A method for preparing a high-performance low-carbon red mud-based geopolymer

Abstract

A method for preparing a high-performance low-carbon red mud-based geopolymer includes the preparation of a slurry. The dried Bayer red mud is crushed and then calcined. The calcined red mud and slag powder are mixed as a cementitious material. The cementitious material, aggregate, alkali activator, and external additive are mixed, and water is added and stirred evenly to form a slurry. The external additive includes a polymer composition, and the polymer composition is composed of hydroxypropyl ethyl cellulose, polyethylene oxide, and ethylene-vinyl acetate copolymer. In the present invention, by adding the polymer composition, the strength of the geopolymer is effectively improved, enabling the Bayer red mud to have excellent flexural strength and flexural strength even at a high ratio. At the same time, the solidification effect of the geopolymer on heavy metal ions is also effectively improved. The dissolution degrees of heavy metal ions such as Cr, Cu, and Ni have decreased by more than 50%, reducing the dissolution and diffusion of heavy metal ions during long-term use and improving the environmental performance of the prepared geopolymer.

Description

Technical Field

[0001] The present invention relates to the technical field of preparing geopolymer building materials, and particularly relates to a method for preparing a high-performance low-carbon red mud-based geopolymer. Background Art

[0002] Red mud is a solid waste generated by separating the red mud slurry obtained after high-temperature and high-pressure digestion of bauxite during the production of alumina. The waste has a high iron oxide content and appears red in color, so it is called red mud. Red mud contains a large amount of alkali liquor. When a large amount of red mud is stacked, alkali leakage is likely to occur. A large amount of fluoride ions, sodium ions, and heavy metal ions exist in the alkali liquor, which will cause pollution of underground and surface water and salinization of the surrounding soil. Dust is easily formed on the surface of the exposed dry red mud, polluting the surrounding environment.

[0003] The pH value of red mud is between 12 and 14. It has a large specific surface area and complex components. Each component exists in the form of silica residue and does not conform to the mineral composition of natural soil. It is an insoluble residue, and its resource utilization is severely restricted. Therefore, the treatment of red mud has also become an international problem.

[0004] The research on the resource utilization of red mud mainly focuses on the recovery of valuable metals, adsorption materials, soil remediation, building materials, catalysts, and new functional materials, etc. Among them, the research on building materials is the most likely method to achieve large-scale resource utilization of red mud. As a new type of inorganic non-metallic material, geopolymers use solid wastes such as red mud, slag, and fly ash as raw materials to prepare building materials, which have the advantages of high early strength, fast setting speed, acid and corrosion resistance, and good interfacial bonding ability. It can replace cement, not only reducing the emission of CO 2 (the CO 2 emission from cement production accounts for about 7% of the global total emission), reducing environmental pollution, but also making the solid waste resourcefully utilized.

[0005] Existing red mud geopolymers are divided into binary or multi-component geopolymers composed of red mud and fly ash, slag, metakaolin, lime, etc. according to the gel materials. Among them, the research on red mud + slag-based geopolymers is relatively more. Red mud + slag-based geopolymers have higher strength than other geopolymers and can meet the requirements of building materials. Red mud is divided into Bayer process red mud and sintering process red mud according to different production processes. The prior art prepares geopolymers from Bayer process red mud and sintering process red mud respectively. After testing, Bayer process red mud is not suitable for preparing geopolymers whether it is calcined or not. Due to the low activity of Bayer process red mud, the strength of the formed geopolymer is low. High-temperature calcination can improve the strength of the geopolymer to a certain extent, but the effect is not ideal. Summary of the Invention

[0006] Based on the problems of the existing technology, the object of the present invention is to provide a method for preparing a high-performance low-carbon red mud-based geopolymer. Using Bayer red mud as raw material, high-strength geopolymers are prepared. In addition, heavy metal ions in the red mud are effectively solidified, reducing environmental pollution caused by the free volatilization of heavy metal ions in the geopolymers.

[0007] The object of the present invention is achieved by the following technical solutions:

[0008] A method for preparing a high-performance low-carbon red mud-based geopolymer, including the preparation of a slurry, characterized in that: the preparation of the slurry is to crush dry Bayer red mud, then carry out calcination treatment, and the calcined red mud and slag powder are mixed as a cementitious material, and the cementitious material, aggregate, alkali activator and external additive are mixed, and water is added and stirred evenly to form a slurry.

