JPH0541407B2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a curing sheet that is attached to the surface of a formwork when fresh concrete or mortar is poured into the formwork and hardened. For more information,
The present invention relates to a curing sheet that has water permeability, air permeability, and excellent water and air discharge properties.

<Conventional technology and issues> In the concrete formwork construction method, in order to increase the fluidity of the cast ready-mixed concrete or mortar so that it fills every corner of the formwork, it is necessary to use a surplus of water exceeding the amount of water required to harden the cement. water is added.

For this reason, when fresh concrete or mortar is poured into the formwork and compacted using a vibrator, breathing water and air bubbles in the concrete collect on the surface of the concrete, resulting in insufficient surface strength of the concrete and An "avatar" was formed on the surface, which was unfavorable in terms of durability and appearance.

Therefore, holes were made in the formwork to ventilate the inside of the formwork.
A water-permeable base material such as non-woven fabric or woven fabric is attached, and the weight of the poured concrete is used to permeate and deaerate the breathing water and air, reducing the water-cement ratio on the surface of the concrete. A dewatering formwork construction method has been developed that increases the density and strength of the surface and reduces ``avatar'' on the surface.

However, conventional materials attached to formwork, specifically non-woven fabrics and woven fabrics, have water permeability and air permeability, so they are effective in reducing ``avatar'' on the concrete surface and making the surface denser. Concrete invades the concrete and, after curing, peelability is poor when removing the nonwoven fabric or woven fabric from the concrete. This causes the nonwoven or woven fabric to stretch or become damaged, making it impossible to reuse it. Additionally, fibers adhere to the concrete during peeling, resulting in poor paintability. Furthermore, traces of the texture of the non-woven fabric or woven fabric remain on the surface of the concrete, resulting in disadvantages such as poor smoothness.

A laminate in which a perforated sheet or film is laminated on the surface of a non-woven fabric or woven fabric has a good concrete surface smoothness, but the cement that permeates through the pores of the sheet or film adheres to the non-woven fabric or woven fabric, so it must be cleaned. It won't happen. Furthermore, when the laminate is dried after use, the nonwoven fabric or woven fabric shrinks, causing wrinkles in the sheet or film, or the laminate curling, resulting in poor reusability.

The present invention improves these drawbacks, and makes it possible to obtain concrete that has a smooth concrete surface after curing, has less occurrence of avatars, has a densified concrete surface, has high surface strength, and has excellent durability. To provide a curing sheet that is easy to use and inexpensive.

<Means for Solving the Problems> In order to prevent the occurrence of avatars on the concrete surface and obtain concrete with a smooth surface and high surface strength, the present inventor has developed a method for reuse with a high air and water discharge effect. As a result of intensive research in order to obtain a curing sheet with excellent properties, we found that the sheet material has pores that allow air and water to pass through, and that the contact angle of the sheet surface with water is adjusted so that water can easily pass through. By making the sheet material hydrophilic so as to lower the water content, and by providing an uneven drainage groove on the back side of the sheet material with a concave and convex portion connected to it so that air and water that have passed through the sheet material can be easily discharged, The inventors discovered that this method is extremely effective in eliminating air and water, and that the sheet is also excellent in cleaning properties after curing, leading to the completion of the present invention.

<Example> An example of the implementation of the present invention will be described based on the drawings. The sheet material 1 is made of a soft thermoplastic resin such as soft vinyl chloride resin, has a hydrophilic property, has a smooth surface, and has a smooth back surface. The recesses 2 are provided with a continuous pattern of protrusions and recesses, and a large number of pores 3 penetrating from the front surface to the back surface are formed to maintain water permeability and air permeability.

In addition to the vinyl chloride resin described above, the soft thermoplastic resin in the present invention includes vinyl chloride-vinyl acetate copolymer, vinyl chloride-urethane copolymer, polyvinyl alcohol, polyethylene, ethylene-vinyl acetate copolymer, polypropylene, Ethylene-
Thermoplastic resins such as propylene copolymers, nylon resins, and polyesters can be used, but soft vinyl chloride resins with added plasticizers are preferred from the viewpoint of ease of drilling with a needle roll, ease of peeling from concrete, and economic efficiency.

As the plasticizer, common phthalate plasticizers, phosphoric acid plasticizers, polyester plasticizers, etc. can be used, and the amount of the plasticizer to be added can be determined as appropriate depending on the mode of use.

As a method of imparting hydrophilicity to the sheet fabric 1,
In the case of hydrophobic resins, there are methods such as blending a hydrophilic resin with the resin, blending a surfactant with the resin, and treating the sheet surface with a surfactant. In consideration of economy and durability, a method of adding a surfactant to the resin is preferred. In the case of a hydrophilic resin, it may be used as is, but a similar method is optional.

