JP2011236080A - Production method for medium-fluidity concrete and medium-fluidity concrete produced by the method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a production method which can inexpensively produce medium-fluidity concrete without adding powder to normal concrete, and to provide medium-fluidity concrete produced by the method.SOLUTION: Whether an AE water reducing agent is contained or not as an admixture, in normal concrete having a slump flow of 15 to 21 cm is confirmed. When it is contained, a thickener component-containing high performance AE water reducing agent is blended instead of the AE water reducing agent. Further, the blending ratio of fine aggregate occupied in the whole weight is controlled so as to be made higher than the blending ratio of coarse aggregate. Then, cement, the fine aggregate and the coarse aggregate are charged to a forced action biaxial mixer and are kneaded, thereafter, water and the thickener component-containing high performance AE water reducing agent are charged, and further, kneading is performed, thus the medium-fluidity concrete is produced.

Description

  The present invention relates to a method for producing medium fluidized concrete and a medium fluidized concrete produced by the method.

  Conventionally, ordinary concrete having slumps of 15 cm to 21 cm has been used as concrete for tunnel lining. Since this ordinary concrete has low fluidity, there is a risk of insufficient filling in the mold.

  Therefore, in recent years, there are increasing cases of using high fluidity concrete (slump flow larger than 50 cm) having high fluidity and excellent filling properties. However, since the high fluidity concrete has high fluidity, material separation of the coarse aggregate is likely to occur. In order to prevent this, a large amount of powder such as cement may be used or a material separation preventing agent may be used, but there is a problem that the material cost increases. Furthermore, since a special material such as a material separation preventing agent is used, there is a problem that it takes time and effort for manufacturing management.

  Therefore, recently, medium-fluidity concrete (slump flow of 35 cm or more and 50 cm or less), which has better fluidity than ordinary concrete, is lower in cost than high-fluidity concrete, and easy in quality control, has come to be used ( Patent Document 1).

For example, Non-Patent Document 1 describes the standard performance of medium-fluid concrete as shown in FIG. 9 (p. 4, Table-3.1), and ordinary concrete (cement) is used to ensure this standard performance. It is recommended to add stone powder (LS), coal ash (FA) or additional cement to 270 kg / m ³ or more (page 5).

JP 2008-285843 A

Tunnel construction management guidelines (Middle fluid lining concrete), East Japan Expressway Co., Ltd., Central Japan Expressway Co., Ltd., West Japan Expressway Co., Ltd., August 2008

  However, in order to use the above-mentioned stone powder and coal ash, a new storage silo and measuring instrument must be added to the existing concrete production plant. In addition, in certain areas, it is difficult to obtain stone powder and coal ash.

  In addition, the method of adding additional cement has a problem in that the temperature of concrete after placing increases due to an increase in the amount of cement, which may promote the occurrence of temperature cracks.

  Therefore, the present invention has been made in view of the above problems, and can produce medium-fluidity concrete at low cost without adding powder such as stone powder, coal ash, or additional cement to ordinary concrete. It is an object of the present invention to provide an intermediate manufacturing method and a medium fluidity concrete manufactured by the method.

The method for producing medium fluidity concrete of the present invention includes a confirmation step of confirming whether or not an AE water reducing agent is contained in the concrete having a slump of 15 cm to 21 cm,
In the confirmation step, when the concrete contains the AE water reducing agent, a high performance AE water reducing agent and a thickener are blended instead of the AE water reducing agent, and the blending amount of the water and the cement is changed. And a blending step of blending so that the blending ratio of the fine aggregate in the total weight is larger than the blending ratio of the coarse aggregate,
It is characterized by providing.

  Moreover, in the said confirmation process, when the said AE water reducing agent is not contained in the said concrete, the manufacturing method of the medium fluidity concrete of this invention mix | blends a high performance AE water reducing agent and a thickener, It is good also as providing the adjustment process mix | blended so that the mixture ratio of the said fine aggregate which occupies for a weight may become larger than the mixture ratio of the said coarse aggregate.

