Concrete self-cleaning long-life protective coating structure and preparation method thereof

Abstract

The invention relates to the technical field of road construction, in particular to a concrete self-cleaning long-life protective coating structure and a preparation method thereof.The coating structure comprises an interface reinforcing layer, a flexible anti-cracking layer, an anchoring breathable layer, an alkali-resisting repairing layer and a self-cleaning outer layer which are sequentially arranged on the outer side of a concrete wall from inside to outside; the interface reinforcing layer is subjected to bidirectional permeation bonding through an anchoring interface agent, the flexible anti-crack layer is formed by layered blade coating of polymer putty and comprises a coarse putty layer and a fine putty layer, the anchoring breathable layer is breathable primer copolymerized by acrylic acid-silicon-fluorine monomers, the alkali-resisting repairing layer is fluorine-silicon modified polyurethane finish paint, and the self-cleaning outer layer is fluorine-silicon composite finish-coat paint. Meanwhile, compared with a traditional paint system, the paint is more environmentally friendly, and compared with a single coating system, the paint has the longer service life.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of highway construction, and relates to a concrete self-cleaning long-life protective coating structure and a preparation method thereof. BACKGROUND

[0002] The research on highways and bridges is relatively in-depth in China, and the attention to accessory facilities is not high. The concrete crash wall of highways and bridges is usually made of low-grade concrete wall, and due to the special structure of the concrete wall, the wall has large internal pores, and the wall is more prone to damage in harsh environments. Therefore, how to improve the durability of the wall and ensure the crash level is very important for driving safety. The reinforced concrete wall is the mainstream application form of the crash barrier of the expressway, and the design service life is generally 15 years. Due to the long-term exposure to the external environment, the concrete wall is prone to early diseases such as cracking, spalling and steel corrosion caused by carbonation and water seepage under the repeated action of wind, sun and rain, which has become a common problem in the operation and maintenance of highways and bridges.

[0003] The concrete has the characteristics of porosity, neutralization and high adsorption. The conventional organic coating has a short service life and poor compatibility with the substrate, and it is very difficult to meet the long-term protection requirements. The coating often peels off after 1-2 years. The durability of concrete has a "five times law", that is, saving 1 dollar for steel protection in the design stage means that 5 dollars will be added for maintenance when the steel is corroded, and 25 dollars will be added for maintenance when the concrete cracks.

[0004] The information disclosed in this BACKGROUND section is only intended to enhance the understanding of the general background of the application, and should not be considered as recognition or implicit acknowledgment in any form that this information constitutes prior art known to those skilled in the art. SUMMARY

[0005] The first object of the present application is to provide a concrete self-cleaning long-life protective coating structure, which realizes water resistance, carbonation resistance, chloride ion resistance and other multi-effect protection, and is more environmentally friendly than traditional paint systems and has a longer service life than single coating systems.

[0006] The above technical object of the present application is achieved by the following technical scheme:

[0007] A self-cleaning, long-life protective coating structure for concrete includes an interface reinforcement layer, a flexible anti-cracking layer, an anchoring breathable layer, an alkali-resistant repair layer, and a self-cleaning outer layer, arranged sequentially from the inside out on the outside of the concrete wall. On the one hand, it can penetrate into the internal pores of the concrete and achieve molecular connection through internal anchoring, significantly improving the adhesion of the concrete substrate. On the other hand, it forms a waterproof layer with excellent hydrophobicity and self-cleaning functions on the outside of the concrete, which can effectively prevent the intrusion of external water, oxygen, chlorides, and harmful substances, inhibit the growth of mold and algae on the concrete surface, and thus improve the durability and structural safety of the concrete wall. The fluorosilicone homogeneous repair material and ultra-low surface energy self-cleaning and stain-resistant material in the present invention have a longer service life than traditional protective materials.

[0008] The interface reinforcement layer is bonded bidirectionally through the anchoring interface agent, creating a radial chain anchoring effect that firmly bonds the materials together and strengthens the concrete surface. Excellent wet adhesion strength in both dry and wet states effectively prevents peeling and shedding of the topcoat. The flexible, anti-cracking layer is formed by layering polymer putty, comprising a coarse putty layer and a fine sub-layer. The anchoring breathable layer is a breathable primer made from an acrylic-silicon-fluorine monomer copolymer. The alkali-resistant repair layer is a fluorosilicone-modified polyurethane topcoat, and the self-cleaning outer layer is a fluorosilicone composite topcoat.

