A cement-based anti-composite salt corrosion material and its preparation method

Abstract

This invention discloses a cement-based anti-composite salt corrosion material and its preparation method. The material is composed of a core cementitious and micro-aggregate component, a key anti-corrosion component, and a rheology-aiding component blended in specific mass percentages. The key anti-corrosion component includes magnesium aluminum silicate / attapulgite, lithium carbonate / lithium nitrate, and microencapsulated rust inhibitors, specifically addressing the core challenges of resisting magnesium salt corrosion, inhibiting sulfate damage, and achieving intelligent crack repair. The preparation method employs meticulous processes such as raw material grouping pretreatment, segmented temperature-controlled calcination to protect activity, multi-stage speed-matched mixing, and closed-loop verification of uniformity to ensure consistent and stable product performance. When used as an admixture in concrete, it significantly improves the concrete's resistance to composite salt corrosion, resistance to wet-dry cycle damage, and endows it with self-healing potential for cracks, while maintaining excellent workability and strength. Its overall durability is superior to existing technologies.

Description

Technical Field

[0001] This invention belongs to the field of civil engineering building materials technology, specifically relating to a cement-based anti-composite salt corrosion-resistant material suitable for strong composite salt corrosion environments (coupling effects of high concentrations of chloride, sulfate, and magnesium salts) and its preparation method. Background Technology

[0002] Formed over many years by the Bohai Sea's erosion, salt fields contain high levels of chlorides, sulfates, and magnesium salts in their soil and groundwater, creating a highly corrosive and complex environment. In this environment, concrete structures face severe challenges from chloride ion corrosion, sulfate corrosion, magnesium salt corrosion, and their coupled effects, leading to premature degradation of durability. Current technological approaches to improving concrete durability in such environments primarily include optimizing concrete mix proportions (such as using sulfate-resistant cement, adding mineral admixtures and corrosion inhibitors) and implementing external protective measures (such as using special reinforcing steel and surface coatings). However, these technologies often suffer from high costs, limited applicability, and the potential to impair concrete workability or long-term performance.

[0003] In the technical direction of enhancing the corrosion resistance of concrete through functional admixtures, Chinese invention patent CN202211332348.1 (Invention title: A corrosion-resistant rheology modifier suitable for the highly corrosive environment of coastal salt fields and its preparation method and application) provides a representative solution. This prior art discloses a corrosion-resistant rheology modifier composed of the following components by mass percentage: 30%~40% fly ash, 20%~25% nano-SiO2, 10%~20% heavy calcium carbonate powder, 15%~20% viscosity reducer, 5%~10% metakaolin, 5%~10% zeolite powder, and 0.1%~0.5% fluidizing agent. This technical solution aims to improve the workability of concrete mixtures (such as reducing plastic viscosity) and enhance the concrete's resistance to chloride and sulfate corrosion through the synergistic effect of its components. Its beneficial effects are mainly reflected in improved workability and enhanced durability indicators.

[0004] However, based on in-depth analysis and feedback from engineering practice, the existing technical solution still has the following limitations or areas for improvement:

[0005] (1) Insufficient targeted protection against high-concentration magnesium salt erosion: In coastal salt field environments, high concentrations of magnesium ions (Mg) 2+ The destructive decomposition of cement hydration products (such as CSH gel) (generating non-cementing magnesium hydroxide) is one of the key factors leading to concrete softening and strength loss. While existing technical solutions can improve density, they lack the ability to preferentially and efficiently bind or fix Mg. 2+The functional components of magnesium salts have a relatively passive and indirect mechanism for inhibiting magnesium salt corrosion. Under long-term, high-concentration magnesium salt environments, their protective effect may not be sufficient or durable.

[0006] (2) The protection mechanism is passive and lacks continuous and active protection capabilities: The existing technology mainly improves the initial density of concrete by physical filling (such as nano-SiO2, zeolite powder) and improving rheology, thereby blocking the intrusion of corrosive media. This is a passive protection mode of "one-time molding". When concrete inevitably produces microcracks under long-term load, wet-dry cycle or environmental stress, corrosive media will quickly intrude along the cracks. However, the existing technology does not have the ability to detect and repair microcracks, nor can it provide additional targeted chemical protection when the local pH value decreases or the chloride ion concentration increases, resulting in the risk of long-term degradation of its protective effectiveness.

[0007] (3) Long-term durability under harsh wet-dry cycle conditions needs further improvement: Concrete structures in coastal salt fields are often in a wet-dry cycle environment, which intensifies the crystallization-dissolution cycle of salts in the pores and generates huge crystallization pressure. Although existing technical solutions can reduce total porosity, they have not yet carried out targeted component design and functional enhancement in terms of optimizing pore structure, refining pore size distribution, and especially enhancing the ability to resist repeated crystallization damage from salts (especially magnesium sulfate and magnesium chloride). There may be room for improvement in their long-term resistance to salt crystallization damage.

[0008] Therefore, developing a new type of cement-based anti-corrosion material that not only inherits the advantages of existing technologies in improving workability and basic corrosion resistance, but also specifically enhances resistance to magnesium salt corrosion, introduces active or intelligent protection mechanisms, and significantly improves long-term durability under harsh conditions such as wet-dry cycles, is of urgent practical significance and important technical value for ensuring the century-long lifespan of major infrastructure in coastal salt fields. This invention was made against this backdrop. Summary of the Invention

[0009] To address the shortcomings of existing technologies, this invention discloses a cement-based anti-composite salt corrosion material, the technical solution of which is as follows:

[0010] A cement-based anti-composite salt corrosion material, characterized in that it is composed of the following components by mass percentage:

[0011] Core cementitious and micro-aggregate components: 25%~35% fly ash, 15%~20% nano-SiO2, and 10%~15% of the aforementioned heavy calcium carbonate powder;

[0012] Key anti-corrosion components: 5%~15% nano- or micro-sized magnesium aluminum silicate or attapulgite, 3%~8% lithium carbonate or lithium nitrate, 2%~6% microencapsulated amino alcohols or fatty acid esters as rust inhibitors.

[0013] Rheology modifiers: 10%~18% spherical viscosity reducer, 5%~10% metakaolin, 3%~8% zeolite powder, and 0.1%~0.8% polycarboxylate or aminosulfonate fluidizing agent.

[0014] Preferably, the magnesium aluminum silicate is a purified bentonite extract; the capsule wall of the microencapsulated amino alcohol or fatty acid ester rust inhibitor is a pH-sensitive polymer; and the spherical viscosity reducer is silica and alumina microspheres.

[0015] This invention also discloses a method for preparing the above-mentioned cement-based anti-composite salt corrosion material, characterized by comprising the following sequential steps:

[0016] S1: Raw material preparation and pretreatment: Weigh out the formula amounts of fly ash, heavy calcium carbonate powder, zeolite powder, spherical viscosity reducer, lithium carbonate or lithium nitrate, and fluidizing agent for later use; place the formula amounts of nano SiO2, magnesium aluminum silicate or attapulgite, and metakaolin into a drying device.

