JP2003048790A - Concrete surface coating method and section repair method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a primer which enhances the strength of adhesion between a concrete surface and a construction material and the durability in coating the concrete surface with a resin or repairing its section. SOLUTION: The primer of a silane-siloxane system consisting of an alkoxysilane and polyorgano-siloxane as essential components and containing these effective components at >=60 wt.% in total in an aqueous medium is used as the primer of the surface coating construction method and section repairing construction method for the concrete.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a concrete surface coating method and a cross-section restoration method using a specific undercoating agent.

[0002]

2. Description of the Related Art In recent years, deterioration of concrete structures has become a problem, and various means have been adopted for the purpose of extending the life of structures during new construction and repair work. Among them, the surface coating method for forming a resin-based material coating on the concrete surface, and for deteriorated concrete, the deteriorated part of the concrete is removed and repaired materials such as mortar and polymer cement mortar are loaded into the part. A cross-section restoration method for restoration is generally adopted.

In both of the surface coating method and the cross-section restoration method, an undercoat (primer) made of an epoxy resin, a silane compound or the like is applied to the concrete surface in advance at the time of construction.

The main purpose of applying the undercoat is to strengthen the existing concrete surface and to improve the adhesive strength of the construction material.
When using a silane-based compound undercoat, it is said that the water-repellent property also has an effect of preventing the phenomenon that water accumulates between the existing concrete and the construction material. The silane compound-based undercoating agent that has been conventionally applied to the surface coating method and the cross-section restoration method is the same as the one marketed as “silane-based water repellent”.

When a silane water repellent is applied to give water repellency to concrete, it is usually necessary to apply it about three times. The main reason is that the silane water repellent component is composed of 5 to 7% by weight of silane molecules, which are silicone monomolecules, and an organic solvent, and the silane monomolecules have good penetrability into concrete. On the other hand, it is unavoidable that some silane molecules are volatilized along with the organic solvent during coating, and several repeated coatings are required to form a high-density water-repellent layer. However, in the case of an undercoating method such as a surface coating method in which it is not always necessary to form a high-density water-repellent layer, it is usual to store it in a single application due to the limitation of the construction period and cost.

As an example of applying a silane-based water repellent to an undercoat on a concrete surface, for example, JP-A-63-
There are those described in Japanese Patent Publication No. 69779, Japanese Patent Publication No. 4-68274, Japanese Patent Laid-Open No. 4-300961 and Japanese Patent Laid-Open No. 9-189030.

On the other hand, as a material which does not cause volatilization, a water repellent having a high molecular weight siloxane as a main component has been proposed.
For example, Japanese Patent Publication No. 4-68274 cited above exemplifies the application of a siloxane compound to the undercoat of concrete.

[0008]

According to the conventional way of thinking, the durability of the concrete surface when the surface coating method or the cross-section restoration method is adopted is higher than that of the base coating material, that is, the surface coating method of the base coating material. Coating materials such as epoxy resin and acrylic resin to be applied to the surface, and cross-section restoration materials such as cement-based mortar or polymer cement mortar in the cross-section restoration method (these coating materials and cross-section restoration materials are collectively referred to as "construction materials").
I'm looking forward to). Therefore, when the silane-based compound is applied to the undercoat, it is usually applied only once. Therefore, if the construction material cracks or deteriorates due to some cause, the undercoat layer cannot exert the function of maintaining the durability of the existing concrete, and deterioration factors such as chloride ions and water cannot be maintained. There is a problem that the concrete structure deteriorates again in an early stage once it has penetrated into the concrete.

In order to avoid this, it is conceivable to apply a silane-based water repellent overcoating. However, since this water repellent has a low viscosity in addition to the scattering of the silane compound, scattering and liquid sagging are likely to occur. Since it is not possible to apply the coating, it is not preferable to repeat the application of the thin coating and the drying because the construction period is extended and the cost is increased.

On the other hand, a water-repellent agent having a high molecular weight siloxane as a main component can form a high-density coating film, but since it hardly penetrates into concrete, a high-density coating film is formed only on the surface layer portion. As a result, there is a problem that sufficient adhesion strength to concrete cannot be obtained, and the undercoat layer may cause peeling or cracking of the construction material.

