Surface strengthening agent, method for reinforcing concrete base material, and finishing method

Abstract

To obtain a concrete surface reinforcing agent which is capable of sufficiently impregnating an alkali metal silicate to a concrete structure.SOLUTION: A concrete surface reinforcing agent includes at least an alkali metal silicate, a water-soluble silane compound, and water, wherein the alkali metal silicate includes sodium silicate and potassium silicate.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a novel concrete surface strengthening agent.

Background Art

[0002] Conventionally, many concrete structures have been used for bridges, tunnels, elevated roads, buildings, and the like. However, concrete structures deteriorate over time due to salt damage, carbonation, freezing damage, etc., and there are problems such as cracks and peeling of concrete pieces occurring in the structures. Therefore, many methods for repairing and strengthening concrete structures have been proposed.

[0003] For example, Japanese Patent Application Laid-Open No. 2002-179479 (Patent Document 1) discloses permeating an alkali metal silicate such as water glass. However, in such Patent Document 1, there are cases where the alkali metal silicate cannot permeate to the inside of the concrete structure.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The present invention has been made in view of such circumstances, and an object thereof is to obtain a concrete surface strengthening agent capable of sufficiently impregnating an alkali metal silicate into a concrete structure.

Means for Solving the Problems

[0006] In view of the problems of the prior art as described above, the inventors of the present invention have conducted intensive research and, as a result, have conceived of a concrete surface strengthening agent characterized by containing at least an alkali metal silicate, a water-soluble silane compound, and water, and have completed the present invention.

[0007] That is, the present invention has the following characteristics. 1. It contains at least an alkali metal silicate, a water-soluble silane compound, and water, The above alkali metal silicate includes sodium silicate and potassium silicate and lithium silicate and contains and the content of the sodium silicate in the above alkali metal silicate (in terms of active ingredient) is 30 to 98% by weight, the content of the potassium silicate (in terms of active ingredient) is 1.5 to 50% by weight, and the content of the lithium silicate (in terms of active ingredient) is 0.5 to 40% by weight A concrete surface strengthening agent characterized by this. 2. The mixing ratio of the above sodium silicate and the above potassium silicate is such that SiO2 / (Na2O + K2O) (molar ratio) is 5 / 1 to 1 / 1, and the concrete surface strengthening agent according to 1. 3. The mixing ratio of the sodium silicate, the potassium silicate, and the lithium silicate is such that the molar ratio of SiO 2 / (Na 2 O + K 2 O + Li 2 O) is 5 / 1 to 1 / 1, and it is the concrete surface strengthening agent according to 1 4. The water-soluble silane compound contains an amino group-containing silane compound, and the concrete surface strengthening agent according to 1. 5. A method for reinforcing a concrete substrate, characterized in that the concrete surface strengthening agent according to 1. is applied to the concrete substrate. 6. A method for reinforcing a concrete substrate, characterized in that after applying a reinforcing agent containing a water-soluble calcium salt to the concrete substrate, the concrete surface strengthening agent according to 1. is applied. 7. A method for finishing a concrete substrate, characterized in that after applying the concrete surface strengthening agent by the method for reinforcing a concrete substrate according to 5. or 6., a topcoat is applied.

Effects of the Invention

[0008] According to the present invention, the permeability of the alkali metal silicate to the concrete structure can be further increased, the deterioration of the concrete structure can be repaired, and the surface strength can be increased. [Embodiments for Carrying Out the Invention]

[0009] Hereinafter, embodiments for carrying out the present invention will be described.

[0010] (Concrete Surface Strengthening Agent) The present invention relates to a surface strengthening agent to be applied to a concrete structure. By applying it to a concrete structure, particularly a deteriorated concrete structure, an alkali metal silicate penetrates (impregnates) into the concrete structure, forms a cured body, repairs the deteriorated part, and can increase the surface strength. 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.

[0011] Examples of concrete structures include those composed of cement, mortar, etc., such as bridges, tunnels, elevated roads, and buildings, and they can be either new or existing. The composition of the present invention is suitable for existing concrete structures, particularly deteriorated concrete structures in which neutralization has progressed due to aging, calcium components have eluted due to rainfall, or cracks have occurred.

