Multi-element solid waste treatment method and process for preparing self-compacting low-carbon ultra-high performance concrete by using multi-element solid waste treatment method

Abstract

The invention relates to a multi-element solid waste treatment method and a process for preparing self-compacting low-carbon ultra-high performance concrete by using the multi-element solid waste treatment method, and a self-compacting low-carbon ultra-high performance concrete system is constructed by using a multi-element solid waste synergistic utilization and material modification technology. The distribution of solid wastes with different particle sizes is accurately regulated and controlled by adopting a particle grading optimization model, and performance improvement is realized by combining multi-dimensional material activation and modification. A three-step modification process of high-temperature carbonization pore-forming, acid pickling activation and silane coupling is carried out on the superfine fly ash to form the admixture with both activity and interface enhancement effect; and an electrochemical stripping and microbial mineralization synergistic activation technology is innovatively adopted for the lithium slag, so that the potential activity is effectively excited. The fiber surface is modified through plasma etching and chemical grafting, a multi-scale hybrid fiber reinforcement is prepared in cooperation with an in-situ composite spinning technology, the material toughness is remarkably improved, meanwhile, the problems that ultra-high performance concrete is high in raw material cost, large in carbon emission and large in shrinkage are solved, and therefore the self-compacting low-carbon ultra-high performance concrete is obtained.

Description

Technical Field

[0001] This invention belongs to the field of building materials technology, specifically relating to a method for the disposal of multi-component solid waste and a process for preparing self-compacting low-carbon ultra-high-performance concrete, applicable to building structures, precast components and the resource utilization of solid waste. Background Technology

[0002] Ultra-high performance concrete (UHPC) is characterized by high strength, high durability, and high toughness. When used in structures, it can significantly reduce structural dimensions and extend structural lifespan, and is also more carbon-efficient than ordinary reinforced concrete structures. However, the preparation of UHPC consumes a large amount of cement due to its extremely low water-cement ratio and the fact that much of the cement does not participate in the hydration reaction. Typically, the cement content in UHPC is 800-1000 kg / m³. 3 It has more than three times the heat of hydration of ordinary concrete, and a high heat of hydration and shrinkage rate. Due to its extremely low water-cement ratio, most cement particles, about 60%-70%, do not hydrate and act as fillers.

[0003] Existing technologies frequently incorporate multi-component solid waste materials into ultra-high performance concrete (UHPC) to replace some of the non-hydrating cement used for filling, thereby reducing costs. However, current technologies lack methods for the proper disposal of these materials, leading to significant shrinkage issues when added to concrete. Furthermore, the substantial carbon emissions of UHPC itself limit its large-scale application. Given the maximum packing density requirements for UHPC formulation, the application of solid waste in UHPC holds great promise.

[0004] Unactivated fly ash and pozzolanic material have low activity and slow early reaction, resulting in low early strength of concrete. Furthermore, the dense glassy structure on the surface of untreated fly ash particles reduces concrete density and strength when directly incorporated. Lithium slag powder particles are mostly irregularly shaped flakes; direct incorporation easily reduces concrete fluidity, increases water demand, and leads to a decline in concrete performance. Added fibers are generally polyester, nylon, vinylon, acrylic, polypropylene, or chlorofiber. Direct addition of fibers can cause them to form clusters due to electrostatic adsorption or mechanical entanglement, resulting in uneven distribution in the concrete and further affecting its performance, failing to achieve the reinforcing and toughening effects of the fibers.

[0005] Therefore, the research focus of this invention is how to specifically modify and process multi-component solid waste to obtain solid waste products that meet the requirements of UHPC formulation, and to prepare self-compacting ultra-high performance concrete in a green and low-carbon manner. Summary of the Invention

[0006] The purpose of this invention is to provide a method for the disposal of multi-component solid waste and a process for preparing self-compacting low-carbon ultra-high performance concrete.

[0007] To solve the above-mentioned technical problems, the specific process of the present invention is as follows:

[0008] The raw materials are: cement, silica fume, active solid waste admixture, inert solid waste filler, aggregate, and fiber;

[0009] Based on the improved Anderson model, to achieve the self-compacting requirement, the distribution modulus is taken as 0.23, where d represents the particle size of the material in the UHPC system, in μm; max d represents the maximum particle size of the material in the UHPC system, in μm; min V represents the minimum particle size of the material in the UHPC system, in μm; d The cumulative volumetric doping amount is denoted by particle size d; according to the formula... Find the range of each particle size, where the particle size is within d. min -1μm is silica fume and active solid waste admixture; 1μm-10μm is active solid waste admixture and inert solid waste filler; 10μm-100μm is cement and inert solid waste filler; 100μm-d max For aggregates, calculate the cumulative volumetric admixture difference, V1-V min V 10 -V1:V 100 -V 10 V dmax -V 100 That is, the initial volume ratio.

[0010] The cement or new low-carbon cementitious material is 52.5 ordinary Portland cement or a new low-carbon cementitious material of equivalent grade 52.5, and has undergone grinding and mixing processes, with a particle size range of 10-100μm and a specific surface area of ​​380-450m². 2 / kg;

[0011] The particle size range of silica fume is 0-1 μm;

[0012] Active solid waste admixture: Ultrafine fly ash and ultrafine lithium slag admixture, processed through ultrafine grinding and sorting, with a particle size range of 1-10μm and a specific surface area of ​​600-800m². 2 / kg;

[0013] Inert solid waste filler: Stone powder and tailings powder are processed through ultrafine grinding and sorting, with a particle size range of 10-100μm and a specific surface area of ​​350-480m². 2 / kg;

[0014] Aggregates: construction waste, artificial aggregates, natural aggregates or compound aggregates, of which the fine aggregate size range is 0-5mm and the coarse aggregate size range is 3-8mm, all of which meet the requirements of the Fuller curve.

[0015] The ultrafine fly ash in the activated solid waste admixture also includes the following treatment:

[0016] High-temperature carbonization: Ultrafine fly ash is heated to 800℃ at 10℃ / min in an argon atmosphere and held for 1 hour to generate a porous carbon skeleton.

