Exfoliation-resistant concrete structure and method for manufacturing the same

Abstract

To provide an exfoliation-resistant concrete structure, having sufficient exfoliation resistance performance of concrete fragments, and capable of visually confirming any deformation, such as cracks, in the concrete structure even when the deformation occurs.SOLUTION: An exfoliation-resistant concrete structure sequentially comprises: a concrete base material; a reinforcing layer sequentially comprising a polymer cement layer, a mesh sheet, and a polymer cement layer; and a topcoat layer, wherein the top coat layer is formed from a urethane-based painting material containing a water-based urethane resin and a (meth)acrylic resin, and a content of the water-based urethane resin is 50 mass% or more and less than 100 mass% based on 100 mass% of the total of the water-based urethane resin and the (meth)acrylic resin.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a concrete structure for preventing peeling and a method for manufacturing the same.

Background Art

[0002] In recent years, the aging of concrete structures has become a problem, and in particular, damage caused by the fall of concrete pieces due to such aging has become a problem. Regarding preventing the fall of the concrete pieces, for example, Patent Documents 1 and 2 disclose a method for preventing peeling of concrete pieces and a peeling prevention structure.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the conventional peeling prevention methods and peeling prevention structures, when a deformation such as a crack occurs in the concrete structure, it is difficult to visually judge, so inspection by a sounding test or the like is required, and there is a problem that the maintenance and management of the concrete structure become complicated.

[0005] Therefore, an object of the present invention is to provide a concrete structure for preventing peeling having sufficient performance for preventing peeling of concrete pieces and capable of visually confirming the deformation even when a deformation such as a crack occurs in the concrete structure, and a method for manufacturing the same.

Means for Solving the Problems

[0006] As a result of intensive studies by the present inventors, it has been found that the above problems can be solved according to the following configuration examples, and the present invention has been completed. The configuration examples of the present invention are as follows.

[0007] [1] A concrete base material, A reinforcing layer including a polymer cement layer, a mesh sheet, and a polymer cement layer in this order, A topcoat layer, Including them in this order, The topcoat layer contains an aqueous urethane resin and a (meth)acrylic resin, and the content of the aqueous urethane resin with respect to a total of 100% by mass of the aqueous urethane resin and the (meth)acrylic resin is 50% by mass or more and less than 100% by mass, and it is a layer formed from a urethane resin-based paint. A concrete structure for preventing peeling.

[0008] [2] The urethane resin-based paint further contains an associative thickener, and the concrete structure for preventing peeling according to [1].

[0009] [3] The mesh sheet is a vinylon mesh sheet, and the concrete structure for preventing peeling according to [1] or [2].

[0010] [4] The polymer cement layer contains at least one resin selected from the group consisting of an epoxy resin and a (meth)acrylic resin, and the concrete structure for preventing peeling according to any one of [1] to [3].

[0011] [5] A first step of forming a reinforcing layer including a polymer cement layer, a mesh sheet, and a polymer cement layer in this order on a concrete base material, A second step of applying a topcoat paint on the reinforcing layer to form a topcoat layer, Including, The topcoat paint contains an aqueous urethane resin and a (meth)acrylic resin, and is a water-based urethane resin-based paint in which the content of the aqueous urethane resin is 50% by mass or more and less than 100% by mass based on the total of 100% by mass of the aqueous urethane resin and the (meth)acrylic resin. Method for manufacturing a concrete structure with anti-peeling property.

Effect of the Invention

[0012] According to one embodiment of the present invention, there can be provided an anti-peeling concrete structure having sufficient anti-peeling performance for concrete pieces and capable of visually confirming the deformation even when a deformation such as a crack occurs in the concrete structure, and a method for manufacturing the same. Further, according to one embodiment of the present invention, an anti-peeling concrete structure can be manufactured by a method with low fire hazard and high safety for the human body and the like.

Mode for Carrying Out the Invention

[0013] ≪Anti-peeling Concrete Structure≫ The anti-peeling concrete structure according to the present invention (hereinafter also referred to as "this structure") includes a concrete base material, a reinforcing layer including a polymer cement layer, a mesh sheet, and a polymer cement layer in this order, and a topcoat layer in this order. The topcoat layer contains an aqueous urethane resin and a (meth)acrylic resin, and is a layer formed from a urethane resin-based paint in which the content of the aqueous urethane resin is 50% by mass or more and less than 100% by mass based on the total of 100% by mass thereof.

[0014] "Concrete" in the present invention is not particularly limited and refers to concrete in a broad sense (a material in which aggregates are hardened with a binder), which has been generally called concrete.

[0015] <Concrete Base Material> The concrete base material is not particularly limited, and examples thereof include concrete structures such as bridges, tunnels, elevated roads, railway structures, and other buildings (e.g., buildings, walls, chimneys, water tanks).

[0016] <Reinforcement layer> The reinforcement layer includes a polymer cement layer, a mesh sheet, and a polymer cement layer in this order. The thickness of the reinforcement layer is preferably 0.5 to 4.5 mm, more preferably 1.0 to 3.0 mm, from the viewpoint of easily forming the present structure having sufficient performance for preventing peeling of concrete pieces.

[0017] [Polymer cement layer] The polymer cement layer is a layer formed from polymer cement mortar. The polymer cement layer between the concrete base material and the mesh sheet and the polymer cement layer between the mesh sheet and the topcoat layer may be layers formed from the same polymer cement mortar or layers formed from different polymer cement mortars, but it is preferable that they are layers formed from the same polymer cement mortar. For example, polymer cement mortar may be applied to the concrete base material, and a mesh sheet may be pressed into the applied polymer cement mortar to form a reinforcement layer including a polymer cement layer, a mesh sheet, and a polymer cement layer in this order. In this case, it can be said that the polymer cement layers formed on both sides of the mesh sheet are substantially one layer.

[0018] The thickness of each polymer cement layer constituting the present structure is preferably 0.4 to 4.0 mm, more preferably 0.8 to 2.5 mm, from the viewpoint of forming a polymer cement layer having excellent adhesion to the concrete base material and the topcoat layer. The thickness of the polymer cement layer between the concrete base material and the mesh sheet and the thickness of the polymer cement layer between the mesh sheet and the topcoat layer may be the same or different. Each polymer cement layer may also be formed inside the mesh sheet. In this case, the thickness of each polymer cement layer refers to the length between the concrete base material and the surface of the mesh sheet (assuming the surface without the mesh of the mesh sheet), or the length between the surface of the mesh sheet (assuming the surface without the mesh of the mesh sheet) and the topcoat layer.

[0019] The polymer cement mortar is obtained by adding a polymer (resin) as a binder to cement, and it is preferably one with good workability when performing concrete unevenness adjustment and good workability when attaching the mesh sheet. Also, it is preferably one with good curability at low temperatures and capable of exhibiting strength within about 7 days after construction.

[0020] The polymer cement mortar usually contains water, cement, aggregate, resin, etc. In addition, to the polymer cement mortar, if necessary, conventional additives other than the above-mentioned water, cement, aggregate, and resin that have generally been used in polymer cement mortar (e.g., curing agents [e.g., epoxy resin curing agents], inorganic powders, water retention agents, fluidizing agents, setting regulators) may be blended. As for the conventional additives, each may be used alone or two or more kinds may be used.