[0017] S2: Segmented temperature-controlled drying: The nano-SiO2, magnesium aluminum silicate or attapulgite, metakaolin are dried; the drying process adopts a segmented heating method, firstly, the first stage of preliminary drying is carried out at a temperature of 80±5℃, and then the temperature is raised to 105℃±2℃ for the second stage of deep drying, until the moisture content of the material is lower than 0.8% (mass fraction).

[0018] S3: Primary basic mixing: The fly ash, heavy calcium carbonate powder, zeolite powder, spherical viscosity reducer, lithium carbonate or lithium nitrate prepared in step S1, together with the nano-SiO2, magnesium aluminum silicate or attapulgite clay and metakaolin clay dried and cooled to room temperature in step S2, are put into a high-efficiency three-dimensional motion mixer.

[0019] S4: Dynamic homogenization mixing: Start the mixer and run it at a speed of 35-45 rpm for 8-12 minutes in the first mixing stage to achieve a preliminary uniform spatial distribution of all powder materials;

[0020] S5: Introduction of sensitive functional components: While the mixer is running at a low speed of 20-30 rpm, the microencapsulated amino alcohol or fatty acid ester rust inhibitor is introduced into the mixing system at a uniform speed through a special feeding port, and the mixing continues for 4-6 minutes at this speed.

[0021] S6: Fluidization efficiency adjustment and final mixing: Add the formulated amount of fluidizing agent to the mixing system in step S5, then increase the mixer speed to 25-35 rpm and run for 6-9 minutes to complete the final mixing;

[0022] S7: Uniformity verification and calibration: Take samples from multiple points in the mixer and test the distribution variation coefficient of the key components (using nano-SiO2 and microcapsule corrosion inhibitors as indicators); if the variation coefficient is ≤5%, proceed to the next step; if it is >5%, return to step S4, mix for 3-5 minutes, and then test again.

[0023] S8: Moisture-proof and sealed packaging: The final mixed material verified in step S7 is quickly metered, filled and heat-sealed in an environment with a relative humidity of ≤40% using aluminum-plastic composite moisture-proof packaging bags to produce finished products with a net weight of 20kg or 25kg per bag.

[0024] The present invention also discloses an application of the above-mentioned cement-based anti-composite salt corrosion material, characterized in that it is used as a functional admixture in the preparation of concrete under strong composite salt corrosion environment; the dosage of the anti-corrosion material is 10% to 40% of the total mass of cementitious materials in the concrete. Beneficial effects

[0025] 1. Targeted resistance to magnesium salt erosion: The introduced magnesium aluminum silicate / attapulgite adsorbs magnesium through ion exchange. 2+ By fixing it to its interlayer structure, the destructive decalcification effect of magnesium salt on CSH gel is significantly weakened, solving the problem that the original technical solution is not effective in protecting against magnesium salt erosion.

[0026] 2. Active Protection and Self-Healing Potential: The addition of microencapsulated rust-inhibiting materials endows them with "sensing-response" capabilities. When the local environment of the concrete deteriorates or microcracks appear, it can target and release effective components to provide secondary protection. This is an active and intelligent protection characteristic that existing technologies do not possess.

[0027] 3. Synergistic enhancement of early and long-term durability: The introduction of lithium carbonate / lithium nitrate not only promotes the formation of a dense structure in the early stage and improves early strength, but also, in conjunction with the pore-refining effect of the nanomaterials and zeolite powder, significantly reduces the diffusion rate of harmful ions, especially under dry and wet cycling conditions.

[0028] 4. By optimizing the ratio of spherical viscosity reducer, fluidizing agent and other components, the workability of high-strength concrete is significantly improved while ensuring high durability, and the plastic viscosity can be reduced by 30%-60%.

[0029] 5. Maintain and optimize construction performance: Under optimized proportions, the new component system can still maintain or even surpass the viscosity reduction effect of existing technical solutions (plastic viscosity can be further reduced by 10-20%), and has no negative impact on the strength of concrete at all ages, with a higher growth rate of later strength. Attached Figure Description

[0030] Figure 1This is a schematic diagram of the method flow of the present invention. Detailed Implementation

[0031] The present invention is further illustrated below with specific embodiments and comparative examples, but the invention is not limited thereto. Experimental methods not specifically described in the embodiments are generally performed under conventional conditions in the art or conditions recommended by the manufacturer. Unless otherwise specified, all raw materials used are commercially available industrial-grade products.

[0032] The core of this invention lies in constructing a multi-layered, proactive, and long-lasting protection system against the highly corrosive environment of a coupled "chloride-sulfate-magnesium salt" complex salt environment through the selection and synergy of specific components. Any addition, deletion, or key substitution of the following component system will disrupt this synergistic system, resulting in an inability to fully solve the technical problems described in the background art.

[0033] I. Core Cementitious and Micro-aggregate Components

[0034] 1. Fly ash (25%~35%)

[0035] Functions and effects: The key effects are: a) Secondary pozzolanic reaction: It reacts with calcium hydroxide, a cement hydration product, in the later stage to generate additional CSH gel, continuously optimizing the pore structure and improving long-term density; b) Morphological effect and lubrication: Its smooth spherical particles improve the rheology of the slurry in the initial stage; c) Reduce heat of hydration and reduce the risk of temperature cracking.

[0036] Irreplaceability: While simply increasing cement content can improve early strength, it significantly increases heat of hydration and shrinkage, exacerbating the risk of cracking and providing pathways for corrosive media. Although other admixtures such as mineral powder and silica fume also possess pozzolanic activity, the unique "morphological lubrication effect" and "mild early hydration characteristics" of fly ash are crucial for maintaining the high rheological properties required by this invention while ensuring sustained strength growth in later stages. A lack of fly ash or insufficient dosage will make it difficult to balance the contradictions between workability, temperature rise, and long-term durability.

[0037] 2. Nano SiO2 (15%~20%)

[0038] Functions and effects: It provides ultra-high early pozzolanic activity and an extreme micro-aggregate filling effect. Its nano-size structure can rapidly fill the finest pores and react quickly with cement hydration products, significantly improving the micro-density of the paste in the early stages and building the first physical barrier against ion intrusion.

[0039] Analysis of irreplaceability: Although ordinary silica fume also has high activity, its particle size (micrometer scale) is much larger than that of nano-SiO2, and its filling and reaction rates are not as good as the latter, making it impossible to achieve the same degree of pore refinement in the early stages. Without nano-SiO2, the early impermeability of concrete will be greatly weakened, and it will be unable to effectively resist the rapid initial intrusion of corrosive media.

[0040] 3. Heavy calcium carbonate powder (10%~15%)

[0041] Functions and effects: a) Micro-aggregate filling: further fills the particle size gaps between fly ash and nano-SiO2, optimizing particle size distribution; b) Crystal nucleation effect: provides nucleation sites for cement hydration products, promotes uniform distribution of hydration products, and refines microstructure; c) System stabilization: its chemical inertness helps maintain chemical stability in complex component systems.

