A silicon-titanium aerogel, a silicon-titanium aerogel-modified silane emulsion, a method for preparing the same, and a superhydrophobic self-cleaning hydraulic lime mortar.

Abstract

This invention belongs to the field of lime mortar technology and provides a silicon-titanium aerogel, a silicon-titanium aerogel-modified silane emulsion, its preparation method, and a superhydrophobic self-cleaning hydraulic lime mortar. The preparation method of the silicon-titanium aerogel of this invention includes the following steps: mixing silica sol and titanium dioxide sol to obtain a silicon-titanium cosol; sequentially allowing the silicon-titanium cosol to stand and age to obtain a gel; and subjecting the gel to supercritical carbon dioxide drying to obtain a dried silicon-titanium aerogel. This invention alters the physicochemical properties of the lime mortar surface through silica and surface chemical modification (such as silanes), thereby giving it superhydrophobic and self-cleaning properties; it maintains the traditional advantages of lime mortar, such as air permeability and environmental friendliness, while also significantly improving the mortar's waterproofness and stain resistance.

Description

Technical Field

[0001] This invention relates to the field of lime mortar technology, and in particular to a silicon-titanium aerogel, a silicon-titanium aerogel-modified silane emulsion, a method for preparing the same, and a superhydrophobic self-cleaning hydraulic lime mortar. Background Technology

[0002] Natural hydraulic lime mortar has a long history of use as a building plastering material, playing a particularly important role in the restoration and preservation of historical buildings. Traditional lime mortar possesses good air permeability, plasticity, and adhesion, making it a natural and environmentally friendly material suitable for the decoration and protection of building walls. Another advantage of lime mortar is its excellent self-healing ability; when micro-cracks appear, it can absorb carbon dioxide from the air and react with water to form calcium carbonate, thereby filling the cracks and enhancing the building's durability. However, traditional natural hydraulic lime mortar also has some drawbacks, especially evident in modern building applications. Its main problem is poor water resistance, making it susceptible to rain erosion, leading to gradual weathering and peeling, especially in humid environments. Furthermore, due to its rough surface and high water absorption, dirt and contaminants easily adhere to the mortar surface, resulting in a deteriorated appearance and requiring frequent cleaning and maintenance. Therefore, improving the water resistance and self-cleaning ability of traditional lime mortar has become a pressing technical challenge in the restoration of both modern and historical buildings.

[0003] To overcome the shortcomings of traditional natural hydraulic lime mortar, superhydrophobic self-cleaning natural hydraulic lime mortar plastering materials have become a research hotspot in the field of building materials. Superhydrophobic technology achieves this by forming a nanoscale rough structure and low surface energy chemical modification on the lime mortar surface, enabling it to effectively repel water droplets. The water contact angle of a superhydrophobic surface typically exceeds 150 degrees, allowing water droplets to roll like beads, carrying away dust and dirt—this is the so-called "self-cleaning" effect. This property significantly reduces the erosion and contamination of the mortar surface by rainwater and pollutants, extending the service life of buildings.

[0004] Another significant advantage of superhydrophobic self-cleaning lime mortar is that it retains the traditional advantages of lime mortar, such as breathability and environmental friendliness, while significantly improving its waterproofness and stain resistance. This composite functional material can be used in modern buildings and is particularly suitable for the restoration and preservation of historical buildings. By combining nanotechnology with lime mortar, it is endowed with new functionality, which not only reduces maintenance costs and extends the life of buildings but also improves the appearance quality of buildings, keeping them clean and tidy for a long time. The application background of superhydrophobic self-cleaning natural hydraulic lime mortar mainly focuses on two aspects: exterior wall coatings for modern buildings and the protection and restoration of historical buildings. With the acceleration of urbanization and the increasing environmental protection requirements, the durability and low maintenance cost of building materials have become the focus of the construction industry. Although traditional lime mortar has excellent environmental performance, its susceptibility to water erosion and surface pollution limits its widespread application. The emergence of superhydrophobic self-cleaning lime mortar provides buildings with a new type of material with low maintenance costs and high durability, which retains the natural texture and ecological characteristics of lime mortar while meeting functional requirements.

