JP2001019513A - Powder for reducing separation of concrete and production of concrete - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain powder for reducing separation of concrete, capable of shortening kneading time and provide a method for producing concrete. SOLUTION: This powder for reducing separation of concrete comprises a polymer obtained by polymerizing a polymerizable monomer having a group capable of increasing hydrophilic property by adding an alkaline substance in the presence of water, e.g. carboxyl group, sulfonic acid group or phenolic hydroxyl group. This method for producing concrete comprises adding the above powder for reducing separation of concrete to concrete. According to the above method, an amount of the powder used can be reduced in comparison with that of emulsion and excellent slump value and flow value of concrete equivalent to that of concrete obtained by using emulsion can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a powder for reducing concrete separation and a method for producing concrete, characterized by adding the powder. The present invention relates to a concrete separation reducing powder having an excellent flow value and a method for producing concrete to which the powder is added.

[0002]

2. Description of the Related Art Cement paste in which water is added to cement, mortar in which sand is mixed with fine aggregate, and concrete in which pebbles are mixed are used for various purposes such as structural materials, foundations and fire-resistant walls. The amount is also large. However, mortar and concrete exhibit strength through agglomeration and hardening due to a hydration reaction between cement and water, so that workability generally decreases with time after the addition of water. However, if the fluidity of the concrete is simply increased, the uniformity of the concrete is impaired due to a difference in specific gravity of each component constituting the concrete, and a part of the concrete is precipitated, which may adversely affect the strength and durability of the concrete structure. In particular, since the early deterioration of concrete structures became a social problem, reducing the unit water content in concrete,
While there is a strong demand for improving its workability and durability, technical innovations have been made on cement additives that greatly affect the quality and performance of cement compositions.

On the other hand, there is an initial crack of concrete as a factor relating to deterioration of concrete, which is caused by sinking of concrete components, uneven expansion and drying shrinkage due to heat of hydration. The sinking of concrete is a phenomenon in which mortar components and water are separated before setting, and is a phenomenon that occurs when the amount of water mixed with cement is increased in order to improve workability. On the other hand, cracks due to heat of hydration are caused by a temperature difference between the concrete surface and the central portion, and are a serious problem when setting or hardening mass concrete such as a dam or a pier. In addition, cracks due to drying shrinkage are caused by water evaporating and drying before setting.

[0004] In order to prevent such deterioration of the concrete, a thickener is used for the purpose of adjusting the slump characteristics of the highly fluidized concrete. This thickener is also used for the purpose of preventing bleeding, preventing drying during curing, reducing material separation during casting in water, and suppressing generation of dust in the sprayed concrete method. As such thickeners, those conventionally used include cellulose derivatives such as methylcellulose, ethylcellulose and hydroxyethylcellulose, polyacrylamides, polyvinyl alcohol, polysaccharides, β-1,3-glucan and the like.

JP-A-8-225353 discloses an admixture for highly fluid concrete containing a copolymer emulsion having a free carboxylic acid group obtained from a monomer component in a polymer chain. Have been. According to the publication, in the combination of a conventional inorganic fine powder and a high-performance water reducing agent, the compounding method itself is not easy because a large amount of the inorganic fine powder is mixed into concrete, and drying shrinkage of concrete and It is pointed out that durability of concrete deteriorates, for example, cracks due to heat of hydration of a large amount of the additive increase. Further, when a high-performance water reducing agent and an organic separation reducing agent such as a natural polysaccharide polymer such as water-soluble cellulose are used in combination, since these substances are powder, not only the addition work is complicated, but also the He points out that it also lowers freeze-thaw performance. Therefore, in order to solve the disadvantages of these powders, the above publication proposes an emulsion agent.

[0006] However, the emulsion agent originally contains water, and it is required to add a large amount of the emulsion agent compared to the powder. I can't. Therefore, especially when the construction site is narrow, the workability at the time of concrete preparation is reduced by the use of the emulsion agent.
In particular, since the emulsion agent has a high water content, it is not limited to the time of its use, but involves the movement of bulky and heavy products regardless of the production, sale, storage and transportation. The burden on both the trader and the user is disadvantageous.

[0007]

Accordingly, the first aspect of the present invention is as follows.
Is to provide a concrete separation reducing powder containing a polymer obtained by polymerizing a monomer component containing a polymerizable monomer having a group whose hydrophilicity is increased by adding an alkaline substance in the presence of water. It is.

A second object of the present invention is to provide a method for producing concrete, characterized by adding the concrete separation reducing powder.

[0009]

The above object is achieved by the following (1) to (5).

(1) Powder for concrete separation reduction containing a polymer obtained by polymerizing a monomer component containing a polymerizable monomer having a group whose hydrophilicity is enhanced by adding an alkaline substance in the presence of water .

(2) The groups which increase the hydrophilicity include a carboxyl group, a sulfonic acid group, a phenolic hydroxyl group, a phosphoric acid group, a carboxylic acid ester group which is easily hydrolyzed to form an acid group, a phosphoric acid ester group and The powder for reducing concrete separation according to the above (1), which is at least one member selected from the group consisting of sulfate groups.

(3) The powder for concrete separation reduction according to the above (1) or (2), wherein the polymerization is emulsion polymerization.

(4) The powder for reducing concrete separation according to any of (1) to (3), further comprising a defoaming agent.

(5) A method for producing concrete, comprising adding the powder for reducing concrete separation according to any of (1) to (4).

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The first aspect of the present invention is that, in the presence of water,
It is a concrete separation reducing powder containing a polymer obtained by polymerizing a monomer component containing a polymerizable monomer having a group whose hydrophilicity is increased by adding an alkaline substance. Conventionally, as a compound used as a thickener, a mere water-soluble polymer that is soluble in neutral water, such as a cellulose derivative, polyacrylamides, polyvinyl alcohol, and polysaccharides, has been frequently used. However, the present invention contains a group that increases the hydrophilicity by adding an alkaline substance in the polymer in the presence of water, so that the action of the alkali contained in the cement in the presence of water results in rapid and strong hydrophilicity. It can exert an action and a thickening action. Moreover, since it is a powder, it can be premixed with cement, and uniform kneading becomes easy. Hereinafter, the concrete separation reducing powder of the present invention will be described in detail.

