An anti-erosion cracking low-carbon concrete and a preparation method thereof

Abstract

The embodiment of the application provides an anti-erosion cracking low-carbon concrete and a preparation method thereof, and relates to the technical field of building concrete. The anti-erosion cracking low-carbon concrete comprises the following raw materials in parts by mass: 350-550 parts of red mud-based low-carbon cementing material, 950-1100 parts of coarse aggregate, 650-900 parts of fine aggregate, 0.3-6 parts of modified basalt fiber, 10-60 parts of high-aluminum slag ion solidifying agent, 2-8 parts of polycarboxylate superplasticizer, and 100-250 parts of water. The preparation method of the anti-erosion cracking low-carbon concrete comprises the following steps: step one, preparation of the red mud-based low-carbon cementing material; step two, preparation of the aluminum-based basalt fiber; step three, preparation of the high-aluminum slag ion solidifying agent; and step four, mixing and stirring of the red mud-based low-carbon cementing material, the coarse aggregate, the fine aggregate, the aluminum-based basalt fiber, the high-aluminum slag ion solidifying agent, the polycarboxylate superplasticizer and the water to obtain the anti-erosion cracking low-carbon concrete.

Description

Technical Field

[0001] This invention belongs to the field of building concrete technology, and particularly relates to an anti-erosion and cracking low-carbon concrete and its preparation method. Background Technology

[0002] Concrete: refers to a general term for engineering composite materials in which aggregates are bound together by cementing materials. The term concrete usually refers to cement concrete, which is made by mixing cement as cementing material, sand and stone as aggregates, and water (which may contain admixtures and additives) in a certain proportion. It is also called ordinary concrete and is widely used in civil engineering.

[0003] The existing technology (patent application CN106830802B, entitled "Concrete and its Preparation Method") has the advantages of good cold resistance, stability, and durability, and is not prone to cracking. However, in the process of implementing this technical solution, at least the following problems were found in the existing technology: Most of the concrete currently used in construction is made of ordinary silicate cement concrete, single mineral admixture low-carbon concrete, and ordinary fiber concrete systems. The resulting functions are too limited and cannot meet the high requirements of construction projects, thus limiting its applicability. Summary of the Invention

[0004] This application aims to at least address one of the technical problems in the prior art where it is impossible to use a multi-material co-mixing method to produce concrete with multiple functions such as erosion resistance, crack prevention, and low carbon content. To this end, this application proposes an erosion-resistant, crack-resistant, low-carbon concrete and its preparation method.

[0005] To achieve the above objectives, the specific technical solution of the present invention is as follows: A low-carbon concrete resistant to erosion and cracking is prepared from red mud-based low-carbon cementitious materials, coarse aggregate, fine aggregate, aluminum-based basalt fiber, high-alumina slag ion curing agent, polycarboxylate superplasticizer and water. The raw materials, by weight, include: 350-550 parts of red mud-based low-carbon cementitious material, 950-1100 parts of coarse aggregate, 650-900 parts of fine aggregate, 0.3-6 parts of modified basalt fiber, 10-60 parts of high-alumina slag ion curing agent, 2-8 parts of polycarboxylate superplasticizer, and 100-250 parts of water.

[0006] Preferably, the water-cement ratio of the low-carbon concrete is 0.25–0.40, more preferably 0.3–0.38; the dosage of the polycarboxylate superplasticizer is 0.5%–1.0% of the total mass of the cementitious material; the red mud-based low-carbon cementitious material is composed of a solid cementitious precursor and an alkali activator; the solid cementitious precursor is composed of red mud, ultrafine fly ash, blast furnace slag powder, desulfurized gypsum, and glass powder; the alkali activator is composed of sodium silicate solution and sodium hydroxide solid particles; the molar ratio of silicon dioxide to sodium oxide in the sodium silicate solution is 3.29; and the modulus of the composite alkali activator formed by mixing the sodium silicate solution and sodium hydroxide is 1.45.

[0007] Preferably, the red mud-based low-carbon cementitious material comprises, by mass, 20-40 parts red mud, 20-40 parts ultrafine fly ash, 10-30 parts blast furnace slag powder, 5-15 parts desulfurized gypsum, 10-30 parts glass powder, and 5-15 parts alkali activator. The glass powder is obtained from waste glass through crushing, ball milling with grinding aid, drying, and sieving. During ball milling of the waste glass, anhydrous ethanol is used as the solvent, and a composite grinding aid of 0.2% by mass of the waste glass is added. The ball milling time is 20-60 minutes, preferably 30 minutes. After ball milling, the glass powder is obtained by drying and sieving. The coarse aggregate is crushed stone or continuously graded stone, and the fine aggregate is natural sand, manufactured sand, or a combination thereof. The aluminum-based basalt fiber is obtained from basalt fiber after surface pretreatment, silane coupling agent impregnation modification, and aluminum ion loading treatment.

[0008] Preferably, the aluminum ion loading treatment is as follows: basalt fibers impregnated with silane coupling agent are placed in an Al(NO3)3 solution with a concentration of 0.05–0.2 mol / L. Subsequently, the pH of the system is slowly adjusted to 6–7 by adding ammonia or urea, so that an aluminum hydroxide precipitate layer is generated in situ on the surface of the basalt fibers, and an Al(OH)3 coating layer is preferentially formed on the fiber surface.

[0009] Preferably, the aluminum-based basalt fiber accounts for 0.1% to 3.0% of the total mass of the cementitious material, more preferably 0.5% to 2.0%. The high-alumina slag ion curing agent is prepared by combining high-alumina slag, composite grinding aid, surface modifier, ion-promoting solvent, and water. The components of the high-alumina slag ion curing agent, by mass percentage, include: 75% to 85% high-alumina slag, 0.05% to 0.5% composite grinding aid, 0.1% to 1.0% surface modifier, 1.0% to 5.0% ion-promoting solvent, and 10% to 25% water. In the high-alumina slag ion curing agent, high-alumina slag accounts for 80%, composite grinding aid for 0.1%, surface modifier for 0.4%, ion-promoting solvent for 2.0%, and water for 17.5%.

[0010] Preferably, the composite grinding aid comprises triethanolamine and ethylene glycol, with the mass percentages of triethanolamine and ethylene glycol being 0.04% and 0.06%, respectively; the surface modifier comprises lignin sulfonate and PEG-400, with the mass percentages of lignin sulfonate and PEG-400 being 0.25% and 0.15%, respectively; the ionic co-solvent comprises sodium aluminate and potassium silicate, with the mass percentages of sodium aluminate and potassium silicate being 1.0% and 1.0%, respectively; and the high-alumina slag ionic curing agent is incorporated into the low-carbon concrete as a functional mineral admixture, with its dosage being 2% to 10% of the total mass of the cementitious materials, preferably 3% to 8%. In the low-carbon concrete, the red mud-based low-carbon cementitious materials partially or completely replace the traditional silicate cementitious system, thereby reducing the amount of cement clinker used and the carbon emissions during the preparation process.

[0011] A method for preparing erosion-resistant and crack-resistant low-carbon concrete includes the following steps: Step 1: Preparation of red mud-based low-carbon cementitious materials; Step 2: Preparation of aluminum-based basalt fibers; Step 3: Preparation of high-alumina slag ion curing agent; Step 4: Mix and stir the red mud-based low-carbon cementitious material, coarse aggregate, fine aggregate, aluminum-based basalt fiber, high-alumina slag ion curing agent, polycarboxylate superplasticizer and water to obtain erosion-resistant and crack-resistant low-carbon concrete.

