JP5170032B2 - Immediate demolding concrete product and manufacturing method thereof - Google Patents

Description

  The present invention relates to an immediate demolding concrete product and a method for producing the same, and more particularly to an immediate demolding concrete product having excellent filling properties, a dense and high strength, and a good moldability and a method for producing the same.

An immediate demolding concrete product is a concrete product produced by putting concrete kneaded with a very small amount of water into a product form, compacting by vibration, and then immediately demolding and curing.
Examples of such an immediate demolding concrete product include a pile block, a hollow concrete block, a concrete plate for sidewalk, an interlocking block, an unreinforced concrete pipe, and the like, and examples include products that are inexpensive and mass-produced.

  In order to produce a concrete product by casting, it is not possible to demold it until the steam curing is completed after the fluid concrete is put into the formwork. In addition, since concrete can be put into a product formwork and demolded immediately after vibration compaction molding to form the next concrete, mass production is possible with one formwork.

However, since immediate demolding concrete products are demolded immediately, the amount of kneading water is extremely small in order to prevent loss of shape. It was difficult.
Furthermore, if the water-cement ratio is reduced in order to obtain high strength, the filling property is lowered, and not only the strength but also the surface properties are deteriorated.

In order to improve the fluidity and strength of concrete, silica fume is generally mixed with various cements as an admixture.
This silica fume is a spherical ultrafine particle material with a particle size of about 0.1 to 0.3 μm mainly composed of amorphous silicon dioxide produced as a by-product during the production of metallic silicon and ferrosilicon, and when mixed with mortar or concrete It is known that the cured body is densified and its strength is enhanced by its high pozzolanic activity and microfiller effect.
However, the primary particles of silica fume are ultrafine particles having a particle size of about 0.1 to 0.3 μm, and usually aggregate to form secondary particles of several to several tens of μm in size. Dispersibility is not good.
Silica fume is a by-product of the production of metallic silicon and ferrosilicon, so the quality is not stable and contains several percent of various impurities such as unburned carbon, sulfur trioxide, and magnesium oxide. When the silica fume is used as an admixture for cement, impurities need to adjust the required amount of a chemical admixture such as a high-performance water reducing agent or an AE agent each time.

  On the other hand, Japanese Patent Application Laid-Open No. 2001-97712 discloses a method for producing spherical silica particles having a relatively large average particle size of less than 8 μm by melting and spheronizing fine silica fume in a burner flame. It has been proposed (Patent Document 1). Although these spherical silica particles are easy to handle and have the effect of improving the fluidity of the concrete composition, inorganic impurities such as magnesium oxide mixed in silica fume cannot be removed, and the quality of the concrete is stabilized. It is difficult to let

  Therefore, an immediate demolding concrete product with good filling properties, high density, high strength, and good moldability and a method for producing the same are expected.

JP 2001-97712 A

  The object of the present invention is to overcome the above-mentioned problems and to provide an instant demolding concrete product having excellent filling properties, high density, high strength, and excellent moldability even when the water / cement ratio is small, and its production Is to provide a method.

The instant demolding concrete product of the present invention is obtained by subjecting a concrete composition containing (A) cement, (B) fine synthetic spherical silicon dioxide powder, (C) lithium sulfate, (D) aggregate and water to pressure vibration molding. The component (B) has a silicon dioxide content of 99% by mass or more, an ignition loss at 1000 ± 50 ° C. of 0.3% by mass or less, and a BET specific surface area of 1-4. 0.8 m ² / g, and in the concrete blend, the content of the component (B) is 10 to 40 parts by mass with respect to 100 parts by mass in total of the component (A) and the component (B). The water / [(A) component and (B) component] mass ratio is 0.16 or more and less than 0.3, and the total amount of 100 parts by mass of the (A) component and the (B) component is relative to the (C) component. The immediate demolding core is characterized in that the content of is 1.5 to 2.5 parts by mass A cleat product.

  Another immediate demolding concrete product of the present invention is an immediate demolding concrete product, characterized in that (E) a water reducing agent is further contained in the immediate demolding concrete product.

