JPH08188458A - Concrete composition inseparable in water - Google Patents

Abstract

PURPOSE: To obtain a concrete composition inseparable in water having high fluidity, excellent separation resistance in water and improved freezing and thawing resistance. CONSTITUTION: This concrete composition containing a water-soluble cellulose ether controls an amount of air in concrete by adding an anti-foaming agent and improves freezing and thawing resistance by adding hollow fine spherules and fine powder of blast furnace slag.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inseparable concrete containing water-soluble cellulose ether and having improved freeze-thaw resistance.

[0002]

2. Description of the Related Art Generally, when concrete containing no thickening agent is poured into water, the concrete separates and its strength becomes extremely low. On the other hand, by adding a water-soluble cellulose ether such as hydroxypropylmethyl cellulose and adding a water-reducing agent such as melamine, the concrete composition has excellent fluidity and less deterioration in strength even when cast in water. It is possible to manufacture things. Such concrete composition is generally called underwater non-separable concrete (JSCE, underwater non-separable concrete design and construction guidelines, hereinafter referred to as JSCE guidelines).

On the other hand, in concrete to which water-soluble cellulose ether such as hydroxypropylmethyl cellulose is added, air bubbles entrapped in the concrete escape due to the interfacial action of the hydroxyl group of cellulose as a raw material and various substituents reacted with it. There is a feature that it becomes difficult.

When a large amount of air bubbles are mixed in during the kneading, the air amount standard (generally 4.5 ± 1.5%)
And the increase in the amount of air causes a decrease in compressive strength. Therefore, in these water-separable concrete in which a relatively large amount of water-soluble cellulose ether is added, a defoaming agent such as tributyl phosphate is used in combination,
The current situation is to control the amount of air.

[0005]

However, underwater non-separable concrete which is a concrete containing a relatively large amount of water-soluble cellulose ether and an antifoaming agent is
It is generally said that it is inferior in freeze-thaw resistance (Proceedings of the symposium on underwater non-separable concrete, 199).
August 0, hereinafter referred to as symposium proceedings).

For this reason, as seen in the JSCE Guidelines, there are restrictions on construction in cold regions where there is a risk of freezing in winter, construction in tidal zones, etc. In casting, since the cured body is in water, it does not freeze, so it does not matter.) Various methods have been tried in order to improve this drawback. For example, addition of expandable aluminum powder, addition of hollow microspheres, etc. (Concrete Engineering Annual Report, pp899-pp904, Vol.15, No.1.1993; Concrete Engineering Annual Report) , Pp567 ~ pp572, Vol.16, No.1.199
Four).

However, in the case of adding the antifoaming agent (see the symposium collection, etc.), the freezing and thawing resistance cannot be cleared unless the air amount is as high as about 10% or more, resulting in a new problem of reduction in compressive strength. Generate points. Further, in the case where the hollow microspheres are added, there is no problem in terms of the air amount of about 5%, but there is a drawback in terms of cost that a large amount of relatively expensive hollow microspheres must be added.

As described above, under the present circumstances, it is difficult to obtain an underwater non-separable concrete that can clear freeze-thaw resistance without adversely affecting the cured physical properties such as compressive strength and relatively economically. .

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to provide an underwater non-separable concrete composition which is excellent in material separation resistance in water and freezing and thawing resistance while ensuring fluidity. To do.

[0010]

In view of such a situation, the present inventors have added a water-soluble cellulose ether and a water reducing agent to secure material separation resistance and fluidity, and With an amount of air equivalent to that of concrete, and as a result of diligent examination of a concrete composition for underwater casting that can economically clear freeze-thaw resistance,
It was found that a concrete composition for pouring underwater having excellent freeze-thaw resistance can be obtained by using a combination of polymer hollow microspheres and blast furnace slag fine powder in concrete whose air content is controlled by an antifoaming agent. .

That is, in order to achieve the above-mentioned object, the invention of claim 1 provides a water-soluble cellulose ether-containing non-separable concrete composition comprising hollow microspheres,
It is characterized by blending an antifoaming agent and blast furnace slag fine powder.

[0012] According to a second aspect of the invention, in water nondisjunction concrete composition of claim 1, fineness of the blast furnace slag, 2,500～15,000Cm in Blaine value ² /
g.

The water-soluble cellulose ether used in the present invention is used to prevent the separation of materials such as aggregate and cement in water, and the following water-soluble nonionic cellulose ethers can be mentioned. Hydroxyalkyl cellulose: hydroxyethyl cellulose (HEC), hydroxypropyl methyl cellulose (H
PC) etc. Hydroxyalkylalkylcellulose: hydroxyethylmethylcellulose (HEMC), hydroxypropylmethylcellulose (HPMC), hydroxyethylethylcellulose (HEEC), etc. Among such nonionic cellulose ethers, HPMC and HEC are particularly preferable. In addition, you may use these water-soluble cellulose ethers individually by 1 type or in combination of 2 or more types.

