A cement strength enhancer and a method for preparing the same

Abstract

The application relates to the technical field of cement admixtures, in particular to a cement strength synergist and a preparation method thereof. The synergist is composed of a nano-composite core component modified by biomimetic mineralization, an early-strength component, an interface strengthening component and a carrier component. The core lies in the following steps: firstly, a primary composite of nano-silicon dioxide and nano-crystal core material is prepared through a sol-gel method; then, an adhesion layer of polydopamine is formed on the surface of the primary composite by adopting a biomimetic dopamine interface polymerization technology; finally, secondary mineralization treatment is carried out in a simulated cement pore solution, so that hydrated calcium silicate nanocrystals are induced to grow in situ on the PDA layer, and an organic-inorganic hybrid core-shell structure is formed. After the synergist is activated and compounded with anhydrous sodium sulfate, triisopropanolamine and other components through high-speed shearing, the obtained product can simultaneously and significantly improve the early and late strength of cement, solves the problem of unbalanced strength development, has excellent adaptability, stability and energy-saving and carbon-reducing effects, and has a wide application prospect.

Description

Technical Field

[0001] This invention relates to the field of cement admixture technology, specifically to a cement strength enhancer and its preparation method. Background Technology

[0002] The cement industry is a pillar of the national economy, but it is also a major consumer of energy and a major emitter of carbon. Under the macro-level context of energy conservation and emission reduction, improving cement efficiency and reducing unit cement consumption through admixture technology is an inevitable path for the industry's sustainable development. Currently, most common cement strength enhancers on the market use inorganic salts such as sodium sulfate and triethanolamine combined with organic amines, or simply incorporate active materials such as mineral powder and fly ash. While these technologies have some effect, they have significant bottlenecks: First, the synergistic effect between simply compounded components is poor, and early strength improvement often comes at the expense of later strength, failing to achieve balanced strength development; second, physically mixed nanomaterials are prone to agglomeration and have poor dispersibility in alkaline cement foundations, making it difficult to fully utilize their nano-effects; third, the interfaces constructed by traditional modification methods (such as silane coupling agents) have limited compatibility with cement hydration products and limited catalytic nucleation efficiency.

[0003] Chinese invention patent CN100445231C discloses a concrete reinforcing agent and preparation method for a civil engineering material curing agent, which is a physical mixture of fly ash, sodium sulfate, triethanolamine, etc. This technology utilizes industrial solid waste, but it has problems such as limited reinforcing effect, weak later strength growth, high alkali content, and unstable compatibility with cement. The fundamental reason is that it fails to solve the nucleation and interface optimization problems at the source of the hydration mechanism.

[0004] This invention aims to break through the limitations of traditional technologies. We innovatively introduce the cutting-edge concept of biomimetic mineralization from materials science and bionics into the field of cement admixtures. By constructing an "organic-inorganic hybrid core-shell structure" that perfectly matches the crystal structure of cement hydration products, we fundamentally reshape the mechanism of action of strength enhancers. This not only provides a completely new solution to the inherent problem of unbalanced cement strength development but also greatly improves product performance and reliability, which is of great significance for promoting technological progress in the industry. Summary of the Invention

[0005] The purpose of this invention is to provide a cement strength enhancer and its preparation method. This enhancer consists of a biomimetic mineralization-modified nanocomposite core component, an early-strength component, an interface strengthening component, and a carrier component. The core of its preparation method lies in: firstly, preparing a primary composite of nano-silica and nanocrystalline nuclei using a sol-gel method; then, employing biomimetic dopamine interface polymerization technology to form a polydopamine (PDA) adhesion layer on the surface of the primary composite; finally, performing a secondary mineralization treatment in a simulated cement pore solution to induce the in-situ growth of hydrated calcium silicate nanocrystals on the PDA layer, forming an organic-inorganic hybrid core-shell structure. This specially structured nanocomposite core component acts as a "perfect nucleation seed," significantly reducing the cement hydration nucleation barrier and directionally guiding the dense growth of hydration products. After being combined with components such as anhydrous sodium sulfate and triisopropanolamine through high-speed shear activation, the resulting product can simultaneously and significantly improve the early and late-stage strength of cement, solving the problem of unbalanced strength development, and exhibiting excellent adaptability, stability, and energy-saving and carbon-reducing effects, showing broad application prospects.

