JP5158935B2 - Water absorption inhibitor composition for civil engineering and construction - Google Patents

Description

  The present invention relates to a water absorption inhibitor that has excellent permeability to a civil engineering building structure substrate, is excellent in surface water repellency, and allows easy removal of residues on the substrate surface after drying.

  It has hitherto been known that the surface of a building material is made hydrophobic by applying an organosilicon compound such as a silane compound or polysiloxane to various building materials and water permeation into the building material is suppressed. The target building materials are inorganic porous building materials such as concrete, mortar, lightweight cellular concrete, bricks, etc., and the above compounds penetrate into the pores of the porous building material and make the surface layer hydrophobic, thereby deteriorating these building materials. Aging is suppressed. Furthermore, since water repellency is also imparted, there is an effect that the adhesion of dust and the generation of mold are suppressed and the dirt is hardly attached. In particular, when applied to concrete used as a base material for civil engineering and construction structures, it penetrates the base material from the pores on the concrete surface and forms a water absorption preventing layer on the inner surface of the pores. By maintaining the air permeability of the building, it does not hinder the evaporation of moisture in the building material, and prevents the penetration of moisture, thereby suppressing deterioration such as peeling due to rust and expansion of the reinforcing bars due to the progress of neutralization There is.

  For example, Patent Document 1 discloses an emulsion in which an alkylalkoxysilane is dispersed in water using an emulsifier. Although this emulsion penetrates into concrete, silane near the applied concrete surface tends to volatilize in the atmosphere, so a water absorption prevention layer that penetrates deeply into the concrete is not formed, and the water repellency of the surface is inferior. It is necessary to recoat the divided emulsion.

  Patent Document 2 discloses a silane / siloxane emulsion in which an alkylalkoxypolysiloxane is used in addition to an alkyltrialkoxysilane. Although this method is sufficient to hydrophobize the portion near the concrete surface to which the emulsion is applied, the emulsion has a low viscosity because the silane / siloxane concentration in the emulsion is as low as about 50% at the maximum, making it more dense like civil engineering structures. When it is applied to a place other than the horizontal plane of concrete, there is a drawback that dripping is likely to occur before penetration, and the concrete becomes hydrophobic.

  Further, Patent Document 3 discloses a cream-like emulsion having a high silane / siloxane concentration, which is a polysiloxane having an alkylalkoxysilane and an amino group, or a silane / siloxane emulsion in which an alkylalkoxypolysiloxane is added thereto. Has been. Since it is creamy, dripping does not easily occur even when it is applied to a vertical surface of a civil engineering structure, but it has a drawback that it does not have sufficient permeability to dense concrete for civil engineering.

  On the other hand, Patent Document 4 discloses a coating composition that obtains water repellency by adding a hydrophobic powder and a filler to a binder, but these impair the breathability when applied to a porous building material. Deterioration such as delamination due to rust expansion of reinforcing bars and rust cannot be suppressed.

Japanese Patent Laid-Open No. 62-197369 JP-T 6-501514 Japanese Patent Laid-Open No. 10-81824 JP-A-7-118577

  When these compositions according to the prior art are applied to civil engineering structures made of dense concrete, they do not form a water absorption preventing layer with sufficient depth due to dripping or insufficient permeability. The surface water repellency was inferior, and rain streaks were likely to remain on the surface.

  An object of the present invention is to solve the problems in the case where the above-described composition according to the prior art is used for a civil engineering structure, that is, dripping can be suppressed even when applied to a vertical surface of a civil engineering structure. Another object of the present invention is to provide a water absorption inhibitor composition having excellent permeability, excellent surface water repellency, and easy removal of residues on the substrate surface after drying.

In order to solve the above problems, the present inventor has intensively studied the structure and composition of each component of the water absorption inhibitor, and as a result, found that the problem can be solved by combining silica with alkylalkoxysilane. Invented the invention. That is, the present invention
[1] It comprises (A) 100 parts by weight of an alkylalkoxysilane, and (B) 0.5 to 25 parts by weight of wet silica and / or dry silica , and (A) is represented by the general formula (1)
R ¹ _X Si (OR ² ) _4-X (1)
[Wherein, R ¹ is the same or different alkyl group having 1 to 20 carbon atoms, R ² is the same or different alkyl group having 1 to 6 carbon atoms or a hydrogen atom, and X is 1 or 2 The water absorption inhibitor composition for civil engineering and architecture represented by
[2] The water absorption inhibitor composition according to [1], wherein the silica (B) is dry silica.
[3] The water absorption inhibitor composition according to any one of [1] or [2], wherein the silica (B) is hydrophobic dry silica.

