Red mud-based solid waste cementing material and preparation method thereof
By using a multi-scale, multi-component, surface-functionalized fiber hybrid system and composite activators, the problem of weak toughness and strength of red mud-based cementitious materials has been solved, resulting in red mud-based cementitious materials with high compressive/flexural strength and excellent durability, thus improving their comprehensive utilization efficiency.
Patent Information
- Application Number
- CN202511193410.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-25
- Publication Date
- 2025-11-18
AI Technical Summary
Existing red mud-based cementitious materials have weak toughness and strength, and the interface between fibers and concrete matrix is weak, resulting in poor improvement effects. Furthermore, traditional fiber incorporation methods have failed to fully release their cementing potential.
A multi-scale, multi-component, and surface-functionalized fiber hybrid system is adopted. By using composite activators and modified fibers, a multi-level synergistic toughening mechanism is constructed, including short fibers bridging microcracks, medium fibers crossing medium cracks, and long fibers bearing the main cracks. Combined with the synergistic effect of sodium silicate, nano-sized metakaolin, and coated sodium carbonate, the activation and interfacial bonding strength are improved.
It significantly improves the compressive/flexural strength and durability of red mud-based cementitious materials, realizes the synergistic effect of red mud, desulfurized gypsum and slag, reduces the cost of admixtures, reduces solid waste accumulation and environmental pollution, and improves the comprehensive utilization efficiency of materials.
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Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of solid waste resource utilization, and particularly relates to a red mud-based solid waste cementing material and a preparation method thereof. BACKGROUND
[0002] At present, the utilization rate of solid waste in China is low, and the stock is large. Traditional utilization methods such as filling are difficult to efficiently absorb in large quantities, and are prone to cause secondary pollution. Therefore, the resource utilization of solid waste is imminent. It is a research hotspot to prepare cementing materials by using red mud. However, the overall efficiency of conventional single alkali activation is low, and the cementing potential of red mud cannot be fully released, resulting in weak strength and toughness of the material matrix. The use of fibers is the main measure to improve the toughness, but the fibers are usually directly added or simply mixed without considering the influence of the process and the use of fiber size, resulting in weak interface bonding between the fiber and the concrete matrix and poor improvement effect. Therefore, it is urgent to optimize the performance of the red mud-based solid waste cementing material to improve the comprehensive utilization efficiency. SUMMARY
[0003] In view of the problems and deficiencies in the prior art, the purpose of the present application is to provide a red mud-based solid waste cementing material and a preparation method thereof.
[0004] To achieve the above purpose, the present application adopts the following technical scheme:
[0005] The present application provides a red mud-based solid waste cementing material, which is composed of the following raw materials by weight: 45-55 parts of red mud, 8-12 parts of desulfurization gypsum, 25-30 parts of slag powder, 5-10 parts of composite activator, and 6-8 parts of mixed fibers.
[0006] Preferably, the preparation method of the coated sodium carbonate is as follows: a 34-36℃ sodium carbonate saturated solution is atomized and sprayed on the surface of a 0-4℃ silica sol solution, stirred, and filtered to obtain microsphere particles. The microsphere particles are dried to obtain the coated sodium carbonate.
[0007] More preferably, the concentration of the silica sol solution is 10%-15%.
[0008] Preferably, the mass ratio of sodium silicate powder, nano-scale metakaolin, sodium hydroxide, and coated sodium carbonate in the composite activator is (6-9):(2-4):(1-3):(18-22).
[0009] Preferably, the mixed fibers are a mixture of modified basalt fibers and modified biomass fibers.
[0010] Preferably, the modified basalt fiber is compounded by modified basalt short fiber, modified basalt medium fiber and modified basalt long fiber in a mass ratio of 3: (3-5) : (1-2).
[0011] Preferably, the preparation method of the modified basalt short fiber is that the basalt short fiber is modified by silane coupling agent.
[0012] More preferably, the preparation method of the modified basalt short fiber is that the basalt short fiber is impregnated by silane coupling agent.
[0013] Preferably, the preparation method of the modified basalt medium fiber and the modified basalt long fiber is that the basalt medium fiber or / and the basalt long fiber is modified by silane coupling agent first, and then nano-SiO2 particles are loaded on the surface of the basalt medium fiber or / and the basalt long fiber modified by silane coupling agent.
