JPH0316980A - Concrete deterioration-preventive construction - Google Patents

Abstract

PURPOSE:To obtain concrete with improved durability to its neutralization by applying on a concrete form a resin emulsion followed by a polymer cement- based cured layer and a water based emulsion coating in this order. CONSTITUTION:Firstly, a concrete form is coated with a resin emulsion containing (A) 1-10 pts.wt., on a SiO2 basis, of colloidal silica and (B) 10-50 pts.wt., on a solid basis, of a resin. Second, a polymer-cement-based material is prepared by blending (1) 5-40 pts.wt., on a solid basis, of a resin emulsion with (2) 100 pts.wt. of cement-based binder made by mixing (a) 100 pts.wt. of cement and (b) 5-30 pts.wt. of a pulverized noncrystalline siliceous material 7000-10000cm<2>/g in fineness such as of waste glass, plate glass, blast furnace granulated slag, fly ash and/or silica fume. Thence, this polymer-cementbased material is applied, after drying of the resin emulsion, on the coated concrete form, and a water-based emulsion coating is then applied on the resulting coated concrete form after curing of said polymer-cement-based material.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a method for preventing deterioration of concrete.

``Conventional technology and issues'' As is well known, when constructing structures, emphasis is placed on workability such as pump installation, increasing the unit water volume, and reinforcing reinforcement due to insufficient number of reinforcing bars. is not carried out correctly, resulting in insufficient cover thickness of the reinforcing bars, resulting in a -TIr condition, which causes cracks in the concrete due to corrosion and deterioration of the reinforcing bars due to carbonation, etc., which is causing serious problems for society. This is becoming a problem.

As a countermeasure to this problem, it is possible to reduce the water permeability and air permeability of concrete by performing appropriate surface treatments to prevent corrosion of reinforcing bars and, in turn, prevent deterioration of concrete. Conventionally, methods for treating the surface of concrete have included applying organic paints, slapping a surface finish, and the like. However, these are more for the aesthetic purpose than for the protection of the concrete itself. The application of organic paints is not sufficient as a countermeasure against cracks caused by the carbonation of concrete in recent years and alkali-aggregate reactions, and the accompanying corrosion of reinforcing bars. This is because organic paints are relatively susceptible to surface deterioration. Factors that cause the appearance deterioration of organic paints include the effects of ultraviolet rays, ozone, oxidation, water,
Chemical effects such as acid gas are considered. In architecture and structures, due to reflection and review of specifications based on disposable thinking during the period of high economic growth, there has been a shift in recent years to a direction in which emphasis is placed on the durability of structures, and concerns about the durability of these organic paints have become apparent. Another method for preventing concrete deterioration is to apply and impregnate concrete with a special aqueous alkali silicate solution, which is an alkaline restoring agent for the surface of concrete. As such an alkalinity imparting agent, it is possible to use an IA agent that supplies alkali ions, and N ao j{ , K'O HCa (
○I-1), nato is used. However, these alkalizing agents react with carbon dioxide gas in the air and become carbonated and neutralized in a short period of time, and the restored alkalinity does not last long, and it cannot be used with drugs containing Na or K. Depending on the type of aggregate used, there is a risk of inducing an alkaline aggregate reaction. Therefore, an alkaline salt that does not contain Na or K and has a slow neutralization rate is preferable, and lithium silicate is also being used. death. However, in reality, there is a limit to the amount of coating chemicals available in order to neutralize the carbon dioxide gas that enters concrete with alkali. According to the Bureau, the most desirable way to prevent concrete deterioration is to make the surface of the concrete structure more dense.

On the other hand, the waterproofing agent shown in Japanese Patent Publication No. 1'361 46434 is said to be applied to a wet concrete surface, and the eluted silicate ions penetrate into the concrete and strengthen the concrete base. ing. but,
Under high temperatures in summer, this waterproofing agent may lack the moisture necessary for curing due to absorption of the substrate and drying from the surface.
If used on the exterior wall of a building, which is subject to severe dryness, it may cause dryout and cause the concrete to peel off from the surface without adhering to the surface of the structure.
! iIt's not working. Therefore, the patent application number 63,900 = 63,900
No. (March 24, 1985, Method for Preventing Surface Deterioration of Cement-Based Hardened Materials), by incorporating a polymer emulsion into this waterproofing agent and using a water-based emulsion paint in combination, We were able to obtain a durable material that can be applied to concrete surfaces and has excellent carbonation suppression ability. However, even in actual concrete buildings, if the material dries out during application, water absorption into the substrate is rapid and large, resulting in an increase in the amount of application and a decrease in water content from the amount of material being applied. This has often caused problems such as poor adhesiveness and initial cracking on the surface of the coating material.For this, it is also a good idea to apply an emulsion-based sealer to the surface. Concrete 1: There are problems with adhesion to the surface, and even peeling may occur, so it is not suitable for practical use.

