JP3423853B2 - Cement admixture and cement composition - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a cement admixture and a cement composition. More specifically, in a so-called cement mixture such as cement paste, mortar or concrete, the present invention relates to a slump holding type cement admixture that prevents the fluidity of the cement mixture from decreasing with time, and a cement composition containing the cement admixture. .

[0002]

2. Description of the Related Art Since the early deterioration of concrete structures became a social problem in 1981, it has been strongly demanded to reduce the amount of unit water in concrete to improve its workability and durability. Technological innovations are being actively carried out on cement dispersants that greatly affect the quality and performance of cement.

As a conventional method, an AE agent or AE is used.
Fluidity with a water reducing agent (hereinafter referred to as "slump")
A low fluidity concrete was manufactured in a plant, transported to a construction site by a ready-mixed concrete truck, and then a fluidizing agent was added to fluidize it to fluidize it to raise the slump to a predetermined value. . However, this construction method includes environmental problems such as noise and exhaust gas generated when a fluidizing agent is added to concrete by stirring with a ready-mixed concrete truck, the responsibility of the quality of the fluidized concrete obtained, the fluidized concrete. There were various problems such as a remarkable deterioration of the slump with time.

Therefore, so-called high-performance AE water-reducing agents that can be added in raw plants have been vigorously developed by each admixture manufacturer, and at present, naphthalene-based, aminosulfonic acid-based and polycarboxylic acid-based agents are commercially available. . Among them, the polycarboxylic acid type high-performance AE water reducing agent has an excellent feature that the highest water reducing rate can be obtained.
Under severe conditions of use such as transporting the obtained fresh concrete to a remote place in the summer, there is a problem that the slump loss may not be sufficiently suppressed, like other high performance AE water reducing agents.

[0005]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a cement admixture having excellent slump retention and a cement composition containing the cement admixture.

[0006]

[Means for Solving the Problems] The above-mentioned object is as follows (1)
Is achieved by (4).

(1) General formula (1)

[0008]

[Chemical 7]

(Wherein R ¹ represents a hydrogen atom or a methyl group, R ² O represents an oxyethylene group, R ³ represents a hydrogen atom or an alkyl group having 1 to 22 carbon atoms, and m represents an oxy group. The average number of moles of ethylene groups added, 1
Represents an integer of 97. ) The first polyethylene glycol (meth) acrylate (a) of 5 to 90% by weight, represented by the general formula (2)

[0010]

[Chemical 8]

(Wherein R ⁴ is a hydrogen atom or a methyl group, R ⁵ O is an oxyethylene group, R ⁶ is a hydrogen atom or an alkyl group having 1 to 22 carbon atoms, and n is an oxy group. It is the average number of added moles of ethylene groups, and is 4 to
It represents an integer of 100, and n ≠ m and n−m ≧ 3. ) 2nd polyethylene glycol (meth) acrylate (b) 5 to 90% by weight, represented by the general formula (3)

[0012]

[Chemical 9]

(Wherein R ⁷ represents a hydrogen atom or a methyl group, M ¹ represents a hydrogen atom, a monovalent metal atom, a divalent metal atom, an ammonium group or an organic amine group). 5 to 90% by weight of the monomer (c) and 0 to 50% by weight of another monomer (d) copolymerizable with these monomers (however, (a), (b),
The sum of (c) and (d) is 100% by weight. ) The first copolymer (A) and / or the first copolymer salt (B) obtained by further neutralizing the first copolymer (A) with an alkaline substance. A cement admixture with excellent slump retention.

