High-corrosion-resistance marine Portland cement and preparation method thereof

Abstract

The invention discloses high-corrosion-resistance marine Portland cement and a preparation method thereof, and relates to the technical field of marine engineering building materials. The self-repairing cement comprises the following components in parts by weight: 70-80 parts of Portland cement clinker, 10-15 parts of superfine slag powder, 5-10 parts of silica fume, 2-4 parts of a double-response self-repairing capsule, 1.5-3 parts of a difunctional nano composite material, 0.5-1.5 parts of a bio-based loaded inorganic matter synergistic mineralizer, 3-5 parts of gypsum and 0.02-0.05 part of triethanolamine. The preparation method comprises the following steps: drying the raw materials, co-grinding, adding the three functional components, and uniformly mixing. Through the synergistic effect of the three functional components, the cement has excellent chloride ion erosion resistance and sulfate corrosion resistance, intelligent self-repairing of cracks can be achieved, and the durability of marine concrete in tidal range, total immersion and sea mud areas is remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of marine engineering construction materials technology, specifically to a high corrosion-resistant marine silicate cement and its preparation method. Background Technology

[0002] Marine engineering construction is an important component of the national development strategy. However, the harsh marine environment poses unprecedented challenges to the durability of reinforced concrete structures. Chloride ion corrosion leading to steel corrosion, sulfate corrosion causing volume expansion and damage, and accelerated material degradation due to physical processes such as wet-dry cycles and freeze-thaw cycles are the core factors causing premature failure and high maintenance costs of marine structures. The corrosion process is particularly severe in areas with frequent wet-dry cycles, such as tidal zones and splash zones.

[0003] To improve the durability of marine concrete, traditional technical approaches mainly focus on the following aspects: First, reducing porosity and refining pore size by incorporating large amounts of mineral admixtures (such as slag, fly ash, and silica fume) to physically block the migration of harmful ions. However, this cannot completely prevent long-term ion penetration under concentration gradients and lacks self-healing properties for existing microcracks. Second, introducing external anti-corrosion measures, such as applying coatings or migration-type rust inhibitors to the concrete surface. These methods have inherent drawbacks, including limited durability, short maintenance cycles, and inability to repair internal damage. Third, developing self-healing technologies. Current research mainly focuses on single mechanisms, such as incorporating microcapsules containing healing agents or utilizing microbial-induced mineralization. However, microcapsule technology often only responds to mechanical damage (crack formation) and lacks active defense against the chemical processes of corrosive ion intrusion. Microbial mineralization technology faces problems such as inactivation of microorganisms due to the high-alkalinity environment in the early stages of cement hydration, termination of repair capabilities after nutrient depletion, and insufficient bond strength between mineralized products and the matrix.

[0004] More importantly, existing technologies often employ a strategy of stacking technologies, lacking effective synergy and coordination among various durability-enhancing methods. For example, physical barrier materials cannot intelligently repair damage they themselves generate; chemical adsorption materials lose their protective ability after saturation and may even alter local pH levels, causing side effects; while bioremediation processes often occur independently of the material's chemical environment. This fragmented protection system struggles to cope with the complex erosion processes in the marine environment, which involve multiple coupled factors and continuous evolution, and cannot achieve intelligent, adaptive protection throughout the entire lifecycle of the structure.

[0005] Therefore, developing a new type of high corrosion-resistant marine silicate cement that can synergistically solve the above problems from the perspectives of material composition design, microstructure control and functional integration has become a technical bottleneck that urgently needs to be overcome in the field of building materials in terms of long-term durability. Summary of the Invention

[0006] The purpose of this invention is to provide a high corrosion-resistant marine silicate cement and its preparation method to solve the problems mentioned in the background art.

[0007] In a first aspect, the present invention provides a high corrosion-resistant marine silicate cement, comprising the following raw materials in parts by weight: 70-80 parts of silicate cement clinker; 10-15 parts of ultrafine slag powder; 5-10 parts silica fume; Two to four doses of dual-response self-repair capsules; 1.5-3 parts of bifunctional nanocomposite material; 0.5-1.5 parts of bio-based supported inorganic synergistic mineralizer; 3-5 parts plaster; Triethanolamine 0.2-0.5 parts.

[0008] As a preferred embodiment of the present invention, the preparation method of the dual-response self-healing capsule is as follows: A1. The phase change material was heated to 60℃ to melt. Deionized water and sodium dodecyl sulfate were added under stirring in a water bath at 60℃. The mixture was emulsified for 10 min under high-speed shear at 10000-14000 r / min to form an oil-in-water emulsion. Tetraethyl orthosilicate and ammonia were added. The mixture was stirred and reacted at 60℃ for 6 h. The mixture was collected by centrifugation, washed three times with ethanol, and dried under vacuum at 60℃ to obtain the phase change material @SiO2 nanomaterial, which was named Repair Agent A. The phase change material is refined paraffin or n-octadecane; The phase transition temperature of the refined paraffin is 28°C; The concentration of the ammonia solution is 20-30%; The ratio of the phase change material, deionized water, sodium dodecyl sulfate, tetraethyl orthosilicate, and ammonia is 10g:200mL:1g:2g:1mL. A2. Weigh out sodium metasilicate, lithium silicate and lithium sulfate, mix and grind them evenly in a mortar to obtain repair agent B; The ratio of sodium metasilicate, lithium silicate, and lithium sulfate is 5:2:0.5; A3. Prepare a chloroform solution containing poly(N-isopropylacrylamide), a hexane suspension containing repair agent A, and an ethanol solution containing polyvinyl butyral. Using a microfluidic device, perform the first layer coating. The inner phase 1 is a hexane suspension containing repair agent A, the intermediate phase 1 is a chloroform solution containing poly(N-isopropylacrylamide), and the outer phase 1 is a 1% polyvinyl alcohol aqueous solution. Control the flow rate of the inner phase to 5 μL / min, the flow rate of the intermediate phase to 15 μL / min, and the flow rate of the outer phase to 40 μL / min. Collect the monolayer PNIPAM-coated microsphere emulsion at 25°C. The PAM-coated microsphere emulsion was centrifuged, filtered, and washed three times with anhydrous ethanol to obtain a monolayer of PNIPAM-coated microspheres. The obtained monolayer PNIPAM-coated microspheres were redispersed in anhydrous ethanol to prepare a suspension as the inner phase 2 for the second coating. The intermediate phase 2 was a slurry formed by mixing repair agent B powder with an ethanol solution containing polyvinyl butyral, and the outer phase 2 was a 2% polyvinyl alcohol aqueous solution. The flow rates of the inner phase, intermediate phase, and outer phase were controlled at 3 μL / min, 8 μL / min, and 25 μL / min, and the droplets were collected at 30℃ to obtain a bilayer coated microsphere emulsion. The chloroform solution containing poly(N-isopropylacrylamide) has a poly(N-isopropylacrylamide) mass fraction of 5%. The mass fraction of repair agent A in the hexane suspension containing repair agent A is 10%. The ethanol solution containing polyvinyl butyral has a polyvinyl butyral mass fraction of 8%. In the inner phase suspension used for the second coating, the mass ratio of monolayer PNIPAM-coated microspheres to anhydrous ethanol is 1:99. In the intermediate phase slurry used for the second coating layer, the ratio of repair agent B powder to ethanol solution containing polyvinyl butyral is 1g:5mL. A4. The double-layer coated microsphere emulsion obtained in A3 was allowed to stand at low temperature and then dried with hot air at 60°C for 12 hours to solidify the PVB shell and evaporate the solvent. The particles were then collected by filtering through a 200-400 mesh sieve and vacuum dried at 40°C for 24 hours to obtain the dual-response self-healing capsule.

