JP2000001352A - Cement admixture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To impart flowability, flowability retention, fillability and material separation resistance in a well-balanced state to fresh concrete and to improve applicability, work efficiency and the quality of a hardened body by using a copolymer obtd. by polymerizing two specified vinyl monomers. SOLUTION: The cement admixture contains a copolymer obtd. by copolymerizing 2-90 wt.% one or more monomers (A) represented by formula I (where R1 and R2 are each H or methyl and R3 is H or 1-5C alkyl), 90-10 wt.% one or more monomers (B) represented by formula II [where R5 is H or methyl; X is-C(=O)- or -CH2-; Y is 2-4C alkylene; R5 is H or 1-5C alkyl and (n) is an integer of 1-100] and 0-60 wt.% vinyl monomer other than the monomers A and B. The total amt. of the monomers A-C is 100 wt.%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cement admixture, and more particularly, to a cement admixture, such as concrete, mortar, cement paste, etc., to obtain good fluidity and fluidity retention performance. Filling,
The present invention relates to a cement admixture capable of imparting material separation resistance and the like in a well-balanced manner and improving workability, workability, quality of a cured product, and the like.

[0002]

2. Description of the Related Art In recent years, there has been an increasing demand for compaction-free concrete in order to simplify on-site work and reduce noise by vibrating compaction. In addition, as structures become more complex and more sophisticated, it is necessary to uniformly fill concrete into highly densely laid formwork, and concrete with high fluidity and filling properties is being actively studied. ing. In general,
A water reducing agent is added to these concretes to improve their fluidity and filling properties. These water reducing agents include various salts such as a salt of melamine sulfonic acid formaldehyde, a salt of naphthalene sulfonic acid formaldehyde, and a polycarboxylate. Further, among these water reducing agents, water reducing agents having particularly high water reducing performance and capable of improving the time-dependent decrease of the fluidity of the cement composition, that is, the improvement of slump loss, have been actively proposed (for example, Japanese Patent Application Laid-Open No. Hei 5-238795). JP, JP-A-8-225354, JP-A-6-206050
No.). However, when these water reducing agents are used, the fluidity of the cement composition can be improved due to its high dispersing effect, but the material separation of the aggregate occurs, and the entanglement of the coarse aggregate lowers the filling property, and the uniformity decreases. Since it is impossible to obtain proper concrete, the quality of concrete is reduced.

For the purpose of suppressing this material separation, the addition of water-soluble polymers such as cellulose derivatives such as methylcellulose ether, synthetic polymers such as polyacrylamide, and natural polysaccharides such as curdlan has been studied (for example, JP-A-61-72664, JP-A-61-260453, and JP-A-9-2856. However, when these water-soluble polymers are added in an amount sufficient to suppress material separation, there is a problem that the fluidity decreases with an increase in viscosity. As described above, in the prior art, fluidity,
It is extremely difficult to satisfy the required properties such as fluidity retention performance, filling property, and material separation resistance in a well-balanced manner, and cement admixtures that can satisfy these requirements have been long-awaited.

[0004]

SUMMARY OF THE INVENTION The present invention improves workability, workability and hardened material quality by imparting fluidity, fluidity retention, filling properties and material separation resistance to fresh concrete in a well-balanced manner. It is an object to provide a cement admixture that can be used.

[0005]

Means for Solving the Problems The present inventor has made intensive studies to solve the above-mentioned problems, and as a result, completed the present invention. That is, the present invention relates to the general formula (1)

Embedded image (Wherein, R ¹ and R ² each independently represent a hydrogen atom or a methyl group, and R ³ represents a hydrogen atom or a C 1 -C 1
5 represents an alkyl group. 2) to 90% by weight of one or more monomers (A) represented by the general formula (2)

Embedded image (Wherein, R ⁴ represents a hydrogen atom or a methyl group;
Represents —C (＝ O) — or —CH ₂ —, and Y represents 2 to 2 carbon atoms.
R ⁵ is a hydrogen atom or a C 1 -C 4 alkylene group;
5 represents an alkyl group, and n represents an integer of 1 to 100. )), One or two or more monomers (B) are
0% by weight, and 0 to 60% by weight of the vinyl monomer (C) other than the monomer (A) and the monomer (B) [however, the monomer (A) and the monomer (B) And the total of the vinyl monomer (C) is 100% by weight. And a cement admixture characterized by containing a copolymer obtained by polymerizing the same.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The general formula (1) used in the present invention
Examples of the monomer (A) represented by are, for example, N-vinylformamide, N-vinylacetamide, N-vinylpropionamide, N-vinylbutylamide, N-methyl-N-vinylformamide, N-methyl-N -Vinylacetamide and the like, and N-vinylacetamide is preferred from the viewpoint of improving material separation resistance. The monomer (A) in all the monomers of the copolymer used in the cement admixture of the present invention is 2 to 90% by weight, preferably 5 to 50% by weight.
% By weight. If it exceeds 90% by weight, it is difficult to impart sufficient fluidity and fluidity retention performance to fresh concrete, and if it is less than 2% by weight, it becomes difficult to impart sufficient viscosity to fresh concrete. , Material separation tends to occur.

