Carbon-negative solid waste-based foam concrete for highway engineering and preparation method thereof

Abstract

The application discloses a negative-carbon solid waste-based foam concrete for highway engineering and a preparation method thereof, and relates to the field of building materials. The negative-carbon solid waste-based foam concrete for highway engineering comprises the following raw materials in parts by weight: solid waste cementing material 60-64 parts, carbon mineralization inducer 8-12 parts, foaming liquid 6-8 parts, and water 21-22 parts. The solid waste cementing material comprises mineral powder, salt gypsum and waste sepiolite fiber; the carbon mineralization inducer comprises municipal solid waste incineration bottom ash and potato starch waste liquid; and the foaming liquid comprises sodium dodecyl sulfonate and waste alkali washing liquid of a waste fan blade. The solid waste cementing material, the carbon mineralization inducer, the foaming liquid and the water are mixed according to a specific ratio, and the prepared solid waste-based concrete after specific curing has the characteristics of stable mechanical properties, negative-carbon emission properties and the like, and can be used as green building materials for highway engineering.

Description

Technical Field

[0001] This application relates to the field of building materials, and in particular to a carbon-negative solid waste-based foamed concrete for highway engineering and its preparation method. Background Technology

[0002] Foamed concrete is a lightweight porous material that introduces numerous pores into a cementitious slurry through physical or chemical foaming processes. It boasts advantages such as lightweight, thermal insulation, sound absorption and noise reduction, and ease of construction, and has been widely used in highway engineering fields such as roadbed filling, bridge abutment backfilling, and tunnel cavity filling. With the deepening of the national "dual-carbon" strategy, using industrial solid waste to replace traditional cement as a cementitious material to prepare foamed concrete, combined with carbon mineralization technology to achieve CO2 solidification and sequestration, has become an important technological path for carbon emission reduction in the building materials sector.

[0003] However, existing solid waste-based foamed concrete has the following shortcomings: First, the mechanical properties are poor. Existing technologies typically use multiple types of industrial solid waste as cementing materials. While this increases the amount of solid waste disposed of, the combined use of various industrial solid wastes can complicate or even abnormalize the hydration reaction pathways of the cementing materials, affecting the formation of the structural framework. Furthermore, the introduction of multiple solid wastes often adversely affects the stability of the foam, resulting in poor mechanical properties of the foamed concrete. These problems limit the widespread use of solid waste-based foamed concrete in applications such as highway engineering where high mechanical performance is required.

[0004] Second, the carbon fixation capacity is limited. Foamed concrete, with its numerous pores, is naturally suitable as a carrier for CO2 diffusion and carbon mineralization reactions. However, existing technologies exhibit a "self-blocking" problem during carbon mineralization. Specifically, calcite generated during carbon mineralization continuously deposits and grows on the pore walls of the foamed concrete. The calcite crystals are densely packed, and as the carbon mineralization reaction proceeds, the densely packed calcite gradually blocks the pores and connecting pathways of the foamed concrete, making it difficult for CO2 to continue diffusing into the interior. This limits the depth of the carbon mineralization reaction, and the amount of carbon fixed tends to plateau or even stagnate with prolonged curing time. Although existing technologies attempt to improve permeability and carbon mineralization capacity by introducing pore-opening agents and carbon-fixing microorganisms, the introduction of pore-opening agents often comes at the cost of sacrificing mechanical properties, and the survival conditions for carbon-fixing microorganisms are demanding, with unstable effects. Therefore, the carbon fixation capacity of existing solid waste-based foamed concrete is limited.

[0005] Therefore, there is an urgent need to develop a solid waste-based foamed concrete with fewer solid waste types, excellent mechanical properties, and high carbon solidification capacity, as well as its preparation method, to meet the needs of highway engineering for green building materials. Summary of the Invention

[0006] To address at least one of the aforementioned technical problems, this application proposes a carbon-negative solid waste-based foamed concrete for highway engineering and its preparation method.

[0007] In the first aspect, this application provides a carbon-negative solid waste-based foamed concrete for highway engineering, comprising the following raw materials in parts by weight: 60-64 parts of solid waste cementitious material, 8-12 parts of carbon mineralization inducer, 6-8 parts of foaming liquid, and 21-22 parts of water. The solid waste cementitious material includes mineral powder, salt gypsum and waste sepiolite fiber, and the weight ratio of the mineral powder, the salt gypsum and the waste sepiolite fiber is (69~71):(20~25):(5~10). The carbon mineralization inducer includes municipal solid waste incineration bottom ash and potato starch waste liquid, wherein the weight ratio of the municipal solid waste incineration bottom ash to the potato starch waste liquid is (75~90):(10~25). The foaming liquid includes sodium dodecyl sulfonate and waste alkaline washing liquid from waste wind turbine blades, with the weight ratio of sodium dodecyl sulfonate to waste alkaline washing liquid from waste wind turbine blades being (10~20):(980~990).

[0008] By adopting the above technical solution, this application uses three types of solid waste—mineral powder, salt gypsum, and waste sepiolite fiber—as cementing materials. This reduces the number of solid waste types and allows for a controllable hydration reaction pathway, effectively avoiding the problem of abnormal hydration reactions caused by a large variety of solid waste types in existing technologies. Waste sepiolite fiber forms the basic spatial framework, mineral powder fills the larger gaps between the fibers, and salt gypsum further fills the tiny gaps between the mineral powder particles, reducing ineffective porosity in the matrix. During curing, after being activated by salt gypsum, the mineral powder, combined with the crystal regulation effect of chloride ions in the salt gypsum, forms a large number of oriented prismatic crystals, thereby constructing the structural framework and providing the main mechanical strength support for the foamed concrete.