(2) General formula (1)

[0015]

[Chemical 10]

(Wherein R ¹ is a hydrogen atom or a methyl group, R ² O is an oxyethylene group, R ³ is a hydrogen atom or an alkyl group having 1 to 22 carbon atoms, and m is an oxy group. The average number of moles of ethylene groups added, 1
Represents an integer of 97. ) The first polyethylene glycol (meth) acrylate (a) of 5 to 90% by weight, represented by the general formula (2)

[0017]

[Chemical 11]

(Wherein R ⁴ is a hydrogen atom or a methyl group, R ⁵ O is an oxyethylene group, R ⁶ is a hydrogen atom or an alkyl group having 1 to 22 carbon atoms, and n is an oxy group. It is the average number of added moles of ethylene groups, and is 4 to
It represents an integer of 100, and n ≠ m and n−m ≧ 3. ) 2nd polyethylene glycol (meth) acrylate (b) 5 to 90% by weight, represented by the general formula (3)

[0019]

[Chemical 12]

(Wherein R ⁷ represents a hydrogen atom or a methyl group, M ¹ represents a hydrogen atom, a monovalent metal atom, a divalent metal atom, an ammonium group or an organic amine group). 5 to 90% by weight of the monomer (c) and 0 to 50% by weight of another monomer (d) copolymerizable with these monomers (however, (a), (b),
The sum of (c) and (d) is 100% by weight. ) The first copolymer (A) and / or the first copolymer salt (B) obtained by further neutralizing the first copolymer (A) with an alkaline substance. A cement admixture having excellent slump retention, wherein the other monomer (d) is an ester of an aliphatic alcohol having 1 to 18 carbon atoms and (meth) acrylic acid as a component.

(3) A cement composition containing at least the cement admixture according to (1) or (2), cement and water.

(4) The cement according to the above (3), wherein the cement admixture is 0.01 to 1.0% by weight with respect to the cement, and the water / cement weight ratio is 0.15 to 0.7. Composition.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION First, the first cement admixture according to the present invention comprises a first copolymer (A) described below and / or the first copolymer (A) further treated with an alkaline substance. The main component is the first copolymer salt (B) obtained by the addition.

The first copolymer (A) has the general formula (1):
The first polyethylene glycol (meth) acrylate (a) represented by 5 to 90% by weight, preferably 5 to 70% by weight, more preferably 10 to 65% by weight, the second polyethylene represented by the general formula (2). Glycol (meth) acrylate (b) 5 to 90% by weight, preferably 1
0 to 90% by weight, more preferably 20 to 70% by weight,
Carboxylic acid-based monomer (c) represented by general formula (3) 5 to
90% by weight, preferably 5 to 40% by weight, more preferably 8 to 30% by weight, and 0 to 50% by weight, preferably 0 to 50% by weight of other monomer (d) copolymerizable with these monomers. It is derived at a ratio of 30% by weight (however, the total of (a), (b), (c) and (d) is 100% by weight). Further, the first copolymer salt (B) is
It is obtained by further neutralizing the first copolymer (A) with an alkaline substance.

General formula (1)

[0026]

[Chemical 13]

In the general formula (1), R ¹ represents a hydrogen atom or a methyl group, R ² O represents an oxyethylene group,
R ³ is a hydrogen atom or an alkyl group having 1 to 22 carbon atoms, preferably 1 to 15 carbon atoms, and m is the average number of moles of addition of the oxyethylene group, 1 to 97, preferably 1 to
Represents an integer of 10.

General formula (2)

[0029]

[Chemical 14]

In the general formula (2), R ⁴ represents a hydrogen atom or a methyl group, R ⁵ O represents an oxyethylene group,
R ⁶ is a hydrogen atom or an alkyl group having 1 to 22 carbon atoms, preferably 1 to 15 carbon atoms, and n is the average number of added moles of an oxyethylene group, 4 to 100, preferably 1
It represents an integer of 1 to 100, and n ≠ m and n−m ≧ 3, preferably n−m ≧ 5.

General formula (3)

[0032]

[Chemical 15]

In the formula (3), R ⁷ represents a hydrogen atom or a methyl group, M ¹ represents a hydrogen atom, a monovalent metal atom, a divalent metal atom, an ammonium group or an organic amine group.

The polyethylene glycol (meth) acrylates (a) and (b) represented by the general formula (1) used in the present invention include short-chain polyethylene glycol (meth) acrylate and long-chain polyethylene glycol (meth) acrylate. There is.

