JP2003252666A - Segregation reducing agent for concrete - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a segregation reducing agent for concrete having a segregation resistibility which does not lose a performance required for high-strength concrete or high-flowing concrete and capable of realizing high-strength and high-durability of a hardened product, rationalization of a work, and a method for producing the concrete. <P>SOLUTION: The segregation reducing agent for the concrete is used together with one or more kinds of chemical admixtures selected from the group consisting of an AE agent, a water reducer, an AE water reducer, a high- performance water reducer, a high-performance AE water reducer and a fluidizing agent. The segregation reducing agent for the concrete contains a copolymer polymerized of a monomer (A) which is an ether of a polyalkylene glycol or its monoalkyl ether and (meth)acrylate or allyl alcohol of 20-80 vol.% with a monomer (B) which is an unsaturated carboxylic acid or its salt of 20-80 vol.%, and whose mean molecular weight is 0.5 million-3 million. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a material separation reducing agent for concrete, more specifically, AE
Additives, water reducing agents, AE water reducing agents, high-performance water reducing agents, high-performance AE water reducing agents, superplasticizers and other chemical admixtures for concrete are added in small amounts to deteriorate fluidity and fluidity retention performance. The present invention relates to a material separation reducing agent for concrete that can prevent the separation of aggregates, the prevention of bleeding, the improvement of filling properties, etc., and can significantly improve the workability, workability, and quality of hardened bodies.

[0002]

2. Description of the Related Art In recent years, the performance of concrete has been rapidly improved along with the demand for higher functionality and higher durability of structures and the demand for rationalization of construction. In order to improve the durability of concrete, it is necessary to reduce the amount of unit water that is generally mixed, minimize voids such as capillary voids, and create uniform and dense concrete without junkers, etc. The standard specifications, concrete standard specifications, etc. also regulate the unit water volume. In addition, in response to demands such as simplification of on-site work such as vibration compaction, improvement of pumping performance, improvement of concrete pouring speed, filling of steel pipes by new construction method, adaptation to densification of reinforcing bars, etc. As shown in, the performance of concrete is improving. Under these circumstances, it is an important issue to satisfy high fluidity and filling property without increasing the amount of water to be blended (unit water amount).

On the other hand, against the background of exhaustion of aggregate resources, high-quality aggregates such as river gravel and sand, crushed stones / sand, marine aggregates, mountainous aggregates, and by-products such as blast furnace slag and disposal have been used. There is no choice but to switch to artificial aggregates made from materials,
In particular, aggregates made of by-products such as blast furnace slag and fly ash and wastes as raw materials have been increasing in use ratio as aggregates from the viewpoint of global environment conservation and resource saving.

However, the material conversion of these aggregates often causes a tendency to go against the high performance of concrete, such as a decrease in fluidity and an increase in the amount of unit water. As described above, the cement admixture plays an increasingly important role in achieving high performance of concrete in the tendency of deterioration of material quality such as aggregate. Conventionally, there are various cement admixtures such as lignin sulfonate, melamine sulfonate formaldehyde salt, naphthalene sulfonate formaldehyde salt, and polycarboxylate for the purpose of reducing water and maintaining fluidity. Cement admixture of mono (meth) acrylic acid ester- (meth) acrylic acid copolymer system (Japanese Patent Publication No. 59-1833).
No. 8) has a particularly high water-reducing effect and fluidity-retaining effect, and its use ratio is increasing, and it is being adopted not only in high-fluidity concrete and high-strength concrete but also in general-purpose concrete.

However, when these cement admixtures are used, the cement composition exhibits high fluidity due to its high dispersion effect, and therefore the workability and fluidity of the concrete composition can be greatly improved. However, when the fluidity of the concrete composition is increased, bleeding and separation of aggregates having a relatively large grain size, mainly coarse aggregates, are likely to occur. Further, when the aggregates are separated, not only the separated aggregates are entangled with each other to impede the filling property, but also homogeneous concrete is not obtained, so that the quality of the resulting hardened product such as strength is unavoidable. In addition, in the ready-mixed concrete factory, due to material fluctuations such as the water ratio of aggregate surface,
Liquidity fluctuations and sudden material separation can also occur.

[0006] For the purpose of suppressing the material separation and mitigating the quality fluctuation due to the material fluctuation, it has been proposed to use a water-soluble polymer thickener as a material separation reducing agent for concrete. As a material separation reducing agent for concrete, a cellulose derivative such as methyl cellulose ether, a synthetic polymer such as polyacrylamide, and a water-soluble polymer such as a natural polysaccharide such as curdlan have been proposed (see, for example, Japanese Patent Application Laid-Open No. S60-18753). 61-72664, JP-A-61-2604
53, JP-A-9-2856).

