JP2001206754A - Highly flowable concrete - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the highly flowable concrete having a high water-to-binder ratio and exhibiting 15-30 N/mm2 compressive strength and with the freshness hardly affected by the used material. SOLUTION: This highly flowable concrete contains a cement-base binder, limestone powder, thin aggregate, coarse aggregate, a water reducing agent, a water-soluble polymer having a thickening action and water and exhibits 15-30 N/mm2 compressive strength.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a high water-binding material ratio.
Relates high fluidity concrete expressing compressive strength of 15 to 30 N / mm ^2, in particular, it relates to a high fluidity concrete less susceptible to material fresh properties are used.

[0002]

2. Description of the Related Art In recent years, the density of reinforcing bars has been increased due to an increase in size and complexity of a structure, and an increase in labor in construction and generation of construction defects have become problems. For this reason, fluidity and material separation are considered from the viewpoint of shortening the construction period, labor saving and eliminating construction defects in construction work, and reducing noise due to vibration compaction in concrete product factories. The use of highly fluid concrete with excellent resistance has been promoted.

[0003] The high-fluid concrete includes 1) high-fluid concrete usually referred to as a thickener, which uses a water-soluble polymer having a thickening effect, and 2) cement, blast furnace slag powder, silica fume and the like in concrete. There is known a high-fluidity concrete generally called a powder type in which the amount of binder is increased and the ratio of water binder is reduced.

[0004]

The thickener-based high-fluidity concrete and powder-type high-fluidity concrete have a relatively low water binder ratio of about 30 to 50%, and thus have a compressive strength of 40 N / N. mm ² or more are many things had become as having excessive performance compared to design strength, which is commonly used. In order to solve the problem related to the strength, Japanese Patent Application Laid-Open No. 10-29849 discloses a limestone fine powder having a specific specific surface area, a specific coarse aggregate, a binder containing cement, and specific mixing conditions composed of water. High fluidity concrete is disclosed. The high fluidity concrete has a compressive strength of about 24 N / mm ² .

However, in the high-fluidity concrete disclosed in JP-A-10-29849, the water binder ratio is high (65% or more), so that the fresh properties are easily affected by the material used, for example, particle size distribution and shape. When different aggregates are used, there is a problem that the fluidity and the material separation resistance are different even under the same blending condition.

Therefore, in the present invention, the ratio of the water binder
In the high fluidity concrete expressing compressive strength of ~30N / mm ^2, it is an object to provide a material less susceptible high fluidity concrete of the fresh properties are used.

[0007]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, in a high fluidity concrete having a high water binder ratio, a limestone powder and a water-soluble polymer having a thickening effect have been obtained. The present inventors have found that the above-mentioned problems can be solved by using in combination, and have completed the present invention.

That is, the present invention comprises a cement binder, limestone powder, fine aggregate, coarse aggregate, a water reducing agent, a water-soluble polymer having a thickening action, and water, and has a compression of 15 to 30 N / mm ² . It is a high-fluid concrete characterized by exhibiting strength (claim 1). In the high fluidity concrete, the slump flow is preferably 50 to 70 cm (Claim 2), and the volume ratio of limestone powder / (cement-based binder + limestone powder) is 0.1 to 100 cm.
0.4 is preferable (claim 3), and the compounding amount of the water-soluble polymer having a thickening action is preferably 0.05 to 0.5 kg / m ³ (claim 4).

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. The present invention, cementitious binder, limestone powder, fine aggregate, coarse aggregate, comprising a water-soluble polymer and water with water-reducing agent, a thickening action, high expressing compressive strength of 15 to 30 N / mm ² It is fluid concrete. If the compressive strength is less than 15 N / mm ² , the strength becomes lower than the nominal strength specified in “JIS A 5308 (ready mixed concrete)”, which is not preferable. When the compressive strength exceeds 30 N / mm ² , it has an excessive performance as compared with a generally used design standard strength, which is not preferable.

The cement-based binder used in the present invention includes various portland cements such as ordinary portland cement, early-strength portland cement, moderately heated portland cement, low-heat portland cement, and mixed cements such as blast furnace cement and fly ash cement. Examples thereof include those obtained by replacing part of the portland cement or the mixed cement with a latent hydraulic powder and / or a pozzolanic powder. Here, blast furnace slag and the like are used as the latent hydraulic powder, silica fume is used as the pozzolanic powder,
Examples include silica dust, fly ash, slag, volcanic ash, silica sol, precipitated silica, and the like.

