JP3140665B2 - Method for producing recycled aggregate from cement / concrete mass - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing recycled aggregate from cement / concrete lumps produced by dismantling cement / concrete structures in construction work. is there.

[0002]

2. Description of the Related Art Conventionally, in the construction work of roads, buildings and civil engineering structures, etc., cement / concrete lump generated due to demolition of cement / concrete structures is generally used as a roadbed material for road paving or for temporary roads. Used for low value-added materials such as gravel and backfill.

In this case, it is not possible to reuse the entire amount of the generated cement / concrete mass, and about half of the mass is discarded. In view of the current situation and the depletion of aggregate resources, the "Law Concerning the Use of Recycled Resources" (Recycling Law) was enforced in October 1991, and cement and concrete blocks were The demand for use as recycled aggregate is increasing rapidly.

[0004]

When a large amount of recycled aggregate for concrete is produced from a cement / concrete mass (50 to 200 ton / h), the cement / concrete mass is usually subjected to a jaw crusher, an impact crusher, and a cone crusher. Crushed by a crushing machine, etc., and classified by a screen to produce recycled aggregate. In this method, in the case of recycled coarse aggregate, the amount of mortar adhered (generally 45 to 55%) In the case of regenerated fine aggregate, the amount of paste deposit (generally 35 to 45%) is large, and therefore, in terms of water supply rate and stability of the aggregate due to sodium sulfate (hereinafter referred to as stability), it is regenerated. Ministry of Construction "Guideline for Design and Construction of Concrete Using Recycled Aggregate (Draft)" (hereinafter referred to as "Guideline (Draft)")
It is almost difficult to satisfy the quality standard values of the recycled coarse aggregates 1 and 2 and the recycled fine aggregate 1 or the production efficiency is very poor.

[0005] By the way, as a production method for satisfying these quality standard values, in the case of recycled coarse aggregate, the mortar content is removed by narrowing the interval between the aggregates of the crusher or passing the aggregate plural times. Then, the aggregate itself is rubbed with a mill such as a rod mill, a ball mill, a natural mill or the like to reduce the mortar adhesion rate, thereby removing the mortar adhering to the surface of the aggregate grain, or by polishing the aggregate grain. Remove the mortar adhering to the surface,
There is a method of reducing the mortar adhesion rate.

In the case of recycled fine aggregate, it is more difficult to remove the adhered paste portion than in the case of recycled coarse aggregate. However, these methods increase equipment size due to poor production efficiency, increase equipment costs, and increase production costs. In addition, due to the low production yield, at present, a large amount of fine powder for which reuse is hardly found is generated, and the disposal thereof requires a large amount of cost. It has not reached widespread use.

The present invention has been made in view of the above problems, and has as its object the purpose of the present invention is to make it possible to easily produce high-quality recycled aggregate for concrete and to improve the yield of recycled aggregate. To provide a method for producing recycled aggregate from cement / concrete lump which can suppress generation of fine powder having no use, reduce energy consumption of a microwave heating device, and reduce production cost of recycled aggregate. On the point.

[0008]

In order to achieve the above object, a method for producing recycled aggregate from a cement-concrete mass according to the present invention comprises heating a cement-concrete mass by a heating device at 100 to 600 ° C. And then crushing the concrete mass to the maximum aggregate size contained therein by a crusher, or crushing the cement concrete mass to the maximum aggregate size contained in the concrete by a crusher, Next, 100 to 60 by heating device
Heat treatment at 0 ° C, then remove the cement mortar adhering to the surface of coarse aggregate particles by polishing action of grinding the aggregate itself by vibration or rotation of rod mill, ball mill, autogenous mill, etc., and then classification Thus, aggregate particles having a particle diameter of 5 mm or more are taken out (claim 1).

In the method for producing recycled aggregate from a cement / concrete mass according to claim 1, the fine aggregate that passes through a 5 mm sieve generated before the heat treatment is heated to 100 to 600 ° C. by a heating device. Or a fine aggregate of 5 mm or less obtained by classification after the heat treatment or the polishing treatment is crushed by a rod mill, a ball mill, or an autogenous mill into a crushing medium having a fine aggregate amount of 0.5 to 1.5 times (about 40 mm). Crushed together with gravel, etc., and mainly fine particles of 0.15 mm or less may be removed by an air separator or the like (claim 2).