[0009] Further, the calcination is to calcine the crushed Bayer red mud at 600-800 °C for 1-2 h, and then naturally cool to room temperature.

[0010] More preferably, the calcination is to calcine the crushed Bayer red mud at 600 °C for 2 h, and then naturally cool to room temperature.

[0011] Further, in the cementitious material, the mass ratio of Bayer red mud to slag powder is 0.4:0.6-0.7:0.3, and the slag powder is at least one of S95 slag powder and S105 slag powder.

[0012] The specific surface area of the slag powder ≥ 400m 2 / kg, the flow ratio ≥ 95%, meeting the standard GB / T 18046-2017 "Ground Granulated Blast Furnace Slag for Cement, Mortar and Concrete".

[0013] Further, the aggregate is standard sand, specifically ISO standard sand.

[0014] Further, the alkali activator is instant sodium silicate powder, and sodium hydroxide is added to adjust the solution modulus to 1.0-2.5.

[0015] Further, the external additives include water reducer, retarder, expansive agent and polymer composition.

[0016] Further, the water reducer is at least one of sodium lignosulfonate, polycarboxylate water reducer, naphthalene-based water reducer, and melamine-based water reducer.

[0017] Further, the retarder is at least one of sodium gluconate, boric acid, sucrose, calcium stearate, dodecyltrimethoxysilane, desulfurized gypsum, etc.

[0018] Further, the expansive agent is at least one of UEA type and AEA type concrete expansive agents.

[0019] Further, the polymer composition is composed of hydroxypropyl ethyl cellulose, polyethylene oxide and ethylene-vinyl acetate copolymer.

[0020] Further, based on the mass of the cementitious material, the addition amounts of the components in the polymer composition are, by mass percentage, 0.05% - 0.5% of hydroxypropyl ethyl cellulose, 0.05% - 0.4% of polyethylene oxide, and 0.5% - 3% of ethylene-vinyl acetate copolymer.

[0021] Further, in the polymer composition, the molecular weight of hydroxypropyl ethyl cellulose is 200,000 - 400,000, the molecular weight of polyethylene oxide is 6,000,000 - 8,000,000, and the molecular weight of ethylene-vinyl acetate copolymer is 100,000 - 200,000.

[0022] Further preferably, the doping amounts of the components in the polymer composition are 0.2% of hydroxypropyl ethyl cellulose, 0.1% of polyethylene oxide, and 2.0% of ethylene-vinyl acetate copolymer.

[0023] In the slag, the amount of SiO 2 and Al 2 O 3 is higher in amount of substance than that in the red mud, which can meet the requirement of the silicon-aluminum ratio for stable geopolymers.

[0024] Since the strength and elastic modulus of the red mud geopolymer will decrease with the increase of the red mud doping amount, the amount of red mud used in most red mud geopolymers is less than 50%. When the doping amount is too high, it will significantly reduce the strength of the geopolymer, resulting in failure to meet the use requirements, especially for Bayer red mud.

[0025] In the present invention, by adding the polymer composition, the strength of the geopolymer is effectively improved, so that the geopolymer can still maintain a relatively high strength when the red mud content increases. In addition, it is also found that the addition of the polymer composition composed of hydroxypropyl ethyl cellulose, polyethylene oxide and ethylene-vinyl acetate copolymer in the present invention effectively enhances the heavy metal ion solidification effect of the prepared geopolymer and reduces the dissolution and diffusion of heavy metal ions during the long-term use of the geopolymer.

[0026] Further, in the prepared slurry, the mass ratio of the cementitious material to the aggregate is 1:1 - 3. Based on the mass of the cementitious material, by mass percentage, the alkali activator in the slurry is 6.5% - 7.5% calculated as Na 2 O, the water reducer is 0.4% - 1.2%, the retarder is 2% - 3%, the expansive agent is 0.5% - 1%, and the water-cement ratio of the slurry is 0.35 - 0.55.

