JPS63151693A - Surface finishment for cement set body - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for finishing the surface of a hardened cement body such as hardened concrete, mortar, or cement paste, and more specifically relates to a method for forming a film on the surface of a hardened cement body. It concerns a novel method.

[Conventional technology]

If hardened cement is used without surface treatment, cracks may occur due to corrosion of the hardened material itself due to chemical substances, neutralization due to the action of carbon dioxide in the air, or corrosion of reinforcing steel due to the action of salt such as seawater. etc., the deterioration will be accelerated.

For this reason, a film is formed on the surface of the hardened cement to provide a surface finish to prevent the ingress of chemicals, carbon dioxide, salt, moisture, etc. Generally, inorganic or organic materials are used to finish the surface. There is a method of applying or gluing.

[Problem that the invention seeks to solve]

However, the coating formed by the conventional method may peel off due to drying shrinkage of the hardened cement product or a difference in coefficient of thermal expansion from the hardened cement product, and thus does not fulfill its role satisfactorily.

[Means for solving problems]

In order to solve the above-mentioned problems, the present invention provides a film retaining material having voids into which cement paste can enter, on the inner surface of a formwork for molding a hardened cement product, which forms the surface that requires surface finishing of the hardened cement product. After spreading, a cement mixture is placed in the formwork, and after the cement mixture has solidified, it is removed from the mold, cured, and cured. The present invention provides a method for finishing the surface of a cured cement product, which comprises applying a coating to form a film on the surface of the cured cement product.

[Effect]

The operation of the present invention will be explained using the drawings.

FIG. 1 is a schematic cross-sectional view showing the process of forming a film in the method of the present invention, where l is a mold for forming a hardened cement product, 2 is a film holding material, 3 is a hardened cement product, and 4 is a film.

When a film retaining material 2 having voids through which cement paste can enter is spread on the inner surface of the formwork 1 (Fig. 1a), and a cement mixture is poured into this formwork, part of the cement paste in the cement mixture is poured. The part enters the gap into which the cement paste can enter from the surface of the film retaining material 2 that is in contact with the cement mixture, and after the cement mixture has solidified, it is removed from the mold and cured to harden. The surface layer of the hardened cement body 3 is formed by the hardened portion.

It is fixed (Fig. 1b).

When paint is applied to the surface of the hardened cement body 3 to which the film retaining material 2 is adhered, the paint penetrates into the gaps in the film retaining material 2 where the cement paste did not enter and covers the surface of the hardened cement body 3. , and solidify to form a coating 4. Since the film retaining material 2 is continuously distributed over both the hardened cement body 3 and the film 4, the covering M4 can reliably cover the surface of the hardened cement body 3 without peeling off.

The film retaining material 2 is spread on the inner surface of a mold 1 for forming the surface of the hardened cement body 3 that requires surface finishing.

The film-retaining material is not particularly limited as long as it has voids into which the cement paste in the cement mixture can enter and has the strength to hold the film on the surface of the hardened cement body. Polyamide, Organic polymer compositions such as polyaramid, polyimide, polyester, polyvinyl chloride, polyvinyl alcohol, polyolefin, and carbon.

Woven fabrics, non-woven fabrics 1 Artificial leather, synthetic leather made of inorganic materials such as glass and slag, either singly or in combination.

It can take the form of a foam having i-cells (so-called sponge structure), but woven fabrics, non-woven fabrics, artificial leathers, and synthetic leathers made of organic polymer compositions are suitable because they are easy to obtain and handle.

In order to improve the adhesion of the film-retaining material to the hardened cement, and to prevent the cement paste from entering the surface of the film-retaining material in contact with the formwork and preventing the paint from penetrating into the film-retaining material, It is also possible to use a film retaining material having a coarse structure on the cement hardened body side and a dense structure on the formwork side.

When spreading the film-retaining material onto the formwork, it is sufficient to simply place it on the bottom surface if it is being spread on the bottom surface, and apply appropriate moisture to the surface of the formwork or the surface where the film-retaining material is spread onto the formwork. It can be pasted by If it is necessary to spread it to the side of the formwork or to the bottom of the formwork with a certain degree of strength, it can be adhered with adhesive. ° It is suitable to use, for example, an aqueous solution of polyvinyl alcohol as the adhesive.

Paints can be made from natural resins, bitumen, oils, synthetic resins, and cellulose derivatives.
It is also possible to add pigments and the like for the purpose of imparting beauty to the finished surface. Further, the paint can be cured by baking if necessary.

The hardened cement body to which the surface finishing method of the present invention is applied is
Can be molded with Portland cement, blast furnace cement, silica cement, fly ash cement, etc., and can be molded with reinforcing bars,
It may or may not be reinforced with a reinforcing material such as reinforcing fibers.

〔Example〕

The present invention will be explained in further detail with reference to Examples.

