JPH01270547A - Admixture for concrete - Google Patents

Abstract

PURPOSE:To make it possible to keep the target air flow rate for a long period, by using fine particles of resin acid or a bi- or polyvalent metallic complex thereof as an air-entraining agent for concrete. CONSTITUTION:An admixture (air-entraining agent) for concrete obtained by using a water-insoluble or sparingly soluble resin acid or a complex of a polyvalent metal (e.g., Mg, Ba, Zn, Fe or Al) and having 0.05-100mum, preferably 0.05-50mum average particle diameter. The above-mentioned complex is preferably obtained normally by adding a polyvalent metallic hydroxide in an amount of 50-100% based on neutralization equiv. of the resin acid. The amount of the admixture added to the cement is normally 0.001-0.1% based on the cement.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an admixture for cement and mortar concrete, and more specifically, to an air entraining agent (hereinafter referred to as AE agent). relates to an AE agent that can prevent the amount of air in cement, mortar, and concrete from decreasing over time.

[Conventional technology]

By using an AE agent that gives air entrainment properties to cement slurry, mortar, and concrete, it is possible to (1) improve freeze-thaw resistance, (2) improve workability, (3) improve pumpability, and (4) air bubbles. This has the effects of reducing breathing due to increased water holding capacity, and (5) reducing unit water volume. - AE agents used for boat fishing include anionic surfactants such as resin acid Na salts, alkylbenzene sulfonates, alkyl sulfonic acid triethanolamine salts, polyoxyethylene alkyl sulfates, and polyoxyethylene alkyl phenols. There are nonionic activators, etc. In addition, as an air-entraining water reducing agent,
Examples include lignin sulfonate, alkylnaphthalene sulfonic acid formalin condensate salt, and the like. On the other hand, examples of low-foaming water reducers, i.e., water reducers whose air content in concrete is 3% or less when used in normal amounts, include β-naphthalene sulfonic acid formalin high condensate salts, melamine formalin condensate sulfonates, etc. . Normally, the amount of air entrained into concrete by the combined use of an AE agent and a water reducing agent is constant (4±1% according to the standards of the Architectural Institute of Japan), and it is preferable that it not decrease over time.

[Problem to be solved by the invention]

However, the amount of air entrained by conventional AE agents decreases rapidly over time due to factors such as the water-cement ratio of concrete, the mix of concrete, the softness of concrete, and the rate of replacement of cement with flywheel. There were drawbacks.

[Failure to solve the problem]

The present invention has been made to improve the drawbacks of the conventional AE agents mentioned above. Normally, concrete contains 1 to 2% air bubbles even without the use of AE agents;
A chemical agent is used to actively entrain air bubbles. 7. When an anionic surfactant is used as the E agent, the surface tension of the water in the concrete is lowered, so air bubbles are more likely to enter with slight agitation compared to water that does not contain a surfactant. In the surrounding water, the lipophilic groups of the anionic activator are oriented toward the gas side and the hydrophilic groups are oriented toward the water side.

As the amount of the activator added increases, the distance between the molecules becomes closer, the intermolecular attraction becomes stronger, and the bubbles become more stable. However, it is said that when a low-foaming water reducing agent is added to this, it enters between the molecules of the active agent and weakens the intermolecular attraction, making it easier to break the foam. Of course, defoaming may be caused by cement, aggregate, or mixer blades. Furthermore, when the diameter of the entrained bubbles becomes 20 μm or less, the internal pressure of the bubbles increases rapidly, and the bubbles dissolve in water and disappear.

The inventors of the present invention have conducted intensive studies on a method that allows air bubbles to be entrained one after another even if the air bubbles in concrete entrained by the activator disappear.
When a resin acid or a metal complex of a resin acid that is sparingly soluble or water-insoluble in 0 μm water is added to concrete,
It was discovered that the target amount of air could be maintained for a long period of time, and the present invention was completed. In other words, fine particles of resin acids or divalent metal complexes of resin acids are insoluble or poorly soluble in ordinary water, but when added to concrete, they react with alkali ions eluted from the concrete, becoming soluble and gradually It dissolves, lowers the surface tension of the concrete, traps air and turns it into bubbles using the stirring force of the concrete mixer, compensates for the amount of bubbles that have defoamed due to the reasons mentioned above, and stabilizes the amount of air over time.