[0027] Specifically, a method for preparing a high-performance low-carbon red mud-based geopolymer, characterized by comprising the following steps:

[0028] (1) Crush the dried Bayer red mud, pass it through a 40-mesh sieve, calcine it at 600-800 °C for 1-2 h, and then cool it naturally;

[0029] (2) Mix the Bayer red mud treated in step (1) and slag powder as a cementitious material according to a mass ratio of 0.4:0.6 - 0.7:0.3. Mix the cementitious material, alkali activator, water reducer, retarder, expansive agent, and polymer composition, add water and stir evenly, then add aggregate and stir evenly to form a slurry, with a water-cement ratio of 0.35 - 0.55; the mass ratio of the cementitious material to the aggregate is 1:1 - 3. Based on the mass of the cementitious material, according to mass percentages, in the slurry, the alkali activator is 6.5% - 7.5% in terms of Na 2 O, the water reducer is 0.4% - 1.2%, the retarder is 2% - 3%, the expansive agent is 0.5% - 1%. The polymer composition is composed of hydroxypropyl ethyl cellulose, polyethylene oxide, and ethylene-vinyl acetate copolymer, and the doping amounts are 0.05% - 0.5% for hydroxypropyl ethyl cellulose, 0.05% - 0.4% for polyethylene oxide, and 0.5% - 3% for ethylene-vinyl acetate copolymer respectively; the aggregate is ISO standard sand, the alkali activator is instant sodium silicate powder, the solution modulus is adjusted to 1.0 - 2.5 with sodium hydroxide, the water reducer is at least one of lignosulfonate, polycarboxylate water reducer, naphthalene-based water reducer, and melamine-based water reducer, the retarder is at least one of sodium gluconate, boric acid, sucrose, calcium stearate, dodecyltrimethoxysilane, desulfurized gypsum, etc., and the expansive agent is at least one of UEA type and AEA type concrete expansive agents;

[0030] (3) Pour the slurry prepared in step (2) into a mold, place it in a standard constant temperature and humidity curing box, keep it in an environment with a temperature of 21 °C and a humidity of 95% for 2 hours, and continue to place it in the constant temperature and humidity curing box for curing after demolding.

[0031] The present invention has the following technical effects:

[0032] In the present invention, by adding a polymer composition composed of hydroxypropyl ethyl cellulose, polyethylene oxide, and ethylene-vinyl acetate copolymer, the strength of the geopolymer is effectively improved, enabling the Bayer red mud to have excellent flexural strength and flexural strength even at a high ratio. At the same time, the curing effect of the geopolymer on heavy metal ions is effectively improved, reducing the dissolution and diffusion of heavy metal ions during long-term use. The dissolution degrees of heavy metal ions such as Cr, Cu, and Ni have all decreased by more than 50%, improving the environmental protection performance of the prepared geopolymer. Description of the Drawings

[0033] Figure 1: Scanning electron micrograph of the geopolymer prepared in Example 1 after being naturally placed for 60 days.

[0034] Figure 2 : Scanning electron micrograph of the geopolymer prepared by separately adding 0.3% hydroxypropyl ethyl cellulose after being naturally placed for 60 days.

[0035] Figure 3 : Scanning electron micrograph of the geopolymer prepared by separately adding 1.0% ethylene-vinyl acetate copolymer after being naturally placed for 60 days.

[0036] Figure 4 : Scanning electron micrograph of the geopolymer prepared in Example 2 after being naturally placed for 60 days.

[0037] Figure 5 : Influence curve of hydroxypropyl ethyl cellulose (Z1) on the compressive strength of the geopolymer.

[0038] Figure 6 : Influence curve of polyethylene oxide (Z2) on the compressive strength of the geopolymer.

[0039] Figure 7 : Influence curve of ethylene-vinyl acetate copolymer (Z3) on the compressive strength of the geopolymer. Detailed implementation manners

[0040] The present invention will be specifically described below through examples. It is necessary to point out here that the following examples are only used to further illustrate the present invention and cannot be construed as limiting the protection scope of the present invention. Those skilled in the art can make some non-essential improvements and adjustments to the present invention according to the above content of the present invention.

[0041] The red mud used in the present invention is Bayer red mud provided by Chongqing Jiulong Wanbo New Material Technology Co., Ltd., including Australian ore red mud and several ore red mud according to different ore sources. The chemical properties of red mud from different ore sources are shown in Table 1.

