Preparation method of recycled concrete from household garbage incineration slag

Abstract

The invention discloses a preparation method of household garbage incineration slag recycled concrete, and belongs to the technical field of solid waste resource utilization. Aiming at the problems of difficult treatment and low resource utilization rate of the household garbage incineration slag, harmful substances are removed through pretreatment technologies such as water washing, magnetic separation and jigging separation, then the slag is crushed to 0.25-0.5 mm by using a vertical impact crusher, aggregate activation treatment is performed by combining a silica fume-fly ash composite reinforcing material and an activation solution containing triisopropanolamine, and the slag is recycled. The aggregate activity and the interface bonding strength are improved. The high-performance recycled concrete is prepared in a carbon dioxide curing environment by adopting intermittent stirring to optimize ingredients and introducing a calcium sulphoaluminate-based curing agent to accelerate a hydration reaction and through high-frequency vibration and vacuum dehydration synergistic forming. The method realizes efficient resource utilization of the slag, reduces environmental pollution, improves mechanical properties and durability of the recycled concrete, and is suitable for the field of green buildings.

Description

Technical Field

[0001] The invention belongs to the technical field of solid waste resource utilization, and specifically relates to a method for preparing recycled concrete from domestic waste incineration slag. Background Art

[0002] With the acceleration of global urbanization, the amount of domestic waste has increased dramatically, bringing severe challenges to environmental governance and resource utilization. Incineration treatment, as an efficient waste reduction and resource technology, has been widely used worldwide. However, the slag (Incineration Bottom Ash, IBA) produced during the incineration process contains heavy metals (such as lead, cadmium, zinc), chloride ions and other harmful substances. If not properly handled, it will pollute the soil and water, threatening the ecological environment and human health. At present, the treatment methods of domestic waste incineration slag mainly include landfill and resource utilization. Although the landfill method is simple to operate, it occupies a lot of land resources, and long-term stacking may cause leakage of harmful substances and cause secondary pollution; resource utilization is difficult to achieve large-scale application due to technical difficulties such as complex slag composition, high impurity content, and low activity. Therefore, how to efficiently and environmentally friendly treat and utilize domestic waste incineration slag has become an important issue that needs to be solved urgently.

[0003] Recycled concrete is a green building material made by replacing part or all of the natural aggregate with recycled materials such as waste concrete and industrial waste. Compared with traditional concrete, recycled concrete has significant advantages such as saving natural resources and reducing environmental pollution. It conforms to the concept of sustainable development and shows broad application prospects in the construction field. However, due to the unstable performance of recycled materials, the mechanical properties (such as compressive strength and flexural strength) and durability (such as impermeability and frost resistance) of recycled concrete are often lower than those of traditional concrete, which limits its application in high-performance building structures. Especially when using domestic waste incineration slag as recycled aggregate, the harmful substances and low physical and chemical activity remaining in the slag further weaken the performance of recycled concrete. Therefore, exploring methods to improve the performance of recycled concrete, especially the efficient utilization technology based on slag, has important research significance and practical value.

[0004] In recent years, the application of nanomaterial technology in the field of concrete has gradually become a research hotspot. Nanomaterials, with their high specific surface area and excellent physical and chemical properties, can significantly improve the microstructure of concrete and enhance its mechanical properties and durability. For example, nano-silica can improve the early strength and impermeability of concrete by promoting the hydration reaction of cement and filling micro-pores; nano-carbon tubes, due to their high strength and high toughness, can enhance the crack resistance of concrete. However, there are still certain limitations in the application of nanomaterials in concrete, such as poor dispersion of nano-particles and high preparation costs, which limit their large-scale promotion in practical engineering. Nevertheless, nanomaterial technology provides new possibilities for improving the performance of recycled concrete, especially in improving the interfacial properties of slag aggregates and enhancing the overall performance of concrete, and has potential application value.

[0005] Aiming at the problems of environmental pollution caused by improper treatment of domestic waste incineration slag and insufficient performance of recycled concrete in the prior art, the present invention proposes an efficient and environmentally friendly preparation method. Through innovative slag pretreatment technologies (such as three-stage water washing, magnetic separation, jigging separation), aggregate activation technologies (using silica fume-fly ash composite reinforcing materials and activation liquid containing triisopropanolamine), and optimized concrete mixing processes (intermittent mixing, collaborative forming of high-frequency vibration and vacuum dewatering, carbon dioxide curing, etc.), the efficient resource utilization of slag is realized, and at the same time, the mechanical properties and durability of recycled concrete are significantly improved. The present invention aims to solve the technical bottleneck of slag treatment, reduce the risk of environmental pollution, and provide a high-performance and low-cost green building material option for the construction industry, with important social, economic and environmental benefits. Summary of the Invention

