Concrete structure and method for producing concrete structure

Abstract

To provide a concrete structure having an improved performance balance between observability and appearance.SOLUTION: A concrete structure 100 comprises concrete 50 and a layer 10 composed of a composition for concrete. In the concrete structure 100, when an optional area of 70 mm×150 mm of the surface of the concrete structure 100 is viewed from the side of the layer 10 composed of a composition for concrete, the entire surface of the concrete 50 cannot be observed in the visible light range and a part or the entire surface of the concrete 50 can be observed in the near-infrared region.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a concrete structure and a method for manufacturing a concrete structure. [Background technology]

[0002] Various studies have been conducted on compositions for concrete that can protect, reinforce, or repair concrete. Examples of techniques related to compositions for concrete include those described in Patent Documents 1 and 2.

[0003] Patent Document 1 describes a composition that contains (1) a radical polymerizable monomer, (2) a copolymer of a vinyl aromatic hydrocarbon and a conjugated diene compound, (3) a polymerization initiator, and (4) a polymerization accelerator, and contains 1 to 10 parts by mass of (2) the copolymer of a vinyl aromatic hydrocarbon and a conjugated diene compound per 100 parts by mass of the total of (1) and (2). It is described that the composition described in Patent Document 1 provides a composition having excellent curability and transparency.

[0004] Patent Document 2 describes a surface protection composition to be applied to the surface of a porous body, which has an elongation of the surface protection layer of 0.5 mm or more as measured by a specified crack tracking test procedure in accordance with JSCE K 532. It is described that the surface protecting composition described in Patent Document 2 provides a surface protecting composition having excellent application stability. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2021-20983 [Patent Document 2] JP 2023-46902 A Summary of the Invention [Problem to be solved by the invention]

[0006] Hereinafter, a structure comprising concrete and a layer made of a concrete composition will be referred to as a concrete structure.

[0007] From the perspective of managing concrete deterioration, it is required that when the concrete structure is viewed through the layer made of the concrete composition, cracks and the like on the surface of the concrete can be observed (hereinafter, the degree to which cracks and the like on the concrete surface can be observed is also referred to as "observability").

[0008] Furthermore, concrete structures are also required to have good appearance.

[0009] The present invention has been made in consideration of the above circumstances, and provides a concrete structure having an improved balance of performance between observation ability and appearance. [Means for solving the problem]

[0010] According to the present invention, there are provided a concrete structure and a method for manufacturing a concrete structure as described below.

[0011] [1] A concrete structure comprising concrete and a layer made of a concrete composition, A concrete structure, in which, when any area of ​​70 mm x 150 mm on the surface of the concrete structure is viewed from the side of the layer made of the composition for concrete, the entire surface of the concrete cannot be observed in the visible light region, but a part or the entire surface of the concrete can be observed in the near-infrared region. [2] The concrete structure according to [1] above, wherein the composition for concrete contains a resin (A) and a pigment (B). [3] The concrete structure according to [2], wherein the resin (A) includes at least one selected from the group consisting of modified silicone resins, urethane resins, urea resins, urethane urea resins, epoxy resins, and (meth)acrylic resins. [4] The content of the pigment (B) in the composition for concrete is 0.005 parts by mass or more and 40 parts by mass or less when the content of the resin (A) in the composition for concrete is 100 parts by mass. The concrete structure according to [2] or [3]. [5] The concrete structure according to any one of the above [2] to [4], wherein the pigment (B) contains a near-infrared transmitting pigment. [6] The concrete structure according to any one of [2] to [5], wherein the pigment (B) includes one or more pigments selected from the group consisting of black pigments (B-1) and white pigments (B-2). [7] The concrete structure according to [6], wherein the black pigment (B-1) includes at least one selected from the group consisting of metal oxide pigments, phthalocyanine pigments, azo pigments, melanin pigments, carbon black, metal oxynitride pigments, metal nitride pigments, bisbenzofuranone pigments, azomethine pigments, and perylene pigments. [8] The concrete structure according to [6] or [7], wherein the white pigment (B-2) includes at least one selected from the group consisting of calcium carbonate, titanium oxide, silica, alumina, zinc oxide, zirconia, glass, crosslinked (meth)acrylic particles, crosslinked polystyrene resin, melamine resin, phenolic resin, epoxy resin, polycarbonate, and fluorine-based compounds. [9] Further comprising a layer made of a primer composition; The concrete structure according to any one of [1] to [8], wherein the layer made of the primer composition is located between the concrete and a layer made of the composition for concrete.

[10] Further comprising a layer of a topcoat composition; The concrete structure according to any one of [1] to [9], wherein the layer made of the top coat composition is located on the opposite side of the layer made of the composition for concrete to the concrete side.

[11] The method for producing a concrete structure according to any one of [1] to

[10] , forming a layer of a primer composition on the surface of the concrete; and forming a layer made of the composition for concrete on the layer made of the composition for primer.

[12] A structure comprising a substrate and a layer made of a composition, When any region of 70 mm × 150 mm on the surface of the structure is viewed from the side of the layer made of the composition, the entire surface of the substrate cannot be observed in the visible light region, but a part or the entire surface of the substrate can be observed in the near-infrared region. Effect of the Invention

[0012] According to the present invention, it is possible to provide a concrete structure having an improved balance of performance in terms of observation property and appearance property. [Brief description of the drawings]

[0013] [Figure 1] 1 is a cross-sectional view showing a schematic example of a preferred structure of a concrete structure according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, an embodiment of the present invention will be described. The substrate of the present invention is preferably concrete. The composition of the present invention is preferably a composition for concrete. The structure of the present invention is preferably a concrete structure. Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The drawings are simplified and do not correspond to the actual dimensional ratio. The numerical range "A to B" represents A or more and B or less unless otherwise specified. In addition, in this specification, "(meth)acrylic" means "at least one of acrylic and methacrylic".

[0015] As described above, concrete structures are required to have good observability and appearance. As a conventional technique for improving observation properties, for example, there is a technique described in Patent Document 1 in which a highly transparent composition is used as a composition for concrete.

[0016] According to the study by the present inventors, when a highly transparent composition is used as a composition for concrete, cracks and the like in the concrete can be confirmed even when the concrete is not being subjected to deterioration management, which may be undesirable in terms of appearance, in other words, the appearance of the concrete structure may be deteriorated. In other words, according to the study by the present inventors, it was found that there is a trade-off between observability and appearance in a concrete structure.

[0017] The present invention has been made in consideration of the above circumstances, and provides a concrete structure having an improved balance of performance between observation ability and appearance.

