JPH04279674A - Composition for coating concrete structure - Google Patents

Abstract

PURPOSE:To obtain the title composition which prevents the occurrence of holes of concrete structure for man-made gathering-place of fish, wave suppression, check of erosion of rivers and the ocean and preserves alkali from elution, containing an emulsion resin, iron (compound), etc. CONSTITUTION:The objective composition comprising (A) an emulsion resin composed of an acrylic/styrene copolymer, a vinyl acetate/Veova(R) copolymer, urethane (one pack type) or epoxy (one pack type) having <=15 deg.C lowest film- forming temperature and <=20% saponification degree, (B) iron and/or an iron compound such as iron sulfate, iron sulfide, iron oxide, iron nitrate, iron hydroxide, iron carbide, iron carbonate or iron nitride and, in the case of the iron compound showing acidity, (C) a hydrating agent such as calcium hydroxide or cement powder caustic soda.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is applied to concrete structures used for fish reefs, wave dissipation, and prevention of erosion in rivers and oceans in order to prevent alkali from leaching out of the concrete structures. The present invention relates to a composition for coating concrete structures.

0002

[Prior Art] Conventionally, many concrete structures have been used for coastal area reclamation, reclamation, construction of breakwaters and jetties, wave prevention works such as sinking of wave-dissipating blocks, river security, fish reefs, etc. When these concrete structures are submerged in water, alkali (PH10-13) is eluted. The eluted alkali has a negative impact on the habitat of microorganisms, algae, fish and shellfish in the water, and the ecosystem.

[0003] Conventionally, coating agents containing iron, which is necessary for the growth of aquatic organisms, have been applied to the surface of such concrete structures to prevent alkali from leaching out of the concrete structures, and have been applied to the surfaces of such concrete structures, for example. Kosho 62-201
It is disclosed in Japanese Patent Publication No. 62 and Japanese Patent Publication No. 41527/1983. This type of coating agent has already been put into practical use by being applied to fish reefs and concrete structures, and has proven effective in promoting seaweed beds and attracting fish and shellfish. Iron content has the effect of creating microbial colonies, attracting algae spores, and collecting fish and shellfish, and activating the habitat of living things.

0004

[Problems to be Solved by the Invention] The above-mentioned coating agents that have already been proposed and put into practical use include water-soluble acrylic resin, ferrous sulfate, ferric sulfate, manganese sulfate, or sulfuric acid and iron oxide powder or manganese sulfate. However, there were the following problems.

■ Directly mixing ferrous sulfate with emulsion resin such as acrylic will cause destruction of the emulsion resin as ferrous sulfate exhibits strong acidity in water, leaving bare holes in the painted surface. increases, and alkali elution cannot be prevented.

[0006] Furthermore, as ferrous sulfate destroys the emulsion resin, its adhesive strength on the concrete surface becomes weaker, and the microbial attracting effect becomes shorter.

[0007] In addition, with regard to compounds other than ferrous sulfate, the adhesion to concrete deteriorates over time and deterioration occurs due to inappropriate combinations of compounding ratios and specific materials used. There was a problem.

The present invention has been made in view of the above points, and can effectively prevent alkali elution from concrete structures, reduce deterioration of concrete structures,
Another object of the present invention is to provide a composition for coating concrete structures that can effectively exhibit the microbial attracting effect.

[0009]Specifically, 1) finding a resin that penetrates and adheres to concrete and has little deterioration in water, 2) stably fixing the iron component in the resin, and 2) making it easy to use as a one-component type. By doing so, we can effectively stop alkali leaching from concrete, allow iron to exist, create a natural environment that is the original purpose, activate the ecosystem of living things, and also reduce the coating work. Its purpose is to facilitate.

[0010] The present invention does not completely block alkaline elution from concrete, but rather permanently keeps the surface of concrete structures at pH 9.0 or lower so as not to affect microorganisms and disturb the microbial ecosystem. It was made so that it could be maintained.

[0011]

[Means for Solving the Problems] The composition for coating concrete structures according to the present invention contains an emulsion resin, iron and/or an iron compound, and, if the iron compound is acidic, a neutralizing agent. At least it was configured. Further, an inorganic extender pigment may be mixed with the iron component.

[0012] The mixing ratio of each of the above components is preferably such that the total amount of iron and/or iron compound, neutralizing agent and inorganic extender pigment is 100 to 200 parts by weight per 100 parts by weight of the emulsion resin.