Examples of short-chain polyethylene glycol (meth) acrylates include hydroxyethyl (meth) acrylate
(Poly) oxyethylene glycol mono (meth) acrylic acid esters such as acrylate, polyethylene glycol mono (meth) acrylate, methoxy (poly) ethylene glycol mono (meth) acrylate, ethoxy (poly) ethylene glycol mono (meth) acrylate, etc. There is. It is important that the polyethylene glycol (meth) acrylate (a) has hydrophobicity in the short-chain polyethylene glycol of its side chain. Therefore, as polyethylene glycol (meth) acrylate (a),
An (alkoxy) (poly) ethylene glycol (meth) acrylate having an average added mole number m of 1 to 97, preferably 1 to 10 is preferable.

The long-chain polyethylene glycol type monomer (b) used in the present invention is represented by the above-mentioned general formula, and for example, polyethylene glycol mono (meth) acrylate, methoxy polyethylene glycol mono (meth) acrylate, ethoxy. Examples include polyoxyethylene glycol mono (meth) acrylic acid esters such as polyethylene glycol mono (meth) acrylate. In order to obtain a high water-reducing property, it is important to disperse the cement particles with steric repulsion and hydrophilicity due to the polyethylene glycol chain having an average addition mole number of 4 to 100 of polyethylene glycol (meth) acrylate (b). The average number of moles n of ethylene glycol chains added to the (alkoxy) polyethylene glycol (meth) acrylate (b) is 4
-100, preferably 11-100.

The carboxylic acid type monomer (c) is represented by the above general formula (3). Examples of the monomer (c) include acrylic acid, methacrylic acid, and monovalent metal salts, divalent metal salts, ammonium salts and organic amine salts of these acids, and one or two of these may be mentioned. The above can be used.

The monomer (d) is a monomer copolymerizable with the monomers (a), (b) and (c). Monomer (d)
Examples of maleic acid, fumaric acid, citraconic acid,
Dicarboxylic acids such as mesaconic acid and itaconic acid and HO (R
⁸ O) _p R ⁹ (wherein R ⁸ O represents one or a mixture of two or more oxyethylene groups having 2 to 4 carbon atoms, and 2
In the case of more than one species, they may be added in a block form or in a random form, p is the average number of moles of oxyethylene groups added and represents an integer of 1 to 100, and R ⁹ is hydrogen or a carbon atom. It represents an alkyl group represented by the formula 1 to 22. )
Monoesters or diesters with alcohols represented by: unsaturated amides such as (meth) acrylamide and (meth) acrylalkylamide; vinyl esters such as vinyl acetate and vinyl propionate; vinyl sulfonic acid, (meth) allyl Sulfonic acid, sulfoethyl (meth)
Acrylate, 2-methylpropanesulfonic acid (meth)
Unsaturated sulfonic acids such as acrylamide and styrene sulfonic acid and their monovalent metal salts, divalent metal salts, aluminium salts, organic amine salts; aromatic vinyls such as styrene and α-methylstyrene; carbon atoms of 1 to 18 Esters of phenyl group-containing alcohols such as aliphatic alcohols or benzyl alcohol with (meth) acrylic acid;
And the like, and one or more of these can be used.

The first copolymer (A) comprises the monomer (a),
It is derived using (b), (c) and, if necessary, the monomer (d) in the above-mentioned specific ratio. That is, the mixing ratio of the monomers (a), (b) and (c) is such that the monomer (a) is 5 to 90% by weight, the monomer (b) is 5 to 90% by weight, and the monomer is (C) is in the range of 5 to 90% by weight, preferably 5 to 70% by weight of the monomer (a) and 10 to 9 of the monomer (b).
0% by weight, the monomer (c) is in the range of 5 to 40% by weight, more preferably the monomer (a) is 10 to 65% by weight, the monomer (b) is 20 to 70% by weight, The monomer (c) is in the range of 8 to 30% by weight, and the mixing ratio of the monomer (d) copolymerizable with these monomers is 50% by weight or less, preferably 30% by weight or less. is there. If the ratio is out of this range, the desired cement dispersant having excellent performance cannot be obtained.