[0006] A cement strength enhancer is made of the following components in weight percentage: 10-25% of a biomimetic mineralization modified nanocomposite core component, 10-20% of an early strength component, 0.5-2.5% of an interface strengthening component, 0.2-1.5% of a polymeric dispersant, and the balance being a carrier component.

[0007] Preferably, the biomimetic mineralization modified nanocomposite core component is obtained by biomimetic dopamine interfacial polymerization and secondary mineralization treatment; the primary composite of the nanocomposite core component is composed of nano-silica and nanocrystal nucleus material through sol-gel method, wherein the nanocrystal nucleus material is nano-sized calcium silicate.

[0008] Preferably, the primary composite preparation steps of the nanocomposite core component are as follows: the nanocrystalline nucleus material is dispersed in deionized water at a solid-liquid ratio of 1g:(5-15)mL, and nano-silica sol is slowly added under stirring conditions, wherein the mass ratio of silica in the nano-silica sol to the nanocrystalline nucleus material is 1:(4-1), and the pH of the system is adjusted to 10-11 with alkaline solution, and the reaction is carried out at 75-85℃ for 2-4 hours; after cooling, the mixture is filtered, washed, and dried to obtain the primary composite powder.

[0009] Preferably, the preparation steps of the biomimetic mineralization modified nanocomposite core component are as follows: the primary composite is dispersed in Tris-HCl buffer solution with a pH of 8.5 at a solid-liquid ratio of 1g:(20-100)mL, and then dopamine hydrochloride is added at a mass ratio of 1:(10-50) to the primary composite. The mixture is stirred and reacted at room temperature for 18-24 hours to coat the surface of the primary composite with polydopamine. After washing and drying, a polydopamine-coated intermediate is obtained. Then, this intermediate is dispersed in a simulated cement pore solution containing calcium ions and silicates at a solid-liquid ratio of 1g:(50-200)mL and reacted at 60-80℃ for 6-12 hours to induce the in-situ growth of hydrated calcium silicate crystals on its surface. After washing and drying, the final product is obtained.

[0010] Preferably, the simulated cement hole solution is a saturated calcium hydroxide solution or a solution containing K. + Na + Ca 2+ SO4 2- A mixed solution of ions.

[0011] Preferably, the early strength component is anhydrous sodium sulfate; and the interface strengthening component is triisopropanolamine.

[0012] Preferably, the polymeric dispersant is a polycarboxylate-based water-reducing agent powder.

[0013] Preferably, the carrier component is ultrafine fly ash microspheres with a specific surface area of ​​not less than 450 m² / kg.

[0014] A method for preparing a cement strength enhancer includes the following steps:

[0015] S1. Preparation of primary composite: Disperse nanocrystalline nuclei in deionized water at a solid-liquid ratio of 1g:(5-15)mL, slowly add nano-silica sol under stirring, wherein the mass ratio of silica in the nano-silica sol to nanocrystalline nuclei is 1:(1-4), adjust the pH of the system to 10-11 with alkaline solution, and react at 75-85℃ for 2-4 hours; after cooling, filter, wash, and dry to obtain the primary composite;

[0016] S2. Biomimetic mineralization modification: The primary composite obtained in S1 is coated with polydopamine and subjected to secondary mineralization treatment to obtain the modified nanocomposite core component; the polydopamine coating is carried out by dispersing the primary composite in Tris-HCl buffer solution with a pH of 8.5 at a solid-liquid ratio of 1g:(20-100)mL, adding dopamine hydrochloride at a mass ratio of 1:(10-50) to the primary composite, stirring and reacting at room temperature for 18-24 hours, and washing and drying after the reaction; the secondary mineralization treatment is carried out by dispersing the coated intermediate in simulated cement pore solution at a solid-liquid ratio of 1g:(50-200)mL, reacting at 60-80℃ for 6-12 hours, and washing and drying after the reaction;

[0017] S3. Homogenization and compounding: According to the formula, the modified core component, early strength component, interface strengthening component, polymer dispersant and carrier component obtained in S2 are placed in a high-speed shear mixer and mixed for 20-40 minutes at a speed of 1000-2000 rpm under inert gas protection.