In the present invention, there is no particular limitation on the group which increases the hydrophilicity by adding an alkaline substance in the presence of water. However, an acid group such as a carboxyl group or an acid group which is easily hydrolyzed is converted into an acid group. There are a carboxylic acid ester group, a sulfonic acid group, a phenolic hydroxyl group, a phosphoric acid group, a phosphoric acid ester group, a sulfate ester group, and the like, which are formed. The monomers used in the present invention are not limited to those having one of these groups, and may include two or more of these groups in one molecule.
Among them, those having a carboxyl group are preferable because the neutralization reaction proceeds promptly by the addition of an alkaline substance in an aqueous medium, and becomes a hydrophilic carboxyl ion, and is easily adapted to the aqueous medium. One of these monomers may be used alone, or two or more of them may be used in combination.

The monomeric component used in the present invention contains, in one molecule, a group whose hydrophilicity is enhanced by these alkaline substances.
At least one kind of polymerizable monomer (A) containing at least one kind is essential, and a monomer component containing another polymerizable monomer copolymerizable therewith is used.

Specific examples of the polymerizable monomer (A) include (1) carboxyl group-containing polymerizable polymers such as (meth) acrylic acid, itaconic acid, fumaric acid, crotonic acid, maleic acid and maleic anhydride. Monomer, (2) a sulfonic acid group-containing polymerizable monomer such as vinyl sulfonic acid, styrene sulfonic acid, sulfoethyl (meth) acrylate, allyl sulfonic acid, methallyl sulfonic acid, and (3) an alkaline aqueous solution having a pH of 10. Polymerizable monomers having higher hydrolyzability than butyl acrylate, such as methyl acrylate, ethyl acrylate, hydroxyethyl acrylate, etc. Monomer, (4) 2- (meth) acryloyloxyethyl acid phosphate, 2- (meth) acryloyloxypropyl acid phosphate Acid phosphate ester group-containing polymerizable monomers such as phosphate, 2- (meth) acryloyloxy-3-chloropropyl acid phosphate, 2- (meth) acryloyloxyethyl phenyl phosphate, and (5) vinylphenol, isopropenylphenol And phenolic hydroxyl group-containing polymerizable monomers such as allylphenol. In the present invention, one of these can be used alone, or two or more can be used in combination. In the present invention, among these polymerizable monomers (A), (meth) acrylic acid and (meth) acrylic acid ester are preferable, and methacrylic acid, acrylic acid and acrylic acid ester are more preferable. This is because the compound obtained by these increases the viscosity.

Other polymerizable monomers copolymerizable with the polymerizable monomer (A) include the following monomers.

(1) Styrene-based polymerizable monomers such as styrene, vinyltoluene, α-methylstyrene, chloromethylstyrene, (2) (meth) acrylamide, N-monomethyl (meth) acrylamide, N-monoethyl (meth) ) (Meth) acrylamide-based polymerizable monomers such as acrylamide, N, N-dimethyl (meth) acrylamide,
(3) Esters of methacrylic acid such as methyl methacrylate, ethyl methacrylate, butyl methacrylate and the like, and alcohols having 1 to 18 carbon atoms (excluding cyclic alcohols), and acrylic acid and alcohols having 4 to 18 carbon atoms ( (Excluding cyclic alcohols) and (meth) acrylic acid ester-based polymerizable monomers, and (4) cyclohexyl group-containing polymerizable monomers such as cyclohexyl (meth) acrylate: (meth) acrylic acid 2 -Hydroxy group-containing (meth) acrylate-based polymerizable monomers which are monoesters of (meth) acrylic acid and polypropylene glycol such as hydroxyethyl and 2-hydroxypropyl (meth) acrylate, (5) polyethylene glycol (Meth) acrylic ester and other polyethylene glycol chain-containing polymerizable monomers (but not acrylic Except for the 2-hydroxyethyl),
(6) basic polymerizable monomers such as dimethylaminoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylamide, dimethylaminopropyl (meth) acrylamide, vinylpyridine, and vinylimidazole;
(7) crosslinkable (meth) acrylamide-based polymerizable monomers such as N-methylol (meth) acrylamide, N-butoxymethyl (meth) acrylamide, (8) vinyltrimethoxysilane, vinyltriethoxysilane, γ- ( (9) Hydrolyzable silicon group-containing polymerizable monomers such as methacryloylpropyltrimethoxysilane, vinyltris (2-methoxyethoxy) silane and allyltriethoxysilane; and (9) glycidyl (meth) acrylate, acrylic glycidyl ether and the like. Epoxy group-containing polymerizable monomer,
(10) 2-isopropenyl-2-oxazoline, 2-
Oxazoline group-containing polymerizable monomers such as vinyl oxazoline; (11) aziridine group-containing polymerizable monomers such as (meth) acrylic acid-2-aziridinylethyl and (meth) acryloylaziridine; (12) fluorination (13) (meth) acrylic acid, ethylene glycol, 1,3-butylene glycol, diethylene glycol, 1,6-hexanediol, a halogen-containing polymerizable monomer such as vinyl, vinylidene fluoride, vinyl chloride, and vinylidene chloride; Polyfunctional having two or more polymerizable unsaturated groups in the molecule such as esterified product with polyhydric alcohol such as neopentyl glycol, polyethylene glycol, propylene glycol, polypropylene glycol, trimethylolpropane, pentaerythritol, dipentaerythritol, etc. (Meth) acrylate Compatible monomers, (14) polyfunctional (meth) acrylamide-based polymerizable monomers having two or more polymerizable unsaturated groups in the molecule such as methylenebis (meth) acrylamide, (15) diallyl phthalate, diallyl monomer Polyfunctional allyl-based polymerizable monomers having two or more polymerizable unsaturated groups in the molecule, such as acrylate and diallyl fumarate, (16)
In addition, vinyl acetate, (meth) acrylonitrile, N-
Examples thereof include vinylpyrrolidone, allyl (meth) acrylate, divinylbenzene, and the like. One of these can be used alone, or two or more polymerizable monomers can be used in combination. .

