JP4911759B2 - Method for preparing concrete - Google Patents

Description

  The present invention relates to a method for preparing concrete, and more particularly to a method for preparing concrete using fly ash containing unburned carbon at a high concentration of 8 to 25% by mass. In recent years, the amount of fly ash generated, especially the amount of fly ash generated as coal ash in coal-fired power plants, has increased. Such fly ash generated in a coal-fired power plant contains unburned carbon in a high concentration of 8 to 25% by mass, and has a characteristic that the variation in the concentration of unburned carbon varies depending on the power plant in which it is generated. . The present invention relates to a method for preparing concrete using fly ash containing unburned carbon such as fly ash generated in a coal-fired power plant at a high concentration of 8 to 25% by mass.

  When concrete is prepared using fly ash containing unburned carbon at a high concentration of 8 to 25% by mass, 1) the amount of high-performance water reducing agent or high-performance AE water reducing agent used to obtain the required fluidity increases. 2) Increase in fluidity over time (slump loss) 3) Increase in the amount of AE agent used to obtain the required amount of entrained air, resulting in increased cost 4 Various problems occur such as :) the resistance of the obtained cured body to freeze-thaw action is lowered, and 5) the strength of the obtained cured body is lowered.

In order to improve such various troubles, when preparing concrete using fly ash, a method using an air entraining agent as an admixture (for example, see Patent Documents 1 and 2), a method using a coal ash dispersant (for example, Patent Documents 3 to 5), methods using a skin surface improver (see, for example, Patent Documents 6 to 7), and the like are known. However, in these conventional methods, it goes without saying that these are carried out alone, and even when these are carried out in combination, those containing unburned carbon at a high concentration of 8 to 25% by mass as fly ash. If used, there is still a problem that various problems as described above occur.
Japanese Patent Laid-Open No. 1-157442 JP-A-8-295545 JP-A-11-157903 Japanese Patent Laid-Open No. 2001-213648 Japanese Patent Application Laid-Open No. 2003-267663 JP-A-5-132347 JP 2002-234663 A

  The problem to be solved by the present invention is that even when fly ash containing unburned carbon at a high concentration of 8 to 25% by mass is used for the preparation of concrete, 1) high to obtain the required fluidity Suppress the increase in the amount of performance water-reducing agent or high-performance AE water-reducing agent, 2) prevent the fluidity from decreasing over time (slump loss), and 3) the amount of AE agent used to obtain the required amount of entrained air 4) giving the hardened body obtained a strong resistance to freeze-thaw action and 5) giving the obtained hardened body a sufficient strength. It is in providing a method of preparation.

  Accordingly, as a result of researches to solve the above-mentioned problems, the present inventors have found that when preparing concrete using fly ash containing unburned carbon at a high concentration of 8 to 25% by mass, such fly ash is used. It has been found that it is correct and suitable to use a predetermined unit amount, and to use an admixture containing specific three components in a predetermined ratio with respect to the cement.

That is, in the present invention, when preparing concrete using fly ash containing unburned carbon at a high concentration of 8 to 25% by mass, the fly ash is used so that the unit amount is 40 to 100 kg / m ^3. 62 to 89 mass% of the following A component, 10 to 35 mass% of the following B component, and 0.3 to 3 mass% of the following C component will be contained, and these three components in total The present invention relates to a method for preparing concrete, characterized in that the admixture to be contained in an amount of 100% by mass is used at a ratio of 0.1 to 3 parts by mass per 100 parts by mass of cement.

  Component A: 1) Graft copolymer obtained through the following first step and second step, 2) Graft copolymer salt obtained through the following third step, from the above 1) and 2) One or more selected.

  First step: maleic anhydride and monomers represented by the following chemical formula 1 are contained in a total of 95 mol% or more and maleic anhydride / the monomer = 50/50 to 65/35 (molar ratio). A step of radically polymerizing a radically polymerizable monomer mixture contained in a proportion in the absence of a solvent to obtain a copolymer having a mass average molecular weight of 5000 to 70000.

  Second step: The graft copolymer is obtained by graft-reacting the polyether compound represented by the following chemical formula 2 at a ratio of 0.05 to 5.0 parts by mass per 100 parts by mass of the copolymer obtained in the first step. Obtaining.