[0018] S4. Aging and Packaging: After aging the well-mixed product for 24 hours, vacuum pack it.

[0019] The cement strength enhancer described in this invention is used in general-purpose silicate cement or sulfoaluminate cement concrete at a dosage of 0.5-1.5% of the total mass of cement materials.

[0020] The core innovation of this invention lies in the creative design and preparation of a biomimetic mineralization-modified nanocomposite core component, which constitutes the cornerstone of the entire synergist's efficacy. Its innovation is reflected in the modification strategy and mechanism: First, utilizing the principle of mussel biomimicry, a polydopamine (PDA) film is formed on the surface of the primary nanocomposite through a self-polymerization reaction. PDA contains a large amount of catechols and amino functional groups, providing superior surface adhesion and an extremely high reactive platform. This step completely solves the problem of dispersion stability of nanomaterials in cementitious matrices.

[0021] The deeper innovation lies in the subsequent secondary mineralization treatment. This invention does not stop at PDA coating, but further places the PDA intermediate in an environment simulating cement pore solution. Utilizing the strong complexing effect of PDA functional groups on calcium and silicate ions, it induces heterogeneous nucleation and in-situ growth of hydrated calcium silicate (CSH) nanocrystals on their surface. This step cleverly "pre-grows" CSH "seeds" that are completely homogeneous with the cement hydration products.

[0022] The resulting nanocomposite core component is a multifunctional unit with a "core-shell-shell" structure: the core is a nano-SiO2-CSH composite that provides initial activity, the middle layer is a PDA organic layer that provides strong adhesion and buffering, and the outermost layer is a CSH inorganic nanoshell that is completely consistent with the final hydration product. This structure makes it no longer a simple "reactant" or "nucleation site," but a "pre-hydrated," perfectly matched "nucleation template" that can be integrated into the cement hydration system with almost zero barrier, greatly accelerating and optimizing the hydration process, and achieving a leap from "promoting" hydration to "guiding" hydration.

[0023] Beneficial technical effects of the present invention:

[0024] This invention brings about a breakthrough improvement in strength performance. Thanks to the "perfect nucleating seed" effect generated by biomimetic mineralization modification, this synergist can simultaneously and significantly catalyze both early and late hydration reactions. Tests show that after adding this product, the 3-day compressive strength of cement mortar can be increased by more than 50%, and the 28-day compressive strength can be increased by more than 35%, completely resolving the contradiction between early strength and late strength.

[0025] This invention significantly improves the product's applicability and durability. The unique PDA modification layer endows the product with excellent dispersibility and adaptability to different cement chemical compositions, avoiding performance instability caused by fluctuations in cement composition. Simultaneously, the PDA layer itself possesses certain antioxidant properties, potentially benefiting the long-term durability of reinforced concrete.

[0026] This invention offers significant energy-saving and environmental benefits. The extremely high strengthening efficiency means that 10-15% of cement can be saved when preparing concrete of the same strength grade. This not only directly reduces material costs but also significantly reduces carbon emissions during cement production, perfectly aligning with the national green and low-carbon development strategy, resulting in substantial economic and social benefits. Attached Figure Description

[0027] Figure 1 This is a flow chart of the preparation process of the cement strength enhancer of the present invention.