In the present invention, the proportion of the polymerizable monomer (A) in the monomer component is preferably from 3 to 80 mol%, more preferably from 10 to 60 mol%. When the proportion of the polymerizable monomer (A) is less than 3 mol%, the viscosity of the resulting compound is low, and when it exceeds 80 mol%, the polymerization stability may be reduced and the desired compound may not be obtained. is there.

The preparation of the powder for concrete separation reduction of the present invention is not particularly limited, and known methods such as bulk, solution, dispersion, suspension and emulsion polymerization can be applied. However, in emulsion polymerization, since polymerization proceeds in each of the particles present in the emulsion, a long-chain polymer is obtained,
Emulsion polymerization is particularly preferred in that a high molecular weight polymer can be obtained at high speed, and the uniformity and reproducibility of particles are excellent.

The emulsion polymerization may be carried out by a conventionally known emulsion polymerization method using a known emulsifier, a polymerization initiator, a chain transfer agent or the like, or may be a soap-free emulsion polymerization using no emulsifier.

Examples of the anionic surfactant include alkyl sulfate salts such as sodium dodecyl sulfate, potassium dodecyl sulfate and ammonium alkyl sulfate; sodium dodecyl polyglycol ether sulfate; sodium sulfolisinoate; sulfonated paraffin salts and the like. Alkyl sulfonates such as sodium dodecylbenzene sulfonate, alkali metal sulfate of alkali phenol hydroxyethylene; high alkyl naphthalene sulfonate; naphthalene sulfonic acid formalin condensate, sodium laurate, triethanolamine oleate, triethanolamine Fatty acid salts such as ahiate; polyoxyalkyl ether sulfates; poly Reactive anionic emulsifiers having a double bond such as xylethylene carboxylate sulfate, polyoxyethylene phenyl ether sulfate; dialkyl succinate sulfonate; polyoxyethylene alkylaryl sulfate, etc. can be used. .

Examples of the nonionic surfactant include polyoxyethylene alkyl ether; polyoxyethylene alkyl aryl ether; sorbitan aliphatic ester; polyoxyethylene sorbitan aliphatic ester; and glycerol monolaurate. Aliphatic monoglyceride; polyoxyethyleneoxypropylene copolymer, ethylene oxide and aliphatic amine,
Condensation products with amides or acids can be used.

Examples of the polymeric surfactant include:
Polyvinyl alcohol and modified products thereof; (meth) acrylic acid-based water-soluble polymer; hydroxyethyl (meth) acrylic acid-based water-soluble polymer; hydroxypropyl (meth) acrylic acid-based water-soluble polymer; .

When the above-mentioned emulsifier is used, the amount of the emulsifier used may be any as long as it can support the formation of the emulsion and can exhibit the desired function of stabilizing the formed emulsion. Therefore, the amount used is usually 0.1 to 10% by weight, preferably 1 to 10% by weight, based on the total amount of the polymerizable monomer.
5% by weight. If the amount of the emulsifier is less than 0.1% by weight, the stability of the emulsion polymerization is remarkably lost, a large amount of aggregates are generated, or the whole is aggregated. on the other hand,
If the amount of the emulsifier exceeds 10% by weight, it is not preferable because the setting of the cement composition is delayed or excessive air is entrained.

As the above-mentioned polymerization initiator, for example, persulfates such as potassium persulfate, ammonium persulfate and sodium persulfate, which are substances decomposed by heat to generate molecules having radicals; 2,2'-azobis ( Water-soluble azo compounds such as 2-amidinopropane) dihydrochloride and 4,4'-azobis (4-cyanopentanoic acid); a thermal decomposition initiator such as hydrogen peroxide; and a combination of an oxidizing agent and a reducing agent. Redox polymerization initiators such as hydrogen peroxide and ascorbic acid, t-butyl hydroperoxide and Rongalit, potassium persulfate and metal salts, and ammonium persulfate and sodium bisulfite to generate molecules having radicals in the oxidation-reduction reaction. And one or more of these can be used as a mixture.

The amount of the above-mentioned polymerization initiator used is not particularly limited as long as it can easily generate free radicals or ions and exhibit the desired function of initiating polymerization by a chain reaction. Is usually 0.
001 to 1% by weight, preferably 0.01 to 0.5% by weight
It is. If the amount of the polymerization initiator is less than 0.001% by weight, the polymerization will be remarkably slow or the polymerization will not start. On the other hand, when the amount of the polymerization initiator exceeds 1% by weight, the polymerization becomes unstable and aggregates increase.

Further, at the time of the above-mentioned emulsion polymerization, it is possible to appropriately add various known hydrophilic solvents and additives as described below as needed, as long as the physical properties are not adversely affected. . In preparing the emulsion polymer, a chain transfer agent may be used for controlling the molecular weight. Examples of the chain transfer agent include t-dodecyl mercaptan (1,1-dimethyldecane-1-thiol), 1-hexadecanethiol, 1,10-decanethiol, 1,8-dimercapto-3,6-dioxa. Octane, 1,5,10-decanetrithiol, 2-ethylhexyl mercaptopropionate, 2-mercaptoethyl octanoate, carbon tetrachloride, carbon tetrabromide, α-methylstyrene dimer, terpinolene,
α-terpinene, β-terpinene, dipentene, allyl alcohol, 2-amino-propanol and the like.

In order to promote emulsion polymerization, for example, reducing agents such as sodium pyrobisulfite, sodium sulfite, sodium bisulfite, ferrous sulfate, sodium formaldehyde sulfoxylate, L-ascorbic acid and salts thereof are used. Alternatively, for example, a chelating agent such as sodium ethylenediaminetetraacetate and glycine may be used in combination. In addition, for example, a dispersant such as sodium polyacrylate, an electrolyte such as potassium chloride, disodium phosphate, trisodium phosphate, diammonium phosphate, sodium pyrophosphate, sodium tripolyphosphate, a pH adjuster, and the like. They can be used together.