``Means for Solving the Problems'' In the present invention, intensive studies have been made to prevent moisture from being rapidly absorbed into the underlying concrete during the application of the inorganic permeable materials mentioned above, and to fully exhibit its effects. and achieved the purpose.

The inventors of the present invention have studied various materials that have the above-mentioned inorganic permeable materials that absorb less water into the underlying concrete in the initial stage and do not impair its permeability. the result,
If you apply a resin emulsion containing 1 to 10 parts by weight of colloidal silicone in terms of sjO2 and 5 to 50 parts by weight of resin solids, the concentration of water when an inorganic permeable material is applied is 1). - Suppresses absorption into the II body and does not prevent elution ions from penetrating into the body,
It was found that it has a desirable characteristic of bamboo.

That is, the concrete deterioration prevention work according to the present invention is to apply a resin emulsion containing 1 to 10 parts by weight of colloidal silicone in terms of SiO 2 and 10 to 50 parts by weight of resin solids to a concrete frame. Amorphous silicic materials such as scrap glass, plate glass, granulated blast furnace slag, fly ash, silica fume, etc.
5 to 40 parts by weight of resin emuljoy in terms of resin solid content is added to 100 parts by weight of a cement-based binder made by mixing 5 to 30 parts by weight of 100 parts by weight of cement after finely pulverizing to ~10,000 cm'/g. A polymer cement 1-based material made of the above is applied to the concrete structure after the applied resin emulsion has dried, and further, a water-based emulsion paint is applied to the concrete structure after the polymer cement-based material has hardened. It is.

The present invention will be explained in more detail below.

As is well known, the surface of existing concrete can become extremely dry depending on the conditions;
・A polymer emulsion containing 1 to 10 parts by weight of colloidal silica and 5 to 50 parts by weight of resin solids is applied to the surface, and after drying, a permeable polymer cement-based material is further applied to the initial stage of the substrate. reduces moisture absorption and does not impair permeability.

There are various methods for dispersing the colloidal silica, but the method is to add a silane coupling agent with vinyl fibers to a resin emulsion and combine them in the presence of colloidal silica force, which is a resin known as a silica composite emulsion. It is desirable to use an emulsion in which the surface of the emulsion particles is coated with colloidal silica.

When this emulsion is applied to a concrete body, the permeability of colloidal silica into the concrete body is lower than when an aqueous solution of floidal silica is applied, but it has excellent film-forming properties. Furthermore, the film formed on the surface of the concrete structure is porous because it contains organic polymers and silica78, and since each polymer emulsion particle is covered with a silica component, the surface of the film is porous. The surface of the part is hydrophilic. For this reason, the organic polymer film does not prevent some alkali, silicate ions, etc. from penetrating into the concrete structure from the inorganic cement material applied thereon. Therefore, it exhibits the same effect as the waterproofing agent shown in Japanese Patent Publication No. 61-464-34, and can densify concrete structures.

Further, a part of the colloidal silica penetrates into the underlying concrete structure together with the penetrating components.

Polymers that can be used in the emulsion containing colloidal silica in the present invention include acrylic emulsions such as acrylic styrene, vinyl acetate emulsions such as ethylene-vinyl acetate, and styrene-butadiene latex. An emulsion covering the particle surface is desirable.

This emulsion is applied to the concrete structure and allowed to dry.

After that, powder of 7000 to loo
A polymer cement system containing 5 to 40 parts by weight of a resin emulsion as a resin solid content to 100 parts by weight of a cementitious binder mixed with 5 to 30 parts by weight of an amorphous silicic acid material finely pulverized to oocm'/g. By applying the material to the concrete 1/frame and, after curing, further applying a water-based emulsion paint, it is possible to protect the concrete 1/frame and improve its durability.

The cement used for the polymer cement-based material may be any known cement such as Ordinary Bol 1, Landcemen I, or Early Strength Bolland Cement, or may be an ultra-rapid hardening cement.

