Concrete super-hydrophobic protective coating and preparation method and protection method thereof

Abstract

The invention discloses a concrete super-hydrophobic protective coating which comprises the following components in percentage by mass: 5-10wt% of amine-free porous material, 5-10wt% of inorganic filler and the balance of water. 6-12wt% of PVA (Polyvinyl Alcohol) is coated with 0.4 wt% to 0.6 wt% of an additive; 8 to 15 weight percent of octyl triethoxy silane; 0.6 to 2.2 wt% of nanometer bentonite; 1 to 3 wt% of sodium carboxymethyl cellulose; and the balance deionized water. The invention further provides a corresponding preparation method and a protection method. Carbonization reaction is carried out in the atmosphere, about 5.3 g of carbon can be fixed in each square meter of the coating, and a negative carbon technical path is realized; fluorine-containing substances, amine template agents and ethyl alcohol are not needed in the whole process, water is adopted as a main solvent, n-butyl alcohol can be efficiently recycled, and green chemical principles and environmental protection laws and regulations are met.

Description

Technical Field

[0001] This invention relates to the field of superhydrophobic protective coatings for concrete. More specifically, this invention relates to a superhydrophobic protective coating for concrete, its preparation method, and its protective method. Background Technology

[0002] Concrete is the most widely used building material today, but its porous structure makes it susceptible to the penetration of moisture and corrosive ions (such as chloride ions), leading to steel corrosion and structural deterioration. Superhydrophobic coatings are an effective means of improving concrete durability, but existing technologies have significant drawbacks: 1. High environmental risk: Most high-performance superhydrophobic coatings rely on fluorinated compounds (such as perfluorooctanoic acid, PFOA) to achieve extremely low surface energy. However, these substances are permanent fluorinated compounds (PFAS) and have been strictly restricted or banned in regions such as the EU. Some technologies require the introduction of high-purity... Forced carbonization of gases (as reported in Adv. Mater. 2024) has a high carbon footprint and requires complex equipment, which defeats the purpose of concrete carbon sequestration technology.

[0003] 2. The preparation process is not environmentally friendly: This involves the synthesis of key materials (such as porous materials). Amine template agents (such as CN2017110523593) are often required in the preparation of coatings. Residual amines not only pollute the environment but may also affect the long-term stability of the coating. Preparation of nano-active materials (such as nano-...) In order to control particle size, organic solvents such as ethanol are often used for solvothermal or dehydration treatment (such as CN113480082A), which increases the risk of flammability and explosion and the cost of the production process.

[0004] 3. Poor cost and practicality: Superhydrophobic technology, which relies on expensive raw materials or complex processes, is difficult to promote and apply on a large scale in the field of civil engineering, especially in large-scale infrastructure (such as ports and dams).

[0005] Therefore, it is necessary to develop an environmentally friendly, low-cost, easy-to-construct, and proactively atmospheric technology. The superhydrophobic protection technology for concrete has significant scientific and engineering value. Summary of the Invention

[0006] To achieve these objectives and other advantages according to the invention, a preferred embodiment of the invention provides a superhydrophobic protective coating for concrete, comprising, by weight percentage: 5-10 wt% amine-free porous 6-12wt% PVA-coated nanoparticles 0.4-0.6wt% ; 8-15wt% octyltriethoxysilane; 0.6-2.2wt% nano-bentonite; 1-3wt% sodium carboxymethyl cellulose; balance deionized water.

[0007] The superhydrophobic protective coating for concrete in this embodiment is a water-based coating used for the protection of concrete substrate surfaces. During the film-forming process, the expansion properties of nano-bentonite allow it to fill the tiny voids within the coating, reducing porosity and forming a continuous and dense protective structure. Simultaneously, it enhances the coating's hardness, wear resistance, and impact resistance, preventing cracking and peeling due to external forces. The highly active montmorillonite component in the nano-bentonite can weakly interact with hydroxyl groups and calcium ions on the concrete substrate surface, and also interacts with the PVA-coated nano-bentonite in the coating. The components, such as sodium carboxymethyl cellulose, form a synergistic bond, enhancing the interfacial adhesion between the coating and the concrete substrate, reducing peeling problems caused by environmental changes during long-term use, and extending the protection period.