[0012] Preferably, in step one, the preparation of the red mud-based low-carbon cementitious material includes: mixing red mud, ultrafine fly ash, blast furnace slag powder, desulfurized gypsum, and glass powder in a certain proportion to obtain a solid cementitious precursor; mixing sodium silicate solution with sodium hydroxide to prepare an alkali activator; and then mixing the alkali activator with the solid cementitious precursor to obtain the red mud-based low-carbon cementitious material. In step one, the preparation of the glass powder includes: crushing waste glass, using anhydrous ethanol as a solvent, adding 0.2% of a composite grinding aid by weight of the waste glass, and ball milling for 20-60 minutes; after ball milling, drying and sieving are performed to obtain the glass powder. Further optionally, in step one, the sieved particle size is 45-150 μm, preferably the specific surface area of ​​the glass powder is not less than 400 m² / kg, and in step one, the alkaline activator is prepared by using a sodium silicate solution with a molar ratio of silicon dioxide to sodium oxide of 3.29 and mixing it with solid sodium hydroxide, so that the modulus of the composite activation system after mixing is 1.45; In step two, the preparation of aluminum-based basalt fibers includes: surface cleaning and pretreatment of basalt fibers; impregnation and modification of the pretreated basalt fibers in a silane coupling agent solution to obtain surface-activated fibers; aluminum ion loading treatment of the surface-activated fibers in an Al(NO3)3 solution; slow adjustment of the pH value of the system to 6-7 by adding ammonia or urea to allow aluminum ions to preferentially deposit on the surface of the basalt fibers to form an Al(OH)3 layer; and obtaining the aluminum-based basalt fibers after washing and drying. In step two, the silane coupling agent is one or more of aminosilane coupling agents, epoxysilane coupling agents, or methacryloxysilane coupling agents. In step two, the concentration of the Al(NO3)3 solution is 0.05-0.2 mol / L, the aluminum ion loading treatment time is 0.5-4 h, and the drying temperature is 40-80 °C. In step three, the preparation of the high-alumina slag ion curing agent includes: adding high-alumina slag, composite grinding aid, surface modifier, and ion-promoting solvent into a mixing device and mixing them evenly; adding water and continuing stirring to activate the surface of the high-alumina slag particles through grinding and ion-promoting solubilization modification, thereby obtaining a slurry-like high-alumina slag ion curing agent; and, if necessary, performing an aging treatment to improve the uniformity and activation effect of the system. In step three, the high-alumina slag can be pre-ground to achieve a specific surface area of ​​300–800 m² / kg. In step three, the mixing and stirring time is 10–60 min, the stirring speed is 200–800 rpm, and the aging time is 0.5–24 h. In step three, the triethanolamine and ethylene glycol in the composite grinding aid work synergistically to improve the grinding efficiency and particle dispersibility of the high-alumina slag; the lignin sulfonate and PEG-400 work synergistically to improve the wettability of the particle surface and interfacial compatibility; and the sodium aluminate and potassium silicate are used to improve the release capacity of aluminum-silicon active ions.

[0013] In step four, the preparation of the erosion-resistant and crack-resistant low-carbon concrete includes: first, dry mixing coarse aggregate, fine aggregate, and red mud-based low-carbon cementitious material in a mixer for 10-60 seconds; then, adding high-alumina slag ion curing agent and some mixing water for wet mixing for 30-120 seconds; subsequently, adding polycarboxylate superplasticizer, the remaining mixing water, and alumina-based basalt fiber and continuing mixing for 60-300 seconds; after uniform mixing, the erosion-resistant and crack-resistant low-carbon concrete mixture is obtained; in step four, the alumina-based basalt fiber is added in a dispersed manner, or premixed with some fine aggregate before being added, to avoid fiber agglomeration; in step four, the concrete mixture is poured, vibrated, and molded before curing, and the curing method is one of standard curing, steam curing, or composite curing; the standard curing conditions are a temperature of 20±2℃, a relative humidity of ≥95%, and a curing age of 3-28 days.

[0014] Preferably, in step four, red mud-based low-carbon cementitious material, coarse aggregate, fine aggregate, aluminum-based basalt fiber, high-alumina slag ion curing agent, polycarboxylate superplasticizer and water are added to the mixing tank through the feeding hopper for mixing. During the mixing, four sets of vibration damping seats with vibration damping pads are fixed at the bottom of the mixing tank to dampen and cancel the vibration. Then, the erosion-resistant and crack-resistant low-carbon concrete obtained in step four is discharged through the discharge hopper. The bottom of the mixing tank is fixed with a fixing frame, and the fixing frame is equipped with a longitudinal mixing component for dry / wet mixing of the materials in the mixing tank. Furthermore, the longitudinal mixing assembly includes a servo motor fixed to the bottom of the fixed frame. The servo motor is fitted with a drive spur gear, and driven spur gears that rotate with the fixed frame are meshed around the drive spur gear. Concentric shafts that rotate with the mixing box are fixed on the four sets of driven spur gears, and stirring rods for longitudinal mixing of each material are alternately fixed on the concentric shafts. The two sets of feeding hoppers are equipped with a material guiding assembly, which includes a material guiding impeller fitted on the four stirring rods. The two sets of feeding hoppers are provided with a discharge port that rotates with the material guiding impeller to guide the material. The discharge port is provided with a material guiding groove around its perimeter. The inner side of the two sets of feeding hoppers is fixed with a flow divider, and a material guiding port communicating with the mixing box is provided below the flow divider. The mixing chamber is fixed with an inner cover, and a transverse mixing assembly is provided inside the inner cover. The assembly includes a central shaft fixed to the output shaft of a servo motor via a coupling. The central shaft rotates with the mixing chamber and extends to the top of the mixing chamber. Both the upper and lower sides of the central shaft are fitted with drive bevel gears, and driven bevel gears mesh around the drive bevel gears. A stirring frame that rotates with the inner cover is fixed to the outside of the driven bevel gears for transverse mixing of various materials. Guide frames that intersect with the stirring rod and stirring frame are fixed around the inner cover and are fixed to the mixing chamber.

[0015] Preferably, in step four, a water tower tank is included for adding red mud-based low-carbon cementitious material, coarse aggregate, fine aggregate, alumina-based basalt fiber, high-alumina slag ion curing agent, polycarboxylate superplasticizer, and water to the wet mixture in the mixing tank. The water tower tank is equipped with a liquid level sensor for liquid level monitoring, and a water distribution assembly is provided on the water tower tank. A booster pump is also included, which is embedded in the top of the water tower tank. The bottom of the water tower tank is connected to an electrically controlled valve with a metering sensor. The bottom end of the electrically controlled valve is connected to a rotating end. The rotating end is connected to a connecting end and communicates with a hollow cavity opened in the central shaft. Water distribution holes communicating with the hollow cavity are opened around the central shaft.

[0016] The erosion-resistant and crack-resistant low-carbon concrete and its preparation method of the present invention have the following advantages: 1. This invention relates to an anti-erosion and cracking low-carbon concrete and its preparation method. A multi-component solid waste synergistic cementitious system is constructed using red mud, ultrafine fly ash, blast furnace slag powder, desulfurized gypsum, and glass powder, and its potential activity is activated using a composite alkali activation method. This system significantly reduces the amount of traditional silicate cement clinker used, thus reducing carbon emissions during concrete preparation from the raw material end. Furthermore, through the synergistic reaction between the aluminosilicate phase, calcium aluminosilicate phase, and sulfate-activated components, a relatively continuous and dense cementitious structure can be formed, improving the strength and microstructural stability of the slurry matrix. This overcomes the problems of insufficient early reaction, loose structure, or insufficient later stability when some industrial solid wastes are used alone, constructing a multi-solid waste synergistic cementitious system that balances low carbon emissions with mechanical properties.

