A waterborne inorganic coating for concrete structures and a method for its preparation

Abstract

The application discloses a water-based inorganic coating for a concrete structure and a preparation method thereof. In one aspect, the application provides a water-based inorganic coating for a concrete structure, which comprises an A component and a B component; the A component comprises the following components in a proportion: modified water glass 20-30 parts, fine filler 8-12 parts, ultra-fine filler 6-10 parts, fluorosilicate 0.5-1 part, Portland cement 50-60 parts, retarding water reducing agent 2-4 parts, and water 25-35 parts; the B component comprises the following components in a proportion: polybutadiene type silane-terminated polyurethane prepolymer 30-40 parts, Portland cement 50-60 parts, nano titanium dioxide 18-24 parts, polycarboxylic acid type water reducing agent 1-1.5 parts, and water 35-45 parts. In another aspect, the application further provides a preparation method of the water-based inorganic coating for a concrete structure. The application has excellent deep penetration crystallization performance, and has strong waterproof performance and anti-permeation performance.

Description

Technical Field

[0001] This application relates to the field of waterproof materials technology, and in particular to a water-based inorganic coating for concrete structures and its preparation method. Background Technology

[0002] Concrete is the most commonly used building material in modern construction, widely applied in buildings, bridges, tunnels, and culverts. These structures are exposed to the external environment for extended periods, making them susceptible to chemical or physical reactions with corrosive media, leading to damage. Current research indicates that water, oxygen, carbon dioxide, and chloride ions are the main factors causing concrete corrosion, with moisture being the key factor. Under the influence of moisture, carbon dioxide easily penetrates the concrete, forming carbonic acid, which causes carbonation and corrosion. Corroded concrete cannot effectively protect the internal reinforcing steel, and the penetration of moisture and oxygen triggers electrochemical reactions in the steel, leading to corrosion. Therefore, waterproofing is crucial for ensuring the durability of concrete structures.

[0003] Currently, the main method for waterproofing concrete is to apply a waterproof coating layer to the concrete surface. Existing waterproof coatings are divided into two categories: organic and inorganic. Organic waterproof coatings have a flexible film after formation, are not prone to cracking over long-term use, and have excellent water-blocking properties, thus they are widely used. However, the hydrophobic nature of organic waterproof coatings leads to poor compatibility with concrete, and the significant difference in their coefficients of thermal expansion and contraction with concrete results in a generally shorter service life and a tendency to blister and peel off. Inorganic waterproof coatings, with inorganic gel materials as the main component, have good compatibility with concrete and offer advantages such as environmental friendliness and weather resistance. In particular, penetrating crystalline inorganic waterproof coatings, with silicate gel materials as the main component, can penetrate from concrete cracks into the concrete and crystallize within, deeply repairing damaged concrete and are widely used for waterproofing repairs in concrete structures.

[0004] Existing penetrating crystalline inorganic waterproof coatings are generally quite rigid, making them prone to cracking with long-term use. Although incorporating crack-resistant fibers can alleviate the cracking problem to some extent, existing penetrating crystalline inorganic waterproof coatings still suffer from insufficient penetration depth, inadequate overall waterproofing performance, and poor impermeability. Summary of the Invention

[0005] In order to solve at least one of the above-mentioned technical problems, and to develop a relatively low-cost, deep-penetrating crystallizing inorganic waterproof coating with excellent deep-penetrating crystallizing properties and strong waterproof and impermeable properties, this application provides a water-based inorganic coating for concrete structures and its preparation method.

[0006] On one hand, this application provides a water-based inorganic coating for concrete structures, comprising component A coated on the concrete surface and component B coated on the outer surface of component A; the mass proportions of each raw material component of component A include: 20-30 parts modified water glass, 8-12 parts micron-sized fine filler, 6-10 parts nano-sized ultrafine filler, 0.5-1 part fluorosilicate, 50-60 parts silicate cement, 2-4 parts retarding water-reducing agent, and 25-35 parts water; the mass proportions of each raw material component of component B include: 30-40 parts polybutadiene-type silane-terminated polyurethane prepolymer, 50-60 parts silicate cement, 18-24 parts nano titanium dioxide, 1-1.5 parts polycarboxylate water-reducing agent, and 35-45 parts water; the modified water glass is sodium-lithium water glass, the mass ratio of sodium silicate to lithium silicate is 2-3:1, and the nano-sized ultrafine filler is nano-kaolin.

[0007] Optionally, the raw materials of component A may further include 8 to 10 parts of basalt short fibers, wherein the length of the basalt short fibers is 0.1 to 0.5 mm and the fiber diameter is 7 to 14 μm.

[0008] Optionally, in the modified water glass, the mass ratio of sodium silicate to lithium silicate is 2~3:1.

[0009] Optionally, the micron-sized fine filler is selected from waste gas glass micro powder.

[0010] Optionally, the preparation of the polybutadiene-type silane-terminated polyurethane prepolymer includes the following steps:

[0011] S1-1. Mix monoisocyanate-grafted silane and hydroxyl-terminated polybutadiene thoroughly in a 1:1 molar ratio to prepare a mixture.

[0012] S1-2. Add 0.08% of dibutyltin dilaurate to the mixture obtained in step S1-1. After thorough mixing, heat to 60-65℃ and react for 4-4.5 hours. After cooling, a polybutadiene-type silane-terminated polyurethane prepolymer is obtained.

[0013] Optionally, in step S1-1, the monoisocyanate-grafted silane is selected from 3-isocyanate-propyltrimethoxysilane.

[0014] Optionally, in step S1-1, the hydroxyl-terminated polybutadiene is selected from hydrogenated hydroxyl-terminated polybutadiene.

[0015] Alternatively, the preparation of the hydrogenated hydroxyl-terminated polybutadiene includes the following steps:

[0016] Sa, Dissolve hydroxyl-terminated polybutadiene in cyclohexane to prepare a 5% solution, then add a mixed catalyst of copper chromite powder and copper oxide powder in a 1:1 mass ratio, and add it to a pressure reaction vessel;

[0017] Sb. Hydrogen gas is continuously introduced into the container to maintain the pressure in the reaction container at 1.2~1.4MPa. The temperature is first raised to 55~60℃ and reacted for 2h, and then raised to 75~80℃ and reacted for 6h. The mixed catalyst is filtered out to obtain the reaction mixture.

[0018] Sc. The reaction mixture is rotary evaporated at 80~85℃ to remove the cyclohexane solvent, and hydrogenated hydroxyl-terminated polybutadiene is obtained.

[0019] On the other hand, this application also provides a method for preparing the above-mentioned water-based inorganic coating for concrete structures, comprising the following steps:

[0020] S1. Preparation of polybutadiene-type silane-terminated polyurethane prepolymer;

[0021] S2. According to the formula, mix all the raw materials of component A, and shear and stir at high speed of 2000~2500 rpm for more than 30 minutes. After standing to defoam, component A is obtained.

[0022] S3. According to the formula, mix silicate cement, nano titanium dioxide and polycarboxylate superplasticizer, add water according to the formula, and stir thoroughly to make slurry. Then add polybutadiene-type silane-terminated polyurethane prepolymer to the slurry, and shear and stir at high speed of 2000~2500 rpm for more than 30 minutes. After standing to defoam, component B is obtained.

[0023] In summary, the present invention has at least one of the following beneficial technical effects:

[0024] 1. Component A of this application is used to coat concrete surfaces, with sodium-lithium silicate and silicate cement as the main gelling materials. Sodium-lithium silicate has strong permeability and, when combined with a retarding water-reducing agent, can fully penetrate into the deep layers of concrete for crystallization, effectively sealing concrete cracks. Silicate cement, supplemented with graded fillers, ensures the compactness of the coating's bonding, resulting in good water-blocking and seepage-resistant effects. In addition, Component A is a concrete-like material with excellent compatibility with concrete, effectively bonding with it without causing problems such as blistering or peeling. The bonded waterproof layer contains a certain amount of sodium and lithium, which provides excellent chloride-blocking effects and effectively protects the concrete.

[0025] 2. In this application, a protective layer of component B is provided on the outside of component A as the cementing layer. Component B uses silicate cement as the gelling material and nano-titanium dioxide as the filler to form a relatively dense cementing layer. In addition, component B can form a specific silane-terminated polyurethane crosslinking network through the curing of polybutadiene-type silane-terminated polyurethane prepolymer. The above-mentioned crosslinking network containing polybutadiene groups and silane groups has extremely strong hydrophobicity and can fully fill the gaps in the cementing layer, giving the component B protective layer extremely strong water-blocking and seepage-resistant properties. The introduction of the above-mentioned crosslinking network can give the component B protective layer a certain degree of flexibility and significantly improve its crack resistance.

[0026] 3. Both component A and component B of this application contain silicate cement, which can ensure the compatibility of the component A and component B bonding layers, and also ensure that the coefficients of thermal expansion and contraction of the waterproof coating layer and the concrete are relatively close, so that the waterproof coating layer has excellent durability and will not have problems such as peeling or cracking of the waterproof layer after long-term use. Detailed Implementation

[0027] The present application will be further described in detail below with reference to the embodiments.

[0028] This application provides a water-based inorganic coating for concrete structures, comprising component A coated on the concrete surface and component B coated on the outer surface of component A. The raw material components of component A are proportioned as follows: 20-30 parts modified water glass, 8-12 parts micron-sized fine filler, 6-10 parts nano-sized ultrafine filler, 0.5-1 part fluorosilicate, 50-60 parts silicate cement, 2-4 parts retarding water-reducing agent, and 25-35 parts water. The raw material components of component B are proportioned as follows: 30-40 parts polybutadiene-type silane-terminated polyurethane prepolymer, 50-60 parts silicate cement, 18-24 parts nano titanium dioxide, 1-1.5 parts polycarboxylate water-reducing agent, and 35-45 parts water. The modified water glass is sodium-lithium water glass, the mass ratio of sodium silicate to lithium silicate is 2-3:1, and the nano-sized ultrafine filler is nano-kaolin.

[0029] The method for preparing the above-mentioned water-based inorganic coating for concrete structures according to this application includes the following steps:

[0030] S1. Preparation of polybutadiene-type silane-terminated polyurethane prepolymer;

[0031] S2. According to the formula, mix all the raw materials of component A, and shear and stir at high speed of 2000~2500 rpm for more than 30 minutes. After standing to defoam, component A is obtained.

[0032] S3. According to the formula, mix silicate cement, nano titanium dioxide and polycarboxylate superplasticizer, add water according to the formula, and stir thoroughly to make slurry. Then add polybutadiene-type silane-terminated polyurethane prepolymer to the slurry, and shear and stir at high speed of 2000~2500 rpm for more than 30 minutes. After standing to defoam, component B is obtained.

[0033] To address the problems existing in the prior art, this application designs a two-component inorganic waterproof coating.

[0034] Component A of this application, as a penetrating crystalline waterproof coating, uses sodium-lithium silicate as the penetrating crystalline gel material and is supplemented with a retarding water-reducing agent. This enables the waterproof coating to possess deep penetrating crystalline properties, effectively achieving deep repair of concrete. The main raw materials of Component A are primarily silicate-based materials, exhibiting excellent compatibility and dispersibility. During application, sodium and lithium can penetrate into the concrete cracks, forming effective chloride-blocking protection. Furthermore, Component A employs a graded filler composed of micron- and nano-sized fillers, which, when combined with silicate cement, forms a dense, concrete-like cementitious layer with good water-blocking and seepage-resistant effects.

[0035] This application also designs component B as the outermost protective layer, mainly composed of silicate cement and nano-titanium dioxide filler, forming a relatively dense adhesive layer. Component B also incorporates a highly hydrophobic polybutadiene-type silane-terminated polyurethane crosslinking network to crosslink and fill the adhesive layer of component B, further improving the density of the adhesive layer. This composite adhesive layer exhibits excellent water-blocking and seepage-resistant properties, while also possessing a certain degree of flexibility and good crack resistance. It can effectively protect the adhesive layer of component A, further significantly improving the overall water-blocking and seepage-resistant performance of the waterproof coating layer.

[0036] Component B of this application uses nano-titanium dioxide as a filler, which can provide excellent ultraviolet shielding and effectively prevent the aging of the polybutadiene-type silane-terminated polyurethane crosslinking network caused by ultraviolet radiation, thus ensuring the durability of the waterproof coating.

[0037] The following are preparation examples and embodiments of this application.

[0038] All the main raw materials used in the embodiments of this application are commercially available.

[0039] Among them, sodium silicate glass (sodium silicate content 36%) was purchased from Foshan Zhongfa Water Glass Factory; lithium silicate glass (lithium silicate content 22%) was purchased from Foshan Zhongfa Water Glass Factory; waste glass powder (particle size 100-200μm) was purchased from Lingshou County Dianjin Mineral Products Processing Plant; nano-kaolin (calcined activated kaolin, particle size 150-300nm) was purchased from Shijiazhuang Xu'ang Mineral Products Processing Co., Ltd.; fluorosilicate (sodium fluorosilicate) was purchased from Shenyang Longrun Fine Chemical Raw Materials Co., Ltd.; silicate cement (P·O 52.5) ​​was purchased from Hubei Qibajiu Chemical Co., Ltd.; basalt short fibers (fiber diameter 7-14μm, length 0.1-0.5mm) were purchased from Sichuan Qianyi Composite Materials Co., Ltd.; rutile nano-diol... Titanium oxide, 15-30 nm, was purchased from Beijing Deco Island Gold Technology Co., Ltd.; trimethylsilyl isocyanate was purchased from Hubei Hengjingrui Chemical Co., Ltd.; 3-isocyanatopropyltrimethoxysilane was purchased from Hubei Svit New Material Technology Co., Ltd.; hydroxyl-terminated polybutadiene was purchased from Wuhan Jiyesheng Chemical Co., Ltd.; dibutyltin dilaurate was purchased from Merck Chemicals; copper chromite was purchased from Shandong Guohua Chemical Co., Ltd.; copper oxide, 10 μm particle size, was purchased from Merck Chemicals; retarding water-reducing agent, CSP-2 type retarding high-efficiency water-reducing agent, was purchased from Guangdong Hongqiang New Material Co., Ltd.; polycarboxylate water-reducing agent, polycarboxylate-based high-performance water-reducing agent, was purchased from Zhuzhou Feilu High-tech Material Technology Co., Ltd.

[0040] The following is a preparation example of this application.

[0041] Preparation Example 1

[0042] The preparation of hydrogenated hydroxyl-terminated polybutadiene in this example includes the following steps:

[0043] Sa, Dissolve hydroxyl-terminated polybutadiene in cyclohexane to prepare a 5% solution, then add a mixed catalyst consisting of copper chromite powder and copper oxide powder in a 1:1 mass ratio, accounting for 5% of the total mass of hydroxyl-terminated polybutadiene. After mixing, transfer the mixture to a reaction vessel.

[0044] Sb. Nitrogen gas is introduced into the reactor to purge the air, and then hydrogen gas is introduced into the container to purge the nitrogen gas. Hydrogen gas is then continuously introduced to maintain the pressure in the reaction container at 1.2~1.4MPa. The temperature is first raised to 55~60℃ and reacted for 2 hours, and then raised to 75~80℃ and reacted for 6 hours. The mixed catalyst is filtered out to obtain the reaction mixture.

[0045] Sc. The reaction mixture is rotary evaporated at 80~85℃ to remove the cyclohexane solvent, and hydrogenated hydroxyl-terminated polybutadiene is obtained.

[0046] Residual hydroxyl-terminated polybutadiene was detected by liquid chromatography. The reaction yield was 98.6% based on hydroxyl-terminated polybutadiene, and the purity of the hydrogenated hydroxyl-terminated polybutadiene obtained exceeded 99%.

[0047] Preparation Example 2

[0048] The preparation of the polybutadiene-type silane-terminated polyurethane prepolymer in this example includes the following steps:

[0049] S1-1. Trimethylsilyl isocyanate and hydroxyl-terminated polybutadiene are thoroughly mixed in a 1:1 molar ratio to prepare a mixture.

[0050] S1-2. Add 0.08% of dibutyltin dilaurate to the mixture obtained in step S1-1. After thorough mixing, heat to 60-65℃ and react for 4 hours. After cooling, a polybutadiene-type silane-terminated polyurethane prepolymer is obtained.

[0051] Preparation Example 3

[0052] The preparation of the polybutadiene-type silane-terminated polyurethane prepolymer in this example includes the following steps:

[0053] S1-1. Mix 3-isocyanate-propyltrimethoxysilane and hydroxyl-terminated polybutadiene thoroughly in a 1:1 molar ratio to prepare a mixture.

[0054] S1-2. Add 0.08% of dibutyltin dilaurate to the mixture obtained in step S1-1. After thorough mixing, heat to 60~65℃ and react for 4.5h. After cooling, a polybutadiene-type silane-terminated polyurethane prepolymer is obtained.

[0055] Preparation Example 4

[0056] The difference between this preparation example and preparation example 3 is that the hydrogenated hydroxyl-terminated polybutadiene prepared in preparation example 1 is used to replace the hydroxyl-terminated polybutadiene.

[0057] The following are embodiments of this application.

[0058] The method for preparing water-based inorganic coatings for concrete structures according to embodiments of this application includes the following steps:

[0059] S1. Select a specific polybutadiene-type silane-terminated polyurethane prepolymer;

[0060] S2. According to the formula, mix all the raw materials of component A, and shear and stir at high speed of 2500 rpm for 30 minutes. After standing to defoam, component A is obtained.

[0061] S3. According to the formula, mix silicate cement, nano titanium dioxide and polycarboxylate water-reducing agent, add water according to the formula, and stir thoroughly to make slurry. Then add polybutadiene-type silane-terminated polyurethane prepolymer to the slurry, and shear and stir at 2200 rpm for 30 minutes. After standing to defoam, obtain component B.

[0062] Example 1

[0063] The water-based inorganic coating for concrete structures in this embodiment includes component A and component B.

[0064] The mass proportions of each raw material component in component A include: 20 parts modified water glass, 8 parts waste glass powder, 6 parts nano kaolin, 0.5 parts sodium fluorosilicate, 50 parts silicate cement, 2 parts retarding water-reducing agent, and 25 parts water.

[0065] The mass proportions of each raw material component in component B include: 30 parts of polybutadiene-type silane-terminated polyurethane prepolymer, 50 parts of silicate cement, 18 parts of nano titanium dioxide, 1 part of polycarboxylate superplasticizer, and 35 parts of water.

[0066] The modified water glass is prepared by mixing sodium silicate and lithium silicate in a mass ratio of sodium silicate to lithium silicate of 1:1. The polybutadiene-type silane-terminated polyurethane prepolymer is the polybutadiene-type silane-terminated polyurethane prepolymer prepared in Preparation Example 2.

[0067] Example 2

[0068] The water-based inorganic coating for concrete structures in this embodiment includes component A and component B.

[0069] The mass proportions of each raw material component in component A include: 30 parts modified water glass, 12 parts waste glass powder, 10 parts nano kaolin, 1 part sodium fluorosilicate, 60 parts silicate cement, 4 parts retarding water-reducing agent, and 35 parts water.

[0070] The mass proportions of each raw material component in component B include: 40 parts of polybutadiene-type silane-terminated polyurethane prepolymer, 60 parts of silicate cement, 24 parts of nano titanium dioxide, 1.5 parts of polycarboxylate superplasticizer, and 45 parts of water.

[0071] The modified water glass is prepared by mixing sodium silicate and lithium silicate in a mass ratio of sodium silicate to lithium silicate of 1:1. The polybutadiene-type silane-terminated polyurethane prepolymer is the polybutadiene-type silane-terminated polyurethane prepolymer prepared in Preparation Example 2.

[0072] Example 3

[0073] The water-based inorganic coating for concrete structures in this embodiment includes component A and component B.

[0074] The mass proportions of each raw material component in Component A include: 26 parts modified water glass, 10 parts waste glass powder, 8 parts nano kaolin, 0.8 parts sodium fluorosilicate, 54 parts silicate cement, 3 parts retarding water-reducing agent, and 32 parts water.

[0075] The mass proportions of each raw material component in component B include: 35 parts of polybutadiene-type silane-terminated polyurethane prepolymer, 55 parts of silicate cement, 22 parts of nano titanium dioxide, 1.2 parts of polycarboxylate superplasticizer, and 40 parts of water.

[0076] The modified water glass is prepared by mixing sodium silicate and lithium silicate in a mass ratio of sodium silicate to lithium silicate of 4:1. The polybutadiene-type silane-terminated polyurethane prepolymer is the polybutadiene-type silane-terminated polyurethane prepolymer prepared in Preparation Example 2.

[0077] Example 4

[0078] The difference between this embodiment and Embodiment 3 is that the modified water glass is prepared by using sodium water glass and lithium water glass, with a mass ratio of sodium silicate to lithium silicate of 2:1.

[0079] Example 5

[0080] The difference between this embodiment and Embodiment 3 is that the modified water glass is prepared by using sodium water glass and lithium water glass, with a mass ratio of sodium silicate to lithium silicate of 3:1.

[0081] Example 6

[0082] The difference between this embodiment and Example 5 is that the polybutadiene-type silane-terminated polyurethane prepolymer used is the polybutadiene-type silane-terminated polyurethane prepolymer prepared in Example 3.

[0083] Example 7

[0084] The difference between this embodiment and Example 5 is that the polybutadiene-type silane-terminated polyurethane prepolymer used is the polybutadiene-type silane-terminated polyurethane prepolymer prepared in Example 4.

[0085] Example 8

[0086] The difference between this embodiment and Embodiment 7 is that 8 parts of basalt short fibers are added to component A.

[0087] Example 9

[0088] The difference between this embodiment and Embodiment 7 is that 10 parts of basalt short fibers are added to component A.

[0089] Example 10

[0090] The difference between this embodiment and Embodiment 7 is that 9 parts of basalt short fibers are added to component A.

[0091] Comparative Example 1

[0092] This application adopts Example 2 of Chinese Invention Patent No. CN115490536A, entitled "An Aqueous Penetrating Inorganic Waterproofing Agent and Its Preparation Method and Application", as Comparative Example 1.

[0093] Comparative Example 2

[0094] The difference between this comparative example and Example 7 is that potassium silicate glass with an equal amount of silicate is used instead of lithium silicate glass.

[0095] Comparative Example 3

[0096] The difference between this comparative example and Example 7 is that an equal amount of nano-montmorillonite was used to replace nano-kaolinite.

[0097] Comparative Example 4

[0098] The difference between this comparative example and Example 7 is that an equal amount of polyether-type MDI-terminated polyurethane prepolymer produced by Orion (Jining) Chemical Co., Ltd. was used to replace the polybutadiene-type silane-terminated polyurethane prepolymer.

[0099] The waterproof coatings of Examples 1-10 and Comparative Examples 1-4 of this application were tested for relevant properties, including 28-day compressive strength, 28-day flexural strength, impermeability, and impermeability after aging. Specifically, the total application thickness of the waterproof coatings of Examples 1-10 and Comparative Examples 2-4 was 5 mm, with component A having a thickness of 3 mm and component B a thickness of 2 mm; the waterproof coating of Comparative Example 1 had an application thickness of 5 mm.

[0100] The compressive strength was tested according to the method described in GB 177-85;

[0101] Flexural strength was tested according to the method described in GB 177-85;

[0102] The impermeability was tested according to the method described in JC / T 1018-2020, which determined the permeability height ratio under a pressure of 1 MPa.

[0103] Concrete samples were prepared according to the recommended mix proportions and parameters specified in JC / T 1018-2020;

[0104] The aging treatment was conducted at a temperature of 80℃, humidity of 100%, and UV intensity of 0.45W / m. 2 Under these conditions, the treatment was carried out over 30 days.

[0105] The test results are shown in Table 1 below.

[0106] Table 1. Performance Test Data of Waterproof Coating

[0107] Compressive strength (MPa) Flexural strength (MPa) Penetration height ratio (%) Penetration height ratio after aging (%) Example 1 57.2 8.1 10.6 14.9 Example 2 57.4 8.1 10.2 14.4 Example 3 57.7 8.2 9.9 13.8 Example 4 58.4 8.7 9.0 12.1 Example 5 58.5 8.7 8.8 11.6 Example 6 59.4 9.1 6.9 8.7 Example 7 59.6 9.2 5.6 5.6 Example 8 59.7 9.4 5.5 6.5 Example 9 59.7 9.4 5.5 5.5 Example 10 59.8 9.4 5.5 5.5 Comparative Example 1 54.2 7.6 21.6 23.9 Comparative Example 2 58.8 8.8 40.4 40.4 Comparative Example 3 56.5 7.9 8.1 8.1 Comparative Example 4 58.1 8.6 19.4 28.3

[0108] As can be seen from the data in Table 1, the 28-day compressive strength and 28-day flexural strength of the waterproof coatings in Examples 1-10 of this application are significantly improved compared to Comparative Example 1 of the prior art. This indicates that the waterproof layer formed by the waterproof coatings of this application has superior strength and toughness, and its crack resistance is significantly better than that of the waterproof coating in Comparative Example 1 of the prior art. Furthermore, the penetration height ratio of the waterproof coatings in Examples 1-10 of this application is much lower than that of the waterproof coating in Comparative Example 1; this demonstrates that the waterproof coatings of this application possess excellent waterproof and seepage-resistant properties, far superior to those of Comparative Example 1 of the prior art. The above test results fully demonstrate that the inorganic waterproof coating obtained by this application using a specific two-component design exhibits excellent performance in all aspects.

[0109] The applicant prepared fractured concrete samples and compared the application results using the inorganic waterproof coatings of Examples 1-10 of this application and the inorganic waterproof coating of Comparative Example 1. The penetration and crystallization depth of the inorganic waterproof coatings of Examples 1-10 of this application was at least 15% greater than that of the inorganic waterproof coating of Comparative Example 1. Therefore, the penetration and crystallization depth of the inorganic waterproof coating of this application is also significantly better than that of the product of Comparative Example 1, which also uses sodium-lithium silicate. The applicant believes that the use of fluorosilicate combined with a retarding water-reducing agent in this application can effectively promote the penetration of sodium-lithium silicate, giving the waterproof coating of this application superior penetration and crystallization performance. Furthermore, the penetration and crystallization performance of Example 5 of this application is better than that of Example 4, and the penetration and crystallization performance of Example 4 is significantly better than that of Examples 1-3. It can be seen that the system designed in this application, with the mass ratio of modified water glass sodium silicate to lithium silicate controlled at 2-3:1, can achieve the best penetration and crystallization effect.

[0110] The data comparison in Table 1 for Examples 1-10 shows that the performance of the waterproof coating was further improved after the optimized formulation. Furthermore, the impermeability and aging resistance of Example 7 are superior to those of Example 6, while the impermeability and aging resistance of Example 6 are significantly superior to those of Example 5. This demonstrates that the optimization and improvement of the polybutadiene-type silane-terminated polyurethane prepolymer significantly enhances the impermeability and aging resistance of the waterproof coating. The applicant believes that hydrogenated hydroxyl-terminated polybutadiene exhibits superior stability, and the silane-terminated polyurethane prepared with 3-isocyanate-propyltrimethoxysilane demonstrates excellent resistance to thermal and oxygen aging. Moreover, the hydrophobic and water-blocking properties of this polyurethane are significantly superior to other types of silane-terminated polyurethane, thus enabling the waterproof coating to achieve better waterproof and impermeable performance. Additionally, the flexural strength of Examples 8-10 is slightly better than that of Example 7, indicating that the addition of fiber reinforcement promotes the toughness and crack resistance of the bonded waterproof layer.

[0111] The data in Table 1, comparing Example 7 with Comparative Examples 2-4, shows that the performance of Example 7 is significantly better than that of Comparative Examples 2-4. This demonstrates that the sodium-lithium silicate used in this application exhibits superior impermeability compared to sodium-potassium silicate. Furthermore, the use of nano-montmorillonite as an ultrafine filler further enhances its waterproofing and impermeability performance. The applicant believes that nano-kaolinite can form a bicrystalline phase with silicates, possessing superior stability and denser crystals, effectively improving barrier properties. Moreover, the use of polybutadiene-type silane-terminated polyurethane prepolymer in this application results in significantly better waterproofing and impermeability performance than other polyurethane prepolymers. The applicant believes that the hydrophobicity and water-blocking properties of polybutadiene-type silane-terminated polyurethane are significantly superior to other polyurethanes, and the resulting cross-linked network can greatly improve the water-blocking performance of the waterproof coating layer, thereby significantly enhancing its waterproofing and impermeability performance.

[0112] The above are all preferred embodiments of this application and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A water-based inorganic coating for concrete structures, characterized in that, The product comprises Component A, which is coated onto the surface of concrete, and Component B, which is coated onto the outer surface of the Component A coating. The component A comprises the following components in the following proportions by mass: 20-30 parts modified water glass, 8-12 parts micron-sized fine filler, 6-10 parts nano-sized ultrafine filler, 0.5-1 part fluorosilicate, 50-60 parts silicate cement, 2-4 parts retarding water-reducing agent, and 25-35 parts water. The component B comprises the following components in the following proportions by mass: 30-40 parts polybutadiene-type silane-terminated polyurethane prepolymer, 50-60 parts silicate cement, 18-24 parts nano-titanium dioxide, 1-1.5 parts polycarboxylate water-reducing agent, and 35-45 parts water. The modified water glass is sodium-lithium water glass, with a sodium silicate to lithium silicate mass ratio of 1-4:

1. The nano-sized ultrafine filler is nano-kaolin.

2. The water-based inorganic coating for concrete structures according to claim 1, characterized in that, The raw materials of component A also include 8 to 10 parts of basalt short fibers, wherein the length of the basalt short fibers is 0.1 to 0.5 mm and the fiber diameter is 7 to 14 μm.

3. The water-based inorganic coating for concrete structures according to claim 2, characterized in that, In the modified water glass, the mass ratio of sodium silicate to lithium silicate is 2~3:

1.

4. The water-based inorganic coating for concrete structures according to claim 1, characterized in that, The micron-sized fine filler is made from waste glass powder.

5. The water-based inorganic coating for concrete structures according to claim 1, characterized in that, The preparation of the polybutadiene-type silane-terminated polyurethane prepolymer includes the following steps: S1-1. Mix monoisocyanate-grafted silane and hydroxyl-terminated polybutadiene thoroughly in a 1:1 molar ratio to prepare a mixture. S1-2. Add 0.08% of dibutyltin dilaurate to the mixture obtained in step S1-1. After thorough mixing, heat to 60-65℃ and react for 4-4.5 hours. After cooling, a polybutadiene-type silane-terminated polyurethane prepolymer is obtained.

6. The water-based inorganic coating for concrete structures according to claim 5, characterized in that, In step S1-1, the monoisocyanate-grafted silane is selected from 3-isocyanate-propyltrimethoxysilane.

7. The water-based inorganic coating for concrete structures according to claim 5, characterized in that, In step S1-1, the hydroxyl-terminated polybutadiene is selected from hydrogenated hydroxyl-terminated polybutadiene.

8. The water-based inorganic coating for concrete structures according to claim 7, characterized in that, The preparation of the hydrogenated hydroxyl-terminated polybutadiene includes the following steps: Sa, Dissolve hydroxyl-terminated polybutadiene in cyclohexane to prepare a 5% solution, then add a mixed catalyst of copper chromite powder and copper oxide powder in a 1:1 mass ratio, and add it to a pressure reaction vessel; Sb. Hydrogen gas is continuously introduced into the container to maintain the pressure in the reaction container at 1.2~1.4MPa. The temperature is first raised to 55~60℃ and reacted for 2h, and then raised to 75~80℃ and reacted for 6h. The mixed catalyst is filtered out to obtain the reaction mixture. Sc. The reaction mixture is rotary evaporated at 80~85℃ to remove the cyclohexane solvent, and hydrogenated hydroxyl-terminated polybutadiene is obtained.

9. A method for preparing a water-based inorganic coating for concrete structures according to any one of claims 1 to 8, characterized in that, Includes the following steps: S1. Preparation of polybutadiene-type silane-terminated polyurethane prepolymer; S2. According to the formula, mix all the raw materials of component A, and shear and stir at high speed of 2000~2500 rpm for more than 30 minutes. After standing to defoam, component A is obtained. S3. According to the formula, mix silicate cement, nano titanium dioxide and polycarboxylate superplasticizer, add water according to the formula, and stir thoroughly to make slurry. Then add polybutadiene-type silane-terminated polyurethane prepolymer to the slurry, and shear and stir at high speed of 2000~2500 rpm for more than 30 minutes. After standing to defoam, component B is obtained.