JPH092853A - Slag-reducing agent and production of centrifugally formed article using the material - Google Patents

Abstract

PURPOSE: To efficiently defoam a centrifugally formed article by using a slag- reducing agent containing bentonite, silica fume and/or fly ash fume and a defoaming agent as main components. CONSTITUTION: The objective slag-reducing agent is composed of <=20kg (based on 1m<3> of concrete) of bentonite which is a kind of clay mineral composed mainly of montmorillonite and having a swelling degree of >=5 by A.C.C method, <=50kg (in the case of using as a single component) or <=30kg (in the case of using in combination with bentonite) (based on 1m<3> of concrete) of superfine silica fume having a surface area of 150,000-3,000,000cm<2> /g or superfine fly ash fume having a surface area of 300,000-700,000cm<2> /g and >=1g (based on 1m<3> of concrete) of a defoaming agent such as a long-chain alcohol stable to the alkali in concrete. The slag-reducing agent is added in the kneading of mortar or concrete preferably in the form of a slurry prepared by using the kneading water, etc. The kneaded mortar, etc., is centrifugally formed to obtain a highly defoamed centrifugally formed article.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a material for reducing slag during the production of centrifugal compacts, and more specifically, concrete piles, poles, and concrete piles produced by centrifugally forming mortar or concrete.
The present invention relates to a steel pipe composite pile, a steel pipe lining, and a slag reducing material for reducing slag, such as a fume pipe, and a method for manufacturing a centrifugal force molded body using the same.

[0002]

2. Description of the Related Art Conventionally, concrete products manufactured by centrifugal force forming such as piles and poles have a slag due to centrifugal force. Since this slag is a strong alkaline sludge containing 20 to 40% by weight of fine powder such as cement and sand, it cannot be discarded as it is outside the factory in order to prevent pollution. After that, the supernatant liquid is neutralized and drained, and the precipitate is discarded as industrial waste, which requires a lot of time and cost. In order to reduce the occurrence of this slag,
The present inventors have proposed a noro reduction material containing bentonite as a main component, a centrifugal force molded body using the same, a method for manufacturing the same, and the like (Japanese Patent Laid-Open No. 3-247543). Further, JP-A-2-28533 proposes a method of manufacturing a concrete column by centrifugal force using silica fume for the purpose of reducing slag. In addition, Japanese Unexamined Patent Application Publication No.
Japanese Patent No. 44053 also proposes a method for producing a centrifugal force molded body for the purpose of reducing slag using a combination of silica fume, bentonite and an AE agent. However, when using bentonite, silica fume, or fly ash fume having a surface area equal to or greater than that of silica fume, to reduce slag, the concrete with these additions loses its viscosity and becomes plastic and its water retention capacity is enhanced. In order to exert the effect of reducing slag, the air entrained when concrete is put into the form is not limited to the filling type and the pumping type, and it cannot be removed by centrifugal force forming on the inner surface of the centrifugal force forming body. As a result, a large amount of them are gathered, resulting in a problem that the appearance is deteriorated and the strength is also reduced. Such a tendency is that the amount of unit cement in concrete is extremely small, aggregates with small water retention such as crushed sand are used, and the concrete slump is large due to pumping etc. into the formwork. In this case, in order to reduce the occurrence of slag, it becomes remarkable when it is necessary to reduce the high speed GNo. In addition, in the method for producing a centrifugal force molded body in which the AE agent is added to reduce the occurrence of slag, air bubbles entrained by the AE agent collect on the inner surface and are deposited in the shape of a shaving cream, which promotes the slag reduction effect, but the strength is increased. Will be reduced. The entrained air is entrained with small air bubbles of about 200 μm or less or a surfactant such as a water reducing agent which is entrained by the AE agent during kneading.
Rather than air bubbles of around μm, hard concrete in the case of the filling type is a large air bubble of several mm to several cm that enters the gap between concrete and concrete at the time of concrete injection, and in the case of soft pumped concrete, the pump uses concrete When it is sucked in or rotated at low speed, the concrete will be in a state of being mixed once,
It is a large air bubble that is sucked together at this time.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a new slag reducing material that solves the above problems, and a method for manufacturing a centrifugal force molded body using the same.