[4] The average composition of the (C) siloxane unit is represented by the formula (2)
R ³ _a R ⁴ _b SiO _{(4-ab) / 2} (2)
[Wherein, R ³ is substituted with a group containing any one or more of O, N, S, or P atoms, and may be substituted with a halogen atom, and may be the same or different. These are monovalent hydrocarbon groups or hydroxyl groups. R ⁴ is a hydrocarbon group having 1 to 10 carbon atoms which may be the same or different. a is 0.001 to 1.0, b is 0.9 to 2.4, and a + b is 1.0 to 2.5. The water absorption inhibitor composition [5] according to any one of claims 1 to 3, wherein the polyorganosiloxane represented by formula (A) is contained in an amount of 0.1 to 10 parts by weight per 100 parts by weight of (A) alkylalkoxysilane. (C) The water absorption inhibitor composition according to any one of [1] to [4], wherein the polyorganosiloxane is a polyorganosiloxane having an aminoalkyl group.
[6] The water absorption inhibitor composition according to [1] to [5], which is used for a concrete structure for civil engineering and construction.

  The composition of the present invention can prevent dripping even when applied to a vertical surface of a civil engineering building structure, has excellent permeability, imparts water repellency to the surface, and remains on the substrate surface after drying. There is an effect that it is easy to remove.

Hereinafter, the present invention will be specifically described. The alkylalkoxysilane which is the component (A) of the present invention is represented by the general formula (1).
R ¹ _X Si (OR ² ) _4-X (1)
R ¹ in formula (1) may be the same or different, and the alkyl group having 1 to 20 carbon atoms, R ² may be the same or different, the alkyl group having 1 to 6 carbon atoms or a hydrogen atom, X is 1 Or it is an integer of 2. Examples of R ¹ in the formula (1) are methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, octyl group, decyl group, dodecyl group, tetradecyl group, hexadecyl group, octadecyl group and the like. These may be one kind or two or more kinds. Among these alkyl groups, an alkyl group having 6 or 10 carbon atoms is preferable.

Examples of R ² in formula (1) are methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, t-butyl group, n-pentyl group, isopentyl group, neopentyl group, It is an alkyl group such as a t-pentyl group or n-hexyl group, and may be the same or different in the molecule. Of these, preferred R ² is an alkyl group having 1 or 2 carbon atoms.

  Specific examples of such alkylalkoxysilanes include methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, propyltrimethoxysilane, propyltriethoxysilane, butyltrimethoxysilane, and butyltriethoxy. Silane, pentyltrimethoxysilane, pentyltriethoxysilane, hexyltrimethoxysilane, hexyltriethoxysilane, heptyltrimethoxysilane, heptyltriethoxysilane, octyltrimethoxysilane, octyltriethoxysilane, nonyltrimethoxysilane, nonyltriethoxy Silane, decyltrimethoxysilane, decyltriethoxysilane, undecyltrimethoxysilane, undecyltriethoxysilane, dodecyltrimethyl Xysilane, dodecyltriethoxysilane, tridecyltrimethoxysilane, tridecyltriethoxysilane, tetradecyltrimethoxysilane, tetradecyltriethoxysilane, pentadecyltrimethoxysilane, pentadecyltriethoxysilane, hexadecyltrimethoxysilane, hexa Examples include decyltriethoxysilane, heptadecyltrimethoxysilane, heptadecyltriethoxysilane, octadecyltrimethoxysilane, octadecyltriethoxysilane, dimethyldimethoxysilane, octylmethyldimethoxysilane, and octadecylmethyldimethoxysilane.

Among them, hexyltrimethoxysilane, hexyltriethoxysilane, octyltrimethoxysilane, octyltriethoxysilane, and decyltrimethoxysilane in which the alkyl group represented by R ¹ in formula (1) has 6 or more carbon atoms are preferably used. It is done. These alkyl alkoxysilanes can also be used as partial condensates or mixtures.

