KR20040087062A - Method to recover high quality aggregates from waste concrete and that product - Google Patents

Abstract

PURPOSE: A method for preparing a recycled aggregate and a recycled aggregate prepared by the method are provided, to obtain the recycled aggregate having the quality equal to or superior to that of a natural aggregate from the cement·concrete mass for reducing environmental pollution. CONSTITUTION: The method comprises the steps of heating the cement·concrete mass generated by the destruction of cement·concrete construction at a temperature of 100-600 deg.C; pulverizing the heated one into a size less than a maximum aggregate size; heating the pulverized one at a temperature of 100-600 deg.C to remove the cement·mortar part adhered to the surface of coarse aggregate particles by the vibration or rotation of rods or balls or the polishing due to the friction of aggregate; and collecting aggregate particles by classification.

Description

Method for recovering recycled aggregate from cement or concrete mass and its product {Method to recover high quality aggregates from waste concrete and that product}

The present invention relates to a method for producing recycled aggregates from cement and concrete agglomerates and products thereof, and more particularly, to conserving natural resources by recovering high-quality recycled aggregates having a quality equal to or higher than that of natural aggregates from cement and concrete agglomerates. The aim is to minimize pollution and environmental pollution, which in turn significantly improves the quality and reliability of products.

As is well known, domestic construction wastes amounted to 108,520 tons per day in 2001. Since such a large amount of construction wastes are generated in densely populated cities and the surrounding areas, long distance transportation to landfills or intermediate treatment sites is inevitable. Due to complex factors such as lack of management system, lack of awareness of emitters, shortsighted for-profit purveyor of processors, it is not possible to carry out or process properly in landfill or intermediate treatment ground, and illegal dumping of nearby mountain or human resources is a serious problem. It is causing. In addition, aggregates, which were recognized only as abundant natural resources, could not meet the rapidly increasing demand due to overheating or revitalization of the construction industry, resulting in severe aggregate supply and demand imbalance in the next 5 to 10 years. It is expected. Under these backgrounds, resource conservation and effective use are becoming more important in society in recent years, and interest in recycling and resource conservation is intensifying from everyday life to various industrial fields. For example, in the case of 200 construction companies that were designated as key management targets under the "Resource Conservation and Recycling Promotion Act", in 1995, 62.2% of earth and sand, 35.0% of waste concrete, 48.5% of the waste asphalt concrete was recycled, indicating that the construction wastes are being recycled by large construction companies.

However, the existing technology for manufacturing recycled aggregates only uses rock crushers and curb removers, and the cement paste attached to the aggregates is not sufficiently removed to be used as structural aggregates. It is impossible to apply to structural concrete because of the durability of concrete. For this reason, the recycled aggregate currently produced is not used as a material for structural concrete, but is used as roadbed or most of it is landfilled.

1, 2 and Table 1 to illustrate this, it shows the particle size distribution of the recycled aggregate produced from domestic waste concrete recycling companies, the cement mortar content at each particle size, specific gravity, wear rate, absorption rate by particle size. The particle size of recycled aggregate was 20.2% for 20-25mm, 21.6% for 15-20mm, 38.8% for 10-15mm, 18.3% for 5-10mm, and 98.8% of the total. The cement mortar adhesion amount was repeated 7 times and showed the average value and the maximum and minimum value. The average cement mortar adhesion amount of 20 to 25 mm was 17.4%, 20 to 15 mm was 23.5%, 15 to 10 mm was 35.5%, and 10 to 5 mm was 57.6%. As the furnace particle size decreased, the cement mortar adhesion increased. There were no significant differences according to the particle size of the regenerated aggregate, the dry weight ratio, the absorption rate, and the wear rate of the recycled aggregates. The water absorption rate and the wear rate increased significantly as the particle size decreased. The tendency of the absorption rate and wear rate shows the same tendency as the content of cement mortar attached to the aggregate according to the particle size, and it can be seen that the degradation of physical properties of the recycled aggregate such as the absorption rate is mainly influenced by the cement mortar attached to the aggregate of waste concrete. The KS standards for the absorption, wear and specific gravity of coarse aggregates for concrete show that the absorption rate and wear rate do not meet the criteria for absorption rate and wear rate of 3.0 or less, 2.5 or more of dry weight, and 40% or more of wear rate.

