JP2003146723A - Concrete composition and mortal composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a concrete composition and a mortal composition respectively giving concrete and mortal without necessitating increase of unit water quantity and without necessitating remarkable increase of adding quantity of an expensive auxiliary AE (air-entraining) agent, even though a non-calcined coal ash granulated material is added. SOLUTION: It is found out that concrete and mortal to which coal ash is added in a form of a non-calcined granulated material as a portion of fine aggregate give the same hardened bodies as those when general fine aggregate is used without incurring increase of unit water quantity. The concrete composition and the mortal composition are characterized in that the non-calcined coal ash granulated material is used as a portion of fine aggregate and the ratio of the non-calcined coal ash granulated material in the fine aggregate is <=50 pts.vol.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a concrete composition and a mortar composition characterized by containing an unfired coal ash granulated product as one of the components of a fine aggregate.

[0002]

2. Description of the Related Art About 70% of coal ash, which is generated as a large amount as an industrial by-product, is effectively used, but the rest is landfilled. It's a problem. As an alternative to landfilling, many methods have been disclosed for achieving effective use as a material for construction materials, which is expected to consume a large amount of resources.
However, most of them are used as artificial lightweight aggregates that are manufactured through a firing / foaming process at high temperatures, or as general aggregates by firing granules or as inorganic admixtures that reduce the amount of unburned carbon. It is about doing. Although this method is one of the useful methods for utilizing coal ash, it has a problem that it is an energy-consuming method because it requires firing at high temperature. On the other hand, there are few disclosed technologies relating to the production and use of unfired artificial aggregate or artificial sand by only granulation that does not require energy for firing at high temperature. For unbaked artificial aggregate or artificial sand granulated sand using coal ash, see, for example, Japanese Patent Application Laid-Open No.
No. 00-154526, JP-A No. 11-130494,
Most of the techniques relating to the granulation method and the production method disclosed in JP-A No. 11-263658 are related to the use of the granulated material such as a pavement material as disclosed in JP-A No. 2001-90012. Although there are some usage techniques to be applied, there is no conventional usage technique for fine aggregate for concrete or mortar.

When coal ash is added as powder to concrete as an admixture, it is necessary to increase the unit water content in order to maintain the same slump value, but an increase in the unit water content leads to a decrease in concrete durability. , Furthermore, when the amount of coal ash increases, the viscosity becomes high and it becomes difficult to handle.
Since the unburned carbon contained in the coal ash adsorbs the AE agent, there is a problem that the addition amount must be increased in order to secure a predetermined air amount, which leads to an increase in cost.

[0004]

DISCLOSURE OF THE INVENTION The present invention does not require an increase in the amount of unit water, even though unburned coal ash granules are added, and significantly increases the amount of expensive auxiliary AE agent added. An object of the present invention is to provide a concrete composition and a mortar composition that give concrete that does not need to be increased.

[0005]

MEANS FOR SOLVING THE PROBLEMS The present inventors have found that concrete and mortar to which coal ash is added as a part of fine aggregate in the form of unsintered granules do not increase the amount of unit water, and The present invention has been completed by finding that a hardened body equivalent to the case where aggregate is used is provided. That is, the first invention of the present application uses the unburned coal ash granulated material as a part of the fine aggregate,
The present invention relates to a concrete composition characterized in that the proportion of the unburned coal ash granulated material in fine aggregate is 50 parts by volume or less. Further, a second invention of the present application is characterized in that the unburned coal ash granulated product according to the first invention is manufactured by mixing and granulating coal ash, cement and inorganic fine particles. Regarding things. 3rd invention of this application WHEREIN: The unburned coal ash granulated material in the said 1st or 2nd invention respectively WHEREIN: One or more selected from the hydroresidue discharged as a by-product from the magnesia manufacturing process from cement clinker dust and seawater is an inorganic substance The present invention relates to a concrete composition manufactured by using as fine particles. Furthermore, the fourth to sixth inventions of the present application relate to the inventions in which the objects of application in the first to third inventions are changed from concrete compositions to mortar compositions, respectively.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION What is used in the present invention by substituting a part of the fine aggregate is an unsintered granule containing coal ash as a main component. Coal ash is fly ash having an average particle size of about 10 to 40 μm, which is collected by a dust collector of a pulverized coal combustion boiler, but it is preferable to add various additives such as a paste material in the granulation for granulation. . The most preferred additive is cement. Cement is a component and acts as a sizing material, but commonly used ordinary Portland cement or blast furnace cement type B can be preferably used. In granulating, it is preferable to add inorganic fine particles as a granulating aid. Inorganic particles have an average particle size of 1
The particle size is preferably 0 μm or less, and for example, cement kiln dust or hydro residue discharged as a by-product from the magnesia manufacturing process can be preferably used. In addition,
Hydro residue is CaCO ₃ (aragonite) which is a by-product when obtaining dolomite by adding calcium hydroxide to seawater.
And Mg (OH) ₂ as the main component.