[0018] [Concrete structure] FIG. 1 is a cross-sectional view showing a schematic example of a preferable structure of the concrete structure of the present embodiment. The concrete structure 100 of this embodiment is a concrete structure 100 comprising concrete 50 and a layer 10 made of a composition for concrete, and when any region of 70 mm x 150 mm on the surface of the concrete structure 100 is viewed from the side of the layer 10 made of a composition for concrete, the entire surface of the concrete 50 cannot be observed in the visible light region, but a part or the entire surface of the concrete 50 can be observed in the near-infrared region.

[0019] As described above, in conventional concrete structures, there is a trade-off between observation ability and appearance. The present inventors have conducted extensive research to solve the above problems. As a result, they have found that, by satisfying the requirement that when an arbitrary region of 70 mm×150 mm on the surface of the concrete structure 100 is viewed from the layer 10 side made of a composition for concrete, the entire surface of the concrete 50 cannot be observed in the visible light region, and therefore, when the concrete structure 100 is viewed visually, the entire surface of the concrete 50 cannot be observed, and all cracks and the like of the concrete 50 cannot be observed, thereby improving the appearance.

[0020] On the other hand, it has been found that when a concrete structure 100 is viewed from the side of the layer 10 made of a composition for concrete over any area of ​​70 mm x 150 mm on the surface of the concrete structure 100, by satisfying the requirement that it is possible to observe a part or the entire surface of the concrete 50 in the near-infrared region, it is possible to observe cracks on the surface of the concrete 50, for example, by the following method for managing the deterioration of concrete, thereby improving observability. As a method for managing the deterioration of concrete, for example, the surface of concrete 50 is observed by irradiating light with a wavelength in the near-infrared region onto the surface of layer 10 made of a concrete composition of concrete structure 100 and observing the reflected light with a near-infrared camera.

[0021] In this specification, the visible light region means, for example, a region of light having a wavelength of 380 nm or more and less than 750 nm, preferably 490 nm or more and 650 nm or less, and the near-infrared region means, for example, a region of light having a wavelength of 750 nm or more and 2500 nm or less, preferably 800 nm or more and 1500 nm or less.

[0022] The concrete structure 100 can be configured such that, for example, by adjusting the materials that make up the composition for concrete; by setting the physical properties of the composition for concrete within a predetermined range; etc., "when any area of ​​70 mm x 150 mm on the surface of the concrete structure 100 is viewed from the side of the layer 10 made of the composition for concrete, the entire surface of the concrete 50 cannot be observed in the visible light region, but a part or the entire surface of the concrete 50 can be observed in the near-infrared region." More specifically, for example, the above configuration can be realized by the composition for concrete satisfying the preferred aspects described below.

[0023] Here, in this embodiment, cracks on the surface of the concrete 50 are those having a width of 0.1 mm or more and a length of 5 mm or more, and although there is no particular upper limit, for example, the width is 5 mm or less and the length is 100 mm or less.

[0024] Each layer of the concrete structure 100 will now be described.

[0025] <Concrete> The concrete structure 100 comprises concrete 50 . The concrete 50 is not particularly limited, but may be, for example, a part of the concrete that constitutes an elevated bridge.

[0026] <Layer made of concrete composition> The concrete structure 100 comprises a layer 10 of a concrete composition.

[0027] The composition for concrete forming the layer 10 made of the composition for concrete may be an uncured product, a semi-cured product, or a cured product.

[0028] The layer 10 made of the concrete composition is preferably 0.1 mm or more, more preferably 0.3 mm or more, even more preferably 0.5 mm or more, even more preferably 0.7 mm or more, and preferably 3 mm or less, more preferably 2.5 mm or less, even more preferably 2 mm or less, even more preferably 1.8 mm or less.

[0029] The total amount of non-volatile components of the concrete composition in the layer 10 made of the concrete composition is preferably 0.5 kg / m 2 More preferably, 0.7 kg / m 2 More preferably, 1 kg / m 2 and preferably 2 kg / m 2 Less than or equal to 1.7 kg / m 2 The following is the result.

[0030] <Layer made of primer composition> The concrete structure 100 preferably further comprises a layer 20 of a primer composition, the layer 20 of primer composition being located between the concrete 50 and the layer 10 of concrete composition. In other words, it is preferable that the concrete structure 100 comprises, in this order, concrete 50, a layer 20 made of the primer composition, and a layer 10 made of the composition for concrete, and it is more preferable that the concrete structure 100 comprises, in this order, concrete 50, a layer 20 made of the primer composition, and a layer 10 made of the composition for concrete, with the layers being in direct contact with each other.

[0031] The primer composition forming the layer 20 made of the primer composition may be an uncured product, a semi-cured product, or a cured product.

[0032] The total amount of non-volatile components of the primer composition in the layer 20 made of the primer composition is preferably 0.03 kg / m 2 More preferably, 0.05 kg / m 2 and preferably 0.3 kg / m 2Less than or equal to 0.2 kg / m 2 Less than 0.1 kg / m, more preferably 0.1 kg / m 2 The following is the result.

[0033] <Layer composed of topcoat composition> The concrete structure 100 preferably further comprises a layer 30 of a topcoat composition, the layer 30 of the topcoat composition being located on the opposite side to the concrete 50 side of the layer 10 of the concrete composition. In other words, it is preferable that the concrete structure 100 comprises, in this order, concrete 50, a layer 10 made of a composition for concrete, and a layer 30 made of a topcoat composition, and it is even more preferable that the concrete structure 100 comprises, in this order, concrete 50, a layer 10 made of a composition for concrete, and a layer 30 made of a topcoat composition, with each layer being in direct contact with the other.

[0034] The topcoat composition forming layer 30 made of the topcoat composition may be an uncured product, a semi-cured product, or a cured product.

[0035] The total amount of non-volatile components of the topcoat composition in the layer 30 of the topcoat composition is preferably 0.03 kg / m 2 More preferably, 0.05 kg / m 2 More preferably, 0.07 kg / m 2 and preferably 0.3 kg / m 2 Less than or equal to 0.2 kg / m 2 The following is the result.

[0036] When the concrete structure 100 further comprises a layer 20 of a primer composition and a layer 30 of a topcoat composition, the concrete structure 100 preferably comprises, in this order, concrete 50, a layer 20 of a primer composition, a layer 10 of a concrete composition, and a layer 30 of a topcoat composition, and more preferably comprises, in this order, concrete 50, a layer 20 of a primer composition, a layer 10 of a concrete composition, and a layer 30 of a topcoat composition, with each layer being in direct contact with the other layers.

[0037] Preferred embodiments of the compositions constituting each layer of the concrete structure 100 will now be described.

[0038] <Concrete composition> A preferred embodiment of the composition for concrete constituting the layer 10 made of a composition for concrete will be described.

[0039] Hereinafter, the preferred ranges of the transmittance at a wavelength of 1000 nm and the transmittance at a wavelength of 600 nm of the composition for concrete of this embodiment will be described, but these mean the values ​​obtained by transmittance measurement 1, respectively.