  Third step: A step of obtaining a graft copolymer salt by partially neutralizing or completely neutralizing the graft copolymer obtained in the second step with an alkali metal hydroxide.

In Chemical Formula 1 and Chemical Formula 2,
R ¹ : Methyl group or acetyl group R ² : Aliphatic hydrocarbon group having 8 to 20 carbon atoms A ¹ : Only ¹ to 150 oxyethylene units or 2 to 150 total oxyethylene units and oxypropylene in the molecule Residue obtained by removing all hydroxyl groups from a (poly) alkylene glycol having a (poly) oxyalkylene group composed of units A ² : composed of a total of 23 to 70 oxyethylene units and oxypropylene units in the molecule And a residue obtained by removing all hydroxyl groups from a polyalkylene glycol having a polyoxyalkylene group in which the oxyethylene unit and the oxypropylene unit are bonded in a block form

  Component B: Organic amine ethylene oxide adduct represented by the following chemical formula 3

In chemical formula 3,
R ³ : Aliphatic hydrocarbon group having 8 to 20 carbon atoms n, m: an integer of 1 or more and 4 ≦ n + m ≦ 12

  Component C: Organophosphate represented by the following chemical formula 4

In chemical formula 4,
R ⁴ : Aliphatic hydrocarbon group having 8 to 20 carbon atoms M ¹ , M ² : Hydrogen atom, alkali metal, alkaline earth metal, ammonium or organic amine

  In the concrete preparation method according to the present invention (hereinafter simply referred to as the method of the present invention), as will be described in detail later, fly ash, fine aggregate containing cement and unburned carbon at a high concentration of 8 to 25% by mass, In addition to coarse aggregate and water, concrete is prepared using specific admixtures. As a result, the admixture used in the present invention is composed of the three components of A component, B component and C component.

The component A of the admixture used in the method of the present invention is 1) a graft copolymer obtained through the first step and the second step, 2) a salt of the graft copolymer obtained through the third step, One or more selected from 1) and 2). Therefore, the component A includes 1) one or more selected from graft copolymers, 2) one or more selected from salts of graft copolymers, and 3) mixtures thereof.

  The first step is a step of obtaining a copolymer by radical polymerization of a radical polymerizable monomer mixture in the absence of a solvent. As the radical polymerizable monomer mixture, maleic anhydride and the monomer represented by Chemical formula 1 are contained in a total of 95 mol% or more and maleic anhydride / the monomer = 50/50 to 65/35 ( (Molar ratio), preferably 52/48 to 62/38 (molar ratio).

In the monomer represented by Chemical formula 1, A ^{1 in} Chemical formula ¹ includes: 1) All hydroxyl groups from (poly) ethylene glycol having (poly) oxyethylene groups composed only of oxyethylene units in the molecule. Residues removed 2) Excluding all hydroxyl groups from (poly) ethylene (poly) propylene glycol having (poly) oxyethylene (poly) oxypropylene groups composed of oxyethylene units and oxypropylene units in the molecule In the case of 2), the bonding mode of the oxyethylene unit and the oxypropylene unit may be either a random bond or a block bond, but the case of 1) is preferred. The number of repeating oxyalkylene units constituting A ¹ is ¹ to 150, preferably 10 to 90.

  Specific examples of the monomer represented by Chemical Formula 1 described above are: 1) α-allyl-ω-methyl- (poly) oxyethylene, 2) α-allyl-ω-methyl- (poly) oxyethylene (poly) ) Oxypropylene, 3) α-allyl-ω-acetyl- (poly) oxyethylene, 4) α-allyl-ω-acetyl- (poly) oxyethylene (poly) oxypropylene, and the like.

  The radical polymerizable monomer mixture used in the first step contains a total of 95 mol% or more of maleic anhydride and the monomer represented by Chemical Formula 1, in other words, other radical polymerizable monomer. The body can be contained within a range of 5 mol% or less. Such other radical polymerizable monomers include styrene, vinyl acetate, acrylic acid, acrylate, alkyl acrylate, methyl methacrylate, (meth) allyl sulfonic acid, (meth) allyl sulfonate, and the like. Can be mentioned.