[0009] Among them, the acrylic acid-silicon-fluoropolymer in the anchoring breathable layer penetrates into the anchoring repair matrix from the concrete pores and forms a waterproof and breathable membrane on the pore surface, preventing harmful media such as Cl - and SO4 2- The fluorine-silicon modified polyurethane in the alkali-resistant repair layer releases active silicate in the environment of pH>10, and reacts with Ca in the concrete. 2+ The reaction generates CSH gel, which repairs microcracks, improves fine defects on the concrete surface, enhances interfacial adhesion, and further protects against water and ion penetration. The fluorine-silicon composite material in the self-cleaning outer layer alters the surface wetting angle, forming a hydrophobic, anti-stick protective film with a lotus effect. Fluorine atoms, with their high electronegativity, form a dense electron cloud on the surface, absorbing ultraviolet rays and shielding the substrate, enhancing anti-aging and durability.

[0010] The present invention achieves a synergistically enhanced composite protection effect by setting three different functional silicon and fluorine mixtures in the flexible anti-cracking layer and forming gradient protection through physical shielding, chemical bonding and dynamic drainage.

[0011] As preferred, the anchoring interface agent is mixed and stirred evenly with cement:sand:acrylic resin interface agent in a mass ratio of 20-30:45-55:10-15. Among them, the particle size of cement is ≤80 μm, the particle size of sand is between 0.15-0.3 mm, and an electric device is needed to stir into a uniform thin slurry. Improve the bonding performance with the main body of concrete, in addition, can inhibit the base concrete to the coated concrete or mortar absorption moisture.

[0012] As preferred, the flexible anti-cracking layer adopts polymer putty to repair and level the concrete base layer, and the pulling strength can reach 2 MPa, improving the surface appearance and anti-cracking property of the concrete wall. The polymer putty is composed of cement, high molecular latex powder and aggregate, with a mass ratio of 45-58:12-20:30-40, and a water-cement ratio of 1:3. It can effectively inhibit the invasion of chloride and carbon dioxide, and improve the durability of concrete structures. It combines the flexibility of polymer and the rigidity of cement, meeting the requirements of the project for material compressive strength, bending strength, wear resistance, flexibility, adhesion to base material, low shrinkage, anti-cracking and other requirements. The high molecular latex powder is one or more of ethylene-vinyl acetate, vinyl acetate-ethylene copolymer and acrylate copolymer.

[0013] As preferred, the aggregate includes coarse aggregate and fine aggregate, the coarse aggregate and cement are mixed with high molecular latex powder to prepare coarse putty mixture, the fine aggregate and cement are mixed with high molecular latex powder to prepare fine putty mixture, and the amount ratio of coarse putty mixture to fine putty mixture is 1.2-1.8:0.6-1.0; the aggregate is basalt or limestone or quartz, the particle size of fine aggregate is <0.3 mm, and the particle size of coarse aggregate is 0.3-3 mm. The compressive strength of the flexible anti-cracking layer is ≥15 MPa, and the elastic modulus is ≤2 GPa.

[0014] As preferred, the anchoring air-permeable layer is prepared by free radical graft polymerization-surfactant-free emulsion process, the wet film thickness of the primer is 60-80 μm, and the amount is 0.17 kg / m 2 , the moisture permeability is ≤0.5 g / (m 2 ·h). The paint film has excellent weather resistance, good adhesion to concrete base material, can effectively protect the concrete from neutralization damage, and can also avoid cracks caused by the invasion of concrete.

[0015] As preferred, the preparation method of the anchoring air-permeable layer includes:

[0016] (1) Under nitrogen protection, 45-60 parts of butyl acrylate, 20-35 parts of methyl methacrylate, 15-25 parts of silane coupling agent and 10-18 parts of perfluorohexyl ethyl acrylate are dissolved in deionized water to form a pre-emulsion with a monomer mass concentration of 40%; 0.5-1.2 parts of ammonium persulfate is added as an initiator, the stirring rate is 300-500 rpm, and the pH is adjusted to 6.5-7.5;

[0017] (2) Add 10% of the pre-emulsion to the reactor, heat it to 75-80°C, and react for 30 minutes to generate the seed emulsion; the remaining pre-emulsion is added dropwise at constant pressure within 2 hours, maintaining the temperature at 80±2°C;

[0018] (3) adding 0.1-0.3 parts of sodium lauryl sulfate as a stabilizer and continuing the reaction for 3-4 hours until the conversion rate is greater than 98%; cooling to 40°C, adjusting the pH to 8.0-8.5 with aqueous ammonia, and filtering to obtain a soap-free emulsion with a solid content of 48±2%;

[0019] (4) After roller coating, allow to dry for 2 hours at 25°C, with a film thickness of 60-80 μm.

[0020] Preferably, the alkali-resistant repair layer is a fluorosilicone modified polyurethane topcoat, which is used to adjust base surface defects and enhance the adhesion of the self-cleaning surface layer. The wet film thickness is 75-100 μm and the surface tension is ≤25 mN / m.

