Emulsion-based penetrating water-repellent agent for unfaced concrete

Abstract

To provide an emulsion-based penetrating water-repellent agent which has excellent penetration into civil engineering and construction materials such as concrete, exhibits water repellency 24 hours after application, prevents the appearance of a wet color on the concrete surface, and maintains excellent surface water repellency and visual appearance even after long-term weather resistance tests.SOLUTION: An emulsion composition comprises a mixture of an alkylalkoxysilane siloxane emulsion and an aqueous silicone resin emulsion. It is preferable that the weight ratio of (a) the alkylalkoxysilane siloxane emulsion to (b) the aqueous silicone resin emulsion is from 50:50 to 99:1 wt.% in weight ratio.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a penetrative water absorption prevention material for civil engineering and building materials such as concrete and mortar.

Background Art

[0002] Conventionally, it has been widely known that alkylalkoxysilanes and their condensates are useful as penetrative water absorption prevention materials for civil engineering and building materials such as concrete. Since the penetrative water absorption prevention material penetrates into the interior of concrete or the like and forms a thick water-repellent layer on the surface layer, the water absorption prevention performance can be maintained for a long time, and various deterioration phenomena caused by the penetration of salts and moisture can be suppressed. Generally, as the penetrative water absorption prevention material, those obtained by diluting these alkylalkoxysilanes with various solvents are used. However, when these solvent-based water absorption prevention materials are applied to civil engineering and building materials, although they exhibit high water repellency, their use is restricted due to the volatility and flammability of the solvents. For example, when isopropyl alcohol is used as the solvent, the evaporation of the solvent is rapid, and the water absorption prevention material does not sufficiently penetrate into the base material, resulting in problems such as poor durability of the coated product. Conversely, when a solvent that is difficult to volatilize is used, there are problems such as the coated surface remaining in a wet state and being difficult to dry, and overcoating not being possible. In addition, generally, solvent-based types have problems such as being unable to be applied to a wet concrete surface.

[0003] In order to obtain a penetrative water absorption prevention material that does not use an organic solvent, the following methods can be considered. First, a method of applying alkylalkoxysilane as it is can be considered. However, alkylalkoxysilane itself has flammability, and although the danger is small, it is a dangerous substance under the Fire Service Act, and transporting and using it as it is cannot be said to be a fundamental environmental improvement. There is also a problem that it is difficult to apply to a wet surface.

[0004] Therefore, various methods of applying an alkylalkoxysilane as an aqueous dispersion have been studied. See, for example, Patent Document 1, Patent Document 2, and Patent Document 3.

[0005] In addition, a paste-like aqueous dispersion has been proposed to reduce sagging during painting. Specifically, in (Patent Document 4), an aqueous emulsion is produced from a component (A) selected from an alkylalkoxysilane (A1) and an alkoxy group-containing organopolysiloxane (A2), an organopolysiloxane (B) containing a siloxane unit having a group having basic nitrogen, an emulsifier (C), and water, and the remaining (A) and optionally (B) are mixed into the aqueous emulsion and stirred in a stator-rotor-stirring device at high speed until a creamy consistency is achieved, and a stable aqueous creamy water repellent is described. However, all of these have a problem that the surface water repellency completely disappears when a long-term weather resistance test is conducted.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0007] The present invention has been made in view of the above circumstances, and the emulsion-type penetrative water repellent for slump concrete of the present invention has little sag, exhibits good water repellency 24 hours after application, is less likely to become wet-colored, penetrates deeply into the concrete surface, and maintains good surface water repellency and aesthetics even after a long-term weather resistance test. The purpose is to provide an emulsion-type penetrative water repellent for slump concrete.

Effect of the Invention

[0008] The water repellent of the present invention is excellent in permeability to civil engineering and building materials such as concrete, exhibits good water repellency comparable to that of solvent-type penetrative water repellents, and can suppress the generation of dirt and mold on the applied surface over a long period of time. In particular, the emulsion-type penetrative water repellent of the present invention has little sag with respect to the slump concrete surface, exhibits good water repellency 24 hours after application, is less likely to become wet-colored, penetrates deeply into the concrete surface, and can maintain good surface water repellency and aesthetics even after a long-term weather resistance test.