[0013] When the total amount of iron compounds, etc. is less than 100 parts by weight, the degree of film formation by the emulsion resin becomes strong and the alkali blocking effect is improved, but blisters are likely to occur in the coating film, and the blisters eventually Causes paint film to peel. Conversely, when the total amount of iron compounds, etc. is more than 200 parts by weight,
Many holes are formed in the film, and the alkali blocking effect is poor.
Alkaline elution increases.

[0014] The iron compounds used in the present invention include iron (II) sulfate (III), iron (II) sulfide (II), and iron (II) sulfide (II).
I), iron (II) oxide (III), iron (II) nitrate (I
iron(II)(III) hydroxide, iron(II)(III) hydroxide, iron carbide, iron(II)(III) carbonate, iron nitride, ammonium iron(III) sulfate, iron(II)(III) fluoride, iron halide(
Examples include iron(II)(III), iron(II)(III) phosphate, iron(II)(III) phosphate, rhodanic iron, and organic iron.

[0015] Examples of neutralizing agents for acidic iron compounds include calcium hydroxide (slaked lime) and calcium oxide (quicklime).
, cement powder, cement hardened powder, caustic soda,
There are low-cost products such as caustic potash, ammonia, and amines. That is, when ferrous sulfate, which is easy to produce, is used as the iron component, its pH value is 2.4, so it is neutralized with a neutralizing agent such as calcium hydroxide, and the pH is in the range of 7 to 9. In other words, it adjusts the pH to a safe range even when added to emulsion resins.

[0016] Inorganic extender pigments used in combination with the iron component include:
Non-polluting, colorless or white kaolin is preferable, and naturally produced finely powdered kaolin (Al2O3・2SiO2・
2H2O), talc [Mg3H2・(SiO3)4.3
MgO・4SiO2・H2O], barium sulfate (BaS
O4), barium carbonate (BaCO3), calcium carbonate (CaCO3), Mikageite powder, marble, etc. In addition, white pigments such as zinc white and titanium oxide can also be used.

[0017] Emulsion resins are mainly commercially available for cement mixing and mortar, with a minimum film-forming temperature of 15°C or less and saponification value of 20% or less, such as acrylic,
Examples include acrylic/styrene copolymer, vinyl acetate/beova copolymer, urethane (one-component type), and epoxy (one-component type). Emulsion resins prevent water from penetrating into concrete and also prevent alkali from leaching out of concrete, but there are concerns regarding safety during storage, handling, and work on land, and measures against volatile organic compounds. Therefore, we selected a water-soluble emulsion resin.

[0018]

[Operation] As described above, the composition for coating concrete structures according to the present invention is composed of a selected emulsion resin mixed with an iron component and, in some cases, a neutralizing agent and an inorganic extender pigment in a specific ratio. Therefore, even if this is applied to a concrete structure and immersed in water, no blistering, peeling, or cracking will occur, and holes will not easily form in the coating, reducing the amount of alkali leached from the concrete structure to a very small amount. . As a result, the effect of attracting microorganisms to iron can be enhanced without disturbing the microbial ecosystem around the concrete structure. This effect continues continuously.

[0019]

EXAMPLES Examples of the present invention will be described in detail below.

FIG. 1 is a diagram showing the blending composition and blending ratio (% by weight) of the first to sixth embodiments according to the present invention. In the figure, the symbols ■ to ■ in the neutralizing agent column indicate the types of neutralizing agents, and their specific components are shown in FIG. Further, the symbols I to V in the emulsion resin column indicate the types of emulsion resins, and their specific components are shown in FIG. The emulsion resin shown in FIG. 1 contains water, and the actual emulsion resin is the heating residue (%) shown in FIG.

As shown in FIG. 1, in Example 1, non-acidic iron oxide (such as Bengara) was used as the iron compound, so no neutralizing agent was used. On the other hand, in Examples 2 to 6, ferrous sulfate/7 water, which is acidic, was used as the iron compound, so a neutralizing agent was used.

In any of the examples shown in FIG. 1, iron oxide (or ferrous sulfate/7 water), a neutralizing agent, and an inorganic substance were added to 100 parts by weight of the emulsion resin excluding water. Part by weight including pigment (kaolin) is 100~
It is blended within a range of 200 parts by weight.

Next, the method of blending the components constituting each of Examples 1 to 6 will be explained in order.

[1] When using an iron compound that does not show acidity (in the case of Example 1), after adding water and polycarboxylic acid sodium salt to the iron compound and mixing, grind the iron compound with a particle size of 30 μm or less using a sand grind mill. (JIS-K-5400
4.7.2 String method). Note that the polycarboxylic acid sodium salt is a dispersant here.

