JP2008239355A - Manufacturing method of admixture for cement-concrete and admixture for cement-concrete - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of admixture for cement-concrete in which the fine powder made globular is obtained in stable quality at a low cost. <P>SOLUTION: The manufacturing method of admixture for cement-concrete includes a process of preparing an admixture of the fine powder made globular by subjecting slurry-like inorganic raw material in which a dispersant is added to counter collision at a high pressure. Therethrough, protrusions on particle surface of the fine powder are shaved by adjusting the solid component concentration and the fine powder having substantially globular shape can be obtained in the stable quality without being aggregated. Further, the grinding during which the protrusions on the particle surface is shaved is performed, therefore, large amounts of the fine powder of superfine particles having a particle size of 0.5 μm or less can be obtained, the micro filler effect can be brought about and, thereby, desired higher strength and higher fluidity of various kinds of material such as high-strength concrete, high-strength non-shrinkage grout material and self-leveling material can be provided. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for producing a cement / concrete admixture that is used in high strength concrete, non-shrink grout material, self-leveling material, etc. used in the field of construction and civil engineering, and contributes to fluidity and strength development, and cement / concrete. It relates to admixtures.

Conventionally, silica fume (amorphous SiO ₂ ) is widely known as an admixture of inorganic materials used for high-strength concrete, non-shrink grout materials, self-leveling materials and the like. Silica fume is expensive and industrial waste, and therefore has a demerit that quality is not stable or high quality is difficult to obtain. For this reason, in recent years, development of alternative materials for silica fume and development of inorganic admixtures with stable quality has been promoted.

For example, Patent Document 1 describes that silica fume, limestone, silica stone, blast furnace slag, and the like are obtained by pulverizing with a ball mill or a solid roller mill as an inorganic admixture used for producing high-strength concrete. Further, Patent Document 2 describes that a predetermined particle size is obtained by combining classifiers in order to obtain ultrafine particles of coal or limestone by a solid roller mill. Furthermore, Patent Document 3 discloses a production method for obtaining spherical fine particles by a synthesis method in which a CO ₂ -containing gas is reacted with slaked lime slurry.
In addition, a method of obtaining pulverized ultrafine particles by wet pulverization of limestone using balls or beads as a medium is also known, and an alkali salt of polyacrylic acid (Na, K) is usually used as a dispersant. .

JP-A-6-199549 JP-A-10-28889 Japanese Patent Laid-Open No. 7-33433

The following problems remain in the conventional technology.
That is, the techniques described in Patent Documents 1 and 2 are methods for obtaining a predetermined particle size by combining a dry pulverizer such as a roller mill or a ball mill and a classifier, but the particle size is in the order of several microns to submicron order. In order to obtain a finely pulverized product, it is necessary to increase the classification efficiency, and the yield is poor, which is not preferable in terms of cost. In addition, these technologies perform pulverization by compressing and shearing the object to be pulverized by the drop impact or rotational motion of a ball or roller, so that the particle shape is large and the particle shape does not become a spherical shape suitable for an admixture. .
Further, in the technique described in Patent Document 3, although to obtain spherical particles by reacting CO ₂ containing gas into slaked lime slurry, instead of grinding the limestone, it is necessary to add such phosphates and acrylate When used as an admixture, it has the disadvantage of adversely affecting the fluidity and strength development of concrete. In addition, the spherical fine particles produced by this technique are not suitable as admixtures for concrete because the production method is complicated, the product is expensive, the particle surface is rough, and the fluidity is poor.
Furthermore, in the method of wet grinding using balls or beads as a medium to obtain ultrafine pulverized material, the ultrafine particle pulverized material having a desired average particle diameter can be obtained by observation with an electron microscope, but primary particles are aggregated. When used as a material, there is a problem that the performance of the original particle size cannot be obtained. In addition, the ultrafine particle pulverized product produced by this technique does not have a spherical particle shape.

  The present invention has been made in view of the above-described problems, and provides a method for producing an admixture for cement and concrete and a cement and concrete admixture that can obtain a spheroidized fine powder with stable quality and low cost. The purpose is to do.