The method for adding the polymerizable monomer to the polymerization reaction system is not particularly limited, and any method such as a batch addition method, a monomer dropping method, a pre-emulsion method, a power feed method, a seed method, and a multi-stage addition method can be used. Can be used.

In the present invention, the number average molecular weight of the polymer obtained by the emulsion polymerization method by GPC is usually 100,000 to 10,000,000, preferably 500,000 to 2,000,000. When the number average molecular weight is less than 100,000, the separation reduction performance of the cement composition is remarkably reduced when the powder is subsequently made into a powder, and when the number average molecular weight exceeds 10,000,000, the flow of the cement composition is reduced. This is because sex is impaired.

In the present invention, the above emulsion polymer is dried, preferably by a dry pulverization method, a salting out method, a coagulation sedimentation method, a freeze drying method, a coagulation disintegration drying method, a spray drier method, a drum drier method, a belt drier or the like. Concrete separation reduction powder in the form of powder or slurry.

As a freeze-drying method, the emulsion polymerization reaction solution is rapidly cooled with liquid nitrogen or the like to freeze it, and then the frozen emulsion polymerization reaction solution is dried under reduced pressure using a freeze dryer to obtain 40 n
A powder having a particle size of m to 500 μm can be obtained.

As a spray drier method, the emulsion is atomized using a spray drier, mixed with hot air, and dried in the air to obtain a particle size of 100 μm.
m or less can be obtained.

In the drum dryer method, the emulsion polymerization reaction liquid is dried by using a drum dryer or a belt dryer so as to have a film thickness of 100 μm or less, and the resultant is pulverized and classified to obtain a powder of 300 μm or less. be able to.

Further, as an agglomeration-crushing-drying method, an emulsion polymerization reaction solution and an aqueous solution of an aggregating agent are added while kneading with a kneader to coagulate the entire emulsion polymerization reaction solution, and the mixture is further kneaded several times with ion-exchanged water. Wash and crush to about 2-3 mm. Thereafter, the powder is dried under reduced pressure at room temperature using a reduced-pressure dryer, and crushed and classified to obtain a powder having a size of 300 μm or less. As the flocculant, a sulfate band, calcium chloride, zinc chloride, a cationic polymer flocculant and the like can be used.

The concrete separation reducing powder of the present invention may contain other known additives. The compounding may be added to the above-mentioned emulsion polymerization reaction product, may be added at the time of powder operation, or may be added after the powder operation. As such a compoundable additive, there is an antifoaming agent. In particular, when an emulsifier is used in preparing a polymer contained in the concrete separation reducing powder, it is preferable to add an antifoaming agent. If an emulsifier is used during the preparation of the polymer, the effect of the emulsifier extends to the powder and foaming may occur during kneading of the cement. However, by adding an antifoaming agent, foaming can be suppressed and a homogeneous mortar or concrete can be produced.

In the present invention, the following compounds can be preferably used as such an antifoaming agent.

(1) Mineral oil-based antifoaming agent: kerosene, liquid paraffin, etc. (2) Fat / oil-based antifoaming agent: animal and vegetable oils, sesame oil, castor oil, alkylene oxide adducts thereof, etc., (3) fatty acid-based antifoaming agent Oleic acid, stearic acid, alkylene oxide adducts thereof, etc. (4) Fatty acid ester antifoaming agents: glycerin monoricinoleate, alkenyl succinic acid derivatives, sorbitol monolaurate, sorbitol trioleate, natural wax, etc. ) Oxyalkylene antifoaming agents: polyoxyalkylenes such as (poly) oxyethylene (poly) oxypropylene adduct; diethylene glycol heptyl ether;
Polyoxyethylene oleyl ether, polyoxypropylene butyl ether, polyoxyethylene polyoxypropylene 2-ethylhexyl ether, having 12 to 12 carbon atoms
(Poly) oxyalkyl ethers such as oxyethylene oxypropylene adduct to 14 higher alcohols; (poly) oxyalkylene (alkyl) aryl ethers such as polyoxypropylene phenyl ether and polyoxyethylene nonyl phenyl ether; 4,7,9
-Tetramethyl-5-decyne-4,7-diol, 2,
5-dimethyl-3-hexyne-2,5-diol, 3-
Acetylene ethers obtained by addition-polymerizing an alkylene oxide to an acetylene alcohol such as methyl-1-butyn-3-ol; (poly) oxyalkylene fatty acid esters such as diethylene glycol oleate, diethylene glycol laurate, and ethylene glycol distearate (Poly) oxyalkylene sorbitan fatty acid esters such as polyoxyethylene sorbitan monolaurate and polyoxyethylene sorbitan trioleate; (poly) such as sodium polyoxypropylene methyl ether sulfate and sodium polyoxyethylene dodecyl phenol ether sulfate Oxyalkylene alkyl (aryl) ether sulfates; (poly) oxyethylene stearyl phosphate, etc. (Poly) oxyalkylenealkyl phosphates; (poly) oxyalkylenealkylamines such as polyoxyethylene laurylamine; polyoxyalkyleneamides, etc. (6) alcohol-based antifoaming agents: octyl alcohol, hexadecyl alcohol, acetylene Alcohols, glycols, etc.

(7) Amide-based defoamer: acrylate polyamine, etc. (8) Phosphate ester-based defoamer: tributyl phosphate, sodium octyl phosphate, etc. (9) Metal soap-based defoamer: aluminum stearate
(10) silicone-based antifoaming agent: dimethyl silicone oil,
Examples include silicone paste, silicone emulsion, organically modified polysiloxane (polyorganosiloxane such as dimethylpolysiloxane), fluorosilicone oil and the like.
Of these, oxyalkylene-based and silicone-based antifoaming agents are preferred.

The amount of addition of these defoamers was 1
1000 to 1 g / m ³ per m ³ , more preferably 500
To ³ g / m ³ , particularly preferably 300 to 5 g / m ³ . If the amount is less than 1 g / m ^3, it is difficult to obtain the defoaming effect, and if it exceeds 1000 g / m ³ , the effect of reducing the material separation is reduced.

