Solid waste-based uhpc power components and green preparation method thereof

Abstract

The application discloses a solid waste-based UHPC electric power component, raw materials of which comprise the following components in parts by weight: cement 350-450 parts, fly ash 150-250 parts, slag powder 120-200 parts, machine-made sand tailings 80-150 parts, quartz sand 500-650 parts, steel fiber 60-100 parts, water reducing agent 8-15 parts, and water 145-165 parts; the cement has a median particle size D50 of 20-50 mu m, the fly ash has a median particle size D50 of 10-20 mu m, the slag powder has a median particle size D50 of 10-20 mu m, the machine-made sand tailings have a median particle size D50 of less than or equal to 10 mu m, and the median particle size of the cement is greater than that of the fly ash and the slag powder, and the median particle size of the fly ash and the slag powder is greater than that of the machine-made sand tailings; the micro-fine interspaces between fly ash and slag powder particles are filled with machine-made sand tailings, the larger interspaces between cement particles are filled with fly ash and slag powder, and the cement, fly ash, slag powder and machine-made sand tailings form a three-level particle grading system, thereby reducing the porosity of the powder accumulation system.

Description

Technical Field

[0001] This invention belongs to the field of power component technology, and particularly relates to solid waste-based UHPC power components and their green manufacturing methods. Background Technology

[0002] Ultra-high performance concrete (UHPC) uses up to 800-1000 kg / m³ of cement. 3 This leads to persistently high costs and carbon emissions. To reduce cement usage, researchers have attempted to replace some cement with industrial solid wastes such as fly ash and slag powder. However, due to factors such as the low activity and slow early strength development of solid wastes, when the cement replacement rate exceeds 30%, the compressive strength of UHPC is difficult to maintain above 120 MPa, indicating a contradiction between high utilization of solid wastes and maintaining ultra-high strength.

[0003] Furthermore, the production of manufactured sand generates a large amount of stone powder tailings, which are currently mainly disposed of through stockpiling, resulting in extremely low resource utilization. Due to its high water demand and low activity, it is generally regarded by those skilled in the art as a negative component that degrades the performance of concrete, and is only used in small quantities in ordinary mortar. On the other hand, when using fly ash and slag powder to replace cement, because the particle size of fly ash and slag powder is similar, a large number of unfilled micro-voids exist after stacking, resulting in insufficient system density and limiting further improvement in the cement substitution rate. Summary of the Invention

[0004] To address the problems in the prior art, the present invention proposes the following technical solution: This invention provides a solid waste-based UHPC power component, the raw materials of which, by weight, comprise the following components: 350-450 parts cement, 150-250 parts fly ash, 120-200 parts slag powder, 80-150 parts manufactured sand tailings, 500-650 parts quartz sand, 60-100 parts steel fiber, 8-15 parts water-reducing agent, and 145-165 parts water; The median particle size D50 of the cement is 20μm~50μm, the median particle size D50 of the fly ash is 10μm~20μm, the median particle size D50 of the slag powder is 10μm~20μm, and the median particle size D50 of the manufactured sand tailings is ≤10μm. Furthermore, the median particle size of the cement is greater than the median particle size of the fly ash and slag powder, and the median particle size of the fly ash and slag powder is greater than the median particle size of the manufactured sand tailings. The fine voids between fly ash and slag powder particles are filled by manufactured sand tailings, while the larger voids between cement particles are filled by fly ash and slag powder. Cement, fly ash, slag powder and manufactured sand tailings form a three-level particle size distribution system, reducing the porosity of the powder packing system.

[0005] As a preferred embodiment of the above technical solution, the fly ash has a sieve residue of 1%~12% on a 45μm square hole sieve and a loss on ignition of 1%~5%; the slag powder has a specific surface area of ​​400㎡ / kg~600㎡ / kg.

[0006] As a preferred embodiment of the above technical solution, the manufactured sand tailings are dust tailings with a particle size ≤75μm collected during the manufactured sand production process, with a SiO2 content of 50%~68% and a water requirement ratio of 108%~115%.

[0007] As a preferred embodiment of the above technical solution, the steel fiber is copper-plated steel fiber or straight steel fiber, with a length of 10mm~15mm, a diameter of 0.15mm~0.25mm, and a tensile strength of 2600MPa~3000MPa.