[0009] It should be noted that the dual-response self-healing capsule utilizes microfluidic technology to construct a double-shell core structure. The inner layer is a thermosensitive polymer (PNIPAM) shell encapsulating phase change paraffin, while the outer layer is a moisture-sensitive polymer (PVB) shell encapsulating a crystalline repair agent (Repair Agent B). When ambient humidity increases or moisture penetrates along the crack, water molecule penetration causes the outer PVB shell to gradually swell, soften, and even disintegrate, releasing the internal silicate-based repair agent (Repair Agent B). This repair agent reacts with the cement hydration product Ca(OH)2 at the crack to generate hydration products such as CSH gel, achieving initial chemical repair and sealing of the crack. Subsequently, when microcracks appear in the cement matrix due to temperature fluctuations, stress or heat transfer at the crack tip can cause the thermosensitive polymer shell to undergo phase change shrinkage or rupture, releasing the phase change material. When phase change materials absorb heat and undergo a solid-liquid phase change, they expand in volume, dissipate heat stress, and can exert a certain squeezing and filling effect on microcracks. They flow and fill the crack space that has been initially sealed by repair agent B, providing secondary physical repair and stress buffering, and further enhancing the density and toughness of the repair.

[0010] As a preferred embodiment of the present invention, the preparation method of the bifunctional nanocomposite material is as follows: B1. Dissolve hexadecyltrimethylammonium bromide in a mixture of deionized water and ethanol, stir until clear, add ammonia, stir in a 35°C water bath for 30 min, add tetraethyl orthosilicate dropwise, continue the reaction for 6 h, centrifuge after the reaction is complete, wash with a mixture of ethanol and dilute hydrochloric acid to remove the template agent, dry at 80°C, and grind to obtain mesoporous silica nanospheres. The ratio of hexadecyltrimethylammonium bromide, deionized water, ethanol, ammonia, and tetraethyl orthosilicate is 2g:480mL:70mL:30mL:10mL. The concentration of the ammonia solution is 20-30%. The concentration of dilute hydrochloric acid in the mixture of ethanol and dilute hydrochloric acid is 0.1 mol / L; B2. LDH nanosheets were prepared by co-precipitation method. A mixed salt solution containing magnesium nitrate and aluminum nitrate and a mixed alkaline solution containing sodium hydroxide and sodium carbonate were simultaneously added dropwise to deionized water under nitrogen protection and vigorous stirring. The dropwise rate was 2 mL / min, the pH of the reaction system was controlled at 10, and the mixture was aged at 60 °C for 18 h. After centrifugation, washing with water and freeze drying, LDH nanosheet powder was obtained. The concentration of magnesium nitrate in the mixed salt solution containing magnesium nitrate and aluminum nitrate is 0.2 mol / L, and the concentration of aluminum nitrate is 0.1 mol / L. The concentration of sodium hydroxide in the mixed alkaline solution containing sodium hydroxide and sodium carbonate is 0.8 mol / L, and the concentration of sodium carbonate is 0.2 mol / L. The volume ratio of the mixed salt solution, the mixed alkaline solution, and the deionized water is 1:1:2; B3. Place the mesoporous silica nanospheres prepared in B1 in a vacuum dryer, apply a vacuum of -0.1 MPa and maintain it for 1 h. Disperse the LDH nanosheet powder prepared in B2 in anhydrous ethanol to form a suspension and inject it into the dryer. Immerse the mesoporous silica nanosphere carrier in the suspension while maintaining the vacuum. After restoring normal pressure, let it stand for 24 h, filter, and dry at 60 °C to obtain LDH-loaded silica nanoparticles. The ratio of mesoporous silica nanospheres, LDH nanosheets, and anhydrous ethanol is 5g:1g:50mL. B4. Dissolve sodium silicate and sodium hydroxide in water to form an aqueous phase, and dissolve Span-80 emulsifier in liquid paraffin to form an oil phase. Under high-speed shear at 8000-12000 r / min, slowly add the aqueous phase to the oil phase and emulsify for 15 min to form a water-in-oil microemulsion. Spray dry to obtain sustained-release microspheres. Mix the LDH-supported silica nanoparticles prepared in B3 with the sustained-release microspheres, add anhydrous ethanol, and mix for 2 h in a drum mixer at 30 r / min to obtain a composite material. The ratio of sodium silicate, sodium hydroxide, water, Span-80 emulsifier and liquid paraffin is 3g:1g:20mL:1g:40mL; The conditions for the spray drying operation are an inlet temperature of 180°C and an outlet temperature of 80°C. The ratio of LDH-supported silica nanoparticles, sustained-release microspheres, and anhydrous ethanol is 5g:1g:(20-50)mL. B5. Dissolve silane coupling agent KH-570 in a 95% ethanol solution, adjust the pH to 4-5 with acetic acid, let stand for 30 min to obtain hydrolysate, immerse the composite material obtained in B4 in the hydrolysate, sonicate for 10 min, react at 60℃ for 4 h with stirring, centrifuge, wash, and dry at 80℃ to obtain bifunctional nanocomposite material.

