JP2964386B2 - High fluidity concrete - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-flowable concrete, and more particularly to a high-flowable concrete with less self-shrinkage and drying shrinkage during hardening.

[0002]

2. Description of the Related Art In recent years, concrete having high fluidity and excellent separation resistance has been developed and put into practical use as one of effective means for streamlining construction, labor saving and mechanization. I have. Such concrete is generally called high fluidity concrete.

[0003] In high-fluidity concrete, powder materials such as cement, blast-furnace slag fine powder, fly ash and silica fume are used in a relatively large amount in order to enhance the fluidity of the concrete. Many use agents.

[0004] In such high-fluidity concrete, the amount of coarse aggregate is smaller than that of ordinary concrete due to the large amount of unit powder, and there is a concern that shrinkage during hardening may increase. That is, when the amount of powder in the concrete increases, the water-powder ratio decreases, the self-shrinkage caused by the hydration reaction of the cement increases, and the increased self-shrinkage and the drying shrinkage caused by the evaporation of moisture in the concrete. As a result, the amount of shrinkage of the entire concrete is increased, and cracks are likely to occur during hardening of the concrete.

[0005] Here, in general concrete,
As a means of reducing cracks due to shrinkage that occurs during hardening, the unit water content in concrete is reduced. Curing or curing of concrete is carried out by curing under wet air or under water. Add organic shrinkage reducing agent to concrete. Add inorganic expander to concrete. And other measures have been taken.

It is considered that these means are basically effective also for the above-mentioned high-fluidity concrete. However, these means further reduce the water-powder ratio of the high-fluidity concrete, and consequently cause self-shrinkage. And high fluidity concrete does not necessarily lead to crack prevention. Although it is considered that the method of (1) can greatly reduce the drying shrinkage, in high fluidity concrete having a high rate of self-shrinkage, the overall amount of shrinkage cannot be reduced so much, and is not an effective means. Is effective for high-fluidity concrete, but there are problems such as delay in setting of the concrete and reduction in initial strength depending on the amount of use. I can't do that. In general, high-fluid concrete uses a thickener and a relatively large amount of an admixture such as a high-performance water-reducing agent, and these admixtures significantly delay the setting of concrete. In some cases, the effect of the expanding material may not be sufficiently obtained.

[0007] The applicant of the present application has previously devised a method for adding a known inorganic expanding material and a specific organic shrinkage reducing agent to a mortar or concrete raw material as a method for preventing cracking of a hardened cement body. An application was filed (Japanese Patent Publication 2-17501). The organic shrinkage reducing agent used in such means is an amide compound and / or a modified amide compound, or a compound of the general formula RO (AO) _n H (R is
An alkyl group having from 7 to 7 or a cycloalkyl group having from 5 to 6 carbon atoms, A is one or two alkylene groups having from 2 to 3 carbon atoms,
n is a number from 1 to 10).

The means described in Japanese Patent Publication No. 2-17501 has a remarkable shrinkage-reducing effect even in high-fluidity concrete and can prevent the occurrence of cracks.
When the amide compound and / or modified amide compound as the organic shrinkage reducing agent or the compound represented by the general formula RO (AO) _n H is added to the high fluidity concrete, the amount of entrained air increases, and the amount of air in the concrete increases. This raises a new problem that the properties such as the compressive strength of the cured product decrease.

SUMMARY OF THE INVENTION The present invention has been made in view of the inconvenience that occurs when the above-described conventional shrinkage reducing means is applied to high-fluidity concrete as it is. It is an object of the present invention to provide a high fluidity concrete which does not impair various properties such as compressibility and compressive strength, and which is small in shrinkage and excellent in crack resistance.

[0010]

In order to achieve the above-mentioned object, the present invention provides a high-fluidity concrete containing a known inorganic expanding material and a general formula ROH (R is a carbon number of 4 to 6). Or a cycloalkyl group having 5 to 6 carbon atoms).

Here, the high-fluidity concrete means that the unit powder amount is 400 kg / m ³ or more and the slump flow is 4 kg / m ³ or more.
The powder used is concrete with a size of 00 mm or more, and the powder used is ordinary Portland cement, moderately heated Portland cement, early-strength Portland cement, high belite portland cement, blast furnace cement, fly ash cement, silica cement, and blast furnace Any mixture of inorganic powders such as slag fine powder, fly ash and limestone fine powder may be used.

[0012] As the inorganic expanding material, commercially available calcium sulfaluminate (CSA) is used.
Any of expandable materials such as lime, calcareous, gypsum or MgO may be used, and these expandable materials may be used alone or in combination. However, preferably CS
A type and quick lime type expansion material are good.