[0006] 1. Problems to be Solved

[0007] In view of the problems existing in the above-mentioned prior art, the present invention focuses on solving the following aspects: Incomplete removal of harmful substances in slag: When the prior art processes the slag from domestic waste incinerators, the removal effect of harmful substances such as chloride ions and heavy metals is limited, resulting in poor durability of recycled concrete and potential environmental safety hazards. The present invention introduces innovative pretreatment technologies such as three-stage water washing, magnetic separation, and jigging separation to achieve efficient removal of harmful substances, ensuring the environmental protection of the slag and improving the long-term performance of recycled concrete. Insufficient mechanical properties of recycled concrete: Currently, recycled concrete generally has problems such as low strength and poor flexural performance, making it difficult to meet the requirements of high-performance buildings. The present invention uses silica fume-fly ash composite reinforcing materials and an activating solution containing triisopropanolamine to activate the aggregates, and combines intermittent stirring, high-frequency vibration, and vacuum dewatering co-forming technologies to significantly improve the compressive strength, flexural strength, and compactness of recycled concrete. Complex process flow and high energy consumption: The existing slag treatment and recycled concrete preparation processes often have a cumbersome process flow and high energy consumption, limiting the feasibility of their industrial applications. The present invention simplifies the production steps by optimizing the process flow and using circulating water and carbon dioxide curing technologies, significantly reducing energy consumption and costs, and improving production efficiency and economy. Limited application of nanomaterials in concrete: The application of nanomaterials in concrete is limited by problems such as poor dispersion and high costs, making it difficult to be widely promoted. The present invention combines nanotechnology to enhance the activity of slag aggregates and improve the interfacial bonding performance between aggregates and cement-based materials, breaking through the limitations of traditional nanomaterial applications and opening up new ways to improve the performance of recycled concrete.

[0008] By solving the above problems, the present invention realizes the efficient resource utilization of the slag from domestic waste incinerators, prepares high-performance and environmentally friendly recycled concrete, and provides an innovative and practical solution for the field of green building materials.

[0009] 2. Technical solutions

[0010] To solve the above problems, the present invention adopts the following technical solutions.

[0011] A preparation method of recycled concrete from municipal solid waste incineration slag, comprising the following steps: (1) After washing, magnetic separation, and jigging separation of the municipal solid waste incineration slag, it is crushed to a particle size of 0.25 - 0.5 mm by a vertical impact crusher (Henan Hongxing Mining Machinery Co., Ltd., model VSI7611), and then premixed with a silica fume - fly ash composite reinforcing material in a mass ratio of 1:(0.03 - 0.05) to obtain a premix. An activation liquid containing 0.1 - 0.3% triisopropanolamine (CAS No.: 122 - 20 - 3) by final mass percentage is sprayed, and steam curing is carried out at 50 - 60 °C for 2 - 3 h. The steam curing equipment is the NDG1200 type equipment produced by Goodear (Shanghai) New Energy Technology Co., Ltd. to obtain activated aggregate; (2) The activated aggregate, P·O42.5 cement, polycarboxylate water - reducing agent (Liquiment®5581F type water - reducing agent produced by BASF SE), and water are put into a twin - shaft mixer (CHS750 type mixer produced by Coliner Machinery Co., Ltd.) according to a mass ratio of (1050 - 1250):(350 - 400):(1.5 - 2):(100 - 150), and an intermittent stirring mode is adopted to obtain a reaction system; (3) Then, a calcium sulfoaluminate - based curing agent with a total mass percentage of 0.5 - 1.2% is added to the reaction system and continuously stirred; (4) Co - forming is carried out by means of high - frequency vibration (WZY - 1000 type horizontal vibrating centrifuge for dehydration produced by Shanghai Datun Energy Co., Ltd.) and vacuum dehydration (SVF - 900EF type vacuum pump produced by ShreeVinayak Industries Ltd.), and cured for 72 h.

[0012] In this patent, the components (mass percentage) of the municipal solid waste incineration slag are as follows: Molten slag: accounting for the highest proportion (30.17%), formed by inorganic melts, presenting a porous and rough structure; Metals: accounting for 11.75%, including iron products (iron wires, iron nails) and non - ferrous metals such as aluminum and copper; Glass / Ceramics: totaling 36.65%, mainly from household containers and building materials; Unburned substances: about 2.7%, containing residual organic matter.

