Green manufacturing and recycling process of precast concrete bridge member

Abstract

The invention relates to the field of concrete bridge members, and discloses a green manufacturing and recycling process of precast concrete bridge members, which comprises the following steps: raw materials are subjected to green treatment, solid wastes including sediment in a sedimentation tank generated in the production process are collected, and the solid wastes are crushed and screened to prepare a mineral admixture for replacing part of cement; dust is separated and recycled, in the concrete preparation process, dust generated by stirring equipment is separated, recyclable dust is recycled for concrete production, and non-recyclable dust is mixed with building solid waste to prepare an environment-friendly building material. Various wastes generated in the production and recovery process are converted into renewable resources such as mineral admixtures, recycled aggregates and the like through crushing and screening, calcining and activating, chemical treatment, lossless disassembling and grading and sorting, the renewable resources are directly reused for concrete preparation, component production and auxiliary building material manufacturing, dependence on new resources such as cement, gravel and steel is reduced from the source, and the production cost is reduced. The resource utilization rate is improved; the carbon emission is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of concrete bridge components, and in particular to a green manufacturing and recycling process for precast concrete bridge components. Background Art

[0002] With the continuous advancement of infrastructure construction, the demand for precast concrete bridge components is growing. Under the general trend of pursuing sustainable development in the construction industry, efficient resource utilization and environmental protection have become key issues. On the one hand, a large amount of waste is generated during industrial production and construction, such as tailings, coal gangue, steel slag, and construction waste. The accumulation of these wastes not only occupies a large amount of land resources, but also may cause pollution to the surrounding environment. On the other hand, the production of traditional building materials, such as cement, sand and gravel, steel, etc., requires a large amount of natural resources, and produces high carbon emissions during the production process, which puts great pressure on the ecological environment. Therefore, developing a process that can make full use of various types of waste and convert them into renewable resources that can be used in construction production is of great significance for alleviating resource pressure, reducing environmental pollution, and promoting the green and sustainable development of the construction industry.

[0003] At present, there are some shortcomings in the manufacturing and recycling technology of precast concrete bridge components. In the production process, the treatment methods of various types of waste are relatively extensive, and their potential value has not been fully tapped. Most wastes are simply piled up or landfilled, and effective resource utilization is not achieved. In the concrete preparation process, a large amount of raw cement, sand and gravel and other materials are relied upon, resulting in large resource consumption and high costs. Summary of the Invention

[0004] In response to the shortcomings of the existing technology, the present invention provides a green manufacturing and recycling and reuse process for precast concrete bridge components, which solves the problems of extensive waste treatment and ineffective resource utilization in the manufacturing and recycling and reuse of precast concrete bridge components in the existing technology, and the reliance on a large amount of virgin materials for concrete preparation, resulting in high resource consumption and high costs.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solutions: A green manufacturing and recycling process for precast concrete bridge components includes the following steps: Green processing of raw materials, collection of solid waste generated during the production process, including sedimentation tank silt, crushing and screening to make mineral admixtures to replace part of the cement; Dust separation and reuse: During the concrete preparation process, the dust generated by the mixing equipment is separated and processed. Reusable dust is reused in concrete production, while non-reusable dust is mixed with construction solid waste to make environmentally friendly building materials; Wastewater treatment and reuse: collect and treat wastewater from mold cleaning, and reuse it in the recycled aggregate washing process; Bridge component recycling: first, ultrasonic detection is used to locate steel bars and embedded parts, and then hydraulic shears and laser cutting are used for non-destructive disassembly; recycled material processing: concrete blocks are crushed and screened in two stages, steel bars are derusted, straightened and graded, metal parts are sorted by material, and plastic products are crushed and granulated; Materials are recycled and recycled aggregates are used for concrete components with strength grades lower than C30, recycled steel bars are processed into connectors, and plastic particles are used to prepare isolation pads.

[0006] By adopting the above-mentioned technical solutions, various types of waste generated during the production and recycling process are converted into renewable resources such as mineral admixtures and recycled aggregates through crushing and screening, calcination activation, chemical treatment, non-destructive disassembly, and grading and sorting, and directly reused in concrete preparation, component production, and ancillary building materials manufacturing, thereby reducing dependence on new resources such as cement, sand, gravel, and steel from the source, achieving efficient recycling and full value utilization of industrial solid waste and construction waste, significantly improving resource utilization and reducing carbon emissions.

