JPH01219259A - Crack-preventing work for concrete - Google Patents

Abstract

PURPOSE:To easily remove a heat insulator from concrete face by a method in which a heat insulator is coated through a releasing material on the surface of concrete, hardened, and allowed to stand for a given length of time. CONSTITUTION:Adhesive tapes 3 are bonded to given places of the surface 2 of concrete 1. A releasing agent 4 is coated through the tapes 3 on the surface 2 of the concrete 1 and the tapes 3 are removed, whereupon the releasing agent 4 coated on the tapes 3 is removed concurrently. A heat insulator 5 composed of rigid urethane foam, etc., is sprayed for coating onto the surface 2 of the concrete 1 through a releasing material 4, hardened, and allowed to stand for about 3 month. The heat insulator can thus be smoothly and easily removed from the surface of the concrete 1 because of the interposition of the releasing material between the heat insulator and the surface of the concrete 1.

Description

[Detailed description of the invention] (Industrial application field) The present invention provides a method for preventing cracks in concrete,
More specifically, this is a concrete crack prevention method known as the so-called insulation curing method, which uses a heat insulating material such as urethane foam to prevent cracks from forming in poured concrete with large cross-sections such as at dam construction sites. Regarding improvements.

(Prior Art) Generally, in concrete casting work where members have a large cross section, such as at a dam construction site, a large temperature difference occurs between the center of the cross section and the near surface of the poured concrete due to the influence of outside air temperature.

In addition, moisture evaporates from the part of the poured concrete that faces the outside air (therefore, there is a difference in water content between the center of the cross section and the area near the surface).

Therefore, there is a difference in the amount of thermal expansion and drying shrinkage between the center of the concrete and the area near the surface, causing cracks in the concrete and impairing the durability of the concrete.

To solve this problem, conventional methods have been to spray and paint a heat insulating material such as hard urethane foam on the concrete surface after pouring the concrete, and then leave it for a certain period of time.
As a result, a so-called heat insulation curing method has been used to prevent the occurrence of cracks due to the above-mentioned temperature differences and water content differences.

(Problems to be Solved by the Invention) However, in this construction method, although the intended purpose of preventing cracks from occurring due to differences in temperature and moisture content inside and outside the concrete can be achieved, After leaving it for so-called insulation curing, the insulation must be peeled off from the concrete surface, which is a very troublesome process, and the insulation remains on the concrete surface, causing a change in the appearance of the concrete surface. A new problem has arisen: unsightly behavior.

The present invention was made to solve new problems in the heat insulation curing method using such heat insulating materials. The purpose is to remove it from the concrete surface very easily and smoothly, leaving almost no residue behind.

(Means for Solving the Problems) The present invention has been made to solve the above-mentioned problems in order to achieve the above object, and the means for solving the problems are as follows: A heat insulating material 5 is applied via a peeling means such as a stripping agent 4, and then, after the heat insulating material 5 is cured, it is left for a predetermined period of time, and then the heat insulating material 5 is peeled off from the surface 2 of the concrete 1. The purpose is to remove the heat insulating material 5.

(Function) In other words, since the heat insulating material is applied to the concrete surface via the above-mentioned peeling means, the heat insulating material is not directly applied to the concrete surface, and therefore, the heat insulating material is not peeled off from the concrete surface afterwards. In this way, the heat insulating material does not remain on the concrete surface and can be smoothly removed by the above-mentioned peeling means.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

The example of Koushi Tsuchimoto is an example in which a release agent is used as the removal means.

First, as shown in Fig. 1, adhesive tape 3. Paste...

Next, a release agent 4 obtained by using naphtha as a solvent and mixing 5% by weight of wax is prepared, and the release agent 4 is applied to the surface of the concrete 1 through the adhesive tape 3 as shown in FIG. Apply with a brush.

Next, as shown in FIG. 3, the adhesive tape 3 is peeled off and removed from the surface 2 of the concrete 1. As a result, the adhesive tape 3 and the release agent 4 applied to the upper surface of the adhesive tape 3 are removed at the same time.

Next, a heat insulating material 5 made of hard urethane foam prepared in advance by mixing raw material liquid and fluorocarbon gas is sprayed onto the surface 2 of the concrete 1 through the stripping agent 4 using a gun using a compressor. A heat insulating material 5 is applied to the surface of the concrete 1. The thickness of the heat insulating material 5 to be coated is approximately 2 ci.

Next, after the heat insulating material 5 is cured, it is left for about 3 months. As a result, so-called heat insulation curing is performed, and the temperature difference between the center of the concrete and the area near the surface becomes small, and the accidental dispersion of moisture is prevented, thereby preventing the occurrence of cracks in the concrete 1. becomes.

Thereafter, as shown in FIG. 5, the heat insulating material 5 is peeled off from the surface of the concrete 1. In this case, since the above-mentioned stripping agent 4 is interposed between the heat insulating material 5 and the surface 2 of the concrete 10, the heat insulating material 5 is removed from the surface 2 of the concrete 1 through the stripping agent 4. It will be peeled off smoothly and easily, and the heat insulating material 5 will not remain attached, at least on the surface to be peeled off.

On the other hand, in the areas where the release agent 4 has been removed together with the adhesive tape 3 in advance, the heat insulating material 5 is in direct contact with the surface of the concrete 1, so even after the release agent 4 is removed, there is still some heat insulation. Material 5 will remain.

As mentioned above, the removal agent 4 made it possible to remove the heat insulating material 5 from the concrete surface very easily and smoothly.

Kosei soil 1 In this example, heat insulation curing and peeling of the heat insulating material are carried out using the same procedure as in Example 1 above, but with the removal agent 4.
A material having a different composition from that of Example 1 was used.