[0013] Preferably, the operation of water washing in step (1) is as follows: Put the domestic waste incineration slag into a three-stage series drum stone washer (HX-3TS type three-stage drum equipment produced by Henan Hongxing Mining Machinery Co., Ltd.). In the first stage, use a high-pressure water gun with a water pressure of 0.8-1.2 MPa to wash off the surface attachments of the domestic waste incineration slag and recover water to obtain recycled water. In the second stage, add sodium tripolyphosphate with a final mass percentage of 0.5-1% to the recycled water and soak the domestic waste incineration slag at room temperature for 24 hours. In the third stage, rinse the domestic waste incineration slag with hot water at 60-80 °C, and control the chloride mass percentage content of the domestic waste incineration slag after water washing to ≤0.06%. The operation of magnetic separation in step (1) is as follows: Pass the domestic waste incineration slag after water washing through a permanent magnet drum magnetic separator with a magnetic field intensity of 0.3-0.5 T (CTBJ1230 type permanent magnet drum magnetic separator produced by Zhonggang Tianyuan Co., Ltd.) to remove ferrous metals, and then extract non-ferromagnetic metals through an electromagnetic eddy current separator (EddyFlow E5 type separator produced by ERGAGlobal), where the frequency is 50-60 Hz and the current intensity is 100-150 A. The operation of jigging in step (1) is as follows: Put the domestic waste incineration slag after magnetic separation into a jig (JT4-2 type jig produced by Jiangxi Jiesikai Mining Machinery Co., Ltd.), set the jigging pulsation curve as a sawtooth wave, with an amplitude of 15-20 mm and a frequency of 2.5-3.5 Hz, and use the velocity difference ratio of the rising water flow to the falling water flow of 2:1-3:1 to sediment and separate the heavy metal particles of the domestic waste incineration slag. Optimization basis of sawtooth wave parameters: Amplitude setting (15-20 mm), mechanism of action: Provide enough bed expansion space to cause particles with a density difference ≥1.5 g / cm 3 to be stratified; Adapted particle size: For 2-20 mm metal particles (such as copper and zinc) in the slag, the amplitude needs to be >1.5 times the particle diameter; Experimental data: When the amplitude increases from 10 mm to 20 mm, the lead particle recovery rate increases by 23%. Frequency setting (2.5-3.5 Hz): Dynamic balance: Too high a frequency (>4 Hz) results in insufficient particle suspension time, and too low a frequency (<2 Hz) reduces the processing efficiency; Energy consumption comparison: The unit energy consumption is the lowest (0.8 kWh / t) at 3 Hz, and the separation efficiency reaches the peak value of 92%. Design principle of water flow velocity difference: The velocity ratio is 2:1-3:1, rising water flow: Controlled at 0.2-0.3 m / s to bring light glass / ceramic particles into the overflow layer; Falling water flow: 0.07-0.1 m / s to extend the sedimentation time window of heavy metal particles. Advantages of sawtooth wave: Compared with the traditional sine wave, the rising section is steep (accounting for 30% of the cycle) to accelerate the discharge of light particles, and the gentle falling section (accounting for 70% of the cycle) creates a stable sedimentation environment and reduces turbulent interference.

[0014] Preferably, the silica fume-fly ash composite reinforcing material in step (1) contains, by mass percentage: 70-90% silica fume, with a specific surface area ≥800 m2 / kg, with a solid content of silicon dioxide ≥ 94%; Class I fly ash 5 - 20%, with a water demand ratio ≤ 95% and a loss on ignition ≤ 5%; S95 slag powder 5 - 20%, with a specific surface area ≥ 400 m 2 / kg, with a solid content of calcium oxide ≥ 35%.

[0015] Preferably, in step (1), the mass ratio between the activation liquid and the premix is 1:8 - 1:12, and the spraying rate of the activation liquid is controlled at 0.5 - 1.2 L / min per square meter; in step (1), the mass ratio between triisopropanolamine, triethanolamine, citric acid, sodium lignosulfonate, and deionized water in the activation liquid is 1:(0.07 - 0.2):(0.17 - 0.33):(0.33 - 0.67):(331 - 997).

[0016] Preferably, the intermittent stirring mode in step (2) is as follows: Place the activated aggregate and P·O 42.5 cement in a double-horizontal shaft mixer, and perform dry mixing at 200 rpm for 60 s in a water-free state. After the dry mixing is completed, add polycarboxylate water reducer and water, and continue wet mixing at 200 rpm for 180 s in the mixer. After the wet mixing is completed, let it stand for 90 s. Finally, perform final mixing at 300 rpm for 120 s.

[0017] Preferably, the calcium sulfoaluminate-based curing agent in step (3) is prepared by calcining desulfurized gypsum and metakaolin at a mass ratio of 3:1 at 800 - 850 °C. Usually, the calcination time of 3 h is sufficient. Among them, for desulfurized gypsum, by mass percentage, its components are as follows: CaSO4·2H2O ≥ 93%, SO3 35 - 41%, CaO 30 - 35%, impurities (Cl⁻ ≤ 0.01%). Among them, for metakaolin, by mass percentage, its components are as follows: Al2O3 ≥ 40%, SiO2 ≥ 48%, loss on ignition ≤ 1.5%.

[0018] Preferably, the rotation speed of stirring in step (3) is 120 rpm, and the stirring temperature is 45 °C - 50 °C.

[0019] Preferably, the parameters of high-frequency vibration in step (4) are as follows: 50 - 60 Hz, amplitude 0.3 - 0.5 mm; the parameters of vacuum dewatering in step (4) are as follows: -0.08 MPa, 2 - 3 min.

[0020] Preferably, the curing environment in step (4) is a carbon dioxide volume concentration of 20 - 30% and a humidity ≥ 95%.

[0021] 3. Beneficial effects

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows: efficient removal of harmful substances: the three-stage water washing, magnetic separation and jigging separation technology are adopted to significantly reduce the chloride ion and heavy metal content in the slag, and the chloride ion content is reduced to ≤0.06%, and the heavy metal leaching amount is greatly reduced, ensuring the environmental protection and durability of the recycled concrete, and reducing the risk of pollution to the environment. Aggregate activity is significantly improved: the introduction of silica fume-fly ash composite reinforcement and activation liquid containing triisopropanolamine, combined with steam curing technology, optimizes the microstructure of slag aggregate, enhances the interface bonding force between aggregate and cement matrix, and improves the overall performance of recycled concrete. Recycled concrete has excellent performance: through innovative processes such as intermittent mixing, high-frequency vibration and vacuum dehydration collaborative molding, the compressive strength of recycled concrete reaches 42.0-46.0MPa, the flexural strength is 7.5-8.3MPa, and the durability indicators (such as frost resistance and impermeability) are significantly improved, meeting the needs of high-performance building materials. Green, environmentally friendly and energy-saving: The use of circulating water system and carbon dioxide maintenance technology reduces water resource consumption and carbon emissions. After the process is optimized, energy consumption is reduced by more than 30%, which meets the requirements of green building materials and sustainable development. Significant economic benefits: The process is simplified, the production cost is reduced by 20-25%, and the slag resource utilization rate is increased to more than 90%. It is economical and practical, and easy to promote industrialization.

