JP2002012464A - High-fluidity high-strength concrete - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide high-fluidity and high-strength concrete, compressive strength of which is manifested by >=70 N/mm2 and amount of self-shrinkage can be reduced. SOLUTION: The high-fluidity and high-strength concrete is characterized in that the main minerals are 3CaO.SiO2-2CaO.SiO2-CaO-interstitial material, 3CaO.SiO2-CaO-interstitial material, 2CaO.SiO2-CaO-interstitial material, or CaO-interstitial material, and admixture consisting of ground mixture of clinker composition containing 50-92 wt.% CaO crystal and gypsum, or the ground mixture of the clinker composition of quick lime and the gypsum, cement whose weight decreasing quantity is 0.7-2.5 wt.% measured by thermogravimetric measurement from 20 deg.C to 500 deg.C, water reducing agent, fine aggregate, coarse aggregate and water, the total amount of the cement and the admixture is 500-700 kg/m3, the ratio of water/cement is 25-35 wt.%, slump flow value is 50-80 cm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a high-flow high-strength concrete exhibiting a compressive strength of 70 N / mm ² or more, and more particularly to a high-flow high-strength concrete having a small amount of self-shrinkage after hardening.

[0002]

2. Description of the Related Art In recent years, from the viewpoint of more effective use of land, the tendency of buildings to become super-high-rise or large-scale has been increasingly remarkable. In the construction work of such a super-high-rise or large-scale building, from the viewpoint of shortening the construction period, labor saving of construction, eliminating construction defects, etc., it is excellent in fluidity and material separation resistance and has high strength ( Compressive strength 70N / mm ²
High fluidity concrete that expresses the above) is required. Further, in view of also reducing noise caused by vibration compaction in concrete products factory, excellent fluidity and material separation resistance, and high flow concrete is required to express the high-strength (compressive strength 70N / mm ² or higher) ing.

[0003] Conventionally, as high-fluid concrete, 1) high-fluid concrete usually referred to as a thickener system using a water-soluble polymer having a thickening action, and 2) a large amount of cement in concrete (for example, , 500k
g / m ³ or more), and using a water reducing agent (such as a high performance water reducing agent or a high performance AE water reducing agent) to reduce the water / cement ratio (for example,
35% by weight or less), a high-fluidity concrete usually called a powder type.

[0004]

SUMMARY OF THE INVENTION The above thickener-based high-fluid
In concrete, the amount of cement
Is 400 ~ 500kg / m^ThreeWater / cement ratio is about 40-50% by weight
Often it is. Therefore, the thickener-based high fluid conc
For REET, 70N / mm^TwoDeveloping the above compressive strength
It was difficult. On the other hand, powdery high-fluidity concrete
Excellent in mobility and material separation resistance, 70 N / mm ^TwoAbove high strength
It can be expressed, but on the other hand,
Hardening due to high volume and small water / cement ratio
There has been a problem that the subsequent self-shrinkage becomes large. This
For concrete with large self-shrinkage, for example, RC
When used for a member, the size of the lower edge of the member
Strong tensile stress, which may cause mechanical problems.
Is pointed out.

[0005]

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, the thermogravimetric measurement has been conducted.
If the weight loss from 20 ° C. to 500 ° C. is a high range concrete of a specific mixing ratio using a cement and a specific admixture in a specific range, even if the compressive strength of 70 N / mm ² or more, The inventors have found that the amount of self-shrinkage can be reduced, and have completed the present invention. That is, the present invention is the main mineral _{3CaO · SiO 2 -2CaO · SiO 2} -CaO- gap material, 3CaO · SiO ₂ -CaO- gap material, in 2CaO · SiO ₂ -CaO- gap material or CaO- gap material , And CaO crystals 50-92
A mixture and a mixture of a clinker composition and gypsum, or an admixture of a mixture and a mixture of calcined lime and gypsum, containing 20% by weight of thermogravimetry.
Cement with a weight loss of up to 500 ° C of 0.7 to 2.5% by weight, a water reducing agent, fine aggregate, coarse aggregate, and water, and the total amount of cement and admixture is 500 to 700 kg / m ^3. A high-flow, high-strength concrete having a water / cement ratio of 25 to 35% by weight and a slump flow value of 50 to 80 cm (Claim 1). And the compounding amount of the admixture is 1 to 60 kg / m ³
Is preferable (claim 2).

