JPH10230507A - Manufacture of centrifugally molded article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain productivity even when molding is performed under high speed centrifugal force, prevent limewash from developing, and realize the revelation of high strength by a method wherein a concrete kneaded matter, which includes specified amounts of acid clay and of water-soluble polymeric substance and the slump of which lies within a specified range, is centrifugally molded. SOLUTION: A concrete kneaded matter, which includes 2.5-10kg/m<3> of acid clay and 0.01-0.2kg/m<3> of water soluble polymeric substance having a thickening action and the slump of which is 13.0cm or less, is centrifugally molded. The acid clay is mainly made of aluminum silicate. The acid clay employed is made of montmorilonite as its major mineral. As the water soluble polymeric substance having a thickening action, an acrylic amide-based compound such as polyacrylic amide, polymethacrylic amide or the like, a cellulose-based compound such as methyl cellulose, carboxy methyl cellulose, hydroxy ethyl cellulose or the like and microbial fermented polysaccharides are employed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a centrifugally molded product, and more particularly to a concrete molding such as a pole, a pile, a hume tube, a steel tube composite pile, etc., which is manufactured using a centrifugal force. The present invention relates to a method for manufacturing a product.

[0002]

2. Description of the Related Art When a concrete kneaded product is formed by centrifugal force by this kind of manufacturing method, slag occurs. Since the slag exhibits strong alkalinity and cannot be discarded, the use of an admixture has been proposed as one method for reducing the slag. The admixture includes those composed of an organic substance and those composed of a combination of an inorganic substance and an organic substance. For example, Japanese Patent Application Laid-Open No.
Japanese Patent Publication No. 201649, and the latter, JP-A-5-105496.

The above-mentioned Japanese Patent Application Laid-Open No. 61-201649 (Examples,
(See Table 2), the slump range is 3.0-4.0cm and
When forming a concrete tube from a concrete kneaded material of 8.0 to 10.5 cm with a centrifugal force of 15 G or 30 G, a cellulosic compound and / or a polyacrylamide compound as an admixture are added to the raw material (0.1 to 0.1 cm). 2.0 kg / m ³ ) to reduce the generation of slag. As such compounds, in the cellulose system, hydroxyethyl cellulose, carboxymethyl cellulose, methyl cellulose are exemplified.
In the case of polyacrylamides, there are many so-called water-soluble polymer substances such as polyacrylamide and polymethacrylamide.

Japanese Patent Application Laid-Open No. 5-105496 discloses a slag reducing agent for centrifugal molding containing a water-soluble polymer (polyacrylamide, starches, etc.) and bentonite (Note). Their usage is 0.5 kg /
m ³ or less and the latter less than 10 kg / m ³ . When a slump 6 ± 2 cm concrete kneaded product obtained by kneading the reducing agent with the raw material composition was molded with a centrifugal force of 35 G, generation of slag could be reduced and strength was not reduced (see Example 1). In addition, water was added to the composition to make slump 10 ± 2 cm, making it easy to generate slag, and even when molded with 40 G centrifugal force, the slag reduction effect was obtained stably and it was not affected by slump fluctuation. (See Example 3). (Note) Swelling degree of 5 to 4 with montmorillonite as the main component
Commercial products of about 0.

[0005]

In the above prior art, when only a water-soluble polymer substance is added, the viscosity of the concrete kneaded material increases with an increase in the amount of addition, due to the thickening action of the polymer substance. There are advantages such as prevention of slag at the time of centrifugal force forming and improvement of material separation. On the other hand, compared to the case of no addition, the viscosity of the kneaded material becomes higher, and the load on the power source (motor) of the mixer increases. The amount of kneading had to be reduced.

The admixture using a water-soluble polymer and bentonite in combination has an effect that the swelling property of bentonite more reliably prevents the generation of slag. But,
The use of bentonite required increasing the unit water volume to maintain the set slump of the concrete mixture. As a result, there is a disadvantage in that the thickening effect, which is an advantage of the water-soluble polymer substance, is reduced.