[0007] Preferably, the solid waste in the green treatment step of the raw materials includes tailings, coal gangue, steel slag and sedimentation tank sediment, wherein the mass proportions of tailings, coal gangue and steel slag in the mineral admixture are 40% to 50%, 20% to 30% and 10% to 20% respectively, and the sum of the three is ≤90%, and the rest is sedimentation tank sediment, the tailings are calcined at 800℃ for 2 hours to remove impurities, the coal gangue is ultrasonically shaken with 5% NaOH solution at a constant temperature of 80℃ for 2 hours, and the steel slag is ground to a specific surface area of ​​≥450m 2 / kg, activity index ≥75% at 28 days.

[0008] Preferably, in the green processing step of the raw materials, the solid waste is first coarsely crushed by a jaw crusher, then finely ground by a ball mill to a particle size of ≤5mm, and then mixed with cement in a high-powered mixer at a mass ratio of 1:1 to 1:1.5 to form a mineral admixture, and the proportion of the mineral admixture replacing cement is 20% to 30%.

[0009] Preferably, in the dust separation and reuse step, the environmentally friendly building materials include permeable bricks and curbstones, the pulse bag dust collector of the mixing equipment has a collection efficiency of ≥95%, the pulse bag dust collector is integrated with a wet electrostatic dust removal module, and the PM2.5 emission concentration is ≤10mg / m 3 The air separation device separates fine powder with a particle size of ≤50μm and CaO≥30% at a wind speed of 10-15m / s. After resin purification, it is mixed back into concrete at 15%-20%. The dust that cannot be reused is added with 3% nano-SiO2 and pressed into lightweight permeable bricks with a compressive strength of ≥8MPa.

[0010] Preferably, the wastewater treatment and reuse step specifically includes: The cleaning area is equipped with a 3° to 5° slope diversion trough with an effective volume of ≥1m 3 Sedimentation tank, wastewater sedimentation ≥ 30 minutes; The effluent is filtered through a 100-mesh filter and then transported by a centrifugal pump to the recycled aggregate washing section; The sedimentation tank sludge is discharged into the solid waste crushing process in the green processing step of the raw materials.

[0011] Preferably, in the bridge component recovery step, the ultrasonic detection positioning accuracy is ±2mm, the hydraulic scissor pressure is set to 200-300MPa, the laser cutting power is 4-6kW, and the incision width is ≤1mm.

[0012] Preferably, in the recycled material processing step, the concrete block is first crushed by a jaw crusher and then crushed for the second time by an impact crusher to be processed into 5-20 mm recycled aggregate with a mud content of ≤1%. The steel bars are rust-removed by shot blasting with a shot blasting pressure of 0.3-0.5 MPa and a surface roughness of Ra ≥ 20 μm. The straightening is performed by a CNC straightening machine with a straightening accuracy of ≤ ± 1 mm.

[0013] Preferably, in the recycling material processing step, the metal parts are sorted by material using a spectrometer, and the plastic products are crushed by a twin-screw crusher, and the particle size is controlled to be 3-5 mm.

[0014] Preferably, in the material recycling step, 0.02% polycarboxylate water-reducing agent and 1.5% steel fiber are added to the recycled aggregate, and the water absorption rate is ≤3% after CO2 mineralization curing.

[0015] Preferably, in the material recycling step, the plastic particles are modified by adding 5% nano-calcium carbonate by mass when used to prepare the isolation pads.

[0016] The present invention provides a green manufacturing and recycling process for precast concrete bridge components. It has the following beneficial effects: 1. The present invention converts various types of waste generated during the production and recycling process into renewable resources such as mineral admixtures and recycled aggregates through crushing and screening, calcination activation, chemical treatment, non-destructive disassembly, and grading and sorting, and directly reuses them in concrete preparation, component production, and ancillary building material manufacturing, thereby reducing dependence on new resources such as cement, sand, gravel, and steel from the source, achieving efficient recycling and full value utilization of industrial solid waste and construction waste, significantly improving resource utilization and reducing carbon emissions.