[0008] Sodium carboxymethyl cellulose is a water-soluble polymer compound that, when dissolved in coatings, forms a viscous, transparent aqueous solution. Its molecular chains can be adsorbed onto amine-free porous materials. PVA-coated nanoparticles A stable dispersion layer is formed on the surface of solid particles, preventing particle sedimentation due to gravity and avoiding problems such as oil-water separation and component stratification during coating storage, thus ensuring the uniformity of the coating system. Furthermore, the molecular chains formed after the water-soluble high-molecular-weight sodium carboxymethyl cellulose dissolves can be adsorbed onto the surface of nano-bentonite particles, hindering particle aggregation through steric hindrance. Simultaneously, the layered structure of nano-bentonite provides attachment sites for sodium carboxymethyl cellulose molecular chains, reducing the free flow of sodium carboxymethyl cellulose in water and preventing localized viscosity unevenness in the coating due to molecular aggregation. These two factors work together to ensure that the coating system remains uniformly dispersed throughout storage and application, without stratification or sedimentation. During film formation, the high-molecular-weight chains of sodium carboxymethyl cellulose intertwine to form a basic membrane framework, and the expanded nano-bentonite particles fill the tiny gaps in this framework, forming a dense "framework-particle filling" structure. On the one hand, the flexibility of sodium carboxymethyl cellulose can alleviate the risk of coating brittleness caused by the rigidity of nano-bentonite; on the other hand, the high specific surface area of ​​nano-bentonite can enhance the mechanical strength of the sodium carboxymethyl cellulose membrane, so that the final protective layer has both good flexibility and excellent wear resistance and impact resistance.

[0009] The superhydrophobic protective coating for concrete prepared in this embodiment is a milky white, uniform fluid with moderate viscosity, facilitating application. After application to the concrete substrate, the coating, through the synergistic effect of its components, forms a dense superhydrophobic protective film on the concrete surface. It is amine-free and porous. The constructed porous structure, combined with the hydrophobic groups provided by octyltriethoxysilane, exhibits excellent superhydrophobicity, effectively preventing moisture, chloride ions, and other corrosive media from penetrating the concrete interior. PVA-coated nanoparticles... The addition of [a specific ingredient] fills the tiny pores on the concrete surface, improving the density of the protective film. Simultaneously, its alkaline properties neutralize acidic substances on the concrete surface, slowing down the carbonation process. The synergistic effect of nano-bentonite and sodium carboxymethyl cellulose enhances the film-forming properties and adhesion of the coating, ensuring a strong bond between the protective film and the concrete substrate, preventing it from easily detaching. Furthermore, the PVA-coated nano-[a specific ingredient] in the coating... It can undergo carbonization reaction with carbon dioxide in the atmosphere to achieve active carbon fixation, forming a negative carbon technology path; and the entire coating formulation and preparation process does not require fluorine-containing substances, amine template agents and ethanol, and uses water as the main solvent.

[0010] Preferably, the amine-free porous The specific surface area is >100m² / g and the pore size is 15-27nm. It is prepared by the following steps: using industrial silica sol as raw material, it is dried under normal pressure with HF catalysis and PVA124 assistance, and then calcined.

[0011] Amine-free porous The powder possesses a high specific surface area and suitable pore size. Its amine-free nature avoids the influence of amines on the alkali-aggregate reaction of concrete, ensuring the stability of the concrete structure. When this powder is applied to superhydrophobic protective coatings for concrete, its abundant porous structure can serve as a carrier substrate for hydrophobic groups, significantly improving the dispersibility and binding strength of octyltriethoxysilane in the coating. This results in a protective film formed after coating formation with more hydrophobic sites, significantly enhancing the superhydrophobic effect on the concrete surface.

[0012] Preferably, the PVA is coated with nanoparticles. The particle size is 50-100 nm, and the PVA coating rate is 0.1-0.3 wt%. It is prepared by the following steps: in an aqueous environment in which PVA124 is present, ... After reacting with NaOH to form a precipitate, the precipitate is dehydrated by azeotropic distillation of n-butanol.

[0013] The PVA-coated nanoparticles prepared in this embodiment The powder has uniform particle size and good dispersibility; the PVA coating effectively inhibits nanoparticle growth. The aggregation of particles allows for stable dispersion in aqueous coating systems, preventing sedimentation. When this composite powder is applied to superhydrophobic protective coatings for concrete, the nanoscale... The particles can fill the tiny pores on the concrete surface, react with hydration products in the concrete matrix to form stable chemical bonds, and enhance the adhesion between the protective film and the concrete matrix. Simultaneously, Its alkaline properties can neutralize the acidic corrosive media on the concrete surface, delaying the carbonation and corrosion process of the concrete; the PVA coating layer enhances the compatibility of the powder with other components of the coating, and improves the film-forming properties of the coating and the flexibility of the protective film.