Further, in the compound represented by the general formula ROH, the alkyl group having 4 to 6 carbon atoms for R is
n-butyl group, iso-butyl group, tert-butyl group, n-pentyl group, iso-pentyl group, tert-
Examples thereof include a pentyl group, an n-hexyl group and an iso-hexyl group, and examples of the cycloalkyl group having 5 to 6 carbon atoms include a cyclopentyl group and a cyclohexyl group. Among these, a butyl group is preferred.
Specifically, as the alcohol represented by the general formula ROH,
Examples include n-butyl alcohol, iso-butyl alcohol, tert-butyl alcohol, n-pentyl alcohol, iso-pentyl alcohol, tert-pentyl alcohol, n-hexyl alcohol, iso-hexyl alcohol, cyclopentyl alcohol, cyclohexyl alcohol, and the like. .

The content of the alcohol represented by the general formula ROH is from 1 to 1 in 1 m ^{3 of} high-fluidity concrete.
It is preferably contained at a rate of 0 kg / m ³ . This is because if the content is less than 1 kg / m ³ , the effect of reducing shrinkage during curing is small, while if the content exceeds 10 kg / m ³ , the strength of the cured product is significantly reduced. In addition, the content of the above-mentioned inorganic expander may be contained as a guide in an amount usually added for the purpose of reducing shrinkage, but an amount exceeding 40 kg / m ³ is present in 1 m ^{3 of} high-fluid concrete. This is not preferable because the strength of the cured product is reduced. Preferably, the weight ratio between the content of the alcohol represented by the general formula ROH and the content of the inorganic expanding material is 0.1 to 0.3.

The method for containing the compound represented by the general formula ROH and the inorganic expander in the high-fluidity concrete is not particularly limited, but the following methods are exemplified. That is, a method of previously dissolving and mixing in water, a method of mixing and dispersing in a cement in advance by mixing and pulverizing with a mill, a compound represented by the general formula ROH during kneading of high-fluid concrete, and an inorganic expander , Or a method in which the compound represented by the general formula ROH and the inorganic expander are uniformly mixed in advance, and then added to the high-fluidity concrete and kneaded.

The high-fluidity concrete according to the present invention is characterized in that the inorganic expandable material and the alcohol represented by the general formula ROH present in the high-fluidity concrete reduce shrinkage during hardening and reduce the compressive strength of the hardened body. The generation of cracks can be significantly prevented without lowering the characteristics.

[0017]

Test Examples Hereinafter, test examples supporting the effects of the above-mentioned high fluidity concrete according to the present invention will be described.

Test Examples 1 to 4 [Materials Used] Cement: Ordinary boltant cement (specific gravity: 3.15, manufactured by Nippon Cement Co.) Fine aggregate: Tokyo crushed sand (FM: 2.87, specific gravity: 2.62) Coarse aggregate: Crushed stone from Tokyo (FM: 6.73, specific gravity: 2.64) Thickener: Acrylic thickener (Asano HF, manufactured by Nippon Cement Co.) Admixture: Melamine-based high-performance water reducer (Wall Fine 510AN,
Expanding material: CSA-based expanding material (Asano Shidical, manufactured by Nippon Cement Co., Ltd.) Shrinkage reducing agent: lower alcohol alkylene oxide adduct (Tetraguard AS20, manufactured by Nippon Cement Co., Ltd.)

The above materials and a butyl alcohol-based compound (Tetraguard AS21, manufactured by Nippon Cement Co., Ltd .;
Butyl alcohol) was mixed and kneaded at the ratios shown in Table 1 to produce a high-fluidity concrete. In addition, Test Example 1 shown in Table 1 is a high-fluidity concrete not containing a substance having a shrinkage reducing effect such as an expanding material, Test Example 2 is a high-fluidity concrete containing only the expanding material, and Test Example 3 is High fluidity concrete containing the above-mentioned shrinkage reducing agent together with the above-mentioned expansive material (high-fluidity concrete using the means of Japanese Patent Publication No. 2-17501), and Test Example 4 shows that the high-fluidity concrete containing butyl alcohol together with the above-mentioned expansive material High fluidity concrete according to the invention).

[0020]

[Table 1]

The amount of air, slump flow, separation resistance and compressive strength of the high-fluid concrete of each of the above formulations were measured. Table 2 shows the measurement results. The amount of air was measured immediately after mixing according to JIS A 1128. Slump flow was defined as slump flow according to JIS A 1101. Separation resistance was measured by placing each high-fluidity concrete in a 2 liter container, gently opening it on a 5 mm mesh, and allowing it to stand for 5 minutes, then measuring the mass of the mortar passing through the mesh.
The value (SI value) divided by the mortar mass in 2 liters of high fluidity concrete was calculated and evaluated. Furthermore, the compressive strength
According to JIS A 1108. The test material age was 28 days.