To obtain the copolymer (A), the above monomer components may be copolymerized using a polymerization initiator. The copolymerization can be carried out by a method such as polymerization in a solvent or bulk polymerization.

Polymerization in a solvent can be carried out batchwise or continuously, and the solvent used in this case is water;
Lower alcohols such as methyl alcohol, ethyl alcohol and isopropyl alcohol; aromatic or aliphatic hydrocarbons such as benzene, toluene, xylene, cyclohexane and n-hexane; ester compounds such as ethyl acetate;
Ketone compounds such as acetone and methyl ethyl ketone; and the like. Raw material monomer and resulting copolymer (A)
It is preferable to use at least one selected from the group consisting of water and a lower alcohol having 1 to 4 carbon atoms, from the viewpoint of the solubility and the convenience of using the copolymer (A). In that case, among lower alcohols having 1 to 4 carbon atoms, methyl alcohol, ethyl alcohol, isopropyl alcohol and the like are particularly effective.

When carrying out the polymerization in an aqueous medium, a water-soluble polymerization initiator such as ammonium or alkali metal persulfate or hydrogen peroxide is used as the polymerization initiator.
At this time, an accelerator such as sodium bisulfite and Mohr's salt may be used in combination. For polymerization using a lower alcohol, aromatic hydrocarbon, aliphatic hydrocarbon, ester compound or ketone compound as a solvent, peroxides such as benzoyl peroxide and lauroyl peroxide; hydroperoxides such as cumene hydroperoxide; azo An aromatic azo compound such as bisisobutyronitrile is used as a polymerization initiator. At this time, an accelerator such as an amine compound may be used in combination. Further, when a water-lower alcohol mixed solvent is used, it can be appropriately selected and used from the above various polymerization initiators or a combination of a polymerization initiator and an accelerator. The polymerization temperature is appropriately determined depending on the solvent and the polymerization initiator used, but is usually 0 to 1
It is carried out within the range of 20 ° C.

Bulk polymerization is carried out using a peroxide such as benzoyl peroxide or lauroyl peroxide; a hydroperoxide such as cumene hydroperoxide; an aliphatic azo compound such as azobisisobutyronitrile, etc. It is carried out within a temperature range of 200 ° C.

Further, a thiol chain transfer agent may be used in combination for controlling the molecular weight of the obtained copolymer (A). Thiol chain transfer agents used in this case, the general formula HS-R ¹⁰ -E _g (provided that wherein R ¹⁰ represents an alkyl group having a carbon number of 1 to 2, E is -OH, -COOM
² , —COOR ¹¹ or —SO ₃ M ² group, M ² represents hydrogen, monovalent metal, divalent metal, ammonium group or organic amine group, and R ¹¹ represents an alkyl group having 1 to 10 carbon atoms. And g represents an integer of 1 to 2. ), For example, mercaptoethanol, thioglycerol, thioglycolic acid, 2-mercaptopropionic acid,
Examples thereof include 3-mercaptopropionic acid, thiomalic acid, octyl thioglycolate, and octyl 3-mercaptopropionic acid, and one or more of these can be used.

Copolymer (A) thus obtained
Is used as the main component of the cement dispersant as it is, but if necessary, the copolymer salt (B) obtained by further neutralizing with an alkaline substance may be used as the main component of the cement dispersant. Preferred examples of such alkaline substances include inorganic substances such as hydroxides, chlorides and carbon salts of monovalent and divalent metals; ammonia; organic amines and the like.

[0046] Also, the copolymer to be used as a cement admixture of the present invention (A) Contact and / or copolymer salt (B)
Has a weight average molecular weight of 500 to 500,000,
It is particularly preferable to set it in the range of 5,000 to 300,000. When the weight average molecular weight is less than 500, the water-reducing performance of the cement dispersant deteriorates, which is not preferable. on the other hand,
When the molecular weight exceeds 500,000, the water-reducing performance and slump loss preventing ability of the cement dispersant are deteriorated, which is not preferable.