  In the first step, a radical initiator is added to the radical polymerizable monomer mixture described above for radical polymerization to obtain a copolymer having a mass average molecular weight of 5000 to 70000, preferably 10,000 to 50000. In the present invention, the weight average molecular weight means the weight average molecular weight in terms of pullulan according to the GPC method. The radical polymerization is a method in which, for example, a radical polymerizable monomer mixture is charged into a reaction vessel, a radical initiator is added in a nitrogen atmosphere, and a radical polymerization reaction is performed at 60 to 90 ° C. for 5 to 10 hours. In order to control the radical polymerization reaction to obtain a desired copolymer, the type and amount of radical initiator and radical chain transfer agent, polymerization temperature, polymerization time, etc. are appropriately selected. As radical initiators, azo initiators such as azobisisobutyronitrile, 2,2′-azobis (4-methoxy2,4-dimethylvaleronitrile), benzoyl peroxide, lauroyl peroxide, cumene hydroperoxide And non-aqueous initiators.

  The second step is a step of obtaining a graft copolymer by graft reaction of the polyether compound represented by Chemical Formula 2 to the copolymer obtained in the first step.

In the polyether compound represented by Chemical formula 2, R ^{2 in} Chemical formula ^{2 is} as follows: 1) Octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, octadecyl group 8) a saturated aliphatic hydrocarbon group having 8 to 20 carbon atoms such as isoactadecyl group and doodecyl group, and 2) an unsaturated aliphatic hydrocarbon group having 8 to 20 carbon atoms such as decenyl group, tetradecenyl group, octadecenyl group and eicocenyl group. Among them, an aliphatic hydrocarbon group having 10 to 20 carbon atoms is preferable, and an unsaturated aliphatic hydrocarbon group having 12 to 18 carbon atoms is more preferable.

In the polyether compound represented by Chemical Formula 2, A ^{2 in} Chemical Formula 2 is a polysiloxane composed of oxyethylene units and oxypropylene units in the molecule and having the oxyethylene units and the oxypropylene units bonded in a block form. A residue obtained by removing all hydroxyl groups from a polyalkylene glycol having an oxyalkylene group. The total number of repeating oxyethylene units and oxypropylene units constituting A ² is 23 to 70, but is preferably 25 to 60. The polyether compound represented by the chemical formula 2 described above is a known compound that undergoes addition reaction of ethylene oxide and propylene oxide in a block form at a ratio of 23 to 70 mol in total with respect to 1 mol of an aliphatic alcohol having 8 to 20 carbon atoms. It can be synthesized by the method.

  In the second step, the ratio of 0.05 to 5 parts by mass, preferably 0.2 to 4 parts, of the polyether compound represented by Chemical Formula 2 as described above per 100 parts by mass of the copolymer obtained in the first step. Graft reaction is carried out at a ratio of parts by mass to obtain a graft copolymer. A known method can be applied to the graft reaction. For example, the copolymer obtained in the first step, the polyether compound represented by Chemical Formula 2, and a basic catalyst are charged into a reaction can, and after a nitrogen atmosphere, the graft reaction is performed at 100 ° C. for 4 to 6 hours. A graft copolymer can be obtained. Here, as the basic catalyst, a known catalyst used in the ring-opening ester reaction between an acid anhydride and an alcohol can be used. Among them, an amine catalyst is preferable, and a lower alkylamine is more preferable.

  The third step is a step in which the graft copolymer obtained in the second step is partially or completely neutralized with a basic compound to obtain a graft copolymer salt. Examples of such basic compounds are 1) alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, 2) alkaline earth metal hydroxides such as calcium hydroxide and magnesium hydroxide, 3) ammonia, triethanolamine. Amines such as alkali metal hydroxides are preferred.

  The B component of the admixture used in the method of the present invention is an organic amine ethylene oxide adduct represented by Chemical Formula 3. The organic amine ethylene oxide adduct represented by Chemical Formula 3 is obtained by adding ethylene oxide at a ratio of 4 to 12 moles with respect to 1 mole of primary alkyl or alkenylamine having 8 to 20 carbon atoms.

