JP5664520B2 - Concrete structure and manufacturing method thereof - Google Patents

Description

  The present invention relates to a concrete structure and a manufacturing method thereof, and more specifically, a concrete structure capable of easily detecting a crack when cracks occur in the concrete constituting the concrete structure, a manufacturing method thereof, and The present invention relates to a method for detecting cracks in concrete.

Concrete structures are widely used on the walls of buildings, tunnels, bridges, piers, abutments, piers, box culverts, parapets, railings, undersides of slabs, balconies, chimneys, concrete poles, tanks, frames, dikes, etc. Yes. The concrete structure deteriorates with age, and from the viewpoint of durability, the surface of the concrete structure in recent years has a protective layer such as an undercoat layer or an overcoat layer. (See Patent Document 1).
A typical deterioration phenomenon of a concrete structure is a crack due to an internal stress or the like. By early detection and repair of the crack, a decrease in strength or destruction of the concrete structure is suppressed to extend the life.

On the other hand, concrete having a so-called self-diagnosis function has been developed, in which abnormal stress is sensed and light is emitted itself before breakage due to cracking occurs (see Patent Document 2). This concrete is doped with an emission center (Ce ₂ O ₃ ) composed of one or more of rare earth elements or transition metals that emit light when electrons excited by mechanical energy return to the ground state in an inorganic base material (gerenite). It contains a stress-stimulated luminescent material.

JP-A-4-14537 JP 2003-137632 A

As described above, on the surface of the concrete structure, a film for improving durability and the like is formed. On the other hand, this film may not break at the same time as the occurrence of a crack, and the exact position of the cracked part Confirmation may be difficult.
An object of the present invention is to provide a concrete structure capable of easily detecting cracks when a crack is generated in a concrete base constituting the concrete structure, a manufacturing method thereof, and a crack detection method for concrete. It is.

The present inventors are a concrete structure in which at least two functional layers are formed on the surface of a concrete base, and when a crack occurs in the concrete base, the functional layer on the surface side covers the crack The present inventors have found a concrete structure in which the transmittance of ultraviolet rays is increased and the inner functional layer emits light by receiving ultraviolet rays.
The present invention is as follows.
1. A base made of concrete; a first layer formed on the surface side of the base; and a second layer formed on the surface side of the first layer, wherein the first layer is a polyacrylate or a cross-linked product thereof includes a polymer and a fluorescent brightening agent containing, the second layer, seen containing a polymer and an ultraviolet absorber containing an acrylic silicone resin or a crosslinked product or a fluorine-containing resin is measured according to JIS a 6021 The tensile break elongation of the film constituting the first layer is 50% or more higher than the tensile break elongation of the film constituting the second layer, and the tensile break elongation of the film constituting the first layer is from 100% to 2, A concrete structure having a tensile elongation at break of 10% to 200% of the film constituting the second layer .
2. 2. The concrete structure according to 1 above, wherein the first layer has a thickness of 50 to 3,000 μm, and the second layer has a thickness of 10 to 500 μm .
3. The concrete structure according to 1 or 2 above, wherein the polyacrylate is a copolymer obtained by using a (meth) acrylic acid ester compound having an ester part containing a hydrocarbon group having 4 to 10 carbon atoms .
4). The optical brightener is stilbene, benzimidazole, benzoxazole, naphthalimide, benzothiazole, naphthothiazole, dibenzothiophene-5,5-dioxide, rhodamine, coumarin, oxazine, biphenyl The concrete structure according to any one of 1 to 3 above, which is at least one selected from the group consisting of methine cyanines, pyrazolines, benzidines and carbostyrils .
5. The content ratio of the fluorescent brightening agent is the concrete structure according to any one of 1 to 4 above, which is 0.01 to 3 parts by mass when the polymer in the first layer is 100 parts by mass .
6). Any of 1 to 5 above, wherein the ultraviolet absorber is at least one selected from benzotriazoles, benzophenones, triazines, benzoxazinones, salicylic acid phenyl esters, hindered amines, indoles and azomethines . The concrete structure according to one item.
7). The content rate of the said ultraviolet absorber is a concrete structure as described in any one of said 1 thru | or 6 which is 0.5-5 mass parts when the polymer in the said 2nd layer is 100 mass parts .
8). The concrete structure according to any one of 1 to 7 above, further comprising an undercoat layer between the base and the first layer .
9. The concrete structure according to any one of 1 to 8, further comprising another layer between the first layer and the second layer .
10. A method for producing a concrete structure as described in 1 above, wherein a composition for forming a first layer containing polyacrylate and a fluorescent brightening agent is applied to the surface side of a base made of concrete, and then dried. The step of forming the first layer, and the second layer forming composition containing the acrylic silicone resin or fluorine-containing resin and the ultraviolet absorber are applied to the surface side of the first layer, and then dried. A method for producing a concrete structure comprising the step of forming a second layer.
11. A method for detecting cracks in a base portion of a concrete structure according to any one of the above 1 to 9 , wherein the surface of the concrete structure having the cracks is irradiated with ultraviolet rays, and the ultraviolet rays are broken by the cracks. The first crack is formed by transmitting the crack space part of the formed second layer or the thin part of the second layer stretched by cracks to reach the first layer arranged on the surface side of the crack part. A method for detecting cracks in concrete, characterized by causing a fluorescent whitening agent contained in an ultraviolet light receiving part in a layer to emit light.

According to the concrete structure of the present invention, when a crack is generated in the concrete base, the crack can be easily detected.
Tensile elongation at break of the film constituting the first layer, since 50% or more higher than the tensile elongation at break of the film constituting the second layer, when the cracking concrete base occurs, the surface side covering of cracking sites In the part, the second layer tends to break more easily than the first layer. Therefore, the second layer covering the surface side of the cracked portion is broken or thinned, thereby forming a local crack space or thinned portion, respectively. These parts have a lower concentration of ultraviolet absorbers than the normal second layer without any defects in the interior (concrete base), so if the surface of the concrete structure (second layer side surface) is irradiated with ultraviolet rays UV rays can be easily transmitted and can reach the first layer with a high dose. When the ultraviolet rays reach the first layer, the fluorescent brightening agent emits light. However, since the emission intensity increases at the crack covering portion of the first layer covering the surface side of the crack portion, the position of the crack can be easily set. Can be confirmed. If the second layer covering the cracked part is thinned locally, it may be judged that there is no defect in the inside in appearance, but it is irradiated with ultraviolet rays, and the thinned part is allowed to pass through. The light emission intensity obtained is higher than the light emission intensity in a portion other than the thin portion (portion without cracks). Therefore, cracks can be detected by irradiating ultraviolet rays regardless of the surface appearance of the concrete structure, and oversight of cracks can be reduced.
Moreover, according to the manufacturing method of the concrete structure of this invention, the 1st layer and 2nd layer in the surface of the base part which consist of concrete can be formed efficiently.
Furthermore, according to the method for detecting cracks in concrete according to the present invention, it is possible to smoothly check the position of cracks in a concrete base having cracks.

It is a schematic sectional drawing which shows an example of the concrete structure of this invention. It is a schematic sectional drawing which shows the other example of the concrete structure of this invention. It is a schematic sectional drawing which shows the other example of the concrete structure of this invention. It is a schematic sectional drawing which shows an example of the phenomenon which generate | occur | produced in the 1st layer and the 2nd layer when the crack generate | occur | produced in the concrete base in the concrete structure of this invention. It is a schematic sectional drawing which shows the other example of the phenomenon which generate | occur | produced in the 1st layer and the 2nd layer, when the crack generate | occur | produced in the concrete base part in the concrete structure of this invention. It is the schematic which shows the evaluation method of the concrete structure in an Example, (A) is sectional drawing which shows the slate board which has a groove | channel, (B) is sectional drawing which shows the laminated body formed by the Example, ( C) is a cross-sectional view showing that the slate plate is split in half along the groove, and (D) is a cross-section showing that the film is stretched by being subjected to a tensile test in the state of (C). FIG.

The present invention will be described in detail below.
In the present specification, “(meth) acryl” means acryl and methacryl, “(meth) acrylate” means acrylate and methacrylate, and “(co) polymer” means homopolymer and copolymer. .

The concrete structure of the present invention includes a base made of concrete (hereinafter also referred to as “concrete base”), a first layer formed on the surface side of the concrete base, and a surface side of the first layer. The first layer includes a polymer containing polyacrylate or a cross-linked product thereof (hereinafter referred to as “first polymer”) and a fluorescent brightening agent, and the second layer is an acrylic layer. It contains a polymer containing a silicone resin or a cross-linked product thereof or a fluorine-containing resin (hereinafter referred to as “second polymer”) and an ultraviolet absorber. The concrete structure of the present invention is preferably a wall of a building, a tunnel, a bridge, a pier, an abutment, a pier, a box culvert, a parapet, a railing, a floor slab, a balcony, a chimney, a concrete pole, a tank, a frame, a dike In such a structure, a functional layer including a first layer and a second layer is provided on the surface side of the concrete base.
Thus, the concrete structure of the present invention includes the specific first layer and the second layer on the surface of the concrete base. Therefore, in the concrete structure, when cracks occurred in the concrete base due to internal stress or the like, it was determined that the surface was normal regardless of whether or not the outermost surface of the concrete structure had changed. Even if it is a case, the position of a crack can be confirmed by irradiating an ultraviolet-ray. This principle will be briefly described. When cracking occurs in the concrete base, the first layer and the second layer are stretched and thinned in the surface side covering portion of the cracked portion, and in the preferred embodiment, only the second layer is broken. By cracking, the first layer covering the cracked portion is stretched without being broken, and the second layer is locally broken to form a crack space portion or thinned to form a thin wall portion. Alternatively, since there is no UV absorber in the thin-walled portion or the concentration is reduced, ultraviolet rays are easily transmitted through these portions. The fluorescent whitening agent can be caused to emit light by the ultraviolet rays that have reached the crack covering portion of the first layer that covers the crack portion. The first layer and the second layer in the concrete structure that does not have cracks on the inner side both have a small degree of change in thickness due to cracks. The absorber reduces the intensity of light emission derived from the fluorescent brightener from the first layer. In this way, it can be easily confirmed that cracks of the base made of concrete exist on the inner side of the portion showing high emission intensity by irradiation with ultraviolet rays.