The present invention employs the following configuration in order to solve the above problems. That is, the method for producing a cement / concrete admixture according to the present invention includes a step of producing a spherical fine powder admixture by causing a slurry-like inorganic raw material to which a dispersant is added to collide with each other at high pressure. And
In this method for producing an admixture for cement and concrete, a slurry-like inorganic raw material to which a dispersant is added is pulverized by an opposing collision wet pulverization method in which an opposing collision is performed at a high pressure. The convex portions on the surface of the particles can be shaved to obtain a substantially spherical particle shape with stable quality and without agglomeration. In addition, since the pulverization is performed to remove the convex portions on the particle surface, many fine powders of ultrafine particles having a particle diameter of 0.5 μm or less are obtained, and various desired materials (high-strength concrete, High strength non-shrink grout material, self-leveling material, etc.) and high fluidity can be realized. Furthermore, the obtained fine powder can be used as it is as an admixture of the above-mentioned various materials in a slurry state, and can also be used as a powder mixed with other additives by drying with an air dryer or the like. it can. Further, after removing water by centrifugal dehydration or the like, it can be used as a mixed cement by pulverizing simultaneously with clinker and gypsum.

  The method for producing an admixture for cement and concrete according to the present invention is characterized in that the solid content concentration of the inorganic raw material in a slurry state is set within a range of 10% to 50%. That is, in this method for producing a cement / concrete admixture, a fine powder having an average particle size of 2 μm or less can be obtained by setting the solid content concentration of the slurry-like inorganic raw material within a range of 10% to 50%. it can. In addition, the fine powder spheroidized with an average particle diameter of 2 μm or less is excellent in fluidity and strength development and is suitable as an admixture for high-strength concrete.

  Furthermore, the method for producing an admixture for cement and concrete according to the present invention is characterized in that a polycarboxylic acid-based high-performance water reducing agent or a polycarboxylic acid-based high-performance AE water reducing agent is used as the dispersant. That is, in this method for producing an admixture for cement / concrete, a polycarboxylic acid-based high-performance water reducing agent or a polycarboxylic acid-based high-performance AE water reducing agent is used, so that the fine powder after pulverization can be performed without damaging the dispersion effect of the fine powder. Since the above water reducing agent is adsorbed to the powder, the amount of water reducing agent added can be reduced as an admixture used for high strength concrete, high strength non-shrink grout material, self-leveling material and the like, and the economic effect is high.

In the method for producing an admixture for cement and concrete according to the present invention, the inorganic raw material of limestone or silica is made into a fine powder spheroidized to an average particle size of 2 μm or less and a circularity of 0.90 or more by the opposing collision. It is characterized by that.
That is, in this method for producing an admixture for cement / concrete, limestone or silica stone inorganic raw material is spheroidized into a high degree of circularity having an average particle size of 2 μm or less and a circularity of 0.90 or more by a counter collision wet pulverization method. Since it is a powder, it is possible to obtain an admixture with high fluidity and high strength development as ultra-high-strength concrete or high-strength concrete as a substantially spherical fine limestone fine powder or silica fine powder. Here, the circularity is defined as (circumference of circle equal to projected area of particle) / (contour length of projected particle).

  Moreover, the manufacturing method of the admixture for cement / concrete of the present invention may use waste slurry containing fine powder generated when crushing limestone and collecting limestone as the slurry-like inorganic raw material.

  In addition, the cement / concrete admixture of the present invention is produced by the above-described method for producing a cement / concrete admixture of the present invention. That is, this cement / concrete admixture is produced by the above-described method for producing a cement / concrete admixture according to the present invention, and has an average particle size of several microns to submicron order and a high degree of circularity. Since it is a powder, when it is used as an admixture in various materials such as high-strength concrete, high-strength non-shrink grout material, and self-leveling material, high strength and high fluidity can be realized.

