Quality improvement method for waste concrete recycle coarse aggregate by composite stimulus material

Abstract

To provide a quality improvement method for a waste concrete recycle coarse aggregate by a composite stimulus material.SOLUTION: In step 1, an alkaline solution is prepared; in step 2, a composite precursor powder is prepared; in step 3, a recycled coarse aggregate is manufactured; in step 4, a high-pressure airless spray device is turned on, and the alkaline solution prepared in step 1 is sprayed to the recycled coarse aggregate obtained in step 3; in step 5, a powder ejection device is turned on, and the composite precursor powder prepared in step 2 is uniformly sprayed to the surface of the recycled coarse aggregate whose surface has been uniformly sprayed with the alkaline solution; in step 6, the alkaline solution prepared in step 1 is uniformly sprayed to the surface of the recycled coarse aggregate whose surface has been uniformly sprayed with the composite precursor powder; and in step 7, the strengthened recycled coarse aggregate is left in a shaded place for curing.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] This application relates to the technical field of recycled coarse aggregates for waste concrete, and particularly to a method for improving the quality of recycled coarse aggregates for waste concrete by using composite stimulating materials.

Background Art

[0002] In current construction projects, natural coarse aggregates mixed with concrete are widely used as non-renewable resources. At the same time, a large number of aging buildings are demolished, generating a large amount of waste concrete, which accumulates and takes up space, causing environmental problems. Waste concrete can be processed into recycled coarse aggregates to replace natural coarse aggregates.

[0003] Compared with natural coarse aggregates, recycled coarse aggregates have more corners, the surface is unevenly wrapped with mortar, and there are micro-cracks distributed unevenly. Therefore, recycled coarse aggregates have a high water absorption rate, a high porosity, and a high crushing value. Concrete mixed directly with recycled coarse aggregates has poor workability and low strength, which limits the application of recycled coarse aggregates for waste concrete (hereinafter abbreviated as recycled coarse aggregates). Therefore, it is necessary to improve the quality of recycled coarse aggregates in order to expand the application range of recycled coarse aggregate concrete, reduce the consumption of natural aggregates, and improve the utilization rate of waste concrete.

[0004] Conventionally, methods for improving the quality of recycled coarse aggregates include physical strengthening, chemical strengthening, and microbial strengthening. Among them, physical strengthening has high energy consumption, great damage to recycled aggregates, and a decrease in resource utilization rate. Chemical strengthening has a large material loss and high cost. Microbial strengthening is slow and inefficient.

Summary of the Invention

Problems to be Solved by the Invention

[0005] The objective of this application is to provide a method for improving the quality of recycled coarse aggregate of waste concrete using a composite stimulating material to solve the technical problems such as high cost and low efficiency in the conventional waste concrete recycling coarse aggregate strengthening technology.

Means for Solving the Problem

[0006] To achieve the above objective, this application adopts the following technical solutions.

[0007] The method for improving the quality of recycled coarse aggregate of waste concrete using a composite stimulating material includes the following steps.

[0008] In Step 1, prepare an alkaline solution, and by weight parts, weigh 20 - 30 parts of NaOH or KOH solid particles, 10 - 15 parts of instant soluble sodium silicate fine powder, and 100 parts of water, mix the weighed water, NaOH or KOH solid particles, and instant soluble sodium silicate fine powder, and stir until the solid particles are completely dissolved.

[0009] In Step 2, prepare a composite precursor powder, and by weight parts, proportionally place 100 parts of solid waste - based activating material and 15 - 20 parts of sulfate in a powder mixer and stir evenly.

[0010] In Step 3, crush, sieve, wash, and dry waste concrete so that aggregates with a particle size of 5 - 20 mm account for 95% or more to obtain recycled coarse aggregate.

[0011] In Step 4, turn on a high - pressure airless spraying device including a first vibrating sieve and a high - pressure airless spraying machine used in combination, put the recycled coarse aggregate obtained in Step 3 into the inlet of the high - pressure airless spraying device, evenly spray the alkaline solution prepared in Step 1 on the surface of the recycled coarse aggregate, and discharge the recycled coarse aggregate with the alkaline solution evenly sprayed on its surface from the outlet of the high - pressure airless spraying device.

