JPS62288181A - Coating material for concrete - 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 3. Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a coating material for concrete and mortar (hereinafter simply referred to as "concrete"), and in particular, The present invention relates to concrete coating materials used to prevent early deterioration of concrete caused by alkali-aggregate reactions and to repair concrete structures that have expanded and deteriorated due to alkaline aggregate reactions.

(Prior Art) In recent years, many cases of concrete structures in which early deterioration has occurred due to alkaline aggregate reactions have been reported and are attracting attention.

The factors that cause alkaline aggregate reactions are A) reactivity in the aggregate, B) alkaline content in concrete, and C) moisture. Therefore, in order to prevent or suppress early deterioration of concrete structures due to alkaline aggregate reactions, It is sufficient to eliminate at least one of these factors.

Specific measures for this purpose that have been proposed or implemented in the past are, for example, as follows.

a) Measures to eliminate reactivity regarding aggregates Regarding aggregates, consider the past experience and conduct various evaluation tests to identify aggregates that may have alkali reactivity and avoid using them.

b) Measures to reduce alkaline content in concrete i) Alkali concentration (Na 0 equivalent, weight ratio to cement) is 0.
Use low alkali cement of 6x or less.

ii) Part of cement is replaced by pozzolan such as fly ash and silica hume to reduce the alkaline content in concrete to 3 kg/m' or less.

C) Measures to eliminate moisture i) By blending acrylic or epoxy synthetic resin, the concrete itself to be poured becomes dense.

ii) For the same purpose as in i) above, an acrylic or epoxy synthetic resin paint is applied to the surface of concrete to form a water-impermeable surface layer.

(Problems with the conventional method) However, the above-mentioned countermeasures using the conventional method have the following problems.

First of all, regarding the aggregate itself, conducting tests to determine its toxicity requires specialized skills and a long time, and the alkali reactivity may vary depending on the source of the rock or the location where it is collected. There are many problems, and since aggregate is also a limited resource, it may be necessary to use it even if there is some doubt about its alkali reactivity. Next, although low-alkali cement has now been standardized in JIS, its use results in high costs, and there are many cases where pozzolan, blast furnace slag, etc. cannot be used due to the type of structure or environmental conditions. The problem is that there is no. Finally, waterproofing using synthetic resins inevitably increases costs, and if large structures or retaining walls are waterproofed using synthetic resins, moisture will be trapped inside the structure. As a result, there is a problem in that there is a possibility that the aggregate reaction may be promoted.

(Circumstances leading to the invention and purpose of the invention) In order to prevent or suppress the alkaline aggregate reaction in concrete, it is important to eliminate at least one of the three major factors mentioned above. It is difficult, or rather impossible, to judge in advance whether or not an aggregate reaction will occur in poured concrete. Taking this into consideration, assuming that an aggregate reaction has occurred in a concrete structure, the best way to prevent or suppress early deterioration of this concrete structure in the future is to prevent moisture from entering from the outside. seems to be the only way to do so.

For this purpose, the use of synthetic resin materials is naturally envisaged. However, common synthetic resin paints such as acrylic and epoxy paints that have traditionally been used for this purpose are
As mentioned above, it has the so-called negative effect of actually accelerating the aggregate reaction.

Therefore, the main object of the present invention is to provide a coating material for concrete that does not promote the alkaline aggregate reaction.

An additional object of the present invention is to provide a coating material for concrete that can follow the deformation and exhibit the desired performance even if an alkaline aggregate reaction occurs and the concrete expands as a result. It is in.

(Means or action for achieving the object) According to the present invention, the above object is achieved by combining the resin content of a polyacrylic acid ester copolymer emulsion with a glass transition temperature of -60 to 0°C, cement, and fine bones. Material and 1: 2.5-3.5:
Contains at a weight ratio of 0.2-1.5 and has a water permeability of 0.
．． 2cc/day or less, and the moisture permeability is 3.0 mg/
cmj-day or more and an elongation rate of 100% or more after a heat deterioration test.

Among the components constituting the coating material according to the present invention, the glass transition temperature (Tg) of the polyacrylic acid ester copolymer emulsion is specified to be -60 to 0°C. This is because the elasticity becomes excessive and sufficient elasticity cannot be obtained, and if the Tg is 0° C. or higher, the elongation decreases and the ability to follow deformation decreases.

In order to prepare a copolymer emulsion having Tg within the above specified range, emulsion copolymerization may be carried out using appropriate amounts of a soft monomer component and a hard monomer component. Examples of the monomer components include n-butyl acrylate, isobutyl acrylate, hexyl acrylate, n-octyl acrylate, and 2-ethylhexyl acrylate, and examples of the hard monomer components include methyl acrylate, ethyl acrylate, and methyl. Examples include methacrylate, styrene, acrylonitrile, glycidyl acrylate, glycidyl methacrylate, lauryl methacrylate, acrylamide, N-methylolacrylamide, and the like. Incidentally, if necessary, carboxyl group-containing ethylenically unsaturated monomers such as acrylic acid, methacrylic acid, itaconic acid, and maleic acid can also be used.

