Construction waste regenerated mixed aggregate grading determination method

Abstract

The invention relates to the technical field of road engineering, and discloses a construction waste regenerated mixed aggregate grading determination method which comprises the following steps: step 1, construction waste pretreatment and crushing parameter acquisition; the method comprises the following steps: S1, carrying out multi-stage crushing on the construction waste through combined operation of a jaw crusher and an impact crusher, collecting a crushed particle size distribution curve of recycled aggregate, and measuring the proportion of needle-sheet-shaped particles and surface roughness parameters; and S2, metal and light impurities are separated through magnetic separation and winnowing equipment, and it is ensured that the metal residual rate is smaller than 1%, and the wood / plastic residual rate is smaller than 3%. According to the construction waste recycled mixed aggregate grading determination method, a recycled aggregate dynamic grading model is established on the basis of the crushing fractal rule and the maximum compactness theory, grading design precision is remarkably improved, it is ensured that the performance of a mixture is equivalent to that of natural aggregate, and a construction waste resource utilization path is optimized through a grading replacement strategy.

Description

Technical Field

[0001] The present invention relates to the technical field of road engineering, and particularly to a method for determining the gradation of recycled mixed aggregate of construction waste. Background Art

[0002] Construction waste is the general term for engineering muck, engineering slurry, engineering waste, demolition waste, decoration waste, etc., including the soil, materials and other waste generated during the construction, expansion, renovation and demolition of various buildings, structures, pipe networks, etc. and the decoration of houses by residents, excluding construction waste identified as hazardous waste through inspection.

[0003] With the rapid development of China's economy, the urbanization process and infrastructure construction in China are also advancing at a quite fast speed. As a major infrastructure country, on the one hand, remarkable achievements have been made in infrastructure construction and urbanization speed, and on the other hand, there are also adverse effects accompanying the rapid development of infrastructure construction. Since there is still a lack of authoritative guiding documents for the treatment of construction waste in China and the relevant policies, laws and regulations are not perfect, construction waste cannot be effectively treated.

[0004] At present, the traditional screening method does not consider the influence of material water absorption rate and density difference on the gradation, resulting in a large error in the actual ratio. At the same time, the ratio of bricks to concrete in the mixed aggregate is not optimized, which is likely to cause shrinkage cracking or insufficient strength, and there is a lack of differential treatment processes for recycled aggregates of different particle sizes, resulting in low resource utilization rate. Summary of the Invention

[0005] In view of the above problems of the existing traditional screening method that does not consider the influence of material water absorption rate and density difference on the gradation, resulting in a large error in the actual ratio, at the same time, the ratio of bricks to concrete in the mixed aggregate is not optimized, which is likely to cause shrinkage cracking or insufficient strength, and there is a lack of differential treatment processes for recycled aggregates of different particle sizes, resulting in low resource utilization rate, the present invention is proposed.

[0006] Therefore, the object of the present invention is to provide a method for determining the gradation of recycled mixed aggregate of construction waste, and its purpose is to achieve refined classification of components such as concrete and bricks and tiles in construction waste through sorting, crushing and screening processes, and preferentially replace specific particle size ranges of natural aggregates (such as full replacement of fine aggregates and partial replacement of coarse aggregates), significantly improving the comprehensive utilization rate of construction waste.

[0007] To solve the above technical problems, the present invention provides the following technical solution: A method for determining the gradation of recycled mixed aggregate of construction waste, comprising:

[0008] Step 1, Pretreatment of construction waste and collection of crushing parameters

[0009] S1. Conduct multi-stage crushing of construction waste through the combined operation of a jaw crusher and a counterattack crusher, collect the crushing particle size distribution curve of the recycled aggregate, and measure the proportion of flaky particles and the surface roughness parameters.

[0010] S2. Use magnetic separation and air separation equipment to separate metals and light impurities, ensuring that the metal residue rate < 1% and the wood / plastic residue rate < 3%.

[0011] S3. Conduct pre-wetting treatment on the recycled aggregate, controlling the moisture content within the range of 5% - 8%.

[0012] Step Two. Construction and optimization of the dynamic grading model

[0013] S1. Based on the crushing fractal law and the maximum dense packing theory, establish a grading curve function in a double logarithmic coordinate system, and the function is in the form of a linear and non-linear superposition.

