JPH0269375A - Concrete covering material and covering method - Google Patents

Abstract

PURPOSE:To improve the durability, water and chemical resistances of concrete by covering the surface of the concrete with a covering material consisting of the hydrolyzate of a metal alkoxide and an inorg. filler. CONSTITUTION:A metal alkoxide (e.g., alkoxysilane, alkoxy zirconium or alkoxy titanium) is hydrolyzed. The resulting hydrolyzate is mixed with an inorg. filler (e.g., zircon, silica, mica or graphite) to obtain a covering material and the surface of concrete is covered with the covering material.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a concrete coating material and a coating method using the same. More specifically, this invention
The present invention relates to a concrete coating material and a coating method that can improve the durability, water resistance, chemical resistance, etc. of concrete.

(Background Art) Conventionally, a wide variety of surface coating materials have been used to improve the durability of concrete products such as concrete, mortar, cement, and slate. Especially in recent years, concrete has been affected by salt damage, carbonation, and deterioration due to chemicals.
As research into concrete deterioration due to alkaline aggregate reactions progresses and detailed reports are published in various places, surface coating methods are attracting more attention as a countermeasure against such concrete deterioration.

These conventional coating methods include a variety of methods, including those in which concrete products and concrete structures are coated immediately after they are formed, and those in which they are coated after deterioration has begun. There are a wide variety of substances, from inorganic to organic. It is also widely known that the most practical type is a curable resin coating made of acrylic resin.

However, in many cases, the concrete coating materials known so far have excellent durability, especially water resistance and chemical resistance, and are not inexpensive, making them practical in terms of both performance and cost. The reality is that we cannot find anything that is completely satisfying. Of course, many coating material compositions and methods of use have been proposed, but this situation has not changed.

In such a situation, the important question is how to solve the following issues.

The first is that concrete (including mortar, cement, slate, etc.) itself is strongly alkaline (pH 12~
13), and this strong alkalinity advances the destruction of the paint film and generates efflorescence, which significantly impairs the lifespan and beauty of the coated paint film.

The second reason is that concrete, unlike metal or ceramic materials, absorbs moisture. In other words, chemically bound water with cement and gel water exist in the internal structure of concrete, and free water exists in the pores, and these evaporate into the air, and moisture in the air also exists. Including it, it can be further fitted inside.

This latter problem is particularly problematic in the case of modern resin coatings. In order to improve the chemical resistance of concrete, attempts have been made to coat the surface of concrete with organic paints such as acrylic resins, epoxy resins, urethane resins, and fluororesins, which have excellent chemical resistance. However, although this coating has excellent properties such as chemical resistance and weather resistance, it has the opposite characteristics of air-blocking and sealing properties, so it has a serious drawback of being prone to blistering and peeling due to the water vapor pressure inside the concrete. There is. Moreover, these resin-based coating materials are extremely expensive.

Although it has been proposed to provide a ventilation layer between the coating film and the concrete in order to improve the ventilation blocking and sealing properties, the construction cost in this case would be extremely high and would be impractical.

In order to overcome the above-mentioned problems, we have taken a completely different approach, which does not form a covering layer by itself, but chemically bonds with the concrete base, making the concrete waterproof and resistant without impairing its permeability. Penetration treatment materials using silane compounds have been developed to improve alkalinity, salt resistance, weather resistance, and the like. However, since these silane compounds are not originally intended to improve the chemical resistance of concrete, they prevent ions from a limited number of chemicals (alkali and salts) from entering the concrete. It can only be prevented.

Although they are used as coating materials, various inorganic coating materials have been studied in order to improve the drawbacks of resin-based coating materials. For example, it has been proposed that a filler such as alumina, silica, mica, etc. is mixed with a binder such as alkali silicate, alkyl silicate, or colloidal silica. However, even in these cases, nothing has been found that improves the durability of concrete, especially its chemical resistance.Moreover, these are easily soaked in the alkali of concrete and lack visibility to correspond to the shrinkage and expansion of concrete. It has the disadvantage of poor workability. It has also been proposed to bake these inorganic coatings, but the effects in this case are also not satisfactory.

(Objective of the Invention) This invention was made based on the above-mentioned circumstances, and it solves the drawbacks of conventional concrete coating materials and infiltration treatment methods, and improves durability, especially chemical resistance and water resistance. The purpose of the present invention is to provide a new concrete covering material and its covering method that can realize excellent concrete products and concrete elliptical relics.

