JPH0419187B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a surface reinforcement finishing method for cementitious materials made of hardened materials such as cement, mortar, and concrete. Traditionally, cured products such as cement, mortar, and concrete have been widely used as cement-based materials in architecture, civil engineering, and other fields. Deterioration progresses, and deterioration, especially on the walls of structures, is causing serious problems.
It is known that such deterioration of cementitious materials is due to carbonization by outside air and the gradual development of micropores existing on the surface into cracks. Therefore, as methods for strengthening and finishing the surface of cementitious materials, methods have been proposed in which the surface layer of cementitious materials is chemically modified or coated with finishing materials, but no satisfactory method has yet been found. do not have. For example, JP-A-55-78764 discloses a method for repairing reinforced concrete by impregnating the surface of deteriorated concrete with an aqueous solution of a silicate compound, and then coating the impregnated surface with cement paste. However, this coating layer made of cement paste does not have elasticity or crack resistance, and does not have sufficient water resistance, water permeability resistance, or air permeability, so if it is used for a long time after repair, it may be difficult to stop the progress of deterioration. Can not. On the other hand, organic finishing materials based on synthetic resin binders, which are usually used as coating materials, are currently available in rubber-like elastomer finishing materials,
It was developed under the name of wall waterproofing material, and the coating film formed using this material has some flexibility, elasticity, and crack resistance, but it is inferior in water resistance, dry hardening properties, and long-term weather resistance. As a matter of course, it has drawbacks such as not being nonflammable at all, so it cannot be said to be a perfect method for surface reinforcement finishing of cementitious materials. The present inventors impregnated the surface of a cement material with a treatment liquid containing alkali silicate as a main component, dried it, and applied an inorganic finishing material with rubber-like high elasticity or a nonflammable finishing material to the surface. The cementitious material obtained by applying and curing the elastic finishing material has a thick modified surface layer obtained by impregnating and liquefying the treatment liquid, and the strength and alkalinity of the deteriorated surface layer are restored. Therefore, deterioration of the modified surface layer is significantly prevented, and the surface of this modified surface layer has the property of increasing the adhesive strength with the finishing material, so by applying the finishing material to this surface, the surface of the modified surface layer can be formed. Even if the coating film is exposed to wind and rain and there are large temperature changes, it will not crack or peel, and it is even better because it has excellent water resistance, water permeability, and air permeability, and is nonflammable. The present invention was completed by discovering that the surface of cement-based materials can be strengthened. The purpose of the present invention is to provide a surface layer with high strength and improved water resistance, water permeability, weather resistance, etc., from the surface of the cement material to the deep inside, in order to strengthen and finish the surface of the cement material. After forming, an inorganic coating film having rubber-like high elasticity with improved crack resistance, peeling resistance, water resistance, water permeability resistance, and air permeability resistance, and an elastic coating film that is also nonflammable is formed. In particular, it is an object of the present invention to provide a method for enhancing the surface of cementitious materials. The cementitious material to which the method of the present invention is applied uses ordinary cement such as cement, mortar, concrete, ALC, slate board, etc. as a raw material, and the necessary components are blended with this and then hardened by a hardening reaction. The method of the present invention can be applied to all types of cement-based materials, including those that have just been poured, those that have already experienced surface deterioration due to use after placement, and those that have dried out during placement. It is preferable that the material is sufficiently dry before being impregnated with the treatment liquid. The allyl silicate used in the present invention includes Li, Na,
It is a silicate of K, Cs, NH ₄ etc., and when the above alkali metal atom or NH ₄ is represented by M, SiO ₂ /
_M2O molar ratio of 1 to 4 sodium water glass,
Potassium water glass, lithium water glass, cesium silicate, ammonium silicate, etc., are easily available as commercial products. In the present invention, the alkali silicate can be used as an aqueous solution having an alkali silicate content of 1 to 30% by weight by diluting it with water, or as a mixture of two or more thereof. Preferred alkali silicate is SiO ₂ /
Lithium silicate with an M ₂ O molar ratio of 2.2 to 4.0 may be mentioned. When lithium silicate is used, the water resistance of the cement material surface obtained by applying the method of the present invention is significantly improved, and furthermore, efflorescence does not occur.
