JPH07247149A - Agent for preventing lowering of fluidity of concrete - Google Patents

Abstract

PURPOSE:To improve fluidity-retaining property of a hydraulic composition by including a specific copolymer as an essential component of a concrete admixture. CONSTITUTION:Monomers of formula III [R1 is R2; (n1) is (n3); (n2) is 1-300; X1 is X2] constisting of 50-1mol% of formula I [R2 to R3 each is H or methyl; (n3) and (n5) each is 0-2; (n4) is 9-300; A0 is a 2-3C oxyalkylene; X2 to X3 each is H, a 1-3C alkyl or (substituted) amino] and 50-99mol% of a monomer of formula II are copolymerized in the presence of an aqueous polymerization initiator to provide the objective agent for preventing lowering of fluidity of concrete having 1000-500000 weight-average molecular weight (measured by gel permeation chromatography/sodium polystyrenesulfonate which is a standard substance/water system). 0.02-1.0wt.% of this fluidity-lowering preventing agent and 0.25-1.0wt.% of well-known concrete admixture such as formaldehyde condensate of a naphthalenesulfonic acid salt, formaldehyde condensate of melaminesulfonic acid salt or lignin sulfonic acid salt are added to cement.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an agent for preventing deterioration of concrete fluidity. More specifically, the present invention relates to a concrete fluidity deterioration preventive agent that exhibits an excellent effect of retaining fluidity of hydraulic compositions such as cement paste, mortar and concrete.

[0002]

BACKGROUND OF THE INVENTION Among concrete admixtures, naphthalene sulfonic acid formaldehyde condensate (hereinafter referred to as naphthalene type) and melamine sulfonic acid formaldehyde condensate are typical ones having a great fluidizing effect. (Hereinafter, referred to as melamine-based), polycarboxylic acid salts (hereinafter referred to as polycarboxylic acid-based), and so on, which are called high performance water reducing agents.

While these admixtures each have excellent characteristics, they have problems. For example, although naphthalene-based and melamine-based resins have excellent curing properties, they have the problem that the fluidity decreases over time (hereinafter referred to as slump loss), and the workability decreases, and polycarboxylic acid-based resins also have slump-like properties. It has been pointed out that loss and curing delay are large.

In recent years, with the development of a polycarboxylic acid system exhibiting excellent fluidity, it becomes possible to obtain dispersibility with a low addition amount, and curing delay is being improved. For example, copolymers of a polyalkylene glycol monoester monomer having an unsaturated bond and an acrylic acid and / or an unsaturated dicarboxylic acid monomer (Japanese Patent Publication No. 59-18338, Japanese Patent Publication No. 2-78).
No. 978, No. 2-7898, No. 2-7901, No. 2-11
542, JP-A-3-75252, JP-A-59-162163) and the like.

However, these copolymers are also due to the progress of physical and chemical agglomeration of cement particles, and several methods for preventing this phenomenon have been proposed.

For example, there is a method of adding a curing retarder such as oxycarboxylic acid for the purpose of preventing chemical aggregation.
Although the hydration reaction of cement can be delayed by this method, it is difficult to prevent physical agglomeration, and slump loss has not been prevented yet. In addition, there is a drawback that the early strength of concrete decreases.

Further, a method has been proposed in which a dispersant is granulated, added to concrete, and the granular dispersant is gradually dissolved (Japanese Patent Laid-Open No. 54-139929). Although slump loss can be prevented to some extent by this method, there are drawbacks such as a decrease in strength and a decrease in durability due to the presence of the granular dispersant locally in the concrete after hardening.

At present, some of the methods proposed so far have new problems and have not been able to sufficiently improve slump loss.

[0009]

Means for Solving the Problems The inventors of the present invention have made earnest studies to solve the above-mentioned problems, and as a result, clarified the characteristics of various surfactants for concrete, and based on the findings, designed a slump loss inhibitor. By carrying out the above, it was possible to complete a fluidity lowering agent (slump loss) inhibitor for concrete, which has excellent fluidity of cement and extremely excellent slump retention.

That is, the present invention provides one or more compounds selected from the compounds represented by the following general formula (a) (monomer
The present invention relates to a concrete fluidity deterioration preventing agent, which comprises a copolymer obtained by polymerizing (A)) as an essential component.

