JPH08239256A - Production of concrete - Google Patents

Abstract

PURPOSE: To obtain concrete improved in durability and surface appearance through remedying noise pollution, by compaction of concrete having each specific formulation composition and slump under application of primary and secondary vibrations while packing it in a formwork. CONSTITUTION: Using normal Portland cement and blast furnace slag 4000cm<2> /g in specific surface area, a composition is prepared so as to be 45 50wt.% in water-cement ratio (W/C), 32-40wt.% in the ratio W/(C + slag), 300-320kg/m<3> in clement content and 80-120kg/m<3> in blast furnace slag content, and 0.5-2.5wt.%, based on the cement, of a high-performance water reducing agent and 0.01-0.1wt.%, based on the cement, of a foaming agent are added to the composition to obtain a fluid concrete 16-20cm in slump. Next, a primary vibration with displacement vibrations of 5-7mm and 1-3mm in the Y-direction and Z-direction, respectively, and vibration accelerations of 1.5-2.5G and 0.2-0.3G in the Y-direction and Z-direction, respectively, and an arbitrary secondary vibration are applied to the fluid concrete while packing it in a formwork, followed by steam curing of the concrete to obtain the objective concrete 150-220kg/cm<2> in compressive strength.

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 a concrete product. More specifically, the slump value is
The present invention relates to a method for producing concrete with excellent durability and surface aesthetics, which is characterized by compacting 16 to 20 cm soft concrete with extremely low vibration and then steam curing it, and which has improved the environment against noise. .

[0002]

2. Description of the Related Art Since it is most effective to manufacture concrete products, it is most effective to carefully consolidate concrete with a minimum amount of water in order to improve the performance of the concrete itself. As far as possible, concrete that has been hard-mixed (slump value: 2 to 8 cm) was poured into a mold, and large vibrations, mainly vertical vibrations, were added to it to perform molding. However, the noise during compaction
It is as large as 95 to 100 dB, which is a source of worsening work environment and noise and vibration pollution in the neighborhood.

[0003]

Means for Solving the Problems The present inventors have found a concrete composition, a proper slump value and a vibration condition of extremely low vibration for solving the above problems, and completed the present invention.

That is, according to the present invention, the primary vibration and the secondary vibration are caused after or while the concrete is filled with the concrete whose composition and slump value are shown in the following items (A) to (G) in the formwork. The present invention relates to a method for producing concrete, characterized in that the primary vibration is compacted under the vibration conditions shown in the following items (H) to (I).

(A) Water cement ratio (W / C) is 45 to 50% by weight, and W / (C + slag) ratio is 32 to 40% by weight. (B) Content of ordinary Portland cement (unit cement) Amount) is 300-320kg / m ³ (C) Blast furnace slag content (unit slag amount) is 80-120kg /
m ³ (D) The specific surface area of the blast furnace slag is 4000 cm ² / g or more (E) The concrete admixture is (a) naphthalene sulfonic acid formaldehyde condensate, (b) melamine sulfonic acid formaldehyde condensate, ( c) One or two selected from methylol compounds of melamine, urea, phenol or aniline.
At least one high-performance water reducing agent selected from at least one formaldehyde condensate, (d) unsaturated monocarboxylic acid and its derivative, and (e) unsaturated dicarboxylic acid and its derivative (F) Concrete The foaming agent (AE agent) is an anionic activator or a nonionic activator (G) The slump value is 16 to 20 cm (H) The displacement vibration amount is in the Y direction (left and right direction when viewed from the front) 5 to 7 mm, 1 to 3 mm in the Z direction (vertical direction) (I) Vibration acceleration is 1.5 to 2.5 G in the Y direction, and in the Z direction
Must be 0.2 to 0.3 G.

The concrete composition of the present invention will be described below.

First, the W / C ratio and the W / (C + slag) ratio will be described. The optimum W / C ratio is 45 to 50% by weight. If the W / C ratio exceeds 50% by weight, the predetermined strength cannot be obtained, and material separation due to low vibration occurs, which is not preferable.
When the W / C ratio is less than 45% by weight, strength exceeding a predetermined strength is exhibited and separation resistance is improved, which is preferable, but the amount of the high-performance water reducing agent to be added is increased, which is not preferable from the economical aspect.