The C component of the admixture used in the method of the present invention is an organic phosphate represented by Chemical Formula 4. The organic phosphate ester represented by Chemical Formula 4 is an organic phosphate ester having an aliphatic hydrocarbon group having 8 to 20 carbon atoms, preferably an aliphatic hydrocarbon group having 10 to 16 carbon atoms. Such organophosphates include organophosphate monoesters when M ¹ and M ² in Chemical Formula 4 are hydrogen atoms, alkali metal salts of the organophosphate monoesters, alkaline earths of the organophosphate monoesters Metal salt, ammonium salt of organic phosphoric acid monoester, organic amine salt of organic phosphoric acid monoester, and organic phosphoric acid ester of component C includes alkali of organic phosphoric acid monoester as described above Metal salts are preferred.

The organophosphate ester represented by Chemical Formula 4 can be synthesized by a known method. For example, after reacting a higher alcohol having 8 to 20 carbon atoms with phosphoric anhydride and then recrystallizing with an organic solvent, the organic phosphoric acid mono-mono when M ¹ and M ^{2 in} Chemical Formula 4 are hydrogen. An ester can be synthesized, and an organic phosphoric acid monoester alkali metal salt can be synthesized by neutralizing the organic phosphoric acid monoester with an alkali metal hydroxide.

  The admixture used in the method of the present invention contains 62 to 89% by mass of the A component as described above, 10 to 35% by mass of the B component, and 0.3 to 3% by mass of the C component. These three components are contained so as to be 100% by mass in total. When the content ratio of each component deviates from these ranges, it becomes difficult for the concrete prepared using such an admixture to simultaneously have the desired multi-function described above.

  In the method of the present invention, cement, fly ash containing fine unburned carbon at a high concentration of 8 to 25% by mass, fine aggregate, coarse aggregate, water and an admixture as described above are mixed to prepare concrete. However, in this case, the admixture is used in an amount of 0.1 to 3 parts by mass, preferably 0.15 to 2 parts by mass, per 100 parts by mass of cement. When the amount of the admixture used is less than this, the prepared concrete has poor fluidity, and it becomes difficult to simultaneously provide the desired multi-function described above. On the contrary, even if the amount of the admixture used is larger than this, an effect commensurate with it cannot be obtained.

  The method for adding the admixture is not particularly limited. As the admixture, a premixed predetermined amount of each component may be used, or a predetermined amount of each component may be used separately. Normally, cement, fly ash containing a high concentration of unburned carbon, fine aggregate, and coarse aggregate are kneaded with a mixer, while kneading a premixed mixture of each component in advance. A method of diluting with mixed water and then kneading both is preferable.

In the method of the present invention, examples of the cement include various portland cements such as ordinary cement, early-strength cement, intermediate heat cement, sulfate resistant cement, and ordinary cement is preferable. The amount of cement used is not particularly limited, but is preferably used so that the unit amount is 200 to 400 kg / m ³ in order to sufficiently secure the initial strength.

In the method of the present invention, as fly ash, one containing unburned carbon at a high concentration of 8 to 25% by mass, for example, coal ash generated from a coal-fired power plant as described above is used. The effects of the present invention are particularly prominent when concrete is prepared using fly ash containing unburned carbon at a high concentration of 8 to 25% by mass. Such fly ash is used so that the unit amount is 40 to 100 kg / m ³ . This is for sufficiently securing the initial strength of the obtained cured product.

  In the method of the present invention, examples of the fine aggregate include river sand, mountain sand, sea sand, and crushed sand, and examples of the coarse aggregate include river gravel, crushed stone, and lightweight aggregate.

  In the method of the present invention, it is preferable that the concrete to be prepared is AE concrete having an entrained air amount of 3 to 6% by volume in order to make the obtained hardened body exhibit strong resistance to freezing and thawing. Such an entrained air amount can be prepared by adjusting the content ratio of the C component having a large influence on the entrained air amount among the A component, the B component, and the C component described above.