The concrete separation reducing powder of the present invention comprises:
When used in the form of a dry powder or slurry, it is usually 40 nm to 500 μm, preferably 0.1 to 300 μm.
Suitably, a particle size of μm is formed. When the particle size is less than 40 nm, the bulkiness is high and the particles are easily scattered in the air, so that handling becomes difficult. On the other hand, the particle size is 500 μm
If it exceeds, it does not dissolve quickly, so it takes a long time to obtain sufficient viscosity and separation resistance. This allows
Concrete productivity is reduced, and fine adjustment of fluidity and the like depending on the amount of addition becomes considerably difficult.

The concrete separation reducing powder of the present invention comprises:
It does not dissolve in acidic or neutral water, but is characterized by the fact that the group of the monomer enhances the hydrophilicity in alkaline aqueous solutions such as concrete and cement paste, and the powder dissolves or swells to a high viscosity. . In order to show the flowability and separation resistance of a suitable cement composition, the concrete separation reducing powder of the present invention has a flow of 400 to 800 mm in the test described in JIS A1101.

The second aspect of the present invention is a method for producing concrete, comprising adding the above-mentioned powder for reducing concrete separation. Here, "concrete" refers to a composition containing at least water and cement or a hardened product thereof.As a cement composition, mortar obtained by kneading sand or the like which is fine aggregate to cement, further contains pebbles and the like. It shall include the concrete that has been laid. Therefore, using the powder for reducing concrete separation of the present invention, cement compositions such as high-fluidity concrete, underwater non-separable concrete, sprayed concrete, upside down concrete, ground injection (improvement) method, concrete molding, shield method, etc. object,
It can be used for mortar, concrete and the like.

Here, the cement is not particularly limited as long as it can be used for paste, mortar or concrete. For example, ordinary, fast, ultra fast, moderate heat, white, etc. And various cements such as portland cement, belite-rich cement, alumina cement, fly ash cement, blast furnace cement, silica cement, various mixed cements, etc., as well as hydraulic materials other than cement such as gypsum.

The amount of cement in the powder for reducing concrete separation is appropriately determined according to the purpose of use, application, etc., but is generally desired for cement compositions such as concrete. In order to provide various properties such as viscosity increase and uniformity, cement is used in an amount of 150 to 700 kg / m ³ , preferably 200 to 650 kg / m ³ , more preferably 250 to 700 kg / m ³ per 1 m ^{3 of} the cement composition used.
Preferably, it contains 600 kg / m ³ . If the cement content is less than 150 kg / m ³ , sufficient strength cannot be obtained due to the small amount of cement. On the other hand, when the content of the cement exceeds 700 kg / m ³ , the strength by the cement is obtained, but the unit bone material is reduced.
As a result, the strength of the entire cement composition such as concrete is not sufficient.

The above-mentioned fine aggregate refers to an aggregate containing a 10 mm net sieve as a whole and a 5 mm net sieve at 85% by weight or more. Specifically, for example, river sand, mountain sand, crushed sand,
Sea sand, fly ash, artificial lightweight aggregate and the like can be mentioned, and these can be used alone or in an appropriate combination of two or more.

The amount of the fine aggregate to be compounded is
Although it is appropriately determined according to the use and the like, usually, in order to have various properties such as fluidity and uniformity generally desired for a cement composition such as mortar or concrete, a cement composition to be used is used. 1m ³ per fine aggregate 500 to 1
500 kg / m ³ , preferably 550-1200 kg /
m ³ , more preferably 600 to 1000 kg / m ³ . 500kg fine aggregate content
If it is less than / m ³ , the amount of coarse bone material increases and material separation easily occurs. On the other hand, the content of the fine aggregate is 1500
If the amount exceeds kg / m ³ , the separation resistance will occur and the fluidity will be impaired, and the strength will also decrease due to the decrease in unit bone material.

The above-mentioned coarse aggregate refers to an aggregate that becomes 85% by weight or more in a 5-mm mesh sieve, and specifically includes, for example, river gravel, mountain gravel, crushed stone, sea sand, chestnut stone, blast furnace slag crushed stone, and the like. Light natural gravel, artificial lightweight aggregate, and the like can be used as natural lightweight aggregates, and these can be used alone or in an appropriate combination of two or more.

The amount of the coarse aggregate to be used depends on the purpose of use,
Although it is appropriately determined according to the use and the like, usually, in order to have various properties such as fluidity and uniformity generally desired for a cement composition such as mortar or concrete, a cement composition to be used is used. 1m ³ per, the coarse aggregate 500 to 1
500 kg / m ³ , preferably 550-1200 kg /
m ³ , more preferably 600 to 1000 kg / m ³ . 500kg of coarse aggregate content
If it is less than / m ³ , the amount of unit coarse bone material is reduced, and sufficient strength is not obtained. On the other hand, when the content of the coarse aggregate is 150
If it exceeds 0 kg / m ³ , material separation is likely to occur.

Further, the mixing amount of the water, that is, the unit water amount is not particularly limited, but the concrete 1
A unit water volume of 120 to 200 kg / m ³ per m ³ is recommended. In addition, it is preferable that the compounding amount of the cement and the water is adjusted in a range of water / cement ratio = 20 to 70, preferably 30 to 60.

The concrete separation reducing powder of the present invention comprises:
When producing a cement composition, other cement additives can be used in combination. Examples of such cement additives include a cement water reducing agent, a cement dispersant, and a cement AE agent. Among these, it is particularly preferable to use together with a cement water reducing agent. The reason is that, by adding the cement water reducing agent into the mixing system and kneading it, it is possible to prepare a simple and reliable cement composition having excellent work efficiency.

Such a conventionally known optional cement water reducing agent is not particularly limited to its name, but is a surface active agent which adsorbs on the surface of cement particles and causes repulsion between them. Any material can be used as long as the unit water content of the cement composition such as concrete can be reduced and the strength can be increased. In addition, those having other functions, such as an AE water reducing agent also having an air entraining function, a high-performance water reducing agent capable of greatly reducing the water-cement ratio to obtain a cement composition such as high-strength concrete. A high-performance water reducing agent used in cement compositions such as concrete for fluidization, which has the effect of maintaining high workability (workability) for a certain period of time while maintaining the quality of cement compositions such as concrete and kneaded concrete. It may be a certain fluidizing agent or the like. In addition, a wide variety of cement water reducing agents, AE water reducing agents, high performance water reducing agents, high performance AEs developed to date
What is called a water reducing agent, superplasticizer or cement dispersant, and even if it is described only as a cement or concrete admixture, what is included in the cement water reducing agent based on its components It can be widely applied.