[0021] As the cement, various cements generally adopted in polymer cement mortar can be used without particular limitation. Preferred examples of such cements include hydraulic cements. Examples of the hydraulic cement include Portland cement (including ordinary, early strength, ultra-early strength, medium heat, low heat, sulfate-resistant Portland cement, etc.), alumina cement, white cement, lime blended cement, blast furnace cement, colloidal cement, silica cement, fly ash cement, and slag cement. The cement may be used alone or two or more kinds may be used.

[0022] The cement used as a raw material for polymer cement mortar is usually in powder form, and its specific surface area is, for example, 3000 to 6000 g / cm when measured by the specific surface area test of JIS R 5201:2015. 2 That's it.

[0023] The blending amount of cement is generally 10 to 60% by mass, preferably 20 to 50% by mass, based on 100% by mass of the total amount of polymer cement mortar.

[0024] As the aggregate, various aggregates that have generally been adopted in polymer cement mortar can be used without particular limitation. Preferred examples of such aggregates include silica sand, river sand, crushed stone, crushed porcelain, crushed glass, glass beads, and lightweight aggregates. The aggregate may be used alone or in combination of two or more.

[0025] The size of the aggregate is preferably such that the residue remaining on a sieve with an opening of 0.3 mm, measured in accordance with JIS A 1102:2014, is 30% by mass or less, and the residue remaining on a sieve with an opening of 0.15 mm is 70% by mass or less. More preferably, the residue remaining on a sieve with an opening of 0.3 mm is 0% by mass, and the residue remaining on a sieve with an opening of 0.15 mm is 30% by mass or less.

[0026] The blending amount of the aggregate is generally 10 to 80% by mass, preferably 30 to 50% by mass, based on 100% by mass of the total amount of polymer cement mortar.

[0027] As the resin, various resins can be used without particular limitation. The resin may be used alone or in combination of two or more. The polymer cement mortar preferably contains at least one resin selected from the group consisting of an epoxy resin, a (meth)acrylic resin, and a cationic resin. From the viewpoint of excellent adhesion to the topcoat layer, etc., it is more preferable to contain at least one resin selected from the group consisting of an epoxy resin and a (meth)acrylic resin, and it is even more preferable to contain an epoxy resin. In particular, when the epoxy resin is contained in the polymer cement layer in contact with the topcoat layer, in the punching test described in the following examples, which is an index of the peeling prevention performance of the concrete pieces of the topcoat layer, it is possible to easily form a topcoat layer in which the maximum load and the maximum displacement satisfy the passing criteria.

[0028] In addition, the “(meth)acrylic resin” in this specification means an acrylic resin and / or a methacrylic resin. Hereinafter, “(meth)acrylic” means methacrylic and / or acrylic, and similar expressions (e.g., (meth)acrylate) also have the same meaning. Moreover, the resin used as a raw material of the polymer cement mortar may be in any form such as a solution, an emulsion, or a re-emulsified powder resin obtained by powdering an emulsion.

[0029] Examples of the epoxy resin include bisphenol A type epoxy resin, bisphenol F type epoxy resin, alkyl monoglycidyl ether, alkyl monoglycidyl ester, alkyl diglycidyl ether, alkyl diglycidyl ester, alkylphenol monoglycidyl ether, polyglycol monoglycidyl ether, and polyglycol diglycidyl ether. Note that the epoxy resin is a resin other than the cationic resin. Here, the alkyl group in the alkyl monoglycidyl ether or the like is preferably an alkyl group having 3 to 15 carbon atoms, for example. Examples of such an alkyl group preferably include alkyl groups such as a neopentyl group and a 2-ethylhexyl group.

[0030] In addition, when using an epoxy resin, it is preferable to use an amine-based compound as a curing agent. The amine compound is not particularly limited, but amine compounds other than tertiary amines such as aliphatic, alicyclic, aromatic, and heterocyclic amines are preferred.

[0031] Examples of the (meth)acrylic resin include resins using (meth)acrylic compounds such as ethyl (meth)acrylate, butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate as raw materials. The (meth)acrylic resin is a resin other than a cationic resin.

[0032] The cationic resin is preferably an organic polymer that can be dispersed and emulsified in water and can form a polymer film by drying. Examples of the cationic resin include (meth)acrylic acid alkyl ester (co)polymers, copolymers of styrene and (meth)acrylic acid alkyl esters, ethylene-vinyl acetate copolymers, ethylene-vinyl acetate-vinyl chloride copolymers, vinyl acetate-beoba copolymers, and resins obtained by introducing cationic groups (e.g., ammonium base, quaternary ammonium group) into base resins such as chloroprene rubber. When using a cationic resin, a nonionic surfactant or the like may be used to assist the emulsion stability.

[0033] The total blending amount of the resin and the curing agent is generally 2.0 to 20% by mass, preferably 3.0 to 10% by mass, based on 100% by mass of the total amount of the polymer cement mortar.

[0034] The amount of water used in the polymer cement mortar can be arbitrarily selected. However, from the viewpoints of sufficient kneading during the preparation of the polymer cement mortar and easy formation of a polymer cement layer having sufficient strength, it is preferably 30 to 70 parts by mass, (i.e., the water-cement ratio (W / C) is 30 to 70% by mass), more preferably 35 to 65 parts by mass, based on 100 parts by mass of cement.

[0035] [Mesh sheet] The mesh sheet is preferably a mesh sheet made of high-strength and high-elasticity fibers. Specific examples of the fibers include glass fiber, vinylon fiber, polyamide fiber, polyethylene fiber, polyphenylene fiber, poly(meth)acrylate fiber, polyarylate fiber, aramid fiber, and carbon fiber. Among these, a vinylon resin (vinylon mesh sheet) is preferred in terms of excellent load resistance and excellent wettability with polymer cement mortar.

[0036] As for the form of the fibers of the mesh sheet, there are mesh shapes such as biaxial, triaxial, and quadraxial. However, from the viewpoints of strength, cost, etc., a biaxial mesh sheet or a triaxial mesh sheet is preferred for the mesh sheet used in this structure.

[0037] The mesh size (mesh aperture) of the mesh sheet is preferably a mesh with a side length of 5 to 20 mm for each side of the mesh. When the mesh size of the mesh sheet is within the above range, the effect of preventing concrete spalling can be sufficiently exerted, and a structure excellent in the adhesion of each layer constituting this structure can be easily formed.

[0038] The thickness of the mesh sheet is preferably 100 to 500 μm, more preferably 150 to 400 μm, from the viewpoints such as sufficient exertion of the effect of preventing concrete spalling. Note that two or more mesh sheets may be used for this structure, but the thickness of the mesh sheet is the total thickness of the mesh sheets used for this structure.

[0039] <Top coat layer> The top coat layer is formed from a urethane resin-based paint containing an aqueous urethane resin and a (meth)acrylic resin, and the content of the aqueous urethane resin with respect to a total of 100% by mass is 50% by mass or more and less than 100% by mass. The thickness of the top coat layer is preferably 100 to 800 μm, more preferably 200 to 600 μm, from the viewpoints such as sufficient exertion of the effect of preventing concrete spalling and easy visual confirmation of deformation such as cracks in the concrete base material.