[0011]

[Chemical 3]

[0012] (wherein, R _1: hydrogen, methyl n _1: 0 to 2 integer n _2: 1 to 300 integer AO: oxyalkylene group having 2 to 3 carbon atoms X _1: hydrogen, 1 to carbon atoms 3 represents an alkyl group, an amino group or a substituted amino group.) More specifically, the present invention provides the following general formula (b):
The invention relates to a concrete fluidity deterioration preventing agent, which comprises a copolymer obtained by polymerizing a monomer (B) represented by the above formula and a monomer (C) represented by the following general formula (c) as an essential component.

[0013]

[Chemical 4]

(Wherein R ₂ and R _{3 are} hydrogen and methyl groups n ₃ and n ₅ are integers of 0 to 2 n ₄ are integers of 9 to 300 AO are oxyalkylene groups of _{2 to} 3 carbon atoms X ₂ , X _3:. hydrogen, an alkyl group having 1 to 3 carbon atoms, copolymers of representing) the present invention an amino group or a substituted amino group is hydrolyzed by alkaline components eluted from cement in the concrete,
The acid groups are adsorbed on the cement, the dispersibility is developed, and slump loss can be prevented.

In the present invention, as the monomer (A), methoxy polyethylene glycol, methoxy polypropylene glycol, methoxy polyethylene polypropylene glycol, ethoxy polyethylene glycol, ethoxy polypropylene glycol, ethoxy polyethylene polypropylene glycol, propoxy polyethylene glycol, propoxy polypropylene glycol, To the esterification product of the dehydrogenation (oxidation) reaction product of (meth) acrylic acid or fatty acid with polyalkylene glycol with one terminal alkyl-blocked such as propoxy polyethylene polypropylene glycol or the dehydrogenation (oxidation) reaction product of (meth) acrylic acid or fatty acid One or two or more of the ethylene oxide and propylene oxide adducts are used. The addition mole number of polyalkylene glycol is 1 to 300, but 5 to 10
0 mol is preferable for slump loss and dispersibility. For both ethylene oxide and propylene oxide adducts,
Any of random addition, block addition, alternate addition and the like can be used. When the number of moles of polyalkylene glycol added exceeds 300, not only the polymerizability decreases but also the dispersibility decreases.

Further, the monomers constituting these polymers
Among (A), a copolymer obtained by polymerizing the monomer (B) and the monomer (C) is particularly preferable for slump loss and dispersibility.

In the present invention, as the monomer (B), methoxy polyethylene glycol, methoxy polypropylene glycol, methoxy polyethylene polypropylene glycol, ethoxy polyethylene glycol, ethoxy polypropylene glycol, ethoxy polyethylene polypropylene glycol, propoxy polyethylene glycol, propoxy polypropylene glycol, To the esterification product of the dehydrogenation (oxidation) reaction product of (meth) acrylic acid or fatty acid with polyalkylene glycol blocked at one end by alkylation such as propoxy polyethylene polypropylene glycol or the dehydrogenation (oxidation) reaction product of (meth) acrylic acid or fatty acid The ethylene oxide and propylene oxide adducts thereof are used. The number of added moles of polyalkylene glycol is 9 to 300, and 9 to 100 is preferable for slump loss and dispersibility. Both the ethylene oxide and propylene oxide adducts can be used in any of random addition, block addition, alternating addition, and the like. If the number of added moles of polyalkylene glycol exceeds 300, not only the polymerizability decreases but also the dispersibility decreases, and if it is less than 9, the dispersibility decreases.

Further, as the monomer (C), 2-hydroxyethyl (meth) acrylate, hydroxypropyl
(Meth) acrylate and the like can be mentioned. If the number of moles of the oxyalkylene group added to the monomer (C) exceeds 1, the slump loss tends to decrease.

A monomer (B) constituting the copolymer of the present invention,
The reaction unit of monomer (C) is monomer (B) / monomer (C)
= 50/50 to 1/99 (molar ratio) is suitable for preventing slump loss and dispersibility, and more preferably monomer (B) / monomer (C) = 10/90 to 30 / A range of 70 (molar ratio) is preferable. Monomer
When the molar ratio of (C) is less than 50, the performance gradually deteriorates to 0.
If it is 01 or less, the performance is difficult to obtain.