The present invention has the following effects.
That is, according to the method for producing an admixture for cement / concrete according to the present invention and the admixture for cement / concrete, a slurry-like inorganic raw material to which a dispersant has been added is opposed to each other at high pressure to obtain a fine powder. Spherical particle shape can be obtained at low cost without stable quality and agglomeration, and an admixture that realizes high fluidity and high strength in high strength concrete, high strength non-shrink grout material, self-leveling material, etc. Obtainable.

  Hereinafter, an embodiment of a method for producing an admixture for cement and concrete and an admixture for cement and concrete according to the present invention will be described with reference to FIGS. 1 and 2.

The admixture for cement / concrete of this embodiment is used as an admixture for various cement materials such as high-strength concrete, high-strength non-shrink grout material, and self-leveling material. For example, for high-strength concrete, it is preferable to add to medium-heated Portland cement or low-heat Portland cement containing a large amount of C ₂ S (2CaO · SiO ₂ ). Further, it is preferable to add to the early-strength Portland cement in the non-shrink grout material and to add to the ordinary or early-strength Portland cement in the self-leveling material.

  The method for producing the cement / concrete admixture includes, for example, a dry pulverization process of an inorganic raw material of limestone or silica, a process of making the pulverized inorganic raw material into an aqueous slurry and adding a dispersant, and a slurry-like inorganic material. And a step of producing a fine powdered admixture obtained by causing the raw materials to collide with each other at high pressure (a collision-type crushing step). In addition, as the slurry-like inorganic raw material, waste slurry containing a large amount of fine powder generated when crushing limestone and collecting coarse aggregate for concrete or limestone for producing quicklime can be used.

  In the dry pulverization, for example, when limestone is used, the limestone is dry pulverized with a roller mill and then classified to obtain, for example, a limestone pulverized raw material having an average particle diameter of 18.6 μm. In addition, when using silica stone, the silica stone is dry-ground by a ball mill and then classified to obtain a silica stone raw material having an average particle size of 8.5 μm, for example.

Limestone is a sedimentary rock in which 50% or more of its constituent minerals are calcite or aragonite (CaCO ₃ ) and dolomite (CaMg (CO ₃ ) ₂ ), and calcite or aragonite is much more rock than dolomite. The limestone of the present invention uses calcite or aragonite from 80% to 100%. Limestone is in the process of formation, and there are fine crystalline and coarse crystalline ones, both of which can be used. In addition, shell components such as oysters are also aragonite, and can be used in the same manner as limestone.

On the other hand, the quartzite is a mineral or rock mainly composed of quartz, and examples thereof include white quartzite, chart, soft quartzite, and sandy quartz sand. As the silica stone of the present invention, one having a chemical component (SiO ₂ ) of 80% to 100% is used. Further, cristobalite having a crystal structure different from that of quartz, diatomaceous earth having a different formation process, or activated clay having a SiO ₂ purity of 80% or more can be used in the same manner as the silica.

The solid content concentration of the slurry-like inorganic raw material is set within a range of 10% to 50%. The solid content concentration is preferably set to about 20%. The dispersant is a polycarboxylic acid-based high-performance water reducing agent or a polycarboxylic acid-based high-performance AE water reducing agent, which is preferably 0.2% to 3% based on the solid content of the slurry-like inorganic raw material. Add within the range. In this embodiment, for example, a high-performance AE water reducing agent for polycarboxylic acid concrete is used. If this polycarboxylic acid-based concrete high-performance AE water reducing agent is set in an amount exceeding 3%, foaming increases, which is not preferable. Moreover, sufficient effect cannot be acquired as the addition amount of the high performance AE water reducing agent for polycarboxylic acid-type concrete is less than 0.2%.
The pulverization conditions in the facing collision wet pulverization step are, for example, wet pulverization for 30 minutes with a discharge pressure of 200 MPa, a solid content concentration of 20%, and a dispersant addition rate of 1%.

