JPH1179816A - Cement admixture for grout and cement composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a cement admixture for grouts, capable of reducing the flowing of the grouts even under the conditions of high temperatures by including a specific expanded substance and a polycarboxylic acid polymer having carboxyl groups and polyalkylene oxide structures in side chains. SOLUTION: CaO raw material, Al2 O3 raw material and CaSO4 raw material are mixed in a CaO/Al2 O3 molar ratio of 6.5-18 and in a CaSO4 /Al2 O3 molar ratio of 1.5-4 and subsequently sintered at 1,100-1,600 deg.C to obtain an expanded substance having a Blaine value of >=4,000 cm2 /g, preferably 5,000-9,000 cm2 /g. The cement admixture for grouts comprises the expanded substance, 0.5-15 pts.wt. of a polycarboxylic acid polymer having a mol.wt. of 3,000-50,000, preferably 3,000-100,000 and an average particle diameter of >=1,000 μm, preferably >=500 μm, and having carboxy groups and polyalkylene oxide structures in side chains and, if necessary, >=13 pts.wt. of a fluidizing agent and/or 0.01-10 pts.wt. of a defoaming agent, wherein the total amount of the components is 100 pts.wt.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a cement admixture for grout and a cement composition mainly used in the civil engineering and construction industries.

[0002]

2. Description of the Related Art Cement is a widely used material because it can produce large structures at low cost. However, cement has a problem of shrinkage. Wood is proposed
(JP-A-53-13650, JP-A-53-31170, etc.).
These cement admixtures impart expandability and were excellent in compensating for shrinkage of cement.

Further, as a cement admixture for grout, there has been proposed a cement admixture containing a usual expanding substance and a fluidizing agent as main components (JP-B-48-9331 and JP-B-56-638).
No. 1). These materials are materials that impart fluidity in addition to expansibility to improve workability in order to smoothly complete grouting work. However, recently, the required physical properties of the grout material have been remarkably increased, and in some cases, the required physical properties cannot be satisfied.

[0004] The required physical properties of the grout material include non-shrinkage, good fluidity, excellent retention, and no breathing, and all of these required physical properties are satisfied. Is required.

However, the conventional cement admixture for grout does not have sufficient fluidity retention properties. In particular, under high-temperature operating conditions where the kneading temperature of the grout material is 30 ° C. or more, the kneading material is not more than 10 There was a problem that the construction could not be performed because the fluidity was lost in about a minute and condensed. SUMMARY OF THE INVENTION An object of the present invention is to provide a grout material having a small decrease in fluidity even under conditions of use at high temperatures.

[0006]

The present inventor has conducted various studies to solve the above-mentioned problems, and as a result, the use of a swelling substance having a specific composition and a polycarboxylic acid-based polymer has solved the above-mentioned problems. The present invention has been completed with the knowledge obtained.

That is, the present invention relates to an expanding substance produced by heat-treating a composition containing a CaO raw material, an Al ₂ O ₃ raw material and a CaSO ₄ raw material, wherein CaO, Al ₂ O ₃ and CaSO ₄ are effectively used. It consists of minerals as components, and the component ratio in the minerals is CaO / Al ₂
O ₃ molar ratio is 6.5-18, CaSO ₄ / Al ₂ O ₃ molar ratio is 1.5-4, Blaine value of 4,000 cm ² / g or more inflating substance, carboxyl group and polyalkylene oxide structure in side chain A grout cement admixture containing a polycarboxylic acid-based polymer, and a grout cement admixture comprising the grout cement admixture and a fluidizing agent and / or an antifoaming agent. It is a cement composition comprising cement and the cement admixture for grout.

[0008]

Hereinafter, the present invention will be described in more detail.

The raw material of the expanding substance used in the present invention can be arbitrarily selected depending on the purity and cost, and is not particularly limited. For example, the CaO raw material includes CaCO such as limestone and slaked lime. ₃ quality and Ca (OH) ₂ quality
In addition, as the Al ₂ O ₃ raw material, bauxite or aluminum residual ash, etc., further, as the CaSO ₄ raw material, anhydrous gypsum,
Hemihydrate gypsum, dihydrate gypsum and the like can be mentioned. The contamination of impurities such as SiO ₂ , Fe ₂ O ₃ , CaF ₂ , MgO, and TiO ₂ present in the raw material is not particularly limited as long as the object of the present invention is not substantially impaired.