The method for producing an immediate demolding concrete product of the present invention comprises adding (A) cement, (B) synthetic spherical silicon dioxide fine powder, (C) lithium sulfate, (D) aggregate and water, Has a silicon dioxide content of 99% by mass or more, an ignition loss at 1000 ± 50 ° C. of 0.3% by mass or less, and a BET specific surface area of 1 to 4.8 m ² / g. B) The content of the component (B) is blended so as to be 10 to 40 parts by mass with respect to 100 parts by mass in total with the component, and water is added to the water / [(A) component and (B) component] mass ratio. However, the content of the component (C) is 1.5 to 2.5 parts by mass with respect to a total of 100 parts by mass of the component (A) and the component (B). And then knead uniformly to prepare a concrete compound, and the prepared concrete compound is formed into a formwork The method for producing an immediate demolding concrete product is characterized in that it is molded by compaction by pressing vibration and molded immediately after being compacted and then subjected to curing treatment.

The instant demolding concrete product of the present invention can be an inexpensive immediate demolding concrete product that has good filling properties, is dense and exhibits high strength, and has good moldability.
Furthermore, the immediate demolding concrete product of the present invention can improve wear resistance, that is, surface smoothness, in addition to the above effects.
Moreover, the method for producing an immediate demolding concrete product according to the present invention can efficiently produce the instant demolding concrete product in a large amount at a low cost.

It is a figure which shows the filling rate of the illustrated immediate demolding concrete molded object. It is a figure which shows the compressive strength of the illustrated immediate demolding concrete molded object.

An exemplary embodiment for carrying out the present invention will be described below.
The instant demolding concrete product of the present invention is obtained by subjecting a concrete composition containing (A) cement, (B) fine synthetic spherical silicon dioxide powder, (C) lithium sulfate, (D) aggregate and water to pressure vibration molding. The component (B) has a silicon dioxide content of 99% by mass or more, an ignition loss at 1000 ± 50 ° C. of 0.3% by mass or less, and a BET specific surface area of 1 4.8 m ² / g, and in the concrete blend, the content of the component (B) is 10 to 40 parts by mass with respect to 100 parts by mass of the total of the component (A) and the component (B). Yes, an immediate demolding concrete product having a water / [(A) component and (B) component] mass ratio of 0.16 or more and less than 0.3.

There is no restriction | limiting in particular as (A) cement in the concrete compound used for the immediate demolding concrete product of this invention, From the cement currently used for the conventional concrete product, according to the use of a concrete product, You can make the right choice.
As such a cement, for example, at least one kind selected from various portland cements such as normal, moderate heat, low heat, early strength, super early strength, sulfate resistance, mixed cements such as blast furnace cement, fly ash cement and silica cement Can be mentioned.

Further, in the concrete composition, the synthetic spherical silicon dioxide fine powder used as the component (B) is a fine particle material mainly composed of amorphous SiO ₂ , for example, igniting the metal silicon powder in an oxygen-containing atmosphere. It is a synthetic product produced by forming a combustion flame and continuously oxidizing and burning metal silicon powder.
Moreover, the silicon dioxide powder may coexist at the time of oxidative combustion of the metal silicon powder to burn impurities in the silicon dioxide powder.
Because it is such a synthetic product, unlike silica fume, which is a by-product during production of other materials and contains a large amount of impurities, the silicon dioxide content is 99% by mass or more, and the ignition loss at 1000 ± 50 ° C. is 0.3%. It is a high purity of less than mass%, contains almost no impurities harmful to mortar and concrete such as unburned carbon, sulfur trioxide, magnesium oxide, etc. and has a BET specific surface area of 1 to 4.8 m ² / g. It is a spherical silicon dioxide fine powder having a large particle size.
Here, the ignition loss is measured by a chemical analysis method of JIS R 5202 Portland cement, and the BET specific surface area is measured by a “nitrogen adsorption method”.