The viscosity is not particularly limited, but it is 1% (1% by weight) measured by using a B type viscometer.
If the viscosity of the aqueous solution is 1,000 to 50,000 cP, the object of the present invention can be sufficiently achieved.

The amount of water-soluble cellulose ether added varies depending on the type, molecular weight, degree of substitution, unit cement amount, setting environment, etc.
Addition of 1 to 5% by weight, preferably 0.5 to 2% by weight makes it possible to obtain concrete having excellent resistance to material separation in water.

The polymer hollow microspheres used in the present invention are made of a polymer spherical elastic film and have a diameter of 300.
It is desirable that the thickness is less than or equal to μm, preferably less than or equal to 100 μm. If the particle size is too large, the compressive strength will decrease even with the same amount added.

Although the material thereof is not limited, thermoplastic resins such as polystyrene, polyvinylidene chloride, polymethylmethacrylate, vinyl chloride, acrylic resin and the like can be used. It may be a polymer or a copolymer.

The amount of addition depends on the amount of water-soluble cellulose ether, the amount of antifoaming agent, and the required amount of air. Generally 0.01 per 1 m ^{3 of} concrete
About 5.0 kg is preferable (excluding attached water).

The blast furnace slag fine powder used in the present invention is
It is produced when producing pig iron from iron ore, and can be made into powder by a roller mill or the like.

The fineness is represented by a Blaine value, and if the Blaine value is less than 2,500 cm ² / g, improvement in freeze-thaw resistance as in the present invention cannot be expected. Further, the larger the Blaine value, the higher the freeze-thaw resistance, but those having a Blaine value of more than 15,000 cm ² / g are effective for the freeze-thaw resistance, but a large amount of energy is required to obtain a fine powder. Is necessary and there is a problem in terms of economy.

The amount of addition depends on the desired freeze-thaw resistance, hardening characteristics, setting characteristics and the like. Generally, about 20 to 400 kg per 1 m ^{3 of} concrete is preferable.

As the defoaming agent used in the present invention, those used as defoaming agents for cement, mortar, concrete or gypsum can be used. For example, tributyl phosphate, Pluronic-based defoaming agent [Pluronic L61 (manufactured by Asahi Denka Kogyo), etc.], silicone-based defoaming agent [KM73 (manufactured by Shin-Etsu Chemical Co., Ltd.)], acetylene glycol derivative [Surfynol (Nissin Chemical Industry Co., Ltd. Made)
Etc.] etc. are used. The amount used is generally 0.05 to 2.0 kg per 1 m ^{3 of} concrete.

The water-reducing agent used in the present invention includes a high-performance water-reducing agent, an AE water-reducing agent, and the like in addition to a normal water-reducing agent, and of these, the high-performance water-reducing agent is preferable.

As the high-performance water reducing agent, a highly condensed triazine compound, a formalin condensate of melamine sulfonate, a polycarboxylic acid salt derivative, a modified lignin sulfonate compound, an amino sulfonic acid polymer, naphthalene Examples thereof include formalin condensates of sulfonates and isoprene compounds. Among these, highly condensed triazine compounds, formalin condensates of melamine sulfonates, polycarboxylic acid salt derivatives, modified lignin sulfonates Compounds and isoprene compounds are preferred.

These water reducing agents are generally present in an amount of 0.5 to 5% by weight, preferably 1 to 3% by weight, based on the cement binder.
Used in.

Examples of the cement binder of the present invention include, in addition to ordinary Portland cement, fast-strength Portland cement, moderate heat Portland cement, white Portland cement, super fast-strength Portland cement, blast furnace cement containing fine powder of blast furnace slag, silica cement, In addition to inorganic powders such as fly ash cement and fly ash and stone powder, those having a pozzolanic reaction such as silica fume are also included, and one kind or a combination of two or more kinds selected from these is used.

AE of fatty acid soap type, resin acid type, etc.
Agents can also be used in combination.

Typical examples of the water-separable concrete mixture composition according to the present invention are as follows. Cement binder 300~500kg / m ³ blast furnace slag 20~400kg / m ³ Aggregate 1600~2000kg / m ³ water 150 to 250 kg / m ³ water-soluble cellulose ether 1.0 to 5.0 kg / m ³ Hollow microspheres 0.01 to 5.0 kg / m ³ antifoaming agent 0.05 to 2.0 kg / m ³ water reducing agent 3 to 20 L / m ³

The composition of the present invention can be produced according to a conventional method. For example, in a raw concrete plant or on-site, cement binder, aggregate, water reducing agent and water, water-soluble cellulose ether, hollow microspheres, blast furnace are used. It is produced by adding slag fine powder and an antifoaming agent, and stirring and mixing. The hollow microspheres, blast-furnace slag fine powder and defoaming agent can be used either by being premixed with the water-soluble cellulose ether or by being directly added to concrete.