In the method for producing recycled aggregate from a cement / concrete lump according to claim 1 or 2, when the cement / concrete lump is crushed into small pieces, the cement / concrete lumps or the small crushed pieces are microwave-heated. To a temperature of 100 to 600 ° C. to weaken the cement in the cement / concrete mass, thereby facilitating removal of the cement / mortar adhering to the aggregate surface, and heated by the same microwave heating device. The air is brought into contact with the cement / concrete mass to cool the cement / concrete mass and heat the air.The heated air is brought into contact with the cement / concrete mass before entering the microwave heating device, and the cement / concrete mass is brought into contact with the cement / concrete mass. Heat recovery may be performed by preheating the concrete mass (claim 3).

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) Next, a method for producing recycled aggregate from a cement / concrete lump according to the present invention will be described in detail. 1 is a flowchart of Example 1, and FIG. 2 is Example 2.
FIG. 3 is a flowchart of Example 3.

In the method for producing recycled aggregate from a cement-concrete mass according to the present invention, the cement-concrete mass generated when the cement-concrete structure is dismantled is heated to 100 to 600 ° C. by a heating device, and then the crusher Crushing the concrete mass to the maximum aggregate size contained therein, or crushing the cement concrete mass to the maximum aggregate size contained in the concrete by a crusher, 600
℃, and then the cement or cement adhered to the surface of coarse aggregate particles by the grinding action when the aggregate itself is rubbed by vibration or rotation of a rod mill, ball mill, autogenous mill, etc.
The mortar is removed, and then aggregate particles having a particle size of 5 mm or more are taken out by classification, and recycled aggregate is produced from the cement / concrete mass.

At this time, 5 mm generated before the heat treatment is performed.
Fine aggregate of the amount passed through the sieve is 100 to 600
C. or a fine aggregate having a size of 5 mm or less obtained by classification after the heat treatment or the polishing treatment is used.
After crushing with a 1.5-fold amount of crushing medium (such as gravel of about 40 mm), fine particles of 0.15 mm or less are mainly removed by an air separator or the like. Crushing of the cement concrete block includes jaw crusher, cone crusher, impact Use a crusher such as a crusher alone or in combination to obtain a maximum particle size of 80
Crush into particles of about 20 mm.

For sieving, those having various particle size ranges are used depending on the use of the recycled aggregate. Further, the heating temperature of the crushed aggregate when performing the heat treatment is not particularly limited, but is preferably set to 100 to 600 ° C. The reason is that when the temperature is lower than 100 ° C., the cement mortar or the cement paste is hardly dewatered, so that it is difficult for the cement mortar or the cement paste to peel off from the aggregate, and when the temperature is higher than 600 ° C., the aggregate in the concrete mass tends to deteriorate. .

The heating device includes a filling dryer, a rotary dryer, a band dryer, an electric dryer,
Use an electromagnetic heater. The heat treatment by this heating device is performed at a stage before passing through a primary crusher, at a stage of coarse crushing through a primary crusher, or at a stage of medium crushing or fine crushing after passing through a secondary crusher.

For the mortar removal treatment, a mortar removal device such as a ball mill, a self-made mill or a rod mill is used. That is, in the case of the heat-treated coarse crushed material, the middle crushed material or the finely crushed material that has passed through the secondary crusher is subjected to mortar removal through a mortar removing device. In the case of a medium or fine crushed material, the crushed material is divided into coarse and fine aggregates through a 5 mm sieve, and the coarse aggregates are passed through a mortar removing device. The fine aggregate having a thickness of 5 mm or less is subjected to a paste removing process.

In the paste removal treatment, it is preferable that the crushing is performed by using a crushing medium composed of gravel of about 40 mm in a rod mill, a ball mill or a self-producing mill in an amount of 0.5 to 1.5 times the amount of fine aggregate. Here, if the amount of the crushing medium is more than 1.5 times, it is not finely divided into fine aggregate having a predetermined particle size.
If the amount is less than 0.5 times, the water absorption is not improved. Thereafter, it is separated into recycled fine aggregate and fine powder of 0.5 mm or less by a classifier including an air separator.

