JP2003292357A - Powdery admixture for cement or concrete - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a powdery admixture for a cement or concrete high in stability, easy in handleability and excellent in performance as the admixture, and also to provide a method for production thereof. <P>SOLUTION: This powdery admixture is obtained by carrying an organic admixture on the powder of calcium silicate hydrate having a BET specific surface area of 30 m<SP>2</SP>/g or wider as a carrier. The method for producing the admixture comprises impregnating the calcium silicate hydrate powder with an organic admixture solution, drying, and then crushing the obtained solid material. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a powdery admixture for cement and concrete and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, organic admixtures to be mixed with cement or concrete are often marketed as an aqueous solution. Such a liquid organic admixture cannot be used as it is to prepare a premix product mixed with cement, sand, or the like, or a premix product mixed with blast furnace slag, fly ash, or the like.

Among the liquid organic admixtures, those whose active ingredient is a formalin condensate of naphthalene sulfonate, a formalin condensate of melamine sulfonate or a lignin sulfonate are obtained by directly drying the liquid admixture. It may be used as a powdery admixture as a stable powder.
In such a case, various premix products can be prepared by mixing the powdery admixture.

However, among the liquid admixtures, it is difficult to obtain a stable powder by directly drying a polycarboxylic acid type water reducing agent which has been widely used in the cement and concrete fields in recent years because of its particularly excellent water reducing property. Therefore, it is impossible to prepare a highly useful premix product.

A water-soluble polymer as a raw material of the polycarboxylic acid type water reducing agent is usually synthesized in a solution. Therefore, the water-soluble polymer is usually obtained in the form of an aqueous solution and has a very high affinity with water. Therefore, it is difficult to directly dry the polycarboxylic acid-based admixture using the water-soluble polymer as a raw material to remove the water content and to be powdered. Moreover, even if it can be directly dried and pulverized, it has a very high hygroscopicity, so it absorbs moisture in the air during storage and softens, or the solid surface becomes an adsorbate, and the performance as a water reducing agent It often causes problems in handling. Such characteristics become more remarkable as the fine powder having a large surface area is used.

As described above, there are various liquid organic admixtures other than polycarboxylic acid water-reducing agents which hinder the performance as an admixture and the handling only by directly drying and powdering. Even with such a liquid organic admixture, there is a demand for the development of a technique capable of forming a powdery admixture without impairing the performance and handleability of the admixture.

[0007]

DISCLOSURE OF THE INVENTION The present invention provides a powdery admixture for cement and concrete which has high stability, is easy to handle, and has excellent performance as an admixture, and a method for producing the same. The main purpose is that.

[0008]

The present inventor has conducted extensive studies in view of the problems of the prior art, and as a result, the calcium silicate hydrate powder is used as a carrier, and the calcium silicate hydrate powder is used as a carrier. The inventors have found that a material obtained by supporting an organic admixture on the above can achieve the above object, and have completed the present invention.

That is, the present invention relates to the following powdery admixture for cement and concrete and a method for producing the same.

1. Powder for cement and concrete, characterized in that a calcium silicate hydrate powder having a BET specific surface area of 30 m ² / g or more is used as a carrier, and the calcium silicate hydrate powder is loaded with an organic admixture. Admixture.

2. The powdery admixture for cement and concrete according to the above item 1, wherein the organic admixture is a polycarboxylic acid-based admixture.

3. Powder for cement and concrete, characterized in that calcium silicate hydrate powder having a BET specific surface area of 30 m ² / g or more is impregnated with an aqueous solution of an organic admixture and dried, and then the obtained solid material is crushed. Of manufacturing a state-of-the-art admixture.

4. A powdery admixture for cement and concrete, which is produced by the production method according to above item 3.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Cement and concrete powder
End shaped admixture for cement and concrete powder admixture of the present invention (hereinafter referred to as "the present invention powdered admixture".) Is, B
A calcium silicate hydrate powder having an ET specific surface area of 30 m ² / g or more is used as a carrier, and an organic admixture is carried on the calcium silicate hydrate powder.

[Calcium silicate hydrate powder] As the carrier calcium hydrate hydrate, it is necessary to use one having a BET specific surface area of 30 m ² / g or more,
Preferably, an organic admixture having a large BET specific surface area of 60 m ² / g or more is used. In the present specification, the specific surface area is the specific surface area determined by the BET method based on the adsorption amount of nitrogen gas.

