Multi-source solid waste-based low-carbon geopolymer cementing material as well as preparation method and application thereof

Abstract

The invention relates to a multi-source solid waste-based low-carbon geopolymer cementing material as well as a preparation method and application thereof, and belongs to the technical field of geopolymer materials. The multi-source solid waste-based low-carbon geopolymer cementing material is prepared from the following components in parts by weight: 80 to 95 parts of curing base material, 5 to 20 parts of excitation component, 2 to 5 parts of regulation component and 0.5 to 2 parts of nano reinforcing agent. The invention also provides a preparation method and application of the multi-source solid waste-based low-carbon geopolymer cementing material. The multi-source solid waste-based low-carbon geopolymer cementing material prepared by the invention has the advantages of high-value utilization of solid waste resources, excellent mechanical and durability, low-carbon and efficient process and wide application scene, and provides an innovative solution for green building materials and circular economy.

Description

Technical Field

[0001] The present invention relates to the technical field of geopolymer materials, and in particular to a multi-source solid waste-based low-carbon geopolymer cementitious material, a preparation method thereof, and applications thereof. Background Art

[0002] Geopolymer low-carbon cementitious materials, as alkali-activated cementitious materials distinct from traditional Portland cement, are becoming a research hotspot and attracting increasing attention due to their superior mechanical properties, durability, radiation protection, frost resistance, corrosion resistance, and environmental friendliness. In recent years, the production of geopolymer cementitious materials from various industrial wastes through geopolymerization has demonstrated unique advantages. These products offer excellent mechanical properties, a simple preparation process, low energy consumption, and low carbon emissions, making them a promising alternative to ordinary Portland cement.

[0003] With the development of industrialization and infrastructure construction, the amount of industrial solid waste generated has increased annually, while overall utilization rates remain low. The accumulation of large amounts of industrial solid waste (such as fly ash, waste concrete fines, and blast furnace slag) and construction waste (such as fly ash and crushed stone) results in significant resource waste and environmental pollution. Among existing solid waste treatment technologies, geopolymers have attracted attention due to their low-carbon and environmentally friendly properties, but several challenges remain.

[0004] Patent CN113416025A discloses a method for preparing a fast-hardening, high-strength fly ash geopolymer material, the method comprising the following steps: (1) uniformly mixing fly ash and blast furnace slag to obtain a mixed powder; (2) adding an alkali activator, a nano-reinforcement agent, and water to the mixed powder and stirring the mixture uniformly, wherein a polycondensation reaction and a hydration reaction occur simultaneously during the stirring process, and a geopolymer slurry is obtained after the two reactions are completed; (3) the geopolymer slurry is poured into a mold, shaken, and allowed to stand in sequence, and then the geopolymer slurry after standing is heated and dried, and demolded to obtain a fly ash geopolymer material. Although the fly ash geopolymer prepared in the above patent can reach a compressive strength of more than 70 MPa after drying at 60-75°C for 24 hours, which is even higher than the strength of similar products formed after 28 days of curing, it still requires a long period of curing.

[0005] Patent CN116283078A discloses a clay brick powder-steel slag-fly ash-based geopolymer material, comprising clay brick powder, steel slag, fly ash, and an alkali activator. While this patent utilizes solid waste, the resulting geopolymer material is limited in strength. Furthermore, existing technologies often utilize a single activating component, limiting further improvements in material performance. Summary of the Invention

[0006] In view of the problems existing in existing low-carbon geopolymers based on solid waste, such as long-term maintenance and low strength, the present invention provides a multi-source solid waste-based low-carbon geopolymer cementitious material and its preparation method and application to solve the above problems.

[0007] The technical solutions of the present invention are as follows: In a first aspect, the present invention provides a multi-source solid waste-based low-carbon geopolymer cementitious material, comprising: 80-95 parts of a solidifying base material, 5-20 parts of an excitation component, 2-5 parts of a regulating component, and 0.5-2 parts of a nano-enhancer; The solidifying substrate comprises: 30-50 parts of recycled fine powder of waste concrete or recycled fine powder of fly ash and crushed stone, 20-30 parts of fly ash, 10-20 parts of steel slag, and 10-15 parts of clay brick powder; the activating components comprise a solid activator and a liquid activator; the solid activator is at least two of the group consisting of instant powdered sodium silicate, anhydrous sodium carbonate, and sodium hydroxide, with a dosage of 3-12 parts; the liquid activator is water glass, with a dosage of 2-8 parts.

