JP2001064072A - Cement composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a cement composition which has higher flowability sustainable for a practically sufficient time and superior quick hardening properties as compared with a mixed quick hardening composition conventionally used and accordingly enables shortening of a construction period and efficient execution of construction work. SOLUTION: This cement composition contains: (A) cement consisting essentially of a calcium aluminate based compound(s); and (B) a powdery cement dispersant obtained by adding a reducing inorganic compound and a reducing organic compound to a liquid consisting essentially of a polycarboxylic acid based high molecular compound(s) having a polyalkylene glycol chain, drying the resulting material and pulverizing the dried material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cement composition having fast-setting properties used for repair and emergency work in the field of civil engineering and construction, and more particularly to a cement composition supplied in a ready-mixed state.

Heretofore, a cement composition having a quick-setting property has been widely used for various repair works, emergency works, production of concrete products, etc. by utilizing the quick-setting property. In order to exhibit quick-setting properties, cements containing calcium aluminate as a main component are generally used for the cement composition, and calcium aluminates having extremely high reactivity are rapidly hydrated due to rapid hydration. Although exhibited, the rapid hydration of calcium aluminates significantly lowers the fluidity of the cement composition and deteriorates workability, and is usually an organic system for delaying the hydration of calcium aluminates. Addition of a retarder or a cement dispersant prevents a decrease in fluidity.

[0003] A fast-setting cement composition, which is prepared by mixing a cement containing calcium aluminates as a main component, a cement dispersant, and if necessary, an aggregate and other cement admixtures, has a fluidity. Powdered cement dispersant mainly composed of naphthalenesulfonate formalin condensate and melaminesulfonate formalin condensate, and a setting retarder such as citric acid. It may be done.

[0004] Conventionally, most repair works and emergency works have many time constraints such as road and bridge works. However, in recent years, with the worsening traffic conditions, shortening of the construction period has been more strongly required. Further, even a cement composition having a quick-setting property has a higher quick-setting property, and an improvement in fluidity has been desired for improving work efficiency.

However, since the conventional powdery cement dispersant has relatively low water-reducing and fluidity retaining effects, in order to maintain high fluidity, the amount of the powdery cement dispersant added must be increased or the water-cement ratio must be increased. Had to be higher. However, when the amount of the powdery cement dispersant added is increased or the water-cement ratio is increased, there is a problem that the setting is delayed more than necessary, the quick-setting property is impaired, and the strength is reduced. The setting retarder is usually used together with a cement dispersant, but when used in combination with a powdery cement dispersant mainly containing a conventional naphthalene sulfonate formalin condensate or a melamine sulfonate formalin condensate, In order to maintain a high fluidity, a large amount of a setting retarder is required, and as a result, there is a problem that setting is delayed more than necessary and quick setting property is reduced. Further, in a cement dispersant containing a sulfonate-based formalin condensate as a main component, formalin is a harmful substance, so that it must be restricted in handling and use thereof.

In recent years, cement dispersants containing a polycarboxylic acid-based polymer compound having a high fluidity retaining effect as a main component have been used as a water reducing agent for concrete. However, this cement dispersant has been manufactured as an aqueous solution. For this reason, it has not been possible to mix it in a ready-mixed cementitious composition having quick-setting properties in advance.

On the other hand, powdering of a dispersant containing a polycarboxylic acid polymer as a main component has been attempted, but a known powdering technique (Japanese Patent Publication No. 7-14829) has been proposed.
When trying to obtain a powdery dispersant with high solubility in water,
An insoluble gel was formed during the powder production process, and the obtained powder was liable to lack stability in properties such as dispersing action. Also, a powdering method using a spray drying device (Patent No. 2
No. 669761) is also known, but since a large amount of inorganic powder must be used in combination, the content of the polycarboxylic acid-based polymer compound in the dispersant decreases, or the polycarboxylic acid-based polymer compound is adsorbed by the inorganic powder, and is dissolved in an aqueous solution. There was a problem that the dispersion performance was lower than when used.

[0008]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned problems and to provide a cement composition which is excellent in fluidity and rapid setting.

[0009]

The present inventors have conducted various studies and found that a reducing inorganic compound and a reducing organic compound were added to a solution containing a polycarboxylic acid polymer compound having a polyalkylene glycol chain. By dry powdering, a powdery cement dispersant with excellent fluidity can be obtained efficiently,
Combining this with a cement containing calcium aluminates as the main component ensures necessary and sufficient fluidity,
In addition, they have found that rapid hardening can be obtained, and have completed the present invention.