  In the water absorption inhibitor composition of the present invention, as the component (B), silica produced by a method known to those skilled in the art can be used. For example, wet silica synthesized by a sedimentation method in which sodium silicate and mineral acid are reacted on the alkali side to precipitate silica that is easy to filter, and a mixture of vaporized silicon tetrachloride and hydrogen at 1000 to 1200 ° C. or higher. Dry silica synthesized by a combustion method that burns in air to obtain very fine particles of about 10 nm, dry silica is heated to about 400 ° C. together with a hydrophobized surface treatment agent and an inert carrier gas, to dry silica Examples thereof include hydrophobic dry silica synthesized by reacting a silanol group having a hydrophilic surface with a hydrophobizing surface treatment agent. Examples of the hydrophobizing surface treatment agent include organopolysiloxane, organopolysilazane, chlorosilane, and alkoxysilane. In the present invention, the silica is preferably dry silica, and hydrophobic dry silica is particularly preferably used. These silicas may be used alone or in combination of two or more.

  In the present invention, silica is an important component for solving the problems of the present invention. Conventionally, silica has the effect of adjusting the viscosity and preventing dripping when applied to a vertical surface when added to an organic resin such as unsaturated polyester resin or polyorganosiloxane in sealants for paints and building materials. Is known. However, the viscosity of the alkylalkoxysilane is greatly improved by using the silica of the component (B) for the alkylalkoxysilane of the component (A), which has a very low viscosity, and the viscosity is adjusted to drastically improve the dripping of the mixture. It was not expected to do. Component (B), especially hydrophobic dry silica, is particularly excellent in compatibility and wetting action with component (A) alkylalkoxysilane. It is thought that outflow and volatilization are suppressed. At the same time, it is considered that the surface water repellency was greatly improved in order to develop the lotus effect on the substrate surface after drying.

  The component (B) needs to be 0.5 to 25 parts by weight, preferably 2 to 10 parts by weight with respect to 100 parts by weight of the component (A). If the amount is less than 0.5 part by weight, the effect of silica addition is not sufficient, so that the liquid dripping does not form a water absorption preventing layer having a sufficient depth, resulting in poor surface water repellency. On the other hand, when the amount is more than 25 parts by weight, the viscosity of the water absorption inhibitor composition is too high, so that the workability of coating is inferior, and a large amount of residue adheres to the substrate surface.

  In the present invention, a polyorganosiloxane having a polar group can be used as the component (C). The polyorganosiloxane having a polar group increases the effect of the silica of the component (B), and even if the amount of the component (B) is decreased, the intended effect of the present invention can be achieved. The component (B) remains on the surface after the composition of the present invention is applied to a civil engineering structure. When the component (C) is used, the residual amount of the component (B) can be reduced. There is also an effect that it is easy to remove objects.

In the polyorganosiloxane having a polar group which is the component (C) of the present invention, the average composition of the siloxane unit is represented by the general formula (2).
R ³ _a R ⁴ _b SiO _{(4-ab) / 2} (2)
It is polyorganopolysiloxane represented by these.
R ³ in Formula (2) is substituted with a group containing any one or more of O, N, S, or P atoms, and may be substituted with a halogen atom, and may be the same or different carbon number ˜20 monovalent hydrocarbon group, or hydroxyl group , R ⁴ is the same or different hydrocarbon group having 1 to 10 carbon atoms . a is 0.001 to 1.0, b is 0.9 to 2.4, and a + b is 1.0 to 2.5. The component (C) can be used in an amount of 0.1 to 10 parts by weight with respect to 100 parts by weight of the alkylalkoxysilane as the component (A).

Examples of R ³ include a hydrocarbon group containing a polar group in the structure. Examples of polar groups containing one or more of O, N, S or P atoms constituting R ³ include methyl acrylate group, acrylate group, epoxy group (glycidyl group), amino group, aminoalkyl group, hydroxyamino Group, carbonyl group, dicarbonyl group, acid anhydride group, aldehyde group, isocyanate group, mercapto group, alkyl mercapto group, polyoxyalkylene group, formamide group, acetamide group, cyano group, amide group, imide group, hydroxyl group, oxazoline Group and the like. As the hydrocarbon group constituting R ³ , methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, t-butyl group, pentyl group, neopentyl group, hexyl group, 2-ethylhexyl group, heptyl group Alkyl groups such as octyl group, nonyl group, decyl group and dodecyl group; cycloalkyl groups such as cyclopentyl group, cyclohexyl group and cycloheptyl group; aryl groups such as phenyl group, tolyl group, xylyl group, biphenyl group and naphthyl group An aralkyl group such as a benzyl group, a phenylethyl group, a phenylpropyl group, or a methylbenzyl group; a chloromethyl group in which some of the hydrogen atoms in these hydrocarbon groups are substituted by a halogen atom, a 2-bromoethyl group, 3, 3,3-trifluoropropyl group, 3-chloropropyl group, chloropheny And halogen-substituted hydrocarbon groups such as a dialkyl group, a dibromophenyl group, a tetrachlorophenyl group, and a difluorophenyl group. R ³ may be the same or different in the molecule.