[0017] Impurity removal and activation: The high-temperature carbonized fly ash was first added to 5% dilute sulfuric acid at a solid-liquid ratio of 1:8, and stirred at 300-500 rpm. The impurities were removed by acid washing at 60-80℃. Then, it was washed with water until the pH reached 6.5-7.5. After drying, 2% Ca(OH)2 that had passed through a 200-mesh sieve was added and dry-mixed at 60-100 rpm. The mixture was then moist-heat cured at 60℃ for 48 hours to activate the activity.

[0018] Silane coupling treatment: Activated fly ash was soaked in a 3% KH550 silane coupling agent ethanol solution at a solid-liquid ratio of 1:5, ultrasonically treated for 1 hour, dried at 60℃, and then ground and sorted to obtain particles ranging from 1-10 μm with a specific surface area of ​​600-800 m². 2 / kg of ultrafine fly ash.

[0019] The ultrafine lithium slag admixture in the activated solid waste admixture also includes the following treatment:

[0020] Electrochemical activation: Lithium slag powder was mixed with 0.5 mol / L sulfuric acid solution at a solid-liquid ratio of 1:3. A current density of 10 mA / cm² was applied in an electrolytic cell using graphite electrodes. 2 The reaction lasted for 2 hours.

[0021] Microbial mineralization: After washing the activated lithium slag powder 2-3 times with water, add it to 9K culture medium at a solid-liquid ratio of 1:5, and add *Thiobacillus acidophilus* at a concentration of 10. 8 CFU / mL, temperature 30-35℃, add sulfuric acid to adjust pH to 2.0-2.5, shake and incubate for 48h at a shaking rate of 150-200 rpm;

[0022] Low-temperature calcination: The lithium slag powder after microbial mineralization was filtered, dried, and calcined at 300℃ for 1 hour, followed by grinding and sorting to obtain a particle size range of 1-10 μm and a specific surface area of ​​600-800 m². 2 / kg of ultrafine lithium slag admixture.

[0023] The fiber is a blend of modified polyester, nylon, and chlorofiber.

[0024] The preparation process of the mixed fiber modified with polyester, nylon, and chlorofiber includes:

[0025] Plasma etching: Polyester, nylon, and chlorofiber surfaces are treated with 100W radio frequency power for 10 minutes under an argon atmosphere and a pressure of 50Pa to generate micro-nano-scale rough structures.

[0026] Chemical grafting: The etched fibers are immersed in a 5% acrylic acid solution and reacted at 60°C for 2 hours to introduce carboxylic acid groups;

[0027] Composite process: Prepare a mixed solution of phenol and tetrahydrofuran, wherein the concentration of phenol is 6% and the concentration of tetrahydrofuran is 5%, and mix them at a mass ratio of 2:1 to obtain a mixed solution. Add polyester, nylon, and chlorofiber to the mixed solution at a mass ratio of 3:2:1, and adjust the total concentration of the mixed solution to 8-12wt% to form a spinning solution. Stir at 60℃ for 3-5h, and control the viscosity to 500-1500 mPa·s. Extrude the spinning solution from a syringe and pass it through a high-voltage electric field of 15-20 kV, a receiving distance of 12-28 cm, a flow rate of 1.0-2.0 mL / h, a temperature of 25-30℃, and a humidity of 40-50%. Collect the composite fibers on a collector using a high-speed rotating drum at 800-1500 rpm. Vacuum dry at 60℃ for 12h to obtain mixed fibers with a fiber length of 10-50 mm and a diameter of less than 0.2 mm.

[0028] A process for preparing self-compacting low-carbon ultra-high performance concrete from multi-element solid waste includes the following steps:

[0029] (1) Calculate the initial weight ratio of each solid waste material by designing the initial mix proportion of the multi-component solid waste materials;

[0030] (2) Design the initial mix proportion based on cement, aggregates, etc., calculate the initial weight ratio of each material, and combine it with the initial mix proportion of multi-component solid waste materials to obtain the initial weight ratio of raw materials such as multi-component solid waste materials, cement, and aggregates;

[0031] (3) Based on the fiber content of 0.5-1.5% and the water-reducing agent content of 1.8-2% of the cementitious material, adjust the water-cement ratio or the amount of admixture according to the fluidity to meet the spread ≥700mm;

[0032] (4) Place the substrate at 90℃ for 48 hours for steam curing.

[0033] The process of adjusting the water-cement ratio or the amount of additives based on fluidity is as follows:

[0034] First, using Anderson's close-packed particle model, the gradation between coarse and fine aggregates was calculated, and the mix proportion of UHPC was determined using the volumetric method. Then, the porosity P of the mixed aggregate was determined under the maximum bulk density of the coarse and fine aggregates: P = (1 - ρ b / ρ a )×100%,

[0035] ρb ρ is the bulk density of the mixed aggregate; a To determine the apparent density of the mixed aggregate, the amount of paste V is determined. P =nP: Selecting the slurry surplus coefficient n values ​​of 1.1 and 1.15, determine the total amount of UHPC cementitious material used:

[0036] V P =V w +V b =W w / 1000+W b / ρ

[0037]

[0038] In the formula The water-to-binder ratio is 0.16, 0.18, and 0.2, where... For the quality of cementitious materials, W w For water quality, V w Let ρ be the water volume and ρ be the density of the cementitious material. Substituting these values ​​into the formula will yield the total amount of cementitious material used for different water-cement ratios.

[0039] The beneficial effects of this invention are as follows:

[0040] 1. This invention provides a method for the disposal of multi-component solid waste and the preparation of self-compacting ultra-high performance concrete. The ultra-high performance concrete is prepared by mixing cement or a novel low-carbon cementitious material, active solid waste admixtures, inert solid waste fillers, and / or aggregates, a high-efficiency water-reducing agent, reinforcing and toughening fibers, and water. After steam curing for 48 hours (at 90℃), the compressive strength is ≥150MPa. The multi-component solid waste is general industrial solid waste that meets the requirements for radioactivity and leaching toxicity. It is prepared through one or more processes such as crushing, granulation, screening, grinding, mixing, high-temperature sintering, and surface modification to obtain novel low-carbon cementitious materials, active solid waste admixtures, inert solid waste fillers, and aggregates. This process optimizes aggregate gradation based on the Anderson particle close packing model, combined with low water-cement ratio and high-efficiency water-reducing agent control. While ensuring self-compacting performance with a spread exceeding 700mm, it significantly reduces carbon emissions and resource consumption, solving the problems of high raw material cost, large carbon emissions, and large shrinkage in ultra-high performance concrete (UHPC), thereby obtaining self-compacting low-carbon ultra-high performance concrete.

