JP2865567B2 - Centrifugal force forming cement composition and concrete forming product - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cement composition for centrifugal force molding, and a molded concrete product produced by using the same, particularly a fume tube.

More specifically, the present invention is directed to a method for shortening the time required for a centrifugal force forming step, reducing the amount of sludge generated during compaction, and having high dewatering properties, and thereby obtaining a compact concrete product. The present invention relates to a cement composition for centrifugal force molding having a high property and a good finish on the inner surface of a molded article, and a centrifugal force molded concrete product obtained therefrom, particularly a fume pipe.

[0003]

2. Description of the Related Art Conventionally, methods for producing concrete products such as piles, poles, fume pipes and the like are characterized in that the obtained products have high strength and are suitable for formability in producing columnar products. The centrifugal molding method is widely used. The centrifugal force forming method is a method of compacting concrete before hardening by centrifugal force obtained by rotating the forming mold at a high speed, and squeezing out mixing water to obtain a dense concrete product.

[0004] However, in the centrifugal force forming method, a large amount of sludge is generated at the time of manufacturing a product, and the processing of the sludge requires a large processing cost. Here, the sludge means the solid content in the slag separated from the water squeezed out of the concrete at the time of centrifugal molding, accompanied by the fine powder portion in the concrete. At a site such as a factory, the sludge is treated as landfill or industrial waste, so that a large disposal cost is required.

Conventionally, in order to prevent the generation of such sludge, a method of suppressing the generation of sludge by adhering a polymer thickener such as methylcellulose or a water-retention admixture to the inner surface of the pipe, and various flocculants Has been proposed to separate water and solids. However, these measures reduce the strength of the molded product, and also increase the thickness of the paste layer on the inner surface of the molded product, for example, the tube material, so that sagging and cracking are likely to occur. It was said to be unavailable.

[0006] The present applicant has proposed means for solving the above-mentioned problem of the conventional centrifugal force forming. (Patent Application No. 2-333481, Patent Application No. 4-110450
No.) This means is that centrifugal molding is performed by limiting the particle size of cement particles, limiting the other fine and coarse powder portions to a prescribed amount or less, and limiting the amount of gypsum contained to a prescribed amount or less. The solid content in the slurry that is sometimes discharged is greatly reduced, and a great effect is obtained in increasing the strength of the concrete molded product. However, in the case of the above cement, when this is used for the production of various pipes, although the molding time is reduced and the sludge is reduced,
Sludge was never completely gone.

[0007]

DISCLOSURE OF THE INVENTION The present invention relates to a method for producing a concrete product by a centrifugal force forming method, in which a small amount of sludge is generated at the time of centrifugal force forming and the dewatering property at the time of forming is improved. High moldability, short molding time,
Another object of the present invention is to provide a concrete product having a compacted inner surface finish, particularly a centrifugal force forming cement composition suitable for producing a fume tube, and a concrete product obtained therefrom, particularly a fume tube.

[0008]

SUMMARY OF THE INVENTION A centrifugal molding cement composition according to the present invention comprises a first cement particle component having a particle size of less than 5 μm and a volume content of less than 20%,
A second cement particle component having a particle size of not less than 11 μm and a volume content of 35% or less;
A third cement particle component having a particle size of less than 2 μm and a volume content of 35% or more;
a fourth cement particle component having a particle size of less than μm and having a volume content of 30% or less;
m and a fifth cement particle component having a volume content of 5% or less and gypsum, and the content of the gypsum is 1.5% by weight or less in terms of SO _3. It is characterized by being.

Another centrifugal molding cement composition of the present invention has a particle size of less than 5 μm, a first cement particle component having a volume content of 20% or less, and a particle size of 5 μm or more and less than 11 μm. And a second material having a volume content of 35% or less.
A cement particle component, a third cement particle component having a particle size of 11 μm or more and less than 22 μm and having a volume content of 35% or more, and a particle size of 22 μm or more and less than 44 μm and a volume of 30% or less A fourth cement particle component having a content, a fifth cement particle component having a particle size of 44 μm or more and 88 μm or less and having a volume content of 5% or less, gypsum, and a water-soluble polymer material And the gypsum content is 1.5 when converted to SO _3.
% By weight or less.