[0008] This invention also provides a green manufacturing method for solid waste-based UHPC power components, comprising the following steps: S1. Preparation of activated mixed powder: Fly ash, slag powder and manufactured sand tailings are mixed in proportion, and a composite activator is added for grinding and activation. The mixture is ground until particles with a diameter ≤5μm account for 25%~40% of the total volume to obtain activated mixed powder. S2. Dry mixing: Dry mix the cement and the obtained activated powder for 1 to 2 minutes until uniform to obtain a dry mixture. S3. Adding sand and mixing: Add quartz sand to the obtained dry mixture and continue to dry mix for 1 to 2 minutes until uniform to obtain sand mixture; S4. Adding liquid and mixing: After the water-reducing agent is mixed evenly with water, add it to the obtained sand mixture and mix for 3 to 5 minutes to obtain a wet-mixed mixture. S5. Fiber dispersion: Add steel fibers to the obtained wet mixture and continue stirring for 2 to 3 minutes until the fibers are evenly dispersed to obtain UHPC mixture; S6. Molding and curing: After the obtained UHPC mixture is cast into a mold, it is steam cured to obtain solid waste-based UHPC power components.

[0009] As a preferred embodiment of the above technical solution, in step S1, the composite activator is composed of NaOH and Na2SiO3 in a mass ratio of 1:(1.5~2.0), and the amount added is 2%~3% of the total mass of fly ash, slag powder and manufactured sand tailings.

[0010] As a preferred embodiment of the above technical solution, in step S1, the grinding and activation is performed by using a planetary ball mill at a speed of 300 rpm to 450 rpm for 15 min to 30 min, and the material temperature is controlled at 50℃ to 70℃ during the grinding process.

[0011] As a preferred embodiment of the above technical solution, in step S6, the steam curing includes a static stop stage, a heating stage, a constant temperature stage, and a cooling stage performed sequentially.

[0012] As a preferred embodiment of the above technical solution, in step S6, the temperature of the static stopping stage is 20℃~30℃, and the static stopping time is 2h~4h; the heating stage heats up to 75℃~85℃ at a rate of 10℃ / h~15℃ / h; the temperature of the constant temperature stage is 75℃~85℃, and the constant temperature time is 48h~72h; the cooling stage cools down to room temperature at a rate of 10℃ / h~15℃ / h.

[0013] The beneficial effects of this invention are as follows: (1) This invention utilizes the ultrafine characteristics of manufactured sand tailings and introduces them as functional ultrafine filler components into UHPC. Together with cement, fly ash, and slag powder, they form a three-level particle size distribution system (cement is the first level, fly ash and slag powder are the second level, and manufactured sand tailings are the third level). The manufactured sand tailings fill the micro-voids between fly ash and slag powder particles, reducing the porosity of the powder. Thus, even with high dosage of fly ash and slag powder replacing cement, the ultra-high strength of UHPC can still be guaranteed. At the same time, the originally low-value stockpiled manufactured sand tailings are transformed into functional components in UHPC, significantly reducing carbon emissions. This achieves the synergistic improvement of solid waste resource utilization, ultra-high strength, and low carbon emissions.

[0014] (2) In the preparation process, the three solid waste particles are further refined by grinding and activating fly ash, slag powder and manufactured sand tailings. At the same time, the alkaline activation effect of the composite activator promotes the dissolution of the glass phase in fly ash and the calcium silicate phase in slag, and releases active silica-alumina components to participate in the secondary hydration reaction, generating hydrated calcium silicate gel and hydrated calcium aluminate gel to fill the micropores, further compensating for the strength loss caused by the reduction of cement.

[0015] (3) The present invention uses a feeding method of pre-mixing, grinding and activating fly ash, slag powder and manufactured sand tailings before adding cement, so that the manufactured sand tailings are fully dispersed and evenly coated on the surface of fly ash and slag powder particles during the mixing process, ensuring that they are evenly distributed in space and arranged in a micro-ordered manner of step-by-step filling, avoiding the problems of agglomeration and uneven dispersion caused by separate feeding, thereby giving full play to the dense packing effect of the three-level particle gradation system. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments.