[0041] 2. Through high-temperature carbonization pore-forming technology, a multi-level porous structure is formed inside the fly ash particles, significantly enhancing their adsorption capacity for moisture and ions, effectively optimizing the internal humidity distribution of concrete, and inhibiting early shrinkage cracking. Acid washing removes iron oxide and unburned carbon impurities from the particle surface, exposing the internal active silica-alumina phase and greatly improving its pozzolanic reaction efficiency. Silane coupling agents construct an organic-inorganic interface transition layer on the particle surface, enhancing the chemical bonding with the cement matrix while imparting hydrophobic properties to the fly ash and reducing capillary permeability. This triple-modified fly ash combines physical filling, chemical activation, and interface strengthening functions, significantly improving matrix density while reducing cement usage, thus enhancing the compressive strength and scalability of concrete.

[0042] 3. Electrochemical stripping technology precisely breaks down the glassy inert outer shell of lithium slag particles, releasing the internal amorphous silicon-aluminum active components, increasing their specific surface area and providing ample contact interfaces for subsequent reactions. Microbial mineralization generates nanoscale calcium carbonate and calcium silicate hydrates in situ on the particle surface, forming active seeds to accelerate the hydration reaction and simultaneously filling the interparticle gaps. Low-temperature calcination regulates the transformation of the mineral phase from a disordered structure to a highly active metastable state, forming a metastable structural network rich in active silicon-aluminum, significantly improving its dissolution rate in alkaline environments.

[0043] 4. The activated lithium slag and fly ash form a gradient reaction synergistic effect, which promotes nucleation in the early stage through nano-mineral phase and continuously releases active components in the later stage, realizing the full-cycle strength growth of the cementitious system and effectively suppressing the risk of temperature cracks in large-volume concrete.

[0044] 5. Fiber composite modification technology significantly enhances the reinforcing performance of polyester, nylon, and chlorofiber fibers in self-compacting low-carbon ultra-high performance concrete through multi-stage synergistic treatment. Plasma etching generates micro- and nano-scale rough structures on the fiber surface, greatly increasing the specific surface area; the carboxylic acid groups introduced by acrylic acid grafting can form coordination bonds with calcium ions in cement hydration products, achieving chemical anchoring. In contrast, untreated fiber surfaces are smooth and inert, relying solely on physical friction bonding, and are prone to debonding and failure under stress; simple cutting or acid washing pretreatment can improve roughness, but lacks directional functional group modification, failing to establish a stable chemical bonding network. The modified fiber interfacial bonding strength is improved, effectively inhibiting crack propagation.

[0045] 6. The synergistic modification process of plasma etching and chemical grafting endows composite fibers with multi-dimensional reinforcement functions. The micro-nano-scale rough surface formed by etching and the chemical anchoring effect of grafted carboxylic acid groups construct a physical-chemical dual-bonding system between the fiber and the matrix, which improves the interfacial bonding strength of the fiber. The three-dimensional network structure of electrospinning optimizes the stress transmission path, which can improve the overall impact resistance and durability of concrete. Detailed Implementation

[0046] The present invention will be further described in detail below with reference to embodiments. The raw materials used include: cement or a new low-carbon cementitious material, specifically 52.5 ordinary Portland cement or a new low-carbon cementitious material of equivalent grade 52.5, which has undergone grinding and mixing processes, resulting in a particle size range of 10-100 μm and a specific surface area of ​​380-450 m². 2 / kg;

[0047] The particle size range of silica fume is 0-1 μm;

[0048] Active solid waste admixture: Ultrafine fly ash and ultrafine lithium slag admixture, processed through ultrafine grinding and sorting, with a particle size range of 1-10μm and a specific surface area of ​​600-800m². 2 / kg;

[0049] Inert solid waste filler: Stone powder and tailings powder are processed through ultrafine grinding and sorting, with a particle size range of 10-100μm and a specific surface area of ​​350-480m². 2 / kg;

[0050] Aggregates: construction waste, artificial aggregates, natural aggregates or compound aggregates, of which the fine aggregate size range is 0-5mm and the coarse aggregate size range is 3-8mm, all of which meet the requirements of the Fuller curve.

[0051] The water-reducing agent used is one or more of lignin sulfonate, naphthalene sulfonate formaldehyde polymer.

[0052] Example 1

[0053] Ultrafine fly ash treatment:

[0054] High-temperature carbonization: Ultrafine fly ash is heated to 800℃ at 10℃ / min in an argon atmosphere and held for 1 hour to generate a porous carbon skeleton.

[0055] Impurity removal and activation: The high-temperature carbonized fly ash was first added to 5% dilute sulfuric acid at a solid-liquid ratio of 1:8, stirred at 400 rpm, and acid washed at 70℃ to remove impurities. Then it was washed with water until the pH reached 7.0, dried, and then 2% Ca(OH)2 passing through a 200-mesh sieve was added and dry-mixed at 80 rpm. It was then moist-heat cured at 60℃ for 48 hours to activate the activity.

[0056] Silane coupling treatment: The activated fly ash was soaked in a 3% KH550 silane coupling agent ethanol solution at a solid-liquid ratio of 1:5, ultrasonically treated for 1 hour, dried at 60℃, and then ground and sorted to obtain particles with a particle size range ≤10μm and a specific surface area of ​​700m². 2 / kg of ultrafine fly ash.

[0057] Treatment of ultrafine lithium slag admixtures:

[0058] Electrochemical activation: Lithium slag powder was mixed with 0.5 mol / L sulfuric acid solution at a solid-liquid ratio of 1:3. A current density of 10 mA / cm² was applied in an electrolytic cell using graphite electrodes. 2 The reaction lasted for 2 hours.