In the present invention, the mixing ratio of the various raw materials is such that the molar ratio of CaO / Al ₂ O ₃ is 6.5 to 18 and the molar ratio of CaSO ₄ / Al ₂ O ₃ is 1.5 to 4, and the CaO / Al ₂ O ₃ molar ratio is 8 to 12
It is preferable that the molar ratio of CaSO ₄ / Al ₂ O ₃ is 2 to 3. If the CaO / Al ₂ O ₃ molar ratio is less than 6.5, sufficient expandability may not be obtained when used in a mixed cement, and if it exceeds 18, the strength expression may be reduced. On the other hand, if the molar ratio of CaSO ₄ / Al ₂ O ₃ is less than 1.5, sufficient expandability may not be obtained. If the molar ratio is more than 4, the onset of expansion will be delayed, and expansion failure may occur.

In the present invention, the desulfurization decomposition temperature of gypsum greatly changes depending on the mixing ratio of the mixture of raw materials and the content of impurities. Therefore, the firing temperature during firing is not particularly limited. The temperature is preferably about 1,100 to 1,600 ° C.

The method of mixing the raw materials is not particularly limited, and a usual method can be used. The heat treatment method for producing the expanding material is not particularly limited, and for example, any method such as firing using a rotary kiln or melting using an electric furnace is possible.

The particle size of the expanding material is 4,000 cm ² in Blaine value.
/ g or more, preferably 5,000 to 9,000 cm ² / g, and 6,000 to
7,000 cm ² / g is more preferred. If it is less than 4,000 cm ² / g, breathing is likely to occur. Also, if it exceeds 9,000 cm ² / g,
It is difficult to pulverize until it exceeds 9,000 cm ² / g, and there is a tendency that an increase in its use effect cannot be expected.

The polycarboxylic acid polymer used in the present invention is a polycarboxylic acid polymer having a carboxyl group and a polyalkylene oxide structure in a side chain.

Examples of polycarboxylic acid polymers having a carboxyl group and an alkylene glycol structure in the side chain include, for example, JP-A-6-256554 and JP-B-6-888.
And unsaturated vinyl monomers such as vinyl ether-maleic anhydride copolymer, olefin-maleic anhydride copolymer and styrene-maleic anhydride copolymer described in JP-A-18-188, JP-B-6-88817 and the like. There is an esterified product of a dicarboxylic acid copolymer with an alkylene glycol compound.

Further, a (meth) acrylate group as an unsaturated group described in JP-A-8-12396, JP-A-62-216950, JP-A-1-226575, JP-A-6-206750, etc. And a copolymer of an unsaturated monocarboxylic acid or unsaturated dicarboxylic acid and a monomer having a sulfonic acid group such as allylsulfonic acid and methallylsulfonic acid.

Japanese Patent Application Laid-Open Nos. Hei 7-53249, Hei 7-215746, Hei 8-165157
, A copolymer comprising a monomer comprising a polyoxyalkylene derivative described in JP-A-7-232945 and a monomer having a carboxyl group as an essential component, an antifoaming agent and / or a defoamer And the like.

Among these, from the viewpoint of fluidity retention performance, a copolymer comprising polyalkylene glycol alkenyl ether represented by the following general formula (1) and maleic anhydride, or a hydrolyzate and / or hydrolyzate thereof Are most preferred.

[0019]

Embedded image (R1 is a vinyl group, an allyl group, AO is an oxyalkylene group having 2 to 4 carbon atoms, n is an integer of 1 to 100, and R2 is hydrogen or an alkyl group having 1 to 4 carbon atoms)

In the formula (1), examples of the oxyalkylene group having 2 to 4 carbon atoms represented by AO include an oxyethylene group, an oxypropylene group and an oxytetramethylene group. From the viewpoint, an oxyethylene group having 2 carbon atoms is particularly preferable. Incidentally, as long as the water solubility of the obtained copolymer is not impaired, an oxypropylene group, a random or block copolymer with an oxyalkylene group such as an oxytetramethylene group, or a polyalkylene glycol alkenyl ether having each oxyalkylene group. One or more mixtures can be used.

The average number of added moles n of the oxyalkylene group is preferably from 1 to 100 moles. If n is 1, sufficient fluidity retention performance cannot be obtained, which is not preferable. If it exceeds 100 moles, the polymerizability with maleic anhydride decreases, and it becomes difficult to form a copolymer.