[0012] (A) The alkali metal silicate (hereinafter also referred to as "component (A)") penetrates (impregnates) into the concrete structure and forms a cured body, thereby improving the surface strength, etc. of the concrete structure. As such a component (A), any water-soluble alkali metal silicate represented by the general formula: M2O·nSiO2 (M is at least one alkali metal selected from Li, K, Na, Cs) (also referred to as "water glass") can be used. Examples of such a component (A) include sodium silicate, sodium orthosilicate, sodium metasilicate, lithium silicate, potassium silicate, etc. Also, water glass commercially available as an aqueous solution of an alkali metal silicate can be used. The above alkali metal silicates may be used alone or in combination of two or more.

[0013] The content of component (A) in the surface strengthening agent is preferably 5 to 60% by weight (more preferably 8 to 50% by weight) in terms of the active components (M2O and SiO2) in the surface strengthening agent. In such a range, the surface strength can be increased and excellent aesthetic properties can be obtained.

[0014] In the present invention, as component (A), it is preferable to contain sodium silicate having at least SiO2 / Na2O (molar ratio) of 5 / 1 to 2 / 1 (more preferably 4 / 1 to 3 / 1). In such a case, the effects of the present invention can be further enhanced. Further, in the present invention, potassium silicate having SiO2 / K2O (molar ratio) of 5 / 1 to 1 / 1 (more preferably 4 / 1 to 1 / 1) and lithium silicate having SiO2 / Li2O (molar ratio) of 5 / 1 to 2 / 1 (more preferably 5 / 1 to 3 / 1) can be mixed and used. Thereby, the permeability to the concrete structure is increased, and a dense cured body can be formed. By the reinforcement method of the present invention, the waterproof property of the concrete structure is increased, and deterioration due to penetration of water such as rainfall can be effectively suppressed. Furthermore, elution of alkali metals and the like can be suppressed, and efflorescence on the surface of the concrete structure can also be prevented.

[0015] In the present invention, in particular, it is preferable to mix and use sodium silicate and potassium silicate. The mixing ratio of sodium silicate and potassium silicate is such that SiO2 / (Na2O + K2O) (molar ratio) is 5 / 1 to 1 / 1 (preferably 4 / 1 to 2.5 / 1), and it is preferable to adjust so that the content of SiO2 is 5 to 50% by weight (more preferably 10 to 30% by weight) with respect to the whole surface strengthening agent. In this case, the content of sodium silicate (in terms of active component) 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 (in terms of active component) is preferably 2 to 90% by weight (more preferably 5 to 70%) to adjust to the above range. When it is in such a range, the surface strength can be further increased and excellent aesthetic properties can be obtained.

[0016] Furthermore, it is also preferable to use a mixture containing lithium silicate. In this case, the mixing ratio of sodium silicate, potassium silicate, and lithium silicate is such that SiO2 / (Na2O + K2O + Li2O) (molar ratio) is 5 / 1 to 1 / 1 (preferably 4 / 1 to 2 / 1), and it is preferable to adjust the SiO2 content to 5 to 50% by weight (more preferably 10 to 30% by weight) based on the total surface strengthening agent. In this case, the content of sodium silicate (in terms of active ingredient) in component (A) is preferably 30 to 98% by weight (more preferably 50 to 95% by weight), the content of potassium silicate (in terms of active ingredient) is preferably 1.5 to 50% by weight (more preferably 4 to 40% by weight), and the content of lithium silicate (in terms of active ingredient) is preferably 0.5 to 40% by weight (more preferably 1 to 30%) so as to be adjusted within the above range. When in such a range, the water resistance is enhanced, and appearance abnormalities such as whitening and gloss change due to water penetration such as rainfall can be effectively suppressed.

[0017] 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 component (A) and component (B) in combination, the penetrability (impregnation) of the above component (A) into the interior (deep part) of the concrete structure can be enhanced. As a result, the component (A) can penetrate without accumulating near the surface of the concrete structure, so that a sufficient penetration depth and penetration amount can be ensured, and the surface strength can be increased. Furthermore, a finish with excellent aesthetic properties without coating unevenness, surface whitening, etc. can be obtained. In addition, the component (B) that has penetrated (impregnated) into the concrete structure can react with the constituent components (cement, etc.) of the concrete structure to increase the strength.

