JPH08217506A - Concrete admixture with slag reduced - Google Patents

Abstract

PURPOSE: To reduce slag by incorporating the water-soluble salt of a naphthalene sulfonate-formalin condensate and the water-soluble salt of a specified copolymer. CONSTITUTION: 30-40 pts.wt. of the water-soluble salt of a naphthalene sulfonate- formalin condensate, maleic acid and/or maleic anhydride, 0.05-5 pts.wt. of the water-soluble salt of a coplymer obtained by copolymerizing an ethylenically, unsaturated monomer copolymerizable with maleic acid and/or maleic anhydride and having 1,000,000-2,000,000 weight average mol.wt. and 69.95-50 pts.wt. of water are mixed, and the mixture is agitated at room temp to 90 deg.C for 1 to 6hr and dissolved to obtain a concrete admixture. This admixture is added by 0.5-3 pts.wt. to 100 pts.wt. of cement.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a concrete pile,
The present invention relates to a concrete admixture used in the production of concrete products such as poles, steel pipe composite piles, fume pipes, and steel pipe linings that are formed by using centrifugal force.

[0002]

2. Description of the Related Art Conventionally, concrete piles and poles,
Concrete products such as fume pipes are manufactured by compacting and compacting by centrifugal force (hereinafter, these products are collectively referred to as centrifugal molded products). In the centrifugal molding process, the water in the concrete is squeezed out and a dense structure is generated, but this water contains cement and fine powder in the aggregate.
It is discharged as so-called Noro. Especially for piles that require high strength, a large amount of high-performance water reducing agent is added.
The amount of slag is large, and the tightness of the mortar layer on the inner surface of the pipe is poor. This noro is strongly alkaline, so sedimentation separation
After neutralization, the solid content must be treated as industrial waste. Therefore, not only a large amount of cost is required, but also recently, it has become difficult to secure a disposal place for the slag, which is a big problem for the centrifugal molding industry.

Therefore, a method of reusing slag as a raw material for concrete products has been disclosed (JP-A-63-28).
No. 46). However, it is obvious that this method requires investment in new facilities such as a storage tank for Noro and piping for recycling Noro, and it has not been put to practical use except for a few companies. Therefore, most of the measures against slag that have already been disclosed are measures to reduce the amount of slag.

[0004] The principle of the proposed measures for preventing slag generation is as follows: (1) The viscosity of the paste is increased by adding a thickener or a substance having water retention property, and the discharge of slag is reduced. By adding a coagulant during molding, the particles separated as Noro are coagulated so that only water is discharged. (3) Others are roughly classified.
As one utilizing the thickening effect of the paste of (1),
For example, a method of adding a cellulosic compound and / or a polyacrylamide compound (Japanese Patent Laid-Open No. 61-201649), a method of adding an air entraining agent and finely divided silica and fine inorganic particles of clay (Japanese Patent Laid-Open No. 63-2016). No. 103850),
Alternatively, a method of adding a polymer dispersion such as styrene-butadiene rubber and inorganic fine powder (Japanese Patent Laid-Open No. 5-24
No. 031) is disclosed. Further, as a method utilizing the aggregating effect of (2), a polyacrylamide type aggregating agent and an anionic surfactant or a nonionic surfactant are used to form bubbles having a specific bubble density, and the bubbles are formed during molding. Injecting method (JP-A-63-60141), and adding a polyacrylamide partial hydrolyzate having a molecular weight of 300 to 1,000,000 and a hydrolysis rate of 5-35% during molding (JP-A-5-306154). Gazette) is disclosed. further,
As the method utilizing the other principle of (3), a method of adding thiosulfate which is a hardening accelerator for concrete (JP-A-61-68361) and a method of adding caseins (Japanese Patent Publication No. 13896) and the like are disclosed.

However, all of these methods use powders or chemicals prepared by dissolving powders in water in advance during mixing of concrete or during molding, and the measurement and feeding of powders into existing equipment. Equipment or powder melting equipment must be added, which requires capital investment. Furthermore, the drug used in these methods is a powder that easily becomes so-called "mamako". Therefore, it takes a long time to dissolve in concrete kneading water or water, and from this point as well, the manufacturing cost of the product becomes high and there are many problems. From these facts, the noro reducing agent disclosed in the above publication is rarely used, and most of it is currently treated as industrial waste.