[0040] [Urethane resin-based paint] The urethane resin-based paint contains an aqueous urethane resin and a (meth)acrylic resin, and the content of the aqueous urethane resin with respect to a total of 100% by mass of the aqueous urethane resin and the (meth)acrylic resin is 50% by mass or more and less than 100% by mass. It can also be said that the urethane resin-based paint is an aqueous urethane resin-based paint.

[0041] [Aqueous urethane resin] The urethane resin-based paint contains an aqueous urethane resin. Examples of the aqueous urethane resin include a urethane resin having water or water as a main solvent or dispersion medium, or a urethane resin that is miscible with water (dilutable with water). More specifically, examples include a water-dispersion type urethane resin, a water-soluble urethane resin, and a self-emulsifying urethane resin. Among these, from the viewpoint of handling workability and the like, a water-dispersion type urethane resin is preferable, and a urethane resin emulsion or a urethane resin dispersion is more preferable. Such an aqueous urethane resin can be synthesized by a conventionally known method, for example, a solution polymerization method, a suspension polymerization method, an emulsion polymerization method, a seed polymerization method, a miniemulsion polymerization method, a microemulsion polymerization method, or a soap-free emulsion polymerization method. In addition to these, an aqueous urethane resin can also be obtained by a method of emulsifying a urethane resin by a known method, for example, phase inversion emulsification, D-phase emulsification, forced emulsification, gel emulsification, inversion emulsification, high-pressure emulsification, or the like. The aqueous urethane resin may be used alone or in combination of two or more.

[0042] As the aqueous urethane resin, a known aqueous urethane resin can be used without limitation and is not particularly limited. For example, a urethane resin emulsion or a urethane resin dispersion obtained by dispersing a urethane prepolymer obtained by reacting a raw material containing a polyisocyanate and a polyol in water can be mentioned.

[0043] The polyisocyanate is a compound having at least two isocyanate groups in one molecule, and examples thereof include aliphatic polyisocyanates, alicyclic polyisocyanates, araliphatic polyisocyanates, aromatic polyisocyanates, and derivatives of the polyisocyanate. The polyisocyanate may be used singly or in combination of two or more.

[0044] Examples of the aliphatic polyisocyanate include aliphatic diisocyanate compounds such as trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylene diisocyanate, 1,2-butylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, 1,5-pentamethylene diisocyanate, 1,6-hexamethylene diisocyanate), 2,4,4- or 2,2,4-trimethylhexamethylene diisocyanate, dimer acid diisocyanate, methyl 2,6-diisocyanatohexanoate; aliphatic triisocyanate compounds such as 2-isocyanatoethyl 2,6-diisocyanatohexanoate, 1,6-diisocyanato-3-isocyanatomethylhexane, 1,4,8-triisocyanatooctane, 1,6,11-triisocyanatoundecane, 1,8-diisocyanato-4-isocyanatomethyloctane, 1,3,6-triisocyanatohexane, 2,5,7-trimethyl-1,8-diisocyanato-5-isocyanatomethyloctane; are included.

[0045] Examples of the alicyclic polyisocyanate include Aliphatic cyclic diisocyanate compounds such as 1,3-cyclopentane diisocyanate, 1,3-cyclopentene diisocyanate, 1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate, 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate (isophorone diisocyanate), methylene bis(cyclohexyl isocyanate), methylcyclohexane diisocyanate, 4-methyl-1,3-cyclohexylene diisocyanate (hydrogenated TDI), 2-methyl-1,3-cyclohexylene diisocyanate, 1,3- or 1,4-bis(isocyanatomethyl)cyclohexane (hydrogenated xylylene diisocyanate), methylene bis(4,1-cyclohexane diyl) diisocyanate (hydrogenated MDI), norbornane diisocyanate; Aliphatic cyclic triisocyanate compounds such as 1,3,5-triisocyanatocyclohexane, 1,3,5-trimethylisocyanatocyclohexane, 2-(3-isocyanatopropyl)-2,5-di(isocyanatomethyl)-bicyclo(2.2.1)heptane, 2-(3-isocyanatopropyl)-2,6-di(isocyanatomethyl)-bicyclo(2.2.1)heptane, 3-(3-isocyanatopropyl)-2,5-di(isocyanatomethyl)-bicyclo(2.2.1)heptane, 5-(2-isocyanatoethyl)-2-isocyanatomethyl-3-(3-isocyanatopropyl)-bicyclo(2.2.1)heptane, 6-(2-isocyanatoethyl)-2-isocyanatomethyl-3-(3-isocyanatopropyl)-bicyclo(2.2.1)heptane, 5-(2-isocyanatoethyl)-2-isocyanatomethyl-2-(3-isocyanatopropyl)-bicyclo(2.2.1)-heptane, 6-(2-isocyanatoethyl)-2-isocyanatomethyl-2-(3-isocyanatopropyl)-bicyclo(2.2.1)heptane; are mentioned.

[0046] Examples of the aromatic aliphatic polyisocyanate include, for example, Aromatic aliphatic diisocyanate compounds such as methylene bis(4,1-phenylene) diisocyanate (MDI), 1,3- or 1,4-xylylene diisocyanate, ω,ω'-diisocyanato-1,4-diethylbenzene, 1,3- or 1,4-bis(1-isocyanato-1-methylethyl) benzene (tetramethylxylylene diisocyanate); Aromatic aliphatic triisocyanate compounds such as 1,3,5-triisocyanatomethylbenzene; etc. can be mentioned.

[0047] Examples of the aromatic polyisocyanate include, for example, Aromatic diisocyanate compounds such as m-phenylene diisocyanate, p-phenylene diisocyanate, 4,4'-diphenyl diisocyanate, 1,4- or 1,5-naphthalene diisocyanate, 2,4-tolylene diisocyanate (2,4-TDI), 2,6-tolylene diisocyanate (common name: 2,6-TDI), 4,4'-toluidine diisocyanate, 4,4'-diphenyl ether diisocyanate; Aromatic triisocyanate compounds such as triphenylmethane-4,4',4''-triisocyanate, 1,3,5-triisocyanatobenzene, 2,4,6-triisocyanatotoluene; Aromatic tetraisocyanate compounds such as 4,4'-diphenylmethane-2,2',5,5'-tetraisocyanate etc. can be mentioned.

[0048] Examples of the derivative of the polyisocyanate include, for example, dimer, trimer, biuret, allophanate, uretdione, uretoimine, isocyanurate, oxadiazinetrione, polyol (alcohol addition (adduct) body), polymethylene polyphenyl polyisocyanate (crude MDI, polymeric MDI), crude TDI of the polyisocyanate.

[0049] Examples of the polyol include diol compounds, polyether diol compounds, polyester diol compounds, polyether ester diol compounds, polycarbonate diol compounds, and aliphatic polyols having three or more hydroxyl groups. One type of the polyol may be used, or two or more types may be used.