[0018] The component (B) of the present invention may be any one that can be dissolved in water, and preferably one that can prepare a 1% by weight silane aqueous solution. When preparing this 1% by weight silane aqueous solution, the pH may be adjusted as necessary. Examples of such 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, 8-glycidoxyoctylmethyldiethoxysilane;

[0019] Amino group-containing silane compounds such as γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropyltriisopropoxysilane, γ-aminopropylmethyldimethoxysilane, γ-aminopropylmethyldiethoxysilane, N-β(aminoethyl)-γ-aminopropyltrimethoxysilane, N-β(aminoethyl)-γ-aminopropylmethyldimethoxysilane, N-β(aminoethyl)-γ-aminopropyltriethoxysilane, N-β(aminoethyl)-γ-aminopropylmethyldiethoxysilane, N-β(aminoethyl)-γ-aminopropyltriisopropoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, γ-ureidopropyltrimethoxysilane, γ-anilinopropyltrimethoxysilane, γ-ureidopropyltrimethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, N-vinylbenzyl-γ-aminopropyltriethoxysilane, N-β(aminoethyl)-8-aminooctyltrimethoxysilane, γ-triethoxysilyl-N-(1,3-dimethyl-butylidene)propylamine;

[0020] (Meth)acrylic group-containing silane compounds such as 3-(meth)acryloxypropylmethyldimethoxysilane, 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropylmethyldiethoxysilane, 3-(meth)acryloxypropyltriethoxysilane; Other examples include 3-mercaptopropyltrimethoxysilane, bis(triethoxysilylpropyl)tetrasulfide, and 3-isocyanatopropyltriethoxysilane. These can be used alone or in combination of two or more.

[0021] Among them, in the present invention, as the component (B), it is preferable to contain an amino group-containing silane compound. Thereby, the penetration (impregnation) property of the above component (A) can be further enhanced, and the accumulation of calcium components on the surface of the concrete structure can be suppressed. Also, after application, there are no coating irregularities, surface whitening, etc., and it has excellent aesthetic properties. The content of the amino group-containing silane compound is preferably 50% by weight or more (more preferably 80% by weight or more) in the component (B), and it may be in the form of only the amino group-containing silane compound.

[0022] The content of the component (B) is preferably 0.01 to 5% by weight (more preferably 0.05 to 5% by weight) in the composition. When such a range is satisfied, the penetrability of the above component (A) into the concrete structure can be enhanced, and the surface strength can be further enhanced.

[0023] The surface strengthening agent of the present invention is obtained by dissolving the above component (A) and the above component (B) in water. The water content in the surface strengthening agent is the remaining amount excluding the active ingredients of the above component (A) and the above component (B), and is preferably 45 to 95% by weight (more preferably 50 to 90% by weight).

[0024] The concrete surface strengthening agent of the present invention can contain known additives as required. Such additives include, for example, thickeners, leveling agents, wetting agents, antifreezing agents, antiseptics, mildew inhibitors, algicides, antibacterial agents, deodorants, dispersants, defoamers, adsorbents, flame retardants, coloring pigments, extender pigments, fibers, water repellents, ultraviolet absorbers, light stabilizers, antioxidants, catalysts, etc.

[0025] (Reinforcement method) The present invention includes a step of applying the above surface strengthening agent to a concrete structure, and can reinforce the concrete structure and increase the surface strength. In particular, it is suitable for existing deteriorated concrete structures.

[0026] The method of applying the surface strengthening agent is not particularly limited, and for example, various methods such as brush painting, roller painting, and spray painting can be adopted. Also, when painting in a factory, in addition to the above, a roll coater, a flow coater, etc. can also be used for painting.