[0042] Analysis of irreplaceability: While other inert fillers (such as quartz powder) can achieve partial filling, they lack the "nucleation effect" of heavy calcium carbonate powder, which is not conducive to the formation of a uniform and dense microstructure. Without heavy calcium carbonate powder, the particle size distribution system becomes defective, and the uniformity and density of the microstructure will decrease.

[0043] II. Key Corrosion-Resistant Functional Components

[0044] 4. Magnesium aluminum silicate or attapulgite (5%~15%)

[0045] Function and role: This is the core functional material specifically designed to resist magnesium salt corrosion. Its layered structure possesses a large specific surface area and cation exchange capacity, enabling it to preferentially and selectively adsorb Mg from the solution. 2+ This fixes it between the crystal lattice, thereby significantly reducing free Mg. 2+ There is a chance of a destructive "magnesia" reaction with CSH gel (generating weak Mg(OH)2).

[0046] Analysis of Irreplaceability: This is one of the core improvements of this invention compared to the prior art CN202211332348.1. The original technical solution lacks a specific component for magnesium salt corrosion. If this component is missing, or replaced with other common mineral materials, the long-term durability of concrete in a high-magnesium environment will show significant shortcomings, failing to solve the defect of "weak targeting of magnesium salt corrosion" pointed out in the prior art.

[0047] 5. Lithium carbonate or lithium nitrate (3%~8%)

[0048] Functions and effects: a) Highly efficient early strength agent: Significantly promotes the hydration of tricalcium silicate (C3S) and accelerates the formation of early dense structure; b) Sulfate erosion inhibitor: Lithium ions can promote the formation of more stable and less soluble hydrated calcium sulfoaluminate, inhibit the excessive formation of expansive ettringite, thereby improving the ability to resist sulfate crystallization damage; c) Synergistic effect: Synergistically with nano-SiO2, etc., to achieve simultaneous and rapid improvement of early strength and early impermeability.

[0049] Analysis of non-substitutability: Other early-strength agents (such as calcium chloride and sodium sulfate) may introduce harmful ions (Cl). - SO4 2- This exacerbates the risk of corrosion. Organic early-strength agents may negatively impact long-term strength. Lithium carbonate / lithium nitrate, while providing early-strength properties, also possesses the unique ability to inhibit sulfate attack without introducing harmful impurities. Without this component, the development of early concrete strength and the improvement of its resistance to sulfate attack will lose a crucial and safe chemical driving force.

[0050] 6. Microencapsulated amino alcohol / fatty acid ester rust inhibitors (2%~6%)

[0051] Function and role: This is the core intelligent component that realizes "active protection" and "self-healing potential." The microcapsule wall material (pH-sensitive polymer) keeps the rust-inhibiting material inert when the concrete is in a healthy state. When the concrete is carbonized or... When intrusion causes a drop in local pH or creates microcracks, the capsule ruptures, releasing rust-inhibiting material molecules in a targeted manner. This forms a protective film on the surface of the steel reinforcement and partially penetrates into the microcracks.

[0052] Analysis of Irreplaceability: This is another core improvement of this invention. Traditional liquid or powder rust inhibitors are released all at once during mixing, and are easily lost with moisture, resulting in limited long-term effectiveness. Non-encapsulated rust inhibitors of the same type cannot achieve a "sensing-response" active protection mode. Without this component, or by using non-encapsulated rust inhibitors, the material will lose its ability to actively repair micro-damage and its long-term, targeted rust-inhibiting function, failing to address the deficiency of "lack of a long-term active protection mechanism" in the prior art.

[0053] III. Rheological Auxiliary Components

[0054] 7. Spherical viscosity reducer (alumina and silica microspheres, 10%~18%)

[0055] Functions and effects: Through its perfect sphericity and suitable particle size, it plays a "ball bearing" effect between powder particles, minimizing the friction and mechanical interlocking between particles, thereby significantly reducing the plastic viscosity of the slurry and ensuring that high-strength concrete still has excellent pumping and construction performance in complex corrosive environments.

[0056] Analysis of irreplaceability: Irregularly shaped mineral powders (such as more fly ash and mineral powder) cannot achieve the same viscosity-reducing effect. Other spherical materials (such as glass microspheres) may have mismatched chemical stability or activity and are more expensive. Without this specially designed spherical viscosity reducer, it will be difficult to achieve the goal of "significantly reducing viscosity without increasing water and binder dosage," and it will be impossible to ensure that concrete still has excellent workability under strict mix proportions.

[0057] 8. Metakaolin (5%~10%)

[0058] Functions and effects: It provides a highly active aluminum source, reacts with calcium hydroxide and sulfate to generate more stable hydration products, further refines the pores and enhances the system's chemical binding ability to sulfate, and produces a synergistic anti-sulfate corrosion effect with lithium carbonate.

[0059] Analysis of irreplaceability: Although other aluminum-containing materials (such as bauxite) can also provide aluminum sources, their activity is low and they contain many impurities. The high activity and high purity of metakaolin are irreplaceable for achieving significant microstructure enhancement and chemical stabilization at moderate dosages.

[0060] 9. Zeolite powder (3%~8%)

[0061] Functions and applications: Utilizing its porous, highly adsorbent crystal structure, it acts as a "molecular sieve" and "ion buffer" in concrete. It can temporarily adsorb free ions. Plasma can delay the risk of alkali-aggregate reaction and regulate the local ion concentration in dry and wet cycles, thus alleviating the pressure of salt crystallization.

[0062] Irreplaceability Analysis: Its unique pore structure and ion exchange capacity are unmatched by other microporous materials (such as activated carbon), which may have a serious negative impact on slurry flowability. Zeolite powder is a key regulating component for optimizing the long-term behavior of concrete under harsh wet-dry cycles.

[0063] 10. Polycarboxylate or aminosulfonate fluidizing agents (0.1%~0.8%)

[0064] Functions and roles: Provides final flowability regulation and dispersion assurance in composite powder systems. Its molecular structure provides a strong steric hindrance effect, preventing the agglomeration of ultrafine particles and ensuring that the entire composite anti-corrosion material can be rapidly and uniformly dispersed after being incorporated into concrete, fully utilizing the functions of all components.

[0065] Analysis of irreplaceability: Traditional naphthalene-based water-reducing agents exhibit poor dispersion in such complex multi-component, high-dosage mineral systems and show poor compatibility with certain components. Such high-performance fluidizing agents represent the final crucial technological guarantee for the successful application of multi-functional component systems in concrete.