[0023] Through the above innovations, the present invention not only solves the difficult problems of slag treatment and insufficient performance of recycled concrete, but also provides the construction industry with a high-performance, low-cost green building material option with significant social, economic and environmental benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a picture of the untreated domestic waste incineration slag in Example 1 prepared in Example 1.

[0025] Figure 2 This is a scanning electron microscope image of the domestic waste incineration slag after pretreatment in Example 1 prepared in Example 1 (the small right corner is magnified 2 times).

[0026] Figure 3 is a scanning electron microscope image of the activated aggregate prepared in Example 1.

[0027] Figure 4 This is a physical picture of the recycled concrete prepared in Example 1. DETAILED DESCRIPTION

[0028] The present invention will be described in detail below through specific embodiments. However, the uses and purposes of these exemplary embodiments are only used to illustrate the present invention, and do not constitute any form of limitation to the actual protection scope of the present invention, nor will the protection scope of the present invention be limited thereto. For parameter ranges not mentioned, intermediate values are selected. At the same time, for mass percentages or weight percentages not clearly stated or mentioned, it generally refers to the final concentration after addition.

[0029] Example 1

[0030] Preparation method of recycled concrete from municipal solid waste incineration slag

[0031] Slag pretreatment: Water washing: First stage: Put 1000 g of municipal solid waste incineration slag into a three-stage series drum stone washer, and use a high-pressure water gun with a water pressure of 1.0 MPa to wash away the surface attachments of the municipal solid waste incineration slag, and recycle the water to obtain recycled water. Second stage: Add 7.5 g of sodium tripolyphosphate (final mass percentage 0.75%) to the recycled water, and soak at room temperature for 24 h. Third stage: Rinse with 70 °C hot water, and control the chloride mass percentage content of the municipal solid waste incineration slag after water washing ≤ 0.06%. Magnetic separation: Pass the water-washed slag through a permanent magnet drum separator with a magnetic field intensity of 0.4 T to remove ferrous metals. Then extract non-ferromagnetic metals through an electromagnetic eddy current separator (frequency 55 Hz, current intensity 125 A). Jigging separation: Put the magnetically separated slag into a jig, and set the jigging pulsation curve as a sawtooth wave, with an amplitude of 17.5 mm and a frequency of 3.0 Hz. Use the ratio of the rising water flow velocity to the falling water flow velocity of 2.5:1 to sediment and separate the heavy metal particles of the municipal solid waste incineration slag. The situation of the untreated and pretreated slag is as Figure 1 and Figure 2 shown.

[0032] Aggregate activation: Crush the treated slag to a particle size of 0.375 mm using a vertical impact crusher. Premix it with a silica fume-fly ash composite reinforcement in a mass ratio of 1:0.04, that is, 1000 g of slag and 40 g of the composite reinforcement. Silica fume-fly ash composite reinforcement: 32 g (80%) of silica fume, specific surface area 800 m 2 / kg, silica solid content 94%. 4 g (10%) of Class I fly ash, water demand ratio 95%, loss on ignition 5%. 4 g (10%) of S95 slag powder, specific surface area 400 m 2 / kg, calcium oxide solid content 35%. Activation liquid: The mass ratio of the activation liquid to the premix (slag + composite reinforcement = 1040 g) is 1:10, that is, 104 g of the activation liquid. Composition of the activation liquid: 0.208 g (0.2%) of triisopropanolamine, 0.028 g of triethanolamine, 0.052 g of citric acid, 0.104 g of sodium lignosulfonate, 103.608 g of deionized water. Spraying rate 0.85 L / min / m 2Cure at 55°C in steam for 2.5 h to obtain activated aggregate, as Figure 3 shown.

[0033] Concrete batching and mixing: Put 1150 g of activated aggregate, 375 g of P·O 42.5 cement, 1.75 g of polycarboxylate water reducer, and 125 g of water into a twin-shaft mixer. Intermittent mixing mode: Dry mixing: Mix the activated aggregate and cement in anhydrous state for 60 s at 200 rpm. Wet mixing: Add the water reducer and water, and continue to mix for 180 s at 200 rpm. Standing: 90 s. Final mixing: 120 s at 300 rpm.

[0034] Addition of curing agent: The calcium sulfoaluminate-based curing agent is prepared by calcining desulfurized gypsum and metakaolin at a mass ratio of 3:1 at 825°C. Add 16.065 g of curing agent (0.85% of the total mass, based on 1150 g of aggregate + 375 g of cement + 1.75 g of water reducer + 125 g of water = 1651.75 g). Mix at 47.5°C and 120 rpm.

[0035] Molding and curing: High-frequency vibration: 55 Hz, 0.4 mm amplitude. Vacuum dewatering: -0.08 MPa, 2.5 min. Curing: Cure in an environment with a carbon dioxide volume concentration of 25% and a humidity of 95% for 72 h to obtain the recycled concrete as Figure 4 shown.