In the present invention, the metal complex refers to a compound in which a carboxyl group in a resin acid and a polyvalent metal are bonded intramolecularly or intermolecularly to form a poorly water-soluble or insoluble compound. In addition, in the present invention, resin acid is a general term for organic acids that exist free or as Nisdel in natural resins. It is preferable that it be as small as possible. However, if the particles are too small, the surface area of the particles will increase and most of them will dissolve during concrete mixing.
The stability of air volume over time is poor. On the other hand, if the particle size is too large, the surface area of the fine particles will become small, and the amount of air added will be large to obtain the target amount of air, and the entire amount will not dissolve during concrete pouring and undissolved particles will remain, resulting in a decrease in the strength of the concrete. I don't like waking up. From these aspects, the average particle size is 0.0
It needs to be 5 to 100 μm, preferably 0
．． 05 to 50 μm.

As the resin acid used in the present invention, commercially available resin acids can be used as is as long as they have a desired average particle size. If the particle size is too large, it is used after being crushed.

The polyvalent metal used in the production of the polyvalent metal complex of resin acid is a metal with a valence of more than 2, which forms a compound that is insoluble or poorly soluble in water by bonding intramolecularly or intermolecularly with the carboxyl group of the resin acid. You can use anything. The amount added to the resin acid is 50 to 5 of the neutralization equivalent of the resin acid.
00% is desirable. A practical compound is Ca.

Hydroxide compounds of Mg, Ba, Zn, Fe, and Al are generally used, but they may also be used in the form of salts such as carbonic acid, sulfuric acid, nitric acid, or in the form of oxidation. Further, the formation of a polyvalent metal complex of resin acid can be easily carried out by mixing the above-mentioned polyvalent metal compound into an aqueous suspension of resin acid or an aqueous solution of an alkali metal salt of resin acid. At this time, heat treatment is a preferable method from the viewpoint of promoting reaction. Even if everything becomes a polyvalent metal complex due to the reaction between resin acid and polyvalent metal compound,
Furthermore, even if some of the resin is complex and the rest is in the form of a mixture with free resin acid, there is no significant difference in effectiveness in either case. Resin acid fine particles pose no problem when stored as a fine powder, but when stored in a water suspension, they gradually dissolve, and when used as an AE agent, their long-term air retention performance is inferior to that of polyvalent metal complexes. Therefore, in the present invention, it is preferable to use a polyvalent metal complex.

The concrete admixture of the present invention can also be used in combination with other admixtures such as commercially available water reducers, slump loss inhibitors, early strength agents, foaming agents, and antifoaming agents.

The admixture of the present invention can be in the form of powder or water suspension, and can also be blended into cement in advance. It can be added to concrete at any time up to the time of concrete pouring, and its effects are fully demonstrated. When transporting concrete using a fresh concrete mixer truck, it is desirable to provide appropriate agitation. Remixing is also necessary in the case of premixed concrete.

The amount added to cement varies depending on the mix, softness, and type of admixture of concrete, but is usually 0.00 to 0.1% of cement.

〔Example〕

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

Example 1 Hydrocarbon compound 14.6%, rosin derivative compound 27
．． 3%, phenolic compound 58.1% (manufactured by Vercules, USA; VIN SQL Resin) 50
The divalent or trivalent metal compounds shown in Table 1 were added to g, and 900 g of water was added thereto and stirred for 30 seconds using a juice mixer. 200g of this suspension 71 and glass beads (diameter 0.5mm) 500
Sand grinder (manufactured by Igarashi Machine Manufacturing ■; N
o, TSG-6H) container and cool it for 15 minutes.
After the grinding, the glass beads were removed using a filter and the particle size was measured (manufactured by Shimadzu Corporation; sedimentation type particle size distribution analyzer/model 5A-CPa). The obtained suspension is added to concrete, and the change in air content over time,
Slump and compressive strength were measured. The water reducing agent used in combination was β-
Micronized product (average particle size 0.10 μm) of naphthalene sulfonic acid formalin high condensate Ca salt, lower olefin (carbon number 4), and maleic anhydride copolymer (average particle size 0.10 μm) in a solid content ratio of 95:5
It is blended with 0.5 to cement in terms of solid content.
% added. The mixer used was a tilting type mixer, and after mixing the concrete, it was rotated 4 times per minute and stirred for up to 60 minutes.

Vinsol (Na salt of resin acid) was used as a comparative AE agent.
A product sold by Yamasou Chemical Co., Ltd.) was used.

