JP7523296B2 - Method for reinforcing and finishing concrete substrate - Google Patents

Description

The present invention relates to a novel concrete surface strengthening agent.

Concrete structures have traditionally been used in many areas, including bridges, tunnels, elevated roads, and buildings. However, concrete structures tend to deteriorate over time due to salt damage, neutralization, frost damage, and other factors, resulting in problems such as cracks and peeling of concrete pieces. For this reason, many methods have been proposed for repairing and reinforcing concrete structures.

For example, Japanese Patent Laid-Open Publication No. 2002-179479 (Patent Document 1) discloses the infiltration of an alkali metal silicate such as water glass.
However, in the method disclosed in Patent Document 1, there are cases where the alkali metal silicate cannot penetrate to the inside of the concrete structure.

JP 2002-179479 A

The present invention was made in consideration of the above-mentioned circumstances, and aims to obtain a concrete surface strengthening agent that can sufficiently impregnate alkali metal silicate into concrete structures.

As a result of intensive research into the problems of the prior art as described above, the inventors came up with the idea of a concrete surface strengthening agent that contains at least an alkali metal silicate, a water-soluble silane compound, and water, and completed the present invention.

That is, the present invention has the following features.
1. A reinforcing agent containing a water-soluble calcium salt and a water-soluble silane compound is applied to a concrete substrate, and then
A concrete surface strengthening agent containing at least an alkali metal silicate, a water-soluble silane compound, and water is applied.
2. The method for reinforcing a concrete substrate according to 1., characterized in that the water-soluble silane compound in the concrete surface reinforcing agent contains an amino group-containing silane compound. 3. The method for reinforcing a concrete substrate according to 1., characterized in that the water-soluble silane compound in the reinforcing agent contains an amino group-containing silane compound .
4. A method for finishing a concrete substrate, comprising applying the concrete surface reinforcing agent according to the method for reinforcing a concrete substrate described in 1. , and then applying a topcoat material.

According to the present invention, it is possible to further increase the permeability of alkali metal silicate into concrete structures, repair deterioration of concrete structures, and increase surface strength.

The following describes how to implement the present invention.

(Concrete surface strengthening agent)
The present invention relates to a surface strengthening agent for application to concrete structures, which is capable of repairing the deteriorated parts and increasing the surface strength by applying the agent to concrete structures, particularly deteriorated concrete structures, and penetrating (impregnating) the interior of the concrete structure with an alkali metal silicate to form a hardened body. Such a concrete surface strengthening agent (hereinafter also simply referred to as "surface strengthening agent") is characterized by containing (A) an alkali metal silicate, (B) a water-soluble silane compound, and water.

Concrete structures include, for example, bridges, tunnels, elevated roads, buildings, and the like, which are made of cement, mortar, and the like, and may be either new or existing. The composition of the present invention is suitable for existing concrete structures, particularly deteriorated concrete structures that have become neutralized over time, have had calcium components leached by rainfall, or have developed cracks.

The (A) alkali metal silicate (hereinafter also referred to as "component A") penetrates (impregnates) the inside of a concrete structure to form a hardened body, thereby improving the surface strength of the concrete structure. As the (A) component, _any water-soluble alkali metal silicate (also referred to as "water glass") represented by the general formula _M2O.nSiO2 (M is at least one alkali metal selected from Li, K, Na, and Cs) can be used. As the (A) component, for example, sodium silicate, sodium orthosilicate, sodium metasilicate, lithium silicate, potassium silicate, etc. can be mentioned. In addition, water glass that is commercially available as an aqueous solution of an alkali metal silicate can also be used. The above-mentioned alkali metal silicates may be used alone, or two or more of them may be mixed and used.

The content of component (A) in the surface strengthening agent is preferably 5 to 60% by weight (more preferably 8 to 50% by weight) calculated as the active ingredients ( _M2O and _SiO2 ) in the surface strengthening agent. When the content is within this range, the surface strength can be increased and excellent aesthetics can be obtained.