[0021] Preferably, the preparation method of the alkali-resistant repair layer includes:

[0022] (1) adding 60-75 parts of polytetramethylene glycol and 25-35 parts of isophorone diisocyanate into a reaction kettle, reacting at 80-85° C. for 2 hours under nitrogen protection to obtain a prepolymer with an NCO content of 6.5-7.2%;

[0023] (2) adding 8-12 parts of fluorinated diol and 5-8 parts of silane coupling agent, and carrying out chain extension reaction at 70°C for 1.5 hours; adding 0.05-0.1 parts of dibutyltin dilaurate as catalyst until the NCO content is reduced to <0.2%;

[0024] (3) Two-pass roller coating, single-pass coating amount 0.2kg / m 2 , wet film thickness 30-50μm; total thickness 75-100μm, apply the second coat after the first coat is dried at 25℃ for 4h.

[0025] As a preferred self-cleaning outer layer, a fluorine-silicon composite topcoat is prepared by mixing silicone resin and fluorine resin in a mass ratio of 3:7, adding 0.5-1.0 parts of silane coupling agent, ball milling for 4-6 hours until uniform dispersion, and filtering to obtain the finished coating. The wet film thickness is 60-80μm, and the dosage is 0.13kg / m 2 , contact angle ≥110°, and surface energy ≤18mN / m. Fluororesin coatings, due to the high electronegativity of the introduced fluorine element and the strong carbon-fluorine bond, offer weather resistance, heat resistance, low-temperature resistance, and chemical resistance, as well as unique non-stick and low-friction properties. This creates a strong bond between the protective material and the concrete, forming a dense surface layer that blocks corrosive ions from entering the concrete.

[0026] Among them, the silicone resin is a mixture of 60-75 parts of phenyltrichlorosilane monomer, 22-30 parts of toluene organic solvent, and 5-10 parts of silanol. It forms silicon-oxygen bonds through hydrolysis and condensation reaction, and passivated impurities are separated by water washing, neutralization, and drying. It has good thermal stability, chemical resistance and flexibility.

[0027] Fluororesin is a fluorine-containing polymer formed by mixing 45-64 parts of polytetrafluoroethylene, 20-35 parts of polyvinylidene fluoride, 8-12 parts of a cross-linking agent, 4-8 parts of a light stabilizer, and 3-5 parts of an antioxidant, and heat-treated at 260-360°C. The fluorine atoms are bonded through high-energy epoxy bonds to form a stable helical structure, which has excellent heat resistance, chemical resistance, and weather resistance.

[0028] The mass ratio of silicon to fluorine in the anchoring breathable layer is 1-1.25:1; the mass ratio of silicon to fluorine in the alkali-resistant repair layer is 1:0.8-1.2; and the mass ratio of silicon to fluorine in the self-cleaning outer layer is 1:1-1.15.

[0029] The second main purpose of the present invention is to provide a method for preparing a self-cleaning and long-life protective coating structure for concrete, and to ensure the smooth coating of the self-cleaning and long-life protective coating structure for concrete through process optimization, thereby extending the service life of the concrete wall structure.

[0030] In order to achieve the above-mentioned object, the method for preparing a self-cleaning long-life protective coating structure for concrete proposed in the present invention comprises the following steps:

[0031] S1. To ensure a clean working surface, use a water gun to wash the concrete wall base, remove surface stains and damaged or loose parts, and repair damaged areas;

[0032] S2. Coating the anchoring agent to form an interface reinforcement layer, and then scraping the coarse putty mixture and the fine sub-mixture after the surface is dry;

[0033] Among them, the surface of the base surface is dried for about 30 minutes at 25℃. After the base surface treatment is completed, the first coat of coarse putty can be applied. After about 2 hours at 25℃, the first coat of coarse putty is dry, and the second coat of fine putty can be applied. The fine putty aggregate is finer than the coarse putty, and the dosage is 0.8kg / m 2 The scraping method is the same as the first layer of coarse putty. After the second layer of fine putty is dry, it is manually polished to make the surface smoother and eliminate tiny bubbles while repairing defects in time.

[0034] S3. Curing for 7 days until the tensile strength is ≥1MPa, then using a roller brush, apply a 60-80μm wet film thickness anchoring breathable layer on the surface of the formed flexible anti-cracking layer. The anchoring breathable layer can be surface-dried at 25°C for 2 hours.

[0035] S4. After the anchoring air-permeable layer is dry, roll-coat 75-100 pm wet film thickness of alkali-resistant repair layer in two passes, with a single coating amount of 0.2 kg / m 2 , 4 h at 25°C, and the first pass is dry, immediately roll-coat the second pass of topcoat in the same way, and the two passes of topcoat are of the same material;

[0036] S5. After the alkali-resistant repair layer is dry, roll-coat 60-80 pm wet film thickness of self-cleaning outer layer using a roller brush, which can be completely cured in 6 h at 25°C, to enhance the surface's stain resistance and self-cleaning ability, and obtain a concrete self-cleaning long-life protective coating structure after curing.