[0011] It should be noted that the bifunctional nanocomposite material uses mesoporous silica as a framework, loads layered double hydroxide (LDH) nanosheets, and anchors alkali-activated repair microspheres (sodium silicate / sodium hydroxide) through physical mixing and surface modification. When this material is incorporated into marine cement, the LDH dispersed in the cement matrix can selectively adsorb invading chloride ions using its interlayer ion exchange properties, thereby reducing the concentration of free chloride ions in the pore fluid. The external alkali-activated repair microspheres can slowly dissolve in the alkaline environment of the cement pore fluid, continuously releasing silicate and hydroxide ions. Silicate ions can react with calcium ions generated during cement hydration to form additional CSH gel, filling capillary pores; hydroxide ions help maintain a high pH value in the pore fluid, inhibiting steel reinforcement depassivation. This combination of harmful ion adsorption and beneficial ion slow release aims to enhance the erosion resistance of the cement matrix through different pathways.

[0012] As a preferred embodiment of the present invention, the preparation method of the bio-based supported inorganic synergistic mineralizer is as follows: C1. Prepare liquid culture medium, sterilize at 121℃ for 20 min, inoculate with Bacillus pasteurellii, and culture with shaking at 30℃ and 180 r / min for 48 h to obtain bacterial suspension. Centrifuge at 8000 r / min at 0-4℃ for 10 min to collect bacterial cells, wash with sterile physiological saline, resuspend in sterile CaCl2 solution, and incubate at 0-4℃ for 7 days to induce spore formation; centrifuge again to collect spores, wash with sterile water, and freeze-dry to obtain spore powder; The liquid culture medium contains 10g urea, 5g yeast extract, 5g peptone, 10g sodium acetate and 0.1g manganese sulfate per liter, with a pH of 9; The CaCl2 solution concentration is 0.5 mol / L, and the amount used is to resuspend the bacterial cells obtained by centrifugation in 20 mL of sterile CaCl2 solution for every 100 mL of bacterial culture. C2. Attapulgite clay is calcined at 500℃ for 2 hours, cooled, and then mixed with the spore powder obtained in C1 to obtain mixture 1; polylactic acid is dissolved in dichloromethane, and urea and yeast extract powder are dispersed in this solution, and nutrient-encapsulated polylactic acid microcapsules are obtained by spray drying; mixture 1, polylactic acid microcapsules, and carboxymethyl cellulose are mixed in a V-type mixer for 1 hour to obtain mixture 2; The ratio of attapulgite clay, spore powder, polylactic acid, dichloromethane, urea, and yeast extract is 5g:1g:2g:40mL:1.5g:0.5g. The conditions for the spray drying operation are an inlet temperature of 40°C and an outlet temperature of 25°C. The mass ratio of the mixture 1, polylactic acid microcapsules, and carboxymethyl cellulose is (4-6):0.8:0.2; C3. Using a fluidized bed granulator, the mixture 2 obtained in C2 is used as the base material, and a 5% hydroxypropyl methylcellulose aqueous solution is used as the binder for atomized spray granulation. The air inlet and material temperature are controlled to obtain bio-based particles. Slag silicate cement powder is mixed with water to form a slurry as a pre-hardening coating material. The bio-based particles are used as the core for bottom spray coating in a fluidized bed. The mixture is cured at room temperature and 95% relative humidity for 48 hours and dried at 30℃ to constant weight to obtain a bio-based loaded inorganic synergistic mineralizer. The fluidized bed granulation conditions are: inlet air temperature 50°C and material temperature 40°C. The mass ratio of the slag silicate cement powder to water is 1:4.

[0013] It should be noted that the core of the bio-based inorganic synergistic mineralizer is the composite granulation of Bacillus pasteurellii spores, microcapsules providing nutrients for their metabolism, and porous attapulgite as an attachment carrier, with an outermost layer of cement-based protective shell. When incorporated into highly corrosion-resistant marine silicate cement, the outer protective shell provides physical isolation during the early stages of cement hydration, preventing premature inactivation of the internal spores in a strongly alkaline environment. During the service life of the concrete, if microcracks develop and moisture intrudes, the protective shell may gradually break down under the influence of moisture penetration and ion exchange. Subsequently, the released spores are activated in the presence of water and nutrients, and the urease produced by their metabolism catalyzes the hydrolysis of urea, generating carbonate ions, which then combine with calcium ions in the environment, depositing calcium carbonate crystals in situ at the cracks. The attapulgite carrier provides attachment points for microorganisms and regulates the local microenvironment. The calcium carbonate generated by this biomineralization process can physically fill cracks and mechanically interlock with the surrounding cement matrix, thereby repairing the microcracks.

[0014] A second aspect of the present invention provides a method for preparing high corrosion-resistant marine silicate cement, comprising the following steps: S1. Weigh the raw materials according to the weight parts, and dry the silicate cement clinker, gypsum, ultrafine slag powder and silica fume at 105℃ until the moisture content is less than 0.5%; place the dual-response self-healing capsules, dual-functional nanocomposite materials and bio-based loaded inorganic synergistic mineralizer in a desiccator for later use. S2. The dried clinker, gypsum, ultrafine slag powder and silica fume were put into a test planetary ball mill, triethanolamine was added, and the mill was ground at 300 r / min for 45 min. During the process, the mill was stopped every 15 min to cool for 5 min, and the milled material was obtained. S3. Transfer the material from the mill to a three-dimensional motion mixer. Add the bifunctional nanocomposite material at 10 r / min and mix for 15 min to ensure uniform dispersion. Add the bio-based loaded inorganic synergistic mineralizer and mix for 10 min. Add the dual-response self-healing capsules and mix at 5 r / min for 20 min. Discharge the material, vacuum seal it in an aluminum foil bag, and store it in a cool, dry place.

