JPH01158179A - Sheet for sticking formwork - Google Patents

Abstract

PURPOSE: To obtain a concrete structure which has a fine surface, high strength and high quality by constituting a sheet to be stuck to an inside surface of a form by adhering a permeable material and an impermeable film having many pores punched. CONSTITUTION: On an inside surface of a form 16, a sheet for sticking form constituted by adhering a permeable material 10 and an impermeable film 12 having many pores 14 punched is stuck and concrete 18 is placed. Therefore, surplus water is discharged from the pores 14 to the outside via the permeable material 10 and curing is performed in a wet state, securing water required for hardening. As a result, peeling of the sheet can be easily performed even after concrete is completely hardened and a structure which has a fine surface, high strength and high quality can be made.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) This invention relates to a sheet for pasting formwork, and particularly to a sheet that can simultaneously improve the surface condition of poured concrete after hardening and its curing condition. .

(Prior Art) As is well known, when constructing a concrete structure, excessive water is added to concrete to ensure workability.

This excess water is removed by compacting the concrete after it is placed in the formwork.

However, the water separated during compaction is accompanied by air bubbles.
It collects on the formwork surface, causing so-called pockmarking on the hardened concrete surface.

Concrete structures with such pockmarks not only impair their aesthetic appearance, but also cause cracks due to cross-sectional defects.

In addition, excess water collected at the interface between the poured concrete and the formwork increases the water-cement ratio of the concrete in this area, reducing the durability of the concrete after hardening.
Accelerates deterioration due to salt damage, etc.

Such problems occur significantly in concrete structures having sloped surfaces.

Therefore, as a method to solve such problems, for example, Japanese Patent Application Laid-Open No. 60-43528, 1987 Concrete Engineering Annual Paper Report Collection-1 ([1054] Concrete mold using super absorbent polymer sheet) As disclosed in ``Method for Improving the Physical Properties of Frame Surfaces'', a method has been proposed in which a water-permeable or water-absorbing sheet is attached to the surface of the formwork that the concrete to be poured will come into contact with. The sheets used for this have the following problems.

(Problem to be solved by the invention) In other words, in the former method, a sheet made of porous material is used, and excess water is actively drained through this sheet from the time of pouring concrete to the time of hardening. This prevents the concrete from deteriorating at the interface, but if the porous sheet is left in contact with concrete for a long period of time, the concrete will penetrate into the porous areas and harden, making the sheet extremely difficult to remove. There was a problem.

To solve this problem, it seems to be possible to remove the sheet early before the concrete completely hardens, but if the sheet is removed early, the problem arises that the concrete will not be able to cure sufficiently.

In other words, when concrete is cured in a moderately moist state, its strength is better developed than when it is cured in the air, but if the sheet is removed early, the curing period in the air becomes longer and the concrete is not cured properly. concrete becomes unable to develop its strength.

Furthermore, since the sheet of porous material has a large degree of opening, even if it is kept in contact with the concrete surface for a long period of time, it is difficult to cure it in an appropriately moist state.

On the other hand, the latter method uses a sheet made of fibrous material impregnated with a superabsorbent polymer, and uses the superabsorbent polymer to absorb excess water from poured concrete, thereby removing pockmarks, etc. However, the superabsorbent polymer did not absorb as much excess water as expected, and the absorbed polymer gelled and closed the voids in the fiber material, so the excess water was not drained sufficiently and the surface strength of the concrete was sufficiently increased. The problem was that I couldn't do it.

This invention was made in view of these conventional problems, and its purpose is to be able to maintain the aesthetic appearance by easily peeling off the concrete even after it has completely hardened, and to prevent the concrete from hardening. While securing the necessary moisture,
To provide a formwork pasting sheet that can be cured in a wet state.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a sheet that is attached to a formwork surface that comes into contact with poured concrete, the sheet being placed on the formwork side. A water-permeable material and an impermeable film with a large number of pores attached to the water-permeable material and arranged on the side of the contact surface with the concrete.