[0014] Moreover, the preparation of PVA-coated nanoparticles The n-butanol used in the process can be efficiently recovered through condensation separation, with a recovery rate of over 95%, which complies with green chemistry principles and environmental regulations.

[0015] Preferably, the sodium carboxymethyl cellulose has a degree of substitution of 0.6-0.8, a purity of ≥98%, and a viscosity of [missing value] in a 2wt% aqueous solution at 25°C. .

[0016] Preferably, the nano-bentonite has a particle size of 40-120 nm, a montmorillonite content of ≥95%, and an expansion ratio of 15-25 times in an aqueous environment at 25°C.

[0017] On the other hand, another technical solution of the present invention provides a method for preparing the superhydrophobic protective coating for concrete, comprising the following steps: S1. Preparation of amine-free porous materials Take 10 L of industrial silica sol, 20 L of deionized water, and 0.1 L of HF solution, and add 0.2% PVA124 (by weight of the total coating). Stir at 30-50℃ until a gel forms. Then, dry the gel under normal pressure. After drying, calcine it at 550℃ for 4 hours. Finally, after pulverization and sieving, obtain an amine-free porous gel. ; S2. Preparation of PVA-coated nanoparticles Add 10 L of 0.5 mol / L [agent] to 0.2% PVA124 of the total coating mass. The solution was slowly mixed with 12 L of 1.0 mol / L NaOH solution under continuous stirring, and reacted at 25 °C for 1 hour to form a precipitate. Then, 22 L of n-butanol was added, and azeotropic distillation was performed to dehydrate the precipitate. After dehydration, the product was vacuum dried to obtain white PVA-coated nanoparticles. powder; S3. Add sodium carboxymethyl cellulose to a small amount of deionized water at a mass ratio of 1:45-50, and ultrasonically disperse until a uniform dispersion is formed to obtain an aqueous solution of sodium carboxymethyl cellulose for later use; add nano-bentonite to deionized water at a mass ratio of 1:45-50, and stir to dissolve at 35-40℃ to form a transparent nano-bentonite dispersion for later use. S4. Preparation of protective coating First of all Dissolved in partially deionized water, then octyltriethoxysilane with a pre-hydrolysis degree >90% was added and stirred until homogeneous; then the PVA-coated nanoparticles obtained in step S2 were added. The sodium carboxymethyl cellulose aqueous solution and nano-bentonite dispersion obtained in step S3 were treated by ultrasonic dispersion; finally, the amine-free porous material obtained in step S1 was added. The material undergoes high-speed shearing and homogenization, while deionized water is added to the required total volume to obtain a superhydrophobic protective coating for concrete.

[0018] Amine-free porous PVA-coated nanoparticles The combination of components such as nano-bentonite creates a unique microstructure on the concrete surface after the coating film is formed. This structure, along with the low surface energy octyltriethoxysilane, significantly increases the water contact angle of the coating surface, achieving a superhydrophobic effect. This effectively prevents water adhesion and penetration onto the concrete surface, protecting it from water erosion. Nano-bentonite and sodium carboxymethyl cellulose, acting as thickeners and stabilizers, effectively prevent the sedimentation and agglomeration of solid particles in the coating, ensuring a uniform state during storage and use, preventing layering, clumping, and other phenomena, thus guaranteeing consistent quality and performance. Furthermore, the components are tightly bonded through chemical bonds and physical interactions, forming a stable structure. Octyltriethoxysilane enhances the adhesion between the coating and the concrete substrate, making the coating less susceptible to external environmental factors such as ultraviolet radiation, temperature changes, and chemical corrosion during long-term use. This allows it to maintain excellent protective performance for extended periods, extending the service life of the concrete structure and reducing maintenance costs and frequency.

[0019] On the other hand, another technical solution of the present invention provides a method for superhydrophobic protection of concrete, wherein the superhydrophobic protective coating for concrete described in any one of claims 1-4 is applied using... The dosage is applied to the concrete substrate surface by spraying, followed by natural curing of the concrete for 48-72 hours.