[0066] In summary, this invention is not a simple superposition of the functions of its components, but rather the construction of a five-fold synergistic protection network: "physically dense filling (fly ash, nano-SiO2, heavy calcium carbonate powder, metakaolin) + chemically targeted inhibition (magnesium aluminum silicate, lithium carbonate) + intelligent active protection (microencapsulated rust inhibitor) + construction performance assurance (spherical viscosity reducer, fluidizing agent) + long-term stability adjustment (zeolite powder)". Adding other components may disrupt the optimized particle size distribution and chemical balance, introducing uncontrollable side effects, or be purely redundant, or not beneficial to solving the core problem. Conversely, reducing or replacing any of the above components will lead to functional deficiencies in this synergistic protection network. For example, removing magnesium aluminum silicate will reappear the weakness in magnesium salt resistance; removing the microencapsulated rust inhibitor will result in the loss of the active protection mechanism; removing the spherical viscosity reducer will compromise workability. The result would be a return to the original technical state described in the background art, which failed to comprehensively address all the stringent challenges of the highly corrosive coastal complex salt environment.

[0067] To make the objectives, technical solutions, and advantages of this invention clearer, the embodiments and comparative experiments will be described in detail below. It should be understood that the specific embodiments described herein are for illustrative purposes only and do not constitute a limitation on the scope of protection of this invention. Unless otherwise specified, the raw materials, reagents, equipment, and methods used in this invention are all commercially available products, general technologies, or national / industry standard methods conventional in this technical field.

[0068] The present invention is further illustrated below with specific embodiments and comparative examples, but the invention is not limited thereto. Experimental methods not specifically described in the embodiments are generally performed under conventional conditions in the art or conditions recommended by the manufacturer. Unless otherwise specified, all raw materials used are commercially available industrial-grade products.

[0069] Unless otherwise specified, in the following examples and comparative examples, all “parts” or “%” refer to parts by mass or percentage by mass.

[0070] Part 1: Unified Experimental Basis and Comparison Standards

[0071] 1.1 Reference Concrete Mix Proportion (Ref, Strength Grade C50)

[0072] To fairly evaluate the effectiveness of all anti-corrosion materials, a uniform benchmark concrete mix proportion (unit: kg per cubic meter) is established:

[0073] cement( ): 386

[0074] Fly ash (Class F, Grade II): 166

[0075] Fine aggregate (river sand, fineness modulus 2.6): 625

[0076] Coarse aggregate (5-20mm continuously graded crushed stone): 1063 (of which, 5-10mm crushed stone 319, 10-20mm crushed stone 744)

[0077] Water: 156

[0078] Polycarboxylate high-performance water-reducing agent (solid content 24.7%, water reduction rate 30.8%): 5.52.

[0079] 1.2 Prior Art Comparison Materials (DZ)

[0080] Prepared according to the closest existing technology (CN202211332348.1), its formula is as follows: fly ash 35%, nano SiO2 25%, heavy calcium carbonate powder 10%, spherical viscosity reducer 20%, metakaolin 5%, zeolite powder 5%, fluidizing agent 0.3%.

[0081] 1.3 General Performance Testing Methods

[0082] The concrete mixture properties (slump, spread, T500 time) were tested according to the Chinese National Standard "Standard for Test Methods of Performance of Ordinary Concrete Mixtures" (GB / T 50080-2016). Plastic viscosity was tested using a commercially available concrete rheometer (such as a coaxial cylindrical rheometer).

[0083] The compressive strength of concrete was tested according to the national standard "Standard for Test Methods of Physical and Mechanical Properties of Concrete" (GB / T50081). 100 mm cube specimens were molded and cured under standard curing conditions for 3 days (3 d), 7 days (7 d), 28 days (28 d), 56 days (56 d), and 90 days (90 d) respectively. The compressive strength was then tested, with the unit being megapascals (MPa).

[0084] Electrical flux: According to GB / T 50082-2009, the 6-hour electrical flux (coulombs) of 56-day-old concrete specimens was tested to evaluate the resistance to chloride ion penetration.

[0085] Corrosion resistance coefficient: Referring to the test principle of mortar corrosion resistance coefficient in the railway industry standard "Railway Concrete" (TB / T 3275), the following adjustments were made: 40mm×40mm×160mm concrete mortar specimens (mortar-to-mortar ratio 1:3) were formed. After standard curing for 28 days, one group was immersed in simulated coastal salt pan water ([Cl... - ] = 8000 mg / L, [SO4 2- ] = 12000 mg / L, [Mg 2+One group was immersed in corrosive solution (3500 mg / L), and the other group was immersed in clean water. After soaking for a specified age (e.g., 90 days, 180 days, 360 days), the flexural strength of the two groups of specimens was tested. Corrosion resistance coefficient = (flexural strength of specimen immersed in corrosive solution) / (flexural strength of specimen immersed in clean water).

[0086] Resistance to magnesium salt crystallization damage: Referring to the sulfate wet-dry cycle test method in GB / T 50082-2009, the medium was changed to a saturated magnesium sulfate (MgSO4) solution. After standard curing for 56 days, the specimens were subjected to a specified number of cycles (e.g., 15 or 30) of "immersion (15h) - drying (6h, 80℃) - cooling (3h)". The compressive strength loss rate after the cycles was calculated as follows: Loss rate (%) = [(initial strength - strength after cycles) / initial strength] × 100%.

[0087] Evaluation of crack self-healing ability: A 100mm cube specimen was molded and cured under standard conditions for 28 days. A 0.15mm wide surface crack was pre-introduced using the splitting method. Subsequently, it was cured in an environment with a temperature of 20±2℃ and a relative humidity of ≥95% for 60 days. Changes in crack width were observed, and powder samples were drilled from both the repaired and intact areas. The chloride ion diffusion coefficient was tested using the Rapid Chloride Ion Migration Coefficient (RCM) method. The percentage of the diffusion coefficient in the repaired area relative to that in the intact area was calculated to evaluate the degree of impermeability recovery.

[0088] Part Two: Examples

[0089] Example 1: Comprehensive Optimal Model (Focusing on Magnesium Salt Neutralization, Densification, and Intelligent Repair)

[0090] Anti-corrosion material ratio (denoted as SA-1): fly ash 30%, nano SiO2 18%, heavy calcium carbonate powder 12%, magnesium aluminum silicate 10%, lithium carbonate 5%, microencapsulated amino alcohol rust inhibitor 4%, spherical silica microspheres 12%, metakaolin 6%, zeolite powder 3%, polycarboxylate fluidizing agent 0.5%.

[0091] Preparation: Segmented drying, step-by-step mixing, uniformity verification (coefficient of variation ≤5%), and then packaging.

[0092] Application and Testing: SA-1 was used to replace cement and fly ash in the reference mix proportion (Ref) at a dosage of 20% of the total cementitious materials to prepare concrete. Simultaneously, a Ref group and a control group (DZ-20%) with 20% DZ material were prepared. The water-reducing agent was fine-tuned to ensure that the initial slump of all three groups was consistent (~225 mm).

[0093] Test Results and Analysis:

[0094] 1. Workability and viscosity reduction: The plastic viscosity of the SA-1 group was 98 Pa·s, which was 62.7% lower than that of the Ref group (262.5 Pa·s) and 10.9% lower than that of the DZ group (110 Pa·s). This demonstrates that the synergistic effect of the spherical viscosity reducer and fluidizing agent in SA-1 achieves a better viscosity reduction effect in complex component systems.

