JPH0399805A - Ageing sheet for concrete retaining mold - Google Patents

Abstract

PURPOSE:To obtain concrete having a densified surface, high surface strength and excellent durability by a method wherein hydrophilicity is imparted to a sheet and the contact angle with water of the surface of the sheet is set to a specific angle or less to make the surface of the sheet smooth and an embossed pattern is provided to the rear of the sheet and a large number of fine through-holes are opened to the sheet. CONSTITUTION:A sheet 1 is composed of a soft thermoplastic resin such as a soft vinyl chloride resin and hydrophilicity is imparted to the surface of the sheet 1 to make the same smooth while embossed patterns wherein recessed parts 2 communicate each other are provided to the rear of the sheet 1 and a large number of pores 3 piercing from the surface of the sheet to the rear thereof are opened to the sheet to hold water permeability and air permeability. When the contact angle with water of the sheet is 45 deg. or more, water permeability is bad and the surface strength of concrete does not become high and the number of pits also increases. The size of pores 3 is 5 - 500 mum and, when the pore size is 5 mum or less, water permeability is inferior and the surface strength of concrete becomes high. When the pore size is 500 mum or more, cement is easy to flow out and the clogging of pores is generated and pore marks are formed on the surface of concrete to damage the surface smooth ness of concrete.

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. Specifically, the present invention relates to a curing sheet that has water permeability, air permeability, and excellent water and air discharge properties.

<Prior art and problems> In the concrete formwork construction method, in order to increase the fluidity of poured fresh concrete or mortar so that it fills every corner of the formwork, it is necessary to reduce the amount of water h1 necessary for curing cement.
Add excess water.

For this reason, when fresh concrete or mortar is poured into formwork and compacted using a pie break, breathing water and air bubbles in the concrete collect on the surface of the concrete, resulting in a lack of surface strength of the concrete. ,
This created "avatars" on the concrete 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 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 penetrates into the concrete and after curing, peelability is poor when removing the non-silk 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, marks from the nonwoven fabric or silk fabric remain on the surface of the concrete, resulting in disadvantages such as poor smoothness.

A V4 layered structure in which a perforated sheet or film is laminated on the surface of a non-woven fabric or woven fabric has a smooth concrete surface, 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. Must be. Furthermore, when the laminate is dried after use, the nonwoven fabric or woven fabric shrinks, causing wrinkles in the sheet or film or curling of the laminate, 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> The present inventor prevents the occurrence of avatars on the concrete surface,
In order to obtain concrete with a smooth surface and high surface strength, we conducted intensive research to obtain a curing sheet that has a high air and water drainage effect and is highly reusable. The sheet material has pores, and the sheet material is made hydrophilic to lower the contact angle with water on the sheet surface so that water can easily pass through, and air and water that have passed through the sheet material can be discharged. By providing a convex and concave discharge groove with a concave and concave connection on the back side of the sheet material, it is extremely effective in discharging air and water, which was not possible before, and also has excellent cleaning properties of the sheet after curing. This discovery led 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 a soft vinyl chloride resin, has a smooth surface by imparting hydrophilicity, and The back surface is provided with an uneven pattern in which concave portions (2) are connected, 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, and polyethylene. Thermoplastic resins such as ethylene-vinyl acetate copolymer, polypropylene, ethylene-propylene copolymer, nylon resin, and polyester can be used, but plasticizers are preferred due to ease of drilling with a needle roll, ease of peeling from concrete, and economical efficiency. A soft vinyl chloride resin to which is added is preferred.

As the plasticizer, common heptatarate plasticizers, phosphoric acid plasticizers, polyester plasticizers, etc. can be used, and the addition of 9% of the plasticizer can be added as appropriate depending on the mode of use.

Methods for imparting hydrophilicity to the sheet material (1) include, in the case of a hydrophobic resin, a method of blending a hydrophilic resin with the resin, a method of blending a surfactant with the resin, and a method of imparting hydrophilicity to the sheet surface. There are methods such as treatment with surfactants,
In consideration of processability, economic efficiency, and durability, it is preferable to add an interfacial agent to the resin. 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, and polyethylene glycol fatty acid esters and sorbitan fatty acid esters. Although any surfactant can be used, such as nonionic surfactants such as, surfactants with good heat resistance are preferred.

The number of surfactants 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, the water permeability is poor, the surface strength of the concrete is not high, and the number of avatars is large, which is not preferable.

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) have a diameter of 5 to 50 mm in the sheet material (1) so that air and water permeate from the front surface to the back surface of the sheet material (1).
A large number of holes are formed in the range of 0μ, preferably in the range of 10 to 300μ. If it is less than 5μ, water permeability will be poor and the strength of the concrete surface will not increase. If it is more than 500 μm, cement tends to flow out, the pores become clogged, and pores are formed on the surface of the concrete after curing, which impairs the smoothness of the surface, 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/cIi,
More preferably, the range is from 20 to 100 pieces/cj. If the number of pores is less than 10 pores/cd, water permeability takes time, deaeration becomes insufficient, and a lot of pores occur, which is not preferable. On the other hand, if it exceeds 200 f/ci, the physical strength of the sheet decreases, which is not preferable.

Air permeability is also related to water permeability, and although it cannot be generally limited, air permeability is preferably in the range of 2 to 200 cc/d/scc, and more preferably 10 to 100 cc/d/scc.
The range c is good because there is less avatar on the concrete surface.