[0005] In the restoration of historical buildings, enhancing their protective capabilities without altering the properties of the original building materials is a significant technical challenge. Superhydrophobic self-cleaning lime mortar, with its breathability and self-healing properties, is an ideal restoration material, while its superhydrophobic function effectively prevents moisture erosion of the building structure. Through this new material, historical buildings can be better protected without damaging their original appearance, slowing down the process of weathering and aging.

[0006] Therefore, the research yielded a silicon-titanium aerogel, a silicon-titanium aerogel-modified silane emulsion, its preparation method, and a superhydrophobic self-cleaning hydraulic lime mortar, which not only retains the original excellent properties of lime mortar but also improves its hydrophobic self-cleaning ability, which is of great significance. Summary of the Invention

[0007] The purpose of this invention is to address the shortcomings of existing lime mortar plastering techniques by providing a silicon-titanium aerogel, a silicon-titanium aerogel-modified silane emulsion, a preparation method thereof, and a superhydrophobic self-cleaning hydraulic lime mortar.

[0008] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0009] This invention provides a method for preparing silicon-titanium aerogel, comprising the following steps:

[0010] 1) Mix the silicon source and anhydrous ethanol to obtain a silicon solution, and add water droplets to the silicon solution to form a silica sol;

[0011] A titanium source and anhydrous ethanol are mixed to obtain a titanium solution. Water is then added to the titanium solution to form a titanium dioxide sol.

[0012] 2) Silica sol and titanium dioxide sol are mixed to obtain a silica-titanium cosol. The silica-titanium cosol is then allowed to stand and age sequentially to obtain a gel.

[0013] 3) The gel is dried by supercritical carbon dioxide to obtain dried silicon-titanium aerogel.

[0014] Preferably, the silicon source comprises one or more of tetraethyl orthosilicate, methyl orthosilicate, methyltriethoxysilane, propyltrimethoxysilane, and colloidal silica; the titanium source comprises one or more of tetrabutyl titanate, tetraisopropyl titanate, and titanium isopropoxide.

[0015] In silica sol, the mass ratio of silicon source, anhydrous ethanol, and water is 10–15:30–45:20–50, and the dropping rate is 1–2 mL / min; in titanium dioxide sol, the mass ratio of titanium source, anhydrous ethanol, and water is 10–20:30–60:30–50, and the dropping rate is 0.5–1 mL / min.

[0016] Preferably, the mass ratio of silica sol to titanium dioxide sol in step 2) is 10-15:10-20, and the standing time is 6-12 hours.

[0017] The aging process is carried out in an aging solution containing one or more of anhydrous ethanol, methanol, isopropanol, and propanol; the aging temperature is 20–60°C, and the aging time is 12–36 h.

[0018] Preferably, in the supercritical carbon dioxide drying process described in step 3), the system pressure is first controlled to be >7.38MPa and the system temperature to be <31.1℃ to keep the carbon dioxide in a liquid state; then the temperature and pressure are sequentially increased and decreased, with the pressure remaining constant during the heating process and the target temperature being >31.1℃.

[0019] The present invention also provides a silicon-titanium aerogel prepared by the aforementioned preparation method.

[0020] The present invention also provides a method for preparing a silicon-titanium aerogel-modified silane emulsion from the aforementioned silicon-titanium aerogel, comprising the following steps:

[0021] (1) The silicon-titanium aerogel was ultrasonically dispersed in water to obtain a silicon-titanium aerogel dispersion.

[0022] A silane solution is added dropwise to an aqueous emulsifier solution, and the mixture is stirred to form a silane emulsion.

[0023] (2) The silicon-titanium aerogel dispersion is added dropwise to the silane emulsion for reaction to obtain the silicon-titanium aerogel modified silane emulsion.

[0024] Preferably, the mass ratio of silicon-titanium aerogel to water is 5-10:10-15; the silane solution is obtained by mixing silane coupling agent and water, with a mass ratio of silane coupling agent to water of 30-40:20-40; and the emulsifier aqueous solution is obtained by dissolving emulsifier in water, with a mass ratio of emulsifier to water of 2-5:10-15.

[0025] The mass ratio of the silicon-titanium aerogel, silane coupling agent, and emulsifier is 5–10:30–40:2–5;

[0026] The silane coupling agent is one or more of trimethylolpropane trimethacrylate, ethylene glycol dimethacrylate, vinyltriisopropoxysilane, 1,4-butanediol methacrylate and polydimethylsiloxane.