The synthetic spherical silicon dioxide fine powder used in the present invention has a BET specific surface area in the above range, a particle size of several μm to several tens of μm, several times to several tens of times larger than silica fume, and a large bulk density. It has good properties, does not agglomerate in the concrete composition, has excellent dispersibility and is easy to knead, and a highly fluid concrete composition can be obtained.
For example, such synthetic spherical silicon dioxide fine powder is commercially available under the trade names Admafine SO-E3, SO-E5, SO-E6, SO-C3, SO-C5, SO-C6, etc., manufactured by Admatechs. can do.

  Further, the shape of the synthetic spherical silicon fine powder may be a true sphere, an ellipse, or a spherical shape that is slightly distorted and uneven, and is included in the “spherical shape” in the present invention.

  Such spherical silicon dioxide fine powder has (1) a large particle size compared to silica fume, so it has a low degree of aggregation and excellent dispersibility, and can be used in large quantities even at a low water / cement ratio. Yes, (2) High sphericity, excellent fluidity and low viscosity, (3) Even if it is used in a large amount with few impurities, it does not adversely affect the physical properties of concrete, and has immediate demoldability High-strength concrete products excellent in

  The content of the synthetic spherical silicon dioxide fine powder of the component (B) in the concrete blend is the above (A) from the viewpoints of workability, compaction, surface finish and strength required for immediate demolding. ) Component and the component (B) are 100 parts by mass in total, and the content of the component (B) is 10 to 40 parts by mass, preferably 20 to 30 parts by mass.

In the concrete blend, lithium sulfate is blended as the component (C).
In addition to lithium sulfate available on the market, lithium sulfate can be used as a by-product in the production of lithium batteries and used as industrial waste. This is also environmentally preferable.

The lithium sulfate content of the component (C) in the concrete blend is the components (A) and (B) in terms of workability, compaction, surface finish and strength required for immediate demolding. The content of the component (C) is 0.5 to 3.0 parts by mass, and 1.5 to 2.5 parts by mass in the present invention with respect to 100 parts by mass of

In the concrete composition, the aggregate used as the component (D) includes a fine aggregate and a coarse aggregate. Examples of the fine aggregate include mountain sand used in ordinary mortar and concrete, Land sand, sea sand, river sand, crushed sand, blast furnace slag fine aggregate, ferronickel slag fine aggregate, copper slag fine aggregate, electric furnace oxidation slag, and the like.
The fine aggregate preferably has a fine particle amount of 5% by mass or less, preferably 3% by mass or less, as determined by the method of JIS A 1103 “Aggregate Fine Particle Amount Test Method”. Can be used.
Moreover, as a coarse aggregate, river gravel, mountain gravel, land gravel, sea gravel, crushed stone, blast furnace slag coarse aggregate, electric furnace oxidation slag, etc. can be used, for example.
The fine aggregate and coarse aggregate to be used are desirably selected to have a quality that can satisfy a compressive strength of 150 N / mm ² .

Furthermore, the concrete composition may contain a water reducing agent as the component (E) as necessary.
Examples of the water reducing agent include a high performance water reducing agent and a high performance AE water reducing agent that is a polycarboxylate-based water reducing agent. A general water reducing agent such as lignin sulfonate having a small water reducing rate has an effect of improving fluidity. Is difficult to obtain.
The high-performance water reducing agent is mainly composed of either a polyalkylallyl sulfonate system or a melamine formalin resin sulfonate system.

For example, polyalkylallyl sulfonate-based high-performance water reducing agents include methyl naphthalene sulfonic acid formalin condensate, naphthalene sulfonic acid formalin condensate, anthracene sulfonic acid formalin condensate, and the like. Trade name “FT-500” and its series, product names “Mighty-100 (powder)” and “Mighty-150” and its series, manufactured by Kao Corporation, Daiichi Kogyo Seiyaku Co., Ltd. Product name “Sunflow PS” and its series, such as “Cell Flow 110P (powder)”, Takemoto Yushi Co., Ltd., “Pole Fine 510N”, and Floric Inc. A typical product is the aromatic amino sulfonate-based high-performance water reducing agent of the product name “Palic FP200H” series.
The melamine formalin resin sulfonate-based high-performance water reducing agent includes trade name “FT-3S” manufactured by Grace Chemicals Co., Ltd., trade name “Molmaster F-10 (powder)” manufactured by Showa Denko Co., Ltd. and “ Molemaster F-20 (powder) ".