(Function) According to the sheet with the above configuration, since an impermeable film with many pores is adhered to the water permeable material, when concrete is poured into the formwork, the pores are removed. The holes will be blocked by the aggregate in the concrete, but the poured concrete has its own weight, which acts as lateral pressure on the formwork, and this pressure causes excess water to flow between the aggregate and the inner surface of the film. The water passes through the gaps and reaches the water-permeable material through the pores, and is drained from the water-permeable material to the outside.

Then, as the poured concrete gradually hardens and the lateral pressure acting on the formwork decreases, the pores in the sheet are blocked by aggregate, so drainage also decreases accordingly, causing the concrete to harden. In addition to securing the necessary moisture, the film itself is water-impermeable, blocking contact with air.
Curing is carried out in a moist state.

Furthermore, since the film is in contact with the concrete surface, it can be easily removed even after the concrete has sufficiently hardened.

(Embodiments) Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIGS. 1 to 3 show an embodiment of a form pasting sheet according to the present invention.

The sheet shown in the figure includes a water-permeable material 10, such as a nonwoven fabric of a predetermined thickness, and a synthetic resin, such as polyethylene or polypropylene, bonded to the water-permeable material 10.

Water-impermeable film 1 made of ethylene vinyl acetate, etc.
It is composed of 2.

The film 12 has a thickness of about 20 to 100 μmm, and has a large number of pores 14 passing through it.
・is drilled.

The diameter of the pores 14 is smaller than the average particle size of the fine aggregate 15 used in the concrete to be placed, for example, about 0.6++n++, and the maximum particle size of cement, for example, 0. It is set larger than .1mm+.

Further, the surface side of the film 12 is preferably a smooth surface.

In addition, when bonding the film 12 to the water-permeable material 10 made of non-woven fabric, the non-woven fabric is composed of concentric or sheath-core adhesive fibers, and the film 12 with the pores 14 perforated by press processing is attached to the non-woven fabric. Place the nonwoven fabric and film 12 on the top surface.
It is desirable to bond the film 12 under pressure using a roller or the like, and if the sheet is produced in this way, the pores 14 of the film 12 will not be clogged with adhesive.

The sheet in which the water-permeable film 12 in which the pores 14 are formed is adhered to the water-permeable material 10 is, for example, pasted on the inner surface of the formwork 16 using an adhesive before it is installed, or it is attached at appropriate locations. is attached by mechanical means, and at this time, the sheet of water-permeable material 10 is installed on the formwork 16 side so as to be in contact with the concrete 18 on which the film 12 is cast.

FIG. 1 shows a state in which a formwork 16 with a sheet pasted thereon is installed and concrete 18 is poured into the formwork 16.

When the concrete 18 is placed, it is compacted by its lateral pressure, vibrator, etc.

At this time, since an impermeable film 12 in which a large number of pores 14 are made in a water-permeable material 10 is adhered to the inner surface of the formwork 16, concrete 18 is poured into the formwork 16. Then, the pores 14 are closed relatively quickly by the aggregate 15 in the concrete 18, but the poured concrete 18 has its own weight, which acts on the formwork 16 as lateral pressure.

When such pressure is applied, excess water in the concrete 18 flows toward the formwork 16 side, passes through the gap between the aggregate 15 and the inner surface of the film 12, and flows through the pores 14 into the water-permeable material 1.
0, and water is drained from the water-permeable material 10 to the outside.

Then, the poured concrete 18 gradually hardens,
When hardness is developed, the lateral pressure acting on the formwork 16 decreases,
Along with this, since the pores 14 of the film 12 are closed with the aggregate 15, the amount of drainage also decreases accordingly, so that the moisture necessary for hardening the concrete 18 is secured, and the film 12 itself is Since it is impermeable, there is no drainage from this part, and contact between the concrete 18 and air is cut off, and curing takes place in a wet state.