[0022]

[Table 2]

From Table 2, it can be seen that the high fluidity concrete according to the present invention (Test Example 4) has no major problems in the characteristics of air volume, slump flow, separation resistance and compressive strength. On the other hand, it can be seen that the high fluidity concrete using the means of Japanese Patent Publication No. 2-17501 (Test Example 3) has a large amount of air and its compressive strength is significantly reduced.

Test Examples 5 to 13 The above-mentioned materials were used in the following manner: cement = 360 kg / m ³ , water / cement ratio = 50%, S / a = 52.3%, admixture = 12 kg /
m ³ and a thickener = 3 kg / m ³ , respectively, and the above-mentioned expander and butyl alcohol were added at the ratios shown in Table 3 to produce a highly fluid concrete.

The air content, compressive strength, and maximum expansion rate of the high-fluid concrete of each of the above formulations were measured. Table 3 also shows the measurement results. The air volume is
According to JIS A 1128, the amount of air immediately after mixing was measured. The compressive strength conformed to JIS A 1108. The test material age was 28 days. Further, the measurement of the maximum expansion rate was performed by the following method. [Measurement of maximum expansion coefficient] Specimen size was 10 × 10 × 40 cm
Immediately after casting the high-fluidity concrete, the surface was covered with a vinyl sheet (0.1 mm in thickness), and left standing in a constant temperature room at 20 ° C. for one day. One day after the material was removed, the entire surface of the test piece was immediately sealed with an aluminum foil adhesive tape to prevent the escape of water. After one day of material age, store in a constant temperature / humidity room at 20 ° C and 60% RH, measure the length change with a dial gauge (1 / 1000mm) in an unconstrained state, and maximize the expansion of each specimen. The rate was measured.

[0026]

[Table 3]

From Table 3, it can be seen that when the content of the expanding material exceeds 40 kg / m ³ (Test Example 8), the maximum expansion rate increases, but the compressive strength is significantly reduced. When the content of butyl alcohol is less than 1 kg / m ³ (Test Examples 6 and 7), even if the expanding material is contained in an appropriate amount, there is no expansion promoting effect.
Conversely, if the content exceeds 10 kg / m ³ (Test Example 1
2) It can be seen that the compressive strength decreases. Further, when the expander and butyl alcohol are contained in appropriate amounts (Test Examples 9, 10 and 11), it can be seen that the maximum expansion coefficient is significantly increased without lowering the compressive strength.

Test Examples 14 to 17 A wall was manufactured using the high-fluidity concrete having the composition of Test Examples 5, 6, 13 and 10, and the occurrence of cracks in the wall was observed. The results are shown in FIG. In addition, in FIG. 1 and Table 4, Test Example 14 is a wall manufactured using high-fluidity concrete not containing a substance having an effect of reducing shrinkage such as an expanding material (high-fluidity concrete blended with Test Example 5). Test Example 15 is a wall body manufactured using high-fluidity concrete containing only the expanding material (high-fluidity concrete blended in Test Example 6), and Test Example 16 is a high-fluidity concrete containing only butyl alcohol ( Test example
The wall body manufactured using the high-fluidity concrete having the composition of 13 and the test example 17 further include the high-fluidity concrete containing the butyl alcohol together with the expander (the high-fluidity concrete having the composition of the test example 10, ie, the present invention). It is a wall manufactured using high fluidity concrete).

As shown in FIG. 1, the test method is as follows: a window hole having a height of 6 m, a length of 30 m and a thickness of 20 cm (length 120 cm, width 2 cm).
00cm) The wall is divided into four sections, and the high-fluidity concrete is poured into each section using a pump truck with a maximum discharge rate of 110m ³ / hr. The subsequent crack situation was sketched (FIG. 1), and the width and length of each crack were measured (Table 4).

[0030]

[Table 4]

FIG. 1 and Table 4 show that the wall body was manufactured using the high-fluidity concrete according to the present invention (Test Example 17).
Since the number of cracks is small and the width and length of the cracks are small as compared with other wall bodies, it can be seen that the high fluidity concrete according to the present invention has remarkable crack resistance.

-Test Examples 18 to 21-[Materials Used] Cement: Ordinary polyester cement (specific gravity: 3.15, manufactured by Nippon Cement Co.) Limestone powder: specific gravity: 2.71, specific surface area: 3000 cm ² / g Fine aggregate: Okayama Prefecture Sea sand (FM: 2.57, specific gravity: 2.54)
6: 4 mixed with Okayama Prefecture mountain sand (FM: 2.80, specific gravity: 2.54) Coarse aggregate: Okayama Prefecture concrete crushed stone 1505 (FM: 6.
30, specific gravity: 2.65) and concrete breaking stone 2015 (FM: 6.9)
6, specific gravity: 2.65) in 4: 6 and used. Thickener: Acrylic thickener (Asano HF, manufactured by Nippon Cement Co.) Admixture: Melamine-based high-performance water reducing agent (Wall Fine 510A)
N, manufactured by Takemoto Yushi Co., Ltd.) Expansive material: CSA-based expansive material (Asano Shidukakar, manufactured by Nippon Cement Co., Ltd.)

