JPH0570199A - Cement admixture for promoting centrifugal compaction - Google Patents

Abstract

(57) [Abstract] [Objective] The present invention uses a centrifugal compaction molding method to develop a cement-containing substance (mortar, concrete, asbestos-cement mixture, etc.) that has not yet solidified, to develop centrifugal compaction properties at an early stage. Provide an admixture used for the purpose of finishing a cement product having predetermined performance. [Composition] A cement admixture for promoting centrifugal compaction, which comprises a high-performance water reducing agent and polyalkylene oxide. [Effect] By using the cement admixture for promoting centrifugal compaction according to the present invention, the resistance of the centrifugally molded product to impact is increased, and it becomes possible to remarkably improve the compaction property during centrifugal molding. Further, according to the present invention, the escape rate of slag is increased, and the water content in the concrete is removed. As a result, the water / cement ratio is lowered, and the centrifugal force exerts an excellent effect in terms of compressive strength. Is possible.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention uses a centrifugal compaction molding method for a cement-containing substance (mortar, concrete, asbestos cement mixture, etc.) that does not solidify yet to develop centrifugal compaction properties at an early stage, The present invention relates to an admixture used for the purpose of finishing a cement product having the above-mentioned performance.

[0002]

2. Description of the Related Art A centrifugal compaction molding method is a method for producing a secondary cement product by utilizing centrifugal force generated by a rotational force, and is a method for producing a cement secondary product. This is an excellent molding method that simultaneously squeezes the water content of the material and simultaneously pressurizes it by several tens of times the acceleration of gravity to compress the concrete and finish a product with a solid structure. In order to effectively carry out the centrifugal compaction molding method, high molecular weight polyalkylene oxide (average molecular weight 10
1 to 6 million) to impart dispersibility and wettability to these compositions, reduce frictional resistance, accelerate dehydration under centrifugal force,
A method for producing a secondary cement product is known (Japanese Patent Publication No.
52-42815). However, even if a polyalkylene oxide having an average molecular weight of 100,000 to 6,000,000 is used, it is not always sufficient to exert the centrifugal compaction effect in a short time, and it also exhibits sufficient performance in compressive strength. Not a thing. When polyethylene glycol having an average molecular weight of 4,000 to 80,000 is used for the same purpose (Japanese Patent Publication No.
63-1259) also improves the dehydration promoting action under centrifugal force, but does not yet have sufficient performance in compressive strength.

[0003]

With the above problems in mind, the present inventors have obtained a centrifugal compaction-promoting admixture capable of producing concrete exhibiting a large compressive strength in a short time and a large long-term compressive strength. As a result of intensive studies, it was found that a cement admixture containing a high-performance water-reducing agent and a polyalkylene oxide has excellent water-reducing property, excellent dehydration accelerating property, and can express sufficient short-term compressive strength. It has been completed. That is, the present invention provides a cement admixture for promoting centrifugal compaction, which comprises a high-performance water reducing agent and a polyalkylene oxide.

The high-performance water reducing agent is an admixture whose main purpose is to disperse cement, and has an excellent water reducing effect together with dispersibility.

Examples of the high-performance water-reducing agent used in the present invention include formaldehyde condensates or cocondensates of alkylallyl sulfonic acids or metal salts thereof, and high condensates of triazine derivatives or metal salts thereof. As the formaldehyde condensate or co-condensate of alkylallyl sulfonic acid, a naphthalene sulfonic acid formaldehyde condensate, a phenol or derivative thereof which is addition-condensed in combination with an amino-based polymerization terminator, melamine or a derivative thereof and a group consisting of urea Formaldehyde co-condensates of one or more compounds selected are preferred.

As the amino-based polymerization terminator, one or more compounds selected from the group of compounds represented by the following general formulas (A), (B), (C) and (D) are suitable. General formula (A)

[0007]

[Chemical 1]

(Where X ₁ is hydrogen, a linear or branched alkyl group having 1 to 3 carbon atoms, a carboxyl group or an alkali metal salt thereof, a sulfone group or an alkali metal salt thereof,
It is selected from the group consisting of a hydroxyl group and a methoxy group, and Y ₁ is selected from the group consisting of a carboxyl group or an alkali metal salt thereof and a sulfone group or an alkali metal salt thereof. ) General formula (B)

[0009]

[Chemical 2]

(Where X ₂ is hydrogen, a linear or branched alkyl group having 1 to 3 carbon atoms, a carboxyl group or an alkali metal salt thereof, a sulfone group or an alkali metal salt thereof,
Y ₂ is selected from the group consisting of a carboxyl group or an alkali metal salt thereof and a sulfone group or an alkali metal salt thereof. ) General formula (C)

[0011]

[Chemical 3]

(Wherein Z is selected from hydrogen, a linear or branched alkyl group having 1 to 3 carbon atoms, and --CH ₂ SO ₃ M, and M means hydrogen or an alkali metal). D) H ₂ NSO ₃ M (D) (where M means hydrogen or an alkali metal) Further, examples of the phenol or its derivative include compounds represented by the following general formula (E): melamine or As the derivative thereof, a compound represented by the following formula (F) is suitable. General formula (E)