The preferred mixing ratio of each component is 50% coal ash.
˜95 parts by mass, cement 2 to 25 parts by mass, and inorganic fine particles 3 to 45 parts by mass. Coal ash, cement, and inorganic fine particles are mixed in a mixer that is generally used for dry mixing of powders such as a V-shaped mixer, a ribbon mixer, etc., and an appropriate amount of water is added to the mixture. Granulation can be performed using a general granulator such as a stirring granulator. The use of the conical screw mixer not only enables automation of a series of operations from the input of solid raw materials such as coal ash, cement, and inorganic fine particles and water to the discharge of granulated materials, but also has a wide particle size distribution. Is obtained, which is the preferred method.

As the granulated product, it is preferable to use one having an average particle size of 0.5 to 1 mm as compared with the existing mass. Further, it is preferable that the abundances of particles having a particle size smaller than 0.15 mm and larger than 5 mm are 20% by mass or less and 5% by mass or less, respectively. In the present invention, this granulated product is hereinafter referred to as granulated sand.

The present invention is characterized in that 50% or less of the volume of the fine aggregate constituting the concrete or mortar is replaced with the same volume of the granulated sand. If the replacement rate by the granulated sand is too high, the increase in the unit water amount cannot be ignored, which leads to an increase in the addition amount of the expensive AE agent. On the other hand, although the addition effect of the granulated sand is exhibited even with a small amount, it is preferable that the substitution rate is 10% by volume or more from the viewpoint of economical efficiency and effective use of coal ash.

In the present invention, it is the same as a general concrete composition and mortar composition except that a part of the fine aggregate is replaced with granulated sand, and the preparation of concrete or mortar is the same as general concrete and mortar. You can do it. That is, slump, air volume,
The water-cement ratio and the fine aggregate ratio are set, and a predetermined amount of cement, fine aggregate, granulated sand, coarse aggregate and a water reducing agent are mixed so as to satisfy the set values, and further, a dispersant if necessary. , A filler, an antifoaming agent, or the like, to which a general amount of a commonly used admixture is added, and water is added to obtain a predetermined water-cement ratio. The mixing method and kneading method are not particularly limited, and general methods can be used without any problems. The concrete or mortar after kneading is filled into the formwork such as ready-mixed concrete, general casting secondary products, immediate demolding products such as interlocking blocks and building blocks, dewatering press molding products such as thick slate, etc. A concrete secondary product can be obtained by a general manufacturing method that includes demolding and curing.
Hereinafter, the present invention will be described in more detail by showing specific examples.

[0011]

Examples (1) Granulated sand A predetermined amount of coal ash and a predetermined amount of Portland cement were mixed with a conical screw mixer (effective volume 100 l, revolution 4 rp).
m, rotation 27 rpm) for 10 minutes, and then a predetermined amount of water was added to carry out granulation. After mixing with water, stirring and mixing were continued for 40 minutes to obtain a granulated product. The granulated product was aged at room temperature for 7 days to obtain granulated sand. Table 1 shows the raw material mixture ratio and the characteristics of the obtained granulated sand.

(2) Preparation and evaluation of concrete The following raw materials were used for the preparation of concrete.・ Cement: Normal Portland cement ・ Fine aggregate: Sea sand from Hakata, Fukuoka Density: 2.59 g / cm ³・ Coarse aggregate: Crushed stone from Yamaguchi 2005, Density: 2.70 g /
cm ³ (1005 for immediate demolding concrete) ・ AE water-reducing agent: NBM Pozzolis No. 7
0 Auxiliary AE water reducing agent: NMB Micro Air 3
03 (In case of concrete for immediate demolding Micro Air 1
01)

A predetermined amount of cement, fine aggregate, granulated sand, fly ash, coarse aggregate, AE water reducing agent and auxiliary AE water reducing agent were mixed with a pan-type forced kneading mixer for 90 seconds to obtain concrete. Concrete has a water-cement ratio of 50% or more, and the slump and the target amount of air are 15% each.
cm and 4.50% of ordinary concrete, and water cement ratio of 32%, and a target filling rate of 90% or more can be roughly classified into two types of concrete for immediate demolding.