As a particularly preferred aqueous lithium silicate solution, a transparent one such as that described in Japanese Patent Publication No. 54-20480 is used. The treatment liquid used in the present invention may contain additives in addition to the alkali silicate described above, as long as the object of the present invention is achieved. In some cases, a more preferable treatment liquid can be obtained by containing other additives. That is, the treatment liquid containing 100 parts by weight of the aqueous alkali silicate solution and 0.01 to 5 parts by weight of naphthalene sulfonic acid sodium aldehyde condensate salt as an additive further increases the thickness of the modified surface layer by improving the impregnating property. can be done. Similarly, a treatment solution containing 100 parts by weight of the aqueous alkali silicate solution and 0.01 to 5 parts by weight of an aliphatic monohydric lower alcohol having a linear or branched chain such as methanol, ethanol, n-propanol, isopropanol, butanol, etc. Impregnating properties are improved. On the other hand, according to the treatment liquid containing the above-mentioned alkali silicate in an amount of 1 to 30% by weight and a polymer aqueous emulsion in an amount of 1 to 30% by weight as solid content, the thickness of the modified surface layer did not decrease and The water resistance of the surface is significantly increased, the elution of alkaline components from the surface layer is extremely reduced, and deterioration of the surface of the modified surface layer is significantly prevented. Furthermore, the surface of this modified surface layer can increase the adhesive strength with the top coating material, resulting in further improvement. The aqueous polymer emulsion used in combination with the alkali silicate is not particularly limited as long as it can be stably mixed with the aqueous alkali silicate solution, but usually preferred examples include acrylic resin emulsion, vinyl acetate resin, etc. Examples include emulsion, SBR latex, NBR latex, natural rubber latex, etc. Note that these additives may be mixed and contained as long as the purpose of the present invention is achieved. In the present invention, the surface of the cement material is first impregnated with the treatment liquid, and then the cement material after the treatment is dried. Examples of the impregnation method include coating with a brush, spray, etc., and dipping. Any conventional method may be used, such as a method using pressure, pressure, or suction. By drying after the impregnation, the alkali silicate causes a hardening reaction in the surface layer of the cement material, forming a modified surface layer with improved strength and alkalinity. The method of the present invention is further characterized in that a coating material is applied onto the modified surface and cured. The above coating materials include
The special components are cement, fine aggregate, film elongation of 1500% or more, and glass transition temperature of -10.
Contains an emulsion of an acrylic polymer at a temperature of 0.degree. As the above-mentioned cement used in the method of the present invention, various cements such as ordinary Portland cement, white Portland cement, blast furnace cement, silica cement, and fly ash cement can be used, and as the fine aggregate, sand, silica sand, and impregnated sand can be used. , natural and artificial lightweight aggregates, etc. can be used. The alkaline polymer in the alkaline polymer emulsion used in the above coating material must have a film elongation of 1500% or more and a glass transition temperature of -10°C or less as determined in accordance with JISK-6301. If the amount is outside this range, the desired rubber-like high elasticity cannot be obtained and the cracking resistance of the coating film becomes poor, so it is not preferable. Examples of the acrylic polymers include 2-ethylexyl acrylate, butyl acrylate,
Examples include polymers or copolymers of ethyl acrylate, isopropyl acrylate, lauryl methacrylate, hexyl methacrylate, styrene, and acrylonitrile, which impart elasticity to the coating film formed by the coating material according to the present invention, It is not limited to the polymers exemplified above. Acrylic polymer emulsions are available on the market, such as Polytron Z-220 (trade name: manufactured by Asahi Kasei Corporation), Yodozol AD-21, and Acronal S-400 (trade name: manufactured by Kanebo NSC).
"Product name: Manufactured by Basuf Corporation" etc. In addition to the above-mentioned cement, fine aggregate, and acrylic polymer, the coating materials used in the present invention include pigments as necessary, mica to help prevent cracks, calcium stearate to help waterproof, other dispersants, and nonflammability. Fillers such as borax, additives, water, etc. may be included. The coating material used in the present invention also has a content ratio of fine aggregate to 100 parts by weight of cement.
