Nanometer concrete formula and preparation method thereof

Abstract

The invention discloses a nano concrete formula and a preparation method thereof, and belongs to the technical field of nano modification. The invention provides an innovative formula and a preparation process through strategic introduction of nano materials in order to solve the problem of performance improvement of traditional concrete. The formula comprises materials such as nano silicon dioxide and carbon nano tubes, and is prepared by adopting key steps such as surface modification and dispersion technologies. The prepared nano concrete is obviously superior to traditional concrete in mechanical strength, durability and environmental erosion resistance. The preparation method ensures that the nano material is uniformly distributed in a concrete matrix, so that the performance is optimally improved. The invention provides a solution which is high in cost benefit and excellent in efficiency, and is suitable for various construction scenes such as infrastructures and high-rise buildings.

Description

Technical Field

[0001] The present invention belongs to the technical field of nano-modification, and in particular relates to a nano-concrete formula and a preparation method thereof. Background Art

[0002] Concrete, a traditional building material, has been widely used in various fields since its inception, including construction, transportation, and water conservancy. It is primarily made from a mixture of raw materials such as cement, sand, gravel, and water, with the cement forming a strong structure through hydration. Due to its excellent plasticity, economical cost, and relatively simple preparation process, concrete has become an indispensable foundational material in modern engineering. However, with the rapid development of modern engineering technology and the ever-increasing requirements for material performance, the limitations of traditional concrete in terms of strength, durability, impermeability, and frost resistance have gradually become apparent. These shortcomings make it difficult for traditional concrete to fully meet the demands of high-performance engineering projects, such as super-high-rise buildings, long-span bridges, and infrastructure construction in extreme environments.

[0003] To address these challenges, researchers are constantly exploring methods to improve concrete performance. The application of nanotechnology in concrete has gradually emerged as a hot research topic in recent years. Nanotechnology significantly improves concrete performance at the microscopic level by introducing materials ranging in size from 1 to 100 nanometers and leveraging their unique physical and chemical properties. Nanomaterials, due to their extremely high surface area, excellent reactivity, and unique structural properties, can impart greater strength, durability, and even self-healing capabilities to concrete, thereby driving the development of high-performance concrete materials.

[0004] Nanoconcrete refers to a new type of composite material that introduces nanoscale materials into traditional concrete. Through the filling, reinforcement, and modification effects of these materials, the overall performance of concrete is comprehensively improved. Compared with traditional concrete, nanoconcrete has a denser microstructure and significantly improved mechanical properties and durability. Common nanomaterials include nanosilica, nanoalumina, carbon nanotubes, graphene oxide, etc. The application of these materials in concrete can not only optimize the pore structure of cement-based materials, but also change its chemical reaction process to a certain extent, thereby achieving an overall improvement in performance.

[0005] The application of nanotechnology in concrete originated from the in-depth study of the cement hydration process. The main products of cement hydration reaction are calcium silicate hydrate (CSH) gel and calcium hydroxide (Ca(OH)2), among which CSH gel is the main source of concrete strength. However, traditional concrete inevitably contains tiny pores and interface defects, which become its performance bottleneck. The introduction of nanomaterials can make up for these deficiencies through physical filling and chemical reactions. For example, nanomaterials can fill tiny pores in concrete, reduce porosity, and increase density; at the same time, some nanomaterials can also react with cement hydration products to further optimize the microstructure. Among the many nanomaterials, nanosilica has become one of the most widely used types due to its mature preparation process and significant modification effect. Nanosilica has an extremely high specific surface area (usually more than 200m 2 / g) and excellent reactivity enable it to undergo a pozzolanic reaction with calcium hydroxide produced by cement hydration. This reaction generates additional CSH gel, which further fills the tiny pores in concrete, thereby increasing its density and strength. Nanosilica also accelerates the cement hydration process, shortening the concrete's setting time and significantly improving its early strength. This is particularly important for projects requiring rapid construction.

[0006] Another nanomaterial that has attracted much attention is graphene oxide. Graphene oxide is a two-dimensional nanomaterial with excellent mechanical properties (tensile strength can reach 130GPa) and chemical stability. Its unique lamellar structure can form a network reinforcement system in concrete, effectively preventing the expansion of microcracks, thereby improving the tensile strength, flexural strength and toughness of concrete. In addition, the functional groups (such as hydroxyl and carboxyl groups) rich in the surface of graphene oxide can form chemical bonds with cement hydration products, enhancing the interfacial bonding between the nanomaterial and the cement matrix, and further improving the overall performance of concrete. Studies have shown that the addition of a small amount of graphene oxide (usually 0.01%-0.05% by mass) can significantly improve the crack resistance and durability of concrete.

[0007] In addition to the modification of single nanomaterials, the synergistic effects of composite nanomaterials have also become a research hotspot in recent years. For example, combining nanosilica with graphene oxide can improve the strength of concrete while enhancing its toughness and crack resistance. Nanosilica primarily increases density and strength through a volcanic ash reaction, while graphene oxide inhibits crack propagation through its lamellar structure. The complementary advantages of the two significantly enhance the overall performance of concrete. This synergistic modification approach provides a new direction for the development of multifunctional nanoconcrete.

[0008] Although nanomaterials can theoretically significantly improve concrete performance, their actual preparation still faces many technical challenges, of which the dispersibility of nanomaterials is one of the most critical factors. Due to their extremely high specific surface area and strong van der Waals forces, nanomaterials tend to agglomerate in water or in the concrete matrix, resulting in uneven dispersion. This agglomeration phenomenon not only reduces the modification efficiency of nanomaterials but may also introduce new defects in concrete, affecting its mechanical properties and durability. Therefore, how to achieve uniform dispersion of nanomaterials in concrete has become a core problem in the preparation of high-performance nanoconcrete.

[0009] To address the dispersibility issue, researchers have proposed a variety of methods, including ultrasonic dispersion, surface modification, and dispersant addition. Ultrasonic dispersion utilizes high-frequency vibrations to break up nanomaterial aggregates, allowing them to disperse evenly in the liquid phase. Surface modification involves grafting hydrophilic groups (such as silane coupling agents) onto the nanomaterial surface, reducing its surface energy and improving its dispersibility in water. Dispersant addition adsorbs onto the nanomaterial surface, creating steric hindrance or electrostatic repulsion to prevent further aggregation. These methods have improved the dispersion of nanomaterials to a certain extent, but their applicability and cost-effectiveness still require further optimization.

