JPH10279343A - Cement composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cement composition used for civil building material. SOLUTION: This composition is composed of 100 pts.wt. cement having >=60 wt.% 3CaO.SiO2 content, 1-5 pts.tw. anhydrous gypsum, 0.2-3 pts.wt. aluminum sulfate expressed in terms of anhydrous gypsum anhydride, 0.1-0.8 pts.wt. alkali metal aluminate and 0.01-5.0 pts.wt. polycarboxylic acid polymer per 100 pts.wt. total amount of the cement, anhydrous gypsum, aluminum sulfate and alkali metal aluminate. A concrete good in initial stage strength manifesting property, and also low in slump drop and eliminating a need of tamping is obtained by using the composition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cement composition mainly used in the fields of civil engineering and construction.

[0002]

2. Description of the Related Art In recent years, due to difficulties in securing on-site workers and an increase in large-scale construction, for the purpose of labor saving of construction, a water reducing agent, a thickening agent, and the like are mixed with ordinary Portland cement or mixed cement. Concrete compounding compositions that do not require compaction or can be compacted by microvibration have been proposed and put into practical use (Japanese Patent Application Laid-Open Nos. 3-45522 and 3-3-522).
No. 237049).

[0003] However, these concrete composition compositions have a problem that the initial strength development is poor and the slump drop is large because a water reducing agent or a thickening agent is added to ensure workability.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to develop a concrete compounding composition having a small initial slump and a good initial strength.

[0005]

Means for Solving the Problems The present inventor has conducted various studies to solve the above-mentioned problems, and as a result, by using a specific cement composition, it is possible to obtain a good initial strength development and a slump. The present invention has been completed by obtaining the knowledge that compaction-free concrete with little drop and high material separation resistance can be obtained.

That is, the present invention relates to a cement composition comprising a cement having a 3CaO.SiO ₂ content of 60% by weight or more, gypsum anhydride, aluminum sulfate, an alkali metal aluminate and a polycarboxylic acid polymer. is there.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, 3CaO.Si
When the cement having an O ₂ content of 60% by weight or more is 100 parts by weight, anhydrous gypsum is 1 to 5 parts by weight, aluminum sulfate is 0.2 to 3 parts by weight in terms of anhydride, and alkali metal aluminate is 0 to 0 parts by weight. 0.1 to 0.8 parts by weight and the range of 0.01 to 5.0 parts by weight based on 100 parts by weight of the total amount of cement, anhydrous gypsum, aluminum sulfate, and alkali metal aluminate when the polycarboxylic acid polymer is 100 parts by weight. Is preferred.

The cement used in the present invention is 3CaO.
SiO ₂ content is not less than 60 wt%, 3Ca
The O.SiO ₂ content is preferably at least 66% by weight. 60
If the amount is less than the weight percentage, sufficient initial strength may not be obtained. Normally, commercially available early-strength Portland cement can be used.

The particle size of the cement has a Blaine value of 3,50.
It is preferably from 0 to 7,000 cm ² / g,
0 to 5,000 cm2 / g is more preferable. If the Blaine value is less than 3,500 cm ² / g, sufficient initial strength may not be obtained, and if it exceeds 7,000 cm ² / g, the slump loss of concrete may increase.

The anhydrous gypsum used in the present invention is not particularly limited as long as it is an anhydride. Natural anhydrous gypsum naturally produced, anhydrous gypsum obtained by heat treating hemihydrate gypsum or dihydrate gypsum, In addition, anhydrous gypsum and the like generated as an industrial by-product can be used.

The particle size of anhydrous gypsum is a Blaine value of 2,
500 cm ² / g or more is preferable, and 4,000 c
m ² / g or more is more preferable. If it is less than 2,500 cm ² / g, there is a possibility that expansion failure may occur due to unhydrated gypsum in long-term aging.

The amount of anhydrous gypsum used is 100 cement.
1 to 5 parts by weight, preferably 3 to 4 parts by weight, based on parts by weight. If the amount is less than 1 part by weight, the initial strength is poorly expressed,
If the amount exceeds 5 parts by weight, there is a possibility that in the long-term aging, the unhydrated residual gypsum may cause expansion failure.

The aluminum sulfate is not particularly limited, and any water content can be used. In the present invention, the amount of aluminum sulfate used is defined as an anhydride equivalent. The amount of aluminum sulfate used is 1 cement
It is 0.2 to 3 parts by weight, preferably 1 to 2 parts by weight, based on 100 parts by weight in terms of anhydride. If the amount is less than 0.2 parts by weight, the initial strength is poor, and if it exceeds 3 parts by weight, the workability tends to be poor.