[0008] Although ordinary Portland cement and blast furnace slag are indispensable as the cement to be used, it is also possible to use early strength cement instead of ordinary cement. When the concrete temperature rises in the summer and the slump loss is large, a water reducing agent (to be described later) that prevents slump loss is used, so that a predetermined strength can be obtained without changing the pre-positioning time, which is particularly effective. The unit cement amount is 300 ~
320 kg / m ³ is preferred. If it is less than 300 kg / m ³ , the separation resistance between the coarse aggregate and the mortar portion is deteriorated, which is not preferable.
When it exceeds 320 kg / m ³ , separation resistance increases, which is preferable, but it is not preferable in terms of economy. The optimum unit slag amount of blast furnace slag used together is 80 to 120 kg / m ³ . If it is less than 80 kg / m ³ , the separation resistance becomes poor, which is not preferable. 120 kg / m ³
If it exceeds, separation resistance increases, which is preferable, but it is not preferable in terms of economy.

Further, the fineness of the blast furnace slag is usually preferably expressed by the specific surface area. Specific surface area is 4000 cm
² / g or more is preferable. If the powder has a specific surface area of 4000 cm ² / g or more, it can be used without being limited to the blast furnace slag, but the blast furnace slag is preferable from the economical point of view. Examples of commercially available blast furnace slag include Essent (manufactured by Nippon Steel Chemical Co., Ltd.).

As the high-performance water reducing agent to be used, naphthalene sulfonic acid formaldehyde condensate (trade name: Mighty 150: Kao Corporation) and melamine sulfonic acid formaldehyde condensate (trade name: Mighty 150V2: Kao Corporation) ) Or one or more formaldehyde condensates selected from melamine, urea, phenol or a methylol compound of aniline (compounds such as the compound described in Japanese Patent No. 1097647 and the compound described in JP-A No. 1-113419). It can be used alone or in combination. Further, in order to prevent slump loss of concrete in the summer, the above-mentioned high-performance water reducing agent and unsaturated monocarboxylic acid and its derivative and / or unsaturated dicarboxylic acid and its derivative (Japanese Patent Publication No. 2-7901, JP-A-3-752).
52) and the compound described in JP-B-2-8983), it is possible to prevent slump loss.
These high-performance water reducing agents and slump loss preventing agents are usually liquid products, but they can be added in the form of powder. When added, it may be added at the same time as water, or may be added after kneading with cement, water, fine aggregate and coarse aggregate. The amount added to cement varies depending on the method of addition, but is 0.5 to 2.5% by weight.

Freeze-thaw resistance is required when concrete products are used in cold regions, and it is necessary to entrain air bubbles in the concrete to increase the resistance. In this case, it is necessary to add a foaming agent (AE agent) to adjust the concrete air amount to 3 to 6% by volume.

The foaming agent used in the present invention is preferably an anionic activator or a nonionic activator.

Examples of the anionic activator include polyoxyethylene alkylphenyl ether sulfate (trade name: Mighty AE03: manufactured by Kao Corporation), polyoxyethylene lauryl sulfate (trade name: Emal 20C: manufactured by Kao Corporation). Made), α-olefin sulfonate, alkylbenzene sulfonate (trade name: Neoperex No2
5, Neoperex F25: manufactured by Kao Corporation, lauryl sulfate (trade name: Emal 0: manufactured by Kao Corporation), resin acid salt (trade name: Vinsol W: manufactured by Yamamune Chemical Co., Ltd.), etc. Anionic activators, nonionic or amphoteric activators can be used.

As the foaming agent, any activator can be used as long as it foams in concrete, but since the high-performance water reducing agent added to concrete is anionic, the cationic foaming agent forms a complex. However, it is not preferable because it precipitates. To increase freeze-thaw resistance, it is necessary to entrain fine bubbles. It is preferable to use an anionic activator as the foaming agent which meets this purpose. This foaming agent is usually dissolved in a high-performance water-reducing agent solution before use, but its effect does not change even if it is added separately or afterwards. The amount of foaming agent added to cement is 0.01-
0.1% by weight is used. If there is no problem of freezing and thawing, a foaming agent may not be used.

The fluidity of the concrete thus obtained is measured by the slump value according to the slump test described in JIS-A1101 method. The slump value of the present invention is preferably 16 to 20 cm. If the slump value is less than 16 cm, it is difficult to sufficiently fill the mold for producing a concrete product under the vibration conditions of the present invention, and the appearance of the concrete product surface after demolding is poor. It is possible to improve the filling by further increasing the vibration conditions of the present invention, but it is not preferable because it causes noise. When the slump value exceeds 20 cm, the filling property is improved, but the mortar part and the aggregate are separated and the strength is lowered, which is not preferable.