The first copolymer (A) and / or the copolymer salt (B) can be used as a cement dispersant, either alone or as a mixture thereof.
Further, the copolymer (A) and / or the copolymer salt (B)
When used in combination with other known cement admixtures containing as a main component, such known cement admixtures include, for example, conventional cement dispersants, air entraining agents, cement wetting agents, expanding agents, waterproofing agents, Examples thereof include a retarder, a quick-setting agent, a water-soluble polymer substance, a thickener, a coagulant, a drying shrinkage reducing agent, a strength enhancer, a curing accelerator and an antifoaming agent.

The cement admixture of the present invention can be used for hydraulic cements such as Portland cement, belite-rich cement, alumina cement, various mixed cements, and hydraulic materials other than cements such as gypsum.

The cement admixture used in the present invention exhibits an excellent effect even when added in a small amount as compared with the conventional cement admixture. For example, when it is used for mortar or concrete using hydraulic cement, it is 0.01 to 1.0%, preferably 0.02 to 0.
An amount of 5% may be added during kneading.
By this addition, various desirable effects such as achievement of high water reduction rate, improvement of slump loss prevention performance, reduction of unit water amount, increase of strength, improvement of durability are brought about. If the addition amount is less than 0.01%, the performance is insufficient, and conversely 1.0
Even if a large amount exceeding 10% is used, the effect is practically leveled off and it is disadvantageous from the economical aspect.

In the cement composition of the present invention, the amount of cement used per 1 m ^{3 of the} cement composition and the unit water amount are not particularly limited, but the unit water amount is 120 to 185 kg / m 2.
³ , water / cement weight ratio = 0.15 to 0.7, preferably unit water amount 120 to 175 kg / m ³ , water / cement weight ratio = 0.2 to 0.5 are recommended.

Generally, when the hydration rates of the respective cement components are compared, C ₃ A is the fastest and the hydration rate within 3 minutes after pouring water is 3
It exceeds 0%. The reduction of the kneading water split by such rapid hydration may be one of the causes of slump loss.
In addition, since the known cement dispersant adsorbs to C ₃ A, which has high activity among the cement components, most of the added dispersant is contained in the crystals generated by the hydration reaction of C ₃ A. It is presumed that the slump loss may be caused by the burial and loss of the cement dispersion power over time. Therefore, it is expected that the slump loss can be greatly reduced if the activity of C ₃ A can be suppressed. The copolymer of the present invention is, for example, a polycarboxylic acid type copolymer having both a short polyethylene glycol and a long polyethylene glycol in a side chain in one molecule, and the short polyethylene glycol side chain has a hydrophobic property. The activity of C ₃ A is suppressed, and the long polyethylene glycol side chain exerts a strong water reducing effect due to its hydrophilicity and steric repulsion.

However, the cement admixture of the present invention is not limited to the above reasons.

The present invention will be described more specifically with reference to the following examples. In the examples,% is% by weight unless otherwise specified.
And parts are parts by weight.

Example 11 Production of Cement Admixture (6) 500 parts of water was charged into a glass reaction vessel equipped with a thermometer, a stirrer, a dropping funnel, a nitrogen introducing tube and a reflux condenser, and the inside of the reaction vessel was stirred. Replaced with nitrogen, and under a nitrogen atmosphere at 80 ℃
Heated up. Next, 50 parts of methoxy polyethylene glycol monomethacrylate (average number of moles of ethylene oxide added 4), methoxy polyethylene glycol monomethacrylate (average number of moles of ethylene oxide added 2)
3 pieces) 350 parts, methacrylic acid 100 parts, water 150 parts,
And a monomer aqueous solution mixed with 2.8 parts of 3-mercaptopropionic acid as a chain transfer agent and 40 parts of a 10% ammonium persulfate aqueous solution were added dropwise over 4 hours, and after completion of the addition, 10 parts of a 10% ammonium persulfate aqueous solution was added over 1 hour. Dropped. Then, the temperature was maintained at 80 ° C. for 1 hour to complete the polymerization reaction, and the weight average molecular weight of 2
A cement admixture (6) of the present invention consisting of 2000 polymer aqueous solution was obtained.