[0017] In this invention, cement particles (median particle size D50 of 20μm~50μm, the coarsest) form the skeleton, while fly ash and slag powder particles (median particle size D50 of 10μm~20μm, the next finest) fill the larger voids between the cement particles. Manufactured sand tailings (median particle size D50 ≤10μm, the finest) further fill the micro-voids between the fly ash and slag powder particles, forming a three-stage progressive filling structure of "coarse → medium → fine". This structure significantly reduces the packing porosity of the powder, increases the contact points between particles, and at the same water-cement ratio, reduces the water demand of the system, thins the free water film layer, reduces capillary pores after hardening, and makes the structure more compact, thus maintaining ultra-high strength while reducing cement usage.

[0018] In step S1 of this invention, fly ash, slag powder, and manufactured sand tailings are ground and activated, and a composite activator composed of NaOH and Na2SiO3 is added. On one hand, the high-speed grinding action of the planetary ball mill further refines the particles of fly ash, slag powder, and manufactured sand tailings, increasing their specific surface area. This results in lattice distortion and defects on the particle surface, breaking Si-O and Al-O bonds, and significantly increasing the dissolution rate of active SiO2 and Al2O3, providing more active sites for subsequent secondary hydration reactions. On the other hand, the composite activator composed of NaOH and Na2SiO3 provides a high-pH alkaline environment, allowing the glassy phase in fly ash, the calcium silicate phase in slag powder, and the residual silica components in manufactured sand tailings to react with the OH-. - Under the influence of this action, dissolution is accelerated, releasing soluble Si. 4+ And Al 3+ The released active silica-alumina components react with Ca(OH)2 in the system to generate hydrated calcium silicate (CSH) gel and hydrated calcium aluminate (CAH) gel. These secondary hydration products fill the micropores between particles, making the hardened body structure more compact and effectively compensating for the later strength loss caused by the reduction of cement.

[0019] Fly ash, slag powder, and manufactured sand tailings exhibit complementary functions in terms of chemical composition and the timing of their activity. Slag powder, with its higher CaO content, exhibits superior early-stage activity compared to fly ash, allowing it to rapidly participate in the hydration reaction during the initial curing period and contribute to early strength. Fly ash, with its higher SiO2 and Al2O3 content, allows for pozzolanic reaction primarily to occur in the middle and later stages, contributing to later-stage strength growth. The residual silica in manufactured sand tailings participates in secondary hydration under alkali activation, further supplementing the later-stage strength source. This synergistic effect of the three materials ensures a continuous relay of hydration reactions from early to late stages, enabling UHPC to maintain good strength development throughout its entire lifespan.

[0020] Example 1

[0021] This embodiment provides a solid waste-based UHPC power component, the raw materials of which, by weight, include: 400 parts cement, 200 parts fly ash, 160 parts slag powder, 120 parts manufactured sand tailings, 580 parts quartz sand, 80 parts steel fiber, 12 parts water-reducing agent, and 155 parts water.

[0022] In this embodiment, the cement is P·O The following materials are used: 52.5 grade ordinary Portland cement with a median particle size D50 of 35 μm; fly ash with a 45 μm square hole sieve residue of 6%, loss on ignition of 3%, and median particle size D50 of 15 μm; blast furnace slag powder of S95 grade with a specific surface area of ​​500 m² / kg and median particle size D50 of 15 μm; manufactured sand tailings with a particle size ≤75 μm collected during manufactured sand production, containing 60% SiO2 and 108% water demand, and median particle size D50 of 8 μm; quartz sand with a fineness modulus of 2.4; copper-plated steel fiber with a length of 13 mm, a diameter of 0.20 mm, and a tensile strength of 2800 MPa; polycarboxylate superplasticizer with a water reduction rate of 35%; and a composite activator composed of NaOH and Na2SiO3 in a mass ratio of 1:1.8.

[0023] The green manufacturing method for solid waste-based UHPC power components in this embodiment is as follows: S1. Preparation of activated mixed powder: 200 parts of fly ash, 160 parts of slag powder, and 120 parts of manufactured sand tailings are mixed in a certain proportion, and a composite activator is added for grinding and activation. The amount of composite activator added is 2.5% of the total mass of fly ash, slag powder, and manufactured sand tailings. A planetary ball mill is used to ball mill at a speed of 380 rpm for 22 minutes. The material temperature is controlled at 60℃ during the grinding process. Grinding is carried out until particles with a particle size ≤5μm account for 32% of the total volume of the mixture, thus obtaining the activated mixed powder.