50 to 300 parts by weight, and the solid content of the acrylic polymer emulsion is 5 to 100 parts by weight. If the content of fine aggregate is less than 50 parts by weight, it is not preferable because the elongation rate of the coating material becomes low and dry cracks are more likely to occur in the initial stage of construction. On the other hand, if it exceeds 300 parts by weight, it is not preferable because not only the strength and adhesion of the coating film decreases, but also the water resistance and surface drying properties deteriorate. In addition, if the solid content of the acrylic polymer emulsion is less than 25 parts by weight, the resulting coating film will not have high initial rubber-like elasticity, and if it exceeds 100 parts by weight, the cohesive strength It is not preferable because the coating material becomes sticky and the stain resistance decreases. The content of the coating material used in the present invention can be varied within the above range depending on the purpose. For example, when nonflammability is desired, the fine aggregate is preferably 50 to 200 parts by weight, and the solid content of the acrylic polymer emulsion is preferably about 5 to 15 parts by weight per 100 parts by weight of cement. When a highly elastic coating film is intended, it is preferable to use 50 to 300 parts by weight of fine aggregate and 25 to 100 parts by weight of acrylic polymer emulsion as a solid content per 100 parts by weight of cement. The coating material used in the present invention includes the above cement,
fine aggregate and acrylic polymer emulsion,
Alternatively, it can be easily adjusted by adding optional ingredients and water as necessary and mixing thoroughly. In the method of the present invention, the surface of the cement material is impregnated with the treatment liquid, dried, and then the coating material is applied to the surface, and then the hydraulic reaction of the cement contained therein is carried out. A finishing method that forms a coating film on the surface of a cementitious material by drying and curing an emulsion. The coating material may be applied by conventional methods such as brush application, roll application, etc. The method of the present invention can be easily carried out, and the cement-based materials obtained by the method of the present invention are significantly prevented from deterioration due to carbonation or the development of cracks, and are water resistant and resistant. It also has excellent water permeability and weather resistance. Therefore, it is extremely useful for preventing the deterioration of cementitious materials before deterioration, and for repairing and restoring deteriorated cementitious materials. The present invention will be described in more detail below by giving Examples together with Comparative Examples, but the technical scope of the present invention is not limited thereto. Example 1 A sodium silicate solution with a SiO ₂ concentration of 10% and a molar ratio (SiO ₂ /Na ₂ O) of 3.0 was applied to each of the test specimens No. 1 to No. 5 shown in Table 1 with a brush until the suction stopped. After application, it was dried. Separately, a coating material was prepared by stirring and mixing 100.2 parts of a homogeneous mixture of the formulations shown in Table 2 and 41.03 parts of a thorough mixture of the acrylic polymer emulsion formulations shown in Table 3, and impregnated with the above sodium silicate. Test pieces for each test were prepared by coating the sample with a thickness of 1 mm after drying, and each test was conducted. The test results are shown in Table 9.

[Table] Table 2 Portland cement 46 parts Tancal G-100 ^* 17〃 Tancal G-50 ^* 30〃 Borax sand 4〃 Mica 1〃 Calcium stearate 0.2 parts Titanium oxide 2 parts Total 100.2 parts * Manufactured by Hayashi Kasei Co., Ltd.: Calcium carbonate Product name Table 3 Acronal S-400 ^* 12.5 parts Methyl cellulose 0.2〃 Calcium gluconate 1.0〃 Nonionic surfactant 1.0 parts Slamony B ^** 0.03 parts Nobuco NXZ ^*** 0.3 parts Water 26.0 parts Total 41.03 parts * Manufactured by Basf Corporation: Solid Trade name of 57% acrylic polymer emulsion, the glass transition temperature of the polymer is -20℃, and the elongation is more than 2700%. **Manufactured by Takeda Pharmaceutical Co., Ltd.: Brand name of preservative ***Manufactured by San Nobuco Co., Ltd.: Brand name of antifoaming agent Examples 2 to 6 The sodium silicate solution in Example 1 was changed to the alkaline silicate solution shown below. The test was conducted in exactly the same manner as in Example 1. The results are shown in Table 9. Example 2 Potassium silicate SiO ₂ concentration 10% SiO ₂ /M ₂ O molar ratio
3.0 Example 3 Lithium silicate SiO ₂ concentration 10% SiO ₂ /M ₂ O molar ratio 3.5 Example 4 Lithium silicate SiO ₂ concentration 10% SiO ₂ /M ₂ O molar ratio 3.5 Naphthalenesulfonic acid soda formalin condensate
0.1% Example 5 Lithium silicate SiO ₂ concentration 10% SiO ₂ /M ₂ O molar ratio
3.5 Example of adding ethyl alcohol to 0.5% 6 Lithium silicate SiO ₂ concentration 10% SiO ₂ /M ₂ O molar ratio
3.5 5% as solid content of acrylic-styrene synthetic resin emulsion Example 7 As in Example 3, SiO ₂ concentration of 10% was added to each specimen.