The above materials and butyl alcohol-based compound (Tetraguard AS21, manufactured by Nippon Cement Co., Ltd .;
Butyl alcohol) was mixed and kneaded at the ratios shown in Table 5 to produce a highly fluid concrete. In addition, Test Example 18 shown in Table 5 is a high-fluidity concrete not containing a substance having a shrinkage reducing effect such as an expanding material, Test Example 19 is a high-fluidity concrete containing only the expanding material, and Test Example 20 is High-fluidity concrete containing only butyl alcohol, and Test Example 21 is a high-fluidity concrete containing butyl alcohol together with the expander (high-fluidity concrete according to the present invention).

[0034]

[Table 5]

The high fluidity concrete of each of the above formulations was tested for shrinkage, autogenous shrinkage and crack resistance under dry conditions. The test results are shown in FIGS. In addition, the test of the shrinkage under a dry condition and the self-shrinkage were performed by the following methods, respectively. The crack resistance was tested in accordance with the JIS draft “Dry shrinkage crack test method for concrete”. (Shrinkage test under dry conditions) According to JIS A 1129,
Shrinkage was measured for the high fluidity concretes of all formulations shown in Table 5. The dimensions of the specimen were 10 × 10 × 40 cm, and each mixture was three. After leaving it in a constant temperature room at 20 ° C until the material age is 1 day, it is removed from the mold. After 1 day in the material age, it is kept in a constant temperature and humidity room at 20 ° C and 60% RH. Mass and dial gauge (1 / 1000mm) The length was measured by. In addition, about the compound using the expansion material, the test was performed without restriction. [Autogenous shrinkage test] The specimen was set to a size of 10 × 10 × 40 cm. Immediately after the high-fluidity concrete was cast, the surface was covered with a vinyl sheet (0.1 mm in thickness) and allowed to stand in a constant temperature room at 20 ° C. for one day. One day after the material was removed, the entire surface of the test piece was immediately sealed with an aluminum foil adhesive tape to prevent the escape of water.
After one day of material age, it was stored in a constant temperature and humidity room at 20 ° C. and 60% RH, and its length was measured by mass and a dial gauge (1/1000 mm). In addition, about the compound using the expansion material, the test was performed without restriction.

[0036]

[Table 6]

2 and 3, the high-fluidity concrete according to the present invention, that is, the high-fluidity concrete containing an inorganic expander and butyl alcohol (Test Example 21) was compared with the high-fluidity concrete of other formulations. It can be seen that the initial expansion is remarkably large, and the shrinkage at the time of curing, particularly the shrinkage due to self-shrinkage, is significantly reduced. Also, from Table 6, the high fluidity concrete according to the present invention containing an inorganic expanding material and butyl alcohol (Test Example 21)
Shows that the number of days until the occurrence of cracks is longer than that of other materials, indicating that the high fluidity concrete according to the present invention has remarkable crack resistance.

[0038]

As described above, according to the high-fluidity concrete according to the present invention described above, various properties such as air volume, slump flow, separation resistance and compressive strength are not impaired, and cracking resistance with small shrinkage is also attained. It has the effect of becoming excellent high fluidity concrete.

[Brief description of the drawings]

FIG. 1 is a diagram in which cracks generated in the walls of Test Examples 14 to 17 are sketched.

FIG. 2 is a graph showing the results of a shrinkage test under drying conditions of Test Examples 18 to 21.

FIG. 3 is a graph showing the results of a self-shrinkage test of Test Examples 18 to 21.

Continuation of the front page (51) Int.Cl. ⁶ Identification code FI C04B 22:14) 111: 62 (72) Inventor Kan Ogawa 1-1-13 Yamashita, Okayama City, Okayama Prefecture Omotogumi Co., Ltd. (56 References JP-A-3-37146 (JP, A) JP-A-4-338146 (JP, A) JP-A-52-127920 (JP, A) JP-A-51-50935 (JP, A) 57-102985 (JP, A) JP-A-49-64625 (JP, A) JP-A-50-97625 (JP, A) JP-B-2-17501 (JP, B2) (58) Fields investigated (Int. Cl. ⁶ , DB name) C04B 28/02 C04B 24/02

Claims (2)

(57) [Claims] 1. A high-fluidity concrete contains a known inorganic expanding material and has a general formula ROH (R is an alkyl group having 4 to 6 carbon atoms or a cycloalkyl group having 5 to 6 carbon atoms). Highly fluid concrete, characterized by containing the indicated alcohol. Wherein the alcohol represented by the general formula ROH is, during the high fluidity concrete 1 m ^3, characterized in that it contains a proportion of 1 to 10 kg / m ^3, a high fluidity concrete of claim 1, wherein .