  In the method of the present invention, as described above, cement, fly ash, fine aggregate, coarse aggregate, water and an admixture containing 8 to 25% by mass of unburned carbon are mixed to produce concrete. In this case, within the range not impairing the effect of the present invention, in addition to the above-mentioned admixture, other additives such as a setting accelerator, a setting retarder, a waterproofing agent, an antiseptic, a rusting agent, etc. Additives can be used in combination.

  According to the method of the present invention described above, even when fly ash containing unburned carbon at a high concentration of 8 to 25% by mass is used, 1) a high-performance water reducing agent for obtaining required fluidity Suppress the increase in the amount of high-performance AE water reducing agent used, 2) prevent the fluidity from decreasing over time (slump loss), and 3) suppress the increase in the amount of AE agent used to obtain the required amount of entrained air. 4) giving the hardened body obtained strong resistance to freeze-thaw action, and 5) preparing concrete having the functions 1) to 5) at the same time of giving sufficient strength to the obtained hardened body. There is an effect that can be done.

  Hereinafter, in order to make the configuration and effects of the present invention more specific, examples and the like will be described. However, the present invention is not limited to the examples. In the following examples and the like, unless otherwise indicated,% means mass%, and part means mass part.

Test Category 1 (Synthesis of each component used for preparation of admixture)
Synthesis of graft copolymer (a-1) used as component A Maleic anhydride 120 g (1.2 mol) and α-allyl-ω-methyl-poly (n = 33) oxyethylene 1524 g (1.0 mol) Was uniformly dissolved while stirring, and the atmosphere was replaced with nitrogen. The temperature of the reaction system was kept at 70 ° C. in a warm water bath, and 3 g of azobisisobutyronitrile was added to initiate radical polymerization reaction. Further, 5 g of azobisisobutyronitrile was added in portions, and the radical polymerization reaction was continued for 4 hours to complete the reaction. When the obtained copolymer was analyzed, it was a mass average having a ratio of maleic anhydride / α-allyl-ω-methyl-polyoxyethylene (n = 33) = 55/45 (molar ratio) in terms of raw materials. The copolymer had a molecular weight of 26000. Next, 100 g of this copolymer and α-oleyl-ω-hydroxy-polyoxyethylene (n = 6) poly added in a block form at a ratio of 6 mol of ethylene oxide and 43 mol of propylene oxide to 1 mol of oleyl alcohol. 2.8 g of oxypropylene (m = 43) and 2 g of tributylamine as a catalyst were charged into a reaction vessel, and the atmosphere was replaced with nitrogen. While maintaining the temperature of the reaction system at 90 ° C., the graft reaction was continued for 4 hours to obtain a graft copolymer (a-1).

Synthesis of graft copolymers (a-2) to (a-4) and (r-1) to (r-5) used as component A In the same manner as the synthesis of graft copolymer (a-1), Graft copolymers (a-2) to (a-4) and (r-1) to (r-5) were synthesized.

-Synthesis of graft copolymer salt (a-5) used as component A 250 g of 40% aqueous solution of the above graft copolymer (a-1) was charged into a reaction vessel, and 10 g of 30% aqueous sodium hydroxide solution was stirred. Was gradually added to carry out a partial neutralization treatment to obtain a partially neutralized salt (a-5) of the graft copolymer. The degree of neutralization of the partially neutralized salt (a-5) of the graft copolymer was 50%.

-Synthesis of graft copolymer salt (a-6) A reaction vessel was charged with 250 g of a 40% aqueous solution of the graft copolymer (a-3), and 43 g of a 30% aqueous sodium hydroxide solution was gradually added while stirring. Then, a complete neutralization treatment was performed to obtain a graft copolymer salt (a-6). The contents of each of the graft copolymers synthesized above are summarized in Table 1.