[0004]

SUMMARY OF THE INVENTION The present invention will be described in brief. The present invention is directed to the production of a centrifugal force molded article containing one or more of bentonite, silica fume, and fly ash fume and an antifoaming agent as main components. The present invention relates to a slag reducing material and a method for manufacturing a centrifugal force molded body using the same.

As a result of intensive studies aimed at solving the above-mentioned problems, the present inventors have found that defoaming can be efficiently performed by using a small amount of an antifoaming agent together, and the present invention is completed. I arrived.

Hereinafter, the present invention will be described in detail. Bentonite according to the present invention is a kind of clay mineral containing montmorillonite as a main component and has swelling property. Although the swelling property of bentonite differs depending on the place of production and the ore deposit, it is preferable that the degree of swelling is large from the viewpoint of the slag reduction effect. C. C. The swelling degree by the method [American Colloid Company standard] is 5
The above is used, usually, 10 or more is preferable, and 20 or more is more preferable. Further, in the present invention, the amount of bentonite used is such that the larger the degree of swelling of bentonite, the smaller the effect of reducing slag, and the more water, or water and a water-reducing agent, rather than added in the powder state. It is more effective to reduce the amount of slag when used as a slurry, but usually, bentonite is 20 k in 1 m ³ of concrete.
g or less is preferable, more preferably 15 kg or less, and further considering the effect of reducing slag, securing strength and economical efficiency, 1 to
12 kg is most preferred. In 1 m ³ of concrete,
If bentonite is used in an amount exceeding 20 kg, the unit water amount becomes too large even if the degree of swelling is small, and the strength decrease tends to increase. If the amount of water reducing agent is increased and the water-cement ratio is decreased so as not to decrease the strength, However, the viscosity of the water reducing agent peculiarly appears in the concrete itself, and the slag reducing effect is completely lost. If it is less than 1 kg, the degree of swelling is large, and even if it is used in a slurry, a practical effect of reducing slag cannot be obtained so much.

Further, the silica fume according to the present invention has a surface area of 150,000 to 50% as a main component, which is amorphous silica generated as ash when a ferrosilicon alloy, calcium silicon or metallic silicon is produced in an electric furnace.
Ultra fine powder of 3,000,000 cm ² / g, fly ash fume is ash collected from a pulverized coal-fired thermal power plant, and further has a surface area of 300,000 to 700, which is collected by vaporizing the ash at a high temperature. 1,000 cm ² /
g of ultrafine powder. When used in combination with bentonite, the amount of silica fume or fly ash fume used is preferably 30 kg or less in 1 m ³ of concrete, more preferably 5 to 15 kg / m ³ . Also,
When used alone, 50 kg / m ³ or less is preferable,
It is more preferably 8 to 40 kg / m ³ . 5 kg / m
^If it is less than ³ , the effect of promoting slag prevention is small even when used in combination with bentonite, and even if it is added alone in excess of 50 kg / m ³ , the effect of slag prevention does not increase and it becomes uneconomical.

As the defoaming agent used in the present invention, generally, it can be used irrespective of its kind and component as long as it is stable against the alkali of concrete. For example, long chain alcohols, fatty acid esters, metal soaps, silicones and the like. Examples of commercially available products include San Nopco's trade name “SN deformer 157”, “SN deformer 11-P”, and “SN deformer 14-H”.
"P", "SN deformer 24-FP", "SN deformer 15-P", "Nopco PD # 1", "Nopco 80"
34 ”and the like, but are not limited thereto. The amount of defoamer used is 1 in 1 m ³ of concrete.
The amount is preferably g or more, more preferably 4 g or more, still more preferably 8 to 100 g.

Further, the anti-lorosing material of the present invention is added when kneading mortar or concrete, and the kneading method may be a commonly used method. And, the addition method of the slag reducing agent of the present invention is not particularly limited, but as described above, it may be added together when mixing the concrete as powder as it is, or in a part or the whole amount of the mixing water. It may be suspended and made into a slurry form, and further charged, and further, it may be suspended and put in a part or the whole amount of water mixed with the water reducing agent. It is particularly preferable to add the slurry because the effect of preventing slag is exhibited in a smaller amount when the material is suspended and made into a slurry rather than in the powder state. Regarding the timing of addition, in the kneading method in which the water reducing agent is added afterwards, it is more effective to add the water reducing agent after adding the water reducing agent, even if the mixing time is shorter, and the effect of preventing slag is greater. In the kneading and mixing method in which the above are added at the same time, it is preferable to add them together with other concrete materials.