  Moreover, the manufacturing method of the medium fluidity concrete of this invention is good also as mix | blending a siliceous fine powder in the said mixing | blending process or the said adjustment process.

  The medium fluidity concrete of the present invention is manufactured by the above-described method of producing medium fluidity concrete.

  According to the present invention, medium-fluidity concrete can be produced at low cost without adding powder to ordinary concrete.

It is a figure which shows the performance of the medium fluidity concrete which concerns on this embodiment. It is a figure which shows the manufacturing process of the medium fluidity concrete which concerns on this embodiment. It is a figure which shows the relationship between a slump and a fine aggregate rate. It is a figure which shows the mixing | blending of the test bodies 1 and 2. FIG. It is a figure which shows the slump and slump flow of the test bodies 1 and 2. FIG. It is a figure which shows the mixing | blending, slump, and slump flow of the test bodies 3-8. It is a figure which shows the mixing | blending, slump, and slump flow of the test bodies 9-12. It is a figure which shows the difference in bleeding by the presence or absence of siliceous fine powder. It is a figure which shows the standard performance of middle fluidity concrete.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. First, general ordinary concrete will be described, and then medium-fluid concrete according to the present invention will be described.

General ordinary concrete is produced by mixing water, cement, fine aggregate, coarse aggregate, admixture and the like. Among these, since aggregate occupies most of the volume of concrete, the fluidity of concrete is greatly influenced by the properties of the aggregate. These aggregates are roughly classified into fine aggregates and coarse aggregates according to the particle size, and sand and stones that are highly available in areas where concrete is produced are used as appropriate. Since sand and stone have different properties depending on the type, the mixing ratio of water, cement, fine aggregate, coarse aggregate, and admixture varies depending on the region, even if the concrete has the same fluidity.
For example, the proportion of ordinary concrete with a slump of 18 cm may be known in each region or originally prepared by a contractor. In addition, this mixing | blending ratio can be easily known by inquiring literature and a supplier.

  The present invention is a method for producing medium fluidity concrete based on known blending ratios present in each region. In the present embodiment, a method for producing medium-fluidity concrete will be described based on the blending ratio of ordinary concrete with a slump of 15 cm to 21 cm.

FIG. 1 is a diagram showing the slump and slump flow performance of the medium-fluidized concrete according to the present embodiment.
As shown in FIG. 1 and FIG. 9 described in the background art section, in this embodiment, concrete having a slump flow of 35 cm or more and 50 cm or less is defined as medium fluidity concrete.

  FIG. 2 is a diagram showing a production process of the medium fluidized concrete according to the present embodiment. As shown in the figure, after the confirmation step S10, the medium-fluidity concrete is manufactured by performing either the blending step S20 or the adjustment step S30.

  Hereinafter, each step will be described.

  First, the confirmation step S10 is performed. In this step, the blending ratio of ordinary concrete with a slump of 15 cm to 21 cm is confirmed.

  As described above, since the blending ratio of ordinary concrete varies from region to region, the types and blending amounts of water, cement, fine aggregate, coarse aggregate, and admixture are confirmed in the region where medium fluidized concrete is manufactured.

  Further, it is confirmed whether or not an AE water reducing agent is contained as an admixture. When the AE water reducing agent is included as an admixture, next, the blending step S20 is performed.

  In the blending step S20, the medium fluidity concrete is blended based on the blending ratio of the ordinary concrete confirmed in the confirmation step S10. Below, the mixing | blending method of medium fluidity concrete is demonstrated.

<About the admixture>
A high performance AE water reducing agent containing a thickener component is blended in place of the AE water reducing agent contained in ordinary concrete.

  About the compounding quantity of a thickener component containing high performance AE water reducing agent, an optimal quantity is suitably determined based on the relationship with another material.

  In this embodiment, the AE water reducing agent is a material having a water reducing performance of about 10% to 12%, and the thickener component-containing high performance AE water reducing agent has a function of a thickener, In addition, it refers to a material having a water reduction performance of about 18% or more.