As described above, when only a water-soluble polymer substance is added, the kneading amount of the concrete kneaded material is reduced based on the increase in viscosity, which leads to an increase in cost (that is, a decrease in productivity). Also, the combined use of bentonite and a water-soluble polymer substance has a problem that an increase in the unit water amount due to the use of bentonite reduces the thickening effect of the water-soluble polymer substance and causes a decrease in compressive strength.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems and disadvantages, and has an object to maintain productivity even when molding with a high-speed centrifugal force of 35 G or more and to prevent slag from being generated. Another object of the present invention is to provide a method for producing a centrifugally molded product capable of exhibiting high strength (at least 60 N / mm ² ).

[0009]

SUMMARY OF THE INVENTION The present invention is characterized in that a concrete kneaded material in a specific slump range containing a specific amount of acid clay and a water-soluble polymer substance is prepared and subjected to centrifugal molding. Accordingly, the present invention provides a method for producing a target centrifugal molded article as described above without impairing the effect of adding a water-soluble polymer substance used in combination like the bentonite.

[0010] That is, the present invention relates to "acid clay of 2.5 to 1
0 kg / m ³ and 0.01 water-soluble polymeric substance having a thickening effect
A method for producing a centrifugally molded product, wherein a concrete kneaded material having a slump of 13.0 cm or less and containing 0.2 kg / m ³ is centrifugally molded. (Claim 1). Further, the water-soluble polymer substance is "polyacrylamide and / or microorganism-fermented polysaccharide" (claim 2).

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The method for producing a centrifugal molded product according to the present invention is characterized in that
This method is applied to the production of concrete molded products using centrifugal force such as pipes, piles, etc., especially when the kneaded concrete is subjected to high-speed centrifugal force of 35G or more without lowering the productivity. Further, molding can be performed without generation of slag. (The applicant of the present invention has reported that a concrete kneaded material having a slump of 13 cm or less containing only an acid clay as an admixture is used.
A patent application containing the invention of a manufacturing method for molding by centrifugal force of G was filed earlier (Japanese Patent Application No. 8-309616), but the present invention
Productivity is maintained even in molding with high-speed centrifugal force of 5G or more, without generating slag, enabling the development of compressive strength of 60 N / mm ² or more, that is, the invention is improved and the applicable range is expanded. It is. )

The present invention is applied to a centrifugal molded product of a concrete kneaded material having a slump of 13.0 cm or less. If the slump of the kneaded product exceeds 13.0 cm, even if it contains acidic clay and a water-soluble polymer substance, slag occurs, the strength is significantly reduced, and the effect of the inclusion is not produced. The above-mentioned "concrete kneaded material having a slump of 13.0 cm or less" means a slump of a kneaded material obtained by kneading a common concrete raw material and the acid clay and the water-soluble polymer used together in the present invention is 13.0 cm. It means the following. (In addition, when the concrete kneaded material is pumped by pump, slump 3.0cm
The above can be transported smoothly. )

The acid clay used in the present invention mainly consists of aluminum silicate, and the main mineral is montmorillonite. The fineness of commercially available acid clay is roughly 4,
000 to 19,000 cm ² / g, but in the present invention, 5,000 to 15,000
Those having 0 cm ² / g are preferred.

Usually, when the acid clay is dispersed in water to form a suspension, it exhibits a wide range of pH values from acidic (about pH 5) to alkaline (about pH 9) due to differences in the place of production and ore veins. Any pH value can be used. Further, since the amount of the acid clay is small, the inhibition of the hydration reaction of the cement and the corrosion of the reinforcing steel are negligible in practical use. In the present invention, two or more kinds of acid clay having different pH values can be used in combination.

When the acid clay is dispersed in water,
Usually, it swells somewhat by absorbing and adsorbing water. Its swelling degree
(Note) is significantly smaller than the degree of swelling of bentonite (5-40), most of which are 1 or less (sometimes about 3)
Therefore, even if the prescribed amount of acidic whiteness is blended, the unit water amount is not corrected, the strength is not reduced by water absorption, or the thickening effect of the water-soluble polymer substance is not affected. (Note) American Colloid Campany standard.