In Table 1,
* 1: Part of the polyether compound or the like represented by Chemical Formula 2 grafted to 100 parts of the copolymer obtained in the first step * 2: Sodium hydroxide d-1: α-allyl-ω-methyl- Polyoxyethylene (n = 33)
d-2: α-allyl-ω-methyl-polyoxyethylene (n = 70)
d-3: α-allyl-ω-acetyl-polyoxyethylene (n = 10)
d-4: α-allyl-ω-acetyl-polyoxyethylene (n = 50)
e-1: Styrene f-1: α-Oleyl-ω-hydroxy-polyoxyethylene (n = 6) -polyoxypropylene (m = 43)
f-2: α-lauryl-ω-hydroxy-polyoxyethylene (n = 3) -polyoxypropylene (m = 32)
dr-1: α-allyl-ω-acetyl-polyoxyethylene (n = 160)
fr-1: α-lauryl-ω-hydroxy-polyoxyethylene (n = 15)
fr-2: α-oleyl-ω-hydroxy-polyoxyethylene (n = 50)

Test Category 2 (Preparation of admixture)
-Preparation of admixture (P-1) 75 parts of graft copolymer (a-1) synthesized in Test Category 1 as component A, 23 parts of laurylamine ethylene oxide adduct (b-1) as component B, and component C As an admixture (P-1), 2 parts of octyl phosphate monoester potassium salt (c-1) was mixed.

Preparation of Admixtures (P-1) to (P-12) and (R-1) to (R-14) In the same manner as Admixture (P-1), Admixtures (P-1) to (P-) 12) and (R-1) to (R-14) were prepared. The contents of the admixtures prepared above are summarized in Table 2.

In Table 2,
P-1 to P-12: Admixtures used in Examples R-1 to R-14: Admixtures used in Comparative Examples a-1 to a-6, r-1 to r-5: synthesized in Test Category 1 Graft copolymer etc. b-1: Ethylene oxide (4 mol) adduct of laurylamine b-2: Ethylene oxide (8 mol) adduct of laurylamine b-3: Ethylene oxide (12 mol) adduct of stearylamine c-1: Potassium salt of octyl phosphate monoester c-2: Sodium salt of tetradecyl phosphate monoester c-3: Sodium salt of dodecyl phosphate monoester * 3: Rosin salt AE agent (manufactured by Takemoto Yushi Co., Ltd.) Product name AE300)
* 4: Polycarboxylic acid-based high-performance AE water reducing agent (Brand name Tupol HP-8 manufactured by Takemoto Yushi Co., Ltd.)
* 5: Naphthalenesulfonic acid-based high-performance water reducing agent (trade name Pole Fine 510AN manufactured by Takemoto Yushi Co., Ltd.)

Test category 3 (Preparation and evaluation of concrete using fly ash containing unburned carbon in high concentration)
-Examples 1-15 and Comparative Examples 1-16
Under the compounding conditions shown in Table 3, a 50 L pan-type forced kneader was mixed with ordinary Portland cement (density = 3.16, brain value 3300), fly ash (produced by Chugoku Electric Power Mizushima Thermal Power Plant, density = 2.12 g / cm ³ , Blaine value 3650, unburned carbon amount 12.5%), fine aggregate (Oikawa water sand, density = 2.58 g / cm ³ ) and coarse aggregate (Okazaki crushed stone, density = 2.68 g / cm ³ ) Were put in order and kneaded for 15 seconds. Next, the admixture prepared in Test Category 2 was added together with water and kneaded so that the target slump was 18 ± 1 cm and the target air amount was in the range of 4 to 5%, thereby preparing concrete for each example. Table 4 summarizes the contents of the concrete prepared in each example, along with the amount of admixture used.

In Table 3,
* 6: Powder is the total amount of cement and fly ash

-Physical property evaluation of prepared concrete About the concrete prepared in each case, the air content, slump, and slump residual rate were calculated | required as follows, and the result was put together in Table 4 and shown. Moreover, about the hardened | cured material of the concrete prepared in each example, the compressive strength and the freeze-thaw resistance index were calculated | required as follows, and the result was put together in Table 5 and shown.

Air amount: Measured in accordance with JIS-A1128 for concrete immediately after mixing and concrete after standing for 90 minutes.
Slump: Measured according to JIS-A1101 simultaneously with the measurement of the air amount.
Slump residual ratio: (slump after standing for 90 minutes / slump just after mixing) × 100.
-Freeze-thaw durability index: About the concrete of each example, the numerical value calculated by the durability index of ASTM-C666-75 was shown using the value measured based on the appendix 2 of JIS-A1129. This numerical value indicates that the maximum value is 100, and the closer to 100, the better the resistance to freezing and thawing.
Compressive strength: The concrete of each example was measured at a material age of 7 days and a material age of 28 days in accordance with JIS-A1108.