Examples 12 to 17 Production of cement admixtures (7) to (12) The same procedure as in Example 11 was carried out to produce cement admixtures (7) to (12) of the present invention. Table of contents
It shows collectively in 1 .

Comparative Example 5 Production of Comparative Cement Admixture (1) 500 parts of water was charged into a glass reaction vessel equipped with a thermometer, a stirrer, a dropping funnel, a nitrogen introducing tube and a reflux condenser, and the inside of the reaction vessel was stirred. To 80 ° C under nitrogen atmosphere
Heated up. Next, 10 parts of methoxypolyethylene glycol monomethacrylate (average number of moles of ethylene oxide added 4), methoxypolyethylene glycol monomethacrylate (average number of moles of ethylene oxide added 2)
3) 390 parts, methacrylic acid 100 parts, water 150 parts,
And a monomer aqueous solution mixed with 2.6 parts of 3-mercaptopropionic acid as a chain transfer agent and 40 parts of a 10% ammonium persulfate aqueous solution were added dropwise over 4 hours. Dropped. Then, the temperature was maintained at 80 ° C. for 1 hour to complete the polymerization reaction, and the weight average molecular weight of 2
A comparative cement admixture (1) consisting of 3000 polymer aqueous solutions was obtained.

Comparative Examples 6 to 7 Preparation of Comparative Cement Admixtures (2) to (3) The comparative cement admixtures (2) to (3) were produced in the same manner as in Comparative Example 5 below. The contents are summarized in Table 1 .

[0058]

[Table 1]

Examples 18 to 24 and Comparative Examples 8 to 10 Mortar test 3 Cement admixtures (6) to (12) of the present invention shown in Table 1
(Examples 18 to 24) and comparative cement admixtures (1) to (3) (Comparative Examples 8 to 10) were added for comparison, and changes with time of mortar flow values were measured.

The materials and mortar formulations used in the test were 800 g of Chichibu Onoda High Flow Cement, 400 g of Toyoura standard sand, and 200 g of water containing the inventive or comparative cement dispersant.

Mortar is prepared by mechanical kneading with a mortar mixer, and the mortar is packed in a hollow cylinder having a diameter of 55 mm and a height of 55 mm. Next, after the cylinder was lifted vertically, the diameter of the mortar spread on the table was measured in two directions, and the average was used as the flow value. Thereafter, the entire amount of the mortar was allowed to stand in a closed container for a predetermined time, and the same operation as above was repeated to measure the change with time in the flow value. Table of results
2 shows.

[0062]

[Table 2]

Examples 25 to 31 and Comparative Examples 11 to 12 Normal Portland cement (Chichibu Onoda Cement: specific gravity: 3.16) was used as a concrete test cement, and Oigawa water system land sand (specific gravity 2.62, FM2. 71), crushed hard sandstone from Ome (specific gravity 2.64, MS 20 mm) was used as coarse aggregate.

As the cement dispersant, the cement admixtures (6) to (12) of the present invention (Examples 25 to 31) and the comparative cement admixtures (1) to (2) (Comparative Examples 11 to 1)
2) was used. The air content was adjusted using a commercially available antifoaming agent.

The mixing conditions of concrete are a unit cement amount of 660 kg / m ^{3 and} a unit water amount of 165 kg / m ³ and a fine aggregate ratio of 40.3%.

Under the above conditions, concrete is produced,
Slump and air volume are all measured by Japanese Industrial Standards (JIS
A 1101, 1128). The results are shown in Table 3 .

[0067]

[Table 3]

From Table 2 and Table 3 , the cement admixture-added mortar and concrete of the present invention were tested after 30 minutes.
Even after 60 minutes, the decrease in the flow value is significantly suppressed,
It can be seen that it has an excellent effect in reducing slump loss.