[0040] <Transmittance measurement 1> A hardened product made of a concrete composition formed to a thickness of 1 mm is prepared as transmittance measurement sample 1. For transmittance measurement sample 1, the transmittance at wavelengths from 300 nm to 1500 nm is measured in accordance with JIS K 0115 (2020) to obtain values ​​of the transmittance at a wavelength of 1000 nm and the transmittance at a wavelength of 600 nm.

[0041] Here, the transmittance measurement sample 1 can be prepared, for example, by the method described in the Examples. Specifically, the composition for concrete is applied to a PET film to a thickness of 1 mm, and the composition for concrete is allowed to harden at 23°C and a relative humidity of 50% for 7 days, after which the PET film is peeled off.

[0042] From the viewpoint of further improving observability, the transmittance at a wavelength of 1000 nm of the composition for concrete of this embodiment is preferably 30% or more, more preferably 35% or more, more preferably 40% or more, even more preferably 50% or more, even more preferably 55% or more, even more preferably 58% or more, and even more preferably 60% or more, and the upper limit is not particularly limited, but may be, for example, 100% or less, 99% or less, 95% or less, or 90% or less.

[0043] The transmittance of the composition for concrete of this embodiment at a wavelength of 1000 nm can be controlled, for example, by each of the constituent components, such as the resin and pigment, contained in the composition for concrete. Specifically, it can be controlled by using a near-infrared transmitting pigment as the pigment contained in the composition for concrete; by adjusting the content of the pigment in the composition for concrete; etc.

[0044] From the viewpoint of further improving the appearance, the transmittance at a wavelength of 600 nm of the composition for concrete of this embodiment is preferably 58% or less, more preferably 55% or less, even more preferably 50% or less, even more preferably 40% or less, even more preferably 30% or less, even more preferably 20% or less, even more preferably 15% or less, and even more preferably 10% or less, and the lower limit is not particularly limited, and may be, for example, 0.0% or more, or 0.1% or more.

[0045] The transmittance at a wavelength of 600 nm of the composition for concrete of this embodiment can be controlled, for example, by each of the constituent components, such as the resin and pigment, contained in the composition for concrete. Specifically, it can be controlled by including one or more pigments selected from the group consisting of black pigments and white pigments as the pigment contained in the composition for concrete; by adjusting the content of the pigment in the composition for concrete; etc.

[0046] Hereinafter, the lightness L of the concrete composition of this embodiment will be referred to as * (white board), chromaticity a *(white board), chromaticity b * (white board), brightness L * (Blackboard), chromaticity a * (blackboard), chromaticity b * (Blackboard), Lightness difference ΔL * , chromaticity difference Δa * , chromaticity difference Δb * , color difference ΔE * ab These values ​​refer to values ​​obtained by color difference measurement 1.

[0047] <Color difference measurement 1> A hardened concrete composition formed to a thickness of 1 mm is prepared as color difference measurement sample 1. The color difference measurement sample 1 is placed on a standard white board and chromaticity measurement is performed. * a * b * Lightness L in color space * (white board), chromaticity a * (white board), chromaticity b * (White board) is obtained. The color difference measurement sample 1 is placed on the standard black board, and the chromaticity is measured. * a * b * Lightness L in color space * (Blackboard), chromaticity a * (blackboard), chromaticity b * (Blackboard) is obtained. Then, the brightness L * (Whiteboard) to Lightness L * (Blackboard) subtracted value is the brightness difference ΔL * , chromaticity a * (White board) to chromaticity a * (Blackboard) subtracted value is chromaticity difference Δa * , chromaticity b * (White board) to chromaticity b * (Blackboard) is subtracted and the chromaticity difference is Δb * As the brightness difference ΔL * , chromaticity difference Δa * , chromaticity difference Δb * The color difference ΔE is calculated based on the following formula (1): * ab get.

[0048]

number

[0049] The color difference measurement sample 1 can be prepared, for example, by the same method as the transmittance measurement sample 1.

[0050] The lightness L of the concrete composition of this embodiment * (White board) is not particularly limited, but may be, for example, 5 or more and 95 or less. The lightness L of the concrete composition of this embodiment * (Blackboard) is not particularly limited, but may be, for example, 2 or more and 95 or less, or 3 or more and 85 or less.

[0051] The lightness difference ΔL of the concrete composition of this embodiment * From the viewpoint of further improving the appearance, is preferably 40 or less, more preferably 35 or less, even more preferably 30 or less, even more preferably 20 or less, even more preferably 10 or less, and even more preferably 5 or less, and the lower limit is not particularly limited and may be, for example, -1 or more, -0.1 or more, or -0.05 or more.

[0052] Color a of the concrete composition of this embodiment * (White board) is not particularly limited, but may be, for example, -10 or more and 10 or less, or -5 or more and 5 or less. Color a of the concrete composition of this embodiment * (Blackboard) is not particularly limited, but may be, for example, between -10 and 10, or between -5 and 5. Color difference Δa of the concrete composition of this embodiment * is not particularly limited, and may be, for example, -10 or more and 10 or less, or -5 or more and 5 or less. Color difference Δa of the concrete composition of this embodiment * By setting the content of the polymer in the above range, the color of the composition for concrete can be made similar to the color of concrete (for example, gray).

[0053] Color b of the concrete composition of this embodiment * (White board) is not particularly limited, and may be, for example, -25 or more and 25 or less, -15 or more and 15 or less, -10 or more and 10 or less, or -5 or more and 5 or less. Color b of the concrete composition of this embodiment * (Blackboard) is not particularly limited, and may be, for example, -15 or more and 15 or less, -10 or more and 10 or less, or -5 or more and 5 or less. Color difference Δb of the concrete composition of this embodiment * is not particularly limited, and may be, for example, -20 or more and 20 or less, -10 or more and 10 or less, or -5 or more and 5 or less. Color difference Δb of the concrete composition of this embodiment * By setting the content of the polymer in the above range, the color of the composition for concrete can be made similar to the color of concrete (for example, gray).

[0054] Color difference ΔE of the concrete composition of this embodiment * ab From the viewpoint of further improving the appearance, is preferably 35 or less, more preferably 33 or less, even more preferably 30 or less, even more preferably 27 or less, even more preferably 23 or less, even more preferably 20 or less, even more preferably 15 or less, even more preferably 10 or less, even more preferably 8 or less, even more preferably 5 or less, even more preferably 4 or less, and even more preferably 2 or less, and the lower limit is not particularly limited, but may be 0.01 or more, or 0.02 or more.