[0027] Regarding the application amount of the surface strengthening agent, it is preferably 0.01 - 0.5 kg / m 2 (More preferably 0.05 - 0.4 kg / m 2 ). The number of times of applying the surface strengthening agent can be appropriately set according to the state of the concrete structure (degree of deterioration, etc.), but it is preferably 1 - 2 times. Also, after applying the surface strengthening agent, in order to enhance the permeability, water can be sprayed on the surface. Thereby, it is difficult to cause uneven gloss, etc., and a finish with excellent aesthetic appearance can be obtained. The drying time of the composition is preferably 1 hour or more. Also, the drying temperature is preferably 0°C or higher and 50°C or lower, more preferably 5°C or higher and 40°C or lower.

[0028] In the present invention, according to the surface state of the concrete structure (neutralization, crack state), a reinforcing agent may be applied before the above step. Thereby, the surface strength can be further enhanced. As the reinforcement method, for example, (1) A step of applying the above reinforcing agent to the concrete structure, (2) The step of applying the surface strengthening agent are preferably carried out sequentially.

[0029] (Reinforcing agent) The reinforcing agent in the above step (1) preferably contains (C) water-soluble calcium salt (hereinafter also referred to as "(C) component"). The (C) component is a component that replenishes calcium ions into the voids inside the concrete structure. The (C) component of the present invention is a calcium salt that can dissolve 1% by weight or more in water at 25°C, and examples thereof include calcium chloride, calcium nitrate, calcium nitrite, calcium acetate, etc. 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, etc. In particular, when calcium nitrite is included, it is suitable because a rust prevention effect on the reinforcing bars inside the concrete structure can be obtained due to the action of nitrite ions.

[0030] (C) The content of the component is preferably 1 to 50% by weight (more preferably 2 to 40% by weight, still more preferably 3 to 20% by weight) in the reinforcing agent. When such a range is satisfied, sufficient calcium ions can be replenished into the inside of the concrete structure.

[0031] Further, it is 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 penetrability (impregnation) of the component (C) into the interior of the concrete structure can be enhanced. As a result, calcium ions do not accumulate in the vicinity of the surface of the concrete structure immediately after coating, and the component (C) can penetrate to the deep part of the concrete structure to sufficiently replenish calcium ions, so that a sufficient penetration depth and penetration amount for repair can be ensured. Further, the component (B) that has penetrated into the interior of the concrete structure can react with the constituent components (such as cement) of the concrete structure to enhance the strength. Further, by including the component (B), in step (2), when applying the surface strengthening agent of the present invention, it becomes possible to penetrate the surface strengthening agent to the interior (deep part) of the concrete structure, further enhancing the strength of the concrete structure and imparting excellent waterproof properties. Furthermore, since the surface strengthening agent can be uniformly penetrated (impregnated), it is difficult to cause uneven gloss or the like, and a finish with excellent aesthetic appearance can be obtained.

[0032] (B) The content of the component is preferably 0.01 to 5% by weight (more preferably 0.05 to 5% by weight) in the reinforcing agent. When such a range is satisfied, the penetrability of the component (C) with respect to the concrete structure can be enhanced, and the surface strength can be further enhanced.

[0033] The reinforcing agent is a solution of the component (C) and the component (B) in water. The water content in the composition is the remaining amount excluding the component (C) and the component (B), and is preferably 45 to 98.99% by weight (more preferably 55 to 97.95% by weight).

[0034] The reinforcing agent can contain known additives as necessary, as long as the effects of the present invention are not significantly impaired. Examples of such additives include thickeners, leveling agents, wetting agents, antifreezing agents, preservatives, fungicides, algicides, antibacterial agents, deodorants, dispersants, antifoaming agents, adsorbents, flame retardants, coloring pigments, extender pigments, fibers, water repellents, ultraviolet absorbers, light stabilizers, antioxidants, catalysts, and the like.

[0035] In the above step (1), the method of applying the reinforcing agent is not particularly limited. For example, various methods such as brush painting, roller painting, and spray painting can be adopted. Also, when painting in a factory, in addition to the above, it can also be painted using a roll coater, a flow coater, etc. Further, for cracks and the like, it can also be injected using a cylinder or the like.