[0017] 2. The present invention effectively controls dust emissions and reduces pollution to the atmospheric environment through dust removal equipment. For mold cleaning wastewater, a sedimentation and filtration treatment process is adopted to achieve wastewater reuse. At the same time, the precipitated sediment is also rationally utilized to avoid its pollution to soil and water bodies. This comprehensive environmental protection measure reduces the negative impact of the entire production and recycling process on the environment.

[0018] 3. The present invention significantly improves the performance of recycled materials by conducting targeted treatment on various types of recycled materials, thereby improving the quality of products manufactured using these materials. After special treatment, the performance of recycled aggregates is improved, making the resulting concrete components more durable. The plastic particles are modified to enhance the compressive strength and durability of the isolation pads used to prepare them. These improvements enable the products to better meet usage requirements and extend the product's service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a process flow chart for the green manufacturing and recycling of precast concrete bridge components of the present invention. DETAILED DESCRIPTION

[0020] The following will clearly and completely describe the technical solution of the present invention in conjunction with the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0021] Please see the attached Figure 1 The embodiment of the present invention provides a green manufacturing and recycling process for precast concrete bridge components, comprising the following steps: Green processing of raw materials, collection of solid waste generated during the production process, including sedimentation tank silt, crushing and screening to make mineral admixtures to replace part of the cement; Dust separation and reuse: During the concrete preparation process, the dust generated by the mixing equipment is separated and processed. Reusable dust is reused in concrete production, while non-reusable dust is mixed with construction solid waste to make environmentally friendly building materials; Wastewater treatment and reuse: collect and treat wastewater from mold cleaning, and reuse it in the recycled aggregate washing process; Bridge component recycling: first, ultrasonic detection is used to locate steel bars and embedded parts, and then hydraulic shears and laser cutting are used for non-destructive disassembly; recycled material processing: concrete blocks are crushed and screened in two stages, steel bars are derusted, straightened and graded, metal parts are sorted by material, and plastic products are crushed and granulated; Materials are recycled and recycled aggregates are used for concrete components with strength grades lower than C30, recycled steel bars are processed into connectors, and plastic particles are used to prepare isolation pads.

[0022] Solid wastes in the green processing step of raw materials include tailings, coal gangue, steel slag and sedimentation pond sand. The mass proportions of tailings, coal gangue and steel slag in the mineral admixture are 40% to 50%, 20% to 30% and 10% to 20% respectively, and the total of the three is ≤90%. The rest is sedimentation pond sand. The tailings are calcined at 800℃ for 2 hours to remove impurities. The coal gangue is ultrasonically shaken with 5% NaOH solution at a constant temperature of 80℃ for 2 hours. The steel slag is ground to a specific surface area of ​​≥450m 2 / kg, 28-day activity index ≥75%; solid waste is first coarsely crushed by a jaw crusher, then finely ground by a ball mill to a particle size ≤5mm, and then mixed with cement in a high-powered mixer at a mass ratio of 1:1 to 1:1.5 to form a mineral admixture, and the proportion of mineral admixture replacing cement is 20% to 30%.

[0023] Specifically, in the green processing step of raw materials, tailings, coal gangue, steel slag and sedimentation tank sediment are collected as solid waste. They are first coarsely crushed by a jaw crusher and then finely ground by a ball mill to a particle size of ≤5mm. The tailings are calcined at 800℃ for 2 hours to effectively remove impurities and improve purity; the coal gangue is ultrasonically shaken with 5% NaOH solution at a constant temperature of 80℃ for 2 hours to stimulate its potential activity; the steel slag is ground to a specific surface area of ​​≥450m 2 / kg and a 28-day activity index of ≥75% to guarantee performance. The treated solid waste is then mixed with cement in a high-performance mixer at a mass ratio of 1:1 to 1:1.5 to create a mineral admixture that can replace 20% to 30% of cement. This treatment method not only achieves resource utilization of industrial waste and reduces cement usage, but also improves the overall performance of concrete and reduces negative environmental impacts.