[0059] Microbial mineralization: The activated lithium slag powder was washed three times with water and then added to 9K culture medium at a solid-liquid ratio of 1:5. *Thiobacillus ferrooxidans* was added at a concentration of 10⁻⁶. 8 CFU / mL, temperature 32℃, pH adjusted to 2.3 with sulfuric acid, shaken and incubated for 48h at a shaking rate of 180 rpm;

[0060] Low-temperature calcination: The lithium slag powder after microbial mineralization is filtered, dried, and calcined at 300℃ for 1 hour, followed by grinding and sorting to obtain particles with a particle size range ≤10μm and a specific surface area of ​​600m². 2 / kg of ultrafine lithium slag admixture.

[0061] Example 2

[0062] Ultrafine fly ash treatment:

[0063] High-temperature carbonization: Ultrafine fly ash is heated to 800℃ at 10℃ / min in an argon atmosphere and held for 1 hour to generate a porous carbon skeleton.

[0064] Impurity removal and activation: The high-temperature carbonized fly ash was first added to a 5% dilute sulfuric acid solution at a solid-liquid ratio of 1:8, stirred at 500 rpm, and acid-washed at 60°C to remove impurities. Then it was washed with water until the pH reached 7.5, dried, and then 2% Ca(OH)2 passing through a 200-mesh sieve was added and dry-mixed at 60 rpm. The mixture was then moist-heat cured at 60°C for 48 hours to activate the activity.

[0065] Silane coupling treatment: The activated fly ash was soaked in a 3% KH550 silane coupling agent ethanol solution at a solid-liquid ratio of 1:5, ultrasonically treated for 1 hour, dried at 60℃, and then ground and sorted to obtain particles with a particle size range ≤10μm and a specific surface area of ​​800m². 2 / kg of ultrafine fly ash.

[0066] Treatment of ultrafine lithium slag admixtures:

[0067] Electrochemical activation: Lithium slag powder was mixed with 0.5 mol / L sulfuric acid solution at a solid-liquid ratio of 1:3. A current density of 10 mA / cm² was applied in an electrolytic cell using graphite electrodes. 2 The reaction lasted for 2 hours.

[0068] Microbial mineralization: The activated lithium slag powder was washed three times with water and then added to 9K culture medium at a solid-liquid ratio of 1:5. *Thiobacillus ferrooxidans* was added at a concentration of 10⁻⁶.8 CFU / mL, temperature 30℃, pH adjusted to 2.5 with sulfuric acid, shaken and incubated for 48 h at a shaking rate of 200 rpm;

[0069] Low-temperature calcination: The lithium slag powder after microbial mineralization is filtered, dried, and calcined at 300℃ for 1 hour, followed by grinding and sorting to obtain particles with a particle size range ≤10μm and a specific surface area of ​​600m². 2 / kg of ultrafine lithium slag admixture.

[0070] Example 3

[0071] Ultrafine fly ash treatment:

[0072] High-temperature carbonization: Ultrafine fly ash is heated to 800℃ at 10℃ / min in an argon atmosphere and held for 1 hour to generate a porous carbon skeleton.

[0073] Impurity removal and activation: The high-temperature carbonized fly ash was first added to 5% dilute sulfuric acid at a solid-liquid ratio of 1:8, stirred at 300 rpm, and acid washed at 60-80℃ to remove impurities. Then it was washed with water until the pH reached 6.5, dried, and then 2% Ca(OH)2 passing through a 200-mesh sieve was added and dry mixed at 100 rpm. It was then moist heat cured at 60℃ for 48 hours to activate the activity.

[0074] Silane coupling treatment: Activated fly ash was soaked in a 3% KH550 silane coupling agent ethanol solution at a solid-liquid ratio of 1:5, ultrasonically treated for 1 hour, dried at 60℃, and then ground and sorted to obtain particles ≤10μm with a specific surface area of ​​600m². 2 / kg of ultrafine fly ash.

[0075] Treatment of ultrafine lithium slag admixtures:

[0076] Electrochemical activation: Lithium slag powder was mixed with 0.5 mol / L sulfuric acid solution at a solid-liquid ratio of 1:3. A current density of 10 mA / cm² was applied in an electrolytic cell using graphite electrodes. 2 The reaction lasted for 2 hours.

[0077] Microbial mineralization: The activated lithium slag powder was washed twice with water and then added to 9K culture medium at a solid-liquid ratio of 1:5. *Thiobacillus ferrooxidans* was added at a concentration of 10⁻⁶. 8 CFU / mL, temperature 30-35℃, pH adjusted to 2.0 with sulfuric acid, shaken and incubated for 48h at a shaking rate of 150 rpm;

[0078] Low-temperature calcination: The lithium slag powder after microbial mineralization is filtered, dried, calcined at 300℃ for 1 hour, and then ground and sorted to obtain particles with a particle size range ≤10μm and a specific surface area of ​​600-800m². 2 / kg of ultrafine lithium slag admixture.

[0079] Comparative Example 1

[0080] The difference between this comparative example and Example 1 is that the ultrafine fly ash in this comparative example is treated by grinding and sorting processes to obtain a particle size range ≤10μm and a specific surface area of ​​700m². 2 / kg of ultrafine fly ash; the rest is the same as in Example 1.

[0081] Comparative Example 2

[0082] The difference between this comparative example and Example 1 is that the ultrafine fly ash treatment in this comparative example is as follows: fly ash is first added to 5% dilute sulfuric acid at a solid-liquid ratio of 1:8, stirred at 400 rpm, and acid-washed at 70°C to remove impurities. Then, it is washed with water until the pH reaches 7.0, dried, and then ground and sorted to obtain particles with a particle size range ≤10 μm and a specific surface area of ​​700 m². 2 / kg of ultrafine fly ash; the rest is the same as in Example 1.

[0083] Comparative Example 3

[0084] The difference between this comparative example and Example 1 is that the ultrafine fly ash treatment in this comparative example is: high-temperature carbonization: the ultrafine fly ash is heated to 800°C at 10°C / min in an argon atmosphere and kept at that temperature for 1 hour to generate a porous carbon skeleton.