In the centrifugal force molding method of the present invention, a conventional method is used which is performed in 3 to 5 stages using low speed (low speed I, low speed II), medium speed (medium speed I, medium speed II) and high speed. , Not limited. The low speed G No. is the concrete to which the slag reducing agent of the present invention is added becomes a plastic, so in order to improve the axial extension, especially in the case of a low slump such as a built-in type, a low speed is used to prevent jumpers. 3 G or less is preferable, and the low speed rotation time is preferably 1 minute or more, and most preferably 2 to 6 minutes. Medium speed is medium speed I and medium speed II
In the case of adding 4 to 4 stages in total, the medium speed I is 0.5 to 4 to 8 G in order to make the centrifugal force molded body have a uniform thickness.
More than a minute, then medium speed II (medium II in the three-stage molding method)
Is a medium speed), in order to arrange aggregates in the circumferential direction and prepare for expelling air bubbles, it is 12 to 20G when the slump is lower than 5 cm, and the slump exceeds 5 cm. With pumping, 0.5 at 8-15G
It is preferable to carry out for 1 minute or more, more preferably for 1 minute or more,
It is most preferable to perform the treatment for 2 to 5 minutes from the viewpoint of defoaming. At high speeds, there is no slag and the tightness is good so that it does not fall off due to the impact during transportation etc. In order to perform defoaming efficiently, it is related to the rotation time rather than the size of GNo.
Minutes or more, preferably 2 minutes or more are required. If it is less than 1 minute, the defoaming effect is not sufficiently exhibited even if the tightness is good, which is not preferable.

The cement used in the present invention is usually early strength, medium heat Portland cement and mixed cement such as blast furnace, silica and fly ash cement, alumina cement, cement mixed with blast furnace slag in accordance with JIS standards or the like. It is preferable to use a high-strength admixture mainly composed of gypsum or a cement expansive material that is used to improve the bond strength between steel pipe and concrete. It is essential from the perspective of getting.

The use of a gypsum-based high-strength admixture or cement expansive material is preferable because it promotes prevention of slag.
On the other hand, it is more difficult to defoam, so it is more preferable to use it in combination with an antifoaming agent, and the defoaming agent does not have any adverse effect on the performance of the admixture or the like, and on the contrary, it has an adverse effect on the defoaming effect of the admixture or defoaming agent. Not give at all.

[0013]

EXAMPLES The present invention will now be described in detail with reference to examples, but the present invention is not limited to these examples.

Examples 1 to 2 Based on the concrete composition of Table 1, one or more kinds of crushed sand, crushed stone, cement + bentonite, silica fume, and fly ash fume (hereinafter referred to as bentonite, etc.) + A defoaming agent is planeted. The mold was put into a mixer having a capacity of 100 liters, stirred dry for 20 seconds, added with an aqueous solution in which a water reducing agent was dissolved in kneading water, and kneaded for 90 seconds to prepare 40 liters of concrete.
Slump was measured.

[0015]

[Table 1]

<Materials used> Cement: Normal Portland cement manufactured by Denki Kagaku Kogyo Co., Ltd. Sand: Himekawa Niigata Prefecture crushed sand Specific gravity 2.64 Crushed stone: Crushed stone specific gravity 2.64 Water reducing agent: Main component polyalkylaryl sulfonate System, powder a. Bentonite: Swelling degree 30 (A.C.C. method) b. Silica fume: Surface area of 2,500,000 cm ² / g (BET method) c. Fly ash fume: Surface area 2,500,000 cm ² / g (BET method) d. Defoaming agent: San Nopco Ltd. product name "SN Deformer 157" liquid

18 kg of the produced concrete is put into a mold and subjected to centrifugal force forming to prepare a centrifugal force forming specimen having an outer diameter of 20 × length 30 × thickness of 5 cm, and the centrifugal force forming is performed every hour. Then, the bubbles on the inner surface were observed. The results are shown in Tables 2 and 3. The amount of the water reducing agent was arbitrarily changed depending on the amount of bentonite or the like added so that a prescribed slump was produced, but it is omitted in Tables 2 and 3.