[0020] Preferably, the maintenance conditions are: temperature 28-35℃, relative humidity 65-75%.

[0021] The present invention has at least the following beneficial effects: (1) Environmental friendliness: The entire process does not require fluorine-containing substances, amine template agents and ethanol. Water is used as the main solvent and n-butanol can be efficiently recovered (>95%), which complies with the principles of green chemistry and environmental protection regulations.

[0022] (2) Active carbon sequestration: utilizing carbon in the atmosphere The carbonization reaction can achieve a net carbon fixation of approximately 5.3 grams per square meter of coating, realizing a negative carbon technology path.

[0023] (3) Excellent performance: The contact angle of the resulting coating is >153°. Sliding angle < 5 It reduces chloride ion permeability by more than 83%, resulting in significant protective effects.

[0024] (4) Industrialization feasibility: The raw materials are all industrial grade, the preparation process is simple (atmospheric pressure drying, aqueous phase reaction), the equipment requirements are low, and the comprehensive cost is only about RMB 6.2 per square meter, which has great potential for large-scale application.

[0025] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Detailed Implementation

[0026] The present invention will be further described in detail below with reference to embodiments, so that those skilled in the art can implement it based on the description.

[0027] The following description is intended to disclose the present invention and enable those skilled in the art to implement it. The preferred embodiments described below are merely examples, and other obvious modifications will occur to those skilled in the art. The basic principles of the invention defined in the following description can be applied to other embodiments, modifications, improvements, equivalents, and other technical solutions that do not depart from the spirit and scope of the invention.

[0028] It is understood that the term "a" should be understood as "at least one" or "one or more", that is, in one embodiment, the number of an element can be one, while in another embodiment, the number of the element can be multiple, and the term "a" should not be understood as a limitation on the number.

[0029] Example 1 S1. Preparation of amine-free porous materials Take industrial silica sol ( 10 L of 30% HF solution was diluted with 20 L of deionized water. 0.1 L of 0.1% HF solution and 0.2 wt% PVA124 were added, and the mixture was stirred at 40 °C for 2 hours until gelation. The gel was placed in a PTFE tray and dried at 25 °C and 50% humidity under normal pressure for 48 hours. The dried block was calcined in a muffle furnace at 550 °C for 4 hours, cooled, and then pulverized through a 120-mesh sieve to obtain an amine-free porous material. Powder. BET test results show a specific surface area of ​​118 m² / g and an average pore size of 24.1 nm.

[0030] S2. Preparation of PVA-coated nanoparticles Add 10 L of 0.5 mol / L [agent] to 0.2% PVA124 of the total coating mass. The solution was slowly mixed with 12 L of 1.0 mol / L NaOH solution under continuous stirring, and the reaction was carried out at 25 °C for 1 hour to form a precipitate. After the reaction was complete, 22 L of n-butanol was added to the slurry, and azeotropic distillation was performed at 85 °C to dehydrate and recover the solvent mixture. The resulting wet solid was vacuum dried at 80 °C for 12 hours to obtain a white powder. TEM analysis showed that the average particle size was 82 nm.

[0031] S3. Add 2 kg of sodium carboxymethyl cellulose to 98 kg of deionized water and ultrasonically disperse until a uniform dispersion is formed to obtain an aqueous solution of sodium carboxymethyl cellulose for later use; add 1.4 kg of nano-bentonite to 28 kg of deionized water and stir to dissolve at 35-40℃ to form a transparent nano-bentonite dispersion for later use. S4. Prepare the protective coating: Measure 60L of deionized water and add... 10.2g (make) The concentration was 0.05 mol / L, and the mixture was stirred to dissolve. 12 kg (12 wt%) of pre-hydrolyzed (92% degree of hydrolysis) octyltriethoxysilane was added, and the mixture was stirred for 10 minutes. The PVA-coated nanoparticles prepared in step S2 were then added. 7.2 kg (7.2 wt%) of powder was treated with an ultrasonic disperser (200 W) for 10 minutes. The amine-free porous powder prepared in step 1 was then slowly added. 6 kg (6 wt%) of powder was homogenized at 3000 rpm for 5 minutes using a high-speed shear disperser. Finally, deionized water was added to bring the total mass to 100 kg, and the mixture was stirred until homogeneous to obtain the protective coating.

[0032] Application testing: The protective coating prepared in this embodiment was sprayed onto the surface of a C40 concrete specimen (150mm×150mm×150mm), with a dosage of [amount missing]. Cured naturally for 72 hours at 30℃ and 70%RH.