(Disclosure of the Invention) In order to achieve the above object, the present invention provides a concrete coating material comprising a mixture of a metal alkoxide hydrolyzate and an inorganic filler.

The present invention also provides a method of coating a concrete surface with this coating material.

The main components of the coating material of this invention are the metal alkoxide hydrolyzate and inorganic filler as described above.
Among these, the hydrolyzate of metal alkoxide has the general formula M
(OR) is a product obtained by hydrolyzing a metal alkoxide such as alkoxysilane, alkoxyzirconium, alkoxytitanium, etc., and is a 5t-0-3t product obtained by hydrolyzing an alkoxysilane in the presence of an acid catalyst. Those having a bond can be exemplified as particularly preferred.

This hydrolyzate may be mixed with an inorganic filler and hydrolyzed, or may be mixed with an inorganic filler and hydrolyzed. , conditions such as use of catalyst, etc.
It may be selected appropriately depending on the type and usage amount of the target metal alkoxide.

As the inorganic filler to be mixed with the hydrolyzate, an inorganic substance or metal in any shape such as powder, flake, or fiber can be used. for example,
Chemically resistant materials such as zircon, silica, mica, alumina, zirconia, glass flakes, glass fibers, graphite, and stainless fibers can be used as appropriate. Regarding these fillers, consider the balance between the performance of the resulting coating and the cost! 113i! For example, if you want to make it cheaper, use a lot of silica, and if you want to increase visibility and thicken the coating, use mica, glass flakes, glass fibers, etc. in flake or fiber form. You just have to mix a lot of things together.

These inorganic fillers may be used alone or
Multiple types may be used.

The mixing ratio of the metal alkoxide hydrolyzate and these inorganic fillers is also determined appropriately. - Inside the shell, for example, in the case of zircon (specific gravity 4.7), the hydrolyzate solution/zircon (weight ratio) is about 171.5 to 1/3,
In the case of silica (specific gravity 2.7), similarly 110.5 ~
Add mica (particle size 50 to 300) to about 1/2.
μIl), the weight ratio is zircon/mica = 4/1 to 10/1, silica/mica 2/1 to 6
/'1 is preferable, and the mixing ratio of other types of inorganic fillers may be determined using these values as a guide.

Note that as the mixing ratio of mica increases, the hardness of the coating decreases, so this needs to be taken into consideration depending on the application purpose of the coating material. Hard fibers such as glass fibers and stainless steel fibers have a
It is also effective in preventing cracks when a thick coating of about 1 mm is required. In terms of cost, the larger the weight ratio of silica, the cheaper it will be, but this will also reduce the abrasion resistance, so it is necessary to take this point into consideration.

When using the above-described coating material, the film thickness may be appropriate, and can be determined depending on the composition of the coating material and the purpose of coating. In addition, in this coating, after the coating is completed, it is preferable to perform a penetration treatment with a silane compound to improve waterproofness. In this case, the silane compound is preferably an alkyl alkoxysilane. By infiltrating the coating layer with a compound, chemical resistance and salt resistance can be significantly improved.

By using the coating material of the present invention and its use, an inorganic film, which was conventionally thought to be susceptible to alkali unless heat-baking treatment is applied, can be effectively used as a material with excellent durability, especially chemical resistance. can.

Mixing inorganic fillers also provides flexibility that can accommodate the contraction and expansion of concrete.

Next, the present invention will be explained in more detail by showing examples.

Examples 1 to 7 (^) Preparation of coating material A hydrolyzate of metal alkoxide as a binder was prepared using ethyl silicate Si (OC2H%)4.

That is, 1 m01 of ethyl silicate is 0.025 no
Hydrolysis was carried out in a mixed solvent of ethanol and water using 1 of sulfuric acid as a catalyst at a temperature of 20° C. over a period of 24 hours.

The inorganic filler had a composition shown in Table 1 below. The coating materials of Examples 1 to 6 shown in Table 1 were prepared as mixtures of this filler and the above hydrolyzate.

(B) Coating of concrete The surface of concrete was coated using the coating materials of Examples 1 to 6 above.

Further, after this coating was performed, the coating layer was also subjected to an infiltration treatment with an ethanol solution of methyltriethoxysilane. The coating layer in this case was based on Example 1 (Example 7).