In addition, as the polycarboxylate-based high-performance AE water reducing agent, the product name “Leo Build SP8” series manufactured by BASF Pozzolith Co., Ltd., the product name “Floric SF500” series manufactured by Floric Co., Ltd. ) Product name “Chupol HP8,11” series manufactured by company, product name “Darlex Super 100, 200, 300, 1000” series manufactured by Grace Chemicals Co., Ltd., “Mighty 21WH, 3000S” manufactured by Kao Corporation, etc. Can be obtained and used on the market.
The blending amount of the high performance water reducing agent or the high performance AE water reducing agent is usually about 1.0 to 2.5 parts by mass with respect to 100 parts by mass in total of the component (A) and the component (B). desirable.

Moreover, an inorganic admixture can be further mix | blended with the said concrete compound as needed.
As the inorganic admixture, any known inorganic admixture such as blast furnace slag fine powder, limestone fine powder, fly ash, expansion material, high-strength concrete admixture, and the like can be used. It can be added in the amount blended in.

  Moreover, although water is mix | blended with a concrete compound, it mix | blends so that water / [total of (A) component and (B) component] mass ratio may be 0.16 or more and less than 0.3. By making the amount of water blended in this way small, it is possible to immediately remove the mold without losing its shape, and it is possible to produce dense and high-strength concrete with good moldability.

Next, a method for producing an immediate demolding concrete product using a concrete blend obtained by blending the above materials will be described.
The method for producing an immediate demolding concrete product of the present invention comprises adding (A) cement, (B) synthetic spherical silicon dioxide fine powder, (C) lithium sulfate, (D) aggregate and water, Has a silicon dioxide content of 99% by mass or more, an ignition loss at 1000 ± 50 ° C. of 0.3% by mass or less, and a BET specific surface area of 1 to 4.8 m ² / g. B) The content of the component (B) is blended so as to be 10 to 40 parts by mass with respect to 100 parts by mass in total with the component, and water is water / [(A) component and (B) component] mass ratio. Is added to be 0.16 or more and less than 0.3, and a concrete compound is prepared by uniformly kneading, and the prepared concrete compound is put into a formwork and compacted under pressure and vibration. This is a method in which the mold is removed immediately after being molded and subjected to curing treatment.
In addition, as described above, a water reducing agent, an inorganic admixture, or the like can be added as necessary when preparing the concrete composition.

That is, the above-mentioned material components used in the concrete blend used for the production of the immediate demolding concrete product of the present invention, the uniaxial or biaxial forced kneading pug mill type mixer, the forced kneading pan type with the above-mentioned prescribed ratio of blending The concrete composition is prepared by kneading using a mixer or a tiltable mixer.
Next, this concrete composition is put into a mold having a desired shape and molded.
At the time of molding, a pressure vibration molding process is added. Thereby, the filling property of the obtained concrete product becomes better and densified, which is effective.
The pressure vibration forming process depends on the output of the machine to be used and the frequency. For example, the applied pressure is 0.04 to 0.49 MPa, the frequency is 47 to 108 Hz, the amplitude is 0.3 to 2.5 mm, and the vibration The time is about 1 to 60 seconds and the maximum acceleration is about 41 to 442 m / s ² .

The concrete composition subjected to the pressure vibration molding treatment is immediately demolded from the mold.
Subsequently, the immediate demolding concrete product of the present invention is obtained by curing.
The curing method is not particularly limited, and any method can be applied as long as it is a normal concrete curing method. For example, steam curing can be applied. As specific curing conditions, after precuring for about 2 to 6 hours at room temperature, the temperature is increased to about 60 to 80 ° C. at a rate of temperature increase of about 10 to 30 ° C. per hour, and then 2 to 6 hours. A method of maintaining the degree and then naturally cooling can be exemplified.