The amount of the acid clay is 2.5 to 10 kg / m ³ . A preferred range is 3.5-8.5 kg / m ³ , particularly preferred is 4.0-7.5 kg / m ³ . If the compounding amount is less than 2.5 kg / m ³ , when molded by high-speed centrifugal force (35 G or more), stickiness occurs, which is not preferable. On the other hand, if it exceeds 10 kg / m ³ , the unit water volume becomes extremely large, and the compressive strength decreases, which is also not preferable.

Examples of the water-soluble polymer substance having a thickening action used in the present invention include commercially available acrylamide compounds such as polyacrylamide and polymethacrylamide, methylcellulose and carboxymethylcellulose.
And cellulosic compounds such as hydroxyethylcellulose and microbial fermented polysaccharides (Note). The water-soluble polymer substance may be used in combination of two or more kinds. In the present invention, a preferred water-soluble polymer substance is polyacrylamide and / or a microbial fermentation polysaccharide. (Note): For example, there is a dry powder (eg, welan gum) obtained by fermenting with ATTC 31555 cells of Alcaligenes strain using glucose as a medium and purifying microbial polysaccharides produced outside the cells.

The compounding amount of the water-soluble polymer substance is 0.01 to
It is 0.2kg / m ^3. Preferred range is 0.015~0.1kg / m ^3, particularly preferred is 0.02~0.05kg / m ^3. If the compounding amount is less than 0.01 kg / m ³ , when molded by high-speed centrifugal force (35 G or more), stickiness is generated, which is not preferable. On the other hand, 0.
If more than 2 kg / m ^3, concrete - for bets kneaded product becomes extremely high viscosity, reduction of the kneading volume, that is, the amount of production is reduced, the cost also increases (i.e., decrease in productivity), so
Not preferred. When two or more water-soluble polymer substances are used in combination, the total amount must be within the above range.

A method for producing a concrete kneaded product by mixing and kneading predetermined amounts of the above-mentioned acidic clay and the water-soluble polymer substance is as follows: a mixture obtained by previously mixing the acid clay and the water-soluble polymer substance. Or a method in which both are separately blended with other concrete raw materials and kneaded to produce a kneaded material. The above-mentioned other concrete raw materials are kneaded in advance, and the mixture is mixed in the kneading process or the two or more are mixed. Are individually compounded, and a method of producing a kneaded material by further continuing kneading,
Conventional methods are shown. In short, it is important that the compounded acid clay and the water-soluble polymer substance are uniformly dispersed in the concrete kneaded material after the kneading is completed, and the present invention particularly limits those methods. is not.

Since the above-mentioned mixture dissolves immediately when the water-soluble polymer substance comes into contact with the kneading water, it need not necessarily be uniformly dispersed in the acid clay. The method of mixing and kneading the above-mentioned acidic clay and the water-soluble polymer substance separately with other concrete raw materials to produce a kneaded material is the shortest in kneading time, and is therefore preferable in terms of productivity.・
It is a kneading method. In this case, like the other concrete raw materials, they can be sequentially charged into the mixer,
In particular, because the amount of the water-soluble polymer compound is small,
The whole amount may be dissolved in kneading water in advance and blended.

In the centrifugal force forming method, pre-compacting is performed at low / medium speed, and then centrifugal force forming is performed at high speed. In the present invention, molding with a high-speed centrifugal force of 35 G or more was made possible by using an acid clay and a water-soluble polymer in combination. Therefore, the above-mentioned poles and piles can be formed with higher strength. Molding time at high speed is 1-5
Minutes. In addition, it is also possible to mold with a centrifugal force of 35G or less by using an acid clay and a water-soluble polymer substance together,
In that case, no slag occurs. The pre-compaction is performed at a low speed of 1-3G for 1-3 minutes, as usual, for 3-15 minutes.
G Perform at medium speed for 1-5 minutes.