Furthermore, these conventional material separating and reducing agents for concrete are not sufficient in their separating and reducing ability, and when an amount necessary for suppressing the material separating is added, the fluidity and the fluidity retaining performance are deteriorated with the increase of viscosity, In addition to problems such as delay in setting and reduction in durability of the cured product due to mixing of a large amount of organic matter, there has been a problem of excessive increase in material cost.
As described above, in the conventional technology, the fluidity, the fluidity retention performance,
Concrete that can sufficiently satisfy material separation resistance, which is a performance that is seemingly contradictory to fluidity, without impairing various required performances such as filling property, setting speed, and durability of hardened material. The development of a material separation reducing agent is strongly desired.

[0008]

SUMMARY OF THE INVENTION According to the present invention, by adding a small amount to cement, high strength concrete such as fluidity, fluidity retention performance, filling property, setting rate, durability of hardened material, high fluidity, etc. Provide a material separation reducing agent for concrete that can exhibit sufficient resistance to material separation without impairing the performance required for high-performance concrete, and can realize high strength and durability of hardened material, rationalization of construction, etc. Especially.

[0009]

The present inventor has completed the present invention as a result of intensive research to solve the above-mentioned problems. That is, the present invention provides [1] an AE agent, a water reducing agent, an AE water reducing agent, a high-performance water reducing agent,
One or two selected from high-performance AE water reducing agent and superplasticizer
A material separation reducing agent for concrete, which is also used in combination with concrete containing one or more chemical admixtures for concrete, represented by the following general formula (1) CH ₂ = CR ¹ | (1) X ¹ O (X ² O) nR ² (wherein, R ¹ is hydrogen or a methyl group, X ¹ is —C (═O) — or —C H ₂ —, and X ² has 2 to 4 carbon atoms. The alkylene group of R, R ² is hydrogen or an alkyl group having 1 to 5 carbon atoms, and n is a number of 2 to 100), or one or more monomers (A) ... ··· 20 to 80% by mass, the following general formula (2) CH = CR ⁴ | | ··· (2) R ³ (CH ₂ ) _m COOX ³ (wherein R ³ is a hydrogen atom, a methyl group or -COOX ^4, R ⁴ is a hydrogen atom, a methyl group or -COOX ^5, X ^3, X ⁴ and X ⁵ are hydrogen, an alkali metal Alkaline earth metal, ammonium group or organic amino group, and m represents 0 or 1.) 1 or 2 or more monomers (B) .. The copolymer obtained by copolymerization has a weight-average molecular weight (measured by gel permeation chromatography using pullulan as a standard substance) of 500,000-3.
A material separation reducing agent for concrete, characterized by containing a copolymer of

[2] In the copolymer of the monomer (A) and the monomer (B), the following general formula (3) CH ₂ ═CR ⁵ —CONH—R ⁶ —SO ₃ X ⁶ ... (3) (wherein, R ⁵ is hydrogen or a methyl group, R ⁶ is a linear or branched alkylene group having 1 to 4 carbon atoms, X ⁶
Represents hydrogen, an alkali metal, an ammonium salt, or an organic ammonium salt. 40% by mass or less of one or more kinds of the monomer (C) represented by), and / or the monomer (A), the monomer (B), and a vinyl-based material other than the monomer (C). A copolymer obtained by copolymerizing 30% by mass or less of the monomer (D), having a weight average molecular weight (measured by gel permeation chromatography using pullulan as a standard substance) of 500,000. A material separation reducing agent for concrete according to the above [1], which contains a copolymer of 3 to 3,000,000;

[3] The material separation reducing agent for concrete according to the above [1] or [2], wherein n (the number of moles of alkylene oxide added) of the monomer (A) is 4 to 50, [4] Single amount The concrete according to any one of [1] to [3] above, wherein the body (B) is one or more selected from acrylic acid and / or methacrylic acid and / or salts thereof. Material separation reducing agent, [5] The concrete according to any one of the above [2] to [4], wherein the monomer (C) is 2-acrylamido-2-methyl-propanesulfonic acid and / or a salt thereof. Material separation reducing agent, [6] AE agent, water reducing agent, AE water reducing agent, high performance water reducing agent,
One or two selected from high-performance AE water reducing agent and superplasticizer
For more than one chemical admixture for concrete, the above [1]
An admixture for concrete in which the material separation reducing agent for concrete according to any one of to [5] is mixed,