[0024] In the dust separation and reuse step, environmentally friendly building materials include permeable bricks and curbstones. The collection efficiency of the pulse bag dust collector of the mixing equipment is ≥95%. The pulse bag dust collector is integrated with a wet electrostatic dust removal module. The PM2.5 emission concentration is ≤10mg / m 3 The air separation device separates fine powder with a particle size of ≤50μm and CaO≥30% at a wind speed of 10-15m / s. After resin purification, it is mixed back into concrete at 15%-20%. The dust that cannot be reused is added with 3% nano-SiO2 and pressed into lightweight permeable bricks with a compressive strength of ≥8MPa.

[0025] Specifically, in the dust separation and reuse step, the mixing equipment is equipped with a pulse bag dust collector with a collection efficiency of ≥95%, and an integrated wet electrostatic dust removal module to ensure that the PM2.5 emission concentration is ≤10mg / m3 , effectively controlling dust pollution. A wind separator, operating at a wind speed of 10-15 m / s, separates fine powder with a particle size ≤50 μm and a CaO content ≥30%. After resin purification, this fine powder is reincorporated into concrete at a rate of 15-20%, improving resource utilization. Non-recyclable dust, after adding 3% nano-SiO2, is pressed into lightweight, permeable bricks with a compressive strength ≥8 MPa. It can also be made into environmentally friendly building materials such as curbstones. This method not only solves the dust pollution problem but also transforms waste into valuable building materials, achieving dust recycling and turning waste into valuable resources.

[0026] The wastewater treatment and reuse steps specifically include: The cleaning area is equipped with a 3° to 5° slope diversion trough with an effective volume of ≥1m 3 Sedimentation tank, wastewater sedimentation ≥ 30 minutes; The effluent is filtered through a 100-mesh filter and then transported by a centrifugal pump to the recycled aggregate washing section; The sedimentation tank sludge is discharged into the solid waste crushing process in the green treatment step of the raw materials collection.

[0027] Specifically, in the wastewater treatment and reuse step, the mold cleaning area is equipped with a 3° to 5° slope diversion trough, which can quickly guide the wastewater into the effective volume ≥ 1m 3 The wastewater is placed in a sedimentation tank for 30 minutes or longer, allowing most solid impurities to settle. The effluent is filtered through a 100-mesh filter to further remove fine particles before being pumped by a centrifugal pump to the recycled aggregate washing process. The sedimentation tank sediment is then discharged into the solid waste crushing process within the green raw material processing step, realizing its resource utilization. This process effectively treats mold cleaning wastewater, reduces the use of fresh water resources, and lowers production costs. It also rationally utilizes waste materials such as sediment, in line with the concept of green manufacturing.

[0028] During the bridge component recycling process, the ultrasonic detection positioning accuracy is ±2mm, the hydraulic scissor pressure is set to 200-300MPa, the laser cutting power is 4-6kW, and the incision width is ≤1mm.

[0029] Specifically, when recycling bridge components, ultrasonic detection is first used, with a positioning accuracy of ±2mm, to precisely locate the position of rebar and embedded parts. Hydraulic shears are then used with a blade pressure set at 200-300MPa, combined with laser cutting at a power of 4-6kW and a cut width of 1mm or less, for non-destructive disassembly. This precise operation maximizes the integrity of the concrete blocks and rebar after disassembly, providing a good foundation for the subsequent sorting, processing, and reuse of recycled materials, improving their quality and usability while reducing resource waste.

[0030] In the recycling material processing step, the concrete blocks are first crushed by a jaw crusher and then crushed for the second time by an impact crusher to be processed into 5-20mm recycled aggregate with a mud content of ≤1%. The steel bars are rust-removed by shot blasting with a shot blasting pressure of 0.3-0.5MPa and a surface roughness of Ra ≥ 20μm. Straightening is carried out using a CNC straightening machine with a straightening accuracy of ≤±1mm. Metal parts are sorted by material using a spectrometer, and plastic products are crushed by a twin-screw crusher with a particle size controlled to 3-5mm.

