Protective coating for concrete structure surfaces and method for applying same

Abstract

The present application relates to the technical field of civil engineering materials, and provides a protective coating for a concrete structure surface and a construction method thereof, the protective coating comprising: component A and component B; the component A and the component B are composed in a mass ratio of 3:1-5:1; the component A comprises: a polyurea polymer, an acrylate copolymer, a flame retardant, a defoaming agent and a leveling agent; the component B comprises: an inorganic cementitious material, a fiber, a nano filler and a curing agent; the acrylate copolymer in the component A cooperates with the curing agent in the component B, so that the mixed coating is quickly surface-dried under light or oxidation-reduction conditions. The present application activates the crosslinking of the acrylate double bond through a photoinitiator, and simultaneously forms an interpenetrating network structure through physical entanglement of the polyurea resin, thereby achieving 3-second surface drying without the need for heating; cement particles are enriched at the bottom of the coating to improve adhesion, the fiber is distributed in the surface layer to resist cracking, and the nano filler fills the interface micropores to improve impermeability.

Description

Technical Field

[0001] This invention relates to the field of civil engineering materials technology, and in particular to a protective coating for concrete structure surfaces and its construction method. Background Technology

[0002] Traditional tunnel lining protection materials mainly use epoxy resin, polyurethane, and thermally sprayed polyurea systems, but these materials have significant drawbacks. During construction, the use of isocyanate-based curing agents releases toxic gases, and the high-temperature spraying process may pose a risk of combustion and explosion, resulting in poor construction safety. Furthermore, these materials are not environmentally friendly; solvent-based coatings contain volatile organic compounds (VOCs) exceeding national standards, and long-term use may lead to coating chalking and subsequent groundwater pollution. In addition, existing polyurea materials generally have low elongation at break; when concrete cracks exceed 0.2 mm, the coating is prone to stress concentration and fracture, losing its waterproofing function. Regarding durability, single polymer materials are prone to embrittlement and detachment under harsh environments such as freeze-thaw cycles and salt-alkali erosion, leading to a significant decrease in bond strength.

[0003] To address the shortcomings of existing materials, technological improvements are focused on developing environmentally friendly composite systems of modified polyurea and inorganic materials. For example, incorporating silicate cement can improve coating rigidity, or carbon fiber-reinforced polyurea can enhance crack resistance. However, these methods still face the challenge of balancing rapid curing with flexibility, as well as insufficient interfacial adhesion. Existing organic coatings such as polyurethane and epoxy resins generally suffer from a conflict between curing speed and mechanical properties, and rely on isocyanate-amine chemical reactions for film formation, posing health and safety risks. Cement-based penetrating crystalline materials, due to continuous hydration reactions, lose water rapidly in tunnels, forming a porous, powdery layer that affects aesthetics. Therefore, there is an urgent need to develop a composite protective system that requires no heating, is non-toxic, and can adapt to dynamic cracks. Furthermore, open-ended formulation and process design are needed to improve the technology's versatility and adaptability to meet the demands of modern tunnel engineering. Summary of the Invention

[0004] The purpose of this invention is to solve at least one technical problem in the background art and to provide a protective coating for concrete structure surfaces and its construction method.

[0005] To achieve the above objectives, the present invention provides a protective coating for concrete structure surfaces, comprising: component A and component B; The A component and the B component are composed in a mass ratio of 3:1 to 5:1; Component A comprises: 40-70% polyurea polymer, 15-30% acrylate copolymer, 5-15% flame retardant, 0.1-0.8% defoamer, and 0.1-0.3% leveling agent; Component B comprises: 5-20% inorganic cementitious material, 1-8% fiber, 2-10% nanofiller, and 1-5% curing agent; The acrylate copolymer in component A undergoes a cross-linking reaction under light irradiation or redox conditions under the action of the curing agent in component B, enabling the mixed coating to achieve rapid surface drying.

[0006] The acrylate copolymer in component A contains hydrophilic functional groups, which, together with the inorganic cementitious material in component B, form a stable organic-inorganic hybrid dispersion system under the action of a coupling agent; through high-speed dispersion and vacuum degassing processes, the water-based cement powder and organic resin are uniformly mixed.

[0007] The curing agent comprises a composite system of photoinitiator and redox initiator, wherein the photoinitiator is used for rapid surface drying of the surface layer, and the redox initiator continuously initiates deep crosslinking of the acrylate copolymer under no light conditions, ensuring complete overall curing of the coating.