That is, the present invention relates to (A) a cement containing calcium aluminates as a main component, and (B) a liquid containing a polycarboxylic acid polymer compound having a polyalkylene glycol chain as a main component. It is an object of the present invention to provide a cement composition containing a powdery cement dispersant obtained by adding a compound and a reducing organic compound, followed by drying and powdering.

[0011]

A cement composed mainly of calcium aluminates used in the Detailed Description of the Invention The present invention (A) are, lime, CaO and Al ₂ O in the clinker obtained by firing a raw material containing alumina component such as CaO-Al ₂ containing ₃ as a main component
O ₃ minerals, ie, calcium aluminates
It is a pulverized product of such a clinker. Further, the cement may be obtained by mixing the clinker pulverized product with Portland cement,
In addition, the cement contains other inorganic hydraulic components such as Ca
Calcium silicates containing O and SiO ₂ as main components may be included. Calcium aluminates, which are the main components of the cement, are C for CaO, A for Al ₂ O ₃ ,
Then, C ₃ A, C ₃ A ₃ .CaSO ₄ , C ₁₂ A ₇ , C ₁₁
If A ₇ .CaF ₂ and F ₂ O ₃ are F, C ₆
A component represented by a mineral composition such as A ₂ F and C ₄ AF, that is, C /
It is a compound containing at least one of the compounds having a molar ratio of A of 0.5 to 4.0 as a main component. Further, a material containing a small amount of impurities such as SiO ₂ and TiO ₂ as a trace component may be used. Of these, C ₃ A, C ₃ A ₃ .CaSO ₄ ,
Calcium aluminates containing C ₁₂ A ₇ , C ₁₁ A ₇ .CaF ₂ alone or a combination thereof as a main component are more preferred. As the cement (A) containing such calcium aluminates as a main component, a commercially available product called "Jet Cement" (manufactured by Taiheiyo Cement Corporation) is known.

The powdery cement dispersant (B) blended in the cement composition of the present invention comprises a liquid containing a polycarboxylic acid polymer having a polyalkylene glycol chain as a main component as described above. And a reducing organic compound, and dried to obtain a powder. The polycarboxylic acid-based polymer compound having a polyalkylene glycol chain used herein is not particularly limited. For example, (B ¹ ) a (meth) acrylic acid-based copolymer having a polyalkylene glycol chain and (B ² ) A maleic acid-based copolymer having a polyalkylene glycol chain (however, in the case of (B ² ), excluding a polyvalent metal salt) and the like, and these may be used alone or in combination of two or more. .

Of these, (B ¹ ) includes a group —CO
Preferred are OM (wherein M represents a hydrogen atom, an alkali metal, an alkaline earth metal, ammonium or an organic amine) and a (meth) acrylic acid-based copolymer having a polyalkylene glycol chain. Preferred examples of (B ² ) include polyalkylene glycol alkenyl ether-maleic anhydride copolymer (excluding polyvalent metal salts).

M in the group (COOM) of the (B ¹ ) (meth) acrylic acid copolymer is a hydrogen atom; an alkali metal such as sodium or potassium; an alkaline earth metal such as calcium or magnesium; ammonium or an organic compound. Amines are preferred.

The polyalkylene glycol chain in the above (B ¹ ) and (B ² ) includes —O (CH ₂ CH (R
^a ) O) _b- those represented by-are preferred. Here, Ra represents ^a hydrogen atom or a methyl group, and b is 2 to 200, preferably 5 to 109, particularly preferably 20 to 109, and more preferably 30 to 109.

Further, (B ¹ ) a preferable (meth) acrylic acid-based copolymer is a structural unit (1) represented by the following formula (1) in an amount of 40 to 80 mol% in all the structural units.
The structural unit (2) represented by the following formula (2) is 2 to 25 mol%, and the structural unit (3) represented by the following formula (3) is 3 to 20 mol%.
Mole% and a number average molecular weight of 2,000 having a structural unit (4) represented by the following formula (4) at a ratio of 1 to 45 mole%.
50,000 (meth) acrylic acid copolymers.