[0085] Impurity removal and activation: The high-temperature carbonized fly ash was first added to 5% dilute sulfuric acid at a solid-liquid ratio of 1:8, stirred at 400 rpm, and acid-washed at 70℃ to remove impurities. Then, it was washed with water until the pH reached 7.0, dried, and then 2% Ca(OH)₂ (passed through a 200-mesh sieve) was added and dry-mixed at 80 rpm. It was then moist-heat cured at 60℃ for 48 hours to activate the process. After drying, it was ground and sorted to obtain particles ≤10μm with a specific surface area of ​​700m². 2 / kg of ultrafine fly ash; the rest is the same as in Example 1.

[0086] Comparative Example 4

[0087] The difference between this comparative example and Example 1 is that the ultrafine lithium slag admixture in this comparative example is made by directly grinding and sorting the ultrafine lithium slag to obtain a particle size range of ≤10μm and a specific surface area of ​​700m². 2 / kg of ultrafine lithium slag powder.

[0088] Comparative Example 5

[0089] The difference between this comparative example and Example 1 is that the ultrafine lithium slag treatment in this comparative example is as follows: lithium slag powder is mixed with 0.5 mol / L sulfuric acid solution at a solid-liquid ratio of 1:3, and graphite is used as the electrode in an electrolytic cell with a current density of 10 mA / cm².2 The reaction was carried out for 2 hours; after drying, the powder was ground and sorted to obtain particles with a particle size range of ≤10μm and a specific surface area of ​​700m². 2 / kg of ultrafine lithium slag powder; the rest is the same as in Example 1.

[0090] Comparative Example 6

[0091] The difference between this comparative example and Example 1 is that the ultrafine lithium slag treatment in this comparative example is as follows: lithium slag powder is mixed with 0.5 mol / L sulfuric acid solution at a solid-liquid ratio of 1:3, and graphite is used as the electrode in an electrolytic cell with a current density of 10 mA / cm². 2 The reaction was carried out for 2 hours. The activated lithium slag powder was then washed three times with water and added to 9K culture medium at a solid-liquid ratio of 1:5. *Thiobacillus ferrooxidans* was added at a concentration of 10⁻⁶. 8 CFU / mL, temperature 32℃, pH adjusted to 2.3 with sulfuric acid, incubated with shaking for 48 h at a shaking rate of 180 rpm; after washing and drying, the sample was milled and sorted to obtain particles ≤10 μm in size and with a specific surface area of ​​700 m². 2 / kg of ultrafine lithium slag powder; the rest is the same as in Example 1.

[0092] Based on the improved Anderson model, to achieve the self-compacting requirement, the distribution modulus is taken as 0.23, and d represents the particle size of the material in the UHPC system, in μm; d max d represents the maximum particle size of the material in the UHPC system, in μm; min V represents the minimum particle size of the material in the UHPC system, in μm; d This represents the cumulative volumetric doping amount based on particle size d.

[0093] formula,

[0094] The initial mix ratio can be calculated as (V1-Vmin):(V10-V1):(V100-V10):(Vdmax-V100) = 12.6:9:14.9:63.5. Based on the design bulk density of dry powder M = 2200g and the particle size range of each material, the mass ratio of silica fume: ultrafine fly ash / ultrafine lithium slag powder: cement: graded sand is 241:258:438:1263.

[0095] Test 1: The compressive strength test was conducted in accordance with GB / T31387-2015, and the expansion was tested in accordance with GB / T 50080. The proportions and corresponding properties are shown in Table 1 below.

[0096] Table 1

[0097] Group number Silica fume (g) Ultrafine fly ash (g) Ultrafine lithium slag powder (g) Cement (g) Sand (g) Water (g) Water-reducing agent (g) Compressive strength (MPa) Expansion (mm) Example 1 241 258 0 438 1263 169 11.27 122.3 640 Example 2 241 0 258 438 1263 169 11.27 123.6 645 Example 3 241 129 129 438 1263 169 11.27 125.8 650 Comparative Example 1 241 129 129 438 1263 169 11.27 105.8 555 Comparative Example 2 241 129 129 438 1263 169 11.27 109.7 580 Comparative Example 3 241 129 129 438 1263 169 11.27 116.4 620 Comparative Example 4 241 129 129 438 1263 169 11.27 106.2 565 Comparative Example 5 241 129 129 438 1263 169 11.27 112.5 590 Comparative Example 6 241 129 129 438 1263 169 11.27 118.6 630

[0098] Example 4

[0099] The preparation process of blended fibers modified with polyester, nylon, and chlorofiber includes:

[0100] Plasma etching: Polyester, nylon, and chlorofiber surfaces are treated with 100W radio frequency power for 10 minutes under an argon atmosphere and a pressure of 50Pa to generate micro-nano-scale rough structures.

[0101] Chemical grafting: The etched fibers are immersed in a 5% acrylic acid solution and reacted at 60°C for 2 hours to introduce carboxylic acid groups;

[0102] Composite process: A mixed solution of phenol and tetrahydrofuran was prepared, with a phenol concentration of 6% and a tetrahydrofuran concentration of 5%, and mixed at a mass ratio of 2:1 to obtain a mixed solution. Polyester, nylon, and chlorofiber were added to the mixed solution at a mass ratio of 3:2:1, and the total concentration of the mixed solution was adjusted to 10 wt% to form a spinning solution. The solution was stirred at 60°C for 4 hours, and the viscosity was controlled at 1000 mPa·s. The spinning solution was extruded from a syringe and passed through a high-voltage electric field of 18 kV, a receiving distance of 20 cm, a flow rate of 1.5 mL / h, a temperature of 28°C, and a humidity of 45%. The composite fibers were collected on a collector using a high-speed rotating drum at 1200 rpm and vacuum dried at 60°C for 12 hours to obtain a mixed fiber with a fiber length of 30 mm and a diameter of less than 0.2 mm.

[0103] Example 5

[0104] The preparation process of blended fibers modified with polyester, nylon, and chlorofiber includes:

[0105] Plasma etching: Polyester, nylon, and chlorofiber surfaces are treated with 100W radio frequency power for 10 minutes under an argon atmosphere and a pressure of 50Pa to generate micro-nano-scale rough structures.