[0027] The emulsifier is one or more of Tween-80, sodium dodecyl sulfate, fatty alcohol polyoxyethylene ether, and hexadecyltrimethylammonium chloride.

[0028] Preferably, the ultrasonic dispersion power in step (1) is 150-300kW, the ultrasonic dispersion time is 0.5-1h, the dropping rate is 0.5-1.5mL / min, and the stirring rate is 300-600rpm.

[0029] The dropping rate in step (2) is 1-2 mL / min, the reaction temperature is 30-50℃, the reaction time is 1-3 h, and the stirring rate during the reaction is 400-600 rpm.

[0030] The present invention also provides a silicon-titanium aerogel modified silane emulsion prepared by the method.

[0031] The present invention also provides a superhydrophobic self-cleaning hydraulic lime mortar comprising the aforementioned silicon-titanium aerogel-modified silane emulsion. The superhydrophobic self-cleaning hydraulic lime mortar comprises the following components in parts by weight: 40-50 parts of natural hydraulic lime, 40-100 parts of fine aggregate, 3-10 parts of silicon-titanium aerogel-modified silane emulsion, 1-3 parts of nano-silica, 0.5-2 parts of water-reducing agent, 0.1-1 parts of dispersant, and 20-30 parts of water.

[0032] The beneficial effects of this invention include the following:

[0033] This invention functionally improves traditional lime mortar, endowing it with superhydrophobic and self-cleaning properties. By modifying the surface physicochemical properties of lime mortar with silica and surface chemicals (such as silanes), it acquires superhydrophobic and self-cleaning characteristics. The superhydrophobic self-cleaning hydraulic lime mortar of this invention retains the traditional advantages of lime mortar, such as breathability and environmental friendliness, while also greatly improving the waterproofness and stain resistance of the mortar. Detailed Implementation

[0034] This invention provides a method for preparing silicon-titanium aerogel, comprising the following steps:

[0035] 1) Mix the silicon source and anhydrous ethanol to obtain a silicon solution, and add water droplets to the silicon solution to form a silica sol;

[0036] A titanium source and anhydrous ethanol are mixed to obtain a titanium solution. Water is then added to the titanium solution to form a titanium dioxide sol.

[0037] 2) Silica sol and titanium dioxide sol are mixed to obtain a silica-titanium cosol. The silica-titanium cosol is then allowed to stand and age sequentially to obtain a gel.

[0038] 3) The gel is dried by supercritical carbon dioxide to obtain dried silicon-titanium aerogel.

[0039] In this invention, the silicon source preferably comprises one or more of tetraethyl orthosilicate, methyl orthosilicate, methyltriethoxysilane, propyltrimethoxysilane, and colloidal silica; the titanium source preferably comprises one or more of tetrabutyl titanate, tetraisopropyl titanate, and titanium isopropoxide.

[0040] In the silica sol, the preferred mass ratio of silicon source, anhydrous ethanol, and water is 10–15:30–45:20–50, more preferably 11–14:35–40:25–45, and even more preferably 12–13:36–37:30–40; the preferred dropping rate is 1–2 mL / min, more preferably 1.2–1.8 mL / min, and even more preferably 1.5–1.6 mL / min. In the titanium dioxide sol, the preferred mass ratio of titanium source, anhydrous ethanol, and water is 10–20:30–60:30–50, more preferably 12–18:35–55:35–45, and even more preferably 15–16:40–50:38–40; the preferred dropping rate is 0.5–1 mL / min, more preferably 0.6–0.9 mL / min, and even more preferably 0.7–0.8 mL / min.

[0041] When water droplets are added to a silicon solution, the silicon source undergoes hydrolysis and condensation reactions to form a silica sol. When water droplets are added to a titanium solution, the titanium source hydrolyzes to form a titanium dioxide sol. The water droplets are added slowly to prevent the reaction from being too rapid and causing precipitation.

[0042] In this invention, the mass ratio of silica sol and titanium dioxide sol in step 2) is preferably 10-15:10-20, more preferably 11-14:12-18, and even more preferably 12-13:15-16. The settling time is preferably 6-12 hours, more preferably 8-11 hours, and even more preferably 9-10 hours.

[0043] The aging process is carried out in an aging solution, which preferably contains one or more of anhydrous ethanol, methanol, isopropanol and propanol; the aging temperature is preferably 20-60°C, more preferably 30-50°C, and even more preferably 40°C; the aging time is preferably 12-36 hours, more preferably 18-30 hours, and even more preferably 22-25 hours.

[0044] In this invention, during the mixing of silica sol and titanium dioxide sol in step 2), the mixture is stirred evenly to ensure uniform dispersion of the silica sol and titanium dioxide sol, thus fully mixing the silicon and titanium substances. During the standing process, a spontaneous condensation reaction occurs, forming a three-dimensional network structure, which gradually transforms into a gel.

[0045] In this invention, during the supercritical carbon dioxide drying process described in step 3), the system pressure is first controlled to be >7.38MPa and the system temperature to be <31.1℃ to keep the carbon dioxide in a liquid state; then the temperature and pressure are sequentially increased and decreased, with the pressure remaining constant during the heating process and the target temperature being >31.1℃.

[0046] In this invention, supercritical carbon dioxide drying is carried out in a supercritical drying vessel. Liquid carbon dioxide is slowly introduced into the supercritical drying vessel, and the system pressure is gradually increased to a level higher than the critical pressure of carbon dioxide (7.38 MPa). Simultaneously, the system temperature is kept below the critical temperature of carbon dioxide (31.1 °C) to keep the carbon dioxide in a liquid state. Then, while maintaining a constant pressure, the temperature is gradually increased to exceed the critical temperature of carbon dioxide (31.1 °C). During the heating process, the carbon dioxide changes from a liquid state to a supercritical state, eliminating the liquid-gas interface and thus avoiding the effect of capillary forces. Then, while maintaining the temperature and pressure in the supercritical region, the pressure is slowly reduced, allowing the supercritical carbon dioxide to be slowly released through the exhaust port. During this process, the carbon dioxide directly changes from a supercritical state to a gaseous state without passing through a liquid state, thus avoiding the collapse of the gel structure. After the carbon dioxide in the system is completely released, the temperature is gradually reduced, the drying vessel is opened, and the dried silicon-titanium aerogel is removed.

[0047] The present invention also provides a silicon-titanium aerogel prepared by the aforementioned preparation method.

[0048] The present invention also provides a method for preparing a silicon-titanium aerogel-modified silane emulsion from the aforementioned silicon-titanium aerogel, comprising the following steps:

[0049] (1) The silicon-titanium aerogel was ultrasonically dispersed in water to obtain a silicon-titanium aerogel dispersion.

[0050] A silane solution is added dropwise to an aqueous emulsifier solution, and the mixture is stirred to form a silane emulsion.

[0051] (2) The silicon-titanium aerogel dispersion is added dropwise to the silane emulsion for reaction to obtain the silicon-titanium aerogel modified silane emulsion.

[0052] In this invention, the preferred mass ratio of silicon-titanium aerogel to water is 5-10:10-15, more preferably 6-9:11-14, and even more preferably 7-8:12-13. The silane solution is obtained by mixing a silane coupling agent and water, and the preferred mass ratio of the silane coupling agent to water is 30-40:20-40, more preferably 32-38:25-35, and even more preferably 35-36:30. The emulsifier aqueous solution is obtained by dissolving the emulsifier in water, and the preferred mass ratio of the emulsifier to water is 2-5:10-15, more preferably 3-4:11-14, and even more preferably 3.5:12-13.

[0053] The preferred mass ratio of the silicon-titanium aerogel, silane coupling agent, and emulsifier is 5-10:30-40:2-5, more preferably 6-9:32-38:3-4, and even more preferably 7-8:35-36:3.5;

[0054] The silane coupling agent is preferably one or more of trimethylolpropane trimethacrylate, ethylene glycol dimethacrylate, vinyltriisopropoxysilane, 1,4-butanediol methacrylate and polydimethylsiloxane.

[0055] The emulsifier is preferably one or more of Tween-80, sodium dodecyl sulfate, fatty alcohol polyoxyethylene ether, and hexadecyltrimethylammonium chloride.