[0009] The waste alkaline washing liquid of abandoned wind turbine blades in the foaming liquid plays a dual interface strengthening function in the foam concrete system. (1) Gas-solid interface strengthening: When the foaming liquid is mixed with the cementitious material slurry, the NaOH in the alkaline washing liquid can produce a local strong alkaline activation effect at the interface between the foam film and the cementitious material (i.e., the gas-solid interface). The strong alkalinity of NaOH can destroy the glassy structure on the surface of the mineral powder particles, accelerate the hydration reaction rate of the mineral powder in the gas-solid interface region, and rapidly generate a high-strength hydration product shell layer around the foam. This hydration product shell layer tightly wraps the foam pore wall, significantly improving the bonding strength of the gas-solid interface and preventing the foam pore wall from collapsing or merging due to insufficient interface strength. (2) Solid-liquid interface strengthening: The organic fibers (free carbon fibers and some glass fiber fragments) in the waste alkaline washing liquid of abandoned wind turbine blades play a role in reducing the gas-liquid interfacial tension in the foam film, enhancing the mechanical strength and elasticity of the foam film, and effectively improving the stability of the foam. Through the above-mentioned gas-solid interface strengthening and solid-liquid interface strengthening, the wet density and mechanical properties of solid waste-based foamed concrete are guaranteed.

[0010] The carbon mineralization inducer consists of municipal solid waste incineration bottom ash and potato starch waste liquid, both of which play a synergistic kinetic regulatory role in the carbon mineralization process. Specifically, the municipal solid waste incineration bottom ash contains a high content of organic carbon, which is naturally porous. During the carbon mineralization process, the porous organic carbon can rapidly accumulate CO2, forming a local high-concentration region of CO2 on the surface of the organic carbon particles, lowering the initiation energy barrier of the carbon mineralization reaction and accelerating the nucleation process of carbonization products. Simultaneously, the surface of the organic carbon particles has abundant oxygen-containing functional groups, which can adsorb Ca from the solution through electrostatic attraction and hydrogen bonding. 2+ , making Ca 2+ Enrichment on the surface of organic carbon provides numerous active sites for heterogeneous nucleation of calcium carbonate. Therefore, calcium carbonate preferentially nucleates and deposits on the surface of organic carbon particles, rather than randomly on the pore walls. This mechanism shifts the deposition location of carbon mineralization products from the pore walls to the surface of organic carbon particles (i.e., dispersed within the matrix), spatially reducing the risk of pore blockage.

[0011] Potato starch waste liquid is rich in natural amino acids. These amino acid molecules play a key role in regulating crystal morphology during carbon mineralization. The regulatory mechanism is as follows: the carboxyl group (-COOH) in the amino acid molecule can react with Ca in the solution. 2+ Formation of complexes reduces the amount of free Ca in the solution. 2+ The concentration of this will cause the calcium phase in the hydration products of the cementitious material to continuously dissolve and release Ca. 2+ Thus maintaining the Ca content in the carbon mineralization system 2+A continuous supply of amino acids ensures the continuous progress of the carbon mineralization reaction. During the growth of carbon mineralization products, amino acid molecules can selectively adsorb onto specific crystal faces of the carbon mineralization products, forming a stable adsorption layer. This amino acid adsorption layer hinders the continued deposition and growth of subsequent carbon mineralization products on that crystal face, i.e., it inhibits the growth of carbon mineralization products along that crystal face direction, effectively controlling the crystal morphology of the carbon mineralization products. After morphology control, a loosely packed carbon mineralization product layer is formed. The loosely packed carbon mineralization product layer retains a large number of interparticle gaps and channels, allowing CO2 gas and pore water containing dissolved CO2 to continuously diffuse into the interior of the foamed concrete through these gaps and channels. The depth of the carbon mineralization reaction is not limited by the densification of the product layer. This fundamentally solves the problem of dense packing of carbon mineralization products blocking pores in existing technologies.

[0012] This application utilizes the coupling effect of foaming liquid and waste sepiolite fibers to construct a highly interconnected pore network within foamed concrete, optimizing CO2 mass transfer channels. The foam formed after high-speed foaming of the foaming liquid is introduced into the foamed concrete system, creating numerous millimeter- and sub-millimeter-sized macroscopic pores within the matrix. These pores provide the primary channels for CO2 gaseous diffusion. Waste sepiolite fibers possess a natural tubular microporous structure, and the fibers are randomly distributed three-dimensionally within the foamed concrete matrix. The tubular channels within the fibers and the microcracks (interface transition zones) formed at the fiber-matrix interface establish microscopic interconnected channels between adjacent macroscopic pores, linking the originally relatively independent macroscopic pores into a highly interconnected three-dimensional pore network. The macroscopic pores provide the primary storage and diffusion space for CO2, while the microscopic interconnected channels ensure the sustainable transport of CO2 from the carbonized outer pores to the uncarbonized inner pores. Even if carbonized products have deposited on the outer pore walls, CO2 can still reach deeper regions of the foamed concrete through the microscopic interconnected channels provided by the sepiolite fibers. This coupling construction of macro-micro pores significantly increases the effective diffusion depth of CO2, ensuring the realization of high carbon solidification capability from the perspective of thermodynamic mass transfer.

