JPH0455152B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a curing sheet placed along the inner surface of the formwork when forming various types of concrete or hydraulic compositions such as mortar (hereinafter simply referred to as concrete) using a formwork. . [Prior Art] In order to give the ready-mixed concrete or mortar, etc., enough fluidity to completely fill the corners of the formwork, surplus water in excess of the amount of water required for hardening is added. Therefore, when compacting with a vibrator etc., it becomes breathing water and tends to be accompanied by air bubbles. Furthermore, when hard mixed concrete is used, a large amount of air bubbles are likely to be mixed into the concrete during pouring. The formwork used for concrete work is usually composed of a weir plate and a template made of iron or wood, and the surface that comes into direct contact with the concrete is impermeable and air-permeable. It was a hot plate. Therefore, on the surface of the concrete from which the formwork has been removed after curing, so-called pockmarks occur, which are traces of water bubbles that have accumulated on the side of the formwork and air bubbles that have entered the concrete. The occurrence of these pockmarks not only impairs the beauty of the concrete surface, but also causes problems such as a decrease in the surface strength of the concrete and a decrease in durability. In recent years, in order to solve these problems, a method has been proposed in which a curing sheet with good mold releasability, water permeability, and air permeability is arranged on the inner surface of the mold. For example, Japanese Patent Application Laid-Open No. 63-63858 describes a surface layer that has good mold releasability and a large number of water and ventilation pores for poured concrete, and a back surface of this surface layer that allows water and ventilation to flow in the thickness direction. A curing sheet comprising a base layer having a large number of voids is described. The surface layer may be a porous film or flat yarn fabric made of materials such as nylon or polyethylene, and the base layer may be corrugated plastic, felt, needle punch carpet, or the like. [Problems to be Solved by the Invention] However, such curing sheets that have been proposed in the past have a complicated structure when, for example, a plastic molded body is used as the base layer, and the structure is complicated when felt or the like is used as the base layer. There were problems such as insufficient water permeability in the direction parallel to the . Furthermore, in either case, there was a problem in that the thickness and weight of the curing sheet increased. The present invention solves the problems of the conventional curing sheet, and has sufficient releasability and water permeability in the direction parallel to the layer, and has a small thickness and weight.
The purpose is to provide a curing sheet with a simple structure. [Means for Solving the Problems] The present invention provides a curing sheet that has water permeability and air permeability and does not allow solid particles in a concrete composition to pass through, which is placed on the inner surface of a formwork for pouring concrete. It is a laminate of a surface layer made of a fabric having a smooth surface with a diameter of 300μ or less and an inner layer made of a fabric having a rough surface. The weft is made of a woven fabric with flat yarn, the thickness ratio of the flat yarn and monofilament is 1.5 to 30, and the amount of water permeation in the parallel direction from the surface layer to the surface layer through the laminate is 5 to 100 kg/100 cm ² under a pressurized water column of 100 cm.・It is in the curing sheet that is characterized by being hr. In the present invention, the amount of water permeation is measured from the surface layer of a laminated product through the interlayers in a direction parallel to the layers, as measured with a water level difference of 100 cm using a commercially available woven fabric water resistance tester (for example, manufactured by Toyo Seiki Co., Ltd.). This is the amount of water that permeates through. If the water permeability is less than 5 kg/100 cm ² hr, the excess water after concrete placement will not be dewatered at the bottom, and the concrete will shrink significantly during drying, causing cracks, or the concrete will not be able to fully demonstrate its strength. There are problems such as not being able to do it. In addition, the water permeability is 100
If it exceeds Kg/100cm ² hr, excessive dehydration and deaeration will cause a surface dryout phenomenon, causing concrete to lose its fluidity and create many voids, causing problems. In the present invention, a woven fabric having a smooth surface refers to a woven fabric that does not allow solid particles in a concrete composition to pass through, has a relatively smooth surface, and has good peelability from concrete after curing. The preferred surface roughness of this fabric is 300μ or less, and more preferably,