[0036] Regarding the application amount of the reinforcing agent, it is preferably 0.01 to 0.5 kg / m 2 More preferably 0.03 to 0.4 kg / m 2 , even more preferably 0.05 to 0.3 kg / m 2 ). When the above range is satisfied, the effects of the present invention can be sufficiently obtained. Also, when applied below the above upper limit, discoloration and the like of the concrete surface can be suppressed. Note that the number of times of applying the reinforcing agent may be appropriately set according to the state (degree of deterioration, etc.) of the concrete structure, but it is preferably 1 to 2 times. Also, after applying the reinforcing agent, the surface of the concrete structure can be watered. In the present invention, when the component (B) is included, the above component (C) can more easily penetrate (impregnate) into the interior of the concrete structure together with the sprayed water, and the effects of the present invention can be enhanced. Furthermore, since it is difficult for the reinforcing agent to remain on the surface, discoloration and the like can also be suppressed. The drying time of the reinforcing agent is preferably 1 hour or more. Also, the drying temperature is preferably 0°C or higher and 50°C or lower, more preferably 5°C or higher and 40°C or lower.

[0037] Furthermore, in the present invention, after applying the surface strengthening agent of the present invention, a topcoat can be applied as necessary. Furthermore, (1) A step of applying the above reinforcing agent to a concrete structure, (2) A step of applying the above surface strengthening agent, (3) A step of applying a topcoat, are preferably carried out sequentially.

[0038] (Topcoat) The topcoat material used in the above (3) process 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. Examples of usable topcoat materials include those containing a resin component and, if necessary, a coloring pigment.

[0039] As the resin component, various resins can be used. Examples of resin types 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 selected from acrylic resin, urethane resin, acrylic silicone resin, fluororesin, etc. are preferred. Also, examples of the form of such a resin component include water-soluble resin, water-dispersible resin (resin emulsion), solvent-soluble resin, solvent-free resin, non-aqueous dispersion resin, powder resin, etc. Also, among solvent-soluble resins and / or non-aqueous dispersion resins, so-called weak solvent-type resins in which 50% by weight or more (preferably 60% by weight or more) of all solvents are aliphatic hydrocarbons are also preferred. 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 terpene oil and mineral spirit. Among these, in the present invention, water-soluble resin and / or water-dispersible resin is preferred. Also, 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 film can be improved.

[0040] As the coloring pigment, for example, known inorganic coloring pigments, organic coloring pigments, etc. can be used. By appropriately using one or more of these coloring pigments, the topcoat material can be set to a 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 with respect to 100 parts by weight of the solid content of the above resin component.

[0041] As the topcoat material of the present invention, those that form a transparent film can also be used. In this case, it is suitable because it can impart performance such as water stoppage, durability, and aesthetic appearance while making use of the appearance of the concrete structure. Also, one or more topcoat materials can be used. When using two or more topcoat materials, it is also possible to use topcoat materials with different color tones to finish with a multi-color appearance of two or more colors.

[0042] Such a topcoat material may contain various components other than the above components as long as the effects of the present invention are not significantly impaired. Examples of such components include thickeners, film-forming aids, leveling agents, wetting agents, plasticizers, antifreezing agents, pH adjusters, extender pigments, antiseptics, fungicides, algicides, antibacterial agents, dispersants, defoamers, adsorbents, fibers, crosslinking agents, ultraviolet absorbers, light stabilizers, antioxidants, catalysts, solvents, water, and the like. The topcoat material of the present invention can be manufactured by uniformly mixing the above various components by a conventional method.

[0043] In the painting of the topcoat material, known painting tools can be used. As the painting tools, for example, sprayers, rollers, brushes, etc. can be used. The coating amount of the topcoat material may be appropriately set according to the surface shape of the base material, the type of the topcoat material, the type of the painting tool, etc., but is preferably 0.1 to 1 kg / m 2 , more preferably 0.15 to 0.5 kg / m 2 . At the time of painting, the topcoat material can be appropriately diluted as necessary.

Examples

[0044] Examples are shown below to make the features of the present invention clearer.