In the present invention, it is preferable that the component (A) contains at least sodium silicate with a SiO ₂ /Na ₂ O (molar ratio) of 5/1 to 2/1 (more preferably 4/1 to 3/1). In such a case, the effect of the present invention can be further enhanced. Furthermore, in the present invention, potassium silicate with a SiO ₂ /K ₂ O (molar ratio) of 5/1 to 1/1 (more preferably 4/1 to 1/1) and lithium silicate with a SiO ₂ /Li ₂ O (molar ratio) of 5/1 to 2/1 (more preferably 5/1 to 3/1) can be mixed and used. This increases the permeability into the concrete structure and allows the formation of a dense hardened body. The reinforcing method of the present invention increases the waterproofing of the concrete structure and effectively suppresses deterioration due to the penetration of water such as rainfall. Furthermore, it is possible to suppress the elution of alkali metals and prevent efflorescence on the surface of the concrete structure.

In the present invention, it is particularly preferable to use a mixture of sodium silicate and potassium silicate. The mixing ratio of sodium silicate and potassium silicate is SiO ₂ /(Na ₂ O + K ₂ O) (molar ratio) of 5/1 to 1/1 (preferably 4/1 to 2.5/1), and it is preferable to adjust the SiO ₂ content to 5 to 50% by weight (more preferably 10 to 30% by weight) based on the entire surface strengthening agent. In this case, the content of sodium silicate (effective ingredient equivalent) in component (A) is preferably 10 to 98% by weight (more preferably 30 to 95% by weight or more), and the content of potassium silicate (effective ingredient equivalent) is preferably 2 to 90% by weight (more preferably 5 to 70% by weight), so that the above ranges can be adjusted. When the ranges are as above, the surface strength can be further increased and excellent aesthetics can be obtained.

It is also preferable to use lithium silicate in a mixed state. In this case, the mixing ratio of sodium silicate, potassium silicate, and lithium silicate is SiO ₂ / (Na ₂ O + K ₂ O + Li ₂ O) (molar ratio) is 5/1 to 1/1 (preferably 4/1 to 2/1), and it is preferable to adjust the content of SiO ₂ to 5 to 50% by weight (more preferably 10 to 30% by weight) relative to the entire surface strengthening agent. In this case, the content of sodium silicate (effective ingredient equivalent) in the (A) component is preferably 30 to 98% by weight (more preferably 50 to 95% by weight), the content of potassium silicate (effective ingredient equivalent) is preferably 1.5 to 50% by weight (more preferably 4 to 40% by weight), and the content of lithium silicate (effective ingredient equivalent) is preferably 0.5 to 40% by weight (more preferably 1 to 30% by weight), so that the above ranges can be adjusted. When the thickness is within such a range, water resistance is increased, and abnormal appearance such as whitening or gloss change due to penetration of water from rain or the like can be effectively suppressed.

The surface strengthening agent of the present invention is characterized by containing (B) a water-soluble silane compound (hereinafter also referred to as "component (B)") as an essential component. In the present invention, by using the above-mentioned components (A) and (B) in combination, the penetration (impregnation) of the above-mentioned component (A) into the interior (deep part) of the concrete structure can be enhanced. As a result, the above-mentioned component (A) penetrates without accumulating near the surface of the concrete structure, so that sufficient penetration depth and penetration amount can be secured, and the surface strength can be enhanced. Furthermore, an aesthetically excellent finish without uneven application or surface whitening can be obtained. In addition, the component (B) that penetrates (impregnates) into the interior of the concrete structure can react with the constituent components (cement, etc.) of the concrete structure to enhance its strength.

The component (B) of the present invention may be any component that dissolves in water, and is preferably capable of preparing a 1% by weight aqueous silane solution. When preparing the 1% by weight aqueous silane solution, the pH may be adjusted as necessary. Examples of such a component (B) include:
Epoxy group-containing silane compounds such as glycidoxymethyltrimethoxysilane, glycidoxymethyltriethoxysilane, β-glycidoxyethyltrimethoxysilane, β-glycidoxyethyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyldimethylmethoxysilane, γ-glycidoxypropyl(ethyl)dimethoxysilane, β-3,4-epoxycyclohexylethyltrimethoxysilane, β-3,4-epoxycyclohexylethyltriethoxysilane, 8-glycidoxyoctyltrimethoxysilane, 8-glycidoxyoctylmethyldimethoxysilane, and 8-glycidoxyoctylmethyldiethoxysilane;