[0013] The regulation of carbon mineralization kinetics (loosely packed carbon mineralization products do not block the pores) and the optimization of carbon mineralization thermodynamics (coupling of macro-micro pores ensures continuous CO2 mass transfer) promote the continuous increase of carbon mineralization depth and carbon fixation capacity, thereby improving the carbon solidification ability of the material.

[0014] In summary, this application uses three types of solid waste—mineral powder, salt gypsum, and waste sepiolite fiber—as cementing materials. The limited variety of solid wastes and controllable hydration reaction pathways effectively avoid the abnormal hydration reaction problems caused by the large number of solid waste types in existing technologies. This application ensures mechanical properties through "rapid hydration of solid waste cementing materials to construct a structural framework + foaming liquid interface reinforcement," and enhances carbon solidification capacity by combining "carbon mineralization inducer to regulate carbon mineralization kinetics + interconnected pore network to optimize carbon mineralization thermodynamics." This solves the problems of poor mechanical properties and limited carbon solidification capacity in existing solid waste-based foamed concrete.

[0015] Optionally, the weight ratio of the solid waste cementitious material, the carbon mineralization inducer, the foaming liquid and the water is (61~64):(8~10):(6~8):(21~22).

[0016] Preferably, the weight ratio of solid waste cementitious material, carbon mineralization inducer, foaming liquid and water is 64:8:6:22.

[0017] Optionally, in the solid waste cementitious material, the weight ratio of the mineral powder, the gypsum, and the waste sepiolite fiber is 70:(23~25):(5~7). Preferably, in the solid waste cementitious material, the weight ratio of the mineral powder, the gypsum, and the waste sepiolite fiber is 70:23:7.

[0018] By adopting the above technical solution and controlling the ratio of mineral powder, salt gypsum and waste sepiolite fiber, the amounts of the three solid wastes are matched and mutually restrictive, which not only ensures the full progress of the hydration reaction and the formation of a high-strength skeleton structure, but also ensures the effective functioning of fiber toughening and micro-connection channel construction, thus achieving synergistic optimization of the mechanical properties and carbon solidification ability of foamed concrete.

[0019] Optionally, in the solid waste cementitious material, the mineral powder is S95 grade granulated blast furnace slag powder with an average particle size of 10~20μm and a specific surface area of ​​850~950m². 2 / kg, by weight percentage, the chemical composition of the mineral powder includes: MgO 4.0~9.0wt%, CaO 30~42wt%, SiO2 26~35wt%, Al2O3 10~18wt%, Fe2O3 0.5~2.0wt%, with the balance being other trace components; The average particle size of gypsum salt is 3~8μm, and the specific surface area is 2000~2600m². 2 / kg, by weight percentage, the chemical composition of salt gypsum includes: 90~96wt% dihydrate gypsum, 0.5~3.0wt% chloride ion content, and the balance being other trace components; The average particle size of waste sepiolite fibers is 30~80μm, and the specific surface area is 200~300m². 2 / kg, by weight percentage, the chemical composition of waste sepiolite fiber includes: sepiolite fiber 30~40wt%, pearl salt 5~15wt%, calcium carbonate 10~20wt%, free water and crystal water 8~15wt%, and the balance is associated mineral impurities such as quartz and dolomite.

[0020] Optionally, the weight ratio of municipal solid waste incineration bottom ash to potato starch waste liquid in the carbon mineralization inducer is (83~85):(15~17). Preferably, the weight ratio of municipal solid waste incineration bottom ash to potato starch waste liquid in the carbon mineralization inducer is 84:16.

[0021] By adopting the above technical solution, the bottom ash from municipal solid waste incineration provides sufficient active calcium sources and heterogeneous nucleation sites for carbon mineralization, driving the efficient carbon mineralization reaction. Amino acids and other substances in potato starch waste liquid also contribute to the carbon mineralization reaction. 2+ By finely controlling the supersaturation, nucleation mode, and crystal morphology, and by controlling the ratio of municipal solid waste incineration bottom ash and potato starch waste liquid, the carbon mineralization product layer formed is directionally deposited in the pore walls and matrix in a loosely packed form, thus achieving high carbon solidification and effective enhancement of mechanical properties by carbon mineralization products.

[0022] Optionally, in the carbon mineralization inducer, the loss on ignition of the municipal solid waste incineration bottom ash is 12-18 wt%, the average particle size of the municipal solid waste incineration bottom ash is 20-80 μm, and the chemical composition of the municipal solid waste incineration bottom ash, by weight percentage, includes: organic carbon 3.2-4.7 wt%, calcium hydroxide 5-8 wt%, CaO 15-25 wt%, SiO2 20-35 wt%, Al2O3 8-15 wt%, Fe2O3 5-12 wt%, MgO 2-5 wt%, Na2O 3-8 wt%, K2O 1-4 wt%, Cl - 1.5~5.0wt%, SO3 2~6wt%, P2O5 0.5~2.0wt%, heavy metals (based on total Pb, Zn, Cu, and Cr) 0.3~1.2wt%, balance being trace oxides such as TiO2 and MnO and bound water; Potato starch wastewater is an organic wastewater generated during the refining of crude starch milk. By weight percentage, the chemical composition of potato starch wastewater includes: 0.8–1.2 wt% natural amino acids, 3.0–6.0 wt% residual starch and starch degradation products (dextrin, maltose, and glucose), 0.5–1.5 wt% protein and polypeptide fragments, 0.3–0.8 wt% organic acids (citric acid, malic acid, and oxalic acid), and potassium. + 0.3~0.8wt%, Mg 2+ 0.05~0.15wt%, PO4 3-0.1~0.4wt%, Ca 2+ 0.02~0.08wt%, 0.2~0.5wt% cellulose and pectin polysaccharides, pH 4.5~6.0, balance is water.