Next, the method for producing recycled aggregate from a cement / concrete lump according to the present invention will be described in more detail. Table 1 shows heat treatment properties of the regenerated coarse aggregate obtained by the production method of the present invention and heat treatment properties of the regenerated coarse aggregate obtained by the conventional technique. The water absorption of the recycled coarse aggregate is determined by JI
SA 1110 (Test method for specific gravity and water absorption of coarse aggregate)
It was measured according to

The mortar adhesion rate was as follows.
After soaking in N hydrochloric acid for 2 days to dissolve the cement, washing and drying the undissolved aggregate, the mass of the aggregate remaining on the 5 mm sieve was measured and calculated by the following formula.

[0020]

(Equation 1)

From Table 1, it can be seen that the water absorption does not fall below 3% in the prior art. On the other hand, according to the present invention, 250 to 400
The coarse aggregate heat-treated to ℃ is polished by a rod mill, a ball mill and a natural mill, the cement / mortar component is separated by about 20 to 40%, and the water absorption of the recycled coarse aggregate is 3
% Or less.

[0022]

[Table 1]

Table 2 shows the heat treatment properties of the recycled fine aggregate obtained by the production method of the present invention and the heat treated properties of the recycled fine aggregate obtained by the prior art. Here, the water absorption of the recycled fine aggregate is measured according to JIS A 1109 (test method of specific gravity and water absorption of fine aggregate).
The mortar paste adhesion rate was 18 N for recycled fine aggregate.
It is immersed in hydrochloric acid for 2 days to dissolve the cement component, wash and dry the undissolved aggregate, measure the aggregate mass, and calculate by the following formula.

[0024]

(Equation 2)

From Table 2, it can be seen that the water absorption does not fall below 5% in the prior art. On the other hand, according to the present invention, 250 to 400
The fine aggregate heat-treated to 0 ° C is put into a ball mill, a rod mill and a self-producing mill, and the crushing medium is further reduced to 0.5 to
When 1.5 times the amount is charged and crushed, the cement mortar and cement paste are removed from the fine aggregate by 20 to 35%, and the water absorption of the recycled fine aggregate becomes 5% or less.

[0026]

[Table 2]

Table 3 shows a comparison of the yield and the amount of fine powder generated by the reference value of the regenerated coarse and fine aggregate obtained by the present invention and the regenerated aggregate obtained by the prior art. From Table 3, it can be seen that, in the case of the regenerated coarse and fine aggregate obtained by the production method of the present invention, one type of regenerated coarse and fine aggregate obtained by the prior art is used.
The amount of fine powder generated is significantly smaller than in the case of the combination of species.

In the method for producing recycled aggregate of the present invention, the yield of recovered recycled aggregate is particularly large in one type of recycled coarse aggregate.

[0029]

[Table 3]

The recycled coarse aggregate (cement / concrete mass) is a pavement concrete shell, which is made based on civil engineering and building standards. FIG. 4 shows an example of the composition table.

[0031]

[Table 4]

(Second Embodiment) Next, a method for producing recycled aggregate from a cement-concrete lump according to the present invention according to claim 3 will be specifically described. 4 is a flow chart of Example 1 (flow chart for performing microwave heating first), FIG. 5 is a flow chart of Example 2 (flows for performing microwave heating after passing through the primary crusher), and FIG. 6 is a flow chart of Example 3. It is a (flow figure which performs microwave heating after passing through a secondary crusher).

