JPH0652003B2 - Construction method of RC wall opening - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for constructing an RC wall opening capable of suppressing cracks occurring at corner positions of a reinforced concrete (RC) wall opening.

<Conventional technology> Cracks on the outer wall of reinforced concrete cause water leakage due to rainwater, and if this crack reaches the finishing material, it will be a major obstacle from the viewpoint of aesthetics. Therefore,
The cracks that can be known when demolding after placing concrete is 0.
For large cracks of about 2 mm to 0.3 mm, resin was injected into the cracks, and for other inconspicuous ones, mortar sealing was performed by applying a mortar-based material.

<Problems to be solved by the invention> However, the repair method of injecting resin into cracks is incomplete in effect despite the fact that it takes a lot of time for each construction, and in many cases adjoining parts often crack again, and with mortar The simple method of sealing often caused cracks to occur again at the same location.

In particular, during the temporary period immediately after the concrete is poured, the drying shrinkage is severe, and in the case of the outer wall, the temperature and humidity changes of the atmosphere also act and the initial crack grows (expands). Such a growth crack cannot be sufficiently dealt with by the conventional repair method.

The present invention has been made in view of the above circumstances, and an object thereof is to easily and inexpensively reinforce a portion where cracks are likely to occur from a concrete driving step for forming an outer wall, that is, a corner portion of a wall opening. There is a method of constructing an RC wall opening that suppresses

<< Means for Solving Problems >> In order to achieve the above object, a method for constructing an RC wall opening according to the present invention is a wall formwork, in which a corner of a dam plate surface located at a corner of the opening in advance is used. A non-corrosive high-performance fiber woven fabric is partially attached to the corner-corresponding parts with double-sided adhesive tape, and then the non-rust high-performance fiber woven fabric has good adhesion to concrete. The agent is applied, and after that, the mold is built up and concrete is poured, and the mold is demolded after the required strength is achieved.

《Action》 Temporarily fix the rust-proof high-performance fiber woven cloth on the dam plate surface with double-sided adhesive tape, and use the adhesive applied to the moisture in the fresh concrete and the rust-proof high-performance fiber woven cloth when placing concrete. Reacts. Then, as the concrete gradually hardens and the surface thereof dries, the adhesive exhibits a strong adhesive force. That is, this adhesive is a binder having concrete and an antirust high performance fiber as an adherend, and when the mold is demolded, the antirust high performance fiber is integrated into the concrete,
The formwork separates from the rustproof high performance fiber. The adhesive tape adheres to the mold or the non-rusting high-performance fiber side, and is peeled off later as appropriate.

The rust-proof high-performance fiber is completely integrated with the concrete to forcibly restrain the behavior of the concrete and suppress the growth of cracks. The rustproof high-performance fiber woven fabric used in the present invention refers to a woven fabric of carbon fiber, aramid fiber, polyethylene fiber or the like.

<Example> Hereinafter, a preferred example of the present invention will be described in detail with reference to the drawings.

First, before building the wall form 1, the carbon fiber woven fabric 3 formed in a sheet shape with a width of about 50 cm is temporarily temporarily fixed to the position corresponding to the inner opening corner of the weir slope 2 with the double-sided adhesive tape 4. .
Next, the ethylene vinyl acetate resin emulsion (EVA) as the adhesive 5 is applied to the temporarily fixed carbon fiber woven fabric 3. This has, for example, the trade name NS-Hiflex (Nippon Kasei), and a triple solution thereof may be used.

After that, the barrier plate 2 is built in a predetermined position, and the thick piece 6 is set on the outside thereof. The built-in state of the mold 1 is as shown in FIG. Although the carbon fiber woven fabric 3 is provided only on one of the dam plates 2 in the drawing, it may be provided inside each of the dam plates 2-2 facing each other. Then, when the concrete 7 is poured and cured as it is, the adhesive 5 reacts with the moisture in the fresh concrete while receiving the lateral pressure of the concrete 7, and swells and is re-hardened in combination with the hardening of the concrete 7.