[0055] The lightness L of the concrete composition of this embodiment * (white board), chromaticity a * (white board), chromaticity b * (white board), brightness L * (Blackboard), chromaticity a * (blackboard), chromaticity b * (Blackboard), Lightness difference ΔL * , chromaticity difference Δa *, chromaticity difference Δb * , color difference ΔE * ab can be controlled, for example, by each of the constituent components, such as the resin and the pigment, contained in the composition for concrete. Specifically, the composition for concrete can include one or more pigments selected from the group consisting of black-based pigments and white-based pigments; by adjusting the content of the pigment in the composition for concrete; etc.

[0056] The composition for concrete of the present embodiment is preferably a curing type resin composition. The curable resin composition is preferably any one selected from the group consisting of a moisture-curable resin composition and a room temperature-curable resin composition, and more preferably a moisture-curable resin composition.

[0057] The composition for concrete of the present embodiment is preferably a paint.

[0058] The concrete composition of the present embodiment is preferably liquid at 23°C.

[0059] The components contained in the concrete composition of this embodiment are not particularly limited, but preferably contain a resin (A) and a pigment (B), more preferably contain a resin (A), a pigment (B), silica particles, and a crosslinking agent, and even more preferably contain a resin (A), a pigment (B), silica particles, a crosslinking agent, and a light stabilizer.

[0060] Hereinafter, preferred components contained in the composition for concrete of the present embodiment will be specifically described.

[0061] <Resin (A)> The composition for concrete of the present embodiment preferably contains a resin (A). The resin (A) is not particularly limited, but preferably contains at least one selected from the group consisting of modified silicone resins, urethane resins, urea resins, urethane urea resins, epoxy resins, and (meth)acrylic resins, and more preferably contains a modified silicone resin.

[0062] The modified silicone resin refers to a polymer having two or more reactive silyl groups in the molecule, and includes those in which reactive silyl groups are added to a polymer that serves as the main chain.

[0063] In the modified silicone resin, examples of the polymer to which the reactive silyl group is added include polyether-based polymers such as polyoxyethylene, polyoxypropylene, and polyoxybutylene; aliphatic hydrocarbon-based polymers such as polyisoprene, polyisobutylene, and polybutadiene; acrylic polymers such as poly(meth)acrylic acid and poly(meth)acrylate; and polyester-based polymers. Among these, polyether-based polymers are preferred, polyoxyalkylene is more preferred, and polyoxypropylene is even more preferred.

[0064] The polymer backbone to which the reactive silyl group is added may be linear or branched, but is preferably linear.

[0065] The polymer to which the reactive silyl group is added may be used alone or in combination of two or more kinds.

[0066] In the modified silicone resin, examples of the reactive silyl group include an addition-reactive silyl group, a condensation-reactive silyl group, and a hydrolyzable silyl group. Specific examples include groups in which a reactive group such as a hydrogen atom, a hydroxyl group, an alkoxy group, a halogen atom, an acyloxy group, an alkenyloxy group, an oxime group, a ketoximate group, an amide group, an acid amide group, a mercapto group, or an aminooxy group is bonded to a silicon atom.

[0067] Preferred examples of the reactive silyl group include alkoxysilyl groups such as trimethoxysilyl group, dimethoxymethylsilyl group, dimethylmethoxysilyl group, triethoxysilyl group, diethoxymethylsilyl group, dimethylethoxysilyl group, dimethoxyphenylsilyl group, diphenylmethoxysilyl group, diethoxyphenylsilyl group, and diphenylethoxysilyl group; and polymerizable reactive silyl groups such as dialkylsilicone, alkylalkoxysilicone, dialkoxysilicone, diphenylsilicone, and alkoxyphenylsilicone in which these alkoxysilyl groups are bonded to the terminals. Of these, the dimethoxymethylsilyl group is more preferred.

[0068] The modified silicone resin preferably contains at least one selected from the group consisting of modified silicone resin A having two or more reactive silyl groups at its terminals (particularly both terminals) and modified silicone resin B having one reactive silyl group at its terminals (particularly both terminals), and more preferably contains both modified silicone resin A and modified silicone resin B.

[0069] The viscosity of modified silicone resin A at 23°C is preferably 100 mPa·s or more, more preferably 500 mPa·s or more, even more preferably 1000 mPa·s or more, and preferably 7000 mPa·s or less, more preferably 5000 mPa·s or less, even more preferably 3000 mPa·s or less. The viscosity of modified silicone resin B at 23°C is preferably 7500 mPa·s or more, more preferably 10000 mPa·s or more, even more preferably 20000 mPa·s or more, and preferably 50000 mPa·s or less, more preferably 45000 mPa·s or less, even more preferably 40000 mPa·s or less. The viscosity of the modified silicone resin in this embodiment refers to a value measured using a B-type rotational viscometer (for example, Brookfield Viscometer RVDV1M, manufactured by Eiko Seiki Co., Ltd.) under conditions of 23° C. and a rotation speed of 20 rpm.

[0070] The content ratio of modified silicone resin A to modified silicone resin B in the modified silicone resin (modified silicone resin A:modified silicone resin B) is, in mass terms, for example, 40:60 to 99:1, preferably 45:55 to 90:10, and more preferably 50:50 to 80:20.

[0071] The viscosity of resin (A) at 23°C is preferably 1000 mPa·s or more, more preferably 5000 mPa·s or more, even more preferably 8000 mPa·s or more, and preferably 100,000 mPa·s or less, more preferably 90,000 mPa·s or less, even more preferably 50,000 mPa·s or less, even more preferably 30,000 mPa·s or less. The viscosity of the resin (A) herein means a value measured using a B-type rotational viscometer (for example, Brookfield Viscometer RVDV1M, manufactured by Eiko Seiki Co., Ltd.) under conditions of 23° C. and a rotation speed of 20 rpm. When resin (A) is composed of two or more resins, the viscosity of resin (A) at 23° C. means the viscosity of a mixture of two or more resins.

[0072] As the resin (A), one type of resin may be used, or two or more types of resins may be used.

[0073] <Pigment (B)> The composition for concrete of the present embodiment preferably contains a pigment (B).

[0074] From the viewpoint of further improving observation properties, the pigment (B) preferably contains a near-infrared transmitting pigment. Here, the near-infrared transmitting pigment means a pigment that easily transmits light having a wavelength of 900 nm or more and 1200 nm or less.

[0075] Examples of near-infrared transmitting pigments include metal oxide pigments, calcium carbonate, phthalocyanine pigments, and azo pigments. Furthermore, the near-infrared transmitting pigment may be a so-called heat shielding pigment.

[0076] The pigment (B) preferably includes one or more pigments selected from the group consisting of a black pigment (B-1) and a white pigment (B-2), and more preferably includes a black pigment (B-1) and a white pigment (B-2).