On the other hand, when using an iron compound exhibiting acidity (in the case of Examples 2 to 6), a neutralizing agent and a small amount of water are added to the iron compound, thoroughly kneaded with a stirrer, and a glass electrode hydrogen ion concentration meter is used. After adjusting the pH to 7 to 9, add fine powder of inorganic extender pigment (kaolin), further add water and sodium polycarboxylic acid salt, and use a sand grind mill to reduce the particle size to 30 μm or less. Spread. The product dispersed as described above is hereinafter referred to as "milbase".

[2] Next, the emulsion resin is weighed in advance and placed in a mixing tank, and the mill base is added and mixed while stirring the emulsion resin.

[3] The composition for coating concrete structures according to the present invention is completed as described above, but in each of these examples, hydroxypropyl methyl cellulose is further added as a suspending agent to the composition for coating concrete structures. , stirred and mixed.

Next, the inventors of the present invention also produced comparative examples for comparison with each of the above embodiments. FIG. 4 is a diagram showing the blending composition and blending ratio (wt%) of Comparative Examples i to v. In the same figure, the specific components of the neutralizing agent are calcium hydroxide indicated by the symbol ■ shown in FIG. 2, and the specific components of the emulsion resin are the resins in FIG. be.

Next, the method of blending the components constituting each of Comparative Examples i to v will be explained.

First, ferrous sulfate was placed in a container, and water and emulsion resin were added and mixed. Comparative example i is now complete.

In the case of Comparative Examples ii to v, ferrous sulfate 7
After adding a neutralizing agent (calcium hydroxide) and a small amount of water to water and kneading and adjusting the pH to 7 to 9, fine powder of inorganic extender pigment (kaolin) is added, and then water and polycarboxylic acid sodium salt are added. In addition, the particle size is 30μ using a sand grind mill.
m or less (hereinafter referred to as "mil base"). Next, the emulsion resin is weighed in advance and placed in a mixing tank, and the mill base is added and mixed while stirring the emulsion resin. Furthermore, hydroxypropyl methyl cellulose was added to this mixture and mixed with stirring. Comparative Examples ii to v are now completed.

Next, the inventor of the present invention applied the above-mentioned Examples 1 to 6 and Comparative Examples iv to v on concrete blocks, and conducted an alkali elution test and an algae growth evaluation test.

The concrete blocks used in the test are mixed at a ratio of cement/sand/gravel = 1/3/6, and are 30 x 100 x 100 (mm) in size for alkaline measurement, and for seawater immersion (algae). For evaluation of the degree of proliferation of 30 x 260 x 260 (mm) samples with a hole in the center for passing a rope were used, and both were dried for 7 days.

The compositions of Examples 1 to 6 and Comparative Examples iv to V were applied three times with a brush to the concrete blocks for alkali measurement and seawater immersion, respectively, under the following conditions. 1st coat: Apply to a dry film thickness of 20-30 μm, dry for 1 day. 2nd coat:
, 〃3rd time
〃 ,Dried for 5 days

[1] Alkali elution measurement test Two glass rods of 6 mm in diameter were placed in the bottom of a plastic container (depth 60 x 120 x 130 mm), the above-mentioned concrete block for alkali measurement was placed on top of the rods, and 430 cc of tap water was added. inject,
The pH value of the water was measured after being left for 5 days. After measuring the pH value,
The same amount of water was replaced with fresh water, and the water was left to stand for 5 days, and the pH value of the water was measured again. This measurement process is repeated every 5 days, and the degree of alkali elution from the concrete is measured by 1 over time.
Measurements were taken for 2 months.

FIG. 5 is a diagram showing the results of this test. As shown in the figure, in Examples 1 to 6 according to the present invention, the degree of alkali elution was maintained at pH 9.0 or lower for 12 months from the beginning of the test.

[0037] In the case where no composition was applied (the concrete block remained), the pH decreased over time from 13.0 at the beginning of the test, and remained at 11.3 to 5.

In the case of Comparative Example i, the pH value changes to the same as that of the uncoated specimen 5 months after immersion, and thereafter shows the same change over time as that of the uncoated specimen.

Comparative Example ii has a lower pH value than the above-mentioned uncoated Comparative Example i, but since the minimum film forming temperature of the emulsion resin is higher than 15°C (see symbol VI in FIG. 3), the coating film is It becomes hard and there is a gap (fine cracks) between the iron component and the resin.
The amount of alkali elution increases over time, and after 12 months, the pH value becomes approximately 10.6.