  In the concrete structure of the present invention, the first layer and the second layer may be configured such that these layers are adjacent to each other as shown in FIGS. 1 and 2, or the first layer as shown in FIG. A configuration including another layer (intermediate layer) between 4 and the second layer 6 may be employed. Moreover, as shown in FIG. 2, the structure provided with the other layer (undercoat layer) 3 between the concrete bases 2 and the 1st layer 4 may be sufficient. Further, although not shown, a configuration in which another layer (an overcoat layer) is provided on the surface side of the second layer 6 may be employed.

FIG. 1 shows a concrete structure 1 including a concrete base 2, a first layer 4 formed on the surface of the concrete base 2, and a second layer 6 formed on the surface of the first layer 4. .
FIG. 2 shows a concrete base 2, another layer (undercoat layer) 3 formed on the surface of the concrete base 2, and a first layer formed on the surface of another layer (undercoat layer) 3. 4 is a concrete structure 1 including a second layer 6 formed on the surface of the first layer 4. In FIG. 2, the other layer (undercoat layer) 3 is assumed to be a single-layer type, but is not limited to this, and any of the two-layer type, the three-layer type, or the like is continuous. Also good.
3 shows the concrete base 2, the first layer 4 formed on the surface of the concrete base 2, the other layer (intermediate layer) 5 formed on the surface of the first layer 4, and the like. This is a concrete structure 1 including a second layer 6 formed on the surface of the layer (intermediate layer) 5. In FIG. 3, the other layer (intermediate layer) 5 is assumed to be a single-layer type, but is not limited to this, and any of the continuous layers may be a multi-layer type such as a two-layer type or a three-layer type. Good.
Although not shown, the concrete structure 1 of the present invention includes a concrete base 2, another layer (undercoat layer) 3 formed on the surface of the concrete base 2, and another layer (underlayer). The first layer 4 formed on the surface of the coating layer 3, the other layer (intermediate layer) 5 formed on the surface of the first layer 4, and the surface of the other layer (intermediate layer) 5. An aspect including the second layer 6 may also be adopted.
Moreover, when the concrete structure 1 of this invention is provided with an overcoat layer, it may be a single layer type, and may be a multilayer type such as a continuous two-layer type or a three-layer type.

  The concrete base 2 usually contains a cement-based inorganic material, an aggregate, a pozzolanic material, a thickener, a water reducing agent, an aggregate, and water, and if necessary, a fibrous reinforcement It is a part made of concrete obtained by placing and curing a cement composition containing an agent, an organic binder and the like. The components constituting this cement composition will be described later.

  The first layer 4 is a layer containing a first polymer and a fluorescent brightening agent, and is filled with a filler; plasticizer, antioxidant, anti-aging agent, coloring agent, preservative, fungicide, flame retardant, extinguishing agent. It is a layer that may contain additives such as foaming agents, film-forming aids, dispersants, anti-settling agents; And in this 1st layer 4, the fluorescent whitening agent is disperse | distributing by making the 1st polymer into a mother phase. In addition, when a filler, an additive, and the like are included, these are dispersed using the first polymer as a matrix.

The first polymer forms a film having excellent flexibility. Specifically, in the concrete structure of the present invention, when a crack is generated in the concrete base, the portion covering the crack is formed. A polymer that provides a first layer that stretches but does not break. As this first polymer, acrylic urethane resin and its cross-linked product, acrylic silicone resin and its cross-linked product, polyacrylate and its cross-linked product, polyurethane resin and its cross-linked product, etc. can be used. Contains acrylate or cross-linked product thereof . These components may be contained alone or in combinations of two or more.

As an acrylic urethane resin, an ester moiety has a hydrocarbon group having 1 to 18 carbon atoms, preferably 4 to 10 carbon atoms, and one hydrogen atom contained in this hydrocarbon group is substituted with a hydroxyl group. Examples thereof include resins obtained by reacting a group-containing (meth) acrylic ester compound with an isocyanate group-terminated urethane prepolymer.
Moreover, as a crosslinked product of acrylic urethane resin (hereinafter also referred to as “crosslinked acrylic urethane resin”), a reaction product obtained by reacting the above acrylic urethane resin with polyisocyanate; reacting acrylic polyol with polyisocyanate. And the like.

The acrylic polyol can be obtained by radical polymerization of an acrylic monomer having a hydroxyl group alone, or this acrylic monomer and another polymerizable monomer having an unsaturated carbon-carbon bond. Acrylic polyol can be used, and other polyester-modified acrylic polyols can be used.
The polyisocyanate is not particularly limited as long as it has two or more isocyanate groups. 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4′-diphenylmethane diisocyanate, 2 , 4'-diphenylmethane diisocyanate, 2,2'-diphenylmethane diisocyanate, 4,4'-diphenyl ether diisocyanate and the like; hexamethylene diisocyanate (HMDI), tetramethylene diisocyanate, 2-methyl-pentane-1,5-diisocyanate , Aliphatic diisocyanates such as 3-methyl-pentane-1,5-diisocyanate, lysine diisocyanate, trioxyethylene diisocyanate; xylylene-1,4-diisocyanate, xylylene Aro-aliphatic diisocyanates such as len-1,3-diisocyanate (XDI), tetramethylxylylene diisocyanate; isophorone diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated xylylene diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated tetramethylxylylene diisocyanate And alicyclic diisocyanates such as Nuureates and biurets of these compounds can also be used.

Acrylic silicone resins include (co) polymers obtained by radical polymerization of (meth) acrylic monomers having alkoxysilyl groups in the side chains; (meth) acrylic monomers having alkoxysilyl groups in the side chains. A copolymer obtained by radical polymerization of a monomer and another polymerizable monomer having an unsaturated carbon-carbon bond; unsaturated carbon-carbon in the presence of one of these (co) polymers A (meth) acrylic silicone graft resin obtained by radical polymerization of a polymerizable monomer having a bond; a (co) polymer containing a structural unit derived from a (meth) acrylic monomer, and a polyorganosiloxane A block polymer or a graft polymer obtained by reacting the above.
The other polymerizable monomer having an unsaturated carbon-carbon bond is not particularly limited as long as it is an unsaturated compound having radical polymerizability. For example, aromatic vinyl compounds, vinyl compounds having amino groups, vinyl compounds having amide groups, vinyl compounds having alkoxyl groups, conjugated diene compounds, maleimide compounds, vinyl ester compounds, vinyl ether compounds, vinyl compounds having glycidyl groups, Examples thereof include monoalkyl esters of unsaturated dicarboxylic acids and dialkyl esters of unsaturated dicarboxylic acids. These can be used alone or in combination of two or more.

  Examples of the crosslinked product of acrylic silicone resin (hereinafter also referred to as “crosslinked acrylic silicone resin”) include reaction products obtained by reacting the acrylic silicone resin with polyisocyanate.

  As polyacrylate, (co) polymer obtained by polymerizing a (meth) acrylic acid ester compound whose ester part contains a hydrocarbon group having 1 to 18 carbon atoms, preferably 4 to 10 carbon atoms; the ester part is carbon A copolymer obtained by polymerizing a (meth) acrylic acid ester compound containing a hydrocarbon group having 1 to 18 atoms and another polymerizable monomer having an unsaturated carbon-carbon bond; It is done. As the other polymerizable monomer having an unsaturated carbon-carbon bond, the compounds exemplified as the monomer used for forming the acrylic silicone resin can be used. As other polymerizable monomers, aromatic vinyl compounds, vinyl compounds having an amide group, and the like are preferable.

In addition, as a crosslinked product of polyacrylate (hereinafter also referred to as “crosslinked polyacrylate”), the above-described (meth) acrylic ester group contains a hydrocarbon group having 1 to 18 carbon atoms, preferably 4 to 10 carbon atoms. A reaction product obtained by reacting a copolymer obtained by polymerizing an acid ester compound with a (meth) acrylate having a glycidyl group and a compound having a hydroxyl group or an amino group; A copolymer obtained by polymerizing a (meth) acrylic acid ester compound containing a hydrocarbon group having 1 to 18 carbon atoms, preferably 4 to 10 carbon atoms, and a (meth) acrylate having a hydroxyl group) A reaction product obtained by reacting a compound having a glycidyl group with an unsaturated compound obtained by polymerizing a monomer containing a polyfunctional (meth) acrylate Containing - carbon bond (co) polymer; and the like.
Examples of the compound having a hydroxyl group, glycidyl group or amino group include glyoxal, ethylene glycol, (poly) ethylene glycol diglycidyl ether, (poly) propylene glycol diglycidyl ether, (di) glycerol polyglycidyl ether, polyglycerol poly A glycidyl ether, epichlorohydrin, ethylenediamine, etc. are mentioned.

  The polyurethane resin is not particularly limited as long as it has two or more urethane bonds in the molecular chain, and a polyol including a polyol having an unsaturated carbon-carbon bond, a polyisocyanate, and an optional use. And a polyurethane resin obtained by reacting with a chain extender.