The functional group represented by R 1 is an allyl group,
A vinyl group is exemplified, but a vinyl group is preferred from the viewpoint of copolymerizability with maleic anhydride. R2 is hydrogen or an alkyl group having 1 to 4 carbon atoms, such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl,
A tertiary butyl group is exemplified, and a methyl group is preferred from the viewpoint of water solubility and production cost.

In the copolymerization of polyalkylene glycol alkenyl ether and maleic anhydride, the molar ratio is preferably in the range of 1/2 to 2/1, more preferably 1 / 1.2 to 1.2. / 1. A known radical polymerization method can be applied to the production of the copolymer. For example, according to the methods described in JP-A-64-109 and JP-A-8-46652, it can be produced by radical copolymerization using a radical initiator in an organic solvent or under the condition of bulk without solvent. It is.

The molecular weight of the copolymer of polyalkylene glycol alkenyl ether and maleic anhydride is not particularly limited, but the weight average molecular weight in terms of polyethylene glycol measured by aqueous GPC is in the range of 3,000 to ⁵ × 10 ^5. be able to. Particularly good dispersibility is exhibited in the range of 3,000 to 1 × 10 ⁵ . Weight average molecular weight of 3,
When it is less than 000, the dispersion performance is reduced. On the other hand, when the weight average molecular weight exceeds 5 × 10 ⁵ , the production becomes difficult and the production cost increases, and the dispersing performance also decreases.

As long as the water reducing performance and water solubility of the copolymer are not impaired, maleimides such as styrene and phenylmaleimide, olefins such as α-olefin, methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, n Copolymerization of copolymerizable monomers such as lower alkyl vinyl ethers such as -butyl vinyl ether and isobutyl vinyl ether;

The polycarboxylic acid-based water reducing agent used in the present invention can be used in the form of a powder or an aqueous solution, but it can be used as a cement admixture for grout, a mixture of cement admixture for grout and cement, or a grout admixture. The mixture of cement admixture and cement and aggregate is a product in which all of the components are premixed in advance so that it can be used immediately by mixing with water without the need for detailed weighing operations. However, since the workability on site is good, it is desirable that the water reducing agent used is also in a powder form. When the polycarboxylic acid-based water reducing agent used in the present invention is used in the form of a powder, if the polycarboxylic acid-based polymer itself has a property that does not easily become a powder, it is described in JP-A-6-239652. A powder obtained by a method in which the powder is supported on an inorganic powder of the above, or a method in which the powder is formed by forming a salt with a polyvalent metal can be used.

As a method of pulverizing the polycarboxylic acid copolymer by converting it into a salt with a polyvalent metal, for example, an organic solvent for the copolymer obtained from polyalkylene glycol monoalkenyl ether and maleic anhydride is used. Solution, aqueous solution of the copolymer or melted copolymer melted by heating, adding calcium hydroxide or calcium hydroxide-water slurry, after neutralization reaction, drying and grinding to obtain copolymer calcium salt, by polymerization After the obtained copolymer-organic solvent solution was turned into a copolymer aqueous solution by stripping with heating steam, it was reacted with calcium hydroxide and dried.
A method of pulverizing to obtain a copolymer calcium salt may, for example, be mentioned.

The average particle size of the polycarboxylic acid polymer used in powder form is preferably 1000 μm or less, more preferably 500 μm or less. Powders having an average particle size of 1000 μm or more are not preferable because the original performance cannot be obtained with good reproducibility due to the difference in dissolution rate with respect to the solvent and the segregation when dry-blended with various powder materials.

As the polycarboxylic acid polymer having a carboxyl group and a polyalkylene oxide structure in the side chain, only one kind may be used alone. Two or more kinds having different numbers or different molecular weights of the polycarboxylic acid-based polymer itself may be used in combination.

The amount of the polycarboxylic acid-based polymer to be used cannot be unambiguously determined depending on each material, but is usually composed of an intumescent material and a polycarboxylic acid-based polymer, or an intumescent material and a polycarboxylic acid-based polymer. It is preferably 0.5 to 15 parts by weight, more preferably 2.0 to 10 parts by weight, based on 100 parts by weight of the cement admixture for grout comprising the coalescing and the fluidizing agent and / or defoaming agent. If the amount is less than 0.5 part by weight, sufficient dispersibility cannot be obtained, and 1
If the amount exceeds 5 parts by weight, setting delay may occur, which is not economically preferable.

In the present invention, a polycarboxylic acid polymer having a carboxyl group and a polyalkylene oxide structure in the side chain has a sufficient effect even when used alone, but a fluidizing agent is used as long as the effect is not impaired. You may use together.