<About fine aggregate and coarse aggregate>
FIG. 3 is a diagram showing the relationship between the slump and the fine aggregate ratio (ratio of fine aggregate in the aggregate) (concrete blending design / construction guideline (draft) based on construction performance, page 55, 2007). (Extracted from Japan Society of Civil Engineers April)

  FIG. 3 shows that in order to produce concrete having a large slump, it is necessary to increase the fine aggregate ratio, that is, to increase the blending ratio of the fine aggregate rather than the coarse aggregate. From this, it adjusts so that the mixture ratio of the fine aggregate to the whole weight may become larger than the mixture ratio of a coarse aggregate.

  At this time, the total weight of the fine aggregate and the coarse aggregate is adjusted to be substantially the same as the total weight of the fine aggregate and the coarse aggregate included in the ordinary concrete confirmed in the confirmation step S10 (details will be described later). To do).

<About water and cement>
The blending amounts of water and cement are the same as those contained in the ordinary concrete in the confirmation step S10.

  Since the amount of ordinary cement does not change, the temperature after placing is almost the same as the temperature after placing concrete. Therefore, it can be cured in the same way as ordinary concrete, so it does not take time and the possibility of cracking does not change.

<Summary of blending step S20>
Medium fluid concrete has a composition containing water, cement, fine aggregate, coarse aggregate, and a high-performance AE water reducing agent containing a thickener component.

  After determining the blending ratio of each material as described above, cement, fine aggregate and coarse aggregate are put into a forced biaxial kneading mixer and mixed, and then water and a thickener component-containing high-performance AE water reducing agent are added. Medium flow concrete is produced by adding and kneading.

  In addition, the manufacturing method of the medium fluidity concrete of this invention does not add a chemical | medical agent etc. to the normal concrete used by confirmation process S10, but makes it a medium fluidity concrete, and mixes a material newly in mixing | blending process S20. It produces medium fluidity concrete.

  Next, the case where the AE water reducing agent is not included in the normal concrete as an admixture in the confirmation step S10 will be described.

  When the AE water reducing agent is not included in the ordinary concrete, the adjustment step S30 is performed next.

  In this process, the mixing ratio of water, cement, fine aggregate, coarse aggregate, and high-performance AE water reducing agent containing thickener component is newly determined without reference to the mixing ratio of ordinary concrete. .

  At this time, it mix | blends so that the mixture ratio of the fine aggregate to the whole weight may become larger than the mixture ratio of a coarse aggregate.

  Then, after determining the blending ratio of each material, the cement, fine aggregate and coarse aggregate are put into a forced biaxial kneading mixer and kneaded in the same manner as in blending step S20, and then the content of water and thickener component is increased. A medium-fluidity concrete is produced by adding a performance AE water reducing agent and further kneading.

  Here, as described above, a high-performance AE water reducing agent containing a thickener component is blended in place of the AE water reducing agent contained in ordinary concrete having a slump of 15 cm to 21 cm, and a fine aggregate and a coarse aggregate are blended. Since it has been confirmed by experiments that the performance of the medium fluidity concrete shown in FIG. 1 can be satisfied by changing the ratio, it will be described below.

In this experiment, specimens 1 and 2 having the composition shown in FIG. 4 were produced. Details of each specimen are as follows.
Specimen 1: Normal concrete with a slump of 17.5 cm and containing an AE water reducing agent. For cement and fine aggregate, ordinary cement and processed sand were used, respectively.
Specimen 2: A thickener component-containing high-performance AE water reducing agent was used in place of the AE water reducing agent of Specimen 1, and the fine aggregate was increased in the proportion of fine aggregate and coarse aggregate. At this time, fine aggregate (949kg / ^{m 3)} and the total weight (1762kg / ^{m 3)} of the coarse aggregate (813kg / ^{m 3)} is fine aggregate specimens 1 and (867kg / ^{m 3)} coarse aggregate It was adjusted to be approximately the same as the combined weight of the ^{(898kg / m 3) (1765kg} / m 3) ( equivalent to the present embodiment).