[0106] Chemical grafting: The etched fibers are immersed in a 5% acrylic acid solution and reacted at 60°C for 2 hours to introduce carboxylic acid groups;

[0107] Composite process: A mixed solution of phenol and tetrahydrofuran was prepared, with a phenol concentration of 6% and a tetrahydrofuran concentration of 5%, and mixed at a mass ratio of 2:1 to obtain a mixed solution. Polyester, nylon, and chlorofiber were added to the mixed solution at a mass ratio of 3:2:1, and the total concentration of the mixed solution was adjusted to 8 wt% to form a spinning solution. The solution was stirred at 60°C for 5 h, and the viscosity was controlled at 500 mPa·s. The spinning solution was extruded from a syringe and passed through a high-voltage electric field of 20 kV, a receiving distance of 12 cm, a flow rate of 2.0 mL / h, a temperature of 25°C, and a humidity of 50%. The composite fibers were collected on a collector using a high-speed rotating drum at 800 rpm and vacuum dried at 60°C for 12 h to obtain a mixed fiber with a fiber length of 50 mm and a diameter of less than 0.2 mm.

[0108] Example 6

[0109] The preparation process of blended fibers modified with polyester, nylon, and chlorofiber includes:

[0110] Plasma etching: Polyester, nylon, and chlorofiber surfaces are treated with 100W radio frequency power for 10 minutes under an argon atmosphere and a pressure of 50Pa to generate micro-nano-scale rough structures.

[0111] Chemical grafting: The etched fibers are immersed in a 5% acrylic acid solution and reacted at 60°C for 2 hours to introduce carboxylic acid groups;

[0112] Composite process: Prepare a mixed solution of phenol and tetrahydrofuran, wherein the concentration of phenol is 6% and the concentration of tetrahydrofuran is 5%, and mix them at a mass ratio of 2:1 to obtain a mixed solution. Add polyester, nylon and chlorofiber to the mixed solution at a mass ratio of 3:2:1, and adjust the total concentration of the mixed solution to 12wt% to form a spinning solution. Stir at 60℃ for 3-5h, control the viscosity to 1500 mPa·s, and extrude the spinning solution from the syringe. Pass it through a high voltage electric field of 15 kV, a receiving distance of 28 cm, a flow rate of 1.0 mL / h, a temperature of 30℃ and a humidity of 40%. Collect the composite fibers on the collector using a high-speed rotating drum at 1500 rpm, and vacuum dry at 60℃ for 12h to obtain a mixed fiber with a fiber length of 10 mm and a diameter of less than 0.2 mm.

[0113] Comparative Example 7

[0114] The difference between this comparative example and Example 4 is that the fibers in this comparative example are polyester fibers with a length of 30 mm and a diameter of less than 0.2 mm, obtained by crushing and sorting.

[0115] Comparative Example 8

[0116] The difference between this comparative example and Example 4 is that the fibers in this comparative example are polyester, nylon and chlorofiber fibers mixed and crushed in equal proportions, and sorted to obtain mixed fibers with a fiber length of 30 mm and a diameter of less than 0.2 mm.

[0117] Comparative Example 9

[0118] The difference between this comparative example and Example 4 is that the fibers in this comparative example are mixed and crushed by mixing polyester, nylon and chlorofiber fibers in a ratio of 3:2:1, and sorted to obtain mixed fibers with a fiber length of 30 mm and a diameter of less than 0.2 mm.

[0119] Comparative Example 10

[0120] Plasma etching: The surface of polyester fiber was treated with 100W radio frequency power for 10 minutes under an argon atmosphere and a pressure of 50Pa to generate a micro-nano-scale rough structure.

[0121] Chemical grafting: The etched fibers are immersed in a 5% acrylic acid solution and reacted at 60°C for 2 hours to introduce carboxylic acid groups;

[0122] Composite: A mixed solution of phenol and tetrahydrofuran was prepared, wherein the concentration of phenol was 6% and the concentration of tetrahydrofuran was 5%, and the mixture was mixed at a mass ratio of 2:1 to obtain a mixed solution. Polyester was added to the mixed solution, and the total concentration of the mixed solution was adjusted to 10 wt% to form a spinning solution. The solution was stirred at 60℃ for 4 h, and the viscosity was controlled at 800 mPa·s. The spinning solution was extruded from a syringe and passed through a high-voltage electric field of 18 kV, a receiving distance of 20 cm, a flow rate of 1.5 mL / h, a temperature of 258℃, and a humidity of 45%. The fibers were collected on a collector using a high-speed rotating drum at 1200 rpm and vacuum dried at 60℃ for 12 h to obtain polyester fibers with a fiber length of 30 mm and a diameter of less than 0.2 mm.

[0123] Comparative Example 11

[0124] Plasma etching: Polyester, nylon, and chlorofiber surfaces are treated with 100W radio frequency power for 10 minutes under an argon atmosphere and a pressure of 50Pa to generate micro-nano-scale rough structures.

[0125] Chemical grafting: The etched fibers are immersed in a 5% acrylic acid solution and reacted at 60°C for 2 hours to introduce carboxylic acid groups;

[0126] Composite process: A mixed solution of phenol and tetrahydrofuran was prepared, with phenol concentration of 6% and tetrahydrofuran concentration of 5%, and mixed at a mass ratio of 2:1 to obtain a mixed solution. Polyester and nylon were added to the mixed solution at an equal mass ratio, and the total concentration of the mixed solution was adjusted to 10 wt% to form a spinning solution. The solution was stirred at 60℃ for 4 hours, and the viscosity was controlled at 1000 mPa·s. The spinning solution was extruded from a syringe and passed through a high-voltage electric field of 18 kV, a receiving distance of 20 cm, a flow rate of 1.5 mL / h, a temperature of 28℃, and a humidity of 45%. The composite fibers were collected on a collector using a high-speed rotating drum at 1200 rpm and vacuum dried at 60℃ for 12 hours to obtain a mixed fiber with a fiber length of 30 mm and a diameter of less than 0.2 mm.