[0017]

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[0018] ^{wherein, R 1, R 2, R} 4 and R ⁵ are the same or different and represent a hydrogen atom or a methyl group, R ³
And R ⁶ represent an alkyl group having 1 to 3 carbon atoms, M ¹ represents a hydrogen atom, an alkali metal, an alkaline earth metal, ammonium or an organic amine, and X represents —SO ₃ M ² or —
O-Ph-SO ₃ M ² (where M ² represents a hydrogen atom, an alkali metal, an alkaline earth metal, ammonium or an organic amine, and Ph represents a phenylene group), and n is an integer of 2 to 200 Show)

In the above formulas (1) to (4), R ¹ , R ² , R
⁴ and R ⁵ are preferably a methyl group. Further, as R ³ and R ⁶ , a methyl group, an ethyl group, an n-propyl group,
An i-propyl group is mentioned, and a methyl group is particularly preferable.
Further, as M ¹ , sodium, potassium, calcium, magnesium, alkanolamine and the like are preferable,
Particularly, sodium is preferable from the viewpoint of solubility in water. Examples of M ² in the group X include alkali metal atoms such as sodium and potassium, alkaline earth metals such as calcium and magnesium, and organic amines such as alkanolamines such as ammonium and ethanolamine. As Among these X, -SO ₃ Na are preferred. In the formula (4), n is 2 to 200,
109 is preferred, especially 20 to 109, more preferably 30 to 1
09 is preferred. The content of the structural unit (1) is preferably from 40 to 80 mol%, and particularly preferably from 45 to 75 mol%. The content of the structural unit (2) is preferably 2 to 25 mol%, and particularly preferably 5 to 20 mol%. The content of the structural unit (3) is preferably from 3 to 20 mol%, particularly preferably from 5 to 15 mol%. Further, the content of the structural unit (4) is preferably from 1 to 45 mol%, particularly preferably from 3 to 40 mol%. In addition, mol% of a structural unit shows mol% of each structural unit when all the structural units of (1)-(4) are 100 mol%.

In particular, as the preferable (B ¹ ) (meth) acrylic acid copolymer, 40 to 70 mol% of a structural unit (5) represented by the following formula (5) in all the structural units: A structural unit (6) represented by the following formula (6) is
Mol%, the structural unit (7) represented by the following formula (7) is 1 to
Number average molecular weight having 20 mol%, 1 to 30 mol% of the structural unit (8) represented by the following formula (8), and 1 to 30 mol% of the structural unit (9) represented by the following formula (9). 2
000 to 50,000 (meth) acrylic acid-based copolymers.

[0021]

Embedded image

Wherein R ⁷ , R ⁸ , R ¹⁰ , R ¹¹ , R ¹³ and R ¹⁴ are the same or different and each represent a hydrogen atom or a methyl group, and R ⁹ , R ¹² and R ^{15 each} have 1 to 1 carbon atoms. 3 represents an alkyl group, M ³ represents a hydrogen atom, an alkali metal, an alkaline earth metal, ammonium or an organic amine, and Y represents —SO ₃ M ⁴ or —O-Ph—SO ₃ M ⁴ (where M ^Four
Represents a hydrogen atom, an alkali metal, an alkaline earth metal, ammonium or an organic amine, Ph represents a phenylene group), m represents an integer of 2 to 200, and p represents 2 to 200.
Indicates an integer of 109. ]

In the above formulas (5) to (9), R ⁷ , R ⁸ , R
¹⁰ , R ¹¹ , R ¹³ and R ¹⁴ are preferably a methyl group. Examples of R ⁹ , R ¹² and R ¹⁵ include a methyl group, an ethyl group, an n-propyl group, and an i-propyl group, with a methyl group being preferred. As M ³ and M ⁴ , sodium, potassium, calcium, magnesium, alkanolamine and the like are preferable, and sodium is particularly preferable. The -SO ₃ Na is preferably a group Y. (8) In the formula, m is 2 to 200,
Is preferred, and particularly preferably 20 to 109, and more preferably 30 to 109.
To 109 are preferable. Further, p in the expression (9) is 2 to 10.
9, but preferably 5 to 50. Structural unit (5) is 4
It is preferably from 0 to 70 mol%, particularly from 45 to 65 mol%.
Preferably it is mol%. Structural unit (6) is 5 to 3
It is preferably 0 mol%, particularly preferably 8 to 23 mol%. Structural unit (7) is 1 to 20 mol%
It is particularly preferable that the content is 1 to 15 mol%. The content of the structural unit (8) is preferably from 1 to 30 mol%, particularly preferably from 5 to 25 mol%. Further, the content of the structural unit (9) is preferably 1 to 30 mol%, and particularly preferably 3 to 25 mol%. In addition, mol% of a structural unit shows mol% of each structural unit when the total of all the structural units of (5)-(9) is 100 mol%.