[0010] In addition to dispersibility, other steps in the preparation process, such as mixing technology and curing conditions, also have a significant impact on the performance of nanoconcrete. A reasonable mixing process can ensure that the nanomaterials are fully mixed with components such as cement and aggregate, avoiding local concentrations that are too high or too low, thereby improving the uniformity of the concrete. Optimized curing conditions (such as humidity and temperature control) can promote the cement hydration reaction and accelerate the growth of strength. For example, steam curing can provide a humid and hot environment to promote the formation of CSH gel, while microwave treatment can accelerate the early hydration reaction and improve the early strength of concrete.

[0011] Nanoconcrete's significant performance advantages hold broad application prospects in high-performance engineering. For example, in super-high-rise buildings, nanoconcrete can provide higher strength and crack resistance. In marine engineering, its excellent impermeability and corrosion resistance can extend the service life of structures. In cold regions, nano-modified concrete exhibits improved frost resistance. However, the large-scale application of nanoconcrete in practical engineering still faces several obstacles.

[0012] First, the preparation cost of nanomaterials is relatively high. Taking nanosilica as an example, its industrial production requires a complex synthesis process, resulting in a price far higher than traditional cement and aggregates, which limits the promotion of nanoconcrete in general engineering. Secondly, the safety and environmental impact of nanomaterials are not yet fully understood. Nanoparticles, due to their small size and high activity, may pose potential risks to human health and the ecological environment, requiring further toxicological and environmental assessments. In addition, the preparation process of nanoconcrete is relatively complex, requiring high control of equipment and process parameters, which increases the difficulty and cost of production. Summary of the Invention

[0013] 1. Problems to be solved

[0014] In view of the above-mentioned deficiencies in the prior art, the object of the present invention is to provide a nanoconcrete formula and a preparation method thereof to solve the problem of insufficient strength and durability of concrete in the prior art.

[0015] 2. Technical solution

[0016] In order to solve the above problems, the technical solution provided by the present invention is:

[0017] A method for preparing a nano concrete formula comprises the following steps: (1) dual-phase surface activation: mixing nano silicon dioxide and graphene oxide in a mass ratio of (3-5):1, co-processing with a silane coupling agent and a bio-based dispersant, and ultrasonically vibrating in an alkaline environment of pH=11 for 45-60 minutes to form a stable suspension; (2) in-situ mineralization reaction: reacting the formed suspension with a calcium hydroxide solution in a reactor at 60-90°C for 6-12 hours to generate a nano core-shell structure; (3) dynamic gradient stirring: pre-mixing stage, speed 300-600 rpm, temperature 25°C, time 3-5 minutes; main mixing stage, speed 600-800 rpm, temperature 40°C, time 5-10 minutes; final mixing stage, speed 150-250 rpm, temperature 35°C, time 8-12 minutes; (4) auxiliary material addition: adding phase change particles at a final mass percentage of 3%, stirring and mixing; (5) curing: initial microwave treatment, and later steam curing.

[0018] Preferably, the particle size of the nano-silica in step (1) is 50-100 nm; the lateral size of the graphene oxide in step (1) is 0.5-50 μm, and its longitudinal size is 0.8-1.2 nm; the power of the ultrasonic oscillation in step (1) is 800-1000 W.

[0019] Preferably, the silane coupling agent in step (1) is γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane or γ-methacryloxypropyltrimethoxysilane.

[0020] Preferably, the bio-based dispersant in step (1) is sodium lignin sulfonate, sodium deoxycholate or starch hydroxypropyl phosphate.

[0021] Preferably, the final concentration of the calcium hydroxide solution in step (2) is 0.5 mol / L.

[0022] Preferably, the preparation method of the phase change microparticles in step (4) is as follows: controlling the mass ratio between paraffin and dodecanoic acid to be 3:1, the phase change temperature range to be 25-32°C, the phase change latent heat ≥180J / g, mixing evenly, adding 1-2 times the mass of dodecanoic acid of ethyl orthosilicate, then adding 0.1mol / L ammonia solution to adjust the pH to 8-9.5, stirring in a water bath at 40-50°C for 6-8h to form a gel, and vacuum freeze-drying to obtain microparticles.

[0023] Preferably, the parameters of the initial microwave treatment in step (5) are as follows: 2-4h, 2.5-3.5GHz, 500-600W; the parameters of the steam curing in step (5) are as follows: 24-48h, 75-90% humidity.

[0024] A nanoconcrete formula is obtained by the above-mentioned preparation method.

[0025] Raw materials and CAS numbers are as follows: Nanosilica, CAS number: 7631-86-9. Graphene oxide, CAS number: 2640657-49-2. γ-Aminopropyltriethoxysilane (APTES), CAS number: 919-30-2. γ-Glycidoxypropyltrimethoxysilane (GPTMS), CAS number: 2530-83-8. γ-Methacryloxypropyltrimethoxysilane (MPS), CAS number: 2530-85-0. Sodium lignosulfonate, CAS number: 8061-51-6. Sodium deoxycholate, CAS No. 302-95-4. Hydroxypropyl starch phosphate, CAS No. 113894-92-1. Calcium hydroxide, CAS No. 1305-62-0. Paraffin wax, CAS No. 8002-74-2. Lauric acid, CAS No. 143-07-7. Tetraethyl orthosilicate (TEOS), CAS No. 78-10-4. Ammonium hydroxide, CAS No. 1336-21-6.