[0127] Comparative Example 12

[0128] Chemical grafting: Polyester, nylon, and chlorofiber fibers are immersed in a 5% acrylic acid solution and reacted at 60°C for 2 hours to introduce carboxylic acid groups;

[0129] Composite process: A mixed solution of phenol and tetrahydrofuran was prepared, with a phenol concentration of 6% and a tetrahydrofuran concentration of 5%, and mixed at a mass ratio of 2:1 to obtain a mixed solution. Polyester, nylon, and chlorofiber were added to the mixed solution at a mass ratio of 3:2:1, and the total concentration of the mixed solution was adjusted to 10 wt% to form a spinning solution. The solution was stirred at 60°C for 4 hours, and the viscosity was controlled at 1000 mPa·s. The spinning solution was extruded from a syringe and passed through a high-voltage electric field of 18 kV, a receiving distance of 20 cm, a flow rate of 1.5 mL / h, a temperature of 28°C, and a humidity of 45%. The composite fibers were collected on a collector using a high-speed rotating drum at 1200 rpm and vacuum dried at 60°C for 12 hours to obtain a mixed fiber with a fiber length of 30 mm and a diameter of less than 0.2 mm.

[0130] Based on Example 3 above, fiber materials from Examples 4-6 and Comparative Examples 7-12 were added, with a fiber content of 0.5-1.5% and a water-reducing agent content of 1.8-2% of the cementitious material. The matrix was then steam-cured at 90°C for 48 hours. Using the Anderson particle close packing model described above, the gradation between coarse and fine aggregates was calculated, and the mix proportion of UHPC was determined using the volumetric method. The porosity of the mixed aggregate was determined as P = (1-ρb / ρa)×100% at the maximum bulk density of the coarse and fine aggregates.

[0131] ρ b ρ is the bulk density of the mixed aggregate; a apparent density of mixed aggregates

[0132] Determine the amount of slurry V P =nP: Select paste surplus coefficient n values ​​of 1.1 and 1.15.

[0133] Determine the total amount of UHPC cementitious material used:

[0134] V P =V w +V b =W w / 1000+W b / ρ

[0135]

[0136] In the formula The water-to-binder ratio is 0.16, 0.18, and 0.2, where... For the quality of cementitious materials, W w For water quality, V w Let ρ be the water volume and ρ be the density of the cementitious material. Substituting these values ​​into the formula will yield the total amount of cementitious material used for different water-cement ratios.

[0137] Test 2: The compressive strength test was conducted according to GB / T31387-2015, and the expansion was tested according to GB / T 50080. The proportions and corresponding properties are shown in Table 2 below.

[0138] Table 2

[0139] Group number Silica fume (g) Ultrafine fly ash (g) Ultrafine lithium slag powder (g) Cement (g) Sand (g) Water (g) Water-reducing agent (g) Fiber (g) Compressive strength (MPa) Expansion (mm) Example 4 187 156 156 438 1263 169 12.4 29.75 178.45 820 Example 5 187 156 156 438 1263 169 12.4 11.9 176.93 810 Example 6 187 156 156 438 1263 169 12.4 47.6 177.28 815 Comparative Example 7 187 156 156 438 1263 169 12.4 29.75 154.85 750 Comparative Example 8 187 156 156 438 1263 169 12.4 29.75 157.46 760 Comparative Example 9 187 156 156 438 1263 169 12.4 29.75 163.92 775 Comparative Example 10 187 156 156 438 1263 169 12.4 29.75 166.54 785 Comparative Example 11 187 156 156 438 1263 169 12.4 29.75 169.28 790 Comparative Example 12 187 156 156 438 1263 169 12.4 29.75 171.36 800

[0140] Experiment 3: The mechanical properties of the concrete materials obtained in Examples 4-6 were tested according to the standards "Reactive Powder Concrete" (GB / T 31387-2015) and "Standard for Test Methods of Mechanical Properties of Ordinary Concrete" (GB / T50081-2002). The specific test results are shown in Table 3 below.

[0141] Table 3

[0142] Sample Flexural strength (MPa) Tensile strength (MPa) Elastic modulus GPa Example 4 30.2 18.5 52.3 Example 5 28.8 17.6 51.9 Example 6 24.5 17.4 50.7

Claims

1. A process for preparing self-compacting low-carbon ultra-high performance concrete from multi-element solid waste, characterized in that: The raw materials are: cement, silica fume, active solid waste admixture, inert solid waste filler, aggregate, and fiber; Based on the improved Anderson model, to achieve the self-compacting requirement, the distribution modulus is taken as 0.23, where d represents the particle size of the material in the UHPC system, in μm; max d represents the maximum particle size of the material in the UHPC system, in μm; min V represents the minimum particle size of the material in the UHPC system, in μm; d The cumulative volumetric doping amount is denoted by particle size d; according to the formula... Find the range of each particle size, where the particle size is within d. min -1μm is silica fume and active solid waste admixture; 1μm-10μm is active solid waste admixture and inert solid waste filler; 10μm-100μm is cement and inert solid waste filler; 100μm-d max For aggregates, calculate the cumulative volumetric admixture difference, V1-V min V 10 -V1:V 100 -V 10 V dmax -V 100 That is, the initial volume ratio.

2. The process for preparing self-compacting low-carbon ultra-high performance concrete from multi-element solid waste according to claim 1, characterized in that: The cement or new low-carbon cementitious material is 52.5 ordinary Portland cement or a new low-carbon cementitious material of equivalent grade 52.5, and has undergone grinding and mixing processes, with a particle size range of 10-100μm and a specific surface area of ​​380-450m². 2 / kg; The particle size range of silica fume is 0-1 μm; Active solid waste admixture: Ultrafine fly ash and ultrafine lithium slag admixture, processed through ultrafine grinding and sorting, with a particle size range of 1-10μm and a specific surface area of ​​600-800m². 2 / kg; Inert solid waste filler: Stone powder and tailings powder are processed through ultrafine grinding and sorting, with a particle size range of 10-100μm and a specific surface area of ​​350-480m². 2 / kg; Aggregates: construction waste, artificial aggregates, natural aggregates or compound aggregates, of which the fine aggregate size range is 0-5mm and the coarse aggregate size range is 3-8mm, all of which meet the requirements of the Fuller curve.