The copolymer of the present invention may be copolymerized with other copolymerizable monomers within the range that does not impair the effects of the present invention. For example, acrylonitrile, acrylic acid ester, acrylamide, methacrylamide,
Examples thereof include styrene and styrene sulfonic acid.

The weight average molecular weight (gel permeation chromatography method / polystyrene sulfonic acid conversion) of the copolymer of the present invention is preferably in the range of 1,000 to 500,000,
The range of 5,000 to 100,000 is more preferable for dispersibility.

If the weight average molecular weight is less than 1,000, the dispersibility is insufficient, and if it exceeds 500,000, the cohesiveness is exhibited, which is not preferable.

Further, the concrete fluidity lowering preventive agent of the present invention can be used in combination with a known cement admixture. Examples of known cement admixtures include naphthalene sulfonate formaldehyde condensate, melamine sulfonate formaldehyde condensate, lignin sulfonate, phenol / sulfanylate formaldehyde condensate, oxycarboxylate, polyalkyl oxide ( Examples thereof include (meth) acrylic acid ester- (meth) acrylic acid ester copolymer salt. The addition amount is preferably 0.25 to 1.0% by weight based on the solid content of cement.

The polymer of the present invention can be produced by a known method. For example, JP-A-59-162163,
Methods such as Japanese Patent Publication No. 2-11542, Japanese Patent Publication No. 2-7901 and Japanese Patent Publication No. 2-7897 can be mentioned.

The solvent used for the solution polymerization is water,
Methyl alcohol, ethyl alcohol, isopropyl alcohol, benzene, toluene, xylene, cyclohexane, n-hexane, aliphatic hydrocarbons, ethyl acetate, acetone, methyl ethyl ketone and the like can be mentioned. From the viewpoint of handling and reaction equipment, water and alcohol having 1 to 4 carbon atoms are preferable.

As the water-based polymerization initiator, a water-soluble initiator such as ammonium or alkali metal persulfate or hydrogen peroxide is used. Benzoyl peroxide, lauroyl peroxide and the like are used as a polymerization initiator for solution polymerization other than the aqueous system.

It is also possible to use sodium sulfite, mercaptoethanol or an amine compound as a chain transfer agent in combination with the polymerization initiator, and these polymerization initiators or chain transfer agents can be appropriately selected and used. it can.

The amount of the concrete fluidity lowering inhibitor of the present invention added to concrete is preferably 0.02 to 1.0% by weight, more preferably 0.05 to 0.5% by weight, based on the solid content of cement.

The concrete fluidity lowering inhibitor of the present invention can be used in combination with known additives (materials). For example, AE agent, AE water reducing agent, superplasticizer, high-performance water reducing agent, retarder, early strengthening agent, accelerator, foaming agent, foaming agent, defoaming agent, thickener, waterproofing agent, antifoaming agent, Examples include silica sand, blast furnace slag, fly ash, silica fume and the like.

Further, the concrete fluidity lowering preventive agent of the present invention is added to cement paste, mortar, concrete or the like having a composition of hydraulic cement,
The content is not limited.

[0031]

EXAMPLES The present invention will be specifically described below, but the present invention is not limited to these examples. In addition, "parts" and "%" in the following examples are "parts by weight" and "% by weight".

The contents of the monomer (A), the monomer (B) and the monomer (C) used in the polymerization of the present invention are shown below. Contents of Monomers (A) to (C) A-1: Polyethylene glycol monoacrylate (number of moles of ethylene oxide added = 3.4) A-2: Polyethylene glycol monoacrylate (number of moles of ethylene oxide added = 9.1) A-3: Polyethylene glycol Monomethacrylate
(Ethylene oxide addition mole number = 23.2) A-4: Polyethylene polypropylene glycol monomethacrylate (Ethylene oxide addition mole number = 122.5,
Propylene oxide addition mole number = 2.5 block addition product) B-1: Polyethylene glycol monoacrylate (ethylene oxide addition mole number = 9.1) B-2: Polyethylene glycol monoacrylate (ethylene oxide addition mole number = 23.2) C-1: 2- Hydroxyethyl (meth) acrylate C-2: 2-Hydroxypropyl acrylate Production Example 1 A reaction vessel equipped with a stirrer was charged with 15 mol of water and heated to 75 ° C in a nitrogen atmosphere. 1 mol of A-1, 0.01 mol of a 20% ammonium persulfate aqueous solution, and 7 g of 2-mercaptoethanol were simultaneously added dropwise to the reaction system over 2 hours, and the mixture was aged at the same temperature (75 ° C.) for 1 hour. After aging, the temperature was raised to 95 ° C, and 18g of 36% hydrogen peroxide was added dropwise over 1 hour.
Aging at the same temperature for a time gave a copolymer having a molecular weight of 11,000.