[0006]

[Problems to be Solved by the Invention] As described above,
Disadvantages of the prior art are (1) powder or a chemical in which powder is previously dissolved in water is used during concrete kneading or during molding, and new capital investment is required, and (2) concrete Because it uses powder that tends to become "mamako" when it is dissolved in kneading water or water, it takes a long time to dissolve and the cost increases.
It is a point. Also, it is generally difficult to handle powder,
A liquid drug is desired as a slag reducing agent. Furthermore, while satisfying the cement dispersibility required as a high-performance water reducing agent, liquid chemicals that have been imparted with a slag reducing ability are equipped with measuring and charging equipment for concrete admixtures such as high-performance water reducing agents that have been used conventionally. Since it can be diverted as it is, its industrial value as a slag reducing agent is very high. However,
Nothing is known about such drugs.

In view of the above, the inventors of the present invention have found a concrete admixture having only a liquid chemical agent and a cement dispersibility which is required as a high-performance water-reducing agent and which has a slag-reducing ability. As a result of earnestly studying the purpose, the present invention has been completed. That is, the object of the present invention is to
It is intended to provide a concrete admixture having a slag reducing ability, and further to provide a concrete admixture having a slag reducing ability while satisfying the cement dispersibility required as a high performance water reducing agent.

[0008]

In order to solve the above-mentioned problems, the present inventors have maintained the fluidity of concrete,
As a result of intensive studies aimed at obtaining an admixture capable of reducing the amount of slag produced, the present invention has been completed.
That is, the present invention is a concrete admixture capable of reducing porosity, which is an aqueous solution containing the following A component and B component. Component A: Water-soluble salt of naphthalene sulfonic acid formalin condensate. Component B: A water-soluble salt of a copolymer of maleic acid and / or maleic anhydride and an ethylenically unsaturated monomer copolymerizable therewith.

Further, the present invention is preferably the above-mentioned admixture obtained by dissolving the component A in an amount of 30 to 45 parts by weight and the component B in an amount of 0.05 to 5 parts by weight in 69.95 to 50 parts by weight of water.
In the present invention, the weight average molecular weight of the component B is 100,000.
~ 2,000,000 is preferred, and further, the present invention is
The ethylenically unsaturated monomer copolymerizable with maleic acid and / or maleic anhydride is selected from the group consisting of vinyl acetate, styrene, acrylic acid, alkyl esters of acrylic acid, and olefins having 2 to 8 carbon atoms. It is preferably at least one kind of monomer.

[0010]

The concrete admixture capable of reducing slag of the present invention (hereinafter referred to as the admixture of the present invention) will be described in detail below. It is known that it is possible to reduce roe by thickening the paste (eg cement industry,
(216) 33, 1989). Therefore, the use of thickeners that are commonly used in the technical field relating to concrete, such as cellulosics and polyacrylamides, can reduce slag. However, when such an ordinary thickener is dissolved in an aqueous solution of a water-soluble salt of a naphthalenesulfonic acid formalin condensate (hereinafter referred to as NSF), which is a high-performance water reducing agent, it hardly dissolves or even when dissolved. The viscosity of the aqueous solution after dissolution becomes high, and an admixture that can be put to practical use cannot be obtained.

Therefore, as a result of examining the molecular structures of various thickeners in an NSF aqueous solution, the present inventors have found that maleic acid and / or maleic acid and / or Alternatively, when a water-soluble salt (component B) of a copolymer of maleic anhydride and an ethylenically unsaturated monomer copolymerizable with maleic anhydride is added, the molecular chain becomes threadlike and the viscosity of the admixture does not increase. However, it has been found that in concrete, the molecular chain stretches and acts effectively as a slag reducing agent. Furthermore, preferably, by setting the concentrations of the A component and the B component in the admixture within specific ranges, it is possible to impart a high slag reduction ability while satisfying the cement dispersibility required as a high performance water reducing agent. I found it.