For further comparison, tar epoxy resin paint (Comparative Example 1) and acrylic resin paint (Comparative Example 2) were applied to concrete.
) and a concrete coated with methyltriethoxysilane (Comparative Example 3) were prepared.

(C) Evaluation of chemical resistance Concrete coatings (Examples 1 to 7, Comparative Examples 1 to 2) and concrete infiltration treated products (Comparative Example 3) were immersed in various chemicals for 10 days as shown in Table 2. And I saw its appearance change.

In the case of the examples of this invention, as shown in Table 2, it can be seen that they have excellent chemical resistance.

In the case of acrylic resin paint (Comparative Example 2), the resistance to all chemicals was insufficient, and in the case of only penetration treatment with a silane compound (Comparative Example 3), the resistance to acids was extremely low. bad.

(D) Evaluation of ion permeation amount The ion permeation amount was evaluated using the configuration shown in FIG.

That is, Table 3 was applied to the unglazed container (1) whose inner surface was coated.
The aqueous solution (2) shown in (2) was added to the water (4) placed in the outer container (3), and the amount of ions was measured after one week.

Table 3 shows a comparison with no coating.

Table 2 Chemical resistance A: No change B: Destruction within 3 to 9 days C: Destruction within 1 to 2 days Table 3 Amount of ion permeation The embodiment of this invention effectively prevents ion permeation. I know what you're doing.

(E) Evaluation of water vapor permeation amount The amount of water vapor permeation was evaluated using the configuration shown in FIG.

That is, silica gel (6) is placed in an unglazed container (5) whose outer surface is coated, the upper part is sealed with an acrylic plate (7), and placed in a curing chamber at a temperature of 20°C and humidity of 100% for one week. The weight of silica gel (6) was measured.

Table 4 shows the results, and in the case of the examples of the present invention, the permeability was very good, equivalent to that without coating.

A...Transmission amount of 1/100 or less B...1/10 to 1/100 transmission amount C...1/2 to 1/10 permeation amount D...Transmission amount table equivalent to that without coating 4 Water vapor transmission amount A: Mostly uncoated No change, 80-100% Transmittance of B...20-80% transmittance C... has almost no breathability.

Examples 8 to 11 of transmittance of 0 to 20% Covering materials were produced in the same manner as in Examples 1 to 7, and concrete was covered. The blending ratio is as shown in Table 5.

Along with Comparative Examples 1 and 2, the characteristics were evaluated as shown in Table 5.

The stainless steel fibers blended in Examples 8 to 11 had a diameter of 5US430L and a diameter of 8. Un, with an average length of 11, was used. In addition, when using stainless steel fiber, - the inside of the shell has a diameter of 5 to 100 μm, more preferably 5 to 30 μm.
Diameter and length 100μm to 31ri, more preferably 200μm
µm to 111 l is used. If the diameter becomes thicker than 100 μm, the finish of the concrete covered surface will become rough. For example, in the case of Huyume pipe, the standard roughness coefficient is 0.014.
As a result, the workability is poor and undesirable, and when the length exceeds 3u, the roughness coefficient tends to increase.

In addition, the stirring properties during mixing and the workability become worse.

In the case of this invention, as shown in Table 5, cracking resistance, outdoor durability, skewer abrasion resistance, adhesive strength, and chemical resistance are all good.

(Effects of the Invention) The present invention provides a low-cost concrete covering material that has excellent durability, particularly chemical resistance.

The concrete coating also has excellent visibility.

By penetrating with a silane compound, water resistance and chemical resistance are further improved.

[Brief explanation of the drawing]

FIG. 1 and FIG. 2 are a perspective view and a partially cutaway perspective view, respectively, showing equipment for evaluating the amount of ion permeation and the amount of water vapor permeation used in the embodiment of the present invention.

Claims (5)

[Claims] (1) A concrete coating material comprising a mixture of a metal alkoxide hydrolyzate and an inorganic filler. (2) The concrete covering material according to claim (1), which contains an inorganic filler in the form of powder, flakes, and/or fibers. (3) The inorganic filler is zircon, silica, mica,
The concrete covering material according to claim 1, comprising graphite, glass and/or metal. (4) A method for coating concrete, which comprises coating a concrete surface with the concrete coating material according to claim (1). (5) A method for coating concrete, which comprises forming a coating by the method according to claim (4) and then impregnating it with a silane compound.