Therefore, the present invention relates to a silane water repellent,
A water-repellent undercoat layer that solves the above problems of siloxane-based water repellents and can exhibit sufficient durability and adhesive strength even in a single application as an undercoat (primer) for a surface coating method or a cross-section restoration method. Is intended to form.

[0012]

According to the present invention, in a concrete surface coating method for forming a coating film of a coating material such as a resin-based material on a concrete surface, an undercoating agent is applied. A silane / siloxane-based undercoating agent comprising an alkylalkoxysilane and a polyorganosiloxane as active ingredients and containing these active ingredients in a total amount of 60% by weight or more, preferably 75% by weight or more in an aqueous medium. A method for coating a concrete surface is provided.

Further, according to the present invention, the deteriorated portion of the existing concrete is removed, a primer is applied to the removed concrete surface portion, and then a cross-section restoration material such as cement-based mortar or polymer cement mortar is loaded. In the cross-section restoration method of concrete that restores deteriorated parts,
As the undercoat, an alkylalkoxysilane and a polyorganosiloxane are used as active ingredients, and these active ingredients are contained in an aqueous medium in a total amount of 60% by weight or more, preferably 7% or more.
A cross-section restoration method for concrete is provided, which comprises using a silane / siloxane-based undercoating agent containing 5% by weight or more.

In any case, the silane / siloxane water repellent is contained in the aqueous medium at a weight ratio of alkylalkoxysilane: polyorganosiloxane of 2: 1 to 10: 1. Is preferred, this silane
It is preferable to form the primer layer with one coating of the siloxane-based water repellent.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention provides a silane-siloxane compound in which a silane compound having a property of easily permeating but volatilizing and a siloxane compound having a property of hardly volatilizing but hardly permeating are advantageously combined. It is characterized in that an undercoat layer was formed by using the concrete surface coating method or section restoration method.

The silane / siloxane-based primer according to the present invention is an alkylalkoxysilane represented by the general formula _, R-Si- (OR ') (where R is an alkyl group having 1 to 15 carbon atoms,
R ′ represents an alkoxy group having 1 to 6 carbon atoms) and: a polyorganosiloxane represented by the general formula, R ¹ _a R ² _b R ³ _c SiO _{(4-abc) / 2} (R ¹ is a methyl group, R ² represents an aminoalkyl group, R ³ represents a hydroxyl group or an alkoxy group, and 0 <a
+ B + c <3) and: are used as active ingredients, and these active ingredients are contained in the aqueous medium in an amount of 60% by weight or more, preferably 75% by weight or more. In this case, the weight ratio of alkylalkoxysilane to polyorganosiloxane should preferably be 2: 1 to 10: 1. Further, the silane / siloxane based primer can contain a small amount of a surfactant.

FIG. 1 schematically shows the characteristics of the silane / siloxane based primer according to the present invention. Conventionally marketed silane-based water repellents are active ingredients (silane) in organic solvents.
Is contained in only about 7 to 8% and easily penetrates into concrete, but volatilizes easily, so that a single coating can form only a low-density water-repellent layer as shown in FIG. 1 (a). . In addition, conventional siloxane-based water repellents are polymeric and viscous, and almost no volatile components are present, making it difficult to volatilize.
Hard to penetrate into concrete. Therefore, as shown in FIG. 1B, the water-repellent layer is formed only on the very surface portion, and is easily peeled off and is easily affected by frost damage. On the other hand, the silane / siloxane-based undercoating agent of the present invention can express only the advantages that the former two have, and as shown in FIG. Since it covers, the silane molecules are less likely to volatilize, and the silane molecules are more likely to permeate into the concrete, so that the silane molecules are less likely to volatilize and more easily permeate. As a result, a sufficiently dense undercoat layer is formed even after one application.

