JP4458639B2 - Concrete composition for immediate mold release - Google Patents

Concrete composition for immediate mold release Download PDF

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Publication number
JP4458639B2
JP4458639B2 JP2000242716A JP2000242716A JP4458639B2 JP 4458639 B2 JP4458639 B2 JP 4458639B2 JP 2000242716 A JP2000242716 A JP 2000242716A JP 2000242716 A JP2000242716 A JP 2000242716A JP 4458639 B2 JP4458639 B2 JP 4458639B2
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Japan
Prior art keywords
concrete
fly ash
method
coarse
concrete composition
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Japanese (ja)
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JP2002053361A (en
Inventor
伸郎 上原
徳治 富加見
浩展 村井
壽一 澤井
光裕 石井
誠一 長岡
Original Assignee
住友大阪セメント株式会社
四国電力株式会社
四電ビジネス株式会社
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Priority to JP2000242716A priority Critical patent/JP4458639B2/en
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    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02WCLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
    • Y02W30/00Technologies for solid waste management
    • Y02W30/50Reuse, recycling or recovery technologies
    • Y02W30/90Reuse, recycling or recovery technologies cross-cutting to different types of waste
    • Y02W30/91Use of waste materials as fillers for mortars or concrete
    • Y02W30/92Combustion residues, e.g. purification products of smoke, fumes or exhaust gases