[0024] S2. Dry mixing: Add 400 parts of cement and the activated mixed powder obtained in step S1 to a forced mixer and dry mix for 1.5 minutes until uniform to obtain a dry mixed material.

[0025] S3. Adding sand and mixing: Add 580 parts of quartz sand to the dry mixture obtained in step S2, and continue to dry mix for 1.5 minutes until uniform to obtain sand mixture.

[0026] S4. Add liquid and mix: Mix 12 parts of water-reducing agent with 155 parts of water evenly and add it to the sand mixture obtained in step S3. Mix for 4 minutes to obtain a wet-mixed mixture.

[0027] S5. Fiber dispersion: Evenly sprinkle 80 parts of steel fiber into the wet mixture obtained in step S4, and continue stirring for 2.5 minutes until the fiber is evenly dispersed to obtain UHPC mixture.

[0028] S6. Molding and Curing: The UHPC mixture obtained in step S5 is poured into a power component mold, vibrated and shaped, and then steam cured. Steam curing includes a static stop stage, a heating stage, a constant temperature stage, and a cooling stage performed sequentially. The static stop stage has a temperature of 25℃ and a static stop time of 3 hours; the heating stage raises the temperature to 80℃ at a rate of 12℃ / h; the constant temperature stage maintains the temperature at 80℃ for 60 hours; and the cooling stage lowers the temperature to room temperature at a rate of 12℃ / h, thus obtaining the solid waste-based UHPC power component.

[0029] Example 2

[0030] This embodiment provides a solid waste-based UHPC power component, the raw materials of which include, by weight, 350 parts cement, 250 parts fly ash, 120 parts slag powder, 150 parts manufactured sand tailings, 500 parts quartz sand, 100 parts steel fiber, 8 parts water-reducing agent, and 165 parts water.

[0031] In this embodiment, the cement is P·O The following materials are used: 52.5 grade ordinary Portland cement with a median particle size D50 of 50 μm; fly ash with a 12% residue on a 45 μm square-hole sieve, a 1% loss on ignition, and a median particle size D50 of 20 μm; S95 grade granulated blast furnace slag powder with a specific surface area of ​​600 m² / kg and a median particle size D50 of 10 μm; manufactured sand tailings with a particle size ≤75 μm collected during manufactured sand production, containing 50% SiO2 and a water requirement ratio of 115%, and a median particle size D50 of 10 μm; quartz sand with a fineness modulus of 2.0; straight steel fibers with a length of 10 mm, a diameter of 0.25 mm, and a tensile strength of 2600 MPa; a polycarboxylate-based high-efficiency water-reducing agent with a water reduction rate of 30%; and a composite activator composed of NaOH and Na2SiO3 in a mass ratio of 1:1.5.

[0032] The green manufacturing method for solid waste-based UHPC power components in this embodiment is as follows: S1. Preparation of activated mixed powder: 250 parts of fly ash, 120 parts of slag powder, and 150 parts of manufactured sand tailings are mixed in a certain proportion, and a composite activator is added for grinding and activation. The amount of composite activator added is 3.0% of the total mass of fly ash, slag powder, and manufactured sand tailings. A planetary ball mill is used to ball mill at a speed of 450 rpm for 15 minutes. The material temperature is controlled at 70℃ during the grinding process. Grinding is carried out until particles with a particle size ≤5μm account for 40% of the total volume of the mixture, thus obtaining the activated mixed powder.

[0033] S2. Dry mixing: Add 350 parts of cement and the activated mixed powder obtained in step S1 to a forced mixer and dry mix for 2 minutes until uniform to obtain a dry mixed material.

[0034] S3. Adding sand and mixing: Add 500 parts of quartz sand to the dry mixture obtained in step S2, and continue to dry mix for 2 minutes until uniform to obtain sand mixture.