As the calcium silicate hydrate powder, at least one powder selected from known synthetic calcium silicate hydrate and natural calcium silicate hydrate can be used.

As the synthetic calcium silicate hydrate, for example, zonotolite, tobermorite, foshagite, gyrolite, hirebrandite, rosenhanite obtained by hydrothermal reaction from a lime raw material and a silicic acid raw material,
Truscotite, lierite, calcio chondrodite, affilite, quasi-crystalline calcium silicate hydrate (C
SHn) and the like.

The calcium silicate hydrate powder may be primary particles (single crystals) of calcium silicate hydrate, or an aggregate (secondary particle) in which primary particles are three-dimensionally entangled. May be

[Organic Admixture] The type of the organic admixture in the present invention is not particularly limited. For example, in the production of concrete, known organic admixtures used by being mixed with various cements or concrete can be used.
Examples of such organic admixtures include AE agents, water reducing agents, high-performance water reducing agents, AE water reducing agents, high-performance AE water reducing agents,
A fluidizer, a thickener, a hardening accelerator, a setting retarder, a shrinkage reducing agent, a super retarder, a foaming agent, a foaming agent, an antifoaming agent, a waterproofing agent and the like.

As the AE agent, as an active ingredient, for example, fatty acid soap, alkylbenzene acid salt, higher alcohol sulfate ester salt, polyoxyethylene alkyl ether phosphate ester salt, polyoxyethylene alkyl ether, polyoxyethylene sorbitan fatty acid ester, The thing containing at least 1 type of natural resin acid salt etc. is mentioned.

As the water reducing agent, as an active ingredient, for example, at least one of lignin sulfonate, gluconate, alkylarisulfonate, naphthalene sulfonate formalin condensate, melamine sulfonate formalin condensate, etc. is contained. There are things.

As a high-performance water reducing agent, as an active ingredient,
For example, those containing at least one of naphthalene sulfonate formalin condensate, melamine sulfonate formalin condensate and the like can be mentioned.

Examples of the AE water reducing agent include those containing, as an active ingredient, at least one of lignin sulfonate, gluconate, alkylallyl sulfonate and the like.

As a high-performance AE water reducing agent, as an active ingredient, for example, an olefin maleic acid copolymer, (meth)
Such as copolymers of acrylic acid and (meth) acrylic acid ester, polycarboxylic acid compounds such as allyl ether maleate ester; modified lignin sulfonate, naphthalene sulfonic acid formalin condensate, melamine sulfonic acid formalin condensate, etc. The thing containing at least 1 type is mentioned.

Examples of the fluidizing agent include those containing, as an active ingredient, at least one of naphthalene sulfonic acid formalin condensate and melamine sulfonic acid formalin condensate.

As the thickener, as an active ingredient, for example, a cellulosic compound derivative such as cellulose ester,
Examples thereof include those containing at least one kind of polyacrylamide, polysaccharide polymer, water-soluble polysaccharide and the like.

Examples of the curing accelerator include those containing, as an active ingredient, triethanolamine and the like.

Examples of the setting retarder include those containing, as an active ingredient, at least one of lignin sulfonate, oxycarboxylate and the like.

Examples of the shrinkage reducing agent include those containing, as an active ingredient, at least one of alkylene oxide polymers, glycol ether compounds, lower alcohol alkylene oxide adducts such as methanol and ethanol.

Examples of the ultra-delaying agent include those containing at least one kind of oxycarboxylic acid salt, oxycarboxylic acid compound polyol-based organic polymer complex, etc. as an active ingredient.

Examples of the foaming agent include those containing, as an active ingredient, at least one of synthetic surfactants such as polyoxyethylene alkyl ether sulfate and resin soaps such as rosin soap and rosin maleate.

Examples of the foaming agent include those containing, as an active ingredient, a natural resin acid salt special surfactant and the like.

Examples of the antifoaming agent include those containing, as an active ingredient, at least one of lower alcohols such as methanol and ethanol; silicone compounds such as silicone resins.

Examples of the waterproofing agent include those containing at least one of higher fatty acid, organic emulsion, organic polymer dispersion, organic water-soluble polymer and the like as an active ingredient.