[0077] The black pigment (B-1) is not particularly limited as long as it is a black pigment, but preferably contains at least one selected from the group consisting of metal oxide pigments, phthalocyanine pigments, azo pigments, melanin pigments, carbon black, metal oxynitride pigments, metal nitride pigments, bisbenzofuranone pigments, azomethine pigments, and perylene pigments, more preferably contains at least one selected from the group consisting of metal oxide pigments, phthalocyanine pigments, azo pigments, melanin pigments, and carbon black, and more preferably contains at least one selected from the group consisting of metal oxide pigments and phthalocyanine pigments. An example of the metal oxynitride pigment is titanium black. An example of the metal nitride pigment is titanium nitride.

[0078] The white pigment (B-2) is not particularly limited as long as it is a white pigment, but preferably contains at least one selected from the group consisting of calcium carbonate, titanium oxide, silica, alumina, zinc oxide, zirconia, glass, crosslinked (meth)acrylic particles, crosslinked polystyrene resin, melamine resin, phenolic resin, epoxy resin, polycarbonate, and fluorine-based compounds, more preferably contains at least one selected from the group consisting of calcium carbonate and titanium oxide, and more preferably contains calcium carbonate. Examples of the fluorine-based compound include magnesium fluoride and calcium fluoride.

[0079] The content of pigment (B) in the concrete composition of this embodiment, when the content of resin (A) in the concrete composition is 100 parts by mass, is preferably 0.005 parts by mass or more, more preferably 0.01 parts by mass or more, even more preferably 0.1 parts by mass or more, even more preferably 1 part by mass or more, even more preferably 5 parts by mass or more, even more preferably 10 parts by mass or more, and is preferably 40 parts by mass or less, more preferably 35 parts by mass or less, even more preferably 30 parts by mass or less, and even more preferably 20 parts by mass or less.

[0080] The content of the black pigment (B-1) in the composition for concrete of this embodiment is, relative to the content of the resin (A) in the composition for concrete of 100 parts by mass, preferably 0.005 parts by mass or more, more preferably 0.01 parts by mass or more, even more preferably 0.05 parts by mass or more, and is preferably 1.0 part by mass or less, more preferably 0.7 parts by mass or less, and even more preferably 0.5 parts by mass or less.

[0081] The content of the white pigment (B-2) in the concrete composition of this embodiment, relative to the content of the resin (A) in the concrete composition being 100 parts by mass, is preferably 0.1 parts by mass or more, more preferably 1 part by mass or more, even more preferably 5 parts by mass or more, even more preferably 10 parts by mass or more, and is preferably 40 parts by mass or less, more preferably 35 parts by mass or less, even more preferably 30 parts by mass or less, and even more preferably 20 parts by mass or less.

[0082] <Silica> The composition for concrete of the present embodiment preferably contains silica particles from the viewpoint of preventing dripping of the composition for concrete. The content of silica particles in the concrete composition of this embodiment is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and preferably 10 parts by mass or less, more preferably 5 parts by mass or less, and even more preferably 3 parts by mass or less, relative to 100 parts by mass of the resin (A) in the concrete composition.

[0083] <Crosslinking agent> The concrete composition of the present embodiment preferably contains a crosslinking agent. The crosslinking agent is not particularly limited, but when a modified silicone resin is contained as the resin (A), it is preferable to contain a silane coupling agent.

[0084] Examples of silane coupling agents include aminosilane-based compounds such as 3-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, and N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane; epoxysilane-based compounds such as γ-glycidoxypropyltrimethoxysilane; vinylsilane-based compounds such as γ-(meth)acryloxypropyltrimethoxysilane; cationic silane-based compounds such as N-β-(N-vinylbenzylaminoethyl)-γ-aminopropyltrimethoxysilane hydrochloride; and phenylsilane-based compounds. Among these, aminosilane-based compounds are preferred, and 3-aminopropyltrimethoxysilane is more preferred.

[0085] The content of the crosslinking agent in the composition for concrete of this embodiment is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and preferably 10 parts by mass or less, more preferably 8 parts by mass or less, and even more preferably 5 parts by mass or less, relative to 100 parts by mass of the resin (A) in the composition for concrete.

[0086] The crosslinking agents may be used alone or in combination of two or more.

[0087] <Light stabilizer> The concrete composition of the present embodiment preferably contains a light stabilizer. The light stabilizer is not particularly limited, but for example, a hindered amine light stabilizer can be used.

[0088] Examples of the hindered amine light stabilizer include N-OR type hindered amine compounds, NR type hindered amine compounds, and NH type hindered amine compounds. Here, R represents a hydrocarbon group, and N-OR type and NR type refer to those in which an OR group and an R group are bonded to a nitrogen atom of a piperidyl skeleton. In addition, NH type refers to those in which a hydrogen atom is bonded to a nitrogen atom of a piperidyl skeleton.

[0089] The content of the light stabilizer in the composition for concrete of this embodiment, relative to the content of the resin (A) in the composition for concrete of 100 parts by mass, is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, even more preferably 1.5 parts by mass or more, even more preferably 2 parts by mass or more, and is preferably 10 parts by mass or less, more preferably 8 parts by mass or less, even more preferably 5 parts by mass or less, and even more preferably 3 parts by mass or less.

[0090] The light stabilizers may be used alone or in combination of two or more.

[0091] <Curing catalyst> The concrete composition of the present embodiment preferably contains a curing catalyst. The curing catalyst includes at least one selected from the group consisting of tin-based catalysts, titanium-based catalysts, aluminum-based catalysts, zinc-based catalysts, iron-based catalysts, phosphorus-based catalysts, and the like. When the resin (A) contains a modified silicone resin, it is preferable to use a curing catalyst that catalyzes the reaction of the reactive silyl group contained in the modified silicone resin. The content of the curing catalyst in the concrete composition of the present embodiment is an appropriate amount.

[0092] <Textile> The composition for concrete of the present embodiment may further contain fibers from the viewpoint of further improving the strength of a hardened product made of the composition.

[0093] The fibers include, for example, at least one selected from the group consisting of glass fibers, (meth)acrylic fibers, polyethylene fibers, nylon 6 fibers, nylon 6,6 fibers, polyester fibers, polypropylene fibers, vinylon fibers, aramid fibers, BPO (polyparaphenylenebenzoxazole) fibers, and carbon fibers, and among these, glass fibers are preferred.

[0094] The fiber length of the fibers is, for example, 0.1 mm or more and 50 mm or less, and preferably 3 mm or more and 10 mm or less. The fiber diameter of the fibers is, for example, 0.1 μm or more and 30 μm or less, and preferably 4 μm or more and 10 μm or less. The cross-sectional shape of the fiber is not particularly limited, and may be a perfect circle or an ellipse. The fibers may be cut fibers or may be in the form of a sheet of woven or nonwoven fabric.

[0095] The total content of fibers in the concrete composition of this embodiment, when the total of non-volatile components in the concrete composition is 100 mass%, is preferably 0.1 mass% or more, more preferably 0.5 mass% or more, even more preferably 1 mass% or more, and is preferably 15 mass% or less, more preferably 10 mass% or less, even more preferably 5 mass% or less.