The monomer (B) represented by the general formula (2) used in the present invention includes, for example, polyethylene glycol, methoxypolyethylene glycol, ethoxypolyethylene glycol, polypropylene glycol and polybutylene glycol wherein n is 1 to 100. And methoxy polypropylene glycol, ethoxy polypropylene glycol, and the like, and an esterified product of (meth) acrylic acid, or an etherified product of allyl alcohol, and the like. N of these compounds is preferably 4 to 50. Particularly preferably, n is 8 to 23, X is -C (= O) - and, Y is -CH ₂ -CH ₂ - is, R ⁵ is a methyl group. In the copolymer used in the cement admixture of the present invention, the monomer (B) in all the monomers is 90 to 1
0% by weight, preferably 70 to 40% by weight.
If it exceeds 90% by weight, it becomes difficult to impart sufficient viscosity to the fresh concrete, so that material separation tends to occur. If it is less than 10% by weight, sufficient fluidity and fluidity retention for the fresh concrete are obtained. It becomes difficult to provide performance.

[0008] Vinyl monomer (C) used in the present invention
May be a vinyl monomer other than the monomer (A) and the monomer (B). For example, (meth) acrylic acid, maleic acid, fumaric acid, itaconic acid, 2-acrylamide-2
Anionic monomers such as -methyl-propanesulfonic acid, 2-acrylamidoethanesulfonic acid, 2-methacrylamidoethanesulfonic acid, 3-methacrylamidopropanesulfonic acid, (meth) acrylsulfonic acid, styrenesulfonic acid or salts thereof. Body, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, (meth) acrylamide, N, N-dimethyl (meth) ) Acrylamide, N-isopropylacrylamide, diacetone acrylamide, N-methylolacrylamide, acryloylmorpholine, N-vinylpyrrolidone, (meth) acrylonitrile, styrene, α-methylstyrene, p-methyls Ren, styrene dimer,
Non-ionic monomers such as vinyl acetate, methyl vinyl ketone, ethyl vinyl ketone, methyl vinyl ether, ethyl vinyl ether, isobutylene, 4-methylpentene-1, norbornene, allyl alcohol, and allyl chloride; N, N-dimethylaminoethyl acrylate; Cationic monomers such as N, N-dimethylaminopropylacrylamide or a quaternary ammonium salt thereof, and the like. In the present invention, “(meth) acryl” is used.
Means “acry” or “methacry” or both. In the present invention, the vinyl monomer (C) may or may not be used as a monomer, but when used, it should not exceed 60% by weight of the total monomers. It is preferably at most 30% by weight. If it exceeds 60% by weight, the performance as a cement admixture of the present invention cannot be sufficiently exhibited.

The method for producing the copolymer used in the present invention is not particularly limited, but methods such as aqueous solution polymerization, reverse phase suspension polymerization, and precipitation polymerization can be used. Usually, a polymerization initiator is used. The polymerization initiator is
A normal radical polymerization initiator can be used,
2′-azobisisobutyronitrile, 2,2′-azobis (2-amidinopropane) dihydrochloride,
2,2′-azobis [2- (2-imidazolin-2-yl) propane] dihydrochloride, 2,2′-azobis [2- (3,4,5,6-tetrahydropyrimidin-2-yl) propane ] Dihydrochloride, 2,
2′-azobis [2- (5-hydroxy-3,4,5,
Azo initiators such as 6-tetrahydropyrimidin-2-yl) propane] dihydrochloride, peroxides such as hydrogen peroxide, benzoyl peroxide, t-butyl hydroperoxide, succinic peroxide, ammonium persulfate, peroxide A so-called redox initiator in which a persulfate such as potassium sulfate, a peroxide or a persulfate and a reducing agent such as triethanolamine, sodium sulfite or sodium thiosulfate are present in the same system is exemplified. In addition, a chain transfer agent can be used at the time of polymerization as a molecular weight regulator. Examples of the chain transfer agent include n-butyl mercaptan, triethylamine, isopropyl alcohol, ammonium thioglycolate, sodium hypophosphite and the like.