[0015] It should be noted that in this formulation system, there is a functional synergy between the bifunctional nanocomposite material and the bio-based supported inorganic synergistic mineralizer, as well as between the bifunctional nanocomposite material and silica fume.

[0016] First, the bifunctional nanocomposite material provides targeted and optimized reaction sites for the biomineralizing agent. After adsorbing chloride ions, the layered double hydroxide (LDH) within the composite material may adaptively adjust its lamellar structure, leading to changes in the ion concentration and pH of the local microenvironment within the crack. This microenvironment preferentially induces and accelerates the subsequent activated biomineralization process, making it easier for calcium carbonate crystals to efficiently nucleate and grow on and around the LDH particles. The result is not only crack filling but also the formation of an adsorption and sealing barrier: the calcium carbonate crystals encapsulate and fix the LDH particles that have adsorbed chloride ions, achieving a dual physicochemical locking of harmful ions and enhancing the stability of the restoration.

[0017] Secondly, the bifunctional nanocomposite material acts as an efficient alkali source for the activation of silica fume. The alkaline slow-release microspheres loaded on it provide continuous and controllable local alkali activation within the cement matrix, creating optimal reaction micro-zones for the ultra-highly active silica fume. Compared to conventional mixing, this inside-out, directional supply of alkali environment can more fully and uniformly activate the pozzolanic reaction of silica fume, promoting the formation of a large amount of low-calcium-to-silica CSH gel. This process optimizes the pore structure of cement stone, and its pore refinement effect is superior to the reaction of silica fume with alkali activator alone under ordinary alkali conditions. Thus, macroscopically, it synergistically endows the matrix with excellent impermeability and erosion resistance.

[0018] Compared with the prior art, the present invention has the following beneficial effects: (1) This invention achieves phased repair of microcracks by introducing a self-healing capsule with dual temperature and humidity response characteristics. First, the volume change of the phase change material is used for preliminary physical filling, and then chemical healing is achieved by generating hydration products through a chemical repair agent, which helps to improve the adaptability of concrete crack repair in alternating wet and dry marine environments.

[0019] (2) This invention introduces a nanocomposite material that combines chloride ion adsorption and alkaline substance slow release functions. On the one hand, it reduces the risk of corrosion to steel bars by adsorbing chloride ions through LDH; on the other hand, it promotes matrix densification and maintains a high-alkaline environment by slowly releasing alkaline-activated components, thereby enhancing the durability of cement matrix from multiple angles, delaying the corrosion process, and improving the intrinsic corrosion resistance of cement matrix.

[0020] (3) This invention employs bio-based loading synergistic mineralization technology. By encapsulating and protecting microbial spores, they can be activated when the cement matrix is ​​damaged in the later stages, and the cracks are repaired by bio-induced calcium carbonate precipitation, providing a supplementary method to improve the long-term service performance of cement-based materials. Detailed Implementation

[0021] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] Preparation Example 1 The preparation method of the dual-response self-repair capsule is as follows: A1. Melt 10g of n-octadecane at 60℃, add 200mL of deionized water and 1g of sodium dodecyl sulfate under stirring in a water bath at 60℃, emulsify for 10min under high-speed shear at 12000r / min to form an oil-in-water emulsion; add 2g of tetraethyl orthosilicate and 1mL of 25% ammonia, stir and react at 60℃ for 6h, collect by centrifugation, wash three times with ethanol, and vacuum dry at 60℃ to obtain the phase change material @SiO2 nanomaterial, named repair agent A; A2. Weigh 5g of sodium metasilicate, 2g of lithium silicate and 0.5g of lithium sulfate, mix and grind them evenly in a mortar to obtain repair agent B; A3. Prepare a chloroform solution containing poly(N-isopropylacrylamide), a hexane suspension containing repair agent A, and an ethanol solution containing polyvinyl butyral. Using a microfluidic device, perform the first layer coating. The inner phase 1 is a hexane suspension containing repair agent A, the intermediate phase 1 is a chloroform solution containing poly(N-isopropylacrylamide), and the outer phase 1 is a 1% polyvinyl alcohol aqueous solution. Control the flow rate of the inner phase to 5 μL / min, the flow rate of the intermediate phase to 15 μL / min, and the flow rate of the outer phase to 40 μL / min. Collect the monolayer PNIPAM-coated microsphere emulsion at 25°C. The PAM-coated microsphere emulsion was centrifuged, filtered, and washed three times with anhydrous ethanol to obtain a monolayer of PNIPAM-coated microspheres. The obtained monolayer PNIPAM-coated microspheres were redispersed in anhydrous ethanol to prepare a suspension as the inner phase 2 for the second coating. The intermediate phase 2 was a slurry formed by mixing repair agent B powder with an ethanol solution containing polyvinyl butyral, and the outer phase 2 was a 2% polyvinyl alcohol aqueous solution. The flow rates of the inner phase, intermediate phase, and outer phase were controlled at 3 μL / min, 8 μL / min, and 25 μL / min, and the droplets were collected at 30℃ to obtain a bilayer coated microsphere emulsion. The chloroform solution containing poly(N-isopropylacrylamide) has a poly(N-isopropylacrylamide) mass fraction of 5%. The mass fraction of repair agent A in the hexane suspension containing repair agent A is 10%. The ethanol solution containing polyvinyl butyral has a polyvinyl butyral mass fraction of 8%. In the inner phase suspension used for the second coating, the mass ratio of monolayer PNIPAM-coated microspheres to anhydrous ethanol is 1:99. In the intermediate phase slurry used for the second coating layer, the ratio of repair agent B powder to ethanol solution containing polyvinyl butyral is 1g:5mL. A4. The double-layer coated microsphere emulsion obtained in A3 was allowed to stand at low temperature and then dried with hot air at 60°C for 12 hours to solidify the PVB shell and evaporate the solvent. The particles were then filtered through a 300-mesh sieve, collected, and vacuum dried at 40°C for 24 hours to obtain the dual-response self-healing capsule.