[0037] As preferred, in step S1, the concrete wall surface treatment includes the following steps:

[0038] S11: Use a high-pressure fan-shaped water gun nozzle, with a water gun pressure of 35-50 MPa, which is adjusted according to the aging degree of the concrete wall on site, and for a fluorocarbon-based original coating, the water pressure can be increased to 60 MPa; to avoid repeated water transportation and affect the construction progress, the water tank volume is not less than 2000 L;

[0039] S12: After repeated washing, for the original putty that is not washed clean, use a knocking and grinding method to process the surface to be generally flat to facilitate subsequent construction, and perform rust-proof treatment on the exposed reinforcing bars of the concrete wall, use a brush to apply a rust-proof agent, which is a non-polluting water-based rust-proof agent, use fast-curing cement mortar to repair damaged parts, and ensure that the surface is flat during repair, without height difference with the original surface (cured in 20 min at 25°C).

[0040] As preferred, in step S2, the flexible anti-cracking layer construction includes the following steps:

[0041] S21: Use a spatula and a trowel in combination during scraping to make the surface as smooth and flat as possible without obvious scraping marks;

[0042] S22: Do not expose the coarse putty to water before it is dry, and if it is exposed to heavy rain during the period, it needs to be scraped off and then scraped again;

[0043] S23: After the first pass of coarse putty is dry, perform the second pass of fine putty scraping construction.

[0044] As preferred, in step S3, the anchoring air-permeable primer construction includes the following steps:

[0045] S31: Roll-coat the anchoring air-permeable primer on the existing surface to penetrate into the flexible anti-cracking layer and form an air-permeable protective film;

[0046] S32: The amount of anchoring air-permeable primer is about 0.17 kg / m 2, that is, use a roller to adhere to the primer paint and roll it without dripping, with a wet film thickness of 60-80μm.

[0047] Compared with the prior art, the self-cleaning and long-life protective coating structure for concrete of the present invention has the following significant advantages:

[0048] The present invention achieves multi-effect protection such as water resistance, carbonization resistance, and chloride ion resistance. At the same time, it is more environmentally friendly than traditional paint systems and has a longer lifespan than single coating systems. The coating structure consists of an interface reinforcement layer, a flexible anti-cracking layer, an anchoring breathable layer, an alkali-resistant repair layer, and a self-cleaning outer layer. On the one hand, it can penetrate into the internal pores of the concrete, achieve molecular connection through internal anchoring, and greatly improve the adhesion of the concrete substrate; on the other hand, it forms a waterproof layer with good hydrophobicity and self-cleaning functions on the outside of the concrete, which can effectively prevent the intrusion of external water, oxygen, chlorides and harmful substances, inhibit the growth of mold and algae on the surface of the concrete, and thus improve the durability and structural safety of the concrete wall. The developed fluorosilicone homogeneous repair materials and ultra-low surface energy self-cleaning and stain-resistant materials have a longer service life than traditional protective materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0050] Figure 1 This is a schematic diagram of the structure of the self-cleaning and long-life protective coating for concrete according to the present invention.

[0051] Figure 2 This is a schematic cross-sectional view of the self-cleaning and long-life protective coating for concrete according to the present invention.

[0052] Figure numerals: 10, coating structure; 11, interface reinforcement layer; 12, flexible anti-cracking layer; 13, anchoring breathable layer; 14, alkali-resistant repair layer; 15, self-cleaning outer layer. DETAILED DESCRIPTION

[0053] To further illustrate the technical means and effectiveness of the present invention in achieving its intended purpose, the following describes in detail a self-cleaning, long-life protective coating structure for concrete and its preparation method, along with its specific implementation, features, and effectiveness. It should be understood that the specific embodiments described herein are intended only to illustrate the present invention and are not intended to limit the present invention.

[0054] The raw materials or reagents used in the Examples of the present invention and / or the Comparative Examples are all purchased from mainstream manufacturers in the market. If the manufacturer is not specified or the concentration is not specified, they are all analytically pure raw materials or reagents that can be routinely obtained. As long as they can play the expected role, there are no special restrictions. The instruments and equipment used in this embodiment are all purchased from major manufacturers in the market. As long as they can play the expected role, there are no special restrictions. If specific techniques or conditions are not specified in this embodiment, they are carried out according to the techniques or conditions described in the literature in this area or according to the product specifications.

[0055]

[0056]

[0057] Example 1

[0058] like Figure 1 and Figure 2 A self-cleaning and long-life protective coating structure for concrete is shown. The self-cleaning and long-life protective coating structure 10 for concrete consists of a 5mm interface reinforcement layer 11, a 3mm flexible anti-cracking layer 12, a 65μm anchoring breathable layer 13, an 80μm alkali-resistant repair layer 14 and a 70μm self-cleaning outer layer 15. On the one hand, it can penetrate into the internal pores of the concrete, realize molecular connection through internal anchoring, and greatly improve the adhesion of the concrete substrate; on the other hand, it forms a waterproof layer with good hydrophobicity and self-cleaning function on the outside of the concrete, which can effectively prevent the invasion of external water, oxygen, chlorides and harmful substances.