[0017] 2. This invention relates to an anti-corrosion and cracking low-carbon concrete and its preparation method. It introduces a high-alumina slag ion curing agent as a functional mineral admixture. After grinding-aid activation and ion-promoted dissolution, this curing agent releases active Al and Si components, promoting the continuous generation of cementitious products, improving the pore structure of the hardened paste and the interface transition zone, and reducing the proportion of harmful and interconnected pores. Simultaneously, its active aluminum component readily forms compound products, such as Friedel's salt, with calcium sources and chloride ions under chloride salt corrosion conditions, and readily forms insoluble precipitates or relatively stable aluminum sulfate products under sulfate conditions. This achieves curing and inhibition of corrosive ions, reduces the chloride ion diffusion coefficient and free chloride ion content, and improves the material's corrosion resistance.

[0018] 3. This erosion-resistant, crack-resistant low-carbon concrete and its preparation method utilize aluminum-based basalt fibers that have undergone surface pretreatment, silane coupling modification, and in-situ aluminum ion loading treatment. The Al(OH)3 coating layer formed on the fiber surface enhances the fiber's surface activity and interfacial compatibility with the cementitious matrix, strengthening interfacial bonding and stress transfer capabilities. The modified fibers effectively bridge and inhibit crack propagation in concrete, significantly improving splitting tensile strength and crack toughness. Furthermore, under chloride erosion conditions, the Ca(OH)2 and Al active sites and chloride ions enriched near the fiber interface facilitate the formation of calcium chloroaluminate-like compounds that fill the interfacial pores; under sulfate erosion conditions, they promote the formation of localized insoluble precipitates. Thus, the fiber interface possesses the dual functions of reinforcing and solidifying erosion ions, improving the long-term service stability of concrete in complex erosive environments.

[0019] 4. This erosion-resistant and crack-resistant low-carbon concrete and its preparation method involve high-alumina slag ion curing agent and alumina-based basalt fiber acting not independently, but forming a synergistic reinforcement mechanism at the microstructural level. The former mainly improves the matrix density by promoting the formation of cementitious products, filling pores, and optimizing the interfacial transition zone; the latter mainly inhibits the initiation and propagation of microcracks by bridging cracks, dispersing stress, and improving interfacial bonding strength. After their coupled effect, they can effectively inhibit the entry of corrosive media into the material interior along defect channels, thereby achieving simultaneous improvement in strength, crack resistance, and durability. The ion curing agent and modified fiber form a synergistic mechanism of "densification-bridging crack suppression".

[0020] 5. This invention relates to an anti-erosion and cracking low-carbon concrete and its preparation method. The prepared low-carbon concrete can be used in marine engineering, port engineering, offshore wind power foundations, coastal buildings, cross-sea bridges, seawalls, breakwaters, and engineering projects in saline soil areas, where concrete structures are subjected to multiple coupled erosion effects such as chloride, sulfate, and wet-dry cycles over long periods. It not only has a high solid waste resource utilization rate and significant low-carbon advantages, but also exhibits excellent performance in compressive strength, splitting tensile strength, erosion resistance, chloride ion penetration resistance, and crack control. It possesses good engineering promotion value, is suitable for complex erosive environments, and has outstanding engineering application prospects.

[0021] 6. This erosion-resistant and crack-resistant low-carbon concrete and its preparation method involve clearly defined steps, process parameter ranges, and raw material composition ranges for the preparation of red mud-based cementitious materials, modification of aluminum-based basalt fibers, preparation of high-alumina slag ion curing agents, and concrete mixing processes. These can be appropriately adjusted according to engineering needs, demonstrating good repeatability and scalability. Compared to high-cost and highly complex special durable concrete systems, this invention better meets the needs of large-scale engineering material preparation and actual construction. The preparation process is clear and controllable, possessing industrial feasibility. Attached Figure Description

[0022] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0023] Figure 1 This is a front view of the overall structure of an anti-erosion and cracking low-carbon concrete and its preparation method according to the present invention. Figure 2 This is an overall sectional view of the structure of an anti-erosion and cracking low-carbon concrete and its preparation method according to the present invention. Figure 3This is a partial front view of the structure of an anti-erosion and cracking low-carbon concrete and its preparation method according to the present invention. Figure 4 This is a partial cross-sectional view of the mixing tank and inner cover structure of the present invention; Figure 5 This is a front view of the longitudinal mixing assembly structure of the present invention; Figure 6 This is a partial cross-sectional view of the feeding hopper and material guiding assembly structure of the present invention; Figure 7 This is a bottom view of the structure of the transverse mixing assembly, water tower tank, and water distribution assembly of the present invention; Figure 8 This is an exploded view of the transverse mixing assembly structure of the present invention; Figure 9 This is a bottom cross-sectional view of the water tower tank, central shaft, and water distribution assembly structure of the present invention.

[0024] The markings in the diagram are as follows: 1. Mixing tank; 2. Feeding hopper; 3. Discharging hopper; 4. Fixing frame; 51. Servo motor; 52. Drive spur gear; 53. Driven spur gear; 54. Concentric shaft; 55. Stirring rod; 61. Guide impeller; 62. Discharge port; 63. Guide trough; 64. Diverter bar; 65. Guide port; 7. Inner cover; 81. Central shaft; 82. Driven bevel gear; 83. Driven bevel gear; 84. Stirring frame; 85. Guide frame; 9. Water tower tank; 101. Booster pump; 102. Electrically controlled valve; 103. Rotating end; 104. Connecting end; 105. Hollow cavity; 106. Water distribution hole; 11. Liquid level sensor; 12. Quantitative sensor; 13. Vibration damping seat. Detailed Implementation

[0025] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments: (a) Raw materials Red mud: Select pretreated industrial by-product red mud, dry it for later use.

[0026] Ultrafine fly ash: Ultrafine fly ash with a high specific surface area is used.

[0027] Blast furnace slag powder: S95 grade or equivalent active slag powder is used.

[0028] Desulfurized gypsum: as a sulfate regulating component.

[0029] Glass powder: It is produced by crushing, ball milling with grinding aid, drying and sieving waste glass.

[0030] Alkali activator: prepared by mixing sodium silicate solution and sodium hydroxide according to a set modulus.

[0031] Coarse aggregate: crushed stone or continuously graded stone.

[0032] Fine aggregate: natural sand, manufactured sand, or a combination thereof.

[0033] Basalt fiber: surface pretreated and modified.

[0034] High-alumina slag: used to prepare ion-curing agents.

[0035] Water-reducing agent: Polycarboxylate high-performance water-reducing agent.

[0036] Mixing water: Deionized water or tap water that meets the standards for concrete mixing.

[0037] (II) Preparation of red mud-based low-carbon cementitious materials Red mud, ultrafine fly ash, blast furnace slag powder, desulfurized gypsum and glass powder were mixed evenly in a mass ratio of 25:35:15:5:20 to obtain a solid cementitious precursor.

[0038] The glass powder is preferably prepared as follows: after crushing waste glass, anhydrous ethanol is used as the dispersion medium, and a composite grinding aid of 0.2% by mass of waste glass is added for ball milling. The ball milling time is controlled at 20 to 60 minutes, preferably 30 minutes. After ball milling, the slurry is dried and sieved to control the particle size to 45 to 150 μm, preferably with a specific surface area of ​​not less than 400 m² / kg.

