JPH06219809A - Production of self-packing concrete - Google Patents

Abstract

PURPOSE:To densely deposit a concrete over the entire area of a mold flask by mixing a cement, a fine aggregate and a mixing agent for concrete and after adding and kneading water and a water reducing agent, feeding to knead a coarse aggregate in a concrete plant mixer to dispense with or minimize the tamping work at the time of depositing. CONSTITUTION:The mixing agent for concrete is obtained by combining (A) 100 pts.wt. mineral fine powder (e.g. calcium carbonate) 7000-20000cm<2>/g in specific surface area, (B) 1-10 pts.wt. mineral coarse powder (e.g. Portland cement clinker) 500-4000cm<2>/g in specific surface area, (C) 0.26-2 pts.wt. separation reducing agent composed of the cellulose based compound (e.g. water-soluble cellulose ether) and (D) 0.5-25 pts.wt. gypsum anhydrite powder 3000-7000cm<2>/g in specific surface area. The concrete is prepared by sufficiently mixing the cement, the aggregate and the mixing agent for concrete and after that, adding water to knead and adding the water reducing agent (e.g. highly condensed triazine derivative) and kneading again.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing concrete having a good self-filling property, and more particularly, it has a high fluidity with a slump flow value of 45 cm to 72 cm, a good filling property and a high material separation resistance. However, the unit water volume is 14
0 to 195 kg / m ³ , and the water cement ratio is 35%
70% of self-compacting concrete manufacturing method.

[0002]

2. Description of the Related Art Conventionally, when it is attempted to improve the filling property of concrete, the unit water content is increased to make soft concrete, or the unit water content is increased by using an admixture such as a water reducing agent or a fluidizing agent. The slump value was increased without increasing it. However, the above-mentioned soft-mixed concrete causes a large amount of material separation and breathing due to an increase in the amount of water, and also tends to cause defects such as cracks due to drying shrinkage. In the case of fluidized concrete using a water reducing agent or a fluidizing agent, it is difficult to control the construction because the material separation resistance is low, and it is difficult to control the quality of the slump and the slump is large.

[0003]

The object of the present invention is to solve the problems found in the conventional concrete having a large slump value as described above, and to have high self-filling property, fluidity and material separation resistance, The object is to produce a self-compacting concrete that can be cast without performing compaction work or with significantly reduced placement even with members having a complicated shape and dense bar arrangement.

[0004]

The above object is to provide a method for producing a self-compacting concrete according to the present invention, that is, any one of the following (1), (2), (3) and (4). Achieved by (1) A production method comprising adding cement, an aggregate and an admixture for concrete to a mixer of a concrete plant and thoroughly mixing them, and then adding water and a water reducing agent and kneading the mixture. (2) Add cement, fine aggregate and admixture for concrete to the mixer of the concrete plant and mix them well,
Then, a manufacturing method comprising adding water and a water reducing agent to sufficiently knead the mortar, and then adding coarse aggregate to knead the concrete.

(3) Cement, fine aggregate and admixture for concrete were added to a mixer of a concrete plant and mixed well, and then water was added to sufficiently knead the mortar, and then coarse aggregate and reduced water A manufacturing method comprising adding an agent and kneading concrete. (4) Manufacturing in which cement, aggregate, and admixture for concrete are added to a mixer of a concrete plant, they are sufficiently mixed, and then water is added and kneaded, and a water reducing agent is added and the mixture is kneaded again. Method.

In the manufacturing methods (1) to (4), at least one selected from the pan-type forced kneading mixer and the biaxial forced kneading mixer is used as the mixer for the concrete plant, and the concrete is used. (A) Specific surface area of 7,000 to 20,000 cm ² /
Fine powder of mineral matter having a specific surface area of (b) 500 to 40
A substance containing coarse mineral powder having a density of 00 cm ² / g, (c) a separation reducing agent composed of a cellulosic compound, and (d) an anhydrous gypsum powder having a specific surface area of 3000 to 7000 cm ² / g is used.

In particular, the following requirements (i), (ii) and (ii)
When i) is satisfied, the above object is more remarkably achieved. (I) the finely divided mineral material (a) is at least one selected from calcium carbonate and glassy blast furnace slag,
Coarse mineral powder (b) is at least one selected from Portland cement clinker grounds, calcium carbonate and glassy blast furnace slag.