[7] A monomer mixture comprising 20 to 80% by weight of the monomer (A) and 20 to 80% by weight of the monomer (B) is subjected to aqueous solution polymerization at a monomer concentration of 5 to 20% by weight or A method for producing a material separation-reducing agent for a concrete, which is a copolymer having a weight average molecular weight (measured by gel permeation chromatography using pullulan as a standard substance) of 500,000 to 3,000,000 by aqueous solution polymerization. [8] Water, cement, fine aggregate, coarse aggregate, and AE agent,
A method for producing concrete by kneading one or more chemical admixtures for concrete selected from a water reducing agent, an AE water reducing agent, a high performance water reducing agent, a high performance AE water reducing agent, and a superplasticizer, wherein ] The material separation reducing agent for concrete according to any one of [6] to 20-1,000 per unit mass of cement as a copolymer solid content mass.
a method for producing concrete, characterized by further mixing at a ppm addition rate, [9] water, cement, fine aggregate, coarse aggregate, and AE agent,
A method for producing concrete by kneading one or more chemical admixtures for concrete selected from a water reducing agent, an AE water reducing agent, a high performance water reducing agent, a high performance AE water reducing agent, and a superplasticizer, wherein ]-[6] mix | blending the material separation reducing agent for concrete, and further mix | blending the polyethylene oxide of viscosity average molecular weight 100,000-10,000,000, The manufacturing method of the concrete, and [10] AE agent, water reducing agent, AE water reducing agent, high-performance water reducing agent,
One or two selected from high-performance AE water reducing agent and superplasticizer
For more than one chemical admixture for concrete, the above [1]
The problems described above were solved by developing the material separation reducing agent for concrete according to any one of to [5] and an admixture for concrete containing polyethylene oxide having a viscosity average molecular weight of 10 to 10,000,000.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION A monomer (A) represented by the general formula (1) is used as a raw material of a copolymer used as a material separation reducing agent for concrete of the present invention. Of 2 to 100, preferably 4 to 50, polyethylene glycol, methoxy polyethylene glycol, ethoxy polyethylene glycol, polypropylene glycol, methoxy polypropylene glycol, ethoxy polypropylene glycol, or other polyalkylene glycols or their C 1-5 monoalkyl ethers. , An ester compound with acrylic acid or methacrylic acid, or an addition mole number of 5 to 50
The above-mentioned alkylene glycols or ether compounds of their monoalkyl ethers with allyl alcohol are preferred.

The composition ratio of the monomer (A) in the copolymer of the concrete material separating and reducing agent of the present invention is 20 to 80% by mass, preferably 40 to 70% by mass. When the proportion of the monomer (A) exceeds 80% by mass, the fresh concrete tends not to have sufficient resistance to material separation, and when it is less than 20% by mass, the fluidity and fluidity retention of the fresh concrete are maintained. It tends to impair performance.

Examples of the monomer (B) represented by the general formula (2) used in the present invention include acrylic acid, methacrylic acid, crotonic acid, isocrotonic acid, maleic acid, fumaric acid, itaconic acid or alkalis thereof. Examples thereof include salts of metals or alkaline earth metals, and acrylic acid, methacrylic acid or salts thereof are particularly preferable in terms of performance and cost balance.

In the agent for reducing concrete material separation of the present invention, the composition ratio of the monomer (B) in the copolymer is 2
The amount is 0 to 80% by mass, preferably 30 to 60% by mass.
The ratio of the monomer (B) exceeds 80% by mass, or 2
If it is less than 0% by mass, the fresh concrete tends to have insufficient resistance to material separation.

Examples of the monomer (C) represented by the general formula (3), which is optionally used in the present invention, include:
2-acrylamido-2-methylpropanesulfonic acid,
Examples thereof include acrylamidoalkanesulfonic acids such as 3-methacrylamidopropanesulfonic acid, 2-acrylamidoethanesulfonic acid, and 2-methacrylamidoethanesulfonic acid, and / or salts thereof. Among them, 2-acrylamido-2-methylpropanesulfonic acid. And / or salts thereof are preferred.

In the agent for reducing concrete material separation of the present invention, the composition ratio of the monomer (C) in the copolymer is 40.
It is not more than mass%, preferably not more than 20 mass%. It is not necessary to use the monomer (C), but depending on the type of polymer dispersant used when preparing concrete and the type of aggregate used, material separation can be achieved by using the monomer (C) together. In some cases, the resistance can be increased. If the proportion of the monomer (C) exceeds 40% by mass, the material separation resistance of fresh concrete tends to decrease.

A vinyl-based monomer (D) which can be optionally used in the concrete material separation-reducing agent of the present invention.
As the monomer (A), the monomer (B), the monomer (C)
Other vinyl-based monomers can be mentioned. Usable vinyl monomers (D) are, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, acrylamide, N, N-.
Dimethylacrylamide, N-isopropylacrylamide, diacetoneacrylamide, N-methylolacrylamide, acryloylmorpholine, N-vinylpyrrolidone, acrylonitrile, styrene, α-methylstyrene, p-methylstyrene, styrene dimer, vinyl acetate, methyl vinyl ketone, ethyl. Nonionic monomers such as vinyl ketone, methyl vinyl ether, ethyl vinyl ether, isobutylene, 4 methyl pentene-1, norbornene, allyl alcohol, allyl chloride, N, N-dimethylaminoethyl acrylate, N,
Examples thereof include cationic monomers such as N-dimethylaminopropyl acrylamide or a quaternary ammonium salt thereof. In the present invention, the vinyl monomer (D) does not have to be used as a monomer, but when it is used, it does not lose the water solubility of the copolymer and exceeds 30% by mass. I won't. It is preferably 20% by mass or less. If it exceeds 30% by mass, the performance as the material separation reducing agent for concrete of the present invention cannot be sufficiently exhibited.