It is less than 200μ. If the surface roughness exceeds 300μ, the problem arises that the peelability of the curing sheet from the concrete after curing is poor. In addition, a fabric with a rough surface has a rough surface with relatively uneven surfaces, and the rough surface forms an effective permeation channel between the laminated layers, and satisfies the water permeation amount range described above. It refers to textiles that have a similar effect. The preferred surface roughness of this fabric is 0.5 mm or more, preferably 0.8 to 5.0 mm, more preferably 0.8 to 3.0 mm. If the roughness is less than 0.5 mm, sufficient permeability channels will not be formed in the direction parallel to the layer. The roughness referred to here is the difference between the maximum and minimum values of surface irregularities measured by a commercially available film/sheet thickness continuous measuring device (for example, manufactured by Anritsu Denki). As the material used for the surface layer, a synthetic resin fabric is preferable in terms of peelability from concrete after placement and good appearance of the concrete surface after peeling. In particular, fabrics using tape-like materials made of synthetic resins such as nylon, polyester, and polyolefin, that is, flat yarn fabrics, are suitable. Among these, polyolefin fabrics are lightweight, low cost, and have good releasability from concrete. is more suitable. Polyolefins include ethylene,
The main component is a monoolefin polymer such as propylene or butene, such as high-density polyethylene, medium- and low-density polyethylene, crystalline polypropylene, crystalline ethylene-propylene block copolymer, polybutene, poly-3- Examples include methylbutene-1, polymethylpentene-1, ethylene-vinyl acetate copolymer, and mixtures thereof. Flat yarn made of polyolefin is produced by making a film using a method such as the T-die inflation method using a raw resin composition containing the polyolefin as the main component and a small amount of other polymers and additives, and then slitting this film. It can be made into a tape. Stretching either before or after slitting is preferred because it improves the strength of the flat yarn, that is, the strength of the fabric. The stretching ratio is about 2 to 10 times, preferably 3 to 8 times. The fineness of flat yarn is 200~
in the range of 300 denier, more preferably 500
~2000 denier. The thread density of the flat yarn fabric is 4 to 30 threads/inch, preferably 8 to 20 threads/inch, and the fineness and placement density of the flat yarn fabric in the surface layer that contacts the concrete surface are determined as appropriate depending on the concrete placement conditions, etc. It will be done. Further, in order to make the surface layer smoother, it is preferable to perform hot pressing at a temperature below the melting point to improve releasability. As for the fabric having a rough surface used for the inner layer, it is necessary that a permeation channel is formed between the surface layer and the inner layer, or between the inner layers, so as to satisfy the water permeation rate of the present invention. The woven fabric having such a rough surface is one using flat yarn and monofilament, that is, a woven fabric using flat yarn for the warp and monofilament for the weft, or a woven fabric using monofilament for the warp and flat yarn for the weft. The ratio of flat yarn thickness to monofilament thickness (direct diameter) is in the range of 1.5 to 30, preferably 2 to 30.
The range is 15. Outside this range, the ratio is 1.5
At the end of the range, it becomes difficult to obtain the water permeability of the present invention, and when the ratio exceeds 15, the surface of the concrete after curing becomes wavy, which is not preferable. The monofilament is, for example, nylon,
It is a filament made of synthetic resin such as polyester or polyolefin, and among them, polyolefin is more suitable because it is lightweight and low cost. A monofilament made of polyolefin uses a raw resin composition containing the polyolefin as a main component and a small amount of other polymers, additives, etc., and usually obtains a filament by drawing a strand extruded with an extruder. The stretching ratio is about 2 to 20 times, preferably 5 to 15 times. The fineness of the monofilament ranges from 200 to 10,000 denier,
More preferably 500 to 5000 deniers. In order to laminate the woven fabrics, they can be fixed and laminated using adhesives, adhesives, heat point seals, powder fusion, or the like. When a pressure-sensitive adhesive or adhesive is used, the application may be applied over the entire surface or partially in the form of dots, strips, etc. When coating the entire surface, care must be taken to ensure that necessary properties such as water permeability and air permeability are not impaired, and consideration must be given to applying the coating at a thickness that creates a dot-like or similar dispersion form. In either case, it is necessary that the adhesion strength between the laminated layers is at least such that the laminated layers do not easily peel off during construction and demolding. In the laminated structure of the curing sheet of the present invention, the fabric having the rough surface forming the permeation channel may be used as the second layer or the third layer, or the second layer and the third layer. Of course, the surface layer and the bottom layer may be made of a woven fabric having a smooth surface, and the intermediate layer (inner layer) may be a single layer or multiple layers of a rough-surfaced woven fabric forming a permeation channel. [Function] The curing sheet according to the present invention has the above-mentioned structure, in which a surface layer of a fabric having a smooth surface and an inner layer of a fabric having a rough surface are laminated, and the fabric having a rough surface has a thickness ratio of 1.5 to 30. It is a relatively thin fabric that uses monofilament and flat yarn depending on the texture, but it has an uneven surface.