[0023] Optionally, the weight ratio of sodium dodecyl sulfonate to waste alkaline washing liquid of discarded wind turbine blades in the foaming liquid is (15.5~16.5):(982~986). Preferably, the weight ratio of sodium dodecyl sulfonate to waste alkaline washing liquid of discarded wind turbine blades in the foaming liquid is 16:984.

[0024] By adopting the above technical solution and controlling the ratio of sodium dodecyl sulfonate and waste alkaline washing liquid from waste wind turbine blades, the waste sepiolite fiber is fully mixed with the waste sepiolite fiber to ensure foaming rate, foaming stability, and stability of interconnected pores, thus ensuring the mass transfer channel of CO2.

[0025] Optionally, the chemical composition of the wastewater from the alkaline washing of discarded wind turbine blades, by weight percentage, includes: 10-20 wt% sodium hydroxide, 8-12 wt% free carbon fiber, 5-15 wt% epoxy resin alkaline hydrolysis products, 1-4 wt% water-soluble sodium silicate, 2-6 wt% short-chain polyether polyol, 0.5-3 wt% sodium bisphenol A and its oligomers, 0.3-2.0 wt% glycerol and propylene glycol, 0.2-1.0 wt% suspended fine glass fiber fragments, 0.5-2.0 wt% free Na2CO3, pH value 13-14, and the balance being water.

[0026] Secondly, this application provides a method for preparing carbon-negative solid waste-based foamed concrete for highway engineering as described in any of the above claims, comprising the following steps: Solid waste cementitious materials, carbon mineralization inducers, foaming liquid and water are mixed and stirred to obtain a slurry. The slurry is then cast into a mold and carbonized to obtain the negative carbon type solid waste-based foamed concrete for highway engineering.

[0027] By adopting the above technical solution, the solid waste-based foamed concrete produced achieves high carbon solidification and has excellent mechanical properties.

[0028] Optionally, the preparation method of the carbon-negative solid waste-based foamed concrete for highway engineering includes the following steps: S1. Mix and homogenize mineral powder, salt gypsum and waste sepiolite fiber to obtain solid waste cementitious material; mix municipal solid waste incineration bottom ash with potato starch waste liquid and stir to obtain carbon mineralization inducer; add sodium dodecyl sulfonate to waste wind turbine blade alkaline washing waste liquid and stir to obtain foaming liquid. S2. Mix solid waste cementitious material, carbon mineralization inducer and water, stir to obtain slurry A; stir the foaming liquid obtained in step S1 at high speed to obtain foam, add the foam to slurry A, and fully homogenize to obtain slurry B; S3. The slurry B obtained in step S2 is poured into a mold and cured for 6-8 hours under the conditions of temperature of 30-35℃, relative humidity of 40-60%, and CO2 volume percentage concentration of 30-40% to complete carbon mineralization and obtain the negative carbon type solid waste-based foamed concrete for highway engineering.

[0029] It is understood that the CO2 volume percentage for carbonization curing can be 30-40%, preferably 35%; the temperature can be 30-35℃, preferably 32℃; the relative humidity can be 40-60%, preferably 50%; and the curing time can be 6-8 hours, preferably 7 hours.

[0030] The high-speed stirring in "foaming liquid is obtained by high-speed stirring" refers to a stirring rate of 1500~2500 rpm, preferably 2000 rpm.

[0031] In summary, this application includes at least one of the following beneficial technical effects: (1) This application uses solid waste to prepare cementitious materials. There are few types of solid waste, and the hydration path of cementitious materials is easy to control. Organic fibers and NaOH in foaming liquid are used to improve the strength of solid-liquid interface and gas-solid interface. Thus, a large amount of solid waste can be disposed of and the mechanical properties of foamed concrete can be effectively improved.

[0032] (2) This application utilizes the organic carbon and natural amino acids in the carbon mineralization inducer to provide crystallization sites for the carbon mineralization products of foamed concrete and regulate the morphology of the carbon mineralization products; the highly interconnected pores constructed by the foam generated by the foaming liquid and the waste sepiolite fibers continuously generate loosely deposited carbon mineralization products; thereby realizing the high carbon solidification capacity and overall negative carbon properties of solid waste foamed concrete.

[0033] (3) The solid waste foam concrete of this application has the characteristics of stable mechanical properties and negative carbon emission properties, and can be used as a green building material for highway engineering. Attached Figure Description

[0034] Figure 1 Image of the carbon-negative solid waste-based foamed concrete obtained in Example 2; Figure 2 This is a SEM image of the carbon-negative solid waste-based foamed concrete obtained in Example 2. Detailed Implementation

[0035] The present application will be further described in detail below with reference to the embodiments.