The agent for reducing separation of materials for concrete of the present invention is a copolymer obtained by copolymerizing each of the above-mentioned monomers with a weight average molecular weight (measured by gel permeation chromatography using pullulan as a standard substance). Value) is 500,000 to 3,000,000, preferably 1,000,000 to 20
It is in the range of 0,000. When the weight average molecular weight is 500,000 or less, viscosity imparting to fresh concrete becomes insufficient, and when it is 50,000 or less, it is used as a cement dispersant or cement water reducing agent, and the fluidity of fresh cement is greatly improved. However, it is easy to cause aggregate separation. On the other hand, when the weight average molecular weight exceeds 3,000,000, the viscosity is excessively imparted, the dispersibility is lowered, and the fluidity, the fluidity retention performance and the filling property tend to be insufficient.

The addition amount of the material separation reducing agent for concrete of the present invention is in the range of 20 ppm to 1000 ppm in terms of copolymer solids per unit mass of cement, and 50
The range of ppm to 500 ppm is more preferable. 20
If it is less than or equal to ppm, the viscosity of fresh concrete is insufficiently imparted, which tends to cause material separation.
If it exceeds 1000 ppm, the dispersibility will decrease and the fluidity,
The fluidity retention performance and filling property tend to be insufficient.

The material separation reducing agent for concrete of the present invention is water, cement, fine aggregate, coarse aggregate, and AE agent, water reducing agent, AE water reducing agent, high performance water reducing agent, high performance AE water reducing agent,
In the production of concrete containing a chemical admixture for concrete such as superplasticizer, it can exhibit good material separation resistance even when used alone, but by further using polyethylene oxide in combination, higher material separation resistance It is possible to exert the nature. The viscosity average molecular weight of polyethylene oxide used in combination with the concrete material separation-reducing agent of the present invention is in the range of 100,000 to 10,000,000, preferably 1,000,000 to 8,000,000. Viscosity average molecular weight is 1
If it is less than 0,000, the material separation resistance of the fresh concrete tends to be insufficient, and if it exceeds 10 million, the fluidity and flow retention of the fresh concrete tend to be impaired. The addition amount of polyethylene oxide used in combination with the concrete material separation reducing agent of the present invention is not particularly limited, but is preferably equal to or less than the addition amount of the concrete material separation reducing agent of the present invention. If the amount is more than the same amount, the resistance to material separation tends to be rather reduced when added alone. The method of using polyethylene oxide in combination with the concrete material separation reducing agent of the present invention is not particularly limited, and may be powder-mixed with cement during concrete preparation. Alternatively, it may be mixed in advance as an aqueous solution and added to the concrete kneading water as a mixed aqueous solution.

The material separation reducing agent for concrete of the present invention is used by mixing it with a chemical admixture for concrete such as AE agent, water reducing agent, AE water reducing agent, high performance water reducing agent, high performance AE water reducing agent and superplasticizer. can do. In this case, it is possible to impart performance such as suppression of material separation and mitigation of quality fluctuations due to material fluctuations without significantly affecting the various performances of those chemical admixtures for concrete.
It is also effective as an additive to chemical admixtures for concrete. In particular, fresh concrete containing a fluidity-imparting agent such as a water-reducing agent, an AE water-reducing agent, a high-performance water-reducing agent, or a high-performance AE water-reducing agent tends to cause aggregate separation and bleeding due to its high fluidity. In order to prevent this, it is extremely effective to use this material separation reducing agent for concrete together, and it has become possible to prevent aggregate separation and bleeding without deteriorating the fluidity.

The method for producing the copolymer of the present invention is not particularly limited, but aqueous solution polymerization, aqueous solution polymerization which is a hydrophilic organic solvent such as lower alcohol-aqueous system aqueous medium, reverse phase suspension polymerization. The method of carrying out the aqueous solution polymerization or the aqueous solution polymerization at a monomer concentration of 5 to 20% by mass can be used in such a manner that the weight average molecular weight of the copolymer falls within the range of the present invention. It is preferable from the viewpoint of payment.