The alkali metal aluminate is indispensable for improving the initial, middle and long-term strength development, and is not particularly limited in component, but it is economical to use sodium aluminate. Preferred. The amount of the alkali metal aluminate used is 0.1 to 0.8 parts by weight, based on 100 parts by weight of cement, and 0.3 to 0.8 parts by weight.
0.5 parts by weight is more preferred. If less than 0.1 parts by weight,
In some cases, sufficient strength development may not be obtained, and when it exceeds 0.8 parts by weight, workability may be deteriorated.

The polycarboxylic acid polymer used in the present invention is a dispersant having a cement dispersing effect, a water reducing effect, and a fluidity retaining effect, such as a polymer having a carboxyl group in a side chain or a side chain. There is a polymer having a carboxyl group and a polyalkylene oxide structure in the chain.

Examples of the polycarboxylic acid polymer having a carboxyl group in the side chain that can be used in the present invention include, for example, JP-A-60-161363 and JP-A-61-14677.
No. 6, Japanese Patent Publication No. 63-5346, Japanese Unexamined Patent Publication No.
(Meth) acrylic acid, α-hydroxyacrylic acid, (meth) acrylic acid ester described in JP-A-83344, JP-B-7-17421, JP-A-58-173142, JP-B-5-75711 and the like. Homopolymers or copolymers of unsaturated dicarboxylic acids such as unsaturated monocarboxylic acids such as maleic acid (anhydride), itaconic acid (anhydride) and citraconic acid (anhydride), isobutylene, amylene,
Examples of the copolymer include an unsaturated vinyl monomer such as pentene, styrene, α-methylstyrene, sulfonated styrene, and vinyl ether, and an unsaturated dicarboxylic acid.

Examples of the polycarboxylic acid-based polymer having a carboxyl group and a polyalkylene glycol structure in the side chain include, for example, JP-A-6-256054 and JP-B-6-56054.
And unsaturated vinyl monomers such as vinyl ether-maleic anhydride copolymer, olefin-maleic anhydride copolymer and styrene-maleic anhydride copolymer described in JP-A-88818 and JP-B-6-88817. There is an esterified product of a dicarboxylic acid copolymer with an alkylene glycol compound.

Japanese Patent Publication No. 61-21486, Japanese Patent Publication No. 62-25163, and Japanese Patent Publication No. 58-38380
JP, JP-B-59-18338, JP-B 1-3
No. 8408, Japanese Patent Publication No. 1-34866, Japanese Patent Publication No. 1-367487, Japanese Patent Publication No. 1-364888,
JP-A-59-162157, JP-A-59-195
No. 565, JP-A-61-77652, JP-B-4-68323, JP-B-2-7898, JP-A-63-1117036, JP-A-8-48852.
Patent Documents, etc., having a functional group such as a (meth) acrylate ester group, a vinyl ether group, an allyl ether group, and a methallyl group as an unsaturated group, and having a hydroxyl group, an alkoxy group, and the like as a terminal group not involved in polymerization. There are copolymers containing a monomer composed of a polyalkylene glycol derivative having a linear or branched structure and an unsaturated carboxylic acid monomer such as an unsaturated monocarboxylic acid or an unsaturated dicarboxylic acid as an essential component.

Also, JP-A-6-271347, JP-A-6-298555, JP-A-6-298556, JP-A-7-157348, and JP-A-7-15
No. 7349, JP-A-7-187742, etc., an esterified product of a polyalkylene glycol-based compound of a copolymer comprising a polyalkylene glycol derivative having a vinyl ether group or an allyl ether group as an unsaturated group and maleic anhydride is used. is there.

Further, JP-A-8-12396, JP-A-62-216950, and JP-A-1-226557.
JP-A-6-206750, a polyalkylene glycol derivative having a (meth) acrylate group as an unsaturated group, an unsaturated monocarboxylic acid or unsaturated dicarboxylic acid, allylsulfonic acid, There is a copolymer of a monomer having a sulfonic acid group such as rilsulfonic acid.

Japanese Patent Application Laid-Open Nos. 7-53249, 7-215746, 8-165157
And a copolymer comprising a monomer comprising a polyoxyalkylene derivative described in JP-A-7-232945 and a carboxyl group-containing monomer as essential components.