[0008] According to one aspect of the present invention, the polyurea polymer is at least one of aliphatic polyurea and polyaspartic acid ester.

[0009] According to one aspect of the invention, the inorganic cementitious material is selected from one or more of silicate cement, sulfoaluminate cement, and geopolymers.

[0010] According to one aspect of the present invention, the fiber is basalt fiber, polypropylene fiber, steel fiber or polyvinyl alcohol fiber, with a fiber length of 0.5-8 mm, an aspect ratio of 30-300, and a content of 1-5%.

[0011] According to one aspect of the present invention, the nanofiller is one or more of nano-silica, nano-alumina, carbon nanotubes or montmorillonite, with a particle size ≤200nm and a doping amount of 3-8%.

[0012] According to one aspect of the present invention, the flame retardant is at least two of aluminum hydroxide, zinc borate, expanded graphite, and phosphorus-nitrogen synergistic flame retardants.

[0013] According to one aspect of the invention, the curing agent is a nonionic photoinitiator or redox initiator, selected from benzophenone derivatives and persulfate-ascorbic acid systems, with a dosage of 1-3%.

[0014] According to one aspect of the present invention, component A further comprises: 0.5-2% of a coupling agent, wherein the coupling agent is at least one selected from silane coupling agents and titanate coupling agents.

[0015] To achieve the above objectives, the present invention also provides a method for applying the above-mentioned protective coating, comprising: (1) Surface preparation: Clean and repair the concrete surface; (2) Material mixing: Before on-site construction, mix component A and component B in proportion and let them mature for 5-15 minutes; (3) Spraying construction: High-pressure airless spraying or air pressure spraying process is used to spray the mixture onto the treated concrete base surface to form a wet film; (4) Curing: Under natural light or auxiliary ultraviolet light, the coating will be surface dry in 3-8 seconds and cured at room temperature for 48-96 hours.

[0016] According to one aspect of the present invention, the pressure of the high-pressure airless spraying is 10-25 MPa, the nozzle diameter is 0.4-0.8 mm, and a single spraying layer forms a wet film thickness of 1.2-2.0 mm. The air pressure spraying is 0.5-1.0MPa, the nozzle diameter is 1.0-2.0mm, the spraying distance is 30-60cm, and 2-3 coats are applied to a total thickness of 1.2-2.0mm.

[0017] According to the solution of the present invention, compared with the conventional solution, the present invention can achieve the following beneficial effects: Non-reactive curing mechanism: Acrylic double bonds are cross-linked by photoinitiator, and polyurea resin physically entangles to form an interpenetrating network structure, achieving surface drying in 3 seconds without heating. Gradient reinforcement design: Cement particles are enriched at the bottom of the coating to improve adhesion, fibers are oriented on the surface to resist cracking, and nanofillers fill the micropores at the interface to improve impermeability. Open process parameters: Supports two modes: high-pressure airless spraying (pressure 18-25MPa) and air pressure spraying (0.6-0.8MPa), covering the needs of different engineering scenarios.

[0018] This invention overcomes the limitations of traditional heating processes by using a room-temperature curing polyurea-cement composite coating; it resolves the rigidity-flexibility contradiction through a gradient structure of cement bottom anchoring + fiber intermediate reinforcement + nano-surface sealing; and it eliminates isocyanate substances and achieves zero VOC emissions through a benzophenone photoinitiation system.

[0019] This invention employs an open-source formulation design, supporting flexible replacement of cement types (silicate / sulfoaluminate) and fiber types (basalt / polypropylene). No toxic gases are released during construction, and the overall cost is reduced by 40% compared to traditional methods.

[0020] According to the present invention, a polyurea-cement-based protective coating is provided. Through the synergistic effect of a non-reactive photocurable system and a gradient reinforcement structure, it achieves rapid film formation at room temperature and possesses excellent comprehensive performance. Its beneficial effects are illustrated below through experimental data and theoretical analysis: (1) Rapid curing and construction adaptability At room temperature (20°C), the coating system of this invention achieves surface drying within 3 seconds and allows for the next coat to be applied within 8 minutes. Compared with traditional thermal spray polyurea (which requires heating to above 60°C) and epoxy resin (curing time > 2 hours), this solution significantly improves construction efficiency, reduces energy consumption, and eliminates the need for dedicated heating equipment, making it suitable for tunnel environments with limited ventilation.