[0012] In step 5, turn on the powder ejection device including the second vibrating sieve machine and the electrostatic powder spraying machine used in combination, feed the recycled coarse aggregate with an alkaline solution uniformly sprayed on the surface obtained in step 4 into the inlet of the powder ejection device, uniformly spray the composite precursor powder prepared in step 2 on the surface of the recycled coarse aggregate with an alkaline solution uniformly sprayed on the surface, and discharge the recycled coarse aggregate with the composite precursor powder uniformly sprayed on the surface from the outlet of the powder ejection device.

[0013] In step 6, let the recycled coarse aggregate with the composite precursor powder uniformly sprayed on the surface obtained in step 5 stand for 30 to 60 minutes. After the composite precursor powder on the surface of the recycled coarse aggregate has basically solidified, feed it into the inlet of the high-pressure airless spraying device, turn on the first vibrating sieve machine and the high-pressure airless spraying machine, uniformly spray the alkaline solution prepared in step 1 on the surface of the recycled coarse aggregate with the composite precursor powder uniformly sprayed on the surface, discharge the strengthened recycled coarse aggregate from the outlet of the high-pressure airless spraying device, and control the thickness of the strengthening layer of the strengthened recycled coarse aggregate to be 0.8 mm to 1.5 mm.

[0014] In step 7, let the strengthened recycled coarse aggregate obtained in step 6 stand in the shade for 24 hours and then cure it in a standard curing room for 7 days.

[0015] Furthermore, the first vibrating sieve machine is a linear vibrating sieve. The sieve aperture size is 4 mesh and it is a square hole. The width of the sieve is 1 to 1.2 m. The aspect ratio of the sieve surface is 2:1 to 3:1. The inclination angle α of the sieve surface is 3 to 5°. The vibration direction angle δ is 45°. The amplitude A is 4 to 6 mm. The frequency ω is 800 to 900 r / min. The high-pressure airless spraying machine is used in combination with the first vibrating sieve machine. Two rows of high-pressure airless spraying nozzles are arranged vertically above and below the sieve surface, perpendicular to the sieve surface and 0.5 m away from the sieve surface. The spraying pressure is greater than 5 Mpa, and the flow rate of a single nozzle is greater than 3 L / min.

[0016] Furthermore, the second vibrating sieve is a linear vibrating sieve, the sieve aperture is 4 mesh in size, square holes, the width of the sieve is 1 - 1.2 m, the aspect ratio of the sieve surface is 2:1 - 3:1, and the inclination angle α of the sieve surface is 3 - 5°. The vibration direction angle δ is 45°, the amplitude A is 4 - 6 mm, the frequency ω is 800 - 900 r / min. The electrostatic powder sprayer is used in combination with the second vibrating sieve. Two rows of powder ejection nozzles are arranged vertically above and below the sieve surface, perpendicular to the sieve surface, and 0.5 m away from the sieve surface. The ejection pressure is greater than 0.5 Mpa, and the powder discharge amount of a single nozzle is greater than 500 g / min.

[0017] Furthermore, the solid waste-based activated material is one or a combination of one or more of granulated blast furnace slag, fly ash, refuse incineration bottom slag fine powder, and calcined botta fine powder.

[0018] Furthermore, the sulfate is phosphogypsum or desulfurized gypsum.

[0019] Furthermore, the granulated blast furnace slag is S105 grade granulated blast furnace slag powder, the fly ash is grade 2 fly ash, the refuse incineration bottom slag fine powder is the residue obtained by recovering metals from the bottom slag generated in a refuse incineration facility, aging, drying, and pulverizing in an open-air environment, and passing through a 200-mesh sieve. The calcined botta fine powder is the residue obtained by calcining botta at 800 - 1000 °C, pulverizing, and passing through a 200-mesh sieve.

[0020] Furthermore, the phosphogypsum or desulfurized gypsum is meta-phosphogypsum or desulfurized gypsum, and is 200 mesh or less.

[0021] Compared with the prior art, the present application has the following features and beneficial effects.

[0022] This application discloses a method for improving the quality of recycled coarse aggregate of waste concrete using a composite stimulating material. Using industrial solid waste as the basic raw material, modifying existing equipment, and forming a strengthening layer with a certain thickness on the recycled coarse aggregate in the form of spraying, powder spraying, and then spraying again, the quality of the recycled coarse aggregate of waste concrete can be effectively improved, with characteristics such as high safety and applicability, high popularization and practical value. When widely popularized and applied, good economic effects can be achieved.