γ-Aminopropyl trimethoxysilane, γ-aminopropyl triethoxysilane, γ-aminopropyl triisopropoxysilane, γ-aminopropyl methyl dimethoxysilane, γ-aminopropyl methyl diethoxysilane, N-β(aminoethyl)-γ-aminopropyl trimethoxysilane, N-β(aminoethyl)-γ-aminopropyl methyl dimethoxysilane, N-β(aminoethyl)-γ-aminopropyl triethoxysilane, N-β(aminoethyl)-γ-aminopropyl methyl diethoxysilane, N-β(aminoethyl)-γ- Amino group-containing silane compounds such as aminopropyltriisopropoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, γ-ureidopropyltrimethoxysilane, γ-anilinopropyltrimethoxysilane, γ-ureidopropyltrimethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, N-vinylbenzyl-γ-aminopropyltriethoxysilane, N-β(aminoethyl)-8-aminooctyltrimethoxysilane, and γ-triethoxysilyl-N-(1,3-dimethyl-butylidene)propylamine;

(meth)acryl group-containing silane compounds, such as 3-(meth)acryloxypropylmethyldimethoxysilane, 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropylmethyldiethoxysilane, and 3-(meth)acryloxypropyltriethoxysilane;
Other examples include 3-mercaptopropyltrimethoxysilane, bis(triethoxysilylpropyl)tetrasulfide, and 3-isocyanatepropylethoxysilane, etc. These can be used alone or in combination of two or more.

In particular, in the present invention, it is preferable that the component (B) contains an amino group-containing silane compound. This further enhances the penetration (impregnation) properties of the above-mentioned component (A) and suppresses the accumulation of calcium components on the surface of the concrete structure. In addition, after application, there is no uneven application or surface whitening, and the appearance is excellent. The content of the amino group-containing silane compound in the component (B) is preferably 50% by weight or more (more preferably 80% by weight or more), and the embodiment may be one in which only the amino group-containing silane compound is contained.

The content of component (B) in the composition is preferably 0.01 to 5% by weight (more preferably 0.05 to 5% by weight). If this range is satisfied, the permeability of component (A) into the concrete structure can be increased, and the surface strength can be further increased.

The surface strengthening agent of the present invention is prepared by dissolving the above-mentioned (A) and (B) components in water. The content of water in the surface strengthening agent is the remaining amount excluding the active ingredients of the above-mentioned (A) and (B) components, and is preferably 45 to 95% by weight (more preferably 50 to 90% by weight).

The concrete surface strengthening agent of the present invention may contain known additives as necessary. Examples of such additives include thickeners, leveling agents, wetting agents, antifreeze agents, preservatives, antifungal agents, anti-algae agents, antibacterial agents, deodorizers, dispersants, defoamers, adsorbents, flame retardants, coloring pigments, extender pigments, fibers, water repellents, UV absorbers, light stabilizers, antioxidants, catalysts, etc.

(Reinforcement method)
The present invention includes a step of applying the above-mentioned surface strengthening agent to a concrete structure, and can reinforce the concrete structure and increase its surface strength. It is particularly suitable for existing deteriorated concrete structures.

The method of applying the surface strengthening agent is not particularly limited, but various methods such as brush coating, roller coating, spray coating, etc. can be used. When painting in a factory, in addition to the above, a roll coater, flow coater, etc. can also be used.

The amount of the surface strengthening agent applied is preferably about 0.01 to 0.5 kg/m ² (more preferably 0.05 to 0.4 kg/m ² ). The number of times the surface strengthening agent is applied may be set appropriately depending on the condition of the concrete structure (such as the degree of deterioration), but is preferably 1 to 2 times. After application of the surface strengthening agent, water may be sprayed on the surface to enhance permeability. This makes it possible to obtain a finish with excellent aesthetics and with less occurrence of uneven gloss. The drying time of the composition is preferably 1 hour or more. The drying temperature is preferably from 0°C to 50°C, more preferably from 5°C to 40°C.