[0013]

[Chemical 4]

(Where X ₃ is hydrogen, a linear or branched alkyl group having 1 to 3 carbon atoms, a carboxyl group or an alkali metal salt thereof, a sulfone group or an alkali metal salt thereof,
It is selected from the group consisting of a hydroxyl group and a methoxy group. ) General formula (F)

[0015]

[Chemical 5]

(Here, X ₄ is hydrogen, hydroxyl group, —CH ₂ SO ₃
Selected from M, M means hydrogen or an alkali metal.
X ₅ is selected from hydrogen, hydroxyl group and —CH ₂ SO ₃ M, and M means hydrogen or an alkali metal. X ₆ is hydrogen, hydroxyl group, -CH ₂ S
It is selected from O ₃ M and M means hydrogen or an alkali metal. ) As a highly condensed product of the triazine derivative, a melaminesulfonic acid formaldehyde condensate is suitable. The superplasticizer used in the present invention has an average molecular weight of 1,000 to 10
A range of 0,000 is preferred. If the average molecular weight is less than 1,000, sufficient dispersibility is not exhibited, while if it exceeds 100,000, the cohesiveness becomes remarkable, and it is not suitable as a water reducing agent.

As the polyalkylene oxide of the present invention, water-soluble polymers such as polyethylene glycol and polyethylene oxide are preferable. The average molecular weight of the polyalkylene oxide of the present invention is 1,000 to 200,
The range of 000 is preferable, and the range of 4,000 to 80,000 is more preferable. As shown in Examples and Comparative Examples described later,
The reason is not clear, but if the average molecular weight is less than 1,000 or more than 200,000, the performance as a cement admixture for promoting centrifugal compaction is inferior, which is not preferable.
The addition amount of the cement admixture for promoting centrifugal compaction of the present invention is usually 0.0 in terms of effective components in terms of effective cement.
The range of 01 to 4.0% by weight is preferable, 0.001 to 2.0% by weight
Is more preferable. If it is less than 0.001% by weight, the effect of promoting dehydration is poor, while if it exceeds 4.0% by weight, the compressive strength is lowered for a short period of time, which is not preferable.

Since the final compressive strength is large when the admixture according to the present invention is used, the amount of cement used can be reduced when the compressive strength above a certain value is not required. The diameter can be made smaller, and if the diameter is made smaller and the weight is made lighter, the carrying work becomes easier, and the driving work becomes much easier.

[0019]

EXAMPLES The present invention will be described below with reference to production examples and examples, but the present invention is not limited to these production examples and examples. Production Example 1 Sodium phenolsulfonate in a reaction vessel equipped with a stirrer
1.0 mol, urea 0.8 mol and sodium sulfamate
The solution is adjusted to pH 6.2 and the solid concentration is adjusted to 35% by weight by adding 0.9 mol and adding 0.1 N sulfuric acid and water. Next, the adjusted solution is heated to 90 ° C., 37% formalin (3.2 mol as formaldehyde) is added with stirring, and the reaction mixture is stirred under reflux for 8 hours. Then, the mixture is cooled to room temperature, adjusted to pH 9 by adding a 40% aqueous sodium hydroxide solution, and adjusted to a solid concentration of 25% by adding water to obtain a formaldehyde cocondensate. Table 1 below shows the contents of the condensate produced in the same manner as in this production example except that the raw materials (molar ratio) were changed as shown in Table 1.

[0020]

[Table 1]

Production Example 4 Phenol (1.0 mol) and melamine were placed in a reaction vessel equipped with a stirrer.
0.6 mol and 1.5 mol of sulfanilic acid are charged and the pH of this solution is adjusted to 8.6 by adding 40% aqueous sodium hydroxide solution and water, and the solid content concentration is adjusted to 35% by weight. Then, the adjusted solution is heated to 95 ° C., 37% formalin (3.1 mol as formaldehyde) is added with stirring, and the reaction mixture is stirred under reflux for 7 hours. Then, the mixture is cooled to room temperature, adjusted to pH 9 by adding a 40% aqueous sodium hydroxide solution, and adjusted to a solid concentration of 25% by adding water to obtain a formaldehyde cocondensate. Table 2 below shows the contents of the condensate produced in the same manner as in this production example except that the raw materials (molar ratio) were changed as shown in Table 2.

[0022]

[Table 2]

Production Example 7 A reaction vessel equipped with a stirrer was charged with 0.6 mol of p-hydroxybenzoic acid, 0.7 mol of N-methylsulfonated melamine and 1.5 mol of naphthoic acid, and 40% aqueous sodium hydroxide solution and water were added. The pH of this solution is adjusted to 10.5, and the solid content concentration is adjusted to 35% by weight. Next, the adjusted solution is heated to reflux temperature, 37% formalin (2.6 mol of formaldehyde) is added with stirring, and the reaction mixture is stirred under reflux for 10 hours. Then, the mixture is cooled to room temperature and adjusted to pH 9 by adding 0.1N sulfuric acid, and water is added to adjust the solid content concentration to 25% to obtain a formaldehyde cocondensate. Table 3 below shows the contents of the condensate produced in the same manner as in this Production Example except that the raw materials (molar ratio) were changed as shown in Table 3.