An effective permeation channel is formed between the laminated layers with the smooth surface fabric on the surface layer, and the amount of water permeation in the direction parallel to the surface layer is 5 to 100 kg/100.
A high value of cm ² hr can be achieved. Furthermore, since the inner layer fabric is thin, changes in thickness due to the pressure of poured concrete can be ignored, and there is no need to consider the influence of concrete dimensions. The surface fabric with a smooth surface has a roughness of 300μ or less, and after curing,
It has excellent removability from concrete, almost no concrete adhesion to the sheet, and no cleaning is required during recycling, resulting in high work efficiency. The resulting concrete surface is smooth, free of pockmarks, and has excellent durability. Therefore, when concrete is placed along the inner surface of the formwork for pouring concrete, permeability channels and ventilation channels are formed between the layers that are parallel to the formwork surface, and at the same time intersect with the formwork surface that penetrates between the laminated layers. Directional permeability channels and ventilation channels are formed. Excess water, air bubbles, water bubbles, etc. contained in the ready-mixed concrete to be poured are mainly degassed and dehydrated vertically through these laminated layers, and can be dehydrated and dehydrated without creating through holes in the formwork. . However, when using the curing sheet of the present invention, the use of formwork provided with water permeable holes is not excluded. When such a formwork is used, its permeable holes will take charge of partial drainage. In this way, the curing sheet that has formed the permeation channels and water channels allows excess water, air bubbles, and water bubbles from the poured concrete to easily permeate through the air and be discharged.
The degree to which concrete particles block the empty openings, ie, form a floor, is significantly reduced. Of course, there is hardly any phenomenon in which solidified concrete is embedded in the voids of the surface fabric. Therefore, pockmarks do not occur on the surface of hardened concrete, and excellent surface strength and durability such as surface rebound hardness can be imparted. [Example] Each characteristic in the example described later was measured by the following method. Water permeability: Water permeability was measured using a tester based on JIS-L1096, that is, a woven fabric water resistance tester (Toyo Seiki Co., Ltd.) shown in Figure 1.
Co., Ltd.), set the sheet 1 sample on the sample holder 2, overlap the waterproof metal plate 3 on the back side (upper part in the figure), and feed water from the bottom (water inundation area
100cm ² ), and the water permeability (dewatering amount) in the direction parallel to the layer of sheet 1 is measured under a pressurized water column of 100cm. In the figure, 4
is a receiver for permeated water, and 5 is a stand. In this example, after curing, the sheet was peeled off from the concrete surface and the water permeability of the sheet after 5 cycles of use was measured. Surface smoothness: The presence or absence of roughness on the concrete surface after removal from the curing form was observed and evaluated by ranking. 〇: No pockmarks on the surface and small surface irregularities △: No pockmarks on the surface but significant unevenness ×: Pockets are observed on the surface Reworkable adhesion amount: From concrete after curing 5 of the peeled off sheet
Weight gain after cycling was measured. The weight gain is caused by the concrete adhering to the sheet. Surface rebound hardness: The rebound hardness of the concrete surface after curing was measured using a Schmidt hammer. Freeze-thaw test: Cured concrete at 5°C to -18°C for 3 hours.