[0035] S4. Add liquid and mix: Mix 8 parts of water-reducing agent with 165 parts of water evenly and add it to the sand mixture obtained in step S3. Mix for 3 minutes to obtain a wet-mixed mixture.

[0036] S5. Fiber dispersion: Evenly sprinkle 100 parts of steel fiber into the wet mixture obtained in step S4, and continue stirring for 3 minutes until the fiber is evenly dispersed to obtain UHPC mixture.

[0037] S6. Molding and Curing: The UHPC mixture obtained in step S5 is poured into a power component mold, vibrated and shaped, and then steam cured. Steam curing includes a static stop stage, a heating stage, a constant temperature stage, and a cooling stage performed sequentially. The static stop stage has a temperature of 30℃ and a static stop time of 2 hours; the heating stage raises the temperature to 75℃ at a rate of 15℃ / h; the constant temperature stage maintains the temperature at 75℃ for 72 hours; and the cooling stage lowers the temperature to room temperature at a rate of 15℃ / h, thus obtaining the solid waste-based UHPC power component.

[0038] Example 3

[0039] This embodiment provides a solid waste-based UHPC power component, the raw materials of which include, by weight: 450 parts cement, 150 parts fly ash, 200 parts slag powder, 80 parts manufactured sand tailings, 650 parts quartz sand, 60 parts steel fiber, 15 parts water-reducing agent, and 145 parts water.

[0040] In this embodiment, the cement is P·O 52.5 grade ordinary Portland cement with a median particle size D50 of 20 μm; the fly ash has a 1% residue on a 45 μm square-hole sieve, a loss on ignition of 5%, and a median particle size D50 of 10 μm; the slag powder is S95 grade granulated blast furnace slag powder with a specific surface area of ​​400 m² / kg and a median particle size D50 of 20 μm; the manufactured sand tailings are dust tailings with a particle size ≤75 μm collected during the manufactured sand production process, with a SiO2 content of 68%, a water demand ratio of 112%, and a median particle size D50 of 6 μm; the fineness modulus of the quartz sand is 2.8; the steel fiber is copper-plated steel fiber with a length of 15 mm, a diameter of 0.15 mm, and a tensile strength of 3000 MPa; the water-reducing agent is a polycarboxylate-based high-efficiency water-reducing agent with a water reduction rate of 40%; and the composite activator is composed of NaOH and Na2SiO3 in a mass ratio of 1:2.

[0041] The green manufacturing method for solid waste-based UHPC power components in this embodiment is as follows: S1. Preparation of activated mixed powder: 150 parts of fly ash, 200 parts of slag powder, and 80 parts of manufactured sand tailings are mixed in a certain proportion. A composite activator is added for grinding and activation. The amount of the composite activator added is 2.0% of the total mass of fly ash, slag powder, and manufactured sand tailings. A planetary ball mill is used to ball mill at a speed of 300 rpm for 30 minutes. The material temperature is controlled at 50℃ during the grinding process. Grinding is carried out until particles with a particle size ≤5μm account for 25% of the total volume of the mixture, thus obtaining the activated mixed powder.

[0042] S2. Dry mixing: Add 450 parts of cement and the activated mixed powder obtained in step S1 to a forced mixer and dry mix for 1 minute until uniform to obtain a dry mixed material.

[0043] S3. Adding sand and mixing: Add 650 parts of quartz sand to the dry mixture obtained in step S2, and continue to dry mix for 1 minute until uniform to obtain sand mixture.

[0044] S4. Add liquid and mix: Mix 15 parts of water-reducing agent with 145 parts of water evenly and add it to the sand mixture obtained in step S3. Mix for 5 minutes to obtain a wet-mixed mixture.

[0045] S5. Fiber dispersion: Evenly sprinkle 60 parts of steel fiber into the wet mixture obtained in step S4, and continue stirring for 2 minutes until the fiber is evenly dispersed to obtain UHPC mixture.

[0046] S6. Molding and Curing: The UHPC mixture obtained in step S5 is poured into a power component mold, vibrated and shaped, and then steam cured. Steam curing includes a static stop stage, a heating stage, a constant temperature stage, and a cooling stage performed sequentially. The static stop stage has a temperature of 20℃ and a static stop time of 4 hours; the heating stage raises the temperature to 85℃ at a rate of 10℃ / h; the constant temperature stage maintains the temperature at 85℃ for 48 hours; and the cooling stage lowers the temperature to room temperature at a rate of 10℃ / h, thus obtaining the solid waste-based UHPC power component.