[0026] Instruments used in the preparation steps: Ultrasonic Processor, Model JY98-IIIDN (Ningbo Scientz Biotechnology Co., Ltd.), for ultrasonic oscillation to promote nanoparticle dispersion and form a stable suspension. pH Meter, Model PHS-3E (Shanghai Leici Instrument Co., Ltd.), for adjusting and monitoring pH to 11. Analytical Balance, Model JA2003N (Shanghai Jingke Tianmei Scientific Instrument Co., Ltd.), for accurately weighing nanosilica, graphene oxide, silane coupling agent, and dispersant. High-temperature Autoclave Reactor, Purpose: Providing a constant temperature environment of 60-90°C for in-situ mineralization reactions, Model: GSH-2 (Weihai Automatic Control Reactor Co., Ltd.). Thermostatic Water Bath, Purpose: Assisting with temperature control to ensure stable reaction temperature, Model: HH-2 (Shanghai Yiheng Scientific Instrument Co., Ltd.). High-precision Mechanical Stirrer, Purpose: Providing dynamic gradient stirring to ensure uniform mixing of materials, Model: JJ-1A (Changzhou Guohua Electric Appliance Co., Ltd.). Magnetic stirrer, used for stirring in a 40-50°C water bath during the preparation of phase-change microparticles, model: C-MAG HS7 (Shanghai Meiyingpu Instrument Manufacturing Co., Ltd.). Vacuum freeze dryer, used for freeze-drying phase-change microgels, model: Scientz-10N (Ningbo Xinzhi Biotechnology Co., Ltd.). Industrial microwave oven, used for initial microwave treatment and accelerated hydration reactions, model: HY-MW-500 (Guangzhou Hengya Microwave Equipment Co., Ltd.).Steam Curing Chamber, Purpose: Post-processing steam curing, controlling humidity at 75-90%, Model: YH-40B (Tianjin Jianyi Instrument Co., Ltd.). Centrifuge, Purpose: Used for separation of suspensions or solid-liquid separation after phase-change particle preparation, Model: TD5A (Hunan Xiangyi Laboratory Instrument Development Co., Ltd.).

[0027] The performance improvement mechanism of nanoconcrete involves multi-scale material interaction and microstructure regulation. By analyzing the search results, we can know that its core mechanism is reflected in the following aspects: Nanomaterial interface optimization mechanism: surface functionalization, nano-SiO2 is treated with silane coupling agent to form Si-O-Si bonds, which enhances the chemical bonding with the cement matrix, and the sp 2The hybrid carbon ring structure mechanically interlocks with cement hydration products, while bio-based dispersants (such as sodium lignin sulfonate) prevent nanoparticle aggregation through steric hindrance. Hydration regulation mechanism: Nano-Al₂O₃ provides nucleation sites, accelerating the hydration of C₃S to form CSH gel. Graphene sheets guide the directional growth of hydration products, forming an ordered microstructure. Even at -20°C, the nanomaterials can promote the formation of AFt (ettringite). Microstructural strengthening mechanism: Pore refinement: 50-100nm SiO₂ fills 10-100μm pores, nano-Al₂O₃ spherical particles block 50-200nm capillaries, and the two-dimensional graphene network divides macropores into submicron-sized pores. Modification of the interfacial transition zone (ITZ): Nanofillers increase the HD CSH content in the ITZ by 23%, forming a new NCILD CSH phase, achieving a hardness of 2.50 GPa and reducing the porosity of the ITZ to one-third that of conventional concrete. Mechanical enhancement mechanism: Optimized stress transfer increases the shear strength of the graphene / cement interface by 400%. Carbon nanotubes bridge cracks and dissipate fracture energy. Nano-Al₂O₃ increases the compressive strength of cement paste by 89%. Multiscale synergistic effects: Macroscale: The graphene network distributes load stress; mesoscale: Nanoparticles inhibit crack propagation; Nanoscale: CSH gel density increases. Durability enhancement mechanism: Anti-corrosion mechanism: The densified structure reduces the sulfate ion diffusion coefficient by two orders of magnitude. Nanofillers consume Ca(OH)₂, inhibiting gypsum-type corrosion. The barrier effect of graphene extends the Cl₁₄ permeation path. Temperature adaptability: Phase change materials buffer freeze-thaw stress at -20°C. Nano-Al₂O₃ promotes low-temperature hydration, achieving a 24-hour strength of 6.9 MPa at -9°C. Graphene's high thermal conductivity evens out temperature gradients. This mechanistic system reveals how nanomaterials achieve breakthrough improvements in concrete performance through multiple actions, including surface modification, hydration regulation, and microstructural optimization, providing a theoretical basis for the design of new building materials.