Comparative Example iii has a lower pH value than the uncoated Comparative Example i, but since the saponification value of the emulsion resin is high (40%), it is immersed in the alkali of the concrete and the resin is blocked by the alkali. The effect gradually decreases, and after 12 months, the pH value becomes approximately 10.6.

Comparative Example iv is the above-mentioned non-coating, Comparative Example i, i
Although the pH value is lower than those of i, iii, and v, the mixing ratio of (emulsion resin)/(iron compound + neutralizing agent + inorganic extender pigment) was set to 100/80, that is, the ratio of emulsion resin is high. Therefore, although the blocking effect of the resin is great, the blisters become noticeable, and the blisters become holes, and the alkali in the concrete begins to dissolve, and after 12 months, P
The H value increases to about 10.2.

Comparative Example v has a lower pH value than the above-mentioned uncoated Comparative Example i, but the mixing ratio of (emulsion resin)/(iron compound + neutralizing agent + inorganic extender pigment) was 100/25.
Since it was set to 0, that is, the ratio of emulsion resin is low, there are many bare holes, and the alkali of the concrete is eluted.
After 12 months, the pH value will be approximately 10.6.

[2] Algae growth evaluation test Example 1
~6. A rope was tied to a concrete block for seawater immersion coated with the compositions of Comparative Examples iv to iv, and the block was immersed at a depth of 4 m in the sea with a transparency of 5 m, and the degree of algae growth was examined.

FIG. 6 is a diagram showing the state of algae growth when the concrete block was immersed in seawater for one year. As shown in the figure, almost no algae adheres to the unpainted concrete blocks, and about 50% of algae adheres to the concrete blocks of Comparative Examples iv to 6, whereas the concrete blocks of Examples 1 to 6 It was found that algae adhered to all concrete blocks.

[0045] It is said that the ability of fish and shellfish to collect is proportional to the degree of adhesion of algae.

In the above example, a dispersant (polycarboxylic acid sodium salt in the example) and a suspending agent (hydroxypropyl methyl cellulose in the example) were blended, so the composition could be made into one liquid, making it easier to use. This has improved the workability of applying it to concrete structures.

[0047]

Effects of the Invention As explained above in detail, according to the composition for coating concrete structures according to the present invention, iron and/or iron compounds, in some cases, can be added to the selected emulsion resin in a specific proportion. The composition was made by mixing a neutralizing agent and an inorganic extender pigment, so even if it was applied to a concrete structure and immersed in water, it would not cause blistering or peeling.
It has the excellent effect of not causing cracking and reducing alkali elution from concrete structures to a very small amount. As a result, the effect of attracting microorganisms to iron can be enhanced without disturbing the microbial ecosystem around the concrete structure. Furthermore, since the above-mentioned effect persists over time, it also has the effect of preventing deterioration of concrete structures.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the blending composition and blending ratio (% by weight) of the first to sixth examples according to the present invention.

FIG. 2 is a diagram showing specific types of neutralizing agents used in the present invention.

FIG. 3 is a diagram showing specific types of emulsion resins used in the present invention.

[Figure 4] Composite composition and blending ratio (wt%) of Comparative Examples i to v
).

FIG. 5 is a diagram showing the results of an alkali elution measurement test for Examples 1 to 6 and Comparative Examples i to v.

FIG. 6 is a diagram showing the results of algae growth evaluation tests for Examples 1 to 6 and Comparative Examples i to v.

Claims (6)

[Claims] 1. A composition for coating concrete structures, characterized in that it contains an emulsion resin, iron and/or an iron compound, and, if the iron compound is acidic, a neutralizing agent. 2. A composition for coating concrete structures, characterized in that the composition for coating concrete structures according to claim 1 further contains an inorganic extender pigment. 3. The emulsion resin according to claim 1 or 2 is acrylic, or acrylic/styrene copolymer, or vinyl acetate/beova copolymer, which has a minimum film forming temperature of 15° C. or less and saponification value of 20% or less. or urethane (one-component type),
Or a composition for applying to concrete structures characterized by being composed of epoxy (one-component type). 4. The mixing ratio of each component in the composition for coating concrete structures according to claim 1 or 2 is such that the emulsion resin is 100 parts by weight, and the components other than the emulsion resin are combined. A composition for coating concrete structures, characterized in that it contains 100 to 200 parts by weight. 5. A concrete structure, characterized in that the composition for coating a concrete structure according to any one of claims 1 to 4 is applied to the surface of the concrete structure. 6. A method of using a concrete structure, comprising installing the concrete structure according to claim 5 underwater.