In the present invention, the cement-based binder preferably has a Blaine specific surface area of 2500 to 7000 cm ² / g. Brain specific surface area of cement binder is 2500cm ² / g
If it is less than 1, the material separation resistance is undesirably reduced.
It is not preferable that the specific surface area of the cement-based binder exceeds 7000 cm ² / g because the fluidity decreases. The amount of cementitious binder, 200~330kg / m ³ is preferred. If the amount of the cement-based binder is less than 200 kg / m ³ , strength development is undesirably reduced. The amount of cement-based binder
If it exceeds 330 kg / m ³ , it has an excessive performance (strength) as compared with a generally used design standard strength, which is not preferable.

The limestone powder used in the present invention preferably has a Blaine specific surface area of 3000 to 10000 cm ² / g. If the limestone powder has a Blaine specific surface area of less than 3000 cm ² / g, the fluidity decreases, which is not preferable. The specific surface area of the limestone powder
If it exceeds 10,000 cm ² / g, the cost for pulverization increases, which is not preferable. The amount of the limestone powder is as follows:
0.1 to 0.4 by volume ratio of (cement-based binder + limestone powder)
Is preferred. When the amount of the limestone powder is outside the above range,
It is not preferable because fluidity is reduced and strength developability is reduced.

The fine aggregate and coarse aggregate used in the present invention are not particularly limited. Examples of the fine aggregate include river sand, sea sand, and sand.
Mountain sand, crushed sand and mixtures thereof, lightweight fine aggregate, blast furnace slag fine aggregate, and the like can be given. Examples of the coarse aggregate include river gravel, sea gravel, crushed stone and mixtures thereof, lightweight coarse aggregate, blast furnace slag coarse aggregate, and the like. In the present invention, the unit coarse aggregate volume is preferably 0.28~0.33m ³ / m ^3. Unit coarse aggregate volume is difficult to adjust to an appropriate unit quantity of water or fine aggregate rate is less than 0.28m ³ / m ^3, the unit coarse aggregate volume is the fluidity exceeds 0.33 m ³ / m ³ Both are not preferred because they decrease. In the present invention, in order to obtain a suitable fine aggregate ratio, the fine aggregate amount is preferably 735 to 1200 kg / m ³ .

Examples of the water reducing agent used in the present invention include alkyl allyl sulfonic acid type, naphthalene sulfonic acid type, melamine sulfonic acid type and polycarboxylic acid type water reducing agents, AE
Water reducing agents, high-performance water reducing agents, and high-performance AE water reducing agents. The water reducing agent can be used in either liquid or powder form. The compounding amount of the water reducing agent is preferably 0.03 to 0.7% in terms of solid content based on the cement binder. If the amount of the water reducing agent is less than 0.03% in terms of the solid content with respect to the cement-based binder, the fluidity is undesirably reduced. If the amount of the water reducing agent exceeds 0.7% in terms of solid content with respect to the cement-based binder, the material separation resistance is undesirably reduced.

The water-soluble polymer having a thickening effect used in the present invention includes polyacrylamide, a copolymer of N-methylacrylamide and a specific acrylic monomer (specifically, JP-A-9-132444). Water-soluble polymer disclosed in No. 1), poly (N-vinylacetamide), carboxymethylcellulose and the like. In the present invention, a commercially available thickener or separation reducing agent containing the water-soluble polymer may be used. The compounding amount of the water-soluble polymer is 0.05 to 0.5 kg /
m ³ is preferred, and 0.1 to 0.4 kg / m ³ is more preferred. If the blending amount of the water-soluble polymer is less than 0.05 kg / m ³ , the fresh properties are easily affected by the material used, and the separation resistance of the material is undesirably reduced. If the amount of the water-soluble polymer is more than 0.5 kg / m ³ , the viscosity becomes too large and the fluidity decreases, which is not preferable.

In the present invention, the amount of water is preferably from 150 to 185 kg / m ³ . If the amount of water is less than 150 kg / m ^3, it has an excessive performance (strength) as compared with a generally used design standard strength, which is not preferable. If the amount of water exceeds 185 kg / m ³ , the material separation resistance is undesirably reduced.