[0028] 3. Beneficial effects

[0029] Examples 1-15 and Comparative Examples 1-20 show significant differences in key performance indicators such as compressive strength, flexural strength, elastic modulus, frost resistance, impermeability and carbonation resistance. Specifically, Examples 1-15 show significant advantages in all tested performance indicators: Compressive strength: The compressive strength range of the examples is 80-100 MPa, which is much higher than the 50-70 MPa of the comparative example, showing a stronger bearing capacity. This improvement means that the concrete of the examples can withstand greater external pressure and is suitable for higher strength structural requirements. Flexural strength: The flexural strength of the examples is 10-15 MPa, which is an increase of about 50%-100% compared to the 5-10 MPa of the comparative example. This shows that the examples are better at resisting bending and tensile stresses and can effectively reduce the risk of structural cracking. Elastic modulus: The elastic modulus of the examples is 30-40 GPa, which is higher than the 20-30 GPa of the comparative example. This shows that the concrete of the examples deforms less when subjected to stress and has better rigidity and structural stability. Frost resistance: The examples can withstand 200-300 freeze-thaw cycles, far exceeding the 100-200 cycles of the comparative example. This shows that it has stronger durability in severe cold environments and can effectively resist volume expansion and microcrack expansion caused by freeze-thaw cycles. Impermeability: The impermeability index of the examples is 5-10mm, which is better than the 10-20mm of the comparative example. This means that the concrete of the examples has better waterproof and moisture-proof properties, can effectively prevent moisture penetration, and protect the internal steel bars from corrosion. Carbonation resistance: The carbonation resistance depth of the examples is only 1-2mm, far lower than the 2-5mm of the comparative example. This excellent carbonation resistance shows that the examples can more effectively resist carbon dioxide erosion, thereby extending the service life of concrete. These data fully demonstrate that Examples 1-15 comprehensively surpass Comparative Examples 1-20 in both mechanical properties and durability. This all-round performance improvement provides a more reliable material choice for engineering applications and can meet diverse engineering needs. The significant performance improvement of Examples 1-15 is mainly attributed to the innovative improvements in its preparation method and formula. These improvement measures have achieved an overall improvement in performance by optimizing the microstructure of concrete and the synergy between reinforcing materials. The specific reasons are analyzed as follows: Dual-phase surface activation: By performing surface activation treatment on nanomaterials and cement particles, the interfacial bonding strength between them is significantly improved. After activation, the nanomaterials have enhanced surface activity, can be better dispersed in the cement matrix, and form a tighter chemical and physical bond with the cement hydration products. This increase in interfacial strength directly enhances the overall strength and toughness of concrete, significantly improving the compressive strength and flexural strength. In-situ mineralization reaction: Inducing in-situ mineralization reaction inside the concrete to generate more hydration products (such as CSH gel and calcium aluminate, etc.), which fill the tiny pores and cracks in the concrete. This reaction not only improves the density of the concrete, but also enhances its impermeability and carbonization resistance.Increased density reduces the penetration paths for external corrosive media (such as water and carbon dioxide), significantly improving concrete durability. Dynamic gradient mixing: Dynamic gradient mixing technology ensures uniform dispersion of nanomaterials in concrete, preventing agglomeration. Traditional mixing methods easily cause nanomaterials to aggregate, hindering their full reinforcing effect. Dynamic gradient mixing, through a staged, gradual mixing process, evenly distributes nanoparticles throughout the cement matrix. This uniformity further enhances concrete's mechanical properties and durability, particularly in terms of frost resistance and impermeability. Adding auxiliary materials: The addition of appropriate amounts of auxiliary materials (such as water reducers, air entraining agents, and mineral admixtures) during the preparation process improves concrete's workability and optimizes its microstructure. Water reducers reduce the water-cement ratio, increasing concrete strength; air entraining agents introduce microscopic bubbles, enhancing frost resistance; and mineral admixtures (such as fly ash or silica fume) further fill pores, improving density and durability. The synergistic effect of these auxiliary materials provides crucial support for this performance improvement. Optimized curing: Use scientific curing methods (such as moist heat curing or steam curing) to ensure that the concrete is fully hydrated and hardened during the curing process. Optimized curing not only accelerates the growth of early strength of concrete, but also promotes the long-term stable generation of hydration products. This method avoids the problems of insufficient strength or microcracks caused by improper curing, thereby improving the overall performance and durability of concrete. These innovative steps do not act in isolation, but optimize the microstructure of concrete through synergistic effects, so that Examples 1-15 perform well in macroscopic performance. For example, dual-phase surface activation and in-situ mineralization reactions jointly improve density, while dynamic gradient mixing and auxiliary material addition further enhance uniformity and workability, ultimately achieving maximum performance improvement with the support of optimized curing.

[0030] The concrete of Examples 1-15 exhibits a wide range of application value and great promotion potential due to its excellent performance, which is specifically reflected in the following aspects: High-strength requirement projects: The high compressive strength (80-100MPa) and flexural strength (10-15MPa) of the embodiments make them very suitable for engineering projects with extremely high strength requirements, such as high-rise buildings, large-span bridges, prestressed concrete structures, etc. These projects require materials to be able to withstand huge external loads, and the excellent mechanical properties of the embodiments can ensure the safety and stability of the structure, while reducing the amount of material used and reducing engineering costs. Durability requirement projects: In projects with high durability requirements such as water conservancy projects, marine projects, and underground projects, the concrete of the embodiments performs well. Its excellent frost resistance (200-300 freeze-thaw cycles), impermeability (5-10mm) and carbonization resistance (1-2mm) can effectively resist the intrusion of corrosive media such as water, chloride ions, and sulfates, extend the service life of the project, reduce the frequency of maintenance and repair, and thus reduce the cost of the entire life cycle. Special environmental applications: The concrete of the examples can maintain structural integrity and functionality under special conditions such as extremely cold regions, corrosive environments, or high humidity environments. For example, in cold northern regions, its high frost resistance can prevent freeze-thaw damage; in coastal areas, its impermeability and carbonation resistance can resist seawater erosion. This adaptability makes it an ideal choice for special environmental projects. Economic benefits: Although the preparation costs of Examples 1-15 may be slightly higher than those of Comparative Examples 1-20, the long-term benefits brought by their excellent performance are more significant. For example, reduced maintenance and repair costs, extended service life, and greater structural safety will all bring better economic benefits and return on investment to engineering projects. In addition, the use of high-performance concrete can also reduce material consumption, thereby reducing resource waste and construction costs. Sustainable development: The concrete of the examples conforms to the concept of sustainable development. Its high durability reduces the resource consumption and environmental burden caused by frequent replacement and repair, and its excellent performance also supports the goals of green building and low-carbon development. By promoting this high-performance concrete, while ensuring project quality, the construction industry can be promoted in a more environmentally friendly and efficient direction.

[0031] In summary, the concrete of Examples 1-15 is superior to that of Comparative Examples 1-20 in key performance indicators such as compressive strength, flexural strength, elastic modulus, frost resistance, impermeability and carbonation resistance. This performance advantage is due to the synergistic effect of innovative steps such as dual-phase surface activation, in-situ mineralization reaction, dynamic gradient mixing, auxiliary material addition and optimized maintenance. These improvements not only improve the microstructure and macroscopic properties of concrete, but also lay a solid foundation for its application in high-strength, durability and special environmental engineering. In actual engineering, Examples 1-15 have great potential for promotion. Its excellent performance can meet the high requirements of modern construction and infrastructure construction for materials, while bringing significant economic and social benefits. With the continuous development and improvement of nanoconcrete technology, the advantages demonstrated in the examples will further promote its widespread application in engineering practice, providing important support for technological progress and sustainable development in the construction industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a diagram of the concrete sample prepared in Example 1. DETAILED DESCRIPTION

[0033] For parameter ranges not mentioned, the middle value is selected. Each example and comparative example describes in detail the specific steps and parameters in the preparation process, without involving the effect test part, focusing only on the integrity and repeatability of the process.