Examples of R ³ are hydroxyl group, aminopropyl group, N-aminoethyl-aminopropyl group, mercaptopropyl group, methyl acrylatepropyl group, polyoxyethylenepropyl group and the like.

R ⁴ in the formula (2) is a hydrocarbon group having 1 to 10 carbon atoms. Examples of R ⁴ include methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, t-butyl group, pentyl group, neopentyl group, hexyl group, 2-ethylhexyl group, heptyl group, octyl group, Alkyl groups such as nonyl and decyl; cycloalkyl groups such as cyclopentyl, cyclohexyl and cycloheptyl; aryl groups such as phenyl, tolyl, xylyl and biphenyl; benzyl, phenylethyl and phenylpropyl Group, aralkyl group such as methylbenzyl group; chloromethyl group, 2-bromoethyl group, 3,3,3-trifluoropropyl group in which some or all of hydrogen atoms in these hydrocarbon groups are substituted by halogen atoms 3-chloropropyl group, chlorophenyl group, dibromophenyl group, teto And halogen-substituted hydrocarbon groups such as a lachlorophenyl group and a difluorophenyl group. A preferred example of R ⁴ is a methyl group.

  The polyorganosiloxane having a polar group of the present invention can be produced by a method known to those skilled in the art, and preferably has a viscosity at 25 ° C. of 1,000 to 100,000 mPa.s. of s. Viscosity 1000 mPa. If it is less than s, the dripping prevention effect of the composition is insufficient when applied to a vertical surface of a civil engineering building structure, and the viscosity is 100,000 mPa.s. When it is larger than s, the viscosity of the water absorption inhibitor composition is too high, so that the workability of coating is poor, and there is a disadvantage that it adheres to the surface of the substrate and becomes fouled.

Suitable examples of component (C) is a polyorganosiloxane having an aminoalkyl group as R ³ in the formula (2), R ³ having aminoalkyl groups are those represented by the general formula (3).
-R ⁵ -[(NR ⁶ ) -R ⁷ ] _t NR ⁸ R ⁹ (3)
In formula (3), R ⁵ and R ⁷ represent a divalent hydrocarbon group having 1 to 18 carbon atoms, and R ⁶ , R ⁸ and R ⁹ are a hydrogen atom, an unsubstituted or halogen-substituted carbon. The alkyl group of number 1-10 is represented, and t represents the integer of the value of 0-6.

Examples of the divalent C 1-18 hydrocarbon groups R ⁵ and R ⁷ are methylene group, ethylene group, n-propylene group, iso-propylene group, n-butylene group, iso-butylene group, t-butylene. Group, n-pentylene group, iso-pentylene group, hexylene group, heptylene group, octylene group, nonylene group and decylene group. Examples of the alkyl group represented by R ⁶ , R ⁸ and R ⁹ are alkyl groups having up to 10 carbon atoms among the alkyl groups described for R ¹ .

  Examples of polyorganosiloxanes having aminoalkyl groups include aminopropyl-modified polydimethylsiloxane, aminoethylaminopropyl-modified polydimethylsiloxane, and the like. These include alkoxy groups such as methoxy groups and ethoxy groups, May contain hydroxyl groups.

  The polyorganosiloxane having an aminoalkyl group of the present invention can be produced by methods known to those skilled in the art, and preferably has a viscosity at 25 ° C. of 1000 to 100,000 mPa.s. of s. Viscosity 1000 mPa. If it is less than s, the dripping prevention effect of the composition is insufficient when applied to a vertical surface of a civil engineering building structure, and the viscosity is 100,000 mPa.s. When it is larger than s, the viscosity of the water absorption inhibitor composition is too high, so that the workability of coating is poor, and there is a disadvantage that it adheres to the surface of the substrate and becomes fouled.

