JPH0647868B2 - Formwork for concrete - Google Patents

Description

[Detailed Description of the Invention] When constructing a power transmission tower or the like, concrete is poured by assembling rebars and fixing an iron formwork to the outside, but the problem is that this iron formwork is heavily assembled and disassembled at 300 to 500 kg, and Work such as transportation is difficult.

Currently, various means such as winches or helicopters are used. This weight becomes a problem especially in poor location conditions such as in mountainous areas.

<Purpose of the Invention> By making this mold frame from cloth, it is possible to greatly reduce the weight, and since it is flexible, handling becomes very easy.

However, if an easily stretchable cloth is used, it will be deformed remarkably by the pressure when pouring concrete, and if the strength is insufficient, it will break or become drum-shaped and the intended purpose cannot be achieved.

Further, when the affinity between the cloth and the mortar is high, the concrete solidifies and a large amount of the mortar adheres to the form when the form is removed, which increases the weight of the form and makes the form removing work difficult.

The present invention is directed to solving such problems in concrete formwork.

<Structure of the Invention> That is, the present invention comprises a cloth composed of high-strength and low-elongation organic fibers and processed with one or more release agents selected from the group consisting of fluororesins and silicone resins. Formwork for concrete.

Here, as the organic fiber, a type of hard strength and low elongation type is preferable. If a low strength and high elongation type is used, the mold may swell into a drum shape due to the injection of concrete, and in some cases breakage occurs. Specifically, wholly aromatic polyamide fiber, wholly aromatic polyester fiber, and high-strength polyester are preferable. Chemical resistance to withstand alkali and high temperature treatment,
In particular, Technora fiber (manufactured by Teijin Ltd.) having extremely high alkali resistance is preferable. The cloth may be in any form such as woven fabric, knitted fabric, and non-woven fabric as long as it has necessary strength, but it is required that it has sufficient water permeability (for example, opening by texture).

Regarding the shape of the fibers constituting the cloth, short fibers are preferably used rather than long fibers in terms of increasing the dimensional stability of the form, and the basis weight of the cloth is preferably about 200 to 500 g / m ² . For example, a matte composition (2/2 dobby) having a crisp feeling is used.

The release agent is selected from the group consisting of fluororesins and silicone resins. You may mix and use both.

Specifically, poly (vinylidene difluoride), polyvinyl fluoride,
Fluorinated ethylene propylene, polyfluorinated alcohol, poly 4
Examples include ethylene fluoride, dimethylpolysiloxane, and methylhydrogenpolysiloxane.

Particularly, polytetrafluoroethylene gives the most preferable results in terms of releasability and durability. The release agent may be used in any form such as a solution, an emulsion and a suspension. A known method such as an impregnation method or a coating method may be used for processing the cloth with a release agent, but it is necessary to perform processing so that the texture or the stitch of the cloth remains. This is because the excess water from the texture is used as reactor water to develop the strength early and help shorten the construction period. Especially polytetrafluoroethylene at high temperature (around 370 ℃)
The one treated with is excellent in durability and can form a frame with excellent releasability.

<Effects of the Invention> The present invention has the following effects.

(A) The weight is reduced to 1/30 to 1/60 of that of conventional products, and because it has flexibility, it is easy to carry, install (assemble) and disassemble (remove), and handling is dramatically improved.

(2) Excess water is released from the texture during concrete molding (water effect). Therefore, the concrete strength is developed faster and the construction period is shortened.

(3) Mortar does not adhere to the dismantled cloth formwork because it is provided with peelability.

(4) It has excellent durability and can be used repeatedly.

<Example> Below, the manufacturing method of the concrete formwork of this invention is illustrated by an Example.

Example 1 Technora (para-based amide fiber) thread (thickness # 10)
Using a vertical and horizontal direction, a woven fabric with a density of 56 threads / 25.4 mm (290 g / m ² , tensile strength vertical, horizontal 600 kg / 30 mm, elongation vertical, horizontal 5%) is a polytetrafluoroethylene solution. Immerse in 370 ° C and attach it so that the solid content is 0.5% of the fiber weight.
Was heat-treated at a high temperature.

As a result of comparing the peeling performance between the untreated woven fabric and this treated fabric with concrete, the treated fabric showed almost no mortar adhesion, and the weight increase rate of the fabric form after peeling was about 3%, whereas the untreated fabric was untreated. It was found that the increase rate when using the woven fabric was 233%, which was twice the initial weight.

The smoothness of the concrete surface is fairly smooth in the case of treated cloth.

Next, comparing with the conventional method, the weight of the conventional iron is 30
Compared with 0 kg / set, the initial weight of cloth is 5 kg / set, which is 1/58 of the weight of iron, which is a great reduction in weight. In the case of iron, the weight after use had some adhesion, but there was no adhesion on the molding surface, but in the case of cloth, the mortar adhered to the unprocessed product in large amounts and the weight increased, but it still remained at 12 kg / set. . In the case of the cloth made of polytetrafluoroethylene, the weight was 5.1 kg / set, and the weight was only slightly increased. It was found that there is almost no adhesion to the surface of the cloth, so that it can be used continuously from the next time onward, which helps improve work efficiency.

Good results were obtained with almost no deterioration in peeling performance up to 30 times of repeated use.

Claims (1)

[Claims] 1. A formwork for concrete, which is made of a high-strength organic fiber and is made of a cloth processed with one or more mold release agents selected from the group consisting of fluororesins and silicone resins. .