[0028] Figure 2a , 2b 2c is a schematic diagram showing the preparation process and structural evolution of the core component of the biomimetic mineralization modified nanocomposite of this invention. Figure 2a The term "primary composite" refers to a preliminary composite structure formed by loading nano-silica onto the surface of a nanocrystalline nucleus material via a sol-gel method. Here, number 1 represents the nano-silica layer and number 2 represents the nanocrystalline nucleus material (such as nano-calcium silicate). Figure 2bThis indicates a PDA-coated intermediate, which is polymerized at a biomimetic dopamine interface to form a polydopamine (PDA) adhesion layer on the surface of the primary composite, improving dispersibility and reactivity. Here, number 1 represents the nano-silica layer, number 2 represents the nanocrystalline nucleus material (such as nano-calcium silicate), and number 3 represents the polydopamine (PDA) coating layer. Figure 2c This indicates the biomimetic mineralization modified core component, which undergoes secondary mineralization in a simulated cement pore solution, inducing the in-situ growth of hydrated calcium silicate (CSH) nanocrystals on the PDA layer, forming an organic-inorganic hybrid core-shell structure. Here, number 1 represents the nano-silica layer, number 2 represents the nanocrystal core material (such as nano-calcium silicate), number 3 represents the polydopamine (PDA) coating layer, and number 4 represents the hydrated calcium silicate (CSH) shell layer. Detailed Implementation

[0029] Before further describing specific embodiments of the present invention, it should be understood that the scope of protection of the present invention is not limited to the specific embodiments described below; it should also be understood that the terminology used in the embodiments of the present invention is for describing specific embodiments and not for limiting the scope of protection of the present invention. Test methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions or as recommended by the respective manufacturers.

[0030] When numerical ranges are given in the embodiments, it should be understood that, unless otherwise stated in this invention, both endpoints of each numerical range and any value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by those skilled in the art. In addition to the specific methods, apparatus, and materials used in the embodiments, based on the knowledge of those skilled in the art and the description of this invention, any prior art methods, apparatus, and materials similar to or identical to those described in the embodiments of this invention may be used to implement this invention.

[0031] Unless otherwise stated, the test methods, detection methods and preparation methods disclosed in this invention all adopt conventional techniques in this technical field.

[0032] Example 1

[0033] 100g of nano-calcium silicate was dispersed in 1000mL of deionized water and sonicated for 30 minutes. Then, 250g of nano-silica sol (SiO2 mass fraction 20%) was slowly added under mechanical stirring. The pH was adjusted to 10.5 with 1M NaOH solution, and the mixture was reacted in an 80℃ water bath for 3 hours. After filtration, washing, and drying at 105℃ for 12 hours, the mixture was ground to obtain a primary composite powder. 20g of this powder was dispersed in 1000mL of Tris-HCl buffer solution (pH=8.5), and 1g of dopamine hydrochloride was added. The mixture was stirred at room temperature for 20 hours. After centrifugation, washing with water and ethanol, and drying, a PDA-coated intermediate was obtained. 10g of this intermediate was then dispersed in 1000mL of saturated Ca(OH)2 solution, and 50mL of 0.5M NaOH solution was added. A Na2SiO3·9H2O solution was reacted at 70℃ for 8 hours, filtered, washed with ethanol, and vacuum dried at 60℃ to obtain a biomimetic mineralized modified nanocomposite core component. Finally, 15% of this core component, 15% of anhydrous sodium sulfate, 1.0% of triisopropanolamine, 0.8% of polycarboxylate superplasticizer powder, and 68.2% of ultrafine fly ash microspheres (specific surface area 500 m² / kg) were mixed at high speed of 1500 rpm for 30 minutes under nitrogen protection, aged for 24 hours, and then vacuum packaged to obtain a cement strength enhancer.

[0034] Example 2

[0035] 100g of nano-calcium silicate was dispersed in 500mL of deionized water, ultrasonically treated, and then nano-silica sol containing 25g of SiO2 (SiO2 to nanocrystalline nucleus material mass ratio 1:4) was added. The pH was adjusted to 10.0, and the mixture was reacted at 75℃ for 4 hours to obtain a primary composite powder. 20g of this powder was dispersed in 400mL of Tris-HCl buffer solution, and 0.4g of dopamine hydrochloride (mass ratio 1:50) was added. The mixture was reacted at room temperature for 24 hours to obtain a PDA-coated intermediate. 10g of this intermediate was dispersed in 500mL of saturated Ca(OH)2 solution for a secondary mineralization reaction. Finally, the mixture was prepared by mixing the following proportions under nitrogen protection: 10% core component, 10% anhydrous sodium sulfate, 0.8% triisopropanolamine, 0.5% polycarboxylate superplasticizer powder, and 78.7% ultrafine fly ash microspheres at 1000 rpm for 40 minutes. After aging, the final product was obtained.