[0036] Example 2 - 10

[0037] The following examples adjust some parameters based on Example 1, and other steps are the same as those in Example 1.

[0038] Example 2: The slag is crushed to a particle size of 0.25 mm.

[0039] Example 3: The slag is crushed to a particle size of 0.5 mm.

[0040] Example 4: The mass ratio of silica fume - fly ash composite reinforcing material is 1:0.03, that is, 1000 g of slag and 30 g of composite reinforcing material (24 g of silica fume, 3 g of fly ash, 3 g of mineral powder).

[0041] Example 5: The mass ratio of silica fume - fly ash composite reinforcing material is 1:0.05, that is, 1000 g of slag and 50 g of composite reinforcing material (40 g of silica fume, 5 g of fly ash, 5 g of mineral powder).

[0042] Example 6: 0.104 g (0.1%) of triisopropanolamine in the activation liquid, and other components are adjusted proportionally, and the total mass is still 104 g.

[0043] Example 7: 0.312 g (0.3%) of triisopropanolamine in the activation liquid, and other components are adjusted proportionally, and the total mass is still 104 g.

[0044] Example 8: Steam curing temperature is 50°C.

[0045] Example 9: Steam curing temperature is 60°C.

[0046] Example 10: The addition amount of curing agent is 8.258 g (0.5% of the total mass).

[0047] Comparative Examples 1 - 6

[0048] The following comparative examples are based on Example 1 with key steps missing or parameters adjusted, and other steps are the same as Example 1.

[0049] Comparative Example 1: Without the water washing step, directly conduct magnetic separation and jigging separation on 1000 g of slag.

[0050] Comparative Example 2: Without the magnetic separation step, directly conduct jigging separation on the slag after water washing.

[0051] Comparative Example 3: Without the jigging separation step, directly crush the slag after magnetic separation.

[0052] Comparative Example 4: Without the aggregate activation step, directly use 1000 g of the crushed slag for concrete batching.

[0053] Comparative Example 5: Adopt the ordinary stirring mode (continuous stirring for 300 s, 200 rpm), without intermittent stirring.

[0054] Comparative Example 6: Without adding curing agent.

[0055] Evaluate the mechanical properties, durability and environmental friendliness of the recycled concrete to ensure it meets the building material standards.

[0056] Test content: Strength test: Test the compressive strength, flexural strength and tensile strength, referring to the "Standard for Test Methods of Physical and Mechanical Properties of Concrete" (GB / T50081). Durability test: Test the frost resistance, impermeability and carbonation resistance, referring to the "Standard for Test Methods of Long-Term Performance and Durability of Ordinary Concrete" (GB / T50082). Environmental friendliness test: Test the heavy metal leaching amount and radioactivity level, referring to the "Identification Standard for Hazardous Wastes - Identification for Leaching Toxicity" (GB5085.3) and the "Limit of Radionuclides in Building Materials" (GB6566).

[0057] The test results of the examples are as follows: Example 1: Compressive strength: 45.2 ± 1.5 MPa, Flexural strength: 8.1 ± 0.3 MPa, Chloride ion content: 0.04 ± 0.01%, Heavy metal leaching amount: 0.8 ± 0.2 mg / L, Durability: Freeze resistance: 250 ± 10 times, Impermeability: 5 ± 1 mm. Example 2: Compressive strength: 43.8 ± 1.8 MPa, Flexural strength: 7.9 ± 0.4 MPa, Chloride ion content: 0.045 ± 0.01%, Heavy metal leaching amount: 0.9 ± 0.2 mg / L, Durability: Freeze resistance: 240 ± 12 times, Impermeability: 6 ± 1 mm. Example 3: Compressive strength: 44.5 ± 1.6 MPa, Flexural strength: 8.0 ± 0.3 MPa, Chloride ion content: 0.05 ± 0.01%, Heavy metal leaching amount: 0.85 ± 0.2 mg / L, Durability: Freeze resistance: 245 ± 11 times, Impermeability: 5.5 ± 1 mm. Example 4: Compressive strength: 42.0 ± 1.7 MPa, Flexural strength: 7.5 ± 0.4 MPa, Chloride ion content: 0.048 ± 0.01%, Heavy metal leaching amount: 0.95 ± 0.2 mg / L, Durability: Freeze resistance: 230 ± 12 times, Impermeability: 7 ± 1 mm. Example 5: Compressive strength: 46.0 ± 1.4 MPa, Flexural strength: 8.3 ± 0.3 MPa, Chloride ion content: 0.042 ± 0.01%, Heavy metal leaching amount: 0.75 ± 0.2 mg / L, Durability: Freeze resistance: 255 ± 10 times, Impermeability: 4.5 ± 1 mm. Example 6: Compressive strength: 43.5 ± 1.6 MPa, Flexural strength: 7.8 ± 0.3 MPa, Chloride ion content: 0.047 ± 0.01%, Heavy metal leaching amount: 0.9 ± 0.2 mg / L, Durability: Freeze resistance: 235 ± 11 times, Impermeability: 6.5 ± 1 mm. Example 7: Compressive strength: 45.8 ± 1.5 MPa, Flexural strength: 8.2 ± 0.3 MPa, Chloride ion content: 0.043 ± 0.01%, Heavy metal leaching amount: 0.78 ± 0.2 mg / L, Durability: Freeze resistance: 252 ± 10 times, Impermeability: 5 ± 1 mm. Example 8: Compressive strength: 44.0 ± 1.7 MPa, Flexural strength: 7.9 ± 0.4 MPa, Chloride ion content: 0.046 ± 0.01%, Heavy metal leaching amount: 0.88 ± 0.2 mg / L, Durability: Freeze resistance: 240 ± 12 times, Impermeability: 6 ± 1 mm. Example 9: Compressive strength: 45.5 ± 1.5 MPa, Flexural strength: 8.1 ± 0.3 MPa, Chloride ion content: 0.044 ± 0.01%, Heavy metal leaching amount: 0.82 ± 0.2 mg / L, Durability: Freeze resistance: 248 ± 10 times, Impermeability: 5 ± 1 mm.Example 10: Compressive strength: 42.5 ± 1.8 MPa, flexural strength: 7.6 ± 0.4 MPa, chloride ion content: 0.048 ± 0.01%, heavy metal leaching amount: 0.92 ± 0.2 mg / L, durability: freeze resistance: 230 ± 12 times, impermeability: 7 ± 1 mm.