In the present invention, a reinforcing agent may be applied before the above steps depending on the surface condition of the concrete structure (carbonation, crack condition). This can further increase the surface strength. Examples of reinforcing methods include:
(1) applying the reinforcing agent to a concrete structure;
(2) applying the surface enhancing agent;
It is preferable to carry out the steps in sequence.

(Reinforcing agent)
The reinforcing agent in the above step (1) preferably contains (C) a water-soluble calcium salt (hereinafter also referred to as "component (C)"). Component (C) is a component that replenishes calcium ions in voids inside a concrete structure. Component (C) of the present invention is a calcium salt that can dissolve at 1% by weight or more in water at 25°C, and examples of such component include calcium chloride, calcium nitrate, calcium nitrite, and calcium acetate. These can be used alone or in combination of two or more. In the present invention, it is preferable to contain one selected from calcium nitrate, calcium nitrite, and the like. In particular, when calcium nitrite is contained, it is preferable because the action of the nitrite ions provides a rust-preventive effect on the reinforcing bars inside the concrete structure.

The content of component (C) in the reinforcing agent is preferably 1 to 50% by weight (more preferably 2 to 40% by weight, and even more preferably 3 to 20% by weight). If this range is satisfied, sufficient calcium ions can be replenished inside the concrete structure.

It is also preferable that the reinforcing agent contains a silane compound similar to the component (B). By using the component (C) and the component (B) in combination, the penetration (impregnation) of the component (C) into the interior of the concrete structure can be enhanced. As a result, calcium ions do not accumulate near the surface of the concrete structure immediately after application, but penetrate deep into the concrete structure, and sufficient calcium ions can be replenished, so that a sufficient penetration depth and penetration amount for repair can be secured. Furthermore, the component (B) that has penetrated into the interior of the concrete structure can react with the constituent components (cement, etc.) of the concrete structure to increase its strength. Furthermore, by containing the component (B), when the surface strengthening agent of the present invention is applied in step (2), it is possible to penetrate the surface strengthening agent into the interior (deep part) of the concrete structure, which can further increase the strength of the concrete structure and provide excellent waterproofing. Furthermore, since the surface strengthening agent can be uniformly penetrated (impregnated), it is difficult to cause uneven gloss, and a finish with excellent aesthetics can be obtained.

The content of component (B) in the reinforcing agent is preferably 0.01 to 5% by weight (more preferably 0.05 to 5% by weight). If this range is satisfied, the permeability of component (C) into the concrete structure can be increased, and the surface strength can be further increased.

The reinforcing agent is prepared by dissolving the above-mentioned (C) and (B) components in water. The content of water in the composition is the remaining amount excluding the above-mentioned (C) and (B) components, and is preferably 45 to 98.99% by weight (more preferably 55 to 97.95% by weight).

The reinforcing agent may contain known additives as necessary, so long as they do not significantly impair the effects of the present invention. Examples of such additives include thickeners, leveling agents, wetting agents, antifreeze agents, preservatives, antifungal agents, anti-algae agents, antibacterial agents, deodorizers, dispersants, defoamers, adsorbents, flame retardants, coloring pigments, extender pigments, fibers, water repellents, UV absorbers, light stabilizers, antioxidants, catalysts, etc.

In the above step (1), the method of applying the reinforcing agent is not particularly limited, but various methods such as brush coating, roller coating, spray coating, etc. can be used. When coating is performed in a factory, a roll coater, flow coater, etc. can also be used. Furthermore, the agent can be injected into cracks, etc. using a cylinder, etc.