The weight average molecular weight (measured by gel permeation chromatography using pullulan as a standard substance) of the copolymer of the present invention varies depending on the blending conditions, use conditions and required properties for the cement composition. 5000 to 3,000,000 is preferred. When fluidity and fluidity retention performance are particularly required, it is preferably 5,000 to 300,000. When material separation resistance is particularly required, 30 to 300,000 is preferable.
10,000 to 3,000,000 is preferred. Weight average molecular weight of 5000
When it is less than the above, the viscosity imparting to the fresh concrete becomes insufficient, and there is a tendency that the material is separated.
If the amount is more than 10,000, the dispersibility tends to decrease, and the fluidity, the fluidity retention performance, and the filling property tend to be insufficient.

The amount of the cement admixture of the present invention is usually 0.0
It is preferably from 0.5 to 2.0% by weight. The cement 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.
In addition, the cement admixture of the present invention may contain other cement additives (materials) such as a water reducing agent, an AE water reducing agent, a high-performance water reducing agent, a superplasticizer, a high-performance AE water reducing agent, a retarder, an early strength agent, and an accelerator. Agent,
Foaming agent, foaming agent, water retention agent, thickener, waterproofing agent, antifoaming agent, water-soluble polymer, surfactant, expanding agent (material), blast furnace slag,
It can be used in combination with fly ash, silica fume, asbestos, vinylon fiber, PP fiber and the like. For example,
A thickener such as methylcellulose and polyacrylamide can be used in combination with the cement admixture of the present invention. Further, a high-performance AE (air entraining) water reducing agent can be used in combination with the cement admixture of the present invention.

[0012]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to the examples. Production Example 1 (Production of Copolymer S1) In a glass reactor equipped with a stirrer, 90 g of N-vinylacetamide and 120 g of methoxypolyethylene glycol methacrylate (the number of moles of ethylene glycol added is 9, hereinafter referred to as "9EG-MA"). And methacrylic acid 9
0 g was added, and 530 g of water was added to dissolve. Next, 4
140 g of a 0% aqueous sodium hydroxide solution was added to adjust the pH of the reaction system to 9.0. 60 in a constant temperature water bath with stirring
C. and remove dissolved oxygen by nitrogen aeration.
A 30% aqueous solution of ammonium persulfate (APS) was added, and the mixture was reacted for 5 hours under nitrogen to complete the polymerization. The weight average molecular weight of the obtained copolymer (S1) was 28,000 as a result of measurement by gel permeation chromatography using pullulan as a standard substance (hereinafter, the weight average molecular weight was measured by the same method).

Production Examples 2 to 12 (Production of Copolymers S2 to S12) In the same manner as in Production Example 1, the types of the monomers, the composition ratios of the monomers, and the amounts of the 25% ammonium persulfate aqueous solution were changed. To produce a copolymer (S2 to S12). The specific conditions and the weight average molecular weight are shown in Table 1 together with S1.

[0014]

[Table 1]

In Table 1, NVA: N-vinylacetamide NVF: N-vinylformamide 9EG-MA: methoxypolyethylene glycol methacrylate (number of moles of ethylene glycol added: 9) 23EG-MA: methoxypolyethylene glycol methacrylate (ethylene MA: methacrylic acid • AA: acrylic acid • MS: methacrylsulfonic acid • AN: acrylonitrile • MAA: methyl acrylate • APS: ammonium persulfate

Production Example 13 (Production of Copolymer S13) In a glass reactor equipped with a stirrer, 200 g of N-vinylacetamide and 50 g of methoxypolyethylene glycol methacrylate (9EG-MA) were added, and 740 g of water was added to dissolve it. After keeping the temperature at 30 ° C. in a constant temperature water bath under stirring and removing dissolved oxygen by aeration with nitrogen, 2.5% of 2,2′-azobis [2- (2-imidazolin-2-yl) propane] dihydrochloride was added. An aqueous solution (10 g) was added and reacted under nitrogen aeration. At the end of the reaction, the product is brought to 50 ° C.
For 5 hours. After sufficient removal of water, the powder was reduced to 100 mesh or less by a small crusher. The weight average molecular weight of the obtained copolymer (S13) was 1.21 million.