[0039] The alkali activator was prepared by mixing a sodium silicate solution with a molar ratio of silica to sodium oxide of 3.29 with sodium hydroxide solid particles to obtain a composite alkali-activated system with a modulus of 1.45. The alkali activator was then mixed with a solid cementitious precursor to obtain a red mud-based low-carbon cementitious material.

[0040] The key technical points of the above design are: using red mud and glass powder to provide active aluminum and silicon components, using blast furnace slag powder to provide potential hydraulic components, and using desulfurized gypsum to regulate coagulation and promote specific hydration / activation reactions, ultimately forming a variety of cementitious products under alkaline activation conditions, thereby improving the continuity and density of the matrix.

[0041] (III) Preparation of aluminum-based basalt fibers First, the basalt fibers are cleaned and pretreated to remove surface oils and impurities. Then, the pretreated basalt fibers are impregnated in a silane coupling agent solution for modification, preferably using one or more of aminosilane coupling agents, epoxysilane coupling agents, or methacryloxysilane coupling agents to improve the activity of functional groups on the fiber surface.

[0042] Based on this, basalt fibers treated with coupling agents were placed in an Al(NO3)3 solution with a concentration of 0.05–0.2 mol / L for aluminum ion loading treatment for 0.5–4 hours. Subsequently, the pH of the system was adjusted to 6–7 by slowly adding ammonia or urea, allowing aluminum ions to preferentially deposit in situ on the fiber surface to form an Al(OH)3 layer. After washing and drying, aluminum-based basalt fibers were obtained.

[0043] This modification method transforms the fiber surface from a relatively inert state into a reinforcing phase with higher chemical activity and interfacial bonding ability, which is beneficial to improving the interfacial bonding strength between the fiber and the low-carbon cementitious matrix.

[0044] Aluminum-based basalt fibers, after surface pretreatment, silane coupling modification, and in-situ aluminum ion loading, exhibit an Al(OH)3 coating that enhances fiber surface activity and interfacial compatibility with the cementitious matrix, thereby strengthening interfacial bonding and stress transfer capabilities. In concrete, the modified fibers effectively bridge and inhibit crack propagation, significantly improving splitting tensile strength and crack toughness. Furthermore, under chloride erosion conditions, the enriched Ca(OH)2 and Al active sites, along with chloride ions near the fiber interface, facilitate the formation of calcium chloroaluminate-like compounds that fill interfacial pores. Under sulfate erosion conditions, this promotes the formation of localized insoluble precipitates, thus enabling the fiber interface to possess the dual functions of reinforcing and solidifying corrosive ions, improving the long-term service stability of concrete in complex corrosive environments.

[0045] Ca(OH)₂ + Al 3+ +Cl − →Calcium chloroaluminate Al 3+ +SO4 2- Other fiber surfactants → insoluble precipitates; Subsequently, aluminum-based basalt fiber reinforces the interfacial bonding, significantly improving crack resistance and toughness.

[0046] (iv) Preparation of high-alumina slag ion curing agent A high-alumina slag ion curing agent is prepared by mixing 75%–85% high-alumina slag, 0.05%–0.5% composite grinding aid, 0.1%–1.0% surface modifier, 1.0%–5.0% ionic solvent, and 10%–25% water by weight percentage. The preferred ratio is: 80% high-alumina slag, 0.1% composite grinding aid, 0.4% surface modifier, 2.0% ionic solvent, and 17.5% water.

[0047] The composite grinding aid is preferably composed of triethanolamine and ethylene glycol, with a mass percentage of 0.04% and 0.06%, respectively; the surface modifier is preferably composed of lignin sulfonate and PEG-400, with a mass percentage of 0.25% and 0.15%, respectively; and the ionic co-solvent is preferably composed of sodium aluminate and potassium silicate, with a mass percentage of 1.0% and 1.0%, respectively.

[0048] During preparation, high-alumina slag can be pre-ground to a specific surface area of ​​300-800 m² / kg, and then each component can be added to a mixing device. The stirring time is controlled at 10-60 min and the stirring speed is 200-800 rpm. If necessary, it can be aged for 0.5-24 h to obtain a uniform and stable slurry-like high-alumina slag ion curing agent.

[0049] A high-alumina slag ion-curing agent is introduced as a functional mineral admixture. After grinding-aid activation and ion-promoted solubility, this curing agent releases active Al and Si components, promoting the continuous generation of cementitious products, improving the pore structure of the hardened slurry and the interfacial transition zone, and reducing the proportion of harmful pores and interconnected pores. Simultaneously, its active aluminum component readily forms compound products, such as Friedel's salts, with calcium sources and chloride ions under chloride salt corrosion environments, and readily forms insoluble precipitates or relatively stable aluminum-containing sulfate products under sulfate environments. This achieves curing and inhibition of corrosive ions, reduces the chloride ion diffusion coefficient and free chloride ion content, and improves the material's corrosion resistance.

[0050] Ca 2+ +Al 3+ +Cl − →Friedel's salt (Ca3Al2O6⋅CaCl2⋅10H2O) Al 3+ +SO4 2- → Aluminum sulfate precipitation; Subsequently, high-alumina slag ion curing agents can significantly improve the density and corrosion resistance of the matrix.

[0051] (V) Preparation of erosion-resistant and crack-resistant low-carbon concrete The preferred basic mix proportions by weight are as follows: 450 parts adhesive, 753 parts fine aggregate, 1040 parts coarse aggregate, 153 parts water, 2.25-9 parts ion-curing agent, 5 parts polycarboxylate superplasticizer, and 1%-3% modified basalt fiber by volume. The water-to-adhesive ratio is preferably controlled between 0.25 and 0.40, more preferably between 0.30 and 0.38.

[0052] During preparation, coarse aggregate, fine aggregate, and red mud-based low-carbon cementitious material are first put into a mixer and dry-mixed for 10-60 seconds; then, high-alumina slag ion curing agent and some mixing water are added and wet-mixed for 30-120 seconds; subsequently, polycarboxylate superplasticizer, the remaining mixing water, and aluminum-based basalt fiber are added and the mixture is stirred for 60-300 seconds until the mixture is uniform.

[0053] Basalt fiber is preferably added in a dispersed manner, or premixed with some fine aggregate before being added, to reduce the risk of fiber agglomeration. After the concrete mixture is evenly mixed, it is poured, vibrated, and shaped before curing. Standard curing is preferred, with conditions of 20±2℃, relative humidity ≥95%, and a curing age of 3–28 days.