In Table 4,
* 7: Admixture used for 100 parts of cement

Claims (5)

Upon unburned carbon to prepare a concrete with a fly ash containing a high concentration of 8 to 25 wt%, A components of such fly ash weight unit used to be a 40~100kg / m ^3, also under Symbol the 62-89 wt%, 10-35 wt% of component B described below and C the following ingredients will be contained in a proportion of 0.3 to 3 wt%, and 100% by weight of these three components in total A method for preparing concrete, wherein the admixture to be contained is used at a ratio of 0.1 to 3 parts by mass per 100 parts by mass of cement.
Component A: 1) Graft copolymer obtained through the following first step and second step, 2) Graft copolymer salt obtained through the following third step, from the above 1) and 2) One or more selected.
First step: maleic anhydride and monomers represented by the following chemical formula 1 are contained in a total of 95 mol% or more and maleic anhydride / the monomer = 50/50 to 65/35 (molar ratio). A step of radically polymerizing a radically polymerizable monomer mixture contained in a proportion in the absence of a solvent to obtain a copolymer having a mass average molecular weight of 5000 to 70000.
Second step: A graft copolymer is obtained by graft-reacting a polyether compound represented by the following chemical formula 2 at a ratio of 0.05 to 5 parts by mass per 100 parts by mass of the copolymer obtained in the first step. Process.
Third step: A step of partially or completely neutralizing the graft copolymer obtained in the second step with a basic compound to obtain a salt of the graft copolymer.

(In Chemical Formula 1 and Chemical Formula 2,
R ¹ : Methyl group or acetyl group R ² : Aliphatic hydrocarbon group having 8 to 20 carbon atoms A ¹ : Only ¹ to 150 oxyethylene units or 2 to 150 total oxyethylene units and oxypropylene in the molecule Residue obtained by removing all hydroxyl groups from a (poly) alkylene glycol having a (poly) oxyalkylene group composed of units A ² : composed of a total of 23 to 70 oxyethylene units and oxypropylene units in the molecule And a residue obtained by removing all hydroxyl groups from a polyalkylene glycol having a polyoxyalkylene group in which the oxyethylene unit and the oxypropylene unit are bonded in a block form)
Component B: Organic amine ethylene oxide adduct represented by the following chemical formula 3

(In chemical formula 3,
R ³ : an aliphatic hydrocarbon group having 8 to 20 carbon atoms, n, m: an integer of 1 or more and an integer satisfying 4 ≦ n + m ≦ 12 )
Component C: Organophosphate represented by the following chemical formula 4

(In chemical formula 4,
R ⁴ : aliphatic hydrocarbon group having 8 to 20 carbon atoms M ¹ , M ² : hydrogen atom, alkali metal, alkaline earth metal, ammonium or organic amine) The monomer represented by Chemical formula ¹ is a residue obtained by removing all hydroxyl groups from polyethylene glycol having a polyoxyethylene group in which A ^{1 in} Chemical formula ¹ is composed of a total of 10 to 90 oxyethylene units in the molecule. process for the preparation of concrete with a claim 1 Symbol mounting for the case is. In the polyether compound represented by Chemical Formula ² , R ^{2 in} Chemical Formula ² is an aliphatic hydrocarbon group having 10 to 20 carbon atoms, and A ² is a total of 25 to 60 oxyethylene units and oxypropylene in the molecule. The method for preparing concrete according to claim 1 or 2 , wherein the concrete is a residue obtained by removing all hydroxyl groups from a polyalkylene glycol having a polyoxyalkylene group composed of units. The organophosphate ester represented by Chemical formula ⁴ is the one in which R ^{4 in} Chemical formula ⁴ is an aliphatic hydrocarbon group having 10 to 16 carbon atoms, and M ¹ and M ² are alkali metals. The method for preparing concrete according to any one of items 1 to 3 . The method for preparing concrete according to any one of claims 1 to 4 , wherein the concrete is AE concrete having an air amount adjusted to 3 to 6% by volume of entrained air.