[0008] Furthermore, the particle size D of the recycled fine powder of waste concrete or fly ash crushed stone is 90 <75 μm. Controlling the particle size of recycled fine powder of waste concrete or recycled fine powder of fly ash crushed stone can firstly improve the reaction activity. When the specific surface area of the material increases, the finer the particles (D 90 <75 μm) has a larger specific surface area, making the aluminosilicate components more easily react with alkaline activators (such as sodium hydroxide, sodium silicate), accelerating the geopolymerization process. Fine particles dissolve faster in alkaline solutions, releasing more active silica and alumina species, which is conducive to the formation of a dense three-dimensional network geopolymer structure, improving early strength and final mechanical properties. Second, it can optimize the microstructure. Fine particles can effectively fill the pores in the geopolymer matrix, reduce internal defects, increase material density, reduce porosity, and thus enhance compressive strength, impermeability and durability. The particle size distribution is concentrated (D 90 Fine powders with particle size less than 75 μm help to form a uniform gel phase, avoiding local stress concentration or weak areas caused by coarse particles. Thirdly, fine particles can reduce the internal friction resistance of the mixture, improve the fluidity and pumpability of the slurry, and facilitate pouring and molding. Appropriate fineness can balance water demand and workability, avoiding the problem of excessively fine particles (such as D 90 <50 μm) will lead to a surge in water demand or agglomeration. Fourth, after the fineness of the recycled micropowder reaches the standard, it can replace some natural raw materials (such as kaolin), reducing dependence on natural resources and conforming to the concept of circular economy. Geopolymer itself is a low-carbon cementitious material. Combined with the reuse of recycled micropowder, the carbon footprint of the production process is further reduced. Fifth, the dense microstructure can effectively block harmful ions (such as Cl⁻, SO4 2-) penetration, improving the durability of the material in a corrosive environment. The uniform distribution of fine particles helps improve the high temperature stability of the geopolymer and reduce the risk of cracking at high temperatures. However, if the particle size D 90 Too low (for example, D 90 <30 μm), the water requirement may increase due to particle agglomeration, or a higher amount of alkaline activator may be required, which needs to be solved by optimizing the ratio or dispersant. In addition, the difference in composition of recycled micropowder from different sources may affect the reaction activity, and the type and concentration of activator need to be adjusted in a targeted manner. 90 <75 μm, by enhancing reaction activity, optimizing microstructure and improving construction performance, the mechanical properties and durability of geopolymer cementitious materials are significantly improved, while achieving efficient utilization of waste resources.

[0009] Furthermore, the fly ash contains >50% silica. Controlling the silica content in fly ash to >50% effectively enhances reactivity. A high silica content provides a sufficient active silicon source for the geopolymer reaction. When combined with an alkaline activator, it rapidly forms a three-dimensional network of silicon oxide tetrahedra (SiO₄) and aluminum oxide tetrahedra (AlO₄), enhancing the material's early strength and ultimate mechanical properties. Furthermore, a high silica content accelerates gel phase formation and shortens setting time. A high SiO₂ content contributes to a denser microstructure, reducing porosity and thereby improving compressive strength and chemical resistance. Furthermore, the silica-based network is more stable at high temperatures, endowing the geopolymer with excellent high-temperature crack resistance. Furthermore, research has found that the optimal Si / Al molar ratio for geopolymers is typically between 2 and 4. A high SiO₂ content brings the fly ash's Si / Al ratio closer to the ideal range, reducing the cost and steps required to add additional silicon sources (such as silica fume). However, it is necessary to ensure that the Al2O3 content in the fly ash is appropriate, usually controlled at 15%~30%, to maintain the Si / Al balance and prevent excessive silicon from causing increased brittleness.