[0014] S2. Calculate the fractal dimension based on the difference between the vibration density and the loose density, and optimize the crushing process parameters based on the fractal dimension.

[0015] S3. Conduct surfactant coating treatment on the recycled aggregate to reduce the water absorption rate to ≤ 5%.

[0016] Step Three. Dynamic correction of grading and construction adaptation

[0017] S1. Real-time monitor the grading deviation between the recycled aggregate and the natural aggregate through the Internet of Things terminal, and adjust the proportion of intermediate particles (5 - 10 mm) to 15 - 25%.

[0018] S2. Add a chemical stabilizer (lime) and an anti-shrinkage additive (modified polypropylene fiber) to control the pH value fluctuation range of the mixture ≤ ±1.

[0019] S3. Customize the grading rules according to the engineering scenario requirements, including the maximum particle size of the road base ≤ 100 mm and the maximum particle size of the asphalt mixture ≤ 26.5 mm.

[0020] As a preferred scheme of the method for determining the grading of the recycled mixed aggregate of construction waste described in the present invention, wherein: the calculation method of the fractal dimension in S1 of Step Two is:

[0021]

[0022] Where R α and R β are the vibration density and the loose density respectively, and d max and d min are the maximum and minimum particle sizes.

[0023] As a preferred embodiment of the method for determining the gradation of the recycled mixed aggregate of construction waste according to the present invention, wherein: the calculation formula for the gradation deviation degree of S1 in step three is as follows:

[0024]

[0025] Wherein, G γ,i and G δ,i are respectively the passing rates of recycled and natural aggregates through the sieve holes of the i-th grade.

[0026] As a preferred embodiment of the method for determining the gradation of the recycled mixed aggregate of construction waste according to the present invention, wherein: S3 in step three further includes adding a silane coupling agent (dosage 0.3 - 0.5%) to the road base mixture, with the mass loss rate after freeze-thaw cycles ≤ 5%, controlling the replacement rate of recycled coarse aggregate in the asphalt mixture ≤ 30%, and the crushing value ≤ 20%.

[0027] As a preferred embodiment of the method for determining the gradation of the recycled mixed aggregate of construction waste according to the present invention, wherein: in S2 of step one, the magnetic separation equipment adopts a gradient magnetic field design, with the magnetic field intensity range of 0.8 - 1.5T, and the metal residue rate is reduced to ≤ 0.5%;

[0028] The wind speed of the air separation equipment is controlled at 4 - 6m / s, the residual rate of wood / plastic is ≤ 2%, and the separation rate of light impurities with a particle size > 5mm is ≥ 95%.

[0029] As a preferred embodiment of the method for determining the gradation of the recycled mixed aggregate of construction waste according to the present invention, wherein: the specific manifestation of the non-linear superposition form in S2 of step one is as follows:

[0030] For the coarse particle section (d > 10mm), it is fitted with a power function, and the exponent range is 0.3 - 0.5;

[0031] For the fine particle section (d ≤ 5mm), it is fitted with a quadratic polynomial, and the correlation coefficient R 2 ≥ 0.98.

[0032] As a preferred embodiment of the method for determining the gradation of the recycled mixed aggregate of construction waste according to the present invention, wherein: in the gradation rules of S3 in step three, for the road base mixture, additional limitations are as follows:

[0033] The dosage of the silane coupling agent is 0.3 - 0.5%, and the stirring time with the recycled aggregate is ≥ 5 minutes;

[0034] The mass loss rate after the freeze-thaw cycle test (-20°C to 25°C, 25 cycles) is ≤ 3%.

[0035] As a preferred embodiment of the method for determining the gradation of the recycled mixed aggregate of construction waste according to the present invention, wherein: for the asphalt mixture scenario:

[0036] The replacement rate of the recycled coarse aggregate is ≤ 30%, and the difference in crushing value from the natural aggregate is ≤ 5%.

[0037] The grade of the asphalt adhesion test (boiling water method) is ≥ 4, and the polished value is ≥ 45.

[0038] As a preferred solution of the method for determining the gradation of the recycled mixed aggregate of construction waste in the present invention, wherein: in the S1 gradation deviation monitoring in step three, a control logic is added. When the deviation ΔG > 10%, the gap of the discharge port of the impact crusher is automatically adjusted, and the adjustment range is ±2 mm; the deviation correction period is ≤ 30 minutes, and a real-time gradation adjustment log is generated.