In the production of the copolymer of the present invention, a polymerization initiator is usually used. As the polymerization initiator, an ordinary radical polymerization initiator can be used, and 2,2′-
Asobis isobutyronitrile, 2,2'-asobis (2
-Amidinopropane) dihydrochloride, 2,2-
Asobis [2- (2-imidazolin-2-yl) propanecodihydrochloride, 2,2'-assobis [2-
(3,4,5,6-Tetrahydropyrimidin-2-yl) propane] dihydrochloride, 2,2'-azobis [2- (5-hydroxy-3,4,5,6-tetrahydropyrimidin-2-yl) ) Propane] azo initiators such as dihydrochloride, hydrogen peroxide, benzoyl peroxide, t-butyl hydroperoxide, peroxide initiators such as succinic acid peroxide, and peroxides such as ammonium persulfate and potassium persulfate. Examples thereof include a sulfate-based initiator, or a so-called redox-based initiator in which a peroxide or a persulfate and a reducing agent such as triethanolamine, sodium sulfite, or sodium thiosulfate are present in the same system.

A chain transfer agent may be used as a molecular weight regulator during polymerization. As a chain transfer agent,
Examples thereof include n-butyl mercaptan, triethylamine, isopropyl alcohol, ammonium thioglycolate, sodium hypophosphite and the like. Separation reducing agent for concrete of the present invention, civil engineering as an aqueous solution or an aqueous solution,
It is used for a hydraulic composition of cement such as construction and secondary products, and is not particularly limited.

Further, the separation reducing agent for concrete of the present invention includes other cement additives (materials) such as retarder, early strengthening agent, accelerator, foaming agent, foaming agent, water retention agent, thickener, It can be used in combination with a waterproofing agent, a defoaming agent, a water-soluble polymer, a surfactant, an expanding agent (material), blast furnace slag, fly ash, silica fume, asbestos, vinylon fiber, PP fiber and the like. For example, a thickening agent such as methyl cellulose or polyacrylamide may be used in combination with the concrete separation reducing agent of the present invention. Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to the examples.

[0028]

Example (Production Example 1) (Production of Copolymer S1) In a glass reactor equipped with a stirrer,
Methoxy polyethylene glycol methacrylate (ethylene glycol addition mole number: 9 moles, "9EG-M
A ") 50 g, sodium acrylate (" AA-N
200 g of a 20% aqueous solution of "a") and sodium 2-acrylamido-2-methylpropanesulfonate ("AM").
20 g of 50% aqueous solution of PS-Na ") was added, and water 718
g was added and dissolved. Then, in a constant temperature water bath under stirring,
After removing dissolved oxygen by aeration with nitrogen while maintaining the temperature at 5 ° C, 1% of 2,2'-azobis (2-amidinopropane) dihydrochloride (V-50 manufactured by Wako Pure Chemical Industries, Ltd.)
12 g of the aqueous solution was added, and the reaction was carried out for 6 hours under aeration of nitrogen to complete the polymerization to obtain a 10% aqueous solution of the copolymer S1. The weight average molecular weight of the obtained copolymer S1 (measured by gel permeation chromatography using pullulan as a standard substance) was 1.52 million.

(Production Examples 2 to 8) (Production of Copolymers S2 to S8) In the same manner as in Production Example 1, the monomer composition shown in Table 1 and 2,2'-azobis (2
-Amidinopropane) dihydrochlorite (manufactured by Wako Pure Chemical Industries, Ltd .: V-50) was produced by changing the addition amount of a 1% aqueous solution to obtain copolymers (S2 to S8). The amount of water was adjusted so that the total concentration of all monomers was 10% by weight and the total amount of the charged V-50 aqueous solution was 1000 g.
The compounding conditions and weight average molecular weight of these monomers and radical polymerization initiators are shown in Table 1 together with Production Example 1.

[0030]

[Table 1]

(Note) 9EG-MA ... Methoxypolyethylene glycol methacrylate (ethylene glycol addition mole number: 9 moles) 23EG-MA ... Methoxypolyethylene glycol methacrylate (ethylene glycol addition mole number: 23 moles) AA-Na ... Acrylic Sodium acid / MA-Na ... Sodium methacrylate / AMPS-Na ... 2-Acrylamido-2-methylpropanesulfonic acid sodium salt / AN ... Acrylonitrile / MAA ... Methyl acrylate

Comparative Production Example 1 (Production of Copolymer R1) In a glass reactor equipped with a stirrer,
The same amount of the same type of monomer as in Production Example 4 was charged, and water 68 was added.
0 g was added and dissolved. Then, in a constant temperature water bath under stirring,
After removing dissolved oxygen by aeration with nitrogen while maintaining the temperature at 0 ° C., 2,2′-azobis (2-amidinopropane) dihydrochloride (manufactured by Wako Pure Chemical Industries, V-50) was used.
% Aqueous solution (50 g) was added, and the reaction was continued for 6 hours under aeration of nitrogen to complete the polymerization to obtain a 10% aqueous solution of copolymer R1. The weight average molecular weight of the obtained copolymer R1 (measured by gel permeation chromatography using pullulan as a standard substance) was 80,000.