TABLE 1

Classification (mm) Weight ratio Water absorption Wear rate (%) 5-10 2.64 7.08 45.2 10-15 2.63 4.62 32.2 15-20 2.66 3.58 28.8 20-25 2.67 2.43 15.2

As mentioned above, the quality of recycled aggregates produced from waste concrete recycling companies is significantly lower than that of natural aggregates, so it is difficult to reuse them. Therefore, in view of the reality of environmental protection and conservation of natural resources, appropriate measures for this are urgently needed. This occurred.

The present invention has been made to solve the above problems of the prior art, and the first object is to produce recycled aggregates having the same or higher quality than natural aggregates from cement and concrete mass, and the second object is The process is simple and the processing time is fast so that it is economical. The third purpose is to minimize environmental pollution and contribute to the preservation of natural resources. The fourth purpose is to greatly improve the quality and reliability of the product. The present invention provides a method for producing recycled aggregates and its products from lumps of cement and concrete.

In order to achieve the above object, the present invention provides a method for producing recycled aggregate,

Heating the cement concrete mass produced when dismantling the cement concrete structure to 100 to 600 ° C. by a heating device; Crushing the concrete mass by the crusher to below the maximum aggregate size contained therein, or by crushing the cement / concrete mass to below the maximum aggregate size contained in the concrete; After the crushing step is heated to 100 ~ 600 ℃ by a heating device to the cement mortar portion adhered to the surface of the coarse aggregate particles by vibrating or rotating rod, ball, etc. or by the grinding action when rubbing the aggregate itself. Removing; Recovering aggregate particles by classification after the removal step; provides a method for producing recycled aggregates from the cement / concrete lump, characterized in that it comprises a.

Hereinafter, described in detail with reference to the accompanying drawings a preferred embodiment of the present invention for achieving this purpose are as follows.

1 is a particle size distribution of recycled aggregate produced from waste concrete recycling company.

Graph shown.

2 is the aggregate size of the recycled aggregate produced from waste concrete recycling company

Graph showing the cement mortar content according.

3 shows that 20-25 mm of recycled aggregate was treated by the treatment process of the present invention.

Graph showing cement mortar removal rate over time.

4 shows that 15-20 mm of recycled aggregate was treated by the treatment process of the present invention.

Graph showing cement mortar removal rate over time.

5 shows that the recycled aggregate of 10 to 15 mm was treated by the treatment process of the present invention.

Graph showing cement mortar removal rate over time.

6 shows that 5 to 10 mm of recycled aggregate was treated by the treatment process of the present invention.

Graph showing cement mortar removal rate over time.

Fig. 7 Aggregate when the recycled aggregate is treated by the treatment step of the present invention.

A graph showing the wear rate with changes in particle size and heating temperature.

8 is aggregate when the recycled aggregate is treated by the treatment step of the present invention.

Graph showing absorption rate with change in particle size and heating temperature.

Fig. 9 Aggregate when the recycled aggregate is treated by the treatment step of the present invention.

Graph showing specific gravity with changes in particle size and heating temperature.

10 shows heating when the recycled aggregate is treated by the treatment step of the present invention.

A graph showing the amount of cement mortar remaining with temperature.

The method for producing recycled aggregates from the cement and concrete agglomerates applied to the present invention and their products will be described with reference to FIGS. 3 to 10.

In the following description of the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

The following terms are terms set in consideration of functions in the present invention, which may vary depending on the intention or custom of the producer, and their definitions should be made based on the contents throughout the specification.

First, the present invention is a heat pulverization method in which the cement paste is dehydrated and weakened by heating the cement and concrete agglomerates, and then crushed to the extent that the aggregate is not crushed to selectively remove mortar and cement paste adhered to the aggregate. By recovering high-quality recycled aggregates, when the aggregates are heated to 600 ° C or higher, the quality of the aggregates decreases due to dehydration of the clay minerals contained and the crystal transition of SiO _2. However, when the aggregates are heated below 600 ° C, the aggregate quality is almost affected. On the basis of the fact that it does not affect the aggregate, the present invention proposes a method of recovering recycled aggregate having a quality equal to or higher than that of natural aggregate.