Among the other components constituting the coating material according to the present invention, any cement such as ordinary Portland cement, white Portland cement, blast furnace cement, silica cement, fly ash cement, etc. can be used. Materials include No. 5-8 crushed sand, river sand, sea sand, cold water sand,
Although lightweight aggregates and the like may be used, crushed sand is most preferably used.

The above three components constituting the coating material according to the present invention are used in the ratios mentioned above, but this is because if the amount of cement is excessive, the elongation rate will not be sufficient when the copolymer emulsion is used as the standard. On the other hand, if the amount of cement is too small, the amount of water permeable tends to be too small, and if the amount of fine aggregate is excessive, the coating film becomes rough. This is because if the amount of water permeation becomes too large and the amount of wire aggregate is too small, the coating film becomes dense, and as a result, although the amount of water permeation can be made small, the amount of moisture permeation tends to be too small.

In addition, in the coating material according to the present invention, the amount of water permeation is 0.2 c
It is specified that it is less than c/4ay, but this value is r J
It was measured in accordance with ``ISAS A-6910 Multilayer Pattern Spray Material 6.4 Water Permeability Test'', the lower the better, and there is no lower limit, however, according to this JIS standard, 0.5
cc/day or less, but the coating material to which the present invention relates may not be able to provide sufficient waterproofness unless it is 0.2 cc/day or less. be. The moisture permeability is 3. Otag/c
mj-day or more, but if the moisture permeability is less than this, there is a risk that moisture will be trapped inside the concrete structure and promote aggregate reaction, so there is no upper limit for this amount. No, and the elongation rate after heat deterioration test is 1
00% or more, but if it is less than 100%, it will be impossible to follow the expansion deformation of concrete due to the alkali aggregate reaction, and there is no upper limit for this value either.

As described above, when compared with conventionally used acrylic paints and epoxy paints, the coating material according to the present invention is slightly lower in waterproofness but superior in moisture permeability. Overall, less water is incorporated into the aggregate, thereby eliminating the problems associated with prior art methods of promoting aggregate reactions due to water entrapment. In addition, coating films made of general synthetic resin paints such as acrylic and epoxy paints are brittle and have little resistance to deformation, but the coating material of the present invention has a high elongation rate and is therefore elastic. Because it has
Even if the concrete expands due to the alkaline aggregate reaction, it can follow this expansion and deformation and exhibit the desired waterproofness and moisture permeability.

The coating material for concrete according to the present invention can be applied to concrete structures for the purpose of preventing early deterioration due to alkaline aggregate reaction, and can also be applied to concrete structures after expansion and deterioration due to alkaline aggregate reaction has occurred. It can also be used to prevent or suppress the progress of expansion and deterioration. The coating film formed by this coating material has the ability to evaporate internal moisture while blocking moisture from the outside, so even if the concrete structure has a high water content, it will dry to the extent that the surface layer remains. It is possible to apply if the condition is as follows. If the surface condition of a concrete structure is poor and there is a possibility that problems may arise in terms of adhesion even if the coating material of the present invention is applied, it is possible to prevent this by applying a primer (undercoat) in advance. can also be dealt with. Naturally, a material with high moisture permeability, such as a silane-based or vinyl ester-based impregnating agent, is used as the primer. Examples of such commercially available impregnating agents include silane-based products such as "Aron Water Shut-8" manufactured by Toagosei Chemical Co., Ltd., and vinyl ester-based products such as "Prover" available from Oseo.

(Manufacturing Examples, etc.) Next, the present invention will be explained in more detail with reference to manufacturing examples of the coating material for concrete according to the present invention and test examples regarding various coating materials including the coating material.

A coating material for concrete was obtained by blending and mixing 1 L of the following components in the proportions (weight ratio) shown below.

Or - 11 minutes 1 Resin of milk button polyacrylic acid ester copolymer emulsion Note 1) 1 Cement (
Note 2)3 Water
1.0 Silica sand (No. 8) 0.5 Antifoaming agent (Note 3) 0.01 Note 1) Acryset EMN-2957J manufactured by Nippon Shokubai Chemical Co., Ltd. Tg knee 26℃ Resin content = 55% Note 2) Onoda cement Ordinary Portland cement manufactured by Dow Corning Note 3) rFS Antiform 001 manufactured by Dow Corning. Test coating material sample (sample P
Samples PI, P2, P5 and P6 as control coating samples and commercially available solvent type 1
The following tests were conducted using a liquid acrylic paint (Sample^) and a solvent-based two-component epoxy paint (Sample E).