[0058] The test results of the comparative examples are as follows: Comparative Example 1: Compressive strength: 35.0 ± 2.0 MPa, flexural strength: 6.0 ± 0.5 MPa, chloride ion content: 0.15 ± 0.02%, heavy metal leaching amount: 2.5 ± 0.5 mg / L, durability: freeze resistance: 150 ± 15 times, impermeability: 15 ± 2 mm. Comparative Example 2: Compressive strength: 38.0 ± 1.9 MPa, flexural strength: 6.5 ± 0.4 MPa, chloride ion content: 0.05 ± 0.01%, heavy metal leaching amount: 1.8 ± 0.4 mg / L, durability: freeze resistance: 180 ± 13 times, impermeability: 12 ± 2 mm. Comparative Example 3: Compressive strength: 39.5 ± 1.8 MPa, flexural strength: 6.8 ± 0.4 MPa, chloride ion content: 0.045 ± 0.01%, heavy metal leaching amount: 1.5 ± 0.3 mg / L, durability: freeze resistance: 190 ± 12 times, impermeability: 10 ± 2 mm. Comparative Example 4: Compressive strength: 37.0 ± 2.0 MPa, flexural strength: 6.2 ± 0.5 MPa, chloride ion content: 0.048 ± 0.01%, heavy metal leaching amount: 0.9 ± 0.2 mg / L, durability: freeze resistance: 170 ± 14 times, impermeability: 13 ± 2 mm. Comparative Example 5: Compressive strength: 40.0 ± 1.7 MPa, flexural strength: 7.0 ± 0.4 MPa, chloride ion content: 0.047 ± 0.01%, heavy metal leaching amount: 0.85 ± 0.2 mg / L, durability: freeze resistance: 200 ± 11 times, impermeability: 8 ± 1 mm. Comparative Example 6: Compressive strength: 36.5 ± 2.1 MPa, flexural strength: 6.3 ± 0.5 MPa, chloride ion content: 0.046 ± 0.01%, heavy metal leaching amount: 0.88 ± 0.2 mg / L, durability: freeze resistance: 160 ± 15 times, impermeability: 14 ± 2 mm.

[0059] Examples 1-10 exhibited high compressive strength (42.0 - 46.0 MPa), flexural strength (7.5 - 8.3 MPa), as well as low chloride ion content (0.04 - 0.05%) and heavy metal leaching amount (0.75 - 0.95 mg / L) under different process parameters (such as slag particle size, proportion of reinforcing material, composition of activating solution, curing temperature, addition amount of curing agent). In terms of durability, the frost resistance was 230 - 255 times, and the impermeability was 4.5 - 7 mm, indicating excellent and stable performance. Comparative Examples 1-6: The absence of key process steps (such as water washing, magnetic separation, jigging separation, aggregate activation, intermittent stirring, addition of curing agent) led to a significant decline in performance. The compressive strength decreased to 35.0 - 40.0 MPa, the flexural strength decreased to 6.0 - 7.0 MPa, the chloride ion content and heavy metal leaching amount increased, and the durability was greatly reduced (frost resistance 150 - 200 times, impermeability 8 - 15 mm). The recycled concrete of Examples 1-10 performed excellently in terms of strength, environmental protection and durability, and was suitable for the requirements of high-performance building materials. While Comparative Examples 1-6 had significantly inferior performance to the Examples due to the absence of key steps, verifying the importance of the complete process flow. These data provided a reliable theoretical basis for the preparation of recycled concrete from municipal solid waste incineration slag.

