JP3454324B2 - Slag reduction material, centrifugal force molded article using the same, and method of manufacturing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a slag reducing material, a centrifugal force forming body using the same, and a method for producing the same, and more specifically, a concrete pile or pole produced by centrifugally forming mortar or concrete, Steel pipe composite pile, steel pipe lining, and a slag reducing material that reduces or prevents slag generation when manufacturing concrete products such as fume pipes,
The present invention relates to a centrifugal force molded body using the same and a manufacturing method thereof.

[0002]

2. Description of the Related Art Conventionally, concrete products manufactured by centrifugal molding such as piles and poles have a slag due to centrifugal force during molding. Since this slag is a strong alkaline slurry 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, and the solid content of the slurry was precipitated and filtered. After that, the supernatant liquid is neutralized and drained, and the precipitate is solidified and dumped as industrial waste, which requires a lot of time and cost.

In order to reduce or prevent the occurrence of this slag, the present inventor has proposed a slag reducing material in which fine silica powder and / or a clay mineral other than bentonite are used in combination with bentonite (Japanese Patent Laid-Open No. 3-247543). Japanese Patent Laid-Open No. 3-261639).

However, the slag reducing or preventing effect of these slag reducing materials is to prevent the water in the concrete from moving against the centrifugal force by strengthening the water retaining capacity of the concrete itself. If the unit amount of cement in concrete is extremely small and aggregates with small water retention such as crushed sand are used, or if the concrete slump is large due to pumping, etc. There was a problem that the effect of reducing or preventing the occurrence of the variation was small and the practical range was narrow.

Further, the concrete using these slag reducing agents tends to increase the unit water amount, and therefore the water-cement ratio of the concrete when the same slump is used is increased as compared with the case where the slag reducing agent is not used. As a result, there has been a problem that the strength of the centrifugal molded body is lowered.

The present inventor has conducted various investigations with the aim of simultaneously solving the three problems of reducing or preventing the occurrence of slag and improving the effect of reducing slag and reducing the amount of unit water. The present invention has been completed with the knowledge that the problems can be solved.

[0007]

[Means for Solving the Problems] That is, the present invention is a slag reducing material containing bentonite and a heat-treated bentonite, and a centrifugal force molding formed by molding concrete containing the slag reducing material. And a manufacturing method thereof.

The present invention will be described in detail below.

Bentonite used in the present invention is a clay mineral having a layered structure, taking in water molecules between the layers, and swelling from several times to several tens of times the original volume,
Its mineral name is montmorillonite, which is a type of smectite clay mineral. Montmorillonite is commonly called bentonite, and is called Na-type bentonite or Ca-type bentonite due to cations entering the layer, and H-type bentonite (acid clay) in which bentonite is weathered. It is possible to use one kind or two or more kinds of bentonite and synthetic bentonite.

In the present invention, these bentonites (hereinafter referred to as bentonite A) and heat-treated products thereof (hereinafter referred to as bentonite B) are used together. Bentonite A is effective for reducing or preventing slag generation. In particular, bentonite having a higher swelling property shows a reduction or prevention effect of slag generation with a smaller amount of use, but on the other hand, an increase in unit water amount tends to increase. There is. Bentonite, which has a low swelling property, needs to be used in a large amount in order to reduce or prevent the occurrence of slag, but the unit water amount tends to increase little even if the amount is large.

The swelling property of bentonite A varies depending on the place of production and the ore deposit, but the ACC method (American Colloid Camp)
The swelling degree according to any standard) is preferably 5 or more, more preferably 10 or more, and most preferably 20 or more.

The method of using the bentonite is not particularly limited, but mixing with water or a suspension with water and a water-reducing agent in the concrete causes more slag generation than mixing in powder form with the concrete. It is preferable because it exhibits a reducing or preventing effect.

The amount of bentonite A used is not particularly limited, but is usually 20 per 1 m ^{3 of} concrete.
It is preferably not more than kg, more preferably 0.3 to 15 kg, most preferably 1 to 10 kg in consideration of economic efficiency. Concrete 1
When the amount is less than 0.3 kg, the effect of reducing or preventing the occurrence of slag is small with respect to m ³ , and when the amount exceeds 20 kg, the unit water amount becomes too large and the strength decrease becomes large even if the swelling degree is small. Therefore, if too much water reducing agent is used, conversely there is a tendency for slag to occur.

Bentonite B used in the present invention has the effect of promoting the effect of reducing or preventing the generation of slag and reducing the amount of unit water. Bentonite B is a heat-treated product of Bentonite A.
There are Na-type bentonite, Ca-type bentonite, and H-type bentonite. In the case of Na-type bentonite, acid treatment is more preferable in advance.

The heat treatment temperature for producing bentonite B is preferably 400 ° C. or higher, more preferably 600 ° C. or higher,
Most preferred is a temperature range that does not melt above 800 ° C. If the heat treatment temperature is lower than 400 ° C, the unit water content tends to increase.