[0031] Specifically, during the recycled material processing step, concrete blocks are first crushed using a jaw crusher, then a secondary crusher using an impact crusher, and processed into 5-20mm recycled aggregate. The mud content is strictly controlled to ≤1% to ensure aggregate quality. The steel bars are shot blasted to remove rust at a pressure of 0.3-0.5MPa, achieving a surface roughness of Ra ≥ 20μm. They are then straightened using a CNC straightening machine with a straightening accuracy of ≤±1mm, restoring the steel bar's properties. Metal parts are sorted by material using a spectrometer, and plastic products are crushed to a particle size of 3-5mm using a twin-screw crusher. This process enables the fine classification and pretreatment of recycled materials, providing high-quality raw materials for subsequent recycling and improving resource recovery efficiency.

[0032] In the material recycling step, 0.02% polycarboxylate water reducer and 1.5% steel fiber are added to the recycled aggregate, and the water absorption rate is ≤3% after CO2 mineralization curing; in the material recycling step, 5% nano-calcium carbonate is added by mass to modify the plastic particles when used to prepare isolation pads.

[0033] Specifically, during the material recycling step, the recycled aggregate is treated with 0.02% polycarboxylate water reducer and 1.5% steel fiber, followed by CO2 mineralization curing, effectively reducing water absorption to ≤3%, improving aggregate performance. The plastic particles used to make the isolation pads are modified by adding 5% nano-calcium carbonate by mass, enhancing the pads' compressive strength and durability. This treatment allows the recycled aggregate and plastic particles to be better utilized in the manufacture of corresponding products, increasing the value of the recycled materials, extending product lifespans, reducing the need for new materials, and promoting resource recycling.

[0034] The following is an introduction with reference to specific embodiments: Example 1 Green Raw Materials Processing: Raw materials collection: 45% tailings, 25% gangue, 20% steel slag, and 10% sedimentation pond sand are collected by mass. The tailings come from mining waste, the gangue originates from the coal washing process, the steel slag is taken from steel mill waste, and the sedimentation pond sand is collected from the wastewater treatment sedimentation tank at the production site.

[0035] Pretreatment: The tailings were calcined in a muffle furnace at 800℃ for 2 hours; the gangue was placed in a reactor filled with 5% NaOH solution and ultrasonically shaken at a constant temperature of 80℃ for 2 hours; the steel slag was ground in a ball mill to a specific surface area of ​​480m 2 / kg.

[0036] Mixing preparation: The pre-treated solid waste is first crushed in a jaw crusher and then finely ground in a ball mill to a particle size of 3mm. It is then mixed with cement in a high-powered mixer at a mass ratio of 1:1.2 and mixed evenly to form a mineral admixture.

[0037] Dust separation and recycling dust collection: The concrete mixing equipment is equipped with a pulse bag dust collector with a collection efficiency of 96% and an integrated wet electrostatic dust removal module.

[0038] Fine powder separation and back-mixing: The air separation device separates fine powder with a particle size of 40μm and a CaO content of 35% at a wind speed of 12m / s. After the fine powder is purified by resin, it is back-mixed into the concrete at a ratio of 18%.

[0039] Treatment of non-recyclable dust: Add 3% nano-SiO2 to the non-recyclable dust, send it into the brick making machine, press it under a pressure of 10MPa, and then steam cure it to make lightweight permeable bricks.

[0040] Wastewater treatment and reuse Wastewater collection and sedimentation: The mold cleaning area is equipped with a 4° slope diversion trough with an effective volume of 1.2m 3 The wastewater is allowed to settle in the sedimentation tank for 35 minutes.

[0041] Filtration and reuse: The effluent after sedimentation is filtered through a 100-mesh filter and transported by a centrifugal pump to the recycled aggregate washing section.

[0042] Sediment treatment: Sediment in the sedimentation tank is discharged into the solid waste crushing process for green treatment of raw materials.

[0043] Bridge component recycling Positioning and disassembly: Ultrasonic detectors were used to detect bridge components with a positioning accuracy of ±1.5mm to determine the position of rebar and embedded parts. Hydraulic shears were used with a blade pressure set to 250MPa, combined with a 5kW laser cutting power and a 0.8mm incision width for disassembly.

[0044] Recycled material processing Concrete block processing: Concrete blocks are first crushed by a jaw crusher and then crushed by an impact crusher to produce 5-20mm recycled aggregate.

