JP2000053454A - Artificial aggregate and production of artificial aggregate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an artificial aggregate high in strength, low in water absorption and capable of forcibly pumping of green concrete by granulating a raw material containing expandable shale and construction sludge and firing the granule. SOLUTION: The suitable blending ratio of the construction sludge to the expandable shale is 2-100 pts.wt. construction sludge to 100 pts.wt. expandable shale. For the granulation of the mixture of the expandable shale with the construction sludge, an extrusion type molding machine (extrusion granulator) or a pan type pelletizer is preferably used. The firing temp. of the granulated material is preferably 1,100-1,200 deg.C. The firing method of the granulated material is preferably a method using a rotary kiln or a fluidizing roaster. The shale having <=3 mm particle diameter is obtained by pulverizing further and screening middle sized shale (5-3 mm) generated by pulverizing and screening the raw shale, and the artificial aggregate is obtained by adding water into the raw material containing the resultant shale having <=3 mm particle diameter and/or fine sized shale and the construction sludge, granulating the mixture followed by firing and then screening.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an artificial aggregate using expansive shale and a method for producing the artificial aggregate.
The present invention relates to an artificial aggregate capable of achieving high-strength, low water absorption, enabling pumping of ready-mixed concrete, utilizing industrial waste as a raw material, and achieving resource saving, and a method for producing the artificial aggregate.

[0002]

2. Description of the Related Art In recent years, as an aggregate for lightweight concrete,
Primarily, artificial aggregates produced by firing expansive shale are used. The above lightweight concrete is used as concrete for construction and concrete for civil engineering,
From the purpose of use, the artificial aggregate is required to have low specific gravity (: absolute dry specific gravity) and high strength.

[0003] On the other hand, when casting concrete as a floor or wall in the middle and high layers of a building, it is necessary to pump fresh concrete containing aggregate. In this case, if the water absorption of the aggregate is high, the pipe will be blocked during pumping, so that an aggregate having a low water absorption has been required. FIG. 2 shows a manufacturing process of a conventional artificial aggregate.

[0004] A rough (expandable shale) is first coarsely ground and sieved to obtain a shale having a particle size of 20 to 5 mm (hereinafter referred to as coarse shale) and a shale having a particle size of 5 to 3 mm (hereinafter referred to as medium shale). And a shale having a particle size of 3 mm or less (hereinafter referred to as fine stone). Next, the obtained coarse crushed stone, medium crushed stone, and fine crushed stone are each fired and sieved to obtain coarse aggregate (particle size: 20%).
５5mmφ, absolute dry specific gravity: 1.29 ± 0.05), medium aggregate (particle size: 5)
~ 3mmφ, absolute dry specific gravity: 1.45 ± 0.05), fine aggregate (particle size:-
3mmφ, absolute dry specific gravity: 1.65 ± 0.05).

[0005] Coarse aggregate is used as a natural gravel, and fine aggregate is used as a concrete material corresponding to natural sand. Among the artificial aggregates manufactured by the above-described manufacturing method, coarse aggregates are mainly used for various types of civil engineering, such as roadbed materials or lightweight backing materials that cover the earth bearing capacity.

[0006] Lightweight concrete using the above-mentioned coarse aggregate is 20 to 30% lighter than ordinary concrete, and has the same performance as ordinary concrete. However, in order to further improve strength such as compressive strength, which is an important necessary property of concrete, development of an artificial aggregate having a higher strength of coarse aggregate itself and a method of manufacturing the same are desired.

[0007]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the prior art, and provides an artificial aggregate capable of pumping ready-mixed concrete with high strength and a low water absorption rate. It is intended to provide a manufacturing method.

[0008]

A first aspect of the present invention is an artificial aggregate obtained by granulating and firing a raw material containing expansive shale and civil engineering sludge. The second invention is an artificial aggregate in which a raw material containing shale having a particle size of 3 mm or less and civil engineering sludge obtained by pulverizing and sieving expansive shale and civil engineering sludge is granulated, fired, and then sieved. It is a manufacturing method of.