  In addition, after the ultra-fine powder is formed so as to have a predetermined average particle size and circularity in the opposing collision type pulverization step, it is dried by an air flow dryer as necessary to produce the cement / concrete admixture of this embodiment. Is done. In the present embodiment, the inorganic raw material of limestone or quartzite is a fine powder that is spheroidized to a mean particle size of 2 μm or less and a circularity of 0.90 or more by opposing collision.

The circularity of the cement / concrete admixture thus obtained was determined based on the following circularity formula (1) by observing the particle shape with a scanning electron microscope and subjecting it to image processing. . The circularity of the perfect circle is 1.00. FIG. 1 shows an example of a scanning electron micrograph of a cement / concrete admixture produced using limestone.
Circularity = (circumference of circle equal to projected area of particle) / (contour length of projected particle) (1)

The circularity of the cement / concrete admixture prepared using limestone (Test Example 1: Mitsubishi Materials Higashiya Mine) and silica stone (Test Example 2: manufactured by Nittsu Mining Co., Ltd., silica sand No. 3) by the above-described manufacturing method is as follows. Table 1 shows. Note that tap water is used as the solvent of the aqueous slurry.
In addition, as a comparative example, limestone finely pulverized product (Comparative Example 1) obtained by dry pulverizing limestone with a roller mill, and further classification, limestone having an average particle size equivalent to that of the admixture for high-strength concrete of this embodiment The finely pulverized product (Comparative Example 2) and the silica pulverized product (Comparative Example 3) that has been dry-pulverized with a ball mill are observed with a scanning electron microscope, and the obtained circularity is combined. Table 1 shows. 2 and 3 show examples of scanning electron micrographs in Comparative Example 1 and Comparative Example 2, respectively.

  As can be seen from Table 1, in Comparative Examples 1 to 3, the circularity is low and the particle shape is irregular and not spherical, whereas the cement-concrete admixture produced by the manufacturing method of this embodiment (Test Example) 1 and 2), it can be seen that it has a higher circularity than that of the comparative example, and has a spherical shape close to a perfect circularity of 1.00. Further, it can be seen that in Test Examples 1 and 2, fine fine powders having an average particle size of 0.5 μm or less were obtained without classification.

  As described above, in the method for producing an admixture for cement / concrete according to the present embodiment, the slurry-like inorganic raw material to which the dispersant is added is pulverized by the opposing collision wet pulverization method that causes the opposing collision at high pressure. By adjusting, the convex part of the particle surface of the fine powder is shaved, and a substantially spherical particle shape can be obtained with stable quality and without agglomeration. In addition, since the pulverization is performed to remove the convex portions on the particle surface, many fine powders of ultrafine particles having a particle diameter of 0.5 μm or less are obtained, and various desired materials (high-strength concrete, High strength non-shrink grout material, self-leveling material, etc.) and high fluidity can be realized. Furthermore, the obtained fine powder can be used as it is as an admixture of the above-mentioned various materials in a slurry state, and can also be used as a powder mixed with other additives by drying with an air dryer or the like. it can.

Moreover, the fine powder with an average particle diameter of 2 micrometers or less can be obtained by setting solid content concentration of a slurry-form inorganic raw material in the range of 10%-50%.
Furthermore, a fine powder is obtained by using a polycarboxylic acid-based high-performance water reducing agent or a polycarboxylic acid-based high-performance AE water reducing agent in place of the alkali salt of polyacrylic acid generally used in conventional wet grinding as a dispersant. The above water-reducing agent is adsorbed to the fine powder after pulverization without impairing the dispersion effect, so the amount of water-reducing agent added is reduced as an admixture used in high-strength concrete, high-strength non-shrink grout materials, self-leveling materials, etc. The economic effect is high.

  By making the inorganic raw material of limestone or silica stone into a fine powder spheroidized to a high circularity with an average particle diameter of 2 μm or less and a circularity of 0.90 or more by the production method of this embodiment, a fine powder of almost spherical fine limestone Alternatively, it is possible to obtain an admixture with high fluidity and high strength development as ultrafine silica or high strength concrete as silica powder. For example, by using the obtained limestone fine powder for high-strength concrete, it has fluidity not inferior to high-strength concrete using conventional silica fume and, as will be described later, the initial strength is 7 days old. In, it is possible to obtain a high strength expression beyond the high strength concrete using silica fume.