At that time, since it has air permeability, it does not hinder the movement of water in the concrete, and therefore there is no fear of peeling. That is, it reacts with the water in the ready-mixed concrete after being poured into the ready-mixed concrete, and while it exerts a strong adhesive force, it naturally integrates with the concrete after the mold plate 2 is released from the mold.

When the mold 1 is released from the mold, the carbon fiber woven fabric 3 is left integrally with the wall 8 at the corners of the opening 9 of the wall 8. This is because the carbon fiber woven cloth 3 has already been firmly bound to the concrete 7 by the EV adhesive. After the mold is removed, it is more firmly integrated by drying, and the crack stress due to the drying shrinkage of the concrete 7 is transmitted to the carbon fiber woven fabric 3 to suppress and restrain the crack.

The thickness of the carbon fiber woven cloth 3 is such that the wall strength × concrete tensile strength (about 15 kg / cm ² ) / carbon fiber tensile strength (20,000 k) so that the same tensile strength as the structural concrete is obtained.
g / cm ² ).

For example, when the wall 8 has a thickness of 20 cm, the carbon fiber woven fabric 3 has a thickness of 0.15 mm. If it is attached not only to one side of the wall 8 but also to the front and back sides, a half thickness of 0,15 mm will suffice.

Therefore, even if the E / V / A adhesive 5 is applied to it, it is very thin and light, so it is possible to easily temporarily fix it to the dam plate 2 with the tape 4, and because it is thin, the concrete There is no adverse effect on the workability during placement.

The carbon fiber woven fabric 3 has a wall 8 due to the nature of the EV adhesive.
It is better to install it inside the room. When sticking to both sides of the wall 8, it is advisable to put a waterproof coating on the outer surface (outside) of the wall 8.

<Effect> As described in detail above, in the method for constructing the RC wall opening according to the present invention, the non-corrosive high-performance fiber woven fabric is temporarily fixed to the inside of the mold with an adhesive tape so that the RC wall opening is peeled off at the time of demolding. In this case, since the water-reactive one-dimensional polymer adhesive is reactively integrated with the cast concrete, the surface treatment work of the adhesive surface is not required.
Furthermore, the rust-resistant high-performance fiber woven fabric can be easily cut with scissors to any desired size, and since it has a remarkably high tensile strength, it can obtain the required strength even if it is thin, so that there is no obstacle to concrete placement. Excellent workability with no defects. In addition, since cracks are sufficiently suppressed, it is not necessary to carefully construct the reinforcing bars to be placed in the openings, and the adhesion status with concrete and the placement density can be ensured sufficiently to reduce the burden of reinforcing bar reinforcement construction. It is light and at the same time simple to reinforce with anti-corrosive high-performance fiber, which is extremely effective as it eliminates the need for subsequent crack repair work.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view showing a state in which carbon fiber woven cloth is temporarily fixed to a formwork, and FIG. 2 is an end view when concrete is placed,
FIG. 3 is a perspective view showing the wall opening after the mold is demolded. 1 ... Formwork, 2 ... Dam plate 3 ... Carbon fiber woven cloth, 4 ... Double-sided adhesive tape 5 ... Adhesive, 6 ... Edge material 7 ... Concrete, 8 ... Wall 9 ... Opening Department

Front page continuation (56) Reference JP 61-266760 (JP, A) JP 58-131270 (JP, A) JP 60-5750 (JP, A)

Claims (2)

[Claims] 1. A wall formwork, wherein a non-corrosive high-performance fiber woven fabric is partially attached to a corner-corresponding portion of a dam plate surface located at a corner of an opening in advance with a double-sided adhesive tape, and then the rust-proof. High-performance fiber woven cloth is coated with a water-reactive one-dimensional polymer adhesive with good adhesion to concrete, and after that, the formwork is installed and concrete is poured. A method for constructing an RC wall opening in which the mold is demolded after the required strength is developed. 2. The method for constructing an RC wall opening according to claim 1, wherein the adhesive is an ethylene vinyl acetate resin emulsion.