With respect to the obtained concrete, a hardened body was prepared and evaluated.・ Normal concrete: Measure the compressive strength of 28-day-old cylinders with a diameter of 10 × 20 cm. ・ Immediate demolding concrete: 10 × 20 × 7.5-cm ILB specimens with 7-day and 28-year-old materials. Measurement of day bending strength The strength measurement results are shown in Tables 2 and 3. Also, for ordinary concrete, the amount of granulated sand added and the concrete unit water amount,
1 to 3 show the relationship between the required amount of auxiliary AE agent and the compressive strength of the cured body.
Shown in. FIG. 4 shows the relationship between the amount of granulated sand added and the bending strength of the hardened body for the concrete for immediate demolding.

[0015]

[Table 1]

[0016]

[Table 2]

[0017]

[Table 3]

In the case of ordinary concrete, the amount of concrete unit water increases as the amount of granulated sand added increases, but the rate of increase is smaller than that of the addition of unformed fly ash. The unit water volume is
It is less than or equal to the standard value set by the Concrete Society. Also,
The amount of the auxiliary AE agent used hardly depends on the amount of granulated sand added, and a low amount of 1/10 or less of the amount of unformed fly ash added is sufficient. Furthermore, the compression strength of the hardened product does not improve with the addition amount unlike the case of adding unmolded fly ash, but the rate of decrease due to the addition of granulating sand is small, and it can be sufficiently used as a substitute for fine aggregate. I understand.

On the other hand, when the granulated sand is used as an instant demolding concrete, the unit water amount hardly changes even if the replacement rate of the fine aggregate by the granulated sand increases, so that the moldability and the plasticity immediately after demolding are improved. The effect on deformation is small, and it can be seen that in this case as well, it can be used as a fine aggregate substitute. Granulated sand addition amount 215kg / m ³ or less, fine aggregate volume substitution rate 20%
If it is below, the bending strength of the secondary product is the standard value 4.9 N /
It can be seen that a practicable block can be obtained by exceeding mm ² . Also, granulated sand 500 kg / m ³ , volume replacement rate 5
A bending strength of 4.5 N / mm ² is obtained even at about 0%, and it is sufficiently applicable to products for use in places such as parks and sidewalks where the load applied is small.

[0020]

The concrete and mortar of the present invention are
It has become possible to use unburned granules of coal ash as a substitute for fine aggregate. It provides a method of reusing coal ash whose treatment is a problem, and also helps mitigate the problem of natural fine aggregate depletion. Moreover, since firing is not required for producing the granulated product, there is also an advantage that the environmental load during the production can be reduced.

[Brief description of drawings]

FIG. 1 is a diagram showing the relationship between the added amount of granulated sand and the concrete unit water amount.

FIG. 2 is a diagram showing the relationship between the amount of granulated sand added and the amount of auxiliary AE agent required.

FIG. 3 is a diagram showing the relationship between the amount of granulated sand added and the compressive strength of a secondary product of ordinary concrete.

FIG. 4 is a graph showing the relationship between the amount of granulated sand added and the bending strength of an immediate demolding concrete secondary product.

Continued front page    (72) Inventor Toshikatsu Onishi             Yamaguchi Prefecture Ube City Oji Kogushi Oki Mountain 1-6 shares             Ceremony Ube Mitsubishi Cement Research Institute Ube Center             -In F-term (reference) 4G012 PA26 PA30

Claims (6)

[Claims] 1. An unburned coal ash granulated product is used as a part of fine aggregate, and the ratio of the unburned coal ash granulated product in the fine aggregate is 50 parts by volume or less. Concrete composition. 2. The concrete composition according to claim 1, wherein the unburned coal ash granulated product is produced by mixing and granulating coal ash, cement and inorganic fine particles. 3. An unburned coal ash granulated product is produced by using, as inorganic fine particles, one or more selected from hydro-residues discharged as by-products from a magnesia production process from cement clinker dust and seawater. The concrete composition according to claim 1 or 2, characterized in that: 4. The unburned coal ash granulated product is used as a part of fine aggregate, and the ratio of the unburned coal ash granulated product in the fine aggregate is 50 parts by volume or less. Mortar composition. 5. The mortar composition according to claim 4, wherein the unburned coal ash granulated product is produced by mixing and granulating coal ash, cement and inorganic fine particles. 6. An unburned coal ash granulated product is produced by using, as inorganic fine particles, one or more selected from hydro-residues discharged as by-products from a magnesia manufacturing process from cement clinker dust and seawater. The mortar composition according to claim 4 or 5, characterized in that