Further, the polymer emulzidine to be used may be one having good stability when mixed with cement, such as an acrylic type, a vinyl acetate type, or a styrene butadiene type. Also,
Anionic or nonionic surfactant at 0.01
It may be included up to 1.0% to improve stability and permeability.

Furthermore, paints prepared by adding pigments, thickeners, preservatives, etc. to commercially available acrylic emulsion paints or high-elastic acrylic emulsion paints can be used as water-based emulsion paints, especially water-based emulsion paints. Paint is preferred.

The scope of application of the present invention is the surface of concrete structures, and the effect is particularly great on newly constructed concrete 1. However, the effect is sufficiently recognized even when deterioration has progressed on existing concrete 1. This three-layer coating method can significantly delay deterioration caused by the reaction of the neutralized acrylic aggregate.

"Function" In this way, in the present invention, an emulsion consisting of resin particles whose surface has been coated with colloidal silicone is applied to the surface of a concrete structure and dried, and then an inorganic ion permeable By not preventing the inorganic ions leached from the polymer cement material from penetrating into the substrate, and by minimizing the rapid absorption of moisture into the concrete structure during application, it is possible to improve the densification of the concrete structure. Therefore, it exhibits an excellent effect in terms of durability against carbonation.

Hereinafter, the present invention will be explained in more detail with reference to Examples. Note that the present invention is not limited to the following examples.

[-Example] The manufacturing method of the silica composite emulsion of the present invention used in this example and the emulsicone of the comparative example will be described.

Silica composite emulsion used in the present invention Q-row-J arrow-
Jj-iJ. 1 Monomers consisting of 40 parts of ethyl acrylate, 68 parts of methyl methacrylate, 15 parts of styrene, 15 parts of N-n butene methyl acrylamide, 38 parts of 2-hydroxyethyl acrylate, and 24 parts of acrylic acid. An acrylic co-based water-dispersed resin obtained by polymerizing a mixture of 2,2゜-azobis (2,,j-dimethyl-azobis); in water and an inpropanol solvent with a polymerization initiator consisting of 6 parts 12 (solid content 20%); 375 g was prepared and water-dispersed silica sol (particle size 10-20 mμ) was prepared with sufficient stirring at room temperature.
, SiO, 20%, pH 9 to 10>125g approximately 10
It takes several minutes to drip. Thereafter, 1.5 g of γ-methacryloxypropyl tritrime 1 xy7ran was added dropwise, stirred and mixed, and kept at 85°C for 2 hours to react, yielding a viscous water-dispersed silica; . When the surface of the resin particle was observed using an electron microscope, it was found that the surface was covered with silica fine particles (Silica Composite Emanoresion 1).

30 wL% colloidal silica aqueous solution l Night: Add 100 parts by weight, solid content concentration 35 wL%, 50 cP, pH 8
A composition No. 5 was obtained. When the surface of the resin particle was also observed using an electron microscope, it was confirmed that the surface was covered with silica fine particles (Silica composite emulsion 2).

Manufacturing method of emulsion used in comparative example 1 A silica composite emulsion used in the present invention was manufactured in the same manner as in Note 1 except that no aqueous colloidal silica solution was added (emulsion 3).

Sodium salt of alkylaryl sulfosuccinate;
A solid content obtained by emulsion polymerization of a mixed monomer consisting of 50 parts by weight of butyl acrylate, 44 parts by weight of methyl methacrylate, and 6 parts by weight of γ-methacrylate pyrutrimethoxysilane in the presence of 2 parts by weight. Content 4. ”
O wt% aqueous dispersion: '1oO weight part has a particle size of 10
- 20 mμ, Solid content Manufacturing method 2 of emulsion used in comparative example 2 A method of manufacturing the silica composite emulsion used in the present invention described above was produced in the same manner as in Method 1 except that γ-methacrylate trimethoxysilane was not added. (Emulsion 4).

Tsutsumi'fi fal Method for producing an emulsion with an amount of M 3
? The emulsion used in the present invention was produced in the same manner as in step d2, except that no colloidal silicate aqueous solution was added (Emulzidine 5).

Manufacturing method of emul/:I used in comparative example 4 Manufactured in the same manner as in emulsion manufacturing method 2 used in the present invention except that γ-methacryloxypipill 1, lime 1, and beef shishiran were not added (emulsion 6) .

"Example 1" In the present invention, coating is performed in three layers, and the first coating material,
The second coating material and the third coating material were respectively set and coated as follows.