[0010] Furthermore, the CaO content in the steel slag is greater than 40%, and the particle size is less than 75 μm. Steel slag is rich in oxides of silicon, aluminum, and calcium. The calcium oxide in the steel slag can release alkaline substances, assisting in activating the geopolymer reaction and reducing dependence on external activators. High-calcium steel slag can simultaneously trigger the geopolymer reaction and partial hydration reaction, forming a mixed gelling system and enhancing early strength. However, when the CaO content in the steel slag is low, the geopolymer structure is dense but the early strength development is slow; as the CaO content increases, the early strength development becomes faster, and the chemical corrosion resistance of the geopolymer is improved. However, when the CaO content is high, it may lead to microcracks in the later stage due to incompatibility between the hydration products and the geopolymer structure, reducing the 28-day strength.

[0011] Furthermore, clay brick powder is made from crushed construction waste, with a particle size of less than 75 μm. The primary component of clay brick powder is aluminosilicate, whose silica and alumina phases are mostly crystalline and relatively inactive. Unactivated clay brick powder, due to its high crystallinity, primarily serves as a micro-aggregate filler. Mechanical or thermal activation disrupts the crystal structure, releasing amorphous silica and aluminum oxide, significantly increasing its reactivity and enabling it to replace 30%–50% of traditional raw materials (such as metakaolin). The particle size of clay brick powder should not be too large. Larger particles have a smaller specific surface area, slowing the dissolution rate of aluminosilicates. Only the surface portion participates in the geopolymerization reaction, making the interior less susceptible to activation by alkaline activators, resulting in incomplete reaction. Properly controlling the particle size of clay brick powder not only ensures a sufficient reaction, but also improves interfacial strength and toughness.

[0012] Furthermore, the modulus of water glass ranges from 1.5 to 2.0. Different moduli of water glass affect the alkalinity, viscosity, and silicate content of the solution. This is a key parameter that determines its stimulating effect and the properties of the geopolymer. By regulating the alkalinity, silicate content, and reaction pathway of the system, the modulus directly influences the mechanical properties, durability, and processing characteristics of the geopolymer. A higher modulus of water glass slows the reaction process, but results in a highly dense structure and high compressive strength.

[0013] Furthermore, the nano-reinforcer is a nano-silica gel with a SiO2 content greater than 50%. Nano-SiO2 is rich in silanol (Si-OH) groups on its surface and rapidly dissolves in alkaline activators, releasing active silicate groups that replenish the silicon source required for the geopolymer reaction and promote gel formation. Nanoparticles act as nucleation sites, accelerating the polycondensation reaction of the silica-alumina monomers, refining the gel phase size, and forming a more uniform and dense network structure. Nano-SiO2 also consumes some free OH⁻ groups, lowering the system pH from >13 to 12-12.5, alleviating excessive erosion of the raw materials by the high alkaline environment, and reducing pore defects. The amount of nano-reinforcer added should not be excessive, as this can cause nanoparticles to agglomerate and form stress concentration points, slowing or even decreasing the strength gain.

[0014] Furthermore, the regulating component is silicate cement or metakaolin.

[0015] In a second aspect, the present invention provides a method for preparing a multi-source solid waste-based low-carbon geopolymer cementitious material, comprising the following steps: (1) Pretreatment of solid waste raw materials: crush the components of the solidified substrate separately to obtain powder of specified particle size; (2) Mixing and activation: Add the crushed solidified substrate components into the dry powder mixer in sequence and mix at 150-180 r / min for 10-15 min; add the solid activator, nano-enhancer and regulating component in sequence, and increase the speed of the dry powder mixer to 300-350 r / min and mix for 15-20 min; finally, add the liquid activator and water and stir until the slurry is uniform; (3) Molding and strengthening: Inject the slurry into the mold and vibrate it at 2500-2800 Hz for 3-5 minutes to remove bubbles; let it stand for 20-28 hours and then perform curing in stages.