Brief Description of the Drawings

[0023]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0024] In the following, in order to make the technical means, creative features, achieved objectives and effects realized by this application clearer, this application will be further described below.

[0025] The embodiments described in this specification are specific specific embodiments of this application used to explain the concept of this application, and are all illustrative and exemplary, and should not be construed as limitations on the embodiments of this application and the scope of this application. In addition to the embodiments described in this specification, those skilled in the art may further adopt other obvious technical solutions based on the scope of the patent claims of this application and the content disclosed in the specification. These technical solutions include technical solutions that adopt any obvious substitutions and modifications made to the embodiments described in this specification.

[0026] This application discloses a method for improving the quality of recycled coarse aggregate of waste concrete using a composite stimulating material, including the following steps.

[0027] In step 1, prepare an alkaline solution with a composition of 20 to 30 parts of NaOH or KOH solid particles, 10 to 15 parts of instant sodium silicate fine powder, and 100 parts of water by mass. Weigh the water, NaOH or KOH solid particles, and instant sodium silicate fine powder, mix them, and stir until the solid particles are completely dissolved.

[0028] In step 2, prepare a composite precursor powder with a composition of 100 parts of a solid waste-based activation material, which is one or a combination of one or more of granular blast furnace slag, fly ash, waste incineration bottom slag fine powder, and calcined botta fine powder, and 15 to 20 parts of sulfate by mass. Proportionally place them in a powder mixer and stir evenly.

[0029] The sulfate is phosphogypsum or desulfurized gypsum. The granular blast furnace slag is commercially available S105 grade granular blast furnace slag powder, the fly ash is commercially available grade 2 fly ash, the waste incineration bottom slag fine powder is the residue obtained by recovering metals from the bottom slag generated in a waste incineration facility, aging, drying, and pulverizing it in an open-air environment and passing it through a 200-mesh sieve. The calcined botta fine powder is the residue obtained by calcining botta at 800 to 1000 °C, pulverizing it, and passing it through a 200-mesh sieve. The phosphogypsum or desulfurized gypsum is commercially available meta-phosphogypsum or desulfurized gypsum and is 200 mesh or less.

[0030] In step 3, crush, sieve, wash, and dry waste concrete so that aggregates with a particle size of 5 to 20 mm account for 95% or more to obtain recycled coarse aggregates.

[0031] In step 4, turn on a high-pressure airless spraying device including a first vibrating sieve and a high-pressure airless spraying machine used in combination, put the recycled coarse aggregates obtained in step 3 into the inlet of the high-pressure airless spraying device, uniformly spray the alkaline solution prepared in step 1 on the surface of the recycled coarse aggregates, and discharge the recycled coarse aggregates with the alkaline solution uniformly sprayed on the surface from the discharge port of the high-pressure airless spraying device.

[0032] The first vibrating sieve is a linear vibrating sieve. The sieve holes are square holes with a size of 4 mesh. The width of the sieve is 1 - 1.2 m. The aspect ratio of the sieve surface is 2:1 - 3:1. The inclination angle α of the sieve surface is 3 - 5°. The vibration direction angle δ is 45°. The amplitude A is 4 - 6 mm. The frequency ω is 800 - 900 r / min. The high-pressure airless sprayer is used in combination with the first vibrating sieve. Two rows of high-pressure airless spray nozzles are arranged vertically above and below the sieve surface, perpendicular to the sieve surface, and 0.5 m away from the sieve surface. The ejection pressure is greater than 5 Mpa, and the flow rate of a single nozzle is greater than 3 L / min.

[0033] In step 5, turn on the powder ejection device including the second vibrating sieve and the electrostatic powder sprayer used in combination. Feed the recycled coarse aggregate with an alkaline solution uniformly sprayed on its surface obtained in step 4 into the inlet of the powder ejection device. Uniformly spray the composite precursor powder prepared in step 2 on the surface of the recycled coarse aggregate with an alkaline solution uniformly sprayed on its surface. Then discharge the recycled coarse aggregate with the composite precursor powder uniformly sprayed on its surface from the outlet of the powder ejection device.