[0021] (2) High bond strength and interfacial durability Through the gradient enrichment of cement particles at the bottom of the coating, a microscopic mechanical bond and chemical bond are formed with the concrete matrix. Pull-out tests were conducted using a 20mm diameter aluminum alloy test column at a uniform tensile rate of 0.5 MPa / s, according to GB / T 5210-2006 standard. Experiments showed that the coating's bond strength reached 3.5–4.2 MPa (higher than the national standard ≥1.5 MPa), and remained ≥3.0 MPa after 300 freeze-thaw cycles. Scanning electron microscopy (SEM) revealed no pores or delamination at the coating-concrete interface, indicating excellent interfacial stability.

[0022] (3) Dynamic crack following ability The directional distribution of fibers in the coating and the flexibility of the polyurea-acrylate network enable it to withstand the opening displacement of cracks in the substrate up to 0.3 mm. According to GB / T 528-2009 standard, dumbbell-shaped specimens were stretched at a rate of 50 mm / min on a universal testing machine, and the state of the coating was recorded when the crack width in the substrate was 0.3 mm. The results show that the coating did not crack or peel, and the elongation was ≥180%, indicating that it has good stress dissipation and deformation adaptability, and can effectively follow dynamic cracks in the concrete.

[0023] (4) High impermeability and resistance to environmental erosion The synergistic filling effect of nano-SiO2 and cement hydration products significantly improves the density of the coating. Impermeability tests show that the coating remains impermeable under 1.5 MPa water pressure, and the chloride ion permeability coefficient is ≤1.5×10⁻⁶. -12 m 2 / s, possessing excellent resistance to impermeability and ion erosion. According to GB / T 10125-2012 standard, after a continuous 1000-h salt spray test in a 35℃, 5% NaCl solution spray environment, the coating showed no blistering or peeling, indicating that it has excellent resistance to salt spray erosion and is suitable for coastal or de-icing salt environments.

[0024] (5) Environmental protection and safety performance This invention completely eliminates isocyanate compounds, with a VOC content ≤30 g / L, and no detectable free formaldehyde or benzene compounds. No toxic gases are released during construction, meeting the requirements of GB 50325-2020 "Code for Indoor Environmental Pollution Control of Civil Building Engineering". Attached Figure Description

[0025] Figure 1 The flowchart schematically illustrates a method for applying a protective coating to a concrete structure surface according to one embodiment of the present invention. Detailed Implementation

[0026] The invention will now be discussed with reference to exemplary embodiments. It should be understood that the described embodiments are merely intended to enable those skilled in the art to better understand and thus implement the invention, and are not intended to imply any limitation on the scope of the invention.

[0027] As used herein, the term "comprising" and its variations are to be interpreted as open-ended terms meaning "including but not limited to". The term "based on" is to be interpreted as "at least partially based on". The terms "one embodiment" and "an embodiment" are to be interpreted as "at least one embodiment".

[0028] To achieve the above objectives, the present invention provides a protective coating for concrete structure surfaces, comprising: component A and component B; Component A and component B are composed of a mass ratio of 3:1 to 5:1; Component A comprises: 40-70% polyurea polymer, 15-30% acrylate copolymer, 5-15% flame retardant, 0.1-0.8% defoamer, and 0.1-0.3% leveling agent; Component B comprises: 5-20% inorganic cementitious materials, 1-8% fiber, 2-10% nanofiller, and 1-5% curing agent; Component B comprises: 5-20% inorganic cementitious materials, 1-8% fiber, 2-10% nanofiller, and 1-5% curing agent; According to one embodiment of the present invention, the polyurea polymer is at least one of aliphatic polyurea and polyaspartic acid ester, which forms a network structure of chemical crosslinking and physical entanglement with acrylate copolymer under the action of curing agent, and the molecular weight range is 2000-8000 Da.

[0029] According to one embodiment of the present invention, the acrylate copolymer in component A contains hydrophilic functional groups, and forms a stable organic-inorganic hybrid dispersion system with the inorganic cementitious material in component B under the action of a coupling agent; the uniform mixing of water-based cement powder and organic resin is achieved through high-speed dispersion and vacuum degassing processes.

[0030] According to one embodiment of the present invention, the curing agent comprises a composite system of a photoinitiator and a redox initiator, wherein the photoinitiator is used for rapid surface drying of the surface layer, and the redox initiator continuously initiates deep crosslinking of the acrylate copolymer under no-light conditions, ensuring complete overall curing of the coating.