For example, lignin sulfonate; polyol derivative; naphthalene sulfonic acid formalin condensate; melamine sulfonic acid formalin condensate; polystyrene sulfonate; aminoaryl sulfonic acid-phenol-formaldehyde condensate as disclosed in JP-A-1-113419. A copolymer of a polyalkylene glycol mono (meth) acrylate compound and a (meth) acrylic compound and / or a salt thereof as component (a) as disclosed in JP-A-7-267705; (b) a copolymer of a polyalkylene glycol mono (meth) allyl ether compound and maleic anhydride and / or a hydrolyzate and / or a salt thereof as a component; and (c) a polyalkylene glycol mono (meth) allyl as a component. Ether compounds and polyal Dispersant for cement comprising a copolymer of maleic acid ester of lenglycol compound and / or a salt thereof. Polyalkylene glycol ester of (meth) acrylic acid and (meth) acrylic acid as A component as disclosed in Japanese Patent Publication No. 2508113. Copolymer with acid (salt),
A concrete admixture comprising a specific polyethylene glycol polypropylene glycol compound as the B component and a specific surfactant as the C component, JP-A-62-2169.
50 (poly) glycol (meth) acrylic acid polyethylene (propylene) glycol ester or polyethylene (propylene) glycol mono (meth) allyl ether, (meth) allyl sulfonic acid (salt), (meth) acrylic acid (salt) As described in Japanese Patent Application Laid-Open No. 1-227657, polyethylene (propylene) glycol ester of (meth) acrylic acid, (meth) allylsulfonic acid (salt),
Copolymer of (meth) acrylic acid (salt), Tokuho 5
From polyethylene (propylene) glycol ester of (meth) acrylic acid, (meth) allylsulfonic acid (salt) or p- (meth) allyloxybenzenesulfonic acid (salt) or (meth) acrylic acid (salt) as in 36376 A copolymer of polyethylene glycol mono (meth) allyl ether and maleic acid (salt) as disclosed in JP-A-4-149056; a polyethylene glycol ester of (meth) acrylic acid as disclosed in JP-A-5-170501; (Meth) allylsulfonic acid (salt), (meth) acrylic acid (salt), alkanediol mono (meth) acrylate, polyalkylene glycol mono (meth) acrylate, α, β-unsaturated monomer having an amide group in the molecule Copolymer consisting of a polymer, polyethylene glycol mono (JP-A-6-191918) (Meth) allyl ether, polyethylene glycol mono (meth) acrylate, (meth)
Alkyl acrylate, (meth) acrylic acid (salt), (meth) allyl sulfonic acid (salt) or p-
A copolymer composed of (meth) allyloxybenzenesulfonic acid (salt), a copolymer of alkoxypolyalkylene glycol monoallyl ether and maleic anhydride as described in JP-A-5-43288, or a hydrolyzate or a salt thereof; As disclosed in JP-B-58-38380, a copolymer comprising polyethylene glycol monoallyl ether, maleic acid, and a monomer copolymerizable with these monomers, or a salt or ester thereof, as in JP-B-59-18338. Polyalkylene glycol mono (meth) acrylate monomers, (meth) acrylate monomers, and copolymers composed of monomers copolymerizable with these monomers, (Meth) acrylic acid ester having a sulfonic acid group such as -119147 and copolymerizable therewith if necessary Of a copolymer comprising a monomer or a salt thereof, or a copolymer of an alkoxypolyalkylene glycol monoallyl ether and maleic anhydride with a polyoxyalkylene derivative having an alkenyl group at a terminal, as disclosed in JP-A-6-271347. Reactant, JP-A-6-
Polycarboxylic acids (salts) such as an esterification reaction product of a copolymer of alkoxypolyalkylene glycol monoallyl ether and maleic anhydride with a polyoxyalkylene derivative having a hydroxyl group at a terminal such as 298555; A plurality of these known cement water reducing agents can be used in combination.

The mixing amount of the concrete separation reducing powder of the present invention and the cement water reducing agent cannot be uniformly defined because the appropriate amount varies depending on the kind used and the like.
The water-reducing action that is the purpose of the use is usefully exhibited, and the effect may be reduced by increasing the unit water amount of the cement composition such as concrete by the action and increasing the strength within a range in which the effect of increasing the strength can be usefully expressed. There is no particular limitation.

In the present invention, when producing concrete,
Other additives can be used in combination with the concrete separation reducing agent of the present invention. The following compounds can be used as additives. Such a compound may be used together with the above water reducing agent.