[0018]

[Table 2]

(Note) X: many bubbles, Δ: few bubbles, ◯: no bubbles, ▲: no slag, ×, △, ◯: no slag defoamer: 1 m ³ of concrete Blending amount (g) -Noro is a soft cement paste-like material, has no force to stick to the inner surface, and has a paste layer dropped.

[0020]

[Table 3]

(Note) X: many bubbles, Δ: few bubbles, ◯: no bubbles, ▲: no slag, ×, △, ◯: no slag ・ Antifoaming agent: to 1 m ³ of concrete Compounding amount (g) It is a cement paste type and has no force to stick to the inner surface.
The paste layer is dropped.

From Table 2, the use of the defoaming agent of the present invention makes the defoaming effect on the inner surface of the centrifugal force molding remarkable,
It is shown that the defoamer itself does not have any adverse effect on the slag reducing effect. Further, the defoaming effect is exhibited by adding the defoaming agent in an amount of 1 g / m ³ or more, becomes more remarkable in the addition of 4 g / m ³ or more, and the effect does not change even if 100 g / m ^{3 is} added. Shown. Table 3 shows that the increase in the amount of bentonite or the like causes a remarkable effect of reducing slag.

Example 3 Experiment No. A commercially available gypsum-based high-strength admixture and an expansive material were added in place of sand to the concretes 1-1 and 1-5, and the same test as in Example 1 was performed. In addition to the observation of the defoamed state by the centrifugal force molded body, a centrifugal force molded specimen (outer diameter 20 × length 30 × thickness 5 cm) (for age 7 days) was rotated for 2 minutes for the compression strength test. Specimens and φ10 × 20cm specimens, uniaxially restrained 10 × 10 × 40 for measuring expansion coefficient
cm specimens were prepared, and after 4 hours of pre-incubation, 20 ° C /
The temperature was raised to 75 ° C. for 4 hours, the steam valve was stopped, and the mixture was naturally cooled until the next day. Then, on the next day, the 1-day compressive strength after demolding, the restraint expansion rate, and the indoor air-drying curing 7
The compressive strength and the expansion coefficient after day were measured. The results are shown in Table 4. Note that the experiment No. Nos. 3-1 and 3-3 were obtained by adding only the high-strength admixture to cement, and adding 10% by weight to the cement.
In 3-2 and 3-4, 7% by weight of each of the high-strength admixture and the expansive material was added. <Measurement method> -Compressive strength: Compliant with JIS A1108-Expansion rate: Compliant with JIS A6202 B method

[0024]

[Table 4]

(Note) Gypsum-based high-strength admixture: Denka Kagaku Kogyo Co., Ltd., trade name “Denka Σ1000” Expansion material: Same as above “Denka CSA” x: many bubbles, Δ: few bubbles, ◯: bubbles No ▲: No slag, ×, △, ◯: No slag *: Centrifugal molding specimen

From Table 4, the defoaming effect of the defoaming agent of the present invention is not adversely affected even when it is added together with the high-strength admixture or the expanding agent, and conversely, the defoaming agent of the high-strength admixture or the expanding agent is not affected. It is shown that the performance is not adversely affected.

[0027]

EFFECTS OF THE INVENTION By using the slag reducing material of the present invention, defoaming can be performed in a short time during the production of a centrifugal force molded body, the slag preventing effect can be surely achieved, and the strength is not reduced. It is possible to manufacture piles and the like. Furthermore, the power cost can be reduced and the generation of slag that is discarded as industrial waste can be prevented, which is useful for pollution prevention and environmental conservation.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Moriyama et al. 2209 Aomi, Aomi-cho, Nishikubiki-gun, Niigata Prefecture Aomi Plant, Denki Kagaku Kogyo Co., Ltd. (72) Inventor Junichi Tsurumaki 106 Someya, Sakai-machi, Sarushima-gun, Ibaraki Prefecture Asahi Kasei Kogyo Co., Ltd.

Claims (2)

[Claims] 1. A slag reducing material for producing a centrifugal force molded body, which comprises one or more of bentonite, silica fume, and fly ash fume and an antifoaming agent as a main component. 2. A method for manufacturing a centrifugal force molded body, which comprises using the slag reducing material according to claim 1.