(Ii) the admixture for concrete, the separation reducing agent comprising 1 to 10 parts by weight of the coarse mineral powder (b) and 100 parts by weight of the fine mineral powder (a), and a cellulose compound. (C) 0.26 to 2 parts by weight, and further contains 0.5 to 25 parts by weight of the anhydrous gypsum powder. (iii) As the water reducing agent, a high-performance water reducing agent or a high-performance AE water reducing agent containing a highly condensed triazine derivative or a polycarboxylic acid compound as a main component is used.

The method for producing the self-compacting concrete of the present invention will be described in detail below. As the composition of the self-compacting concrete, cement, aggregate, water, admixture for concrete and water reducing agent are used.

As the type of cement, any of Portland cement, blast furnace cement, silica cement, fly ash cement, etc. defined in JIS may be used. Spheroidized cements such as spheroidized Portland cement, spheroidized blast furnace cement and ASTM type IV may also be used. May be used.

As for the aggregate, any of sand, crushed sand, gravel, crushed stone and the like can be used as long as it meets the JIS standard. Admixtures for concrete used for this compaction-free concrete include (a) mineral fine powder,
A mixture of (b) a mineral coarse powder, (c) a separation reducing agent composed of a cellulosic compound, and (d) an anhydrous gypsum powder, if necessary, is advantageously used.

The fine mineral powder is composed of a mineral phase having no hydraulic property or a mineral phase which hardly forms an initial hydrate, and has a specific surface area of 7,000 to 20,000 cm ² /
Fine powder of g, preferably 7,000 to 12,000 cm ² / g is used. Preferable specific examples of such fine mineral powder include fine powder of calcium carbonate and vitreous blast furnace slag. If the specific surface area of the fine mineral powder used is less than 7,000 cm ² / g, the resulting admixture cannot give the desired high fluidity to concrete, while if it exceeds 20,000 cm ² / g, However, it is difficult to manufacture it with the current technology, and the manufacturing cost is high even if it is intentionally manufactured.

The coarse mineral powder is composed of a hydraulic mineral phase and has a specific surface area of 500 to 4000 cm ^2.
/ G, preferably 1000 to 4000 cm ² / g of coarse powder is used, and as a preferable specific example of such a mineral coarse powder, Portland cement clinker is coarsely pulverized and the particle size is adjusted. Further, it is composed of a mineral phase having no hydraulic property or a mineral phase which hardly forms an initial hydrate, and has a specific surface area of 500 to 4000 cm ² /
g, preferably 1000 to 4000 cm ² / g of coarse powder can be used. Preferred specific examples of such mineral coarse powder include calcium carbonate and glassy blast furnace slag coarse powder.

The coarse mineral powder used has a specific surface area of 500 c.
If it is less than m ² / g or exceeds 4000 cm ² / g, the admixture obtained cannot give the desired high fluidity to concrete. That is, 4000 cm ² /
A specific surface area exceeding g is a general specific surface area of ordinary Portland cement, and when an admixture containing mineral powder having such a specific surface area is added to such Portland cement, each component The effect of the present invention in which the particle size (replaced by the specific surface area) of the particles is made uniform, and the desired high fluidization is obtained cannot be achieved. On the other hand, the specific surface area is 500 cm ^2.
If it is less than / g, good fluidity is obtained, but the quality of the concrete (fillability, etc.) is not stable. The amount of the coarse mineral powder is preferably 1 to 10 parts by weight based on 100 parts by weight of the fine mineral powder.

A cellulose compound is used as the separation reducing agent. Specifically, those containing water-soluble cellulose ether as a main component are preferably used. As the quality of the cellulose compound at the time of use, those in which the separation reducing agent is dissolved in water and the viscosity thereof is about 1000 to 20000 cp (the concentration of the cellulose compound is about 2% by weight) are preferable. The amount of the separation reducing agent is 100
It is preferably 0.26 to 2% by weight with respect to parts by weight.

Anhydrous gypsum powder is useful because it improves the strength development after steam curing. The anhydrous gypsum powder contains anhydrous calcium sulfate (CaSO ₄ ) as a mineral phase in an amount of 90% by weight or more and has a specific surface area of 3000 to 70.
Those having a pressure of 00 cm ² / g, particularly 5000 to 7000 cm ² / g are particularly preferable. A product having a specific surface area within this range is used for the production of ordinary cement and is industrially advantageous. However, if a product having a specific surface area outside this range is produced, the production cost rises considerably. The amount of anhydrous gypsum powder is preferably 0.5 to 25 parts by weight based on 100 parts by weight of the fine mineral powder.