(1) Water-soluble high molecular substances: polyoxyethylene or polyoxypropylene polymers such as polyethylene glycol and polypropylene glycol or copolymers thereof; methylcellulose, ethylcellulose, hydroxymethylcellulose, hydroxyethylcellulose, carboxymethylcellulose Nonionic cellulose ethers such as carboxyethylcellulose and hydroxypropylcellulose; yeast glucan, xanthan gum, and β-1,3 glucans (either linear or branched; for example, curdlan; Polysaccharides produced by microbial fermentation such as baramiron, bakiman, scleroglucan, laminaran, etc.); polyacrylamide; polyvinyl alcohol; starch; starch phosphate; Sodium acid salt; gelatin; a copolymer of acrylic acid having an amino group in the molecule and a quaternary compound thereof; (2) a retarder: gluconic acid, glucoheptonic acid, arabonic acid, malic acid or citric acid, and Oxycarboxylic acids such as inorganic salts or organic salts such as sodium, potassium, calcium, magnesium, ammonium, and triethanolamine; monosaccharides such as glucose, fructose, galactose, saccharose, xylose, abitose, repose, isomerized sugar; Oligosaccharides such as sugars and trisaccharides, or oligosaccharides such as dextrin, or polysaccharides such as dextran; saccharides such as molasses containing them; sugar alcohols such as sorbitol; magnesium silicofluoride; phosphoric acid and its salts or borates Acid esters; aminocarboxylic acids and salts thereof; alkalis Soluble protein; humic acid; tannic acid, phenols, polyhydric alcohols such as glycerin;
Phosphonic acids such as aminotri (methylenephosphonic acid), 1-hydroxyethylidene-1,1-diphosphonic acid, ethylenediaminetetra (methylenephosphonic acid), diethylenetriaminepenta (methylenephosphonic acid) and their alkali metal salts and alkaline earth metal salts And its derivatives, etc. (3) Early strength agents / promoting agents: Soluble calcium salts such as calcium chloride, calcium nitrite, calcium nitrate, calcium bromide, calcium iodide; chlorides such as iron chloride, magnesium chloride; sulfates Potassium hydroxide; sodium hydroxide; carbonate; thiosulfate; formate such as formic acid and calcium formate; alkanolamine; alumina cement; calcium aluminate silicate, etc. (4) AE agent: resin soap, saturated or unsaturated Fatty acids, sodium hydroxystearate, lauryl sal Eto, ABS (alkylbenzenesulfonic acid), LAS (linear alkyl benzene sulfonic acid), alkane sulfonates,
Polyoxyethylene alkyl (phenyl) ether, polyoxyethylene alkyl (phenyl) ether sulfate or salt thereof, polyoxyethylene alkyl (phenyl) ether phosphate or salt thereof, protein material, alkenyl sulfosuccinic acid, α-olefin sulfonate, etc. .

(5) Other surfactants: 6 to 30 per molecule such as octadecyl alcohol and stearyl alcohol.
Alicyclic monohydric alcohol having 6 to 30 carbon atoms in a molecule such as aliphatic monohydric alcohol having two carbon atoms, abiethyl alcohol, etc., and 6 to 30 carbon atoms in a molecule such as dodecyl mercaptan (E.g., alkylphenol having 6 to 30 carbon atoms in the molecule such as monovalent mercaptan, nonylphenol and the like) amine having 6 to 30 carbon atoms in the molecule such as dodecylamine and the like, such as lauric acid and stearic acid Polyalkylene oxide derivatives in which an alkylene oxide such as ethylene oxide or propylene oxide is added in an amount of 10 mol or more to a carboxylic acid having 6 to 30 carbon atoms; and may have an alkyl group or an alkoxy group as a substituent. Alkyl diphenyl ethers in which two phenyl groups having a sulfone group are ether-bonded Sulfonates; various anionic surfactants; various cationic surfactants such as alkylamine acetate and alkyltrimethylammonium chloride; various nonionic surfactants; various amphoteric surfactants; and (6) waterproofing agents: fatty acids ( Salt), fatty acid esters, fats and oils,
Silicon, paraffin, asphalt, wax, etc. (7) Rust inhibitor: Nitrite, phosphate, zinc oxide, etc. (8) Crack reducing agent: Polyoxyalkyl ethers; 2-methyl-2,4-pentanediol (9) Expanding agents; ettringite-based, coal-based, etc. Other known additives include cement wetting agents, thickening agents, separation reducing agents, flocculants, drying shrinkage reducing agents, and strength enhancement. Agent, self-leveling agent, rust inhibitor, coloring agent, fungicide,
Examples thereof include blast furnace slag, fly ash, cinder ash, clinker ash, husk ash, silica fume, silica powder, gypsum, and the like, and a plurality of these known additives can be used in combination.

The appropriate amount of the above-mentioned additives which can be blended varies depending on the intended use and the kind used, and can be appropriately selected. It has useful properties such as thickening action, material separation reducing action, etc.
Concrete and mortar, if blending a more effective amount within the range in which the effect excellent in workability at the time of the preparation of the cement composition such as cement paste can be usefully expressed,
It is not particularly limited, and can be blended in a known amount.

The powdery additives described above may be preliminarily blended with the polymer, which is an essential component of the present invention, as one component of the powder for reducing separation of the present invention. The amount of the polymer which is an essential component of the present invention is 10 to 0.0001 with respect to the cement in the concrete to be produced.
% By weight, and the other components blended at this time can be blended in such an amount that the physical properties such as fluidity, strength, and effective time of the concrete are not adversely affected.

Next, the method of preparing the cement composition of the present invention will be described. However, the method is not particularly limited as long as the concrete separation reducing powder is added to at least water and cement. Applicable.

As a concrete example, when preparing a mortar or concrete as a cement composition, for example, first, (1) a fine aggregate such as cement and sand and a powder for separation reduction of the present invention are suitably used. Pour into the mixer and knead. Thereby, the fine aggregate and the cement are uniformly mixed.

(2) Next, kneading water and a cement admixture such as a cement water reducing agent and an antifoaming agent are added to the fine aggregate / cement prepared by the empty kneading in (1) and kneaded. By the kneading, a uniform mortar is prepared. The above is the method of preparing the mortar.

(3) If necessary, a concrete can be prepared by adding coarse aggregate such as gravel to the mortar prepared by the kneading in the above (2) and further kneading it.

In the present invention, in addition to the method for preparing a cement composition according to the above-described procedure, a cement composition (here, cement) after kneading cement, kneading water, and, if necessary, aggregate may be used. A method of post-adding the cement admixture of the present invention to a mixture containing a cement composition other than the admixture), dispersing or dissolving the cement admixture of the present invention in all or a part of the kneading water used for kneading. Then, a method of kneading cement and aggregate can be applied.

As means (apparatus) for kneading these cement compositions in the above-mentioned mixing system,
Ability to knead cement and aggregate, etc., and ability to knead sufficiently by adding a cement admixture or coarse aggregate containing a cement water reducing agent or a cement additive to these composition components Is not particularly limited as long as it has the following, and various mixers (mixers) conventionally used for preparing such cement compositions such as concrete can be applied as they are, for example, A pan-type forced kneading mixer, a horizontal uniaxial type, a horizontal biaxial type, a drum type, a tilting type, a continuous type mixer and the like can be used.