  The polyol having an unsaturated carbon-carbon bond has at least one polymerizable unsaturated carbon-carbon bond and two or more hydroxyl groups. Specific examples thereof include hydroxyl group-containing polybutadiene, hydroxyl group-containing Examples thereof include hydroxyl group-containing diene polymers such as polypentadiene, hydroxyl group-containing polyhexadiene, and hydroxyl group-containing polybutadiene / polyisoprene. The position of the hydroxyl group in the hydroxyl group-containing diene polymer is not particularly limited. Accordingly, a diene polymer having hydroxyl groups at both ends of the molecular chain main chain, a diene polymer having hydroxyl groups at both the molecular chain side chain terminal and the molecular chain main chain terminal can be used.

As the polyisocyanate, the compounds exemplified above can be used.
Examples of the chain extender include low molecular weight polyols and low molecular weight polyamines.
Examples of the low molecular weight polyol include ethylene glycol, diethylene glycol, triethylene glycol, propanediol (1,2-propanediol, 1,3-propanediol, 2-methyl-1,3-propanediol, etc.), dipropylene glycol, Butanediol (1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 2,3-dimethyl-2,3-butanediol, etc.), neopentyl glycol, Diols such as pentanediol, hexanediol, heptanediol, octanediol, 1,6-cyclohexanedimethylol, aniline diol, bisphenol A diol; triols such as glycerin, trimethylolpropane, hexanetriol; pentaerythris Tall, tetraol or hexanol, etc. sorbitol. Examples of the low molecular weight polyamine include aliphatic polyamines such as ethylenediamine, propylenediamine, butylenediamine and hexamethylenediamine; alicyclic polyamines such as isophoronediamine and piperazine; aromatic polyamines and the like.

  The cross-linked polyurethane resin (hereinafter also referred to as “cross-linked polyurethane”) has a cross-linked structure formed by utilizing an unsaturated carbon-carbon bond portion derived from a polyol in the above-described polyurethane resin. be able to. Such a crosslinked structure can be formed by using, for example, a radical polymerization initiator, an organic sulfur compound, or the like. As a specific example of the crosslinked structure, polyurethane resins were reacted in the presence of a radical polymerization initiator such as an organic peroxide or an azo compound to directly bond unsaturated carbon-carbon bond portions derived from a polyol. Crosslinking structure: In the presence of a crosslinking agent such as an organic peroxide or an organic sulfur compound, polyurethane resins are reacted with each other, and unsaturated carbon-carbon bond portions derived from a polyol are derived from a crosslinking agent such as an organic sulfur compound. Cross-linked structure cross-linked via the structure portion to be used.

Moreover, as a crosslinked polyurethane, what was obtained using the isocyanate group terminal urethane prepolymer and the hardening | curing agent may be used.
As the isocyanate group-terminated urethane prepolymer, one obtained by reacting a polyol and a polyisocyanate can be used.
Examples of the polyol include one or more low molecular polyols such as ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, cyclohexanedimethanol, glycerin, 1,1,1-trimethylolpropane, and glutaric acid. , Adipic acid, pimelic acid, suberic acid, sebacic acid, terephthalic acid, isophthalic acid, dimer acid and other low-molecular carboxylic acids and oligomers with one or more condensation polymers, propionlactone, valerolactone, Polyester ether polyols such as ring-opening polymers such as caprolactone; polyethylene glycol, polypropylene glycol, polypropylene triol, polyglycerin, polytrimethylolpropane, polyhexanetriol, polybutanediol, poly Hydroxyphenyl methane, poly dihydroxyphenyl propane, polyether polyols such as polyoxytetramethylene oxide; polymer polyols; polycarbonate polyols; polybutadiene polyols, hydrogenated polybutadiene polyols; and the like.
As the polyisocyanate, the compounds exemplified above can be used.

  Examples of the curing agent used for forming the crosslinked polyurethane include polyamines having two or more amino groups, polyols having two or more hydroxyl groups, polymercaptans, and phenol resins.

  Among the polyamines, amine compounds having two amino groups include ethylenediamine, 1,2-propanediamine, 1,3-propanediamine, 1,4-butanediamine, 1,5-pentanediamine, 1,6- Hexanediamine, 1,7-heptanediamine, 1,8-octanediamine, 1,9-nonanediamine, 1,10-decanediamine, 1,12-dodecanediamine, 1,14-tetradecanediamine, 1,16-hexadecanediamine , Hexamethylenediamine, trimethylhexamethylenediamine, iminobispropylamine, methyliminobispropylamine, 1,5-diamino-2-methylpentane, isophoronediamine, 1,3-bisaminomethylcyclohexane, 1-cyclohexylamino-3 -Aminopropane, 3 Aliphatic diamines such as aminomethyl-3,3,5-trimethyl-cyclohexylamine, dimethyleneamine having a norbornane skeleton, and metaxylylenediamine (MXDA); 3,3′-dichloro-4,4′-diaminodiphenylmethane (MOCA) ), 4,4′-diaminodiphenylmethane, 2,4′-diaminodiphenylmethane, 3,3′-diaminodiphenylmethane, 3,4′-diaminodiphenylmethane, 2,2′-diaminobiphenyl, 3,3′-diaminobiphenyl, 2,4-diaminophenol, 2,5-diaminophenol, o-phenylenediamine, m-phenylenediamine, p-phenylenediamine, 2,3-tolylenediamine, 2,4-tolylenediamine, 2,5-tridiamine Rangeamine, 2,6-tolylenediamine, 3,4-toluene Aromatic diamines such as phenylenediamine and the like.

Among the polyamines, examples of the amine compound having three or more amino groups include diethylenetriamine, triethylenetetramine, tetraethylenepentamine, and pentaethylenehexamine.
As the polyamine, a ketimine in which the amino group in the exemplified compounds is blocked with a ketone or an aldimine blocked with an aldehyde can be used.

  The above exemplified compounds can be used as the polyol.

  Examples of the polymercaptans include polymercaptocarboxylic acid amides.

The first layer 4 may be formed on the surface of the concrete base 2 as shown in FIGS. 1 and 3, and the lower layer formed on the surface of the concrete base 2 as shown in FIG. 2. You may form in the surface of the coating layer 3 (after-mentioned). In the present invention, in any of these cases, the first polymer is particularly preferably a polyacrylate from the standpoints of substrate followability, durability, and the like.
In addition, when making the said 1st layer 4 act as a waterproofing layer, it is preferable that a 1st polymer | macromolecule is polyacrylate.

The fluorescent whitening agent is a component having an action of absorbing ultraviolet light and converting it into visible light.
Examples of the optical brightener include stilbenes, benzimidazoles, benzoxazoles, naphthalimides, benzothiazoles, naphthothiazoles, dibenzothiophene-5,5-dioxides, rhodamines, coumarins, oxazines, Biphenyls, methine cyanines, pyrazolines, benzidines, carbostyrils and the like can be mentioned. These compounds may be contained alone or in combinations of two or more.

Examples of the stilbenes include 4,4′-bis (triazol-2-yl) stilbene derivatives and bis (triazinylaminostilbene) disulfonic acid derivatives.
Examples of the biphenyls include 4,4′-bis (2-sulfostyryl) biphenyl salts, 4,4′-bis (4-chloro-3-sulfostyryl) biphenyl salts, and the like.
Examples of the naphthothiazoles include 2- (styrylphenyl) naphthothiazole derivatives.

  The content ratio of the optical brightener contained in the first layer 4 is preferably 0.01 to 3 parts by mass, more preferably 0.05 to 1.0 parts by mass with respect to 100 parts by mass of the first polymer. More preferably, it is 0.1-0.5 mass part. When the content of the fluorescent brightening agent is 0.01 to 3 parts by mass, the above-described action in the concrete structure of the present invention is sufficiently exhibited. That is, when ultraviolet rays reach the first layer containing the fluorescent whitening agent composed of the above compound, visible light having a wavelength of 400 to 450 nm is emitted with sufficient luminance, so that an abnormality in the concrete base 2 is easily detected. can do.

  As described above, the first layer 4 may contain a filler, thereby toughening the resulting film, reducing the adhesion of the film surface, and improving workability until the concrete structure is completed. Can be improved. The content of the filler is preferably 30 to 300 masses with respect to 100 mass parts of the first polymer from the viewpoint of the adhesion between the concrete base or undercoat layer and the first layer and the tensile elongation at break. Part, more preferably about 50 to 150 parts by mass. Examples of the filler include cinnabar, talc, calcium carbonate, kaolin, gypsum, diatomaceous earth, titanium oxide, and various portland cement, blast furnace cement, alumina cement, and other cements. These fillers may be included singly or in combinations of two or more.

  The thickness of the first layer 4 is preferably 50 to 3,000 μm, more preferably 100 to 2,000 μm, and still more preferably 500 to 1,500 μm, from the viewpoint of ground followability due to cracking and durability. is there.

  The tensile breaking elongation of the film constituting the first layer 4 is higher than the tensile breaking elongation of the film constituting the second layer 6 described later, and is 100% to 2,000%, more preferably 200% to 1,000%. More preferably, it is 200% to 500%. The tensile elongation at break is a measured value according to JIS A 6021 using a film having the preferred thickness.