The admixture of the present invention is used by adding it during the production of concrete, like the high-performance water reducing agent which is usually used. The admixture of the present invention is characterized in that it is a one-pack type drug that has a slag reduction ability while satisfying the cement dispersibility required as a high-performance water reducing agent. The function of the water-soluble salt of the naphthalene sulfonic acid formalin condensate which is the A component is to impart cement dispersibility, and the maleic acid and / or maleic anhydride which is the B component and an ethylenic unsaturated copolymerizable therewith. The function of the water-soluble salt of the copolymer with the monomer is to impart the slag reducing ability. Therefore, even if only the B component alone is added to the concrete, it is clear that it exhibits a higher noro reduction ability than the conventional noro reduction agents. However, in that case, since the weighing and the charging equipment for charging the component B or the aqueous solution thereof into the concrete are separately required, the industrial superiority becomes low.

Examples of the water-soluble salt (NSF) of the naphthalenesulfonic acid formalin condensate which is the component A of the admixture of the present invention include, for example, the product name "KFLOW" manufactured by Kawasaki Steel Co., Ltd.
S-110 ", product name" Mighty 15 "manufactured by Kao Corporation
Pure content such as "0" is used. As salt, Na salt, K
Any salt selected from water-soluble alkali metal salts such as salts and ammonium salts may be used, but Na salt is most commonly used. In the admixture of the present invention, NSF which is the A component is 30-
It is preferably contained in an amount of 45 parts by weight. If it is less than 30 parts by weight, the fluidity of concrete, which is usually expressed as a slump value, is low, and it does not meet the criteria for a superplasticizer. When the amount of the component A exceeds 45 parts by weight, the fluidity is high, but a water-soluble salt of a copolymer of maleic acid and / or maleic anhydride, which is the component B, and an ethylenically unsaturated monomer copolymerizable therewith is formed. The solubility decreases and the ability to reduce slag becomes insufficient. In addition, the admixture is expensive.

The water-soluble salt of a copolymer of maleic acid and / or maleic anhydride, which is the component B of the admixture of the present invention, and an ethylenically unsaturated monomer copolymerizable therewith is used in the admixture of the present invention. It is preferably contained in an amount of 0.05 to 5 parts by weight. If the amount of the component B in the admixture of the present invention is less than 0.05 parts by weight, the addition effect of the component B for reducing the amount of slag hardly appears. In addition, the admixture is expensive.

The weight average molecular weight of the component B is 100,000 to 2,0.
It is preferably 00,000. If the weight average molecular weight of the component B of the admixture of the present invention is less than 100,000, the effect of the component B on reducing slag is insufficient, and the weight average molecular weight of 2,000
If it exceeds 000, the viscosity of the admixture becomes too high to obtain a practical admixture. Here, an admixture having a viscosity that cannot be put to practical use is an admixture having a viscosity higher than that of a high-performance water-reducing agent that is normally used at present, and is not limited in any way, but is measured by a B-type viscometer. Those with a viscosity of 200 cP or more were considered to be impractical. The weight average molecular weight is 2,000,0.
If it exceeds 00, the fluidity of concrete also decreases.

In the B component, maleic acid and / or
Or, ethylenically unsaturated monomer copolymerizable with maleic anhydride, the reason is not clear, vinyl acetate, styrene, acrylic acid, alkyl esters of acrylic acid,
And at least one monomer selected from the group consisting of olefins having 2 to 8 carbon atoms. Among these monomers, as the olefin having 2 to 8 carbon atoms, ethylene, propylene, isobutylene, butene, 2-methyl-1-butene, hexene, octene,
Diisobutylene and the like can be exemplified, and the carbon number is 2 to 2.
Among the 8 olefins, olefins having 4 to 6 carbon atoms are particularly preferable because they are inexpensive and have an excellent effect of reducing slag.

Each of these ethylenically unsaturated monomers may be used alone in the admixture of the present invention as a water-soluble salt prepared by copolymerization with maleic acid and / or maleic anhydride. The water-soluble salt produced by using can also be used in the admixture of the present invention. The ratio of the ethylenically unsaturated monomer in the component B can be appropriately selected, but is usually 20 to 80 mol%, preferably 30 to 70 mol% in the component B. Na as salt
Various salts selected from alkali metal salts such as salts and K salts, ammonium salts and the like are used, but sodium salts are usually most commonly used. The ratio of salt (neutralization degree) is
Although it is not limited, it is sufficient if water solubility can be imparted, and normally B
It is preferable to neutralize 50 mol% or more of the maleic acid group in the component with a salt. Further, the admixture of the present invention can be used only as a copolymer salt having a single degree of neutralization, or as a mixture of several copolymer salts having different degrees of neutralization.