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a concrete composition suitable for production of an immediate demolding concrete product and a method for producing an immediate demolding concrete product.
[0002]
[Prior art]
At present, concrete products are broadly divided into three types: a pouring method, a centrifugal compaction method, and an immediate demolding method. Among these, the pouring method is a method of compacting using a vibrator while putting relatively soft concrete into the mold, and the centrifugal compaction method squeezes the water inside the concrete by applying centrifugal force. This is a method for producing a concrete product with a lower water-cement ratio. The immediate demolding method adjusts the aggregate particle size so that the aggregate volume in the concrete is as large as possible, and the water-cement ratio is 30-40%. This is a method in which hard concrete of a certain degree is put into a single formwork that is made toughness, compacted by the synergistic effect of gravity while giving strong vibrations, and compression molded.
[0003]
Each of these three types of methods has its own advantages. In particular, the immediate demolding method has an economic merit that it can be formed continuously and automatically using one mold, It can be said that it is a highly useful manufacturing method from the viewpoint of environmental hygiene. Therefore, immediate demolding concrete products are widely used for various applications such as sleepers, concrete pipes, filter pipes and blocks.
[0004]
Concrete used for such an immediate demolding method is difficult to soften beyond a certain limit in order to prevent deformation due to vibration and impact during demolding and subsequent processing, etc., and is molded in a fairly hard state There is a need. On the other hand, the strength of concrete for immediate demolding with many voids in the interior is greatly affected by the cement void ratio rather than the water cement ratio compared to ordinary concrete, so it is sufficient at the time of construction. Compaction is essential. Usually, in order to fully compact cemented carbide, methods such as increasing the vibration and pressure and increasing the vibration and pressurization time can be considered, but the former method is difficult in terms of equipment. Therefore, the latter method must be selected. As a result, the rotation rate of the formwork and the like is reduced, which is a negative factor in terms of economy, which is an advantage of the immediate demolding method.
[0005]
Further, in Japan, it is generally preferred that the surface of a concrete product is smooth, but the product of the immediate demolding method naturally has a rough surface. For this reason, at present, the manufacturing method by the casting method is frequently used, and the demand for the product molded by the immediate demolding method has not increased so far.
[0006]
Various methods for making the surface of the concrete product smooth have been studied.For example, as a method of smoothing the surface by devising a construction method, a soft mortar is poured on a surface iron plate in advance, A method of covering this face iron plate after pouring super hard-mixed concrete is conceivable. However, in this method, there are constant claims such as cracks and uneven color on the surface of the molded block, that is, the mortar surface, a lot of bubbles, and mortar peeling off. In addition, as a method of smoothing the surface by devising the components contained in the cement composition, improvement measures such as using fine-grained sand and reducing the maximum size of coarse aggregate are conceivable. As a result, there is a problem that the amount of cement used increases, which is uneconomical and causes a decrease in strength.
[0007]
Furthermore, in concrete products using the immediate demolding method, the quality of the product greatly affects the quality of the product, and products with a high filling rate are heavy due to the small voids and high strength, but the product filling rate is Since it is greatly influenced by the particle size of the aggregate, when the quality of the aggregate changes, it is not always easy to cope with it.
[0008]
[Problems to be solved by the invention]
The main object of the present invention is to reduce the compaction time without greatly changing the conventional production method by the immediate demolding method, smooth the surface of the resulting concrete product, and easily change the quality of the aggregate. It is to provide a concrete composition suitable for use in an immediate demolding method.
[0009]
[Means for Solving the Problems]
As a result of intensive studies in view of the conventional technology as described above, the present inventor removes fine particles having a particle size of 20 μm or less from fly ash in the concrete composition, and the content of the fine particles having a particle size of 20 μm or less is 10 wt. % Of the fly ash coarse particles are added to ensure the same amount of cement as the conventional concrete composition for immediate demolding, and high vibration filling without increasing the viscosity of the concrete. It has been found that it is possible to obtain a concrete composition having this, and the present invention has been completed here.
[0010]
That is, the present invention provides the following concrete composition for immediate demolding system and a method for producing an immediate demolding concrete product.
1. Cement, coarse aggregate, fine aggregate, to remove the particle size 20μm or less of the fine particles from fly ash, coarse fraction of the fly ash content of the particle size 20μm or less of the fine particles is 10 wt% or less, and the water a concrete composition comprising, characterized in that it contains 20~200kg the coarse fraction of the fly ash for concrete compositions 1 m 3, the immediate demolding method for concrete compositions.
2 . A method for producing an immediate demolding concrete product, characterized in that the concrete composition of the above item 1 is kneaded, subjected to pressure vibration molding, and demolded.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
In the concrete composition of the present invention, fine particles having a particle size of 20 μm or less are removed from fly ash, and the coarse fraction of fly ash in which the content of fine particles having a particle size of 20 μm or less is 10% by weight or less (hereinafter “coarse fly ash”). ").
[0012]
Fly ash is a spherical fine powder collected by an electric dust collector among coal ash generated by coal combustion, and is defined in JIS A 6201. Since most of the particles of fly ash are spherical, the flowability of the concrete composition can be improved by using part of the sentiment with fly ash. However, if a portion of the sentiment is replaced with fly ash, the amount of cement is insufficient and the initial strength is reduced. Therefore, as a concrete composition for an immediate demolding method that requires a good strength expression from a relatively early stage. not appropriate. On the other hand, if fly ash is added without reducing the amount of cement, the viscosity of the concrete composition increases mainly due to the fine particles in the fly ash, so the fluidity decreases and the compaction time becomes longer. Furthermore, it is inappropriate as a concrete composition for an immediate demolding method.
[0013]
In the concrete composition of the present invention, fine particles having a particle size of 20 μm or less are removed from the fly ash, and coarse fly ash having a content of particles having a particle size of 20 μm or less is set to 10% by weight or less. Since there is no increase in viscosity due to the effect of fine particles, it is possible to add fly ash after securing the same amount of cement as conventional concrete composition, and to make concrete products with sufficient initial strength. be able to. Also, the added coarse fly ash can improve the fluidity of the concrete composition due to the effect of spherical particles, and guide the fine aggregate quickly and smoothly into the voids between the coarse aggregates of the concrete composition. Works. At the same time, the coarse fly ash quickly fills the remainder of the voids between the coarse aggregates with cement particles, so that the mortar formed in the space between the coarse aggregates is dense. Since the concrete interior becomes dense relatively early in this way, the vibration used for compaction is effectively transmitted not only in the mold surface but also in the concrete, so that the compaction speed is dramatically improved. Furthermore, the surface of the concrete product becomes smooth because the amount of powder in the concrete can be increased without deteriorating the compaction characteristics.
[0014]
In the present invention, fly ash coarse particles are obtained by removing fine particles having a particle size of 20 μm or less from fly ash specified in JIS A6201, and making the content of fine particles having a particle size of 20 μm or less 10% by weight or less. If it is a grain fraction, it can be used without particular limitation.
[0015]
The instant demolding concrete composition of the present invention includes an aggregate composed of coarse aggregate and fine aggregate, cement, and water in addition to the coarse fly ash described above, kneaded, By molding, the desired concrete product can be obtained. Furthermore, various cement admixtures such as high performance water reducing agents (for example, AE agent, AE water reducing agent, water reducing agent, high performance AE water reducing agent, etc.) may be blended in the concrete composition as necessary. it can.
[0016]
Components other than the coarse fly ash blended in the concrete composition of the present invention may be the same as those used in the conventional concrete composition for immediate demolding. For example, as the cement, various portland cements, mixed cements, and the like can be used. Coarse aggregates, fine aggregates, and the like can be the same as those blended into known concrete compositions.
[0017]
In the concrete composition for immediate demolding system of the present invention, the amount of coarse fly ash is mixed with cement, coarse aggregate, fine aggregate, coarse fly ash, water, and admixture for cement as necessary. About 1 m 3 of the concrete composition made from the above, it is necessary to make it about 20 to 200 kg , and preferably about 30 to 100 kg.
[0018]
In the concrete composition for immediate demolding method of the present invention, the blending ratio of components other than coarse-grained fly ash may be the same as that of the conventional concrete composition for immediate demolding method.
[0019]
The concrete composition for immediate demolding method of the present invention can be made into a concrete product by a normal immediate demolding method. That is, after the concrete composition is kneaded and subjected to pressure vibration molding, it is demolded and cured to obtain a concrete product. Known methods can be employed as they are for the kneading method, the pressure vibration molding method, the curing method, and the like.
[0020]
【The invention's effect】
The concrete composition for immediate demolding system of the present invention has excellent vibration filling properties, and can reduce the compaction time when a concrete product is produced by the immediate demolding system. In addition, the concrete composition of the present invention improves the filling property by blending coarse fly ash, and there is little difference in filling property due to the difference in the type of aggregate, and it can easily cope with changes in the quality of the aggregate. it can.
[0021]
Furthermore, the resulting concrete product has sufficient strength and its surface is a good smooth surface.
[0022]
【Example】
Hereinafter, the present invention will be described in more detail with reference to examples.
Example 1
About each concrete composition of the mixing | blending shown in the following Table 1, using the biaxial forced kneading mixer with a capacity | capacitance of 55 liters, it knead | mixes the kneading amount of 1 batch as 35 liters, and the consistency test method of the concrete for RCD ( Draft) Void ratio and VC value were measured according to (JSCE-F507). The results are shown in Table 2 below.
[0023]
In Examples and Comparative Examples, the optimum fine aggregate rate was selected so that the unit water amount and the cement amount were constant and the porosity was minimized.
[0024]
The types of raw materials used are as follows.
(1) Cement: ordinary portland cement (Blaine 3350cm 2 / g, density of 3.15g / cm 2, manufactured by Sumitomo Osaka Cement Co., Ltd.)
(2) Coarse-grain fly ash (Blaine 1900 cm 2 / g, density 2.21 g / cm 2 , fine particle content of particle size 20 μm or less: about 5% by weight, manufactured by Techno Resource Co., Ltd.)
(3) Coarse aggregate: Crushed stone 2005 (density 2.68 g / cm 2 , FM 6.86, Takatsuki)
(4) Fine aggregate: River sand (Density: 2.57 g / cm 2 , FM3.04, Yasukawa)
[0025]
[Table 1]
[0026]
[Table 2]
[0027]
The concrete compositions of Examples 1 to 4 had a smaller porosity than the composition of Comparative Example 1 that did not contain coarse fly ash. From this result, it is considered that a concrete product having a solid and smooth surface can be obtained according to the concrete composition containing coarse fly ash.
[0028]
In addition, the concrete products of Examples 1 to 4 had a smaller VC value than the composition of Comparative Example 1. The VC value is a numerical value indicating the consistency of the super hard kneaded concrete, and it can be judged that the filling speed by vibration press molding is high when this value is small. This is because coarse fly ash smoothly guides fine aggregates and cement particles, and becomes a concrete that is dense from an early stage, so vibration is effectively transmitted in the concrete. It is done. Accordingly, the concrete mixed with coarse fly ash is judged to have a high compaction speed and good workability.
[0029]
In addition, as shown in Comparative Example 2, if the coarse fly ash is added excessively, both the porosity and the VC value are larger than the composition of Comparative Example 1 not containing the coarse fly ash, which is inappropriate. It is.