[0036] Example 3

[0037] 100g of nano-calcium silicate was dispersed in 1500mL of deionized water, and nano-silica sol containing 100g of SiO2 (mass ratio 1:1) was added. The pH was adjusted to 11.0, and the mixture was reacted at 85℃ for 2 hours to prepare a primary composite powder. 20g of this powder was dispersed in 2000mL of Tris-HCl buffer, and 2g of dopamine hydrochloride (mass ratio 1:10) was added. The mixture was reacted at room temperature for 18 hours. 10g of PDA intermediate was dispersed in 2000mL of simulated cement pore solution (containing 0.3M KOH, 0.1M NaOH, and 0.05M CaSO4). The mixture was reacted in saturated Ca(OH)2 at 80°C for 6 hours. Finally, the mixture was prepared by mixing the following proportions: 25% core component, 20% anhydrous sodium sulfate, 2.0% triisopropanolamine, 1.5% polycarboxylate superplasticizer powder, and 51.5% ultrafine fly ash microspheres at 2000 rpm for 20 minutes under argon protection. After aging, the product was obtained.

[0038] Example 4

[0039] The preparation process is exactly the same as in Example 1. The only difference is that in the secondary mineralization step, a mixed solution containing 0.3M KOH, 0.1M NaOH, 0.05M CaSO4 and saturated Ca(OH)2 (simulating the solution in real cement pores) is used instead of pure saturated Ca(OH)2 solution. All other formulation parameters and process conditions, including the core component 15%, are completely consistent with those in Example 1.

[0040] Comparative Example 1 (without biomimetic mineralization modification)

[0041] After preparing the primary composite powder according to the exact same method and parameters as in Example 1, the entire biomimetic mineralization modification step was omitted. 15 kg of the primary composite powder was directly taken as the core component and mixed with 15 kg of anhydrous sodium sulfate, 1.0 kg of triisopropanolamine, 0.8 kg of polycarboxylate superplasticizer powder and 68.2 kg of ultrafine fly ash microspheres at a high speed of 1500 rpm for 30 minutes under nitrogen protection. After aging for 24 hours, the mixture was vacuum packaged to obtain the comparative sample.

[0042] Comparative Example 2 (PDA coating only, no secondary mineralization)

[0043] After preparing the primary composite powder and coating it with PDA to obtain the PDA@ intermediate according to the exact same method and parameters as in Example 1, the secondary mineralization step was omitted, and 15 kg of the PDA@ intermediate was directly taken as the core component. Its ratio with the other components and the subsequent mixing, aging and packaging processes were exactly the same as in Example 1, and a comparative sample was obtained.

[0044] Comparative Example 3 (Conventional silane modification)

[0045] After preparing the primary composite powder according to the exact same method and parameters as in Example 1, surface modification was performed using the traditional silane coupling agent KH-550: 20g of the primary composite was dispersed in 400mL of ethanol / water (90 / 10, v / v) mixture, 2g of KH-550 was added, and the mixture was refluxed at 80℃ for 4 hours. After washing and drying, silane-modified powder was obtained. 15kg of this powder was taken as the core component, and its ratio with the other components and subsequent mixing, aging, and packaging processes were exactly the same as in Example 1 to obtain a comparative sample.

[0046] Comparative Example 4 (Simple Physical Mixture)

[0047] Without any chemical modification, 10 kg of ordinary nano-silica powder and 5 kg of ordinary nano-calcium silicate powder were directly weighed and simply physically dry-mixed. This 15 kg mixture was used as the core component. The ratio of this mixture to 15 kg of anhydrous sodium sulfate, 1.0 kg of triisopropanolamine, 0.8 kg of polycarboxylate superplasticizer powder and 68.2 kg of ultrafine fly ash microspheres, as well as the subsequent process of high-speed shear mixing at 1500 rpm for 30 minutes under nitrogen protection, aging for 24 hours, and vacuum packaging, were exactly the same as in Example 1, and a comparative sample was obtained.