[0023] Preparation Example 2 The preparation method of bifunctional nanocomposite materials is as follows: B1. Dissolve 2g of hexadecyltrimethylammonium bromide in a mixture of 480mL of deionized water and 70mL of ethanol, stir until clear, add 30mL of 25% ammonia, stir in a 35℃ water bath for 30min, add 10mL of tetraethyl orthosilicate dropwise, continue the reaction for 6h, centrifuge after the reaction is completed, wash with a mixture of ethanol L and 0.1mol / dilute hydrochloric acid to remove the template agent, dry at 80℃, and grind to obtain mesoporous silica nanospheres; B2. LDH nanosheets were prepared by co-precipitation method. A mixed salt solution containing magnesium nitrate and aluminum nitrate and a mixed alkaline solution containing sodium hydroxide and sodium carbonate were simultaneously added dropwise to deionized water under nitrogen protection and vigorous stirring. The dropwise rate was 2 mL / min, the pH of the reaction system was controlled at 10, and the mixture was aged at 60 °C for 18 h. After centrifugation, washing with water and freeze drying, LDH nanosheet powder was obtained. The concentration of magnesium nitrate in the mixed salt solution containing magnesium nitrate and aluminum nitrate is 0.2 mol / L, and the concentration of aluminum nitrate is 0.1 mol / L. The concentration of sodium hydroxide in the mixed alkaline solution containing sodium hydroxide and sodium carbonate is 0.8 mol / L, and the concentration of sodium carbonate is 0.2 mol / L. The volume ratio of the mixed salt solution, the mixed alkaline solution, and the deionized water is 1:1:2; B3. Place 5g of mesoporous silica nanospheres prepared by B1 in a vacuum dryer, apply a vacuum of -0.1MPa and maintain it for 1h. Disperse 1g of LDH nanosheet powder prepared by B2 in 50mL of anhydrous ethanol to form a suspension and inject it into the dryer. Immerse the mesoporous silica nanosphere carrier in the suspension under vacuum conditions. After restoring normal pressure, let it stand for 24h, filter, and dry at 60℃ to obtain LDH-loaded silica nanoparticles. B4. Dissolve 3g of sodium silicate and 1g of sodium hydroxide in 20mL of water to form an aqueous phase. Dissolve 1g of Span-80 emulsifier in 40mL of liquid paraffin to form an oil phase. Under high-speed shear at 10000r / min, slowly add the aqueous phase to the oil phase and emulsify for 15min to form a water-in-oil microemulsion. Spray dry the microemulsion at an inlet temperature of 180℃ and an outlet temperature of 80℃ to obtain sustained-release microspheres. Mix 5g of LDH-supported silica nanoparticles prepared in B3 with 1g of sustained-release microspheres, add 30mL of anhydrous ethanol, and mix for 2h in a drum mixer at 30r / min to obtain a composite material. B5. Dissolve silane coupling agent KH-570 in a 95% ethanol solution, adjust the pH to 4.5 with acetic acid, let stand for 30 min to obtain hydrolysate, immerse the composite material obtained in B4 in the hydrolysate, sonicate for 10 min, react at 60℃ for 4 h with stirring, centrifuge, wash, and dry at 80℃ to obtain bifunctional nanocomposite material.

[0024] Preparation Example 3 The preparation method of bio-based supported inorganic synergistic mineralizer is as follows: C1. Prepare liquid culture medium, sterilize at 121℃ for 20 min, inoculate with Bacillus pasteurellii, and culture with shaking at 30℃ and 180 r / min for 48 h to obtain bacterial suspension. Centrifuge at 8000 r / min at 4℃ for 10 min to collect bacterial cells, wash with sterile physiological saline and resuspend in sterile CaCl2 solution, and incubate at 4℃ for 7 days to induce spore formation; centrifuge again to collect spores, wash with sterile water and freeze-dry to obtain spore powder. The liquid culture medium contains 10g urea, 5g yeast extract, 5g peptone, 10g sodium acetate and 0.1g manganese sulfate per liter, with a pH of 9; The CaCl2 solution concentration is 0.5 mol / L, and the amount used is 100 mL of bacterial solution centrifuged and the bacterial cells are resuspended in 20 mL of sterile CaCl2 solution; C2. Calcine 5g of attapulgite at 500℃ for 2h, cool it, and mix it with 1g of spore powder prepared by C1 to obtain mixture 1; Dissolve 2g of polylactic acid in 40mL of dichloromethane, and disperse 1.5g of urea and 0.5g of yeast extract powder in this solution, and spray dry it at an inlet temperature of 40℃ and an outlet temperature of 25℃ to obtain polylactic acid microcapsules coated with nutrients; Mix 5g of mixture 1, 0.8g of polylactic acid microcapsules and 0.2g of carboxymethyl cellulose in a V-type mixer for 1h to obtain mixture 2; C3. Using a fluidized bed granulator, the mixture 2 obtained in C2 is used as the base material, and a 5% hydroxypropyl methylcellulose aqueous solution is used as the binder for atomized spray granulation. The inlet air temperature is controlled at 50℃ and the material temperature at 40℃ to obtain bio-based particles. Slag silicate cement powder is mixed with water to form a slurry as a pre-hardening coating material. The bio-based particles are used as the core for bottom spray coating in a fluidized bed. The mixture is cured at room temperature and 95% relative humidity for 48 hours and dried at 30℃ to constant weight to obtain a bio-based loaded inorganic synergistic mineralizer. The mass ratio of the slag silicate cement powder to water is 1:4. Example

[0025] A method for preparing high corrosion-resistant marine silicate cement includes the following steps: S1. Weigh the raw materials according to the weight parts, and dry the silicate cement clinker, gypsum, ultrafine slag powder and silica fume at 105℃ until the moisture content is less than 0.5%; place the dual-response self-healing capsules, dual-functional nanocomposite materials and bio-based loaded inorganic synergistic mineralizer in a desiccator for later use. S2. 750 parts of dried silicate cement clinker, 4 parts of gypsum, 12.5 parts of ultrafine slag powder and silica fume were put into a test planetary ball mill, and 0.35 parts of triethanolamine were added. The mill was ground at 300 r / min for 45 min, with the mill stopped every 15 min to cool for 5 min, and the milled material was obtained. S3. Transfer the milled material to a three-dimensional motion mixer. Add 2.3 parts of bifunctional nanocomposite material at 10 r / min and mix for 15 min to ensure uniform dispersion. Add 1 part of bio-based loaded inorganic synergistic mineralizer and mix for 10 min. Add 3 parts of dual-response self-healing capsules and mix at 5 r / min for 20 min. Discharge the material, vacuum seal it in an aluminum foil bag, and store it in a cool, dry place.