Means for Solving the Problems

[0009] As a result of intensive studies to achieve the above object, the present inventors have found that the emulsion-type penetrative water repellent is a water repellent of an organosilicon compound emulsion, and by making it an emulsion composition in which an alkylalkoxysilane emulsion and an aqueous silicone resin emulsion are mixed, it is excellent in permeability to civil engineering and building materials such as concrete, exhibits water repellency 24 hours after application, the concrete surface is less likely to become wet-colored, and good surface water repellency and aesthetics are maintained even after a long-term weather resistance test, and thus the present invention has been completed.

[0010] That is, the present invention is an emulsion-type penetrative water repellent for slump concrete shown below. 〔1〕An emulsion-type permeable water absorption prevention material for cast-in-place concrete, which is an emulsion composition obtained by mixing an alkylalkoxysilane siloxane emulsion and an aqueous silicone resin emulsion. 〔2〕An emulsion-type permeable water absorption prevention material for cast-in-place concrete, which is an emulsion composition obtained by mixing (a) an alkylalkoxysilane siloxane emulsion and (b) an aqueous silicone resin emulsion, and the ratio of (a) to (b) is 50 to 99:50 to 1% by weight. 〔3〕The emulsion-type permeable water absorption prevention material for cast-in-place concrete according to 〔1〕 or 〔2〕, wherein (b) the aqueous silicone resin emulsion is an emulsion obtained by making aqueous a silicone resin having 100% siloxane bonds.

BEST MODE FOR CARRYING OUT THE INVENTION

[0011] Next, the mode for carrying out the present invention will be described. First, (a) the alkylalkoxy emulsion is not particularly limited, but an emulsion containing an alkylalkoxysilane and an alkylalkoxysiloxane is preferably used.

[0012] Examples of the alkylalkoxysilane include methyltrimethoxysilane, methyltriethoxysilane, methyltripropoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, propyltrimethoxysilane, propyltriethoxysilane, butyltrimethoxysilane, butyltriethoxysilane, pentyltrimethoxysilane, pentyltriethoxysilane, hexyltrimethoxysilane, hexyltriethoxysilane, heptyltrimethoxysilane, heptyltriethoxysilane, octyltrimethoxysilane, octyltriethoxysilane, nonyltrimethoxysilane, nonyltriethoxysilane, decyltrimethoxysilane, decyltriethoxysilane, undecyltrimethoxysilane, undecyltriethoxysilane, dodecyltrimethoxysilane, dodecyltriethoxysilane, tridecyltrimethoxysilane, tridecyltriethoxysilane, tetradecyltrimethoxysilane, tetradecyltriethoxysilane, pentadecyltrimethoxysilane, pentadecyltriethoxysilane, hexadecyltrimethoxysilane, hexadecyltriethoxysilane, heptadecyltrimethoxysilane, heptadecyltriethoxysilane, octadecyltrimethoxysilane, octadecyltriethoxysilane, etc. Among them, hexyltrimethoxysilane, hexyltriethoxysilane, octyltrimethoxysilane, octyltriethoxysilane, or decyltrimethoxysilane is preferably used.

[0013] The alkylalkoxysiloxane is usually obtained by subjecting one kind of alkylalkoxysilane alone or a mixture of two or more kinds thereof to a hydrolysis and polycondensation reaction in water, and is a mixture of various alkylalkoxysiloxanes. As such an alkylalkoxysiloxane, those generally commercially available under the trade names such as "TSR165" of Momentive Performance Materials Japan LLC and "SILRES MSE100" of Asahi Kasei Wacker Silicone Co., Ltd. can be used.

[0014] When the weight ratio of the alkylalkoxysiloxane exceeds 0.4, the permeability of the resulting water repellent material to the substrate may deteriorate. In addition, when the total amount of the alkylalkoxysilane and the alkylalkoxysiloxane exceeds 80% by weight, the generated emulsion may become unstable and phase separation may occur. The organosilicon compound emulsion is obtained by mixing water and an emulsifier with the above alkylalkoxysilane and alkylalkoxysiloxane and stirring and emulsifying them at high speed using a stirring device such as a homomixer. As the emulsifier used here, mainly nonionic emulsifiers are used, but a small amount of anionic emulsifiers and cationic emulsifiers can be used if necessary. As the nonionic emulsifier, those with an HLB of about 9 to 16 are preferable. If the HLB is 9 or less or 16 or more, the long-term stability of the emulsion tends to decrease.

[0015] Examples of the nonionic emulsifier include polyoxyethylene alkyl ether, polyoxyethylene alkyl allyl ether, oxyethylene oxypropylene block copolymer, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sorbitol fatty acid ester, glycerin fatty acid ester, polyoxyethylene fatty acid ester, polyoxyethylene alkylamine, and the like.