[0024]

[Table 3]

Production Example 10 0.3 mol of phenolsulfonic acid in a reaction vessel equipped with a stirrer,
Catechol 1.2 mol and N-methylsulfonated urea 1.3
The solution is brought to pH 5.2 by adding 0.1 mol of sulfuric acid and water, and the solid concentration is set to 35% by weight.
Adjust to. Next, the prepared solution is heated to 95 ° C.,
37% formalin (as formaldehyde while stirring
4.2 mol) and the reaction mixture is stirred under reflux for 12 hours. Then, the mixture is cooled to room temperature, adjusted to pH 9 by adding a 40% aqueous sodium hydroxide solution, and adjusted to a solid concentration of 25% by adding water to obtain a formaldehyde cocondensate. Table 4 below shows the contents of the condensate produced in the same manner as in this Production Example except that the raw materials (molar ratio) were changed as shown in Table 4.

[0026]

[Table 4]

The concrete mix and materials used in Examples and Comparative Examples are as follows.・ Maximum size of coarse aggregate 15mm ・ Water / cement ratio (W / C) 38.6% ・ Fine tubing ratio (S / A) 40% ・ Unit cement amount (C) 440Kg / m ³ cement (C): ordinary Portland cement (Specific gravity 3.
17) Thin tube material (S): Sand from Kinokawa (specific gravity 2.58, FM2.91) Coarse aggregate (G): Crushed stone from Takarazuka (specific gravity 2.61, FM6.98) Aggregate (A): (S) + (G) Water (W) ・Compactability measurement A concrete specimen with a diameter of 300, a height of 300, and a thickness of 45 (unit: m / m) was used as a centrifugal force molding condition at a low speed (centrifugal force 3.1 G). / 3 minutes, G is gravitational acceleration 9.8m ² /
Second), and then molded at a medium speed (centrifugal force 12.6 G / 2 minutes), and a drop test was performed on this test piece. In addition, the same centrifugal force test specimen was used as a centrifugal force molding condition at low speed (centrifugal force 3.1 G / 3
Min), then medium speed (centrifugal force 12.6 G / 2 min), and higher speed (centrifugal force 35 G / 2 min), and a drop test was conducted on this test piece.

The drop test in the examples is a test apparatus having a mechanism in which a concrete compact is mechanically raised to a desired height, and then rapidly dropped, and collided with a table on which a sample placed in an initial position is placed ( A concrete molded body compacted by each centrifugal force is applied with a drop motion at a rate of 25m / m with a mold frame once every two or three seconds. The compaction property was evaluated by the number of drop motions until the concrete centrifugal force forming body inside deformed and fractured. Furthermore, the both ends of the form filled with concrete were sealed, and the work was done so that the slag did not escape to the outside of the system, and this form was used as a centrifugal force forming condition at a low speed (centrifugal force 3.1 G / 3
Min), then medium speed (centrifugal force 12.6 G / 2 min), and further high speed (centrifugal force 35 G / 2 min) to stop, and the ratio of the sloppy to the prepared concrete was calculated. The test results of the performance evaluation are shown in Table 5 and Table 6.

[0029]

[Table 5]

* PAO: Polyalkylene oxide PEG: Polyethylene glycol PEO: Polyethylene oxide ** Content of admixture:% by weight of cement, solid content of admixture A: Naphthalenesulfonic acid formaldehyde condensate product name Mighty 150, Kao Co., Ltd. B: Melamine sulfonic acid formaldehyde condensate Product name Melment, Showa Denko KK

[0031]

[Table 6]

*% By weight of cement, solid content of admixture ** PEG: polyethylene glycol

[0033]

EFFECT OF THE INVENTION By using the cement admixture for promoting centrifugal compaction according to the present invention, the resistance of the centrifugally molded product to impact is increased, and the compaction property at the time of centrifugal force molding can be remarkably improved. .. Further, according to the present invention, the escape rate of slag is increased, and the water content in the concrete is removed. As a result, the water / cement ratio is lowered, and the centrifugal force exerts an excellent effect in terms of compressive strength. Is possible.

Claims (3)

[Claims] 1. A cement admixture for promoting centrifugal compaction, which comprises a high-performance water reducing agent and a polyalkylene oxide. 2. The high-performance water reducing agent is one or more compounds selected from formaldehyde condensates or cocondensates of alkylallyl sulfonic acids or metal salts thereof, melamine sulfonic acid formaldehyde condensates or metal salts thereof. Cement dispersant for promoting centrifugal compaction according to 1. 3. The polyalkylene oxide has an average molecular weight.
The cement admixture for promoting centrifugal compaction according to claim 1, which is 4,000 to 80,000 polyethylene glycol.