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. The cement used in the present invention is measured by thermogravimetry.
The weight loss from 20 ° C. to 500 ° C. is 0.7 to 2.5% by weight, preferably 1.0 to 2.2% by weight. By using a cement whose weight loss by thermogravimetry is in the above range, even if the compressive strength is 70 N / mm ² or more, the amount of self-shrinkage after curing can be reduced. 20 by thermogravimetry
Cement with a weight loss of less than 0.7% by weight from 0 ° C to 500 ° C is not preferred because it becomes difficult to reduce the amount of self-shrinkage after curing. 20 ℃ to 500 by thermogravimetry
Cement with a weight loss of more than 2.5% by weight up to ° C. is not preferred because strength developability is reduced and it becomes difficult to develop a compressive strength of 70 N / mm ² or more. Note that the thermogravimetry may be performed using a commercially available thermogravimeter. The heating rate is preferably 10 to 20 ° C / min.

As the cement whose weight loss from 20 ° C. to 500 ° C. by the thermogravimetry is 0.7 to 2.5% by weight, for example, commercially available Portland cements such as ordinary, early-strength, and moderately hot Portland cements can be used. Examples include hydrotreated cement in which water is retained by spraying water while spraying at a high speed and / or spraying steam, and cement crushed while spraying water when crushing cement clinker and gypsum with a finishing mill. Can be

The admixture used in the present invention has a main mineral of 3C
aO ・ SiO ₂ −2CaO ・ SiO ₂ −CaO− interstitial material, 3CaO ・ SiO ₂ −C
aO- gap material is 2CaO · SiO ₂ -CaO- gap material or CaO- gap material and clinker composition containing 50-92 wt% of CaO crystalline and ground mixture of gypsum, or the clinker composition with quicklime And a mixed and ground product with gypsum.

The clinker composition in the admixture contains at least CaO crystals and interstitial materials as main minerals,
It is a pulverized clinker composition that may or may not contain (3CaO.SiO ₂ ) and / or belite (2CaO.SiO ₂ ), and contains 50 to 92% by weight of CaO crystals. By including at least CaO crystals and interstitial materials as main minerals, the effect of reducing the self-shrinkage of high-flow high-strength concrete without impairing workability can be obtained. When the CaO crystal in the clinker composition is less than 50% by weight,
The effect of reducing the self-shrinkage of high-flow high-strength concrete is reduced, which is not preferable. If the CaO crystals in the clinker pulverized material exceed 92% by weight, workability deteriorates, which is not preferable. The interstitial material is similar to a mineral that fills a space between alite and belite in cement clinker minerals. Specifically, calcium ferrite minerals such as 2CaO.Fe ₂ O ₃ and 3CaO.Al ₂ O ₃ calcium aluminate mineral _{or,, 6CaO · Al 2 O 3} · Fe 2 O 3, 4CaO · Al 2 O 3
· Fe ₂ O _3, calcium alumino ferrite minerals such as _{6CaO · 2Al 2 O 3 · Fe} 2 O 3.

The clinker composition is obtained by mixing calcareous raw materials, clay raw materials, silica stones, slags, gypsum, etc., and sufficiently mixing the raw material mixture with a rotary kiln at a temperature of 1300 to 1600 ° C. until a desired clinker mineral is obtained. It is manufactured by baking and firing.

The type of gypsum in the admixture is not limited, and anhydrous gypsum, hemihydrate gypsum and gypsum can be used.
Preferably, anhydrous gypsum is used. The amount of gypsum in the admixture is
When the admixture is a two-component system of a clinker composition and gypsum, 5 to 50 parts by weight of gypsum is appropriate for 100 parts by weight of the clinker composition. When the admixture is a ternary system of a clinker composition, quick lime, and gypsum, 5 to 50 parts by weight of gypsum is appropriate based on 100 parts by weight of the total amount of the clinker composition and quick lime. If the amount of gypsum in the admixture is less than the above range, the effect of reducing the self-shrinkage of the high-flow high-strength concrete is undesirably reduced. If the amount of the gypsum is larger than the above range, the high-flow high-strength concrete is not preferred because there is a fear that the strength may be reduced due to expansion cracks.

By blending quicklime into the admixture,
The self-shrinkage of high-flow high-strength concrete can be reduced. The type of quicklime is not limited,
Soft lime such as soft burnt lime, medium burnt quick lime, hard burned quick lime, and extremely hard burned quick lime can be used. It is preferable to use quicklime, and it is more preferable to use quicklime of 400 ml or less.

The amount of quick lime in the admixture is suitably less than 400 parts by weight per 100 parts by weight of the clinker composition, that is, less than 80% by weight of quick lime in the total amount of the clinker composition and quick lime. If the amount of quicklime in the admixture is more than the above range, the workability deteriorates, which is not preferable.