Claims (2)

  1. Contains coarse particles of fly ash in which fine particles with a particle size of 20 μm or less are removed from cement, coarse aggregate, fine aggregate, fly ash, and the content of fine particles with a particle size of 20 μm or less is 10 wt% or less, and water a concrete composition, characterized by containing 20~200kg the coarse fraction of the fly ash for concrete compositions 1 m 3, the immediate demolding method for concrete compositions.
  2. A method for producing an immediate demolding concrete product, wherein the concrete composition of claim 1 is kneaded, subjected to pressure vibration molding, and demolded.
JP2000242716A 2000-08-10 2000-08-10 Concrete composition for immediate mold release Active JP4458639B2 (en)

Priority Applications (1)

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Application Number Priority Date Filing Date Title
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JP4458639B2 true JP4458639B2 (en) 2010-04-28

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Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
PL358677A1 (en) 2000-03-14 2004-08-09 James Hardie Research Pty Limited Fiber cement building materials with low density additives
NZ528306A (en) 2001-03-02 2005-02-25 James Hardie Int Finance Bv A method and apparatus for forming a laminated sheet material by spattering
MXPA05003691A (en) 2002-10-07 2005-11-17 James Hardie Int Finance Bv Durable medium-density fibre cement composite.
US7998571B2 (en) 2004-07-09 2011-08-16 James Hardie Technology Limited Composite cement article incorporating a powder coating and methods of making same
CA2648966C (en) 2006-04-12 2015-01-06 James Hardie International Finance B.V. A surface sealed reinforced building element
JP4854611B2 (en) * 2007-07-05 2012-01-18 宇部興産株式会社 Hakuhana generation suppression type immediate demolding concrete block and Hakuhana generation prediction method
US8209927B2 (en) 2007-12-20 2012-07-03 James Hardie Technology Limited Structural fiber cement building materials

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