  Next, the second layer 6 is a layer containing a second polymer and an ultraviolet absorber, and a filler; a plasticizer, an antioxidant, an anti-aging agent, a light stabilizer, a heat stabilizer, an antistatic agent, Water repellent, oil repellent, colorant, antiseptic, antifungal agent, flame retardant, antifoaming agent, film forming aid, dispersant, antisettling agent, etc .; may contain reticulated reinforcement Is a layer. And in this 2nd layer 6, the ultraviolet absorber is disperse | distributed by making 2nd polymer into a mother phase. In addition, when a filler, an additive, and the like are included, these are dispersed using the second polymer as a parent phase.

While the second polymer has flexibility, it forms a film that breaks when pulled to a certain extent. Specifically, in the concrete structure of the present invention, when cracks occur in the concrete base. And a polymer that provides a second layer that breaks or stretches in the portion covering both the cracked portion and the cracked coating portion in the first layer. As this second polymer, acrylic urethane resin and its cross-linked product, acrylic silicone resin and its cross-linked product, fluorine-containing resin, epoxy cured product and the like can be used. In the present invention, acrylic silicone resin or its cross-linked product is used. Or a fluorine-containing resin is included . These components may be contained alone or in combinations of two or more.

  When the second polymer is an acrylic silicone resin and a cross-linked product thereof, the above-described acrylic silicone resin and the cross-linked product can be applied.

  Fluorine-containing resins include polytetrafluoroethylene (PTFE), tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene / ethylene copolymer (ETFE), tetrafluoroethylene / hexafluoropropylene copolymer Copolymer (FEP), polyvinylidene fluoride (PVDF), polychlorotrifluoroethylene (PCTFE), fluoroethylene vinyl ether (vinyl ester) copolymer, resin in which some fluorine atoms of PTFE are substituted by functional groups (Modified PTFE) and the like.

The epoxy cured product is obtained by curing an epoxy compound having two or more epoxy groups with a curing agent.
Examples of the epoxy compound include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, orthocresol novolac type epoxy resin, alicyclic epoxy resin, aliphatic epoxy resin, diglycidyl etherified product of phenols, Examples include diglycidyl etherified products of alcohols.
Examples of the curing agent include polyfunctional phenols, amines, imidazoles, acid anhydrides, and phosphorus-containing compounds. Among these, the polyfunctional phenols include monocyclic bifunctional phenols hydroquinone, resorcinol, catechol, polycyclic bifunctional phenols bisphenol A, bisphenol F, naphthalenediols, biphenols, and halides thereof. And alkyl group-substituted products. Furthermore, novolak and resol which are polycondensates of these phenols and aldehydes can be used. Examples of the amines include aliphatic or aromatic primary amines, secondary amines, tertiary amines, quaternary ammonium salts and aliphatic cyclic amines, guanidines, urea derivatives, and the like.

The second layer 6 may be formed on the surface of the first layer 4 as shown in FIGS. 1 and 2, or may be formed on the surface of another layer (intermediate layer) 5 as shown in FIG. May be. In the present invention, in any of these cases, from the viewpoint of adhesion to the undercoat layer or the first layer, weather resistance, etc. when the undercoat layer is formed, the second polymer is an acrylic silicone resin and It is a fluorine-containing resin , and an acrylic silicone resin is particularly preferable.

The ultraviolet absorber is a compound having an absorption maximum in a wavelength range of 250 to 400 nm, preferably 300 to 400 nm.
Examples of the ultraviolet absorber include benzotriazoles, benzophenones, triazines, benzoxazinones, salicylic acid phenyl esters, hindered amines, indoles, and azomethines. These compounds may be contained alone or in combinations of two or more.

  Examples of the benzotriazoles include 2- (2′-hydroxy-5′-methacryloyloxyethoxyphenyl) benzotriazole, 2- (5′-acryloyloxyethoxy-2′-hydroxyphenyl) benzotriazole, 2- (2 ′ -Hydroxy-5'-methylphenyl) benzotriazole, 2,2'-methylenebis [6- (2H-benzotriazol-2-yl) -1,4-dihydroxybenzene], 2,2'-methylenebis [6- ( 2H-benzotriazol-2-yl) -4- (hydroxymethyl) phenol], 2,2′-methylenebis [6- (2H-benzotriazol-2-yl) -4- (2-hydroxyethyl) phenol, 2 -(2H-benzotriazol-2-yl) -p-cresol, 2- (2H-benzo Riazol-2-yl) -4,6-bis (1-methyl-1-phenylethyl) phenol, 2- [5-chloro (2H) -benzotriazol-2-yl] -4-methyl] -6- ( tert-butyl) phenol, 2,4-di-tert-butyl-6- (5-chlorobenzotriazol-2-yl) phenol, 2- (2H-benzotriazol-2-yl) -4,6-di- and tert-pentylphenol, 2- (2H-benzotriazol-2-yl) -4- (1,1,3,3-tetramethylbutyl) phenol, and the like.

  Examples of the benzophenones include 2-hydroxy-4- (2′-methacryloyloxyethoxy) benzophenone, 2-hydroxy-4- (2′-acryloyloxyethoxy) benzophenone, 2,4-dihydroxybenzophenone, and 2-hydroxy-4. -Methoxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy-2'-carboxybenzophenone, 2-hydroxy-4-methoxy-5-sulfobenzophenone trihydrate, 2,2 '-Dihydroxy-4,4'-dimethoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2-hydroxy-4-octadecyloxybenzophenone, sodium 2,2'-dihydroxy-4,4'-dimethoxy-5- Sulfobe Zophenone, 2,2 ′, 4,4′-tetrahydroxybenzophenone, 4-dodecyloxy-2-hydroxybenzophenone, 5-chloro-2-hydroxybenzophenone, resorcinol monobenzoate, 2,4-dibenzoyl resorcinol, 4 , 6-dibenzoylresorcinol, hydroxydodecylbenzophenone, 2,2′-dihydroxy-4 (3-methacryloxy-2-hydroxypropoxy) benzophenone, and the like.

  Examples of the triazines include 2- (4,6-diphenyl-1,3,5-triazin-2-yl) -5-hexyloxyphenol and 2- (4,6-diphenyl-1,3,5-triazine. -2-yl) -5-methyloxyphenol, 2- (4,6-diphenyl-1,3,5-triazin-2-yl) -5-ethyloxyphenol, 2- (4,6-diphenyl-1) , 3,5-triazin-2-yl) -5-propyloxyphenol, 2- (4,6-diphenyl-1,3,5-triazin-2-yl) -5-butyloxyphenol, 2- (4 , 6-bis (2,4-dimethylphenyl) -1,3,5-triazin-2-yl) -5-hexyloxyphenol and the like.

  Examples of the benzoxazinones include 2,2′-p-phenylenebis (4H-3,1-benzoxazin-4-one), 2,2′-p-phenylenebis (6-methyl-4H-3, 1-benzoxazin-4-one), 2,2′-p-phenylenebis (6-chloro-4H-3,1-benzoxazin-4-one), 2,2′-p-phenylenebis (6- Methoxy-4H-3,1-benzoxazin-4-one), 2,2′-p-phenylenebis (6-hydroxy-4H-3,1-benzoxazin-4-one), 2,2 ′-( Naphthalene-2,6-diyl) bis (4H-3,1-benzoxazin-4-one), 2,2 ′-(naphthalene-1,4-diyl) bis (4H-3,1-benzoxazine-4) -One), 2,2 '-(thiophene-2, -Diyl) bis (4H-3,1-benzoxazin-4-one), 2,2 '-(furan-2,5-diyl) bis (4H-3,1-benzoxazin-4-one), 2 , 2 ′-(pyrrole-2,5-diyl) bis (4H-3,1-benzoxazin-4-one) and the like.

  Examples of the salicylic acid phenyl esters include phenyl salicylate, p-tert-butylphenyl salicylate, and p-octylphenyl salicylate.

  Examples of the hindered amines include glycerol ester compounds, α, β-unsaturated carboxylic acid ester compounds, carboxylic acid ester compounds, and dicarboxylic acid ester compounds. Specific examples include bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, bis (1,2, 2,6,6-pentamethyl-4-piperidyl) [{3,5-bis (1,1-dimethylethyl) -4-hydroxyphenyl} methyl] butyl malonate, 1- [2- {3- (3 , 5-Di-tert-butyl-4-hydroxyphenyl) propionyloxy} ethyl] -4- {3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxy} -2,2,6 , 6-tetramethylpiperidine, 8-acetyl-3-dodecyl-7,7,9,9-tetramethyl-1,3,8-triasaspiro [4,5] decane-2,4-dione, 4-benzoyloxy -2, 2, 6 6-tetramethylpiperidine, dimethyl-1- (2-hydroxyethyl) -4-hydroxy-2,2,6,6-tetramethylpiperidine polycondensate, poly [[6- (1,1,3, succinate) 3-tetramethylbutyl) imino-1,3,5-triazine-2,4-diyl] [(2,2,6,6-tetramethyl-4-piperidyl) imino] hexamethylene [[2,2,6 , 6-tetramethyl-4-piperidyl] imino]], poly [6-morpholino-s-triazine-2,4-diyl] [(2,2,6,6-tetramethyl-4-piperidyl) imino]- Hexamethylene [(2,2,6,6-tetramethyl-4-biperidyl) imino]], 2- (3,5-di-tert-butyl-4-hydroxybenzyl) -2-n-butylmalonate bis (1, 2, 2, 6, 6 Pentamethyl-4-piperidyl), tetrakis (2,2,6,6-tetramethyl-4-piperidyl) -1,2,3,4-butanetetracarboxylate, tetrakis (1,2,2,6,6) -Pentamethyl-4-piperidyl) -1,2,3,4, -butanetetracarboxylate, 1,2,3,4-butanetetracarboxylic acid and 1,2,2,6,6-pentamethyl-4- A condensate of piperidinol and tridecyl alcohol, a condensate of 1,2,3,4-butanetetracarboxylic acid and 2,2,6,6-tetramethyl-4-piperidinol and tridecyl alcohol, 1,2, 3,4-butanetetracarboxylic acid, 1,2,2,6,6-pentamethyl-4-piperidinol and β, β, β, β-tetramethyl-3,9- (2,4,8,10-tetra Oxaspi Condensation with [5,5] undecane) diethanol, 1,2,3,4-butanetetracarboxylic acid, 2,2,6,6-tetramethyl-4-piperidinol and β, β, β, β-tetra Condensate with methyl-3,9- (2,4,8,10-tetraoxaspiro [5,5] undecane) diethanol, N, N′-bis (3-aminopropyl) ethylenediamine · 2,4-bis [N-butyl-N- (1,2,2,6,6-pentamethyl-4-piperidyl) amino] -6-chloro-1,3,5-triazine condensate, dibutylamine 1,3,5- Triazine / N, N-bis (2,2,6,6-tetramethyl-4-piperidyl-1,6-hexamethylenediamine / N-2,2,6,6-tetramethyl-4-piperidyl) butylamine Polycondensate, 1, 2, 2, 6, Examples include 6-tetramethyl-4-piperidyl-methacrylate and 2,2,6,6-tetramethyl-4-piperidyl-methacrylate.