Next, practical examples will be described in which the cement / concrete admixture according to the present invention was actually used to produce and evaluate the cement / concrete admixture.
<Example 1>
In the dry pulverization step, silica stone (manufactured by Nissui Mining Co., Ltd., silica sand No. 3) was dry pulverized with a ball mill to obtain an inorganic raw material having an average particle size of 8.5 μm. Then, in the wet pulverization step, this inorganic raw material was wet pulverized by the opposing collision type pulverization method of the present embodiment, and the relationship between the solid content concentration of the slurry-like inorganic raw material and the average particle diameter was examined. The pulverization time at this time is 30 minutes, which is a sufficient pulverization time, and the dispersant is a slurry of a high-performance AE water reducing agent for polycarboxylic acid concrete (Reobuild (registered trademark) SP8SBS, manufactured by NMB). 1.5% of the solid content of the inorganic raw material was added. The results are shown in Table 2 below. In addition, the average particle diameter measured D50 value using the laser diffraction scattering type particle size analyzer (Shimadzu SALD-2100 type). Moreover, the result of the particle size distribution measurement which compared the pulverized material processed by the said wet grinding | pulverization with the unprocessed thing is shown in FIG.

  As is apparent from this result, fine fine powder having an average particle size of 2 μm or less is obtained within the range of the present invention, that is, within the range of the solid content concentration of the slurry-like inorganic raw material of 10% to 50%. In particular, a fine powder having the solid content concentration of 20% and the smallest average particle diameter is obtained.

<Example 2>
In the dry pulverization step, limestone (Mitsubishi Materials Totani Mine) was dry pulverized with a roller mill to obtain an inorganic raw material having an average particle diameter of 18.6 μm. Then, in the wet pulverization step, this inorganic raw material was wet pulverized by the opposing collision type pulverization method of this embodiment, and the relationship between the addition rate of the dispersant and the average particle diameter was examined. The pulverization time at this time was 60 minutes, and the solid content concentration of the slurry-like inorganic raw material was 20%. In addition, a high-performance AE water reducing agent for polycarboxylic acid-based concrete (Reobuild (registered trademark) SP8SBS, manufactured by NM B) was used as the dispersant. The results are shown in Table 3 below. In addition, as a comparative example, the same thing was investigated for a sample not added with a dispersant (Comparative Example 6) and a sample added with a polyacrylic acid-based soda (commercially available product) conventionally used as a dispersant (Comparative Example 8). The results are also shown in Table 3.

  As is apparent from the results, within the scope of the present invention, fine fine powders having an average particle size of 0.5 μm or less were obtained, and a high-performance AE water reducing agent for polycarboxylic acid concrete was used as a dispersant. Then, it is not inferior to the conventionally used dispersant. However, if 4% of the high-performance AE water reducing agent for polycarboxylic acid-based concrete is added to the solid content of the slurry-like inorganic raw material, foaming increases, so this addition amount is in the range of 0.2% to 3%. The inside is preferable. In addition, when a dispersing agent is not added (comparative example 6), grindability is inferior and an average particle diameter exceeds 3 micrometers.

<Example 3>
The slurry-like fine powder of Test Example 1 was dried with an air dryer, and 50 kg of this was produced at a ratio of 10 parts by weight with respect to 90 parts by weight of low heat Portland cement (manufactured by Mitsubishi Materials Corporation). And mixed for 15 minutes to obtain a mixed cement (Test Example 9 (product of the present invention)). Further, in the same manner, (1) silica fume (commercially available product), (2) fine powder having an average particle size of 0.58 μm obtained by classifying the dry pulverized product of Comparative Example 1 was used as a mixed cement (Comparative Example). 9 (Comparative product 1), Comparative example 10 (Comparative product 2)).