[0054] During the preparation of erosion-resistant and crack-resistant low-carbon concrete, red mud-based low-carbon cementitious material, coarse aggregate, fine aggregate, aluminum-based basalt fiber, high-alumina slag ion curing agent, polycarboxylate superplasticizer and water are added to the mixing tank 1 through the feeding hopper 2 for mixing. During the mixing, four sets of vibration damping seats 13 with vibration damping pads are fixed at the bottom of the mixing tank 1 to dampen and cancel the vibration. The erosion-resistant and crack-resistant low-carbon concrete prepared in step four is then discharged through the discharge hopper 3. The bottom of the mixing tank 1 is fixed with a fixing frame 4, and the fixing frame 4 is equipped with a longitudinal mixing component for dry / wet mixing of various materials in the mixing tank 1. The longitudinal mixing assembly includes a servo motor 51 fixed to the bottom of the fixed frame 4. A drive spur gear 52 is mounted on the servo motor 51, and driven spur gears 53 that rotate with the fixed frame 4 are meshed around the drive spur gear 52. Concentric shafts 54 that rotate with the mixing box 1 are fixed on the four sets of driven spur gears 53, and stirring rods 55 for longitudinal mixing of each material are alternately fixed on the concentric shafts 54. When mixing dry / wet materials added to the mixing box 1, longitudinal mixing is used to ensure uniform and thorough mixing. The two sets of feeding hoppers 2 are equipped with a material guiding component, and the material guiding component includes a material guiding impeller 61 sleeved on four stirring rods 55. The two sets of feeding hoppers 2 are provided with a discharge port 62 that rotates with the material guiding impeller 61 to guide the material, and a material guiding groove 63 is provided around the discharge port 62. A flow divider 64 is fixed on the inner side of the two sets of feeding hoppers 2, and a material guiding port 65 communicating with the mixing box 1 is provided below the flow divider 64. An inner cover 7 is fixed inside the mixing chamber 1, and a transverse mixing assembly is provided inside the inner cover 7. The assembly includes a central shaft 81 fixed to the output shaft of the servo motor 51 via a coupling. The central shaft 81 rotates with the mixing chamber 1 and extends to the top of the mixing chamber 1. Both the upper and lower sides of the central shaft 81 are fitted with drive bevel gears 82, and driven bevel gears 83 mesh around the drive bevel gears 82. A stirring frame 84 that rotates with the inner cover 7 is fixed to the outside of the driven bevel gears 83. This frame is used for transverse mixing of various materials. When adding dry / wet materials into the mixing chamber 1, a transverse mixing method is used to ensure uniform and thorough mixing. Combined with the longitudinal mixing of the stirring rod 55, this further enhances the thoroughness and efficiency of the dry / wet mixing of various materials.

[0055] Furthermore, the inner cover 7 is fixed with material guides 85 that intersect with the stirring rod 55 and the stirring frame 84, and are fixed to the mixing box 1. The material guides 85 guide the materials falling into the bottom of the mixing box 1.

[0056] During the preparation of erosion-resistant and crack-resistant low-carbon concrete, a water tower tank 9 is used to add red mud-based low-carbon cementitious materials, coarse aggregate, fine aggregate, alumina-based basalt fiber, high-alumina slag ion curing agent, polycarboxylate superplasticizer, and water to the wet mixture in the mixing tank 1. The water tower tank 9 is equipped with a liquid level sensor 11 for liquid level monitoring, and a water distribution assembly is installed on the water tower tank 9. A booster pump 101 is embedded in the top of the water tower tank 9, and an electrically controlled valve 1 with a metering sensor 12 is connected to the bottom of the water tower tank 9. 02, and the bottom end of the electric control valve 102 is connected to a rotating end 103, and the rotating end 103 is rotatably connected to a connecting end 104, which is connected to the hollow cavity 105 opened in the central shaft 81. Water distribution holes 106 connected to the hollow cavity 105 are opened around the central shaft 81. When wet mixing is required, the swirling water distribution method is adopted to distribute water evenly and comprehensively in each material area, improve the uniformity and fullness of contact between each material and water, and make the wet mixing more thorough.

[0057] The working principle described above is as follows: First, control the servo motor 51 to turn on and drive the drive spur gear 52 and the central shaft 81 to rotate synchronously. The drive spur gear 52 drives the concentric shafts 54 on the four sets of driven spur gears 53 to rotate accordingly. The four concentric shafts 54 drive the four stirring rods 55 and the guide impellers 61 on them to rotate synchronously. The four stirring rods 55 in the rotating state perform longitudinal dry mixing of the materials in the mixing box 1. During the feeding process, the four sets of synchronously rotating guide impellers 61 drive the materials injected into the discharge ports 62 of the two sets of feeding hoppers 2 in batches to perform dynamic material guiding treatment, forcing the materials added in batches to fall into the mixing box 1 through the discharge ports 62 and the guide troughs 63 around them. The flow dividers 64 in the two sets of feeding hoppers 2 guide the materials added in batches to the guide impeller 61 area at the discharge ports 62. At the same time, the materials can also fall into the mixing box 1 through the guide ports 65. At the same time, the central shaft 81 drives the upper and lower sets of drive bevel gears 82 to rotate, and the two sets of drive bevel gears 82 drive the stirring frame 84 on the four sets of driven bevel gears 83 to rotate laterally at the inner cover 7. Then, the materials in the mixing box 1 are subjected to lateral dry mixing. When the four stirring rods 55 and the stirring frame 84 are used to dry mix the materials longitudinally and laterally, the material guide frame 85 guides the materials through them, forcing them to be mixed evenly and fully. When wet mixing is required, the booster pump 101 and the electric control valve 102 are turned on, and the booster pump 101 pressurizes the water tank 9, forcing the water that has been added to the water tank 9 in advance to be quantitatively processed by the quantitative sensor 12 on the electric control valve 102. After passing through the rotating end 103 and the connecting end 104, the water is pressurized and reaches the hollow cavity 105 in the central shaft 81. Then, the water is evenly distributed to each material area in the mixing box 1 through the water distribution hole 106. The stirring rod 55 and the stirring frame 84 perform wet mixing of each material in the longitudinal and transverse directions. During this period, the water level sensor 11 monitors the water level in the water tank 9 in real time so that water can be added in time.

[0058] This application also proposes the application of corrosion-resistant and crack-resistant low-carbon concrete, which can be used in marine engineering, port engineering, offshore wind power foundations, coastal buildings, cross-sea bridges, seawalls, breakwaters, engineering in saline soil areas, and concrete structures subjected to the combined effects of chloride, sulfate and wet-dry cycles.

[0059] The erosion-resistant and crack-resistant low-carbon concrete constructs a multi-solid-waste synergistic cementitious system using red mud, fly ash, blast furnace slag powder, desulfurized gypsum, and glass powder. Under the action of an alkali activator, it forms a cementitious matrix with high density and low carbon emissions.

[0060] High-alumina slag ion curing agent fills and densifies the pore structure of concrete by releasing active aluminum-silicon components and promoting the formation of cementitious products. At the same time, it enhances the curing and blocking effect on corrosive ions, thereby reducing the migration rate of chloride ions, sulfate ions and other harmful media in concrete.

[0061] Aluminum-based basalt fibers improve the interfacial bonding between the fibers and the cementitious matrix by loading an Al(OH)3 layer on the surface in situ, thereby enhancing crack bridging, stress transmission, and crack propagation inhibition capabilities, and thus improving the crack resistance, toughness, and service stability of concrete.

[0062] The synergistic effect of high-alumina slag ion curing agent and aluminum-based basalt fiber improves the density and corrosion resistance of the matrix on the one hand, and inhibits the initiation and propagation of microcracks on the other hand, thereby significantly improving the durability of concrete in high-salt, high-humidity, alternating wet and dry, freeze-thaw and multi-ion coupling environments.

[0063] Compared to ordinary silicate cement concrete, erosion-resistant and crack-resistant low-carbon concrete has lower clinker usage and higher solid waste resource utilization rate. It also has comprehensive advantages such as high compressive strength, excellent impermeability, strong resistance to chloride ion penetration, good resistance to sulfate attack, and excellent crack resistance.

[0064] According to standard GB50081-2019, the compressive strength and splitting tensile strength of 150mm×150mm×150mm cubic concrete specimens were tested. The concrete erosion coefficient was measured according to GB / T749; the chloride ion diffusion coefficient of concrete was tested according to GB / T50082-2024.

[0065] Cement mortar was prepared according to the curing method specified in GB / T17671-1999 "Test Method for Strength of Cement Mortar" and the content of free chloride ions in the mortar specimen was rapidly determined at room temperature using the ion-selective electrode method according to the standard SL352-2006 "Test Procedure for Hydraulic Concrete".

[0066] Concrete mix proportion data table Concrete test data sheet (vi) Performance testing methods 150mm×150mm×150mm cubic concrete specimens were prepared in accordance with GB50081-2019, and their compressive strength and splitting tensile strength were tested.