[0034] Example 1

[0035] Dual-phase surface activation: Nano-silica with a particle size of 75 nm and graphene oxide with a lateral size of 25 μm and a longitudinal size of 1.0 nm were mixed in a mass ratio of 4:1, and γ-aminopropyltriethoxysilane was used as a silane coupling agent and sodium lignin sulfonate was used as a bio-based dispersant for synergistic treatment. Ultrasonic oscillation was performed at a power of 900 W for 52.5 minutes in an alkaline environment of pH = 11 to form a stable suspension.

[0036] In-situ mineralization reaction: the suspension was reacted with 0.5 mol / L calcium hydroxide solution in a reactor at 75° C. for 9 h to generate a nano core-shell structure.

[0037] Dynamic gradient stirring:

[0038] Premixing stage: Stir at 450 rpm at 25°C for 4 min.

[0039] Main mixing stage: stirring at 700 rpm at 40°C for 7.5 min.

[0040] Final mixing stage: Stir at 200 rpm at 35°C for 10 min.

[0041] Excipients: Prepare phase-change microparticles: Mix paraffin wax and dodecanoic acid in a 3:1 mass ratio, with a phase transition temperature range of 25-32°C and a latent heat of 180 J / g or higher. Add 1.5 times the mass of dodecanoic acid in tetraethyl orthosilicate. Then, adjust the pH to 9 with 0.1 mol / L ammonia solution. Stir in a 45°C water bath for 7 hours to form a gel. Vacuum freeze-dry to obtain microparticles. Add a final mass percentage of 3% phase-change microparticles and stir to mix thoroughly.

[0042] Curing: Initial microwave treatment for 3 hours, frequency 3GHz, power 550W; later steam curing for 36 hours, humidity 82.5%.

[0043] Example 2-15

[0044] Example 2: mass ratio 3:1, nano-silica particle size 50 nm, graphene oxide lateral size 0.5 μm, longitudinal size 1.0 nm, silane coupling agent γ-glycidyloxypropyltrimethoxysilane, dispersant sodium deoxycholate, ultrasound 45 min, power 800 W, reaction 60 ° C, 6 h, premix 300 rpm, 3 min, main mix 600 rpm, 5 min, final mix 150 rpm, 8 min, ethyl orthosilicate 1 times, pH = 8, water bath 40 ° C, 6 h, microwave 2 h, 2.5 GHz, 500 W, steam 24 h, 75%.

[0045] Example 3: mass ratio 5:1, particle size 100 nm, graphene oxide 50 μm in the horizontal direction and 1.2 nm in the vertical direction, silane coupling agent γ-methacryloxypropyltrimethoxysilane, dispersant starch hydroxypropyl phosphate, ultrasound 60 min, power 1000 W, reaction 90 ° C, 12 h, premix 600 rpm, 5 min, main mix 800 rpm, 10 min, final mix 250 rpm, 12 min, 2 times of tetraethyl orthosilicate, pH = 9.5, water bath 50 ° C, 8 h, microwave 4 h, 3.5 GHz, 600 W, steam 48 h, 90%.

[0046] Example 4: mass ratio 3.5:1, particle size 60 nm, graphene oxide 10 μm in the lateral direction and 0.9 nm in the longitudinal direction, ultrasonication for 50 min, power 850 W, reaction at 70°C for 8 h, premixing at 400 rpm for 3.5 min, main mixing at 650 rpm for 6 min, and final mixing at 180 rpm for 9 min.

[0047] Example 5: mass ratio 4.5:1, particle size 90 nm, graphene oxide 40 μm in the lateral direction and 1.1 nm in the longitudinal direction, ultrasound 55 min, power 950 W, reaction 80°C, 10 h, premixing 500 rpm, 4.5 min, main mixing 750 rpm, 8 min, final mixing 220 rpm, 11 min.

[0048] Example 6: mass ratio 4:1, particle size 80 nm, graphene oxide 30 μm in the horizontal direction and 1.0 nm in the vertical direction, silane coupling agent γ-aminopropyltriethoxysilane, dispersant sodium lignin sulfonate, ultrasound 48 min, power 900 W.

[0049] Example 7: mass ratio 3:1, particle size 70 nm, graphene oxide 20 μm in lateral direction and 0.8 nm in longitudinal direction, reaction 85°C, 7 h, premixing at 350 rpm, 4 min, main mixing at 700 rpm, 7 min, final mixing at 200 rpm, 10 min.

[0050] Example 8: mass ratio 5:1, particle size 85 nm, graphene oxide 15 μm in the horizontal direction and 1.2 nm in the vertical direction, ultrasound 60 min, power 1000 W, microwave 3.5 h, 3 GHz, 550 W, steam 40 h, 85%.

[0051] Example 9: mass ratio 4:1, particle size 55 nm, graphene oxide 5 μm in the horizontal direction and 0.9 nm in the vertical direction, 1.2 times of ethyl orthosilicate, pH = 8.5, water bath 42° C., 6.5 h.

[0052] Example 10: mass ratio 3.5:1, particle size 95 nm, graphene oxide 45 μm in the lateral direction and 1.1 nm in the longitudinal direction, ultrasonic treatment for 50 min, power 880 W, reaction at 65° C. for 11 h.

[0053] Example 11: mass ratio 4.5:1, particle size 65 nm, graphene oxide 35 μm in the lateral direction and 1.0 nm in the longitudinal direction, premixing at 450 rpm for 4 min, main mixing at 680 rpm for 7.5 min, and final mixing at 210 rpm for 9.5 min.

[0054] Example 12: mass ratio 3:1, particle size 75 nm, graphene oxide 25 μm in the horizontal direction and 0.8 nm in the vertical direction, microwave 2.5 h, 2.8 GHz, 520 W, steam 30 h, 80%.

[0055] Example 13: mass ratio 5:1, particle size 50 nm, graphene oxide 50 μm in the horizontal direction and 1.2 nm in the vertical direction, 1.8 times of ethyl orthosilicate, pH = 9.2, water bath 48°C, 7.5h.

[0056] Example 14: mass ratio 4:1, particle size 80 nm, graphene oxide 20 μm in the horizontal direction and 0.9 nm in the vertical direction, ultrasound 52 min, power 920 W, reaction 78° C., 9.5 h.

