JPH1036708A - Coating composition for surface water-repellent concrete, mold using the coating composition, and method of molding concrete molding using the mold - Google Patents

Abstract

(57) [Summary] [Problem] At the time of concrete placement and demolding, the water repellent has penetrated into the concrete surface, and the surface protection treatment has already been completed. Provided are a paint composition for surface water-repellent concrete, a mold for molding surface water-repellent concrete, and a method for molding a concrete molded product using the mold. A coating composition comprising at least a binder, a water repellent, and a liquid medium, wherein a dry film of the binder has a property of being stable in an acidic and neutral atmosphere and easily dissolving in an alkaline atmosphere. A coating composition for surface water-repellent concrete, a mold for molding surface water-repellent concrete having the coating composition applied to the inner surface thereof, and a method for molding a surface water-repellent concrete molding using the mold.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paint composition for surface water-repellent concrete, which is used when a concrete molding is molded by casting concrete in a mold, curing the concrete for a certain period of time, and removing the concrete from the mold. TECHNICAL FIELD The present invention relates to a mold for molding a surface water-repellent concrete, and a method for molding a concrete molded product using the mold.

[0002]

2. Description of the Related Art Concrete molded products (hereinafter, may be simply referred to as "concrete") have been used in many buildings as structural materials having excellent strength and durability. Degradation of concrete due to acid rain has become a major problem, and as a countermeasure, concrete surface protection treatment has been performed. Conventionally, as a method of protecting the surface of the concrete without coloring it, a silicone-based water repellent or a silane-based water repellent is applied to the surface after the concrete is hardened, or similarly, the concrete is hardened and then transparent. It is common practice to apply a clear resin clear paint.

[0003]

However, in the method of applying these materials after the concrete has hardened, in order to dry the water inside the concrete, it is necessary to remove the concrete from the mold before applying the water repellent or the like. In addition, it is necessary to secure a curing period (about one week to one month), and this process becomes very long, causing a long construction period, and it is difficult for the civil engineering and construction industry to rationalize this point. Had become something.

[0004] Accordingly, an object of the present invention is to provide a water repellent agent that has permeated the surface of concrete at the time of concrete placement and demolding, and the surface protection treatment has already been completed. An object of the present invention is to provide a transferable paint composition for surface water-repellent concrete, a mold for molding surface water-repellent concrete, and a method for molding a concrete molded product using the mold.

[0005]

The above object is achieved by the present invention described below. That is, the present invention is a coating composition comprising at least a binder, a water repellent, and a liquid medium,
A coating composition for surface water-repellent concrete, characterized in that the dry coating of the binder is stable in acidic and neutral atmospheres, and has the property of easily dissolving in an alkaline atmosphere, and the coating composition was applied to the surface. A mold for molding a surface water-repellent concrete, and a method for molding a surface water-repellent concrete molding using the mold.

In the molding method using a concrete mold, when the concrete is poured into the mold, a water repellent which is previously stable on an acidic and neutral atmosphere and easily dissolved in an alkaline atmosphere is applied to the surface of the mold. A concrete molded product having a water-repellent surface can be easily provided by forming an agent-containing coating layer, placing concrete in the formwork, curing, and removing the mold.

[0007]

Next, the present invention will be described in more detail with reference to preferred embodiments. The binder used in the coating composition of the present invention may be any as long as the dried coating film obtained thereby is stable in acidic and neutral atmospheres, and has a property of easily dissolving in water in an alkaline atmosphere. And vinyl acetate-based, acrylic-based, and polyester-based resin emulsions or water-soluble resins, and mixtures thereof. Here, acidic means about 5 or less in terms of pH, similarly, alkaline means about 9 or more, and neutral means an intermediate level.

As the water repellent used in the coating composition of the present invention, any of a silicone type, a fatty acid type and a wax type can be used as long as they are in the form of a solution or emulsion.
Those having alkali resistance and good affinity for cement are suitable.

The coating composition of the present invention is prepared by dissolving or dispersing and mixing the above-mentioned binder and water repellent in a liquid medium. As the liquid medium used in the coating composition of the present invention, water,
A water-soluble organic solvent or a mixture thereof, which does not affect the liquidity of the solution, is preferable. Examples of such a water-soluble organic solvent include butyl cellosolve, carbitol, ethylene glycol, polyethylene glycol and the like. When a water-soluble organic solvent is used by mixing with water, the ratio of the water-soluble organic solvent is preferably about 10 to 50 parts by weight with respect to 100 parts by weight of water.

The proportion of each component in the coating composition of the present invention ranges from 20 to 70 parts by weight of a binder, 5 to 30 parts by weight of a water repellent, and 70 to 0 parts by weight of a liquid medium. 55 parts by weight, 10 to 20 parts by weight of a water repellent, and 55 to 25 parts by weight of a liquid medium.

When the amount of the binder is less than 20 parts by weight, the strength of the resulting coating film is not sufficient, which is not preferable. On the other hand, when the amount of the binder exceeds 70 parts by weight, the viscosity of the coating becomes too high, and It is not preferable because the property deteriorates.
When the content of the water repellent is less than 5 parts by weight, the water repellency of the obtained concrete surface is not sufficient.
Even if the amount exceeds 0 parts by weight, the water repellency of the concrete surface is not further improved.