[0069]

EXAMPLES Examples of the present invention will be shown below, but these are given for illustrative purposes and do not limit the spots of the present invention. In the following, parts and% are parts by weight,
It represents% by weight.

Example 1 A flask equipped with two dropping funnels, a stirrer, a nitrogen inlet tube, a thermometer and a cooler was charged with 327 parts of ion-exchanged water and 4 parts of Hytenol N-08 (Daiichi Kogyo Seiyaku Co., Ltd.). Was added, and Hytenol N-08 was completely dissolved at 72 ° C under stirring. Nitrogen was gently flowed at an internal temperature of 72 ° C., and the inside of the flask was replaced with nitrogen. After sufficient nitrogen substitution, methacrylic acid 105 prepared in advance was dropped from the dropping funnel.
30 parts of a pre-emulsion mixture obtained by vigorously stirring 300 parts of a pre-emulsion mixture, 195 parts of methyl acrylate, and 300 parts of a 1.6% hytenol N-08 aqueous solution, were stirred for 5 minutes. Then
1 part of a 5% aqueous solution of sodium bisulfite and 4 parts of a 1% aqueous solution of ammonium persulfate are added, and the internal temperature is kept at 72 ° C.
Stirring was continued for 0 minutes to perform initial polymerization. The remaining 570 parts of the pre-emulsion mixture and 64 parts of 1% ammonium persulfate were added dropwise thereto over 2 hours. After dropping,
The temperature was raised to 80 ° C., and stirring was continued for 1 hour, followed by cooling to complete the polymerization, thereby obtaining an emulsion having a nonvolatile content of 30.8%.

Next, 100 parts by weight of the emulsion was placed in an eggplant-shaped flask, and the emulsion was frozen on the inner wall of the eggplant-shaped flask while rotating the eggplant-shaped flask in an insulated container containing liquid nitrogen. After the emulsion was frozen, the eggplant-shaped flask was set in a freeze dryer and dried under reduced pressure. Drying of the emulsion was completed in about 6 hours. As a result, a powder for concrete separation reduction having an average particle size of 0.5 μm was obtained.

[0072]

[Table 1]

Example 2: Method for preparing a cement composition (concrete) using a cement additive Ordinary Portland cement (Chichibu Onoda cement, specific gravity 3.16) as cement and Oigawa-based land sand (specific gravity 2) as fine aggregate .6
2, FM2.71) and crushed hard sandstone from Ome (specific gravity 2.64, MS 20 mm) as coarse aggregate.

As a cement dispersing agent, a commercially available naphthalenesulfonic acid formalin condensate (Mighty 150, manufactured by Kao Corporation) is used with a fixed cement weight of 1.2% by weight.
The powder for concrete separation reduction obtained in Example 1 was used. In order to adjust the amount of air, a powder defoamer (manufactured by San Nopco Co., Ltd .; Nopco H-77P, 40 g / m ³ per 1 m ³ of concrete) was used.

The compounding conditions of the cement composition (here, concrete) were such that the unit cement amount was 500 kg / m ³ ,
The unit water amount was 165 kg / m ³ and the fine aggregate ratio was 45%.

Concrete was prepared according to the following procedure under the above-mentioned raw material and concrete mixing conditions.

First, 44.2 kg of fine aggregate and 25.0 kg of ordinary Portland cement were charged into a 50-liter pan-type forced kneading mixer, and kneaded for 10 seconds. 8.11 kg of kneading water containing the cement dispersant was added to the fine aggregate / cement prepared above and kneaded, and the time until the cement composition became uniform was measured. After the cement composition became uniform, kneading was further continued for 30 seconds each. Thereafter, 44.2 kg of the coarse aggregate was added to the cement composition prepared above, and the mixture was further kneaded for 90 seconds to produce concrete. The performance evaluation of the concrete was based on a slump value and a flow value, and the measurement was performed in accordance with Japanese Industrial Standards (JIS A 1101). Table 2 shows the results.

Comparative Example 1 Concrete was produced in the same manner as in Example 2 except that an emulsion before freezing of the powder was used instead of the powder for concrete separation reduction of Example 1. Table 2 shows slump values and flow values performed in the same manner as in Example 2.

[0079]

[Table 2]

[0080]

Industrial Applicability The powder for concrete separation reduction according to the present invention contains a polymerizable monomer having a group whose hydrophilicity is increased by an alkaline substance in the presence of water. The effect of concrete separation was reduced by increasing the viscosity. The concrete separation reducing powder exhibits the same rapid concrete separation reducing effect as that of the emulsion before the powdering treatment, which is an emulsion before the powdering treatment. Was suppressed.

In addition, the addition of the concrete separation reducing powder of Example 1 was 0.02% by weight, so that the desired effects could be obtained. The amount was 0.06% by weight. 3 like this
The fact that the same effect can be obtained with the use of one-half the weight greatly reduces the burden associated with production and transportation, which is preferable.

Further, since the concrete separation reducing powder of the present invention is a powder and does not contain water, it can be mixed with cement in advance and can be treated as non-separable cement. That is, there is a feature that the handleability is superior to the emulsion. Moreover, the obtained concrete was a concrete having a uniform composition and excellent strength.

Claims (5)

[Claims] 1. A concrete separation reducing powder comprising a polymer obtained by polymerizing a monomer component containing a polymerizable monomer having a group whose hydrophilicity is enhanced by adding an alkaline substance in the presence of water. 2. The group whose hydrophilicity is enhanced includes a carboxyl group, a sulfonic acid group, a phenolic hydroxyl group, a phosphoric acid group, a carboxylic acid ester group which is easily hydrolyzed to form an acid group, a phosphoric acid ester group, and sulfuric acid. 2. The method according to claim 1, wherein said at least one ester group is selected from the group consisting of ester groups.
The powder for reducing concrete separation as described above. 3. The concrete separation reducing powder according to claim 1, wherein the polymerization is emulsion polymerization. 4. The powder for reducing concrete separation according to claim 1, further comprising an antifoaming agent. 5. A method for producing concrete, comprising adding the powder for reducing concrete separation according to any one of claims 1 to 4.