The concrete produced in this way is
It is filled in a formwork for producing a concrete product, and an extremely low vibration is applied by a vibrating machine to fill the concrete formwork in every corner.

Although the vibrator used in the present invention is shown in FIG. 1, it is not particularly limited to this vibrator, and as the primary vibration, the vibration condition is that the displacement vibration amount is 5 to 7 m in the Y direction.
m, 1 to 3 mm in Z direction, vibration acceleration 1.5 to 2.5 in Y direction
0.2 to 0.3 G is preferable in the G and Z directions. It is better to perform the vibration separately for the primary and secondary vibrations. The primary vibration is mainly for filling and compacting concrete, and the secondary vibration is mainly for removing voids in the concrete, in other words improving the surface aesthetics of concrete. To do so. It is desirable that the primary vibration is performed using a table type vibrator (FIG. 1) and the secondary vibration is performed using a bar vibrator from above the concrete, but the method is not particularly limited to this. The vibration time required for the primary vibration varies depending on the size of the product, etc., but is preferably 1 to 3 minutes, and the vibration time required for the secondary vibration is preferably 3 to 4 minutes. 20-30% less time than ordinary hard concrete.

The concrete thus produced is steam-cured in order to develop its initial strength. The curing method is not particularly limited and is a commonly used method, that is, the time from the production of concrete to the start of steam curing is 0.5 to 4 hours, the heating rate is 10 to 40 ° C / hour, and the maximum temperature is 60 to 80. C., the maximum temperature holding time is 1 to 4 hours.

[0019]

The soft-mixed concrete produced by the concrete mixture composition of the present invention is subjected to vibration molding at an extremely low vibration, and steam curing is carried out to obtain the following effects.

1. Strength, durability and surface aesthetics equal to or higher than those of conventional hard concrete products can be obtained. 2. Concrete filling is possible enough in complex reinforced concrete structures. 3. In terms of materials and equipment for manufacturing concrete, the manufacturing cost will not be too high without making major modifications to the conventional method. 4. The noise during vibration compaction is less than 85 dB, greatly improving the working environment.

[0021]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

(1) Materials used Cement (C): Normal Portland cement (specific gravity 3.17) Fine aggregate (S): Kinokawa river sand (specific gravity 2.57, FM2.91) Coarse aggregate (G): Takarazuka crushed stone (specific gravity) 2.60, FM6.57) Blast furnace slag (SL): Nippon Steel Chemical Co., Ltd. (specific gravity 2.90, Blaine value 6000 cm ² / g) (2) Concrete production method 50 liters pan type forced mixer (Pacific Metals Co., Ltd.)
40 liters of concrete material was put into the product), kneaded for 3 minutes, and then tested for the following items. The temperature of the concrete was 20 ± 1 ° C. Admixture (Table 1 below
The high-performance water reducing agent shown in (1) and the foaming agent shown in Table 2) were dissolved in kneading water and added. Table 3 shows the mixing conditions of concrete and the following evaluation results.

Slump test: Measured according to JIS A 1101.

Air amount test Measured according to JIS A 1128.

Strength test: Concrete was packed in an iron cylindrical formwork of φ10 cm × 20 cm, and the vibration conditions were changed to perform compaction. After allowing the test piece to stand for 1 hour, steam curing was performed, and a compressive strength test was performed 8 hours after concrete production (8 hours after kneading).

Separation Resistance Test Concrete was packed in a mold shown in FIG. 3, set in a vibrator, and the vibration conditions were changed to perform compaction. After that, the concrete in the portions A and B was washed with water, the coarse aggregate remaining on the 5 mm sieve was dried at 105 ° C. until a constant weight was obtained, and the separation resistance (%) was determined from this weight according to the following formula. Separation resistance = {(A / (A + B)} × 2 × 100 Further, the results were displayed as follows: ○: Separation resistance (95% or more) △: Separation resistance (90 to 95%) X: Separation resistance (90% or less).

Surface aesthetic test A 10 cm x 20 cm x 50 cm (height) steel frame was set on a vibrator table, and the vibration conditions were changed for compaction. The concrete was steam-cured and then demolded, and the number of bubbles (3 mm or more) on the surface (both sides) of the concrete was measured, and the result of the average value was displayed as follows. Number of bubbles per 1000 cm ³ ○: None, △: 5 to 25,
× 25 or more.