[0031] The acrylate copolymer in component A, combined with the curing agent in component B, enables the mixed coating to rapidly surface dry under light or redox conditions. The coating forms a film within 3-8 seconds at room temperature, with a cured thickness of 2.0-3.0 mm, an adhesion strength ≥3 MPa, and can withstand tensile deformation from a 0.3 mm crack in the substrate.

[0032] Furthermore, according to one embodiment of the present invention, the polyurea polymer is at least one of aliphatic polyurea and polyaspartic acid ester, with a molecular weight range of 2000-8000 Da.

[0033] Furthermore, according to one embodiment of the present invention, the inorganic cementitious material is selected from one or more of silicate cement, sulfoaluminate cement, and geopolymer, and the dosage is 5-15%.

[0034] Furthermore, according to one embodiment of the present invention, the fiber is basalt fiber, polypropylene fiber, steel fiber or polyvinyl alcohol fiber, with a fiber length of 0.5-8 mm, an aspect ratio of 30-300, and a content of 1-5%.

[0035] Furthermore, according to one embodiment of the present invention, the nanofiller is one or more of nano-silica, nano-alumina, carbon nanotubes or montmorillonite, with a particle size ≤200nm and a doping amount of 3-8%.

[0036] Furthermore, according to one embodiment of the present invention, the flame retardant is at least two of aluminum hydroxide, zinc borate, expanded graphite, and phosphorus-nitrogen synergistic flame retardant, with a dosage of 8-12%.

[0037] Furthermore, according to one embodiment of the present invention, the curing agent is a nonionic photoinitiator or redox initiator, selected from one of benzophenone derivatives and persulfate-ascorbic acid systems, with a dosage of 1-3%.

[0038] Furthermore, according to one embodiment of the present invention, it further includes: 0.5-2% of a coupling agent, wherein the coupling agent is at least one selected from silane coupling agent KH-550 and titanate coupling agent NDZ-201.

[0039] According to the above-mentioned protective coating of the present invention, its VOC content is ≤50g / L, and free formaldehyde and benzene compounds are not detected. Its impermeability pressure is ≥1.2MPa, its mass loss after 500 freeze-thaw cycles is ≤0.5%, and its flame retardancy rating reaches UL94 V-0.

[0040] According to the above-described scheme of the present invention, the protective coating of the present invention is applicable to the surface protection of tunnel lining, underground integrated pipe gallery, concrete structure of water conservancy and hydropower project, or the repair of cracks in existing concrete structure.

[0041] The protective coating of the present invention maintains flexibility in an ambient temperature range of -30°C to 80°C, and has an elongation at break of ≥150%.

[0042] The protective coating of the present invention can be prepared by using a high-speed disperser (500-1200 rpm) in combination with a vacuum degassing device; the protective coating can be prepared by using a ball mill (grinding fineness ≤50μm) in combination with a drying tower (dew point ≤-40℃). When mixing the protective coating and the protective coating, the two components can be mixed by using a two-component dynamic mixing spray gun with a mixing accuracy error ≤1.5%. The spray gun is equipped with a temperature sensor and a pressure feedback device to adjust the mixing ratio and spraying speed in real time.

[0043] Furthermore, after the protective coating of this invention is formed, the bond strength can be tested using a pull-out tester (≥3MPa); the coating continuity can be tested using an electric spark tester (voltage 9kV / mm); and the impermeability can be tested using a helium leak detection method (leakage rate ≤1×10). -6 Pa·m 3 / s).

[0044] According to the above-described solution of the present invention, compared with the conventional solution, the present invention can achieve the following beneficial effects: Non-reactive curing mechanism: Acrylic double bonds are cross-linked by photoinitiator, and polyurea resin physically entangles to form an interpenetrating network structure, achieving surface drying in 3 seconds without heating. Gradient reinforcement design: Cement particles are enriched at the bottom of the coating to improve adhesion, fibers are oriented on the surface to resist cracking, and nanofillers fill the micropores at the interface to improve impermeability. Open process parameters: Supports two modes: high-pressure airless spraying (pressure 18-25MPa) and air pressure spraying (0.6-0.8MPa), covering the needs of different engineering scenarios.