Unlike the silane-based water repellent, the silane / siloxane-based undercoat used in the present invention does not use an organic solvent and uses water as a medium. And after application,
The water in this medium and the water in the concrete react with the alkylalkoxysilane, and while releasing alcohol, three-dimensionally crosslinks into the silicone resin that is chemically fixed to the concrete, forming a strong impregnated coating film. . This silane-siloxane base coat contains 6 active ingredients.
The amount is 0% by weight, preferably 75% by weight or more, and more preferably about 80% by weight. Since it is not volatile and scattering and liquid dripping hardly occur, a sufficient coating amount can be secured even with one coating.

In order to apply the silane / siloxane-based undercoating agent of the present invention to a concrete surface, air spray (airless gun) or roller application may be performed after cleaning the surface or removing deteriorated concrete. At that time, it is better that the concrete surface to be applied is as dry as possible, and the amount of one application is 150 g / m ² or more and 300 g / m ² or less, preferably 180 g / m ² or more and 250 g / m ² or less. Even if the coating amount is applied once, no sagging occurs. Since this primer does not contain volatile organic solvents, it is treated as a non-hazardous material and does not pollute the surrounding air, so workability is also good in this respect. After the application, a curing period of about 1 day is set, and in the case of the surface coating method, putty is applied and then a coating material such as a resin material is applied as an intermediate coating and a top coating. In the case of the cross-section coating method as well, a curing period of about one day is similarly set, and then a restoration material is loaded thereon.

[0020]

【Example】

Example 1 The same existing concrete material (mortar board) was coated with a commercially available silane-based water repellent agent or a silane / siloxane-based primer according to the present invention as an undercoat, and then an epoxy resin-based surface The coating material was applied and the adhesion strength of the surface coating material was measured under the same conditions.

As the silane-based water repellent, commercially available trade name Spanguard (Density: 0.84 g / cm ² ) manufactured by Shobond Construction Co., Ltd. was used. The silane / siloxane basecoating agent contains alkylalkoxysilane and polyorganosiloxane as active ingredients, and these active ingredients are contained in water in a total amount of 80% by weight, and the weight ratio of alkylalkoxysilane to polyorganosiloxane is 7: 1. What was contained in water in the ratio of was used. Most of the rest of the active ingredient in this primer is water, but a small amount of emulsifier was added.
The density is 0.9 g / cm ² .

When applying a primer (primer), a silane-based water repellent is applied in an amount of about 0.3 k in three coats.
g / m ^2, and in the case of a silane / siloxane based primer, the coating amount was about 0.2 kg / m ² in one coating. The adhesion strength of surface coating materials is measured by the adhesion strength test method for surface coating materials (JSCE
-K531). In the test, the adhesion strength of the surface coating material when the primer coating with the silane-based water repellent or the silane-siloxane base coating agent was performed was compared with the adhesion strength of the surface coating material without the primer coating (primer) treatment. The average value from the round test was evaluated. The measurement results are shown in Table 1.

[0024]

[Table 1]

From the results shown in Table 1, when the primer treatment was performed using the silane / siloxane based primer of the present invention, 1
It can be seen that even with double coating, better adhesion strength can be exhibited than with a silane-based water repellent coated three times.

Example 2 Example 1 was repeated except that SBR polymer cement mortar as a cross-section restoration material was placed on the existing concrete (mortar board) in place of the epoxy resin surface coating. Material Industry Association Standard (N
SK standard) NSKS-001 Polymer cement mortar for base preparation "5.12 The adhesive strength of the cross-section restoration material was measured according to the adhesive strength test. The results are shown in Table 2.

[0027]

[Table 2]

From the results shown in Table 2, the silane-based water repellent does not contribute to the improvement of the adhesion strength to the cross-section restoration material, whereas the silane-siloxane based undercoating agent of the present invention has the effect of significantly increasing the adhesion strength of the cross-section restoration material. It turns out that

Example 3 A 40 × 40 × 160 mm hardened mortar specimen (W / C = 65%) was coated with an undercoating agent and immersed in water, and the weight change before and after the immersion was measured to determine the water absorption. The water absorption test was carried out. The same primer as in Example 1 was used. The silane-based water repellent was applied once and the silane-siloxane based primer was applied once. The test results are shown in FIG. The water absorption test was carried out after curing in air for 14 days after applying the base coat. Fig. 2 shows the relationship between the immersion time in water and the water absorption rate of mortar specimens coated with a primer.
It can be seen that the single-coating primer of the silane / siloxane-based undercoating agent of the present invention exhibits a water-repellent performance equivalent to that of the silane-based water-repellent agent (described as a conventional water-repellent agent in the figure) three times.