The amount of bentonite B used is preferably 20 kg or less, more preferably 0.2 to 15 kg, and most preferably 0.4 to 10 kg per 1 m ^{3 of} concrete, considering economic efficiency. If it is less than 0.2 kg, the water reducing effect is small, and if it exceeds 20 kg, the effect of reducing the unit water amount tends to disappear.

Further, when a concrete is kneaded with the slag reducing material of the present invention to produce a centrifugal force molded product, it is possible to use a water reducing agent together not only to compensate the strength due to the water reducing effect but also to reduce the occurrence of slag. It is preferable because it promotes the prevention effect. The water reducing agent is not particularly limited, but it is preferable to use a high performance water reducing agent.

The high-performance water-reducing agent is a water-reducing agent having a larger water-reducing rate than the conventional lignin sulfonate-based agents and the like, and commercially available high-performance water-reducing agents include polyalkylallyl sulfonate-based and aromatic The main component is any one of an amino sulfonate type, a melamine formalin resin sulfonate type, and a polycarboxylic acid salt type, and there is a mixed type of these. Examples of the polyalkylallyl sulfonate-based high-performance water reducing agent include salts such as methylnaphthalene sulfonic acid formalin condensate, naphthalene sulfonic acid formalin condensate, and anthracene sulfonic acid formalin condensate. Product name of chemical industry company "FT
−500 ”, product name“ Mighty 100 ”manufactured by Kao,“ Mighty ”
150 "and" Mighty 2000 "series, etc., product name" Celflow 110P "manufactured by Daiichi Kogyo Seiyaku Co., Ltd., product name" Pole Fine 510N "manufactured by Takemoto Yushi Co., Ltd., and product name" Sun "manufactured by Nippon Paper Industries Co., Ltd. Typical examples are “Flow PS” and “Sunflow HS700”. Further, as a high performance water reducing agent based on aromatic amino sulfonate, there is a product name "Palic 200" series manufactured by FPC. And as a high performance water reducing agent of melamine formalin resin sulfonate, trade name "FT-3S" manufactured by Denka Grace Co., Ltd., trade name "Melment F-10" and "Melment F-20" manufactured by Showa Denko KK, etc. Can be mentioned. Further, as the polycarboxylic acid salt-based high-performance water reducing agent, olefin-maleic acid copolymer system, alkenyl ether-maleic anhydride copolymer system, and carboxy group-, sulfonic acid group-containing multi-component polymer or polyether carboxylic acid There is a salt-based acrylate-acrylic acid ester copolymer system and the like, and those added with a hydrolyzable polycarboxylic acid cross-linked product in order to enhance the slump retention property, and the like. Typical examples include Denka Grace's trade name “Super 200”, Takemoto Yushi Co., Ltd.'s trade name “Chupole HP11”, and NMB's trade name “Reobuild SP-8HS”.

The amount of the water reducing agent used is preferably 2 parts by weight or less, more preferably 1.5 parts by weight or less, and most preferably 0.2 to 1% by weight in terms of solid content, based on 100 parts by weight of cement. If it is less than 0.2% by weight, even if a polycarboxylic acid salt type water reducing agent having a large water reduction rate is used, the unit water amount tends to be too large and the strength tends to decrease, which is often used for manufacturing piles, poles, fume pipes, etc. When a polyalkylallyl sulfonate-based water reducing agent is used in an amount of more than 2% by weight, the effect of reducing or preventing slag generation decreases even if the amount of bentonite A used is large, which is not preferable.

Here, as the cement, normal, early strength,
Various types of Portland cement such as ultra-rapid strength and moderate heat, various types of mixed cement in which blast furnace slag, fly ash, or silica is mixed in these Portland cements, and slag-based cement or alumina in which fine slag is mixed in accordance with JIS standards or higher. Examples include cement.

Further, the combined use of these cements with a high-strength admixture containing gypsum as a main component, a high-strength admixture such as fly ash fume or silica fume, and a cement expansive material reduces or prevents slag formation. From the viewpoint of

The mixing conditions of concrete are not particularly limited, but the unit powder amount is in the range of 380 to 600 kg / m ³ , and the fine aggregate ratio is 45% or less. When the driving method is the pump driving method, it is preferably 38 to 45%, when it is the filling method, the range is 30 to 38%, and the water powder ratio is preferably 35% or less.

Here, the unit powder amount means concrete 1
The amount of powder in m ³ , which is the total amount of powder of cement, slag powder, siliceous powder, fly ash, high-strength admixture, and admixture such as cement expansive material.

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.