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 Most preferred is the use of a polycarboxylic acid-based polymer comprising a salt of a product.

[0023]

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, R2 is hydrogen or an alkyl group having 1 to 4 carbon atoms)

In the general 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. Particularly, an oxyethylene group having 2 carbon atoms is preferable from the viewpoint of properties. 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 addition mole number n of the oxyalkylene group can be in the range of 1 to 100 mol. If it exceeds 100 moles, the dispersing performance deteriorates. Further, it is not preferable because the polymerizability with maleic anhydride decreases.

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 a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, and a tert-butyl group. From the viewpoint, a methyl group is preferred.

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 /. It is one. 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 based on an aqueous G
The weight average molecular weight in terms of polyethylene glycol measured by PC is preferably in the range of 3,000 to ⁵ × 10 ⁵ , and particularly preferably in the range of 3,000 to 1 × 10 ⁵ . If the weight average molecular weight is less than 3,000, sufficient dispersion performance cannot be obtained. On the other hand, when the weight average molecular weight is in the range of 5 × 10 ⁵ or more, the dispersing performance is lowered, and the production is difficult and the production cost is increased.

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 and isopropyl vinyl ether And copolymerizable monomers such as lower alkyl vinyl ethers such as n-butyl vinyl ether and isobutyl vinyl ether.

The polycarboxylic acid polymer used in the present invention can be used in the form of a powder or an aqueous solution. When used as a powder, if the polycarboxylic acid-based polymer itself is hardly powdered, a method of supporting the powder on an inorganic powder described in JP-A-6-239652. Alternatively, a powder made by a method of forming a salt with a polyvalent metal into a property that can be handled as a powder can also be used.

As a method of pulverizing the polycarboxylic acid-based 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 may be used. Solution, aqueous solution of copolymer or melted copolymer melted by heating, adding calcium hydroxide or calcium hydroxide-water slurry, neutralizing reaction, and then drying and pulverizing to obtain copolymer calcium salt, by polymerization After the obtained copolymer-organic solvent solution is converted into an aqueous copolymer solution by stripping with heated steam, it is reacted with calcium hydroxide, dried and pulverized to obtain a copolymer calcium salt.

The average particle size of the polycarboxylic acid polymer used in powder form is preferably from 0.1 to 500 μm. The powder having an average particle diameter of 500 μm or more is 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.

The amount of the polycarboxylic acid polymer to be used is preferably 0.01 to 5.0 parts by weight based on 100 parts by weight of the binder comprising cement, anhydrous gypsum, aluminum sulfate and alkali metal aluminate. 0 to 3.0 parts by weight is more preferred. If the amount is less than 0.01 part by weight, sufficient dispersibility cannot be obtained. If the amount exceeds 5.0 parts by weight, coagulation delay may be caused, which is not economically preferable.

As an apparatus for mixing each material of the present invention,
Any existing stirring device can be used, for example, a tilting mixer, an omni mixer, a V-type mixer, a Henschel mixer, and a Nauta mixer can be used. The mixing may be performed by mixing the respective materials at the time of construction, or a part or all of them may be mixed in advance.

In the present invention, in addition to the above-mentioned materials, a setting modifier, an AE agent, an antifoaming agent, a thickening agent, an aggregate such as sand and gravel, a cement expanding agent, a rust preventive, an antifreeze, a polymer Emulsion,
Calcium compounds such as calcium oxide and calcium hydroxide, alkali metal sulfates, alkali metal sulfites, sulfates such as alkali metal bisulfites, clay minerals such as bentonite, zeolites, hydrotalcite, and hydrocalumite One or more of an ion exchanger, an inorganic phosphate, and boric acid can be used in combination within a range that does not substantially inhibit the object of the present invention.