However, the organic admixture in the present invention may be an admixture containing an organic compound as an active ingredient, and is not necessarily limited to the admixtures exemplified above.

In the present invention, the organic admixture may be used alone or in admixture of two or more.

[Characteristics of the powdery admixture of the present invention] In the powdery admixture of the present invention, the amount of the organic admixture supported on the calcium silicate hydrate powder having a BET specific surface area of 30 m ² / g or more is not particularly limited. It can be set as needed. Usually 100 hydrated calcium silicate powder
With respect to parts by weight, the organic admixture, as the amount of active ingredient,
About 0.01 to 300 parts by weight, preferably 50 to 150
It may be carried in an amount of about 100 parts by weight, more preferably about 70 to 100 parts by weight. In addition, two or more kinds of organic admixtures may be mixed and supported.

The particle size of the powder of the powdery admixture of the present invention is not particularly limited and can be appropriately set as necessary, but it is usually preferable to set it to about the primary particles of calcium silicate hydrate. . That is, it is usually about 1 to 200 μm, preferably about 2 to 100 μm, more preferably 2 to 50 μm.
It is about μm. The particle diameter is a value measured by a laser diffraction type particle size distribution meter.

In the powdery admixture of the present invention, various organic admixtures can be used as the powdery admixture. As a result, an organic admixture, which could not be made into a stable powder by direct drying, such as a polycarboxylic acid admixture, can also be used as a powder admixture. Moreover, the powdery admixture of the present invention has excellent resistance to moisture absorption, high stability during storage, easy handling, and excellent admixture performance.

By using the powdery admixture of the present invention, premixed products containing various organic admixtures can be prepared. The powdery admixture of the present invention can be used, for example, to prepare a premix product mixed with cement, sand, or the like, or a premix product mixed with blast furnace slag, fly ash, or the like. Being able to prepare various premix products can further contribute to the improvement of concrete production efficiency.

Further, the powdery admixture of the present invention, when mixed with a liquid phase such as water, can quickly elute the supported active ingredient and exert the effect as an admixture. In particular, pH 10-13
It excels in the elution of the active ingredient in the liquid phase in a moderate alkaline atmosphere. Therefore, in the production of concrete, the supported active ingredient can be sufficiently eluted in the liquid phase of the cement composition and the concrete composition.

Moreover, since the calcium silicate hydrate remaining after the active ingredient is eluted is a kind of hydration product of the cement composition, it does not become an impurity in the hardened product of the cement composition.

Method for Producing Powdery Admixture of the Present Invention The method for producing the powdery admixture of the present invention is not particularly limited, and an organic admixture is added to a calcium silicate hydrate powder having a BET specific surface area of 30 m ² / g or more as a carrier. Any method may be used as long as it is a production method capable of obtaining a powdery admixture in which the agent is supported.

As a production method, for example, a calcium silicate hydrate powder having a BET specific surface area of 30 m ² / g or more is impregnated with an aqueous solution of an organic admixture, dried, and then the obtained solid matter is crushed. Is preferred. The method will be described below.

BET specific surface area 30 used in this method
As the calcium silicate hydrate powder of m ² / g or more,
The ones described above can be used. Also, as the organic admixture, those described above can be used.

The organic admixture aqueous solution can be prepared as it is as long as it is an organic admixture commercially available in the form of an aqueous solution, or by mixing with an appropriate amount of water. Alternatively, an organic admixture aqueous solution may be prepared by dissolving a commercially available organic admixture in a powder state in water.

The amount of the active ingredient contained in the organic admixture aqueous solution is not particularly limited and can be appropriately set as necessary. The amount of the active ingredient contained in the organic admixture aqueous solution is usually about 0.1 to 100%, preferably about 1 to 100%, more preferably the amount of the active ingredient contained in the saturated aqueous solution of the organic admixture. Is about 10 to 100%.
In addition, you may use the organic admixture aqueous solution containing 2 or more types of active ingredients as needed.