The present invention will be illustrated by the following examples and comparative examples, but is not limited thereto.
(Materials used)
・ Cement NC: Ordinary Portland cement (manufactured by Sumitomo Osaka Cement Co., Ltd.)
Density 3.15 g / cm ³
-Fine aggregate S: mountain sand (produced in Kakegawa, Shizuoka Prefecture) density 2.58 g / cm ³
Coarse aggregate G: crushed stone (Okutama, Nishitama-gun) density 2.64 g / cm ³
・ Lithium sulfate: Reagent (Mitsuwa Chemical Co., Ltd.)
Water W: tap water Synthetic spherical silicon dioxide powder: shown in Table 1 below.
In Table 1 below, a typical example of silica fume is also shown for comparison.

In Table 1 above, the content of silicon dioxide is the Cement Association method “chemical analysis method of siliceous raw materials”, and the content of SO ₃ (sulfur trioxide) and MgO is JIS R 5202 “chemical analysis method of Portland cement” ”And measured according to each. The ignition loss was measured at 1000 ± 50 ° C. according to JIS A 6201 “Fly Ash for Concrete”. Further, as an index of the amount of unburned carbon (unburned carbon), the amount of methylene blue adsorbed was measured according to the “Methylene Blue Adsorbed Amount Test” of the Cement Association Method. The BET specific surface area was measured by the “nitrogen adsorption method”.
When observed at a magnification of 5,000 to 50,000 times using a FE-SEM (field emission scanning electron microscope), the synthetic spherical silicon dioxide powder has almost spherical primary particles with a particle size of about 0.5 to 50 μm. Silica fume, while not agglomerated, aggregates most of spherical or non-spherical primary particles with a particle size of about 0.1 to 0.3 μm to form irregularly shaped secondary particles with a particle size of about 10 to 50 μm. It was.

From Table 1 above, the synthetic spherical silicon dioxide powder has a higher silicon dioxide content than silica fume and an extremely low content of SO ₃ and MgO as impurities. Further, since the synthetic spherical silicon dioxide powder has significantly less ignition loss and methylene blue adsorption than silica fume, it is judged that there is little unburned carbon (unburned carbon). Moreover, it turns out that a synthetic | combination spherical silicon dioxide powder is significantly smaller than a silica fume in a BET method specific surface area.

(Examples 1-6, Comparative Examples 1-3)
Using each of the above materials, each concrete blend having the blend composition shown in Table 2 was prepared.
Specifically, cement (NC), fine aggregate (S), coarse aggregate (G), synthetic spherical silicon dioxide powder, and lithium sulfate are charged into the biaxial forced kneading mixer in the proportions shown in Table 2 for 30 seconds. After stirring, tap water (W: kneaded water) is added in such an amount that the mass ratio of water / [cement and synthetic spherical silicon dioxide powder] is 0.25 as shown in Table 2, and further for 3 minutes. Each concrete compound was prepared by kneading.

As a formwork, a concrete strength test form having an inner diameter of 10 cm and a height of 20 cm was used, and each of the above concrete compositions was put into the formwork. The amount to be added was measured by measuring the mass of 10 cm in height when the porosity was theoretically 0%, and the amount corresponding to the mass was added.
Subsequently, pressure vibration was added to the concrete composition in the mold by using the one accompanying the marshalling test runner described in JP-A-2005-241371.
Specifically, the ramp is attached so that a cylindrical heavy object having a weight of 4500 g can move up and down relative to a guide rod inserted through the heavy article, and has fallen to the lower end of the guide rod. A pressure plate is provided for transmitting the impact of the heavy object to the concrete underneath, and a fixture for restricting the rising position of the heavy object is provided on the upper portion of the guide rod.
The diameter of the pressing plate provided at the lower end of the rammer is substantially the same as the inner diameter of the mold, and when the pressing plate is placed on the concrete compound put into the mold, the surface of the concrete compound It is comprised so that the whole may be covered.