That is, in this example, naphtha was used as a solvent and 10
A product obtained by mixing % by weight of wax was used as release agent 4.

In this way, by using the release agent 4 with an increased amount of wax mixed in, the release effect was improved.

Backing... This example is an example in which a polyolefin film such as polyethylene or polypropylene was used as the peeling means.

In general, concrete surfaces at dam construction sites, etc. have surfaces where so-called pour joints are performed, so the use of the release agent 4 of Examples 1 and 2 above is inappropriate for such areas, and the use of the release agent 4 of Examples 1 and 2 above is inappropriate for such areas. Preference is given to using films.

To explain the working procedure, first, as shown in FIG. 6, double-sided tape 6 is pasted on the periphery of the surface 2 of the concrete 1 and at predetermined positions between the peripheries.

Next, a film 7 made of polyethylene or the like and having a thickness of about 0.4 m is attached to the surface of the concrete 1 via the double-sided tape 6.

Thereafter, the heat insulating material 5 is removed from the surface 2 of the concrete 1 by peeling off the heat insulating material 5 through the film 7.

In this case, since the film 7 is interposed between the heat insulating material 5 and the surface 2 of the concrete 1, the removal of the heat insulating material 5 by peeling can be performed very easily and smoothly in this embodiment as well. .

In this embodiment, since the film 7 is adhered to the entire surface 2 of the concrete 1, the heat insulating material 5 hardly remains on the surface 2 of the concrete 1.

[Actual] 11 (In this example, heat insulation curing and peeling of the heat insulating material were carried out using the same procedure as in Example 3 above, but a film 7 having a different thickness from that in Example 3 was used.

That is, in this example, the thickness is about 0.2 rma
Film 7 was used.

The thickness of this film 7 can be arbitrarily changed depending on the handling at the dam construction site.

In the above Example 1.2, the adhesive tape 3 is pasted before the release agent 4 is applied, so the adhesive tape 3
Although the heat insulating material 5 and the surface of the concrete 1 come into direct contact at the predetermined position where the adhesive tape 3 is attached, the adhesive tape 3 is not necessarily required if such direct contact is not intended. Therefore, this is not a condition in the present invention.

Furthermore, the 40 kinds of stripping agents are not limited to those in which wax is mixed with naphtha as a solvent as in the above embodiment, but any material that can strip the heat insulating material 5 may be used. .

Furthermore, as a peeling means for peeling off the heat insulating material 5,
The present invention is not limited to the release agent 4 of Examples 1 and 2 or the film 7 of Example 3.4, but any means capable of removing the heat insulating material 5 may be provided in advance on the surface of the concrete 1.

Furthermore, in each of the above embodiments, the heat insulating material 5 is
However, the means of painting is not limited to spraying, and may be applied, for example, by coating.

Further, in each of the above embodiments, hard urethane foam is used as the heat insulating material 5, but the material of the heat insulating material 5 is not limited. In short, it should be something that can be painted on a concrete surface.

Furthermore, the location where the heat insulation curing is performed is not limited to the dam construction site as in the embodiment. In short, as intended by the present invention, concrete can be used for any purpose as long as it has a large cross-section where cracks can occur due to differences in temperature and water content inside and outside the concrete.

(Effects of the Invention) As in the case of ridges, the present invention applies a heat insulating material to the concrete surface using a peeling means such as a release agent or film, leaves it for a certain period of time after the heat insulating material hardens, and then removes the heat insulating material. This method removes the insulation material by peeling it from the concrete surface, so by the peeling means interposed between the insulation material and the concrete, the insulation material can be peeled off very easily and smoothly without remaining on the concrete surface. This has resulted in the remarkable effect of removing the particles.

Furthermore, because the above-mentioned peeling means does not leave the heat insulating material carelessly on the concrete surface, the external appearance of the concrete surface is not impaired.

Furthermore, as the insulation material can be peeled off smoothly and easily as described above, the so-called insulation curing method for preventing cracking, which has traditionally been difficult to use due to the problem of peeling of the insulation material, has become possible. There is a practical benefit of being able to make effective use of.

[Brief explanation of the drawing]

FIG. 1 shows a step of attaching an adhesive tape in a method for removing heat insulating material from a concrete surface as an example, in which (a) is a plan view and (b) is a sectional view taken along the line A-A of (a). FIG. 2 is a sectional view showing the step of applying a release agent. FIG. 3 is a sectional view showing the adhesive tape peeling process. FIG. 4 is a sectional view showing the process of painting the heat insulating material. FIG. 5 is a cross-sectional view showing the process of removing the release agent. FIG. 6 shows the process of attaching double-sided tape in a heat insulating material removal method as another embodiment, in which (a) is a plan view and (b) is a sectional view taken along the line B-B. FIG. 7 is a sectional view showing the film adhesion process. FIG. 8 is a sectional view showing the process of painting the heat insulating material. FIG. 9 is a sectional view showing the step of peeling off the heat insulating material. 1... Concrete 2... Surface 4... Release agent 5... Insulating material applicant Toho Perlite Co., Ltd. agent Patent attorney Noboru Fujimoto (b) Figure 6 (b) No. 8rIA No. 9 WJ

Claims (1)

[Claims] 1. A heat insulating material 5 is applied to the surface 2 of the concrete 1 using a peeling means such as a release agent 4, and then, after the heat insulating material 5 is cured, it is left for a predetermined period of time, and then the A method for preventing the occurrence of cracks in concrete, which comprises peeling the heat insulating material 5 from the surface 2 of the concrete 1 and removing the heat insulating material 5. 2. The method for preventing cracks in concrete according to claim 1, wherein the heat insulating material 5 is made of rigid urethane foam.