  The water absorption inhibitor composition of the present invention includes a fungicide, a bactericidal agent, an algicide, a microbicide, a fragrance, an anticorrosive, an ultraviolet absorber, a photocatalyst, an antifoaming agent and the like as long as the object of the present invention is not impaired. As a secondary agent.

  The water absorption inhibitor composition of the present invention can be produced by stirring and mixing at room temperature using a stirrer such as a homomixer, an ultradisperser, or a high-pressure homogenizer.

  The water absorption inhibitor composition of the present invention can be used by brush coating or spray coating on civil engineering and building structure base materials, especially inorganic porous building materials such as concrete, mortar, lightweight cellular concrete, brick and the like. it can. Moreover, as a drying method, it may be left to dry at room temperature, or may be sun drying or heat drying.

Although the application amount of the water absorption inhibitor composition of the present invention to these civil engineering structure base materials is usually 200 to 500 g / m ² , it is not particularly limited. Moreover, it is possible to apply the required amount with a single coating, but it can also be overcoated.

  The water absorption inhibitor composition of the present invention exhibits its effect particularly when used on a concrete surface of a civil engineering / building structure base that has already been installed. The civil engineering / building structure base material suitably used includes not only those cast on site, but also precast concrete products and members manufactured in factories and yards.

  The present invention will be specifically described based on examples, but the present invention is not limited to the following examples. Mortar specimens in examples, coating property evaluation method, coating sample preparation method, penetration depth evaluation method, residue removability evaluation method, substrate surface discoloration evaluation method after residue removal The evaluation method of the surface water repellency effect is as follows.

(Mortar specimen)
A JIS mortar (70 × 70 × 20 mm) according to JIS R5201 was used as a specimen.
(Evaluation method of coatability)
Apply the water absorption inhibitor composition to the vertical surface of the mortar specimen using a brush so as to be 360 g / m ² and observe whether the applied water absorption inhibitor composition drips up to 2 hours after application. did.

(How to create a coating sample)
The sample used for coating evaluation was applied to the vertical surface of the mortar specimen using a brush so that the water absorption inhibitor composition was 360 g / m ^2, and air-dried for 3 days after application (atmosphere: temperature 20). (° C., humidity 60%).
(Evaluation method of penetration depth)
The penetration depth of the coating sample was determined by dividing the length of the part (hydrophobic layer) that was split vertically from the surface on which the water absorption inhibitor composition was applied and sprayed with water on the split surface, and did not show a paint color due to water. Measurement was made and the average value of the five measurements was taken as the penetration depth.

(Evaluation method for residue removal)
The surface of the coated sample applied with the water absorption inhibitor was lightly rubbed with a brush 5 times, and the adhesion state of the residue on the substrate surface was observed.
(Method for evaluating discoloration of substrate surface after residue removal)
The coating surface of the coated sample was lightly rubbed with a brush 5 times to remove the residue on the surface of the base material, and then the color change of the coated surface was observed.
(Evaluation method of surface water-repellent effect on substrate surface after residue removal)
The coating surface of the coated sample was lightly rubbed with a brush 5 times to remove the residue on the substrate surface. The coated specimen was allowed to stand at an inclination angle of 45 °, and water was poured onto the surface where the water absorption inhibitor was coated with a dropper, and then the surface state was observed.

[Example 1]
The water absorption inhibitor composition of the present invention was prepared by stirring and mixing 94 parts by weight of hexyltriethoxysilane and 6 parts by weight of hydrophilic dry silica (trade name; WACKER HDK N20, manufactured by Wacker Chemie AG) at high speed using a homomixer. Obtained. The obtained water absorption inhibitor was a transparent liquid. Table 1 shows the composition, coating property evaluation, permeability evaluation, residue removal property evaluation, discoloration evaluation of the substrate surface after residue removal, and surface water repellency effect.

[Example 2]
The water absorption inhibitor composition of the present invention is obtained by stirring and mixing 94 parts by weight of hexyltriethoxysilane and 6 parts by weight of hydrophobic dry silica (trade name; WACKER HDK H30, Wacker Chemie AG) at high speed using a homomixer. Got. The obtained water absorption inhibitor was a translucent paste. Table 1 shows the composition, coating property evaluation, permeability evaluation, residue removal property evaluation, discoloration evaluation of the substrate surface after residue removal, and surface water repellency effect.