[0014] More preferably, the preparation method of the modified basalt medium fiber is that the basalt medium fiber is impregnated by silane coupling agent, and then the impregnated basalt medium fiber is put into nano-SiO2 emulsion, ultrasonic dispersed for 5-8 min, and then treated by standing for 12-16 h. The preparation method of the modified basalt long fiber is that the basalt long fiber is impregnated by silane coupling agent, and then the impregnated basalt long fiber is put into nano-SiO2 emulsion, ultrasonic dispersed for 5-8 min, and then treated by standing for 12-16 h.
[0015] More preferably, the solid content of the SiO2 emulsion is 18%-20%.
[0016] Preferably, the length of the modified basalt short fiber is 1-3 mm, the length of the modified basalt medium fiber is 3-6 mm, and the length of the modified basalt long fiber is 6-9 mm.
[0017] Preferably, the modified biomass fiber is compounded by modified biomass short fiber, modified biomass medium fiber and modified biomass long fiber in a mass ratio of 3: (3-5) : (1-2).
[0018] Preferably, the preparation method of the modified biomass short fiber, the modified biomass medium fiber and the modified biomass long fiber is that the biomass short fiber or / and the biomass medium fiber or / and the biomass long fiber is soaked in alkaline solution at 60-80℃ for 16-28 h, then dopamine is added into the alkaline solution, mixed, and then hydrogen peroxide solution is added, and soaked at 40-60℃ for 16-28 h.
[0019] More preferably, the alkaline solution is sodium hydroxide solution.
[0020] More preferably, the concentration of the sodium hydroxide solution is 3-5%.
[0021] More preferably, the concentration of the hydrogen peroxide solution is 3-5%.
[0022] Preferably, the dosage of the dopamine is 1-2% of the mass of the alkaline solution.
[0023] Preferably, the biomass fiber is sisal fiber or bamboo fiber.
[0024] Preferably, the mass ratio of the modified basalt fiber to the modified biomass fiber in the mixed fiber is 6-8:2-4.
[0025] Preferably, the red mud is dried red mud particles, and the particle size of the powder is 400-600m 2 / kg; the mineral slag powder is S95 grade mineral powder.
[0026] The second aspect of the present application provides a preparation method of the red mud-based solid waste cementing material of the first aspect, comprising the following steps: uniformly mixing red mud, desulfurization gypsum, mineral slag powder, composite activator and mixed fiber, and then grinding the mixture to obtain the red mud-based solid waste cementing material.
[0027] Compared with the prior art, the present application has the following beneficial effects:
[0028] (1) The present application constructs a multi-level synergistic toughening mechanism and strength enhancement mechanism of ''short fiber bridging micro-cracks, medium fiber spanning medium cracks, and long fiber bearing main cracks'' through the activation system and the mixed system of multi-scale, multi-component and surface functionalized fibers; and develops a green building material with high compressive / flexural strength, excellent durability and significant environmental benefits. The synergistic effect and resource utilization of red mud, desulfurization gypsum and slag are realized, the cost of the admixture is significantly reduced, and the accumulation of solid waste and environmental pollution are reduced.
[0029] (2) By compounding the composite activator, sodium silicate is used to provide active activation, nano-partial kaolin is used to provide early strength and supplement active aluminum source active substances, coated sodium carbonate is used to provide sustained alkali release, the activation process is prolonged, the late strength reduction is reduced, sodium hydroxide is used to provide strong alkaline substances in the early stage to produce a synergistic effect with silicon-aluminum active substances to improve the activity of red mud.
[0030] (3) By functionalizing the multi-scale mixed fiber and strengthening the interface through surface treatment, the effective inhibition and energy dissipation of ''micro-macro'' cracks are realized, and the flexural resistance of the material is significantly improved.
[0031] (4) By modifying basalt fiber silane coupling agent infiltration, improve the adhesion strength and surface of basalt fiber and matrix, by further using silica attached to the long fiber, improve its reaction with active substances in red mud, improve the interface strength. If lack of modification, basalt fiber can only be incorporated as inert fiber, its modification is not obvious.
[0032] (5) By modifying biomass fiber, using alkali solution for surface treatment, improve the surface roughness of plant fiber, improve its adhesion to matrix, further use dopamine oxidation self polymerization performance on the surface of plant to form a coating, improve its toughness, improve its modification effect on cementitious materials. DETAILED DESCRIPTION
[0033] In order to make the purpose, technical scheme and advantages of the present application more clear, the following will be further described in detail by examples. It should be understood that the specific examples described here are only used to explain the present application, and not to limit the present application.