First, the silica composite emulsion 1 was used as the first coating material, and as the second coating material, 20 parts by weight of plate glass finely pulverized to a fineness of 8000 cm''/g and acetic acid were used as the second coating material. Vinyl powder resin emulsion DM289 (Hex 1, manufactured by Gosei Co., Ltd.)
, 60 parts by weight of No. 6 silica sand, dispersant polio-bovine styrene nonyl phenyl ether (1-1 1.. B 1 3
) 0. 2 parts by weight, powdered silicone foam Qi 11s
N Deformer-14HP (San Nopco Co., Ltd.) 1 part by weight is mixed with 3 parts by weight per 100 weight lU of this mixture.
A mixture mixed with 0 parts by weight of water was used. An acrylic emulsion water-based building paint (manufactured by Asahipen Co., Ltd.) was used as a third coating material on this coating film.

"Example 2" Using the silica composite emulsion 2 as the first coating material,
The same materials as in Example 1 were used as the second coating material and the third coating material, and the same procedure as in Example 1 was carried out.

Next, a comparative example with respect to the above example will be shown.

"Comparative Example 1" In the above example, a material consisting of the second coating material and the third coating material excluding the first coating material was used.

The second coating material and the third coating material are the same materials as in Example 1.

"Comparative Example 2" The emulsion 3 was used as the first coating material, and the same materials as in Example 1 were used as the second coating material and the third coating material.

"Comparative Example 3" The emulsion 4 was used as the first coating material, and the same materials as in Example 2 were used as the second coating material and the third coating material.

"Comparative Example 4" The emulsion 5 was used as the first coating material, and the same materials as in Example 1 were used as the second coating material and the third coating material.

"Comparative Example 5" The emulsion 6 was used as the first coating material, and the same materials as in Example 1 were used as the second coating material and the third coating material.

Next, the performance of the coating film using each of the above emulsions, Example 1
, 2 and Comparative Examples 1 to 5 and their results are shown below.

(Performance test) Each of the silica composite emulsions 1 and 2 and emulsions 3 to 6 was tested on a flexible board, (JIS A
5403) and the coating thickness. After applying the coating to a constant level and drying it at 20°C and 60%RH for 2 weeks, apply JTS
A water permeability test was conducted according to the method of A6910. The amount of water permeation was measured twice, once after 1 hour and after 24 hours. Table 1
The results are shown below, and it can be seen that the wrinkle strength composite emulsion used in the present invention has low water permeability at the initial stage, but becomes considerably water permeable after one day.

Using Examples 1 to 2 and Comparative Examples 1 to 5, a sufficiently dried mortar base plate was subjected to a two-layer treatment.

An adhesion strength test was conducted on the cholera specimen according to JIS A 6910. The results are shown in Table 2.

It can be seen that the present invention has excellent adhesion strength, less absorption into the substrate, and excellent workability.

[Table 2] "Effects of the Invention" As explained above, the method for preventing deterioration of concrete according to the present invention is to apply an emulsion made of resin particles whose surface is coated with colloidal silica force to the surface of a concrete body and to dry it. Furthermore, it does not prevent the inorganic ions leached from the inorganic ion-permeable polymer cement material applied to the top surface from penetrating into the substrate, while minimizing the sudden absorption of moisture into the concrete structure during application. By suppressing the carbon content to 20%, the concrete 1/20 densities are produced, and it exhibits an excellent effect in improving the durability of concrete against neutralization.

Claims (2)

[Claims] (1) Colloidal silica from 1 to 10 in terms of SiO_2
A resin emulsion containing 10 to 50 parts by weight of resin solids is applied to the concrete structure, and amorphous silicic materials such as scrap glass, plate glass, granulated blast furnace slag, fly ash, and silica fume are powdered to a powder degree of 7000.
Contains 5 to 40 parts by weight of a resin emulsion in terms of resin solids in 100 parts by weight of a cementitious binder made by mixing 5 to 30 parts by weight of finely ground powder to 10000 cm^2/g to 100 parts by weight of cement. A polymer cement-based material made of the above-mentioned applied resin emulsion is applied to the concrete structure after drying, and a water-based emulsion paint is further applied to the concrete structure after the polymer-cement material has hardened. Deterioration prevention method. (2) The method for preventing deterioration of concrete according to claim 1, wherein the silica particles in the resin emulsion containing colloidal silica cover the resin particles of the emulsion.