[0059] The interface reinforcement layer 11 is bonded by bidirectional penetration of the anchoring interface agent, generating a radial chain anchoring effect to firmly bond the materials together and strengthen the surface strength of the concrete. It has excellent wet adhesion strength in both dry and wet states, effectively preventing problems such as peeling and shedding of the surface coating. The flexible anti-cracking layer 12 is formed by layered scraping of polymer putty, including a coarse putty layer and a fine sub-layer. The anchoring breathable layer 13 is a breathable primer of acrylic acid-silicon-fluorine monomer copolymer, the alkali-resistant repair layer 14 is a fluorosilicone modified polyurethane topcoat, and the self-cleaning outer layer 15 is a fluorosilicone composite topcoat.

[0060] Among them, the acrylic acid-silicon-fluoropolymer in the anchoring breathable layer 13 penetrates into the anchoring repair matrix from the concrete pores and forms a waterproof breathable membrane on the pore surface, preventing the erosion of harmful media while not blocking the discharge of internal pore water. The fluorine-silicon modified polyurethane in the alkali-resistant repair layer 14 releases active silicate in an environment of pH>10, which reacts with Ca in the concrete. 2+The reaction generates CSH gel, which repairs microcracks, improves fine defects on the concrete surface, enhances interfacial adhesion, and further prevents water and ion penetration. The fluorine-silicon composite material in the self-cleaning outer layer 15 alters the surface wetting angle, forming a hydrophobic, anti-stick protective film that resembles a lotus leaf effect. Fluorine atoms, with their high electronegativity, form a dense electron cloud on the surface, absorbing ultraviolet rays and shielding the substrate, enhancing anti-aging and durability.

[0061] The anchoring interface agent is a mixture of cement, sand and acrylic resin in a mass ratio of 25:50:12, which is mixed and stirred evenly.

[0062] The flexible, crack-resistant layer 12 uses polymer putty to repair and level the concrete base, achieving a pull-out strength of up to 2 MPa, improving the concrete wall's surface appearance and crack resistance. The polymer putty is composed of cement, polymer latex powder, and aggregate in a mass ratio of 50:15:35, resulting in a water-cement ratio of 1:3. This effectively inhibits the intrusion of chlorides and carbon dioxide, improving the durability of concrete structures. Combining the flexibility of polymer with the rigidity of cement, it meets engineering requirements for compressive strength, flexural strength, abrasion resistance, a low elastic modulus, adhesion to the substrate, low shrinkage, and crack resistance. The polymer latex powder is ethylene vinyl acetate.

[0063] Specifically, the aggregate includes coarse aggregate and fine aggregate. The coarse putty mixture is prepared by mixing the coarse aggregate with cement and polymer latex powder, and the fine putty mixture is prepared by mixing the fine aggregate with cement and polymer latex powder. The ratio of the coarse putty mixture to the fine putty mixture is 1.5:0.8. The aggregate is basalt, limestone, or quartz. The particle size of the fine aggregate is less than 0.2 mm, and the particle size of the coarse aggregate is 0.3-1 mm. The flexible anti-cracking layer 12 has a compressive strength of ≥15 MPa and an elastic modulus of ≤2 GPa.

[0064] The preparation method of the anchoring breathable layer 13 includes:

[0065] (1) Under nitrogen protection, 50 parts of butyl acrylate, 25 parts of methyl methacrylate, 18 parts of KH570, and 12 parts of perfluorohexylethyl acrylate were dissolved in deionized water to form a pre-emulsion with a monomer mass concentration of 40%; 0.8 parts of ammonium persulfate was added as an initiator, the stirring rate was 400 rpm, and the pH was adjusted to 7.0;

[0066] (2) Add 10% of the pre-emulsion into the reactor, heat it to 75°C, and react for 30 minutes to generate the seed emulsion; the remaining pre-emulsion is added dropwise at constant pressure within 2 hours, maintaining the temperature at 80±2°C;

[0067] (3) adding 0.2 parts of sodium lauryl sulfate as a stabilizer and continuing the reaction for 3-4 hours until the conversion rate is greater than 98%; cooling to 40°C, adjusting the pH to 8.0 with aqueous ammonia, and filtering to obtain a soap-free emulsion with a solid content of 48%;

[0068] (4) After roller coating, allow to dry for 2 hours at 25°C, with a film thickness of 65 μm.

[0069] The preparation method of the alkali-resistant repair layer 14 includes:

[0070] (1) 70 parts of polytetramethylene ether glycol and 30 parts of isophorone diisocyanate were added to a reaction kettle, and reacted at 80° C. for 2 hours under nitrogen protection to obtain a prepolymer with an NCO content of 7.0%;

[0071] (2) Add 10 parts of fluorinated diol and 6 parts of KH550, and carry out chain extension reaction at 70°C for 1.5 hours; add 0.05 parts of dibutyltin dilaurate as catalyst until the NCO content drops to <0.2%;

[0072] (3) Two-pass roller coating, single-pass coating amount 0.2kg / m 2 , wet film thickness 40μm; apply the second coat after the first coat is dry at 25℃ for 4h, with a total thickness of 80μm.