[0034] The second vibrating sieve is a linear vibrating sieve. The sieve holes are square holes with a size of 4 mesh. The width of the sieve is 1 - 1.2 m. The aspect ratio of the sieve surface is 2:1 - 3:1. The inclination angle α of the sieve surface is 3 - 5°. The vibration direction angle δ is 45°. The amplitude A is 4 - 6 mm. The frequency ω is 800 - 900 r / min. The electrostatic powder sprayer is used in combination with the second vibrating sieve. Two rows of powder ejection nozzles are arranged vertically above and below the sieve surface, perpendicular to the sieve surface, and 0.5 m away from the sieve surface. The ejection pressure is greater than 0.5 Mpa, and the powder discharge amount of a single nozzle is greater than 500 g / min.

[0035] In step 6, the recycled coarse aggregate with the composite precursor powder uniformly sprayed on the surface obtained in step 5 is left standing for 30 to 60 minutes. After the composite precursor powder on the surface of the recycled coarse aggregate has basically solidified, it is fed into the inlet of a high-pressure airless spraying device. Turn on the first vibrating sieve machine and the high-pressure airless spraying machine, and uniformly spray the alkaline solution prepared in step 1 on the surface of the recycled coarse aggregate with the composite precursor powder uniformly sprayed on its surface. Discharge the strengthened recycled coarse aggregate from the outlet of the high-pressure airless spraying device, and control the thickness of the strengthening layer of the strengthened recycled coarse aggregate to be 0.8 mm to 1.5 mm.

[0036] In step 7, the strengthened recycled coarse aggregate obtained in step 6 is left standing in the shade for 24 hours and then placed in a standard curing room for curing for 7 days.

[0037] Example 1. This example provides a method for improving the quality of waste concrete recycled coarse aggregate with a composite stimulating material. The raw materials include a solid waste-based activating material, a sulfate, and an alkaline solution. The mass mixing ratio of each component in the raw materials is shown by the raw materials of each component in the row of Example 1 in Table 1 and their corresponding parts by mass. The manufacturing method uses steps 1 to 7 to control the thickness of the strengthening layer by controlling the linear vibration sieve frequency ω, the ejection pressure of the high-pressure airless spraying machine, the flow rate of a single nozzle, the ejection pressure of the electrostatic powder spraying machine, and the powder discharge amount of a single nozzle, and sets the thickness of the strengthening layer to 1 mm.

[0038] Example 2. This example provides another method for improving the quality of waste concrete recycled coarse aggregate with a composite stimulating material. The raw materials include a solid waste-based activating material, a sulfate, and an alkaline solution. The mass mixing ratio of each component in the raw materials is shown by the raw materials of each component in the row of Example 2 in Table 1 and their corresponding parts by mass. The manufacturing method uses steps 1 to 7 to control the thickness of the strengthening layer by controlling the linear vibration sieve frequency ω, the ejection pressure of the high-pressure airless spraying machine, the flow rate of a single nozzle, the ejection pressure of the electrostatic powder spraying machine, and the powder discharge amount of a single nozzle, and sets the thickness of the strengthening layer to 1 mm.

[0039] Example 3. This example provides a method for improving the quality of recycled coarse aggregate of waste concrete using another composite stimulating material. The raw materials include a solid waste-based activating material, a sulfate, and an alkaline solution. The mass mixing ratio of each component in the raw materials is shown by the raw materials of each component in the row of Example 3 in Table 1 and their corresponding parts by mass. The manufacturing method uses Steps 1 to 7 to control the linear vibration sieve frequency ω, the ejection pressure of the high-pressure airless spray machine, the flow rate of a single nozzle, the ejection pressure of the electrostatic powder spray machine, and the powder discharge amount of a single nozzle, thereby controlling the thickness of the strengthening layer, and setting the thickness of the strengthening layer to 1 mm.

[0040] Example 4. This example provides a method for improving the quality of recycled coarse aggregate of waste concrete using another composite stimulating material. The raw materials include a solid waste-based activating material, a sulfate, and an alkaline solution. The mass mixing ratio of each component in the raw materials is shown by the raw materials of each component in the row of Example 4 in Table 1 and their corresponding parts by mass. The manufacturing method uses Steps 1 to 7 to control the linear vibration sieve frequency ω, the ejection pressure of the high-pressure airless spray machine, the flow rate of a single nozzle, the ejection pressure of the electrostatic powder spray machine, and the powder discharge amount of a single nozzle, thereby controlling the thickness of the strengthening layer, and setting the thickness of the strengthening layer to 1.5 mm.