The productivity of the concrete can be determined by the current value indicated by the ammeter connected to the power source of the mixer at the end of the kneading of the raw material for the concrete. Concrete
When the raw material is put into the mixer and is operated and kneaded, it shows a high current value at the start-up, but decreases rapidly as the kneading progresses, starts to rise gradually again, changes almost constant, and ends the kneading. The current value at the end is read by an ammeter.

Since the volume of the mixer to be used is constant, when the concrete raw material is quantitatively charged into the mixer and kneaded, the viscosity of the kneaded material changes with the progress of kneading. The power supplied to the power source changes in response to a change in viscosity, but under a constant voltage, the change appears as a change in current. Therefore, in the case of a highly viscous kneaded material, the load becomes large, a high current flows, and if it becomes too high, the motor
(Power source) stops or burns in some cases. In order to avoid this, it is necessary to reduce the amount of kneading, reduce the load, and reduce the current. As a result, productivity decreases.

In the present invention, the cement used is:
Normal / early high / super early / moderate heat Portland cement, and mixed cement obtained by mixing blast furnace slag, fly ash, silica, etc. with these Portland cements. The coarse aggregate, the fine aggregate, the water reducing agent (including the high-performance water reducing agent) and the like are commonly used and are not particularly limited.

In the present invention, a part of the above-mentioned various cements can be replaced by fine powder of natural or artificial minerals such as limestone, silica stone, silica fume and blast furnace slag. The replacement ratio is determined according to the characteristics required for the centrifugal molded product. Further, a swelling agent containing calcium oxide, gypsum, or the like as a main component, a strength promoter and the like can be used in combination. The method of kneading and curing the concrete is carried out according to a conventional method, and is not particularly limited in the present invention.

The acid clay and the water-soluble polymer compounded in the method for producing a centrifugal force molded product according to the present invention are mixed with a concrete product (for example,
When blended in the production of box carbonate and manhole side mass), it is effective in improving bleeding and settlement cracks.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments.
The materials used are as follows. Cement: Portland cement of early strength (Nippon Cement Co., Ltd.) Slag: Blast furnace slag (Brain 8,000 cm ² / g, "Fine Cementment" manufactured by Daiichi Cement Co., Ltd.) Fine aggregate: Crushed sand (FM; 2.81, Ome) Coarse aggregate: Crushed stone (from Ome) Water reducing agent: Naphthalenesulfonic acid (“Mighty 150” manufactured by Kao Corporation) Water: Tap water Acid clay: A-1: Brain; 12,000cm ² / g pH of suspension 8.5 (concentration 1 wt%, 20 ° C.), degree of swelling: 1 or less (“Mizukaace # 300” manufactured by Mizusawa Chemical Co., Ltd.) A-2: Brain; pH of suspension at 10,500 cm ² / g; 6.7 ( (Concentration: 1 wt%, 20 ° C), degree of swelling: 1 or less (Nikkanite A-168, manufactured by Nippon Kagaku Shirato) Water-soluble polymer: S-1: Microbial fermented polysaccharide ("Welgam", manufactured by Kelco) S -2: Methyl cellulose (Shin-Etsu Chemical Co., Ltd. “Metros”
90SH-40000 ") S-3: Polyacrylamide (manufactured by Sankyo Kasei Co., Ltd.) Bentonite: Brain; pH of 11,000 cm ² / g suspension; 9.8 (concentration 1 wt%, 20 ° C), swelling degree: 17 (Sungyo Co., Ltd., `` Sizing stamp '')

(Examples 1 to 46, Comparative Examples 1 to 13)
3 (Examples 1 to 42) and Table 4 (Comparative Examples 1 to 13), the materials were sequentially added (acid clay and water-soluble polymer substance separately) to a twin-screw stirring mixer. (0.
Was placed in 1 m ^3), and kneaded for 1.5 minutes concrete - DOO kneaded product 0.1
the m ³ was prepared. (In Comparative Examples 12 and 13, bentonite was blended in place of the acid clay.)