[0045] The following were used as raw materials. (A) component (A1) Aqueous sodium silicate solution Active ingredient: 33.0% (SiO2 = 26.0%, Na2O = 7.0%) SiO2 / Na2O (molar ratio) = 3.83 (A2) Aqueous potassium silicate solution Active ingredient: 55.0% (SiO2 = 28.0%, K2O = 22.0%) SiO2 / K2O (molar ratio) = 1.99 (A3) Aqueous lithium silicate solution Active ingredient: 23.3% (SiO2 = 20.4%, Li2O = 2.9%) SiO2 / Li2O (molar ratio) = 3.50 (B) Component (B1) N-β(aminoethyl)-γ-aminopropyltrimethoxysilane (B2) γ-aminopropyltrimethoxysilane (C) Component (C1) Calcium nitrite

[0046] <Preparation of surface strengthening agent> ·Surface strengthening agent 1 70 parts by weight of aqueous sodium silicate solution (A1), 0.5 part by weight of N-β(aminoethyl)-γ-aminopropyltrimethoxysilane (B1), and 29.5 parts by weight of water were mixed to obtain surface strengthening agent 1. ·Surface strengthening agent 2 60 parts by weight of aqueous sodium silicate solution (A1), 10 parts by weight of aqueous potassium silicate solution (A2), 0.5 part by weight of N-β(aminoethyl)-γ-aminopropyltrimethoxysilane (B1), and 29.5 parts by weight of water were mixed to obtain surface strengthening agent 2. ·Surface strengthening agent 3 55 parts by weight of aqueous sodium silicate solution (A1), 10 parts by weight of aqueous potassium silicate solution (A2), 5 parts by weight of aqueous lithium silicate solution (A3), 0.5 part by weight of N-β(aminoethyl)-γ-aminopropyltrimethoxysilane (B1), and 29.5 parts by weight of water were mixed to obtain surface strengthening agent 3. ·Surface strengthening agent 4 55 parts by weight of aqueous sodium silicate solution (A1), 10 parts by weight of aqueous potassium silicate solution (A2), 5 parts by weight of aqueous lithium silicate solution (A3), 0.5 part by weight of γ-aminopropyltrimethoxysilane (B2), and 29.5 parts by weight of water were mixed to obtain surface strengthening agent 4. ·Surface strengthening agent 5 (A1) 55 parts by weight of an aqueous sodium silicate solution, (A2) 10 parts by weight of an aqueous potassium silicate solution, (A3) 5 parts by weight of an aqueous lithium silicate solution, (B1) 0.1 part by weight of N-β(aminoethyl)-γ-aminopropyltrimethoxysilane, and 29.9 parts by weight of water were mixed to obtain Surface Strengthening Agent 5. · Surface Strengthening Agent 6 (A1) 55 parts by weight of an aqueous sodium silicate solution, (A2) 10 parts by weight of an aqueous potassium silicate solution, (A3) 5 parts by weight of an aqueous lithium silicate solution, (B1) 5 parts by weight of N-β(aminoethyl)-γ-aminopropyltrimethoxysilane, and 25 parts by weight of water were mixed to obtain Surface Strengthening Agent 6. · Surface Strengthening Agent 7 (A1) 55 parts by weight of an aqueous sodium silicate solution, (A2) 10 parts by weight of an aqueous potassium silicate solution, (A3) 5 parts by weight of an aqueous lithium silicate solution, (B1) 8 parts by weight of N-β(aminoethyl)-γ-aminopropyltrimethoxysilane, and 22 parts by weight of water were mixed to obtain Surface Strengthening Agent 7. · Surface Strengthening Agent 8 (A1) 30 parts by weight of an aqueous sodium silicate solution, (A2) 30 parts by weight of an aqueous potassium silicate solution, (A3) 10 parts by weight of an aqueous lithium silicate solution, (B1) 0.5 part by weight of N-β(aminoethyl)-γ-aminopropyltrimethoxysilane, and 29.5 parts by weight of water were mixed to obtain Surface Strengthening Agent 8. · Surface Strengthening Agent 9 (A1) 20 parts by weight of an aqueous sodium silicate solution, (A2) 50 parts by weight of an aqueous potassium silicate solution, (B1) 0.5 part by weight of N-β(aminoethyl)-γ-aminopropyltrimethoxysilane, and 29.5 parts by weight of water were mixed to obtain Surface Strengthening Agent 9. · Surface Strengthening Agent 10 (A1) 70 parts by weight of a sodium silicate solution and 30 parts by weight of water were mixed to obtain Surface Strengthening Agent 10. · Surface Strengthening Agent 11 (A1) 55 parts by weight of an aqueous sodium silicate solution, (A2) 10 parts by weight of an aqueous potassium silicate solution, (A3) 5 parts by weight of an aqueous lithium silicate solution, and 30 parts by weight of water were mixed to obtain Surface Strengthening Agent 11.