[0026] In this embodiment, some of the raw materials used are the same as those obtained in some of the preparation examples 1-3, and the other examples are the same. Example

[0027] A method for preparing high corrosion-resistant marine silicate cement includes the following steps: S1. Weigh the raw materials according to the weight parts, and dry the silicate cement clinker, gypsum, ultrafine slag powder and silica fume at 105℃ until the moisture content is less than 0.5%; place the dual-response self-healing capsules, dual-functional nanocomposite materials and bio-based loaded inorganic synergistic mineralizer in a desiccator for later use. S2. 70 parts of dried silicate cement clinker, 3 parts of gypsum, 10 parts of ultrafine slag powder and silica fume were put into a small planetary ball mill for testing. 0.2 parts of triethanolamine were added and the mill was ground at a speed of 300 r / min for 45 min. During the process, the mill was stopped every 15 min to cool for 5 min, and the milled material was obtained. S3. Transfer the material from the mill to a three-dimensional motion mixer. Add 1.5 parts of bifunctional nanocomposite material at 10 r / min and mix for 15 min to ensure uniform dispersion. Add 0.5 parts of bio-based loaded inorganic synergistic mineralizer and mix for 10 min. Add 2 parts of dual-response self-healing capsules and mix at 5 r / min for 20 min. Discharge the material, vacuum seal it in an aluminum foil bag, and store it in a cool, dry place.

[0028] In this embodiment, some of the raw materials used are the same as those obtained in some of the preparation examples 1-3, and the other examples are the same. Example

[0029] A method for preparing high corrosion-resistant marine silicate cement includes the following steps: S1. Weigh the raw materials according to the weight parts, and dry the silicate cement clinker, gypsum, ultrafine slag powder and silica fume at 105℃ until the moisture content is less than 0.5%; place the dual-response self-healing capsules, dual-functional nanocomposite materials and bio-based loaded inorganic synergistic mineralizer in a desiccator for later use. S2. Add 80 parts of dried silicate cement clinker, 5 parts of gypsum, 15 parts of ultrafine slag powder and silica fume into a test planetary ball mill, add 0.5 parts of triethanolamine, and grind at 300 r / min for 45 min, stopping the mill every 15 min to cool for 5 min, to obtain the milled material. S3. Transfer the material from the mill to a three-dimensional motion mixer. Add 3 parts of bifunctional nanocomposite material at 10 r / min and mix for 15 min to ensure uniform dispersion. Add 1.5 parts of bio-based loaded inorganic synergistic mineralizer and mix for 10 min. Add 4 parts of dual-response self-healing capsules and mix at 5 r / min for 20 min. Discharge the material, vacuum seal it in an aluminum foil bag, and store it in a cool, dry place.

[0030] In this embodiment, some of the raw materials used are the same as those obtained in some of the preparation examples 1-3, and the other examples are the same.

[0031] Comparative Example 1 The difference between this comparative example and Example 1 is that, instead of using a dual-response self-healing capsule, an equal weight of n-octadecane was used.

[0032] Comparative Example 2 The difference between this comparative example and Example 1 is that a bifunctional nanocomposite material was not used; instead, an equal part by weight of layered double hydroxide (LDH) was used.

[0033] Comparative Example 3 The difference between this comparative example and Example 1 is that, instead of using a bio-based loaded inorganic synergistic mineralizer, an equal weight portion of attapulgite clay calcined at 500°C for 2 hours was used.

[0034] test: I. Mechanical property testing The compressive strength of concrete specimens after 28 days was determined in accordance with GB / T 17671-2021 Test Method for Strength of Cement Mortar.

[0035] II. Chloride Ion Diffusion Coefficient Test The chloride ion diffusion coefficient was tested in accordance with GB / T 50082-2024 Standard for Test Methods of Long-Term Performance and Durability of Concrete.

[0036] III. Self-healing performance evaluation The pre-cracking immersion method was employed. After curing cement mortar specimens (40mm×40mm×160mm) for 28 days, a crack with a width of 0.15±0.02mm was pre-introduced through a three-point bending test. The specimens were then immersed in a 3.5% NaCl solution and placed in a 40℃ oven for wet-dry cycles (immersion for 12 hours, drying for 12 hours constitutes one cycle), for a total of 10 cycles. After the cycles, the specimens were removed, dried, and the residual crack width was measured using an optical microscope. The crack healing rate was calculated using the following formula: Healing rate (%) = [(initial crack width - residual crack width) / initial crack width] × 100%.

[0037] IV. Sulfate resistance test According to GB / T 749-2008 Cement Resistance to Sulfate Attack Test Method, the resistance to sulfate attack was tested, and the linear expansion rate after soaking for 150 days was recorded.

[0038] V. Electrochemical Performance Testing (Assessment of Steel Reinforcement Corrosion) Mortar specimens (40mm × 40mm × 160mm, with the reinforcing bar in the center) with embedded steel bars were prepared. After standard curing for 28 days, the specimens were immersed in a 3.5% NaCl solution. Using an electrochemical workstation, the self-corrosion potential (relative to the CSE reference electrode) and linear polarization resistance of the reinforcing bar were measured at 30 and 90 days of immersion.

[0039] The test results are shown in Table 1.

[0040] VI. Summary of Results Table 1

[0041] VII. Discussion of Results As shown in Table 1, the high corrosion-resistant marine silicate cement prepared in Examples 1-3 of this invention has comprehensive properties, excellent corrosion resistance and self-healing ability, and can provide excellent protection for steel bars.

[0042] Compared to Examples 1-3, all durability indicators of Comparative Example 1 decreased significantly, indicating that the dual-response self-healing capsule is the key to maintaining long-term performance.

[0043] Compared to Examples 1-3, Comparative Example 2 showed an increased chloride ion diffusion coefficient and a significantly increased risk of steel reinforcement corrosion, confirming the dominant role of bifunctional nanocomposite materials in ion interception and steel reinforcement protection.