[0016] Furthermore, in step (3), the staged curing includes the following steps: Steam curing: curing at 80~90℃ for 10~15 hours to promote early hydration; Heating and drying: drying in an oven at 60-75°C for 24-48 hours to accelerate the polycondensation reaction; Closed curing at room temperature: curing under standard conditions (20±2℃, humidity ≥95%) to the designed age.

[0017] In a third aspect, the present invention provides an application of the multi-source solid waste-based low-carbon geopolymer cementitious material as a soil solidifier, building wall tiles, floor tiles and lightweight aggregate.

[0018] The beneficial effects of the present invention are: The present invention achieves high performance and low carbonization of geopolymer materials through multi-source solid waste collaborative design, excitation component optimization and nano-enhancement technology, and has both environmental protection, economic and engineering practical value. At the same time, the multi-source solid waste-based low-carbon geopolymer cementitious material prepared by the present invention has excellent mechanical properties. Through the control of the fineness of recycled micropowder, high-calcium steel slag and nano-SiO2 synergistic reinforcement, the 28-day compressive strength can reach 70~110 MPa, and the flexural strength is 8~12 MPa. At the same time, the early strength is fast: steam curing is combined with highly active excitation components, and the strength reaches 30~50 MPa in 3 days, meeting the needs of rapid construction. In addition, the multi-source solid waste-based low-carbon geopolymer cementitious material prepared by the present invention has outstanding durability; nano-SiO2 fills the pores, and the chloride ion diffusion coefficient is less than 1×10 -12 m 2 / s, and a sulfate-resistant mass loss rate of less than 0.5%. A phased curing process (steaming + drying + room temperature) reduces shrinkage cracking, achieving a drying shrinkage rate of less than 0.03%. The high-silica aluminum gel structure exhibits a residual strength of >70% at 800°C, making it suitable for high-temperature environments. In summary, the multi-source solid waste-based low-carbon geopolymer cementitious material prepared by this invention achieves high-value utilization of solid waste resources, excellent mechanical and durability properties, a low-carbon and efficient process, and a wide range of applications, providing an innovative solution for green building materials and the circular economy. DETAILED DESCRIPTION

[0019] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions in the embodiments of the present invention are clearly and completely described below. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work should fall within the scope of protection of the present invention.

[0020] Example 1 A multi-source solid waste-based low-carbon geopolymer cementitious material comprises the following components in parts by weight: 30 parts of waste concrete fine powder, 20 parts of fly ash, 20 parts of steel slag, 10 parts of clay brick powder, 3 parts of instant powdered sodium silicate, 5 parts of sodium hydroxide, 3 parts of water glass, 2 parts of Portland cement, 1 part of nano-silica gel, and 70 parts of water.

[0021] The preparation method is as follows: (1) Pretreatment of solid waste raw materials: crush waste concrete powder, fly ash, steel slag and clay brick powder respectively. The particle size of the crushed waste concrete powder is D 90 =70 μm; fly ash particle size D 90 =60 μm; slag particle size D 90 =65 μm; Clay brick powder particle size D 90 =60 μm.

[0022] (2) Mixing and activation: Add the crushed waste concrete powder, fly ash, steel slag and clay brick powder into the dry powder mixer in sequence and mix at 150 r / min for 10 min; add instant powdered sodium silicate, sodium hydroxide, nano-silica gel and silicate cement in sequence, and increase the speed of the dry powder mixer to 300 r / min and mix for 15 min; finally, add water glass and water and stir until the slurry is uniform; (3) Molding and strengthening: The slurry is injected into the mold (a triple steel mold of 40 mm × 40 mm × 160 mm), and vibrated at 2500 Hz for 3 to 5 minutes to remove bubbles; after standing for 20 to 28 hours, curing is carried out in stages.

[0023] Steam curing: curing at 80°C for 12 hours to promote early hydration; Heating and drying: drying in an oven at 60°C for 24 hours to accelerate the polycondensation reaction; After curing for 24 hours, the mold is removed and the sample is placed in a standard curing room for closed curing at room temperature: curing under standard conditions (20±2℃, humidity ≥95%) until the design age.