[0041] Example 5. This example provides a method for improving the quality of recycled coarse aggregate of waste concrete using another composite stimulating material. The raw materials include a solid waste-based activating material, a sulfate, and an alkaline solution. The mass mixing ratio of each component in the raw materials is shown by the raw materials of each component in the row of Example 5 in Table 1 and their corresponding parts by mass. The manufacturing method uses Steps 1 to 7 to control the linear vibration sieve frequency ω, the ejection pressure of the high-pressure airless spray machine, the flow rate of a single nozzle, the ejection pressure of the electrostatic powder spray machine, and the powder discharge amount of a single nozzle, thereby controlling the thickness of the strengthening layer, and setting the thickness of the strengthening layer to 1.5 mm.

[0042] Example 6. This example provides a method for improving the quality of recycled coarse aggregates of waste concrete using another composite stimulus material. The raw materials include a solid waste-based activating material, a sulfate, and an alkaline solution. The mass ratio of each component in the raw materials is shown by the raw materials of each component in the row of Example 6 in Table 1 and their corresponding parts by mass. The manufacturing method uses steps 1 to 7 to control the thickness of the strengthening layer by controlling the linear vibration sieve frequency ω, the ejection pressure of the high-pressure airless sprayer, the flow rate of a single nozzle, the ejection pressure of the electrostatic powder sprayer, and the powder discharge amount of a single nozzle, and sets the thickness of the strengthening layer to 1.5 mm.

[0043] Comparative Example 1. As a comparative example of Example 1, the components and mass ratio in the raw materials are shown by the raw materials of each component in the row of Comparative Example 1 in Table 1 and their corresponding parts by mass. The manufacturing method uses steps 1 to 7 to control the thickness of the strengthening layer by controlling the linear vibration sieve frequency ω, the ejection pressure of the high-pressure airless sprayer, the flow rate of a single nozzle, the ejection pressure of the electrostatic powder sprayer, and the powder discharge amount of a single nozzle, and sets the thickness of the strengthening layer to 0.8 mm.

[0044] Comparative Example 2. As a comparative example of Example 5, the components and mass ratio in the raw materials are shown by the raw materials of each component in the row of Comparative Example 2 in Table 1 and their corresponding parts by mass. The manufacturing method uses steps 1 to 7 to control the thickness of the strengthening layer by controlling the linear vibration sieve frequency ω, the ejection pressure of the high-pressure airless sprayer, the flow rate of a single nozzle, the ejection pressure of the electrostatic powder sprayer, and the powder discharge amount of a single nozzle, and sets the thickness of the strengthening layer to 0.8 mm.

[0045] Comparative Example 3. As a comparative example of Example 6, the components and mass ratio in the raw materials are shown by the raw materials of each component in the row of Comparative Example 3 in Table 1 and their corresponding parts by mass. The manufacturing method uses steps 1 to 7 to control the thickness of the strengthening layer by controlling the linear vibration sieve frequency ω, the ejection pressure of the high-pressure airless sprayer, the flow rate of a single nozzle, the ejection pressure of the electrostatic powder sprayer, and the powder discharge amount of a single nozzle, and sets the thickness of the strengthening layer to 0.8 mm.

[0046] Comparative Example 4. This comparative example is recycled coarse aggregate of waste concrete without strengthening treatment, used as a comparative example for Examples 1 to 6.

[0047] Performance test: Performance tests were conducted on the performance of the strengthened recycled coarse aggregates produced in Examples 1 to 6, Comparative Examples 1 to 3, and the waste concrete recycled coarse aggregate of Comparative Example 4. The performance of the strengthened waste concrete recycled coarse aggregate provided by this application was tested in accordance with "Construction Jade and Crushed Stones" (GB / T 14685-2022) and "Recycled Coarse Aggregate for Concrete" (GB / T 25177-2010). After 28 days of curing, the specific test results are shown in Table 2.