3. The process for preparing self-compacting low-carbon ultra-high performance concrete from multi-element solid waste as described in claim 2, characterized in that, The preparation process of foamed ceramics is as follows: The ultrafine fly ash in the activated solid waste admixture also undergoes the following treatment: High-temperature carbonization: Ultrafine fly ash is heated to 800℃ at 10℃ / min in an argon atmosphere and held for 1 hour to generate a porous carbon skeleton. Impurity removal and activation: The fly ash treated by high temperature carbonization above is first added to 5% dilute sulfuric acid at a solid-liquid ratio of 1:8, and stirred at 300-500 rpm. The impurities are removed by acid washing at 60-80℃, followed by washing with water until the pH is 6.5-7.

5. After drying, 2% Ca(OH)2 passing through a 200-mesh sieve is added and dry-mixed at 60-100 rpm. The mixture is then moist-heat cured at 60℃ for 48 hours to activate the activity. Silane coupling treatment: Activated fly ash was soaked in a 3% KH550 silane coupling agent ethanol solution at a solid-liquid ratio of 1:5, ultrasonically treated for 1 hour, dried at 60℃, and then ground and sorted to obtain particles ranging from 1-10 μm with a specific surface area of ​​600-800 m². 2 / kg of ultrafine fly ash.

4. The process for preparing self-compacting low-carbon ultra-high performance concrete from multi-element solid waste according to claim 1, characterized in that: The ultrafine lithium slag admixture in the activated solid waste admixture also includes the following treatment: Electrochemical activation: Lithium slag powder was mixed with 0.5 mol / L sulfuric acid solution at a solid-liquid ratio of 1:

3. A current density of 10 mA / cm² was applied in an electrolytic cell using graphite electrodes. 2 The reaction lasted for 2 hours. Microbial mineralization: After washing the activated lithium slag powder 2-3 times with water, add it to 9K culture medium at a solid-liquid ratio of 1:5, and add *Thiobacillus acidophilus* at a concentration of 10. 8 CFU / mL, temperature 30-35℃, add sulfuric acid to adjust pH to 2.0-2.5, shake and incubate for 48h at a shaking rate of 150-200 rpm; Low-temperature calcination: The lithium slag powder after microbial mineralization was filtered, dried, and calcined at 300℃ for 1 hour, followed by grinding and sorting to obtain a particle size range of 1-10 μm and a specific surface area of ​​600-800 m². 2 / kg of ultrafine lithium slag admixture.

5. The process for preparing self-compacting low-carbon ultra-high performance concrete from multi-element solid waste according to claim 1, characterized in that: The fiber is a blend of modified polyester, nylon, and chlorofiber.

6. The process for preparing self-compacting low-carbon ultra-high performance concrete from multi-element solid waste according to claim 5, characterized in that: The preparation process of the polyester, nylon, and chlorofiber modified blended fiber includes: Plasma etching: Polyester, nylon, and chlorofiber surfaces are treated with 100W radio frequency power for 10 minutes under an argon atmosphere and a pressure of 50Pa to generate micro-nano-scale rough structures. Chemical grafting: The etched fibers are immersed in a 5% acrylic acid solution and reacted at 60°C for 2 hours to introduce carboxylic acid groups; Composite process: Prepare a mixed solution of phenol and tetrahydrofuran, wherein the concentration of phenol is 6% and the concentration of tetrahydrofuran is 5%, and mix them at a mass ratio of 2:1 to obtain a mixed solution. Add polyester, nylon, and chlorofiber to the mixed solution at a mass ratio of 3:2:1, and adjust the total concentration of the mixed solution to 8-12wt% to form a spinning solution. Stir at 60℃ for 3-5h, and control the viscosity to 500-1500 mPa·s. Extrude the spinning solution from a syringe and pass it through a high-voltage electric field of 15-20 kV, a receiving distance of 12-28 cm, a flow rate of 1.0-2.0 mL / h, a temperature of 25-30℃, and a humidity of 40-50%. Collect the composite fibers on a collector using a high-speed rotating drum at 800-1500 rpm. Vacuum dry at 60℃ for 12h to obtain mixed fibers with a fiber length of 10-50 mm and a diameter of less than 0.2 mm.

7. The process for preparing self-compacting low-carbon ultra-high performance concrete from multi-element solid waste according to claim 1, characterized in that, Includes the following steps: (1) Calculate the initial weight ratio of each solid waste material by designing the initial mix proportion of the multi-component solid waste materials; (2) Design the initial mix proportion based on cement, aggregates, etc., calculate the initial weight ratio of each material, and combine it with the initial mix proportion of multi-component solid waste materials to obtain the initial weight ratio of raw materials such as multi-component solid waste materials, cement, and aggregates; (3) Based on the concrete fiber content of 0.5-2% per cubic meter, the water-reducing agent content is 1.8-2% of the cementitious material content. Adjust the water-cement ratio or admixture content according to the fluidity to meet the spread ≥700mm. (4) Place the substrate at 90℃ for 48 hours for steam curing.

8. The process for preparing self-compacting low-carbon ultra-high performance concrete from multi-element solid waste according to claim 7, characterized in that, The process of adjusting the water-cement ratio or admixture dosage based on flowability is as follows: First, using the Anderson particle close packing model, the gradation between coarse and fine aggregates is calculated, and the mix proportion of UHPC is determined according to the volume method. Then, the porosity P of the mixed aggregate is determined under the maximum bulk density of the coarse and fine aggregates: P = (1 - ρ b / ρ a )×100%, ρ b ρ is the bulk density of the mixed aggregate; a To determine the apparent density of the mixed aggregate, the amount of paste V is determined. P =nP: Selecting the slurry surplus coefficient n values ​​of 1.1 and 1.15, determine the total amount of UHPC cementitious material used: V P =V w +V b =W w / 1000+W b / ρ In the formula The water-to-binder ratio is 0.16, 0.18, and 0.2, where... For the quality of cementitious materials, W w For water quality, V w Let ρ be the water volume and ρ be the density of the cementitious material. Substituting these values ​​into the formula will yield the total amount of cementitious material used for different water-cement ratios.

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