The holes in the sheet can be formed by a thermal or mechanical method using a radar beam, needle roll, or the like. Among these, the method of embossing with a 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 form a film on the surface of the pores due to the effect of surface tension and seal the pores, making it impermeable for water to pass through. The permeability of concrete also deteriorates, and avatars occur on the concrete surface.
The 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.

The uneven pattern is created by creating concave areas (
2) Make it a continuous uneven shape.

This uneven pattern is formed in the shape of a groove so that the recess (2) becomes a drainage groove, and the recess is in the form of a continuous groove, such as a vertical groove, a horizontal groove, etc.
It may be formed in a straight line or curved shape in the form of an oblique groove, or it may be formed in a so-called concave-convex embossed shape in which the convex portions are independent and the remaining portions are concave portions (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 an uneven pattern with continuous concave parts (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 material are prevented. Since the concrete is smoothly introduced through the recess (2), the occurrence of avatars on the concrete surface is extremely reduced, and the concrete surface becomes denser and stronger.

Since the recess (2) thus serves as a drainage channel, it is preferable that the pore (3) is located in the recess (2), but it may also be located in the convex part. The convex portion having an uneven shape has a function of holding the sheet to the formwork, and is preferably flat in shape.

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, so reusability has been greatly improved.

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

Appropriate A1 plasticizer, stabilizer, filler 1 colorant and surfactant are added to the vinyl chloride resin, kneaded, and rolled into a 0.5-0.8M sheet using a calendar roll.
An embossing machine heats and presses one side of the sheet with a textured roll to tighten it.

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 obtained in this way is
The front side is flat and the back side has an uneven pattern.
The contact angle between the sheet and water is 45 degrees or less, and the pore diameter is 5~
500μ, the number of holes is 10 to 200 pores/ci, and the air permeability is 2
~200cc/ci/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 J blended composition shown in the attached table was mixed with a Pan Bali mixer and rolled with a calendar roll to form o and am sheets.
I pressed it with a grained roll with a textured pattern to tighten it on one side of the sheet. Next, it was pressed three times with a needle roll with a needle implantation density of 25/at, an average needle diameter of 200 μ, and a needle temperature of 80° C., and the number of holes was 75/cIi.

Holes with a pore diameter of 75 to 125 μm were drilled.

Next item, top surface is 45x30cm, a'a size 90i11
．． The sheet was attached to the inner wall surface of a plywood formwork with a lower surface of 45×120 CIl+ and one side surface of which was sloped.

After that, concrete (strength 160 kg after 28 days curing)
/m), compacted with a pie break, and
After curing for a period of time, the mold was removed to obtain concrete. and,
The pock rate 1 surface strength of concrete was measured and evaluated, and the results were as shown in the attached table.

In Comparative Example 1, the amount of surfactant added was 1 part Li, and the contact angle with water was not less than 45 degrees, and in Comparative Examples 2 and 3, no uneven pattern was provided on the back side of the sheet material. In Comparative Example 4, instead of using a composition blended sheet, concrete was poured into a known plywood form and then cured.

Put one on the table *1. Chisso SM (degree of polymerization 1300) *2. Chisso plasticizer *3. Adeka Argus stabilizer 0-130 nide 4. Adeka Argus stabilizer mark WS*5. Nonionic surfactant Rigamal 0-320 * 6 manufactured by Riken Vitamin, measured with a Frazier type persiameter (Toyo Seiki ■) according to JIS L 1079.

*7. A sample was taken in a circular shape with a diameter of 150 IuR, set in a funnel with the flat side of the sheet facing inside, and 50 cc of water was poured inside, and the time taken for 20 cc of water to drip was measured.

*8. A small drop of water is placed on the surface of the sheet, and 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 droplet is measured using a goniometer (Elma ■).

*9. Measure the length of the gap on the track of the slope part 200 of the formwork.

*10. Immediately after demolding the formwork, measure the vertical section of the concrete with a Schmidt hammer.

<Effects of the Invention> The present invention imparts hydrophilicity to a sheet material made of a soft thermoplastic synthetic resin, thereby increasing the contact angle with water on the surface of the sheet material by 45%.
The surface of the sheet material is made smooth by making the surface smooth, and the back surface is provided with an uneven pattern in which concave portions are connected, and a large number of pores are drilled through the sheet material from the surface surface to the back surface. Water and air that breathes from concrete or mortar placed on the inner surface permeates and vents from the surface of the sheet material through the pores to the back surface, and is smoothly discharged through the concave and convex pattern on the back surface. Cured concrete has a smooth surface and a
The formwork has many advantages not available with conventional curing sheets: it has very few "pockets" and therefore has a dense surface, high strength, excellent durability, and can be reused and is economical. We can provide curing sheets for construction methods.

[Brief explanation of drawings]

The drawings show a practical example of the curing sheet of the present invention, in which Fig. 1 is an enlarged back view and Fig. 2 is an enlarged sectional view.
is the sheet material, (2) is the recess, and (3) is the pore.

Claims (1)

[Claims] 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 is provided with an uneven pattern in which concave portions are connected. A curing sheet for concrete formwork, characterized in that it has a large number of pores that can penetrate from the front surface to the back surface of the sheet material.