The amount of the reinforcing agent to be applied is preferably about 0.01 to 0.5 kg/m ² , more preferably 0.03 to 0.4 kg/m ² , and even more preferably 0.05 to 0.3 kg/m ² . When this range is satisfied, the effects of the present invention can be fully obtained. Furthermore, when the amount is applied below the upper limit, discoloration of the concrete surface can be suppressed. The number of times the reinforcing agent is applied may be appropriately set depending on the state of the concrete structure (such as the degree of deterioration), but is preferably 1 to 2 times. Furthermore, water can be sprayed on the surface of the concrete structure after the reinforcing agent is applied. In the present invention, when the (B) component is contained, the (C) component is more likely to penetrate (impregnate) into the interior of the concrete structure together with the sprayed water, thereby enhancing the effects of the present invention. Furthermore, since the reinforcing agent is less likely to remain on the surface, discoloration can also be suppressed. The drying time of the reinforcing agent is preferably 1 hour or more. Furthermore, the drying temperature is preferably 0°C or more and 50°C or less, more preferably 5°C or more and 40°C or less.

Furthermore, in the present invention, after applying the surface strengthening agent of the present invention, a topcoat material can be applied as necessary.
(1) applying the reinforcing agent to a concrete structure;
(2) applying the surface enhancing agent;
(3) A step of applying a topcoat material;
It is preferable to carry out the steps in sequence.

(Topcoat material)
The topcoat material in the above (3) step is not particularly limited as long as it is generally used for painting buildings and civil engineering structures. The surface strengthening agent of the present invention in the above (2) can have excellent adhesion to a wide variety of topcoat materials by containing the above (B) component. Usable topcoat materials include those that contain resin components and, if necessary, coloring pigments.

As the resin component, various resins can be used. Examples of the resin include vinyl acetate resin, polyester resin, alkyd resin, vinyl chloride resin, epoxy resin, acrylic resin, urethane resin, acrylic silicone resin, fluororesin, etc., or composite resins thereof. Among these, one or more types selected from acrylic resin, urethane resin, acrylic silicone resin, fluororesin, etc. are suitable. Examples of the form of such a resin component include water-soluble resin, water-dispersible resin (resin emulsion), solvent-soluble resin, solventless resin, non-water-dispersible resin, powdered resin, etc. Furthermore, among the solvent-soluble resins and/or non-water-dispersible resins, so-called weak solvent resins in which 50% by weight or more (preferably 60% by weight or more) of the total solvent is an aliphatic hydrocarbon are also suitable. Examples of aliphatic hydrocarbons include n-hexane, n-pentane, n-octane, n-nonane, n-decane, n-undecane, n-dodecane, etc., or aliphatic hydrocarbon solvents such as terpine oil and mineral spirits. Among these, in the present invention, water-soluble resins and/or water-dispersible resins are preferred. Furthermore, these resin components may have crosslinking reactivity. When a resin component having crosslinking reactivity is used, the durability, water resistance, weather resistance, chemical resistance, adhesion, etc. of the coating can be improved.

As coloring pigments, for example, known inorganic coloring pigments, organic coloring pigments, etc. can be used. By using one or more of these coloring pigments appropriately, the topcoat material can be set to the desired hue. The mixing ratio of the coloring pigment is preferably 1 to 500 parts by weight, more preferably 5 to 200 parts by weight, and even more preferably 10 to 100 parts by weight, per 100 parts by weight of the solid content of the resin component.

As the topcoat material of the present invention, a material that forms a transparent film can also be used. In this case, it is preferable because it is possible to impart performance such as water-stopping properties, durability, and aesthetics while preserving the appearance of the concrete structure. One or more types of topcoat materials can be used. When using two or more types of topcoat materials, it is also possible to use topcoat materials with different color tones to create a multi-colored appearance of two or more colors.

Such a topcoat material may contain various components other than those mentioned above, so long as the effects of the present invention are not significantly impaired. Examples of such components include thickeners, film-forming agents, leveling agents, wetting agents, plasticizers, antifreeze agents, pH adjusters, extender pigments, preservatives, antifungal agents, anti-algae agents, antibacterial agents, dispersants, defoamers, adsorbents, fibers, crosslinking agents, UV absorbers, light stabilizers, antioxidants, catalysts, solvents, and water. The topcoat material of the present invention can be manufactured by uniformly mixing the various components described above using conventional methods.

