JPH06114824A - Ultra high strength concrete preparation method and ultra fine powder mixture - Google Patents

Abstract

(57) [Summary] (Modified) [Purpose] To reduce the required amount of admixture, kneading water, and ultrafine powder to easily and inexpensively prepare ultrahigh strength concrete with extremely high strength. [Structure] Cement fine aggregate and coarse aggregate (or cement) are added to an ultrafine powder mixture made of a slurry-like substance obtained by mixing ultrafine powder and water (or fine aggregate, or fine aggregate and coarse aggregate). And coarse aggregate or cement only). [Effect] It is possible to obtain a slurry-like material in which ultrafine powder particles that easily aggregate are uniformly dispersed. Therefore, it is possible to obtain fresh concrete having high fluidity. The amount of admixture and the amount of kneading water required to obtain the same fluidity are greatly reduced. The amount of ultrafine powder required to obtain the same strength blend is greatly reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for preparing ultra high strength concrete and an ultra fine powder mixture used as a material for producing ultra high strength concrete.

[0002]

2. Description of the Related Art It is known that when a concrete mixture contains ultrafine powder such as silica fume, the fine voids in the hardened concrete become filled with the ultrafine powder, and the strength of the hardened body is remarkably increased. Has been.

Conventionally, in order to prepare ultra-high strength concrete, water and an admixture are added to cement, ultra-fine powder, fine aggregate and coarse aggregate and kneaded to obtain fresh concrete, or cement is used. After mixing with and ultrafine powder, fine aggregate, coarse aggregate, water and an admixture are added and kneaded,
I try to get fresh concrete.

[0004]

In the above conventional preparation method, since the ultrafine powder easily aggregates, the ultrafine powder is not easily dispersed in the fresh concrete, so that sufficient fluidity and strength development cannot be obtained. Alternatively, there is a problem that a large amount of expensive ultrafine powder (particularly silica fume) and expensive admixture (particularly high performance AE water reducing agent) are required.

The present invention solves the above-mentioned conventional problems and provides a method for easily preparing ultra-high strength concrete in a method for producing high-strength concrete by mixing ultra-fine powder, and an ultra-fine powder mixture therefor. To aim.
Further, the present invention significantly reduces the required amount of ultrafine powder and admixture, provides an ultrahigh-strength concrete at low cost, and reduces the amount of kneading water to provide an ultrahigh-strength concrete having higher strength. The purpose is to do.

[0006]

The method for preparing ultra-high-strength concrete according to claim 1 includes cement, coarse aggregate, fine aggregate,
In a method for preparing ultra-high strength concrete by kneading water, an admixture and ultrafine powder, an ultrafine powder and water are mixed to form a slurry, and cement, fine aggregate and coarse aggregate are added to the slurry. It is characterized by being mixed and kneaded. In this preparation method, the timing of adding the admixture is not limited.

The method for preparing ultra-high-strength concrete according to claim 2 is a method for preparing ultra-high-strength concrete by kneading cement, coarse aggregate, fine aggregate, water, an admixture and ultra-fine powder. The ultrafine powder and water are mixed to form a slurry, and cement and coarse aggregate are added to the slurry and kneaded. In this preparation method, the timing of adding the admixture is not limited.

The method for preparing ultra-high-strength concrete according to claim 3 is a method for preparing ultra-high-strength concrete by kneading cement, coarse aggregate, fine aggregate, water, an admixture and ultrafine powder. The fine aggregate, ultrafine powder, and water are mixed to form a slurry, and cement is added to the slurry and kneaded. In this preparation method, the timing of adding the admixture is not limited.

The ultrafine powder mixture according to claim 4 is characterized in that it comprises a slurry-like material in which fine aggregate, ultrafine powder and water are mixed. An admixture may be added to this slurry.

The ultrafine powder mixture according to a fifth aspect is characterized by comprising a slurry-like material in which coarse aggregate, fine aggregate, ultrafine powder and water are mixed. An admixture may be added to this slurry.

The present invention will be described in detail below.

In the method of the first aspect of the present invention, ultrafine powder and water are sufficiently mixed to form a slurry, and cement, fine aggregate and coarse aggregate are added to the slurry and kneaded.

In the method of claim 2 of the present invention, fine aggregate, ultrafine powder and water are mixed to obtain a slurry-like material according to claim 4 of the present invention, and cement and coarse aggregate are added to the slurry-like material. Add and knead.

In the method of claim 3 of the present invention, the coarse aggregate, the fine aggregate, the ultrafine powder and water are mixed and the mixture of claim 5 of the present invention is used.
The slurry-like material according to (1) is added, and cement is added to the slurry-like material and kneaded.

In the method of the present invention as described above, the mixing ratio of cement, ultrafine powder, fine aggregate, coarse aggregate, and water is in the same range as that of the conventional ultrahigh-strength concrete mixing, but kneading water or mixing The amount of agent and the amount of ultrafine powder can be reduced as compared with the conventional one. Usually, in the present invention, it is preferable to adopt the following blending ratio.

