JP3306255B2 - Concrete admixture - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a concrete admixture. More specifically, the present invention relates to a concrete admixture intended to improve a temporal decrease in fluidity in a high-temperature region where the concrete temperature exceeds 30 ° C.

[0002]

2. Description of the Related Art
Concrete admixtures used for the purpose of improving the fluidity of the hydraulic composition include naphthalene sulfonic acid formaldehyde condensate (hereinafter referred to as naphthalene), melamine sulfonic acid formaldehyde condensate (hereinafter referred to as melamine), Polycarboxylates (hereinafter referred to as polycarboxylic acids) and the like are used. However, although these admixtures are excellent in fluidity, they have a problem that slump loss (decrease in fluidity with time) is large. In order to improve the slump loss, a method of blending a reactive polymer or a crosslinked polymer with an admixture (Cement Association, Cement Concrete, No. 546. Aug, 1992, p24) is generally known. Some effect is recognized by blending these slump retainers, but concrete temperature is 30 ℃
In the summer season exceeding the above, sufficient slump retention is not shown, and countermeasures are desired.

[0003]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to improve the above-mentioned problems. As a result, the admixture base itself has a slump-retaining function, and the oxycarboxylic acid or its salt, sugar, etc. By using together at least one compound selected from the group consisting of sugar alcohols and sugar alcohols, an admixture having extremely excellent slump retention even in a high temperature region has been completed.

That is, the conventional admixture has no dispersion holding property in the base itself, and it is necessary to incorporate a slump holding agent. This slump retainer is hydrolyzed by the alkali in the cement to become a dispersant and exhibits an effect of preventing a decrease in fluidity.However, when the temperature becomes high, the slump retainer is hydrolyzed at an early stage,
It no longer functions as a slump retainer.

Therefore, an admixture having a slump holding function, which prevents aggregation over time as in the present invention, is effective.
Furthermore, the combined use of one or more compounds selected from the group consisting of oxycarboxylic acids or salts thereof, sugars and sugar alcohols further enhances the slump holding function. In general, saccharides are known as retarders, have no dispersing action, and do not exhibit a function as a slump retainer. However, they have found that the combined use with the base of the present invention synergistically enhances the slump retention in a high temperature range.

That is, the present invention is a concrete admixture comprising the following components (a) and (b): Component (a): a monomer (a) represented by the following general formula (A) and one or more monomers selected from the compounds represented by the following general formulas (B) and (C) A copolymer obtained by polymerizing the compound (b). (B) Component: at least one compound selected from the group consisting of oxycarboxylic acids or salts thereof, sugars and sugar alcohols.

[0007]

Embedded image

(Wherein, R ₁ , R ₂ ; hydrogen or a methyl group; m ₁ : number of 0 to 2 AO: oxyalkylene group having 2 to 3 carbons n: number of 50 to 300 X: hydrogen or 1 carbon atom Represents an alkyl group of (1) to (3).

[0009]

Embedded image

Wherein R _{3 to} R _{5 are} hydrogen, a methyl group or
(CH ₂ ) _m2 COOM ₂ R ₆ ; hydrogen or methyl group M ₁ , M ₂ , Y: hydrogen, alkali metal, alkaline earth metal, ammonium, alkyl ammonium or substituted alkyl ammonium m ₂ : represents the number of 0 to 2 . )

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The concrete admixture of the present invention will be described below in detail. The component (A) of the present invention is a water-soluble vinyl copolymer having an oxyalkylene group,
In this structure, as a result of various studies on the chain length and dispersibility (fluidization performance) and slump retention of the polyalkylene glycol, by using the copolymer having the chain length of the specific region and the component (b), The dispersibility at high temperatures and the slump retention are enhanced.

That is, when the average number of moles of the oxyalkylene group in the general formula (A) is in the range of 50 to 300, the dispersibility and the slump retention are excellent, and the range of 100 to 200 is more excellent. The range is very good.

The average number of moles of the added oxyalkylene group is 50
If it is less than 300, the slump retention tends to decrease, and if it exceeds 300, the dispersibility and the slump retention tend to decrease.

In the copolymer (A) used in the present invention, the monomers represented by the general formula (A) include methoxypolyethylene glycol, methoxypolyethylenepolypropylene glycol, methoxypolypropyleneglycol, ethoxypolyethyleneglycol and ethoxypolyethylenepolypropylene. Glycol, ethoxy polypropylene glycol, propoxy polyethylene glycol,
Esterified products of polyalkylene glycol having one end-blocked alkyl such as propoxy polyethylene polypropylene glycol and propoxy polypropylene glycol and acrylic acid or methacrylic acid, or ethylene oxide or propylene oxide adducts of acrylic acid or methacrylic acid are used. The average number of moles of polyalkylene glycol added is 110 to 300, and any of ethylene oxide and propylene oxide adducts can be used in any of random addition, block addition, and alternate addition.

Further, examples of the monomer represented by the general formula (B) include acrylic acid, methacrylic acid, crotonic acid and metal salts thereof. Further, as the unsaturated dicarboxylic acid monomer, maleic anhydride, maleic acid, itaconic anhydride, itaconic acid, citraconic anhydride, citraconic acid, fumaric acid, or an alkali metal salt, an alkaline earth metal salt thereof, Ammonium salts, amine salts, substituted amine salts are used.

As the monomer represented by the general formula (C), allyl sulfonic acid, methallyl sulfonic acid, or an alkali metal salt, an alkaline earth metal salt, an ammonium salt, or an amine salt thereof are used. .

In the present invention, the reaction units of the monomers (a) and (b) constituting the copolymer (a) are monomer (a) / monomer (b) = 1/100 to 100 / A range of 100 (molar ratio) is preferred, and a range of 5/100 to 50/100 is particularly excellent in fluidity and slump retention. When the above molar ratio is less than 1/100 or more than 100/100, the dispersibility and the slump retention tend to decrease.

The copolymer (a) of the present invention can be produced by a known method. For example, JP-A-59-16216
No. 3, Tokuhei 2-15442, Tokuhei 2-7901, Tokuhei 2-78
No. 97, and the like.

Solvents used in the solvent polymerization method include:
Examples include water, methyl alcohol, ethyl alcohol, isopropyl alcohol, benzene, toluene, xylene, cyclohexane, n-hexane, aliphatic hydrocarbon, ethyl acetate, acetone, methyl ethyl ketone, and the like. Water and primary to quaternary alcohols are preferred from the viewpoint of handling and reaction equipment.

As the aqueous polymerization initiator, a water-soluble initiator such as ammonium or alkali metal persulfate or hydrogen peroxide is used. Benzoyl peroxide, lauroyl peroxide or the like is used as a polymerization initiator in solvent polymerization using a solvent other than an aqueous solvent.

It is also possible to use sodium hydrogen sulfite, mercaptoethanol or an amine compound as a promoter in combination with the polymerization initiator, and these polymerization initiators or promoters can be appropriately selected and used. .

The weight average molecular weight (gel permeation chromatography / polystyrene sulfonic acid conversion) of the copolymer (a) is preferably in the range of 3,000 to 500,000,
More preferably, it is from 100 to 100,000. If the molecular weight is too large, the dispersibility tends to decrease, while if the molecular weight is too small, the slump retention tends to decrease.

Further, the copolymer (a) of the present invention
May be reacted with another copolymerizable monomer as long as the effects of the present invention are not impaired. For example, acrylonitrile, acrylate, acrylamide, methacrylamide, styrene, styrenesulfonic acid and the like can be mentioned.

The oxycarboxylic acid of the component (b) in the present invention includes gluconic acid, glucoheptonic acid, arabonic acid, malic acid and citric acid. These salts include, for example, inorganic or organic salts such as sodium, potassium, calcium, magnesium, ammonium, and triethanolamine. Further, as the sugar, glucose, fructose, galactose, saccharose, xylose, abitose, repose, monosaccharides such as isomerized sugars, disaccharides, oligosaccharides such as trisaccharides, or oligosaccharides such as dextrin, or dextran and the like And polysaccharides. Also, molasses containing these are included. Further, examples of the sugar alcohol include sorbitol.

In the present invention, the compounding ratio of (a) and (b) is (a) / (b) = 100/1 to 100/50 in terms of solid content weight ratio.
Is preferable, and the range of 100/3 to 100/40 is particularly preferable. If the compounding ratio of (a) and (b) is less than 100/1, sufficient slump retention will not be exhibited, and if the compounding ratio of (a) and (b) exceeds 100/50, concrete hardening will be delayed. Is not preferred.

The addition amount of the components (a) and (b) of the present invention to concrete is about 0.1 to 3.0% by weight in total of the components (a) and (b) based on the solid content of the cement. 0.2-0.5% by weight is preferably used.

When the components (a) and (b) of the present invention are added, a mixture of (a) and (b) may be added in advance, or they may be added separately. Not something.

In using the concrete admixture of the present invention, it is possible to use the concrete admixture together with another dispersant.

The dispersing agent may be any one which is generally used as an admixture for concrete, and may be a naphthalene sulfonate formaldehyde condensate, a melamine sulfonate formaldehyde condensate, a polycarboxylic acid or an ester thereof or a salt thereof. , Purified lignin sulfonic acid or a salt thereof, polystyrene sulfonic acid, a cement dispersant having a phenol skeleton (for example, formaldehyde co-condensate with another monomer copolymerizable with phenol sulfonic acid), and aniline sulfonic acid. What is conventionally called a high-performance water reducing agent such as a cement dispersant (for example, a formaldehyde co-condensate with another monomer capable of co-condensing aniline sulfonic acid) as a component is preferably used.

The concrete admixture of the present invention is used for a hydraulic composition such as cement for civil engineering, construction, and secondary products, and is not particularly limited.

The concrete admixture of the present invention can be used in combination with known additives (materials). Examples include an AE agent, an AE water reducing agent, a superplasticizer, a high performance water reducing agent, a retarder, a quick strengthener, an accelerator, a foaming agent, a foaming agent, a water retention agent, a thickener, a waterproofing agent, and a defoaming agent. And water-soluble polymers, defoamers, surfactants, etc., cement paste mortar, various cements constituting concrete, blast furnace slag, fly ash, hydraulic compositions using silica fume, and the like.

[0032]

EXAMPLES Hereinafter, the present invention will be described specifically, but the present invention is not limited to these examples.

The weight average molecular weight of the copolymer (a) shown in the examples is determined from the molecular weight by gel permeation chromatography / sodium polystyrene sulfonate.

<Production Example of Copolymer (A)> The contents and symbols of the monomer (a) used in the polymerization of the present invention are shown below. However, EO represents ethylene oxide and PO represents propylene oxide. A-1 Methanol EO / methacrylic acid monoester (EO
A-2 Methanol EO / acrylic acid monoester (EO added mole = 90) A-3 Methanol EO / methacrylic acid monoester (EO)
A-4 Methanol EO / methacrylic acid monoester (EO)
A-5 Acrylic acid PO / EO block adduct (PO added mol = 10, EO added mol = 180) A-6 Acrylic acid EO / PO adduct (EO added mol = 135)
, PO addition mole number = 25) A-7 Methanol EO / methacrylic acid monoester (EO
A-8 (comparative) methanol EO / methacrylic acid monoester (EO added mole = 350) A-9 (comparative) methanol EO / methacrylic acid monoester (EO added mole = 23) The production example of the copolymer (a) is shown. Production Example 1 (Symbol a-1 of Example) 10 mol of water was charged into a reaction vessel equipped with a stirrer, the atmosphere was replaced with nitrogen while stirring, and the temperature was raised to 75 ° C. in a nitrogen atmosphere. A-1
0.30 mol, 1 mol of methacrylic acid (molar ratio = 30/100),
7.5 mol of water mixed and dissolved, 0.01 mol of a 20% ammonium persulfate aqueous solution, and 3 g of 2-mercaptoethanol
Are simultaneously dropped into the reaction system over 2 hours. Next, 0.03 mol of a 20% ammonium persulfate aqueous solution is added dropwise over 30 minutes, and the mixture is aged at the same temperature (75 ° C.) for 1 hour. After aging, the temperature is raised to 95 ° C., 15 g of 35% hydrogen peroxide is added dropwise over 1 hour, and aging is performed at the same temperature (95 ° C.) for 2 hours. After aging, 0.7 mol of 48% sodium hydroxide was added for neutralization to obtain a copolymer having a molecular weight of 35,000.

Production Example 2 (Symbol a-2 of Example) 15 mol of water was charged into a reaction vessel equipped with a stirrer, and the atmosphere was replaced with nitrogen while stirring, and the temperature was raised to 75 ° C. in a nitrogen atmosphere. A-2
0.20 mol, 1 mol of acrylic acid (molar ratio = 20/100), water
A mixture of 15 moles, 0.01 mole of a 20% aqueous solution of ammonium persulfate, and 4 g of 2-mercaptoethanol
Are simultaneously added dropwise to the reaction system over 2 hours. Next, 0.03 mol of a 20% ammonium persulfate aqueous solution is added dropwise over 30 minutes, and the mixture is aged at the same temperature (75 ° C.) for 1 hour. 95 ℃ after aging
Then, 12 g of 35% hydrogen peroxide was added dropwise over 1 hour, and the mixture was aged at the same temperature (95 ° C.) for 2 hours. After aging,
Neutralized by adding 0.7 mol of 48% sodium hydroxide, molecular weight 4
5,000 copolymers were obtained.

Production Example 3 (Symbol a-3 in the example) 15 mol of water was charged into a reaction vessel equipped with a stirrer, and the atmosphere was replaced with nitrogen while stirring, and the temperature was raised to 75 ° C in a nitrogen atmosphere. A-3
0.35 mol, methacrylic acid 1 mol (molar ratio = 35/100),
A mixture of 15 mol of water, 0.01 mol of a 20% aqueous solution of ammonium persulfate, and 4 g of 2-mercaptoethanol were simultaneously added dropwise to the reaction system over 2 hours.
Next, 0.03 mol of a 20% ammonium persulfate aqueous solution is added dropwise over 30 minutes, and the mixture is aged at the same temperature (75 ° C.) for 1 hour. 95 after aging
The temperature was raised to 12 ° C, 12 g of 35% hydrogen peroxide was added dropwise over 1 hour, and the mixture was aged at the same temperature (95 ° C) for 2 hours. After aging, 48
Neutralized by adding 0.7 mol of sodium hydroxide, molecular weight 45,0
Thus, a copolymer No. 00 was obtained.

Production Example 4 (Symbol A-4 of the Example) 10 mol of water was charged into a reaction vessel equipped with a stirrer, the atmosphere was replaced with nitrogen while stirring, and the temperature was raised to 75 ° C. in a nitrogen atmosphere. A-4
0.1 mol, 0.9 mol of acrylic acid, 0.1 mol of sodium methallylsulfonate (molar ratio = 10/90/10), 7.5 mol of water mixed and dissolved, and 20% ammonium persulfate aqueous solution.
01 mol and 4 g of 2-mercaptoethanol are simultaneously added dropwise to the reaction system over 2 hours. Then 20%
An aqueous solution of ammonium persulfate is added dropwise at 0.03 mol over 30 minutes, and the mixture is aged at the same temperature (75 ° C.) for 1 hour. After aging, the temperature was raised to 95 ° C, and 12 g of 35% hydrogen peroxide was added dropwise over 1 hour.
Aged at the same temperature (95 ° C) for hours. After aging, 0.6 mol of 48% sodium hydroxide was added for neutralization to obtain a copolymer having a molecular weight of 45,000.

Production Example 5 (Symbol a-5 in the example) 15 mol of water was charged into a reaction vessel equipped with a stirrer, the atmosphere was replaced with nitrogen while stirring, and the temperature was raised to 75 ° C in a nitrogen atmosphere. A-5
0.05 mol, 1 mol of methacrylic acid (molar ratio = 5/100),
A mixture of 15 mol of water, 0.01 mol of a 20% aqueous solution of ammonium persulfate, and 1 g of 2-mercaptoethanol were simultaneously added dropwise to the reaction system over 2 hours.
Next, 0.03 mol of a 20% ammonium persulfate aqueous solution is added dropwise over 30 minutes, and the mixture is aged at the same temperature (75 ° C.) for 1 hour. 95 after aging
The temperature was raised to 5 ° C., 5 g of 35% hydrogen peroxide was added dropwise over 1 hour, and the mixture was aged at the same temperature (95 ° C.) for 2 hours. After aging, 48
Neutralized by adding 0.7 mol of sodium hydroxide, molecular weight 47,0
Thus, a copolymer No. 00 was obtained.

Production Example 6 (Symbol a-6 in the example) 10 mol of water was charged into a reaction vessel equipped with a stirrer, the atmosphere was replaced with nitrogen while stirring, and the temperature was raised to 95 ° C in a nitrogen atmosphere. A-6
0.05 mol, maleic acid monosodium salt 1 mol (molar ratio = 5/100), 90 ° C hot water 15 mol mixed and dissolved
3% of a 0.01% aqueous solution of ammonium persulfate and 3 g of 2-mercaptoethanol were simultaneously added to the reaction system.
Drip over time. Next, 0.03 mol of a 20% ammonium persulfate aqueous solution is added dropwise over 30 minutes, and the same temperature (95 ° C) for 1 hour
And mature. After aging, 9 g of 35% hydrogen peroxide is added dropwise at 95 ° C. over 1 hour, and aging is performed at the same temperature (95 ° C.) for 2 hours. After aging, add 0.7 mol of 48% sodium hydroxide to neutralize,
A copolymer having a molecular weight of 13,000 was obtained.

Production Example 7 (Example symbol a-7) 8 mol of water was charged into a reaction vessel equipped with a stirrer, the atmosphere was replaced with nitrogen while stirring, and the temperature was raised to 75 ° C in a nitrogen atmosphere. A-7
0.30 mol, 1 mol of methacrylic acid (molar ratio = 30/100),
A mixture of 8 mol of water and 0.01 mol of a 20% aqueous solution of ammonium persulfate and 3 g of 2-mercaptoethanol
Are simultaneously added dropwise to the reaction system over 2 hours. Next, 0.03 mol of a 20% ammonium persulfate aqueous solution is added dropwise over 30 minutes, and the mixture is aged at the same temperature (75 ° C.) for 1 hour. 95 ℃ after aging
, And 15 g of 35% hydrogen peroxide was added dropwise over 1 hour.
Aged at the same temperature (95 ° C) for 2 hours. After aging, 48%
Neutralized by adding 0.7 mol of sodium hydroxide, molecular weight 35,000
Was obtained.

Production Example 8 (Comparative Example A) A reaction vessel equipped with a stirrer was charged with 10 mol of water, the atmosphere was replaced with nitrogen while stirring, and the temperature was raised to 75 ° C. in a nitrogen atmosphere. A-8
0.05 mol, acrylic acid 1 mol (molar ratio = 5/100), water
A mixture of 7.5 moles, 0.01 mole of a 20% aqueous ammonium persulfate solution, and 3 g of 2-mercaptoethanol are simultaneously added dropwise to the reaction system over 2 hours.
Next, 0.03 mol of a 20% ammonium persulfate aqueous solution is added dropwise over 30 minutes, and the mixture is aged at the same temperature (75 ° C.) for 1 hour. 95 after aging
The temperature was raised to 10 ° C., 10 g of 35% hydrogen peroxide was added dropwise over 1 hour, and the mixture was aged at the same temperature (95 ° C.) for 2 hours. After aging, 48
Neutralized by adding 0.7 mole of sodium hydroxide, molecular weight 31,0
Thus, a copolymer No. 00 was obtained.

Production Example 9 (Comparative Example A-9) (Comparative) Five moles of water were charged into a reaction vessel equipped with a stirrer, the atmosphere was replaced with nitrogen while stirring, and the temperature was raised to 75 ° C. in a nitrogen atmosphere. A-9
0.30 mol, 1 mol of methacrylic acid (molar ratio = 30/100),
A mixture of 5 mol of water, 0.01 mol of a 20% aqueous solution of ammonium persulfate and 2 g of 2-mercaptoethanol are simultaneously dropped into the reaction system over 2 hours.
Next, 0.03 mol of a 20% ammonium persulfate aqueous solution is added dropwise over 30 minutes, and the mixture is aged at the same temperature (75 ° C.) for 1 hour. 95 after aging
The temperature was raised to 10 ° C., 10 g of 35% hydrogen peroxide was added dropwise over 1 hour, and the mixture was aged at the same temperature (95 ° C.) for 2 hours. After aging, 48
Neutralized by adding 0.7 mol of sodium hydroxide, molecular weight 32,0
Thus, a copolymer No. 00 was obtained.

The contents and symbols of the comparative admixtures used in the examples, in addition to the comparative copolymers, are shown below. Symbol NS: Naphthalene-based admixture (Mighty 150; manufactured by Kao Corporation).

Table 1 shows the contents and symbols of the compound (b) used in the examples.

[0045]

[Table 1]

<Evaluation as a concrete admixture> Table 2 shows the mixing conditions of concrete.

[0047]

[Table 2]

For the production of concrete, a concrete material and a concrete admixture shown in Table 2 were mixed in a tilting mixer at 25 rp.
It was adjusted by kneading mx 3 minutes. After measuring the slump value,
The sample was further rotated at 4 rpm for 60 minutes, and the slump value after 60 minutes was measured. Concrete temperature was 32 ° C. The amount of the admixture added was such that the initial slump value was 20 ± 1 cm. Slump value was measured by JIS-A1101 method. The curing speed was determined by collecting mortar in concrete and measuring the termination time by the ASTM-C403 method. Table 3 shows the measurement results.

[0049]

[Table 3]

<Evaluation Results> As shown in Table 3, the concrete admixture of the present invention can obtain fluidity with a small amount of addition as compared with the comparative product, and the difference between the slump value immediately after and 60 minutes after is small. That is, it exhibits an excellent water reducing effect and a remarkable effect on slump loss prevention.

[0051]

When the concrete admixture according to the present invention is added to a cement composition, there is no slump loss even at a high temperature in summer, so that a transportation trouble by pumping is eliminated. Furthermore, the concrete admixture according to the present invention improves the fluidity of the cement composition, thereby facilitating the work of filling the form, and the concrete admixture according to the present invention has a large water reducing effect, so that the concrete admixture can be used for high-strength concrete. Application of is also expected.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-8-12398 (JP, A) JP-A-7-187842 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C04B 24/26

Claims (9)

(57) [Claims] 1. A concrete admixture essentially comprising the following components (a) and (b): Component (i): General formula (A) represented by the monomer (a) and that is represented by the following formula (B) Single-mer (b) co obtained by polymerizing a polymer of the following . (B) Component: at least one compound selected from the group consisting of oxycarboxylic acids or salts thereof, sugars and sugar alcohols. Embedded image (Wherein, R ₁ , R ₂ ; hydrogen or a methyl group; m ₁ : number of 0 to 2 AO: oxyalkylene group having 2 to 3 carbons n: number of 50 to 300 X: hydrogen or 1 to 3 carbon atoms Represents an alkyl group.) (Wherein, R ₃ to R _5; hydrogen, or a methyl group COOM ₂ M _1: hydrogen, an alkali metal, alkaline earth metal, ammonium, alkylammonium or substituted alkylammonium M _2: represents an alkali metal.) 2. The concrete admixture according to claim 1, wherein in the component (a), n in the general formula (A) is a number from 100 to 200. 3. The concrete admixture according to claim 1, wherein in the component (a), n in the general formula (A) is a number from 110 to 150. 4. The reaction unit of the monomers (a) and (b) constituting the copolymer (a) is monomer (a) / monomer (b) = 1/100 to 100/100 The concrete admixture according to any one of claims 1 to 3, which is (molar ratio). 5. The copolymer (a) having a weight average molecular weight of 3,0
The concrete admixture according to any one of claims 1 to 4, wherein the amount is from 00 to 500,000. 6. The concrete admixture according to claim 1, wherein the oxycarboxylic acid is gluconic acid, glucoheptonic acid, arabonic acid, malic acid or citric acid. 7. The concrete admixture according to claim 1, wherein the saccharide is a monosaccharide, an oligosaccharide or a polysaccharide. 8. The concrete admixture according to claim 1, wherein the sugar alcohol is sorbitol. 9. The composition ratio of (a) and (b) is (a) /
The concrete admixture according to any one of claims 1 to 8, wherein (b) = 100/1 to 100/50 (weight ratio of solid content).