[0060] Recycled concrete made from municipal solid waste incineration bottom ash has been applied in various construction engineering scenarios due to its excellent mechanical properties and environmental characteristics. The following are its main application areas and specific performances: Municipal infrastructure: Recycled concrete is suitable for the paving of sidewalks, bike lanes, and lightly loaded roads. Its compressive strength reaches 42.0 - 46.0 MPa, which is sufficient to withstand daily traffic loads. At the same time, it has excellent durability, can effectively resist climate change and wear, and significantly reduces road maintenance costs. For example, in a pilot project in a certain city, the non-motorized lane paved with recycled concrete showed no obvious cracks after two years of use, and the maintenance cost was reduced by about 30% compared with traditional concrete. This material can be used to make components such as drainage ditches and rainwater wells. Its impermeability performance is outstanding, with an impermeability depth of 5 - 7 mm, which can effectively prevent water penetration and avoid structural damage caused by long-term immersion in water. In rainy areas in the south, drainage facilities made of recycled concrete show a long service life and reduce the replacement frequency. In heavy industrial plants, the high compressive strength and flexural strength (7.5 - 8.3 MPa) of recycled concrete enable it to withstand the pressure of mechanical equipment and heavy objects. Compared with traditional concrete, its anti-wear performance is better, reducing floor cracking and wear problems. For example, in the renovation of the workshop floor of a steel plant, the service life of the floor was extended by about 25% after using recycled concrete. Logistics warehouse floors need to have high bearing capacity and wear resistance to cope with the frequent rolling of heavy-duty vehicles. The excellent performance of recycled concrete makes it an ideal choice. In a logistics park project, after the warehouse floor was paved with recycled concrete, no obvious damage caused by heavy loads occurred, and the maintenance cost was significantly reduced. In the foundation cushion and basement walls of residential buildings and commercial complexes, recycled concrete performs well. Its strong frost resistance (230 - 255 freeze-thaw cycles) is especially suitable for cold regions and can effectively resist the damage caused by freeze-thaw cycles. In a residential community project in the northeast, the foundation structure cast with recycled concrete remained stable under extreme low temperatures. Recycled concrete can be used to produce precast beams, columns, slabs and other components. Through factory production, not only the quality stability is guaranteed, but also the construction period is significantly shortened. For example, in a commercial complex project, the use of precast components shortened the overall construction period by 15% and reduced the complexity of on-site construction at the same time. The environmental characteristics of recycled concrete make it an excellent material for river slope protection. It can not only prevent soil erosion, but also will not cause secondary pollution to the water body. In a river regulation project, the slope protection blocks made of recycled concrete show good anti-scouring performance while maintaining ecological balance. In the construction of artificial wetlands, recycled concrete can be used for the casting of support structures. Its high strength and durability provide a reliable guarantee for the restoration of wetland ecosystems, and at the same time its low environmental impact meets the sustainable development goals of ecological restoration.

[0061] The technical advantages of recycled concrete are the key to its wide application. The following analyzes its specific manifestations in actual projects from three aspects: environmental protection, performance advantages, and economy: For every 1 ton of slag utilized, the landfill volume can be reduced by approximately 0.8 - 1.0 tons, significantly alleviating the pressure of urban waste treatment. For example, in a project near an incineration plant, a recycled concrete production line with an annual slag treatment capacity of 100,000 tons extended the service life of the local landfill by about 5 years. Using CO2 curing technology, each cubic meter of recycled concrete can absorb 50 - 70 kg of CO2, not only accelerating the hardening process but also contributing to the carbon emission reduction goal. In a pilot project, this technology reduced the overall carbon emissions of the project by approximately 10%. Compared with traditional recycled concrete, the strength of this material has increased by 20 - 30%, reaching the C30 - C40 standard, meeting various engineering requirements. In an industrial floor project, its high strength significantly reduces the cracking risk caused by excessive loads. Recycled concrete is superior to ordinary concrete in terms of frost resistance, impermeability, and carbonation resistance. In cold and humid regions, its service life is extended by about 20% compared to traditional materials, reducing the maintenance frequency. After adding polycarboxylate water reducer, the concrete has excellent fluidity and pumpability, facilitating on-site construction. In a high-rise building project, its good workability increased the pouring efficiency by 15%. Using slag as the main aggregate, the cost is much lower than that of natural sand and gravel, reducing the production cost of concrete by 10 - 15%. This advantage is particularly obvious in resource-scarce areas. The application of intermittent mixing and high-frequency vibration forming technology improves production efficiency and shortens the construction period.

[0062] For example, in a municipal road project, the construction period was shortened by 10 days compared to the traditional method. Taking a city road construction project as an example, the economic benefits of recycled concrete are analyzed: Road length: 1 km, width: 10 m, thickness: 0.2 m. Concrete usage: 2000 m³. Cost comparison: Traditional concrete, raw material cost: 400 yuan / m³, construction cost: 100 yuan / m³, total cost: (400 + 100) × 2000 = 1,000,000 yuan. Recycled concrete: Raw material cost: 320 yuan / m³ (slag replacement rate of 50%, cost reduction of 20%), construction cost: 90 yuan / m³ (process optimization, efficiency improvement), total cost: (320 + 90) × 2000 = 820,000 yuan. Cost savings: 1,000,000 - 820,000 = 180,000 yuan, a reduction of 18%. Slag utilization volume: 2000 m³ × 1.2 t / m³ × 50% = 1200 tons, landfill volume reduction of 1200 tons. CO2 emission reduction: 2000 m³ × 60 kg / m³ = 120,000 kg (120 tons).

[0063] The above content is a further detailed description of the present invention in combination with specific embodiments. It cannot be determined that the specific implementation of the present invention is only limited to these descriptions. For those of ordinary skill in the technical field to which the present invention pertains, without departing from the concept of the present invention, several simple deductions or substitutions can still be made, and all should be regarded as falling within the protection scope determined by the claims submitted for the present invention.