[0048] As can be seen from Table 2, the method for improving the quality of waste concrete recycled coarse aggregate with the composite stimulating material provided by this application can effectively improve the quality of waste concrete recycled coarse aggregate and has the following characteristics. The crushing value decreased by 27.1% - 37.3%, reaching or approaching the standard of Class I recycled coarse aggregate. The water absorption rate decreased by 38.4% - 44.4%, reaching the standard of Class II recycled coarse aggregate. The apparent density increased by 12.1 - 16.7%, reaching or approaching the standard of Class II recycled coarse aggregate. The bulk density increased by 10.3% - 14.1%, showing a significant increase. Table 1 Raw materials and corresponding parts by mass of each component of the strengthening material JPEG2025105515000002.jpg73102 Table 2 Performance test results regarding aggregate performance JPEG2025105515000003.jpg45102

[0049] Compared with the prior art, the method for improving the quality of waste concrete recycled coarse aggregate with the composite stimulating material provided by this application has the following advantages.

[0050] The material provided by the present application for improving the quality of coarse aggregate recycled from waste concrete does not use cement in its production, but stimulates the mineral activity of industrial solid waste such as granulated blast furnace slag, fly ash, waste incineration bottom slag, slag, phosphogypsum, or desulfurized gypsum, thereby improving the quality of coarse aggregate recycled from waste concrete, "strengthening waste with waste", reducing costs, saving energy and protecting the environment, and providing a new direction for the application of industrial solid waste as a resource.

[0051] The method for improving the quality of recycled coarse aggregate from waste concrete using composite stimulating materials provided by the present application involves modifying existing equipment and forming a reinforcing layer on the surface of recycled coarse aggregate in the form of spraying, powder spraying or spraying instead of the traditional immersion method, thereby saving materials, eliminating the need for wastewater treatment, simplifying the process, and reducing the cost of reinforcing the recycled coarse aggregate.

[0052] In view of the above, the method for improving the quality of recycled coarse aggregate from waste concrete by using composite stimulating materials provided by the present application can effectively improve the quality of recycled coarse aggregate from waste concrete, "strengthen waste with waste", fully utilize industrial solid waste, open up new fields for the resource utilization of industrial solid waste, improve the utilization rate and utilization quality of industrial solid waste, save water and materials, simplify the process, and reduce the strengthening processing cost of recycled coarse aggregate.

[0053] The above is only a preferred embodiment of the present application, and is not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the scope of the spirit and principles of the present application should be included in the protection scope of the present application. [Explanation of symbols]

[0054] 1 sieve box 2. Sieve 3. Vibration damping spring 4 Inlet 5 Outlet 6. High-pressure airless spray nozzle 7. Vibrating Electrical Equipment 8 Nozzle of an electrostatic powder spraying machine