In the second aspect of the present invention, when performing the above-described granulation, it is preferable to perform the granulation using an extrusion molding machine. In the second aspect of the invention, it is preferable to use a rotary kiln when performing the above-described firing.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. The present inventors have conducted intensive studies in order to solve the above-mentioned problems of the prior art, and as a result, expansive shale and civil engineering sludge,
The present inventors have found that an artificial aggregate having high strength and low water absorption can be obtained by using a raw material containing construction sludge, and the present invention has been accomplished.

FIG. 1 shows an example of a process chart of the method for producing an artificial aggregate of the present invention. The rough (expandable shale) is first coarsely crushed and sieved to give coarse spar (20-5 mm), medium spar (5
３3 mm) and fine stone (3 mm or less). In the present invention, for example, medium spar (5 to 3 mm) generated by crushing and sieving a rough (expandable shale) is further crushed and sieved to obtain a shale having a particle size of 3 mm or less.

Water is added to the raw material containing the obtained shale having a particle diameter of 3 mm or less and / or the fine stone (3 mm or less) and civil engineering sludge, granulated, fired, and then sieved. This makes it possible to obtain the desired artificial aggregate having high strength and low water absorption. In the present invention, civil works, sludge generated in construction works (civil sludge, construction sludge),
That is, sludge composed of soil components is defined as civil engineering sludge.

The above-mentioned civil engineering sludge includes sludge generated in shield works in tunnel works and underground works, sludge generated in boring when concrete walls are constructed in the basement of buildings, and sludge discharged in piles in building works. And the like, and these can be used in combination. In the present invention, the suitable mixing ratio of the expansive shale and the civil engineering sludge is 2 to 100 parts by weight of the civil engineering sludge (: dry weight) with respect to 100 parts by weight of the expansive shale, and more preferably 100 weight parts of the expansive shale. For part, civil engineering sludge:
It is 50 to 100 parts by weight (: dry weight).

When the amount of civil engineering sludge is less than 2 parts by weight (: dry amount), the resultant artificial aggregate has a high water absorption rate for 24 hours, and its strength is reduced. Conversely, 100 parts by weight of civil engineering sludge (: dry weight)
When it exceeds, the water absorption of the obtained artificial aggregate for 24 hours increases. The civil engineering sludge can be used as it is, that is, in a state containing moisture or mixed with water, or may be used after drying.

The method for granulating a mixture of expansive shale, civil engineering sludge and water in the present invention is not particularly limited.
It is preferable to use an extrusion molding machine (: an extrusion granulator) and a pan-type pelletizer. In addition, by using an extrusion molding machine, an artificial aggregate can be manufactured by a method with excellent productivity, and an artificial aggregate having extremely high strength can be manufactured.

The firing temperature of the granulated product in the present invention is 1100
Preferably it is ~ 1200 ° C. When the sintering temperature is lower than 1100 ° C., the expansion of the shale does not proceed, and the absolute specific gravity becomes large.
When the temperature is higher than 00 ° C., the granulated material is melted and the absolute specific gravity becomes large. The method of firing the granulated material is not particularly limited, and a method using a rotary kiln, a method using a fluidized roasting furnace, a great-type firing furnace, or the like can be used, but a rotary kiln or a fluidized roasting furnace can be used. More preferred.

This is because the temperature of individual particles of the granulated material is made uniform by firing the granulated material using a rotary kiln or a fluidized roasting furnace, so that all the particles are uniformly foamed, expanded, and strengthened. This is because excellent artificial aggregate can be manufactured. Further, in the present invention, by using the above-mentioned extrusion molding machine (: granulator) and a rotary kiln, an artificial aggregate having a large strength can be produced by the above-described operation.
It can be manufactured by a method with excellent productivity.

In the present invention described above, in addition to expansive shale and civil engineering sludge, the following shale burned products, raw sludge, incinerated ash, and the like may be added. (: Binder) and a foaming agent may be added. [Sintered shale:] In the manufacturing process of artificial aggregates, aggregates having a large particle size are generated by bonding of granulated particles and fusion of softened pearlite particles in the firing process, resulting in artificial bone. This contributes to a decrease in the yield of materials to raw materials.