As described above, the admixture for concrete for making a self-compacting concrete by adding and mixing the separation reducing agent, the coarse mineral powder and, if necessary, the anhydrous gypsum fine powder to the fine mineral powder. Is obtained. The amount of admixture for concrete added to concrete varies depending on the aggregate and other materials used, but the total amount of fine mineral powder, coarse mineral powder, separation reducing agent and anhydrous gypsum powder is 10 to 80 kg. / M ³ is preferable. If it is less than 10 kg / m ³ , concrete cannot be given sufficient viscosity and material separation resistance, and 80 kg / m ³
Even if it is added in excess of m ³ , concrete viscosity becomes excessively high and conversely the fluidity of concrete is impaired.

Here, the fine mineral powder, the separation reducing agent, the coarse mineral powder and the anhydrous gypsum powder are individually weighed, and when they are individually added to the mixer, they are uniformly dispersed to obtain uniform concrete. In addition, there was a problem that the mixing time was long and the quality of the concrete was difficult to stabilize. In addition, higher accuracy is required for the weighing device of the plant. However, when these materials are used as an admixture in which they are mixed in advance during the production of concrete, there is an effect that homogeneous concrete can be stably obtained easily within a short time.

The surface water ratio of the fine aggregate can be sufficiently used within the normal range. However, in order to stabilize the quality of concrete, a surface water stabilizer is used to constantly maintain the surface of the fine aggregate. It is more desirable if the water can be controlled at a constant level. As the water-reducing agent, a high-performance water-reducing agent is preferable, and particularly, a high-performance water-reducing agent or a high-performance AE water-reducing agent containing a highly condensed triazine derivative or a polycarboxylic acid compound as a main component is preferable. By adding about 2 to 4% by weight based on the total amount of cement and admixture, the self-filling performance of fresh concrete can be sufficiently exerted and the properties of concrete after hardening can be remarkably improved. In addition,
If necessary, an AE agent and an antifoaming agent can be used in combination.

In the composition of the self-compacting concrete, admixtures such as fly ash, blast furnace slag fine powder and silica fume can be added depending on the application. For self-compacting concrete, add a water reducing agent together with the admixture for concrete as described above, and
0 to 195 kg / m ³ , water cement ratio of 35% to 7
It is prepared by setting the range to 0%.

As described above, the concrete mixed with the admixture for concrete and the water reducing agent is excellent in self-filling property with a slump flow value of 40 to 72 cm, and has high material separation resistance due to its viscosity. Therefore, it is possible to obtain a hardened concrete having high strength, which is densely filled in the entire area of the mold without performing compaction at all in the casting operation or even significantly reducing it.

As a method for producing the self-compacting concrete, any one of the following (1) to (4) is adopted. (1) Cement, aggregate, and admixture for concrete (mineral fine powder, separation reducing agent consisting of cellulosic compound, coarse mineral powder, anhydrous gypsum powder) are thoroughly mixed in a mixer of a concrete plant, and then, Add water and a water reducing agent, and knead sufficiently according to the performance of the mixer. (2) Cement, fine aggregate and admixture for concrete are thoroughly mixed in the mixer of the concrete plant, and then
After adding water and a water-reducing agent to sufficiently knead the mortar, the coarse aggregate is added and sufficiently kneaded according to the performance of the mixer.

(3) Cement, fine aggregate and admixture for concrete are thoroughly mixed in the mixer of the concrete plant, and then water is added to sufficiently knead the mortar,
Add coarse aggregate and water-reducing agent and mix thoroughly according to the performance of the mixer. (4) Cement, aggregate, and admixture for concrete are thoroughly mixed in a mixer of a concrete plant, and then a water reducing agent is added to the concrete that has been kneaded by adding water and kneaded again. As the mixer used in each of the above-described methods for producing a filling concrete, at least one selected from a pan-type forced kneading mixer and a biaxial forced kneading mixer is used. It is difficult to mix self-compacting concrete with other mixers, for example, a tilting type mixer, because the mixing capacity of concrete is low.

[0024]

[Examples] Hereinafter, the composition of the composition produced by the concrete producing method of the present invention will be specifically described with reference to Examples. Example 1 Concrete that does not require compaction was produced by each of the production methods (1) to (4) above, and the properties of the concrete obtained were compared. Table 1 shows the composition of the self-compacting concrete used in the experiment.