After applying a lithium silicate aqueous solution with a molar ratio of 3.0 and drying,
A test was conducted in the same manner on a coating material obtained by uniformly mixing each of the formulations shown in Tables 4 and 5 and applied to a thickness of 1 mm. The results are shown in Table 9. Table 4 White Portland cement 46 parts Tancal G-100 17 parts Tancal G-50 30 parts Borax sand 4 parts Mica 1 part Calcium stearate 0.2 parts Titanium oxide 2 parts Total 100.2 parts Table 5 Acronal S-400 80 parts Methyl cellulose 0.3 parts Gluconic acid Calcium 1.0 parts Nonionic activator 1.0 parts Preservative 0.03 parts Nobuco NXZ 0.3 parts Total 82.63 parts Comparative Example 1 Instead of the sodium silicate solution of Example 1, 100% of an ethylene-vinyl acetate-based synthetic resin emulsion solution (solid content 25%) was used. The process was carried out in exactly the same manner as in Example 1, except that ~120 g/m ² was applied. Table 9 shows the results of these comparative examples. Comparative Example 2 A test was conducted in exactly the same manner as in Example 1, except that a mixture of the formulations shown in Table 6 was used as the coating material. Table 6 Movinyl DM-60 ^* 25 parts Tancal G-100 66 parts Mica 6.5 parts Methyl cellulose 0.15 parts Primal 850 ^** 0.7 parts Ethylene glycol 1.0 parts Nobuko NXZ 0.4 parts Water 1.5 parts Total 101.25 parts *Manufactured by Hoechst Synthetic Co., Ltd.: Solid content The product name is 50% acrylic polymer emulsion, the glass transition temperature of the polymer is 10℃, and the film elongation is about 550%. **Manufactured by Nippon Acrylic Kasei Co., Ltd.: Dispersant trade name Comparative Example 3 The formulations shown in the table below were mixed and manufactured in the same manner as in Example 1, and separately, the polymer emulsion formulations shown in Table 8 below were mixed and manufactured in the same manner as in Example 1. I made it. Table 7 Portland cement 40 parts Tancal G-50 45 parts Mica 5.5 parts Plaster 4.5 parts Titanium oxide 5.0 parts Calcium stearate 0.2 parts Total 100.2 parts Table 8 Sumikaflex 400 ^* 11.2 parts Mercellulose 0.2 parts Calcium gluconate 1.0 parts Nonionic surfactant 1.0 Part Ramony B 0.03 parts Nobuco NXZ 0.3 parts Water 26.3 parts Total 40.03 parts *Manufactured by Sumitomo Chemical Co., Ltd.: Trade name of vinyl acetate emulsion with solid content of 50%. The glass transition temperature of this resin is approximately 0°C, and the film elongation rate is It is 520%. 100.2 parts of the formulation in Table 7 above and 40.03 parts of the formulation in Table 8
A test was conducted in exactly the same manner as in Example 1, except that a mixture of these parts was used as a coating material. The results are shown in Table 9.

[Table] Test method a A Δ-shaped reinforcing bar is placed in the center of the specimen and split.
After removing dust etc. from the cracked surface, spray a solution containing 1% phenolphthalein in an ethanol/water ratio of 9:1 and measure the depth from the mortar surface to the colored area. b According to JISA-6910. c Same as above d According to JISA-1321. 1 in a room with a temperature of 30°C, humidity of 60%, and a _CO2 concentration of 5%.
After leaving it for several months, it was split open, sprayed with phenolphthalein solution, and the depth measured from the surface to the colored area.

Claims (1)

[Claims] 1 Impregnating the cement material from its surface with a treatment solution containing 1 to 30% by weight of alkali silicate,
After drying, further cement 100% on the resulting surface
Weight part, fine aggregate 50-300 weight part and film elongation rate
A cement-based material characterized by applying and curing a coating material containing 5 to 100 parts by weight of an acrylic polymer emulsion with a solid content of 1500% or more and a glass transition temperature of -10°C or less. Surface reinforcement finishing method.