  Examples of the indoles include 5-indoleol, 4-aminoindole, 4-methoxyindole, 4-hydroxy-5-methoxyindole, 6-hydroxy-7-methoxyindole, 5-hydroxy-6-methoxyindole, 5- Examples thereof include hydroxyindole and 4-hydroxyindole.

  Examples of the azomethines include 3-[(phenylimino) methyl] -2,4-dihydroxyquinoline, 3-[(3′-methylphenylimino) methyl] -2,4-dihydroxyquinoline, 3-[(4 ′ -Propylphenylimino) methyl] -2,4-dihydroxyquinoline, 3-[(3'-methoxyphenylimino) methyl] -2,4-dihydroxyquinoline, 3-[(3'-ethoxyphenylimino) methyl]- 2,4-dihydroxyquinoline, 3-[(3′-chlorophenylimino) methyl] -2,4-dihydroxyquinoline, 3-[(2 ′, 4′-dimethylphenylimino) methyl] -2,4-dihydroxyquinoline Etc.

  The content ratio of the ultraviolet absorber contained in the second layer 6 is preferably 0.5 to 5 parts by mass, more preferably 1 to 3 parts by mass, further preferably 1 to 100 parts by mass of the second polymer. ˜2 parts by mass. The said effect | action in the concrete structure of this invention is fully exhibited as content of a ultraviolet absorber is 0.5-5 mass parts. That is, when the crack is generated in the concrete base portion, when the second layer 6 is stretched and thinned, the concentration of the ultraviolet absorber in the thin portion is reduced, so that the ultraviolet transmittance in the thin portion is improved. be able to. And the transmitted ultraviolet-ray can be made to reach | attain a 1st layer, and light emission of the fluorescent whitening agent contained in a 1st layer can be obtained.

  The second layer 6 may include a filler as described above. As the filler, the components exemplified as the filler that can be contained in the first layer 4 can be used.

  The thickness of the second layer 6 is preferably 10 to 500 μm, more preferably 30 to 200 μm, more preferably from the viewpoint of adhesion to the undercoat layer or the first layer when the undercoat layer is formed, and weather resistance. Preferably it is 60-150 micrometers.

  The tensile breaking elongation of the film constituting the second layer 6 is lower than the tensile breaking elongation of the film constituting the first layer 4, and is 10% to 200%, more preferably 10% to 150%, and still more preferably 30. % To 100%. The tensile elongation at break is a measured value according to JIS A 6021 using a film having the preferred thickness.

  The concrete structure 1 of the present invention can include the undercoat layer 3 or the intermediate layer 5 as described above (see FIGS. 2 and 3). Further, an overcoat layer can be further provided on the surface of the second layer (not shown). Preferred compositions of the undercoat layer 3, the intermediate layer 5 and the overcoat layer are described later. The tensile break elongation of the film constituting the undercoat layer 3, the tensile break elongation of the film constituting the first layer 4, It is preferable that the tensile break elongation of the film constituting the intermediate layer 5, the tensile break elongation of the film constituting the second layer 6, and the tensile break elongation of the film constituting the overcoat layer are successively reduced. In particular, the effect of the present invention is sufficiently exerted when the difference in tensile elongation at break between the films constituting two adjacent layers is 50% or more, more preferably 90% or more, and even more preferably 150% or more. . In addition, the tensile break elongation of each film | membrane which comprises two adjacent layers may be the same, However, In this case, the tensile break elongation of each film | membrane which comprises three adjacent layers is not the same. That is, in a concrete structure 1 that is not shown, and includes a concrete base 2, an undercoat layer 3, a first layer 4, an intermediate layer 5, and a second layer 6, for example, the undercoat layer 3, the first layer 4, and The films constituting the intermediate layer 5 do not have the same tensile breaking elongation, and the films constituting the first layer 4, the intermediate layer 5, and the second layer 6 do not have the same tensile breaking elongation. The undercoat layer 3 improves the smoothness of the surface of the concrete base 2 as will be described later. However, since the constituent components of the undercoat layer 3 often penetrate into the recesses, In particular, the tensile elongation at break of the film constituting the undercoat layer 3 can be ignored.

The undercoat layer 3 can be made of a polymer film conventionally formed as a “primer layer” or the like on the outermost surface of a base made of concrete. Since the concave part, the convex part, the groove part, etc. are usually formed on the outermost surface of the concrete base 2 obtained using the cement composition, the smoothness of the surface of the concrete base 2 is improved. An undercoat layer 3 can be provided on the surface of the concrete base 2 in order to suppress the intrusion of carbon dioxide gas, chloride ions, water, etc. affecting the concrete (see FIG. 2). The undercoat layer 3 is, for example, a vinyl ester resin using vinyl acetate or the like, an ethylene / vinyl acetate copolymer, a polyacrylate or a crosslinked product thereof, an acrylic silicone resin or a crosslinked product thereof, a polyurethane resin or a crosslinked product thereof, It is a polymer film having at least one of a styrene / acrylic acid ester copolymer, a styrene / butadiene copolymer or a cross-linked product thereof, and an epoxy cured product as a matrix.
The undercoat layer 3 contains additives such as ultraviolet absorbers, fluorescent brighteners, plasticizers, antioxidants, colorants, preservatives, fungicides, flame retardants, and rust inhibitors. Also good.

  The intermediate layer 5 is formed for the purpose of, for example, improving the adhesion between the first layer and the second layer, improving the ultraviolet transmittance in the cross-sectional direction from one side to the other side, protecting the first layer, and the like. Layer. This intermediate layer 5 is a matrix containing at least one polymer selected from the components exemplified as the first polymer contained in the first layer and the components exemplified as the second polymer contained in the second layer. It can consist of a polymer film as a phase. The intermediate layer 5 includes additives such as fluorescent brighteners, plasticizers, antioxidants, colorants (pigments), preservatives, fungicides, flame retardants, dispersants, antisettling agents, antifoaming agents, and the like. It may contain a net reinforcement or the like, but preferably does not contain an ultraviolet absorber.

  The topcoat layer can be made of a polymer film conventionally formed as a “topcoat layer” or the like on the outermost surface of a concrete structure. Usually, the topcoat layer is formed of the first layer and the second layer. It is a layer formed for the purpose of imparting protection, resistance to fading, weather resistance, stain resistance, and the like. The overcoat layer is composed of a polymer film having at least one polymer selected from the components exemplified as the second polymer contained in the second layer, polyester resin, polyacrylate, etc. as a matrix. can do. This overcoat layer is composed of UV absorbers, plasticizers, antioxidants, colorants (pigments), preservatives, fungicides, flame retardants, dispersants, anti-settling agents and the like; May be included, but it does not contain a fluorescent brightener.

  When the concrete structure 1 of this invention is provided with the primer layer 3, the upper limit of the thickness of this primer layer 3 is 200 micrometers normally.

  When the concrete structure 1 of this invention is provided with the intermediate | middle layer 5, the thickness of this intermediate | middle layer 5 becomes like this. Preferably it is 5-200 micrometers, More preferably, it is 10-100 micrometers, More preferably, it is 20-50 micrometers. The preferred thickness means the thickness when the intermediate layer 5 is a single layer type, and the total thickness when the intermediate layer 5 is a continuous multilayer type.

  Moreover, when the concrete structure 1 of this invention is provided with an overcoat layer, the thickness of this overcoat layer becomes like this. Preferably it is 10-500 micrometers, More preferably, it is 50-300 micrometers, More preferably, it is 80-200 micrometers. The preferred thickness means the thickness when the overcoat layer is a single layer type, and the total thickness when the overcoat layer is a continuous multilayer type.

  The tensile breaking elongation of the film constituting the intermediate layer 5 is lower than the tensile breaking elongation of the film constituting the first layer 4 or the same as the tensile breaking elongation of the film constituting the second layer 6, preferably Is 10% to 200%, more preferably 10% to 150%, still more preferably 10% to 100%. The tensile elongation at break is a measured value according to JIS A 6021 using a film having the preferred thickness.

  The tensile breaking elongation of the film constituting the overcoat layer is the same as or lower than the tensile breaking elongation of the film constituting the second layer 6, preferably 10% to 200%, more preferably 10% to 150. %, More preferably 30% to 100%. The tensile elongation at break is a measured value according to JIS A 6021 using a film having the preferred thickness.

