JP2001114545A - Cement admixture and cement composition made by using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a cement admixture and a cement composition made by using the admixture, capable of providing a concrete, a mortar, a grout or the like, having good fluidity, secured strength, effects for preventing the retardation of coagulation and effects for supressing heat of hydration. SOLUTION: This cement admixture contains (A) a modified starch selected from an etherified starch and an esterified starch, and (B) one or more kinds of surfactants selected from an aromatic sulfonic acid and a salt thereof, a condensate of the aromatic sulfonic acid and the salt thereof, a condensate of a triazine derivative, a ligninsulfonic acid salt and a derivative thereof, and a copolymer of a vinyl compound and an unsaturated dicarboxylic acid, and a derivative thereof. The cement composition contains the cement admixture.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a cement admixture which suppresses a temperature rise due to heat of hydration of cement in concrete, mortar, grout and the like, and a cement composition using the same.

[0002]

2. Description of the Related Art In recent years, civil engineering and building structures have become larger,
Mass concrete construction is increasing,
The heat generated by the hydration of the cement and its accumulation increase, so-called temperature cracks occur in the concrete due to the stress generated when the concrete temperature rises rapidly in the early age or when it falls. appear. As a method for preventing this, a method of adding dextrin having a water-soluble content of 10 to 65% by weight at a temperature of 21 ° C (Japanese Patent Publication No. 57-261), a method of adding dextrin having a cold-water-soluble content of 5 to 90% by weight, A method of adding a surface active agent for concrete (Japanese Patent Publication No. 56-28859) and a method of adding a modified starch having a gelatinization start temperature of 30 to 60 ° C and a 25% aqueous solution having a viscosity of 20 to 5000 centipoise at 50 ° C ( JP-A-6-305799) has been proposed. However, in these methods, the effect of suppressing the temperature rise due to the heat of hydration of the cement is not sufficient, and the setting may be delayed, so that the expected effect may not be obtained depending on the use conditions.

[0003]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a cement admixture which more effectively suppresses the temperature rise due to heat of hydration of cement, which causes cracks in concrete structures, and which does not cause setting delay. An object of the present invention is to provide a cement composition using the same.

[0004]

Means for Solving the Problems In order to solve the above problems, the present inventors have conducted intensive studies on the effect of various additives on the suppression of heat of hydration, and have found that a specific modified starch is combined with a specific surfactant. By doing so, the effect of suppressing the heat of hydration of cement is increased, and setting delay is not caused. Further, by using a cement admixture containing these, a cement composition having improved properties such as strength and fluidity can be obtained. And completed the present invention.

That is, the present invention provides (A) a modified starch selected from etherified starch and esterified starch, and (B) an aromatic sulfonic acid and a salt thereof, a condensate of an aromatic sulfonic acid or a salt thereof, and a triazine derivative. , A lignin sulfonate and a derivative thereof, and a cement admixture comprising one or more surfactants selected from a vinyl compound-unsaturated dicarboxylic acid copolymer and a derivative thereof. Is provided.

The present invention also provides a cement admixture containing the above cement admixture and (C) a hydration-expandable substance.

[0007] The present invention also provides a cement composition containing the above-mentioned cement admixture or cement admixture.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION As the modified starch (A) used in the present invention, potato, sweet potato, corn, tapioca, wheat and other raw starches are esterified (acetate, phosphate, etc.) or etherified (hydroxy). Alkylation, carboxymethylation, cationization, alkylation, benzylation, etc.). Of these, etherified starch is more preferable because it has a large effect of suppressing heat of hydration and has an effect of preventing coagulation delay. Further, among the etherified starches, hydroxyalkylated starch or cationized starch is more preferable, and cationized starch is particularly preferable. The modified starch (A) preferably has a solubility in water at 30 ° C. of 5% by weight or more.

(A) The amount of the modified starch is 10
It is preferable to add about 0.03 to 10 parts by weight to 0 parts by weight. When the amount is less than 0.03 parts by weight, the effect of suppressing heat of hydration is small, and when it exceeds 10 parts by weight, the initial strength is adversely affected. Sometimes. A particularly preferred addition amount is 0.1 to 2 parts by weight based on the cement.

The surfactant (B) used in the present invention includes aromatic sulfonic acid, aromatic sulfonic acid salt, condensate of aromatic sulfonic acid, condensate of aromatic sulfonic acid salt, condensate of triazine derivative, lignin One or more selected from sulfonic acid salts, derivatives of lignin sulfonic acid salts, vinyl compound-unsaturated dicarboxylic acid copolymers and derivatives of the copolymers, and these surfactants are those of (A) When used in combination with modified starch, the effect of suppressing heat of hydration increases.