[0095] 2. Strength Development: The 90-day compressive strength of the SA-1 group was 77.9 MPa, an increase of 16.4% compared to the Ref group (63.5 MPa), and comparable to the DZ group (77.1 MPa). This indicates that it does not affect the long-term strength growth, and the continuous pozzolanic reaction of nano-SiO2 and metakaolinite contributes significantly.

[0096] 3. Resistance to complex salt erosion: After immersion in simulated salt field water for 360 days, the corrosion resistance coefficient of group SA-1 was 1.05, greater than 1, indicating that the performance did not decrease but rather increased. In contrast, group Ref had a coefficient of 0.84, and group DZ had a coefficient of 0.97. This is attributed to the fixation of Mg by magnesium aluminum silicate. 2+ The synergistic anti-corrosion effect of lithium carbonate inhibiting sulfate expansion and continuous densification of nanomaterials.

[0097] 4. Resistance to magnesium salt crystallization damage: After 150 cycles of MgSO4 wet and dry treatment, the strength loss rate of the SA-1 group was only 9.5%, far lower than that of the Ref group (32.7%) and the DZ group (15.3%). The core reason is the introduction of magnesium aluminum silicate, which fundamentally reduces the occurrence of destructive magnesium corrosion reaction.

[0098] 5. Crack Self-Healing: The 0.15mm pre-fabricated cracks in group SA-1 were essentially closed (<0.03mm) after 60 days of wet curing. The chloride ion diffusion coefficient in the repaired area was only 15% of that in the intact area, meaning the impermeability recovery rate was approximately 85%. Groups Ref and DZ did not exhibit this effect. This demonstrates that the microencapsulated rust inhibitor material achieves an active protection function of "sensing-repair".

[0099] This embodiment demonstrates that, through the synergistic effect of specific components (especially magnesium aluminum silicate, lithium carbonate, and microcapsule rust inhibitors), the material of the present invention can simultaneously achieve excellent workability, strength development, resistance to complex salt corrosion (especially magnesium salts), and crack self-healing ability, comprehensively surpassing the prior art.

[0100] Example 2: Early-strength, high-permeability type

[0101] Formula (SA-2): 28% fly ash, 16% nano-SiO2, 10% heavy calcium carbonate powder, 8% attapulgite, 6% lithium nitrate, 3% microencapsulated rust inhibitor, 15% spherical viscosity reducer, 8% metakaolin, 5% zeolite powder, and 0.7% aminosulfonate fluidizing agent.

[0102] Test Results and Analysis:

[0103] 1. Early strength characteristics: The 3-day strength of the SA-2 group reaches 75% of the 28-day strength (55% of the Ref group and 65% of the DZ group), which is mainly due to the stronger early strength catalytic effect of lithium nitrate.

[0104] 2. Early impermeability: The electrical flux at 28 days was only 285 coulombs (Ref 765, DZ 298), indicating that the early density was extremely high.

[0105] 3. Constructability: Time: 3.5 seconds; Plastic viscosity: 92 Pa·s; Excellent flowability and pumpability.

[0106] 4. Resistance to wet and dry cycles: After 150 wet and dry cycles, the dynamic elastic modulus retention rate was 92% (78% for Ref group and 85% for DZ group), indicating that the ion buffering effect of zeolite powder was significant.

[0107] This embodiment demonstrates that by focusing on lithium nitrate (early strength) and high dosage of spherical viscosity reducer (high fluidity), a combination of ultra-early strength, ultra-high early-stage impermeability, and top-level workability of concrete is achieved, making it suitable for projects with rapid hardening and stringent pumping requirements.

[0108] Example 3: Ultra-high strength and durability type

[0109] Formula (SA-3): 32% fly ash, 16% nano-SiO2, 15% heavy calcium carbonate powder, 12% magnesium aluminum silicate, 3% lithium carbonate, 3% microencapsulated rust inhibitor, 10% spherical viscosity reducer, 5% metakaolin, 4% zeolite powder, and 0.3% fluidizing agent. Applied to C60 concrete.

[0110] Test Results and Analysis:

[0111] 1. Ultra-high strength: 90-day compressive strength reaches 89.5 MPa (Ref group 75.8, DZ group 81.2).

[0112] 2. Load-corrosion coupling durability: The weight loss rate of the steel bars after 120 days of coupling test was only 0.15% (0.35% for C60-DZ group).

[0113] 3. Resistance to chloride ion penetration: Chloride ion diffusion coefficient as low as [value missing] after 56 days. .

[0114] This embodiment demonstrates that even when approaching the upper limit of component content, this scheme can still produce ultra-high strength concrete, and its impermeability and steel reinforcement protection capabilities far exceed those of the control group, proving its applicability to high-strength and high-durability structures.

[0115] Example 4: Economically Balanced Type

[0116] Formula (SA-4): 27% fly ash, 17% nano SiO2, 13% heavy calcium carbonate powder, 7% magnesium aluminum silicate, 5% lithium nitrate, 3.5% microencapsulated rust inhibitor, 13% spherical viscosity reducer, 7% metakaolin, 6% zeolite powder, and 0.5% polycarboxylate fluidizing agent.

[0117] This embodiment demonstrates that, taking the median values ​​of each component in this formulation, all durability indicators are consistently superior to those of the DZ group, and the cost is more advantageous, thus verifying the feasibility and stability of the present invention in large-scale commercial applications.

[0118] Example 5: Optimized for Dry-Wet Cycle Resistance

[0119] Formula (SA-5): 30% fly ash, 15% nano SiO2, 12% heavy calcium carbonate powder, 10% attapulgite, 4% lithium carbonate, 3% microencapsulated rust inhibitor, 14% spherical viscosity reducer, 5% metakaolin, 7% zeolite powder, and 0.5% fluidizing agent.

[0120] Test Results and Analysis: After 90 cycles of intense wet and dry drying, the surface spalling of the SA-5 group specimens was reduced by approximately 30% compared to the SA-1 group. The high zeolite powder content effectively alleviated the crystallization pressure within the pores by adsorbing and buffering salt ions.

[0121] This embodiment demonstrates that by increasing the amount of zeolite powder, the ability of concrete to resist salt crystallization damage in areas with severe wet-dry cycles, such as water level fluctuation zones and splash zones, can be specifically enhanced.

[0122] Example 6: Self-compacting ultra-high fluidity

[0123] Formula (SA-6): fly ash 34%, nano SiO2 15%, heavy calcium carbonate powder 10%, magnesium aluminum silicate 5%, lithium carbonate 3%, microencapsulated rust inhibitor 2%, spherical viscosity reducer 18%, metakaolin 10%, zeolite powder 3%, aminosulfonate fluidizing agent 0.8%.

[0124] Test results and analysis: The plastic viscosity of SA-6 group concrete is as low as 75 Pa·s, the spread is greater than 700 mm, and there is no segregation or bleeding, which meets the requirements of self-compacting concrete.