The method of using the slag reducing agent of the present invention is not particularly limited, and the respective components may be mixed separately or in advance and added in a powder state, or a part of the kneading water. Alternatively, it may be suspended in the whole amount and made into a slurry to be added to the mixer, or further, the water reducing agent may be suspended and added to a part or the whole of the mixing water. Then, it is particularly preferable to add it in the form of a slurry or suspension rather than to add it in the form of powder, since the effect of reducing or preventing the occurrence of slag is exhibited with a smaller amount.

The centrifugal force molding method in the present invention is not particularly limited, and includes three stages of low speed, medium speed and high speed,
Alternatively, the ordinary method is performed in four stages of low speed, medium speed I, medium speed II, and high speed, and is not particularly limited.

The GNo., Which is the magnitude of the centrifugal force and is a multiple of the gravitational acceleration, is usually 3 to 5 G at low speeds, and the rotation time can be 1 to 3 minutes. Medium speed I and medium speed II
In order to make the whole into 4 stages, medium speed I is performed for 1 minute or more at about 4 to 8 G in order to make the centrifugal force molded body uniform in thickness, and further, medium speed II is 5 cm or less for slump. If it is low, it is 12 to 25 G, and if the slump is more than 5 cm, pumping is 8 to 20 G.
More preferably, it is carried out for not less than 1 minute, most preferably for about 3 to 6 minutes. When the medium speed is carried out in one step, it is preferable to carry out at 8 to 20 G for 1 to 6 minutes regardless of the slump in consideration of the balance with the high speed. At high speeds, it is not necessary to regulate or standardize the G No. and rotation time in particular, there is no slag and the tightening is good, and it does not have to fall off due to impact during transportation. In addition, if the unit powder amount is large and the water retention capacity is large, and the slump is small, or if the slump is soft and centrifugal force molding is performed using a belt with smooth rotation such as a steel pipe composite pile,
It may take about 3 to 10 minutes for G.

The curing conditions in the present invention are not particularly limited, and normal pressure steam curing at 100 ° C. or less, or high temperature and high pressure curing at about 10 kgf / cm ² and 180 ° C. after normal pressure steam curing is performed. There are two ways to do it.

[0029]

The present invention will be described in detail below with reference to examples, but the present invention is not limited thereto.

[0030] The unit amount of Example 1 each material, water 145 kg / m ^3, cement 450 kg / m ^3, fine aggregates 625 kg / m ^3, coarse aggregate 1,161kg / m ^3, and admixture 45 kg / m ³
And the maximum aggregate size Gmax is 20mm and the slump SL is 3 ± 1c
Bentonite A and bentonite A are sulfuric acid using the basic mix of concrete with m, air 2 ± 1%, fine aggregate ratio S / a 34%, and water cement ratio W / C 32.2%. Bentonite B, which has been treated by the above and heat-treated at different treatment temperatures and pulverized, is blended as shown in Table 1 to obtain an outer diameter of 20 and a length of 30.
C. A centrifugal force molding specimen having a thickness of 5 cm was prepared, and the amount of slag produced at this time was measured. In addition, after the molded centrifugal force test specimen was placed in front for 2 hours, the temperature was raised to 75 ° C at a heating rate of 20 ° C / h, held for 4 hours, then allowed to cool in the steam curing tank until the next day, and then demolded. Then, the sample was cured in a room and the compressive strength on the 7th day was measured. Fluctuations in slump due to the addition of bentonite A and bentonite B were adjusted by adjusting the water reducing agent or adjusting the unit water amount. The test results are also shown in Table 1. In addition, the centrifugal force molding method was as follows: constant concrete input amount was 18 kg, low speed was 2G x 3 minutes, medium speed I was 4G x 1 minute, medium speed II was 15G x 3
The mold and the high speed were performed under the conditions of 35 G × 8 minutes, and the hollow open portions at both ends of the mold were capped so that the generated slag did not leak. In addition, the concrete mixing method is a planetary type capacity 100
Using a liter mixer, 30 liters of concrete was kneaded. To mix, mix cement, fine aggregate, and coarse aggregate into a mixer and dry-stir for 20 seconds, then add bentonite A and bentonite B to an aqueous solution prepared by dissolving water reducing agent α in mixing water and suspending. Then, the mixture was added and kneaded for 90 seconds as a whole.

<Materials used> Cement: Denki Kagaku Kogyo Co., Ltd., ordinary Portland cement, specific gravity 3.16 Fine aggregate: Crushed sand from Himekawa, Niigata, specific gravity 2.64 Coarse aggregate: Crushed stone from Himekawa, Niigata, specific gravity 2.64 Admixture: Electrochemical Koden Co., Ltd. high-strength admixture product name "Denka Σ1000", specific gravity 2.80 water reducing agent α: Dai-ichi Kogyo Seiyaku Co., Ltd. product name "Cellflow 11"
0P ”, powder, main component polyalkylallyl sulfonic acid type bentonite Aa: swelling degree 35, Na-type bentonite bentonite B: swelling degree 20 Na-type bentonite is treated with sulfuric acid and then heat-treated at 800 ° C. for 1 hour.