(Comparative Production Example 2) (Production of Copolymer R2) In a glass reactor equipped with a stirrer,
The same amount of the same type of monomer as in Production Example 4 was charged, and water 68 was added.
0 g was added and dissolved. Next, dissolved oxygen was removed by aeration with nitrogen while maintaining the temperature at 60 ° C. in a constant temperature water tank under stirring, and then 2,2′-azobis (2-amidinopropane) dihydrochloride (W-50, Wako Pure Chemical Industries, Ltd., V-50 ) Of 10
% Aqueous solution (20 g) was added, and the mixture was reacted for 6 hours under aeration of nitrogen to complete the polymerization to obtain a 10% aqueous solution of copolymer R2. The weight average molecular weight of the obtained copolymer R2 (measured by gel permeation chromatography using pullulan as a standard substance) was 230,000.

Comparative Production Example 3 (Production of Copolymer R3) In a glass reactor equipped with a stirrer,
Add 50 g of acrylamide (AAM), 200 g of 20% aqueous solution of sodium acrylate (AA-Na) and 20 g of 50% aqueous solution of sodium 2-acrylamido-2-methylpropanesulfonate (AMPS-Na), and add water 7
15 g was added and dissolved. Next, the dissolved oxygen was removed by aeration with nitrogen while maintaining the temperature at 45 ° C. in a constant temperature water tank under stirring, and then 2,2′-azobis (2-amidinopropane) dihydrochloride (W-50, Wako Pure Chemical Industries, Ltd., V-50 ) 1
% Aqueous solution (15 g) was added, and the mixture was reacted for 6 hours under aeration of nitrogen to complete the polymerization to obtain a 10% aqueous solution of copolymer R3. The weight average molecular weight (measured by gel permeation chromatography using pullulan as a standard substance) of the obtained copolymer R3 was 1,720,000.

(Comparative Production Example 4) (Production of Copolymer R4) In a glass reactor equipped with a stirrer,
Acrylamide (AAM) 40 g, methyl acrylate (MAA) 10 g, sodium acrylate (AA-N)
200 g of a 20% aqueous solution of a) and 2-acrylamido-
Sodium 2-methylpropanesulfonate (AMPS-
20 g of a 50% aqueous solution of Na) was added, and 720 g of water was added and dissolved. Then, while stirring and maintaining the temperature at 45 ° C in a constant temperature water bath, the dissolved oxygen was removed by nitrogen aeration, and then 2, 2 '
10 g of a 1% aqueous solution of azobis (2-amidinopropane) dihydrochloride (V-50 manufactured by Wako Pure Chemical Industries, Ltd.)
Was added, and the mixture was reacted for 6 hours under aeration of nitrogen to complete the polymerization,
A 10% aqueous solution of copolymer R4 was obtained. Weight average molecular weight of the obtained copolymer R4 (measured by gel permeation chromatography using pullulan as a standard substance)
Was 1.6 million. Table 2 shows the compounding conditions of the monomers and radical polymerization initiators of Comparative Production Examples 1 to 4 and the weight average molecular weights of the copolymers R1 to R4.

[0036]

[Table 2] (Note) ・ AAM: Acrylamide

[Performance Evaluation Test of Material Separation Reducing Agent for Concrete (I)] In order to understand the performance of the synthesized copolymer as a material separation reducing agent for concrete, as a concrete material separation reducing agent during concrete preparation, A performance evaluation test was conducted on the fluidity, self-filling property, and material separation resistance by adding the copolymer. (1) Concrete mix and kneading method Table 3 shows the mix of concrete materials in the concrete mix performance evaluation test (I).

[0038]

[Table 3] 1) Water (W) ... Ion-exchanged water 2) Cement (C) ... Ordinary Poldland cement (specific gravity: 3.19) 3) Fine aggregate (S) ... Sagami River production sand (specific gravity: 2.60) 4) Coarse aggregate (G) ... Sagami River crushed stone (specific gravity: 2.63) * a = S (capacity) + G (capacity)

Kneading method Using a 50 L forced-bread mixer, the amount of material was determined so that the concrete kneading amount was 40 L. First,
Cement, fine aggregate and coarse aggregate were stirred for 30 seconds. Next, an aqueous solution in which a high-performance AE water reducing agent and a material separation reducing agent for concrete were dissolved was added in advance, and after kneading for 45 seconds, the mixer was once stopped. After scraping off the mortar component adhering to the bottom and side surfaces of the mixer and the stirring blade, the mixture was kneaded for 45 seconds and discharged. The powdery material separation reducing agent for concrete (methyl cellulose) was added when the cement was charged.