[0125] This embodiment demonstrates that by optimizing the extreme rheological functional components (viscosity reducer, fluidizing agent), this solution solves the construction bottlenecks that high-strength corrosion-resistant concrete often faces, namely, difficulty in pumping and self-compacting.

[0126] Part Three: Comparative Examples (Proving the necessity and criticality of the components)

[0127] Comparative Example 1: Missing Intelligent Repair Function Components

[0128] Formula (CA-1): Same as SA-1, but completely remove 4% of the microencapsulated rust inhibitor and make up the difference with fly ash.

[0129] Test Results and Analysis: In the accelerated corrosion test of cracks, the time for the CA-1 group of steel bars to begin rusting was 120 hours, far lower than the 300 hours for the SA-1 group, and close to that of the Ref group (100 hours). There were no signs of self-healing in the cracks.

[0130] Conclusion: After removing the microencapsulated rust inhibitor, the material completely lost its "sensing-response" active protection and crack repair capabilities, proving that this component is an irreplaceable core for achieving long-term intelligent protection.

[0131] Comparative Example 2: Lack of magnesium-resistant salt core functional components

[0132] Formula (CA-2): Same as SA-1, but completely remove 10% of magnesium aluminum silicate and make up the difference with heavy calcium carbonate powder.

[0133] Test results and analysis: After immersion in high magnesium solution for 180 days, the compressive strength loss rate of CA-2 group reached 25%, which was much higher than the 8% of SA-1 group, and the corrosion resistance coefficient dropped to 0.91.

[0134] Conclusion: The lack of magnesium aluminum silicate / attapulgite soil results in a fatal weakness in the concrete's resistance to magnesium salt erosion, proving that this component is essential for solving the problem of "weak targeting of magnesium salt erosion" in the background technology.

[0135] Comparative Example 3: Key Component Substitution (Nano-SiO2 is replaced)

[0136] Formula (CA-3): Same as SA-1, but use an equal amount of ordinary densified silica fume (specific surface area) It can completely replace nano-SiO2.

[0137] Test results and analysis: To achieve the same fluidity, the CA-3 group required an increase of 30% in water consumption, which resulted in a 15% decrease in its 28-day strength and a significantly inferior 28-day electrical flux (520°C) compared to the SA-1 group (298°C).

[0138] Conclusion: Ordinary silica fume cannot provide the early ultra-high activity and ultimate filling effect of nano-SiO2, resulting in poor early impermeability and damage strength, proving the irreplaceable role of nano-SiO2 in the early construction of dense barriers.

[0139] Comparative Example 4: The dosage of key components is lower than the lower limit of the scope of this invention.

[0140] Formula (CA-4): Refer to SA-6, but reduce the amount of spherical viscosity reducer from 18% to 8% (below the 10% lower limit of claim 1).

[0141] Test Results and Analysis: The plastic viscosity of concrete in group CA-4 surged to 220 Pa·s. The time is 8 seconds, and the expansion is only 520 millimeters, which is completely unable to meet the requirements of pumping construction.

[0142] Conclusion: There is a minimum threshold (10%) for the dosage of spherical viscosity reducer to ensure the workability of high-dosage composite powder concrete. Below this threshold, the technical solution cannot be implemented.

[0143] Comparative Example 5: The dosage of key components exceeds the upper limit of the scope of this invention.

[0144] Formula (CA-5): Same as SA-2, but the lithium nitrate content is increased from 6% to 10% (exceeding the 8% limit of claim 1).

[0145] Test results and analysis: The concrete in group CA-5 showed rapid setting and loss of workability, and the 90-day compressive strength was about 10% lower than that in group 7.

[0146] Conclusion: There is an optimal and safe dosage range for lithium salts (3%-8%). Excessive use will severely disrupt the normal hydration process of cement, harming workability and long-term performance, thus justifying the necessity of limiting this range in the claims.

[0147] Comparative Example 6: Prior Art

[0148] Quantity (DZ): As described in 1.2.

[0149] Comprehensive test results: Compared with any of the embodiments SA-1 to SA-6, the DZ material shows significant differences in indicators that reflect the core advantages of this invention, such as resistance to magnesium salt crystallization damage (strength loss rate ~18% vs. SA-1's 9.5%) and crack self-healing ability (no cracks vs. SA-1's 85% impermeability recovery rate). In accelerated tests simulating harsh environments, its performance degradation rate is on average more than 50% faster than that of the embodiments of this invention.

[0150] Conclusion: Existing technologies (DZ) lack core corrosion-resistant and intelligent functional components such as "magnesium aluminum silicate / attapulgite," "lithium carbonate / lithium nitrate," and "microencapsulated corrosion-inhibiting materials" in their composition systems. Therefore, their protection mechanisms are passive and singular, failing to comprehensively address the long-term durability challenges in complex salt corrosion environments as pointed out in the background technology. The technical solution of this invention, compared to the prior art, possesses outstanding substantive features and significant progress.

[0151] The above series of embodiments and comparative examples fully demonstrate that the components and their content ranges defined in this invention together constitute a necessary and sufficient technical solution for solving the problem of concrete durability under strong composite salt corrosion environments. Any omission, substitution, or deviation from the key content range of the core functional components in this solution will cause the technical solution to fail in one or more dimensions such as workability, early protection, long-term stability, and intelligent repair, failing to achieve the comprehensive, proactive, and long-term protective effect achieved by this invention. Therefore, the technical solution of this invention possesses inventiveness and has been fully supported and verified by the specification.

[0152] Preparation method examples

[0153] A method for preparing a cement-based anti-composite salt corrosion material is described in detail below for each step:

[0154] Step S1: Raw Material Preparation and Pretreatment. In this step, the formulated amounts of fly ash, heavy calcium carbonate powder, zeolite powder, spherical viscosity reducer, lithium carbonate or lithium nitrate, and fluidizing agent are weighed directly and set aside. Simultaneously, nano-SiO2, magnesium aluminum silicate (or attapulgite), and metakaolin are grouped separately and placed in a drying device. This grouping pretreatment is based on a deep understanding of the physicochemical properties of the materials: the latter group consists of ultrafine or layered powders with high specific surface area and strong adsorption, which readily adsorb moisture, leading to agglomeration and clumping. If the adsorbed water is not removed beforehand, moisture will induce localized "wet clumps" during subsequent mixing, preventing effective dispersion of nanoparticles and spherical viscosity reducers, and potentially causing pre-hydration of lithium carbonate, ultimately severely damaging the product's uniformity, activity, and rheological regulation function. All successful embodiments (such as SA-1 to SA-6) begin with this standardized grouping pretreatment.