[0048] Comparative Example 5 (Simulating Existing Technology)

[0049] Referring to the patent scheme CN100445231C, all components were mixed in a conventional drum mixer for 30 minutes to obtain a comparative sample.

[0050] Performance testing

[0051] Testing standard: Tests were conducted according to GB / T 17671-1999 "Test Method for Strength of Cement Mortar (ISO Method)". The synergist dosage in all examples and comparative examples was 1.0% of the cement material mass. Compressive strength was tested at 3 days and 28 days.

[0052] Table 1 shows the cement strength test results when a cement strength enhancer prepared according to various embodiments and comparative examples of the present invention is added to cement.

[0053]

[0054] As shown in Table 1 above, Example 1 (optimal parameters) exhibits the best enhancement effect. The key lies in the optimal balance of parameters: a 1:2 SiO2 / nanocrystalline nucleus material ratio provides sufficient active SiO2 without over-covering the nucleation sites of nano-CSH; a 1:20 dopamine addition ratio ensures a complete and dense PDA coating layer, providing an ideal platform for subsequent mineralization; and a 1:100 secondary mineralization solid-liquid ratio guarantees the optimal combination of ion concentration and mass transfer efficiency, successfully constructing a large number of highly active CSH "seeds." Example 2 (lower parameter limit) shows slightly inferior performance due to relatively insufficient active components and potentially incomplete coating and mineralization. Example 3 (upper parameter limit), although with sufficient active components, may have reduced reaction efficiency due to an excessively high solid-liquid ratio, and the excessively high addition of small components may have subtle effects on other system properties; therefore, its strength is slightly lower than Example 1. Example 4 uses a complex simulated pore solution, whose ionic environment is closer to that of real cement paste, resulting in a more compatible CSH shell; therefore, its performance is comparable to or even slightly better than Example 1.

[0055] The performance differences between the examples and comparative examples stem from the different fundamental mechanisms of action. The core innovation of this invention lies in constructing an organic-inorganic hybrid "pre-hydration nucleation seed" through a biomimetic strategy of "PDA coating + secondary mineralization". The core component in Example 1 has an outermost layer of nano-CSH that is completely consistent with the crystal structure and chemical properties of cement hydration products. It can induce heterogeneous nucleation of hydration products on its surface with almost zero potential barrier, greatly accelerating the hydration process and optimizing the microstructure of hydration products, thereby achieving a leap in strength.

[0056] Despite exhibiting nano-effects, the primary composite in Comparative Example 1 (unmodified) showed severe particle aggregation and surface properties incompatible with CSH, resulting in low nucleation efficiency. Comparative Example 2 (PDA coating only) solved the dispersibility problem, and the PDA layer could adsorb calcium ions, but it lacked the crucial crystal template homologous to the hydration products, failing to effectively guide the orderly and rapid growth of the hydration products. Comparative Example 3 (silane modification) represented a traditional modification method. While silane molecules improved dispersibility, the resulting long-chain organic barrier could even hinder ion exchange and nucleation. Furthermore, its interface compatibility with CSH was far inferior to that of PDA, making its effect far less effective than biomimetic modification.

[0057] Comparative Example 4 (physical mixing) suffers from severe nanoparticle aggregation and a lack of synergistic effects between components, resulting in negligible nanoparticle advantages. Comparative Example 5 (existing technology) represents the traditional approach of physical mixing and salt-induced coagulation. Its enhancement mechanism is limited to increasing the liquid phase ion concentration and promoting early C3S hydration, failing to fundamentally affect later strength, and the high alkali content poses potential risks.

[0058] In conclusion, the performance differences between the embodiments and comparative examples are not simply quantitative changes, but rather qualitative changes caused by the unique, non-obvious biomimetic mineralization modification of this invention. This fully demonstrates its outstanding substantive features and significant technological advancements.