Production Example 2 A reaction vessel equipped with a stirrer was charged with 15 mol of water and heated to 75 ° C. in a nitrogen atmosphere. 1 mol of A-2, 0.03 mol of 20% ammonium persulfate aqueous solution, and 3 g of 2-mercaptoethanol were simultaneously added dropwise to the reaction system over 2 hours, and the mixture was aged at the same temperature (75 ° C.) for 1 hour. After aging, the temperature was raised to 95 ° C, and 15 g of 36% hydrogen peroxide was added dropwise over 1 hour.
Aging at the same temperature (95 ° C) for a time gave a copolymer having a molecular weight of 22,000.

Production Example 3 A reaction vessel equipped with a stirrer was charged with 15 mol of water and heated to 75 ° C. in a nitrogen atmosphere. 1 mol of A-3, 0.01 mol of 20% ammonium persulfate aqueous solution, and 3 g of 2-mercaptoethanol were simultaneously added dropwise to the reaction system over 2 hours, and the mixture was aged at the same temperature (75 ° C.) for 1 hour. After aging, the temperature was raised to 95 ° C, and 15 g of 36% hydrogen peroxide was added dropwise over 1 hour.
Aging at the same temperature (95 ° C) for a time gave a copolymer having a molecular weight of 27,000.

Production Example 4 A reaction vessel equipped with a stirrer was charged with 15 mol of water and heated to 75 ° C. in a nitrogen atmosphere. 1 mol of A-4, 0.01 mol of a 20% ammonium persulfate aqueous solution, and 3 g of 2-mercaptoethanol were simultaneously added dropwise to the reaction system over 2 hours, and the mixture was aged at the same temperature (75 ° C.) for 1 hour. After aging, the temperature was raised to 95 ° C, and 15 g of 36% hydrogen peroxide was added dropwise over 1 hour.
Aging at the same temperature (95 ° C) for a time gave a copolymer having a molecular weight of 57,000.

Production Example 5 15 mol of water was charged into a reaction vessel equipped with a stirrer and heated to 75 ° C. in a nitrogen atmosphere. B-1 0.1 mol, C-1 0.9
Mol and 0.01% 20% ammonium persulfate aqueous solution and 2-
Three parts of 7 g of mercaptoethanol are simultaneously dropped into the reaction system over 2 hours, and aged at the same temperature (75 ° C.) for 1 hour. After aging, the temperature was raised to 95 ° C and 18g of 36% hydrogen peroxide was added.
The mixture was added dropwise over a period of time and aged at the same temperature (95 ° C.) for 2 hours to obtain a copolymer having a molecular weight of 15,000.

Production Example 6 A reaction vessel equipped with a stirrer was charged with 15 mol of water and heated to 75 ° C. in a nitrogen atmosphere. 0.3 mol of B-2 and 0.7 mol of C-1
Mol and 0.01% 20% ammonium persulfate aqueous solution and 2-
3 g of mercaptoethanol (5 g) was simultaneously dropped into the reaction system over 2 hours, and the mixture was aged at the same temperature (75 ° C.) for 1 hour. After aging, raise the temperature to 95 ° C and add 15 g of 36% hydrogen peroxide to 1 g.
The mixture was added dropwise over a period of time and aged at the same temperature (95 ° C.) for 2 hours to obtain a copolymer having a molecular weight of 23,000.