Production Example 14 (Production of copolymer S14) 2-Acrylamide-2 was placed in a glass reactor equipped with a stirrer.
20 g of methyl-propanesulfonic acid and 899 of water
g was added and dissolved. After adjusting the pH to 8.0 by adding sodium hydroxide, 50 g of N-vinylacetamide, 30 g of methoxypolyethylene glycol methacrylate (9EG-MA) and 0.01 g of ammonium thioglycolate were dissolved. After keeping the temperature at 50 ° C. in a constant temperature water bath under stirring and removing dissolved oxygen by nitrogen aeration, 1 g of 2,2′-azobis (2-amidinopropane) dihydrochloride was added and reacted under nitrogen aeration. The weight average molecular weight of the obtained copolymer (S14) is:
It was 1.52 million.

Comparative Production Example 1 (Production of Copolymer R1) Methyl acrylate (M
AA) 105 g and methoxypolyethylene glycol methacrylate (the number of ethylene glycol added: 9 mol) 10
5 g and 90 g of methacrylic acid (MA) are added, and 542 g of water is added.
And dissolved. Next, 140 g of a 40% aqueous sodium hydroxide solution was added to adjust the pH of the reaction system to 9.0. After maintaining the temperature at 60 ° C. in a constant temperature water bath under stirring and removing dissolved oxygen by nitrogen aeration, 18 g of a 25% ammonium persulfate (APS) aqueous solution was added, and the mixture was reacted for 5 hours under nitrogen aeration to complete the polymerization. Obtained copolymer (R1)
Had a weight average molecular weight of 19000. Comparative Production Examples 2 to 8 (Production of Copolymers R2 to R8)

Production was carried out in the same manner as in Comparative Production Example 1 except that the type of monomer, the composition ratio of the monomer, and the amount of 25% aqueous ammonium persulfate added were changed to produce a copolymer (R2-R
8) was obtained. The specific conditions and the weight average molecular weight are shown in Table 2 together with R1.

[0020]

[Table 2] In Table 2, 9EG-MA, 23EG-MA, MA,
AA, MS, AN, MAA, APS are as described above.

(1) Performance evaluation of cement admixture-1 In order to grasp the performance of the synthesized copolymer as a cement admixture, each copolymer was added at the time of concrete preparation, and its fluidity and self-adhesion were evaluated. A performance evaluation test was performed on the filling property and the material separation resistance. (1-1) Concrete mixing and mixing method Concrete mixing Table 3 shows the concrete mixing in the performance evaluation test.

[0022]

[Table 3] 1) Water (W): tap water 2) Cement (C): ordinary Portland cement (specific gravity:
3.16) 3) Fine aggregate (S): River sand from Fujikawa (specific gravity: 2.60, coarse particle ratio: 2.65) 4) Coarse aggregate (G): Ome crushed stone (specific gravity: 2.65, coarse particle ratio:
6.85) * a = S + G

Kneading method: Cement (C), fine aggregate (S), coarse aggregate (G), and admixture (in the case of powder), which are powder raw materials, are each a predetermined amount in a 50 L pan mold. Charge into a mixer and stir for 30 seconds. Thereafter, water (W) and admixture (if liquid) are added and stirring is continued for another 120 seconds. After confirming sufficient mixing, discharge and subject to a performance test.・ Mixer: 50L bread type mixer ・ Mixing amount: 30L

(1-2) Performance test method Fluidity test Slump flow test: "Architectural Institute of Japan JASS 5
T-503 ", immediately after mixing, one hour later,
It was measured after 2 hours.

Self-Fillability Test Using the L-shaped test apparatus shown in FIG. 1 (front view) and FIG. 2 (side view), after filling the left chamber 2 with concrete with the partition plate 1 closed, Open the partition plate 1 fully,
The filling height of the concrete flowing into the right room 3 around the reinforcing bars 4 (up and down 50 mm intervals) was measured. In addition, height H
₁ is 400 mm, H ₂ is 200 mm, horizontal length L ₁ is 2
00mm, L ₂ is 400mm, the width M is 200mm. In the results of this test, the higher the filling height (20
cm) is considered to indicate that a good self-filling property can be secured.

Material Separation Resistance Test A “coarse aggregate washing test” described in “Architectural Institute of Japan, Material, Mixing, Production, Construction Guideline (Draft), and Explanation” was conducted. That is, about 2 kg of fresh concrete after the end of the slump flow test was collected from each of the center and the outer periphery, wet-screened with a 5 mm sieve, and the weight of the remaining aggregate was measured. The ratio of the weight ratio of coarse aggregate at the center was determined as the ratio of inner and outer coarse aggregate. Accordingly, it is determined that the closer the inner / outer coarse aggregate ratio is to 1, the smaller the difference in coarse aggregate between the central portion and the outer peripheral portion, so that the material exhibits better material separation resistance.