[0044] Compared with Examples 1-3, the crack healing rate and erosion resistance of Comparative Example 3 after long-term immersion decreased slightly, indicating that biomineralization provided long-term protection and secondary densification.

[0045] In the description of this specification, the references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0046] The above description is merely an example and illustration of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the scope defined by the invention, and all such modifications and additions should fall within the protection scope of the present invention.

Claims

1. A high corrosion-resistant marine silicate cement, characterized in that: The following ingredients are included by weight: 70-80 parts of silicate cement clinker; 10-15 parts of ultrafine slag powder; 5-10 parts silica fume; Two to four doses of dual-response self-repair capsules; 1.5-3 parts of bifunctional nanocomposite material; 0.5-1.5 parts of bio-based supported inorganic synergistic mineralizer; 3-5 parts plaster; Triethanolamine 0.2-0.5 parts.

2. The high corrosion-resistant marine silicate cement according to claim 1, characterized in that: The preparation method of the dual-response self-healing capsule is as follows: A1. The phase change material was heated to 60℃ to melt, and deionized water and sodium dodecyl sulfate were added under stirring in a water bath at 60℃. The mixture was emulsified for 10 min under high-speed shear at 10000-14000 r / min to form an oil-in-water emulsion. Tetraethyl orthosilicate and ammonia were added, and the mixture was stirred and reacted at 60℃ for 6 h. The mixture was collected by centrifugation, washed three times with ethanol, and dried under vacuum at 60℃ to obtain repair agent A. The phase change material is refined paraffin or n-octadecane; The phase transition temperature of the refined paraffin is 28°C; A2. Weigh out sodium metasilicate, lithium silicate and lithium sulfate, mix and grind them evenly in a mortar to obtain repair agent B; A3. Prepare a chloroform solution containing poly(N-isopropylacrylamide), a hexane suspension containing repair agent A, and an ethanol solution containing polyvinyl butyral. Using a microfluidic device, perform the first layer coating. The inner phase 1 is a hexane suspension containing repair agent A, the intermediate phase 1 is a chloroform solution containing poly(N-isopropylacrylamide), and the outer phase 1 is a 1% polyvinyl alcohol aqueous solution. Control the flow rate of the inner phase to 5 μL / min, the flow rate of the intermediate phase to 15 μL / min, and the flow rate of the outer phase to 40 μL / min. Collect the monolayer PNIPAM-coated microsphere emulsion at 25°C. The PAM-coated microsphere emulsion was centrifuged, filtered, and washed three times with anhydrous ethanol to obtain a monolayer of PNIPAM-coated microspheres. The obtained monolayer PNIPAM-coated microspheres were redispersed in anhydrous ethanol to prepare a suspension as the inner phase 2 for the second coating. The intermediate phase 2 was a slurry formed by mixing repair agent B powder with an ethanol solution containing polyvinyl butyral, and the outer phase 2 was a 2% polyvinyl alcohol aqueous solution. The flow rates of the inner phase, intermediate phase, and outer phase were controlled at 3 μL / min, 8 μL / min, and 25 μL / min, and the droplets were collected at 30℃ to obtain a bilayer coated microsphere emulsion. The chloroform solution containing poly(N-isopropylacrylamide) has a poly(N-isopropylacrylamide) mass fraction of 5%. The mass fraction of repair agent A in the hexane suspension containing repair agent A is 10%. The ethanol solution containing polyvinyl butyral has a polyvinyl butyral mass fraction of 8%. In the inner phase suspension used for the second coating, the mass ratio of monolayer PNIPAM-coated microspheres to anhydrous ethanol is 1:

99. In the intermediate phase slurry used for the second coating layer, the ratio of repair agent B powder to ethanol solution containing polyvinyl butyral is 1g:5mL. A4. The double-layer coated microsphere emulsion obtained in A3 was allowed to stand at low temperature and then dried with hot air at 60°C for 12 hours to solidify the polyvinyl butyral shell and evaporate the solvent. The particles were then filtered through a 200-400 mesh sieve, collected, and vacuum dried at 40°C for 24 hours to obtain the dual-response self-healing capsule.

3. The high corrosion-resistant marine silicate cement according to claim 2, characterized in that: In step A1, the ratio of the phase change material, deionized water, sodium dodecyl sulfate, tetraethyl orthosilicate, and ammonia is 10g:200mL:1g:2g:1mL.

4. The high corrosion-resistant marine silicate cement according to claim 2, characterized in that: In step A2, the ratio of sodium metasilicate, lithium silicate, and lithium sulfate is 5:2:0.

5.