[0096] <Other ingredients> The concrete composition of the present embodiment may further contain other components. The composition for concrete of the present embodiment may further contain, for example, an ultraviolet absorbing agent, an antioxidant, and the like. The contents of the other components are each appropriate amounts.

[0097] The total content of the resin (A) and pigment (B) in the composition for concrete of this embodiment is, when the total of the non-volatile components in the composition for concrete is 100 mass%, preferably 80 mass% or more, more preferably 85 mass% or more, even more preferably 90 mass% or more, and is preferably 98 mass% or less, more preferably 96 mass% or less.

[0098] The total content of the resin (A), pigment (B), silica, crosslinking agent and light stabilizer in the composition for concrete of this embodiment is, when the total of the non-volatile components in the composition for concrete is 100 mass%, preferably 85 mass% or more, more preferably 90 mass% or more, even more preferably 95 mass% or more, even more preferably 97 mass% or more, and preferably 100 mass% or less.

[0099] The concrete composition of the present embodiment can be obtained, for example, by mixing the respective components.

[0100] <Primer composition> A preferred embodiment of the primer composition constituting the layer 20 made of the primer composition will be described.

[0101] The primer composition of the present embodiment contains, for example, a resin. The resin contained in the primer composition is not particularly limited, and may include, for example, one or more selected from the group consisting of (meth)acrylic resins, olefin resins, vinyl acetate resins, urethane resins, epoxy resins, aminated epoxy resins, urea resins, silicone resins, and modified resins thereof, and among these, preferably includes a modified silicone resin, and more preferably includes a silicone-modified (meth)acrylic copolymer resin.

[0102] The primer composition of the present embodiment may contain an organic solvent. The organic solvent includes, for example, polar organic solvents, more specifically, ether-based solvents, alcohol-based solvents, ketone-based solvents, ester-based solvents, and the like. From the viewpoint of further improving the film formation stability, the organic solvent may contain a high boiling point solvent having a boiling point of 50° C. or more, preferably 100° C. or more, more preferably 120° C. or more. The upper limit of the boiling point of the solvent is not particularly limited, but may be, for example, 300° C. or less or 200° C. or less.

[0103] The primer composition of the present embodiment may contain, for example, a filler, a pigment, an ultraviolet absorber, a light stabilizer, an antioxidant, a silane coupling agent, a thickener, etc. The content of each of these components is an appropriate amount.

[0104] The total content of non-volatile components contained in the primer composition of this embodiment, when the total content of all components contained in the primer composition is 100 mass%, is, from the viewpoint of further improving the performance balance between film-formability and handleability, preferably 20 mass% or more, more preferably 30 mass% or more, and even more preferably 40 mass% or more, and from the viewpoint of further improving the performance balance between film-formability and handleability, is preferably 100 mass% or less, more preferably 70 mass% or less, and even more preferably 60 mass% or less.

[0105] The primer composition of the present embodiment can be obtained, for example, by mixing the respective components.

[0106] <Topcoat composition> A preferred embodiment of the topcoat composition constituting layer 30 made of the topcoat composition will now be described.

[0107] The topcoat coating composition of the present embodiment contains, for example, a resin. The resin contained in the topcoat composition is not particularly limited, and may include, for example, one or more selected from the group consisting of fluororesin, (meth)acrylic resin, (meth)acrylic silicone resin, (meth)acrylic urethane resin, urethane resin, olefin resin, vinyl acetate resin, ethylene-vinyl acetate copolymer resin, silicone resin, and modified resins thereof, and among these, preferably includes (meth)acrylic urethane resin.

[0108] The topcoat composition of this embodiment preferably contains a curing agent. Examples of the curing agent include an isocyanate-based curing agent.

[0109] The topcoat composition of this embodiment may contain an organic solvent.

[0110] The topcoat composition of the present embodiment may contain, for example, a filler, a pigment, an ultraviolet absorber, a light stabilizer, an antioxidant, a silane coupling agent, a thickener, etc. The content of each of these components is an appropriate amount.

[0111] The total content of non-volatile components contained in the topcoat composition of this embodiment, when the total content of all components contained in the topcoat composition is 100 mass%, is preferably 20 mass% or more, more preferably 30 mass% or more, even more preferably 40 mass% or more, and is preferably 100 mass% or less, more preferably 70 mass% or less, even more preferably 60 mass% or less.

[0112] The topcoat coating composition of this embodiment can be obtained, for example, by mixing the respective components.

[0113] [Method of manufacturing concrete structures] The method for producing the concrete structure 100 is not particularly limited, and for example, a method in which a composition for concrete is applied onto concrete 50 to form a layer 10 made of a composition for concrete can be mentioned.

[0114] The method for manufacturing the concrete structure 100 preferably includes a step of forming a layer 20 of a primer composition on the surface of the concrete 50, and a step of forming a layer 10 of a concrete composition on the layer 20 of the primer composition.

[0115] The method for forming the layer 20 made of the primer composition on the surface of the concrete 50 is not particularly limited, but an example thereof includes a method in which the primer composition is applied to the surface of the concrete 50 and dried.

[0116] The method for forming layer 10 made of a composition for concrete on layer 20 made of a composition for primer is not particularly limited, but an example thereof includes a method of applying a composition for concrete on layer 20 made of a composition for primer.

[0117] The method for producing the concrete structure 100 may further include a step of forming a layer 30 made of a topcoat composition on the layer 10 made of a concrete composition.

[0118] The method for forming layer 30 made of a topcoat composition on layer 10 made of a concrete composition is not particularly limited, but an example of the method includes applying a topcoat composition onto layer 10 made of a concrete composition and drying it.

[0119] [Deformation management method] The method for managing deterioration of concrete in this embodiment includes a step of irradiating the surface of the concrete structure 100 on the side of the layer 10 made of a composition for concrete with light having a wavelength in the near-infrared region.

[0120] The wavelength of the near infrared region is, for example, 750 nm or more and 2500 nm or less, preferably 800 nm or more and 1500 nm or less.

[0121] The method for managing concrete deterioration in this embodiment preferably includes a step of observing the surface of concrete 50 by irradiating light with a wavelength in the near-infrared region onto the surface of concrete structure 100 facing layer 10 made of a concrete composition, and observing the reflected light with a near-infrared camera.

[0122] Although the embodiments of the present invention have been described above, these are merely examples of the present invention, and various configurations other than those described above can be adopted. Furthermore, the present invention is not limited to the above-described embodiments, and modifications and improvements within the scope of the present invention are included in the present invention. EXAMPLES

[0123] The present invention will be described in detail below with reference to examples, but the present invention is not limited to the description of these examples.