[0050] Examples of the diol compound include aliphatic diols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, 1,2 - butanediol, 1,3 - butanediol, 2,3 - butanediol, 1,4 - butanediol, 2 - methyl - 1,3 - propanediol, 1,5 - pentanediol, neopentyl glycol, 3 - methyl - 1,5 - pentanediol, 2,4 - diethyl - 1,5 - pentanediol, 2,2,4 - trimethylpentane - 1,3 - diol, 1,6 - hexanediol, 2,5 - hexanediol, 1,5 - heptanediol, 1,7 - heptanediol, 1,8 - octamethylene diol, 2,2,4 - trimethyl - 1,3 - pentanediol, tricyclodecane dimethanol, 1,4 - cyclohexane dimethanol; alicyclic diols such as hydrogenated bisphenol A, hydrogenated xylylene diol, cyclohexane diol, cyclohexane dimethanol, hydrogenated dimer diol; aromatic or araliphatic diols such as bisphenol A, bis - hydroxyethyl terephthalate, catechol, resorcinol, hydroquinone, 1,3 - or 1,4 - xylylene diol; and the like.

[0051] Examples of the polyether diol compound include, for example, an alkylene oxide adduct of the diol compound, and a ring-opening (co)polymer of an alkylene oxide or a cyclic ether (e.g., tetrahydrofuran). Specific examples include polyethylene glycol, polypropylene glycol, a (block or random) copolymer of ethylene glycol - propylene glycol, glycol, polytetramethylene glycol, polyhexamethylene glycol, and polyoctamethylene glycol.

[0052] Examples of the polyester diol compound include, for example, a compound obtained by polycondensing a dicarboxylic acid such as adipic acid, succinic acid, sebacic acid, glutaric acid, maleic acid, fumaric acid, phthalic acid or its anhydride with the diol compound under conditions of an excess of hydroxyl groups. Specific examples include an ethylene glycol - adipic acid condensate, a 1,4 - butanediol - adipic acid condensate, a 1,6 - hexanediol - adipic acid condensate, an ethylene glycol - propylene glycol - adipic acid condensate, and a polylactone diol obtained by ring - opening polymerization of lactone using glycol as an initiator.

[0053] Examples of the polyether ester diol compound include, for example, a compound obtained using a diol containing an ether group (e.g., the diol compound or the polyether diol compound), the dicarboxylic acid or its anhydride, and an alkylene oxide. Specific examples include a polytetramethylene glycol - adipic acid condensate.

[0054] Examples of the polycarbonate diol compound include compounds represented by HO-R-(O-C(=O)-O-R)x-OH [where each R is independently a saturated fatty acid diol residue having 1 to 12 carbon atoms; x is the number of repeating units of the molecule, usually an integer of 5 to 50]. Such polycarbonate diol compounds can be obtained, for example, by a transesterification method in which a saturated aliphatic diol and a substituted carbonate (e.g., diethyl carbonate, diphenyl carbonate) are used and reacted under conditions where the hydroxyl groups are in excess, or by a method in which the saturated aliphatic diol and phosgene are used and reacted, etc.

[0055] Examples of the aliphatic polyol having three or more hydroxyl groups include glycerin, trimethylolpropane, pentaerythritol, and sorbitol.

[0056] When synthesizing the urethane prepolymer, conventionally known compounds that have been used in synthesizing urethane prepolymers, for example, compounds having two or more hydroxyl groups and one or more carboxyl groups in the molecule, compounds having two or more hydroxyl groups and one or more sulfonic acid groups in the molecule, may be used. One kind or two or more kinds of the conventionally known compounds may be used.

[0057] The synthesis of the urethane prepolymer can be carried out based on conventionally known methods.

[0058] When the aqueous urethane resin used as a raw material for the urethane resin-based paint is an aqueous urethane resin containing water (e.g., urethane resin emulsion, urethane resin dispersion), the solid content concentration of the aqueous urethane resin can be appropriately determined according to the purpose of use, etc., but is preferably 20 to 60% by mass. By using an aqueous urethane resin satisfying this concentration range, handling becomes easy and the concentration of the aqueous urethane resin in the urethane resin-based paint can be easily adjusted.

[0059] As the aqueous urethane resin, a resin obtained based on a conventionally known method may be used, or a commercially available product may be used. Specific examples of the commercially available product include the "Adekabontaiter" series manufactured by ADEKA CORPORATION.

[0060] The content of the solid content of the aqueous urethane resin with respect to 100% by mass of the total amount of the urethane resin-based paint is preferably 20 to 40% by mass, more preferably 20 to 30% by mass. Further, the content of the solid content of the aqueous urethane resin with respect to 100% by mass of the non-volatile content of the urethane resin-based paint is preferably 45 to 99.5% by mass, more preferably 50 to 99.0% by mass, and still more preferably 55 to 95% by mass. When the content of the aqueous urethane resin is within the above range, the present structure that can sufficiently exhibit the effect of preventing the peeling of concrete can be easily formed. Further, when the content of the aqueous urethane resin is within the above range, in particular, in the punching test described in the following examples, which is an index of the performance of preventing the peeling of concrete pieces in the topcoat layer, a topcoat layer in which the maximum load and the maximum displacement satisfy the passing criteria can be easily formed.

[0061] The non-volatile content of the urethane resin-based paint means the coating film (heating residue) after the urethane resin-based paint is sufficiently heated and dried. Specifically, the non-volatile content (%) of the urethane resin-based paint is measured in accordance with JIS K 5601-1-2:2008. Weigh 1 ± 0.2 g of the urethane resin-based paint into a flat-bottomed dish, spread it evenly using a wire of known mass, dry it at 23°C for 24 hours, and then heat it at a heating temperature of 105°C for 1 hour (under normal pressure). It can be calculated by measuring the heating residue and the mass of the wire. Note that this non-volatile content (%) is equal to the total amount of the solid content (components other than the dispersion medium and the solvent) of the raw material components used in the urethane resin-based paint.

[0062] The urethane resin-based paint contains an aqueous urethane resin and a (meth)acrylic resin described later, and the content of the aqueous urethane resin with respect to 100% by mass of the total of these is 50% by mass or more and less than 100% by mass, preferably 55 to 95% by mass, more preferably 57 to 85% by mass. When the content of the aqueous urethane resin is within the above range, a main structure capable of sufficiently exerting the effect of preventing the concrete from peeling can be easily formed. Further, when the content of the aqueous urethane resin is within the above range, particularly in the punching test described in the following examples, which is an index of the peeling prevention performance of the concrete pieces in the topcoat layer, a topcoat layer in which the maximum load and the maximum displacement satisfy the passing criteria can be easily formed.

[0063] [[(Meth)acrylic resin]] The urethane resin-based paint contains a (meth)acrylic resin. As the (meth)acrylic resin used as a raw material for the urethane resin-based paint, from the viewpoints that the urethane resin-based paint can be easily prepared and a peeling prevention concrete structure having desired physical properties can be easily formed, an aqueous dispersion of the (meth)acrylic resin, particularly an emulsion, is preferable.

[0064] Examples of the (meth)acrylic resin emulsion include conventionally known emulsions obtained by emulsion-polymerizing a polymerizable unsaturated monomer component containing one or more (meth)acryloyl compounds as essential components and, if necessary, one or more other polymerizable unsaturated monomers in one or more steps in the presence of water and a dispersion stabilizer.