[0034] Example 1: Discussion on the type of sodium carbonate in composite activator
[0035] In order to verify the influence of the type of sodium carbonate in composite activator on the performance of red mud based solid waste cementitious material, the present application carries out example 1-1, comparative example 1-1 and comparative example 1-2. The specific content of example 1-1, comparative example 1-1 and comparative example 1-2 is as follows:
[0036] Example 1-1:
[0037] A kind of red mud based solid waste cementitious material, which is composed of the following raw materials by weight: red mud 50 parts, desulfurization gypsum 10 parts, slag powder 28 parts, composite activator 8 parts, mixed fiber 7 parts. The red mud is dried after the red mud particles powder to particle size of 580m 2 / kg; the slag powder is S95 grade mine powder. The composite activator is prepared by mixing sodium silicate powder (modulus is 2.0), nano grade metakaolin, sodium hydroxide, coated sodium carbonate according to the mass ratio of 8:3:2:20. The mixed fiber is prepared by mixing modified basalt fiber and modified biomass fiber according to the mass ratio of 7:3.
[0038] Among them, the preparation method of coated sodium carbonate is: ① Dissolve sodium carbonate in water at 35.4℃, keep the water temperature at 35.4℃, form a saturated solution. ② Control the temperature of 12% silicic acid sol solution at 0℃. ③ Atomize the sodium carbonate solution and spray it on the surface of the silicic acid sol solution, and continuously stir, filter to form microspheres, and dry at 78℃ to obtain coated sodium carbonate.
[0039] The preparation method of the modified basalt fiber is that the modified basalt fiber is compounded by modified basalt short fibers (1-3 mm), modified basalt medium fibers (3-6 mm) and modified basalt long fibers (6-9 mm) in a mass ratio of 3:4:1.2. The preparation method of the modified basalt short fiber is that the basalt short fiber is soaked in a silane coupling agent for 7 h; the preparation method of the modified basalt medium fiber is that the basalt medium fiber is soaked in a silane coupling agent for 7 h, and then the soaked basalt medium fiber is placed in an excessive nano-SiO2 emulsion, ultrasonically dispersed for 6 min, and then left to stand for 14 h; and the preparation method of the modified basalt long fiber is that the basalt long fiber is soaked in a silane coupling agent for 7 h, and then the soaked basalt long fiber is placed in an excessive nano-SiO2 emulsion, ultrasonically dispersed for 6 min, and then left to stand for 14 h. The nano-SiO2 emulsion has a solid content of 20%.
[0040] The preparation method of the modified biomass fiber is that the modified biomass fiber is compounded by modified biomass short fibers, modified biomass medium fibers and modified biomass long fibers in a mass ratio of 3:4:1.2. The preparation method of the modified biomass short fiber is that the biomass short fiber is soaked in an excessive 4% sodium hydroxide solution at 70℃ for 24 h, then dopamine is added to the sodium hydroxide solution, stirred uniformly, 4% hydrogen peroxide solution is added, and the mixture is soaked at 58℃ for 24 h, then drained and dried at 90℃; the amount of dopamine is 1.5% of the mass of the sodium hydroxide solution; and the preparation methods of the modified biomass medium fiber and the modified biomass long fiber are the same as the preparation method of the modified biomass short fiber. The biomass fiber is a bamboo fiber.
[0041] The preparation method of the above-mentioned red mud-based solid waste cementitious material is that red mud, desulfurization gypsum, slag powder, a composite activator and mixed fibers are uniformly mixed, then taken out after being mixed in a ball mill for 6 min, and thus the red mud-based solid waste cementitious material is obtained.
[0042] Comparative Example 1-1:
[0043] The content of Comparative Example 1-1 is basically the same as that of Example 1-1, except that no coated sodium carbonate is added in the composite activator; that is, the composite activator is prepared by mixing sodium silicate powder (modulus is 2.0), nano-scale metakaolin and sodium hydroxide in a mass ratio of 8:3:2.
[0044] Comparative Example 1-2:
[0045] The content of Comparative Example 1-2 is basically the same as that of Example 1-1, except that the composite activator is prepared by mixing sodium silicate powder (modulus 2.0), nano-polar kaolin, sodium hydroxide and common sodium carbonate in a mass ratio of 8:3:2:20 instead of coated sodium carbonate.
[0046] The activity index, mortar compressive strength growth ratio and mortar flexural strength ratio of the cementitious materials prepared in Example 1-1, Comparative Example 1-1 and Comparative Example 1-2 were detected according to the provisions of JG / T 486-2015 Composite Admixture for Concrete, and the results are shown in Table 1.