[0016] Examples of the anionic emulsifier include fatty acid salts, alkyl sulfate esters, alkylbenzene sulfonates, alkylnaphthalene sulfonates, alkyl sulfosuccinates, alkyl diphenyl ether disulfonates, alkyl phosphates, polyoxyethylene alkyl or alkyl allyl sulfate esters, naphthalene sulfonic acid formalin condensates, polyoxyethylene alkyl phosphate esters, and the like.

[0017] Examples of the cationic emulsifier include alkylamine salts, quaternary ammonium salts, alkyl betaines, amine oxides, and the like.

[0018] The emulsifiers can be optionally mixed as needed. However, in order not to reduce the water repellency after coating, the total amount of emulsifiers is preferably 0.1% by weight to 10% by weight based on the alkylalkoxysilane component. If the amount of emulsifier is too small, emulsification may become difficult. If the amount of emulsifier is too large, water repellency may not be exhibited.

[0019] Furthermore, additives such as pH adjusters, preservatives, antifungal agents, antibacterial agents, thickeners, defoamers, oil-soluble dyes, and water-based colorants can be added to the alkylalkoxysilane siloxane emulsion as needed to the extent that they do not affect the dispersibility and the performance as a water absorption preventing material.

[0020] As the pH adjuster, various alkali compounds, pH buffers, etc. may be used. Examples of the alkali compounds include metal hydroxides such as sodium hydroxide and calcium hydroxide, and organic amines such as propylamine, isoamylamine, hexylamine, laurylamine, and stearylamine.

[0021] The preservative prevents the emulsion from spoiling, and the antifungal agent and antibacterial agent prevent the growth of mold and bacteria on the coated surface. These can be used without particular limitation as long as they do not impair the stability of the emulsion. For example, haloallyl sulfone-based, iodopropargyl-based, N-haloalkylthio-based, benzimidazole-based, nitrile-based, pyridine-based, 8-hydroxyquinoline-based, benzothiazole-based, isothiazoline-based, organotin-based, phenol-based, quaternary ammonium salt-based, triazine-based, thiadiazine-based, anilide-based, adamantane-based, dithiocarbamate-based, inorganic salt-based, brominated indanone-based compounds, etc. can be mentioned. Among these, those that are easily soluble in water can be used as preservatives, and those that are poorly soluble in water can be used as antifungal agents or antibacterial agents, either alone or as a mixture of two or more.

[0022] The thickener increases the viscosity to further improve the separation stability of the emulsion, and can be used without particular limitation as long as it does not affect the stability of the silane and the coating surface. For example, water-soluble polymers such as modified polyacrylic acid, modified polyacrylate, polyacrylic acid, polyacrylic acid alkali salt, alginate, alginate ester, polyvinyl alcohol, polyether, casein, mannan, starch, chitosan, carboxymethyl cellulose, and methoxymethyl cellulose can be mentioned, and they may be used alone or as a mixture of two or more.

[0023] The present invention has the greatest feature in that an aqueous silicone resin emulsion uses a water repellent of an emulsion obtained by aqueousizing a silicone resin having 100% siloxane bonds.

[0024] Generally, a water repellent is defined as a substance that forms a hydrophobic film on the surface without changing the internal structure of the substrate and can prevent water permeation. It is water-insoluble and is often in a form dissolved in an organic solvent or emulsified and dispersed in water using an emulsifier. When these water repellents are added to an organosilicon compound emulsion, the water repellent of the organic solvent dissolution type affects the stability of the emulsion. In addition, as the emulsified / dispersed type water repellent, a silicone oligomer, an emulsion of a fluororesin mainly composed of a copolymer or mixture of olefin or acrylic and a fluorine compound, or an emulsion of a compound having a fluoroalkyl group is used, and it does not affect the stability of the organosilicon compound emulsion. However, since the silicone oligomer is not a polymer but has a relatively medium molecular weight, and the initial water repellency of an emulsion of a compound having a fluoroalkyl group is good, the surface water repellency decreases after a long-term weather resistance test.

[0025] On the other hand, the water repellent of the aqueous silicone resin emulsion used in the present invention, which is an emulsion obtained by making an aqueous solution of a silicone resin with 100% siloxane bonds, is an aqueous silicone emulsion having 100% siloxane bonds and has very long-term weather resistance because of its high molecular weight, and has the characteristics of surface water repellency and non-wetting color. Examples of such aqueous silicone emulsions include "Coatsil DRI" manufactured by Momentive Performance Materials Japan G.K., "SILRES BS45" manufactured by Asahi Kasei Wacker Chemical Co., Ltd., "M Coat 56" manufactured by Shin-Etsu Chemical Co., Ltd., and the like. In addition, when the aqueous silicone resin emulsion is applied to a substrate alone, it does not become wet-colored and maintains water repellency even after a long-term weather resistance test, but does not penetrate deeply into the concrete.