In more detail, the step of heating the cement concrete mass generated when dismantling the cement concrete structure to 100 ~ 600 ℃ by a heating device; Crushing the concrete mass by the crusher below the maximum aggregate size included in the heating step or crushing the cement and concrete mass by the crusher below the maximum aggregate size contained in the concrete; After the crushing step is heated to 100 ~ 600 ℃ by a heating device to the cement mortar portion adhered to the surface of the coarse aggregate particles by vibrating or rotating rod, ball, etc. or by the grinding action when rubbing the aggregate itself. Removing; And recovering the aggregate particles by classification after the removing step.

In addition, the present invention is a fine aggregate of 5mm or less obtained by heating the fine aggregate of 5mm sieve passing before the heat treatment to 100 ~ 600 ℃ by a heating device, or by classification after the heat treatment or after polishing treatment, After crushing at the same time as the crushing medium (gravel, etc.) by a rod mill, a ball mill, etc., the fine powder of 0.15 mm or less is mainly removed by an air classifier.

In the present invention, when the cement concrete mass is crushed, the cement concrete mass or crushed substance is heated to 100 to 600 ° C. by a heating device, and the cement mortar that is deteriorated by cement in the cement concrete mass is adhered to the aggregate surface. Cement concrete before making the part easy to remove, and bringing air into contact with the cement concrete mass heated by the heating apparatus, cooling the cement concrete mass and simultaneously heating the air, and putting the heated air into the heating apparatus. It is characterized by contacting the mass and preheating the cement concrete mass.

Furthermore, in the present invention, the crushing by the grinding action of the aggregate itself can be used to select either dry or wet.

Meanwhile, the present invention may be variously modified and may take various forms in applying the Portland cement.

And it is to be understood that the invention is not limited to the specific forms referred to in the above description, but rather includes all modifications, equivalents and substitutions within the spirit and scope of the invention as defined by the appended claims. It should be understood that.

Referring to the production method of the recycled aggregate from the present invention cement / concrete mass configured as described above and the action of the product is as follows.

First, the present invention breaks up the cement concrete mass produced when dismantling the cement concrete structure to the maximum aggregate size or less, and heats it to 100-600 ° C. by a heating device, and the vibration or rotation of the rod mill, ball mill, etc. The cement mortar portion adhering to the aggregate particle surface is removed by the polishing action when rubbing the aggregate itself. Then, the aggregate particle is recovered by classification.

Treatment of cement and concrete lumps through the process of the present invention will produce recycled aggregates having a higher quality than or equal to natural aggregates and can be used equivalently to natural aggregates.

Hereinafter, embodiments of the present invention will be described in detail.

EXAMPLE

For the heating, crushing and grinding experiments of cement and concrete mass, cylindrical rotors of 710 mm in diameter and 510 mm in length were prepared. As a grinding medium, a ball of about 47 cm in diameter and about 400 g in weight was used.

Recycled aggregate produced from domestic waste concrete processing company is heated between 200 ℃ and 500 ℃ and divided into 20 ~ 25mm, 15 ~ 20mm, 10 ~ 15mm, 5 ~ 10mm, and then 20kg of sample and 20kg of ball in the manufactured rotary mill. Cement mortar removal rate was analyzed from the aggregate while rotating to 2 hours.

3 to 6 show the separation rate of cement mortar from aggregates when ball milling after heating and heating at 100 ° C. interval to 200 ° C. to 500 ° C. for each aggregate by particle size. It can be seen that the separation rate of cement mortar increases as the heating temperature increases for each particle size, and this tendency is apparent at 10-25 mm, and the difference in cement mortar separation rate according to preheating temperature is not large at 5-10 mm. When the sample was not preheated, the cement mortar separation rate at 10-25mm was less than 40% when ball milling for 2 hours, but more than 70% of cement mortar was accumulated from aggregate when the ball milling time was 2 hours after heat treatment at 500 ° C. At 5-15mm, more than 85% of cement mortar was separated under the same conditions. Also, for the ball milling time, the higher the preheating temperature and the smaller the aggregate size, the shorter the separation of cement mortar from the aggregate was.

