JP2000213164A - Sleeve for forming hole in concrete structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sleeve which can be easily drawn out although a considerably large strength is required on drawing out the sleeve and hence, it is difficult to draw out it, in such an actual case that a sleeve is fitted in the form when a through hole for pipes or cables is required on the concrete body and concrete is injected and the sleeve is drawn out after curing. SOLUTION: A synthetic resin film 3 having a week water-resistance and alkali-resistance is formed on the surface of a paper tube 2 to constitute a sleeve 1. Further, a water-resistant tape is wound up on the surface of the paper tube 2 in a wider pitch than the tape width or a water-resistant tape provided with appropriate holes thereon is wound up to form the sleeve through which water and moisture can slightly permeate to decrease the strength of the paper tube 2 because the tube gets wet when the concrete cures.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a concrete building such as a concrete building, in which a pipe, wiring, an air conditioning duct and the like are formed with a through hole in the concrete body in order to pass through the hole. It relates to a form to be formed, ie a sleeve (also called a void tube).

[0002]

2. Description of the Related Art Conventionally, in order to form a through hole in a concrete wall, a sleeve is fixed to a predetermined position by inserting the sleeve into a mold or holding it with a reinforcing bar, and ready-mixed concrete is poured into the mold. It is. Then, after the concrete hardens, the paper tube is pulled out to complete the through hole.

[0003] A paper tube is often used as a sleeve for forming the through-hole, but if the surface of the paper tube is not subjected to any treatment, the ready-mixed concrete is not cured until the concrete hardens. Absorbs a large amount of water and softens,
The pressure resistance is deteriorated and the hole is deformed, and a hole having a desired shape cannot be obtained. Therefore, a sleeve in which a water-resistant tape or the like is coated on the surface of a paper tube by adhesion or the like is used for the sleeve.

[0004] As described above, a sleeve having sufficient water resistance by winding a tape around a paper tube maintains its original strength even after the ready-mixed concrete dries, and the internal pressure accompanying the shrinkage of the concrete on the entire outer peripheral surface. Support. Such a sleeve is suitable for forming the desired shape, but it requires a great deal of force to pull it out of hardened concrete and is a difficult task.

[0005]

A sleeve for forming a predetermined through hole in a concrete wall is formed on a paper-like portion of the ready-mixed concrete poured into the form until the concrete loses a certain degree of hardness, that is, fluidity. It is desirable that the original and the original strength and tension are maintained without absorbing water or by absorbing a little moisture, and then the paper is softened by absorbing water. In other words, it is an object to provide the paper tube with water resistance limited to a predetermined period of time, and thereafter impart a property of being flexible through moisture or water permeability.

[0006]

As a means for solving the above-mentioned problems, the present invention provides a synthetic resin weak in chemical resistance, especially water resistance and alkali resistance, a synthetic resin containing an organic acid, a biodegradable resin, and the like. It is characterized by using a sleeve in which a coating is formed by coating the outer peripheral surface of a paper tube. In other words, the sleeve in which the surface of the paper tube is coated, laminated, or film-coated with such a synthetic resin is broken by a certain period of time due to the moisture of the cast concrete, and then the moisture is transmitted. Then, by the time the concrete is solidified, the paper quality, which is the main body of the paper tube, becomes wet and loses its original strength. As a result, it is easy to remove the hardened concrete.

[0007] That is, the invention corresponding to claim 1 is to coat or laminate a synthetic resin (plastic) on the surface of the paper tube with a sheet or by means of a sheet. The coating is deteriorated by the time the ready-mixed concrete poured into the mold is hardened, and the water-permeable or moisture-absorbing material, which is the base material of the paper tube, is imparted so that the sleeve becomes flexible. It is.

[0008] The invention corresponding to claim 2 is a synthetic resin having no resistance to alkaline components, or -OH (hydroxyl group);
The outer surface of a paper tube is coated or coated with a synthetic resin having poor water resistance to which -COOH (carboxyl group) -NH2 (amine) is bonded, a synthetic resin containing an organic acid, a biodegradable resin, or the like. By means of forming
This gives temporary water resistance to the paper base material,
After that, the paper quality of the base material is absorbed by moisture to make it soft.