[0124] [Raw materials] First, the raw materials constituting the concrete composition will be described.

[0125] <Resin (A)> Modified silicone resin 1 (manufactured by Asahi Kasei Wacker Silicone Co., Ltd., product name: GENIOSIL XB502, viscosity at 23°C (measured using a B-type rotational viscometer (manufactured by Eiko Seiki Co., Ltd., product name: Brookfield viscometer RVDV1M) at a rotation speed of 20 rpm): 1300 mPa·s, modified silicone resin having two or more silicon atoms bonded to methoxy groups at each end, having a polyoxypropylene structure as a polyether polymer, and having a dimethoxymethylsilyl group as a reactive silyl group) Modified silicone resin 2 (manufactured by Asahi Kasei Wacker Silicone Co., Ltd., product name: GENIOSIL STP-E30, viscosity at 23°C (measured using a B-type rotational viscometer (manufactured by Eiko Seiki Co., Ltd., product name: Brookfield viscometer RVDV1M) at a rotation speed of 20 rpm): 30,000 mPa s, modified silicone resin having one silicon atom bonded to a methoxy group at each end, having a polyoxypropylene structure as a polyether polymer, and having a dimethoxymethylsilyl group as a reactive silyl group)

[0126] The viscosity at 23°C of a resin obtained by mixing 70 mass% of modified silicone resin 1 and 30 mass% of modified silicone resin 2 was 10,000 mPa s. Here, the viscosity at 23°C refers to a value measured using a B-type rotational viscometer (manufactured by Eiko Seiki Co., Ltd., product name: Brookfield Viscometer RVDV1M) at a rotation speed of 20 rpm.

[0127] <Black pigment (B-1)> Black pigment 1 (manufactured by Dainichiseika Color & Chemicals Co., Ltd., product name: Dipyroxide Black #9583, metal oxide pigment (iron-cobalt-aluminum), near infrared transmitting pigment, particle size: 0.06 μm) Black pigment 2 (manufactured by Dainichi Seika Chemicals Co., Ltd., product name: Chromofine Black A1103, phthalocyanine pigment, near infrared transmitting pigment) Black pigment 3 (manufactured by Denka Co., Ltd., product name: DENKA BLACK Li Li-100, acetylene black)

[0128] <White pigment (B-2)> White pigment 1 (Takehara Chemical Industry Co., Ltd., product name: NEOLIGHT SP, calcium carbonate, near infrared transmitting pigment, particle size: 0.08 μm) White pigment 2 (manufactured by Ishihara Sangyo Kaisha, Ltd., product name: TIPAQUE PFC105, titanium oxide, particle size: 0.28 μm)

[0129] <Silica particles> Silica particles 1 (manufactured by Wacker Asahi Kasei Silicone Co., Ltd., product name: HDK H18, particle size: 10 nm)

[0130] <Crosslinking agent> Crosslinking agent 1 (manufactured by Wacker Asahi Kasei Silicone Co., Ltd., product name: GENIOSIL GF96, 3-aminopropyltrimethoxysilane)

[0131] <Light stabilizer> Light stabilizer 1 (manufactured by BASF Japan Ltd., product name: Tinuvin B75, a mixture of UV absorber, NR-type hindered amine light stabilizer, and antioxidant)

[0132] [Examples 1 to 14 and Comparative Examples 1 to 9] <Preparation of concrete composition> Each raw material other than the crosslinking agent was weighed based on the formulation shown in Tables 1 and 2, and each raw material was stirred for 5 minutes to obtain the base material. The obtained base agent and crosslinking agent were mixed according to the formulations shown in Tables 1 and 2 to obtain concrete compositions of Examples 1 to 14 and Comparative Examples 1 to 9, respectively.

[0133] <Primer composition> The primer composition used was 8SQ-1052 (manufactured by Taisei Fine Chemical Co., Ltd.) The primer composition is a mixture of silicone-modified acrylic copolymer and methoxypropyl acetate (PGMAC, boiling point 146°C), with a non-volatile content of 45% and a viscosity of 600 mPa s.

[0134] <Preparation of concrete slab> In accordance with the method for preparing test substrates in JSCE K 511, mortar with a water / cement ratio of 50% and a sand / cement ratio of 3 was placed in a metal formwork with inner dimensions of 70 mm length x 150 mm width x 10 mm thickness, and cured for 24 hours at a temperature of 20±2°C and a relative humidity of 80% or more, and then removed from the formwork, and cured in water for 6 days at a temperature of 20±2°C. After the underwater curing was completed, the concrete plate was cured for 7 days or more at a temperature of 23±2°C and a relative humidity of 50±5% to obtain a concrete plate. A temporary fixing tape was attached to one side of the obtained concrete plate, and the side opposite to the side where the temporary fixing tape was attached was hit with a hammer to create cracks. Next, the temporary fixing tape was peeled off from the concrete plate. Here, the cracks in the concrete were 0.1 mm or more and 5 mm or less in width and 5 mm or more and 100 mm or less in length. In addition, there were 15 cracks in the concrete.

[0135] The primer composition was applied to the cracked surface of the concrete plate at a coating weight of 0.15 kg / m 2 Then, the composition for concrete of each of Examples 1 to 14 and Comparative Examples 1 to 9 was applied on the layer of the composition for primer at a coating amount of 1.5 kg / m. 2 and then allowed to stand at 23°C and 50% relative humidity for 7 days to harden the composition for concrete and form a layer made of the composition for concrete, thereby obtaining concrete structures of Examples 1 to 14 and Comparative Examples 1 to 9. The concrete structures were laminates having a three-layer structure of "concrete plate / layer made of composition for primer / layer made of composition for concrete."

[0136] [Measurement and Evaluation] Measurements and evaluations of the concrete compositions of Examples 1 to 14 and Comparative Examples 1 to 9 and the concrete structures of Examples 1 to 14 and Comparative Examples 1 to 9 are described below.

[0137] <Transmittance measurement> The concrete composition was applied to a PET film to a thickness of 1 mm, and the concrete composition was allowed to harden at 23°C and a relative humidity of 50% for 7 days. The PET film was then peeled off to obtain a sample for transmittance measurement. The transmittance of the obtained sample for transmittance measurement was measured in the wavelength range of 300 nm to 1500 nm in accordance with JIS K 0115 (2020) using a spectrophotometer (manufactured by Shimadzu Corporation, product name: SolidSpec-3700). From the obtained transmittance measurement results, the transmittance values ​​at a wavelength of 1000 nm and at a wavelength of 600 nm were obtained.

[0138] <Color difference measurement> The concrete composition was applied to a PET film to a thickness of 1 mm, and the concrete composition was allowed to harden at 23°C and a relative humidity of 50% for 7 days. The PET film was then peeled off to obtain a sample for color difference measurement.