[0073] The self-cleaning outer layer 15 is a fluorine-silicone composite topcoat. Specifically, silicone resin and fluororesin are mixed in a 3:7 mass ratio, 0.5 parts KH-570 is added, and the mixture is ball-milled for 5 hours until uniformly dispersed. The finished coating is then filtered to obtain the finished product. The silicone resin is a mixture of 70 parts phenyltrichlorosilane monomer, 25 parts toluene organic solvent, and 6 parts silanol. Through hydrolysis and polycondensation, silanol bonds are formed. Impurities are then separated and passivated through washing, neutralization, and drying. The resulting coating exhibits excellent thermal stability, chemical resistance, and flexibility. The fluororesin is a mixture of 50 parts polytetrafluoroethylene, 30 parts polyvinylidene fluoride, 10 parts crosslinker, 5 parts light stabilizer, and 3 parts antioxidant. After heat treatment at 300°C, the resulting fluorine-containing polymer is formed. Fluorine atoms are bonded through high-energy epoxy bonds, forming a stable helical structure with excellent heat resistance, chemical resistance, and weather resistance.

[0074] A method for preparing a self-cleaning, long-life protective coating structure for concrete comprises the following steps:

[0075] In order to achieve the above-mentioned object, the method for preparing a self-cleaning long-life protective coating structure for concrete proposed in the present invention comprises the following steps:

[0076] S1. To ensure a clean working surface, use a water gun to wash the concrete wall base, remove surface stains and damaged or loose parts, and repair damaged areas;

[0077] S2 coating anchoring interface agent to form an interface reinforcement layer 11, the surface is dried and then scraped coarse putty mixture and fine sub-mixture;

[0078] Wherein, after the base surface treatment is completed, the first rough putty scraping construction can be carried out, and after the first rough putty surface is dry, the second fine putty scraping construction can be carried out, wherein the fine putty aggregate is relatively fine compared with the rough putty, and the usage is 0.8 kg / m 2 , the scraping method is the same as that of the first layer of rough putty, and after the second fine putty surface is dry, manual polishing is carried out to make the surface more smooth and flat, eliminate small bubbles, and timely repair defects;

[0079] S3. After 7 days of curing, the tensile strength is ≥1 MPa, and a 60-80 μm wet film thickness of the anchoring breathable layer 13 is rolled and coated on the surface of the formed flexible anti-cracking layer 12 using a roller brush;

[0080] S4. After the anchoring breathable layer 13 is dry, the alkali-resistant repair layer 14 is rolled and coated in two passes with a wet film thickness of 80 μm, and the single coating amount is 0.2 kg / m 2 , the wet film thickness is 40 μm, and after the first pass is dry, the second pass of topcoat is immediately rolled and coated in the same way, and the two topcoats are the same;

[0081] S5. After the alkali-resistant repair layer 14 is dry, the self-cleaning outer layer 15 is rolled and coated using a roller brush with a wet film thickness of 60-80 μm, enhancing the surface's stain resistance and self-cleaning ability, and after curing, the concrete self-cleaning long-life protective coating structure 10 is obtained.

[0082] Example 2

[0083] As shown in Figure 1 and Figure 2 , a concrete self-cleaning long-life protective coating structure 10 is composed of a 10 mm interface reinforcing layer 11, a 5 mm flexible anti-cracking layer 12, a 75 μm anchoring breathable layer 13, a 75 μm alkali-resistant repair layer 14, and an 80 μm self-cleaning outer layer 15.

[0084] The anchoring interface agent is mixed and stirred uniformly according to a mass ratio of cement:sand:acrylic resin interface agent of 26:51:12.

[0085] The flexible anti-cracking layer 12 uses polymer putty to repair and level the concrete base layer, and the polymer putty is composed of cement, high molecular latex powder, and aggregate, with a mass ratio of 50:15:35 and a water-cement ratio of 1:3. The high molecular latex powder is ethylene-vinyl acetate.

[0086] The preparation method of the anchoring breathable layer 13, the alkali-resistant repair layer 14, the self-cleaning outer layer 15, and the concrete self-cleaning long-life protective coating structure is the same as that of Example 1, which will not be repeated here.

[0087] Example 3

[0088] As shown in Figure 1 and Figure 2A concrete self-cleaning long-life protective coating structure 10 is shown, which is composed of an 8 mm interface reinforcing layer 11, an 8 mm flexible anti-cracking layer 12, an 80 μm anchoring and air-permeable layer 13, a 95 μm alkali-resistant repair layer 14, and a 65 μm self-cleaning outer layer 15.

[0089] The anchoring interface agent is mixed and stirred uniformly by cement: sand: acrylic resin interface agent at a mass ratio of 26:51:12.

[0090] The flexible anti-cracking layer 12 is used to repair and level the concrete base layer with polymer putty, which is composed of cement, high molecular latex powder, and aggregate at a mass ratio of 48:13:34, and the water-cement ratio is 1:3. The high molecular latex powder is ethylene-vinyl acetate.

[0091] The preparation methods of the anchoring and air-permeable layer 13, the alkali-resistant repair layer 14, the self-cleaning outer layer 15, and the concrete self-cleaning long-life protective coating structure are the same as in Example 1, and will not be repeated here.

[0092] Example 4

[0093] As shown in Figure 1 and Figure 2 A concrete self-cleaning long-life protective coating structure 10 is shown, which is composed of an 8 mm interface reinforcing layer 11, an 8 mm flexible anti-cracking layer 12, an 80 μm anchoring and air-permeable layer 13, a 95 μm alkali-resistant repair layer 14, and a 65 μm self-cleaning outer layer 15.

[0094] The anchoring interface agent is mixed and stirred uniformly by cement: sand: acrylic resin interface agent at a mass ratio of 26:51:12.

[0095] The flexible anti-cracking layer 12 is used to repair and level the concrete base layer with polymer putty, which is composed of cement, high molecular latex powder, and aggregate at a mass ratio of 48:13:34, and the water-cement ratio is 1:3. The high molecular latex powder is ethylene-vinyl acetate.

[0096] The preparation methods of the anchoring and air-permeable layer 13, the alkali-resistant repair layer 14, the self-cleaning outer layer 15, and the concrete self-cleaning long-life protective coating structure are the same as in Example 1, and will not be repeated here.

[0097] Example 5

[0098] As shown in Figure 1 and Figure 2 A concrete self-cleaning long-life protective coating structure 10 is shown, which is composed of an 8 mm interface reinforcing layer 11, an 8 mm flexible anti-cracking layer 12, an 80 μm anchoring and air-permeable layer 13, a 95 μm alkali-resistant repair layer 14, and a 65 μm self-cleaning outer layer 15.

[0099] The anchoring interface agent is mixed and stirred uniformly according to a mass ratio of cement:sand:acrylic resin interface agent of 25:52:12.

[0100] The flexible anti-cracking layer 12 is used to repair and level the concrete base layer by using polymer putty composed of cement, high molecular latex powder, and aggregate, with a mass ratio of 50:17:38 and a water-cement ratio of 1:3. The high molecular latex powder is ethylene-vinyl acetate.

[0101] The preparation method of the anchoring air-permeable layer 13, the alkali-resistant repair layer 14, the self-cleaning outer layer 15, and the concrete self-cleaning long-life protective coating structure is the same as that of Example 1, and will not be repeated here.

[0102] Comparative Example 1

[0103] A concrete self-cleaning long-life protective coating structure, which is composed of a 5mm interface reinforcing layer, a 3mm flexible anti-cracking layer, a 65μm anchoring air-permeable layer, an 80μm alkali-resistant repair layer, and a 70μm self-cleaning outer layer.

[0104] The anchoring interface agent is mixed and stirred uniformly according to a mass ratio of cement:sand:acrylic resin interface agent of 15:60:8.

[0105] The flexible anti-cracking layer is used to repair and level the concrete base layer by using polymer putty composed of cement, high molecular latex powder, and aggregate, with a mass ratio of 50:25:35 and a water-cement ratio of 1:1. The high molecular latex powder is ethylene-vinyl acetate.

[0106] The preparation method of the anchoring air-permeable layer, the alkali-resistant repair layer, the self-cleaning outer layer, and the concrete self-cleaning long-life protective coating structure is the same as that of Example 1, and will not be repeated here.

[0107] Comparative Example 2

[0108] A concrete self-cleaning long-life protective coating structure, which is composed of a 5mm interface reinforcing layer, a 3mm flexible anti-cracking layer, a 20μm anchoring air-permeable layer, a 20μm alkali-resistant repair layer, and a 20μm self-cleaning outer layer.

[0109] The anchoring interface agent is mixed and stirred uniformly according to a mass ratio of cement:sand:acrylic resin interface agent of 25:50:12.

[0110] The flexible anti-cracking layer is used to repair and level the concrete base layer by using polymer putty composed of cement, high molecular latex powder, and aggregate, with a mass ratio of 50:15:35 and a water-cement ratio of 1:3. The high molecular latex powder is ethylene-vinyl acetate.

[0111] The preparation method of the anchoring breathable layer, alkali-resistant repair layer, self-cleaning outer layer, and concrete self-cleaning long-life protective coating structure is the same as in Example 1 and will not be repeated here.