[0047] Example 4

[0048] This embodiment provides a solid waste-based UHPC power component, the raw materials of which include, by weight, 380 parts cement, 180 parts fly ash, 190 parts slag powder, 100 parts manufactured sand tailings, 620 parts quartz sand, 70 parts steel fiber, 10 parts water-reducing agent, and 150 parts water.

[0049] In this embodiment, the cement is P·O The following materials are used: 52.5 grade ordinary Portland cement with a median particle size D50 of 30 μm; fly ash with a 45 μm square hole sieve residue of 8%, loss on ignition of 2%, and median particle size D50 of 15 μm; blast furnace slag powder of S95 grade with a specific surface area of ​​550 m² / kg and median particle size D50 of 12 μm; manufactured sand tailings with a particle size ≤75 μm collected during manufactured sand production, containing 55% SiO2 and a water requirement ratio of 110%, and a median particle size D50 of 7 μm; quartz sand with a fineness modulus of 2.6; straight steel fibers with a length of 12 mm, a diameter of 0.18 mm, and a tensile strength of 2700 MPa; a polycarboxylate-based high-efficiency water-reducing agent with a water reduction rate of 33%; and a composite activator composed of NaOH and Na2SiO3 in a mass ratio of 1:1.6.

[0050] The green manufacturing method for solid waste-based UHPC power components in this embodiment is as follows: S1. Preparation of activated mixed powder: 180 parts of fly ash, 190 parts of slag powder, and 100 parts of manufactured sand tailings are mixed in a certain proportion, and a composite activator is added for grinding and activation. The amount of composite activator added is 2.8% of the total mass of fly ash, slag powder, and manufactured sand tailings. A planetary ball mill is used to ball mill at a speed of 350 rpm for 20 minutes. The material temperature is controlled at 55℃ during the grinding process. Grinding is carried out until particles with a particle size ≤5μm account for 30% of the total volume of the mixture, thus obtaining the activated mixed powder.

[0051] S2. Dry mixing: Add 380 parts of cement and the activated mixed powder obtained in step S1 to a forced mixer and dry mix for 1.5 minutes until uniform to obtain a dry mixed material.

[0052] S3. Adding sand and mixing: Add 620 parts of quartz sand to the dry mixture obtained in step S2, and continue to dry mix for 1.5 minutes until uniform to obtain sand mixture.

[0053] S4. Add liquid and mix: Mix 10 parts of water-reducing agent with 150 parts of water evenly and add it to the sand mixture obtained in step S3. Mix for 4 minutes to obtain a wet-mixed mixture.

[0054] S5. Fiber dispersion: Evenly sprinkle 70 parts of steel fiber into the wet mixture obtained in step S4, and continue stirring for 2.5 minutes until the fiber is evenly dispersed to obtain UHPC mixture.

[0055] S6. Molding and Curing: The UHPC mixture obtained in step S5 is poured into a power component mold, vibrated and shaped, and then steam cured. Steam curing includes a static stop stage, a heating stage, a constant temperature stage, and a cooling stage performed sequentially. The static stop stage has a temperature of 25℃ and a static stop time of 3 hours; the heating stage raises the temperature to 78℃ at a rate of 13℃ / h; the constant temperature stage maintains the temperature at 78℃ for 55 hours; and the cooling stage lowers the temperature to room temperature at a rate of 13℃ / h, thus obtaining the solid waste-based UHPC power component.

[0056] Comparative Example 1 The raw materials for this comparative example, by weight, include: 400 parts cement, 320 parts fly ash, 160 parts slag powder, 580 parts quartz sand, 80 parts steel fiber, 12 parts water-reducing agent, and 155 parts water. The difference from Example 1 is that no manufactured sand tailings are added, and the amount of fly ash is adjusted to 320 parts; the other raw material types and preparation methods are the same as in Example 1.