In the present invention, as shown in FIG. 1, a mass of clinker generated in the sintering step and a shale fired product on a sieve that does not satisfy the particle size required for coarse aggregate are pulverized to a part of the raw material. You may use as. [Green sludge] Preferably, the sludge containing polishing powder generated in the glass polishing process, wastewater treatment sludge generated in the petroleum refining process, pickling sludge of steel, and other harmful substances emitted from inorganic chemical factories are included. There is no raw sludge, and these can be used in combination.

[Incinerated ash:] Examples of the incinerated ash include, preferably, incineration dust of various wastes, dust such as coal ash generated from a boiler, sludge incineration ash, and a mixture thereof. [Binder (Binder)] As the binder, one or more selected from bentonite, lignin, pulp waste liquor, polyvinyl alcohol and carboxymethylcellulose are exemplified, and it is more preferable to use bentonite.

[Blowing agent] The blowing agent is not limited as long as it is a substance which generates gas by burning in the softening temperature range of shale (about 1000 ° C.) during firing of the granulated material. Is exemplified. According to the present invention described above, not only is it possible to obtain an artificial aggregate capable of high-strength, low water absorption, and pumping of ready-mixed concrete,
Civil sludge, which is industrial waste, is used as part of the raw material, and the amount of expansive shale used can be reduced, making it possible to achieve resource savings.

[0022]

EXAMPLES The present invention will be described below more specifically based on examples. An artificial aggregate was manufactured according to the manufacturing process shown in FIG. That is, it consists of shale, fine shale (-3 mm) and civil engineering sludge having a particle size of 3 mm or less obtained by further pulverizing and sieving the medium shale obtained by coarsely pulverizing and sieving the expansive shale. Raw materials having the compounding amounts shown in Table 1 were prepared (Examples 1 to 4 of the present invention).

As the civil engineering sludge, shield sludge from tunnel construction was used. Next, water was added to the obtained raw material, and after kneading with a kneading machine, granulating using an extrusion-type molding machine, calcining with a rotary kiln, and opening 20 mm
The mixture was sieved with a sieve of φ5 mmφ to produce an artificial coarse aggregate. At the time of granulation, water was added so that the water content in all the blended raw materials was 25 wt%, and the firing temperature was 1130 ° C.

For comparison, an artificial aggregate and a fired material for civil engineering sludge were produced in the same manner as described above, using the same raw material of only expandable shale having a size of 3 mm or less and the same raw material of only civil engineering sludge. Next, the absolute density, the crushing strength, and the 24-hour water absorption of the obtained artificial aggregate and fired civil engineering sludge were measured.

The absolute dry gravity and the 24-hour water absorption were measured according to JIS A
The crushing strength was measured for 50 sample particles using a uniaxial crushing tester (manufactured by Tesco), and the average value was determined. The experimental results obtained are shown in Table 1 together with the raw material mixing ratio (Examples 1 to 4 of the present invention, Comparative Examples 1 and 2).

As shown in Table 1, according to the present invention,
By using civil engineering sludge, which is waste, as a part of the raw material, it has become possible to produce the desired artificial aggregate having high strength and low water absorption.

[0027]

[Table 1]

[0028]

According to the present invention, it has become possible to obtain an artificial aggregate capable of pumping ready-mixed concrete with high strength and low water absorption, which is the object of the present invention. Furthermore, according to the present invention, since the civil engineering sludge, which is industrial waste, is used as a part of the raw material, the amount of expansive shale used can be reduced, and resources can be saved.

[Brief description of the drawings]

FIG. 1 is a process chart showing an example of a method for producing an artificial aggregate of the present invention.

FIG. 2 is a process chart showing a conventional method for producing an artificial aggregate.

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Claims (4)

[Claims] An artificial aggregate obtained by granulating and firing a raw material containing expansive shale and civil engineering sludge. 2. An artificial aggregate, which is obtained by pulverizing and sieving an expansive shale and raw material containing a shale having a particle size of 3 mm or less and civil engineering sludge, granulating, firing, and sieving. Production method. 3. The method for producing an artificial aggregate according to claim 2, wherein said granulation is performed by using an extrusion molding machine. 4. The method for producing an artificial aggregate according to claim 2, wherein a rotary kiln is used for performing the firing.