FIG. 5 is a diagram showing a slump and a slump flow of the test bodies 1 and 2.
As shown in FIG. 5, the specimen 2 has a slump and slump flow of 21.0 cm and 35 cm, respectively, and satisfies the performance required for medium-fluidity concrete.
In addition, since the test body 1 is normal concrete, neither slump nor slump flow satisfy | fills the performance requested | required as medium flow concrete.

  As a result of the above experiments, a high-performance AE water reducing agent containing a thickener component was blended in place of the AE water reducing agent contained in ordinary concrete, and a large amount of fine aggregate was blended in the blending ratio of fine aggregate and coarse aggregate. It was confirmed that the material satisfies the performance required for medium fluidity concrete.

  According to the above-described method for producing medium-fluid concrete, a high-performance AE water reducing agent containing a thickener component is blended in place of the AE water reducing agent contained in ordinary concrete, and the blending ratio of fine aggregate to coarse aggregate By increasing the size, medium fluidity concrete can be produced.

  In addition, instead of the AE water reducing agent contained in ordinary concrete, it is only necessary to use a high-performance AE water reducing agent containing a thickener component, and the management of the material and the labor of production are almost the same as when producing ordinary concrete, It can be manufactured easily.

  Moreover, since new materials such as stone powder and coal ash are not added, it is not necessary to add a new storage silo or measuring instrument to the existing concrete production plant.

  Furthermore, since the addition of stone powder, coal ash, additional cement, or the like is unnecessary, the economic efficiency is further improved.

In this embodiment, the case where processed sand is used as the fine aggregate has been described. However, the present invention is not limited to this, and land sand, sea sand, a mixture of sea sand and processed sand is used. FIG. 6 shows the results of actually manufacturing specimens 3 to 8 and confirming the slump and slump flow. Details of each specimen are as follows.
Test body 3: Fine aggregate is made of land sand, slump is 17.0 cm, and ordinary concrete containing AE water reducing agent.
Specimen 4: A thickener component-containing high-performance AE water reducing agent was included instead of the AE water reducing agent of Specimen 3, and the fine aggregate was increased in the proportion of fine aggregate and coarse aggregate.
Specimen 5: Fine aggregate made of sea sand, slump 18.0cm, ordinary concrete containing AE water reducing agent.
Test body 6: A high-performance AE water-reducing agent containing a thickener component was included instead of the AE water-reducing agent of test body 5, and the fine aggregate was increased in the blending ratio of fine aggregate and coarse aggregate.
Specimen 7: Fine aggregate consists of a mixture of sea sand and processed sand. Slump is 18.5 cm and is plain concrete containing AE water reducing agent.
Test body 8: A high-performance AE water reducing agent containing a thickener component was contained instead of the AE water reducing agent of the test body 7, and the fine aggregate was increased in the blending ratio of the fine aggregate and the coarse aggregate.

As shown in FIG. 6, the test bodies 4, 6, and 8 satisfy | fill the performance requested | required as medium fluidity concrete in both slump and slump flow.
In addition, since the test bodies 3, 5, and 7 are normal concrete, neither slump nor slump flow satisfy | fills the performance requested | required as medium fluidity concrete.
From the above experiments, it was confirmed that fine aggregate may be land sand, sea sand, or a mixture of sea sand and processed sand.

Moreover, in this embodiment, although the case where the normal cement was used as a cement was demonstrated, it is not limited to this, A blast furnace cement and a low heat blast furnace cement may be used, and the test bodies 9-12 are actually used. The result of manufacturing and confirming the slump and slump flow is shown in FIG. Details of each specimen are as follows.
Specimen 9: Cement is made of blast furnace cement, normal concrete with slump of 19.0 cm and containing AE water reducing agent.
Test body 10: A high-performance AE water reducing agent containing a thickener component was included instead of the AE water reducing agent of the test body 9, and the fine aggregate was increased in the blending ratio of fine aggregate and coarse aggregate.
Specimen 11: Cement is made of low heat blast furnace cement, normal concrete with a slump of 20.0 cm and containing an AE water reducing agent.
Test body 12: A high-performance AE water reducing agent containing a thickener component was included instead of the AE water reducing agent of the test body 11, and the fine aggregate was increased in the blending ratio of the fine aggregate and the coarse aggregate.