The method of producing the copolymer which is the component B used in the present invention is arbitrary and various polymerization methods can be adopted, but it is usually produced by radical polymerization according to a conventional method.
Further, the method for producing the water-soluble salt of the copolymer is arbitrary, and any of a method of neutralizing the monomer with an alkali or the like and then polymerizing it, and a method of synthesizing the copolymer and then neutralizing can be adopted.

Since the physical properties of the concrete used in centrifugal molding and the centrifugal molding conditions vary depending on the centrifugal molder, the content ratios of the components A and B in the admixture of the present invention and B
Regarding the degree of polymerization and the degree of neutralization of the components, an optimal composition can be selected from the suitable range of the admixture of the present invention depending on the physical properties of the concrete used and the centrifugal molding conditions. The admixture of the present invention is prepared by adding water to the above-mentioned pure components A and B and dissolving them to make 100 parts by weight as a whole. Above A, B
Since the components are usually produced as an aqueous solution, a pure content is obtained by an arbitrary method such as drying, then a predetermined amount of water is added, and the admixture of the present invention which is an aqueous solution is produced by an arbitrary method such as stirring. be able to. The stirring is not limited, but is usually performed at room temperature to 90 ° C. for 1 to 6 hours. Further, since the components A and B are usually produced as an aqueous solution, water is not added after producing these pure components, and the remaining water necessary for the aqueous solutions of the components A and B is added and stirred. Alternatively, the admixture of the present invention may be manufactured.

The admixture of the present invention can be used in combination with other known admixtures such as a water reducing agent, an AE agent, an AE water reducing agent, a foaming agent, a retarder, a curing accelerator, and a swelling agent. Further, the admixture of the present invention can be obtained simply by adding water to the components A and B and dissolving it. However, it is also possible to manufacture by adding a small amount of an inorganic salt such as sodium sulfate as a dissolution aid upon dissolution. Examples of such inorganic salts include sodium carbonate, sodium aluminate, and the like, in addition to sodium sulfate.

The admixture of the present invention is usually cement 100
It is used by adding 0.5 to 3 parts by weight to parts by weight. 0.5
If it is less than 3 parts by weight, desired properties cannot be obtained in terms of fluidity and slag reducing ability of the concrete, and if it is more than 3 parts by weight, not only the setting retarding property of the concrete is recognized, but also the price of the admixture is included. This is not preferable because the price of concrete becomes expensive. The addition method and the kneading method may be carried out by the methods generally used in this technical field, and are not limited at all.

The concrete thus kneaded is put into a mold and compacted by centrifugal force. Centrifugal molding conditions may be those normally used, for example, for a pole or pile, low speed 2-5G for 2-5 minutes, then medium speed 5-15G for 2-6 minutes, and finally high speed 15-35G. 4-10
Do this by rotating for a minute. The concrete after centrifugal molding is cured by a normal method such as underwater curing, steam curing, and autoclave curing to obtain a product.

The admixture of the present invention is added to concrete, and as the cements, in addition to ordinary Portland cement, cements such as blast furnace cement, fly ash cement and early strength cement are used. In addition to cement, various admixtures such as fly ash, silica fume, blast furnace slag, and expander can also be used as the admixture of the present invention without any limitation.

[0024]

EXAMPLES The present invention will be specifically described below based on examples, but the present invention is not limited to the specific details described in these examples. As the component A, a water-soluble salt of a naphthalene sulfonic acid formalin condensate, a product name “KFLOW S-110” manufactured by Kawasaki Steel Co., Ltd. or a product name “Mighty 150” manufactured by Kao Co., Ltd. is evaporated and dried to dryness. The obtained pure content was used (in Table 2, N
Notated as SF1 and NSF2). As the component B, pure components of the compounds shown in Table 1 were used (hereinafter, each compound will be referred to by the abbreviations shown in Table 1). IB3 and SY3 are compounds having a weight average molecular weight outside the preferred range of the present invention. Here, the weight average molecular weight was measured by gel permeation chromatography on the basis of polystyrene sulfonate sodium salt. The degree of neutralization was calculated from the charging ratio of NaOH used for neutralization to maleic acid groups.