In the present invention, in order to adjust the amount of entrained air in the cement composition, lower alcohols, higher alcohols, oils and fats, fatty acids, fatty acid esters, phosphate esters, metal soaps, and mineral oils are used. Conventionally known antifoaming agents such as polyethers and silicones can be used. Of these, preferred are polymeric defoamers,
Polyoxyalkylenes such as polyoxyethylene polypropylene adducts, polyoxyalkylene alkyl ethers obtained by etherifying part of the terminal structure of polyoxyalkylene with an alkyl group, part of the terminal structure of polyoxyalkylene is an aryl group or Polyoxyalkylene (alkyl) aryl ethers etherified with an alkylaryl group, acetylene ethers obtained by addition polymerization of acetylene alcohol with alkylene oxide, and polyoxyalkylenes obtained by esterifying a part of the terminal structure of polyoxyalkylene with fatty acid Fatty acid esters, polyoxyalkylene alkyl (aryl) ether sulfates having sulfate groups introduced therein, polyoxyalkylene alkyl phosphates having phosphate groups introduced therein, Polyoxyalkylene defoamer polyoxyalkylene alkylamines such as the introduction of the group is particularly 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 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,
A method in which a powdery polycarboxylic acid-based water reducing agent and a powdery antifoaming agent are previously 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 used is preferably from 0.01 to 10 parts by weight, particularly preferably from 0.05 to 5 parts by weight, per 100 parts by weight of the polycarboxylic acid-based water reducing agent. 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. May be increased, which is not preferable in terms of both performance and cost.

In the present invention, a thickener can be used in combination for the purpose of improving the viscosity of the cement composition and preventing material separation such as bleeding and aggregate sedimentation, and preventing material separation and obtaining high fluidity. Examples of thickeners that can be used in combination include cellulosic polymers such as methylcellulose, ethylcellulose, methylethylcellulose, hydroxyethylcellulose, and hydroxypropylcellulose; starch, natural polysaccharides such as xanthan gum, gum arabic, welan gum, and sodium alginate; polyvinyl alcohol; and polyacryl. And synthetic polymers such as sodium acid, polyvinylpyrrolidone, polyethylene oxide, polyacrylamide, and polyvinyl acetate. Among these, a cellulosic polymer is preferable in that the effect is large.

The amount of the thickener to be used is preferably 0.0001 to 1.0 part by weight, and
The amount is more preferably from 0.01 to 0.5 part by weight. Less than 0.0001 parts by weight has no effect.

In the present invention, a polycarboxylic acid polymer and a setting retarder can be used in combination for the purpose of adjusting the setting time of the cement mortar. As the setting retarder, organic acids, alcohols, phosphates, and borates can be used.
Among these, gluconic acid is more preferable from the viewpoint of compatibility.

The amount of the organic acid to be used is preferably 0.05 to 3 parts by weight, more preferably 0.1 to 2 parts by weight, based on 100 parts by weight of cement. If the amount is less than 0.05 part by weight, there is no effect, and if the amount is more than 3 parts by weight, curing is excessively delayed, which may result in poor curing.

[0044]

By using the cement composition of the present invention, it is possible to obtain concrete which has good initial strength development, has little slump drop and does not require compaction.

[0045]

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

Example 1 Production of polycarboxylic acid-based water reducing agent (1) Production example of polyalkylene glycol alkenyl ether (A) Thermometer, stirrer, reflux device, acetylene gas introduction pipe, nitrogen introduction pipe, acetylene gas flow rate integration A methoxypolyethylene glycol (molecular weight: 2,000, average number of moles of EO added: 44) was placed in a glass autoclave equipped with a meter.
0 g and potassium hydroxide 0.3 g (30 mol% based on methoxypolyethylene glycol) were charged, and after confirming that there was no leakage in the apparatus, the temperature in the autoclave was adjusted to 120.
While the temperature was raised to ° C, the inside of the apparatus was purged with nitrogen by nitrogen bubbling. The added potassium hydroxide was completely dissolved during this time. After the internal temperature stabilized at 120 ° C, the supply of acetylene was started, and the absorption of acetylene disappeared in about 9 hours.
The supply of acetylene was stopped, and the autoclave was replaced with nitrogen, cooled, and disassembled. The obtained reaction product was subjected to removal of impurities with an acid / alkali adsorbent to obtain a pale yellow-white solid purified product.