1) Water permeability test r Based on JIS A-6910 Multi-layer pattern sprayed material 6.4 Water permeability test.

2) Moisture permeability test The test equipment as shown in the attached drawings is used, that is, a closed cylindrical glass container 10 is placed in two chambers, upper and lower, using a mortar specimen disk TS coated with each coating material (pre-coated, material age 8 weeks). 12.14, the lower chamber 12 accommodates a plastic container 12A containing water, the upper chamber 14 accommodates an aluminum container 14B containing silica gel 14A, and water vapor is generated in the lower chamber. The amount of moisture permeation is measured by examining the weight change of the silica gel in the upper chamber.

3) Tensile test r Based on JIS A-6021 Roof Waterproof Coating Materials 5.1 Tensile Test.

The results were as shown in Tables 2 to 4 below.

Table - Yuj water permeability test results) 1 East milk L1JL (cc/day) pt 0.14 P2 0.20 P30.11 P4 0.16 P5 0.70 P6 0j3 A O,25 E O,15 Table-1 (Moisture permeability test results) Moisture permeability (H/cm"・day) Pl
2.1 ['2 2.0 P3 3.3 P4 3.5? 5 4.0 P6 3.8 A2.9 E2.6 Private sector (Tensile test results) From the results shown in Tables 2 to 4 above, the coating material samples P3 and P4 according to the present invention were tested in the water permeability test. It was found to be good through various physical property tests including a wet test, an elongation test, and a tensile test. Coatings made from general acrylic and epoxy paints also show relatively good results, but as seen in Table 4, they lose elongation (elasticity) and become brittle after the heat deterioration test. It has also been found that it is unsuitable as a coating material that is applied to a concrete structure and must follow the expansion and deformation when the concrete structure expands.

Mortar specimens for expansion measurement tests were prepared with dimensions, reactive aggregate particle size distribution, and curing conditions according to STM C-227 (mortar bar method).

Immediately apply the test sample (coating material) to the mortar specimen after demolding (pre-coating), or apply the test sample after the mortar specimen has been cured for two weeks to expand by approximately 0.05X (pre-coating). The results of measuring the expansion rate at 6 months of age are as shown in Table 5 below. Also, in the test sample?
■ to P6, A and E are the same as those used in Test Example 1, N is an uncoated control sample, and P6 is the same as that used in Test Example 1.
3X shows the case where a vinyl ester impregnation agent ("Prover" manufactured by Oseo) was applied as a primer prior to application of test sample P3.

Table j- From these results, it can be seen that whether the coating material is applied before expansion due to aggregate reaction occurs (pre-application) or after expansion occurs (post-application), subsequent expansion, i.e., this It is possible to suppress the deterioration of concrete structures caused by water, but if the coating material used is waterproof enough, the effect of suppressing aggregate reaction will be affected by the moisture permeability of the coating material. The higher the moisture permeability, the better the effect of suppressing the expansion of concrete (see Tables 2 and 3 of Test Example 1). It has been found that the combination of a primer with a high coefficient of 0.0 and a high water resistance has excellent waterproofness and moisture permeability, and also exhibits a good expansion-inhibiting effect in both pre-coating and post-coating.

(Effects of the Invention) The coating material for concrete according to the present invention has both waterproofness and moisture permeability, and therefore, when applied to a concrete structure, it appropriately blocks moisture from entering from the outside while simultaneously Since water is released in the form of transpiration, it is possible to effectively prevent or suppress alkaline aggregate reactions in concrete structures and, by extension, their early deterioration.

Furthermore, since the coating material for concrete according to the present invention has excellent elasticity, even if expansion occurs in the concrete structure due to the reaction with the alkali aggregate, the coating material will follow this expansion deformation, thus achieving the desired Waterproofness and breathability can still be maintained.

BRIEF DESCRIPTION OF THE DRAWINGS The drawing is a vertical sectional view showing an outline of the apparatus used in the moisture permeability test conducted in Test Example 1. 10-1 Closed cylindrical glass container, 12-1 Lower chamber, +2A--Plastics container, 1
4-1 Upper chamber, 14A-1 Silica gel, 14B--Aluminum container, TS-1 Mortar specimen disk

Claims (1)

[Claims] (1) The resin content of a polyacrylic acid ester copolymer emulsion with a glass transition temperature of -60 to 0°C, cement, and fine aggregate are mixed in a ratio of 1:2.5-3.5:0.2-1. 5, the water permeation amount is 0.2 cc/day or less, the moisture permeation amount is 3.0 mg/cm^2・day or more, and the elongation rate after heat deterioration test is 100% or more. A coating material for concrete, which is characterized by: