JPH11171621A - Production of concrete - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a concrete excellent in promotion of strength of a hardened product at low temperatures by adding a water-soluble vinyl copolymer having a specific composition and a hydroxycarboxylic acid (salt) to a hydraulic cement and hardening the cement at a specified temperature. SOLUTION: A copolymer prepared by copolymerizing a monomer represented by formula [R1 and R2 are each H or methyl group; m1 is 0-2; AO is a 2-3C oxyalkylene group; (n) is 30-300; X is H or a 1-3C alkyl group] with one or more monomers of compounds represented by formulae II and III [R3 to R5 are each H, methyl group or (CH2 )m2 COOM2 ; R6 is H or methyl group; M1 , M2 and Y are each H, an alkali (alkaline earth) metal, ammonium or a (substituted) alkylammonium; m2 is 0-2] in (1/100) to (100/100) molar ratio is compounded with a 4-10C hydroxycarboxylic acid or its salt in (100/1) to (100/50) weight ratio and the resultant composition in an amount of 0.02-3.0 wt.% based on a cement is then added thereto to harden the cement.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing concrete at a low temperature. More particularly, the present invention relates to a method for producing a hardened material such as cement paste, mortar, concrete, and the like, which is excellent in increasing the strength at low temperatures.

[0002]

2. Description of the Related Art
The general theory is that the strength of a hardened concrete body is determined by the water / cement ratio. However, it is thought that the effect of crystal growth accompanying the hydration reaction of cement related to strength is also large,
It is still not fully understood.

[0003] For example, even with the same concrete composition, even under the same curing conditions, a difference in strength often occurs due to the admixture added.

[0004] That is, it is considered that the difference in strength has some influence on the adsorption form of the admixture to the cement and the hydration reaction of the cement.

In any case, it is not preferable to decrease the strength due to the admixture. In particular, it is preferable that the strength at a low temperature required for a long time for hardening be expressed as high as possible, and development of a concrete production method is desired.

[0006]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, have found a method for producing concrete which is superior in the strength at the time of low-temperature curing by using a specific additive. Was.

That is, the present invention is a method for producing concrete, characterized by adding the following components (a) and (b) and curing at a temperature of 30 ° C. or lower.

Component (a): at least one selected from monomers (a) represented by the following general formula (A) and compounds represented by the following general formulas (B) and (C) And a copolymer obtained by polymerizing the monomer (b).

Component (b): an oxycarboxylic acid having a total of 4 to 10 carbon atoms or a salt thereof.

[0010]

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 30 to 300 X: hydrogen or 1 carbon atom Represents an alkyl group of (1) to (3).

[0012]

Embedded image

(Wherein, R _{3 to} R _{5 are} hydrogen, methyl, or
(CH ₂ ) m ₂ 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 : number of 0 to 2 Represent. )

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The concrete production method of the present invention will be described below. The concrete targeted by the present invention uses a hydraulic cement containing cement paste, mortar and the like as a binder, and a hydraulic cement using a cement produced by adding the components (a) and (b) as a binder. It is intended for compositions.

The component (a) is a water-soluble vinyl copolymer having excellent dispersibility, and can be used together with the component (b) to obtain a concrete hardened body having excellent strength at low temperatures. is there.

In the copolymer (A) used in the present invention, the monomer represented by the general formula (A) includes a polyalkylene having one terminal alkyl-blocked, such as methoxypolyethylene glycol, methoxypolypropyleneglycol, or ethoxypolyethylenepolypropyleneglycol. Esterified products of glycol and acrylic acid or methacrylic acid or ethylene oxide or propylene oxide adducts of acrylic acid or methacrylic acid are used. Preferably, it is an esterified product of methoxypolyethylene glycol and acrylic acid or methacrylic acid. The average addition mole number of the polyalkylene glycol is 30 to 300, preferably 100 to 200. When the average addition mole number is 30 or less, or 300 or more, the dispersibility tends to decrease, and the fluidity is expressed in a predetermined water / cement. Sometimes not. For both ethylene oxide and propylene oxide adducts, any of random addition, block addition, alternate addition and the like can be used.

The monomers represented by the general formula (B) include unsaturated monocarboxylic acid monomers such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid,
Unsaturated dicarboxylic acid monomers such as fumaric acid, or alkali metal salts, alkaline earth metal salts, ammonium salts, amine salts, substituted amine salts thereof, preferably acrylic acid, methacrylic acid, or these. It is an alkali metal salt.

Examples of the monomer represented by the general formula (C) include allyl sulfonic acid, methallyl sulfonic acid, and alkali metal salts, alkaline earth metal salts, ammonium salts, and amine salts thereof.

In the present invention, the reaction unit of the monomers (a) and (b) constituting the copolymer (a) is monomer (a) / monomer (b) = 1/100 to 100 / A range of 100 (molar ratio) is preferable, and a range of 5/100 to 50/100 is particularly excellent in fluidity. From the viewpoint of controlling the molecular weight of the copolymer, the monomer (b) is preferably selected from (B) alone, (C) and further (B) alone.

The copolymer (a) of the present invention can be produced by a known method. For example, Japanese Unexamined Patent Publication No.
No. 62163, No. 2-1542, No. 2-7
901 and Japanese Patent Publication No. 2-7897.

For example, in the presence of a polymerization initiator such as ammonium persulfate or hydrogen peroxide in water or a lower alcohol having 1 to 4 carbon atoms, if necessary, sodium bisulfite, mercaptoethanol or the like is added, and 50 to 100 ° C. For 0.5 to 10 hours.

The weight average molecular weight (gel permeation chromatography / polystyrene sulfonic acid) of the copolymer (a) is determined from the viewpoint of dispersibility and slump retention.
The range of 3,000 to 500,000 is good, and 5,000 to 100,000 is more preferable.

Further, the copolymer (A) in the present invention is:
Other copolymerizable monomers may be reacted within a range that does not impair the effects of the present invention. For example, acrylonitrile,
Acrylic ester, acrylamide, methacrylamide, styrene, styrenesulfonic acid and the like can be mentioned.

In the present invention, component (b) has a total carbon number of 4 to
The oxycarboxylic acid of 10 includes gluconic acid, glucoheptonic acid, arabonic acid, malic acid or citric acid, and is preferably gluconic acid. These salts include, for example, inorganic or organic salts such as sodium, potassium, calcium, magnesium, ammonium, and triethanolamine.

In the present invention, the compounding ratio of (a) and (b) is (a) / solid weight ratio in terms of solid content in view of strength development at low temperatures.
(B) = 100/1 to 100/50 is preferable, and 100/5
A range of from 100 to 30 is particularly preferred.

The amount of the admixtures (a) and (b) added to the cement is preferably 0.02 to 3.0% by weight (solid content), more preferably 0.1 to 0.5% by weight.

[0027] The method for producing concrete according to the present invention is carried out at 30 ° C.
Hereinafter, an excellent effect can be obtained by carrying out preferably at 30 to 0 ° C, more preferably at 25 to 5 ° C.

Further, the method of adding the admixture during the production of concrete may be a method of adding it to the mixer at the same time as the concrete material, or a method of adding it to the previously kneaded concrete. The components (ii) and (ii) may be added separately without previously mixing so that the weight ratio of the amounts added falls within the above range, and there is no particular limitation on the method of addition and the timing of addition.

The concrete which is the subject of the present invention is mainly composed of cement, fine aggregate and coarse aggregate, but various admixture materials such as various types of blast furnace slag and fly ash can be used. Further, known additives (materials) can be used in combination. For example, an AE agent, an AE water reducing agent, a high performance water reducing agent, a retarder, an early strength agent, an accelerator, a foaming agent, a foaming agent, an antifoaming agent, a thickener, a waterproofing agent, a foam preventing agent and the like can be mentioned.

[0030]

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. Here, EO represents ethylene oxide, and PO represents propylene oxide.

A-1 (comparative): Methanol EO / methacrylic acid monoester (number of moles of added EO = 23) A-2: Methanol EO / methacrylic acid monoester (number of moles of added EO = 55) A-3: Methanol EO・ Acrylic acid monoester (E
A-4: Methanol EO / methacrylic acid monoester (EO added mole number = 115) A-5: Methanol EO / methacrylic acid monoester (EO added mole number = 135) A-6: Acrylic Acid EO / PO random adduct (EO addition mol = 135, PO addition mol = 25) A-7: Acrylic acid PO / EO block adduct (PO addition mol = 10, EO addition mol = 180) -8 (comparative): methanol EO / methacrylic acid monoester (EO addition mole number = 350) A production example of the copolymer (a) is shown below as an example of the copolymer a-4.

Production Example of Copolymer A-4 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-4
0.35 mol, 1 mol of methacrylic acid (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 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 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 45,00
0 copolymer was obtained.

Table 1 summarizes the composition and molecular weight of the obtained copolymer (a).

[0036]

[Table 1]

The contents and symbols of the comparative admixtures used in addition to the comparative copolymers are shown below.

Symbol NS: naphthalenesulfonic acid (Mighty 150; manufactured by Kao Corporation).

Table 2 shows the contents and symbols of the compound (b) used in the examples.

[0040]

[Table 2]

[0041]

[Table 3]

Concrete Production Method and Method of Measuring Strength Concrete was produced by mixing the materials and additives in a concrete biaxial mixer shown in Table 3 for 90 seconds × 3 minutes.

The fluidity (slump flow value) is 20 ± 1 cm
Was adjusted by the addition amount of the present invention and the comparative admixture so that The initial air volume was adjusted to 4 ± 0.5% with a bubble entrainer (Mighty AE-03: manufactured by Kao Corporation) and an antifoaming agent (Antiform E-20: manufactured by Kao Corporation). The materials were adjusted so that the concrete temperature would be 10 ° C, 20 ° C, 30 ° C, and 33 ° C, and the concrete was manufactured in an environment room at a predetermined temperature.

The concrete strength was measured according to JIS-A1132 method, left at a predetermined temperature for 48 hours, cured in water at 20 ° C., and measured the strength after 28 days.

Method for measuring slump flow value; JIS-A110
According to one law.

Measurement of strength: According to JIS-A1108 method.

The evaluation results are shown in Tables 4 to 7.

[0048]

[Table 4]

[0049]

[Table 5]

[0050]

[Table 6]

[0051]

[Table 7]

[0052]

As is clear from Tables 4 to 7, the concrete produced by the production method of the present invention has a distinctly high concrete strength when cured at a low temperature.

According to the present invention, the phenomenon of reduction in concrete strength at the time of curing at low temperature is solved, so that strength design becomes easy.

Claims (5)

[Claims] 1. A method for producing concrete, comprising adding the following components (a) and (b) and curing at a temperature of 30 ° C. or lower. 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: oxycarboxylic acid having 4 to 10 carbon atoms or a salt thereof. Embedded image (Wherein, R ₁ , R ₂ : hydrogen or methyl group m ₁ : number of 0 to 2 AO: oxyalkylene group having 2 to 3 carbons n: number of 30 to 300 X: hydrogen or 1 to 3 carbon atoms Represents an alkyl group.) (Wherein, R _{3 to} R _{5 are} hydrogen, a methyl group, or (CH ₂ ) m ₂ CO
OM ₂ R ₆ : hydrogen or methyl group M ₁ , M ₂ , Y: hydrogen, alkali metal, alkaline earth metal, ammonium, alkylammonium or substituted alkylammonium m ₂ : represents the number of 0 to 2. ) 2. The method for producing concrete according to claim 1, wherein in the component (a), n in the general formula (A) is a number of 100 to 200. 3. The reaction unit of the monomers (a) and (b) constituting the copolymer (a) is a monomer (a) / (b) =
The weight average molecular weight of the copolymer (a) is 1/100 to 100/100 (molar ratio), and the weight average molecular weight is 3,000 to 500,000.
The method for producing concrete according to the above. 4. The method for producing concrete according to claim 1, wherein the oxycarboxylic acid is gluconic acid. 5. The composition ratio of (a) and (b) is 100/1 to 1
5/100 (solid content weight ratio).
The method for producing concrete according to the above item.