According to a third aspect of the present invention, a tape such as a water-resistant kraft tape (a synthetic resin tape or a cloth tape may be used; the same applies hereinafter) is provided with a number of small holes in the surface thereof, and this is formed into a paper tube. A water-permeable sleeve is formed by means of spirally wrapping around the outer peripheral surface to cover the inner surface. Within a predetermined time, the initial strength is maintained, and thereafter, the paper tube is wet and the strength is reduced. It is to try to make it stretch.

According to a fourth aspect of the present invention, when a water-resistant kraft tape is spirally wound around the outer periphery of a paper tube to form a water-resistant paper tube, the helical pitch for coating the tape is smaller than the width of the tape. The sleeve was made slightly larger to form a gap between the wound tapes to limit the amount of water absorbed by the sleeve within a required time, thereby maintaining the strength of the sleeve and thereafter moistening.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The sleeve according to the present invention is, as described above, coated with synthetic resin directly on the surface of a paper tube that has not been subjected to surface treatment for imparting water resistance or tape coating, laminating or winding a film. (Hereinafter, these are collectively referred to as coatings.) A coating is formed, and the coating is intended to have water resistance only for a predetermined time. Here,
It is natural that the film is wound around the film, and the film is wound, and the film is formed into a tube, a paper tube is inserted into the film, and the film is thermally shrunk to adhere to the paper tube. Don't ask.

In general, synthetic resins other than polytetrafluoroethylene, polypropylene and polyethylene have a polar group (excluding halogen groups -Cl and -F). well known. Typical examples are vinyl chloride resin, ABS resin, acrylic resin, vinylidene chloride resin, poamide, polycarbonate,
Polyacetal, acetylcellulose resin, urethane resin, phenol resin, epoxy resin, unsaturated polyester resin, biodegradable resin, etc., have high hygroscopicity. In particular, polyvinyl alcohol, methylcellulose, carboxymethylcellulose and the like are mentioned as synthetic resins having low water resistance.

The synthetic resins having low alkali resistance include soft vinyl chloride resins, vinylidene chloride resins, polyamides, acrylic resins, polycarbonates, thermoplastic polyester resins, acetyl cellulose resins, urethane resins, and the like.
There are phenolic resin, epoxy resin and the like, which can be used together with the water-absorbing resin as a coating of the sleeve for forming holes in the concrete of the present invention.

Of the above resins, those whose purpose is to be used as an adhesive or that which is to be used as a paint can of course be used as a synthetic resin for forming a film on the present sleeve.

A sleeve according to the present invention will be described with reference to the drawings. FIG. 1 shows a sleeve 1 having a paper tube 2 as a base material and a coating film 3 of a synthetic resin formed on the surface thereof. A commercially available void tube can be used as the paper tube 2 as a base material of the sleeve 1. As for the void tube whose surface is coated with a water-resistant tape, a moisture penetration hole described later is formed and used. The use of a void pipe that has not been subjected to a water-resistant treatment corresponds to the first aspect of the present invention. That is, the outer peripheral surface of the paper tube is coated with the synthetic resin to form the coating 3.

The thickness of the coating 3 formed by coating the paper tube with a synthetic resin depends on the above-mentioned properties such as alkali resistance, water resistance, water absorption and biodegradability. In this case, the extremely thin film is permeable to moisture or water by being attacked by the strong alkali component of the concrete.

Cement, which is a main component of concrete, is a strongly alkaline substance containing about 65% of calcium oxide and about 20% of silicon dioxide. Therefore,
If a resin having a weak alkali resistance is used as the resin to be coated on the paper tube, the resin is decomposed or dissolved at an early stage due to the alkali component coming out of the concrete, and the water resistance cannot be maintained. The thickness may be relatively thick.

FIG. 2 shows a sleeve 1 in which a coating 3 of 1 μm to 500 μm is formed on a paper tube with a vinyl chloride resin, a vinylidene chloride resin and a polyamide, respectively.
When a commercially available ready-mixed concrete was poured into the molds 4 and 4 as shown in Fig. 4, the paper tube was wet a few hours later. The bonded portion was separated and could be taken out in a belt shape. The hole formed in the concrete was circular and there was no so-called shape change. In the example, the thickness of the coating was set to 500 μm or less, but a thicker film was wound around the film.
If a thin portion is partially formed, a similar water-permeable effect can be obtained.