FIG. 4 shows that the whole amount of the cement / concrete mass is firstly removed by the preheating device 1 and the microwave heating device 2.
Heat to 0-600 ° C, heat recovery unit 3 and primary crusher 4
2 shows a process of producing a recycled aggregate 9 having a small amount of cement and mortar by the secondary crusher 5, the mortar removing device 6, the paste removing device 7, and the classifier 8. 100-600 ° by the residual heat device 1 and the microwave heating device 2
In the cement / concrete mass heated to C, the cement in the cement / concrete mass is weakened, and the cement / mortar attached to the aggregate surface is easily removed. This cement / concrete lump passes through a primary crusher 4 and a secondary crusher 5 such as a jaw crusher, a cone crusher, and an impact crusher, and a cement / concrete lump having a particle diameter of less than 5 mm and a cement / lump having a particle diameter of 5 to 20 mm. Classified into concrete blocks.

Thereafter, each of them is separately passed through a mortar removing device 6 such as a rod mill, a ball mill, a natural mill, or the like.
It becomes a 20 mm recycled coarse aggregate 9, and passes through a paste removing device 7 and a classifier 8 to a recycled recycled aggregate 1 of less than 0.15 to 5 mm.
0 and fine powder 11 are obtained. The microwave heating temperature when the heat treatment is performed by the microwave heating device 2 is not particularly limited, but is preferably about 100 to 600 ° C. That is, when the temperature is 400 ° C. or less, the dewatering of the cement mortar or cement paste is small, so that these are hardly peeled off from the aggregate. At 600 ° C. or higher, the aggregate in the concrete mass is liable to be altered and crushed.

The heat treatment by the microwave heating device 2 may be performed before passing through the primary crusher 4, at the stage of coarse aggregate passing through the primary crusher 4, or during medium crushing after passing through the secondary crusher 5. Alternatively, it is performed at the stage of crushing. FIG. 2 shows a case where microwave heating is performed at a stage after passing through the primary crusher 4.
FIG. 3 shows a case where microwave heating is performed at a stage after passing through the secondary crusher 5.

Immediately before the microwave heating device 2, a residual heat device 1 by air is provided, and immediately after the microwave heating device 2, a heat recovery device 3 is provided.
The cement / concrete mass heated by the heat enters the heat recovery device 3 and comes into contact with air passing through the heat recovery device 3,
The cement / concrete mass is cooled and the air is heated, and the heated air enters the preheating device 1, and the air passing through the preheating device 1 contacts the cement / concrete mass before entering the microwave heating device 2. Thus, heat recovery is performed by preheating the cement / concrete mass.

Microwave heating is selectively absorbed by water molecules in a substance and fluctuated by electric dipoles in water molecules, as can be seen in a microwave oven that is widespread in ordinary households. A kinetic motion results, generating heat from the frictional load. On the other hand, cement and concrete mass
It is composed of an aggregate having a water content of not more than 2% and a cement portion which binds the aggregate by a hydration reaction.

Since the cement portion has a water content of 8 to 10% or more, when irradiated with microwaves, only the cement / mortar portion absorbs the microwaves and is rapidly heated. When the heating temperature is 100 ° C. or higher, the water in the cement mortar evaporates, the cement portion bonded by the hydration reaction is released, and the cement mortar becomes weak.

Therefore, during subsequent crushing and polishing by a jaw crusher, a cone crusher, an impact crusher, a road mill, a ball mill, a natural mill, or the like, only the cement mortar in the cement / concrete mass is crushed and separated, and regeneration with less adhesion of the cement mortar is performed. Aggregate is produced effectively. In addition, in order to make effective use of microwave heating energy, cement and cement immediately after microwave heating are used.
The air is brought into contact with the concrete mass, heat is recovered, and the heat is brought into contact with the cement / concrete mass immediately before microwave heating to preheat the cement / concrete mass, thereby providing microwave heating energy, that is, electric power. The consumption is reduced and the production cost of the recycled aggregate is reduced.

[0040]

According to the method of the present invention for producing recycled aggregate from a cement-concrete mass, as described above, the cement-concrete mass is subjected to a heat treatment at 100 to 600 ° C. by a heating device, and then the concrete mass is crushed by a crusher. Is crushed to a size less than the maximum aggregate size contained therein, or a cement / concrete mass is crushed to a size less than the maximum aggregate size contained in the concrete by a crusher, and then heated to 100 to 600 ° C. by a heating device. Performing the treatment, and then removing the cement mortar and cement paste adhering to the coarse aggregate grain surface by the grinding action of grinding the aggregate itself by vibration or rotation of a rod mill, ball mill, autogenous mill etc. High quality recycled aggregate for concrete can be easily manufactured, the yield of recycled aggregate can be improved, and there is no use The occurrence of powder content can be suppressed.