[0057] Comparative Example 2 The raw material ratios in this comparative example are the same as those in Example 1. The difference from Example 1 is that in step S1, after mixing fly ash, slag powder and manufactured sand tailings in proportion, no composite activator is added, and no grinding activation treatment is performed. Only simple physical mixing is carried out by stirring at a low speed of 300 rpm for 5 minutes. The rest of the preparation methods are the same as those in Example 1.

[0058] Comparative Example 3 The raw material ratios in this comparative example are the same as in Example 1. The difference from Example 1 is that in step S1, the amount of composite activator added is 1.0% of the total mass of fly ash, slag powder, and manufactured sand tailings. The rest of the preparation methods are the same as in Example 1.

[0059] Comparative Example 4 The raw materials for this comparative example, by weight, include: 400 parts cement, 200 parts fly ash, 160 parts slag powder, 120 parts manufactured sand tailings, 580 parts quartz sand, 80 parts steel fiber, 12 parts water-reducing agent, and 155 parts water.

[0060] The difference from Example 1 is that fly ash, slag powder, and manufactured sand tailings are added to the mixer separately, instead of mixing the three together before adding cement. All other preparation methods are the same as in Example 1.

[0061] The solid waste-based UHPC power components prepared in Examples 1 to 4 and Comparative Examples 1 to 4 were subjected to performance testing. The testing items and methods are as follows: Powder packing porosity: Referring to GB / T 208-2014 "Method for Determination of Cement Density", the compacted bulk density and true density of the mixed powders of cement, fly ash, slag powder and manufactured sand tailings in each example and comparative example were measured respectively, and the powder packing porosity was calculated according to the following formula: Powder packing porosity = (1 - tapped packing density / true density) × 100% Compressive strength: Tested in accordance with the provisions of GB / T 31387-2015 "Reactive Powder Concrete", with specimen size of 100mm×100mm×100mm, test age of 28d, and loading rate of 1.2MPa / s~1.4MPa / s.

[0062] Carbon emission calculation: Refer to GB / T 51366-2019 "Standard for Carbon Emission Calculation of Buildings" to calculate the carbon emissions of each cubic meter of UHPC material throughout its entire life cycle (raw material mining and processing, transportation, and mixing production).

[0063] The carbon emission reduction rate is calculated using the following formula: Carbon emission reduction rate = (Carbon emissions of conventional UHPC - Carbon emissions of the present invention UHPC) / Carbon emissions of conventional UHPC × 100% The traditional UHPC mix proportion is: 950 parts cement, 200 parts silica fume, 1100 parts quartz sand, 80 parts steel fiber, 20 parts water-reducing agent, and 180 parts water, with a water-cement ratio of 0.18, which is a typical UHPC basic mix proportion in publicly available industry literature.

[0064]

[0065] Table 1 Note: The raw material ratios of Comparative Examples 2, 3 and 4 are the same as those of Example 1. The carbon emission calculation is mainly based on the raw material acquisition and processing stage. The carbon emission in this stage depends on the type and amount of raw materials and is not related to the process parameters. Therefore, the carbon emission reduction rate of the above comparative examples is the same as that of Example 1.

[0066] As shown in Table 1, the packing void ratio of the powder in each embodiment was significantly lower than that in the comparative examples, and the 28-day compressive strength increased with the decrease in packing void ratio. This indicates that the construction of the three-level particle size distribution system effectively reduced the packing void ratio, thereby ensuring the ultra-high strength of UHPC under high solid waste content conditions. Comparative Example 1 did not add manufactured sand tailings, and Comparative Example 4 did not premix to form a three-level distribution. Their packing void ratios both exceeded 40%, and their compressive strengths were both below 100 MPa. This confirms that the use of manufactured sand tailings as an ultrafine filler component and the integrity of the three-level particle size distribution system are key to ensuring mechanical properties. Comparative Example 2 did not undergo grinding and activation treatment, and Comparative Example 3 had insufficient activator dosage. Their packing void ratios and compressive strengths were between those of the embodiments and Comparative Example 1. This further verifies that the synergistic effect of grinding and activation treatment and composite activator is an important guarantee for achieving particle refinement and chemical reinforcement, and fully utilizing the effect of the three-level distribution.

[0067] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it.