[0047] Table 1 Performance of the cementitious materials prepared in Example 1-1, Comparative Example 1-1 and Comparative Example 1-2
[0048]
[0049] As can be seen from Table 1, without the addition of coated sodium carbonate, the sustained activation effect cannot be achieved, the activity index decreases significantly, and the compressive strength growth ratio also decreases significantly. When sodium carbonate is used to replace coated sodium carbonate, the 7d activity index increases, but the 28d activity index decreases significantly, and the flexural strength is adversely affected. This shows that the use of coated sodium carbonate has a significant effect, and the sustained activation effect of coated sodium carbonate can prolong the activation time of the admixture and improve the adhesion strength of the admixture and the fiber, which is beneficial to improving the compressive strength of the concrete.
[0050] Example 2: Discussion on mixed fiber modification
[0051] In order to verify the influence of mixed fiber modification on the performance of red mud-based solid waste cementitious material, the present application carries out Comparative Example 2-1 and Comparative Example 2-2. The specific content of Comparative Example 2-1 and Comparative Example 2-2 is as follows:
[0052] Comparative Example 2-1:
[0053] The content of Comparative Example 2-1 is basically the same as that of Example 1-1, except that the mixed fiber is unmodified basalt fiber, i.e. the mixed fiber is compounded by basalt short fiber, basalt medium fiber and basalt long fiber in a mass ratio of 3:4:1.2.
[0054] Comparative Example 2-2:
[0055] The content of Comparative Example 2-2 is basically the same as that of Example 1-1, except that the mixed fiber is unmodified biomass fiber, i.e. the mixed fiber is compounded by biomass short fiber, biomass medium fiber and biomass long fiber in a mass ratio of 3:4:1.2.
[0056] Table 2 Performance of the cementitious materials prepared in Example 1-1, Comparative Example 2-1 and Comparative Example 2-2
[0057]
[0058] As can be seen from Table 2, when the fibers are not modified, the activity index of the cementitious material decreases significantly, and the compressive strength growth ratio and the flexural strength ratio decrease. Moreover, the biomass fiber (bamboo fiber) has a greater negative impact on the performance of the material. When the mixed fibers of the present application are modified basalt fibers and modified biomass fibers, the activity index, the compressive strength growth ratio and the flexural strength ratio of the cementitious material prepared are all better than those of Comparative Example 2-1 and Comparative Example 2-2. This shows that the performance of the cementitious material is significantly improved by the present application.
[0059] Example 3: Mixed fiber length exploration
[0060] In order to verify the influence of the length of the mixed fibers on the performance of the red mud-based solid waste cementitious material, the present application carries out Comparative Example 3-1 and Comparative Example 3-2. The specific contents of Comparative Example 3-1 and Comparative Example 3-2 are as follows:
[0061] Comparative Example 3-1:
[0062] The content of Comparative Example 3-1 is basically the same as that of Example 1-1, except that the mixed fibers are modified basalt short fibers.
[0063] Comparative Example 3-2:
[0064] The content of Comparative Example 3-2 is basically the same as that of Example 1-1, except that the mixed fibers are modified biomass short fibers.
[0065] Table 3 Performance of the cementitious materials prepared in Example 1-1, Comparative Example 3-1 and Comparative Example 3-2
[0066]
[0067] As can be seen from Table 3, when only short fibers are used, the performance decreases significantly due to the lack of multi-stage synergistic toughening effect, especially the flexural strength ratio decreases significantly.
[0068] Example 4:
[0069] A red mud-based solid waste cementitious material is composed of the following raw materials in parts by weight: 45 parts of red mud, 12 parts of desulfurized gypsum, 25 parts of slag powder, 10 parts of composite activator and 6 parts of mixed fibers. The red mud is obtained by drying red mud particles to a powder with a particle size of 600 m 2The slag powder is S95 grade mineral powder. The composite activator is prepared by mixing sodium silicate powder (modulus 1.8), nano-grade metakaolin, sodium hydroxide and coated sodium carbonate at a mass ratio of 9:2:3:18.
[0070] The preparation method of the coated sodium carbonate is as follows: ① Dissolve sodium carbonate in water at 36℃, keep the water temperature at 36℃, and form a saturated solution. ② Control the temperature of 10% silicic acid sol solution at 4℃. ③ Spray the sodium carbonate solution on the surface of the silicic acid sol solution after atomization, and continuously stir, filter to form microsphere particles, and dry at 60℃ to obtain the coated sodium carbonate.