The admixture is composed of a mixed and crushed product of the above-mentioned clinker composition and gypsum or a mixed and crushed product of the above-mentioned clinker composition, quicklime and gypsum. It may be crushed after mixing. Moreover, the individually pulverized material may be put into a mixer together with other materials at the time of kneading the high-flow high-strength concrete. Ball mill,
A pulverizer such as a roll mill can be used. Fineness of admixtures, preferably 3000 cm ² / g or more in Blaine specific surface area, 4000~8000cm ² / g is more preferable. If the admixture has a brane specific surface area of less than 3000 cm ² / g, the effect of reducing the self-shrinkage of the high-flow high-strength concrete is undesirably reduced.

Materials other than the cement and the admixture used in the present invention will be described. As fine aggregate, river sand, land sand, sea sand,
Crushed sand or a mixture thereof can be used. As the coarse aggregate, river gravel, mountain gravel, sea gravel, crushed stone, or a mixture thereof can be used. As the water reducing agent, a lignin-based, naphthalene sulfonic acid-based, melamine-based, polycarboxylic acid-based water reducing agent, an AE water reducing agent, a high performance water reducing agent, or a high performance AE water reducing agent can be used. In the present invention, it is preferable to use a high performance water reducing agent or a high performance AE water reducing agent having a large water reducing effect. As the water, tap water or the like can be used. In the present invention, if necessary, an air entraining agent, an antifoaming agent, an admixture such as a thickener, blast furnace slag powder, fly ash, limestone powder, silica fume and the like are used as long as they do not cause any trouble. That is fine.

The high-flow high-strength concrete of the present invention has a total amount of cement and admixture of 500 to 700 kg / m ³ , a water / cement ratio of 25 to 35% by weight, and a slump flow value of 50 to 80 cm. is there. If the high-flow high-strength concrete under the above conditions, the flowability and material separation resistance are excellent, and 70 N / mm ²
The above compressive strength can be exhibited, and the amount of self-shrinkage after curing can be reduced. In the present invention, the total amount is less than 500 kg / m ³ of cement and admixture, 70N / mm ²
It is not preferable because it is difficult to develop the above compressive strength. If the total amount of cement and admixture exceeds 700 kg / m ³ , it becomes difficult to reduce the amount of self-shrinkage after curing, which is not preferable. In addition, when the water / cement ratio is less than 25% by weight, the slump flow value is less than 50 cm. For example, in the construction of a building, it is possible to shorten the construction period, save labor in the construction, and eliminate construction defects. It is not preferable because it becomes difficult. If the water / cement ratio exceeds 35% by weight, 70
It is difficult to develop a compressive strength of N / mm ² or more, which is not preferable. Also, if the slump flow value is less than 50 cm,
For example, in the construction of buildings, shortening the construction period,
It is not preferable because labor saving of construction and elimination of construction defects become difficult, and it is difficult to reduce noise due to vibration compaction even in a concrete product factory. If the slump flow value exceeds 80 cm, the material separation resistance is undesirably reduced.

[0017] In the high flow and high strength concrete of the present invention, the amount of admixture, from the viewpoint of workability and self-shrinkage reducing, preferably ^{1~60kg / m 3, 5~55kg / m} 3 and more preferably. If the amount of the admixture is less than 1 kg / m ³ , the effect of reducing the self-shrinkage of the high-flow high-strength concrete is undesirably small. If the mixing amount of the admixture exceeds 60 kg / m ³ , workability is deteriorated, and high-flow high-strength concrete is not preferred because it may cause a decrease in strength due to expansion cracks.

In the high-flow high-strength concrete of the present invention, the total amount of cement and admixture is 500 to 700 kg / m ³ , the amount of admixture is preferably 1 to 60 kg / m ³ , and the water / cement ratio is 25 to
If the slump flow value is 35 to 80 cm and the slump flow value is 50 to 80 cm, the water reducing agent / cement ratio and the absolute volume of unit coarse aggregate are not particularly limited. (Solid content conversion) / cement ratio is 0.3 ~
2.0 wt%, the unit coarse aggregate absolute volume is preferably set to 0.27~0.36m ³ / m ^3.

The method and apparatus for kneading the high-flow high-strength concrete of the present invention are not particularly limited, and they may be kneaded by a conventional method using a conventional mixer. In addition, the curing method is not particularly limited, and aerial curing, underwater curing,
Steam curing may be performed.

[0020]

The present invention will be described below with reference to examples. 1. Materials used The following materials were used. 1) Cement Cement A: A normal portland cement manufactured by Taiheiyo Cement Co., Ltd. was charged into a twin-screw kneader, and a water-treated cement was used with stirring and an ultrasonic humidifier.
The weight loss of the cement from 20 ° C. to 500 ° C. by thermogravimetry was 1.3% by weight. Cement B: Ordinary Portland cement manufactured by Taiheiyo Cement Co., Ltd. was used. By thermogravimetry of the cement
The weight loss from 20 ° C. to 500 ° C. was 0.6% by weight.