7 to 9 show the specific gravity, water absorption, and wear rate values after the aggregates of each particle size were heated to 200 ° C. to 500 ° C. for 1 hour at 100 ° C., and then ball milled for 1 hour with 20 kg of aggregates and 20 kg of balls. For comparison, the specific gravity, water absorption, and abrasion rate of the recycled aggregate itself are indicated. Wear rate measurement was performed according to KS F 2508. As shown in FIG. 7, the wear rate of the recycled aggregate itself and the heat treatment and ball milling samples showed a tendency to decrease as the heating temperature was increased. However, the wear rate of the recycled aggregate for concrete was 40% or less. If you consider, it does not mean much. However, the Korean industrial standard of recycled aggregate for concrete has a specific gravity of 2.5 or more, and as shown in FIG. Figure 9 shows the absorption rate, the absorption rate is obviously reduced as the heating temperature is increased, the absorption rate of the aggregate aggregate of 5-10mm aggregate was 7.08 itself, but the ball milling sample after heating to 500 ℃ the absorption rate was reduced to 1.93. 10 shows the contents of the recycled aggregate raw material, the heating temperature and the content of the residual cement mortar after ball milling, and it can be seen that the content of the residual cement mortar can be lowered to less than 6.0% at 500 ° C. for the 10-25 mm aggregate. Therefore, if heated above 400 ℃ could satisfy the Korean industrial standard of natural aggregate for concrete.

As described in detail above, the present invention is intended to produce recycled aggregates having a high quality equivalent to or greater than that of natural aggregates from cement and concrete agglomerates, and the second object is a simple process and a fast treatment time. The third purpose is to minimize environmental pollution and contribute to the preservation of natural resources, and the fourth objective is a very useful invention that can greatly improve the quality and reliability of the product.

Claims (5)

In the manufacturing method of the recycled aggregate, Heating the cement concrete mass produced when dismantling the cement concrete structure to 100 to 600 ° C. by a heating device; Crushing the concrete mass by the crusher to below the maximum aggregate size contained therein, or by crushing the cement / concrete mass to below the maximum aggregate size contained in the concrete; After the crushing step is heated to 100 ~ 600 ℃ by a heating device to the cement mortar portion adhered to the surface of the coarse aggregate particles by vibrating or rotating rod, ball, etc. or by the grinding action when rubbing the aggregate itself. Removing; Recovering aggregate particles by classification after the removal step; Method of producing recycled aggregates from the cement / concrete lump, characterized in that it comprises a. According to claim 1, 5 mm or less fine aggregates obtained by heating the fine aggregates for the passage of 5 mm sieves generated before the heat treatment to 100 to 600 ° C. by a heating apparatus, or obtained by classification after the heat treatment or after the polishing treatment, are loaded into the mill. A method for producing recycled aggregate from cement and concrete agglomerates, which is performed by simultaneously crushing with a crushing medium (eg, gravel) by a mill or the like, and then removing fine powder of 0.15 mm or less mainly by an air classifier. According to claim 1, When crushing the cement concrete lump, the cement concrete lump or crushed substance is heated to 100 to 600 ° C. by a heating device to deteriorate the cement in the cement concrete mass to remove the cement mortar portion adhering to the aggregate surface. The air is brought into contact with the cement concrete mass heated by the heating device, and the air is heated at the same time as the cement concrete mass is cooled, and the heated air is brought into contact with the cement concrete mass prior to feeding the heating apparatus. A method for producing recycled aggregates from cement or concrete agglomerates, wherein the cement and agglomerates are preheated. According to claim 1, A method for producing recycled aggregates from cement or concrete agglomerates, wherein the crushing of the aggregate itself is performed by selecting either dry or wet. Recycled aggregate produced by the method of claim 1.