[0042] Table 1: Chemical properties of red mud from different ore sources

[0043]

[0044] In the polymer composition used in the present invention, the molecular weight of hydroxypropyl ethyl cellulose is 200,000, the molecular weight of polyethylene oxide is 8,000,000, and the molecular weight of ethylene-vinyl acetate copolymer is 100,000.

[0045] Example 1

[0046] A method for preparing a high-performance low-carbon red mud-based geopolymer includes the following steps:

[0047] (1) Crush the dry Australian ore Bayer red mud, sieve it through a 40-mesh sieve, calcine it at 600 °C for 2 h, and then cool it naturally;

[0048] (2) Mix the Bayer red mud and slag powder treated in step (1) as a cementitious material in a mass ratio of 0.5:0.5. Mix the cementitious material, alkali activator, water reducer, retarder, expansive agent, and polymer composition, add water and stir evenly, then add the aggregate and stir evenly to form a slurry, with a water-cement ratio of 0.4; the mass ratio of the cementitious material to the aggregate is 1:1. Based on the mass of the cementitious material, according to the mass percentage, the alkali activator is 7% in terms of Na 2 O, the water reducer is 0.5%, the retarder is 3%, the expansive agent is 1%, and the polymer composition consists of hydroxypropyl ethyl cellulose, polyethylene oxide, and ethylene-vinyl acetate copolymer, with doping amounts of 0.2% hydroxypropyl ethyl cellulose, 0.1% polyethylene oxide, and 2% ethylene-vinyl acetate copolymer respectively; the aggregate is ISO standard sand, the alkali activator is instant sodium silicate powder, the solution modulus is adjusted to 1.2 with sodium hydroxide, the water reducer is a naphthalene-based water reducer, the retarder is desulfurized gypsum, the expansive agent is UEA type expansive agent, the specific surface area of the slag powder ≥ 400 m 2 / kg, the flow ratio ≥ 95%, meeting the standard GB / T 18046-2017 "Ground Granulated Blast-Furnace Slag for Use in Cement, Mortar and Concrete", and the aggregate is standard sand, specifically ISO standard sand;

[0049] (3) Pour the slurry prepared in step (2) into a mold, place it in a standard constant temperature and humidity curing box, keep it in an environment with a temperature of 21 °C and a humidity of 95% for 2 hours, and continue to place it in the constant temperature and humidity curing box for curing after demolding.

[0050] Figure 1 This is the scanning electron micrograph of the geopolymer prepared in this example after being placed in the natural environment for 60 days. It can be seen that the geopolymer structure is uniform and dense. Figure 2 and Figure 3 The scanning electron micrographs of the geopolymers prepared by separately adding 0.3% hydroxypropyl ethyl cellulose and separately adding 1.0% ethylene-vinyl acetate copolymer after being naturally placed for 60 days. It can be seen that after the geopolymer is placed for a period of time, obvious cracks appear in the structure.

[0051] Prepare the slurry by mixing the components in Example 1. By adjusting the use of water-soluble polymer materials, specifically, hydroxypropyl ethyl cellulose, polyethylene oxide, and ethylene-vinyl acetate copolymer are used alone for doping. In the test of adding polymer materials alone, the optimal doping amount of hydroxypropyl ethyl cellulose is 0.3%, the optimal doping amount of polyethylene oxide is 0.1%, and the optimal doping amount of ethylene-vinyl acetate copolymer is 3.0%. By adjusting the doping amount of the polymer composition, the effect of the polymer composition on the strength of the prepared geopolymer is tested. The results are shown in Table 2. In the composition, hydroxypropyl ethyl cellulose, polyethylene oxide, and ethylene-vinyl acetate copolymer are denoted as Z1, Z2, and Z3 respectively.