The fluidizing agent which can be used in the present invention, which imparts fluidity to the cement kneaded material, includes, for example, polyalkylallyl sulfonate condensate, naphthalene sulfonate condensate, and melamine resin sulfone. Formalin condensate, lignin sulfonate, polycarboxylate, dextrin and the like. Dextrin refers to a substance obtained by decomposing starch by heating with acid and making it soluble in cold water, and is also called roasted dextrin. All of these fluidizers can be used in the form of powder, and in the present invention, one or more of these can be used.

The blending amount of the fluidizing agent of the present invention cannot be univocally determined depending on each material, but is usually composed of a swelling substance, a polycarboxylic acid polymer, and a fluidizing agent. In 100 parts by weight of a cement admixture for grout comprising a polycarboxylic acid polymer, a fluidizing agent, and an antifoaming agent, 1
It is preferably at most 3 parts by weight, more preferably at most 10 parts by weight. If it is used in excess of 13 parts by weight, the strength development may be poor.

In the present invention, in order to adjust the amount of air entrained in the grout material, lower alcohols, higher alcohols, fats and oils, fatty acids, fatty acid esters, phosphate esters, metal soaps, mineral oils and the like are used. Conventionally known antifoaming agents such as polyethers and silicones can be used. Among these, preferred are polymeric antifoaming agents, polyoxyalkylenes such as polyoxyethylene polypropylene adducts, and polyoxyalkylene alkyl ethers obtained by etherifying a part of the terminal structure of polyoxyalkylene with an alkyl group. , Polyoxyalkylene (alkyl) aryl ethers obtained by etherifying a part of the terminal structure of polyoxyalkylene with an aryl group or alkylaryl group, acetylene ethers obtained by addition-polymerizing alkylene oxide to acetylene alcohol, polyoxyalkylene Polyoxyalkylene fatty acid esters obtained by esterifying a part of the terminal structure of the fatty acid, polyoxyalkylene alkyl (aryl) ether sulfates having a sulfate group introduced, and poly having a phosphate group introduced Xylene polyoxyalkylene alkyl phosphoric acid esters, polyoxyalkylene-based defoaming agents such as polyoxyalkylene alkyl amines to introduce amine groups are especially preferred.

As a method of using these defoaming agents, a method of separately using an aqueous solution of a polycarboxylic acid-based water reducing agent and a solution of an antifoaming agent, or a method of using a previously prepared aqueous solution of a polycarboxylic acid-based water reducing agent and an antifoaming agent solution are used. A method of using a mixed aqueous solution, a method of adding a defoaming agent component in advance in the production process of a polycarboxylic acid-based water reducing agent and pulverizing it together with a polycarboxylic acid-based water reducing agent, and using a white carbon as an antifoaming agent What was impregnated or supported on an inorganic powder such as silica to obtain a powdery defoaming agent,
There is a method in which a powdery polycarboxylic acid-based water reducing agent and a powdery antifoaming agent are pre-blended and used, or a method in which a powdery polycarboxylic acid-based water reducing agent and a powdery antifoaming agent are separately added and used. .

The amount of the antifoaming agent is preferably 0.01 to 10 parts by weight, particularly preferably 0.05 to 5.0 parts by weight, based on 100 parts by weight of the polycarboxylic acid polymer having a carboxyl group and a polyalkylene oxide structure in the side chain. . If the amount used is less than 0.01 part by weight, a sufficient defoaming effect cannot be obtained, and if it is 10% by weight or more, not only the defoaming effect is not further improved, but also the amount of entrained air in the composition such as mortar or concrete increases. In some cases, which is not preferable in terms of both performance and cost.

In the present invention, the expanding material and a polycarboxylic acid polymer or a mixture of the expanding material and a polycarboxylic acid polymer, a fluidizing agent and / or an antifoaming agent is used as a cement admixture for grout. use.

The amount of the cement admixture for grout of the present invention varies depending on the purpose of use, but is preferably 3 to 15 parts by weight, more preferably 5 to 12 parts by weight, based on a total of 100 parts by weight of cement and the cement admixture for grout. Parts by weight are more preferred. If the amount is less than 3 parts by weight, sufficient dimensional stability may not be obtained.
Exceeding the weight part may cause overexpansion.

Here, as cement, ordinary, early strength,
Ultra-high strength, and various Portland cements such as moderate heat, various mixed cements obtained by mixing a pozzolanic substance with these Portland cements, and alumina cements, and the like.In particular, the cement admixture for the grout of the present invention is particularly suitable for the mixed cements. The effect is remarkable when used.