The method of impregnating the calcium silicate hydrate powder with the organic admixture aqueous solution is not particularly limited. Usually, it can be impregnated by a method of immersing the calcium silicate hydrate powder in the organic admixture aqueous solution, a method of spraying the calcium silicate hydrate powder with the organic admixture aqueous solution, and the like. In addition, a method of adding an organic admixture to a slurry of calcium silicate hydrate and mixing, a method of mixing an organic admixture with a raw material of calcium silicate hydrate during production of calcium silicate hydrate, etc. Can also be impregnated with.

After impregnating the organic admixture aqueous solution, the calcium silicate hydrate is dried. The drying method is not particularly limited, and either natural drying or heat drying may be used. In the case of drying by heating, it is usually about 40 to 150 ° C., preferably about 70 to 120 ° C. for about 1 to 48 hours, preferably 2
It may be carried out for about 24 hours.

After drying, the obtained solid material is crushed to obtain the powdery admixture of the present invention. The crushing method is not particularly limited, and it is preferable to use a known crusher such as a pin mill, a cage mill, a disk mill or the like, and preferably crush the particles so that the powder has the predetermined size.

[0051]

INDUSTRIAL APPLICABILITY The powdery admixture of the present invention is a stable powdery admixture even if it is an organic admixture (for example, a polycarboxylic acid admixture) which does not become a stable powder having excellent moisture absorption resistance when directly dried. It can be an admixture. Further, a powdery admixture that carries two or more kinds of organic admixtures and simultaneously exhibits the effects of a plurality of organic admixtures can be used.

The powdery admixture of the present invention has a pH of 10 to 1 in particular.
Excellent elution of the active ingredient in the liquid phase in an alkaline atmosphere of about 3. Therefore, in the production of concrete, the active ingredient can be sufficiently eluted into the liquid phase of the cement composition and the concrete composition, and the effect as an admixture is excellent.

With the powdery admixture of the present invention, various premixed products containing various organic admixtures can be prepared. For example, a premix product mixed with cement, sand or the like can be prepared, or a premix product mixed with blast furnace slag, fly ash or the like can be prepared. By being able to prepare various premix products, it is possible to further improve the production efficiency of concrete.

[0054]

EXAMPLES The present invention will be described more specifically with reference to Examples and Comparative Examples below. However, the present invention is not limited to these descriptions.

Example 1 BET was added with 80 g of an aqueous solution containing 30% by weight of a polycarboxylic acid-based high-performance AE water reducing agent (trade name "Tupole HP11R" manufactured by Takemoto Yushi Co., Ltd.) as an active ingredient (24 g of the active ingredient).
After impregnating with 10 g of calcium silicate hydrate powder having a specific surface area of 100 m ² / g, it was dried at 100 ° C. for 10 hours to obtain a solid content of 34 g. Next, the solid content was crushed to produce a powdery admixture. The average particle diameter of the powdery admixture is 35 μm
Met.

Comparative Example 1 80 g of an aqueous solution containing 30% by weight of a polycarboxylic acid type high-performance AE water reducing agent (trade name “Chupol HP11R” manufactured by Takemoto Yushi Co., Ltd.) as an active ingredient (effective ingredient amount: 24 g) was used.
Directly dried at ℃ for 24 hours, crush the obtained solid content,
A powdered admixture was produced. The powdery admixture had an average particle diameter of 35 μm.

Comparative Example 2 80 g of an aqueous solution containing 30% by weight of a polycarboxylic acid type high-performance AE water reducing agent (trade name "Chupol HP11R" manufactured by Takemoto Yushi Co., Ltd.) as an active ingredient (24 g of the active ingredient) was used as a liquid admixture. did.

[Comparison of Example 1 and Comparative Example 1] Example 1
The properties of the powdery admixture obtained in Comparative Example 1 were observed over time. The results of changes over time are shown in Table 1 below.

[0059]

[Table 1] As is clear from Table 1, the powdery admixture of the present invention in which the active ingredient is supported on the calcium silicate hydrate powder is produced 72
Even after hours, it remained in a free-flowing powder state. On the other hand, Comparative Example 1 obtained by directly drying the liquid admixture
The powdery admixture of No. 3 is a powder having a sticky surface immediately after its production, and the powders adhere to each other 24 hours after the production.
After 2 hours, it became candy-like and could not be maintained in a powder state for a long time.

[Effect of Powdery Admixture of Example 1 as Admixture] In order to confirm the effect of the powdery admixture of Example 1 as an admixture, the liquid admixture of Comparative Example 2 (conventional product). And the effect was compared.