[0030]

EXAMPLES Hereinafter, specific embodiments of the present invention will be described with reference to Examples and Comparative Examples, but the present invention is not limited thereto. (Examples 1 to 5 and Comparative Examples 1 to 5)

The materials and test methods used in each example are as follows. 1. Water-soluble cellulose ether: HPMC (1% viscosity 3,5
00cP, manufactured by Shin-Etsu Chemical Co., Ltd., abbreviated as HPMC in the table) 2. Hollow microspheres: Expancel (Nippon Philite) 3. Defoaming agent: tributyl phosphate 4. Blast furnace slag fine powder: Cerament, Blaine value 4,7
00 cm ² / g (made by Daiichi Cement, abbreviated as BF in the table) Fine Celerment, Blaine value 8,900 cm ² / g
(Made by Daiichi Cement, abbreviated as BF in the table) 5. Fine aggregate: river sand from Shinanogawa, specific gravity 2.60, coarse grain ratio 2.
82, water absorption rate 1.56 6. Coarse aggregate: crushed stone from Shimozurukawa, specific gravity 2.63, coarse grain ratio 6.
72, water absorption rate 1.86 7. Cement: ordinary Portland cement, specific gravity 3.1
5 (Nippon Cement, abbreviated as NP in the table) 8. High-performance water reducing agent: Reobuild UC-150 (manufactured by Pozoris, abbreviated as UC-150 in the table) 9. The mixing ratio of the water nondisjunction concrete: As water-cement ratio 55.0% fine aggregate ratio 40.0% cement Table 1 Fine aggregate 638kg / m ³ Coarse aggregate 967kg / m ³ water 220 kg / m ³ water-soluble Cellulose ether As shown in Table 1 Hollow microspheres As shown in Table 1 Defoaming agent 0.10 kg / m ³ High performance water reducing agent As shown in Table 1. Kneading: Using a pan mixer, total kneading time is 3
Minutes and 30 seconds. (Empty kneading 30 seconds, main kneading (after water injection) 3 minutes) 11. Concrete test, test method: 1) Slump flow test [Concrete slump flow test method (draft), JSCE (JSCE standard)] 2) Air volume (JIS A 1128) 3) Compressive strength test (JIS A 1108), underwater The prepared specimen conforms to the guidelines of the Japan Society of Civil Engineers. 4) Freeze-thaw test (concrete freeze-thaw test method,
JSCE)

Examples 1 to 5 are water-inseparable concretes containing hollow microspheres and blast furnace slag fine powder, and have excellent fluidity and water-flow separation resistance, and a durability index of 80%.
From the above, the freeze-thaw resistance is also excellent.

Further, as seen in Examples 3 and 5, the larger the amount of the blast furnace slag fine powder added and the larger the Blaine value of the blast furnace slag fine powder, the better the freeze-thaw resistance.

Compared with this, Comparative Examples 1 to 5 are inferior in freeze-thaw resistance or are economically expensive.

Comparative Example 1 is a case of ordinary concrete containing no water-separable admixture, which is inferior in separation resistance in water and has a remarkably low compressive strength.

Comparative Example 2 is a case of a commonly used underwater non-separable concrete in which neither hollow microspheres nor blast furnace slag fine powder are added. It has excellent separation resistance in water, but freeze-thaw resistance. Inferior in sex.

Comparative Examples 3 and 4 are cases in which hollow microspheres were added and blast furnace slag fine powder was not added. Freezing and thawing resistance was improved, but to obtain a durability index of 80% or more, hollow Since it is necessary to add a large amount of relatively expensive hollow microspheres with a microsphere addition amount C × 0.40%, it is not economical.

In Comparative Example 5, hollow microspheres were not added and only blast furnace slag fine powder was added, and the freeze-thaw resistance is poor.

The above results are shown in Table 1.

[0040]

[Table 1]

[0041]

As described above, according to the present invention, by using water-soluble cellulose ether, antifoaming agent, hollow microspheres and blast furnace slag fine powder as essential components, fluidity and inseparability in water resistance Is excellent, and the air content is less than 5%,
An underwater non-separable concrete composition having excellent freeze-thaw resistance can be economically obtained.

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Claims (2)

[Claims] 1. A water-soluble cellulose ether-containing non-separable concrete composition comprising hollow microspheres,
An underwater non-separable concrete composition comprising an antifoaming agent and blast furnace slag fine powder. 2. The underwater non-separable concrete composition according to claim 1, wherein the fineness of the blast furnace slag fine powder is 2,500 to 15,000 cm ² / g in terms of Blaine value.