The (meth) acrylic acid-based copolymer comprising the above structural units includes a number average molecular weight of 2,000 to 5,000.
0 (GPC method, polyethylene glycol equivalent) is preferable, and 3500 to 30,000 is more preferable.

On the other hand, maleic acid-based copolymers having (B ² ) alkylene glycol chains include methyl polyethylene glycol vinyl ether-maleic anhydride copolymer, polyethylene glycol allyl ether-maleic anhydride copolymer, methyl polyethylene glycol Allyl ether-maleic anhydride copolymer, methyl methacrylate polyethylene glycol-maleic acid copolymer and the like can be mentioned. A preferable number average molecular weight (GPC method, calculated as polyethylene glycol) of the copolymer (B ² ) is 30.
It is preferably from 2000 to 200,000, particularly preferably from 3000 to 80000.

Examples of the reducing inorganic compound include sulfite, nitrite, thiosulfate and the like. As these salts, alkali metal salts and alkaline earth metal salts are preferable. Although it is not clear why the addition of the reducing inorganic compound can prevent gelation during kneading and stirring in the drying step, the radical reaction in which the reducing inorganic compound remains in the polycarboxylic acid-based copolymer-containing liquid is initiated. It is considered to deactivate the agent. Therefore, the amount of the reducing inorganic compound to be added may be determined according to the type and amount of the radical reaction initiator remaining in the mixture, and usually, the solid content of the radical reaction initiator used in the synthesis of the polymer compound is determined. (Mol% value) or less, but the amount (mol% value) of the solid content of the remaining radical reaction initiator
It is desirable that the amount is not less than the amount capable of deactivating the oxidizing power of the residual radical reaction initiator.

The reducing organic compound is preferably an amine compound, especially an alkanolamine. Specifically, triethanolamine, diethanolamine, monoethanolamine, isopropanolamine, N, N
Alkanolamines such as diethylethanolamine,
Examples thereof include alkylamines such as sec-butylamine, and diamines such as ethylenediamine. By the addition of the reducing organic compound, the load on the kneading stirrer is greatly reduced, and the COD value of the distilled water discharged at the time of dry powder is reduced (200 mg / L or less).

The amount of each of the reducing inorganic compound and the reducing organic compound is 0.01 to 2.5% by weight, particularly 0.5 to 1% by weight, based on the solid content of the polycarboxylic acid polymer compound. 0.5% by weight is preferred. The addition of such a reducing organic compound reduces the load on the mixing stirrer in the drying and pulverization step, and also lowers the COD value of water distilled off during drying, because it is used as a crushing aid. It is presumed that the polymerization reaction proceeds at a low temperature near room temperature due to the amine effect while the unreacted monomer is consumed.

The powdery cement dispersant (B) used in the present invention can improve its hygroscopicity and blocking properties,
After drying to reduce measurement errors, in addition to the above essential components, a polyalkylene glycol, and a carbon number of 8 to 22
Or a salt thereof, or an inorganic powder.

Preferred examples of the polyalkylene glycol include polyethylene glycol having a molecular weight of 1,000 to 20,000, and polypropylene glycol having a molecular weight of 2,000 to 6,000. Among them, polyethylene glycol is particularly preferable, and further, the average molecular weight is 2,000.
Polyethylene glycol of ~ 4000 is preferred.

The fatty acid having 8 to 22 carbon atoms or a salt thereof may be saturated or unsaturated, and may be linear or branched. Specifically, caprylic acid, pelargonic acid, capric acid, undecylic acid, lauric acid,
Tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachiic acid, behenic acid, undecylenic acid, oleic acid, elaidic acid, setreic acid, erucic acid, brassic acid and salts thereof Can be As the salts of the above fatty acids, metal salts such as sodium, potassium, barium, calcium, zinc, aluminum and magnesium are preferable. In particular, stearic acid or a salt thereof is preferred,
Particularly preferred is calcium stearate. The compounding amount of these polyalkylene glycols and fatty acids having 8 to 22 carbon atoms or salts thereof is 0.2 to 30% by weight based on the solid content of the polycarboxylic acid polymer having a polyalkylene glycol chain, Particularly, 0.5 to 20% by weight is preferable.