[0036] Description of raw materials involved in this application: Mineral powder, S95 grade granulated blast furnace slag powder, with an average particle size of 15μm and a specific surface area of ​​approximately 900m². 2 / kg, by weight percentage, the chemical composition of the mineral powder includes: MgO 5.6wt%, CaO 38wt%, SiO2 31wt%, Al2O3 13wt%, Fe2O3 1.2wt%, with the balance being other trace components; Salt gypsum, with an average particle size of 5 μm and a specific surface area of ​​approximately 2300 m², 2 / kg, by weight percentage, the chemical composition of salt gypsum includes: 93wt% dihydrate gypsum, 1.5wt% chloride ions, and the balance being other trace components; Waste sepiolite fiber is a byproduct of calcium silicate board production, with an average particle size of 50μm and a specific surface area of ​​approximately 250m². 2 / kg, by weight percentage, the chemical composition of waste sepiolite fiber includes: sepiolite fiber 35wt%, pearl salt 10wt%, calcium carbonate 15wt%, free water and crystal water content 12wt%, and the balance is associated mineral impurities such as quartz and dolomite. The bottom ash from municipal solid waste incineration has a loss on ignition of 15 wt% and an average particle size of 50 μm. By weight percentage, the chemical composition of the bottom ash includes: organic carbon 3.9 wt%, calcium hydroxide 6.2 wt%, CaO 20 wt%, SiO2 27 wt%, Al2O3 11.5 wt%, Fe2O3 8.5 wt%, MgO 3.2 wt%, Na2O 5.5 wt%, K2O 2.5 wt%, Cl... - 3.2wt%, SO3 4wt%, P2O5 1.5wt%, heavy metals (total of Pb, Zn, Cu and Cr) 0.6wt%, balance is trace oxides such as TiO2 and MnO and bound water; Potato starch wastewater, an organic wastewater generated during the refining of crude starch milk, comprises, by weight percentage: 1.1 wt% natural amino acids, 4.5 wt% residual starch and starch degradation products (based on the total amount of dextrin, maltose, and glucose), 1.0 wt% protein and polypeptide fragments, 0.5 wt% organic acids (based on the total amount of citric acid, malic acid, and oxalic acid), and K. + 0.5wt%, Mg 2+ 0.10wt%, PO4 3- 0.2wt%, Ca 2+ 0.05 wt%, 0.35 wt% cellulose and pectin polysaccharides, balance water, pH 5.2; The waste liquid from the alkaline washing of discarded wind turbine blades is produced by a process called wet chemical degradation, which involves placing the blades in an alkaline solution to recover carbon fibers from retired wind turbine blades. The chemical composition of this waste liquid includes: 15wt% sodium hydroxide, 10wt% free carbon fibers, 10wt% epoxy resin hydrolysis products, 2.5wt% water-soluble sodium silicate, 4wt% short-chain polyether polyol, 1.5wt% sodium bisphenol A and its oligomers, 1.1wt% glycerol, 0.6wt% suspended fine glass fiber fragments, 1.2wt% free Na₂CO₃, and the balance being water, with a pH of 13.5. Example 1

[0037] A method for preparing carbon-negative solid waste-based foamed concrete for highway engineering includes the following steps: S1. Mix 70 parts by weight of mineral powder, 25 parts by weight of salt gypsum and 5 parts by weight of waste sepiolite fiber, and stir at 500 rpm for 20 min to obtain solid waste cementitious material; mix 84 parts by weight of municipal solid waste incineration bottom ash and 16 parts by weight of potato starch waste liquid, and stir at 300 rpm for 10 min to obtain carbon mineralization inducer; add 16 parts by weight of sodium dodecyl sulfonate to 984 parts by weight of waste wind turbine blade alkaline washing waste liquid, and stir at 500 rpm for 10 min to obtain foaming liquid.

[0038] S2. Mix 60 parts by weight of the solid waste cementitious material obtained in step S1, 12 parts by weight of the carbon mineralization inducer obtained in step S1, and 22 parts by weight of water, and stir at 800 rpm for 5 min to obtain slurry A; inject 6 parts by weight of the foaming liquid obtained in step S1 into a high-speed foaming machine, and mechanically foam at 2000 rpm for 5 min to obtain foam; add the foam to slurry A, and stir at 300 rpm for 2 min to obtain slurry B.

[0039] S3. Pour the slurry B obtained in step S2 into a standard cubic mold of 100mm×100mm×100mm, place it in a carbon mineralization curing box, and cure for 7 hours under the conditions of temperature 32℃, relative humidity 50%, CO2 volume percentage concentration 35% (the balance is nitrogen) to complete carbon mineralization. After demolding, negative carbon type solid waste-based foamed concrete for highway engineering is obtained. Examples 2-3

[0040] Examples 2 and 3 are based on Example 1, the difference being that in step S2, the amounts of solid waste cementitious material, carbon mineralization inducer, foaming liquid, and water are adjusted, while the other steps remain the same as in Example 1. Specifically, Step S2 of Example 2: Mix 64 parts by weight of the solid waste cementitious material obtained in step S1, 8 parts by weight of the carbon mineralization inducer obtained in step S1, and 22 parts by weight of water, and stir at 800 rpm for 5 min to obtain slurry A; inject 6 parts by weight of the foaming liquid obtained in step S1 into a high-speed foaming machine, and mechanically foam at 2000 rpm for 5 min to obtain foam; add the foam to slurry A, and stir at 300 rpm for 2 min to obtain slurry B.