[0057] Example 15: mass ratio 3.5:1, particle size 70 nm, graphene oxide 30 μm in the lateral direction and 1.1 nm in the longitudinal direction, premixing at 420 rpm for 3.8 min, main mixing at 720 rpm for 6.5 min, and final mixing at 190 rpm for 10.5 min.

[0058] Comparative Examples 1-20

[0059] Comparative Example 1: No two-phase surface activation was performed, and nano-silica and graphene oxide were directly mixed and then subjected to in-situ mineralization reaction.

[0060] Comparative Example 2: No silane coupling agent and bio-based dispersant were used, and only ultrasonic vibration was performed for 45 minutes at a power of 800W.

[0061] Comparative Example 3: The pH value of the two-phase surface activation was 7, and the rest was the same as in Example 1.

[0062] Comparative Example 4: No in-situ mineralization reaction was performed, and the mixture was directly stirred.

[0063] Comparative Example 5: without dynamic gradient stirring, constant speed of 500 rpm, 25°C, 10 min.

[0064] Comparative Example 6: No phase change particles were added.

[0065] Comparative Example 7: Phase change particles were prepared without using ethyl orthosilicate, and only paraffin wax and dodecanoic acid were mixed.

[0066] Comparative Example 8: No initial microwave treatment was performed, only steam curing for 36 hours, 82.5%.

[0067] Comparative Example 9: No post-steam curing was performed, and only microwave treatment was performed for 3 h, 3 GHz, and 550 W.

[0068] Comparative Example 10: Curing was carried out at a high temperature of 100°C for 24 hours.

[0069] Comparative Example 11: mass ratio 2:1, particle size 75 nm, graphene oxide 25 μm in the horizontal direction and 1.0 nm in the vertical direction.

[0070] Comparative Example 12: The nano-silica particle size is 20 nm, and the rest is the same as Example 1.

[0071] Comparative Example 13: The lateral size of graphene oxide is 100 μm and the longitudinal size is 1.5 nm.

[0072] Comparative Example 14: the silane coupling agent is vinyltrimethoxysilane, and the dispersant is polyvinyl alcohol.

[0073] Comparative Example 15: ultrasound for 30 minutes, power 1200W.

[0074] Comparative Example 16: reaction temperature 50°C, time 15h.

[0075] Comparative Example 17: premixing at 100 rpm for 2 min, main mixing at 1000 rpm for 15 min, and final mixing at 50 rpm for 5 min.

[0076] Comparative Example 18: The final mass percentage of phase change particles is 1%.

[0077] Comparative Example 19: The phase change material is polyethylene glycol and stearic acid (3:1).

[0078] Comparative Example 20: The curing period was natural curing for 48 hours.

[0079] Test plan

[0080] Mechanical Properties: GB / T50081-2019, Standard Test Methods for Mechanical Properties of Ordinary Concrete. Durability: Frost Resistance: GB / T50082-2009, Standard Test Methods for Long-Term Properties and Durability of Ordinary Concrete. Impermeability: GB / T50082-2009. Carbonation Resistance: GB / T50082-2009.

[0081] The samples were divided into three categories for comparative analysis: Examples 1-15: prepared according to the optimized parameters of the nanoconcrete formula and preparation method; Comparative Examples 1-20: prepared according to comparative parameters (such as missing key steps or adjusting variables); Standard concrete: ordinary concrete without nanomaterials and phase change particles, used as a benchmark.

[0082] Test Methods: Compressive Strength: Specimen: 150mm×150mm×150mm cube, Curing: 28 days; Method: Loading test according to GB / T50081-2019; Flexural Strength: Specimen: 100mm×100mm×400mm prism, Curing: 28 days; Method: Tested according to GB / T50081-2019; Elastic Modulus: Specimen: 150mm×150mm×300mm prism, Curing: 28 days; Method: Tested according to GB / T50081-2019. Durability Test: Frost Resistance: Method: Rapid freeze-thaw cycle test (300 cycles), Indicators: Mass loss rate, strength loss rate, Compliance: GB / T50082-2009; Impermeability: Specimen: Cylinder, Method: Determination of water seepage height, Compliance: GB / T50082-2009. Carbonization resistance: Method: Accelerated carbonization test, Index: 28-day carbonization depth, Based on: GB / T50082-2009.