[0065] Examples of the (meth)acryloyl compound include linear or branched alkyl (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, i-butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, and isostearyl (meth)acrylate; alicyclic alkyl (meth)acrylates such as cyclohexyl (meth)acrylate, methylcyclohexyl (meth)acrylate, t-butylcyclohexyl (meth)acrylate, isobornyl (meth)acrylate, and adamantyl (meth)acrylate; aralkyl (meth)acrylates such as benzyl (meth)acrylate; alkoxyalkyl (meth)acrylates such as 2-methoxyethyl (meth)acrylate and 2-ethoxyethyl (meth)acrylate; fluoroalkyl (meth)acrylates such as hexafluoro-i-propyl (meth)acrylate, perfluorooctylmethyl (meth)acrylate, and perfluorooctylethyl (meth)acrylate; phosphate group-containing (meth)acrylates such as (2-(meth)acryloyloxyethyl) acid phosphate and (2-(meth)acryloyloxypropyl) acid phosphate; N,N-dialkylaminoalkyl (meth)acrylates such as N,N-diethylaminoethyl (meth)acrylate; (meth)acrylamide; carboxyl group-containing (meth)acryloyl monomers such as (meth)acrylic acid and β-carboxyethyl (meth)acrylate; carbonyl group-containing (meth)acryloyl monomers such as acetoacetoxyethyl (meth)acrylate and diacetone (meth)acrylamide; epoxy group-containing (meth)acryloyl monomers such as glycidyl (meth)acrylate, β-methylglycidyl (meth)acrylate, 3,4-epoxycyclohexylmethyl (meth)acrylate, 3,4-epoxycyclohexylethyl (meth)acrylate, and 3,4-epoxycyclohexylpropyl (meth)acrylate; isocyanato group-containing (meth)acryloyl monomers such as isocyanatoethyl (meth)acrylate;Alkoxysilyl group-containing (meth)acryloyl monomers such as γ-(meth)acryloyloxypropyltrimethoxysilane and γ-(meth)acryloyloxypropyltriethoxysilane; Oxidation-curing group-containing (meth)acryloyl monomers such as dicyclopentenyl oxyethyl (meth)acrylate, dicyclopentenyl oxypropyl (meth)acrylate, and dicyclopentenyl (meth)acrylate; Heterocyclic group-containing (meth)acryloyl monomers such as 1,2,2,6,6-pentamethylpiperidyl (meth)acrylate and 2,2,6,6-tetramethylpiperidinyl (meth)acrylate; Quaternary ammonium base-containing (meth)acrylates such as 2-((meth)acryloyloxy)ethyltrimethylammonium chloride, 2-((meth)acryloyloxy)ethyltrimethylammonium bromide, (meth)acryloylaminopropyltrimethylammonium chloride, (meth)acryloylaminopropyltrimethylammonium bromide, tetrabutylammonium (meth)acrylate, tetramethylammonium (meth)acrylate, trimethylbenzylammonium (meth)acrylate, and 2-((meth)acryloyloxy)ethyltrimethylammonium dimethylphosphate; (Meth)acrylates having a polyoxyalkylene chain are mentioned.;

[0066] Examples of the other polymerizable unsaturated monomers include cyano group-containing compounds such as acrylonitrile and methacrylonitrile; vinyl ester compounds such as vinyl acetate and vinyl propionate; vinyl aromatic compounds such as styrene and α-methylstyrene; carboxyl group-containing polymerizable unsaturated monomers such as maleic acid, itaconic acid, and crotonic acid; carbonyl group-containing polymerizable unsaturated monomers such as acrolein, methacrolein, formylstyrene, vinyl alkyl ketones having 4 to 7 carbon atoms (e.g., vinyl methyl ketone, vinyl ethyl ketone, vinyl butyl ketone), and acetoacetoxyallyl ester; epoxy group-containing polymerizable unsaturated monomers such as allyl glycidyl ether; isocyanato group-containing polymerizable unsaturated monomers such as m-i-propenyl-α,α-dimethylbenzyl isocyanate; alkoxysilyl group-containing polymerizable unsaturated monomers such as vinyltrimethoxysilane and vinyltriethoxysilane; oxidation-curable group-containing polymerizable unsaturated monomers such as reaction products of epoxy group-containing polymerizable unsaturated monomers or hydroxyl group-containing polymerizable unsaturated monomers and unsaturated fatty acids; and fluorovinyl ethers such as fluoroalkyl trifluorovinyl ether and perfluoroalkyl trifluorovinyl ether.

[0067] When the (meth)acrylic resin is a copolymer of a (meth)acryloyl compound and other polymerizable unsaturated monomers, the content of the structural unit derived from the (meth)acryloyl compound relative to 100% by mass of all the structural units in the (meth)acrylic resin is preferably 20 to 99.9% by mass, more preferably 40 to 99.5% by mass.

[0068] The glass transition temperature (Tg) of the (meth)acrylic resin is not particularly limited, but is preferably 0 to 40°C from the viewpoint of further improving the adhesion to the reinforcing layer of the topcoat layer formed from the urethane resin-based paint. The glass transition temperature can be measured by a differential scanning calorimeter (DSC).

[0069] The content of the solid component in the emulsion is preferably 30% by mass or more, more preferably 35% by mass or more, preferably 70% by mass or less, and more preferably 60% by mass or less from the viewpoints of the stability of the emulsion and the like.

[0070] The above-mentioned aqueous dispersion or emulsion is a dispersion in which a resin is dispersed in a dispersion medium containing water (hereinafter also referred to as "aqueous medium"). The aqueous medium is not particularly limited as long as it contains water, but the water content in the aqueous medium is preferably 50 to 100% by mass, more preferably 60 to 100% by mass.

[0071] The aqueous medium may contain a medium other than water. Examples of such a medium include acetone, methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, 2-methoxyethanol, 2-ethoxyethanol, 2-butoxyethanol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, diacetone alcohol, dioxane, ethylene glycol, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol monopropyl ether, and ethylene glycol monohexyl ether. These can be used alone or in combination of two or more.

[0072] The emulsion can be prepared, for example, by emulsifying a resin using a surfactant to form an emulsion. Also, an emulsion can be directly prepared by emulsion polymerization of the monomers forming the resin. The surfactant is not particularly limited and can be appropriately selected from anionic surfactants and nonionic surfactants, and may be one kind or two or more kinds.

[0073] As the (meth)acrylic resin, a (meth)acrylic resin obtained by manufacturing using a conventionally well-known method may be used, or a commercially available product may be used. Examples of the commercially available products include Mobinyl 6530 (manufactured by Nippon Coating Resin Co., Ltd.), Vinibran 2684 (manufactured by Nisshin Chemical Industry Co., Ltd.), Cybinol YC-455 (manufactured by Cyden Chemical Co., Ltd.), Cybinol EK-61 (manufactured by Cyden Chemical Co., Ltd.), and DXV-4051 (manufactured by VANORA).

[0074] The content of the solid content of the (meth)acrylic resin with respect to 100% by mass of the total amount of the urethane resin-based paint is preferably 1 to 25% by mass, more preferably 3 to 20% by mass. When the content of the (meth)acrylic resin is within the above range, a main structure that can sufficiently exhibit the effect of preventing peeling of concrete can be easily formed.