It is preferable to use a cement in combination with a latent hydraulic substance in view of increasing resistance to material separation and preventing breathing.

Here, the latent hydraulic substance refers to a pozzolanic substance which does not have hydraulicity by itself but reacts with alkali to exhibit hydraulicity. Specifically, blast furnace slag, fly ash, silica fume, And silica flour. In the present invention, one or more of these can be used. In the present invention, the amount of the latent hydraulic substance is not particularly limited, but usually, a total of 10 cement compositions consisting of cement and cement admixture for grout.
It is preferably less than 80 parts by weight with respect to 0 parts by weight.
If the amount of the latent hydraulic substance exceeds 80 parts by weight, the initial strength expression may be deteriorated.

As a mixing device used for producing a cement kneaded material using the cement admixture or cement composition for grout of the present invention, any existing stirring device can be used. Mixers, omni mixers, V-type mixers, Henschel mixers, Nauta mixers, and the like can be used. In addition, the mixing of the materials may be performed by mixing the respective materials at the time of construction, or may be partially or entirely mixed in advance.

In the present invention, the cement admixture for grout further includes a setting modifier, an AE agent, a high-performance water reducing agent,
High-performance AE water reducer, thickener, aggregate such as sand and gravel, cement hardened material, rust preventive, antifreeze, polymer emulsion, clay mineral such as bentonite, zeolite, hydrotalcite, and hydrocalumite Ion exchangers such as, inorganic sulfates such as aluminum sulfate and sodium sulfate, inorganic phosphates, boric acid, and one or more of metal powders such as aluminum powders and iron powders of the present invention, It is possible to use them together within a range that does not substantially impair the purpose.

[0044]

[Effect of the Invention] By using the cement admixture for grout of the present invention, the temperature of the grout material in summer or the like can be reduced to three.
Even under use conditions exceeding 0 ° C., a sufficient grouting effect can be obtained for the time required for construction without flow down.

[0045]

The present invention will be described below in detail with reference to examples.

(Example of Production of Expanding Material) Using a CaO raw material, an Al ₂ O ₃ raw material, and a CaSO ₄ raw material, the mixture was fired at a maximum firing temperature of 1,400 ° C. using a rotary kiln, and the obtained clinker was pulverized. And the Brain value is 7,000 ± 200 cm ² /
Adjusted to g to give a swelling material. <Materials> CaO raw material: limestone powder, limestone powder from Aomi mine of Denki Kagaku Kogyo Co., Ltd. Al ₂ O ₃ raw material: aluminum residual ash, Nippon Kaisui Kako Co., Ltd. CaSO ₄ raw material: Shin-Akita Chemical Co., Ltd. anhydrous gypsum

The composition of the swelling substance is in accordance with JIS R 5202.
CaO, Al ₂ O _3, and analyze the SO ₃ content was determined by converting further SO ₃ amount CaSO _4. Composition of the expanding material: CaO: Al ₂ O ₃ : CaSO ₄ molar ratio = 12:
1: 2.5

(Examples and Comparative Examples) In a constant temperature room at a temperature of 30 ° C., cement for grout was prepared by mixing the amount of cement dispersant shown in Table 1 with 100 parts by weight of the total amount of the expanding material and cement dispersant. 10 parts by weight of admixture (hereinafter referred to as cement admixture) is added to 100 parts by weight of cement and cement admixture, and 100 parts by weight of fine aggregate and 35 parts by weight of water are mixed to form a mortar. , Kneading temperature 32 ~ 3
A mortar at 5 ° C. was prepared.

[0049] The prepared mortar, the aging of the J ₁₄ funnel flow value up to 60 minutes after kneading, to observe the presence or absence of breathing, further, the create and compressive strength specimens of 4 × 4 × 16cm expansion The rate was measured. Table 1 shows the results. The specimens for compressive strength were cured for 2 days in water after 1 day of age, and the compressive strength of 3 days of age was measured. The materials used are as follows.