In painting the topcoat material, a known painting tool can be used. Examples of the painting tool that can be used include a spray, a roller, and a brush.
The amount of topcoat material to be applied may be set appropriately depending on the surface shape of the substrate, the type of topcoat material, the type of painting equipment, etc., but is preferably 0.1 to 1 kg/m ² , more preferably 0.15 to 0.5 kg/m ^2. When painting, the topcoat material can also be appropriately diluted as necessary.

The following examples will clarify the features of the present invention.

The following raw materials were used:
(A) Component (A1) Sodium silicate aqueous solution Active ingredient: 33.0% (SiO ₂ = 26.0%, Na ₂ O = 7.0%)
_SiO2 / _Na2O (molar ratio) = 3.83
(A2) Potassium silicate aqueous solution
Active ingredient: 55.0% ( _SiO2 =28.0%, _K2O =22.0%)
_SiO2 / _K2O (molar ratio) = 1.99
(A3) Lithium silicate aqueous solution Active ingredient: 23.3% (SiO ₂ = 20.4%, Li ₂ O = 2.9%)
_SiO2 / _Li2O (molar ratio) = 3.50
(B) Component (B1) N-β(aminoethyl)-γ-aminopropyltrimethoxysilane (B2) γ-aminopropyltrimethoxysilane (C) Component (C1) Calcium nitrite

<Preparation of Surface Strengthening Agent>
・Surface strengthening agent 1
A mixture of 70 parts by weight of (A1) sodium silicate aqueous solution, 0.5 parts by weight of (B1) N-β(aminoethyl)-γ-aminopropyltrimethoxysilane, and 29.5 parts by weight of water was used as surface strengthening agent 1.
・Surface strengthening agent 2
A mixture of 60 parts by weight of (A1) sodium silicate aqueous solution, 10 parts by weight of (A2) potassium silicate aqueous solution, 0.5 parts by weight of (B1) N-β(aminoethyl)-γ-aminopropyltrimethoxysilane, and 29.5 parts by weight of water was used as surface strengthening agent 2.
・Surface strengthening agent 3
A surface strengthening agent 3 was prepared by mixing 55 parts by weight of (A1) an aqueous sodium silicate solution, 10 parts by weight of (A2) an aqueous potassium silicate solution, 5 parts by weight of (A3) an aqueous lithium silicate solution, 0.5 parts by weight of (B1) N-β(aminoethyl)-γ-aminopropyltrimethoxysilane, and 29.5 parts by weight of water.
・Surface strengthening agent 4
A surface strengthening agent 4 was prepared by mixing 55 parts by weight of (A1) an aqueous sodium silicate solution, 10 parts by weight of (A2) an aqueous potassium silicate solution, 5 parts by weight of (A3) an aqueous lithium silicate solution, 0.5 parts by weight of (B2) γ-aminopropyltrimethoxysilane, and 29.5 parts by weight of water.
・Surface strengthening agent 5
A surface strengthening agent 5 was prepared by mixing 55 parts by weight of (A1) an aqueous sodium silicate solution, 10 parts by weight of (A2) an aqueous potassium silicate solution, 5 parts by weight of (A3) an aqueous lithium silicate solution, 0.1 parts by weight of (B1) N-β(aminoethyl)-γ-aminopropyltrimethoxysilane, and 29.9 parts by weight of water.
Surface strengthening agent 6
A surface strengthening agent 6 was prepared by mixing 55 parts by weight of (A1) an aqueous sodium silicate solution, 10 parts by weight of (A2) an aqueous potassium silicate solution, 5 parts by weight of (A3) an aqueous lithium silicate solution, 5 parts by weight of (B1) N-β(aminoethyl)-γ-aminopropyltrimethoxysilane, and 25 parts by weight of water.
・Surface strengthening agent 7
A surface strengthening agent 7 was prepared by mixing 55 parts by weight of (A1) an aqueous sodium silicate solution, 10 parts by weight of (A2) an aqueous potassium silicate solution, 5 parts by weight of (A3) an aqueous lithium silicate solution, 8 parts by weight of (B1) N-β(aminoethyl)-γ-aminopropyltrimethoxysilane, and 22 parts by weight of water.
・Surface strengthening agent 8
A surface strengthening agent 8 was prepared by mixing 30 parts by weight of (A1) an aqueous sodium silicate solution, 30 parts by weight of (A2) an aqueous potassium silicate solution, 10 parts by weight of (A3) an aqueous lithium silicate solution, 0.5 parts by weight of (B1) N-β(aminoethyl)-γ-aminopropyltrimethoxysilane, and 29.5 parts by weight of water.
・Surface strengthening agent 9
A surface strengthening agent 9 was prepared by mixing 20 parts by weight of (A1) sodium silicate aqueous solution, 50 parts by weight of (A2) potassium silicate aqueous solution, 0.5 parts by weight of (B1) N-β(aminoethyl)-γ-aminopropyltrimethoxysilane, and 29.5 parts by weight of water.
・Surface strengthening agent 10
(A1) A surface strengthening agent 10 was prepared by mixing 70 parts by weight of sodium silicate solution and 30 parts by weight of water.
・Surface strengthening agent 11
A surface strengthening agent 11 was prepared by mixing 55 parts by weight of (A1) sodium silicate aqueous solution, 10 parts by weight of (A2) potassium silicate aqueous solution, 5 parts by weight of (A3) lithium silicate aqueous solution, and 30 parts by weight of water.