Surfactants include anionic surfactants such as alkyl sulfonates and alkyl sulfates, cationic surfactants such as higher amine halogenates and quaternary ammonium salts, polyethylene glycol fatty acid esters, sorbitan fatty acid esters, etc. Although any surfactant such as nonionic surfactants can be used, surfactants with good heat resistance are preferred.

The number of surfactants to be added may be appropriately adjusted so that the contact angle between the sheet material 1 and water is 45 degrees or less, preferably 35 degrees or less.

If the contact angle with water is 45 degrees or more, water permeability is poor;
The surface strength of the concrete is not high, and the number of avatars is large, which is not desirable.

Furthermore, since the sheet material contains a surfactant or has been surface-treated, the sheet can be easily separated from concrete after curing, and since concrete does not adhere to it, it can be cured for a long period of time.

The pores 3 are formed in the sheet material 1 with a diameter of 5 to 500 ml so that air and water permeate from the front surface to the back surface of the sheet material 1.
A large number of holes in the range of 500〓 are drilled,
Preferably, the range is 10 to 300〓. If it is less than 5, the water permeability will be poor and the strength of the concrete surface will not increase. If it is more than 500〓, the cement tends to flow out, the pores become clogged, and pore marks are formed on the surface of the concrete after curing, which impairs the surface smoothness, which is not preferable. Furthermore, the physical strength of the sheet itself decreases, which is not preferable. The number of holes is preferably in the range of 10 to 200 holes/cm ² , more preferably 20 to 100 holes/cm ² . Number of holes is 10/cm ²
Below this, water permeability takes time, deaeration becomes insufficient, and a lot of avatar occurs, which is not preferable. on the other hand,
If it exceeds 200 pieces/cm ² , the physical strength of the sheet decreases, which is not preferable.

Air permeability is also related to water permeability, so it cannot be absolutely limited, but air permeability is preferably in the range of 2 to 200 c.c./cm ² /sec, and more preferably 10 to 100 c.c./sec.
The range of cm ² /sec is good because there is less avatar on the concrete surface.

The holes in the sheet can be formed thermally or mechanically using a laser beam, a needle roll, or the like. Among these, a method of embossing by heating the needle using a needle roll is preferred because it is easy and can be processed industrially at low cost.

Even if the sheet has pores, if the sheet is hydrophobic, water will not be able to pass through because surface tension will form a film on the surface of the pores and seal the pores.
As a result, air permeability deteriorates, avatars occur on the concrete surface, surface strength does not increase, and simply making holes in the sheet is not effective.

Therefore, in order to improve water permeability, it is necessary to impart hydrophilicity to the sheet material as described above to reduce the surface tension of water.

In order to improve the discharge mechanism for water and air that has passed through the sheet material 1, the uneven pattern is formed on the back surface of the sheet material 1 in an uneven shape with continuous concave portions 2. This uneven pattern may be formed in a straight line or curved shape such as a vertical groove, a horizontal groove, or an oblique groove in order to make the recess 2 into a continuous groove so that the recess 2 becomes a drainage groove. It is also possible to form a so-called uneven texture in which the first part is an independent part and the remaining part is a concave part 2.

If the back side of the sheet is smooth, the sheet will stick tightly to the formwork and water and air that have passed through the sheet cannot be discharged, resulting in avatars on the concrete surface and the surface strength will not be high.

Therefore, by embossing a concave-convex pattern with continuous concave portions 2 on the back side of the sheet material 1,
A certain gap is created between the sheet and the formwork, and water and air that permeate through the sheet are transmitted through the recesses 2 and are smoothly discharged, so the occurrence of avatars on the concrete surface is extremely reduced, and the concrete surface is also smooth. It becomes denser and stronger.

Since the concave portion 2 serves as a drainage groove in this manner, it is preferable that the pore 3 be located in the concave portion 2, but it may be located in a convex portion. The uneven convex portion has a function of holding the sheet to the formwork,
A flat shape is preferred.

Furthermore, by providing an air and water discharge function on the back surface of the sheet, it becomes possible to use the sheet alone as a curing sheet. This makes it easy to clean after peeling off the sheet after concrete curing, and it dries quickly, making it much more reusable.

Next, a method for manufacturing the sheet of the present invention will be described.

Appropriate amounts of plasticizer, stabilizer, filler, colorant, and surfactant are added to vinyl chloride resin, kneaded, and rolled with a calendar roll to form a sheet of 0.5 to 0.8 mm.Then, the sheet is shaped using an embossing machine. Tighten by heating and pressing with a grain roll with a textured pattern on one side. Next, the sheet is pressed with a needle roll heated to 60-100°C to make holes in the sheet.