[0067] The concrete erosion coefficient is measured according to GB / T749.

[0068] The chloride ion diffusion coefficient of concrete was tested according to GB / T50082-2024.

[0069] Cement mortar specimens were prepared according to GB / T17671-1999, and the free chloride ion content in the mortar specimens was determined by ion-selective electrode method according to SL352-2006.

[0070] III. Examples and Analysis Examples 1-4: Effect of Ion Curing Agent Dosage Mix ratio Under the condition that the volumetric content of adhesive, aggregate, water, water-reducing agent and modified basalt fiber remains unchanged, the content of high-alumina slag ion curing agent is gradually increased, as shown in the table below: Example 1: 2.25 parts of ion curing agent Example 2: 4.5 parts of ion curing agent Example 3: 6.75 parts of ion curing agent Example 4: 9 parts of ion curing agent The other components remain as follows: 450 parts of adhesive, 753 parts of fine aggregate, 1040 parts of coarse aggregate, 153 parts of water, 5 parts of water-reducing agent, and 2 vol of modified basalt fiber.

[0071] Results Analysis The test results show that as the dosage of ion curing agent increased from 2.25 parts to 9 parts, the erosion resistance coefficient of concrete increased from 1.01 to 1.17, indicating that the material's ability to resist environmental damage continued to improve; the chloride ion content decreased from 0.0465% to 0.0312%, indicating that the system's ability to block and cure chloride ions gradually improved.

[0072] From a mechanical property perspective, the compressive strength increased from 44.8 MPa to 49.7 MPa, and the splitting tensile strength increased from 5.3 MPa to 5.9 MPa, indicating that an appropriate amount of ion-curing agent helps improve the matrix density and the quality of the interfacial transition zone. In particular, in Example 3, the compressive strength reached 50.2 MPa, the highest among all groups; the chloride ion diffusion coefficient decreased to 0.027 × 10^-12 m² / s, the lowest in the group, indicating that a better balance was achieved between strength and durability at a dosage of 6.75 parts.

[0073] When the dosage was further increased to 9 parts, although the corrosion resistance coefficient and chloride ion content continued to improve, the compressive strength decreased slightly compared to Example 3, and the chloride ion diffusion coefficient also increased slightly. This indicates that although excessive dosage of ion-curing agent enhances the inhibition effect on corrosive media, it may cause a decrease in microstructure uniformity due to excessively rapid local reactions, increased slurry viscosity, or excessive amounts of some active components, thereby slowing down or even slightly reducing the improvement in mechanical properties.

[0074] Therefore, Examples 1-4 show that the high-alumina slag ion curing agent can significantly improve the erosion resistance and strength of concrete. Its preferred dosage range is about 1.5% to 2.0% of the mass of cementitious materials, and more preferably close to the dosage level corresponding to Example 3.

[0075] Examples 5-6: Effect of modified basalt fiber content Mix ratio With the ion-curing agent content remaining constant at 9 parts, the volumetric content of modified basalt fibers was varied: Example 5: 1 vol% Example 4: 2 vol% Example 6: 3 vol% Results Analysis Comparing Examples 5, 4, and 6, it can be seen that as the volumetric content of modified basalt fiber increases from 1 vol% to 3 vol%, the splitting tensile strength increases from 5.5 MPa to 6.4 MPa, the erosion resistance coefficient increases from 1.13 to 1.20, and the chloride ion content decreases from 0.0341% to 0.0297%. These results indicate that modified basalt fiber has a significant effect on improving the crack resistance, integrity, and stability of the material under corrosive environments.

[0076] Example 6 exhibited the highest erosion resistance coefficient and the highest splitting tensile strength, indicating that higher fiber content is more effective in suppressing the initiation and propagation of microcracks and delaying the penetration of corrosive media along crack channels through bridging. Its chloride ion diffusion coefficient was also low, at 0.029 × 10⁻¹² m² / s, further demonstrating that fiber reinforcement did not weaken the system's durability; on the contrary, it improved ion transport behavior to some extent through crack control.

[0077] It should be noted that as the fiber content increased from 2 vol% to 3 vol%, the compressive strength decreased from 49.7 MPa to 47.1 MPa. This phenomenon indicates that although increasing the fiber content is beneficial to improving toughness and crack resistance, excessive fibers may lead to difficulties in dispersion, local agglomeration, or increased air encapsulation, which may affect the continuity of the concrete matrix and thus have an adverse effect on the compressive strength.

[0078] Therefore, the modified basalt fiber in this invention should preferably be controlled within the range of 0.5% to 2.0% to obtain more balanced comprehensive performance; when engineering requirements place more emphasis on crack resistance and erosion resistance, the dosage can also be appropriately increased to 3.0%.

[0079] Comparative Example 1: Only modified basalt fiber was added, without ion curing agent. Mix ratio Comparative Example 1 is basically the same as the Example System, but does not contain high-alumina slag ion curing agent, and the fiber volume content is 2 vol.

[0080] Results Analysis Comparative Example 1 has an erosion resistance coefficient of 0.91, a compressive strength of 43.9 MPa, a splitting tensile strength of 5.0 MPa, a chloride ion diffusion coefficient of 0.048 × 10^-12 m² / s, and a chloride ion content of 0.0472%. Compared with Examples 1 to 4, its overall performance is lower, especially in terms of erosion resistance and chloride ion migration control.

[0081] The results indicate that while the bridging and toughening effect of modified fibers can improve crack control to some extent, it cannot fundamentally change the pore structure characteristics of the slurry and the interface transition zone, nor can it effectively inhibit the diffusion of corrosive media such as chlorides within the material. Therefore, ion-curing agents play a crucial role in matrix densification and ion blocking in this invention, and are an essential component for achieving high durability.

[0082] Comparative Example 2: Only ion-curing agent was added, without modified basalt fiber. Mix ratio Comparative Example 2 was mixed with 9 parts of ion curing agent, but without the addition of modified basalt fiber.

[0083] Results Analysis The corrosion resistance coefficient of Comparative Example 2 was 1.09, which was significantly higher than that of Comparative Example 1, indicating that the ion curing agent can effectively improve corrosion resistance and inhibit chloride ion migration. Its chloride ion content was reduced to 0.0328%, which was also significantly lower than that of Comparative Example 1 and Comparative Example 3, further proving that the ion curing agent has a significant inhibitory effect on the transport of corrosive media.

[0084] However, the compressive strength of Comparative Example 2 was only 42.8 MPa, and the splitting tensile strength was only 4.5 MPa, both lower than those of Examples 4 and 6, with the splitting tensile strength showing a more significant decrease. This indicates that matrix densification alone cannot adequately address the microcrack propagation problem in brittle materials under the coupled effects of load and environment. Without the bridging and crack-inhibiting effect of modified fibers, the material is more prone to crack formation under tensile and shrinkage stresses, thus weakening its overall service performance.

[0085] Therefore, Comparative Example 2 further demonstrates that ion curing agents mainly improve the matrix structure and durability, while modified fibers mainly improve crack control and toughness. The two have different functions and are both indispensable.

[0086] Comparative Example 3: Contains neither ionomer curing agents nor modified basalt fibers. Mix ratio Comparative Example 3 did not contain high-alumina slag ion curing agent or modified basalt fiber.