2) Admixture Preparation of clinker composition Limestone, silica stone, clay, iron raw material and anhydrous gypsum are mixed so as to have a mineral composition shown in Table 1, and the mixture is kept in a rotary kiln at a sintering temperature of 1300 to 1600 ° C. Baking for 60 to 120 minutes to produce clinker, which is
Milled to 5000 cm ² / g.

[0022]

[Table 1]

Preparation of admixture 100 parts by weight of the above clinker composition and 10 parts by weight of anhydrous gypsum (Brain specific surface area: 6500 cm ² / g) were mixed to prepare an admixture.

The following materials were used as materials other than cement and admixtures. 3) A high-performance AE water reducing agent; Leobuild SP-8S (manufactured by NMB) was used. 4) Fine aggregate: Land sand from Shizuoka Prefecture (surface dry specific gravity: 2.60) was used. 5) Coarse aggregate; crushed stone from Ibaraki Prefecture (surface dry specific gravity: 2.64) was used. 6) Water; tap water was used.

2. Mixing and kneading of concrete Concrete was prepared according to the mixing shown in Table 2 using the above materials. The kneading is performed by a 2-axis forced kneading mixer (0.06
The mixture was kneaded for 180 seconds using m ³ ).

[0026]

[Table 2]

3. Evaluation 1) Slump flow value After pulling up a slump cone in accordance with "JIS A 1101 (Slump test method for concrete)", measure the length of the maximum diameter of the spread concrete and the length in the direction perpendicular to it, and calculate the average value. Was calculated, and a slump flow value was obtained. 2) Compressive strength After kneading, molding was performed using a mold having a diameter of 10 x 20 cm. After molding,
Cured for one day in the mold and demolded. Thereafter, the specimen was cured in water until the age of 28 days, and the compressive strength was measured according to “JIS A 1108 (Method of testing compressive strength of concrete)”. 3) Autogenous shrinkage The autogenous shrinkage of the above concrete (material age 28 days) was measured according to the Japan Concrete Institute Association (tentative name) Autogenous shrinkage test method of high fluidity concrete. The measurement was based on the starting time of the setting. Table 3 shows the results.

[0028]

[Table 3]

As is clear from Table 3, in the high-flow high-strength concrete specified in the present invention, the amount of self-shrinkage was small even at a compressive strength of 70 N / mm ² or more.

[0030]

As described above, the high-flow high-strength concrete of the present invention can exhibit a compressive strength of 70 N / mm ² or more and can reduce the amount of self-shrinkage. Therefore, by using the high-flow high-strength concrete of the present invention, for example, in the construction work of a building, it is possible to shorten the construction period, save labor in the construction, and eliminate construction defects. Also, noise reduction due to vibration compaction can be achieved in a concrete product factory.
Furthermore, using the high-flow high-strength concrete of the present invention,
For example, when an RC member is manufactured, there is little possibility that a mechanical adverse effect occurs.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) C04B 22:06 C04B 22:06 Z 22:08 22:08 A 22:14 22:14 B 24:26 24:26 E 14:06) 14:06) Z 103: 30 103: 30 111: 20 111: 20 (72) Inventor Keiji Omori 2-4-2 Daisaku, Sakura-shi, Chiba F-term in the Central Research Institute, Pacific Cement Co., Ltd. Reference) 4G012 MB01 MB23 PA01 PA04 PA06 PB03 PB06 PB11 PC02 PC03 PC12

Claims (2)

[Claims] The main mineral is 3CaO.SiO_Two−2CaO ・ SiO_Two−Ca
O-interstitial material, 3CaO ・ SiO _Two−CaO− interstitial material, 2CaO ・ SiO_Two
-CaO- interstitial material or CaO- interstitial material, and
Of clinker composition containing 50-92% by weight of gypsum and gypsum
Crushed material, or the above clinker composition and quicklime and stone
And an admixture consisting of a ground mixture with
The weight loss from 20 ° C to 500 ° C is 0.7-2.5% by weight.
Some cement, water reducer, fine aggregate, coarse aggregate, and water
Including, the total amount of cement and admixture is 500-700kg / m^Three, Water / seme
Weight ratio is 25-35% by weight and slump flow value is 50-80cm
A high-flow, high-strength concrete characterized by being: 2. The high-flow high-strength concrete according to claim 1, wherein the amount of the admixture is 1 to 60 kg / m ³ .