[0075] [Other components] The urethane resin-based paint may further contain other components such as an aqueous urethane resin and a resin other than the (meth)acrylic resin, a thickener, a pigment, a pigment dispersant, an antifoaming agent, a film-forming auxiliary agent, a surface conditioner (leveling agent), a curing agent, a silane coupling agent, a plasticizer, water, and a solvent, as long as the object of the present invention is not impaired. These other components may be used singly or in combination of two or more.

[0076] (Thickener) The urethane resin-based paint preferably contains a thickener. As the thickener, a thickener of a conventionally well-known thickener can be used, but from the viewpoint of easily forming a main structure that can sufficiently exhibit the effect of preventing peeling of concrete, it is preferably an associative thickener.

[0077] The associative thickener is not particularly limited as long as it is a component other than the aqueous urethane resin, and a conventionally well-known associative thickener can be used. Associative thickeners are usually polymers having hydrophilic groups and hydrophobic groups in the molecule, and exhibit a thickening effect by the association of the hydrophilic groups or the hydrophobic groups with each other, such as between molecules.

[0078] Examples of the hydrophilic groups of the associative thickener include nonionic hydrophilic groups such as polyoxyalkylene groups, and ionic hydrophilic groups (anionic hydrophilic groups such as carboxylate groups (-COO - ), sulfonate groups (-SO 3 - ), and cationic hydrophilic groups such as quaternary ammonium groups). Among these, nonionic hydrophilic groups are preferred as the hydrophilic groups.

[0079] Examples of the hydrophobic groups include functional groups with low polarity such as alkyl groups and phenyl groups, which may be substituted. Among these, alkyl groups are preferred. The alkyl group may be linear, branched, or cyclic. The number of carbon atoms of the alkyl group is preferably 4 to 30. Among the alkyl groups, branched alkyl groups are particularly preferred in terms of dispersibility in water and the like.

[0080] The associative thickener is preferably a urethane-based associative thickener. That is, it is preferably an associative thickener having a polyurethane backbone. Examples of the compounds used as raw materials for the polyurethane of the backbone include the compounds exemplified in the column of the aqueous urethane resin. Urethane-based associative thickeners can be classified into ester-based, ether-based, carbonate-based, etc. according to the type of polyol used as a raw material, and ether-based associative thickeners are more preferred. For example, in an ether-based associative thickener where the polyol used as a raw material is a polyether polyol, the polyether part of the polyether polyol becomes a hydrophilic group. When a polyisocyanate is used as a raw material for the urethane-based associative thickener, an aliphatic polyisocyanate is preferred as the polyisocyanate.

[0081] As the associative thickener, a thickener obtained based on a conventionally known method may be used, or a commercially available product may be used. Examples of the commercially available products include, as urethane-modified polyether-based associative thickeners, for example, SN thickener series such as SN thickener 612, 612NC, 619, 621N, 621TF, 623N, 624N, 625N, 627N, 629N, 660T, 665T manufactured by Sanshin Chemical Industry Co., Ltd.; Nopar series such as Nopar 700N, 710N, 3303 manufactured by Sanshin Chemical Industry Co., Ltd.; Adekanol UH140S, UH438, UH752, UH814 manufactured by ADEKA Corporation; Rheolate 288 manufactured by ELEMENTIS. In addition, examples of the commercially available products include, for example, Aquaflow XLS-530 commercially available from ASHLAND as a nonionic synthetic associative thickener.

[0082] When the urethane resin-based paint contains a thickener, the content of the thickener based on 100% by mass of the nonvolatile content of the urethane resin-based paint is preferably 0.5 to 5.0% by mass, more preferably 0.5 to 2.5% by mass. When the content of the thickener is within the above range, a main structure that can sufficiently exhibit the effect of preventing the peeling of concrete can be easily formed.

[0083] (Defoaming agent) The defoaming agent is preferably a material that can suppress the generation of foam during the production and painting of the urethane resin-based paint, or a material that can break the foam generated in the urethane resin-based paint. By using a defoaming agent, for example, the generation of bubble marks or pinholes in the topcoat layer can be suppressed, and a topcoat layer excellent in the performance of preventing the peeling of concrete pieces can be easily formed.

[0084] Examples of the defoaming agent include silicone-based defoaming agents, polymer-based (non-silicone-based) defoaming agents, and mineral oil-based defoaming agents.

[0085] When the urethane resin-based paint contains an antifoaming agent, the solid content of the antifoaming agent is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and preferably 2% by mass or less, more preferably 1.5% by mass or less, based on 100% by mass of the nonvolatile content of the urethane resin-based paint.

[0086] (Film-forming aid) Examples of the film-forming aid include conventionally known alcohols, glycol ethers, esters, etc. For example, alcohols having 1 to 3 carbon atoms such as isopropyl alcohol, 2,2,4-trimethylpentanediol, 2,2,4-trimethylpentanediol, benzyl alcohol, etc.; glycol ethers such as ethylene glycol diethyl ether, diethylene glycol diethyl ether, propylene glycol diethyl ether, dipropylene glycol diethyl ether, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, dipropylene glycol n-butyl ether, ethylene glycol monobenzyl ether, ethylene glycol monophenyl ether, etc.; esters such as 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate, 2,2,4-trimethylpentanediol diisobutyrate, etc.

[0087] When the urethane resin-based paint contains a film-forming aid, the content of the film-forming aid is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and preferably 15% by mass or less, more preferably 5% by mass or less, based on 100% by mass of the total amount of the urethane resin-based paint, from the viewpoints of excellent film-forming properties at low temperatures and easily forming a topcoat layer with excellent appearance.

[0088] (Water) The urethane resin-based paint has a low fire hazard and high safety for the human body, etc. Also, when forming a topcoat layer (this structure) in a highly airtight place such as a tunnel, etc., it is preferably containing water and more preferably an aqueous urethane resin-based paint, from the viewpoints that it can suppress the risks such as fire and adverse effects on the human body, etc.

[0089] When preparing the urethane resin-based paint, the raw materials such as aqueous urethane resin used may contain water. Therefore, when the urethane resin-based paint contains water, the water contained in the urethane resin-based paint may be only the water contained in the raw materials. However, from the viewpoints of making the preparation of the urethane resin-based paint easier and being able to easily obtain a urethane resin-based paint excellent in desired physical properties, etc., when preparing the urethane resin-based paint, it is preferable to blend water other than the water that may be contained in the raw materials such as aqueous urethane resin used when preparing the urethane resin-based paint. The water other than the water that may be contained in the raw materials is not particularly limited, and examples thereof include tap water, ion-exchanged water, deionized water, and the like.

[0090] When the urethane resin-based paint contains water, the content of water (including the water that may be contained in the raw materials used when preparing the urethane resin-based paint) with respect to 100% by mass of the total amount of the urethane resin-based paint is preferably 20 to 80% by mass, more preferably 40 to 70% by mass, and still more preferably 50 to 65% by mass. When the water content is within the above range, it is possible to enable painting with a thick film, and it is possible to easily obtain a urethane resin-based paint that is less likely to sag and has excellent painting workability.