Cement containing ultra high strength concrete : 100 parts by weight Ultra fine powder: 2 to 20 parts by weight Fine aggregate: 80 to 200 parts by weight Coarse aggregate: 80 to 200 parts by weight Admixture: 0.1 to 20 parts by weight Water Therefore, the ultrafine powder mixture of the present invention is preferably a slurry-like product in which ultrafine powder, water, and fine aggregate, or coarse aggregate is further mixed so as to have the above mixing ratio. .

As a mixing method for preparing the slurry-like material of the present invention, there can be adopted a mixing method using a powerful mixer, a ball mill mixing method, a mixing method using an ultrasonic vibrator, a mixing method using a shaker and the like. The ultrafine powder mixture may contain an admixture.

In the present invention, the ultrafine powder has a particle size of 1
Silica fume, finely ground blast furnace slag, finely ground limestone or the like having a size of not more than μm, especially about 0.1 μm, can be used.

The cement is not particularly limited, and ordinary portland cement, fast-strength portland cement, super fast-strength portland cement, moderate heat portland cement, low heat portland cement, belite type portland cement, blast furnace cement, fly ash cement, many Various kinds of cement such as mixed cement can be adopted.

Further, as the admixture, a water reducing agent containing naphthalene sulfonic acid type, lignin sulfonic acid type, melamine sulfonic acid type and polycarboxylic acid type as a main component, AE water reducing agent, high performance water reducing agent, high performance AE A fluidizing agent such as a water reducing agent or a fluidizing agent can be used.

In the present invention, it suffices if the ultrafine powder is sufficiently mixed with at least water before mixing with cement. For example, in the method of claim 1, the ultrafine powder and a part of water are sufficiently mixed. To the slurry-like substance mixed with
Fine aggregate, coarse aggregate and cement may be added and kneaded. Further, in the method of claim 2, a slurry-like material in which ultrafine powder, a part of water and / or a part of fine aggregate is sufficiently mixed, and the remaining water and / or the remaining fine aggregate and coarse bone are added. Material and cement may be added and kneaded. Similarly, in the method of claim 3, ultrafine powder, part of water, part of fine aggregate and / or
Or to a slurry-like material that is sufficiently mixed with a part of coarse aggregate,
The balance of water, the balance of fine aggregate and / or the balance of coarse aggregate and cement may be added and kneaded.

The concrete prepared according to the invention is
An ultra-high-strength concrete hardened product can be obtained by molding and hardening according to a conventional method.

[0023]

When water is added in advance to ultrafine powder such as silica fume and mixed sufficiently, ultrafine powder particles become a slurry-like substance sufficiently dispersed in water. Then, as compared with the conventional method (procedure) of adding water after mixing the cement and the ultrafine powder, it is possible to obtain a uniform dispersed state without aggregation of the ultrafine powder.

Therefore, with the same composition, higher fluidity than before can be obtained, and workability is greatly improved. By the way, according to the present invention, the viscosity of the fresh concrete can be set to about 2/3 of that of the conventional one, and the fluidity is significantly improved.

Further, according to the present invention, the amount of kneading water and the amount of admixture required to obtain the same fluidity can be greatly reduced as compared with the prior art. Therefore, the cost of the admixture can be reduced. In addition, the strength of the hardened concrete is increased by reducing the amount of kneading water. By the way, according to the present invention, the amount of the admixture used can be set to about 2/3 of the conventional amount, and the strength of the hardened concrete can be improved by about 10% by reducing the amount of kneading water.

Furthermore, according to the present invention, the amount of ultrafine powder required to obtain the same strength is greatly reduced. Therefore, the cost of ultrafine powder can be reduced. Incidentally, according to the present invention, the amount of ultrafine powder used can be set to about 4/5 of the conventional amount.

[0027]

EXAMPLES The present invention will be described more specifically with reference to Examples and Comparative Examples below. For convenience of description, a comparative example will be given first.

The materials used in Examples and Comparative Examples are as follows.

Cement: Mitsubishi ordinary Portland cement Ultrafine powder: Silica fume (average particle size 0.2 μm) Fine aggregate: Crushed sand from Dandoyama, Aichi Prefecture Coarse aggregate: Crushed stone from Dandoyama, Aichi Admixture: NMB Reobuild SP-8N High performance A
E Water Reducing Agent Comparative Example 1 (Conventional method) Concrete was prepared according to the conventional method with the composition shown in Table 1.

That is, cement and ultrafine powder are mixed in advance,
Water to which an admixture was added, fine aggregate and coarse aggregate were added and kneaded.

The fluidity (slump) of the obtained fresh concrete is shown in Table 1. In addition, Table 1 shows the strength of the cured product obtained by molding and curing this fresh concrete.

Example 1 (Method of Claim 1) According to the method of Claim 1 of the present invention, concrete was prepared with the same composition as in Comparative Example 1.