[0039] Advantages of the present invention:

[0040] 1. Based on the crushing fractal law and the maximum density theory, a dynamic gradation model of recycled aggregate is established, significantly improving the gradation design accuracy, ensuring the performance equivalence of the mixture and natural aggregate. Through the hierarchical replacement strategy, the resource utilization path of construction waste is optimized. At the same time, intelligent sorting equipment and surfactant modification technology are adopted to reduce impurity interference and enhance the interfacial bonding force of recycled aggregate. Chemical stabilizers and anti-shrinkage additives are introduced to inhibit the dry shrinkage deformation and freeze-thaw damage of the mixture.

[0041] 2. An Internet of Things monitoring module is integrated to collect crushing parameters (rotor speed, sieve plate aperture) and gradation deviation data in real time, realizing dynamic correction of gradation and automatic compensation for the missing amount of fine aggregate. A "crushing - screening - pre-wetting" integrated process chain is constructed to reduce energy consumption in intermediate links and improve the preparation efficiency.

[0042] 3. Gradation rules and additive ratios are customized for scenarios such as road bases and recycled concrete to meet the requirements of high strength and high durability. A performance database of recycled aggregate is established to support rapid gradation matching and optimization for different engineering scenarios. Description of the Drawings

[0043] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0044] Figure 1 It is a schematic diagram of the overall process of the method for determining the gradation of the recycled mixed aggregate of construction waste in the present invention. Detailed Embodiments

[0045] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0046] Referring to Figure 1 , an embodiment of the present invention provides a method for determining the gradation of recycled mixed aggregate of construction waste. This method for determining the gradation of recycled mixed aggregate of construction waste includes Step 1: Pretreatment of construction waste and collection of crushing parameters.

[0047] S1. Multistage crushing of construction waste is carried out through the combined operation of a jaw crusher and a counterattack crusher. The crushing particle size distribution curve of the recycled aggregate is collected, and the proportion of flaky particles and the surface roughness parameters are measured.

[0048] Multistage crushing process: The combination of a jaw crusher (coarse crushing) and a counterattack crusher (fine crushing), and the discharge particle size is monitored in real time by a laser particle size analyzer, with an error ≤ 2%.

[0049] Impurity separation: Adopt magnetic separation (gradient magnetic field 0.8 - 1.5 T), air separation (air speed 4 - 6 m / s), and flotation (solution density 1.2 - 1.5 g / cm 3 ) three-stage linkage operation;

[0050] Pre-wetting treatment: The spraying water volume is controlled within 5% - 8% of the mass of the recycled aggregate, and the moisture content deviation ≤ 0.5%.

[0051] S2. Magnetic separation and air separation equipment are used to separate metals and light impurities to ensure that the metal residue rate < 1% and the wood / plastic residue rate < 3%.

[0052] Air separation optimization: The air duct structure is optimized through CFD simulation, and the light impurity separation efficiency is increased to ≥ 97%.

[0053] S3. The recycled aggregate is pre-wetted, and the moisture content is controlled within the range of 5% - 8%.

[0054] Step 2: Construction and optimization of the dynamic gradation model

[0055] S1. Based on the crushing fractal law and the maximum dense packing theory, a gradation curve function in a double logarithmic coordinate system is established, and the function is in the form of a linear and non-linear superposition.

[0056] S2. The fractal dimension is calculated according to the difference between the vibrated density and the loose density, and the crushing process parameters are optimized based on the fractal dimension.

[0057] S3. Conduct surface-active agent coating treatment on the recycled aggregate to reduce the water absorption rate to ≤5%.

[0058] Step 3. Dynamic gradation correction and construction adaptation

[0059] S1. Real-time monitor the gradation deviation between the recycled aggregate and the natural aggregate through the Internet of Things terminal, and adjust the proportion of intermediate particles (5-10 mm) to 15-25%.

[0060] S2. Add a chemical stabilizer (lime) and a shrinkage-resistant additive (modified polypropylene fiber) to control the pH value fluctuation range of the mixture ≤±1.

[0061] S3. Customize the gradation rules according to the engineering scenario requirements, including the maximum particle size of the road base ≤100 mm and the maximum particle size of the asphalt mixture ≤26.5 mm.

[0062] The calculation method of the fractal dimension of S1 in Step 2 is as follows:

[0063]

[0064] Where R α and R β are the vibration-compacted and loose-packed densities respectively, and d max and d min are the maximum and minimum particle sizes.