The rammer was placed so that the upper surface of the kneaded concrete put into the mold was covered with the press plate of the rammer. Then, in a state where the guide rod of the rammer was supported vertically, the heavy object was pulled up to the upper end, and the heavy object was freely dropped from the upper end 40 times in 80 seconds. When the heavy material falls, the concrete mixture is tamped through the pressing plate and the surface is pressed down. Therefore, the distance A from the upper end of the formwork to the upper surface of the concrete was measured by removing the rammer.
In this way, if the distance A from the upper end of the formwork to the top surface of the concrete is measured, the concrete height B in the formwork can be obtained by subtracting from the height of the formwork, and the maximum compaction height By dividing 10 cm by the height B, the concrete filling rate (consolidation degree) when a heavy object was dropped at a certain number of times was determined.
The results are shown in Table 3 and FIG. In addition, the density (g / cm < ³ >) in Table 3 shows the density of the obtained immediate demolding concrete molded object.

Subsequently, each immediate demolding concrete molded body is taken out from the mold, and each of the immediate demolding concrete molded bodies of Examples 1 to 6 and Comparative Examples 1 to 3 is subjected to the following steam curing and standard curing, respectively. An immediate demolding concrete product was obtained.
Steam curing: 4 hours after air curing at room temperature (pre-curing), hold for 4 hours at a heating rate of 20 ° C / hour and hold for 4 hours Standard cooling: Molding, demolding after 24 hours Immerse in water up to 14 days of age while maintaining at 20 ± 3 ° C

(Test example)
The results of measuring the compressive strength of each immediate demolding concrete product obtained are shown in Table 4 and FIG.
The compressive strength is a value measured according to JIS A 1108.

  From Table 3 and FIG. 1, the filling property is improved and densified as the blending amount of the synthetic spherical silicon dioxide increases. From Table 4 and FIG. 2, the strength developability as the blending amount of lithium sulfate increases. It turns out that became high.

  The instant demolding concrete product of the present invention can be applied to a pile block, a hollow concrete block, a concrete plate for sidewalk, an interlocking block, an unreinforced concrete pipe, etc., and an inexpensive mass-consumed product for civil engineering and construction Can be applied to. Furthermore, it can be used for waterway applications.

Claims (3)

(A) Cement, (B) Synthetic spherical silicon dioxide fine powder, (C) Lithium sulfate, (D) Immediate demolding concrete product formed by pressure vibration molding of a concrete composition containing aggregate and water, The component (B) has a silicon dioxide content of 99% by mass or more, an ignition loss at 1000 ± 50 ° C. of 0.3% by mass or less, a BET specific surface area of 1 to 4.8 m ² / g, and In the concrete blend, the content of the component (B) is 10 to 40 parts by mass with respect to a total of 100 parts by mass of the component (A) and the component (B), and water / [(A) component and (B ) Component] The mass ratio is 0.16 or more and less than 0.3, and the content of the component (C) is 1.5 to 2. with respect to 100 parts by mass in total of the component (A) and the component (B) . Immediate demolding concrete product characterized by being 5 parts by mass.   The immediate demolding concrete product according to claim 1, further comprising (E) a water reducing agent. (A) cement, (B) synthetic spherical silicon dioxide fine powder, (C) lithium sulfate, (D) aggregate and water are added. The component (B) has a silicon dioxide content of 99% by mass or more, and 1000 The ignition loss at ± 50 ° C. is 0.3% by mass or less and the BET specific surface area is 1 to 4.8 m ² / g, and the total amount of (A) component and (B) component is 100 parts by mass (B ) Component content is blended so as to be 10 to 40 parts by mass, and the water / [(A) component and (B) component] mass ratio is 0.16 or more and less than 0.3, Addition of the component (C) to the total amount of 100 parts by mass of the component (A) and the component (B) so that the content of the component (C) is 1.5 to 2.5 parts by mass, and knead uniformly to mix the concrete. The concrete composition thus prepared is put into a mold and molded by compaction by pressure vibration. A method for producing an immediate demolding concrete product, characterized in that the mold is immediately demolded and cured.

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