In the cement composition for centrifugal molding according to the present invention, the admixture comprising the water-soluble polymer material is contained in an amount of 0.01% by weight or less based on the total weight of the cement component. Is preferred. In addition, the water-soluble polymer material is carboxymethyl cellulose, methyl cellulose, water-soluble urea-formaldehyde condensate, polyethylene glycol, polyethylene oxide, polyacrylic acid and its derivatives and copolymers, polyacrylamide and its derivatives and copolymers, It can be selected from acrylic acid-acrylamide copolymer.

In the above-mentioned cement composition for centrifugal molding according to the present invention, it is preferable that the water-soluble polymer material is selected from a hydrolyzate of polyacrylamide.

It is preferable that the polyacrylamide hydrolyzate has a molecular weight of 10 to 15,000,000.

The method of the present invention is a method for producing a concrete molded product by the centrifugal force forming method using the centrifugal force forming cement according to the present invention.

[0014] The molded concrete products of the present invention include various concrete molded products produced by the method of the present invention. In particular, a typical concrete molded product of the present invention is a concrete fume tube.

[0015]

The cement composition for centrifugal force molding of the present invention will now be described.
The concrete molded article manufacturing method and the product thereof will be described in detail. The cement composition for centrifugal molding of the present invention contains a cement component and a gypsum component, but adjusts the particle size distribution of the cement particles, reduces the content of the fine powder portion and the coarse powder portion to a specific value, and The gypsum content was also limited. Examples of the above-mentioned cement include known portland cements such as ordinary portland cement, early-strength portland cement, and moderately heated portland cement, and admixtures for cement such as blast furnace slag, fly ash, and silica fume.
Or a mixed cement obtained by adding and mixing two or more types.

Gypsum used in the cement composition of the present invention is not particularly limited, and any of gypsum dihydrate, hemihydrate gypsum, and anhydrous gypsum may be used.

The cement component of the cement composition for centrifugal force forming according to the present invention comprises a cement component having a particle size of less than 5 μm as a first cement particle component in a volume content of 20% or less, preferably 0 to 12%. Containing, as the second cement particle component, cement particles having a particle size of 5 μm or more and less than 11 μm, 35% or less, preferably 0 to 30%,
At a volume content of 1% as the third cement particle component.
Cement particles having a particle size of 1 μm or more and less than 22 μm are contained at a volume content of 35% or more, preferably 45 to 100%.
Cement particles having a particle size of less than 4 μm are contained at a volume content of 30% or less, preferably 0 to 25%, and as a fifth cement particle component, 44 μm or more and 88 μm or less.
m, and contains 5% or less, preferably 0 to 3%, by volume of cement particles having a particle size of not more than m.

The second cement particle component (particle size: 5 μm)
When the volume content of the above (less than 11 μm) exceeds 35%, the content of the fine powder component in the cement increases, so that the solid content in the glue discharged at the time of centrifugal molding increases, and These fine powders adhere to the surface of the molded product, especially to the inner surface of the tubular product, and the formed paste layer becomes thicker, and the compaction characteristics deteriorate.

The fourth cement particle component (particle size:
If the volume content (22 μm or more and less than 44 μm) exceeds 30%, the product obtained from cement containing such a relatively large particle size coarse powder has the disadvantage of insufficient strength.

In order to prepare the cement composition for centrifugal molding of the present invention containing the cement component having the above-mentioned particle size distribution, fine particles, that is, fine particles having a particle size of less than 5 μm, are classified from the pulverized cement particles by classification. One component and coarse particles, ie, the fifth component exceeding 44 μm are removed, and the first,
The method of adjusting the volume content of the second, third, fourth and fifth cement particle components as described above, and the first, second, third and fourth particles having a particle size within the above-mentioned range in advance by a classification operation. And 5 cement particle components are prepared in advance, and a method of blending them at a desired mixing ratio can be used.

The method for classifying cement particles is not particularly limited, and gravity classification, centrifugal classification, inertial classification, and the like are generally used. Other methods, for example, sieve classification, may be employed. .