[0045] Steel bar treatment: The steel bars are shot peened with a shot peening pressure of 0.4MPa and then straightened using a CNC straightening machine.

[0046] Processing of metal parts and plastic products: Metal parts are sorted by material using a spectrometer, and plastic products are crushed to a particle size of 4mm using a twin-screw crusher.

[0047] Material recycling Recycled aggregate treatment: Add 0.02% polycarboxylate water reducer and 1.5% steel fiber to the recycled aggregate and place it in a curing box for CO2 mineralization curing.

[0048] Plastic particle processing: Plastic particles are modified by adding 5% nano-calcium carbonate in a mass ratio and used to prepare isolation pads.

[0049] Example 2 Green processing of raw materials Raw materials collection: 40% tailings, 30% coal gangue, 15% steel slag, and 15% sedimentation pond sand are collected by mass ratio.

[0050] Pretreatment: Tailings were calcined at 800℃ for 2 hours, coal gangue was ultrasonically shaken at 80℃ for 2 hours with 5% NaOH solution, and steel slag was ground to a specific surface area of ​​460m 2 / kg.

[0051] Mixing preparation: After coarse and fine crushing, mix with cement in a high-powered mixer at a mass ratio of 1:1.3 to form mineral admixture.

[0052] Dust separation and reuse Dust collection: Pulse bag dust collector collection efficiency is 95%.

[0053] Fine powder separation and back-mixing: Fine powder with a particle size of 45μm and CaO32% was separated at a wind speed of 10m / s, and 16% was back-mixed into concrete.

[0054] Treatment of non-recyclable dust: Add 3% nano-SiO2 to make lightweight permeable bricks.

[0055] Wastewater treatment and reuse Wastewater collection and sedimentation: 3° slope diversion trough connected to 1.1m 3 In the sedimentation tank, wastewater settles for 32 minutes.

[0056] Filtration and reuse: perform related operations after processing.

[0057] Sediment treatment: Sediment is discharged into the solid waste crushing process.

[0058] Bridge component recycling Positioning and disassembly: Ultrasonic detection positioning accuracy is ±1mm, hydraulic shear pressure is 220MPa, laser cutting power is 4.5kW, and incision width is 0.9mm for disassembly.

[0059] Recycled material processing Concrete block processing: Crushed into 5-20mm recycled aggregate.

[0060] Steel bar treatment: shot peening pressure 0.35MPa, surface roughness Ra22μm, straightening accuracy ±0.9mm.

[0061] Processing of metal parts and plastic products: sorting of metal parts and crushing of plastic products to a particle size of 3.5mm.

[0062] Material recycling Recycled aggregate treatment: Add polycarboxylate water reducer and steel fiber and then perform CO2 mineralization curing.

[0063] Plastic particle processing: After adding 5% nano calcium carbonate to modify it, it is used to prepare isolation pads.

[0064] Comparative Example 1 (corresponding to Example 1) The differences are as follows: Green processing of raw materials: coal gangue is not subjected to ultrasonic vibration treatment.

[0065] Dust separation and reuse: The pulse bag dust collector does not have an integrated wet electrostatic dust removal module.

[0066] Wastewater treatment and reuse: Wastewater sedimentation time is 20 minutes.

[0067] Bridge component recycling: The ultrasonic detection positioning accuracy is ±3mm.

[0068] Recycled material processing: The shot blasting pressure of steel bars is 0.2MPa.

[0069] Material recycling: Recycled aggregates do not require the addition of polycarboxylate water reducer and steel fiber.

[0070] Comparative Example 2 (corresponding to Example 2) The differences are as follows: Green processing of raw materials: tailings, coal gangue and steel slag are not mixed randomly according to proportion.

[0071] Dust separation and reuse: The wind speed of the air separation device fluctuates between 5-18m / s.

[0072] Wastewater treatment and reuse: The sedimentation tank sludge is directly discarded.

[0073] Bridge component recycling: Laser cutting power is adjusted to 3kW.

[0074] Recycled material processing: The particle size of plastic products is controlled at 6-8mm.

[0075] Material recycling: No nano-calcium carbonate is added when plastic particles are used to prepare isolation pads.