[0026] In the present invention, it has been found that an emulsion-type penetrating water absorption preventive material for shotcrete that maintains the penetration depth and long-term water repellency can be obtained by mixing an aqueous silicone resin emulsion having 100% siloxane bonds that secures the penetration depth of the organosilicon compound emulsion into the concrete and maintains the water repellency inside the concrete while retaining the surface water repellency after a long-term weather resistance test. An emulsion composition obtained by mixing (a) an alkylalkoxysilane siloxane emulsion and (b) an aqueous silicone resin emulsion, and the ratio of (a) to (b) is preferably 50 to 99:50 to 1% by weight. When (b) is 50% or more, the penetration depth of (a) the alkylalkoxysilane-based emulsion into the concrete decreases. On the other hand, when (b) is 1% or less, the surface water repellency in a long-term weather resistance test decreases. More preferably, it is about 5% to 20%. Also, it is better that the aqueous silicone resin emulsion does not contain an organic solvent. This is because when an organic solvent is contained, the stability of (a) the alkylalkoxysilane siloxane emulsion may be impaired when mixed.

[0027] To apply the water repellent material of the present invention to civil engineering and building materials, rollers, brushes, sprays, etc. are used. As the drying method, it may be left to dry at room temperature, or it may be dried in the sun or by heating.

[0028] Examples of civil engineering and building materials include porous civil engineering and building materials. More specifically, there are cast-in-place concrete, lightweight concrete, precast concrete, lightweight foamed concrete (ALC), mortar, joint mortar, asbestos cement board, pulp cement board, wood wool cement board, cement-based extruded board, glass fiber-reinforced cement board (GRC), carbon fiber-reinforced cement board, calcium silicate board, gypsum board, hard board, plaster, gypsum plaster, dolomite plaster, blocks, bricks, tiles, roof tiles, natural stone, artificial stone, materials mainly composed of inorganic materials such as glass wool, rock wool, ceramic fiber, etc., and materials mainly composed of organic materials such as wood, plywood, particle board, etc.

[0029] Although the water repellent material of the present invention is water-based, it exhibits high surface water repellency equivalent to that of solvent-based water repellent materials, and can prevent rainwater leakage due to strong wind and rain, material deterioration due to acid rain, seepage of dirt, and generation of mold over a long period of time. When the water repellent material of the present invention is applied to a base material, various problems caused by water, such as salt damage by seawater, frost damage in cold regions, and efflorescence due to elution of salts in the base material, can be solved by the water repellent layer formed inside the base material.

Examples

[0030] Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to these examples at all.