[0087] Results Analysis Comparative Example 3 exhibited the lowest erosion resistance coefficient, at only 0.86; compressive strength of 41.2 MPa; splitting tensile strength of 4.2 MPa; highest chloride ion diffusion coefficient of 0.062 × 10⁻¹² m² / s; and highest chloride ion content of 0.0531%. These results indicate that, without the synergistic reinforcement of ion-curing agents and modified fibers, red mud-based low-carbon concrete possesses certain cementing capabilities, but still exhibits significant deficiencies in erosion resistance, crack resistance, and ion transport control.

[0088] This comparative example serves as direct proof of the necessity of the synergistic design of the present invention. Compared with Examples 3, 4, and 6, the present invention achieves a systematic improvement in material properties through the synergistic construction method of "low-carbon cementitious matrix - ion curing agent - aluminum-based basalt fiber," rather than a local improvement in a single parameter.

[0089] IV. Overall Conclusion Based on the combined examples and comparative examples, the following conclusions can be drawn: This invention employs a low-carbon cementing system constructed from red mud, ultrafine fly ash, blast furnace slag powder, desulfurized gypsum, and glass powder. This system can achieve better mechanical properties while reducing clinker consumption and improving the utilization rate of solid waste resources.

[0090] High-alumina slag ion curing agent can significantly improve the pore structure and interfacial density of concrete, and enhance the ability to impede and cure corrosive ions, thereby significantly reducing the chloride ion diffusion coefficient and free chloride ion content.

[0091] Aluminum-based basalt fibers can significantly improve splitting tensile strength and crack toughness, and enhance the stability of materials in corrosive environments through crack bridging.

[0092] There is a significant synergistic effect between the ion curing agent and the aluminum-based basalt fiber, which can achieve the unity of matrix densification and crack control, thereby simultaneously improving compressive strength, erosion resistance, chloride ion penetration resistance and crack resistance.

[0093] From the perspective of overall performance, Examples 3 and 6 represent two preferred solutions with "better balance of strength and durability" and "better crack resistance and corrosion resistance", respectively, both of which demonstrate the significant technical progress of the present invention.

[0094] It should be noted that the specific models and specifications of the servo motor 51, booster pump 101, solenoid valve 102, level sensor 11 and metering sensor 12 need to be selected and determined according to the actual specifications of the device. The specific selection calculation method adopts the existing technology in this field, so it will not be described in detail.

[0095] The power supply circuits for the servo motor 51, booster pump 101, solenoid valve 102, level sensor 11, and metering sensor 12 are clear to those skilled in the art and will not be described in detail here.

[0096] It is understood that the present invention has been described through some embodiments, and those skilled in the art will recognize that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of the invention. Furthermore, under the teachings of the present invention, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of the invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the protection scope of the present invention.

Claims

1. A low-carbon concrete resistant to erosion and cracking, characterized in that: It is made from red mud-based low-carbon cementitious materials, coarse aggregate, fine aggregate, aluminum-based basalt fiber, high-alumina slag ion curing agent, polycarboxylate superplasticizer and water; The raw materials, by weight, include: 350-550 parts of red mud-based low-carbon cementitious material, 950-1100 parts of coarse aggregate, 650-900 parts of fine aggregate, 0.3-6 parts of modified basalt fiber, 10-60 parts of high-alumina slag ion curing agent, 2-8 parts of polycarboxylate superplasticizer, and 100-250 parts of water.

2. The erosion-resistant and crack-resistant low-carbon concrete according to claim 1, characterized in that: The water-cement ratio of the low-carbon concrete is 0.25–0.40, and the dosage of the polycarboxylate superplasticizer is 0.5%–1.0% of the total mass of the cementitious material. The red mud-based low-carbon cementitious material is composed of a solid cementitious precursor and an alkali activator. The solid cementitious precursor is composed of red mud, ultrafine fly ash, blast furnace slag powder, desulfurized gypsum, and glass powder. The alkali activator is composed of sodium silicate solution and sodium hydroxide solid particles. The molar ratio of silicon dioxide to sodium oxide in the sodium silicate solution is 3.29, and the composite alkali activator formed by mixing the sodium silicate solution and sodium hydroxide has a modulus of 1.

45.

3. The erosion-resistant and crack-resistant low-carbon concrete according to claim 2, characterized in that: The red mud-based low-carbon cementitious material comprises, by mass, 20-40 parts red mud, 20-40 parts ultrafine fly ash, 10-30 parts blast furnace slag powder, 5-15 parts desulfurized gypsum, 10-30 parts glass powder, and 5-15 parts alkali activator. The glass powder is obtained from waste glass through crushing, ball milling with grinding aid, drying, and sieving. During ball milling of the waste glass, anhydrous ethanol is used as the solvent, and a composite grinding aid of 0.2% by mass of the waste glass is added. The ball milling time is 20-60 minutes, preferably 30 minutes. After ball milling, the glass powder is dried and sieved. The coarse aggregate is crushed stone or continuously graded stone, and the fine aggregate is natural sand, manufactured sand, or a combination thereof. The aluminum-based basalt fiber is obtained from basalt fiber after surface pretreatment, silane coupling agent impregnation modification, and aluminum ion loading treatment.

4. The erosion-resistant and crack-resistant low-carbon concrete according to claim 3, characterized in that: The aluminum ion loading treatment is as follows: basalt fibers impregnated with silane coupling agent are placed in an Al(NO3)3 solution with a concentration of 0.05–0.2 mol / L. Subsequently, the pH of the system is slowly adjusted to 6–7 by adding ammonia or urea, so that an aluminum hydroxide precipitate layer is generated in situ on the surface of the basalt fibers, and an Al(NO3)3 coating layer is preferentially formed on the fiber surface.

5. The erosion-resistant and crack-resistant low-carbon concrete according to claim 4, characterized in that: The aluminum-based basalt fiber accounts for 0.1% to 3.0% of the total mass of the cementitious material. The high-alumina slag ion curing agent is prepared by combining high-alumina slag, composite grinding aid, surface modifier, ion-promoting solvent and water. The components of the high-alumina slag ion curing agent include, by mass percentage: 75% to 85% high-alumina slag, 0.05% to 0.5% composite grinding aid, 0.1% to 1.0% surface modifier, 1.0% to 5.0% ion-promoting solvent and 10% to 25% water.

6. The erosion-resistant and crack-resistant low-carbon concrete according to claim 5, characterized in that: The composite grinding aid includes triethanolamine and ethylene glycol, with mass percentages of 0.04% and 0.06% for triethanolamine and ethylene glycol, respectively. The surface modifier includes lignin sulfonate and PEG-400, with mass percentages of 0.25% and 0.15% for lignin sulfonate and PEG-400, respectively. The ionic co-solvent includes sodium aluminate and potassium silicate, with mass percentages of 1.0% and 1.0% for sodium aluminate and potassium silicate, respectively. The high-alumina slag ionic curing agent is incorporated into the low-carbon concrete as a functional mineral admixture, with a dosage of 2% to 10% of the total mass of the cementitious materials, preferably 3% to 8%. In the low-carbon concrete, the red mud-based low-carbon cementitious materials partially or completely replace the traditional silicate cementitious system, thereby reducing the amount of cement clinker used and carbon emissions during the preparation process.

7. A method for preparing erosion-resistant and crack-resistant low-carbon concrete, comprising the erosion-resistant and crack-resistant low-carbon concrete according to any one of claims 1-6, characterized in that: Includes the following steps: Step 1: Preparation of red mud-based low-carbon cementitious materials; Step 2: Preparation of aluminum-based basalt fibers; Step 3: Preparation of high-alumina slag ion curing agent; Step 4: Mix and stir the red mud-based low-carbon cementitious material, coarse aggregate, fine aggregate, aluminum-based basalt fiber, high-alumina slag ion curing agent, polycarboxylate superplasticizer and water to obtain erosion-resistant and crack-resistant low-carbon concrete.