The materials used in the examples are as follows.

Concrete mix Ordinary Portland cement 286kg/ln” water
186 Fine aggregate 894 Coarse aggregate
917〃AE water reducing agent 0
．． 72 tt mortar blend Ordinary Portland cement 519kg/rn” water
241 Fine aggregate 1557 tt Non-woven material Polypropylene thickness
1mm Example 1 (Test specimen 1) A nonwoven fabric with a length of 500 rnn and a width of 500 mm was placed on the bottom of a formwork with a length of 500 mm, a width of 500 mm, and a height of 100 mm, and concrete was poured into this form. The post-mold was cured for 24 hours in a constant temperature room at 20°C, and was further cured for 28 days in a constant temperature room at 20°C.

After curing, an epoxy resin was applied to the surface of the concrete to which the nonwoven fabric had adhered, and was allowed to harden to form a film on the surface of the concrete.

(Test specimen 2) A nonwoven fabric measuring 500 mm long and 500 mm wide was adhered to one side of a formwork measuring 500 mm long, 100 mm wide, and 500 mm high. For adhesion, a thin layer of polyvinyl alcohol aqueous solution was applied to the surface of the mold. After the nonwoven fabric was bonded, concrete was poured. The poured concrete was treated in the same manner as Test Specimen 1.

Both test specimens 1 and 2 had smooth surfaces coated with paint. Furthermore, when cores were taken from the concrete and the finished surfaces were observed using a stereomicroscope, the results showed that the surfaces were smooth, the coating was completely formed, and the adhesion between the concrete and the coating was perfect.

Example 2 Specimens for water permeability tests and water absorption tests were molded, and water permeability tests and water absorption tests were conducted.

The mold for making the specimen was 150 mm in diameter and 40 mm in height for the water permeability test, and a nonwoven fabric was placed on the inner bottom.
The formwork for water absorption test is 160mm long, 40mm wide, and 40mm high.
mm, and a nonwoven fabric was adhered to the inner bottom surface, both end surfaces, and both side surfaces by applying a thin layer of polyvinyl alcohol aqueous solution. 1 Specimens for water permeability test and water absorption test are:
In both cases, mortar was packed in two layers using a table vibrator, and curing and paint application were performed in the same manner as in Example 1.

A water permeability test and a water absorption test were conducted according to JIS A 1404 (Test method for cement waterproofing agents for construction). The test water pressure in the water permeability test was 3 kg/CffI'', the test time was 1 hour, and the number of test days in the water absorption test was 7 days.

The test results are shown in Table 1 along with a comparative example that was the same as the example except that no nonwoven fabric and paint were used.

Table 1 Water permeability (g) Water absorption (g) Example 0.2 0.2 Comparative example 1
9.7 29.6 The coating according to the method of the invention showed sufficient waterproof properties.

Example 3 A nonwoven fabric was placed on the bottom of a formwork measuring 400 mm in length, 100 mm in width, and 100 mm in height, concrete was poured, and curing and paint application were performed in the same manner as in Example 1.

The obtained specimen was subjected to an accelerated neutralization test for 6 months using a test tank with a CO2 concentration of 10% by volume. After the test, the specimen was cut and a 1% alcohol solution of phenolphthalein was applied to the cut surface. After spraying, the distance from the surface of the part that did not turn red was measured and determined as the neutralization depth.

The measurement results are shown in Table 2 together with a comparative example that was the same as the example except that the nonwoven fabric and paint were not used.

Table 2 Neutralization Depth mm) Average Maximum Minimum Examples o, o o, o o,
.

Comparative Examples 11.1 18.0 4.5 No neutralization occurred in the Examples, indicating that the coating produced by the method of the present invention was not breathable.

〔Effect of the invention〕

By the method of the present invention, the film is formed integrally with the hardened cement body through the film retaining material, so there is no risk of peeling, and it has sufficient waterproofness and no air permeability, so the chemical We were able to obtain a coating that can prevent deterioration due to corrosion due to carbon dioxide, carbonation due to carbon dioxide gas, and cracks due to corrosion of reinforcing steel due to the action of salt in seawater.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view showing the process of forming a film in the method of the present invention.

Claims (1)

[Scope of Claims] 1. A film retaining material having voids into which the cement paste can enter is spread on the inner surface of the formwork for molding the hardened cement material on which the surface of the hardened cement material that requires surface finishing is to be molded, and the mold A cement mixture is placed in the frame, and after the cement mixture has solidified, it is removed from the mold and cured to harden. Then, paint is applied to the surface of the hardened body to which the film retaining material is adhered, and the cement hardens. A method for finishing the surface of a hardened cement body, characterized by forming a film on the surface of the body. 2. The method for surface finishing a cured cement body according to claim 1, wherein the film-retaining material is a woven fabric, non-woven fabric, artificial leather, or synthetic leather made of an organic polymer composition.