[0071] The preparation method of the modified basalt fiber is as follows: the modified basalt fiber is prepared by compounding modified basalt short fiber (1-3mm), modified basalt medium fiber (3-6mm) and modified basalt long fiber (6-9mm) at a mass ratio of 3:3:2. The preparation method of the modified basalt short fiber is as follows: the basalt short fiber is soaked in silane coupling agent for 6h. The preparation method of the modified basalt medium fiber is as follows: the basalt medium fiber is soaked in silane coupling agent for 6h, and then placed in excess nano-SiO2 emulsion, ultrasonically dispersed for 8min, and then left to stand for 12h. The preparation method of the modified basalt long fiber is as follows: the basalt long fiber is soaked in silane coupling agent for 6h, and then placed in excess nano-SiO2 emulsion, ultrasonically dispersed for 8min, and then left to stand for 12h. The nano-SiO2 emulsion contains 20% solid content.
[0072] The preparation method of the modified biomass fiber is as follows: the modified biomass fiber is prepared by compounding modified biomass short fiber, modified biomass medium fiber and modified biomass long fiber at a mass ratio of 3:4:1.2. The preparation method of the modified biomass short fiber is as follows: the biomass short fiber is soaked in excess 5% sodium hydroxide solution at 60℃ for 24h, then dopamine is added to the sodium hydroxide solution, stirred uniformly, 3% hydrogen peroxide solution is added, and then soaked at 60℃ for 24h, drained and dried at 80℃. The amount of dopamine is 2% of the mass of the sodium hydroxide solution. The preparation methods of the modified biomass medium fiber and the modified biomass long fiber are the same as the preparation method of the modified biomass short fiber. The biomass fiber is bamboo fiber.
[0073] The preparation method of the above-mentioned red mud-based solid waste cementitious material is as follows: mix red mud, desulfurization gypsum, slag powder, composite activator and mixed fiber uniformly, mix in a ball mill for 5min, and then take out to obtain the red mud-based solid waste cementitious material.
[0074] The 7d activity index of the cementitious material of the present example is 105%, the 28d activity index is 120%, the mortar compressive strength growth ratio is 108%, and the mortar flexural strength ratio is 125% according to the provisions of JG / T 486-2015 "Composite Admixture for Concrete".
[0075] Example 5
[0076] A red mud-based solid waste cementitious material is composed of the following raw materials by weight: 55 parts of red mud, 8 parts of desulfurization gypsum, 30 parts of slag powder, 5 parts of composite activator, and 8 parts of mixed fiber. The red mud is dried red mud particles to a powder with a particle size of 400m 2 / kg; the slag powder is S95 grade. The composite activator is prepared by mixing sodium silicate powder (modulus 2.2), nano-partial kaolin, sodium hydroxide, and coated sodium carbonate in a mass ratio of 6:4:1:22. The mixed fiber is prepared by mixing modified basalt fiber and modified biomass fiber in a mass ratio of 8:2.
[0077] The preparation method of the coated sodium carbonate is as follows: ①Dissolve sodium carbonate in water at 34℃, keep the water temperature at 34℃, and form a saturated solution. ②Control the temperature of the 15% silicic acid sol solution at 2℃. ③Atomize the sodium carbonate solution and spray it on the surface of the silicic acid sol solution, and continuously stir to form microsphere particles, which are dried at 80℃ to obtain the coated sodium carbonate.
[0078] The preparation method of the modified basalt fiber is as follows: the modified basalt fiber is prepared by compounding modified basalt short fiber (1-3mm), modified basalt medium fiber (3-6mm), and modified basalt long fiber (6-9mm) in a mass ratio of 3:5:1. The preparation method of the modified basalt short fiber is as follows: soak the basalt short fiber in silane coupling agent for 8h; the preparation method of the modified basalt medium fiber is as follows: soak the basalt medium fiber in silane coupling agent for 8h, and then put it into excess nano-SiO2 emulsion, ultrasonic dispersion for 5min, and then stand for 16h; the preparation method of the modified basalt long fiber is as follows: soak the basalt long fiber in silane coupling agent for 8h, and then put it into excess nano-SiO2 emulsion, ultrasonic dispersion for 5min, and then stand for 16h; the solid content of the nano-SiO2 emulsion is 19%.