The cement composition for centrifugal force forming of the present invention has a SO ₃ equivalent of 1.5% by weight or less, preferably 1.
Contains 0-1.3% by weight gypsum. This gypsum is usually contained in Porland cement at a content of 2.0% by weight, and is an essential component for the hydration reaction of cement. However, if the content exceeds 1.5% by weight, The solid content in the slag discharged during centrifugal molding increases, and the paste layer formed on the inner surface of the tube becomes thick.

The centrifugal molding cement composition of the present invention comprises:
It includes those containing the cement component and the gypsum component and an admixture composed of a water-soluble polymer material.

As described above, the admixture used in the present invention is composed of a water-soluble polymer material, and there is no particular limitation on the type thereof. Generally, carboxymethylcellulose, methylcellulose, and water-soluble urea-formaldehyde are used. Condensate, polyethylene glycol, polyethylene oxide, polyacrylic acid and its derivatives and copolymers, polyacrylamide and its derivatives and copolymers, at least one of acrylic acid-acrylamide copolymer is used, especially polyacrylamide and It is preferable to use a derivative (copolymer) thereof or an acrylic acid-acrylamide copolymer. Further, more preferably, it is a partial hydrolyzate of polyacrylamide, and has a molecular weight of 10 to 15 million, and a molecular weight of 10 to 40.
Those having a hydrolysis ratio of mol% are used.

The admixture may be in the form of solid particles, powder, or an aqueous solution. The above-mentioned admixture is added at a ratio of 0.0005 to 0.01% by weight, preferably 0.001 to 0.005% by weight, as a powder (dry) with respect to cement used as a raw material for concrete. Is appropriate. If the amount exceeds 0.01% by weight, the resulting molded product may have insufficient strength. If the amount is less than 0.001% by weight, a sufficient use effect may not be exhibited.

The cement component whose particle size and content have been adjusted as described above and a gypsum component together with an admixture exhibit remarkably good performance. However, the admixture is used when kneading concrete. May be added directly into the mixing water, or may be added during the mixing of the concrete. Further, during centrifugal force molding, a concrete molded product having sufficient performance can be obtained by mixing by spraying or spraying a predetermined amount of an admixture solution with concrete using cement having an adjusted particle size. Can be.

Up to now, it has been possible to reduce the sludge by using a variety of ordinary cements and gypsums generally available on the market in combination with an admixture, but the content of fine particles contained in the cement is reduced. Due to the large amount, there is a disadvantage that a large amount of paste remains on the inner surface and the compacted state deteriorates. For this reason, it cannot be used for manufacturing a fume tube in which the finished state of the inner surface is emphasized. In the present invention, by using a centrifugal molding cement in which the amount of fine powder and coarse powder in the cement is reduced and an admixture having an action of sticking sludge to the inner surface, the molding (pipe making) time is made longer than usual. The present invention has succeeded in shortening, improving the inner surface condition and strength development, and preventing the generation of sludge.

As a centrifugal force forming method for producing the concrete molded product of the present invention, a method of embedding concrete in a rotary mold and performing centrifugal compaction can be used. In particular, it is preferable to use the above method for manufacturing a fume tube.

[0029]

The present invention will be described in more detail with reference to the following examples, but the scope of the present invention is not limited by these examples.

Examples 1-2 and Comparative Examples 1-2 The composition of the concrete used in Examples 1-2 and Comparative Examples 1-2 was as described in Table 1.

[0031]

[Table 1]

In Table 1, mountain sand from Kashima was used as fine aggregate and crushed stone from Iwase (maximum size 13 mm) as coarse aggregate.
Was used. The cement clinkers of Examples 1 and 2 and Comparative Examples 1 and 2 were adjusted in advance so as to have a particle size distribution shown in Table 2. Gypsum dihydrate (fineness: 5000 cm ² / g) is added to the cement clinker after the particle size distribution is adjusted.
Was added in an amount of 1.1 to 1.5% by weight in terms of SO ₃ .

As the cement of Comparative Example 1, commercially available ordinary Portland cement was used. In addition, a calcium sulfoaluminate-based admixture was used as the expanding material. Using these materials, a concrete slump was blended to be 4 to 8 cm, and kneaded with a forced stirring mixer for 120 seconds. The slump of the obtained kneaded material was measured. The results are shown in Table 2.