  Since the first layer and the second layer constituting the concrete structure of the present invention are both excellent in ground followability, the second layer from the subbing layer or the first layer formed on the surface of the concrete base 2. Or it has excellent adhesiveness up to the topcoat layer when it has a topcoat layer, and is excellent in shape stability as an integrated product thereof. Therefore, the preferred embodiments of the present invention, the tensile breaking elongation of the film constituting the first layer 4, the tensile breaking elongation of the film constituting the intermediate layer 5, the tensile breaking elongation of the film constituting the second layer 6, and In the case where the tensile break elongation of the film constituting the top coat layer has a multilayer type film that sequentially decreases, if cracks occur in the concrete base 2, cracks are generated from the top coat layer side on the surface side of the covering part of the crack part. Or it is thinned. Since the coating is not damaged where there are no cracks inside, the concentration of the UV absorber in the crack space or thin part is reduced only in the second layer, or the second layer and the overcoat layer. It is possible to improve the transmittance.

  Here, the concrete raw materials (cement-based inorganic substance, aggregate, pozzolanic substance, thickener, water reducing agent) constituting the concrete base 2 will be described.

  Examples of the cement-based inorganic substance include ordinary Portland cement, early strength Portland cement, super early strength Portland cement, white Portland cement, moderately hot Portland cement, blast furnace cement, fly ash cement, alumina cement, and ultrafast cement.

Examples of the aggregate include fine aggregates such as river sand, quartz sand, and crushed sand, and coarse aggregates such as river gravel and crushed stone.
The pozzolan substance is used for imparting thixotropic properties to the cement composition, and fumed silica (fused silica), fly ash, natural pozzolan, or the like can be used.

  The thickener is used for imparting viscosity to the cement composition, and cellulose thickeners, acrylic thickeners such as polyacrylamide, and the like can be used.

  The water reducing agent is used to improve workability, and polycarboxylic acid water reducing agents, melamine water reducing agents, naphthalene water reducing agents, lignin water reducing agents, sulfonate water reducing agents, etc. should be used. Can do.

As described above, the cement composition can contain a fibrous reinforcing agent, an organic binder, and the like.
The fibrous reinforcing agent is used for improving the mechanical strength of concrete, suppressing cracking, and improving toughness. Carbon fibers such as PAN-based carbon fibers and pitch-based carbon fibers; polyamide-based fibers , Polyvinyl alcohol fiber, polyvinylidene chloride fiber, polyvinyl chloride fiber, polyacrylonitrile fiber, polyester fiber, polyethylene fiber, polypropylene fiber, polyurethane fiber, fluorine fiber, aramid fiber, etc .; etc. Is mentioned.
In addition, as the organic binder, polyacrylate, (meth) acryl / styrene copolymer, styrene / butadiene rubber (SBR) copolymer, and vinyl ester such as vinyl acetate are used. Examples thereof include ethylene and vinyl / vinyl alcohol (EVA) copolymers.

  When the concrete base 2 is formed, a method in which the cement composition is cast by pouring the cement composition and then cured is employed.

In the method for producing a concrete structure of the present invention, a first layer forming composition containing polyacrylate and a fluorescent brightening agent is applied to the surface side of a concrete base, and then dried to form a first layer. forming step (hereinafter, referred to as "first layer forming step".), and the acrylic silicone resin or a fluorine-containing resin, a second layer forming composition containing an ultraviolet absorber, a surface side of the first layer And a step of forming a second layer by drying (hereinafter referred to as “second layer forming step”).
When the concrete structure of the present invention includes an undercoat layer, an intermediate layer, an overcoat layer and the like, a step of forming an undercoat layer (hereinafter referred to as “undercoat layer forming step”) and an intermediate layer, respectively. A step (hereinafter referred to as “intermediate layer forming step”), a step of forming a top coat layer (hereinafter referred to as “top coat layer forming step”), and the like.

The first layer forming step is a step of forming a first layer by applying a composition for forming a first layer containing polyacrylate and a fluorescent brightening agent to the surface side of the concrete base, and then drying the composition. .
As described above, since the first layer is a layer containing the first polymer, the first layer forming composition includes the first polymer or a component that forms the first polymer (hereinafter referred to as the first polymer). , "First polymer forming material").

The first layer forming composition is a composition containing a polyacrylate or a composition for forming a crosslinked polyacrylate.
Although the composition for forming the first layer may be either an aqueous composition or a solvent-based composition, it is preferable to use an aqueous composition from the viewpoint of safety to the installer and response to the environment.

When the first layer forming composition is a composition containing a polyacrylate, the composition containing the polyacrylate exemplified above can be used.
The composition for forming a crosslinked polyacrylate contains the above polyacrylate having a structural unit derived from glycidyl (meth) acrylate and the like, and a compound having a hydroxyl group or an amino group (may be a polymer). Composition containing the above-mentioned polyacrylate having a structural unit derived from (meth) acrylate having a hydroxyl group and the like, and a compound having a glycidyl group (may be a polymer); polyfunctional (meth) acrylate and polymerization initiator The composition etc. which contain can be used.

  The fluorescent whitening agent illustrated above can be used for the fluorescent whitening agent mix | blended with the said composition for 1st layer formation, A commercial item can be used. When the fluorescent whitening agent is a bis (triazinylaminostilbene) disulfonic acid derivative, for example, “Wytex SA” and “Wytex SKC” (trade name) manufactured by Sumitomo Chemical Co., Ltd. can be used. Further, when the optical brightener is a benzoxazinone, for example, “Tinopearl OB” (trade name) manufactured by BASF Japan Ltd. can be used. In blending, for example, a powder having a uniform particle diameter is used.

  The content of the fluorescent whitening agent contained in the first layer forming composition is preferably 0 with respect to a total of 100 parts by mass of the first polymer forming material contained in the first layer forming composition. 0.01-3 parts by mass, more preferably 0.05-1.0 parts by mass, and still more preferably 0.1-0.5 parts by mass. When the content of the fluorescent brightening agent is 0.01 to 3 parts by mass, the above-described action in the concrete structure of the present invention is sufficiently exhibited.

The first layer forming composition includes a filler; a plasticizer, an antioxidant, an anti-aging agent, a colorant, an antiseptic, a fungicide, a flame retardant, an antifoaming agent, a film forming aid, a dispersing agent, and a sedimentation agent. You may contain additives, such as an inhibitor.
When the said 1st layer formation composition contains a filler, the content becomes like this. Preferably it is 30-300 mass parts with respect to a total of 100 mass parts of 1st polymer formation material, More preferably, it is 50. About 150 parts by mass.

  The viscosity of the composition for forming the first layer is appropriately selected depending on the coating method, but the viscosity in the method measured according to JIS K7117-1 is preferably 3,000 to 70,000 mPa · s, More preferably, it is 5,000 to 50,000 mPa · s.

The application of the first layer forming composition is performed on the surface side of the concrete base portion, and may be performed on the surface of the concrete base portion. It may be performed on the surface of the undercoat layer (primer layer) formed on the surface of the base.
Examples of the method for applying the first layer forming composition include a method using a roller, a rake, a trowel, a spray and the like. You may coat several times with respect to a to-be-coated surface.
The thickness of the coating film is appropriately selected depending on the composition of the first layer forming composition, the coating method, and the like, and is usually 0.2 to 2 mm.

Thereafter, the coating film made of the first layer forming composition is dried to obtain a film containing the first polymer and the fluorescent brightening agent. The drying temperature is generally selected depending on the type of the first polymer forming material and the like, and is 5 ° C to 50 ° C.
In addition, as above-mentioned, a 1st layer can be made into the layer containing a mesh reinforcement. As a manufacturing method of the first layer containing this mesh reinforcement, after laying a mesh reinforcement made of glass fiber, polymer (polyester, polyamide, vinylon, phenol, polyolefin, aramid, etc.) on the surface to be coated, A method of applying and drying the first layer forming composition; A method of applying a first layer forming composition and then placing a net-like reinforcing material before the drying, placing it inside the coating film by gravity, and drying; After applying the composition for forming the first layer, before the drying, a mesh reinforcing material is installed, and the composition for forming the first layer is applied again and dried.

Next, a second layer forming step, an acrylic silicone resin or a fluorine-containing resin, a second layer forming composition containing an ultraviolet absorber, was applied to the surface side of the first layer, and drying the This is a step of forming two layers.
As described above, since the second layer is a layer containing the second polymer, the composition for forming the second layer includes the second polymer containing the acrylic silicone resin or a cross-linked product thereof or a fluorine-containing resin , Or the component which forms this 2nd polymer | macromolecule is contained.

The composition for forming the second layer is a composition containing an acrylic silicone resin, a composition for forming a crosslinked acrylic silicone resin, or a composition containing a fluorine-containing resin.
The composition for forming the second layer may be any of an aqueous composition, a solvent-based composition, and a solventless composition. However, from the viewpoint of safety to the installer and response to the environment, an aqueous composition is used. It is preferable.

  When the composition for forming the second layer is a composition containing a fluorine-containing resin, a composition containing the exemplified fluorine-containing resin can be used.