In Examples 43 to 46 shown in Table 3, first, the above-mentioned materials except for the acid clay and the water-soluble polymer substance were charged and kneaded into the above mixer, and after 1.5 minutes had passed, the acid clay and the water-soluble polymer were then mixed. The polymer substances were sequentially charged, and kneading was continued for 1.0 minute to prepare the same amount of concrete kneaded material.

15 kg of each kneaded material is placed in a cylindrical form (with an inner diameter of 20 kg).
× 30cm in length), 2 minutes at low speed (1G), 2 at medium speed (4G)
After compacting for 1 minute, centrifugal force molding was performed for 2 minutes under high-speed conditions (30 to 45 G) shown in Tables 1 to 4. After molding, 2
Preheated, heated to 65 ° C at a heating rate of 20 ° C / hr, steam-cured at that temperature for 4 hours, allowed to cool naturally, removed from the mold, and left in the air until the material age was 7 days. A 5 cm concrete tube was manufactured.

In Examples 31 and 32, a part of the cement was replaced with fine mineral powder (blast furnace slag). That is, Example 31 shows the unit cement amount of Example 5 and Example 32 shows the unit cement amount of Example 17, respectively.
kg / m ³ is obtained by replacing.

In the above manufacturing process and after the manufacturing, each characteristic was measured according to the following measuring methods, and the obtained results are shown in Tables 1 to 3. (1) Slump (cm): Measured according to "JIS A 1101 (Concrete slump test method)". (2) Slag amount (% by weight): After completion of molding, the amount of sludge (weight) discharged by inclining the cylindrical form was measured, and the ratio to the total weight of the concrete was calculated. (3) Compressive strength (N / mm ² ; material age 7 days): Measured according to “JIS A 1108 (Test method for compressive strength of concrete)”. (4) Current value (A): The current value indicated by the ammeter connected to the power source of the mixer at the end of kneading was used as an index indicating the viscosity of the kneaded material. (5) Centrifugal force (G): Calculated from the rotational speed of the cylindrical form (eg, 40
G; 670 rpm).

[0033]

[Table 1]

[0034]

[Table 2]

[0035]

[Table 3]

[0036]

[Table 4]

From the above Tables 1 to 4, the example of "Concrete kneaded material containing a specific amount of acid clay and a water-soluble polymer substance in a specific slump range and prepared by centrifugal force" according to the present invention is shown. In Nos. 1 to 46, the current value hardly changed, no sticking occurred, and a molded product having high compressive strength was obtained.

On the other hand, in the above-mentioned specific slump ranges, in Comparative Examples 4 to 7 in which a smaller amount of acid clay or a water-soluble polymer substance was added than the range specified in the present invention, slag occurred in all cases. Then, from Examples 2 and 14 (in the case of acid clay) and Examples 3 and 15 (in the case of water-soluble polymer substance) corresponding to them, it is possible to achieve the objectives of acid clay and water-soluble polymer substance, respectively. It was found that there was a minimum blending amount.

On the other hand, if acid clay or a water-soluble polymer substance is added in excess of the specified range, generation of slag can be prevented, but Comparative Examples 8 and 9 for acid clay are used.
In Comparative Examples 10 and 11 for the water-soluble polymer substance, it was recognized that the compressive strength was decreased, and the current value was abnormally increased in Comparative Examples 10 and 11. In Examples 8 and 20 corresponding to the acid clay, and Examples 7 and 19 relating to the water-soluble polymer substance, the current value hardly changed, no sticking occurred, and high compressive strength was exhibited. Was found, and it was found that there was an upper limit in the amount of the acid clay and the water-soluble polymer substance.

In Comparative Examples 2 and 3 performed at a slump of 14.0 cm, even when the acid clay and the water-soluble polymer were within the prescribed compounding ranges, slime was generated and the compressive strength was low, and
On the other hand, in Examples 10 and 22 performed at 12.5 cm, it was recognized that the current value hardly changed, no sticking occurred, and high compressive strength was exhibited.