As the inorganic powder, powders of inorganic salts such as calcium carbonate and calcium silicate, clay mineral powders such as kaolinite and bentonite, and fine powders such as blast furnace slag and fly ash can be used. Such an inorganic powder may be used up to about three times the solid content of the polycarboxylic acid polymer compound.

The liquid containing the polycarboxylic acid polymer as a main component may include a solution or dispersion of water or an organic solvent.

Since the polycarboxylic acid polymer-containing liquid is usually an acidic liquid, sodium hydroxide, potassium hydroxide and calcium hydroxide are added after adding a reducing inorganic compound and a reducing organic compound. PH 7 to 9 by adding an aqueous solution of an alkali metal or alkaline earth metal such as
It is preferred to adjust to. If the pH is not adjusted, the polymer compound in the mixture is liable to undergo hydrolysis during the heating and drying treatment, and the COD value of water distilled off during drying increases. When the polycarboxylic acid-based polymer compound-containing solution has a pH of 7 to 9 from the beginning, it is not necessary to adjust the pH by adding a pH adjuster.

The drying is not particularly limited as long as it is a convection type drying apparatus such as a hot air type or a heat conduction type drying apparatus. Flash jet dryers are suitable. When the processed product is a high-concentration solution exceeding 40% or a material having high viscoelasticity, it is preferable to use a drying machine such as a kneading stirring dryer or a band-type continuous vacuum dryer. However, since the polycarboxylic acid-based polymer compound having a polyalkylene glycol chain may become viscous during the concentration process, from the viewpoint of powdering efficiency and the like, it is particularly preferable to carry out kneading and stirring to dry powder. . Kneading
The stirring temperature is preferably about 40 to 120 ° C, more preferably about 60 to 110 ° C. The kneading / stirring can be carried out in the air, but it is desirable to carry out the kneading in a reduced pressure or an inert gas atmosphere such as nitrogen or argon from the viewpoint of preventing deterioration. Further, it is preferable that after concentrating until the hardness becomes 30 ° or more, it is dried and pulverized while kneading and stirring with a horsepower of 0.5 kg / m ³ / rpm or more. By performing such a drying operation, a powdery dispersant can be obtained. The dried powder may be agglomerated into small agglomerates, but the agglomerates are fragile and can be easily formed into single particles with a slight crushing force.

(B) The powdered dispersant has an average particle size of 5 to 2,000 by any pulverizing / classifying method for convenience in use.
It is desirable to adjust the thickness to μm, more preferably 10 to 500 μm. However, since the produced powder dispersant (B) is relatively weak to heat, a pulverizer having a low heat storage property is preferable, and specifically, a pin mill is preferable. There is also a pulverizer integrated with a screen for adjusting the particle size. However, since the heat of pulverization increases when unpulverized material stays, it is preferable to perform pulverization and classification separately.

If the amount of the powdery cement dispersant (B) thus obtained added to the cement composition of the present invention is too small, there is no effect, and if it is too large, it causes setting retardation and strength reduction. 0.005 to 5 parts by weight, more preferably 0.01 to 3 parts by weight, and particularly preferably 0.05 to 1.5 parts by weight, based on 100 parts by weight of cement containing as a main component.

In order to use the cement composition of the present invention as mortar or concrete, river sand, sea sand, land sand, crushed sand, silica sand and the like can be used as aggregates, and these sands are preferably dry sands. Further, fly ash, blast furnace slag, calcium carbonate, silica fume and the like can be used in combination with the above sand. When the cement composition is supplied as a pre-mixed mortar composition, the aggregate to be blended preferably has a particle size of 5 mm or less and an FM of about 1.5 to 3.0. The amount of aggregate used in the case of the mortar composition is 100 binders (cement mainly composed of calcium aluminates).
30-100 parts by weight, especially 60-150 parts by weight
Parts by weight are preferred.

In the cement composition of the present invention, a setting retarder or a setting accelerator for adjusting quick setting can be used. Any setting retarder can be used as long as it has an effect of delaying the hydration reaction of a cement containing calcium aluminates as a main component, and for example, has an oxycarboxylic acid group such as citric acid, tartaric acid, and gluconic acid. And the like. Examples of the accelerator include alkali metal salts such as potassium carbonate, sodium carbonate, sodium hydrogen carbonate, lithium carbonate, and sodium aluminate.