Production Example 7 A reaction vessel equipped with a stirrer was charged with 15 mol of water and heated to 75 ° C. in a nitrogen atmosphere. 0.1 mol of B-2 and 0.9 mol of C-2
Mol and 0.01% 20% ammonium persulfate aqueous solution and 2-
3 g of mercaptoethanol (5 g) was simultaneously dropped into the reaction system over 2 hours, and the mixture was aged at the same temperature (75 ° C.) for 1 hour. After aging, raise the temperature to 95 ° C and add 15 g of 36% hydrogen peroxide to 1 g.
The mixture was added dropwise over a period of time and aged at the same temperature (95 ° C.) for 2 hours to obtain a copolymer having a molecular weight of 34,000.

The contents and symbols of the dispersants used in the examples other than the comparative polymers of the copolymers are shown below. Symbol for dispersant NS: Naphthalene-based admixture (Mighty 150
; Kao Corporation Dispersant symbol MS: Melamine admixture (Mighty 150V-
2; Kao Corporation) Dispersant symbol PC: polyoxyethylene glycol methacrylate / acrylic acid copolymer (FC-600S; Nippon Shokubai Chemical Co., Ltd.).

Evaluation as a concrete fluidity reduction inhibitor
Table 1 shows the mixing conditions of the valence concrete.

[0041]

[Table 1]

The concrete was prepared by mixing the materials and admixtures in a tilting mixer with a mixing ratio of 25
It was adjusted by kneading for 3 minutes at pm. Liquidity (slump value)
After the measurement, was further rotated at 4 rpm for 60 minutes, and the slump value (cm) after 60 minutes was measured. Also, the initial slump value is 20 ±
It was adjusted by the addition amount of the present invention and the comparative admixture so as to be 1 cm (the addition amount represents the addition amount to cement). The slump value was measured by the JIS A 1101 method. Table 2 shows the measurement results
Shown in.

[0043]

[Table 2]

Evaluation Results As is clear from Table 2, the fluidity lowering preventive agent of the present invention has a remarkable slump retention property as compared with the comparative product.

[0045]

When the concrete fluidity lowering inhibitor according to the present invention is added to the cement composition, the change in fluidity is small over a long period of time, which facilitates the quality control of concrete.

Claims (6)

[Claims] 1. An essential component is a copolymer obtained by polymerizing one or more compounds (monomer (A)) selected from the compounds represented by the following general formula (a): Concrete fluidity reduction inhibitor. [Chemical 1] (Wherein, R _1: hydrogen, methyl n _1: 0 to 2 integer n _2: 1 to 300 integer AO: oxyalkylene group having 2 to 3 carbon atoms X _1: hydrogen, alkyl of 1 to 3 carbon atoms Represents a group, an amino group or a substituted amino group.) 2. A monomer (B) represented by the following general formula (b):
And a concrete fluidity deterioration preventing agent, which comprises a copolymer obtained by polymerizing a monomer (C) represented by the following general formula (c) as an essential component. [Chemical 2] (In the formula, R ₂ and R ₃ : hydrogen, a methyl group n ₃ and n ₅ : an integer of 0 to 2 n ₄ : an integer of 9 to 300 AO: an oxyalkylene group of _{2 to} 3 carbon atoms X ₂ , X ₃ : Represents hydrogen, an alkyl group having 1 to 3 carbon atoms, an amino group or a substituted amino group.) 3. A monomer (B) constituting the copolymer, a monomer
The reaction unit of (C) is monomer (B) / monomer (C) = 50/50 to 1/99
(Molar ratio) 3. The concrete fluidity deterioration preventing agent according to claim 2. 4. The average molecular weight of the copolymer is 1,0 in terms of weight average molecular weight (gel permeation chromatography method / standard substance sodium polystyrene sulfonate / water system).
The concrete fluidity lowering preventive agent according to any one of claims 1 to 3, which is 00 to 500,000. 5. The concrete fluidity deterioration preventing agent according to claim 1, further comprising a known cement admixture. 6. A known cement admixture used in combination is a naphthalene sulfonate formaldehyde condensate, a melamine sulfonate formaldehyde condensate, a lignin sulfonate, a phenol / sulfanylate formaldehyde condensate, and a polyalkyl oxide (meth). 6. The concrete fluidity deterioration preventing agent according to claim 5, which is one or more selected from the group consisting of acrylic acid ester- (meth) acrylic acid ester copolymer salt.