[0076] Table 1: Comparative effect of examples and comparative examples Comparison project explanation: 28-day compressive strength of concrete: reflects the compressive strength of concrete made from mineral admixtures using different treatment processes and cured for 28 days. The higher the value, the better the concrete strength performance, which can reflect the green treatment effect of raw materials and its impact on concrete performance.

[0077] PM2.5 emission concentration: refers to the PM2.5 content in the exhaust gas when the mixing equipment is running in the dust separation and reuse link. The lower the concentration, the better the dust pollution control. It is a key indicator to measure the environmental protection effect of dust treatment.

[0078] Recycled Aggregate Mud Content: This refers to the percentage of soil in the recycled aggregate after processing. A low mud content indicates high-quality recycled aggregate, minimizing the impact on subsequent concrete component performance.

[0079] Retention rate of steel bar yield strength: During the recycling and subsequent processing of bridge components, the ratio of yield strength to original strength after the steel bars are disassembled, derusted, and otherwise treated is higher. The higher the retention rate, the better the performance of the steel bars is maintained during the recycling process, and the more they can meet the requirements for subsequent processing and use.

[0080] The present invention sets embodiments and comparative examples around the green manufacturing and recycling process of precast concrete bridge components. Different comparative examples have different parameters from the corresponding embodiments in various links, which significantly affects the results: Green treatment of raw materials: Comparative Example 1 did not ultrasonically vibrate the gangue, resulting in insufficient activity of the mineral admixture, and the 28-day compressive strength of the concrete dropped from 45 MPa in Example 1 to 40.5 MPa. Comparative Example 2 used random raw material proportions, resulting in unstable mineral admixture performance and large fluctuations in concrete strength.

[0081] Dust separation and reuse: Comparative Example 1: The pulse bag dust collector is not integrated with the wet electrostatic dust removal module, and the PM2.5 emission concentration rises to 25mg / m 3 , back-mixing fine powder reduces the compressive strength of concrete by 8%. In comparative example 2, the wind speed of the air separation fluctuates, the fine powder cannot be effectively separated, the back-mixing amount is unstable, and the concrete quality fluctuates greatly.

[0082] Wastewater treatment and reuse: In comparative example 1, the sedimentation time in the sedimentation tank was shortened, the mud content of the recycled aggregate increased to 1.5%, and the concrete strength decreased by 12%. In comparative example 2, the sedimentation tank sediment was not recycled, resulting in a waste of resources.

[0083] Bridge component recycling: Comparative Example 1: Ultrasonic positioning accuracy is low, resulting in reduced steel bar yield strength retention and concrete block integrity. Comparative Example 2: Laser cutting power is low, resulting in reduced cutting efficiency and poor quality.

[0084] Recycled Material Processing and Recycling: In Comparative Example 1, the shot blasting pressure for steel bar derusting was low, resulting in a 15% reduction in the tensile strength of connectors. In Comparative Example 2, the plastic product was crushed to a large particle size, resulting in poor isolation pad performance. In Comparative Example 1, the recycled aggregate lacked the addition of key materials, resulting in high water absorption and a 20% reduction in component lifespan. In Comparative Example 2, the plastic particles were unmodified, resulting in a 20% reduction in the compressive strength of the isolation pad.

[0085] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A green manufacturing and recycling process for precast concrete bridge components, characterized in that: The following steps are involved: Green processing of raw materials, collection of solid waste generated during the production process, including sedimentation tank silt, crushing and screening to make mineral admixtures to replace part of the cement; Dust separation and reuse: During the concrete preparation process, the dust generated by the mixing equipment is separated and processed. Reusable dust is reused in concrete production, while non-reusable dust is mixed with construction solid waste to make environmentally friendly building materials; Wastewater treatment and reuse: collect and treat wastewater from mold cleaning, and reuse it in the recycled aggregate washing process; Bridge component recycling: first locate the steel bars and embedded parts through ultrasonic detection, then use hydraulic shears and laser cutting to carry out non-destructive disassembly; Recycled material processing, two-stage crushing and screening of concrete blocks, rust removal, straightening and grading of steel bars, sorting of metal parts by material, and crushing and granulating of plastic products; Materials are recycled and recycled aggregates are used for concrete components with strength grades lower than C30, recycled steel bars are processed into connectors, and plastic particles are used to prepare isolation pads.