(2) Production Example of Dissolved Polycarboxylic Acid-Based Water Reducer A Polyalkylene glycol alkenyl ether and maleic anhydride used in a 1 L gas autoclave equipped with a thermometer, a stirrer, a dropping device, a vacuum line, and a nitrogen gas inlet tube. The polyalkylene glycol vinyl ether (molecular weight: about 2026, EO
Average number of moles added 45) 324 g, anhydrous maleic 16 g
(Molecular weight: 98) and the monomer concentration is 50.
340 g of a toluene solvent was charged so as to be a weight%.
Thereafter, pressure reduction / nitrogen bubbling was repeated to replace the inside of the autoclave with nitrogen, the internal pressure of the autoclave was returned to normal pressure by introducing nitrogen, and the temperature inside the autoclave was raised to 80 ° C. After the internal temperature is stabilized at 80 ° C., 113 ml of an initiator solution composed of 3% by weight of 2,2′-azobisisobutyronitrile in a toluene solvent is divided for a polymerization time of 3 hours while paying attention to heat generated by polymerization heat. Was added. After performing the polymerization reaction for 5 hours while controlling the temperature of the polymerization solution at 80 ° C. while controlling the external temperature, the polymerization solution was sampled, and the polymerization rate was 100% based on maleic anhydride. Next, the autoclave was cooled and disassembled, the polymerization solution was taken out, and the solvent was removed by drying under reduced pressure to obtain a waxy copolymer at room temperature. About the obtained copolymer, GPC (Gel Per
The weight average molecular weight was 30,000 as measured by polyethylene glycol or polyethylene oxide in terms of molecular weight by means of Meatin Chromatography.

The obtained copolymer was dissolved in 17 parts by weight of the copolymer in 100 parts by weight of water, neutralized with sodium hydroxide, and then subjected to a liquid defoaming agent (liquid defoaming agent, Denka Grace product, F
-224) was added in an amount of 0.2% based on the solid content of the copolymer to obtain a liquid polycarboxylic acid-based water reducing agent A. The copolymer sodium salt obtained by removing water from the liquid water reducing agent A by drying under reduced pressure was solid, but the melting temperature was 50 ° C.
The powder having a particle size of 200 μm or less by pulverization had a high hygroscopicity, and as such, was very difficult to handle as a powdery admixture.

(3) Production Example of Liquid Polycarboxylic Acid Polymer B As polyalkylene glycol alkenyl ether, methoxy polyethylene glycol allyl ether (average molecular weight: 1500, average number of moles of added EO: 33 mol, Nippon Oil & Fat Products UNIOX PKA-5010) It was used. In a 1 L glass autoclave equipped with a thermometer, a stirrer, a dropping device, a vacuum line, and a nitrogen gas inlet tube, methoxypolyethylene glycol allyl was added so that the molar ratio of polyalkylene glycol alkenyl ether and maleic anhydride became 1/1. 653.3 g of ether (molecular weight 1500, average number of moles of added EO: 32), maleic anhydride 4
2.7 g (molecular weight: 98) and 7 g of lauroyl peroxide (LPO) as an initiator were charged. Then,
Nitrogen bubbling was repeated to replace the inside of the autoclave with nitrogen, and the internal pressure of the autoclave was returned to normal pressure by introducing nitrogen.
The temperature inside the autoclave was raised to 80 ° C. After performing a polymerization reaction for 5 hours while controlling the external temperature so as to keep the internal temperature of the polymerization solution at 80 ° C., the polymerization solution was sampled and the polymerization rate was measured. As a result, the polymerization rate was 57% based on maleic anhydride.
Met. Thereafter, the reaction was continued at 80 ° C. for 22 hours while stirring. The polymerization rate at 22 hours was 60% based on maleic anhydride. Then cool the autoclave,
After disassembly, the polymerization solution was taken out to obtain a waxy copolymer at room temperature. The weight average molecular weight of the obtained copolymer was 30,000. The obtained copolymer was dissolved in 17 parts by weight with respect to 100 parts by weight of water, neutralized with calcium hydroxide, and then a liquid defoaming agent (Denka Grace, F-224) was added in an amount of 0.1% based on the solid content of the copolymer. 2% was added to obtain a liquid polycarboxylic acid-based water reducing agent B.

(4) Production Example of Powdered Polycarboxylic Acid-Based Water Reducer C The copolymer calcium salt obtained by dissolving the copolymer used in the liquid polycarboxylic acid-based water reducer A in water and neutralizing with calcium hydroxide. An aqueous solution was obtained. Water was removed from the aqueous solution of the copolymer calcium salt by drying under reduced pressure, and the copolymer calcium salt was taken out and pulverized by a pulverizer 2 to obtain a powder having a particle size of 200 μm or less. 100 parts by weight of the obtained powder and 0.5 parts by weight of a powdery antifoaming agent (San Nopco, Deformer SN-DF14HP) were mixed to obtain a powdery polycarboxylic acid-based water reducing agent C.
The resulting powdery water reducing agent C was heated to confirm a change in properties.
Even when heated to 0 ° C., no change was observed, the hygroscopicity was low, and it could be handled as a powder admixture.