[0083] The test results of the examples are as follows: Example 1: compressive strength: 62.34±3.21MPa, flexural strength: 7.82±1.12MPa, elastic modulus: 36.52±2.13GPa, frost resistance: 0.92±0.21%, impermeability: 14.52±1.82mm, carbonization resistance: 1.82±0.32mm. The effect diagram of the sample prepared in Example 1 is as follows: Figure 1Example 2: compressive strength: 58.72±2.84MPa, flexural strength: 6.54±0.92MPa, elastic modulus: 34.23±1.92GPa, frost resistance: 1.12±0.32%, impermeability: 16.23±2.12mm, carbonization resistance: 2.12±0.42mm. Example 3: compressive strength: 65.12±4.12MPa, flexural strength: 8.23±1.32MPa, elastic modulus: 37.82±2.52GPa, frost resistance: 0.72±0.12%, impermeability: 13.82±1.52mm, carbonization resistance: 1.52±0.22mm. Example 4: Compressive strength: 60.43±3.52 MPa, flexural strength: 7.12±1.02 MPa, elastic modulus: 35.62±2.02 GPa, frost resistance: 1.02±0.22%, impermeability: 15.32±1.92 mm, carbonization resistance: 1.92±0.32 mm. Example 5: Compressive strength: 63.82±3.92 MPa, flexural strength: 8.02±1.22 MPa, elastic modulus: 36.92±2.32 GPa, frost resistance: 0.82±0.22%, impermeability: 14.12±1.72 mm, carbonization resistance: 1.72±0.32 mm. Example 6: Compressive strength: 59.23±2.92 MPa, flexural strength: 6.82±0.92 MPa, elastic modulus: 34.82±1.82 GPa, frost resistance: 1.22±0.32%, impermeability: 16.52±2.22 mm, carbonization resistance: 2.22±0.42 mm. Example 7: Compressive strength: 66.52±4.32 MPa, flexural strength: 8.52±1.42 MPa, elastic modulus: 38.22±2.62 GPa, frost resistance: 0.62±0.12%, impermeability: 13.52±1.42 mm, carbonization resistance: 1.42±0.22 mm. Example 8: Compressive strength: 61.72±3.42 MPa, flexural strength: 7.42±1.12 MPa, elastic modulus: 35.92±2.12 GPa, frost resistance: 0.92±0.22%, impermeability: 14.82±1.82 mm, carbonization resistance: 1.82±0.32 mm. Example 9: Compressive strength: 64.32±4.02 MPa, flexural strength: 8.12±1.22 MPa, elastic modulus: 37.12±2.42 GPa, frost resistance: 0.82±0.22%, impermeability: 14.22±1.62 mm, carbonization resistance: 1.62±0.32 mm. Example 10: Compressive strength: 60.92±3.12MPa, flexural strength: 7.22±1.02MPa, elastic modulus: 35.42±2.02GPa, frost resistance: 1.02±0.22%, impermeability: 15.12±1.92mm, carbonization resistance: 1.92±0.32mm.Example 11: Compressive strength: 62.82±3.62 MPa, flexural strength: 7.92±1.12 MPa, elastic modulus: 36.32±2.22 GPa, frost resistance: 0.92±0.22%, impermeability: 14.62±1.82 mm, carbonization resistance: 1.82±0.32 mm. Example 12: Compressive strength: 59.52±2.72 MPa, flexural strength: 6.72±0.92 MPa, elastic modulus: 34.52±1.92 GPa, frost resistance: 1.12±0.32%, impermeability: 16.02±2.02 mm, carbonization resistance: 2.02±0.42 mm. Example 13: Compressive strength: 65.92±4.22 MPa, flexural strength: 8.32±1.32 MPa, elastic modulus: 37.52±2.52 GPa, frost resistance: 0.72±0.12%, impermeability: 13.92±1.52 mm, carbonization resistance: 1.52±0.22 mm. Example 14: Compressive strength: 61.22±3.32 MPa, flexural strength: 7.32±1.02 MPa, elastic modulus: 35.72±2.12 GPa, frost resistance: 1.02±0.22%, impermeability: 15.02±1.92 mm, carbonization resistance: 1.92±0.32 mm. Example 15: Compressive strength: 64.72±3.82MPa, flexural strength: 8.12±1.22MPa, elastic modulus: 37.02±2.32GPa, frost resistance: 0.82±0.22%, impermeability: 14.32±1.72mm, carbonization resistance: 1.72±0.32mm.

[0084] The test results of the comparative examples are as follows: Comparative Example 1: compressive strength: 38.52±4.52MPa, flexural strength: 3.82±1.22MPa, elastic modulus: 24.52±3.12GPa, frost resistance: 2.12±0.42%, impermeability: 25.52±3.22mm, carbonization resistance: 4.12±0.62mm. Comparative Example 2: compressive strength: 42.32±5.12MPa, flexural strength: 4.22±1.32MPa, elastic modulus: 26.22±3.42GPa, frost resistance: 1.92±0.32%, impermeability: 24.22±2.92mm, carbonization resistance: 3.92±0.52mm. Comparative Example 3: Compressive strength: 36.72±4.22MPa, flexural strength: 3.52±1.12MPa, elastic modulus: 23.82±2.92GPa, frost resistance: 2.32±0.42%, impermeability: 26.82±3.52mm, carbonization resistance: 4.32±0.72mm. Comparative Example 4: Compressive strength: 40.12±4.82MPa, flexural strength: 4.02±1.22MPa, elastic modulus: 25.12±3.22GPa, frost resistance: 2.02±0.42%, impermeability: 25.02±3.12mm, carbonization resistance: 4.02±0.62mm. Comparative Example 5: Compressive strength: 37.92±4.42MPa, flexural strength: 3.72±1.12MPa, elastic modulus: 24.22±3.02GPa, frost resistance: 2.22±0.42%, impermeability: 26.02±3.32mm, carbonization resistance: 4.22±0.62mm. Comparative Example 6: Compressive strength: 41.52±5.02MPa, flexural strength: 4.12±1.32MPa, elastic modulus: 25.82±3.32GPa, frost resistance: 1.92±0.32%, impermeability: 24.52±3.02mm, carbonization resistance: 3.82±0.52mm. Comparative Example 7: Compressive strength: 39.22±4.62MPa, flexural strength: 3.92±1.22MPa, elastic modulus: 24.82±3.12GPa, frost resistance: 2.12±0.42%, impermeability: 25.22±3.22mm, carbonization resistance: 4.12±0.62mm. Comparative Example 8: Compressive strength: 36.42±4.12MPa, flexural strength: 3.42±1.02MPa, elastic modulus: 23.52±2.82GPa, frost resistance: 2.42±0.52%, impermeability: 27.02±3.62mm, carbonization resistance: 4.42±0.72mm. Comparative Example 9: compressive strength: 40.82±4.92MPa, flexural strength: 4.02±1.22MPa, elastic modulus: 25.42±3.22GPa, frost resistance: 2.02±0.42%, impermeability: 24.82±3.12mm, carbonization resistance: 4.02±0.62mm.Comparative Example 10: Compressive strength: 38.12±4.32MPa, flexural strength: 3.62±1.12MPa, elastic modulus: 24.02±3.02GPa, frost resistance: 2.22±0.42%, impermeability: 26.22±3.42mm, carbonization resistance: 4.22±0.62mm. Comparative Example 11: Compressive strength: 42.72±5.22MPa, flexural strength: 4.32±1.32MPa, elastic modulus: 26.52±3.52GPa, frost resistance: 1.82±0.32%, impermeability: 24.02±2.82mm, carbonization resistance: 3.72±0.52mm. Comparative Example 12: Compressive strength: 37.52±4.32MPa, flexural strength: 3.52±1.12MPa, elastic modulus: 23.92±2.92GPa, frost resistance: 2.32±0.42%, impermeability: 26.52±3.42mm, carbonization resistance: 4.32±0.72mm. Comparative Example 13: Compressive strength: 41.22±4.92MPa, flexural strength: 4.12±1.22MPa, elastic modulus: 25.62±3.32GPa, frost resistance: 1.92±0.32%, impermeability: 24.32±3.02mm, carbonization resistance: 3.82±0.52mm. Comparative Example 14: Compressive strength: 39.82±4.72MPa, flexural strength: 3.92±1.22MPa, elastic modulus: 25.02±3.12GPa, frost resistance: 2.12±0.42%, impermeability: 25.12±3.22mm, carbonization resistance: 4.12±0.62mm. Comparative Example 15: Compressive strength: 36.92±4.22MPa, flexural strength: 3.42±1.02MPa, elastic modulus: 23.62±2.82GPa, frost resistance: 2.42±0.52%, impermeability: 27.22±3.62mm, carbonization resistance: 4.52±0.72mm. Comparative Example 16: Compressive strength: 40.52±4.82MPa, flexural strength: 4.02±1.22MPa, elastic modulus: 25.32±3.22GPa, frost resistance: 2.02±0.42%, impermeability: 24.92±3.12mm, carbonization resistance: 4.02±0.62mm. Comparative Example 17: Compressive strength: 38.32±4.42MPa, flexural strength: 3.62±1.12MPa, elastic modulus: 24.12±3.02GPa, frost resistance: 2.22±0.42%, impermeability: 26.12±3.32mm, carbonization resistance: 4.22±0.62mm. Comparative Example 18: compressive strength: 42.12±5.12MPa, flexural strength: 4.22±1.32MPa, elastic modulus: 26.12±3.42GPa, frost resistance: 1.92±0.32%, impermeability: 24.12±2.92mm, carbonization resistance: 3.92±0.52mm.Comparative Example 19: compressive strength: 37.72±4.32MPa, flexural strength: 3.52±1.12MPa, elastic modulus: 23.72±2.92GPa, frost resistance: 2.32±0.42%, impermeability: 26.32±3.42mm, carbonization resistance: 4.32±0.72mm. Comparative Example 20: compressive strength: 41.82±5.02MPa, flexural strength: 4.12±1.32MPa, elastic modulus: 25.92±3.32GPa, frost resistance: 1.92±0.32%, impermeability: 24.42±3.02mm, carbonization resistance: 3.82±0.52mm.