[0045] This invention overcomes the limitations of traditional heating processes by using a room-temperature curing polyurea-cement composite coating; it resolves the rigidity-flexibility contradiction through a gradient structure of cement bottom anchoring + fiber intermediate reinforcement + nano-surface sealing; and it eliminates isocyanate substances and achieves zero VOC emissions through a benzophenone photoinitiation system.

[0046] Furthermore, to achieve the above objectives, the present invention also provides a method for applying the above-mentioned protective coating, such as... Figure 1 As shown, it includes: (1) Surface preparation: Clean and repair the concrete surface; for example, control the surface roughness of the concrete to Ra≤2.0μm and the moisture content to 8-15%; (2) Material mixing: Before on-site construction, mix component A and component B in proportion and let them mature for 5-15 minutes; (3) Spraying construction: High-pressure airless spraying or air pressure spraying process is used to spray the mixture onto the treated concrete base surface to form a wet film; (4) Curing: Under natural light or auxiliary ultraviolet light, the coating will be surface dry in 3-8 seconds and cured at room temperature for 48-96 hours.

[0047] In this embodiment, the base surface treatment includes: cleaning with a high-pressure water gun (pressure ≥10MPa), controlling the moisture content of the base surface with a vacuum adsorption device, and pre-burying and sealing water pipes at the seepage points.

[0048] The maintenance phase includes covering with a breathable maintenance film and prohibiting water immersion or mechanical impact for 24 hours.

[0049] In this embodiment, when high-pressure airless spraying is used, the pressure of high-pressure airless spraying is 10-25MPa, the nozzle diameter is 0.4-0.8mm, and a single spraying forms a wet film thickness of 1.2-2.0mm. When using air pressure spraying, the pressure should be 0.5-1.0MPa, the nozzle diameter 1.0-2.0mm, the spray distance 30-60cm, and 2-3 coats should be applied to achieve a total thickness of 1.2-2.0mm.

[0050] After obtaining the protective coating using the above methods, the bond strength can be tested using a pull-out tester (≥3MPa); the coating continuity can be tested using an electric spark tester (voltage 9kV / mm); and the impermeability can be tested using a helium leak detection method (leakage rate ≤1×10). -6 Pa·m 3 / s).

[0051] According to the above-described solution of the present invention, compared with the prior art, the technical solution of the present invention has the following significant differences and technical difficulties: 1. Design Challenges of Non-Reactive Curing Systems: Existing polyurea systems mostly rely on isocyanate-amine reactions, requiring heating or rapid mixing, which poses risks of combustion and explosion and a narrow curing window. This invention abandons isocyanates and uses a benzophenone photoinitiator system to activate the crosslinking of acrylate double bonds. Simultaneously, the polyurea resin physically entangles to form an interpenetrating network, achieving surface drying in 3 seconds at room temperature. This system is extremely sensitive to light intensity, humidity, and oxygen inhibition. Achieving stable curing without relying on inert gas protection is a challenge that was difficult to foresee in related fields.

[0052] 2. Controllable Formation of Organic-Inorganic Gradient Structures: Traditional organic-inorganic composite coatings are mostly simple blends, easily leading to phase separation. This invention, through density difference control and spray shear induction, enables cement particles to accumulate at the bottom, fibers to be oriented in the middle layer, and nanofillers to be sealed on the surface, forming a spontaneous gradient structure. This mechanism is highly coupled with multiple variables such as material particle size, density, rheology, and spraying parameters, requiring system optimization to achieve and cannot be obtained through simple combination.

[0053] 3. Balancing zero VOC and high flexibility: Existing environmentally friendly coatings often sacrifice flexibility. This solution achieves a fracture elongation of ≥180% and can withstand dynamic cracks of 0.3mm in a solvent-free system, while maintaining VOC ≤30g / L. It combines environmental protection and mechanical properties, filling a technological gap.

[0054] 4. The open-ended formulation offers substitutability and adaptability: This solution supports flexible replacement of cement types (silicate / sulfoaluminate / geopolymer) and fiber types (basalt / polypropylene / steel fiber), with controllable performance fluctuations. This "modular" design approach is rarely seen in existing patents, demonstrating the universality and engineering adaptability of this invention.