[0041] Step S2 of Example 3: Mix 61 parts by weight of the solid waste cementitious material obtained in step S1, 10 parts by weight of the carbon mineralization inducer obtained in step S1, and 21 parts by weight of water, and stir at 800 rpm for 5 min to obtain slurry A; inject 8 parts by weight of the foaming liquid obtained in step S1 into a high-speed foaming machine, and mechanically foam at 2000 rpm for 5 min to obtain foam; add the foam to slurry A, and stir at 300 rpm for 2 min to obtain slurry B. Examples 4-5

[0042] Examples 4 and 5 are based on Example 2, the difference being that in step S1, the amount of the components constituting the solid waste cementitious material was adjusted, while the other steps remained the same as in Example 2. Specifically, Step S1 of Example 4: Mix 70 parts by weight of mineral powder, 20 parts by weight of salt gypsum and 10 parts by weight of waste sepiolite fiber, and stir at 500 rpm for 20 min to obtain solid waste cementitious material; mix 84 parts by weight of municipal solid waste incineration bottom ash and 16 parts by weight of potato starch waste liquid, and stir at 300 rpm for 10 min to obtain carbon mineralization inducer; add 16 parts by weight of sodium dodecyl sulfonate to 984 parts by weight of waste wind turbine blade alkaline washing waste liquid, and stir at 500 rpm for 10 min to obtain foaming liquid.

[0043] Step S1 of Example 5: Mix 70 parts by weight of mineral powder, 23 parts by weight of salt gypsum and 7 parts by weight of waste sepiolite fiber, and stir at 500 rpm for 20 min to obtain solid waste cementitious material; mix 84 parts by weight of municipal solid waste incineration bottom ash and 16 parts by weight of potato starch waste liquid, and stir at 300 rpm for 10 min to obtain carbon mineralization inducer; add 16 parts by weight of sodium dodecyl sulfonate to 984 parts by weight of waste wind turbine blade alkaline washing waste liquid, and stir at 500 rpm for 10 min to obtain foaming liquid. Examples 6-7

[0044] Examples 6 and 7 are based on Example 5, except that the amount of the components constituting the carbon mineralization inducer in step S1 is adjusted, while the other steps remain the same as in Example 5. Specifically, Step S1 of Example 6: Mix 70 parts by weight of mineral powder, 23 parts by weight of salt gypsum and 7 parts by weight of waste sepiolite fiber, and stir at 500 rpm for 20 min to obtain solid waste cementitious material; mix 75 parts by weight of municipal solid waste incineration bottom ash and 25 parts by weight of potato starch waste liquid, and stir at 300 rpm for 10 min to obtain carbon mineralization inducer; add 16 parts by weight of sodium dodecyl sulfonate to 984 parts by weight of waste wind turbine blade alkaline washing waste liquid, and stir at 500 rpm for 10 min to obtain foaming liquid.

[0045] Step S1 of Example 7: Mix 70 parts by weight of mineral powder, 23 parts by weight of salt gypsum and 7 parts by weight of waste sepiolite fiber, and stir at 500 rpm for 20 min to obtain solid waste cementitious material; mix 90 parts by weight of municipal solid waste incineration bottom ash and 10 parts by weight of potato starch waste liquid, and stir at 300 rpm for 10 min to obtain carbon mineralization inducer; add 16 parts by weight of sodium dodecyl sulfonate to 984 parts by weight of waste wind turbine blade alkaline washing waste liquid, and stir at 500 rpm for 10 min to obtain foaming liquid. Examples 8-9

[0046] Examples 8 and 9 are based on Example 5, the difference being that the amount of the components constituting the foaming liquid was adjusted in step S1, while the other steps remained the same as in Example 5. Specifically, Step S1 of Example 8: Mix 70 parts by weight of mineral powder, 23 parts by weight of salt gypsum and 7 parts by weight of waste sepiolite fiber, and stir at 500 rpm for 20 min to obtain solid waste cementitious material; mix 84 parts by weight of municipal solid waste incineration bottom ash and 16 parts by weight of potato starch waste liquid, and stir at 300 rpm for 10 min to obtain carbon mineralization inducer; add 10 parts by weight of sodium dodecyl sulfonate to 990 parts by weight of waste wind turbine blade alkaline washing waste liquid, and stir at 500 rpm for 10 min to obtain foaming liquid.