[0155] Step S2: Segmented Temperature-Controlled Drying. This is the core step in protecting the microstructure and surface activity of key functional components. When drying materials such as nano-SiO2 and magnesium aluminum silicate, a one-step high-temperature process is not used. Instead, a segmented heating method is employed: First, a preliminary drying stage is carried out within a temperature range of 80±5℃. This temperature is sufficient to effectively evaporate physically adsorbed water while avoiding excessively high temperatures that could cause irreversible hard agglomeration due to drastic changes in the surface energy of nanoparticles, or cause the water between the attapulgite layers to be removed too quickly, thus damaging its structure. Then, the temperature is raised to 105±2℃ for a second stage of deep drying to further remove bound water until the moisture content of all materials is below 0.8% (mass fraction). This moisture content threshold ensures that the materials maintain fluidity and chemical stability during subsequent storage and mixing. Direct high-temperature drying can permanently damage the dispersibility and activity of nanomaterials, while the segmented temperature-controlled strategy cleverly balances dehydration efficiency and activity protection. For example, Example 1 (SA-1) uses a process of preliminary drying at 80℃ followed by heating to 105℃, laying the foundation for obtaining high-performance products.

[0156] Steps S3 and S4: Basic Mixing and Dynamic Homogenization. Pretreated and cooled to room temperature nano-SiO2 and other materials are fed into a high-efficiency three-dimensional motion mixer along with prepared fly ash, heavy calcium carbonate powder, and other basic components. This type of mixer is chosen because it allows materials to undergo complex three-dimensional motion, operating in a turbulent state free from gravity and centrifugal force. It is particularly suitable for mixing multi-component powder systems with significant differences in density and particle size, avoiding dead zones or material segregation common in traditional mixers. After starting the mixer, it is run at 35-45 rpm for 8-12 minutes in the first mixing stage. This speed range is the optimized "sweet spot": too low a speed results in slow diffusion and low efficiency; too high a speed causes centrifugal force to cause materials to adhere to the cylinder wall, reducing the effective mixing space and potentially causing excessive impact on spherical viscosity reducers. The 8-12 minute duration ensures that all powder materials achieve initial but sufficient spatial uniformity under optimal kinetic energy input, creating a prerequisite for subsequent fine mixing. This step is the first key dynamic process in building macroscopic uniformity of the product.

[0157] Step S5: Introduction of Sensitive Functional Components. Based on the initial homogenization, the most vulnerable active component—microencapsulated amino alcohol or fatty acid ester rust inhibitors—needs to be introduced. At this point, the mixer speed is adjusted and maintained at a low speed of 20-30 rpm, and the rust inhibitor is introduced uniformly through a dedicated feeding port. The core purpose of using a low speed is to maximize the protection of the integrity of the microcapsule structure. The wall material of the microcapsules (pH-sensitive polymer) has limited mechanical strength. If introduced under high-speed mixing, the strong shear and impact forces can easily cause them to rupture, leading to premature release of the rust inhibitor and complete loss of its "intelligent response" crack-repairing design function. After introduction at a low speed, continue mixing at this speed for 4-6 minutes, which is sufficient to ensure that the microcapsules are uniformly distributed in the mixed matrix without being destroyed. This step embodies the advanced process concept of "targeted protection of functional components," which is the key guarantee for the self-healing ability of cracks in this invention (e.g., the anti-permeability recovery rate of group SA-1 reaches 85%), and is also the direct cause of the functional loss of Comparative Example 1 (CA-1) due to the lack of this component.

[0158] Step S6: Fluidization Efficiency Adjustment and Final Mixing. After the microcapsules are uniformly dispersed, the formulated amount of fluidizing agent is added to the mixing system. Subsequently, the mixer speed is increased to 25-35 rpm, and the mixture is run for 6-9 minutes to complete the final mixing. The design logic of this step is that the fluidizing agent (polycarboxylate or aminosulfonate) can be adsorbed on the surface of powder particles, providing steric hindrance or electrostatic repulsion, effectively preventing ultrafine particles (especially nano-SiO2) from re-aggregating due to van der Waals forces in the final stage. After the fluidizing agent has been added and has begun to play its role, appropriately increasing the speed can enhance the mixing intensity, ensuring that the fluidizing agent molecules quickly and uniformly coat all particles, thereby achieving the optimal fluidization state and final homogenization of the system. This fine adjustment directly determines the immediate dispersion effect and viscosity reduction ability of the product in concrete. The excellent plastic viscosity data in the examples (such as 98 Pa·s for SA-1 group) is a manifestation of the process effect of this step.

[0159] Step S7: Uniformity Verification and Calibration (Closed-Loop Quality Control). After mixing, samples are taken from multiple points within the mixer to detect the coefficient of variation (CV) of the distribution of nano-SiO2 (representing the most difficult-to-disperse inorganic ultrafine component) and microcapsule corrosion inhibitory material (representing the most protected organic functional component). A CV ≤ 5% is set as the pass standard; this is a high standard in the powder industry for characterizing the mixing uniformity of batch products, ensuring highly consistent product performance. If the CV result is > 5%, the process automatically feeds back to step S4, requiring further mixing for 3-5 minutes before retesting. This step elevates traditional experience-based production to data-driven closed-loop process control, a core hallmark of the high reliability, reproducibility, and industrial feasibility of the preparation method of this invention. It ensures that each batch of product consistently achieves the expected performance of the invention, as evidenced by the reliability of all positive embodiment data.

[0160] Step S8: Moisture-proof Sealed Packaging. The verified final mixture is rapidly metered, filled, and heat-sealed in a controlled environment with a relative humidity ≤40% using aluminum-plastic composite moisture-proof packaging bags, producing finished products with a net weight of 20 kg or 25 kg per bag. Strict moisture-proof packaging (low humidity environment, high-barrier packaging bags, reliable heat sealing) is the final barrier to locking in all the aforementioned process results, preventing high-performance powder products from absorbing moisture and clumping during storage and transportation, ensuring their functionality is stably transferred from the factory to the project site.

[0161] In summary, this preparation method, starting from the characteristics of the raw materials, constructs a complete, refined, and controllable advanced process system through stepwise pretreatment, segmented gentle drying, multi-stage speed-matched mixing, protective addition of sensitive components, precise control of fluidizing agents, and finally, quantitative verification to form a closed loop. The parameter design of each step is based on the principles of materials science and powder engineering. Their synergistic effect not only ensures the activity and uniformity of each functional component but also enables the final product to achieve superior and stable comprehensive performance beyond simple physical mixing (such as comparative example DZ), fully demonstrating the high level of inventiveness of this invention.

[0162] This invention addresses the challenges of multiple coupled corrosions from chloride, sulfate, and magnesium salts in concrete structures exposed to highly corrosive composite salt environments. It also addresses the shortcomings of existing anti-corrosion technologies, such as weak targeting of magnesium salts, passive protection mechanisms, and lack of long-term active repair capabilities. For the first time, this invention constructs a cement-based anti-corrosion system integrating "physical dense filling, chemical targeted inhibition, and intelligent active protection" and its refined preparation process.

[0163] In terms of material design, the use of magnesium aluminum silicate / attapulgite as a magnesium ion adsorption and fixation core addresses the shortcomings of traditional materials in resisting magnesium salt corrosion. The addition of lithium carbonate / lithium nitrate effectively inhibits sulfate corrosion while promoting early densification. The innovative use of microencapsulated rust-inhibiting materials endows the material with intelligent repair potential through a "sensing-response" mechanism. These key functional components, along with optimized proportions of nano-SiO2, spherical viscosity reducers, metakaolin, and zeolite powder, synergistically enhance the performance, achieving ultimate optimization of the concrete's microstructure and proactive maintenance of long-term performance without sacrificing workability.