Claims

1. A preparation method of recycled concrete from domestic waste incineration slag, characterized in that: It includes the following steps: (1) After washing, magnetic separation, and jigging separation of the domestic waste incineration slag, it is crushed to a particle size of 0.25 - 0.5 mm using a vertical impact crusher, and then premixed with a silica fume - fly ash composite reinforcing material at a mass ratio of 1:(0.03 - 0.05) to obtain a premix. An activation liquid containing 0.1 - 0.3% triisopropanolamine by final mass percentage is sprayed, and steam - cured at 50 - 60 °C for 2 - 3 h to obtain activated aggregate; (2) The activated aggregate, P·O42.5 cement, polycarboxylate superplasticizer, and water are put into a double - shaft mixer according to the mass ratio (1050 - 1250):(350 - 400):(1.5 - 2):(100 - 150), and an intermittent mixing mode is adopted to obtain a reaction system; (3) Then, a calcium sulfoaluminate - based curing agent with a total mass percentage of 0.5 - 1.2% is added to the reaction system and continuously stirred; (4) Co - forming with high - frequency vibration and vacuum dehydration is adopted, and cured for 72 h.

2. The preparation method of the recycled concrete from domestic waste incineration slag according to claim 1, characterized in that: The operation of washing in step (1) is as follows: The domestic waste incineration slag is put into a three - stage series drum stone washer. In the first stage, a high - pressure water gun with a water pressure of 0.8 - 1.2 MPa is used to wash the surface attachments of the domestic waste incineration slag and recycle the water to obtain recycled water. In the second stage, 0.5 - 1% sodium tripolyphosphate by final mass percentage is added to the recycled water for soaking the domestic waste incineration slag at normal temperature for 24 h. In the third stage, the domestic waste incineration slag is rinsed with hot water at 60 - 80 °C, and the chloride mass percentage content of the domestic waste incineration slag after washing is controlled to be ≤0.06%; The operation of magnetic separation in step (1) is as follows: The domestic waste incineration slag after washing is passed through a permanent magnetic drum separator with a magnetic field intensity of 0.3 - 0.5 T to remove ferrous metals, and then non - ferromagnetic metals are extracted by an electromagnetic eddy current separator, where the frequency is 50 - 60 Hz and the current intensity is 100 - 150 A; The operation of jigging in step (1) is as follows: The domestic waste incineration slag after magnetic separation is put into a jig, and the jigging pulsation curve is set as a sawtooth wave, with an amplitude of 15 - 20 mm and a frequency of 2.5 - 3.5 Hz. The heavy - metal particles of the domestic waste incineration slag are settled and separated by using the ratio of the rising water flow velocity to the falling water flow velocity of 2:1 - 3:

1.

3. The preparation method of the refuse incineration bottom ash recycled concrete according to claim 1, characterized in that: In step (1), the silica fume-fly ash composite reinforcing material contains, by mass percentage: 70-90% of silica fume, with a specific surface area ≥ 800 m 2 / kg and a solid content of silicon dioxide ≥ 94%; 5-20% of Class I fly ash, with a water demand ratio ≤ 95% and a loss on ignition ≤ 5%; 5-20% of S95 slag powder, with a specific surface area ≥ 400 m 2 / kg and a solid content of calcium oxide ≥ 35%.

4. The preparation method of the refuse incineration bottom ash recycled concrete according to claim 1, characterized in that: In step (1), the mass ratio between the activation liquid and the premix is 1:8 - 1:12, and the spraying rate of the activation liquid is controlled at 0.5 - 1.2 L / min per square meter; In step (1), the mass ratio between triisopropanolamine, triethanolamine, citric acid, sodium lignosulfonate, and deionized water in the activation liquid is 1:(0.07 - 0.2):(0.17 - 0.33):(0.33 - 0.67):(331 - 997).

5. The preparation method of the recycled concrete from domestic waste incineration slag according to claim 1, characterized in that: The intermittent mixing mode in step (2) is as follows: The activated aggregate and P·O42.5 cement are placed in a double - shaft mixer and dry - mixed at 200 rpm for 60 s in a water - free state. After the dry - mixing is completed, the polycarboxylate superplasticizer and water are added, and wet - mixing is continued in the mixer at 200 rpm for 180 s. After the wet - mixing ends, it is left standing for 90 s. Finally, final mixing is carried out at 300 rpm for 120 s.

6. The preparation method of the refuse incineration bottom ash recycled concrete according to claim 1, characterized in that: In step (3), the calcium sulfoaluminate-based curing agent is prepared by calcining desulfurized gypsum and metakaolin at a mass ratio of 3:1 at 800 - 850 °C.

7. The preparation method of the refuse incineration bottom ash recycled concrete according to claim 1, characterized in that: In step (3), the stirring speed is 120 rpm, and the stirring temperature is 45 °C - 50 °C.

8. The preparation method of the refuse incineration bottom ash recycled concrete according to claim 1, characterized in that: In step (4), the parameters of high-frequency vibration are as follows: 50 - 60 Hz, amplitude of 0.3 - 0.5 mm; the parameters of vacuum dehydration in step (4) are as follows: -0.08 MPa, 2 - 3 min.

9. The preparation method of the recycled concrete from domestic waste incineration slag according to claim 1, characterized in that: In step (4), the curing environment is a carbon dioxide volume concentration of 20 - 30% and a humidity of ≥95%.

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