  The ultraviolet absorber illustrated above can be used for the ultraviolet absorber mix | blended with the said composition for 2nd layer formation, A commercial item can be used. For example, in the product of ADEKA, “ADEKA STAB” product grades “LA-52”, “LA-57”, “LA-62”, “LA-67”, “LA-63”, “LA-68LD”, “LA-77Y”, “LA-77G”, “LA-82”, “LA-87”, “LA-402XP”, “LA-502XP”, “LA-601” and “LA-602” are exemplified. The Moreover, in the product of Ciba Japan, “TINUVIN PS”, “TINUVIN 99-2”, “TINUVIN 109”, “TINUVIN 384-2”, “TINUVIN 900”, “TINUVIN 928”, “TINUVIN 1130”, “ TINUVIN 5236 "," TINUVIN 400 "," TINUVIN 405 "," TINUVIN 460 "," TINUVIN 477DW "," TINUVIN 479 "," TINUVIN 111FDL "," TINUVIN 123 "," TINUVIN 144 "," TINUVIN 144 " “TINUVIN 292”, “TINUVIN 5100”, “TINUVIN 5050”, “TINUVIN 5060”, “TINUVIN 5151”, “L” GNOSTAB 1198 "," TINUVIN P / FL "," TINUVIN 234 "," TINUVIN 326 / FL "," TINUVIN 328 "," TINUVIN 329 / FL "," TINUVIN 213 "," TINUVIN 571 "," TINUVIN 1577FF ", "CHIMASSORB 81 / FL", "TINUVIN 120", "CHIMASSORB 119FL", "CHIMASSORB 2020FDL", "CHIMASSORB 944FDL", "TINUVIN 622LD", "TINUVIN 144", "TINUVIN 765", "TINUVIN 765", "TINUVIN 765", "TINUVIN 765", "TINUVIN 765", "TINUVIN 765" ”,“ TINUVIN 783FDL ”,“ TINUVIN 791FB ”,“ Examples are TINUVIN 850FF, TINUVIN 855FF, TINUVIN 494AR, TINUVIN NOR 371FF, and TINUVIN B75. In blending, for example, a powder having a uniform particle diameter is used.

The content of the ultraviolet absorber contained in the second layer forming composition is preferably 0.000 relative to a total of 100 parts by mass of the second polymer forming material contained in the second layer forming composition. It is 5-5 mass parts, More preferably, it is 1.0-3.0 mass parts, More preferably, it is 1.0-2.0 mass parts. The said effect | action in the concrete structure of this invention is fully exhibited as content of a ultraviolet absorber is 0.5-5 mass parts.

The composition for forming the second layer comprises a filler; a plasticizer, an antioxidant, an anti-aging agent, a light stabilizer, a heat stabilizer, an antistatic agent, a water repellent, an oil repellent, a colorant, a preservative, You may contain additives, such as a mold agent, a flame retardant, an antifoamer, a dispersing agent, an anti-settling agent.
When the composition for forming the second layer contains a filler, the content thereof is appropriately selected from the viewpoints of tensile elongation at break of the obtained second layer, adhesion to the first layer, and the like. However, it is usually 50 to 300 parts by mass with respect to 100 parts by mass in total of the second polymer forming material.

  The viscosity of the composition for forming the second layer is appropriately selected according to the coating method, but the viscosity in the method measured according to JIS K 7117-1 is preferably 3,000 to 70,000 mPa · s. More preferably, it is 5,000 to 50,000 mPa · s.

The application of the second layer forming composition may be performed on the surface of the first layer, or the surface of the intermediate layer previously formed on the surface of the first layer by the intermediate layer forming step. It may be performed for.
Examples of the method for applying the second layer forming composition include a method using a roller, a rake, a trowel, a spray and the like. You may coat several times with respect to a to-be-coated surface.
The thickness of the coating film is appropriately selected depending on the composition of the second layer forming composition, the coating method, and the like, and is usually 0.05 to 0.2 mm.

  Thereafter, the coating film comprising the second layer forming composition is dried to obtain a film containing the second polymer and the fluorescent brightening agent. The drying temperature is generally selected depending on the type of the second polymer forming material and the like, and is 5 ° C to 50 ° C.

When the production method of the present invention includes an undercoat layer forming step, the composition for forming the undercoat layer includes polyvinyl acetate, ethylene / vinyl acetate copolymer, polyacrylate, acrylic silicone resin, polyurethane resin, styrene Composition containing at least one selected from acrylate copolymer, styrene / butadiene copolymer, etc .; composition containing polyol and polyisocyanate containing polyol having unsaturated carbon-carbon bond; unsaturated A composition containing a polyol containing a polyol having a carbon-carbon bond, a polyisocyanate and a chain extender; a composition containing a polyurethane resin and a radical polymerization initiator (organic peroxide, azo compound, etc.); a polyurethane resin and Composition containing a crosslinking agent (organic peroxide, organic sulfur compound, etc.); Isocyan Compositions containing over preparative group-terminated urethane prepolymer and a curing agent, epoxy compound and compositions containing the curing agent; and the like.
In addition, this undercoat layer-forming composition contains additives such as ultraviolet absorbers, fluorescent brighteners, plasticizers, antioxidants, colorants, preservatives, fungicides, flame retardants, and rust inhibitors. You may contain.

  When the production method of the present invention includes an intermediate layer forming step, the intermediate layer forming composition preferably contains a composition containing an acrylic urethane resin, a crosslinked acrylic urethane resin forming composition, and an acrylic silicone resin. A composition, a composition for forming a crosslinked acrylic silicone resin, a composition containing a fluororesin, or a composition for forming an epoxy cured product.

  When the production method of the present invention includes an overcoat layer forming step, the composition for forming an overcoat layer preferably comprises a composition containing an acrylic urethane resin, a composition for forming a crosslinked acrylic urethane resin, and an acrylic silicone resin. A composition containing a crosslinked acrylic silicone resin, a composition containing a fluorine-containing resin, a composition containing a polyacrylate, a composition containing a polyester resin, or a composition for forming an epoxy cured product. .

  In the method for detecting cracks in concrete according to the present invention, the surface of a concrete structure having cracks is irradiated with ultraviolet rays, and the ultraviolet rays are stretched and formed by crack spaces in the second layer that are fractured or formed by cracks. Transmitting the thin-walled portion of the second layer to reach the first layer disposed on the surface side of the cracked portion and causing the fluorescent whitening agent contained in the ultraviolet light receiving portion in the first layer to emit light To do.

  FIG. 4 and FIG. 5 show a preferred embodiment of the present invention, when the tensile break elongation of the film constituting the first layer is higher than the tensile break elongation of the film constituting the second layer. It is a fracture surface when a crack occurs.

  FIG. 4 shows that the first layer 4 is stretched without being broken to form a thinned crack cover 45, while the second layer 6 is broken to form a crack space 8. Since the coating is not damaged where there are no cracks inside, the structure of the first layer and the second layer disposed on the surface of the concrete base 2 is maintained.

  Further, in FIG. 5, the first layer 4 is stretched without being broken to form a thinned crack covering portion 45, while the second layer 6 is also stretched without being broken to form a thin portion 65. It shows that. FIG. 5 shows that the first layer 4 and the second layer 6 are excellent in adhesiveness. As a result, a recess is formed on the surface of the second layer 6. Since the coating is not damaged where there are no cracks inside, the structure of the first layer and the second layer disposed on the surface of the concrete base 2 is maintained. Although not shown, when the crack covering portion 45 and the thin portion 65 are peeled off due to the occurrence of a crack, a space is formed between them, but in this case as well, there is no crack inside. Since the coating is not damaged, the structure of the first layer and the second layer disposed on the surface of the concrete base 2 is maintained.

In any case shown in FIGS. 4 and 5, when ultraviolet rays are irradiated from above the drawings, the ultraviolet rays are radiated from the crack space portion 8 (FIG. 4) or the thinned portion 65 (FIG. 5) that has been thinned by stretching. Is transmitted to reach the thinned crack covering portion 45 of the first layer, and the fluorescent whitening agent contained in the crack covering portion 45 (ultraviolet light receiving portion) is caused to emit light. When ultraviolet rays are applied to a normal second layer in which the crack space 8 and the thin portion 65 are not formed, it is difficult to reach the first layer due to the contained ultraviolet absorber. In the portion 65, since there is no ultraviolet absorber or the concentration is reduced, the transmittance of ultraviolet rays is selectively high, and a high emission intensity can be obtained in the crack covering portion 45 (ultraviolet light receiving portion). The position of the part 9 can be detected accurately.
In FIG. 4, the crack space 8 may be visually observed, but the inspection environment varies from a bright place to a dark place, so using ultraviolet rays leads to a reduction in oversight.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples as long as the gist of the present invention is not exceeded.
In the following example, a slate plate 10 having a cut in the lower surface on the lower surface half as shown in FIG. 6A (length 40 mm, width 120 mm, thickness 5 mm. JSCE K532-1999). A test piece (see FIG. 6 (B)) in which an undercoat layer, a first layer, and a second layer are sequentially formed on the surface of “the surface covering material according to the crack followability test method” is manufactured, It used for evaluation.

1. Raw material 1-1. Composition for forming undercoat layer A two-component reaction-curable water-based epoxy resin emulsion “Alonble Coat P-300” (trade name) manufactured by Toagosei Co., Ltd. was used.

1-2. Composition for forming first layer Three types of compositions (A, B and C) shown in Table 1 were used. In any case, after emulsion polymerization of a monomer mainly composed of 2-ethylhexyl acrylate to synthesize a polyacrylate, with a compound such as a fluorescent whitening agent “Tinopearl OB” (trade name) manufactured by BASF Japan Ltd. It is an aqueous composition prepared by mixing.