[0012] The coating composition of the present invention may further contain various additives as required. Examples of the additives that can be added to the coating composition of the present invention include an antifoaming agent, a thickener, a preservative, a fungicide, and a surfactant.

The method for applying the coating composition of the present invention includes:
Any method, such as a spray method, a brush coating method, and a dipping method, may be used as long as a constant film thickness can be ensured. After applying the coating composition of the present invention, the coating composition is sufficiently dried until a coating layer is formed. As a method for drying, it is preferable to use natural drying, but it is also possible to perform hot-air drying that does not affect the binder and the water repellent. The drying time is appropriately set depending on the types and blending ratios of the binder, the water repellent and the liquid medium, the presence or absence of additives, the drying method, and the like.

The thickness of the coating film obtained from the coating composition of the present invention varies depending on the type of the binder and the water repellent, the desired degree of water repellency, and the like.
It is preferably about μm. The coating film thus obtained has water repellency, is stable in an acidic and neutral atmosphere, and has a property of dissolving in an alkaline atmosphere.

When the coating composition of the present invention as described above is applied to the surface of a mold to be used for molding a concrete molded product, a water-repellent agent-containing coating layer is formed, and concrete is poured into the mold. The water-soluble substance in the concrete milk creates an alkaline atmosphere, dissolves the water-repellent-containing coating layer, penetrates the water-repellent component into the uncured concrete surface, and repels the cured concrete molding surface. Water-based.

After the concrete is cast, it is cured for a certain period,
By removing the form after the concrete hardens,
A concrete molding is molded. At this time, the coating film of the coating composition of the present invention can be expected to have an effect of preventing the form from sticking to the concrete and improving the releasability of the cured concrete from the form. Accordingly, the step of applying a release agent to the surface of the mold, which has been conventionally performed to prevent the concrete from sticking, can be omitted. The curing period is a period required for the concrete to become a certain mass and to be sufficiently hardened to withstand use as a structure, and varies depending on the type and the mixing ratio of the concrete. As the form material used in the present invention, any form material such as wood, metal, plastic, rubber or concrete can be used.

[0017]

Next, the present invention will be described more specifically with reference to examples and comparative examples. In the following description, “parts” are based on weight unless otherwise specified. Example 1 (Blending of coating composition) Vinyl acetate emulsion (solid content 50%) 40.0 parts Antifoaming agent 0.2 parts Thickener 0.5 parts Silicone water repellent 10.0 parts Water 45 to 45 50.0 parts The coating composition of the present invention having the above composition was applied to the surface of a styrofoam mold by spraying so as to have a coating thickness of about 100 μm, and air-dried for 18 hours. (Mixing of concrete milk) Portland cement 20.0 parts Silica sand 60.0 parts Aggregate 60.0 parts Water reducing agent 0.2 parts Water 10-20.0 parts Concrete of the above-mentioned composition is added to the formwork on which the coating film is formed. After curing at room temperature for 3 days, the mold was removed to obtain a concrete molded product. The resulting concrete exhibited good water repellency and the surface was dull and similar to the surface of regular concrete.

[0018] The same styrofoam mold and Comparative Example 1 Example 1 was Da設concrete without forming a coating layer, after curing at ambient temperature for 3 days remove the formwork. The concrete was air-dried for about 2 weeks until the surface moisture content became 10% or less, further sprayed with a silicone-based water repellent on the surface, and dried for 1 day to obtain a concrete molded product. The obtained concrete molded product had good water repellency, but remained sticky on the surface and had a glossy appearance.

[0019]

Since the coating film formed from the coating composition of the present invention is essentially completely dissolved by the alkaline substance in the concrete milk, the surface layer after hardening of the concrete is a so-called "polymer-cement mixed concrete". A layer is formed, so that not only the strength is much improved as compared to a normal concrete surface, but also the occurrence of efflorescence due to exposure can be suppressed. Further, since the coating film obtained by the coating composition of the present invention does not dissolve in an acidic and / or neutral atmosphere, the coating film applied to the formwork is not washed away by rain during outdoor construction. . Furthermore, in a normal water repellent treatment method of applying a water repellent to a concrete molding, a curing period of about one week to one month is required after the concrete form is removed and before the water repellent is applied. However, in the method using the mold coated with the coating composition of the present invention, since the water repellent treatment of the concrete surface is completed at the time of removing the mold, it is possible to significantly shorten the construction period. is there.

Claims (3)

[Claims] 1. A coating composition comprising at least a binder, a water repellent, and a liquid medium, wherein a dry film of the binder is stable in an acidic or neutral atmosphere and easily dissolved in an alkaline atmosphere. A coating composition for surface water-repellent concrete, comprising: 2. A mold for molding water-repellent concrete having a surface coated with the coating composition according to claim 1. 3. A method for molding a concrete molded product by placing concrete in a mold and curing it for a certain period of time, and then removing the mold, wherein the mold is the mold according to claim 2. A method for molding a concrete molded product, characterized in that: