A water-repellent and breathable carbon-mineralized protective coating, and a preparation method and application thereof

Abstract

The present application relates to a kind of water-repellent breathable carbon mineralization protective coating and its preparation method and application, by mass parts, including the following components: γ-dicalcium silicate powder: 3~6 parts;Carbonization template: 0.3~0.9 parts;Crystal form regulator: 0.8~1.8 parts;Surface hydrophobic modifier: 0.01~0.1 parts;Water-retention and pore control agent: 2~5 parts.The present application water-repellent breathable carbon mineralization protective coating is based on the carbonization reaction of γ-dicalcium silicate, induces aragonite crystal form growth by crystal form regulator, gives coating surface hydrophobicity by surface hydrophobic modifier, improves pore and water retention by water-retention and pore control agent, can realize the function of water (liquid) blocking not gas (vapor) blocking, give consideration to water-repellent and breathability, effectively avoid the problem that coating is bubbled and falls off due to internal steam pressure is too large, especially suitable for coastal splash zone and tidal zone concrete protection.

Description

Technical Field

[0001] This invention relates to the field of surface protection technology for building materials, and in particular to a water-repellent and breathable carbon mineralized protective coating, its preparation method, and its application. Background Technology

[0002] Concrete structures in coastal areas, especially those located in splash zones and tidal zones, are subject to long-term damage from wet-dry cycles, salt spray erosion, and seawater scouring. Chloride and sulfate ions readily penetrate the concrete, causing cracking and steel corrosion, severely impacting the structure's durability and safety.

[0003] Traditional protective measures mainly include organic coatings (such as epoxy resins and polyurethane) and ordinary cement-based mortar. While organic coatings have good density, they often have poor air permeability; the vapor pressure generated when moisture inside the concrete evaporates due to heat is difficult to release, easily leading to blistering and peeling of the coating. Furthermore, organic materials have poor weather resistance under strong ultraviolet radiation and salt spray environments, are prone to aging and failure, and their bonding strength with the concrete substrate weakens over time. Although ordinary cement-based materials have good compatibility with the substrate, their high porosity makes them unable to effectively block chloride ion erosion, and they lack hydrophobic properties, resulting in high water absorption.

[0004] Therefore, it is difficult to achieve both water repellency and breathability in existing protective coatings, which has become an urgent problem to be solved in the field of marine concrete protection. Summary of the Invention

[0005] The purpose of this invention is to overcome the above-mentioned technical deficiencies and provide a water-repellent and breathable carbon mineralized protective coating, its preparation method and application, thereby solving the technical problem that it is difficult to achieve both water repellency and breathability in the existing protective coating.

[0006] To achieve the above-mentioned technical objectives, the technical solution provided by this invention is as follows: In a first aspect, the present invention provides a water-repellent and breathable carbon mineralized protective coating, comprising the following components by weight: 3-6 parts of γ-dicalcium silicate powder; 0.3-0.9 parts of carbonized template; 0.8-1.8 parts of crystal form regulator; 0.01-0.1 parts of surface hydrophobic modifier; and 2-5 parts of water-retaining and pore-regulating agent.

[0007] Secondly, the present invention provides a method for preparing a water-repellent and breathable carbon mineralized protective coating, comprising the following steps: S1, under stirring conditions, γ-dicalcium silicate powder, carbonization template, crystal form regulator, surface hydrophobic modifier and water-retaining and pore-regulating agent are mixed evenly to obtain a slurry; S2, the slurry is coated on the surface of a concrete substrate and left to stand to form a wet film; S3, the wet film is carbonized and cured to obtain a water-repellent and breathable carbon mineralized protective coating.

[0008] Thirdly, the present invention provides an application of the above-mentioned water-repellent and breathable carbon mineralized protective coating in marine concrete protection.

[0009] Compared with the prior art, the beneficial effects of the present invention include: This invention relates to a water-repellent and breathable carbonized protective coating based on the carbonization reaction of dicalcium silicate. It induces aragonite crystal growth through a crystal form regulator, imparts hydrophobicity to the coating surface through a surface hydrophobic modifier, and improves porosity and water retention through water-retaining and pore-regulating agents. This results in an inorganic-organic composite coating with high weather resistance and high strength. Furthermore, the coating possesses mesoporous breathing channels with pore sizes between water vapor molecules and liquid water droplets. This effectively blocks the penetration of liquid water and harmful ions while allowing internal water vapor to escape effectively, achieving water (liquid) blocking but not gas (vapor) blocking. It balances water repellency and breathability, effectively preventing the coating from bubbling and peeling off due to excessive internal vapor pressure. It is particularly suitable for concrete protection in coastal splash zones and tidal zones. Detailed Implementation

[0010] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0011] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention; the terms “comprising” and “having”, and any variations thereof, in the specification and claims of this invention are intended to cover non-exclusive inclusion.

[0012] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0013] In the field of marine concrete protection, organic coatings are relatively dense, but their strong sealing properties can easily lead to the accumulation of internal moisture, which can cause the coating to peel off. At the same time, organic coatings have poor weather resistance, are prone to aging, and their bonding strength with the concrete substrate decreases over time, which can also cause the coating to fall off. While ordinary cement-based materials have good compatibility with the substrate, their high porosity makes them unable to prevent the intrusion of external liquid seawater and harmful ions.

[0014] Based on this, the present invention is established.

[0015] In a first aspect, the present invention provides a water-repellent and breathable carbon mineralized protective coating, comprising the following components by weight: γ-Dicalcium silicate powder: 3-6 parts; Carbonized template: 0.3–0.9 parts; Crystal form regulator: 0.8–1.8 parts; Surface hydrophobic modifier: 0.01–0.1 parts; Water-retaining and pore-regulating agent: 2-5 parts.

[0016] This invention relates to a protective coating based on the carbonization reaction of dicalcium γ-silicate. The carbonization template enhances the coating's stability, prevents sedimentation, and induces calcium ion dissolution. A crystal form regulator induces aragonite crystal growth, a surface hydrophobic modifier imparts hydrophobicity to the coating surface, and water-retaining and pore-regulating agents improve porosity and retain water. This results in an inorganic-organic composite coating with high weather resistance and high strength. Furthermore, this coating possesses mesoporous breathing channels with pore sizes between water vapor molecules and liquid water droplets. These channels effectively block the penetration of liquid water and harmful ions while allowing internal water vapor to escape effectively, achieving a water (liquid) barrier without blocking gas (vapor). This effectively prevents the coating from bubbling and peeling off due to excessive internal vapor pressure. This invention has significant engineering implications for solving concrete protection problems in harsh coastal environments.

[0017] In some embodiments, the carbonization template includes a styrene-acrylic emulsion, a pure acrylic emulsion, or a silicone-acrylic emulsion, with a solid content of 40-50% and a viscosity of 80-3000 mPa·s. This invention uses styrene-acrylic emulsions, etc., as a carbonization template, and also as a film-forming aid to promote coating film formation.

[0018] In some embodiments, the crystal form regulator comprises a magnesium chloride solution of 0.05–0.2 mol / L.

[0019] In some embodiments, the surface hydrophobic modifier includes one or a mixture of several of polydimethylsiloxane, methyl hydrogen silicone oil, isobutyltriethoxysilane, and n-octyltriethoxysilane.

[0020] In some embodiments, the water-retaining and pore-regulating agent includes liquid sodium silicate, liquid potassium silicate, or liquid lithium silicate; wherein liquid sodium silicate is preferred, the modulus is preferably 3.0 to 3.5, and the solid content is preferably 30 wt% to 40 wt%.

[0021] Secondly, the present invention provides a method for preparing a water-repellent and breathable carbon mineralized protective coating, comprising the following steps: S1, under stirring conditions, γ-dicalcium silicate powder, carbonization template, crystal form regulator, surface hydrophobic modifier and water-retaining and pore-regulating agent are mixed evenly to obtain slurry; S2, apply the slurry to the surface of the concrete substrate and let it stand to form a wet film; S3, the wet film is carbonized and cured to obtain a water-repellent and breathable carbon mineralized protective coating.

[0022] In some embodiments, step S1, the slurry preparation process specifically includes: Under stirring conditions of 300–500 r / min, γ-dicalcium silicate powder was mixed with a carbonized template and stirred for 1–3 min to obtain a homogeneous mixture A. Under stirring conditions of 600–1000 r / min, a crystal form regulator was added to mixture A, and the mixture was stirred for 5–10 min until homogeneous to obtain mixture B; Under stirring conditions of 2000–3000 r / min, a surface hydrophobic modifier was added to mixture B, and the mixture was stirred for 10–15 min to obtain mixture C. Under stirring conditions of 400–600 r / min, water-retaining and pore-regulating agents are added to mixture C, and the mixture is stirred for 1–2 min to obtain a slurry.

[0023] This invention involves first slowly adding a carbonization template (which also acts as a film-forming aid) under low-speed (300–500 r / min) stirring conditions to mix the two and prevent emulsion demulsification. Then, the stirring speed is increased to medium speed (600–1000 r / min) and a crystal form regulator is added to induce the carbonization product to transform into the aragonite crystal form. Next, the stirring speed is adjusted to high-speed shear mode (2000–3000 r / min) to uniformly disperse the surface hydrophobic modifier and form a micro-emulsion, ensuring uniform hydrophobicity after coating curing. After completing the high-speed dispersion and homogenization of the above raw materials, the stirring speed is reduced back to low speed (400–600 r / min), and water-retaining and pore-regulating agents are added to prevent the introduction of air bubbles and form a uniform, non-agglomerated slurry. The water-retaining and pore-regulating agents construct a transient water-retaining network in the slurry system to maintain the liquid phase environment required for the subsequent carbonization reaction.

[0024] In some embodiments, in step S2, the concrete substrate is pretreated before being coated with slurry; the pretreatment involves removing floating dust, oil stains and loose attachments, and then spraying water to make it reach a saturated and surface-dry state.

[0025] It should be noted that the removal of floating dust, oil stains, and loose attachments is a routine operation and can be carried out using a high-pressure water gun or a wire brush.

[0026] In some embodiments, in step S2, the coating method includes scraping, which specifically includes: scraping a base layer with a thickness of 80 to 120 μm, and then scraping a top layer to form a wet film; the total thickness of the wet film is 200 to 550 μm.

[0027] Furthermore, the coating is performed using a stainless steel toothed scraper, with the scraper angle ranging from 45° to 60°. During the initial coat, significant force is required to expel air from the pores; the top coat is then smoothed and polished; the preferred total wet film thickness is 300–500 μm.

[0028] In some embodiments, in step S2, the standing is performed for 30 to 60 minutes in a natural environment; wherein the natural environment preferably has a temperature of 20 to 25°C and a humidity of >50%.

[0029] In some embodiments, the carbonization curing conditions in step S3 include: carbonization curing in a carbonization kettle, with CO2 gas introduced to a pressure of 0.1 to 0.3 MPa, a curing temperature of 28 to 32°C, and a curing time of 12 to 24 hours.

[0030] Understandably, the CO2 gas introduced can be industrial grade or high-purity CO2 gas with a purity of not less than 99.9%; after the carbonization curing is completed, the pressure is released to atmospheric pressure according to the standard operation, and then the carbonization kettle is opened to take out the target product.

[0031] Thirdly, the present invention provides an application of the above-mentioned water-repellent and breathable carbon mineralized protective coating in marine concrete protection.

[0032] The main mechanism of action and advantages of this invention are as follows: (1) This invention utilizes industrial by-products or low-energy raw materials (dicalcium γ-silicate) and CO2 mineralization and storage technology, which not only consumes greenhouse gases, but also makes the reaction process non-toxic, harmless, and free of VOC emissions. Compared with traditional water curing, carbonization curing significantly shortens the curing cycle (high strength can be achieved in 12 to 24 hours); (2) The present invention introduces water-retaining and pore-regulating agents such as liquid sodium silicate, and uses its excellent water retention to build a water-locking network inside the slurry, which effectively inhibits the evaporation of water during the carbonization process, maintains the liquid phase environment necessary for the gas-liquid-solid reaction, and ensures the carbonization depth of γ-dicalcium silicate. (3) The silica gel skeleton generated in situ after carbonization reaction by water-retaining and pore-regulating agents such as liquid sodium silicate, combined with the hydrophobic modification of surface hydrophobic modifiers such as polydimethylsiloxane and the close packing of aragonite crystals, constructs a unique mesoporous breathing channel. The pore size of this channel is between water vapor molecules and liquid water droplets, thus achieving the function of blocking water (liquid) but not gas (vapor), avoiding the coating from bubbling and peeling off due to excessive internal vapor pressure of the substrate, which is particularly suitable for humid coastal environments; (4) The aragonite-type calcium carbonate generated by magnesium chloride regulation has higher hardness and strength than ordinary calcite. Combined with the curing effect of components such as sodium silicate, the coating performs excellently in resisting wave erosion and sand and gravel abrasion.

[0033] The present invention will be further described in detail below through specific embodiments. It should be noted that the embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in this field or in accordance with the product instructions. Reagents or instruments used that do not specify the manufacturer are all conventional products that can be obtained commercially.

[0034] The styrene-acrylic emulsion used is model BS-104 (Shandong Yousuo); the polydimethylsiloxane has a viscosity of 1000 mPa·s and is branded Adamas-beta; the isobutyltriethoxysilane has a concentration of 98% and is branded Ron.

[0035] Example 1 A method for preparing a water-repellent and breathable carbon mineralized protective coating includes the following steps: S1. First, prepare the slurry by weighing 5 parts of γ-dicalcium silicate powder and placing it in a mixing container. Turn on the mixer and slowly add 0.6 parts of styrene-acrylic emulsion at a low stirring speed of 400 r / min, stirring for 3 minutes until uniformly mixed. Then, increase the stirring speed to 800 r / min and add 1.35 parts of 0.1 mol / L magnesium chloride aqueous solution, stirring for 5 minutes to initially wet the powder and use magnesium chloride to induce the transformation of the carbonization products to the aragonite crystal form. Then, adjust the equipment to 3... In a high-speed shearing mode of 000 r / min, add 0.05 parts of polydimethylsiloxane and stir for 10 min. Continue shearing to form a micro-emulsion in the slurry to ensure uniform hydrophobicity after coating curing. After completing the high-speed dispersion and homogenization of the above components, adopt a step-by-step post-addition process, reduce the stirring speed to 500 r / min, and finally add 3 parts of liquid sodium silicate with a modulus of 3.3 and a solid content of 34 wt%. Stir for 1 minute to avoid introducing air bubbles until a uniform, non-agglomerated slurry is formed.

[0036] S2. After the slurry preparation is completed, the substrate is treated and coated. A high-pressure water gun is used to remove floating dust, oil stains and loose attachments from the surface of the concrete substrate. Then, the substrate is sprayed with water to achieve a saturated and surface-dry state. The prepared slurry is applied to the substrate surface by scraping with a stainless steel toothed scraper at a controlled angle of 45°. The construction is divided into two steps. The first step is to apply a base coat with a thickness of about 100μm and press it firmly to squeeze out the air in the pores. The second step is to apply a top coat, smooth and finish it, and control the total wet film thickness to about 500μm. After coating, the sample is left to stand for 30 minutes in a natural environment at 20℃ and humidity greater than 50%.

[0037] S3. Finally, carbonization curing is carried out. The settled sample is placed in a stainless steel carbonization reactor, the air inlet valve is opened, and CO2 gas with a purity of 99.9% is introduced. The reactor is heated by water circulation through the reactor jacket to maintain the temperature inside the reactor at 30°C. The pressure reducing valve is adjusted to maintain the pressure inside the reactor at 0.2MPa. The carbonization reaction is carried out for 12 hours under the above temperature and pressure conditions. After the reaction is completed, the pressure is slowly released at a rate of 0.01MPa / min until it reaches atmospheric pressure. The sample is then removed, and the water-repellent and breathable carbon mineralized protective coating is obtained.

[0038] Example 2 Compared with Example 1, the only difference is the raw material ratio: 4 parts γ-dicalcium silicate powder, 0.4 parts styrene-acrylic emulsion, 1.15 parts crystal form regulator (0.1 mol / L magnesium chloride aqueous solution), 0.07 parts surface hydrophobic modifier (polydimethylsiloxane), and 5 parts water retention and porosity improver (liquid sodium silicate); and the pressure inside the reactor is maintained at 0.1 MPa during the carbonization curing process; other steps and conditions are the same as in Example 1.

[0039] Example 3 Compared with Example 1, the only difference is the raw material ratio: 6 parts γ-dicalcium silicate powder, 0.8 parts styrene-acrylic emulsion, 1.35 parts crystal form regulator (0.1 mol / L magnesium chloride aqueous solution), 0.03 parts surface hydrophobic modifier (polydimethylsiloxane), and 3 parts water retention and porosity improver (liquid sodium silicate); and the pressure inside the reactor is maintained at 0.3 MPa during the carbonization curing process; other steps and conditions are the same as in Example 1.

[0040] Example 4 Compared with Example 1, the only difference is the raw material ratio: 6 parts of γ-dicalcium silicate powder, 0.6 parts of styrene-acrylic emulsion, 1.5 parts of crystal form regulator (0.05 mol / L magnesium chloride aqueous solution), 0.05 parts of surface hydrophobic modifier (isobutyltriethoxysilane), and 4 parts of water retention and porosity improver (liquid sodium silicate); other steps and conditions are the same as in Example 1.

[0041] Example 5 Compared with Example 1, the only difference is the raw material ratio: 5 parts γ-dicalcium silicate powder, 0.3 parts styrene-acrylic emulsion, 1 part crystal form regulator (0.1 mol / L magnesium chloride aqueous solution), 0.1 parts surface hydrophobic modifier (polydimethylsiloxane), and 2 parts water retention and porosity improver (liquid sodium silicate); other steps and conditions are the same as in Example 1.

[0042] Example 6 Compared with Example 1, the only difference is the raw material ratio: 5.5 parts of γ-dicalcium silicate powder, 0.7 parts of styrene-acrylic emulsion, 1.5 parts of crystal form regulator (0.1 mol / L magnesium chloride aqueous solution), 0.04 parts of surface hydrophobic modifier (polydimethylsiloxane), and 3.5 parts of water retention and porosity improver (liquid sodium silicate); other steps and conditions are the same as in Example 1.

[0043] Comparative Example 1 Compared with Example 1, the only difference is that the raw materials in this comparative example do not contain a water-retaining and porosity-improving agent (liquid sodium silicate), that is, no liquid sodium silicate was added during the preparation process; the other steps and conditions are the same as in Example 1.

[0044] Comparative Example 2 Compared with Example 1, the only difference is that the raw materials in this comparative example do not contain a surface hydrophobic modifier (polydimethylsiloxane), that is, polydimethylsiloxane was not added during the preparation process; the other steps and conditions are the same as in Example 1.

[0045] Comparative Example 3 Compared with Example 1, the only difference is that: in the raw materials of this comparative example, there is no crystal form regulator (magnesium chloride aqueous solution), and an equal amount of deionized water is used to replace the magnesium chloride solution in the preparation process; other steps and conditions are the same as in Example 1.

[0046] Comparative Example 4 Compared with Example 1, the only difference is that 7 parts of γ-dicalcium silicate powder were weighed in the raw materials of this comparative example; the other steps and conditions are the same as in Example 1.

[0047] Comparative Example 5 Compared with Example 1, the only difference is that in the raw materials of this comparative example, γ-dicalcium silicate powder is replaced with β-dicalcium silicate powder; the other steps and conditions are the same as in Example 1.

[0048] Performance testing The detection method is as follows: Contact angle test: Static water contact angle test was performed on the cured coating surface using a contact angle measuring instrument. Five different points were selected for each sample and the average value was taken.

[0049] Water vapor transmission rate test: The test was conducted according to the cup method in GB / T 17146-2015 "Test Method for Water Vapor Transmission Performance of Building Materials" to characterize the air permeability of the coating.

[0050] Weather resistance (UV aging resistance) test: Accelerated aging test was conducted using fluorescent UV lamps, referring to GB / T 16422.3 standard. The cycle conditions were set as follows: 8 hours of UV irradiation at 60℃, followed by 4 hours of condensation at 50℃, constituting one cycle. The test was conducted continuously for 1000 hours. After the test, changes in the surface morphology of the coating (such as cracking, blistering, chalking, etc.) were observed.

[0051] The performance of the water-repellent and breathable carbon mineralized protective coatings prepared in each embodiment and comparative example was tested, and the test results are shown in Table 1 below.

[0052] Table 1 Performance test results of each embodiment and comparative example

[0053] According to the test results in Table 1: The carbon mineralization protective coatings prepared in Examples 1-6 all exhibited excellent hydrophobic properties, with hydrophobic angles ranging from 125° to 140°, classifying them as highly hydrophobic surfaces that effectively block the intrusion of liquid water. Simultaneously, their water vapor permeability remained stable at 345–526 g / (m²). 2 The fact that the coating has a range of 24 hours indicates that it retains an appropriate amount of mesoporous channels, which not only prevents moisture penetration but also ensures the effective discharge of water vapor from the substrate, achieving a balance between water repellency and breathability.

[0054] Comparing Example 1 with Comparative Example 1 (without liquid sodium silicate), it can be seen that the hydrophobic angle of Comparative Example 1 drops sharply to 35.45°, and the water vapor transmission rate surges to 1275.47 g / (m²). 2 •24h). This indicates that without the water-retaining and pore-forming effects of liquid sodium silicate, the coating may not react completely during carbonization due to water loss, and it cannot form a dense silica gel skeleton to fill the large pores, resulting in a loose and poorly dense coating structure, thus losing its water-repellent ability and having excessively high permeability.

[0055] Comparing Example 1 and Comparative Example 2 (without surface hydrophobic modifier), it can be seen that Comparative Example 2 has a hydrophobic angle of only 7.76°, exhibiting extremely strong hydrophilicity, and a water vapor permeability as high as 1225.24 g / (m²). 2 (24h). This confirms that surface hydrophobic modifiers play a decisive role in reducing surface energy and constructing a water-repellent barrier. Without polydimethylsiloxane, even with a dense microstructure, moisture can still penetrate rapidly through wetting.

[0056] Comparing Example 1 and Comparative Example 3 (without crystalline regulator), it can be seen that: the hydrophobic angle of Comparative Example 3 is 54.13°, and the water vapor transmission rate is 1300.75 g / (m²). 2• 24h) (highest among all samples). This indicates that the characteristic needle-like interwoven network of aragonite cannot be formed without the addition of magnesium chloride. This loose crystalline stacking structure cannot effectively block moisture channels, resulting in a significant decrease in the physical barrier properties of the coating.

[0057] Comparing Example 1 and Comparative Example 4 (excess powder), it can be seen that: the hydrophobic angle of Comparative Example 4 is 105.47°, and the water vapor transmission rate is 925.43 g / (m²). 2 •24h). This indicates that when the amount of γ-dicalcium silicate powder increases to 7 parts, the imbalance of the powder-liquid ratio in the system leads to a sharp increase in the viscosity of the slurry. The hydrophobic modifier is difficult to disperse evenly to form a film, resulting in incomplete carbonization and microcracks. Consequently, the water-repellent and physical shielding properties of the coating are significantly reduced.

[0058] Comparing Example 1 and Comparative Example 5 (replaced with dicalcium β-silicate), it can be seen that: the hydrophobic angle of Comparative Example 5 is 75.32°, and the water vapor transmission rate is 1050.21 g / (m²). 2 (24h). This indicates that β-dicalcium silicate preferentially undergoes a hydration reaction upon contact with water, severely interfering with the carbonization process and preventing the formation of the micro-nano rough structure unique to aragonite, thus disrupting the original water-repellent and air-permeable balance of the coating.

[0059] Comparing the appearance evaluation results of the various embodiments and comparative examples after 1000 hours of artificially accelerated ultraviolet aging, it can be seen that the coatings prepared in Examples 1-6 all exhibit excellent weather resistance, with no blistering or cracking on the surface, only slight yellowing or almost no discoloration. This indicates that the coating of the present invention effectively shields the internal organic groups from photo-oxidative degradation by ultraviolet light, ensuring the long-term stability of the coating. In contrast, comparative examples 1 to 3, due to insufficient structural density or lack of physical shielding network, resulted in rapid powdering, increased roughness, and partial peeling of the coating; comparative example 4, due to early film formation defects, experienced rapid crack propagation under the dual effects of alternating heating and cooling and ultraviolet aging, leading to severe cracking and localized peeling; comparative example 5, due to interference from hydration products, caused structural collapse, resulting in severe cracking and localized peeling.

[0060] In summary, this invention provides a water-repellent and breathable carbon mineralization protective coating, its preparation method, and its application. This water-repellent and breathable carbon mineralization protective coating is mainly based on the carbonization reaction of γ-dicalcium silicate, using styrene-acrylic emulsion as an organic carbonization template. Aragonite crystal growth is induced by crystal form regulators such as magnesium chloride, and water-retaining and pore-regulating agents such as water glass (sodium silicate) improve pores and retain water. Surface hydrophobic modifiers such as polydimethylsiloxane impart surface hydrophobicity. Thus, an inorganic-organic composite coating with high weather resistance and high strength is developed, which simultaneously achieves water (liquid) blocking but not gas (vapor) blocking function, effectively avoiding the problem of coating bubbling and peeling due to excessive internal vapor pressure.

[0061] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A water-repellent and breathable carbon mineralized protective coating, characterized in that, By weight, it includes the following components: γ-Dicalcium silicate powder: 3-6 parts; Carbonized template: 0.3–0.9 parts; Crystal form regulator: 0.8–1.8 parts; Surface hydrophobic modifier: 0.01–0.1 parts; Water-retaining and pore-regulating agent: 2-5 parts.

2. The water-repellent and breathable carbon mineralized protective coating according to claim 1, characterized in that, The carbonization template includes styrene-acrylic emulsion, pure acrylic emulsion, or silicone-acrylic emulsion.

3. The water-repellent and breathable carbon mineralized protective coating according to claim 1, characterized in that, The crystal form regulator includes a magnesium chloride solution of 0.05–0.2 mol / L.

4. The water-repellent and breathable carbon mineralized protective coating according to claim 1, characterized in that, The surface hydrophobic modifier includes one or a mixture of several of polydimethylsiloxane, methyl hydrogen silicone oil, isobutyltriethoxysilane, and n-octyltriethoxysilane.

5. The water-repellent and breathable carbon mineralized protective coating according to claim 1, characterized in that, The water-retaining and pore-regulating agents include liquid sodium silicate, liquid potassium silicate, or liquid lithium silicate.

6. The method for preparing the water-repellent and breathable carbon mineralized protective coating as described in any one of claims 1-5, characterized in that, Includes the following steps: S1, under stirring conditions, γ-dicalcium silicate powder, carbonization template, crystal form regulator, surface hydrophobic modifier and water-retaining and pore-regulating agent are mixed evenly to obtain slurry; S2, apply the slurry to the surface of the concrete substrate and let it stand to form a wet film; S3, the wet film is carbonized and cured to obtain a water-repellent and breathable carbon mineralized protective coating.

7. The method for preparing the water-repellent and breathable carbon mineralized protective coating according to claim 6, characterized in that, In step S1, the slurry preparation process specifically includes: Under stirring conditions of 300–500 r / min, γ-dicalcium silicate powder was mixed with a carbonized template to obtain mixture A; Under stirring conditions of 600–1000 r / min, a crystal form regulator was added to mixture A and mixed evenly to obtain mixture B; Under stirring conditions of 2000–3000 r / min, a surface hydrophobic modifier was added to mixture B and mixed evenly to obtain mixture C; Under stirring conditions of 400–600 r / min, water-retaining and pore-regulating agents are added to mixture C and mixed evenly to obtain a slurry.

8. The method for preparing the water-repellent and breathable carbon mineralized protective coating according to claim 6, characterized in that, In step S2, the concrete substrate is pretreated before being coated with slurry; the pretreatment involves first removing floating dust, oil stains and loose attachments, and then spraying water to make it reach a saturated and surface-dry state. And / or, The coating method includes blade coating, which specifically includes: first applying a base coat with a thickness of 80–120 μm, then applying a top coat to form a wet film; the total thickness of the wet film is 200–550 μm; and / or, The resting period refers to letting the object stand in a natural environment for 30 to 60 minutes.

9. The method for preparing the water-repellent and breathable carbon mineralized protective coating according to claim 6, characterized in that, In step S3, the carbonization curing conditions include: carbonization curing is carried out in a carbonization kettle, and CO2 gas is introduced to a pressure of 0.1-0.3 MPa, the curing temperature is 28-32°C, and the curing time is 12-24 hours.

10. The application of the water-repellent and breathable carbon mineralized protective coating as described in any one of claims 1-5 in the protection of marine concrete.

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