As shown in FIG. 7, the test bodies 10 and 12 satisfy | fill the performance requested | required as medium fluidity concrete in both slump and slump flow.
In addition, since the test bodies 9 and 11 are normal concrete, neither slump nor slump flow satisfy | fills the performance requested | required as medium fluidity concrete.
From the above experiments, it was confirmed that blast furnace cement and low heat blast furnace cement may be used as cement.

In the blending step S20 of the present invention, siliceous fine powder may be blended. By blending the siliceous fine powder, bleeding can be reduced.
A siliceous fine powder having an average particle diameter of about 1 μm is used.

  Here, it was confirmed by experiment that bleeding can be reduced by blending the siliceous fine powder, which will be described below.

In this experiment, specimens 13 to 16 of medium-fluidity concrete were manufactured, and when the siliceous fine powder was blended for each specimen, the bleeding rate when not blended was measured. The result is shown in FIG. The details of each specimen are as follows.
Test body 13: Medium-fluidity concrete containing fine aggregate made of land sand and slump flow of 45 to 46 cm.
Test specimen 14: Medium-fluidity concrete containing fine aggregate made of sea sand and slump flow of 39 to 40 cm.
Test body 15: Medium-fluidity concrete containing fine aggregate made of processed sand and slump flow of 40 to 41 cm.
Specimen 16: Medium-fluidity concrete containing fine aggregate composed of sea sand and processed sand, with a slump flow of 39 cm.

As shown in FIG. 8, in all the test bodies 13-16, the bleeding rate at the time of including a siliceous fine powder (5 kg / m < ³ >) is lower than the case where it does not include.
From the above experiment, it was confirmed that bleeding can be reduced by including siliceous fine powder. It was also confirmed that bleeding can be reduced regardless of the type of fine aggregate.

In addition, since the compounding quantity of a siliceous fine powder is as little as 5 kg / m < ³ >, it is more efficient to supply by manual work rather than supplying with a supply apparatus etc. Therefore, it is not necessary to add new equipment.

  In addition, in this embodiment, about the case where the compounding ratio of the ordinary concrete from which a slump will be 15 cm-21 cm is already known, and the mixing process S20 which determines the compounding ratio of medium fluidity concrete with reference to this compounding ratio is implemented. Although explained, it is not limited to this, and even when the blending ratio of ordinary concrete is not known, a blending ratio at which slump becomes 15 cm to 21 cm is newly obtained, and blending step S20 with reference to the blending ratio. May be implemented. In such a case, medium-fluidity concrete can be produced even in an area where the blending ratio of ordinary concrete having a slump of 15 cm to 21 cm is unknown.

  In the present embodiment, only slump and slump flow have been described as the performance of medium-fluidity concrete. However, medium-fluidity concrete produced according to the present invention has the vibration deformation test and U-shaped filling described in FIG. It also satisfies the standard performance for high quality.

Claims (4)

In the method for producing medium-fluid concrete containing water, cement, fine aggregate and coarse aggregate,
A confirmation step for confirming whether or not the AE water reducing agent is contained in the concrete in which the slump is 15 cm to 21 cm;
In the confirmation step, when the concrete contains the AE water reducing agent, a high performance AE water reducing agent and a thickener are blended instead of the AE water reducing agent, and the blending amount of the water and the cement is changed. And a blending step of blending so that the blending ratio of the fine aggregate in the total weight is larger than the blending ratio of the coarse aggregate,
A method for producing medium-fluid concrete, comprising:   In the confirmation step, when the concrete does not contain the AE water reducing agent, a high-performance AE water reducing agent and a thickener are blended, and the blending ratio of the fine aggregate in the total weight is the coarse. The method for producing medium-fluidity concrete according to claim 1, further comprising an adjusting step of mixing so as to be greater than a mixing ratio of the aggregate.   The method for producing medium-fluidity concrete according to claim 1 or 2, wherein siliceous fine powder is blended in the blending step or the adjusting step.   The medium fluidity concrete manufactured by the manufacturing method of the medium fluidity concrete as described in any one of Claims 1-3.

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