[0047] <Preparation of Reinforcing Agent> · Reinforcing Agent 1 To 100 parts by weight of a 15% aqueous calcium nitrite solution prepared by dissolving calcium nitrite in water, 0.1 part by weight of (B1) N-β(aminoethyl)-γ-aminopropyltrimethoxysilane was added and stirred to obtain Reinforcing Agent 1. · Reinforcing Agent 2 To 100 parts by weight of a 15% aqueous calcium nitrite solution prepared by dissolving calcium nitrite in water, 0.1 part by weight of (B2) γ-aminopropyltrimethoxysilane was added and stirred to obtain Reinforcing Agent 2. · Reinforcing Agent 3 100 parts by weight of a 15% aqueous calcium nitrite solution prepared by dissolving calcium nitrite in water was used as Reinforcing Material 3.

[0048] <Test Example [I]> On the substrate [I] (standard mortar: 100×100×20 mm), Surface Reinforcing Agents 1 to 11 were each applied by brush coating at an application rate of 0.2 kg / m 2 and cured at room temperature (23°C) for 7 days. The specimens were then used for the following evaluations. The results are shown in Table 1.

[0049] · Appearance evaluation The surface of the specimen was visually evaluated to assess the presence or absence of appearance abnormalities such as gloss unevenness and hue unevenness. The evaluation criteria were set as the following three levels (excellent: A > B > C: poor). A: Uniform finish with no abnormalities. B: Slight abnormalities are observed. C: Obvious abnormalities are observed.

[0050] · Abrasion resistance (surface strength) evaluation For the obtained specimens, in accordance with JIS K5600 5.9 abrasion resistance (abrasion wheel method), the weight loss after 500 rotations was observed using a Taber tester, an abrasion wheel CS-17, and a load of 1000 g. The evaluation was made by comparing with the weight loss of the untreated substrate [I]. The evaluation criteria were set as the following three levels (excellent: A > B > C: poor). A: Better than the untreated product B: Slightly better than the untreated product C: Equivalent to or worse than the untreated product

[0051] ·Water permeability evaluation Surface strengthening agents 1 to 11 were each applied to the above substrate [I] at an application rate of 0.2 Kg / m 2 by brush coating, and the specimens were cured at room temperature (23 °C) for 7 days. The water permeability was evaluated according to JIS A 6909 7.13 (Water permeability test Method B). The evaluation was made in comparison with an uncoated standard mortar plate. The evaluation criteria were set as the following three levels (excellent: A > B > C: poor). A: Small amount of water penetration B: Equivalent C: Large amount of water penetration

[0052]

Table 1

[0053] In Test Examples I-1 to I-9, the surface strengthening agents had good permeability, and good results were obtained in the aesthetic evaluation, abrasion resistance evaluation, and water permeability evaluation. In particular, in Test Examples I-2 to I-5, excellent results with an A judgment were obtained in all evaluations. On the other hand, in Test Examples I-10 to I-11, the permeability of the surface strengthening agents was poor and sufficient results could not be obtained.

[0054] <Test Example [II]> ·Substrate [II] Standard mortar (100 × 100 × 20 mm) was left standing in a 5% CO2 atmosphere for 60 days to be neutralized and used as the substrate. According to the combination of the reinforcing agent and the surface strengthening agent shown in Table 2, the reinforcing agent was applied to the above substrate [II] at an application rate of 0.1 Kg / m 2 by brush coating, cured at room temperature (25 °C, 60% Rh) for 24 hours, then the surface strengthening agent was applied at an application rate of 0.2 kg / m 2 by brush coating, and left standing for 30 minutes. After standing, the excess of Surface Strengthening Agent 1 was removed, then wiped with water, and cured at normal temperature (25 °C) for 7 days to be used as the specimen, and the following evaluations were carried out. The results are shown in Table 2.