[0091] Also, the content of the non-volatile matter in the urethane resin-based paint is preferably 20 to 80% by mass, more preferably 30 to 60% by mass, from the viewpoints of being able to easily obtain a urethane resin-based paint excellent in desired physical properties, etc., and it is preferable to use water or the like so that the content of such non-volatile matter is obtained.

[0092] [Preparation method of urethane resin-based paint] The preparation method of the urethane resin-based paint is not particularly limited. An aqueous urethane resin, optionally a (meth)acrylic resin, and optionally other components are added in an arbitrary order, and each component is mixed by known stirring and mixing means, and preferably dispersed or dissolved in water for preparation. As stirring and mixing means, for example, means using a paint shaker, high-speed disperser, sand grind mill, basket mill, ball mill, three-roll mill, Ross mixer, or planetary mixer can be mentioned.

[0093] ≪Method for manufacturing a concrete structure for preventing peeling≫ A preferred example of the manufacturing method of this structure includes a first step of forming a reinforcing layer including a polymer cement layer, a mesh sheet, and a polymer cement layer in this order on a concrete base material, and a second step of applying a topcoat paint (the aqueous urethane resin-based paint) on the reinforcing layer to form a topcoat layer. Further, this structure may be manufactured by previously forming a laminate of a polymer cement layer / mesh sheet / polymer cement layer / topcoat layer, applying a polymer cement mortar to the laminate on the concrete base material if necessary, and arranging the laminate after drying the applied polymer cement mortar if necessary.

[0094] Specific examples of the first step include a step of forming a reinforcing layer by applying a polymer cement mortar on a concrete base material, drying the applied polymer cement mortar if necessary, arranging a mesh sheet thereon, then applying a polymer cement mortar, and drying the applied polymer cement mortar if necessary, a step of previously forming a laminate of a polymer cement layer / mesh sheet or a laminate of a polymer cement layer / mesh sheet / polymer cement layer, arranging the laminate on a concrete base material after applying a polymer cement mortar to the laminate if necessary, and further applying a polymer cement mortar to the arranged laminate if necessary to form a reinforcing layer can be mentioned. In the latter step, a step of drying the applied polymer cement mortar if necessary may be included. Alternatively, a reinforcing layer including a polymer cement layer, a mesh sheet, and a polymer cement layer in this order may be formed by pressing a mesh sheet into the polymer cement mortar.

[0095] The application of the polymer cement mortar can be carried out by a coating method generally well known to those skilled in the art. For example, it can be applied by brush coating, roller coating, spray coating, scraper coating, etc.

[0096] The application amount of the polymer cement mortar can be appropriately selected according to the shape and use of the concrete base material, etc., and it is preferable to apply it so that the thickness of the formed polymer cement layer falls within the above range.

[0097] When applying the polymer cement mortar on the concrete base material, before the application, if necessary, the deteriorated parts of the concrete base material may be chiseled off, washed, or pretreated such as polished. Further, on the parts of the concrete base material to be protected against deterioration, if necessary, a primer may be applied as a base and cured, and then the convex parts may be shaved off or the concave parts may be plastered to perform unevenness correction, latency treatment, etc., and a cross-section repair treatment may be performed. Furthermore, if necessary, when there are cracks in the deteriorated parts or parts likely to deteriorate of the concrete base material, a crack injection material may be injected in advance, or a primer agent, a rust preventive agent, etc. may be applied.

[0098] The drying conditions of the polymer cement mortar are not particularly limited, but the drying temperature may be appropriately adjusted according to the polymer cement mortar used, etc., and room temperature drying or drying under heating may be mentioned. For example, when drying in a short time such as 10 seconds to 30 minutes is required, the drying temperature is, for example, 40 to 200 °C, preferably 60 to 160 °C.

[0099] The application of the topcoat paint can be carried out by a coating method generally well known to those skilled in the art. For example, it can be applied by brush coating, roller coating, spray coating, scraper coating, etc. Note that before applying the topcoat paint, surface treatment such as cleaning or polishing may be performed on the polymer cement layer as necessary.

[0100] The coating amount of the topcoat paint can be appropriately selected according to the shape and use of the concrete substrate, etc., and it is preferable to apply the paint so that the thickness of the formed topcoat layer falls within the above range. To form a topcoat layer with such a thickness, the topcoat paint may be applied at once, or it may be applied in two or more coats (the process of applying the topcoat paint, drying it, further applying the topcoat paint, and drying it is repeated).

[0101] After applying the topcoat paint, a topcoat layer can be formed by drying it at room temperature or using drying equipment. The drying temperature may be appropriately adjusted according to the topcoat paint used, etc. For example, when short-time drying such as 10 seconds to 30 minutes is required, it is, for example, 40 to 200 °C, preferably 60 to 160 °C. Also, when short-time drying is not required, it may be dried at room temperature, etc.

[0102] The manufacturing method of this structure can be applied, for example, to concrete structures such as bridges, tunnels, elevated roads, railway structures, and other buildings (e.g., buildings, walls, chimneys, water tanks), etc., but it is particularly preferably applied to construction in places with high airtightness such as inside tunnels.

Example

[0103] Hereinafter, the present invention will be described in more detail based on examples. However, the present invention is not limited to these examples.

[0104] [Preparation Examples 1 to 6] <Preparation of Urethane Resin-Based Paint> Urethane resin-based paint was prepared by adding each component described in Table 1 to a container according to the amounts (numerical values) described in Table 1 and stirring and mixing them. Note that the explanations of each component described in Table 1 are shown in Table 2. The numerical values of each component in Table 1 indicate parts by mass, respectively.

[0105]

Table 1

[0106]

Table 2

[0107] [Examples 1 - 2 and Comparative Examples 1 - 6] (1) Preparation of the concrete structure with anti - peeling property For a concrete paving slab (base material) of 300 mm×300 mm×60 mm (thickness) specified in JIS A 5371:2016, the construction was carried out in the order of applying the polymer cement mortar described in Table 3, pasting a vinylon mesh sheet, applying the polymer cement mortar again, and applying the urethane resin - based paint prepared above. Specifically, using a trowel, the polymer cement mortar described in Table 3 was applied to the base material in an amount of 1000 g / m 2 , and then a vinylon three - axis mesh sheet (mesh size (mesh pitch) is 10 mm on each side) was pasted. Further, on it, the same polymer cement mortar as above was applied in an amount of 1000 g / m 2 using a trowel so that the mesh of the vinylon three - axis mesh sheet could not be seen. After the applied polymer cement mortar was dried, the urethane resin - based paint prepared above was applied in an amount of 250 g / m 2 using a brush, and left standing for 24 hours under the conditions of a temperature of 23°C and a relative humidity of 50% to form a coating film. Then, on the formed coating film, the same urethane resin - based paint as the one used to form the coating film was further applied in an amount of 250 g / m 2 using a brush, and then dried for 7 days under the conditions of a temperature of 23°C and a relative humidity of 50% to form a top - coat layer, thereby preparing a concrete structure with anti - peeling property. In Comparative Example 5, a concrete structure with anti - peeling property was prepared in the same manner as above, except that the urethane resin - based paint was not applied. In Comparative Example 6, the polymer cement mortar was not applied. That is, an anti-peeling concrete structure was produced in the same manner as described above, except that the vinylon three-axis mesh sheet was placed on the base material and a urethane resin-based paint was applied thereon.