When the cement / concrete block is broken into small pieces, the cement / concrete block or the small pieces are heated to 100 to 600 ° C. by a microwave heating device to weaken the cement in the cement / concrete block. The cement and mortar adhering to the surface of the aggregate can be easily removed, preventing the crushing and polishing of the aggregate,
From this point, it is also possible to easily produce high-quality recycled aggregate for concrete, to improve the yield of recycled aggregate, and to suppress the generation of fine powder having no use.

Also, air is brought into contact with the cement / concrete mass heated by the microwave heating device to cool the cement / concrete mass and to heat the air. Pre-heat the cement and concrete mass by contacting it with the cement and concrete mass, thereby reducing microwave heating energy, that is, power consumption, and reducing the production cost of recycled aggregate it can.

[Brief description of the drawings]

FIG. 1 is a flowchart showing Example 1 of the first embodiment of the method for producing recycled aggregate from a cement / concrete lump according to the present invention.

FIG. 2 is a flowchart showing Example 2 of the first embodiment.

FIG. 3 is a flowchart showing Example 3 of the first embodiment.

FIG. 4 is a flowchart showing Example 1 of the second embodiment of the method for producing recycled aggregate from a cement / concrete lump according to the present invention.

FIG. 5 is a flowchart showing Example 2 of the second embodiment.

FIG. 6 is a flowchart showing Example 3 of the second embodiment.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 residual heat device 2 microwave heating device 3 heat recovery device 4 primary crusher 5 secondary crusher 6 mortar removal device 7 paste removal device 8 classifier 9 recycled aggregate 10 recycled fine aggregate 11 fine powder

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Toru Yoshikane 6-12-12 Jubancho, Nakagawa-ku, Nagoya-shi, Aichi Examiner at Daiyu Construction Co., Ltd. Atsushi Shiomi (56) References JP-A-4-21550 ( JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C04B 14/00-28/36 B09B 1/00-5/00 JOIS

Claims (3)

(57) [Claims] 1. A cement-concrete mass generated when a cement-concrete structure is dismantled is heated to 100 to 600 ° C. by a heating device, and then the concrete mass is reduced by a crusher to a size less than the maximum aggregate size contained therein. Or a cement / concrete mass is crushed by a crusher to a size equal to or less than the maximum aggregate size contained in the concrete, and then heated to 100 to 600 ° C. by a heating device, and then a rod mill, a ball mill, a spontaneous mill, etc. It is characterized by removing cement and mortar adhering to the surface of coarse aggregate particles by polishing action when the aggregate itself is rubbed by vibration or rotation, and then taking out aggregate particles with a particle size of 5 mm or more by classification. Of recycled aggregate from cement and concrete ingots. 2. A 5 mm sieve obtained by heating a fine aggregate for a 5 mm sieve generated before the heat treatment to 100 to 600 ° C. by a heating device, or obtained by classification after the heat treatment or polishing treatment. The following fine aggregates were prepared using a rod mill, a ball mill, and a natural mill to produce fine aggregates of 0.5-1.
The method for producing recycled aggregate from cement / concrete mass according to claim 1, wherein after crushing with a 5-fold amount of crushing medium (such as gravel of about 40 mm), fine particles of 0.15 mm or less are mainly removed by an air separator or the like. 3. When the cement / concrete mass is crushed into small pieces, the cement / concrete mass or the small crushed pieces is heated to 100 to 600 ° C. by a microwave heating device to weaken the cement in the cement / concrete mass. To reduce the amount of cement and mortar attached to the aggregate surface, and to contact the air with the cement and concrete mass heated by the microwave heater to cool the cement and concrete mass. The heat recovery is performed by heating the air, bringing the heated air into contact with the cement / concrete mass before entering the microwave heating device, and preheating the cement / concrete mass. A method for producing recycled aggregate from cement and concrete lumps.