In each of the examples and comparative examples, 15 kg of the kneaded material was put into a cylindrical test centrifugal force forming frame having an inner diameter of 200 mm, a length of 300 mm, and a thickness of 40 mm.
Centrifugal force molding was performed for 3 minutes at a medium speed of 10 G for 2 minutes and at a high speed of 35 G for 2 minutes. Here, when the admixture is added, after the medium-speed molding is completed, the molding is temporarily stopped, and an admixture composed of a polyacrylamide partial hydrolyzate (molecular weight: 15,000,000, hydrolysis ratio: 20 mol%) is added. , 0.2% containing 0.004% by weight (solid content) based on the amount of cement
Added as an aqueous solution.

Thereafter, the slag discharged at the end of molding was collected, dried and solidified at 110 ° C., and the amount of sludge in the slag was measured. The amount of sludge and the amount of water in the slag were shown as values converted to the amount per unit volume of fresh concrete charged at the time of preparing the test piece. Further, in order to check the compacted state of the inner surface, the thickness of the soft paste layer adhering to the inner surface of the test sample after centrifugal force molding was measured.

After the molded body was placed at 20 ° C. for 2 hours after the centrifugal force forming, the molded body was placed in a steam-cured layer, heated at a rate of 20 ° C. per hour, and reached 65 ° C., and then at this temperature for 3 hours. And then naturally cooled to room temperature. Further, the compression strength of the thus obtained molded body was determined by JI
Measured according to SA1136.

Table 2 also shows the thickness of the paste layer adhered to the inner surface of the molded product, the amount of discharged sludge, the water-to-binder ratio of the concrete molded product after centrifugal molding, and the compressive strength after steam curing.
Table 2 also shows Comparative Examples 1 and 2 for comparison.
In these comparative examples, the formulations and materials were all the same as in Examples 1 to 2.
The same one was used. Further, each measured value was obtained by the same test as in Examples 1 and 2.

[0038]

[Table 2]

As shown in Table 2, when the comparison was made without the admixture, in Comparative Example 1, the amount of sludge discharged after centrifugal force molding was 24.9 with respect to 1 m ^{3 of the} molded concrete.
kg, and the thickness of the inner surface adhered paste layer was 4 mm. In Examples 1 and 2, the amount of sludge discharged was 3.7 to 5.1 kg.
It was confirmed that the paste layer thickness was 0 mm, the rate of reduction of the amount of discharged sludge was extremely large, 79.5 to 85.1%, as compared with Comparative Example 1, and the state of compaction of the inner surface was also very good. Was. In Examples 1 and 2, the amount of discharged sludge was reduced to 0 by adding the admixture (polymer compound), but in Comparative Examples 1 and 2, the thickness of the inner surface attached paste layer was changed by adding the admixture. And the water-binder ratio after centrifugal force forming increased, and the steam-curing compressive strength of the tube also decreased.

Examples 3 to 7 and Comparative Example 3 Next, Table 3 shows the results obtained by using the cement of Example 2 and changing the amount of the polymer compound added under the same molding conditions. That is, in Examples 3 to 7, the polyacrylamide partial hydrolyzate (molecular weight: 15,000,000, hydrolysis rate: 2
0 mol%). In the case where the addition amount is 0.0005 to 0.01% by weight based on the cement weight, in Example 3, the addition amount is slightly excessive and the dehydration property is reduced,
The steam curing strength decreased slightly. In Example 7, a small amount of sludge was generated because the amount of addition was too small. Therefore, the addition amount of the admixture is 0.0005 with respect to the cement amount.
To 0.01% by weight, preferably 0.001 to 0.005
%. Comparative Example 3 is a comparative example in which no admixture (polymer compound) was added.

[0041]

[Table 3]

[0042] In each of Examples 8-9 Examples 8 and 9 were subjected to the same procedure as in Example 2. However, the molecular weight of the polyacrylamide partial hydrolyzate (hydrolysis ratio: 20 mol%) used as an admixture was 5,000,000 (Example 8) and 10,000,000 (Example 9). Table 4 shows the test results. Comparing Examples 8 and 9, and Example 2 (adding an admixture), the molecular weight of the polyacrylamide partial hydrolyzate is preferably from 10,000,000 to 15,000,000 in order to prevent sludge formation. I think that the.