8. The method for preparing erosion-resistant and crack-resistant low-carbon concrete according to claim 7, characterized in that: In step one, the preparation of the red mud-based low-carbon cementitious material includes: mixing red mud, ultrafine fly ash, blast furnace slag powder, desulfurized gypsum, and glass powder in a certain proportion to obtain a solid cementitious precursor; mixing sodium silicate solution with sodium hydroxide to prepare an alkali activator; and then mixing the alkali activator with the solid cementitious precursor to obtain the red mud-based low-carbon cementitious material. In step one, the preparation of the glass powder includes: crushing waste glass, using anhydrous ethanol as a solvent, adding 0.2% of a composite grinding aid by weight of the waste glass, and ball milling for 20-60 minutes; drying and sieving after ball milling to obtain the glass powder. Further optionally, in step one, the sieved particle size is 45-150 μm, preferably the specific surface area of ​​the glass powder is not less than 400 m² / kg, and in step one, the alkaline activator is prepared by using a sodium silicate solution with a molar ratio of silicon dioxide to sodium oxide of 3.29 and mixing it with solid sodium hydroxide, so that the modulus of the composite activation system after mixing is 1.45; In step two, the preparation of aluminum-based basalt fibers includes: surface cleaning and pretreatment of basalt fibers; impregnation and modification of the pretreated basalt fibers in a silane coupling agent solution to obtain surface-activated fibers; aluminum ion loading treatment of the surface-activated fibers in an Al(NO3)3 solution; slow adjustment of the pH value of the system to 6-7 by adding ammonia or urea to allow aluminum ions to preferentially deposit on the surface of the basalt fibers to form an Al(OH)3 layer; and obtaining the aluminum-based basalt fibers after washing and drying. In step two, the silane coupling agent is one or more of aminosilane coupling agents, epoxysilane coupling agents, or methacryloxysilane coupling agents. In step two, the concentration of the Al(NO3)3 solution is 0.05-0.2 mol / L, the aluminum ion loading treatment time is 0.5-4 h, and the drying temperature is 40-80 °C. In step three, the preparation of the high-alumina slag ion curing agent includes: adding high-alumina slag, composite grinding aid, surface modifier, and ion-promoting solvent into a mixing device and mixing them evenly; adding water and continuing stirring to activate the surface of the high-alumina slag particles through grinding and ion-promoting solubilization modification, thereby obtaining a slurry-like high-alumina slag ion curing agent; and, if necessary, performing an aging treatment to improve the uniformity and activation effect of the system. In step three, the high-alumina slag can be pre-ground to achieve a specific surface area of ​​300–800 m² / kg. In step three, the mixing and stirring time is 10–60 min, the stirring speed is 200–800 rpm, and the aging time is 0.5–24 h. In step three, the triethanolamine and ethylene glycol in the composite grinding aid work synergistically to improve the grinding efficiency and particle dispersibility of the high-alumina slag; the lignin sulfonate and PEG-400 work synergistically to improve the wettability of the particle surface and interfacial compatibility; and the sodium aluminate and potassium silicate are used to improve the release capacity of aluminum-silicon active ions. In step four, the preparation of the erosion-resistant and crack-resistant low-carbon concrete includes: first, dry mixing coarse aggregate, fine aggregate, and red mud-based low-carbon cementitious material in a mixer for 10-60 seconds; then, adding high-alumina slag ion curing agent and some mixing water for wet mixing for 30-120 seconds; subsequently, adding polycarboxylate superplasticizer, the remaining mixing water, and alumina-based basalt fiber and continuing mixing for 60-300 seconds; after uniform mixing, the erosion-resistant and crack-resistant low-carbon concrete mixture is obtained; in step four, the alumina-based basalt fiber is added in a dispersed manner, or premixed with some fine aggregate before being added, to avoid fiber agglomeration; in step four, the concrete mixture is poured, vibrated, and molded before curing, and the curing method is one of standard curing, steam curing, or composite curing; the standard curing conditions are a temperature of 20±2℃, a relative humidity of ≥95%, and a curing age of 3-28 days.

9. The method for preparing erosion-resistant and crack-resistant low-carbon concrete according to claim 8, characterized in that: In step four, red mud-based low-carbon cementitious material, coarse aggregate, fine aggregate, aluminum-based basalt fiber, high-alumina slag ion curing agent, polycarboxylate superplasticizer and water are added to the mixing tank (1) through the feeding hopper (2) for mixing and stirring. During the stirring, four sets of shock-absorbing seats (13) with shock-absorbing pads are fixed at the bottom of the mixing tank (1) to dampen and cancel its vibration. Then, the anti-erosion and cracking low-carbon concrete obtained in step four is discharged through the discharge hopper (3). The bottom of the mixing tank (1) is fixed with a fixing frame (4). The fixing frame (4) is equipped with a longitudinal mixing component for dry / wet mixing of each material in the mixing tank (1). The longitudinal mixing assembly includes a servo motor (51) fixed at the bottom of the fixed frame (4). The servo motor (51) is fitted with a drive spur gear (52), and the drive spur gear (52) is meshed with driven spur gears (53) that rotate with the fixed frame (4) on all four sides. The four sets of driven spur gears (53) are fixed with concentric shafts (54) that rotate with the mixing box (1), and the concentric shafts (54) are staggered with stirring rods (55) for longitudinal mixing of each material. The two sets of feeding hoppers (2) are equipped with a material guiding assembly, and the material guiding assembly includes a material guiding impeller (61) sleeved on the four stirring rods (55). The two sets of feeding hoppers (2) are provided with a discharge port (62) that rotates with the material guiding impeller (61) to guide the material. The discharge port (62) is provided with a material guiding groove (63) around its perimeter. The two sets of feeding hoppers (2) are fixed with a flow divider (64) on their inner side. The flow divider (64) is provided with a material guiding port (65) communicating with the mixing box (1) below its lower side. The mixing box (1) is fixed with an inner cover (7), and the inner cover (7) is provided with a horizontal mixing component, including a central shaft (81) fixed to the output shaft of the servo motor (51) by a coupling. The central shaft (81) rotates with the mixing box (1) and extends to the top of the mixing box (1). The upper and lower sides of the central shaft (81) are fitted with drive bevel gears (82), and the drive bevel gears (82) are meshed with driven bevel gears (83) around the periphery. The outer side of the driven bevel gears (83) is fixed with a stirring frame (84) that rotates with the inner cover (7) for horizontal mixing of various materials. The inner cover (7) is fixed with a guide frame (85) that intersects with the stirring rod (55) and the stirring frame (84) and is fixed to the mixing box (1).

10. The method for preparing erosion-resistant and crack-resistant low-carbon concrete according to claim 9, characterized in that: In step four, a water tower tank (9) is used to add red mud-based low-carbon cementitious material, coarse aggregate, fine aggregate, aluminum-based basalt fiber, high-alumina slag ion curing agent, polycarboxylate superplasticizer and water to the mixing tank (1) for wet mixing. The water tower tank (9) is equipped with a liquid level sensor (11) for liquid level monitoring. A water distribution assembly is provided on the water tower tank (9), and a booster pump (101) is embedded in the top of the water tower tank (9). The bottom of the water tower tank (9) is connected to an electric control valve (102) with a quantitative sensor (12). The bottom end of the electric control valve (102) is connected to a rotating end (103). The rotating end (103) is rotatably connected to a connecting end (104) and is connected to a hollow cavity (105) opened in the central shaft (81). Water distribution holes (106) connected to the hollow cavity (105) are opened around the central shaft (81).

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