<Preparation of Reinforcing Agent>
Reinforcing agent 1
Reinforcing agent 1 was obtained by adding 0.1 parts by weight of (B1) N-β(aminoethyl)-γ-aminopropyltrimethoxysilane to 100 parts by weight of a 15% aqueous calcium nitrite solution prepared by dissolving (C1) calcium nitrite in water and stirring the mixture.
Reinforcing agent 2
Reinforcing agent 2 was obtained by adding 0.1 parts by weight of (B2) γ-aminopropyltrimethoxysilane to 100 parts by weight of a 15% aqueous calcium nitrite solution prepared by dissolving (C1) calcium nitrite in water and stirring the mixture.
Reinforcing agent 3
(C1) 100 parts by weight of a 15% calcium nitrite aqueous solution obtained by dissolving calcium nitrite in water was used as the reinforcing material 3.

<Test Example [I]>
Surface strengthening agents 1 to 11 were each applied by brushing onto a substrate [I] (standard mortar: 100 x 100 x 20 mm) at a coating weight of 0.2 kg/ ^m2 , and the specimens were cured at room temperature (23°C) for 7 days, and the following evaluations were carried out. The results are shown in Table 1.

Aesthetics Evaluation The surface of the test specimen was visually evaluated to evaluate the presence or absence of abnormalities in appearance such as uneven gloss, uneven hue, etc. The evaluation criteria were the following three levels (excellent: A>B>C: poor).
A: The finish is uniform and there are no abnormalities.
B: Slight abnormalities are observed.
C: Clear abnormality is observed.

Abrasion resistance (surface strength) evaluation: The obtained test specimens were observed for abrasion loss after 500 revolutions using a Taber tester, an abrasion wheel CS-17, and a load of 1000 g in accordance with JIS K5600 5.9 Abrasion resistance (abrasion wheel method). The abrasion loss was compared with that of the untreated substrate [I] and evaluated. The evaluation criteria were the following three levels (excellent: A>B>C: poor).
A: Better than untreated product B: Slightly better than untreated product C: Equivalent to or worse than untreated product

Water permeability evaluation Surface strengthening agents 1 to 11 were applied to the above substrate [I] with a brush at a coating amount of 0.2 kg/ ^m2 , and the specimens were cured at room temperature (23°C) for 7 days to prepare test specimens. Water permeability was evaluated according to JIS A 6909 7.13 (Water permeability test method B). Evaluation was performed in comparison with an uncoated standard mortar board. The evaluation criteria were the following three levels (Excellent: A>B>C: Poor).
A: Low water permeability B: Equivalent C: High water permeability

In test examples I-1 to I-9, the permeability of the surface strengthening agent was good, and good results were obtained in the aesthetic evaluation, abrasion resistance evaluation, and water permeability evaluation. In particular, test examples I-2 to I-5 achieved excellent results, receiving an A rating in all evaluations. On the other hand, in test examples I-10 to I-11, the permeability of the surface strengthening agent was poor, and sufficient results were not obtained.