[0043]

[Table 4]

[0044]

As described above, the cement for centrifugal force forming of the present invention can eliminate the solid content in the discharged slurry when the admixture is used in combination with the cement for centrifugal force forming of concrete. The cost of sludge disposal can be significantly reduced. In addition, when a pipe is manufactured by this method, the fine powder of cement adheres to the inner surface of the tube very little, and the inner surface condition after molding is improved. Furthermore, since the compact is compacted in a short time, the molding time can be shortened, and the manufacturing cost can be reduced. In addition, by improving the dewatering property during centrifugal force molding, the compact can be made denser, its strength can be increased compared to conventional products, and the occurrence of floating can be prevented, so that the quality of the product can be significantly improved. it can.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C04B 22:14 24:38 24:26 24:30 24:32 24:26) 103: 44 111: 56 (72) Inventor Ono Akira 585 Tomicho, Funabashi-shi, Chiba Sumitomo Cement Co., Ltd., Central Research Laboratory (72) Inventor Yuka Bream 585, Tomicho-cho, Funabashi-shi, Chiba Sumitomo Cement Co., Ltd. Central Research Laboratory (72) Inventor Takeshi Kuninishi Chiba Prefecture 585 Tomimachi, Funabashi City Sumitomo Cement Co., Ltd. Central Research Laboratory (56) References JP-A-4-202036 (JP, A) JP-A-5-301748 (JP, A) JP-A-62-278152 (JP, A) (58) Field surveyed (Int. Cl. ⁶ , DB name) C04B 7/02 C04B 28/04 C04B 24/26 C04B 24/30 C04B 24/32 C04B 24/38 B28B 21/30 B28B 1/20

Claims (9)

(57) [Claims] 1. A first cement particle component having a particle size of less than 5 μm and having a volume content of 20% or less, and a first cement particle component having a particle size of 5 μm or more and less than 11 μm and having a volume content of 35% or less. The second cement particle component, 11 μm or more, 22
a third cement particle component having a particle size of less than μm and a volume content of 35% or more;
a fourth cement particle component having a particle size of less than 30 m and a volume content of 30% or less;
No. 5 having a particle size of not more than 5% and a volume content of not more than 5%
A centrifugal molding cement composition comprising a cement particle component and gypsum, wherein the content of the gypsum is 1.5% by weight or less in terms of SO ₃ . 2. A first cement particle component having a particle size of less than 5 μm and having a volume content of 20% or less, and having a particle size of 5 μm or more and less than 11 μm and having a volume content of 35% or less. The second cement particle component, 11 μm or more, 22
a third cement particle component having a particle size of less than μm and a volume content of 35% or more;
a fourth cement particle component having a particle size of less than 30 m and a volume content of 30% or less;
No. 5 having a particle size of not more than 5% and a volume content of not more than 5%
A centrifuge comprising a cement particle component, a gypsum, and an admixture comprising a water-soluble polymer material, and a gypsum content of 1.5% by weight or less in terms of SO _3. Cement for force forming. 3. The method according to claim 1, wherein the admixture comprising the water-soluble polymer material is 0.0005 with respect to the total weight of the cement component.
The centrifugal force forming cement composition according to claim 2, which is contained in an amount of -0.01% by weight. 4. The water-soluble polymer material is carboxymethylcellulose, methylcellulose, water-soluble urea-formaldehyde condensate, polyethylene glycol, polyethylene oxide, polyacrylic acid and its derivatives and copolymers, polyacrylamide and its derivatives and copolymers. The cement composition for centrifugal force molding according to claim 2, wherein the cement composition is selected from a coalesced product and an acrylic acid-acrylamide copolymer. 5. The centrifugal molding cement composition according to claim 2, wherein the water-soluble polymer material is selected from a hydrolyzate of polyacrylamide. 6. The polyacrylamide hydrolyzate is 1
The cement composition for centrifugal molding according to claim 5, which has a molecular weight of 10,000,000 to 15,000,000. 7. A method for producing a concrete molded product by a centrifugal force forming method using the centrifugal force forming cement according to any one of claims 1 to 6. 8. A molded concrete product produced by the method according to claim 7. 9. A concrete fume tube manufactured by the method according to claim 7.