The dynamic elastic modulus after 300 cycles was measured according to JIS-A1127, and the rate of decrease from the initial value was determined. Removal of the curing sheet: After curing, on the side of the concrete, apply a polyolefin primer and adhesive to the surface of the curing sheet, bond a 50φ metal attachment to the sheet surface, and cut the curing sheet along the attachment with a heat cutter. The peel strength of concrete and curing sheet in the direction perpendicular to the surface of the curing sheet was measured. Example 1 High-density polyethylene tape yarn (1000 denier thickness approx. 40μ) was used, warp and weft density 16×
16/2. A plain weave flat yarn fabric is made into a smooth surface fabric, and the flat tape is used as the weft and high-density polyethylene monofilament yarn (1000 denier diameter approximately 380μ) is used as the warp, and the warp/weft thickness ratio is 9.5. A filament fabric was created and a rough surface fabric was created. A urethane adhesive was applied to obtain a curing sheet in which flat yarn fabric/flat yarn fabric/flat yarn monofilament fabric were adhesively laminated. Next, the wooden formwork 5 is such that the volume of poured concrete will be (width) 500 x depth (thickness) 200 x (height) 430 mm.
The curing sheet was placed along the inner surface of the surfaces (used for four side surfaces and one bottom surface) with the flat yarn fabric facing inside. At that time, an acrylic adhesive was applied to the side of the curing sheet formwork and the curing sheet was adhesively fixed to the formwork. However, one end of the side surface was fixed with double-sided adhesive tape (hereinafter, this surface will be referred to as the peel strength measurement surface). Concrete (compressive strength after 28 days curing in 20℃ water, 300Kg/cm ² ) was poured into this formwork at a pressure of 0.6Kg/cm ² .
I cured it for a day. After that, remove the peel strength measurement surface,
The formwork was removed along with the curing sheet. For the peel strength measurement surface, only the formwork was removed while leaving the curing sheet on the concrete, and the releasability of the concrete and curing sheet was measured according to the method described above. Next, various physical properties of the obtained concrete cured product were evaluated. Example 2 The conditions were the same as in Example 1 except that a curing sheet composed of flat yarn fabric/flat yarn monofilament fabric/flat yarn monofilament fabric was used. Example 3 The conditions were the same as in Example 1 except that polypropylene was used instead of high-density polyethylene. Comparative Example 1 The conditions were the same as in Example 1 except that a nylon 66 multifilament fabric (tensile strength 500 g/3 cm width) was used instead of the flat yarn fabric. Comparative Example 2 The same conditions as in Example 1 were used except that three layers of flat yarn fabric were used. (The warp/weft thickness ratio is 1). Table 1 shows the evaluation results of the physical properties of the cured concrete products produced in Examples and Comparative Examples and the reworkability of the curing sheets used.

〔Effect of the invention〕

This invention is as described above, and by using this curing sheet, it is possible to produce a concrete-like cured product with no blemishes on the surface and excellent surface strength and durability, and the curing sheet can be reused without washing or brushing. It is economical and does not require special holes for drainage and deaeration in the formwork.

[Brief explanation of drawings]

FIGS. 1a and 1b are explanatory diagrams of a method for measuring water permeability and enlarged views of important parts. 1...Curing sheet, 2...Sample holder, 3...
Metal plates, 4...receptors for permeated water, 5...all of them.

Claims (1)

[Claims] 1. A curing sheet that is water permeable and air permeable and does not allow the solid particles in the concrete composition to be placed on the inner surface of the formwork in which concrete is poured, and is made of fabrics that have a smooth surface with a surface roughness of 300μ or less. The rough surface fabric is a laminate of a surface layer consisting of a fabric having a rough surface and an inner layer consisting of a fabric having a rough surface. A curing sheet characterized in that the thickness ratio of the monofilament is 1.5 to 30, and the amount of water permeation from the surface layer through the laminate in a direction parallel to the surface layer is 5 to 100 Kg/100 cm ² hr under a pressurized water column of 100 cm. .