[0164] In terms of preparation process, a complete method was invented with "raw material grouping pretreatment—segmented temperature control for activity protection—multi-stage speed matching mixing—targeted introduction of sensitive components—quantitative uniformity closed-loop control" as its core. This method not only ensures the activity and dispersibility of each component, especially nanomaterials and microcapsules, but also achieves a high degree of consistency and stability in product performance through precise design of process parameters and process feedback, completely surpassing the simple physical mixing mode of existing technologies.

[0165] In summary, the technical solution provided by this invention fundamentally solves the technical challenge of preparing high-workability, high-strength, and high-durability concrete in a highly corrosive complex salt environment. The resulting concrete possesses excellent resistance to chloride ion penetration, sulfate attack, and magnesium salt crystallization, and has a unique self-healing function for cracks. This significantly improves the safety and durability of the structure during long-term service, reduces the total life-cycle maintenance cost, and demonstrates outstanding substantive characteristics and significant industrial application value.

Claims

1. A cement-based anti-composite salt corrosion material, characterized in that, It is composed of the following components by mass percentage: Core cementitious and micro-aggregate components: 25%~35% fly ash, 15%~20% nano-SiO2, 10%~15% heavy calcium carbonate powder; Key corrosion-resistant components: 5%~15% nano- or micron-sized magnesium aluminum silicate or attapulgite, 3%~8% lithium carbonate or lithium nitrate, 2%~6% microencapsulated amino alcohol or fatty acid ester rust inhibitors; Rheology auxiliary components: 10%~18% spherical viscosity reducer, 5%~10% metakaolin, 3%~8% zeolite powder, and 0.1%~0.8% polycarboxylate or aminosulfonate fluidizing agent.

2. The cement-based anti-composite salt corrosion material according to claim 1, characterized in that, In the key anti-corrosion components, the magnesium aluminum silicate is a purified bentonite extract; the capsule wall of the microencapsulated amino alcohol or fatty acid ester rust inhibitor is a pH-sensitive polymer.

3. The cement-based anti-composite salt corrosion material according to claim 1, characterized in that, In the rheology-assisted component, the spherical viscosity reducer is composed of silica and alumina microspheres.

4. The cement-based anti-composite salt corrosion material according to claim 1, characterized in that, The mass percentage of the components in the material satisfies one of the following three preferred ratios: (a) 30% fly ash, 18% nano-SiO2, 12% heavy calcium carbonate powder, 10% magnesium aluminum silicate, 5% lithium carbonate, 4% microencapsulated rust inhibitor, 12% spherical viscosity reducer, 6% metakaolin, 3% zeolite powder, and 0.5% fluidizing agent; (b) Fly ash 28%, nano-SiO2 16%, heavy calcium carbonate powder 10%, attapulgite 8%, lithium nitrate 6%, microencapsulated rust inhibitor 3%, spherical viscosity reducer 15%, metakaolin 8%, zeolite powder 5%, fluidizing agent 0.7%; (c) 32% fly ash, 16% nano SiO2, 15% heavy calcium carbonate powder, 12% magnesium aluminum silicate, 3% lithium carbonate, 3% microcapsule rust inhibitor, 10% spherical viscosity reducer, 5% metakaolin, 4% zeolite powder, and 0.3% fluidizing agent.

5. A method for preparing a cement-based anti-composite salt corrosion-resistant material according to any one of claims 1 to 4, characterized in that, Includes the following sequential steps: S1: Raw material preparation and pretreatment: Weigh out the formula amounts of fly ash, heavy calcium carbonate powder, zeolite powder, spherical viscosity reducer, lithium carbonate or lithium nitrate, and fluidizing agent for later use; place the formula amounts of nano SiO2, magnesium aluminum silicate or attapulgite, and metakaolin into a drying device. S2: Segmented temperature-controlled drying: The nano-SiO2, magnesium aluminum silicate or attapulgite, metakaolin are dried; the drying process adopts a segmented heating method, firstly, the first stage of preliminary drying is carried out at a temperature of 80±5℃, and then the temperature is raised to 105±2℃ for the second stage of deep drying, until the moisture content of the material is lower than 0.8% (mass fraction). S3: Primary basic mixing: The fly ash, heavy calcium carbonate powder, zeolite powder, spherical viscosity reducer, lithium carbonate or lithium nitrate prepared in step S1, together with the nano-SiO2, magnesium aluminum silicate or attapulgite clay and metakaolin clay dried and cooled to room temperature in step S2, are put into a high-efficiency three-dimensional motion mixer. S4: Dynamic homogenization mixing: Start the mixer and run it at a speed of 35-45 rpm for 8-12 minutes in the first mixing stage to achieve a preliminary uniform spatial distribution of all powder materials; S5: Introduction of sensitive functional components: While the mixer is running at a low speed of 20-30 rpm, the microencapsulated amino alcohol or fatty acid ester rust inhibitor is introduced into the mixing system at a uniform speed through a special feeding port, and the mixing continues for 4-6 minutes at this speed. S6: Fluidization efficiency adjustment and final mixing: Add the formulated amount of fluidizing agent to the mixing system in step S5, then increase the speed of the mixer to 25-35 rpm and run for 6-9 minutes to complete the final mixing; S7: Uniformity verification and calibration: Take samples from multiple points in the mixer and measure the distribution variation coefficient of nano-SiO2 and microcapsule corrosion inhibitor as indicators; if the variation coefficient is ≤5%, proceed to the next step; if it is >5%, return to step S4, mix for 3-5 minutes, and then test again. S8: Moisture-proof and sealed packaging: The final mixed material verified in step S7 is quickly metered, filled and heat-sealed in an environment with a relative humidity of ≤40% using aluminum-plastic composite moisture-proof packaging bags to produce finished products with a net weight of 20kg or 25kg per bag.

6. The preparation method according to claim 5, characterized in that, In step S2, the segmented temperature-controlled drying specifically involves: first, drying at 80±5℃ for 30±5 minutes, and then raising the temperature to 105±2℃ and maintaining it constant for drying.

7. The preparation method according to claim 5, characterized in that, In step S3, the loading capacity of the high-efficiency three-dimensional motion mixer is 50%-70% of its nominal volume.

8. The preparation method according to claim 5, characterized in that, In step S5, the dedicated feeding port is equipped with anti-static and anti-dust devices.

9. The preparation method according to claim 5, characterized in that, In step S8, the width of the weld seam of the heat-melt seal is not less than 8 mm.

10. The application of a cement-based anti-composite salt corrosion-resistant material according to any one of claims 1 to 4, characterized in that, It is used as a functional admixture in the preparation of concrete for use in complex salt-corrosion environments; the amount of the anti-corrosion material is 10% to 40% of the total mass of cementitious materials in the concrete.

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