[0025]

[Table 1]

Cement is ordinary Portland cement manufactured by Sumitomo Cement, and fine aggregate is land sand from Kashima (specific gravity: 2.64).
Coarse grain ratio: 2.52), coarse aggregate is Iwase with a maximum size of 20 mm (specific gravity: 2.66, coarse grain ratio: 6.77), and the water reducing agent is the high performance water reducing agent Rhobuild NL-4000 manufactured by NMB.
This is based on the highly condensed triazine derivative.

As the admixture for concrete, 82.475% of calcium carbonate fine powder having a specific surface area of 7700 to 9400 cm ² / g as a fine mineral powder, and a specific surface area of 1100 to 2700 cm ² / g as a coarse mineral powder are used. Cement coarse powder (portland cement clinker coarsely crushed) 1.000% by weight, cellulose ether 0.750% by weight (added as powder), anhydrous gypsum powder (content of anhydrous calcium sulfate of 92% by weight) thing)
Was used in a mixture of 15.775% by weight. A 100-liter capacity pan-type forced kneading mixer was used for kneading the concrete. Table 2 shows the compared manufacturing methods, and Table 3 shows the test results of the concrete by each manufacturing method.

[0028]

[Table 2]

[0029]

[Table 3]

As shown in FIG. 1, the slump flow values in Table 3 are as follows. First, a slump cone 2 is placed on an iron plate 1, and self-compacting concrete 3 is poured into the slump cone to fill the slump cone. The cone 2 is vertically and gently pulled up, and at that time, the maximum value of the diameter at which the concrete 3 spreads on the iron plate 1 and the diameter in the direction orthogonal to the maximum value diameter are measured, and the average value thereof is calculated. The slump flow value was used. In addition, regarding the rebar flow time, the 44th
Proceedings of the Annual Meeting of the Japan Society of Civil Engineers Proceedings of the 5th section "Workability of fresh concrete passing through a narrow void".

A strength test specimen for concrete was prepared by pouring the concrete to the upper end of the mold without performing any compaction. As shown in Table 3, no matter which mixing method was used, concrete having high fluidity and filling property could be obtained. Further, the concrete flow-down condition during the reinforcing bar flow-down time measurement test, and the spread condition of the concrete after pulling up the slump cone in the slump flow test, concrete separation by any manufacturing method does not cause material separation, It was confirmed to have high material separation resistance. In addition, it was confirmed that the concrete kneaded by any of the manufacturing methods exhibited sufficient strength.

Further, FIG. 2 shows the results of examining the change with time of the slump flow value of the concrete of sample No. 1 at 20 ° C. As shown in FIG. 2, it was confirmed that the slump flow value with the lapse of time did not substantially decrease from kneading to about 60 minutes.

Example 2 In the same manner as in Example 1, the self-filling concrete was manufactured by changing the type of the mixer with the composition of Table 1, and the properties of the concrete kneaded with the mixers of different types were compared. The types of mixers used for comparison were a pan-type forced kneading mixer (capacity 100 liters) and a biaxial type forced kneading mixer (capacity 10 liters).
0 liters), tilting mixer (4 pieces: 112 liters)
Is. The kneading of concrete was performed by the method shown in Table 4. Table 5 shows the results of evaluation of various properties of the concrete that was kneaded using various mixers.

[0034]

[Table 4]

[0035]

[Table 5]

As shown in Table 5, the self-filling concrete kneaded by the pan-type forced kneading mixer and the twin-screw type forced-mixing mixer has high fluidity and filling property. It was confirmed that the slump flow value was small and sufficient fluidity could not be obtained due to the insufficient kneading ability of.

[0037]

As described above, by using the self-compacting concrete kneaded by the manufacturing method of the present invention, it is possible to carry out no or almost no compaction work in the concrete placing work.
It is possible to densely fill the entire area of the formwork with concrete. As a result, the work of concrete construction can be rationalized, and noise and vibration can be reduced. Further, it is possible to sufficiently cope with concrete pouring in a difficult-to-fill portion such as a complicated shape and dense bar arrangement.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a test method of a slump flow test.

[Explanation of symbols]

 1 iron plate 2 slump cone 3 concrete mix

FIG. 2 is a diagram showing changes over time in the slump flow value of self-compacting concrete.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical indication C04B 22:14 B 2102-4G 14:06 Z 2102-4G 14:28 2102-4G 18:14 A 2102-4G 24:12 A 2102-4G 24:04) 2102-4G (72) Inventor Mitsuo Ochiai 585, Tomicho, Funabashi, Chiba Central Research Institute, Sumitomo Cement Co., Ltd. (72) Inventor Reiji Yasumoto Chiba Central Research Institute, Sumitomo Cement Co., Ltd. 585 Tomimachi, Funabashi, Japan (72) Inventor Kazuhisa Takayama 585 Tomicho, Funabashi, Chiba Central Research Institute, Sumitomo Cement Co., Ltd.