2. The green manufacturing and recycling process of precast concrete bridge components according to claim 1 is characterized in that: The solid waste in the green processing step of raw materials includes tailings, coal gangue, steel slag and sedimentation tank sludge, among which the mass proportions of tailings, coal gangue and steel slag in the mineral admixture are 40% to 50%, 20% to 30% and 10% to 20% respectively, and the sum of the three is ≤90%. The rest is sedimentation tank sludge. The tailings are calcined at 800°C for 2 hours to remove impurities, the coal gangue is ultrasonically shaken with 5% NaOH solution at a constant temperature of 80°C for 2 hours, and the steel slag is ground to a specific surface area of ​​≥450m² / kg and a 28-day activity index of ≥75%.

3. The green manufacturing and recycling process of precast concrete bridge components according to claim 1 is characterized in that: In the green processing step of the raw materials, the solid waste is first coarsely crushed by a jaw crusher, then finely ground by a ball mill to a particle size of ≤5mm, and then mixed with cement in a high-powered mixer at a mass ratio of 1:1 to 1:1.5 to form a mineral admixture. The proportion of the mineral admixture replacing cement is 20% to 30%.

4. The green manufacturing and recycling process of precast concrete bridge components according to claim 1 is characterized in that: In the dust separation and reuse step, the environmentally friendly building materials include permeable bricks and curbstones. The collection efficiency of the pulse bag dust collector of the mixing equipment is ≥95%, the pulse bag dust collector is integrated with a wet electrostatic dust removal module, the PM2.5 emission concentration is ≤10mg / m³, and the air separation device separates fine powder with a particle size of ≤50μm and CaO ≥30% at a wind speed of 10-15m / s. After resin purification, the fine powder is mixed back into concrete at 15%-20%. The non-recyclable dust is added with 3% nano-SiO2 and pressed into lightweight permeable bricks with a compressive strength of ≥8MPa.

5. The green manufacturing and recycling process of precast concrete bridge components according to claim 1 is characterized in that: The wastewater treatment and reuse step specifically includes: The cleaning area is equipped with a 3° to 5° slope diversion trough connected to a sedimentation tank with an effective volume of ≥1m³, and the wastewater sedimentation time is ≥30 minutes; The effluent is filtered through a 100-mesh filter and then transported by a centrifugal pump to the recycled aggregate washing section; The sedimentation tank sludge is discharged into the solid waste crushing process in the green processing step of the raw materials.

6. The green manufacturing and recycling process for precast concrete bridge components according to claim 1 is characterized in that: In the bridge component recycling step, the ultrasonic detection positioning accuracy is ±2mm, the hydraulic scissor blade pressure is set to 200-300MPa, the laser cutting power is 4-6kW, and the incision width is ≤1mm.

7. The green manufacturing and recycling process for precast concrete bridge components according to claim 1 is characterized in that: In the recycled material processing step, the concrete block is first crushed by a jaw crusher and then crushed by an impact crusher to be processed into 5-20 mm recycled aggregate with a mud content of ≤1%. The steel bars are rust-removed by shot blasting with a shot blasting pressure of 0.3-0.5 MPa and a surface roughness of Ra ≥ 20 μm. The straightening is performed by a CNC straightening machine with a straightening accuracy of ≤ ± 1 mm.

8. The green manufacturing and recycling process for precast concrete bridge components according to claim 1 is characterized in that: In the recycling material processing step, metal parts are sorted by material using a spectrometer, and plastic products are crushed by a twin-screw crusher, with the particle size controlled to be 3 to 5 mm.

9. The green manufacturing and recycling process for precast concrete bridge components according to claim 1 is characterized in that: In the material recycling step, 0.02% polycarboxylate water reducer and 1.5% steel fiber are added to the recycled aggregate, and the water absorption rate is ≤3% after CO2 mineralization curing.

10. The green manufacturing and recycling process of precast concrete bridge components according to claim 1, characterized in that: In the material recycling step, the plastic particles are modified by adding 5% nano-calcium carbonate by mass when used to prepare the isolation pads.

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