[0052] Table 2:

[0053]

[0054] Using bayer red mud as raw material, the influence of adding polymer materials on the compressive strength performance of the prepared geopolymer is as Figures 5 - 7 shown. When each component of the polymer material is added alone, at a certain addition amount, the compressive strength of the prepared geopolymer is improved to a certain extent. Figure 5 shown. When the doping amount of hydroxypropyl ethyl cellulose is between 0.05% and 0.5%, with the increase of the doping amount, the compressive strength of the prepared geopolymer shows a trend of first increasing and then decreasing. When the doping amount is 0.3%, the compressive strength effect of the prepared geopolymer is the best, reaching 42.4 Mpa at 28 days. Figure 6 shown. When the doping amount of polyethylene oxide is between 0.05% and 0.4%, the compressive strength of the prepared geopolymer shows a trend of first increasing and then decreasing. When the doping amount is 0.1%, the compressive strength is the best, reaching 42.2 MPa. Figure 7 shown. When the doping amount of ethylene-vinyl acetate copolymer is between 0.5% and 4.0%, it shows a trend of first increasing and then decreasing. When the doping amount is 1.0%, the effect is the best. At 28 days, the compressive strength can reach 41.6 Mpa. With the increase of the doping amount, the compressive strength decreases significantly. When the doping amount reaches 4.0%, the decrease is the most significant. The compressive strength at 28 days drops to 35.9 MPa, lower than the compressive strength without addition, and then the decrease slows down.

[0055] After compounding Z1, Z2, and Z3, the optimal doping amount of Z1 is 0.2%, and the optimal doping amount of Z2 is 0.1%. Among them, when the doping amount of ethylene-vinyl acetate copolymer increases from 1.0% to 4.0%, the compressive strength of the prepared geopolymer shows a trend of first increasing and then decreasing. When the doping amount reaches 2.0% (Example 1), it reaches the highest, increasing to 50.6 MPa. When the doping amount is further increased to 3.0%, the strength decreases significantly. Continuing to increase the doping amount of Z3, the strength decreases even more significantly. Therefore, no further detection is carried out.

[0056] Solidified heavy metal ion test:

[0057] Before the leaching test, the red mud-based geopolymer was cured for 28 days. The heavy metal leaching test was carried out with reference to the "Horizontal Oscillation Method for Leaching Toxicity of Solid Wastes" (HJ557-2010). 100 g of the sample with dry basis weight was weighed and placed in a wide-mouth bottle with a screw cap and an inner cap. According to the moisture content of the sample, the volume of the leaching agent required was calculated according to the liquid-solid ratio of 10:1 (L / kg). The leaching agent was added, and after tightening the bottle cap, it was vertically fixed on a horizontal oscillation device. The oscillation frequency was adjusted to 110±10 times / min and the amplitude was 40 mm. After oscillating for 8 h at room temperature, the extraction bottle was removed and left to stand for 16 h. A vacuum filtration device was used for suction filtration to obtain the leachate, and an ICP-MS was used to test the heavy metal content in the leachate. The results are shown in Table 3.

[0058] Table 3:

[0059]

[0060] It can be seen that in the geopolymer prepared by adding a single polymer material, the dissolution concentrations of heavy metal ions Cr, Cu, and Ni did not change significantly compared with the geopolymer without addition. However, after adding a combination of three polymer materials, the dissolution concentrations of heavy metal ions decreased significantly, indicating that the addition of the polymer composition effectively improved the solidification effect of the geopolymer on heavy metal ions.

[0061] On the basis of Example 1, by adjusting the proportion of red mud in the cementitious material, the strength change of the prepared geopolymer was detected. The results are shown in Table 4.

[0062] Table 4:

[0063]

[0064] Example 2

[0065] A method for preparing a high-performance low-carbon red mud-based geopolymer, comprising the following steps:

[0066] (1) Crush the dry bauxite red mud, pass it through a 40-mesh sieve, calcine it at 800 °C for 1 h, and then cool it naturally;