[0108] (2) Evaluation test · Punch-out test The anti-peeling property of the anti-peeling concrete structure produced above was evaluated in accordance with the "Punch-out test method for surface coating materials applied to prevent peeling of concrete pieces" of the Japan Society of Civil Engineers Standard JSCE-K533-2010. Specifically, the test was conducted using a cover (hereinafter referred to as "cover") of type name 300 (400 mm × 600 mm × 60 mm (thickness)), which is one type of cover of the upper cover type U-shaped gutter specified in JIS A 5372:2016. A circular core with a diameter of 100 mm was punched out from the central part of the cover using a concrete core drill. The core punching was in the direction from the back surface (the surface opposite to the surface to which the urethane resin-based paint is applied (hereinafter referred to as "construction surface")) toward the construction surface, and was performed to a depth of 55 mm from the back surface. Subsequently, after the surface treatment of the construction surface was performed using a diamond cup, the cover was immersed in water maintained at 23°C for 24 hours with the construction surface facing upward. Next, the upper part of the cover was pulled out of the water, and the water droplets on the construction surface were removed with a towel while the lower 30 mm of the cover was in a water-immersed state. Within 5 minutes after pulling the upper part of the cover out of the water, the urethane resin-based paint prepared above was applied to the central part of 400 mm × 400 mm of the construction surface with a trowel so that the dry film thickness was 600 to 700 μm. The above construction was performed while the lower 30 mm of the cover was in a water-immersed state. Thereafter, curing was performed at a temperature of 23°C for 28 days while the lower 30 mm of the cover was in a water-immersed state to obtain a test piece.

[0109] For the test piece obtained above, a test was conducted using a material testing machine (manufactured by A&D Company, Ltd., model "RTC-1350A") according to the following test method. With the surface of the test piece on which the coating film was formed facing downward, it was set on the fulcrum at a span of 450 mm, and it was confirmed that the fulcrum was not in contact with the coating film. A spherical seat was sandwiched at the center of the core and loaded so that a vertical and uniform load was applied. During the loading process, a load-displacement curve with the load on the vertical axis and the displacement of the test piece on the horizontal axis was recorded. The loading was first carried out at a speed of 1 mm / min until the concrete in the core part was destroyed. Then, after the initial load peak was confirmed, the loading was continued at 5 mm / min, and the maximum load that appeared thereafter was measured. After measuring the maximum load, the loading was terminated when the load decreased to about 50% of the maximum load. Note that three test pieces prepared under the same conditions were tested as a set.

[0110] In the above test, the loading was temporarily stopped at displacements of 10 mm, 20 mm, and 30 mm, the peeling range was marked on the test piece, and photographic records were taken. During this period, the test was terminated when the final load-bearing capacity was confirmed. When it was determined that the test piece still had load-bearing capacity at the 30-mm displacement point, the loading was continued and the test was carried out up to a maximum displacement of 50 mm. Based on the load and displacement stroke data obtained in the test, a load-displacement curve was plotted. The maximum load at displacements of 10 mm or more was determined for each of the three test pieces, and the average value P was calculated. The value obtained by rounding the second decimal place was used as the maximum load and shown in Table 3. Also, the displacement at the maximum load was determined for each of the three test pieces, the average value was calculated, and the value obtained by rounding the second decimal place was used as the maximum displacement and shown in Table 3. Note that the case where the maximum load (average value) was 1.7 kN or more was regarded as qualified. Also, the case where the maximum displacement (average value) was 10 mm or more was regarded as qualified.

[0111] ·Adhesion The anti-peeling concrete structure was horizontally placed still in an atmosphere of 23°C and 50% relative humidity. Adhesive was applied to a part of the center of the topcoat, and a 40 mm square steel jig for upper tension was gently placed on the center of the topcoat and adhered by lightly rubbing. A weight of 1 kg was placed on it, and the adhesive that protruded to the periphery was wiped off, and it was left standing for 24 hours. Then, the weight was removed, and along the periphery of the steel jig for upper tension adhered to the anti-peeling concrete structure, a square cut was made from the topcoat side to the anti-peeling concrete structure until reaching a depth of 1 mm from the base material surface. A steel jig for lower tension and a steel backing plate were attached to the steel jig for upper tension of the anti-peeling concrete structure with the cut. Using a material testing machine (manufactured by A&D Company, Ltd., model "RTC-1350A"), a tensile force with a loading rate of 1500 N / min was applied in a direction perpendicular to the topcoat surface of the anti-peeling concrete structure surface until the anti-peeling concrete structure broke, and the maximum tensile load T (N) when the anti-peeling concrete structure broke was obtained. The above test was conducted twice, and the average value of the maximum tensile load T (N) was calculated. The average value of the adhesion strength calculated by the following formula is shown in Table 3. In addition, when the average value of this adhesion strength is 1.5 N / mm 2 The above cases were regarded as qualified. Adhesion strength (N / mm 2 ) = Average value of T / 1600

[0112] · Crack detectability Cracks were generated in the base material of the anti-peeling concrete structure by hitting it with a wooden mallet from the base material side of the anti-peeling concrete structure. The crack detectability was evaluated based on whether cracks in the base material could be visually detected from the topcoat side of the anti-peeling concrete structure. The results are shown in Table 3. [Evaluation criteria] ○: Cracks can be clearly detected ×: Cracks cannot be detected

[0113]

Table 3

[0114] The polymer cement mortar described in Table 3 is as follows. · Sky Resin EPC-T (manufactured by Dainichi Kasei Co., Ltd.): Epoxy resin-based polymer cement mortar

Claims

1. A concrete base material, a reinforcing layer including a polymer cement layer, a mesh sheet, and a polymer cement layer in this order, a topcoat layer, are included in this order, the topcoat layer contains an aqueous urethane resin and a (meth)acrylic resin, and the content of the aqueous urethane resin with respect to 100% by mass in total of the aqueous urethane resin and the (meth)acrylic resin is 50% by mass or more and less than 100% by mass, and it is a layer formed from a urethane resin-based paint, A concrete structure for preventing peeling.

2. The concrete structure for preventing peeling according to claim 1, wherein the urethane resin-based paint further contains an associative thickener.

3. The concrete structure for preventing peeling according to claim 1, wherein the mesh sheet is a vinylon mesh sheet.

4. The concrete structure for preventing peeling according to any one of claims 1 to 3, wherein the polymer cement layer contains at least one resin selected from the group consisting of an epoxy resin and a (meth)acrylic resin.

5. A first step of forming a reinforcing layer including a polymer cement layer, a mesh sheet, and a polymer cement layer in this order on a concrete base material; a second step of applying a topcoat paint on the reinforcing layer to form a topcoat layer; are included, the topcoat paint contains an aqueous urethane resin and a (meth)acrylic resin, and the content of the aqueous urethane resin with respect to 100% by mass in total of the aqueous urethane resin and the (meth)acrylic resin is 50% by mass or more and less than 100% by mass, and it is an aqueous urethane resin-based paint, A method for manufacturing a concrete structure for preventing peeling.

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