[0033] Application test results: The water contact angle of Example 1 was 154.2°. The sliding angle is 4.2. RCM testing showed that the chloride ion diffusion coefficient decreased by 85.1%; carbonization analysis determined the carbon fixation content to be 5.5%. .

[0034] Comparative Example 1 The component ratios, preparation methods, construction, and curing conditions were completely consistent with those of Example 1. The only difference was that the traditional ethanol solvent method was used to prepare the nanoparticles in Comparative Example 1. (Refer to CN113480082A) PVA coating is not used, and ethanol is used for dehydration and drying.

[0035] Application test results: Nano It exhibits poor dispersibility and is prone to sedimentation in protective coatings, resulting in coating cracks and a water contact angle of 148.1°. Sliding angle 8.5 The chloride ion permeability decreased by 71.2%. This indicates that the aqueous azeotropic dehydration and PVA coating process of the present invention has a significant positive impact on material properties and the final protective effect.

[0036] Comparative Example 2 The component ratios, preparation methods, construction and curing conditions were completely consistent with those of Example 1. The only difference was that Comparative Example 2 did not contain amine porous materials. In the preparation process, PVA124 in the raw materials of Example 1 was replaced with a traditional amine template agent (triethylamine).

[0037] Application test results: Water contact angle 150.2°. Sliding angle 4.8 The chloride ion permeability decreased by 78.5%, and the carbon sequestration was only 3.15%. .

[0038] Comparative Example 3 The component ratios, preparation methods, construction and curing conditions are completely consistent with those of Example 1. The only difference is that sodium carboxymethyl cellulose and nano-bentonite were removed from the raw materials in Example 1 in Comparative Example 3.

[0039] Application test results: The coating's water contact angle is only 139.2°. Sliding angle 14.6 Chloride ion permeability decreased by 59.3%, and carbon sequestration was 3.87. .

[0040] Comparative Example 4 The component ratios, preparation methods, construction and curing conditions are completely consistent with those of Example 1. The only difference is that sodium carboxymethyl cellulose in the raw materials of Example 1 is removed in Comparative Example 4.

[0041] The coating has a water contact angle of 145.3 degrees. Sliding angle 8.9 Chloride ion permeability decreased by 71.4%, and carbon sequestration was 4.02%. .

[0042] Comparative Example 5 The component ratio, preparation method, construction and curing conditions are completely consistent with those of Example 1. The only difference is that the nano-bentonite in the raw materials of Example 1 is removed in Comparative Example 5.

[0043] Water contact angle 148.6 Sliding angle 6.5 Chloride ion permeability decreased by 75.8%, and carbon sequestration was 4.35%. .

[0044] Comparative Example 6 The component ratios, preparation methods, construction and curing conditions were completely consistent with those of Example 1. The only difference was that Comparative Example 6 did not use amine-free porous materials. .

[0045] Application test results: The coating surface is uneven, and the water contact angle is 142.5°. Sliding angle > 10 The chloride ion permeability decrease rate was only 52.4%. This indicates that the porous structure... It is crucial for constructing stable micro / nano structures and improving hydrophobicity.

[0046] Comparative Example 7 The component ratios, preparation methods, construction, and curing conditions are completely consistent with those of Example 1. The only difference is that Comparative Example 7 does not use... .

[0047] Application test results: Water contact angle 149.6° Sliding angle 6.1 The carbon sequestration capacity is only 2.1%. .show The introduction of [the substance] can effectively promote the formation of a more hydrophobic flower-like dolomite structure from the carbonization products. ), and improve carbon sequestration efficiency.

[0048] Compare with Example 1 Using commercially available hydrophobic concrete coatings (fluorine-modified acrylics), following the process recommended in the product instructions (200... The dosage and spraying method were applied to C30 concrete test blocks of the same specifications and cured in a natural environment (temperature 20-25℃, relative humidity 60-70%) for 72 hours as a reference for existing technology.

[0049] Compare with Example 2 As a blank control group, C30 concrete test blocks without any coating were cured for 60 hours under the same curing conditions as in Example 1 and used for benchmark performance testing.

[0050] Comparative Example 1 uses a commercially available concrete hydrophobic coating (fluorine-modified acrylic ester), following the process recommended in the product instructions (200...). The dosage and spraying method were applied to C30 concrete test blocks of the same specifications and cured for 72 hours in a natural environment (temperature 20-25℃, relative humidity 60-70%) as a performance reference for existing technology.