[0065] The calculation formula for the gradation deviation of S1 in Step 3 is as follows:

[0066]

[0067] Where G γ,i and G δ,i are the passing rates of the recycled and natural aggregates through the sieve holes of the i-th stage respectively.

[0068] S3 in Step 3 also includes adding a silane coupling agent (dosage 0.3-0.5%) to the road base mixture, with the freeze-thaw mass loss rate ≤5%, controlling the replacement rate of recycled coarse aggregate in the asphalt mixture ≤30%, and the crushing value ≤20%.

[0069] In S2 of Step 1, the magnetic separation equipment adopts a gradient magnetic field design, with the magnetic field intensity range of 0.8-1.5 T, and the metal residue rate is reduced to ≤0.5%.

[0070] The wind speed of the air separation equipment is controlled at 4-6 m / s, the residual rate of wood / plastic ≤2%, and the separation rate of light impurities with a particle size >5 mm ≥95%.

[0071] The specific manifestation of the non-linear superposition form in S2 of Step 1 is as follows:

[0072] For the coarse particle section (d > 10 mm), a power function fitting is adopted, and the exponent range is 0.3 - 0.5;

[0073] For the fine particle section (d ≤ 5 mm), a quadratic polynomial fitting is adopted, and the correlation coefficient R 2 ≥ 0.98.

[0074] In the S3 grading rule of the third step, an additional limitation is set for the road base mixture:

[0075] The dosage of the silane coupling agent is 0.3 - 0.5%, and the stirring time with the recycled aggregate is ≥ 5 minutes;

[0076] After the freeze-thaw cycle test (-20°C to 25°C, 25 cycles), the mass loss rate ≤ 3%.

[0077] For the asphalt mixture scenario:

[0078] The replacement rate of the recycled coarse aggregate ≤ 30%, and the difference in crushing value from the natural aggregate ≤ 5%;

[0079] The grade of the asphalt adhesion test (boiling water method) ≥ 4, and the polished value ≥ 45.

[0080] In the S1 grading deviation monitoring of the third step, an additional control logic is added. When the deviation ΔG > 10%, the gap of the discharge port of the impact crusher is automatically adjusted, and the adjustment range is ±2 mm; the deviation correction period ≤ 30 minutes, and a real-time grading adjustment log is generated.

[0081] During the use process, based on the crushing fractal law and the maximum density theory, a dynamic grading model of recycled aggregate is established, significantly improving the grading design accuracy, ensuring the equivalent performance of the mixture and natural aggregate. Through the hierarchical replacement strategy, the resource utilization path of construction waste is optimized. At the same time, intelligent sorting equipment and surfactant modification technology are adopted to reduce impurity interference and enhance the interfacial bonding force of recycled aggregate. Chemical stabilizers and anti-shrinkage additives are introduced to inhibit the dry shrinkage deformation and freeze-thaw damage of the mixture;

[0082] An IoT monitoring module is integrated to collect the crushing parameters (rotor speed, screen aperture) and grading deviation data in real time, realize dynamic grading correction and automatic compensation for the missing amount of fine aggregate, construct an integrated process chain of "crushing - screening - pre-wetting", reduce the energy consumption of intermediate links, and improve the preparation efficiency;

[0083] Grading rules and additive ratios are customized for scenarios such as road base and recycled concrete to meet the requirements of high strength and high durability. A performance database of recycled aggregate is established to support the rapid grading matching and optimization of different engineering scenarios.

[0084] Each embodiment in this specification is described in a related manner. For the same or similar parts among the embodiments, reference can be made to each other. Each embodiment focuses on the differences from other embodiments. In particular, for the system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and reference can be made to the relevant part of the method embodiment for the related content.

[0085] The above are only the preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention are included in the protection scope of the present invention.