Others The air volume and compressive strength (after 7 days and 28 days of material age) were measured according to JIS-A1128 and JIS-A1108, respectively. (1-3) Performance test results Tables 4 and 5 show the performance test results.

[0028]

[Table 4]

* Addition amount of cement admixture (solid content of polymer, relative to cement): 0.05% by weight 0.25% by weight 0.75% by weight

[0030]

[Table 5]

1) X: polycarboxylic acid-based high-performance AE water reducing agent (Mighty 2000WHS manufactured by Kao Corporation) 2) Y: polycarboxylic acid ether-based high-performance AE water reducing agent
3) Z: Methyl cellulose (90SH-15000 manufactured by Shin-Etsu Chemical Co., Ltd.) * Additive amount of admixture a (polymer solid content, cement)
0.5% by weight * Addition amount of admixture b (solid content of polymer, relative to cement) 0.015% by weight 0.030% by weight 0.075% by weight 0.15% by weight

(2) Performance evaluation of cement admixture-2 Each polymer synthesized at the time of concrete preparation was added.
A performance evaluation test was performed for each fluidity and fluid retention.

(2-1) Concrete Mixing and Mixing Method Concrete Mixing Concrete mixing in the performance evaluation test is shown in Table 6.

[0034]

[Table 6] 1) Water (W): tap water 2) Cement (C): ordinary Portland cement (specific gravity:
3.16) 3) Fine aggregate (S): River sand from Fujikawa (specific gravity: 2.60, coarse particle ratio: 2.65) 4) Coarse aggregate (G): Ome crushed stone (specific gravity: 2.65, coarse particle ratio: 6.85) * a = S + G Kneading method → Perform the same method as “Performance evaluation of cement admixture-1”.

(2-2) Performance test method The slump test was performed immediately after mixing according to JIS-A1101.
It was measured after 60 minutes. The air volume and compressive strength (after 7 days and 28 days) are as shown in "Performance evaluation of cement admixture-1"
Was performed in the same manner as described above.

(2-3) Performance Test Results The performance test results are shown in Table 7.

[Table 7] * Addition amount of cement admixture (solid content of polymer to cement): 0.5% by weight

[0037]

The cement admixture of the present invention can be added alone to a cement composition such as concrete to impart a good balance of fluidity, fluidity retention, filling and separation resistance to fresh concrete. . Also, by using a small amount in combination with other water reducing agents, the fluidity, fluidity retention, filling properties, and separation resistance can be imparted in a well-balanced manner by self-use of the cement composition, and the workability, workability, and curing It is effective for improving body quality.

[Brief description of the drawings]

FIG. 1 is a front view of an L-type test apparatus for a self-filling test.

FIG. 2 is a side view of an L-shaped test apparatus for a self-filling test.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Partition board 2 Left room 3 Right room 4 13mmφ rebar

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08F 226/02 C08F 226/02 // C04B 103: 30

Claims (4)

[Claims] [Claim 1] The following general formula (1) (Wherein, R ¹ and R ² each independently represent a hydrogen atom or a methyl group, and R ³ represents a hydrogen atom or a C 1 -C 1
5 represents an alkyl group. 2) to 90% by weight of one or more monomers (A) represented by the following general formula (2): (Wherein, R ⁴ represents a hydrogen atom or a methyl group;
Represents —C (＝ O) — or —CH ₂ —, and Y represents 2 to 2 carbon atoms.
R ⁵ is a hydrogen atom or a C 1 -C 4 alkylene group;
5 represents an alkyl group, and n represents an integer of 1 to 100. )), One or more of the monomers (B) are from 90 to 1
0% by weight, and 0 to 60% by weight of the vinyl monomer (C) other than the monomer (A) and the monomer (B) [the monomer (A),
When the total of the monomer (B) and the vinyl monomer (C) is 10
0% by weight. ], A cement admixture characterized by containing a copolymer obtained by polymerizing the above. 2. The cement admixture according to claim 1, wherein the monomer (A) is N-vinylacetamide. 3. The cement admixture according to claim 1, wherein n of the monomer (B) is an integer of 4 to 50. 4. The method according to claim 1, wherein the vinyl monomer (C) is (meth) acrylic acid, 2-acrylamido-2-methyl-propanesulfonic acid, (meth) acrylsulfonic acid, or a salt thereof, or methyl (meth) acrylate. And 1 or 2 or more compounds selected from the group consisting of, ethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate and (meth) acrylonitrile. 3. The cement admixture according to 3.