In the examples, an admixture was prepared by adding water to both components A and B collected in parts by weight shown in Table 2 so that the total amount was 100 parts by weight, and the viscosity of the admixture was measured by a B-type viscometer. After the measurement, concrete was prepared with the composition shown in Table 3. In addition,
The admixture was kneaded and dissolved in water before use. After measuring slump and air volume, according to JIS A 1136, outer diameter 20 cm x height 30 cm
A centrifugally-molded specimen having a concrete thickness of 4 cm was prepared using the above mold. The molding conditions are shown in Table 3. The amount of slag was shown as a relative value with the amount of slag generated in Comparative Example 1 as 100. In addition, measurement of slump and air volume is performed according to JIS A6204.
It was done according to.

Table 2 shows the slump and relative amount of slump when the admixture of the present invention was used and when the admixture having a composition outside the preferred range of the present invention was used to clarify the effect of the present invention. . Table 2 also shows the slump and relative slag amount when the admixture of the present invention was not used (prior art). As is clear from this, by using the admixture of the present invention, in any case of the present invention examples 1 to 21, relative relative to Comparative Examples 1 and 2 which is a conventional technique not using the admixture of the present invention. It is clear that the amount is decreasing.

Further, in the case of Examples 1 to 15 of the present invention using the admixture within the preferred range of the present invention, the slump satisfied the target value as in Comparative Example 1, and exhibited the high fluidity required as a high performance water reducing agent. Despite being maintained, the relative amount of slag is compounded-
It was 40 or less irrespective of the molding conditions and showed a remarkable slag reduction ability. Also, the viscosity of the admixture is 160 cP or less, which is practically
The viscosity was fine. On the other hand, if an admixture in which the concentrations of the components A and B are out of the preferred range of the present invention is used, the slump is reduced (Invention Examples 16 and 19) or the slag reduction ability is reduced (Invention Example 18). Therefore, it is desirable to use the admixture having the concentrations of A and B components within the preferred range of the present invention. The compressive strength of the sample using the admixture of the present invention was the same as that in the case where no admixture was added, and no adverse effects such as retardation of curing were shown.

[0028]

[Table 1]

[0029]

[Table 2]

[0030]

[Table 3]

[0031]

[Table 4]

[0032]

The admixture of the present invention has a large effect of reducing roe. Furthermore, since the admixture of the present invention is a one-pack type agent that has been imparted with the ability to reduce slag while satisfying the cement dispersibility required as a high-performance water-reducing agent, it is possible to use the high-performance water-reducing agent that has been used until now. The metering tank and the input port to the concrete mixer can be used as they are. Therefore, no new capital investment is required, and the slag processing cost can be significantly reduced as compared with the conventional technology. Furthermore, since the amount of Noro, which is an industrial waste, is greatly reduced, it is also useful for protecting the global environment, so that the industrial value of the present invention is very large.

Claims (4)

[Claims] 1. A concrete admixture capable of reducing porosity, which is an aqueous solution containing the following components A and B. Component A: Water-soluble salt of naphthalene sulfonic acid formalin condensate. Component B: A water-soluble salt of a copolymer of maleic acid and / or maleic anhydride and an ethylenically unsaturated monomer copolymerizable therewith. 2. A component of 30 to 45 parts by weight and a B component of 0.05
The concrete admixture according to claim 1, which is dissolved in 69.95 to 50 parts by weight of water at a ratio of 5 to 5 parts by weight. 3. The weight average molecular weight of component B is 100,000-
The concrete admixture capable of reducing slag according to claim 1 or 2, which has a content of 2,000,000. 4. An ethylenically unsaturated monomer copolymerizable with maleic acid and / or maleic anhydride is a group consisting of vinyl acetate, styrene, acrylic acid, an alkyl ester of acrylic acid, and an olefin having 2 to 8 carbon atoms. The concrete admixture capable of reducing slag according to any one of claims 1 to 3, which is at least one kind of monomer selected from the above.