[0079] The preparation method of the modified biomass fiber is that the modified biomass fiber is compounded by modified biomass short fibers, modified biomass medium fibers and modified biomass long fibers according to a mass ratio of 3:4:1.2. The preparation method of the modified biomass short fibers is that the biomass short fibers are soaked in an excessive 3% sodium hydroxide solution at 80 DEG C for 24 hours, then dopamine is added to the sodium hydroxide solution, and after stirring, 5% hydrogen peroxide solution is added, and the mixture is soaked at 40 DEG C for 24 hours, then drained and dried at 120 DEG C; the amount of dopamine is 1% of the mass of the sodium hydroxide solution; the preparation methods of the modified biomass medium fibers and the modified biomass long fibers are the same as the preparation method of the modified biomass short fibers. The biomass fiber is hemp fiber.
[0080] The preparation method of the above-mentioned red mud-based solid waste cementitious material is that red mud, desulfurization gypsum, slag powder, composite activator and mixed fibers are uniformly mixed, then taken out after mixing in a ball mill for 8 minutes, and the red mud-based solid waste cementitious material is obtained.
[0081] According to the provisions of JG / T 486-2015 "Composite Admixture for Concrete", the 7d activity index of the cementitious material of the embodiment is 102%, the 28d activity index is 118%, the mortar compressive strength growth ratio is 112%, and the mortar flexural strength ratio is 127%.
[0082] The above examples are only used to illustrate the technical solutions of the present application, and are not intended to limit the protection scope of the present application. Based on the idea of the present application, those skilled in the art can modify or equivalently replace the technical solutions of the present application without departing from the essence and scope of the present application.
Claims
1. A red mud-based solid waste cementitious material, characterized in that, It is composed of the following raw materials in parts by weight: 45-55 parts red mud, 8-12 parts desulfurized gypsum, 25-30 parts slag powder, 5-10 parts composite activator, and 6-8 parts mixed fiber; the composite activator is a mixture of sodium silicate powder, nano-grade metakaolin, sodium hydroxide and coated sodium carbonate.
2. The red mud-based solid waste cementitious material according to claim 1, characterized in that, The preparation method of the coated sodium carbonate is as follows: atomize a saturated sodium carbonate solution at 34-36°C and spray it onto the surface of a silica sol solution at 0-4°C, stir, filter to obtain microspheres, and dry the microspheres to obtain coated sodium carbonate.
3. The red mud-based solid waste cementitious material according to claim 1 or 2, characterized in that, The mass ratio of sodium silicate powder, nano-sized metakaolin, sodium hydroxide, and coated sodium carbonate in the composite activator is (6-9):(2-4):(1-3):(18-22).
4. The red mud-based solid waste cementitious material according to claim 1, characterized in that, The mixed fiber is a mixture of modified basalt fiber and modified biomass fiber.
5. The red mud-based solid waste cementitious material according to claim 4, characterized in that, The modified basalt fiber is composed of modified basalt short fiber, modified basalt medium fiber and modified basalt long fiber in a mass ratio of 3:(3-5):(1-2); the modified biomass fiber is composed of modified biomass short fiber, modified biomass medium fiber and modified biomass long fiber in a mass ratio of 3:(3-5):(1-2).
6. The red mud-based solid waste cementitious material according to claim 5, characterized in that, The method for preparing the modified basalt short fibers is as follows: the basalt short fibers are modified using a silane coupling agent; the method for preparing the modified basalt fibers and modified basalt long fibers is as follows: the basalt fibers and / or long fibers are first modified using a silane coupling agent, and then nano-SiO2 particles are loaded onto the surface of the basalt fibers and / or long fibers modified by the silane coupling agent.
7. The red mud-based solid waste cementitious material according to claim 4, characterized in that, The preparation method of the modified biomass short fiber, modified biomass medium fiber and modified biomass long fiber is as follows: under the condition of 60-80℃, the biomass short fiber and / or medium fiber and / or long fiber are soaked in an alkaline solution for 16-28h, then dopamine is added to the alkaline solution, mixed well, and then hydrogen peroxide solution is added, and soaked at 40-60℃ for 16-28h.
8. The red mud-based solid waste cementitious material according to claim 7, characterized in that, The amount of dopamine used is 1% to 2% of the mass of the alkaline solution.
9. The red mud-based solid waste cementitious material according to claim 4, characterized in that, The mass ratio of modified basalt fiber to modified biomass fiber in the mixed fiber is 6-8:2-4.
10. A method for preparing a red mud-based solid waste cementitious material according to any one of claims 1-9, characterized in that, Includes the following steps: After mixing red mud, desulfurized gypsum, slag powder, composite activator, and mixed fibers evenly, the mixture is ground and blended to obtain red mud-based solid waste cementitious material.