[0024] High strength: compressive strength ≥5 MPa after 7 days, ≥50 MPa after 28 days, ≥70 MPa after 90 days; Rapid hardening: The strength reaches 70% of the design strength 24 hours after steam curing.

[0025] Example 2 A multi-source solid waste-based low-carbon geopolymer cementitious material comprises the following components in parts by weight: 40 parts of waste concrete fine powder, 25 parts of fly ash, 15 parts of steel slag, 10 parts of clay brick powder, 3 parts of instant powdered sodium silicate, 5 parts of sodium hydroxide, 3 parts of water glass, 2 parts of Portland cement, 1 part of nano-silica gel, and 70 parts of water.

[0026] The preparation method is as follows: (1) Pretreatment of solid waste raw materials: crush waste concrete powder, fly ash, steel slag and clay brick powder respectively. The particle size of the crushed waste concrete powder is D 90 =70 μm; fly ash particle size D 90 =60 μm; slag particle size D 90 =65 μm; Clay brick powder particle size D 90 =60 μm.

[0027] (2) Mixing and activation: Add the crushed waste concrete powder, fly ash, steel slag and clay brick powder into the dry powder mixer in sequence and mix at 150 r / min for 10 min; add instant powdered sodium silicate, sodium hydroxide, nano-silica gel and silicate cement in sequence, and increase the speed of the dry powder mixer to 300 r / min and mix for 15 min; finally, add water glass and water and stir until the slurry is uniform; (3) Molding and strengthening: The slurry is injected into the mold (a triple steel mold of 40 mm × 40 mm × 160 mm), and vibrated at 2500 Hz for 3 to 5 minutes to remove bubbles; after standing for 20 to 28 hours, curing is carried out in stages.

[0028] Steam curing: curing at 80°C for 12 hours to promote early hydration; Heating and drying: drying in an oven at 60°C for 24 hours to accelerate the polycondensation reaction; After curing for 24 hours, the mold is removed and the sample is placed in a standard curing room for closed curing at room temperature: standard conditions (20±2℃, humidity ≥95%) are maintained until the design age.

[0029] High strength: compressive strength ≥5 MPa after 7 days, ≥50 MPa after 28 days, ≥70 MPa after 90 days; Rapid hardening: The strength reaches 70% of the design strength 24 hours after steam curing.

[0030] Example 3 A multi-source solid waste-based low-carbon geopolymer cementitious material comprises the following components in parts by weight: 35 parts of waste concrete fine powder, 30 parts of fly ash, 15 parts of steel slag, 15 parts of clay brick powder, 3 parts of instant powdered sodium silicate, 5 parts of sodium hydroxide, 3 parts of water glass, 2 parts of Portland cement, 1 part of nano-silica gel, and 70 parts of water.

[0031] The preparation method is as follows: (1) Pretreatment of solid waste raw materials: crush waste concrete powder, fly ash, steel slag and clay brick powder respectively. The particle size of the crushed waste concrete powder is D 90 =70 μm; fly ash particle size D 90 =60 μm; slag particle size D 90 =65 μm; Clay brick powder particle size D 90 =60 μm.

[0032] (2) Mixing and activation: Add the crushed waste concrete powder, fly ash, steel slag and clay brick powder into the dry powder mixer in sequence and mix at 150 r / min for 10 min; add instant powdered sodium silicate, sodium hydroxide, nano-silica gel and silicate cement in sequence, and increase the speed of the dry powder mixer to 300 r / min and mix for 15 min; finally, add water glass and water and stir until the slurry is uniform; (3) Molding and strengthening: The slurry is injected into the mold (a triple steel mold of 40 mm × 40 mm × 160 mm), and vibrated at 2500 Hz for 3 to 5 minutes to remove bubbles; after standing for 20 to 28 hours, curing is carried out in stages.

[0033] Steam curing: curing at 80°C for 12 hours to promote early hydration; Heating and drying: drying in an oven at 60°C for 24 hours to accelerate the polycondensation reaction; After curing for 24 hours, the mold is removed and the sample is placed in a standard curing room for closed curing at room temperature: standard conditions (20±2℃, humidity ≥95%) are maintained until the design age.