The aromatic sulfonic acid or a salt thereof includes alkylbenzenesulfonic acid or a salt thereof, alkylphenolsulfonic acid or a salt thereof, alkylnaphthalenesulfonic acid or a salt thereof, aminobenzenesulfonic acid or a salt thereof, and the like. As the alkyl group, an alkyl group having 8 to 24 carbon atoms is preferable. Among these aromatic sulfonic acids or salts thereof, n-dodecylbenzenesulfonic acid or a salt thereof, and n-octadecylbenzenesulfonic acid or a salt thereof are more preferable.

Examples of the condensate of an aromatic sulfonic acid or a salt thereof include a formalin condensate of an alkylnaphthalene sulfonic acid or a salt thereof, and the alkyl group is preferably an alkyl group having 1 to 12 carbon atoms. As a condensate of an aromatic sulfonic acid or a salt thereof, a formalin condensate of a C ₁ -C ₆ alkylnaphthalene sulfonic acid or a salt thereof is more preferable.

Examples of the condensate of the triazine derivative include a formalin condensate of melamine sulfonic acid or a salt thereof, a formalin condensate of benzoguanamine sulfonic acid or a salt thereof, and a formalin condensate of methyl guanamine sulfonic acid or a salt thereof. Examples of the vinyl compound-unsaturated dicarboxylic acid copolymer include a styrene-maleic acid copolymer.

One or more of these surfactants can be used. (B) The amount of the surfactant added is 0.01 to 5 in terms of solid content based on 100 parts by weight of cement.
It is preferably added in parts by weight. If the amount exceeds 5 parts by weight, material separation may occur or the strength may be adversely affected. A particularly preferred addition amount is 0.1 to 4 parts by weight based on 100 parts by weight of cement.

Further, in the present invention, if (C) a hydration-expanding substance is added in addition to the (A) modified starch and (B) surfactant, it can be used as an expander or an admixture for cement-based fillers. It is a useful cement admixture. The (C) hydration expandable substance used here is broadly divided into two types: a substance that promotes expansion by foaming when hydrated and a substance that promotes expansion by the crystal pressure of crystals generated when hydrated. . As what promotes expansion by foaming,
Metallic aluminum powder, calcium carbide, etc. are mentioned.
• Calcium sulfoaluminate compounds represented by 3Al ₂ O ₃ .CaSO ₄ , aluminum compounds and gypsum, quicklime, magnesia, gypsum, commercially available expanding materials for concrete or cement, and the like.

One or more of these (C) hydration expandable substances can be used. In particular, metallic aluminum powder, quicklime contained in cement minerals, 3CaO
One or _{two of} 3Al ₂ O ₃ .CaSO ₄ , anhydrous gypsum
Those containing at least one kind of component as a main component are preferable. (C) The addition amount of the hydration-expanding substance is 0.001 to 100 parts by weight of cement, and the amount which promotes expansion by foaming is 0.001 to 0.001.
0.2 parts by weight;
0 parts by weight, especially those that promote expansion by foaming, 0.01 to 0.2 parts by weight, and those that promote expansion by crystallization pressure add 2 to 30 parts by weight. Preferred from the point.

The modified starch (A), the surfactant (B) and the hydrated swellable substance (C) in the present invention can be in the form of either an aqueous solution or a powder. Mixing, addition to kneading water, or kneading start time of the cement composition, that is, it is also possible to add at the same time or immediately after water injection to the cement until the end of kneading of the cement composition, and once kneaded. Addition to cement formulations is also possible. Either a method of adding the whole amount at a time or a method of adding the solution in several portions may be used.

Known cement can be used as the cement. Particularly preferred is a cement containing calcium silicate. For example, Portland cement (ordinary, high strength, ultra high strength, moderate heat, sulfate resistance, low alkali type, low heat), mixed cement (fly ash cement, blast furnace cement, silica cement) and the like can be used. Further, as a special cement, white cement, oil well cement, colloid cement, alumina cement, ultra-rapid hardening cement, expanded cement or the like may be used.

Also, aggregates such as sand and gravel, retarders, curing accelerators, foaming agents, defoaming agents, water retention agents, thickeners, waterproofing agents, rust inhibitors, crack reducing agents, polymer emulsions, One or more cement additives (materials) such as fibers can be used in combination as needed.

[0020]

Industrial Applicability The cement admixture of the present invention and the cement composition using the same provide concrete, mortar, grout, etc. with good fluidity, sufficient strength, an effect of preventing setting delay and an effect of suppressing heat of hydration. Can be

[0021]

Examples of the present invention will be described below. In addition, these are illustrations and do not limit this invention.