In addition, 18 layers of poured concrete were covered with 1 film.
2 are in contact with each other, it can be easily peeled off even after the concrete 18 has sufficiently hardened.

This prevents pockmarks from forming on the surface of the constructed structure, and provides concrete with higher strength than when it is cured in air.

FIGS. 3 and 4 show a test form A, which was carried out to confirm the effect of the form pasting sheet according to the present invention;
The test results are shown.

The test form A was made of water-resistant plywood and had the dimensions shown in FIG. 3(a), and had a vertical surface B, an approximately 45 degree inclined surface C1, and a horizontal surface.

Then, sheet E is attached to the front and rear surfaces of formwork A, test concrete F is poured into the upper opening of formwork A, and after the concrete F has hardened, it is taken out and the internal unconfined compressive strength and surface strength are measured. was measured.

As sheet E, the present invention product (2) and the conventional product (2) made of the above-mentioned super absorbent polymer sheet were prepared for comparison.

The product (■) of the present invention is a nonwoven fabric made of a blend of polyester and rayon with a thickness of 0.5 mm, and a film made of ethylene vinyl acetate with a thickness of 30 μm adhered to it.
Pores with a diameter of 0.6 mm were drilled at a pitch of 14 mn+.

The conventional product ■ is called Kurazap Sheet (product name manufactured by Kuraray Co., Ltd.), and is made by impregnating a fiber material with a thickness of about 0.35 mm with a super absorbent polymer, and the weight per unit area is 4.
0g was used.

For test concrete F, ordinary Portland cement was used, and fine aggregate, coarse aggregate, and admixture were mixed to achieve the mixing ratio shown in Table 1 below.

The unconfined compressive strength was determined by cutting out core samples from each of the obtained test specimens according to JISA1109.

The surface strength was tested with an N-type Schmidt hammer after 7 days of age.

FIG. 4 shows the test results conducted by the above method, and in this figure, the value obtained with the test form made only of waterproof plywood is set as 100, and the value is expressed relative to this.

As is clear from the results shown in FIG. 4, when the product (2) of the present invention is used, the surface strength of both the vertical surface B and the horizontal surface of the inclined surface (C1) is improved compared to the conventional product (2).

In addition, not only the surface strength but also the internal uniaxial compressive strength is greater than the conventional product (2).

(Effects of the Invention) As explained above in the embodiments, according to the formwork pasting sheet according to the present invention, the sheet is attached to a water-permeable material placed on the formwork side, and is bonded to this water-permeable material, thereby bonding the sheet to concrete. It is constructed with a water-impermeable film with many pores placed on the contact surface side, so it can be easily peeled off after the concrete hardens, and the concrete can be cured in a wet state, resulting in high strength. high quality concrete structures can be obtained.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram of the state in which the sheet according to the present invention is attached to a formwork and concrete is poured, Figure 2 is an explanatory diagram of the state of drainage of excess water, and Figure 3 is an explanatory diagram of the formwork used in the test. Explanatory diagram,
FIG. 4 is a graph showing the test results. 10...Water permeable material 12...Film 14...
......Pore 16...Formwork 18...Concrete Patent applicant Obayashi Co., Ltd. Interrogation Nippon Vilene Co., Ltd. Agent Patent Attorney - Ken Iro Axis
Patent Attorney Masatoshi Matsumoto, Fig. 1 Fig. 2 Fig. 3 (0) (b) Punishment F Kibatsu B
11 items■ Compliant product■ Figure 4(b) Invention A■ Compliant product■

Claims (2)

[Claims] (1) In a sheet that is affixed to the formwork surface that comes into contact with poured concrete, the sheet is attached to a water-permeable material placed on the formwork side, and is adhered to this water-permeable material, and is attached to the surface in contact with the concrete. 1. A sheet for pasting formwork, characterized by comprising a water-impermeable film having a large number of pores arranged therein. (2) The formwork attachment sheet according to claim 1, wherein the film has a smooth surface that comes into contact with the concrete.