Claims

1. A solid waste-based UHPC power component, characterized in that, Its raw materials, by weight, include the following components: 350-450 parts cement, 150-250 parts fly ash, 120-200 parts slag powder, 80-150 parts manufactured sand tailings, 500-650 parts quartz sand, 60-100 parts steel fiber, 8-15 parts water-reducing agent, and 145-165 parts water; The median particle size D50 of the cement is 20μm~50μm, the median particle size D50 of the fly ash is 10μm~20μm, the median particle size D50 of the slag powder is 10μm~20μm, and the median particle size D50 of the manufactured sand tailings is ≤10μm. Furthermore, the median particle size of the cement is greater than the median particle size of the fly ash and slag powder, and the median particle size of the fly ash and slag powder is greater than the median particle size of the manufactured sand tailings. The fine voids between fly ash and slag powder particles are filled by manufactured sand tailings, while the larger voids between cement particles are filled by fly ash and slag powder. Cement, fly ash, slag powder and manufactured sand tailings form a three-level particle size distribution system, reducing the porosity of the powder packing system.

2. The solid waste-based UHPC power component according to claim 1, characterized in that, The fly ash has a sieve residue of 1% to 12% on a 45μm square mesh sieve and a loss on ignition of 1% to 5%; the slag powder has a specific surface area of ​​400㎡ / kg to 600㎡ / kg.

3. The solid waste-based UHPC power component according to claim 1, characterized in that, The manufactured sand tailings are dust tailings with a particle size ≤75μm collected during the manufactured sand production process, with a SiO2 content of 50%~68% and a water requirement ratio of 108%~115%.

4. The solid waste-based UHPC power component according to claim 1, characterized in that, The steel fiber is copper-plated steel fiber or straight steel fiber, with a length of 10mm~15mm, a diameter of 0.15mm~0.25mm, and a tensile strength of 2600MPa~3000MPa.

5. A green manufacturing method for solid waste-based UHPC power components, characterized in that, Includes the following steps: S1. Preparation of activated mixed powder: Fly ash, slag powder and manufactured sand tailings are mixed in proportion, and a composite activator is added for grinding and activation. The mixture is ground until particles with a diameter ≤5μm account for 25%~40% of the total volume to obtain activated mixed powder. S2. Dry mixing: Dry mix the cement and the obtained activated powder for 1 to 2 minutes until uniform to obtain a dry mixture. S3. Adding sand and mixing: Add quartz sand to the obtained dry mixture and continue to dry mix for 1 to 2 minutes until uniform to obtain sand mixture; S4. Adding liquid and mixing: After the water-reducing agent is mixed with water evenly, add it to the obtained sand mixture and mix for 3 to 5 minutes to obtain a wet-mixed mixture. S5. Fiber dispersion: Add steel fibers to the obtained wet mixture and continue stirring for 2 to 3 minutes until the fibers are evenly dispersed to obtain UHPC mixture; S6. Molding and curing: After the obtained UHPC mixture is cast into a mold, it is steam cured to obtain solid waste-based UHPC power components.

6. The green manufacturing method for solid waste-based UHPC power components according to claim 5, characterized in that, In step S1, the composite activator is composed of NaOH and Na2SiO3 in a mass ratio of 1:(1.5~2.0), and the amount added is 2%~3% of the total mass of fly ash, slag powder and manufactured sand tailings.

7. The green manufacturing method for solid waste-based UHPC power components according to claim 5, characterized in that, In step S1, the grinding and activation process involves using a planetary ball mill at a speed of 300 rpm to 450 rpm for 15 min to 30 min, with the material temperature controlled at 50℃ to 70℃ during the grinding process.

8. The green manufacturing method for solid waste-based UHPC power components according to claim 5, characterized in that, In step S6, the steam curing includes a static stop stage, a heating stage, a constant temperature stage, and a cooling stage performed sequentially.

9. The green manufacturing method for solid waste-based UHPC power components according to claim 8, characterized in that, In step S6, the temperature during the static rest phase is 20℃~30℃, and the static rest time is 2h~4h; the temperature rise phase increases to 75℃~85℃ at a rate of 10℃ / h~15℃ / h; the temperature during the constant temperature phase is 75℃~85℃, and the constant temperature time is 48h~72h; the temperature drop phase decreases to room temperature at a rate of 10℃ / h~15℃ / h.

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