In the present invention, the slump flow of the high fluidity concrete is preferably 50 to 70 cm. Slump flow is
If it is less than 50 cm, the fluidity is low, so it is difficult to shorten the construction period, save labor and eliminate construction defects in construction work, and it is difficult to reduce noise by vibration compaction in concrete product factories. Not preferred. If the slump flow exceeds 70 cm, the material separation resistance is undesirably reduced.

In the present invention, the method of kneading the high-fluidity concrete is not particularly limited, but from the viewpoint of shortening the kneading time, a cement-based binder, limestone powder and a water-soluble polymer having a thickening action are used. Are preferably mixed in advance. As the mixer, a conventional mixer may be used.
The curing conditions are not particularly limited.

In the present invention, a known concrete admixture such as an AE agent, an antifoaming agent, a setting retarder, an accelerator, a shrinkage reducing agent, a rust preventive, a foaming agent, an expanding agent, etc., within a range not to impair the purpose. Can be added.

[0020]

Test Examples Hereinafter, the present invention will be described with reference to test examples. 1. Materials used The following materials were used. Cement-based binder; ordinary Portland cement (manufactured by Taiheiyo Cement Co., Ltd.) Limestone powder; limestone powder manufactured by Taiheiyo Cement Co., Ltd. (Brain specific surface area: 5000 cm ² / g) Water reducing agent; Polycarboxylic acid-based high-performance AE water reducing agent N-methylacrylamide / 2-acrylamide-2-methylpropane sodium sulfonate
80/20 (molar ratio) copolymer Coarse aggregate; crushed stone from Iwase Water; tap water

The composition of the concrete is shown in Table 1. The concrete was kneaded for 120 seconds using a biaxial forced kneading mixer (0.1 m ³ ).

[0022]

[Table 1]

The following 1) to the above concrete
The characteristics of 2) were measured. 1) Slump flow: The slump flow of the concrete immediately after kneading and after 60 lapses from the kneading is determined by raising the slump cone in accordance with "JIS A1101 (Slump test method for concrete)".
The length of the maximum diameter of the expanded concrete and the length in the direction perpendicular thereto were measured, and the average value was calculated. In addition, the presence or absence of material separation was checked by visual observation of the expanded concrete. 2) Compressive strength: The compressive strength of a standard cured cured product (φ10 × 20 cm) at a material age of 28 days was measured according to “JIS A1108 (Method of testing compressive strength of concrete)”. The results are shown in the table.

[0024]

[Table 2]

As is evident from Table 2, in the high fluidity concrete of the present invention, even when the water binder ratio was high, the fresh properties were hardly affected by the materials used. On the other hand, in Test Example 16 in which limestone powder was not blended, the fluidity was low.
In Test Examples 17 and 18 in which a water-soluble polymer having a thickening effect was not added, fresh properties were affected by the materials used, and slight material separation was observed.

[0026]

As described above in detail, the high fluidity concrete of the present invention is a mixture of limestone powder and a water-soluble polymer having a thickening effect. As a result, even if the water binder ratio is high, The fresh properties are less affected by the materials used. In addition, the high fluidity concrete of the present invention
~30N / mm is intended to express the compressive strength of ^2, generally an excess compared to the design strength, which is used in the performance (strength)
There is no fear of becoming.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) C04B 103: 30 C04B 103: 30 103: 44 103: 44 111: 20 111: 20 (72) Inventor Yoshihide Shimoyama Chiba 2-4-2 Daisaku Sakura City Pacific Cement Co., Ltd. Sakura Laboratory F-term (reference) 4G012 PA04 PA10 PA29 PB03 PB31 PB32 PB40

Claims (4)

[Claims] 1. It contains a cement-based binder, limestone powder, fine aggregate, coarse aggregate, a water reducing agent, a water-soluble polymer having a thickening action, and water, and exhibits a compressive strength of 15 to 30 N / mm ^2. High fluidity concrete characterized by the fact that: 2. The highly fluid concrete according to claim 1, wherein the slump flow is 50 to 70 cm. 3. The high fluidity concrete according to claim 1, wherein the volume ratio of limestone powder / (cement-based binder + limestone powder) is 0.1 to 0.4. 4. The high fluidity concrete according to claim 1, wherein the compounding amount of the water-soluble polymer having a thickening action is 0.05 to 0.5 kg / m ³ .