[0051] Example 2 served as a blank control group. C30 concrete specimens without any coating were cured for 60 hours under the same curing conditions as in Example 1 and used for benchmark performance testing.

[0052] Test results show that the water contact angle of Example 1 is 154.2°. The sliding angle is 4.2. RCM testing showed that the chloride ion diffusion coefficient decreased by 85.1%; the carbon sequestration per unit area was 5.5. Comparative Example 1 lacks PVA-coated nanoparticles. The water contact angle decreased to 148.1°. The sliding angle is increased to 8.5 degrees. The chloride ion penetration reduction rate was only 71.2%, and there was no significant carbon fixation effect. This indicates that the aqueous azeotropic dehydration and PVA coating process of this invention has a significant positive impact on material properties and the final protective effect. Among these, the PVA-coated nanoparticles... It is key to carbon fixation; its nanoparticle size can fill the tiny gaps in the coating, making the coating denser. Can be in the air The reaction produces calcium carbonate, achieving active carbon fixation; the PVA coating provides protection. It does not prematurely degrade and extends the contact time. In Comparative Example 2, after using an amine template agent, the water contact angle was 150.2°. Sliding angle 4.8 The chloride ion permeability decreased by 78.5%, but the n-butanol recovery rate dropped to 82.3%, and the carbon sequestration was only 3.15%. Furthermore, they contain toxic volatile substances, failing to meet environmental protection requirements. This is because amine template agents leave toxic residues and can interfere with... and The reaction affects solvent recovery efficiency, while Example 1 uses amine-free porous solvents. This problem was avoided. In Comparative Example 3, the stability of the coating significantly deteriorated after both components were removed, with the water contact angle of the coating decreasing to only 139.2°. Sliding angle 14.6 Chloride ion permeability decreased by 59.3%, and carbon sequestration was 3.87. This is because the "dispersing effect" of sodium carboxymethyl cellulose and the "barrier effect" of nano-bentonite are synergistic. Uniform dispersion is essential for the bentonite to fully exert its barrier effect; the absence of either will lead to a significant decline in performance. In Comparative Example 4, after removing sodium carboxymethyl cellulose, the coating showed stratification and precipitation after 72 hours of storage, and the water contact angle of the coating was 145.3°. Sliding angle 8.9 Chloride ion permeability decreased by 71.4%, and carbon sequestration was 4.02%. This is because sodium carboxymethyl cellulose acts like a "dispersant and stabilizer," ensuring all components mix evenly and don't separate. Without it, powder agglomeration and uneven coating occur, compromising both hydrophobic and carbon-fixing effects. In Comparative Example 5, removing nano-bentonite resulted in decreased coating density and a water contact angle of 148.6°. Sliding angle 6.5 Chloride ion permeability decreased by 75.8%, and carbon sequestration was 4.35%. This is because nano-bentonite acts as a "barrier reinforcement agent," its layered structure acting like a "barrier" to block chloride ion penetration while simultaneously enhancing coating strength and making the hydrophobic effect more durable. The overall performance of Comparative Examples 6 and 7 also decreased due to their porous structure. This is crucial for constructing stable micro / nano structures and improving hydrophobicity. The introduction of [a specific ingredient] can effectively promote the formation of a more hydrophobic flower-like dolomite structure from the carbonization products. And improve carbon sequestration efficiency.

[0053] The water contact angle for comparison example 1 is 148.3°. Sliding angle 6.5 The chloride ion penetration reduction rate was 75.2%, with no carbon sequestration effect and the fluoride content was not environmentally friendly; in contrast, the water contact angle of control example 2 was only 45.2°. It has no sliding angle, a chloride ion penetration decrease rate of 0, and no carbon fixation capacity.

[0054] The performance degradation in each comparative example demonstrates that the absence of a single component leads to impaired overall performance, while Example 1 achieves better results through the synergistic effect of the components (PVA-coated nanoparticles). Sodium carboxymethyl cellulose is responsible for carbon fixation and dense coating, sodium carboxymethyl cellulose is responsible for uniform dispersion, nano-bentonite is responsible for barrier reinforcement, and amine-free porous coating is responsible for the overall structure. (Auxiliary hydrophobicity + environmental protection) The introduction of [the substance] effectively promotes the formation of a more hydrophobic flower-like dolomite structure from the carbonization products. porous It can construct stable micro-nano structures and improve hydrophobicity, and comprehensively achieves the unity of hydrophobic performance, impermeability, active carbon fixation and environmental protection. Its technical effect is not a simple superposition of single components, but an unexpected comprehensive improvement brought about by the synergy of multiple factors.