[0059] Finally, it should be noted that the above embodiments are used to illustrate the technical solutions of the present invention and not to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A cement strength enhancer, characterized in that, It is made of the following components by weight percentage: 10-25% of the biomimetic mineralization modified nanocomposite core component, 10-20% of the early strength component, 0.5-2.5% of the interface strengthening component, 0.2-1.5% of the polymeric dispersant, and the balance is the carrier component; The biomimetic mineralization modified nanocomposite core component is prepared by biomimetic dopamine interfacial polymerization and secondary mineralization treatment; the primary composite of the nanocomposite core component is composed of nano-silica and nano-crystal nucleus material by sol-gel method, wherein the nano-crystal nucleus material is nano-sized calcium silicate. The preparation steps of the primary composite of the nanocomposite core component are as follows: the nanocrystalline nucleus material is dispersed in deionized water at a solid-liquid ratio of 1g:(5-15)mL, and nano-silica sol is slowly added under stirring conditions, wherein the mass ratio of silica in the nano-silica sol to the nanocrystalline nucleus material is 1:(4-1), and the pH of the system is adjusted to 10-11 with alkaline solution, and the reaction is carried out at 75-85℃ for 2-4 hours; after cooling, the mixture is filtered, washed, and dried to obtain the primary composite powder. The preparation steps of the biomimetic mineralization modified nanocomposite core component are as follows: The primary composite is dispersed in Tris-HCl buffer solution with a pH of 8.5 at a solid-liquid ratio of 1g:(20-100)mL, and then dopamine hydrochloride is added at a mass ratio of 1:(10-50) to the primary composite. The mixture is stirred and reacted at room temperature for 18-24 hours to coat the surface of the primary composite with polydopamine. After washing and drying, a polydopamine-coated intermediate is obtained. Then, this intermediate is dispersed in a simulated cement pore solution containing calcium ions and silicates at a solid-liquid ratio of 1g:(50-200)mL and reacted at 60-80℃ for 6-12 hours to induce the in-situ growth of hydrated calcium silicate crystals on its surface. After washing and drying, the final product is obtained. The simulated cement hole solution is a saturated calcium hydroxide solution or a solution containing potassium. + Na + Ca 2+ SO4 2- A mixed solution of ions; The early strength component is anhydrous sodium sulfate; the interface strengthening component is triisopropanolamine; The carrier component has a specific surface area of ​​not less than 450 m². 2 / kg of ultrafine fly ash microspheres.

2. The cement strength enhancer according to claim 1, characterized in that: The polymeric dispersant is a polycarboxylate-based water-reducing agent powder.

3. A method for preparing the cement strength enhancer as described in claim 1 or 2, characterized in that, Includes the following steps: S1. Preparation of primary composite: Disperse nanocrystalline nuclei in deionized water at a solid-liquid ratio of 1g:(5-15)mL, slowly add nano-silica sol under stirring, wherein the mass ratio of silica in the nano-silica sol to nanocrystalline nuclei is 1:(1-4), adjust the pH of the system to 10-11 with alkaline solution, and react at 75-85℃ for 2-4 hours; after cooling, filter, wash, and dry to obtain the primary composite; S2. Biomimetic mineralization modification: The primary composite obtained in S1 is coated with polydopamine and subjected to secondary mineralization treatment to obtain the modified nanocomposite core component; the polydopamine coating is carried out by dispersing the primary composite in Tris-HCl buffer solution with a pH of 8.5 at a solid-liquid ratio of 1g:(20-100)mL, adding dopamine hydrochloride at a mass ratio of 1:(10-50) to the primary composite, stirring and reacting at room temperature for 18-24 hours, and washing and drying after the reaction; the secondary mineralization treatment is carried out by dispersing the coated intermediate in simulated cement pore solution at a solid-liquid ratio of 1g:(50-200)mL, reacting at 60-80℃ for 6-12 hours, and washing and drying after the reaction; S3. Homogenization and compounding: According to the formula, the modified core component, early strength component, interface strengthening component, polymer dispersant and carrier component obtained in S2 are placed in a high-speed shear mixer and mixed for 20-40 minutes at a speed of 1000-2000 rpm under inert gas protection. S4. Aging and Packaging: After aging the well-mixed product for 24 hours, vacuum pack it.

4. The application of a cement strength enhancer as described in claim 1 or 2, characterized in that: Its dosage is 0.5-1.5% of the total mass of cement materials, and it is used in general-purpose silicate cement or sulfoaluminate cement concrete.

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