[0034] High strength: compressive strength ≥5 MPa after 7 days, ≥50 MPa after 28 days, ≥70 MPa after 90 days; Rapid hardening: The strength reaches 70% of the design strength 24 hours after steam curing.

[0035] Example 4 A multi-source solid waste-based low-carbon geopolymer cementitious material comprises the following components in parts by weight: 50 parts of waste concrete fine powder, 20 parts of fly ash, 10 parts of steel slag, 10 parts of clay brick powder, 3 parts of instant powdered sodium silicate, 5 parts of sodium hydroxide, 3 parts of water glass, 2 parts of Portland cement, 1 part of nano-silica gel, and 70 parts of water.

[0036] The preparation method is as follows: (1) Pretreatment of solid waste raw materials: crush waste concrete powder, fly ash, steel slag and clay brick powder respectively. The particle size of the crushed waste concrete powder is D 90 =70 μm; fly ash particle size D 90 =60 μm; slag particle size D 90 =65 μm; Clay brick powder particle size D 90 =60 μm.

[0037] (2) Mixing and activation: Add the crushed waste concrete powder, fly ash, steel slag and clay brick powder into the dry powder mixer in sequence and mix at 150 r / min for 10 min; add instant powdered sodium silicate, sodium hydroxide, nano-silica gel and silicate cement in sequence, and increase the speed of the dry powder mixer to 300 r / min and mix for 15 min; finally, add water glass and water and stir until the slurry is uniform; (3) Molding and strengthening: The slurry is injected into the mold (a triple steel mold of 40 mm × 40 mm × 160 mm), and vibrated at 2500 Hz for 3 to 5 minutes to remove bubbles; after standing for 20 to 28 hours, curing is carried out in stages.

[0038] Steam curing: curing at 80°C for 12 hours to promote early hydration; Heating and drying: drying in an oven at 60°C for 24 hours to accelerate the polycondensation reaction; After curing for 24 hours, the mold is removed and the sample is placed in a standard curing room for closed curing at room temperature: standard conditions (20±2℃, humidity ≥95%) are maintained until the design age.

[0039] High strength: compressive strength ≥5 MPa after 7 days, ≥50 MPa after 28 days, ≥70 MPa after 90 days; Rapid hardening: The strength reaches 70% of the design strength 24 hours after steam curing.

[0040] Example 5 A multi-source solid waste-based low-carbon geopolymer cementitious material comprises the following components in parts by weight: 45 parts of waste concrete fine powder, 20 parts of fly ash, 15 parts of steel slag, 10 parts of clay brick powder, 3 parts of instant powdered sodium silicate, 5 parts of sodium hydroxide, 3 parts of water glass, 2 parts of Portland cement, 1 part of nano-silica gel, and 70 parts of water.

[0041] The preparation method is as follows: (1) Pretreatment of solid waste raw materials: crush waste concrete powder, fly ash, steel slag and clay brick powder respectively. The particle size of the crushed waste concrete powder is D 90=70 μm; fly ash particle size D 90 =60 μm; slag particle size D 90 =65 μm; Clay brick powder particle size D 90 =60 μm.

[0042] (2) Mixing and activation: Add the crushed waste concrete powder, fly ash, steel slag and clay brick powder into the dry powder mixer in sequence and mix at 150 r / min for 10 min; add instant powdered sodium silicate, sodium hydroxide, nano-silica gel and silicate cement in sequence, and increase the speed of the dry powder mixer to 300 r / min and mix for 15 min; finally, add water glass and water and stir until the slurry is uniform; (3) Molding and strengthening: The slurry is injected into the mold (a triple steel mold of 40 mm × 40 mm × 160 mm), and vibrated at 2500 Hz for 3 to 5 minutes to remove bubbles; after standing for 20 to 28 hours, curing is carried out in stages.

[0043] Steam curing: curing at 80°C for 12 hours to promote early hydration; Heating and drying: drying in an oven at 60°C for 24 hours to accelerate the polycondensation reaction; After curing for 24 hours, the mold is removed and the sample is placed in a standard curing room for closed curing at room temperature: standard conditions (20±2℃, humidity ≥95%) are maintained until the design age.