[0047] Step S1 of Example 9: Mix 70 parts by weight of mineral powder, 23 parts by weight of salt gypsum and 7 parts by weight of waste sepiolite fiber, and stir at 500 rpm for 20 min to obtain solid waste cementitious material; mix 84 parts by weight of municipal solid waste incineration bottom ash and 16 parts by weight of potato starch waste liquid, and stir at 300 rpm for 10 min to obtain carbon mineralization inducer; add 20 parts by weight of sodium dodecyl sulfonate to 980 parts by weight of waste wind turbine blade alkaline washing waste liquid, and stir at 500 rpm for 10 min to obtain foaming liquid. Comparative Example 1

[0048] This comparative example is based on Example 1, except that in step S2, 12 parts by weight of solid waste cementitious material is used to replace 12 parts by weight of carbon mineralization inducer, while the other steps are the same as in Example 1. Comparative Example 2

[0049] This comparative example is based on Example 1, except that in step S2, the amount of carbon mineralization inducer is 6 parts by weight and the amount of foaming liquid is 12 parts by weight, while the other steps are the same as in Example 1. Comparative Example 3

[0050] This comparative example is based on Example 1, except that in step S1, 25 parts by weight of mineral powder are used instead of 25 parts by weight of salt gypsum, while the other steps are the same as in Example 1. Comparative Example 4

[0051] This comparative example is based on Example 1, except that in step S1, 5 parts by weight of mineral powder are used to replace 5 parts by weight of waste sepiolite fiber, while the other steps are the same as in Example 1. Comparative Example 5

[0052] This comparative example is based on Example 1, the difference being that in step S1, 16 parts by weight of municipal solid waste incineration bottom ash is used to replace 16 parts by weight of potato starch waste liquid, and the other steps are the same as in Example 1. Comparative Example 6

[0053] This comparative example is based on Example 1, except that in step S1, the amount of municipal solid waste incineration bottom ash is 70 parts by weight and the amount of potato starch waste liquid is 30 parts by weight. The other steps are the same as in Example 1. Comparative Example 7

[0054] This comparative example is based on Example 1, except that in step S1, the amount of sodium dodecyl sulfonate used is 5 parts by weight, and the amount of waste alkaline washing liquid from the waste wind turbine blades used is 995 parts by weight. Other steps are the same as in Example 1. Performance testing

[0055] Figure 1 Image of the carbon-negative solid waste-based foamed concrete obtained in Example 2; Figure 2 The images shown are SEM images of the carbon-negative solid waste-based foamed concrete obtained in Example 2. The image on the left is a SEM image at the 1 μm scale, and the image on the right is a SEM image at the 0.5 μm scale.

[0056] The wet density, compressive strength, carbon sequestration amount and carbon emission of the negative carbon solid waste-based foamed concrete obtained in Examples 1-9 and Comparative Examples 1-7 were tested. The test results are shown in Table 1 below.

[0057] Among them, wet density and compressive strength were tested according to the methods in JC / T 2777-2023 "Foamed Concrete for Highway Engineering".

[0058] Carbon sequestration: The carbon-negative solid waste-based foamed concrete was dried at 60℃ to constant weight, and the weight was recorded as m0. The dry density was calculated and recorded as ρ. Then, the dried carbon-negative solid waste-based foamed concrete was calcined at 450℃ to constant weight, and the weight was recorded as m1. Finally, the partially calcined carbon-negative solid waste-based foamed concrete was calcined at 950℃ to constant weight, and the weight was recorded as m2. The carbon sequestration amount CC (kg / m³) is then calculated. 3 =ρ(m1-m2) / m0. Three samples were taken for each group of tests, and the average value of the results was taken.

[0059] Carbon emissions: The calculation of carbon emissions includes three parts: (1) carbon emissions from the production of raw materials, denoted as CE, involving mineral powder and salt gypsum, while the carbon emissions from the production of other components are negligible; (2) carbon emissions caused by the electricity consumption of carbonization curing, denoted as Q; (3) the amount of carbon sequestration during the carbonization curing process, denoted as CC. Therefore, the carbon emissions TCE (kg / m³) 3 = CE + Q - CC.

[0060] Table 1 Wet density, compressive strength, carbon sequestration, and carbon emissions

[0061] As shown in Table 1, the solid waste-based concrete prepared by mixing solid waste cementitious materials, carbon mineralization inducers, foaming liquid and water in a specific ratio and then curing it in a specific manner has the characteristics of stable mechanical properties and negative carbon emission properties, and can be used as a green building material for highway engineering.

[0062] The embodiments described in this specific implementation are preferred embodiments of this application and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the principles of this application should be covered within the scope of protection of this application.

Claims

1. A carbon-negative solid waste-based foamed concrete for highway engineering, characterized in that, The raw materials include the following parts by weight: 60-64 parts solid waste cementitious material, 8-12 parts carbon mineralization inducer, 6-8 parts foaming liquid, and 21-22 parts water; The solid waste cementitious material includes mineral powder, salt gypsum and waste sepiolite fiber, and the weight ratio of the mineral powder, the salt gypsum and the waste sepiolite fiber is (69~71):(20~25):(5~10). The carbon mineralization inducer includes municipal solid waste incineration bottom ash and potato starch waste liquid, wherein the weight ratio of the municipal solid waste incineration bottom ash to the potato starch waste liquid is (75~90):(10~25). The foaming liquid includes sodium dodecyl sulfonate and waste alkaline washing liquid from waste wind turbine blades, with the weight ratio of sodium dodecyl sulfonate to waste alkaline washing liquid from waste wind turbine blades being (10~20):(980~990).

2. The negative carbon solid waste-based foamed concrete for highway engineering according to claim 1, characterized in that, The weight ratio of the solid waste cementitious material, the carbon mineralization inducer, the foaming liquid and the water is (61~64):(8~10):(6~8):(21~22).

3. The negative carbon type solid waste-based foamed concrete for highway engineering according to claim 1, characterized in that, In the solid waste cementitious material, the weight ratio of the mineral powder, the salt gypsum and the waste sepiolite fiber is 70:(23~25):(5~7).