5. The high corrosion-resistant marine silicate cement according to claim 1, characterized in that: The preparation method of the bifunctional nanocomposite material is as follows: B1. Dissolve hexadecyltrimethylammonium bromide in a mixture of deionized water and ethanol, stir until clear, add ammonia, stir in a 35°C water bath for 30 min, add tetraethyl orthosilicate dropwise, continue the reaction for 6 h, centrifuge after the reaction is complete, wash with a mixture of ethanol and dilute hydrochloric acid to remove the template agent, dry at 80°C, and grind to obtain mesoporous silica nanospheres. The concentration of the ammonia water is 20-30%; The concentration of dilute hydrochloric acid in the mixture of ethanol and dilute hydrochloric acid is 0.1 mol / L; B2. LDH nanosheets were prepared by co-precipitation method. A mixed salt solution containing magnesium nitrate and aluminum nitrate and a mixed alkaline solution containing sodium hydroxide and sodium carbonate were simultaneously added dropwise to deionized water under nitrogen protection and stirring. The dropwise rate was 2 mL / min, the pH of the reaction system was controlled at 10, and the mixture was aged at 60 °C for 18 h. After centrifugation, washing with water and freeze drying, LDH nanosheet powder was obtained. The concentration of magnesium nitrate in the mixed salt solution containing magnesium nitrate and aluminum nitrate is 0.2 mol / L, and the concentration of aluminum nitrate is 0.1 mol / L. The concentration of sodium hydroxide in the mixed alkaline solution containing sodium hydroxide and sodium carbonate is 0.8 mol / L, and the concentration of sodium carbonate is 0.2 mol / L. The volume ratio of the mixed salt solution, the mixed alkaline solution, and the deionized water is 1:1:2; B3. Place the mesoporous silica nanospheres prepared in B1 in a vacuum dryer, apply a vacuum of -0.1 MPa and maintain it for 1 h. Disperse the LDH nanosheet powder prepared in B2 in anhydrous ethanol to form a suspension and inject it into the dryer. Immerse the mesoporous silica nanosphere carrier in the suspension while maintaining the vacuum. After restoring normal pressure, let it stand for 24 h, filter, and dry at 60 °C to obtain LDH-loaded silica nanoparticles. The ratio of mesoporous silica nanospheres, LDH nanosheets, and anhydrous ethanol is 5g:1g:50mL. B4. Dissolve sodium silicate and sodium hydroxide in water to form an aqueous phase, and dissolve Span-80 emulsifier in liquid paraffin to form an oil phase. Under high-speed shear at 8000-12000 r / min, slowly add the aqueous phase to the oil phase and emulsify for 15 min to form a water-in-oil microemulsion. Spray dry to obtain sustained-release microspheres. Mix the LDH-supported silica nanoparticles prepared in B3 with the sustained-release microspheres, add anhydrous ethanol, and mix for 2 h in a drum mixer at 30 r / min to obtain a composite material. The conditions for the spray drying operation are an inlet temperature of 180°C and an outlet temperature of 80°C. The ratio of LDH-supported silica nanoparticles, sustained-release microspheres, and anhydrous ethanol is 5g:1g:(20-50)mL. B5. Dissolve silane coupling agent KH-570 in a 95% ethanol solution, adjust the pH to 4-5 with acetic acid, let stand for 30 min to obtain hydrolysate, immerse the composite material obtained in B4 in the hydrolysate, sonicate for 10 min, react at 60℃ for 4 h with stirring, centrifuge, wash, and dry at 80℃ to obtain bifunctional nanocomposite material.

6. The high corrosion-resistant marine silicate cement according to claim 5, characterized in that: In step B1, the ratio of the amount of hexadecyltrimethylammonium bromide, deionized water, ethanol, ammonia, and tetraethyl orthosilicate is 2g:480mL:70mL:30mL:10mL.

7. The high corrosion-resistant marine silicate cement according to claim 5, characterized in that: In step B4, the ratio of sodium silicate, sodium hydroxide, water, Span-80 emulsifier, and liquid paraffin is 3g:1g:20mL:1g:40mL.

8. The high corrosion-resistant marine silicate cement according to claim 1, characterized in that: The preparation method of the bio-based supported inorganic synergistic mineralizer is as follows: C1. Prepare liquid culture medium, sterilize at 121℃ for 20 min, inoculate with Bacillus pasteurellii, and culture with shaking at 30℃ and 180 r / min for 48 h to obtain bacterial suspension. Centrifuge at 8000 r / min at 0-4℃ for 10 min to collect bacterial cells, wash with sterile physiological saline, resuspend in sterile CaCl2 solution, and incubate at 0-4℃ for 7 days to induce spore formation; centrifuge again to collect spores, wash with sterile water, and freeze-dry to obtain spore powder; The liquid culture medium contains 10g urea, 5g yeast extract, 5g peptone, 10g sodium acetate and 0.1g manganese sulfate per liter, with a pH of 9; The CaCl2 solution concentration is 0.5 mol / L, and the amount used is to resuspend the bacterial cells obtained by centrifugation in 20 mL of sterile CaCl2 solution for every 100 mL of bacterial culture. C2. Attapulgite clay is calcined at 500℃ for 2 hours, cooled, and then mixed with the spore powder obtained in C1 to obtain mixture 1; polylactic acid is dissolved in dichloromethane, and urea and yeast extract powder are dispersed in this solution, and nutrient-encapsulated polylactic acid microcapsules are obtained by spray drying; mixture 1, polylactic acid microcapsules, and carboxymethyl cellulose are mixed in a V-type mixer for 1 hour to obtain mixture 2; The ratio of attapulgite clay, spore powder, polylactic acid, dichloromethane, urea, and yeast extract is 5g:1g:2g:40mL:1.5g:0.5g. The conditions for the spray drying operation are an inlet temperature of 40°C and an outlet temperature of 25°C. C3. Using a fluidized bed granulator, the mixture 2 obtained in C2 is used as the base material. A 5% hydroxypropyl methylcellulose aqueous solution is used as the binder for atomized spray granulation. The air inlet and material temperature are controlled to obtain bio-based particles. Slag silicate cement powder is mixed with water to form a slurry as a pre-hardening coating material. The bio-based particles are used as the core for bottom spray coating in a fluidized bed. The mixture is cured at room temperature and 95% relative humidity for 48 hours and dried at 30℃ to constant weight to obtain a bio-based loaded inorganic synergistic mineralizer. The fluidized bed granulation conditions are: inlet air temperature 50°C and material temperature 40°C. The mass ratio of the slag silicate cement powder to water is 1:

4.

9. The high corrosion-resistant marine silicate cement according to claim 8, characterized in that: In step C2, the mass ratio of the mixture 1, polylactic acid microcapsules, and carboxymethyl cellulose is (4-6):0.8:0.

2.

10. A method for preparing high corrosion-resistant marine silicate cement as described in any one of claims 1-9, characterized in that: Includes the following steps: S1. Weigh the raw materials according to the weight parts, and dry the silicate cement clinker, gypsum, ultrafine slag powder and silica fume at 105℃ until the moisture content is less than 0.5%; place the dual-response self-healing capsules, dual-functional nanocomposite materials and bio-based loaded inorganic synergistic mineralizer in a desiccator for later use. S2. The dried clinker, gypsum, ultrafine slag powder and silica fume were put into a test planetary ball mill, triethanolamine was added, and the mill was ground at 300 r / min for 45 min. During the process, the mill was stopped every 15 min to cool for 5 min, and the milled material was obtained. S3. Transfer the material from the mill to a three-dimensional motion mixer. Add the bifunctional nanocomposite material at 10 r / min and mix for 15 min to ensure uniform dispersion. Add the bio-based loaded inorganic synergistic mineralizer and mix for 10 min. Add the dual-response self-healing capsules and mix at 5 r / min for 20 min. Discharge the material, vacuum seal it in an aluminum foil bag, and store it in a cool, dry place.

Images