Freezing and thawing test Measured according to JIS A 6204 (Appendix 2).
In addition, the vibration conditions were changed and compaction was performed, three test pieces were prepared, and the test was performed after steam curing. The display is shown as follows according to the dynamic elastic modulus (%) after the 300 cycle test. ○: Dynamic elastic modulus (%) is 90% or more ×: Dynamic elastic modulus (%) is 90% or less

[0029]

[Table 1]

[0030]

[Table 2]

[0031]

[Table 3]

The results shown in Table 3 show the following.

The examples of the present invention (No. 1 to No. 10) are concrete products excellent in separation resistance of aggregate of fresh concrete, surface aesthetics of hardened concrete, and freeze-thaw resistance, and are more economical, and It can be seen that this is an excellent invention that makes it possible to manufacture with extremely low noise, rather than the conventional high noise.

The concrete mix of Comparative Example No. 13 is within the range of the present invention, but the slump value is lower than the range of the present invention, so that the surface aesthetics of the concrete is poor and it is not preferable.

The concrete mix of Comparative Example No. 14 is No. 13
Similarly, although it is within the range of the composition of the present invention, since the slump value is higher than the range of the present invention, the separation resistance is inferior, which is not preferable.

In Comparative Examples Nos. 15 and 16, the slump value falls within the range of the present invention, but the concrete composition is out of the composition range of the present invention (unit cement and slag amount are small). As a result, separation resistance, surface It is inferior in aesthetics and freeze-thaw resistance, which is not preferable.

In Comparative Example No. 11, the concrete composition is out of the range of the present invention (the unit cement and the amount of slag are large), and the concrete properties are all good, but the unit cement and the unit slag amount are large. It is inferior in economic efficiency and is not preferable.

In Comparative Example No. 12, the concrete composition is out of the range of the present invention (the amount of unit cement is large and the amount of slag is small), and the separation resistance and the surface aesthetics are poor, which is not preferable.

[Brief description of drawings]

FIG. 1 is a diagram showing a state of primary vibration using a table-type vibrator, which is an example of the present invention.

FIG. 2 is a diagram showing a state of secondary vibration using a form vibrator, which is an example of the present invention.

FIG. 3 is a sketch drawing of a mold used in a separation resistance test of Examples.

[Explanation of symbols]

 1 Y direction 2 Z direction 3 Separation resistant concrete 4 Vibration table 5 Vibration machine 6 Formwork

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location C04B 24/24 C04B 24/30 A 24/30 28/08 28/08 B28B 1/08 B // (C04B 28/08 7:19 24:32 24:22) 103: 30 103: 32 (72) Inventor Ryo City Tamaki 63-6 Kinomoto, Wakayama City, Wakayama Prefecture (72) Inventor Akitoshi Tsuji Uchida Town, Naga County, Wakayama Prefecture Nishiisaka 64 of 5

Claims (2)

[Claims] 1. A primary vibration after applying a primary vibration or a secondary vibration after or after the concrete is filled in the formwork with the concrete whose composition and slump value are shown in the following items (A) to (G). In the method for producing concrete, the method comprises compaction under the vibration conditions shown in the following items (H) to (I). (A) The water cement ratio (W / C) is 45 to 50% by weight, and the W / (C + slag) ratio is 32 to 40% by weight. (B) The content (unit cement amount) of ordinary Portland cement is 300 to 320 kg / m ³ (C) Blast furnace slag content (unit slag amount) is 80 to 120 kg /
m ³ (D) Specific surface area of blast furnace slag is 4000 cm ² / g or more (E) Concrete admixture (a) naphthalene sulfonic acid formaldehyde condensate, (b) melamine sulfonic acid formaldehyde condensate, ( c) One or two selected from methylol compounds of melamine, urea, phenol or aniline.
At least one high-performance water reducing agent selected from among at least one formaldehyde condensate, (d) unsaturated monocarboxylic acid and its derivative, and (e) unsaturated dicarboxylic acid and its derivative (F) Concrete The foaming agent (AE agent) is an anionic activator or a nonionic activator. (G) The slump value is 16 to 20 cm. (H) The displacement vibration amount is in the Y direction (horizontal direction when viewed from the front). 5 to 7 mm, 1 to 3 mm in the Z direction (vertical direction) (I) Vibration acceleration is 1.5 to 2.5 G in the Y direction, and in the Z direction
0.2 to 0.3 G 2. A concrete which is steam-cured after compaction and has a compressive strength of immediate release type concrete after curing.
The method for producing concrete according to claim 1, wherein the weight is 150 to 220 kg / cm ² .