[0067] (2) Mix the bauxite red mud treated in step (1) and slag powder in a mass ratio of 0.4:0.6 as the cementitious material. Mix the cementitious material, alkali activator, water reducer, retarder, expansive agent, and polymer composition, add water and stir evenly, and then add the aggregate and stir evenly to form a slurry. The water-cement ratio is 0.55; the mass ratio of the cementitious material to the aggregate is 1:2. Based on the mass of the cementitious material, according to the mass percentage, the alkali activator is Na2 The dosage of O is 7.5%, the dosage of water reducer is 0.4%, the dosage of retarder is 2%, the dosage of expansive agent is 0.5%, the polymer composition is composed of hydroxypropyl ethyl cellulose, polyethylene oxide and ethylene-vinyl acetate copolymer, and the doping amounts are 0.2% of hydroxypropyl ethyl cellulose, 0.1% of polyethylene oxide and 2.0% of ethylene-vinyl acetate copolymer respectively; the aggregate is ISO standard sand, the alkali activator is instant sodium silicate powder, the solution modulus is adjusted to 2.5 with sodium hydroxide, the water reducer is sodium lignosulfonate, the retarder is calcium stearate, the expansive agent is AEA type concrete expansive agent, and the specific surface area of the slag powder ≥ 400m 2 / kg, the flow ratio ≥ 95%, meeting the standard GB / T 18046-2017 "Ground Granulated Blast-Furnace Slag for Use in Cement, Mortar and Concrete". The aggregate is standard sand, specifically ISO standard sand;

[0068] (3) Pour the slurry prepared in step (2) into a mold, place it in a standard constant temperature and humidity curing box, keep it in an environment with a temperature of 21°C and a humidity of 95% for 2 hours, and continue to place it in the constant temperature and humidity curing box for curing after demolding.

[0069] Figure 4 This is the scanning electron microscope image of the geopolymer prepared in this example after being placed in the natural environment for 60 days. After long-term placement, the geopolymer still maintains a tight structure.

[0070] According to the method in this example, by adjusting different polymer material additives, the compressive strength and heavy metal ion solidification effect of the prepared geopolymer are shown in Table 5.

[0071] Table 5:

[0072]

[0073] Example 3

[0074] A method for preparing a high-performance low-carbon red mud-based geopolymer, comprising the following steps:

[0075] (1) Crush the dry Australian bauxite Bayer red mud, pass it through a 40-mesh sieve, calcine it at 700°C for 1.5 h, and then cool it naturally;

[0076] (2) Mix the Bayer red mud treated in step (1) and the slag powder in a mass ratio of 0.7:0.3 as the cementitious material. Mix the cementitious material, alkali activator, water reducer, retarder, expansive agent and polymer composition, add water and stir evenly, and then add the aggregate and stir evenly to form a slurry, with a water-cement ratio of 0.35; the mass ratio of the cementitious material to the aggregate is 1:3. Based on the mass of the cementitious material, according to the mass percentage, in the slurry, the alkali activator is Na 2The dosage of O is 6.5%, the water reducer is 1.2%, the retarder is 2.5%, the expansive agent is 0.8%, and the polymer composition consists of hydroxypropyl ethyl cellulose, polyethylene oxide and ethylene-vinyl acetate copolymer, and the doping amounts are 0.3% of hydroxypropyl ethyl cellulose, 0.4% of polyethylene oxide and 1.0% of ethylene-vinyl acetate copolymer respectively; the aggregate is ISO standard sand, the alkali activator is instant sodium silicate powder, the solution modulus is adjusted to 1.0 with sodium hydroxide, the water reducer is polycarboxylate water reducer, the retarder is dodecyltrimethoxysilane, the expansive agent is UEA type concrete expansive agent, and the specific surface area of the slag powder ≥ 400m 2 / kg, the flow ratio ≥ 95%, meeting the requirements of Standard GB / T 18046-2017 "Ground Granulated Blast-furnace Slag for Use in Cement, Mortar and Concrete". The aggregate is standard sand, specifically ISO standard sand;

[0077] (3) Pour the paste prepared in step (2) into a mold, place it in a standard constant temperature and humidity curing box, keep it in an environment with a temperature of 21°C and a humidity of 95% for 2 hours, and continue to place it in the constant temperature and humidity curing box for curing after demolding.

[0078] The compressive strength and heavy metal ion solidification effect of the geopolymer prepared in this example are shown in Table 6.

[0079] Table 6:

[0080]

Claims

1. A method for preparing a high-performance low-carbon red mud-based polymer, comprising the preparation of a slurry, characterized in that: The slurry is prepared by crushing dried Bayer red mud and then calcining it, mixing the calcined red mud with slag powder as a cementitious material, mixing the cementitious material, aggregate, alkali activator and external additives, adding water and stirring evenly to form a slurry, wherein the external additive includes a polymer composition, and the polymer composition is composed of hydroxypropyl ethyl cellulose, polyethylene oxide and ethylene-vinyl acetate copolymer. The addition amount of each component in the polymer composition is based on the mass of the cementitious material, and is calculated in mass percentage, and the doping amount is 0.2% of hydroxypropyl ethyl cellulose, 0.1% of polyethylene oxide and 2.0% of ethylene-vinyl acetate copolymer.