[0055] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely one preferred embodiment of the invention and are only used to explain the invention. They do not limit the scope of protection of the invention. All other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0056] Example 1

[0057] Protective coatings for concrete structural surfaces include: Component A (mass percentage): Polyurea resin (40-60%); Acrylic ester copolymer (20-30%, glass transition temperature Tg≤-20℃); Flame retardant (5-10%, preferably a 3:1 mixture of aluminum hydroxide and zinc borate); Defoamer (0.2-0.5%, silicone-based); Leveling agent (0.1-0.3%, fluorocarbon modified polyether); Component B: Inorganic cementitious materials (5-15%, optional ordinary silicate, sulfoaluminate or geopolymer cement); Fiber (1-5%, basalt fiber, polypropylene fiber or steel fiber, length 1-6mm, aspect ratio 50-200); Nanofillers (3-8%, nano-SiO2 or CaCO3); Curing agent (1-3%, nonionic benzophenone derivative); Film-forming aid (2-4%, a 1:1 mixture of propylene glycol phenyl ether and dodecyl alcohol ester). Key performance indicators: Bond strength ≥ 3 MPa; Impermeability pressure ≥ 1.2 MPa; After 300 freeze-thaw cycles, the mass loss is ≤0.5%; The flame retardant rating reaches UL94 V-0.

[0058] Example 2

[0059] Application methods for protective coatings on concrete structural surfaces include: Step 1: Base Surface Treatment Surface flatness control: Use an angle grinder to cut protruding steel fibers to 2mm below the base surface; Cleaning and wetting: After rinsing with a high-pressure water gun (pressure ≥15MPa), remove standing water and control the moisture content of the base surface to 8-12%; Treatment of seepage points: Drill holes (Φ10mm) at active seepage points and bury PVC water pipes, and apply quick-setting cement slurry (water-cement ratio 0.3, initial setting time ≤3min) around the seepage points.

[0060] Step 2: Material Preparation Component A mixing: Add polyurea resin and acrylate copolymer to a planetary mixer, disperse at 800 rpm for 10 min, then add flame retardant and defoamer in sequence, and continue stirring for 20 min until the viscosity is ≤2000 mPa·s (25℃). Preparation of component B: Cement, fiber and nanofiller are dry mixed and then added to a ball mill and ground until D50≤50μm. Then, photoinitiator and film-forming aid are added and stirred at low speed (200rpm) for 5min. On-site preparation: Mix A:B = 4:1 (mass ratio), (modified) premix 0.5% coupling agent (KH-550) in component A, and use after maturation for 10 minutes.

[0061] Step 3: Spraying Application Option 1: High-pressure airless spraying Equipment parameters: High-pressure airless sprayer (pressure 18-25MPa, nozzle diameter 0.4-0.6mm, flow rate 2.5-3.5L / min). Spraying operation: Keep the spray gun 30-50cm away from the base surface, move at a speed of 0.8-1.2m / s, fan angle of 60-80°, and spray thickness of 1.5-2.0mm per coat; Precautions: Spraying must be continuous and uniform to avoid uneven thickness caused by interruptions. Spray overlap rate ≥ 50%.

[0062] Option 2: Air pressure spraying Equipment parameters: Use two-component air pressure spraying equipment (pressure 0.6-0.8MPa, nozzle diameter 1.2-1.8mm, mixing ratio 4:1). Spraying operation: The spray gun is at a 45-75° angle to the base surface, the moving speed is 0.5-0.8m / s, the thickness of a single spray is 0.8-1.2mm, and 2-3 sprays are required to achieve a total thickness of 2.3-2.7mm; Each coat should be applied 60-90 seconds apart, ensuring that the previous coat is completely dry before applying the next coat.

[0063] Step 4: Coating Maintenance Initial protection: Avoid water rinsing or mechanical impact within 30 minutes after spraying; Humidity control: Allow to cure naturally when the relative humidity is ≤85%; if the humidity is >85%, cover with a breathable curing film. Temperature management: 5-25℃ environment: curing time ≥72h; 25-40℃ environment: curing time ≥48h.