[0112] Performance test table

[0113]

[0114] As shown in the table above, in the present invention, Examples 1-5 achieve a balance of mechanical, weather resistance, and protective properties through precise ratio control and functional layer thickness design.

[0115] The proportion and water-cement ratio of Comparative Example 1 are unbalanced, and the cement and acrylic acid are insufficient, which makes the anchoring effect ineffective. The water-cement ratio of the flexible anti-cracking layer is 1:1 (too thin), and the porosity increases to form water absorption channels, which increases the water absorption rate. The interface stratification causes ultraviolet rays to directly hit the substrate, accelerating photo-oxidation, and reducing the anti-aging time and light retention rate.

[0116] In Comparative Example 2, the anchoring breathable layer cannot disperse stress and easily expands to form microcracks. The functional layer is not thick enough to repair substrate defects, and the interface bonding is weakened, which leads to systemic defects such as interface failure, increased permeability, and accelerated aging.

[0117] Those skilled in the art will appreciate that the present invention is not limited to the foregoing embodiments. The foregoing embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A concrete self-cleaning long-life protective coating structure, characterized in that: It includes an interface reinforcement layer, a flexible anti-cracking layer, an anchoring breathable layer, an alkali-resistant repair layer and a self-cleaning outer layer arranged on the outside of the concrete wall from the inside to the outside; The interface reinforcement layer is bonded by bidirectional penetration of the anchoring interface agent, the flexible anti-cracking layer is formed by layered scraping of polymer putty, the anchoring breathable layer is a breathable primer of acrylic acid-silicon-fluorine monomer copolymer, the alkali-resistant repair layer is a fluorine-silicon modified polyurethane topcoat, and the self-cleaning outer layer is a fluorine-silicon composite topcoat.

2. The concrete self-cleaning long-life protective coating structure according to claim 1 is characterized in that: The anchoring interface agent is prepared by mixing cement, sand and the interface agent in a mass ratio of 20-30:45-55:10-15 and stirring them evenly.

3. The self-cleaning long-life protective coating structure for concrete according to claim 1, characterized in that: The polymer putty is composed of cement, polymer latex powder and aggregate, with a mass ratio of 45-58:12-20:30-40 and a water-cement ratio of 1:

3.

4. The concrete self-cleaning long-life protective coating structure according to claim 3 is characterized in that: The aggregate includes coarse aggregate and fine aggregate. The coarse aggregate is mixed with cement and polymer latex powder to prepare a coarse putty mixture. The fine aggregate is mixed with cement and polymer latex powder to prepare a fine sub-mixture. The usage ratio of the coarse putty mixture to the fine sub-mixture is 1.2-1.8:0.6-1.

0.

5. The concrete self-cleaning long-life protective coating structure according to claim 3 is characterized in that: The polymer latex powder is one or more of ethylene-vinyl acetate, vinyl acetate-ethylene copolymer, and acrylate copolymer.

6. The concrete self-cleaning long-life protective coating structure according to claim 1, characterized in that: The anchoring breathable layer is prepared by free radical graft polymerization-soap-free emulsion process, the primer wet film thickness is 60-80 μm, and the dosage is 0.17 kg / m 2 , moisture permeability ≤0.5g / (m 2 ·h).

7. The concrete self-cleaning long-life protective coating structure according to claim 1, characterized in that: The alkali-resistant repair layer is applied in two coats, with a wet film thickness of 75-100 μm and a surface tension of ≤25 mN / m.

8. The self-cleaning long-life protective coating structure for concrete according to claim 1, characterized in that: The wet film thickness of the self-cleaning outer layer is 60-80 μm, and the dosage is 0.13 kg / m 2 , contact angle ≥110°, surface energy ≤18mN / m.

9. The method for preparing a self-cleaning, long-life protective coating structure for concrete according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1. Use a water gun to wash the concrete wall base to remove surface stains and damaged and loose parts, and repair damaged parts; S2. Coating the anchoring agent to form an interface reinforcement layer, and then scraping the coarse putty mixture and the fine sub-mixture after the surface is dry; S3. Curing for 7 days until the tensile strength is ≥1MPa, and then rolling the anchoring breathable layer on the surface of the flexible anti-cracking layer; S4. After the anchoring breathable layer is completely dry, apply the alkali-resistant repair layer in two passes; S5. After the alkali-resistant repair layer is completely dry, a self-cleaning outer layer is rolled on. After curing, a self-cleaning, long-life protective coating structure for concrete is obtained.

10. The method for preparing a self-cleaning long-life protective coating structure for concrete according to claim 9, characterized in that: In step S1, the concrete wall base surface treatment includes the following steps: S11: Use high-pressure fan-shaped water gun nozzles, and the water gun pressure is adjusted according to the aging degree of the concrete wall on site; S12: After repeated flushing, perform anti-rust treatment on the exposed reinforcement of the concrete wall and use fast-setting cement mortar to repair the damaged areas. There must be no height difference between the repaired area and the original base surface.

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