[0031] 〔Example 1〕 135 g of n-octyltriethoxysilane and 7 g of a mixture of polyoxyethylene lauryl ether (Emulgen 108 manufactured by Kao Corporation, HLB = 12.1 and Emulgen 147 manufactured by Kao Corporation, HLB = 16.3, adjusted to HLB = 14.2) and 148 g of ion-exchanged water were charged and emulsified with a homomixer to obtain an O / W emulsion. To this emulsion, 680 g of n-octyltriethoxysilane was gradually added while stirring with a homomixer to perform emulsification. Thereafter, it was charged into a homodisper and kneaded at 2500 rpm for 1 hour to obtain a highly viscous emulsion. Then, 194 g of ion-exchanged water and 0.4 g of a preservative (Proxel BDN manufactured by Arch Chemicals) were added to obtain a milky white alkylalkoxysilane emulsion containing 70% by mass of n-octyltriethoxysilane as an active ingredient. Furthermore, 100 g of M Coat 56 manufactured by Shin-Etsu Chemical Co., Ltd. was added as an aqueous silicone resin emulsion to obtain a milky white water penetration and absorption preventing material. Then, 200 g / m of the milky white water penetration and absorption preventing material obtained above was applied to a mortar plate. 2 Coated. [Example 2] 100 g of n-octyltriethoxysilane and 13 g of polyoxyethylene lauryl ether (Emulgen 120 manufactured by Kao Corporation, HLB = 15.3) and 80 g of ion-exchanged water were charged and emulsified with a homomixer to obtain an O / W emulsion. To this emulsion, 600 g of n-octyltriethoxysilane was gradually added while stirring with a homomixer to perform emulsification. Thereafter, it was charged into a homodisper and kneaded at 2500 rpm for 2 hours to obtain a highly viscous emulsion. Then, 374 g of ion-exchanged water and 0.4 g of a preservative (Proxel BDN manufactured by Arch Chemicals) were added to obtain a milky white alkylalkoxysilane emulsion containing 60% by mass of n-octyltriethoxysilane as an active ingredient. Furthermore, 60 g of "Coatsil DRI" manufactured by Momentive was added as an aqueous silicone resin emulsion to obtain a milky white permeable water repellent material. Then, 200 g / m of the milky white permeable water repellent material obtained above was applied to a mortar plate. 2 〔Comparative Example 1〕 A permeable water repellent material was obtained in the same manner as in Example 1, except that the addition of 100 g of the last aqueous silicone resin emulsion "M Coat 56" was changed to 1 g. Then, 200 g / m of the obtained permeable water repellent material was applied to a mortar plate. 2 〔Comparative Example 2〕 A permeable water repellent material was obtained in the same manner as in Example 1, except that the addition of 100 g of the last aqueous silicone resin emulsion "M Coat 56" was changed to 700 g. Then, 200 g / m of the obtained permeable water repellent material was applied to a mortar plate. 2 〔Comparative Example 3〕 A permeable water repellent material was obtained in the same manner as in Example 2, except that 13 g of polyoxyethylene lauryl ether (Emulgen 120 manufactured by Kao Corporation, HLB = 15.3) was changed to 130 g. Then, 200 g / m of the obtained permeable water repellent material was applied to a mortar plate. 2 〔Comparative Example 4〕 The same operation as in Example 2 was performed except that 13 g of polyoxyethylene lauryl ether (Emulgen 120 manufactured by Kao Corporation, HLB = 15.3) was changed to 0.6 g, but the emulsion was unstable and no emulsion could be obtained. 〔Comparative Example 5〕 The same operation as in Example 2 was performed except that 60 g of an aqueous silicone resin emulsion containing a solvent, "SILRES MP-50E" manufactured by Asahi Kasei Wacker Chemical Corporation, was used instead of the aqueous silicone resin emulsion "Coatsil DRI" manufactured by Momentive added last, but the emulsion became unstable over time and separated. 〔Comparative Example 6〕 ​​​​In Example 1, the aqueous silicone resin emulsion Shin-Etsu Chemical Co., Ltd.'s M-Coat 56 was applied to the mortar plate alone without an alkyl alkoxy emulsion. [Comparative Example 7] In Example 2, 100 g of n-octyltriethoxysilane, 13 g of polyoxyethylene lauryl ether (Emulgen 120 manufactured by Kao Corporation, HLB = 15.3), and 80 g of ion-exchanged water were charged, and emulsification was carried out using a homomixer to obtain an O / W emulsion. To this emulsion, a mixture of 410 g of n-octyltriethoxysilane and 74 g of silicone oligomer trade name "SIRES MSE100" of Asahi Kasei Wacker Silicone Co., Ltd. was gradually added while emulsifying with a homomixer. Thereafter, it was charged into a homodisper and kneaded at 2500 rpm for 2 hours to obtain a high-viscosity emulsion. Furthermore, thereafter, 490 g of ion-exchanged water and 0.4 g of a preservative (Proxel BDN manufactured by Arch Chemicals) were added to obtain a milky white alkyl alkoxysilane emulsion containing 50% by mass of n-octyltriethoxysilane as an active ingredient. And the obtained water absorption preventive was applied to the mortar plate at 200 g / m 2 coated. [Comparative Example 8] In Example 2, a water-repellent agent of a fluorine-based aqueous emulsion (trade name "Asahi Guard AG-740" of Asahi Glass Co., Ltd.) was changed to 30 g instead of the aqueous silicone resin emulsion "Coatsil DRI" manufactured by Momentive added last, and a permeable water absorption preventive was obtained by the same operation. And the obtained permeable water absorption preventive was applied to the mortar plate at 200 g / m 2 coated.

[0032] Using the water absorption preventives obtained in Examples 1 to 2 and Comparative Examples 1 to 8, various properties were evaluated by the following methods.

[0033] [Evaluation Method] (1) Storage stability The water repellent materials obtained in the examples and comparative examples were placed in a 150 cc glass container at 100 cc, left standing at 40°C, and the state of phase separation of the emulsion after one month was visually observed.