[0055] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and embodiments shown and described herein.

Claims

1. A superhydrophobic protective coating for concrete, comprising, by weight percentage: 5-10 wt% amine-free porous ; 6-12wt% PVA-coated nano ; 0.4-0.6wt% ; 8-15wt% octyltriethoxysilane; 0.6-2.2wt% nano-bentonite; 1-3wt% sodium carboxymethyl cellulose; balance deionized water.

2. The superhydrophobic protective coating for concrete according to claim 1, characterized in that, The amine-free porous The specific surface area is > 100 m² / g and the pore size is 15-27 nm. It is prepared by the following steps: using industrial silica sol as raw material, it is dried under normal pressure with HF catalysis and PVA124 assistance, and then calcined.

3. The superhydrophobic protective coating for concrete according to claim 1, characterized in that, The PVA-coated nano The particle size is 50-100 nm, and the PVA coating rate is 0.1-0.3 wt%. It is prepared by the following steps: in an aqueous environment in which PVA124 is present, ... After reacting with NaOH to form a precipitate, the precipitate is dehydrated by azeotropic distillation of n-butanol.

4. The superhydrophobic protective coating for concrete according to claim 1, characterized in that, The sodium carboxymethyl cellulose has a degree of substitution of 0.6-0.8, a purity of ≥98%, and a viscosity of [missing value] in a 2wt% aqueous solution at 25°C. .

5. The superhydrophobic protective coating for concrete according to claim 1, characterized in that, The nano-bentonite has a particle size of 40-120 nm, and a montmorillonite content of ≥95%. The nano-bentonite expands 15-25 times in an aqueous environment at 25°C.

6. A method for preparing the superhydrophobic protective coating for concrete according to any one of claims 1-5, characterized in that, Includes the following steps: S1. Preparation of amine-free porous materials Take 10 L of industrial silica sol, 20 L of deionized water, and 0.1 L of HF solution, and add 0.2% PVA124 (by weight of the total coating). Stir at 30-50℃ until a gel forms. Then, dry the gel under normal pressure. After drying, calcine it at 550℃ for 4 hours. Finally, after pulverization and sieving, obtain an amine-free porous gel. ; S2. Preparation of PVA-coated nanoparticles Add 10 L of 0.5 mol / L [agent] to 0.2% PVA124 of the total coating mass. The solution was slowly mixed with 12 L of 1.0 mol / L NaOH solution under continuous stirring, and reacted at 25°C for 1 hour to form a precipitate; then 22 L of n-butanol was added to the precipitate and azeotropic distillation was performed to remove the precipitate. After dehydration, the product was vacuum dried to obtain white PVA-coated nanoparticles. powder; S3. Add sodium carboxymethyl cellulose to deionized water at a mass ratio of 1:45-50, and ultrasonically disperse until a uniform dispersion is formed to obtain an aqueous solution of sodium carboxymethyl cellulose for later use; add nano-bentonite to deionized water at a mass ratio of 1:45-50, and stir to dissolve at 35-40℃ to form a transparent nano-bentonite dispersion for later use. S4. Preparation of protective coating First of all Dissolve in deionized water, then add pre-hydrolyzed octyltriethoxysilane and stir until homogeneous; then add the PVA-coated nanoparticles obtained in step S2. The sodium carboxymethyl cellulose aqueous solution and nano-bentonite dispersion obtained in step S3 were treated by ultrasonic dispersion; finally, the amine-free porous material obtained in step S1 was added. The material undergoes high-speed shearing and homogenization, while deionized water is added to the required total volume to obtain a superhydrophobic protective coating for concrete.

7. A method for superhydrophobic protection of concrete, characterized in that, The superhydrophobic protective coating for concrete according to any one of claims 1-4 is used as follows: The dosage is applied to the concrete substrate surface by spraying, followed by natural curing of the concrete for 48-72 hours.

8. The method for superhydrophobic protection of concrete according to claim 7, characterized in that, Maintenance conditions are: temperature 28-35℃, relative humidity 65-75%.

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