Concrete mix> W/C = 55.5% = 8- 6/A = 5 (1.0% C = 320 kg/m' (Central Portland Cement) Fine aggregate - Monthly coarse aggregate - Takarazuka The crushed stone results are shown in Table 1-11~ As is clear from Table 1, the product of the present invention, which is made by blending a resin acid and a polyvalent metal compound and pulverizing it, can produce the target concrete without reducing the compressive strength of the concrete. Air volume (4±
1%) for a long period of time. In comparison, monovalent metal salts (N
(a) Vinsol, which is an aqueous solution, cannot maintain the target amount of air for a long time, and the product of the present invention
It can be said that it is a drug.

Example 2 The blends of various resin acids and polyvalent metal compounds obtained in Example 1 were heated at 90° C. for 5 hours. About this thing
Changes in air content over time were measured using concrete tests.

The mix of concrete and the test method were the same as in Example 1. The results are shown in Table 2.

The product of the present invention, which is a fine particle made by blending a resin acid and a polyvalent metal compound, pulverizing it, and then heat-treating it, can achieve the target concrete air content (4±.1%) without reducing the compressive strength of concrete. ) is found to be an excellent AE agent that retains for a long time.

Example 3 50 g of the same resin/resin acid as in Example 1 was added with the divalent or trivalent compound shown in Table 3.
A predetermined amount of a metal compound having a valent value (1.2 times the neutralization equivalent of the carboxyl group of the resin acid) was added, stirred at 85°C for 10 hours, and after cooling, an infrared absorption spectrum showed that it had become a metal salt. It was confirmed. Regarding this product, the change in air content over time was measured by a concrete test. The mix of concrete and the test method were the same as in Example 1. Table 3 shows the results.
Shown below.

It can be seen that the atomized polyvalent metal complex of resin acid obtained by heat treatment, which is the product of the present invention, is effective in maintaining the target air content for a long time without reducing the compressive strength of concrete.

Example 4 Hydrocarbon compound 14.8%, rosin derivative compound 27
4% and 58.0% phenolic compounds (
Manufactured by Vercules, USA; VINSOL resin) 50g
900 g of water was added to the mixture and stirred for 30 seconds using a juice mixer. Add 200g of this suspension to a sand grinder (with 500g of glass beads (diameter 0.5mm)
Place the container in a container made by Igarashi Kikai Mfg. (No., TSG-6H) and grind at 1500 rpm without cooling. After grinding, remove the glass beads with a filter and measure the particle size (Made by Shimadzu Mfg.; Sedimentation type particle size distribution measurement. Device/5A-CF2 type)
did. The resulting suspension was added to concrete, and changes in air content over time, slump, and compressive strength were measured.

The water reducing agent used in combination was a combination of β-naphthalene sulfonic acid formalin high condensate Ca salt, lower olefin (carbon number 4), and maleic anhydride copolymer fine particles (average particle size 0.10 μm) in a solid content ratio of 95:5. It was blended, and 0.5% of cement was added in terms of solid content. The mixer used was a tilting type, and after mixing the concrete, it made 4 revolutions per minute and 6
Stir until 0 minutes.

Vinsol (Na salt of resin acid) was used as a comparative AE agent.
A product sold by Yamasou Chemical Co., Ltd.) was used.

<Concrete mix> W/C = 55.7% S/A = 50.0% C = 320 kg/m3 (Central Portland cement) Table 4 shows the results of fine aggregate - period coarse aggregate - crushed stone from Takarazuka As shown in Table 4, the commercially available AE agent Vinsol shows a significant decrease in air content over time immediately after kneading. On the other hand, the product of the present invention has excellent stability over time and is an excellent AE agent that maintains a stability of 4±1%.

Although resin acid fine particles have a high initial air content, it is clear that if a small amount of antifoaming agent is added to these particles, the stability of the bubbles over time becomes even better (Experiment No. 2.3).

When the particle size becomes large (Experiment No. 6), the air amount decreases a little over time, but in this case, by adding a small amount of a commercially available AE agent (Experiment No. 7), the air amount can be further stabilized. It turns out that it is possible to convert

Applicant's agent Kaoru Furutani

Claims (1)

[Claims] 1. Average particle size of 0.05 to 10 that is insoluble or poorly soluble in water.
A concrete admixture containing 0 μm fine particles of resin acid or a divalent or higher valent metal complex of resin acid. 2. The concrete admixture according to claim 1, which contains a water reducing agent.