[0034] (2) Coating appearance, water repellency (contact angle), penetration depth Mortar (70 mm × 150 mm × 10 mm) conforming to JIS R-5201 was used as a specimen, and the water repellent materials obtained in the examples and comparative examples were applied to the entire surface at a rate of 200 g / m 2 . Note that a specimen with nothing applied was used as a control. The obtained specimens were cured for 24 hours in a thermo-hygrostat at a temperature of 20°C and a relative humidity of 65 RH% to measure water repellency (contact angle), and further cured for 14 days to observe the coated surface state. The water repellency was evaluated by measuring the contact angle before the accelerated weathering test. Next, an accelerated weathering test was carried out using a xenon lamp type accelerated weathering tester (Suga Test Instruments Co., Ltd.) at a black panel temperature of 63°C and a humidity of 50%. After 1000 hours had elapsed, the water repellency (contact angle) of the specimens was measured. The penetration depth was measured by cutting the mortar plate and observing the cross section.

[0035] The penetration depth was measured by cutting the mortar plate after the accelerated weathering test, applying methylene blue to the cross section, and measuring the penetration depth. ◎: Penetration depth of 4 mm or more 〇: Penetration depth of 3 mm to less than 4 mm △: Penetration depth of 2 mm to less than 3 mm ×: Penetration depth of 2 mm or less

[0036] Water repellency (contact angle): After applying the water repellent material, after 24 hours, 14 days later, and after the accelerated weathering test, 2 μg water droplets were placed on the specimens, and the contact angle was measured using an automatic contact angle measuring device (Kyowa Interface Science Co., Ltd.). The evaluation criteria were as follows. ◎: Contact angle of water droplets of 110° or more ○: Contact angle of water droplets of 100 to less than 110° △: Contact angle of water droplets of 100° or less ×: Does not form water droplets and immediately absorbs water The evaluation results are shown in Table 1.

Table 1

[0037] From the results in Table 1, the water absorption prevention materials obtained in each example are stable against phase separation of the emulsion and do not undergo phase separation for 1 month. In addition, when applying the water absorption prevention materials obtained in each example, there is little dripping, and the applied specimens have a penetration depth of 4 mm or more, a fast water repellency development rate, and very good water repellency, and their water repellency and water absorption prevention properties can also be maintained over a long period. Although the details of this mechanism are unknown, it is presumed that while the 100% silicone resin aqueous emulsion penetrates the concrete with the organosilicon compound emulsion during the film-forming process, the aqueous silicone resin emulsion forms a film. That is, it is considered that the organosilicon compound emulsion forms a water absorption prevention layer and shares the function of maintaining long-term surface water repellency with the 100% silicone resin emulsion. In the examples using the silicone oligomer of Comparative Example 7 and the fluorine-based aqueous emulsion water repellent of Comparative Example 8, the development of water repellency after the accelerated weathering test is not sufficient. This is presumably because the silicone oligomer and the fluorine-based aqueous emulsion water repellent have relatively medium to low molecular weights, so sufficient water repellency could not be obtained.

[0038] Despite being an aqueous water absorption prevention material, the water absorption prevention material of the present invention imparts extremely excellent water repellency to the surface of civil engineering and construction base materials such as cement products, suppresses the generation of dirt and mold, and at the same time penetrates deep into the base material to form a hydrophobic (water repellent) layer, thereby imparting excellent water absorption prevention properties to the base material and suppressing deterioration phenomena over a long period. Thus, the water absorption prevention material of the present invention is extremely useful in the civil engineering and construction fields. Particularly, in fields such as shotcrete, it is most suitable for applications where the shot surface does not turn wet-colored and maintains good water repellency even after a long-term weathering test.

Claims

1. An emulsion-type permeable water absorption preventive material for self-leveling concrete, which is an emulsion composition obtained by mixing an alkylalkoxysilane siloxane emulsion and an aqueous silicone resin emulsion.

2. An emulsion-type permeable water absorption preventive material for self-leveling concrete, which is an emulsion composition obtained by mixing (a) an alkylalkoxysilane siloxane emulsion and (b) an aqueous silicone resin emulsion, and the ratio of (a) to (b) is 50 to 99:50 to 1% by weight.

3. The emulsion-type permeable water absorption preventive material for self-leveling concrete according to claim 1 or 2, wherein (b) the aqueous silicone resin emulsion is an emulsion obtained by aqueousizing a silicone resin having 100% siloxane bonds.

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