[0064] Example 3

[0065] Component A: 50% polyurea resin, 25% acrylate copolymer, 8% aluminum hydroxide / zinc borate (3:1), 0.3% defoamer, 0.2% leveling agent, 8.5% film-forming aid (propylene glycol phenyl ether and dodecyl alcohol ester 1:1), 7.5% carrier solvent (butyl acetate); Component B: 10% P·O 42.5 silicate cement, 2% polypropylene fiber (3mm), 5% nano-SiO2, 2% benzophenone derivative, 3% film-forming aid (propylene glycol phenyl ether and dodecyl alcohol ester 1:1), 78% carrier solvent (butyl acetate); A:B mixing ratio = 4:1 (mass ratio), wherein component A contains 0.5% premixed coupling agent (KH-550); Preparation and application: Components A and B were prepared as described above and allowed to mature for 10 minutes after mixing. High-pressure airless spraying (20 MPa, 0.5 mm nozzle) was then applied to the treated concrete slab (10% moisture content), with each coat being 1.8 mm thick and the total thickness 2.5 mm. Natural curing was then carried out for 72 hours (temperature 20 ± 5℃, humidity 65%). Test results: Drying time: 4 seconds; Bond strength (28d): 3.8 MPa; Impermeability pressure: 1.6 MPa; Elongation at break: 205%; Mass loss after 500 freeze-thaw cycles: 0.32%; Flame retardant rating: UL94 V-0; VOC content: 38 g / L; Example 4

[0066] Component A: 45% polyurea resin, 30% acrylate copolymer, 8% aluminum hydroxide / zinc borate (3:1), 0.3% defoamer, 0.2% leveling agent, 8.5% film-forming aid (propylene glycol phenyl ether and dodecyl alcohol ester 1:1), 7.5% carrier solvent (butyl acetate); Component B: P·O 42.5 silicate cement 5%, polypropylene fiber (3mm) 3%, nano SiO2 4%, nano montmorillonite 1%, benzophenone derivative 2%, film-forming aid (propylene glycol phenyl ether and dodecyl alcohol ester 1:1) 3%, carrier solvent (butyl acetate) 82%, combined; A:B mixing ratio = 4:1 (mass ratio), wherein component A contains 0.5% premixed coupling agent (KH-550); preparation and application methods are the same as in Example 3; Test results: The elongation at break has been increased to 235%; Tolerable crack width: 0.35mm; Bond strength: 3.2 MPa (still higher than the 3 MPa requirement); Impermeability pressure: 1.4 MPa.

[0067] Example 5

[0068] Component A: 48% polyurea resin, 25% acrylate copolymer, 8% aluminum hydroxide / zinc borate (3:1), 0.3% defoamer, 0.2% leveling agent, 8.5% film-forming aid (propylene glycol phenyl ether and dodecyl alcohol ester 1:1), and 9.5% carrier solvent (butyl acetate). Component B: Rapid-hardening sulfoaluminate cement 12%, polypropylene fiber (3mm) 2%, nano-SiO2 5%, benzophenone derivative 3%, film-forming aid (propylene glycol phenyl ether and dodecyl alcohol ester 1:1) 3%, carrier solvent (butyl acetate) 75%; A:B mixing ratio = 4:1 (mass ratio), wherein component A contains 0.5% premixed coupling agent (KH-550); Cover with a transparent curing film after construction.

[0069] The rest is the same as in Example 3; Cover with a transparent curing film after construction; Test results: Drying time: 3 seconds; 1-hour bond strength: 2.1 MPa; The seepage resistance pressure can reach 1.2 MPa in 24 hours; The curing time can be shortened to 36 hours (to reach 90% of the final strength).

[0070] Comparative Example 1: Commercially available two-component epoxy resin coating (containing isocyanate curing agent) with VOC > 200g / L was used, and the same thickness as in Example 1 was applied.

[0071] Surface drying time: >30 minutes; Bond strength (28d): 2.1 MPa; Crack tolerance: Water seepage occurs when the crack thickness is 0.15 mm; After 300 freeze-thaw cycles, significant pulverization occurred, with a mass loss of 1.8%.

[0072] Comparative Example 2: Only nanofillers and photoinitiators from components A and B are used; no cement or fiber is added.

[0073] The bond strength decreased to 1.5 MPa; The seepage resistance pressure is 0.7 MPa; It fractured when the crack was 0.2mm. Proving the gradient reinforcement effect of cement and fiber is crucial.

[0074] Comparative Example 3: Traditional thermal spraying of polyurea (containing isocyanate) requires heating to 60°C for application; Irritating gases are released during the construction process; High energy consumption and complex equipment; The elongation at break is approximately 150%, and the crack tolerance is 0.22 mm. The cost is about 50% higher than that of this invention.