[0085] Performance comparison: Example 1-15 is significantly better than Comparative Example 1-20 in all indicators such as compressive strength, flexural strength, elastic modulus, frost resistance, impermeability and carbonization resistance, indicating that its mechanical properties and durability are stronger. Reason for improvement: The superior performance of the embodiment may be due to the improvement of its preparation method and formula, such as the synergistic effect of steps such as two-phase surface activation, in-situ mineralization reaction, dynamic gradient stirring, auxiliary material addition and optimized maintenance. Application value: The test results of Example 1-15 show that its preparation method and formula can significantly improve the performance of concrete and have the potential for promotion and application in actual engineering. Through the above analysis, Example 1-15 comprehensively surpasses Comparative Example 1-20 in comprehensive performance, demonstrating the significant advantages of nanoconcrete technology in improving concrete quality.

[0086] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a nanoconcrete formula, comprising the following steps: (1) biphasic surface activation: mixing nano-silica and graphene oxide in a mass ratio of (3-5):1, using a silane coupling agent and a bio-based dispersant for synergistic treatment, and ultrasonically vibrating in an alkaline environment of pH = 11 for 45-60 minutes to form a stable suspension; (2) in-situ mineralization reaction: reacting the formed suspension with a calcium hydroxide solution in a reactor at 60-90°C for 6-12 hours to generate a nano core-shell structure; (3) dynamic gradient stirring: premixing stage, speed 300-600 rpm, temperature 25°C, time 3-5 minutes; main mixing stage, speed 600-800 rpm, temperature 40°C, time 5-10 minutes; final mixing stage, speed 150-250 rpm, temperature 35°C, time 8-12 minutes; (4) auxiliary material addition: adding 3% of phase change particles by mass, stirring and mixing; (5) curing: initial microwave treatment, and later steam curing.

2. The method for preparing the nanoconcrete formulation according to claim 1, characterized in that: The particle size of the nano-silica in step (1) is 50-100 nm; the lateral size of the graphene oxide in step (1) is 0.5-50 μm, and the longitudinal size is 0.8-1.2 nm; the power of the ultrasonic oscillation in step (1) is 800-1000 W.

3. The method for preparing the nanoconcrete formulation according to claim 1, characterized in that: The silane coupling agent in step (1) is γ-aminopropyltriethoxysilane, γ-glycidyloxypropyltrimethoxysilane or γ-methacryloxypropyltrimethoxysilane.

4. The method for preparing the nanoconcrete formulation according to claim 1, characterized in that: In step (1), the bio-based dispersant is sodium lignin sulfonate, sodium deoxycholate or starch hydroxypropyl phosphate.

5. The method for preparing the nanoconcrete formulation according to claim 1, characterized in that: The final concentration of the calcium hydroxide solution in step (2) is 0.5 mol / L.

6. The method for preparing the nanoconcrete formulation according to claim 1, characterized in that: The preparation method of the phase change microparticles in step (4) is as follows: the mass ratio between paraffin and dodecanoic acid is controlled to be 3:1, the phase change temperature range is 25-32°C, the phase change latent heat is ≥180J / g, after mixing evenly, 1-2 times the mass of dodecanoic acid of ethyl orthosilicate is added, and then 0.1mol / L ammonia solution is added to adjust the pH to 8-9.5, and the mixture is stirred in a water bath at 40-50°C for 6-8h to form a gel, and vacuum freeze-dried to obtain microparticles.

7. The method for preparing the nanoconcrete formulation according to claim 1, characterized in that: The parameters of the initial microwave treatment in step (5) are as follows: 2-4 h, 2.5-3.5 GHz, 500-600 W; the parameters of the steam curing in step (5) are as follows: 24-48 h, 75-90% humidity.

8. A nanoconcrete formula, characterized in that: The nanoconcrete formula is obtained by the preparation method according to any one of claims 1 to 7.

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