2. A method for preparing a high-performance low-carbon red mud-based polymer according to claim 1, characterized in that: The calcination is to calcine the crushed Bayer red mud at 600-800° C. for 1-2 h, and then naturally cool it to room temperature.

3. A method for preparing a high-performance low-carbon red mud-based polymer as claimed in claim 1 or 2, characterized in that: In the cementitious material, the mass ratio of Bayer red mud to slag powder is 0.4: 0.6-0.7: 0.3, and the slag powder is at least one of S95 slag powder and S105 slag powder.

4. A method for preparing a high-performance low-carbon red mud-based polymer as claimed in claim 3, characterized in that: The alkaline activator is instant sodium silicate powder, and the solution modulus is adjusted to 1.0-2.5 with sodium hydroxide.

5. A method for preparing a high-performance low-carbon red mud-based polymer as claimed in claim 4, characterized in that: The external additives also include water reducing agent, retarder and expansion agent.

6. A method for preparing a high-performance low-carbon red mud-based polymer according to claim 5, characterized in that: The water reducer is at least one of sodium lignin sulfonate, polycarboxylic acid water reducer, naphthalene water reducer, and melamine water reducer; the retarder is at least one of sodium gluconate, boric acid, sucrose, calcium stearate, dodecyltrimethoxysilane, and desulfurized gypsum; and the expansive agent is at least one of UEA type and AEA type concrete expansive agents.

7. A method for preparing a high-performance low-carbon red mud-based polymer according to claim 6, characterized in that: In the slurry, the mass ratio of cementitious material to aggregate is 1:1-3. Based on the mass of cementitious material and calculated by mass percentage, the alkali activator in the slurry is 6.5%-7.5% in terms of Na2O, the water reducer is 0.4%-1.2%, the retarder is 2%-3%, the expansion agent is 0.5%-1%, and the water-cement ratio of the slurry is 0.35-0.

55.

8. A method for preparing a high-performance low-carbon red mud-based polymer, characterized in that: The steps include: (1) Grind the dried Bayer red mud, pass it through a 40-mesh sieve, calcine it at 600-800°C for 1-2h and then cool it naturally; (2) The Bayer red mud treated in step (1) and the slag powder are mixed in a mass ratio of 0.4: 0.6-0.7:0.3 as a cementitious material, the cementitious material, the alkali activator, the water reducer, the retarder, the expansion agent and the polymer composition are mixed, water is added and stirred evenly, and then the aggregate is added and stirred evenly to form a slurry, and the water-cement ratio is 0.35-0.55; the mass ratio of the cementitious material to the aggregate is 1:1-3, based on the mass of the cementitious material, in terms of mass percentage, the alkali activator is 6.5%-7.5% in terms of Na2O, the water reducer is 0.4%-1.2%, the retarder is 2%-3%, the expansion agent is 0.5%-1%, and the polymer composition is composed of hydroxypropyl ethyl cellulose, polyethylene oxide and ethylene-vinyl acetate copolymer. The composition is as follows: the doping amounts are 0.05% to 0.5% of hydroxypropyl ethyl cellulose, 0.05% to 0.4% of polyethylene oxide, and 0.5% to 3% of ethylene-vinyl acetate copolymer; the aggregate is ISO standard sand; the alkali activator is instant sodium silicate powder; the solution modulus is adjusted to 1.0 to 2.5 with sodium hydroxide; the water reducer is at least one of sodium lignin sulfonate, polycarboxylic acid water reducer, naphthalene water reducer, and melamine water reducer; the retarder is at least one of sodium gluconate, boric acid, sucrose, calcium stearate, dodecyl trimethoxy silane, and desulfurized gypsum; and the expansion agent is at least one of UEA type and AEA type concrete expansion agent; (3) The slurry prepared in step (2) is introduced into a mold and placed in a constant temperature and humidity curing box for 2 hours. After demolding, it is continued to be placed in the constant temperature and humidity curing box for curing.

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