The soft vinyl chloride resin sheet thus obtained has a flat surface and an uneven pattern on the back surface, the contact angle between the sheet and water is 45 degrees or less, and the pore diameter is 5 to 500 degrees. 〓The number of holes is 10 to 200/
cm ² and has an air permeability of 2 to 200 c.c./cm ² /sec.

The contact angle, pore diameter, number of pores, and air permeability are adjusted within the above-mentioned ranges according to the manner of use.

Examples 1 to 2 and Comparative Examples 1 to 4 according to specific embodiments are shown below.

The blended composition shown in the table of the attached sheet was kneaded with a Banbury mixer and rolled with a calendar roll to form a 0.6 mm sheet, which was then pressed with a textured roll to squeeze it on one side of the sheet. Next, the needle planting density is 25 needles/cm ² , the average needle diameter is 200〓, and the needle temperature is 80㎜.
Press 3 times with a needle roll at ℃, the number of holes is 75 holes/cm ² ,
Holes with a diameter of 75 to 125 mm were drilled.

Next, the top surface is 45 x 30 cm, the height is 90 cm, and the bottom surface is
The sheet was attached to the inner wall surface of a plywood formwork measuring 45×120 cm and having one side sloped. after that,
Concrete (strength 160 kg/cm ² after curing for 28 days) was poured, compacted using a vibrator, and removed from the mold after curing for 48 hours to obtain concrete. Then, the pock rate and surface strength of the concrete were measured and evaluated, and the results were as shown in the attached table.

Comparative Example 1 is one in which the amount of surfactant added is 1 part by weight, and the contact angle with water is not less than 45 degrees, and Comparative Examples 2 and 3 are in which the uneven pattern is not provided on the back side of the sheet material. In Comparative Example 4, concrete was poured into a known plywood form instead of a composition blended sheet, and the concrete was cured.

In the table *1 SM made by Chitsuso (degree of polymerization 1300) *2 Plasticizer made by Chitsuso *3 Stabilizer 0-130 made by Adeka Argus *4 Stabilizer mark WS made by Adeka Argus *5 Nonionic surfactant Rikemar 0 made by Riken Vitamin -320 *6 Measured with a Frazier type persiameter (Toyo Seiki Co., Ltd.) in accordance with JIS L 1079.

*7 Take a sample in a circular shape with a diameter of 150 mm, set it in a funnel with the flat side of the sheet facing inside, and pour 50 c.c. of water into the funnel.
Measure the time it takes for water to drip.

*8 Drop a small drop of water on the surface of the sheet, and measure the angle between the sheet and the tangent that passes through the point of contact between the sheet surface and the tip of the water drop using a goniometer (Elma Co., Ltd.).
Measured in.

*9 Measure the length of the gap on the 200mm line on the slope of the formwork.

*10 Immediately after demolding the formwork, the vertical part of the concrete was measured using a Schmidt hammer.

<Effects of the Invention> The present invention imparts hydrophilicity to a sheet material made of a soft thermoplastic synthetic resin so that the contact angle with water on the surface of the sheet material is 45 degrees or less, making the surface smooth and having no concave portions on the back surface. A continuous uneven pattern is provided,
The sheet material has a large number of pores that can penetrate from the surface to the back surface, and by placing these holes on the inner surface of the formwork, water and air breathed from the poured concrete or mortar can be absorbed into the sheet material. It has an excellent drainage function that allows water to permeate and aerate from the surface to the back side through the pores, and drain smoothly through the concave and convex pattern on the back side, and the cured concrete has a smooth surface with no pock marks. The formwork construction method has many advantages that cannot be obtained with conventional curing sheets: it has a very small amount of dirt, has a dense surface, is strong, has excellent durability, can be reused, and is economical. A curing sheet can be provided.

[Brief explanation of the drawing]

The drawings show one embodiment of the curing sheet of the present invention, and FIG. 1 is an enlarged rear view, and FIG. 2 is an enlarged cross-sectional view. In the drawings, 1 is a sheet material, 2 is a recess, and 3 is a pore.

【table】

【table】

Claims (1)

[Claims] 1 The sheet material made of soft thermoplastic synthetic resin is made hydrophilic so that the contact angle with water on the sheet surface is 45 degrees or less, making the surface smooth, and the back surface has an uneven pattern with continuous concavities. 1. A curing sheet for concrete formwork, characterized in that it has a large number of pores that can be penetrated from the front surface to the back surface of the sheet material.