Test Example 1 Low heat Portland cement 2700 g, expansive material 300
g, 6000 g of Toyoura-made silica sand and 1500 g of water, kneading by adding 0.3 parts by weight (9 g) of modified starch and 0.4 parts by weight (12 g) of surfactant to 100 parts by weight of cement and expanding material in total. Mix and knead at about 20 ° C
Mortar adjusted to become 150x150
The temperature in the center of the mortar when placed in a styrene foam container of 200 mm and cured in a constant temperature room at 20 ° C. was automatically measured with a thermocouple, and the maximum temperature was determined. Table 1 shows the results.
Shown in

[Materials used] Hydration-expandable substance: lime-based expansive material (containing quicklime and anhydrous gypsum contained in cement mineral) [trade name: Expo Onoda (manufactured by Onoda Co., Ltd.)] Chemical starch: quaternary cation Starch and hydroxyalkylated starch (both manufactured by Nisseki Chemical Co., Ltd.)

[0024]

[Table 1]

Test Example 2 Low heat Portland cement 2700 g, expander 300
g, 6000 g of Toyoura-produced silica sand and 1500 g of water, and kneaded with the added amounts of the modified starch and the surfactant shown in Table 2, and adjusted the mortar to have a kneading temperature of about 20 ° C. Put in a styrene foam container of × 150 × 200mm, and automatically measure the temperature of the mortar center when cured in a 20 ° C constant temperature room with a thermocouple,
The maximum temperature was determined. In addition, using the same mortar, according to the Japanese Geotechnical Society standard “Uniaxial compression test method of soil” (T511), a specimen of φ50 × 100 mm was prepared using a steel mold, and a uniaxial compression test of 3 days of age was performed. went. Table 2 shows the results.

[Materials used] Hydration-expandable substance: lime-based expansive material (containing quicklime and anhydrous gypsum contained in cement mineral) [Product name: Expon Onoda (manufactured by Onoda)] Chemical starch: quaternary cation Starch (Nichiren Chemical Co., Ltd.) Surfactant: Naphthalene sulfonate formalin condensate (Kao Corporation)

[0027]

[Table 2]

Tables 1 and 2 show that the use of the cement admixture of the present invention can effectively suppress the temperature rise due to the heat of hydration of the cement and provide excellent strength.

Test Example 3 1) Test method 2700 g of low heat Portland cement, 300 expansive material
g, 6000 g of Toyoura silica sand and 1500 g of water, 2 parts by weight of a surfactant (60 g) and 100 parts by weight of a modified starch are added to a total of 100 parts by weight of cement and an expanding agent. 9g), knead and mixed, 3
A setting test was carried out in a constant temperature room at 0 ° C. in accordance with JIS A 6204 “Chemical admixture for concrete”, Appendix 1, “Method of testing setting time of concrete”. Table 3 shows the results.

2) Materials used Hydration-expandable substance: calcium-sulfoaluminate-based expanding material (containing 3CaO.3Al ₂ O ₃ .CaSO ₄ , anhydrous gypsum and CaO) [trade name: Denka CSA # 20 (Denki Kagaku Kogyo Co., Ltd.) Chemically modified starch: quaternary cationized starch, dextrin (both manufactured by Nisseki Chemical Co., Ltd.) Surfactant: polyalkylallyl sulfonate and reactive polymer [trade name: Mighty 2000WH (Kao Corporation)
Made))

[0031]

[Table 3]

From Table 3, it can be seen that when cationized starch is used as the cement admixture of the present invention, in particular, modified starch, mortar of excellent strength is obtained quickly without setting delay as compared with the case of using dextrin. Was done.

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Claims (5)

[Claims] 1. A modified starch selected from (A) an etherified starch and an esterified starch, and (B) an aromatic sulfonic acid and a salt thereof, a condensate of an aromatic sulfonic acid or a salt thereof,
A cement comprising a condensate of a triazine derivative, a lignin sulfonate and a derivative thereof, and one or more surfactants selected from a vinyl compound-unsaturated dicarboxylic acid copolymer and a derivative thereof. Admixture. 2. The cement admixture according to claim 1, wherein (A) the modified starch is an etherified starch. 3. A cement admixture containing the cement admixture according to claim 1 or 2 and (C) a hydration-expandable substance. 4. A cement composition comprising the cement admixture according to claim 1 or 2 or the cement admixture according to claim 3. 5. Component (A) is 0.03 to 10 parts by weight and component (B) is 0.01 to 100 parts by weight of cement.
The cement composition according to claim 4, wherein the content is from 5 to 5 parts by weight.