1-3. Composition for forming the second layer The following three types of compositions (X, Y and Z) were used.
X: Water-based acrylic silicone resin paint “Alonburu Coat T-1000” (trade name) manufactured by Toagosei Co., Ltd. Blended with an ultraviolet absorber 60 parts by mass of acrylic silicone resin, 25 parts by mass of titanium dioxide, and ferric oxide It is an emulsion composition containing 10 parts by mass, 5 parts by mass of carbon black, and 1 part by mass of an ultraviolet absorber “TINUVIN 460” (trade name) manufactured by BASF Japan.
Y: Contains 100 parts by mass of solvent-based fluororesin paint “Neopaint Front Top # 9000AB” (trade name, solid content concentration: 66 mass%) manufactured by Asia Industries Co., Ltd. and 2 parts by mass of the above-mentioned ultraviolet absorber “TINUVIN 460”. It is a composition.
Z: Two-pack type acrylic silicone resin paint “Alonburu Coat T-370” (trade name) manufactured by Toagosei Co., Ltd. Blended with a UV absorber Main agent (acrylic silicone resin 35% by mass, xylene 6% by mass, ethylbenzene 3 parts by weight, 20 parts by weight of white spirit, 20 parts by weight of titanium dioxide, and 16 parts by weight of ferric oxide, and 100 parts by weight of curing agent (15% by weight of polyisocyanate and 3% by weight of xylene) And 25 parts by mass of trimethylbenzene (7% by mass), and 1 part by mass of an ultraviolet absorber “TINUVIN PS” (trade name) manufactured by BASF Japan.

2. Evaluation Example 1
On the surface of the slate plate, the composition for forming an undercoat layer is applied with a roller (coating amount 0.1 kg / m ² ) and dried at 25 ° C. to form a 10 μm thick film (undercoat layer) did. Thereafter, the first layer forming composition (A) was applied with a roller (coating amount 2.0 kg / m ² ) and dried at 25 ° C. to form a film (first layer) having a thickness of 730 μm. . Next, the composition for forming the second layer (X) was applied with a roller (coating amount 0.2 kg / m ² ) and dried at 25 ° C. to form a film (second layer) having a thickness of 60 μm. The test piece shown in FIG. 6 (B) was obtained. The tensile breaking elongation (JIS A 6021) of the film consisting only of the first layer was 450%, and the tensile breaking elongation (JIS A 6021) of the film consisting only of the second layer was 150%.
Thereafter, an impact was applied to the slate plate 10 on which the film was laminated, and the slate plate 10 was halved (slate plates 10a and 10b) using the cuts (see FIG. 6C). This was used as a specimen for a tensile test. Specifically, with the ends of the slate plates 10a and 10b being held, the tensile tester is used to pull at a speed of 1 mm / min. The wavelength of 360 nm) was continuously irradiated, and the fluorescence from the laminated film that was thinned by tension was visually observed. Irradiation with ultraviolet rays was performed using an ultraviolet irradiator “UV-400” (trade name) manufactured by Kyocera, the output was 1,200 mW / cm ² , and the distance from the test specimen was about 30 cm.
With the start of the tensile test, the interval between the slate plates 10a and 10b was widened, the laminated film was stretched (see FIG. 6D), and fluorescence was observed after 30 seconds. Then, when the second layer was broken after about 60 seconds (not shown), the ultraviolet light was applied to the exposed surface of the first layer, so that the fluorescence intensity was further increased.

Example 2
On the surface of the slate plate, the composition for forming an undercoat layer is applied with a roller (coating amount 0.1 kg / m ² ) and dried at 25 ° C. to form a 10 μm thick film (undercoat layer) did. Thereafter, a first layer forming composition (B) was applied by a roller (coated amount 2 kg ^/ m 2), and dried at 25 ° C., to form a film having a thickness of 730Myuemu (first layer). Next, the composition for forming the second layer (Y) was applied with a roller (coating amount 0.2 kg / m ² ) and dried at 25 ° C. to form a 150 μm-thick film (second layer). The test piece shown in FIG. 6 (B) was obtained. The tensile breaking elongation (JIS A 6021) of the film consisting only of the first layer was 450%, and the tensile breaking elongation (JIS A 6021) of the film consisting only of the second layer was 70%.
Thereafter, a tensile test was performed in the same manner as in Example 1. As a result of the start of the tensile test, the interval between the slate plates 10a and 10b increased, the laminated film was stretched, and fluorescence was observed after 10 seconds. Then, when the second layer was broken after about 30 seconds, the ultraviolet light was applied to the exposed surface of the first layer, so that the fluorescence intensity was further increased.

Example 3
On the surface of the slate plate, the composition for forming an undercoat layer is applied with a roller (coating amount 0.1 kg / m ² ) and dried at 25 ° C. to form a 10 μm thick film (undercoat layer) did. Thereafter, the composition for forming the first layer (C) was applied with a roller (coating amount 3.0 kg / m ² ) and dried at 25 ° C. to form a film (first layer) having a thickness of 1,200 μm. Formed. Next, the composition for forming the second layer (Z) was applied with a roller (coating amount: 0.3 kg / m ² ) and dried at 25 ° C. to form a film (second layer) having a thickness of 100 μm. The test piece shown in FIG. 6 (B) was obtained. The tensile breaking elongation (JIS A 6021) of the film consisting only of the first layer was 210%, and the tensile breaking elongation (JIS A 6021) of the film consisting only of the second layer was 60%.
Thereafter, a tensile test was performed in the same manner as in Example 1. As a result of the start of the tensile test, the interval between the slate plates 10a and 10b increased, the laminated film was stretched, and fluorescence was observed after 10 seconds. Then, when the second layer was broken after about 40 seconds, the ultraviolet light was applied to the exposed surface of the first layer, so that the fluorescence intensity was further increased.

  According to the present invention, the position of a crack in a concrete base of a concrete structure can be accurately detected by irradiating an ultraviolet lamp. In particular, it is based on a fluorescent brightener by irradiating with ultraviolet rays even when it is judged that the surface is normal in spite of having a film on the surface of the concrete base. The position of the crack can be detected by light emission. Therefore, the concrete structure of the present invention includes a wall such as a building, a tunnel, a bridge, a pier, an abutment, a pier, a box culvert, a parapet, a railing, a floor slab, a balcony, a chimney, a concrete pole, a tank, a frame, a dike, etc. The structure is suitable as a structure having a functional layer including a first layer and a second layer on the surface side of the concrete base.

1: Concrete structure 2: Concrete base 3: Undercoat layer (primer layer)
4: First layer 6: Second layer 8: Crack space portion 9: Crack portion 10, 10a and 10b: Slate plate 45: Crack covering portion 65: Thin portion

Claims (11)

A base made of concrete, a first layer formed on the surface side of the base, and a second layer formed on the surface side of the first layer;
The first layer includes a polymer containing polyacrylate or a cross-linked product thereof and an optical brightener, and the second layer includes a polymer containing an acrylic silicone resin or a cross-linked product thereof or a fluorine-containing resin and an ultraviolet absorber. seen including,
The tensile breaking elongation of the film constituting the first layer measured according to JIS A 6021 is 50% or more higher than the tensile breaking elongation of the film constituting the second layer,
A concrete structure characterized in that the film constituting the first layer has a tensile breaking elongation of 100% to 2,000%, and the film constituting the second layer has a tensile breaking elongation of 10% to 200%. object. The concrete structure according to claim 1, wherein the first layer has a thickness of 50 to 3,000 μm, and the second layer has a thickness of 10 to 500 μm. The concrete structure according to claim 1 or 2, wherein the polyacrylate is a copolymer obtained by using a (meth) acrylic acid ester compound having an ester part containing a hydrocarbon group having 4 to 10 carbon atoms. The optical brightener is stilbene, benzimidazole, benzoxazole, naphthalimide, benzothiazole, naphthothiazole, dibenzothiophene-5,5-dioxide, rhodamine, coumarin, oxazine, biphenyl The concrete structure according to any one of claims 1 to 3, wherein the concrete structure is at least one selected from the group consisting of methine cyanines, pyrazolines, benzidines and carbostyrils. 5. The concrete structure according to claim 1, wherein the content of the optical brightener is 0.01 to 3 parts by mass when the polymer in the first layer is 100 parts by mass. . 6. The ultraviolet absorber is at least one selected from benzotriazoles, benzophenones, triazines, benzoxazinones, salicylic acid phenyl esters, hindered amines, indoles and azomethines. A concrete structure according to claim 1. The concrete structure according to any one of claims 1 to 6, wherein a content ratio of the ultraviolet absorber is 0.5 to 5 parts by mass when the polymer in the second layer is 100 parts by mass. The concrete structure according to any one of claims 1 to 7 , further comprising an undercoat layer between the base and the first layer. The concrete structure according to any one of claims 1 to 8 , further comprising another layer between the first layer and the second layer. A method for producing a concrete structure according to claim 1,
Polyacrylate, after the first layer forming composition comprising a fluorescent whitening agent, were applied to the surface side of the base made of concrete, forming a first layer and dried,
as well as,
Forming acrylic silicone resin or a fluorine-containing resin, a second layer forming composition containing an ultraviolet absorber, was applied to the surface side of the first layer, the second layer and dried,
A method for producing a concrete structure comprising: A method for detecting cracks in a base portion of a concrete structure according to any one of claims 1 to 9 , wherein the surface of the concrete structure having the cracks is irradiated with ultraviolet rays, and the ultraviolet rays are irradiated to the cracks. The crack space part of the second layer formed by fracture or the thin part of the second layer stretched by the crack is permeated to reach the first layer arranged on the surface side of the crack part. A method for detecting cracks in concrete, wherein the fluorescent whitening agent contained in the ultraviolet light receiving part in the first layer emits light.

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