[0139] The color difference measurement sample is placed on a standard white board (an accessory of the spectrophotometer), and the chromaticity is measured using a spectrophotometer (manufactured by Nippon Denshoku Industries Co., Ltd., product name: NF555). * a * b * Lightness L in color space * (white board), chromaticity a * (white board), chromaticity b * (White board) was obtained.

[0140] The color difference measurement sample was placed on a standard blackboard (an accessory to the spectrophotometer), and the chromaticity was measured using a spectrophotometer (manufactured by Nippon Denshoku Industries Co., Ltd., product name: NF555). * a * b * Lightness L in color space * (Blackboard), chromaticity a * (blackboard), chromaticity b * (Blackboard) each.

[0141] Next, the lightness L * (Whiteboard) to Lightness L* (Blackboard) subtracted value is the brightness difference ΔL * , chromaticity a * (White board) to chromaticity a * (Blackboard) subtracted value is chromaticity difference Δa * , chromaticity b * (White board) to chromaticity b * (Blackboard) is subtracted and the chromaticity difference is Δb * As the brightness difference ΔL * , chromaticity difference Δa * , chromaticity difference Δb * The color difference ΔE was calculated based on the following formula (1): * ab obtained.

[0142]

number

[0143] <Observation in the visible light region> The concrete structure was visually observed from the side of the layer made of the concrete composition. The extent to which the concrete surface could be observed in the visible light region was evaluated based on the following criteria. A: No cracks are observed in the concrete slab. B: Some cracks are observed in the concrete slab, but the cracks are not noticeable. C: All cracks in the concrete slab are observed and the cracks are noticeable. In the concrete structure of this embodiment, the above criteria A and B can be deemed to satisfy the requirement that "when any area of ​​70 mm × 150 mm on the surface of the concrete structure is viewed from the layer side made of the concrete composition, the entire surface of the concrete cannot be observed in the visible light range."

[0144] <Observation in the near infrared region> The surface of the layer made of the concrete composition of the concrete structure was irradiated with 900 nm light using a halogen lamp, and the reflected light was observed with a near-infrared camera. The extent to which the concrete surface could be observed in the near-infrared region was evaluated based on the following criteria. A: The surface of the concrete slab is clearly visible, all cracks can be observed, and cracks are easy to observe. B: The surface of the concrete slab is visible and cracks can be observed, but the cracks are more difficult to observe than in criterion A. C: The surface of the concrete slab is not visible, so no cracks can be observed. In the concrete structure of this embodiment, the above criteria A and B can be deemed to satisfy the requirement that "when any area of ​​70 mm × 150 mm on the surface of the concrete structure is viewed from the side of the layer made of the concrete composition, it is possible to observe part or the entire surface of the concrete in the near-infrared region."

[0145] <Overall rating> The overall evaluation of the observation evaluation in the visible light region and the observation evaluation in the near infrared region was made based on the following criteria. AA: The results of observation and evaluation in both the visible light region and the near-infrared light region were both A. A: One of the evaluation results of observation and evaluation in the visible light region and near-infrared region is A, and the other is B. B: The results of observation and evaluation in both the visible light region and the near-infrared region were B. C: At least one of the evaluation results of the observation evaluation in the visible light region and the observation evaluation in the near-infrared region is C.

[0146] The concrete compositions of Examples 1 to 14 and Comparative Examples 1 to 9 and the concrete structures of Examples 1 to 14 and Comparative Examples 1 to 9 were subjected to the above-mentioned measurements and evaluations, and the results are shown in Tables 1 and 2.

[0147] [Table 1]

[0148] [Table 2]

[0149] The concrete structures of the examples have improved appearance because no cracks or the like are observed when the concrete structures are viewed visually. Furthermore, the concrete structures of the examples have improved observability because cracks or the like can be observed when the concrete structures are viewed with light having a wavelength in the near-infrared region. In other words, it can be seen that the concrete structure of this embodiment improves the balance of performance in terms of observation ability and appearance. [Explanation of symbols]

[0150] 10 Layer made of concrete composition 20 Layer made of primer composition 30 Layer consisting of topcoat composition 50 Concrete 100 Concrete Structure

Claims

1. A concrete structure comprising concrete and a layer made of a concrete composition, A concrete structure, in which, when any region of 70 mm x 150 mm on the surface of the concrete structure is viewed from the side of the layer made of the composition for concrete, the entire surface of the concrete cannot be observed in the visible light region, but a part or the entire surface of the concrete can be observed in the near-infrared region.

2. 2. The concrete structure according to claim 1, wherein the concrete composition comprises a resin (A) and a pigment (B).

3. 3. The concrete structure according to claim 2, wherein the resin (A) comprises at least one selected from the group consisting of a modified silicone resin, a urethane resin, a urea resin, a urethane urea resin, an epoxy resin, and a (meth)acrylic resin.

4. 4. The concrete structure according to claim 2, wherein the content of the pigment (B) in the composition for concrete is 0.005 parts by mass or more and 40 parts by mass or less when the content of the resin (A) in the composition for concrete is 100 parts by mass.

5. The concrete structure according to claim 2 or 3, wherein the pigment (B) includes a near-infrared transmitting pigment.

6. The concrete structure according to claim 2 or 3, wherein the pigment (B) includes one or more selected from the group consisting of black pigments (B-1) and white pigments (B-2).

7. The black pigment (B-1) includes at least one selected from the group consisting of metal oxide pigments, phthalocyanine pigments, azo pigments, melanin pigments, carbon black, metal oxynitride pigments, metal nitride pigments, bisbenzofuranone pigments, azomethine pigments, and perylene pigments. The concrete structure according to claim 6.

8. The concrete structure according to claim 6, wherein the white pigment (B-2) includes at least one selected from the group consisting of calcium carbonate, titanium oxide, silica, alumina, zinc oxide, zirconia, glass, crosslinked (meth)acrylic particles, crosslinked polystyrene resin, melamine resin, phenolic resin, epoxy resin, polycarbonate, and fluorine-based compounds.

9. Further comprising a layer made of a primer composition; 3. The concrete structure according to claim 1, wherein the layer of the primer composition is located between the concrete and the layer of the composition for concrete.

10. Further comprising a layer of a topcoat composition; 3. The concrete structure according to claim 1, wherein the layer made of the topcoat composition is located on an opposite side to the concrete side of the layer made of the composition for concrete.

11. A method for manufacturing a concrete structure according to claim 1 or 2, forming a layer of a primer composition on the surface of the concrete; and forming a layer made of the composition for concrete on the layer made of the composition for primer.

12. A structure comprising a substrate and a layer made of a composition, When any region of 70 mm × 150 mm on the surface of the structure is viewed from the side of the layer made of the composition, the entire surface of the substrate cannot be observed in the visible light region, but a part or the entire surface of the substrate can be observed in the near-infrared region.

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