(2) Performance test method Fluidity test / slump flow test ... “Architectural Institute of Japan JASS5T-
503 ”and was measured immediately after kneading and after 60 minutes.

Self-Filling Test-Using the L-type test apparatus shown in FIG. 1, with the partition plate closed, the left chamber of the partition plate was filled with concrete milk, and the partition plate was fully opened to flow into the right chamber. The filling height of concrete milk was measured. Therefore, it is judged that the higher the filling height (the closer to 20 cm) is, the better the self-filling property can be secured.

Material Separation Resistance Test: The “Coarse Aggregate Washing Test” described in “Materials for High Fluidity Concrete, Mixing, Manufacturing, Construction Guidelines (Draft) and Commentary” of Architectural Institute of Japan was conducted. That is, about 2 kg of fresh concrete after the slump flow test was collected from the central part and the outer peripheral part, and the weight of the coarse aggregate remaining after wet screening with a 5 mm sieve was measured. The ratio of the weight ratio of the coarse aggregate in the central part to the ratio was determined as the ratio of the coarse aggregate to the inner and outer portions. Therefore, it is judged that the closer the inner-outer coarse aggregate ratio is to one, the smaller the difference in coarse aggregate between the central portion and the outer peripheral portion, and the better the material separation resistance.

Others ・ Air volume and bleeding volume are JIS A
1128 and JIS 1123. (3) Performance test results Table 4 shows the performance test results.

[0044]

[Table 4] 1) Polyethylene oxide ... Sumitomo Seika Co., Ltd., P
EO-15 2) High-performance AE water reducing agent ... Polycarboxylic acid ether type [manufactured by NMB Co., Ltd., Rheobuild SP-8N] 3) X ... Methylcellulose [manufactured by Shin-Etsu Chemical Co., Ltd., 90
SH-15000]

[Evaluation Test (II) of "Material Separation Reducer for Concrete 1"] (1) Concrete Mixing and Kneading Method Table 5 shows the basic material mix of concrete in the concrete mixing performance evaluation test (II). (In addition to the composition of Table 5, a test was also conducted on a composition in which water having a water content of 1% of fine aggregate was increased or decreased.)

[0046]

[Table 5] 1) Water (W) ... Ion-exchanged water 2) Cement (C) ... Ordinary Portland cement (specific gravity: 3.19) 3) Limestone fine powder (LP) ... Specific surface area: 3900 cm ²
/ G, specific gravity: 2,674) Aggregate (S) ... Sagamigawa-produced river sand (specific gravity: 2.
60) 5) Coarse aggregate (G) ... Crushed stone from Sagami River (specific gravity: 2.
63) * a = S (capacity) + G (capacity), P = C (weight) + LP
(weight)

The same method as in the kneading method [Performance evaluation test (I) for material separation reducing agent for concrete] was carried out.

(2) Performance test method Flowability test, material separation resistance test, air content measurement, bleeding test,
The same method as in [Performance evaluation test (I) of material separation reducing agent for concrete] was performed. (3) Performance test results Table 6 shows the performance test results.

[0049]

[Table 6] 1) High-performance AE water-reducing agent ... Polycarboxylic acid ether type [Reobuild SP-8N, manufactured by NMB Co., Ltd.] 2) Adjustment of water charge ... "± 0%" is the same as the basic material composition shown in Table 5. And "-1%" and "+1"
% ”Is the amount of water on the surface of fine aggregate relative to the amount of water in the basic material mixture
% Corresponding to the amount (7.24 kg / m ³ ) is shown to be the compounding amount which is respectively reduced and increased.

[0050]

EFFECTS OF THE INVENTION The separation reducing agent for concrete of the present invention has a very small addition amount as compared with the conventional separation reducing agents for concrete, and has a good slump flow value, L-shaped test filling height, and inner and outer coarse bones. Material ratio and bleeding amount are given, and it is possible to impart high aggregate separation resistance, bleeding suppression performance, and filling property to fresh concrete, and it is necessary to obtain sufficient fluidity and fluidity retention. The amount of the cement dispersant such as the high-performance AE water reducing agent can be kept low. Further, it is possible to suppress fluctuations in fluidity of fresh concrete, resistance to material separation, and the like to fluctuations in the water content in concrete mixing. That is, by using the separation reducing agent for concrete of the present invention, at a low chemical cost,
It has become possible to produce concrete with high fluidity, fluidity retention, material separation resistance, and filling.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an L-type test device used for a self-filling property test.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C04B 24/26 C04B 24/26 H 24/32 24/32 A 28/04 28/04 C08F 290/06 C08F 290/06 // C04B 103: 40 C04B 103: 40 103: 44 103: 44

Claims (10)