[0055] ·Aesthetic evaluation The aesthetic property was evaluated in the same manner as in Test Example [I]. ·Abrasion resistance evaluation Wear resistance was evaluated in the same manner as Test Example [I]. In the evaluation, it was compared with the wear loss of the untreated base material [II] and evaluated.

[0056] · Penetration depth evaluation The surface of the obtained test piece is ground every 1 mm in depth. Water is added so that the obtained grinding powder becomes 5%, and it is stirred for 10 minutes and left standing for 24 hours to extract sodium (Na) into 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 compared to the uncoated mortar, and the penetration depth is calculated. The evaluation criteria were set as the following three levels (excellent: A > B > C: inferior). A: 2 mm or more B: 1 mm or more and less than 2 mm C: Less than 1 mm

[0057]

Table 2

[0058] In Test Examples II-1 to II-3, the penetrability of the surface strengthening agent was good, and good results were obtained in the aesthetic evaluation, wear resistance evaluation, and penetrability evaluation. In particular, in Test Examples II-1 and II-2, the penetrability of the surface strengthening agent was excellent, and excellent wear resistance could be obtained even in the neutralized base material [II].

[0059] <Test Example [III]> Reinforcing agent 1 was applied to the above base material [II] by brush coating at an application rate of 0.1 Kg / m 2 and cured at room temperature (25°C, 60% Rh) for 24 hours. Then, the surface strengthening agents shown in Table 3 were each applied by brush coating at an application rate of 0.2 kg / m 2 and left standing for 30 minutes. After standing, the excess of the surface strengthening agent was removed, then wiped with water, and cured at normal temperature (25°C) for 7 days. Next, topcoat 1 (weak solvent type acrylic resin-based paint) was applied by brush coating at an application rate of 0.2 kg / m 2 and cured at normal temperature (25°C) for 7 days to obtain a test piece, and the following evaluation was carried out. The results are shown in Table 3.

[0060] · Adhesion evaluation For the obtained specimens, the adhesion was evaluated by the cross-cut tape method according to JIS K5600-5-6. The evaluation criteria were divided into the following four levels (excellent: A > B > C > D: poor). A: The area of the defective part is less than 10%. B: The area of the defective part is 10% or more and less than 30%. C: The area of the defective part is 30% or more and less than 50%. D: The area of the defective part is 50% or more.

[0061]

Table 3

[0062] In Test Examples III-1 to III-6, good results were obtained in the adhesion evaluation.

Claims

1. At least an alkali metal silicate, a water-soluble silane compound, and water are included, The alkali metal silicate includes sodium silicate, potassium silicate, and lithium silicate, The content of the sodium silicate in the alkali metal silicate (converted into active ingredient) is 30 to 98% by weight, the content of the potassium silicate in the alkali metal silicate (converted into active ingredient) is 1.5 to 50% by weight, and the content of the lithium silicate in the alkali metal silicate (converted into active ingredient) is 0.5 to 40% by weight. A concrete surface strengthening agent.

2. The mixing ratio of the sodium silicate and the potassium silicate is SiO 2 / (Na 2 O+K 2 2. The concrete surface strengthening agent according to claim 1, characterized in that the molar ratio of the component (I) to the component (O) is 5 / 1 to 1 / 1.

3. A concrete surface strengthening agent as described in claim 1, characterized in that the mixing ratio of the sodium silicate, potassium silicate and lithium silicate, SiO2 / (Na2O+K2O+Li2O) (molar ratio), is 5 / 1 to 1 / 1.

4. 2. The concrete surface strengthening agent according to claim 1, wherein the water-soluble silane compound includes an amino group-containing silane compound.

5. A method for reinforcing a concrete substrate, comprising applying the concrete surface reinforcing agent according to claim 1 to the concrete substrate.

6. 13. A method for reinforcing a concrete substrate, comprising applying a reinforcing agent containing a water-soluble calcium salt to the concrete substrate, and then applying the concrete surface reinforcing agent according to claim 1 to the concrete substrate.

7. 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 5 or 6, and then applying a topcoat material.

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