  Cement mortars were prepared from these cements according to JASS 5T 701-2005 “Quality standards for high-strength concrete cement (draft)” (also referred to as NewRC test). About the mortar, the performance was evaluated about 0 striking flow (fluidity evaluation) and compressive strength. The target water cement ratio was set to 0.18 considering the cement for ultra high strength concrete.

In this evaluation, the following materials were used other than the admixture.
・ Cement: Low heat Portland cement (Mitsubishi Materials Corporation)
・ Sand: Standard sand for cement testing (Cement Association)
・ Water-reducing agent: Polycarboxylic acid-based high-performance AE (air entraining) water-reducing agent (Reobuild (registered trademark) ・ SP8SBS NM company)
・ Water: Tap water (water temperature 20 ℃)

The zero stroke flow is the diameter of the mortar after spreading when the flow cone is removed upward according to the flow test of JIS R 5201 “Cement physical test method”. The addition rate of the water reducing agent was adjusted so that the diameter of the mortar was in the range of 250 to 270 mm.
The compressive strength was tested according to JIS R 5201 “Cement physical test method”. The dimensions of the cylindrical specimen were 50 mmφ × 100 mmH, and the ages were 7 days, 28 days, and 91 days.
The results are shown in Table 4 below.

  From this result, the mortar using the admixture of this example (Test Example 8) had fluidity and strength development more than the mortar using the silica fume (Comparative Example 9). Moreover, the mortar (Comparative Example 10) using the admixture obtained by dry-pulverizing limestone increases the water reducing agent addition rate in order to obtain a reference 0-stroke flow value as compared with Test Example 8. Therefore, fluidity is poor and strength development is low.

The technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.
For example, as the base cement, in addition to the medium-heated Portland cement and the low-heat Portland cement described above, normal, early strength, sulfate-resistant Portland cement, blast furnace cement, fly ash cement, and other mixed cements may be adopted. I do not care.

1 is a scanning electron micrograph showing a cement / concrete admixture in an embodiment of a method for producing an admixture for cement / concrete and an admixture for cement / concrete according to the present invention. It is a scanning electron micrograph which shows the admixture for cement and concrete in the manufacturing method of the admixture for cement and concrete which concerns on this invention, and the prior art example (comparative example 1) of the admixture for cement and concrete. It is a scanning electron micrograph which shows the cement-concrete admixture in the manufacturing method of the cement-concrete admixture according to the present invention and the conventional example of the cement-concrete admixture (Comparative Example 2). In the manufacturing method of the cement and concrete admixture according to the present invention and the example of cement and concrete admixture, a graph showing the results of particle size distribution measurement comparing the pulverized material processed by wet pulverization with the untreated one is there.

Claims (6)

  A method for producing an admixture for cement and concrete, comprising a step of producing a spherical fine powder admixture by causing a slurry-like inorganic raw material to which a dispersant is added to face each other at high pressure. In the manufacturing method of the admixture for cement and concrete according to claim 1,
A method for producing an admixture for cement and concrete, wherein the solid content concentration of the slurry-like inorganic raw material is set within a range of 10% to 50%. In the manufacturing method of the admixture for cement and concrete according to claim 1 or 2,
A method for producing an admixture for cement and concrete, wherein a polycarboxylic acid-based high-performance water reducing agent or a polycarboxylic acid-based high-performance AE water reducing agent is used as the dispersant. In the manufacturing method of the cement-concrete admixture according to any one of claims 1 to 3,
A method for producing an admixture for cement and concrete, characterized in that the inorganic raw material of limestone or silica is made into fine powder spheroidized to an average particle size of 2 μm or less and a circularity of 0.90 or more by the opposing collision. In the manufacturing method of the admixture for cement and concrete according to any one of claims 1 to 4,
A method for producing an admixture for cement / concrete, comprising using, as the slurry-like inorganic raw material, a waste slurry containing fine powder generated when limestone is crushed and limestone is collected.   A cement / concrete admixture produced by the method for producing a cement / concrete admixture according to any one of claims 1 to 5.