First, the powdery admixture of Example 1 and the liquid admixture of Comparative Example 2 were added so that the active ingredient was 0.2 parts by weight per 100 parts by weight of ordinary Portland cement, and then the cement was added. 30 parts water for 100 parts by weight
Cement paste was prepared by adding parts by weight and kneading.

Next, the change with time of the viscosity of the cement paste was examined. Immediately after, 30 minutes, 60 minutes, and 90 minutes after the production of the cement paste, the viscosities were measured using a double cylinder type rotational viscometer (trade name “RS-150” manufactured by Haake). Viscosity measurements have shear rates of 200 S ^-1 , 20
Apparent viscosity of cement paste at ℃ (Unit: Pa
・ S). The measurement results are shown in Table 2 below.

[0063]

[Table 2] As is clear from Table 2, polycarboxylic acid-based high performance AE
When the water reducing agent was not added, the paste viscosity increased immediately after the production, and after 90 minutes, the paste was cured and the viscosity could not be measured. On the other hand, with the admixtures of Example 1 and Comparative Example 2, the viscosity increase of the paste was effectively suppressed. From Table 2, it can be seen that the powdery admixture of the present invention has sufficient admixture performance.

Examples 2 to 12 The effect of the powdery admixture of the present invention as an admixture was confirmed from the viewpoint of the amount of the active ingredient carried therein to be eluted.

First, 11 kinds of raw material admixtures shown in Table 3 below were added to 100 g of calcium silicate hydrate powder having a BET specific surface area of 100 m ² / g, and the ratio of the active ingredient was 50% by weight of the powdered admixture. % So that the powdery admixture was produced.

In Examples 2 to 11, the raw material admixture of Example 9 (on the market) was a powder admixture, so a 10% aqueous solution was prepared, and then a predetermined amount of calcium silicate hydrate powder was prepared. It was carried by.

[0067]

[Table 3] Next, 10 g of each of the obtained 11 kinds of powdery admixtures was weighed (10 g of powdery admixture carries 5 g of the active ingredient), and distilled water (pH = 7) and 100 ml of sodium hydroxide aqueous solution were respectively weighed. Dispersed in (pH = 12),
After stirring for 10 minutes, suction filtration was performed, and the TOC amount (total organic carbon amount) of each filtrate was measured. TOC amount is measured by TO
The measurement was performed using a C measuring device (trade name "TOC-650" manufactured by Toray Engineering Co., Ltd.).

Each TOC amount measurement value was compared with the TOC amount (theoretical TOC amount) of the raw material admixture solution containing 5 g of the active ingredient to calculate the elution ratio (%) of the active ingredient from each powdery admixture. . The active ingredient elution ratio (%) from each powdery admixture is shown in Table 4 below.

[0069]

[Table 4] As is clear from Table 4, the powdery admixture of the present invention is excellent in elution of the active ingredient in a solution (particularly, alkaline solution: pH = 12). That is, the powdery admixture of the present invention can exert the effect as an admixture by sufficiently eluting the active ingredient in the liquid phase of the cement composition and the concrete composition in the production of concrete.

Continued front page    (72) Inventor Kensuke Kanai             28 Sumitomo Osaka, 6-6 Rokubancho, Chiyoda-ku, Tokyo             Inside Cement Co., Ltd. (72) Inventor Koichi Matsumoto             28 Sumitomo Osaka, 6-6 Rokubancho, Chiyoda-ku, Tokyo             Inside Cement Co., Ltd.

Claims (4)

[Claims] 1. A cement characterized in that a calcium silicate hydrate powder having a BET specific surface area of 30 m ² / g or more is used as a carrier, and the calcium silicate hydrate powder carries an organic admixture. And a powdery admixture for concrete. 2. The powdery admixture for cement and concrete according to claim 1, wherein the organic admixture is a polycarboxylic acid admixture. 3. A cement characterized in that calcium silicate hydrate powder having a BET specific surface area of 30 m ² / g or more is impregnated with an aqueous solution of an organic admixture, dried, and then the obtained solid substance is crushed. For manufacturing powdered admixtures for concrete and concrete. 4. A powdery admixture for cement and concrete produced by the production method according to claim 3.