When the sleeve is pulled out 5 days after casting under the above-mentioned conditions, the sleeve 1 has the same shape as the above, and the sleeve 1 has a cylindrical shape.
There was kind. In the case where the paper tube came off in a cylindrical shape, the paper tube itself was slightly flexible, and its outer diameter lost its original strength, so that it could be pulled out with a relatively small force.
From the above, the sleeve 1 maintains the required strength within several hours to 10 hours, which is the hardening time of the concrete, and then makes the paper core 2 flexible by moisture or water permeation from the coating 3. Has been demonstrated.

Polyvinyl alcohol is used as a relatively water-absorbing synthetic resin to form 50 to 200 on the paper tube surface.
The sleeve with the micron millimeter coating was inserted into the same formwork as above, and ready-mixed concrete was cast.Similar to the case of the above-mentioned alkali-resistant weak synthetic resin, the sleeve absorbed moisture and had its original strength. It was easy to pull out from the lost and hardened concrete.

Further, using a polylactic acid resin (trade name: Lacia, manufactured by Mitsui Chemicals, Inc.) as a biodegradable resin,
A film of 20 μm mm was formed on the surface of the paper tube, and the same test as above was performed. Such a biodegradable resin is weak in water resistance, and becomes relatively permeable to water in a film of this thickness relatively early.
The strength retention during the concrete solidification time was also sufficient.

In an embodiment corresponding to claim 3, a commercially available adhesive kraft tape 3 coated with a water-resistant resin is used.
(Synthetic resin or cloth tape may be used. The same applies to the following.) A hole 3a having a diameter of 1 mm to several mm was formed through the hole 3a at an appropriate density, and the hole 3a was wound around a paper tube 2 and bonded to obtain a sleeve 1 for concrete hole formation.

This sleeve 1 is mounted on the above-mentioned casting frame,
When commercially available concrete C was cast, naturally, water was gradually absorbed into the paper tube through the hole 3a from the initial stage of casting, but if the diameter of the hole 3a was as described above, the compressive strength was maintained until the fluidity of the concrete was lost. Hold and form the desired concrete holes. During curing, the sleeve 1 lost its original tension and strength and could be easily removed.

As an embodiment of the invention corresponding to claim 4, a commercially available adhesive kraft tape 3 in which the surface of a paper tube 2 is coated with a water-resistant resin is formed at a pitch 1 mm to 5 mm larger than the width of the tape. It is wrapped around and made into a sleeve. Accordingly, a spiral water-absorbing groove 3b having a width of 1 to 5 mm is formed on the surface of the sleeve, and the bottom surface of the groove exposes a paper portion on the surface of the paper tube 2 as a base material.

When this was mounted in concrete molding frames 4 and 4 and commercially available concrete C was cast, the water of the concrete impregnated into the paper tube 2 through the water absorbing groove 3b, As before, the sleeve 1 lost its original tension and could be easily removed. The hole formed in the concrete wall was circular and did not deform.

[0026]

According to the present invention, the sleeve as a concrete material is poured on the outer surface of the paper tube because the outer surface of the paper tube is coated with a synthetic resin or a hygroscopic or water-absorbent resin which is weak against alkali components. The paper tube absorbs or absorbs moisture, and then loses its original strength, tension by drying, so that the concrete retains water resistance during the time it hardens to a certain degree of hardness and then becomes water permeable. The sleeve can be easily removed from the hardened concrete.

Further, when the paper tube is taken out early, the spirally bonded portion of the paper tube comes off and becomes strip-shaped and is taken out. It has also become possible to work by women.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a first embodiment of a sleeve according to the present invention.

FIG. 2 is a perspective view showing a second embodiment of the sleeve.

FIG. 3 is a perspective view showing a sleeve according to a third embodiment.

FIG. 4 is a side sectional view showing a state in which a sleeve is mounted on a mold.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sleeve 2 Paper core 3 Coating 4 Formwork

Claims (4)

[Claims] 1. A sleeve for forming a hole in concrete, wherein the outer peripheral surface of a paper tube is coated or covered with a synthetic resin. 2. A coating or coating on the outer peripheral surface of a paper tube.
2. A sleeve for forming a hole in concrete according to claim 1, wherein the synthetic resin to be coated is a synthetic resin which is weak against moisture or alkaline components, or a synthetic resin containing an organic acid. 3. A concrete hole forming sleeve characterized in that the outer peripheral surface of a paper tube is covered with a water-resistant tape having a large number of small holes. 4. A concrete hole forming sleeve characterized in that the outer peripheral surface of a paper tube is spirally wound with a water-resistant tape and covered at a pitch larger than the tape width.