4. The negative carbon type solid waste-based foamed concrete for highway engineering according to claim 1, characterized in that, The solid waste cementitious material contains S95 grade granulated blast furnace slag powder with an average particle size of 10-20 μm and a specific surface area of ​​850-950 m². 2 / kg, by weight percentage, the chemical composition of the mineral powder includes: MgO 4.0~9.0wt%, CaO 30~42wt%, SiO2 26~35wt%, Al2O3 10~18wt%, Fe2O3 0.5~2.0wt%, with the balance being other trace components; The average particle size of the salt gypsum is 3~8μm, and the specific surface area is 2000~2600m². 2 / kg, by weight percentage, the chemical composition of salt gypsum includes: 90~96wt% gypsum dihydrate, 0.5~3.0wt% chloride ions, and the balance being other trace components; The average particle size of waste sepiolite fibers is 30~80μm, and the specific surface area is 200~300m². 2 / kg, by weight percentage, the chemical composition of waste sepiolite fiber includes: sepiolite fiber 30~40wt%, pearl salt 5~15wt%, calcium carbonate 10~20wt%, free water and crystal water 8~15wt%, and the balance being other mineral impurities.

5. The negative carbon type solid waste-based foamed concrete for highway engineering according to claim 1, characterized in that, In the carbon mineralization inducer, the weight ratio of municipal solid waste incineration bottom ash to potato starch waste liquid is (83~85):(15~17).

6. The carbon-negative solid waste-based foamed concrete for highway engineering according to claim 1, characterized in that, The carbon mineralization inducer contains municipal solid waste incineration bottom ash with a loss on ignition of 12-18 wt% and an average particle size of 20-80 μm. The chemical composition of the municipal solid waste incineration bottom ash, by weight percentage, includes: organic carbon 3.2-4.7 wt%, calcium hydroxide 5-8 wt%, CaO 15-25 wt%, SiO2 20-35 wt%, Al2O3 8-15 wt%, Fe2O3 5-12 wt%, MgO 2-5 wt%, Na2O 3-8 wt%, K2O 1-4 wt%, Cl... - 1.5~5.0wt%, SO3 2~6wt%, P2O5 0.5~2.0wt%, heavy metals 0.3~1.2wt%, balance being other trace oxides and bound water; Potato starch wastewater is an organic wastewater generated during the refining of crude starch milk. By weight percentage, the chemical composition of potato starch wastewater includes: 0.8–1.2 wt% natural amino acids, 3.0–6.0 wt% residual starch and starch degradation products, 0.5–1.5 wt% protein and polypeptide fragments, 0.3–0.8 wt% organic acids, and potassium. + 0.3~0.8wt%, Mg 2+ 0.05~0.15wt%, PO4 3- 0.1~0.4wt%, Ca 2+ 0.02~0.08wt%, 0.2~0.5wt% cellulose and pectin polysaccharides, pH 4.5~6.0, balance is water.

7. The negative carbon type solid waste-based foamed concrete for highway engineering according to claim 1, characterized in that, In the foaming liquid, the weight ratio of sodium dodecyl sulfonate and waste alkaline washing liquid of discarded wind turbine blades is (15.5~16.5):(982~986).

8. The carbon-negative solid waste-based foamed concrete for highway engineering according to claim 1, characterized in that, The chemical composition of the wastewater from the alkaline washing of discarded wind turbine blades, by weight percentage, includes: 10-20 wt% sodium hydroxide, 8-12 wt% free carbon fiber, 5-15 wt% alkaline hydrolysis products of epoxy resin, 1-4 wt% water-soluble sodium silicate, 2-6 wt% short-chain polyether polyol, 0.5-3 wt% sodium bisphenol A and its oligomers, 0.3-2.0 wt% glycerol and propylene glycol, 0.2-1.0 wt% suspended fine glass fiber fragments, 0.5-2.0 wt% free Na2CO3, pH value 13-14, and the balance being water.

9. A method for preparing negative carbon solid waste-based foamed concrete for highway engineering as described in any one of claims 1 to 8, characterized in that, Includes the following steps: Solid waste cementitious materials, carbon mineralization inducers, foaming liquid and water are mixed and stirred to obtain a slurry. The slurry is then cast into a mold and carbonized to obtain the negative carbon type solid waste-based foamed concrete for highway engineering.

10. The method for preparing negative carbon solid waste-based foamed concrete for highway engineering according to claim 9, characterized in that, Includes the following steps: S1. Mix and homogenize mineral powder, salt gypsum and waste sepiolite fiber to obtain solid waste cementitious material; mix municipal solid waste incineration bottom ash with potato starch waste liquid and stir to obtain carbon mineralization inducer; add sodium dodecyl sulfonate to waste wind turbine blade alkaline washing waste liquid and stir to obtain foaming liquid. S2. Mix solid waste cementitious material, carbon mineralization inducer and water, stir to obtain slurry A; stir the foaming liquid obtained in step S1 at high speed to obtain foam, add the foam to slurry A, and fully homogenize to obtain slurry B; S3. The slurry B obtained in step S2 is poured into a mold and cured for 6-8 hours under the conditions of temperature of 30-35℃, relative humidity of 40-60%, and CO2 volume percentage concentration of 30-40% to complete carbon mineralization and obtain the negative carbon type solid waste-based foamed concrete for highway engineering.

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