[Claims] 1. A concrete containing one or more chemical admixtures for concrete selected from an AE agent, a water reducing agent, an AE water reducing agent, a high-performance water reducing agent, a high-performance AE water reducing agent, and a superplasticizer. And a material separation reducing agent for concrete, which is also used in combination, comprising the following general formula (1) CH ₂ = CR ¹ | (1) X ¹ O (X ² O) nR ² (wherein , R ¹ is hydrogen or a methyl group, X ¹ is —C (═O) — or —C H ₂ —, X ² is an alkylene group having 2 to 4 carbon atoms, and R ² is hydrogen or 1 to 4 carbon atoms. The alkyl group of 5, and n is a number of 2 to 100), one or more monomers (A) represented by the formula: 20 to 80% by mass, and the following general formula (2). CH = CR ⁴ | | (2) R ³ (CH ₂ ) _m COOX ³ (where R ³ is a hydrogen atom or methyl A group or —COOX ⁴ , R ⁴ is a hydrogen atom, a methyl group or —COOX ⁵ , X ³ , X ⁴ and X ⁵ is hydrogen, an alkali metal, an alkaline earth metal, an ammonium group or an organic amino group, and m is 0 or 1. A copolymer obtained by copolymerizing 20 to 80% by mass of one or more monomers (B) represented by The molecular weight (measured by gel permeation chromatography using pullulan as a standard substance) is 500,000 to 30.
A material material separation-reducing agent for concrete, which comprises a copolymer of 0,000. 2. In the copolymer of the monomer (A) and the monomer (B), the following general formula (3) CH ₂ ═CR ⁵ —CONH—R ⁶ —SO ₃ X ⁶ ... (3) (wherein, R ⁵ is hydrogen or a methyl group, R ⁶ is a linear or branched alkylene group having 1 to 4 carbon atoms, X ⁶
Represents hydrogen, an alkali metal, an ammonium salt, or an organic ammonium salt. 40% by mass or less of one or more kinds of the monomer (C) represented by), and / or the monomer (A), the monomer (B), and a vinyl-based material other than the monomer (C). A copolymer obtained by copolymerizing 30% by mass or less of the monomer (D), having a weight average molecular weight (measured by gel permeation chromatography using pullulan as a standard substance) of 500,000. The material separation-reducing agent for concrete according to claim 1, which comprises a copolymer of ˜3,000,000. 3. The agent for reducing material separation for concrete according to claim 1, wherein n (the number of moles of alkylene oxide added) of the monomer (A) is 4 to 50. 4. The monomer (B) is acrylic acid, and / or
The methacrylic acid and / or salt thereof is one or more selected from the group consisting of two or more, and the material separation reducing agent for concrete according to any one of claims 1 to 3. 5. The monomer (C) is 2-acrylamide-
2-Methyl-propanesulfonic acid and / or its salt, The agent for reducing concrete material separation according to any one of claims 2 to 4. 6. The chemical admixture for concrete according to claim 1, which is one or more selected from AE agents, water reducing agents, AE water reducing agents, high performance water reducing agents, high performance AE water reducing agents, and superplasticizers. An admixture for concrete in which the material separation reducing agent for concrete according to any one of items 1 to 5 is mixed. 7. A monomer mixture comprising 20 to 80% by weight of the monomer (A) and 20 to 80% by weight of the monomer (B),
Aqueous solution polymerization or aqueous solution polymerization with a monomer concentration of 5 to 20 mass% and a copolymer with a weight average molecular weight (measured by gel permeation chromatography using pullulan as a standard substance) of 500,000 to 3,000,000 for concrete. A method for producing a material separation reducing agent. 8. Water, cement, fine aggregate, coarse aggregate, and AE agent, water reducing agent, AE water reducing agent, high-performance water reducing agent, high-performance A
E In the method for producing concrete by kneading one or more chemical admixtures for concrete selected from water reducing agents and superplasticizers, the material separation for concrete according to any one of claims 1 to 6. The reducing agent, as a copolymer solid content mass, is 20 to 1.0 per unit mass of cement.
A method for producing concrete, characterized in that it is further mixed at an addition rate of 00 ppm. 9. Water, cement, fine aggregate, coarse aggregate, and AE agent, water reducing agent, AE water reducing agent, high-performance water reducing agent, high-performance A
E In the method for producing concrete by kneading one or more chemical admixtures for concrete selected from water reducing agents and superplasticizers, the material separation for concrete according to any one of claims 1 to 6. A method for producing concrete, characterized in that a reducing agent and a polyethylene oxide having a viscosity average molecular weight of 100,000 to 10,000,000 are used in combination. 10. The chemical admixture for concrete according to claim 1, which is selected from the group consisting of AE agents, water reducing agents, AE water reducing agents, high performance water reducing agents, high performance AE water reducing agents, and superplasticizers. 6. A concrete admixture containing the material separation reducing agent for concrete according to any one of 5 to 5 and polyethylene oxide having a viscosity average molecular weight of 10 to 10,000,000.