Claims

1. A method for improving the quality of recycled coarse aggregates of waste concrete using a composite stimulating material, Step 1 of preparing an alkaline solution, which is composed of 20 to 30 parts of NaOH or KOH solid particles, 10 to 15 parts of instant soluble sodium silicate fine powder, and 100 parts of water by mass. Weigh the water, NaOH or KOH solid particles, and instant soluble sodium silicate fine powder, mix them, and stir until the solid particles are completely dissolved. Step 1; Step 2 of preparing a composite precursor powder, which is composed of 100 parts of a solid waste-based activating material that is one or a combination of one or more of granular blast furnace slag, fly ash, waste incineration bottom slag fine powder, and calcined botta fine powder, and 15 to 20 parts of sulfate by mass. Proportionally place them in a powder mixer and stir evenly. Step 2; Step 3 of manufacturing recycled coarse aggregates, which is to crush, sieve, wash, and dry waste concrete so that aggregates with a particle size of 5 to 20 mm account for 95% or more to obtain recycled coarse aggregates. Step 3; Turn on a high-pressure airless spraying device including a first vibrating sieve and a high-pressure airless spraying machine used in combination. Put the recycled coarse aggregates obtained in Step 3 into the inlet of the high-pressure airless spraying device, evenly spray the alkaline solution prepared in Step 1 on the surface of the recycled coarse aggregates, and discharge the recycled coarse aggregates with the alkaline solution evenly sprayed on the surface from the outlet of the high-pressure airless spraying device. Step 4; Turn on a powder spraying device including a second vibrating sieve and an electrostatic powder spraying machine used in combination. Put the recycled coarse aggregates with the alkaline solution evenly sprayed on the surface obtained in Step 4 into the inlet of the powder spraying device, evenly spray the composite precursor powder prepared in Step 2 on the surface of the recycled coarse aggregates with the alkaline solution evenly sprayed on the surface, and discharge the recycled coarse aggregates with the composite precursor powder evenly sprayed on the surface from the outlet of the powder spraying device. Step 5; The recycled coarse aggregate with the composite precursor powder uniformly sprayed on the surface obtained in Step 5 is allowed to stand for 30 to 60 minutes. After the composite precursor powder on the surface of the recycled coarse aggregate has basically solidified, it is fed into the inlet of the high-pressure airless spraying device. Turn on the first vibrating sieve machine and the high-pressure airless spraying machine, and uniformly spray the alkaline solution prepared in Step 1 on the surface of the recycled coarse aggregate with the composite precursor powder uniformly sprayed on the surface, and discharge the reinforced recycled coarse aggregate from the outlet of the high-pressure airless spraying device, and control the thickness of the reinforcement layer of the reinforced recycled coarse aggregate to be 0.8 mm to 1.5 mm, Step 6; Step 7 of allowing the reinforced recycled coarse aggregate obtained in Step 6 to stand in the shade for 24 hours and then placing it in a standard curing room for curing for 7 days; A method for improving the quality of waste concrete recycled coarse aggregate by a composite stimulating material, characterized by including the above.

2. The first vibrating sieve machine is a linear vibrating sieve, the sieve aperture is 4 mesh in size, with square holes, the width of the sieve is 1 to 1.2 m, the aspect ratio of the sieve surface is 2:1 to 3:1, the inclination angle α of the sieve surface is 3 to 5°, the vibration direction angle δ is 45°, the amplitude A is 4 to 6 mm, the frequency ω is 800 to 900 r / min. The high-pressure airless spraying machine is used in combination with the first vibrating sieve machine. Two rows of high-pressure airless spraying nozzles are arranged vertically above and below the sieve surface, perpendicular to the sieve surface, and 0.5 m away from the sieve surface. The ejection pressure is greater than 5 MPa, and the flow rate of a single nozzle is greater than 3 L / min. The method for improving the quality of waste concrete recycled coarse aggregate by a composite stimulating material according to Claim 1, characterized by the above.

3. The second vibrating sieve is a linear vibrating sieve. The sieve holes are square holes with a size of 4 mesh. The width of the sieve is 1 - 1.2 m. The aspect ratio of the sieve surface is 2:1 - 3:

1. The inclination angle α of the sieve surface is 3 - 5°. The vibration direction angle δ is 45°. The amplitude A is 4 - 6 mm. The frequency ω is 800 - 900 r / min. The electrostatic powder sprayer is used in combination with the second vibrating sieve. Powder ejection nozzles are arranged in two rows each, perpendicular to the sieve surface, 0.5 m away from the sieve surface, above and below the sieve surface. The ejection pressure is greater than 0.5 MPa, and the powder discharge amount of a single nozzle is greater than 500 g / min. A method for improving the quality of recycled coarse aggregate of waste concrete by using a composite stimulating material according to claim 2, characterized in that.

4. The sulfate is phosphogypsum or desulfurized gypsum. A method for improving the quality of recycled coarse aggregate of waste concrete by using a composite stimulating material according to claim 1, characterized in that.

5. The granulated blast furnace slag is S105 grade granulated blast furnace slag powder. The fly ash is grade 2 fly ash. The refuse incineration bottom slag fine powder is the residue obtained by recovering metals from the bottom slag generated in a refuse incineration facility, aging, drying, and pulverizing in an open-air environment, and passing through a 200-mesh sieve. The calcined botta fine powder is the residue obtained by calcining botta at 800 - 1000 °C, pulverizing, and passing through a 200-mesh sieve. A method for improving the quality of recycled coarse aggregate of waste concrete by using a composite stimulating material according to claim 1, characterized in that.

6. The phosphogypsum is meta-phosphogypsum. A method for improving the quality of recycled coarse aggregate of waste concrete by using a composite stimulating material according to claim 4, characterized in that.

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