[0044] High strength: compressive strength ≥5 MPa after 7 days, ≥50 MPa after 28 days, ≥70 MPa after 90 days; Rapid hardening: The strength reaches 70% of the design strength 24 hours after steam curing.

[0045] Test Case Referring to the test method of GB / T 17671-2021, the unconfined compressive strength test of the geopolymer cementitious materials prepared in Examples 1 to 5 was carried out. The test results are shown in Table 1 below: Table 1 - Test results

[0046] Although the present invention has been described in detail by way of preferred embodiments, the present invention is not limited thereto. Without departing from the spirit and substance of the present invention, persons of ordinary skill in the art may make various equivalent modifications or substitutions to the embodiments of the present invention, and such modifications or substitutions shall be within the scope of the present invention. Any changes or substitutions that can be readily conceived by persons skilled in the art within the technical scope disclosed in the present invention shall be within the scope of protection of the present invention.

Claims

1. A multi-source solid waste-based low-carbon geopolymer cementitious material, characterized in that: include: 80-95 parts of curing base material, 5-20 parts of excitation component, 2-5 parts of regulating component, 0.5-2 parts of nano-enhancer; The solidifying substrate comprises: 30-50 parts of recycled fine powder of waste concrete or recycled fine powder of fly ash and crushed stone, 20-30 parts of fly ash, 10-20 parts of steel slag, and 10-15 parts of clay brick powder; the activating components comprise a solid activator and a liquid activator; the solid activator is at least two of the group consisting of instant powdered sodium silicate, anhydrous sodium carbonate, and sodium hydroxide, with a dosage of 3-12 parts; the liquid activator is water glass, with a dosage of 2-8 parts.

2. The multi-source solid waste-based low-carbon geopolymer cementitious material according to claim 1, characterized in that: Particle size D of recycled fine powder of waste concrete or recycled fine powder of fly ash crushed stone 90 <75 μm.

3. The multi-source solid waste-based low-carbon geopolymer cementitious material according to claim 1, characterized in that: The silicon dioxide content in the fly ash is greater than 50%.

4. The multi-source solid waste-based low-carbon geopolymer cementitious material according to claim 1, wherein: Clay brick powder is made by crushing construction waste, with a particle size of less than 75 μm.

5. The multi-source solid waste-based low-carbon geopolymer cementitious material according to claim 1, characterized in that: The modulus of water glass is 1.5~2.

0.

6. The multi-source solid waste-based low-carbon geopolymer cementitious material according to claim 1, wherein: The nano-enhancer is nano-silica gel with SiO2 content greater than 50%.

7. The multi-source solid waste-based low-carbon geopolymer cementitious material according to claim 1, characterized in that: The regulating component is silicate cement or metakaolin.

8. A method for preparing the multi-source solid waste-based low-carbon geopolymer cementitious material according to claim 1, characterized in that: The following steps are involved: (1) Pretreatment of solid waste raw materials: crush the components of the solidified substrate separately to obtain powder of specified particle size; (2) Mixing and activation: Add the crushed solidified substrate components into the dry powder mixer in sequence and mix at 150-180 r / min for 10-15 min; add the solid activator, nano-enhancer and regulating component in sequence, and increase the speed of the dry powder mixer to 300-350 r / min and mix for 15-20 min; finally, add the liquid activator and water and stir until the slurry is uniform; (3) Molding and strengthening: Inject the slurry into the mold and vibrate at 2500-2800 Hz for 3-5 minutes to remove bubbles; let it stand for 20-28 hours and then perform curing in stages.

9. The method according to claim 8, wherein In step (3), the staged curing includes the following steps: Steam curing: curing at 80~90℃ for 10~15 hours; Heat drying: Dry in an oven at 60~75℃ for 24~48 hours; Closed curing at room temperature: curing to the design age at 20±2℃ and humidity ≥95%.

10. Use of the multi-source solid waste-based low-carbon geopolymer cementitious material as claimed in claim 1 as a soil solidifier, building wall bricks, floor tiles and lightweight aggregate.

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