[Example 3]
93 parts by weight of hexyltriethoxysilane, 4 parts by weight of hydrophobic dry silica (trade name; WACKER HDK H30, manufactured by Wacker Chemie AG) and a viscosity at 25 ° C. of 10,000 mPa.s. s aminoethylaminopropyl-modified polydimethylsiloxane (I) was stirred and mixed at a high speed using a 3 parts by weight homomixer to obtain the water absorption inhibitor composition of the present invention. The obtained water absorption inhibitor was a translucent paste. Table 1 shows the composition, coating property evaluation, permeability evaluation, residue removal property evaluation, discoloration evaluation of the substrate surface after residue removal, and surface water repellency effect.

[Example 4]
The viscosity at 25 ° C. is 10,000 mPa.s. The viscosity is 1000 mPa.s instead of polydimethylsiloxane modified with aminoethylaminopropyl. A water absorption inhibitor composition of the present invention was obtained in the same manner as in Example 3 except that polydimethylsiloxane (II) modified with aminoethylaminopropyl of s was used. The obtained water absorption inhibitor was a translucent paste. Table 1 shows the composition, coating property evaluation, permeability evaluation, residue removal property evaluation, discoloration evaluation of the substrate surface after residue removal, and surface water repellency effect.

[Comparative Example 1]
100 parts by weight of hexyltriethoxysilane was stirred and mixed at high speed. The obtained water absorption inhibitor composition was a transparent liquid. Table 1 shows the composition, coating property evaluation, permeability evaluation, residue removal property evaluation, discoloration evaluation of the substrate surface after residue removal, and surface water repellency effect.

[Comparative Example 2]
94 parts by weight of hexyltriethoxysilane and 6 parts by weight of montmorillonite were stirred and mixed at high speed using a homomixer to obtain the water absorption inhibitor of the present invention. The obtained water absorption inhibitor composition was a grayish white liquid. Table 1 shows the composition, coating property evaluation, permeability evaluation, residue removal property evaluation, discoloration evaluation of the substrate surface after residue removal, and surface water repellency effect.

  Even if the water absorption inhibitor composition of the present invention is applied to the vertical surface of a civil engineering / structure base material, it does not drip and almost the entire amount penetrates into the base material to form a deep water absorption prevention layer. In addition, after drying, it has excellent surface water repellency, no trace of water droplets remains, the residue on the substrate surface can be easily removed, and there is little fouling and discoloration after coating. It is very useful.

Claims (6)

(A) 100 parts by weight of alkylalkoxysilane, and (B) 0.5 to 25 parts by weight of wet silica and / or dry silica , and (A) is represented by the general formula (1)
R ¹ _X Si (OR ² ) _4-X (1)
[Wherein, R ¹ is the same or different alkyl group having 1 to 20 carbon atoms, R ² is the same or different alkyl group having 1 to 6 carbon atoms or a hydrogen atom, and X is 1 or 2 The water absorption inhibitor composition for civil engineering and architecture represented by   (B) The water absorption inhibitor composition according to claim 1, wherein the silica is dry silica.   (B) The water absorption inhibitor composition according to claim 1 or 2, wherein the silica is hydrophobic dry silica. (C) The average composition of the siloxane unit is represented by the formula (2)
R ³ _a R ⁴ _b SiO _{(4-ab) / 2} (2)
[Wherein, R ³ is substituted with a group containing any one or more of O, N, S, or P atoms, and may be substituted with a halogen atom, and may be the same or different. These are monovalent hydrocarbon groups or hydroxyl groups. R ⁴ is a hydrocarbon group having 1 to 10 carbon atoms which may be the same or different. a is 0.001 to 1.0, b is 0.9 to 2.4, and a + b is 1.0 to 2.5. The water absorption inhibitor composition according to any one of claims 1 to 3, comprising 0.1 to 10 parts by weight of polyorganosiloxane represented by formula (A) based on 100 parts by weight of alkylalkoxysilane.   The water absorption inhibitor composition according to any one of claims 1 to 4, wherein (C) the polyorganosiloxane is a polyorganosiloxane having an aminoalkyl group.   The water absorption inhibitor composition according to any one of claims 1 to 5, which is used for a concrete structure for civil engineering and construction.