That is, cement, fine aggregate and coarse aggregate were added to a slurry obtained by mixing ultrafine powder, an admixture and water and kneaded.

The fluidity (slump) of the obtained fresh concrete is shown in Table 1. In addition, Table 1 shows the strength of the cured product obtained by molding and curing this fresh concrete.

Example 2 (Method of Claim 2 and Mixture of Claim 4) According to the method of Claim 2 of the present invention, concrete was prepared with the same composition as in Comparative Example 1.

That is, cement and coarse aggregate were added and kneaded to the slurry-like material of claim 4 obtained by mixing ultrafine powder, an admixture, water and fine aggregate.

Table 1 shows the fluidity (slump) of the obtained fresh concrete. In addition, Table 1 shows the strength of the cured product obtained by molding and curing this fresh concrete.

Example 3 (method of claim 3 and mixture of claim 5) According to the method of claim 3 of the present invention, concrete was prepared with the same composition as in Comparative Example 1.

That is, cement was added and kneaded to the slurry-like material of claim 5 obtained by mixing ultrafine powder, an admixture, water, fine aggregate and coarse aggregate.

Table 1 shows the fluidity (slump) of the obtained fresh concrete. In addition, Table 1 shows the strength of the cured product obtained by molding and curing this fresh concrete.

Example 4 (Reduction of Admixture Amount) Concrete was prepared in the same manner as in Example 1 except that the concrete composition was changed to that shown in Table 1, and the fluidity (slump) of the obtained fresh concrete was obtained. Is shown in Table 1. In addition, Table 1 shows the strength of the cured product obtained by molding and curing this fresh concrete.

Example 5 (Reduction of Kneading Water Amount) Concrete was prepared in the same manner as in Example 2 except that the concrete composition was changed to that shown in Table 1, and the fluidity (slump) of the obtained fresh concrete was measured. It shows in Table 1. In addition, Table 1 shows the strength of the cured product obtained by molding and curing this fresh concrete.

Example 6 (Reduction of amount of ultrafine powder) Concrete was prepared in the same manner as in Example 3 except that the concrete composition was changed to that shown in Table 1, and the fluidity (slump) of the obtained fresh concrete was obtained. Is shown in Table 1. In addition, Table 1 shows the strength of the cured product obtained by molding and curing this fresh concrete.

[0044]

[Table 1]

The following is clear from Table 1. That is,
By comparing Comparative Example 1 with Examples 1 to 3, it can be seen that according to the method of the present invention, remarkably good fluidity can be obtained and the workability is improved with the same composition as compared with the conventional method.

Further, by comparing Comparative Example 1 with Examples 4 and 5, according to the present invention, the amount of admixture and the amount of kneading water necessary for obtaining the same fluidity are reduced, and the admixture cost is reduced. It can be seen that the cost can be reduced and the strength of the obtained hardened concrete is improved.

Further, by comparing Comparative Example 1 with Example 6, according to the method of the present invention, the amount of ultrafine powder required to obtain the same strength can be reduced, and the cost of ultrafine powder can be reduced. I understand.

[0048]

As described in detail above, according to the method for preparing ultra-high-strength concrete and the mixture of ultra-fine powder of the present invention, in the preparation of ultra-high-strength concrete by adding ultra-fine powder, the fluidity is improved. Improved workability and lower construction cost. Lowering the cost of admixture by reducing the required amount of water reducing agent. Improves the strength of the cured product by reducing the required amount of kneading water. Reduction of ultrafine powder cost by reducing required amount of ultrafine powder. It is possible to easily and efficiently prepare ultra-high-strength concrete having extremely high strength at low cost with good workability.

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Claims (5)

[Claims] 1. A method for preparing ultra-high strength concrete by kneading cement, coarse aggregate, fine aggregate, water, an admixture and ultrafine powder, in which ultrafine powder and water are mixed to form a slurry. A method for preparing ultra-high-strength concrete, which comprises adding cement, fine aggregate and coarse aggregate to a slurry and kneading the mixture. 2. A method for preparing ultra high strength concrete by kneading cement, coarse aggregate, fine aggregate, water, an admixture and ultrafine powder, which comprises mixing fine aggregate, ultrafine powder and water into a slurry form. A method for preparing ultra-high strength concrete, characterized by adding cement and coarse aggregate to this slurry and kneading. 3. A method for preparing ultra-high strength concrete by kneading cement, coarse aggregate, fine aggregate, water, admixture and ultrafine powder, wherein coarse aggregate, fine aggregate, ultrafine powder and water are mixed. A method for preparing ultra-high-strength concrete, comprising: adding a cement to this slurry-like material and kneading. 4. An ultrafine powder mixture for producing ultrahigh-strength concrete, which comprises a slurry-like material in which fine aggregate, ultrafine powder and water are mixed. 5. An ultrafine powder mixture for producing ultrahigh strength concrete, comprising a slurry-like material in which coarse aggregate, fine aggregate, ultrafine powder and water are mixed.