for a formwork for forming a concrete casting space by a formwork and casting a concrete in the space to construct a structure, which is included in the castable concrete. A filter layer (I) made of a nonwoven fabric which is made of a high-density and heat-sealed non-woven fabric that allows air and surplus water to permeate and does not allow the penetration and penetration of fine particles such as cement and sand; The air-permeable and water-permeable layer (II) made of a nonwoven fabric that discharges incoming air and excess water to the outside of the system is integrated, and the air permeability is 9 cc / (cm ² · second) or more as a whole and the vertical water permeability is 0. A water-permeable sheet for formwork, which is at least 1 cm / sec. 2. The filtration layer (I) and the air / water permeable layer (II) are integrated by needle punching or hydroentanglement treatment, and the filtration layer (I) is heat-sealed at the intersection of its constituent fibers. formwork for permeability sheet according to claim 1 which is densified to 0.15 g / cm ³ or more. 3. The water-permeable sheet for a formwork according to claim 1, wherein the filtration layer (I) and the ventilation / water-permeable layer (II) are made of a nonwoven fabric having a basis weight of 50 to 300 g / m ² . 4. A concrete casting space in which a concrete casting space is formed by a formwork, and concrete is poured into the space to construct a structure. A water-permeable formwork to which the water-permeable sheet for formwork according to 1, 2, or 3 is attached. 5. A formwork for forming a concrete casting space by a formwork and casting concrete in the space to construct a structure, wherein the water-permeable sheet for a formwork according to claim 1, 2 or 3 is used. , Put the filtration layer (I) on the concrete side,
A water-permeable formwork in which the ventilation / water-permeable layer (II) is closely fixed to the formwork with the formwork being on the weirboard side. 6. Water permeability formed by thermocompression bonding the air-permeable / water-permeable layer (II) of the water-permeable sheet for formwork according to claim 1, 2 or 3 onto a weir plate via a hot melt adhesive layer. Sex formwork.