Example 4 A mortar sample of φ100 × h50 mm was coated once with the same silane / siloxane base coat as in Example 1 and then cured in air for 14 days to obtain AASHTO T-2.
The permeation amount of chloride ion was evaluated according to the rapid chloride ion permeation test described in 77. The results are shown in Fig. 3. From the results of FIG. 3, it can be seen that the primer of the silane / siloxane basecoating material according to the present invention has a function of preventing permeation of chloride ions.

[0031]

As described above, according to the present invention,
As a primer used in the concrete surface coating method or cross-section restoration method, a silane-siloxane based primer that has a water-repellent function and can increase the adhesive strength with the construction material, and also blocks chloride ion penetration Since it is used, water is prevented from collecting at the interface between the concrete and the construction material, and peeling of the construction material is prevented,
Highly durable surface coating and cross-section restoration are possible. Moreover, since the primer application is sufficiently effective in one application, the workability is also good.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing characteristics of a silane / siloxane-based undercoating agent according to the present invention in comparison with a silane-based water repellent and a siloxane-based water repellent.

FIG. 2 is a diagram showing a water absorption effect when a silane / siloxane based primer according to the present invention is used as a primer in comparison with a silane based water repellent.

FIG. 3 is a diagram showing a chloride ion blocking effect when the silane / siloxane based primer according to the present invention is used as a primer.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C09D 183/04 C09D 183/04 E04G 23/02 E04G 23/02 A (72) Inventor Takenori Hiraishi Tokyo Metropolitan Port Kugen Akasaka 1-2-7 Kashima Construction Co., Ltd. F term (reference) 2E176 AA01 BB04 4D075 AE03 CA13 CA36 CA42 DA06 DA27 DB12 DC05 EA06 EA41 EB04 EB12 EB14 EB22 EB33 EB43 EB01 EB00B52AH06B52AH06B02AH06B02AH06BA02 JB06B 4G028 CA01 CB08 CD02 4J038 DL021 DL031 MA08 NA07 NA12 PA11 PB12 PC04

Claims (6)

[Claims] 1. A method for coating a surface of concrete, which comprises applying a primer to a concrete surface and then forming a coating film on the concrete, wherein the primer is an alkylalkoxysilane and a polyorganosiloxane as active ingredients, and these are effective. A method for coating a surface of concrete, characterized by using a silane / siloxane based primer containing a total of 60% by weight or more of components in an aqueous medium. 2. The method for coating a surface of concrete according to claim 1, wherein the undercoating agent contains an alkylalkoxysilane and a polyorganosiloxane in a weight ratio of 2: 1 to 10: 1 in the aqueous medium. 3. The surface coating method for concrete according to claim 1 or 2, wherein the undercoat layer is formed by a single coating of the silane / siloxane based undercoating agent. 4. Removing the deteriorated part of the existing concrete,
In the cross-section restoration method of concrete, in which a primer is applied to the removed concrete surface portion and then a cross-section restoration material is loaded to restore the deteriorated portion,
A method for restoring cross-section of concrete, which comprises using a silane / siloxane-based undercoating agent containing alkylalkoxysilane and polyorganosiloxane as active ingredients and containing these active ingredients in a total amount of 60% by weight or more in an aqueous medium. 5. The method for restoring the cross section of concrete according to claim 4, wherein the undercoating agent contains an alkylalkoxysilane and a polyorganosiloxane in a weight ratio of 2: 1 to 10: 1 in the aqueous medium. 6. The method for restoring the cross section of concrete according to claim 4 or 5, wherein the undercoat layer is formed by a single coating of the silane / siloxane based undercoating agent.