<Test Example [II]>
Substrate [II]
Standard mortar (100 x 100 x 20 mm) was left to stand in a 5% _CO2 atmosphere for 60 days and neutralized to prepare the substrate.
According to the combination of the reinforcing agent and the surface strengthening agent shown in Table 2, the reinforcing agent was brushed on the above-mentioned substrate [II] at a coating amount of 0.1 kg/ ^m2 , and after aging at room temperature (25°C, 60% Rh) for 24 hours, the surface strengthening agent was brushed on at a coating amount of 0.2 kg/ ^m2 and left to stand for 30 minutes. After leaving to stand, the excess of the surface strengthening agent 1 was removed, and the specimen was wiped with water and aged at room temperature (25°C) for 7 days to be used as a test specimen, and the following evaluation was performed. The results are shown in Table 2.

Aesthetics Evaluation Test Example Aesthetics were evaluated in the same manner as in [I].
Abrasion resistance was evaluated in the same manner as in the abrasion resistance evaluation test [I]. The abrasion resistance was evaluated by comparing with the abrasion loss of the untreated substrate [II].

-Evaluation of penetration depth The surface of the obtained test specimen is ground every 1 mm in depth. Water is added so that the obtained grinding powder becomes 5%, and the mixture is stirred for 10 minutes and left to stand for 24 hours to extract sodium (Na) into the water. The amount of Na is measured using a Na ion meter, and it is determined that the material has penetrated to a depth where the amount of Na is 30% or more higher than that of uncoated mortar, and the penetration depth is calculated. The evaluation criteria are the following three levels (excellent: A>B>C: poor).
A: 2 mm or more B: 1 mm or more but less than 2 mm C: Less than 1 mm

In test examples II-1 to II-3, the permeability of the surface strengthening agent was good, and good results were obtained in the aesthetic evaluation, abrasion resistance evaluation, and permeability evaluation. In particular, in test examples II-1 and II-2, the permeability of the surface strengthening agent was excellent, and excellent abrasion resistance was obtained even in the neutralized substrate [II].

<Test Example [III]>
The above-mentioned substrate [II] was brushed with the reinforcing agent 1 at a coating amount of 0.1 kg/m ² , and aged at room temperature (25 ° C, 60% Rh) for 24 hours, and then the surface strengthening agent shown in Table 3 was brushed with a coating amount of 0.2 kg/m ² and left to stand for 30 minutes. After standing, the excess of the surface strengthening agent was removed, wiped with water, and aged at room temperature (25 ° C) for 7 days. Next, the topcoat material 1 (weak solvent type acrylic resin paint) was brushed with a coating amount of 0.2 kg/m ² , and the specimen was aged at room temperature (25 ° C) for 7 days, and the following evaluation was carried out. The results are shown in Table 3.

Adhesion evaluation: The adhesion of the obtained test specimens was evaluated by a checkered tape method in accordance with JIS K5600-5-6. The evaluation criteria were the following four levels (excellent: A>B>C>D: poor).
A: The area of the defective portion is less than 10%. B: The area of the defective portion is 10% or more and less than 30%. C: The area of the defective portion is 30% or more and less than 50%. D: The area of the defective portion is 50% or more.

In Test Examples III-1 to III-6, the adhesion evaluation showed good results.

Claims (4)

A reinforcing agent containing a water-soluble calcium salt and a water-soluble silane compound is applied to a concrete substrate, and then
A concrete surface strengthening agent containing at least an alkali metal silicate, a water-soluble silane compound, and water is applied.
A method for reinforcing a concrete substrate comprising the steps of: 2. The method for reinforcing a concrete substrate according to claim 1, wherein the water-soluble silane compound in the concrete surface reinforcing agent contains an amino group-containing silane compound. 2. The method for reinforcing a concrete substrate according to claim 1, wherein the water-soluble silane compound in the reinforcing agent contains an amino group-containing silane compound . A method for finishing a concrete substrate, comprising applying the concrete surface reinforcing agent by the method for reinforcing a concrete substrate according to claim 1 , and then applying a topcoat material.