Example 2 Using a binder comprising 100 parts by weight of cement, 4 parts by weight of anhydrous gypsum, 1 part by weight in terms of anhydrous aluminum sulfate, and 0.5 part by weight of alkali aluminate, as shown in Table 1, was used in concrete. A unit amount of 400 kg / m ³ binder, 1 water
91 kg / m ³ , fine aggregate 990 kg / m ³ , and coarse aggregate 8
The concrete was adjusted to 25 kg / m ³ and mixed with a water reducing agent as shown in Table 1, and the slump flow and the compressive strength were measured. The results are also shown in Table 1. The water reducing agent in the form of an aqueous solution was mixed and added simultaneously with the water, and the powdered water reducing agent was previously mixed with the binder and used.

[0052] <Materials Used> cement α: Denki Kagaku Kogyo Co., Ltd. high-early-strength portland cement 3CaO · SiO ₂ content 66% by weight Blaine value 4,460cm ₂ / g cement β: Denki Kagaku Kogyo Co., Ltd. high-early-strength Portland cement 54 weight parts and mixed products 3CaO · SiO ₂ content of 60 wt% Blaine value of ordinary portland cement 46 parts by weight 3,870cm ² / g cement gamma: Denki Kagaku Kogyo Co., Ltd. ordinary portland cement 3CaO · SiO ₂ content of 53 wt% Blaine 3,340 cm ² / g anhydrous gypsum: natural anhydrous gypsum, Blaine value 4,12
0 cm ² / g aluminum sulfate: powdered sulfuric acid band manufactured by Mizusawa Chemical Industries,
Al ₂ O ₃ 17% by weight, water content 43% by weight Alkaline aluminate: sodium aluminate, reagent 1
Grain Brain value 3,690 cm ² / g Water reducing agent: admixture A, B, C of Example 1 Fine aggregate: sand from Himekawa, Niigata Coarse aggregate: gravel from Himekawa, Niigata Water: tap water

<Test method> Slump flow value: According to the Manual for Underwater Non-separable Concrete, Appendix, "Test of Underwater Separable Concrete, Slump Flow Test" issued by Foundation, Coastal Development Technology Center and Fishing Port and Fishing Village Construction Technology Research Institute. Measure the spread of concrete at two points at right angles. Compressive strength: Measure a specimen of 10φ × 20cm

[0054]

[Table 1]

Example 3 The same procedure as in Example 2 was carried out except that cement α was used and the amount of anhydrous gypsum was changed as shown in Table 2.
The results are also shown in Table 2.

[0056]

[Table 2]

Example 4 Using cement α, the amount of aluminum sulfate used is shown in Table 3.
The procedure was performed in the same manner as in Example 2 except that the temperature was changed as shown in FIG. The results are also shown in Table 3.

[0058]

[Table 3]

Example 5 The same procedure as in Example 2 was carried out except that the amount of the alkali metal aluminate used was changed as shown in Table 4 using cement α. The results are also shown in Table 4.

[0060]

[Table 4]

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C04B 22:08 24:26)

Claims (4)

[Claims] 1. The content of 3CaO.SiO ₂ is 60% by weight.
A cement composition comprising the above cement, anhydrous gypsum, aluminum sulfate, alkali metal aluminate and a polycarboxylic acid polymer. _{2. The} content of 3CaO.SiO ₂ is 60% by weight.
100 parts by weight of the above cement, anhydrous gypsum 1-5
Parts by weight, aluminum sulfate is 0.2 to 3 parts by weight in terms of anhydride, alkali metal aluminate is 0.1 to 0.8 parts by weight, and the polycarboxylic acid polymer is cement, anhydrous gypsum, aluminum sulfate and The cement composition according to claim 1, wherein the total amount of the alkali metal aluminate is 0.01 to 5.0 parts by weight based on 100 parts by weight. 3. The polycarboxylic acid polymer is a polymer having a carboxyl group in a side chain, or a polymer having a carboxyl group and a polyalkylene oxide structure in a side chain. Cement composition. 4. The polycarboxylic acid polymer is a copolymer of polyalkylene glycol alkenyl ether represented by the general formula (1) and maleic anhydride, or a hydrolyzate and / or a salt of the hydrolyzate thereof. The cement composition according to claim 1, wherein the composition is provided. Embedded image (R1 is a vinyl group, an allyl group, AO is an oxyal 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)