Cement: ordinary Portland cement manufactured by Denki Kagaku Kogyo Co., Ltd. Fine aggregate: lime sand manufactured by Denki Kagaku Co., Ltd. Water: tap water

Cement dispersant a: β-naphthalene sulfonate salt, commercially available high-performance water reducer Cement dispersant b: Melamine-based commercially available high-performance water reducer Cement dispersant c: Polycarboxylic acid, commercially available superplasticizer

Cement dispersant d: methoxypolyethylene glycol vinyl ether-maleic acid copolymer Ca salt (average number of moles of ethylene oxide added to methoxypolyethylene glycol: 8 mol, weight average molecular weight of the copolymer: 2.0 × 10 ⁴ )

Cement dispersant e: 100 weight of Ca salt of methoxypolyethylene glycol vinyl ether-maleic acid copolymer (average number of moles of ethylene oxide added to methoxypolyethylene glycol 8 mol, weight average molecular weight of copolymer 2.0 × 10 ⁴ ) 100 weight Mixture of 0.5 parts by weight of SN-DF14HP (powder defoamer manufactured by San Nopco Co.)

Cement dispersant f: 100 weight of Ca salt of methoxypolyethylene glycol vinyl ether-maleic acid copolymer (average number of moles of ethylene oxide added of methoxypolyethylene glycol: 44 mol, weight average molecular weight of copolymer: 2.0 × 10 ⁴ ) Mixture of 0.5 parts by weight of SN-DF14HP (powder defoamer manufactured by San Nopco Co.)

Cement dispersant g: 100 weight of Ca salt of methoxypolyethylene glycol vinyl ether-maleic acid copolymer (average number of moles of ethylene oxide added to methoxypolyethylene glycol 8 mol, weight average molecular weight of copolymer 4.8 × 10 ⁴ ) Mixture of 0.5 parts by weight of SN-DF14HP (powder defoamer manufactured by San Nopco Co.)

Cement dispersant h: 100 weight of Ca salt of methoxypolyethylene glycol vinyl ether-maleic acid copolymer (average number of moles of ethylene oxide added to methoxypolyethylene glycol: 8 mol, weight average molecular weight of copolymer: 9.4 × 10 ⁴ ) Mixture of 0.5 parts by weight of SN-DF14HP (powder defoamer manufactured by San Nopco Co.)

Cement dispersant i: 5 parts of cement dispersant e
A mixture of 0 parts by weight and 50 parts by weight of a cement dispersant f.

[0058] <Measurement Method> J ₁₄ funnel flow value: conforming to the measurement of consistency by J funnel of the Japanese Society of Civil Engineering standard. Breathing: Measured according to JIS A 1123. Compressive strength: 4 × 4 × 16 cm specimen age 3 days strength (cured in water at 30 ° C.) Expansion rate: Expansion of filled mortar using expandable material, appendix showing “Guidelines for Design and Execution of Expanded Concrete” Rate of expansion and contraction measured according to "Rate measurement method". However,-in the table indicates the contraction side, and + indicates the expansion side.

[0059]

[Table 1]

Continued on the front page (51) Int.Cl. ⁶ Identification code FI C04B 111: 70 (72) Inventor Yutaka Uemura 2,209 Aomi, Aomi-machi, Nishikubiki-gun, Niigata Pref.

Claims (4)

[Claims] An expanding substance produced by heat-treating a composition containing a CaO raw material, an Al ₂ O ₃ raw material, and a CaSO ₄ raw material,
O, Al ₂ O ₃ , and a mineral containing CaSO ₄ as an active ingredient,
In addition, the component ratio in the mineral is such that the molar ratio of CaO / Al ₂ O ₃ is 6.5.
Brain value with CaSO ₄ / Al ₂ O ₃ molar ratio of 1.5 to 4 at ~ 18
A cement admixture for grout, comprising a swelling substance of 4,000 cm ² / g or more and a polycarboxylic acid polymer having a carboxyl group and a polyalkylene oxide structure in a side chain. 2. A polycarboxylic acid-based polymer having a carboxyl group and a polyalkylene oxide structure in a side chain is a copolymer comprising a polyalkylene glycol alkenyl ether represented by the general formula (1) and maleic anhydride, or a copolymer thereof. The cement admixture for grout according to claim 1, which is a hydrolyzate and / or a salt of the hydrolyzate. Embedded image (R1 is a vinyl group, an allyl group, AO is an oxyalkyl group having 2 to 4 carbon atoms, n is an integer of 1 to 100, and R2 is hydrogen or an alkyl group having 1 to 4 carbon atoms) 3. A grout cement admixture characterized in that the grout cement admixture according to claim 1 or 2 further comprises a fluidizing agent and / or an antifoaming agent. 4. A cement composition comprising cement and the cement admixture for grout according to claim 1, 2 or 3.