When acid clay and a water-soluble polymer substance are contained in specified amounts, they can be formed by high-speed centrifugal force of 45G.
(Examples 33 and 34) or molding with a high-speed centrifugal force such as 30G (Examples 36 and 38), it was confirmed that no sticking occurred and high compressive strength was exhibited.

Further, from Examples 27 and 28,
A similar effect is produced even when acid clay having different values is used in combination, and no abnormality is observed even when a part of cement is replaced with mineral fine powder, and Examples 39 to 42
From, even if the cement is a relatively small blending amount, when the acid clay and water-soluble polymer material contained a specified amount,
No abnormalities were found.

As can be seen from Examples 43 to 46, no abnormalities were observed when the concrete raw materials other than the acid clay and the water-soluble polymer material were added and kneaded during the kneading process.

In Comparative Examples 12 and 13 in which conventional bentonite and a water-soluble polymer were combined instead of the acid clay, it was recognized that the compressive strength was reduced.

From the above, the production method of the present invention can be applied to (1) a specific slump range (2) a specific compounding range for each of the acid clay and the water-soluble polymer substance (3) Acid clay with different pH values can be used together. (4) Molding with high speed centrifugal force of 35G or more. (5) Even if the compounding amount of cement is relatively small, and even if a part of cement is replaced with fine mineral powder. No abnormalities occur (6) No abnormalities are observed even if the acid clay and water-soluble polymer are mixed in the kneading process of other raw materials. (7) Productivity is maintained (reducing the amount of kneading You do not need to do that).

Next, the case where the acid clay and the water-soluble polymer substance used in the present invention are applied to general-purpose concrete molded articles (box-carbat and manhole-side mass) which does not utilize centrifugal force. Is shown as a reference example.

(Reference Examples 1 to 6) According to the formulation shown in Table 5, the materials used in the above Examples were mixed with a forced stirring mixer.
(1.5 m ³ ) and kneaded for 1.5 minutes to prepare a concrete kneaded product.

The box kart is prepared by placing the obtained kneaded material in a “form for“ 1800 × 1800 ””, placing it for 2 hours, and then increasing the temperature to 65 ° C. at a rate of 20 ° C./hr. The manhole side mass was manufactured by warming, steam curing at that temperature for 4 hours, and naturally cooling.The manhole side lump was named “600C” standardized in “JIS A 5317 (manhole side lump for sewerage)”. "For formwork"
Thereafter, it was manufactured in the same procedure and under the same conditions as in the box carbonate.

The following characteristics were measured during the production of the box carbonate and the manhole side mass. The obtained results are also shown in Table 5. (1) Slump (cm): Same as in the above embodiment. (2) Breathing rate (% by weight): JIS A 1123 (Concrete
(Breaking test method). (3) Settlement Cracks: The box carbates were visually inspected on the inner surface of the hunt, and the manhole side mass was visually observed on the neck of the sloped wall, and the settlement cracks were evaluated as “presence or absence”.

[0050]

[Table 5]

From Table 5, it can be seen that the kneaded product containing the acid clay and the water-soluble polymer material for producing the box carbonate and the manhole side lump is also effective in improving the bleeding rate and the settlement crack. It turns out that it is effective.

[0052]

According to the present invention, as described in detail above, a concrete kneaded material containing a specific amount of acid clay and a water-soluble polymer in a specific slump range is formed by centrifugal force. Thereby, even if it is molded with a high-speed centrifugal force of 35 G or more, the productivity is maintained, no sticking is generated, and the effect of expressing high compressive strength is exhibited.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C04B 24:38)

Claims (2)

[Claims] 1. A acid clay was a water-soluble polymer having a 2.5~10kg / m ³ and Thickening 0.01~0.2kg / m ³ is contained, slump 13.0cm following concrete - the centrifugal force the door kneaded product A method for producing a centrifugal molded article, characterized by molding. 2. The method for producing a centrifugally molded article according to claim 1, wherein the water-soluble polymer substance is polyacrylamide and / or a microbial fermentation polysaccharide.