Claims

1. A method for determining the gradation of recycled mixed aggregates of construction waste, characterized in that, It includes the following steps: Step 1, Pretreatment of construction waste and collection of crushing parameters S1, Conduct multi-stage crushing of construction waste through the combined operation of a jaw crusher and a counterattack crusher, collect the crushing particle size distribution curve of recycled aggregates, and measure the proportion of flaky particles and surface roughness parameters; S2, Use magnetic separation and air separation equipment to separate metals and light impurities, ensuring that the metal residue rate < 1% and the wood / plastic residue rate < 3%; S3, Conduct pre-wetting treatment on recycled aggregates, controlling the moisture content within the range of 5% - 8%; Step 2, Construction of a dynamic grading model and optimization S1, Based on the crushing fractal law and the maximum dense packing theory, establish a grading curve function in a double logarithmic coordinate system, and the function is in the form of a linear and non-linear superposition; S2, Calculate the fractal dimension according to the difference between the vibrated density and the loose density, and optimize the crushing process parameters based on the fractal dimension; S3, Conduct surfactant coating treatment on recycled aggregates to reduce the water absorption rate to ≤ 5%; Step 3, Dynamic correction of grading and construction adaptation S1, Real-time monitor the grading deviation between recycled aggregates and natural aggregates through an Internet of Things terminal, and adjust the proportion of intermediate particles (5 - 10 mm) to 15 - 25%; S2, Add chemical stabilizers (lime) and anti-shrinkage additives (modified polypropylene fibers) to control the pH value fluctuation range of the mixture ≤ ±1; S3, Customize grading rules according to the requirements of the engineering scenario, including a maximum particle size of ≤ 100 mm for the road base course and a maximum particle size of ≤ 26.5 mm for the asphalt mixture.

2. The method for determining the gradation of recycled mixed aggregates of construction waste according to claim 1, wherein: The calculation method of the fractal dimension in S1 of Step 2 is as follows: where R α and R β are the tapped density and the loose density respectively, d max and d min are the maximum and minimum particle sizes.

3. The method for determining the gradation of recycled mixed aggregate of construction waste according to claim 2, characterized in that: The calculation formula of the grading deviation in S1 of Step 3 is as follows: Among them, G γ,i and G δ,i are respectively the passing rates of recycled and natural aggregates through the sieve holes of the i-th grade.

4. The method for determining the gradation of recycled mixed aggregates of construction waste according to claim 3, wherein: S3 in Step 3 also includes adding a silane coupling agent (dosage 0.3 - 0.5%) to the road base course mixture, with the freeze-thaw mass loss rate ≤ 5%, controlling the replacement rate of recycled coarse aggregates in the asphalt mixture ≤ 30%, and the crushing value ≤ 20%.

5. The method for determining the gradation of recycled mixed aggregate of construction waste according to claim 1, wherein: In S2 of Step 1, the magnetic separation equipment adopts a gradient magnetic field design, with the magnetic field intensity range of 0.8 - 1.5 T, and the metal residue rate is reduced to ≤ 0.5%; The air separation equipment has the air velocity controlled at 4 - 6 m / s, the wood / plastic residue rate ≤ 2%, and the separation rate of light impurities with a particle size > 5 mm ≥ 95%.

6. The method for determining the gradation of recycled mixed aggregate of construction waste according to claim 5, wherein: The specific manifestation of the non-linear superposition form in S2 of Step 1 is as follows: In the coarse particle section (d > 10 mm), a power function fitting is used, with the exponent range of 0.3 - 0.5; The fine particle segment (d ≤ 5 mm) is fitted with a quadratic polynomial, and the correlation coefficient R 2 ≥ 0.

98.

7. The method for determining the gradation of recycled mixed aggregates of construction waste according to claim 1, characterized in that: In the grading rules of S3 in Step 3, for the road base course mixture, additional limitations are as follows: The dosage of the silane coupling agent is 0.3 - 0.5%, and the stirring time with recycled aggregates ≥ 5 minutes; The mass loss rate ≤ 3% after the freeze-thaw cycle test (-20°C to 25°C, 25 cycles).

8. The method for determining the gradation of recycled mixed aggregates of construction waste according to claim 7, characterized in that: For the asphalt mixture scenario: The replacement rate of recycled coarse aggregates ≤ 30%, and the difference in crushing value from natural aggregates ≤ 5%; The grade of the asphalt adhesion test (boiling water method) ≥ 4, and the polished value ≥ 45.

9. The method for determining the gradation of recycled mixed aggregates of construction waste according to claim 8, wherein: In the S1 gradation deviation monitoring in Step 3, add control logic so that when the deviation ΔG > 10%, the discharge port clearance of the impact crusher is automatically adjusted with an adjustment range of ±2 mm; the deviation correction period ≤ 30 minutes, and a real-time gradation adjustment log is generated.

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