<Test method> Compressive strength: A molded centrifugal force test piece was placed in front for 2 hours,
The temperature was raised to 75 ° C at a heating rate of 20 ° C / h, held for 4 hours, then allowed to cool in the steam curing tank until the next day, and then demolded.
Measure the compressive strength of the material after 7 days of curing

[0033]

[Table 1]

[0034] From Table 1, bentonite A exerts a reducing or preventing effect of the slag produced from 0.3 kg / m ³ approximately, 1.0 kg / m ³
It is shown that it becomes more remarkable from the degree, and the more the amount used, the better the reduction or prevention effect of slag generation, but if the amount used is too large, the amount of water reducing agent also increases and conversely the reduction or prevention effect of slag generation It is shown that 20 kg / m ³ or less is preferable, 15 kg / m ³ or less is more preferable, and 10 kg / m ³ or less is most preferable.

Example 2 Example 1 was repeated except that the amounts of bentonite A and bentonite B used were changed as shown in Table 2. The results are also shown in Table 2.

[0036]

[Table 2]

[0037] From Table 2, the increase and decrease of the appropriate amount unit water bentonite B, 20 kg / m ³ or less are preferred, 0.2~15kg / m ³
Is more preferable, and 0.4 to 10 kg / m ³ is the most preferable.

Example 3 Example 3 was repeated except that the types and amounts of bentonite A and bentonite B were changed as shown in Table 3.
The results are also shown in Table 3.

<Materials used> Bentonite Ab: swelling degree 20, Na-type bentonite bentonite Ac: swelling degree 10, Na-type bentonite bentonite Ad: swelling degree 7, Ca-type bentonite bentonite BI: swelling degree 20 Na-type bentonite is sulfuric acid After treatment, heat treated at 300 ° C for 1 hour Bentonite B: After heat treatment of Na-type bentonite with swelling degree of 20 with sulfuric acid, heat treatment at 400 ° C for 1 hour Bentonite B c: After treatment of Na-type bentonite with swelling degree of 20 with sulfuric acid, at 600 ° C 1-hour heat treatment Bentonite B E: Na-type bentonite with a swelling degree of 20 is treated with sulfuric acid and then heat-treated at 1,200 ° C for 1 hour

[0040]

[Table 3]

It is clear from Table 3 that bentonite A having a larger degree of swelling requires a larger amount of the water reducing agent to obtain the same slump, but has a great effect of reducing or preventing slag generation.

Example 4 A unit amount of each material was 155 kg / m ^{3 of} water and 50 parts of silica cement B type.
0 kg / m ^3, fine aggregates 625 kg / m ^3, and a coarse aggregate 1,161kg / m ^3,
Gmax 20mm, SL 8 ± 2cm, air 2 ± 1%, S / a 38
%, And using W / C of 31%, bentonite A is kept constant at 5 kg / m ³ and bentonite B is kept constant at 3 kg / m ³ , the type and amount of water reducing agent are changed as shown in Table 4,
The centrifugal molding was performed in the same manner as in Example 1 except that the high speed was 30 G and the rotation time was 3 minutes. The results are also shown in Table 4.

<Materials used> Water-reducing agent β: product name "Super 20" manufactured by Denka Grace Co., Ltd.
Solidified "0", main component polycarboxylic acid salt type

<Test method> Compressive strength: A molded centrifugal test piece was placed in front for 2 hours,
The temperature is raised to 75 ° C at a heating rate of 20 ° C / h, kept for 4 hours, and then steam-cured until the next day. After that, up to 180 ℃ 3
After heating for 4 hours and holding for 4 hours, decompressing for 4 hours and cooling,
Next day (3rd day of age) Measure compressive strength

[0045]

[Table 4]

From Table 4, when the amount of water reducing agent used is increased,
If it is within an appropriate amount range, the effect of reducing or preventing slag generation is increased, and it is clear that the amount of the water reducing agent used is preferably 0.2 parts by weight or more per 100 parts by weight of cement.

[0047]

By using the slag reducing material of the present invention, the effect of reducing or preventing slag generated during centrifugal molding can be further improved. Further, the unit water amount of concrete can be reduced to obtain the same slump, and the compressive strength is improved. Further, by using the slag reducing material of the present invention, slag currently discarded as industrial waste can be eliminated, and it is also effective in terms of pollution prevention and environmental protection.

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Claims (3)

(57) [Claims] 1. A slag reducing material comprising bentonite and a heat-treated bentonite product. 2. A centrifugal force molded body formed by molding concrete containing the slag reducing material according to claim 1. 3. A method for producing a centrifugal force molded body, which comprises kneading concrete containing the slag reducing material according to claim 1 and performing centrifugal force molding.