In addition to the above-mentioned materials, the cement composition of the present invention may further contain an expanding material, a shrinkage reducing agent, a thickening agent, a hardening property improving material (eg, gypsum), if necessary.
Also, various extenders, various admixtures, and the like can be used as long as they do not adversely affect the physical properties.

The cement composition of the present invention is usually provided in a state in which the above-mentioned materials are prepared, and is kneaded with water using a mixer at a building site or the like and then poured. The mixer used here is not particularly limited, and the amount of water to be added is usually 30 to 100 parts by weight with respect to 100 parts by weight of the binder (cement mainly composed of calcium aluminates).

[0042]

EXAMPLES Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited thereto. The materials used in the examples are as follows.

[Materials Used] (1) Binder (Cement containing calcium aluminates as a main component) Jet Cement (manufactured by Taiheiyo Cement Co., Ltd.) (2) Powder cement dispersant Powder cement dispersant according to the present invention Agents The polycarboxylic acid polymer compounds used for producing the powdery cement dispersant used in the present invention are shown below.

[0044]

[Table 1]

[0045]

[Table 2]

[Production Method of Powdered Cement Dispersant According to the Present Invention] To each of 800 g of a liquid mixture having a solid content of 45% and containing the high molecular compounds shown in Tables 1 and 2 as a main component,
10% by weight aqueous sodium hydroxide solution 7 for pH adjustment
5.2 g was added, and the mixture was stirred at room temperature for about 3 minutes. Next, sodium sulfite and triethanolamine as a reducing agent are added in an amount of 0.5 to 2% by weight based on the solid content, and the mixture is stirred for 3 minutes. The mixture was concentrated and dried while kneading under a reduced pressure of 30 torr. The obtained powder is pulverized with a pulverizer (MCG180 manufactured by Matsubara Co., Ltd.) to obtain a particle size of 50 to 500.
μm, powdered cement dispersants (1) and (2) shown in Table 3 were obtained.

[0047]

[Table 3]

Conventional powdery cement dispersant Mighty 100 (Naphthalene sulfonate formalin condensate manufactured by Kao Corporation)

(3) Setting regulator Citric acid setting retarder ("Jet Setter" manufactured by Onoda Co., Ltd.)

Table 4 shows examples of the composition of the cement composition of the present invention.

[0051]

[Table 4]

The performance test of the cement composition of the present invention was performed as follows. [Test Example] 40 parts by weight of water was added to 100 parts by weight of the material prepared according to the composition shown in Table 4, and the mixture was mixed for 3 minutes using a Hobart mixer. The setting time was measured as a value and quick-hardness evaluation. The test results are shown in Tables 5 and 6.

[Flow value measuring method] JIS R-520
1 Measured according to “Physical test method of cement”. [Method of measuring setting time] The setting time was measured according to JIS R-5201 “Physical test method of cement”.

[0054]

[Table 5]

[0055]

[Table 6]

As can be seen from Tables 5 and 6, the cement composition of the present invention can maintain high fluidity for a practically necessary period of time and has excellent quick-setting properties as compared with those using a conventional powdery cement dispersant. It was confirmed to have.

[0057]

Industrial Applicability The cement composition of the present invention can maintain high fluidity for a practically sufficient period of time as compared with a previously used quick-setting cement composition which has been conventionally used, and furthermore has an excellent quick-setting property. It is possible to shorten the construction period and increase the efficiency of construction.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) // C04B 103: 40 111: 00 (72) Inventor Hirotaka Isomura 2-4-2 Daisaku, Sakura City, Chiba Prefecture Taiheiyo Cement Co., Ltd. Sakura Research Institute (72) Inventor Koichi Soeda 2-4-2 Daisaku, Sakura City, Chiba Pref. Taiheiyo Cement Co., Ltd. Sakura Research Laboratory F-term (reference) 4G012 MB33 PA23 PB05 PB12 PB15 PB20

Claims (1)

[Claims] 1. A reducing inorganic compound and a reducing agent are added to (A) a cement mainly containing calcium aluminates and (B) a liquid mainly containing a polycarboxylic acid polymer having a polyalkylene glycol chain. A cement composition containing a powdery cement dispersant obtained by adding a water-soluble organic compound and then dry-pulverizing.