[0069]

As described above, the cement admixture according to the present invention is excellent in high water reduction rate and slump retention,
A cement composition containing the cement admixture exhibits a high flow value.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Koichiro Nagaru 10-12 Ukishima-cho, Kawasaki-ku, Kawasaki-shi, Kanagawa Stock company Nihon Shatai Co., Ltd. Japanese catalyst (56) Reference JP 58-74552 (JP, A) JP 62-78137 (JP, A) JP 5-213644 (JP, A) JP 7-187842 (JP, A) JP-A-7-217148 (JP, A) JP-A-7-247149 (JP, A) JP-A-7-247150 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) ) C04B 24/00-24/42

Claims (4)

(57) [Claims] 1. A compound represented by the general formula (1): (However, in the formula, R ¹ is a hydrogen atom or a methyl group, R ² O
Represents an oxyethylene group, R ³ represents a hydrogen atom or an alkyl group having 1 to 22 carbon atoms, m represents the average number of moles of the added oxyethylene group, and represents an integer of 1 to 97. ) A first polyethylene glycol (meth) acrylate (a) of 5 to 90% by weight, represented by the general formula (2): (However, in the formula, R ⁴ is a hydrogen atom or a methyl group, and R ⁵ O
Represents an oxyethylene group, R ⁶ represents a hydrogen atom or an alkyl group having 1 to 22 carbon atoms, n represents the average number of added moles of the oxyethylene group, represents an integer of 4 to 100, and n ≠ m In addition, n−m ≧ 3. ) A second polyethylene glycol (meth) acrylate (b) of 5 to 90% by weight, represented by the general formula (3): (In the formula, R ⁷ represents a hydrogen atom or a methyl group, M ¹ represents a hydrogen atom, a monovalent metal atom, a divalent metal atom, an ammonium group or an organic amine group.) (C) 5 to 90% by weight, and other monomers copolymerizable with these monomers (d) 0 to 50% by weight
(However, the total of (a), (b), (c) and (d) is 100% by weight.) The first copolymer (A) and / or the copolymer. A cement admixture containing a first copolymer salt (B) obtained by further neutralizing (A) with an alkaline substance and having an excellent slump retention property. 2. A compound represented by the general formula (1): (However, in the formula, R ¹ is a hydrogen atom or a methyl group, R ² O
Represents an oxyethylene group, R ³ represents a hydrogen atom or an alkyl group having 1 to 22 carbon atoms, m represents the average number of moles of the added oxyethylene group, and represents an integer of 1 to 97. ) A first polyethylene glycol (meth) acrylate (a) of 5 to 90% by weight, represented by the general formula (2): (However, in the formula, R ⁴ is a hydrogen atom or a methyl group, and R ⁵ O
Represents an oxyethylene group, R ⁶ represents a hydrogen atom or an alkyl group having 1 to 22 carbon atoms, n represents the average number of added moles of the oxyethylene group, represents an integer of 4 to 100, and n ≠ m In addition, n−m ≧ 3. ) A second polyethylene glycol (meth) acrylate (b) of 5 to 90% by weight, represented by the general formula (3): (In the formula, R ⁷ represents a hydrogen atom or a methyl group, M ¹ represents a hydrogen atom, a monovalent metal atom, a divalent metal atom, an ammonium group or an organic amine group.) (C) 5 to 90% by weight, and other monomers copolymerizable with these monomers (d) 0 to 50% by weight
(However, the total of (a), (b), (c) and (d) is 100% by weight.) The first copolymer (A) and / or the copolymer. The main component is the first copolymer salt (B) obtained by further neutralizing (A) with an alkaline substance, and the other monomer (d) is an aliphatic group having 1 to 18 carbon atoms. A cement admixture that is an ester of alcohol and (meth) acrylic acid and has excellent slump retention. 3. A cement composition containing at least the cement admixture according to claim 1 or 2, cement and water. 4. The cement composition according to claim 3, wherein the cement admixture is 0.01 to 1.0% by weight with respect to the cement, and the water / cement weight ratio is 0.15 to 0.7. .