[0075] Through comparative analysis of the above embodiments and comparative examples, it can be seen that the polyurea-cement-based protective coating system provided by the present invention: achieves film formation in seconds at room temperature, making construction convenient and safe; through gradient reinforcement design, it combines high adhesion, high impermeability, and excellent flexibility; it has outstanding environmental performance, with no release of toxic substances; the formula is open and flexible, and can be adjusted according to engineering needs, possessing good engineering adaptability.

[0076] The above description is merely a preferred embodiment of this application and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the inventive concept. For example, technical solutions formed by substituting the above-described features with (but not limited to) technical features with similar functions disclosed in this application.

[0077] It should be understood that the sequence number of each step in the invention and its embodiments does not absolutely imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

Claims

1. A protective coating for concrete structure surfaces, characterized in that, include: Component A and Component B; The A component and the B component are composed in a mass ratio of 3:1 to 5:1; Component A comprises: 40-70% polyurea polymer, 15-30% acrylate copolymer, 5-15% flame retardant, 0.1-0.8% defoamer, and 0.1-0.3% leveling agent; Component B comprises: 5-20% inorganic cementitious material, 1-8% fiber, 2-10% nanofiller, and 1-5% curing agent; The acrylate copolymer in component A undergoes a crosslinking reaction under light irradiation or redox conditions under the action of the curing agent in component B, enabling the mixed coating to achieve rapid surface drying. The acrylate copolymer in component A contains hydrophilic functional groups, which, together with the inorganic cementitious material in component B, form a stable organic-inorganic hybrid dispersion system under the action of a coupling agent; through high-speed dispersion and vacuum degassing processes, the water-based cement powder and organic resin are uniformly mixed. The curing agent comprises a composite system of photoinitiator and redox initiator, wherein the photoinitiator is used for rapid surface drying of the surface layer, and the redox initiator continuously initiates deep crosslinking of the acrylate copolymer under no light conditions, ensuring complete overall curing of the coating.

2. The protective coating for concrete structure surfaces according to claim 1, characterized in that, The polyurea polymer is at least one of aliphatic polyurea and polyaspartic acid ester, which forms a network structure of chemical crosslinking and physical entanglement with the acrylate copolymer under the action of a curing agent.

3. The protective coating for concrete structure surfaces according to claim 1, characterized in that, The inorganic cementitious material is selected from one or more of silicate cement, sulfoaluminate cement, and geopolymer.

4. The protective coating for concrete structure surfaces according to claim 1, characterized in that, The fiber is basalt fiber, polypropylene fiber, steel fiber or polyvinyl alcohol fiber, with a fiber length of 0.5-8mm, an aspect ratio of 30-300, and a content of 1-5%.

5. The protective coating for concrete structure surfaces according to claim 1, characterized in that, The nanofiller is one or more of nano-silica, nano-alumina, carbon nanotubes or montmorillonite, with a particle size ≤200nm and a dosage of 3-8%.

6. The protective coating for concrete structure surfaces according to claim 1, characterized in that, The flame retardant is at least two of the following: aluminum hydroxide, zinc borate, expanded graphite, and phosphorus-nitrogen synergistic flame retardant.

7. The protective coating for concrete structure surfaces according to claim 1, characterized in that, The curing agent is a nonionic photoinitiator or redox initiator, selected from one of the following: benzophenone derivatives or persulfate-ascorbic acid system, with a dosage of 1-3%.

8. The protective coating for concrete structure surfaces according to claim 1, characterized in that, The A component also contains 0.5-2% of a coupling agent, which is at least one of a silane coupling agent and a titanate coupling agent.

9. The method for applying the protective coating according to any one of claims 1-8, characterized in that, include: (1) Surface preparation: Clean and repair the concrete surface; (2) Material mixing: Before on-site construction, mix component A and component B in proportion and let them mature for 5-15 minutes; (3) Spraying construction: High-pressure airless spraying or air pressure spraying process is used to spray the mixture onto the treated concrete base surface to form a wet film; (4) Curing: Under natural light or auxiliary ultraviolet light, the coating will be surface dry in 3-8 seconds and cured at room temperature for 48-96 hours.

10. The method according to claim 9, characterized in that, The high-pressure airless spraying pressure is 10-25MPa, the nozzle diameter is 0.4-0.8mm, and a single spraying layer forms a wet film thickness of 1.2-2.0mm. The air pressure spraying is 0.5-1.0MPa, the nozzle diameter is 1.0-2.0mm, the spraying distance is 30-60cm, and 2-3 coats are applied to a total thickness of 1.2-2.0mm.

Images