Claims (7)

[Claims] 1. A method for producing a self-compacting concrete which fills the entire area of a mold to form a dense concrete hardened body without performing compaction work or significantly reduces the same, which is a pan-type forced kneading mixer. Cement, aggregate and admixture for concrete are added to the mixer of the concrete plant selected from the two-axis forced kneading mixer and sufficiently mixed, and then water and the water reducing agent are added and kneaded. Further, as the admixture for concrete, (a) fine mineral powder having a specific surface area of 7,000 to 20,000 cm ² / g, and (b) a specific surface area of 500 to 4,000.
Coarse mineral powder of cm ² / g, (c) Separation reducing agent comprising a cellulosic compound, and (d) a specific surface area of 30
A production method comprising using an anhydrous gypsum powder having an amount of from 00 to 7000 cm ² / g. 2. A method for producing a self-compacting concrete that fills the entire area of a mold to form a dense concrete hardened body without performing compaction work or remarkably reduces it, which is a pan-type forced kneading mixer. Cement, fine aggregate and admixture for concrete are thoroughly mixed in the mixer of the concrete plant selected from the two-axis forced mixing mixer according to the performance of the mixer, and then water and a water reducing agent are added. And kneading the mortar sufficiently, and then adding coarse aggregate to knead the concrete. Further, as the admixture for concrete, (a) a specific surface area of 7,000 to
Mineral fine powders is 20000 cm ² / g, (ii) mineral coarse powder having a specific surface area of 500~4000cm ² / g, (c) separation reducing agent comprising a cellulose-based compound, and (d) a specific surface area of 3000 A production method comprising using an anhydrite powder having an amount of ˜7000 cm ² / g. 3. A method for producing a self-compacting concrete that fills the entire area of a mold to form a dense concrete hardened body without performing compaction work or significantly reduces it, which is a pan-type forced kneading mixer. Cement, fine aggregate and admixture for concrete are thoroughly mixed in the mixer of the concrete plant selected from among the twin-screw forced kneading mixer according to the performance of the mixer, and then water is added to sufficiently mix the mortar. After kneading, the concrete is kneaded by adding coarse aggregate and a water reducing agent, and further, as the admixture for concrete, (a) a specific surface area of 7,000 to 2
Fine mineral powder having a density of 0000 cm ² / g, (b) Coarse mineral powder having a specific surface area of 500 to 4000 cm ² / g,
(C) A method of producing, which comprises using a separation reducing agent composed of a cellulosic compound and (d) an anhydrous gypsum powder having a specific surface area of 3000 to 7000 cm ² / g. 4. A method for producing a self-compacting concrete in which a compact hardened body is formed by filling the entire area of a mold without compaction work or with a significant reduction, and a pan-type forced kneading mixer and Cement, concrete, and admixture for concrete in a concrete plant mixer selected from the twin-screw forced kneading mixer, according to the performance of the mixer, and then mixed with water to knead the concrete. A water reducing agent is added and the mixture is kneaded again. Further, as the admixture for concrete, (a) a fine mineral powder having a specific surface area of 7,000 to 20,000 cm ² / g, (b) a specific surface area of 500 to 4000 c.
Coarse mineral powder of m ² / g, (c) a separation reducing agent composed of a cellulosic compound, and (d) a specific surface area of 300
A production method comprising using an anhydrite powder of 0 to 7000 cm ² / g. 5. The fine mineral powder (a) is at least one selected from calcium carbonate and glassy blast furnace slag, and the coarse mineral powder (b) is Portland cement clinker ground product, calcium carbonate and glass. 5. At least one selected from quality blast furnace slag.
A method for producing a self-compacting concrete according to any one of 1. 6. The admixture is the fine mineral powder (a) 10
1 to 10 parts by weight of the mineral powder (b), 0.26 to 2 parts by weight of the separation reducing agent (c) composed of a cellulose compound, and 0.5 to 0 parts by weight of the anhydrous gypsum powder. ~
The method for producing a self-compacting concrete according to any one of claims 1 to 5, containing 25 parts by weight. 7. As the water reducing agent, at least one selected from a high performance water reducing agent or a high performance AE water reducing agent containing a highly condensed triazine derivative or a polycarboxylic acid compound as a main component is used. 7. The method for producing a self-compacting concrete according to any of 6.