[0056] In this invention, the power of ultrasonic dispersion in step (1) is preferably 150-300kW, more preferably 200-250kW, and the ultrasonic dispersion time is preferably 0.5-1h; the dripping rate is preferably 0.5-1.5mL / min, more preferably 0.8-1.2mL / min, more preferably 1mL / min, and the stirring rate is preferably 300-600rpm, more preferably 350-550rpm, more preferably 400-500rpm;

[0057] The preferred rate of drop addition in step (2) is 1-2 mL / min, more preferably 1.2-1.8 mL / min, and even more preferably 1.5-1.6 mL / min; the preferred reaction temperature is 30-50°C, more preferably 35-45°C, and even more preferably 40°C; the preferred reaction time is 1-3 h, more preferably 1.5-2.5 h, and even more preferably 2 h; and the preferred stirring rate during the reaction is 400-600 rpm, more preferably 450-550 rpm, and even more preferably 500 rpm.

[0058] In this invention, ultrasonic dispersion is used to ensure that the aerogel particles are uniformly dispersed in water, and that the aerogel particles are completely dispersed and do not agglomerate; the silane emulsion is a uniform white or microemulsion silane emulsion.

[0059] In this invention, stirring is performed during the dropwise addition process described in step (2) to ensure that the aerogel is uniformly dispersed in the silane emulsion and reacts with the silane.

[0060] The present invention also provides a silicon-titanium aerogel modified silane emulsion prepared by the method.

[0061] The present invention also provides a superhydrophobic self-cleaning hydraulic lime mortar comprising the aforementioned silicon-titanium aerogel-modified silane emulsion. The superhydrophobic self-cleaning hydraulic lime mortar comprises the following components in parts by weight: 40-50 parts of natural hydraulic lime, 40-100 parts of fine aggregate, 3-10 parts of silicon-titanium aerogel-modified silane emulsion, 1-3 parts of nano-silica, 0.5-2 parts of water-reducing agent, 0.1-1 parts of dispersant, and 20-30 parts of water.

[0062] In the superhydrophobic self-cleaning hydraulic lime mortar of the present invention, the natural hydraulic lime is preferably 42-48 parts, more preferably 44-46 parts, and even more preferably 45 parts; the fine aggregate is preferably 50-90 parts, more preferably 60-80 parts, and even more preferably 70 parts; the silicon-titanium aerogel modified silane emulsion is preferably 4-8 parts, more preferably 5-7 parts, and even more preferably 6 parts; the nano silica is preferably 1.5-2.5 parts, more preferably 2 parts; the water-reducing agent is preferably 0.8-1.6 parts, more preferably 1-1.5 parts, and even more preferably 1.2 parts; the dispersant is preferably 0.3-0.8 parts, more preferably 0.5-0.6 parts; and the water is preferably 22-28 parts, more preferably 24-26 parts, and even more preferably 25 parts.

[0063] In this invention, the fine aggregate is preferably fine sand with a particle size of 0.1 to 0.3 mm; the water-reducing agent is preferably a polycarboxylate superplasticizer or a naphthalene-based water-reducing agent; and the dispersant is preferably hydroxyethyl cellulose ether and / or anionic cellulose ether.

[0064] In this invention, the preferred method for preparing superhydrophobic self-cleaning hydraulic lime mortar is as follows: natural hydraulic lime, nano-silica and water are first mixed; the first mixture and fine aggregate are second mixed; the second mixture, silicon-titanium aerogel modified silane emulsion, water-reducing agent and dispersant are third mixed to obtain superhydrophobic self-cleaning natural hydraulic lime mortar.

[0065] The first mixing rate is preferably 270-300 rpm, more preferably 280-290 rpm, and even more preferably 285 rpm; the first mixing time is preferably 4-6 min, and even more preferably 5 min. The second mixing rate is preferably 130-150 rpm, more preferably 135-145 rpm, and even more preferably 140 rpm; the second mixing time is preferably 4-6 min, and even more preferably 5 min. The third mixing rate is preferably 270-300 rpm, more preferably 280-290 rpm, and even more preferably 285 rpm; the third mixing time is preferably 15-20 min, and even more preferably 17-18 min.

[0066] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0067] NHL5, a natural hydraulic lime produced by StAstier, France, has an apparent density of 0.85 g / cm³. 3 The 28-day compressive strength is 8MPa, which meets the requirements of European standard EN459-12010; the fine aggregate is fine sand with a particle size of 0.1-0.3mm; the water-reducing agent is naphthalene-based water-reducing agent FDN-C, and the dispersant is hydroxyethyl cellulose ether MH300P2;

[0068] In the embodiments, all the parts are parts by mass; in the preparation of silicon-titanium aerogel, the stirring rate is 300 rpm; in the preparation of silicon-titanium aerogel modified silane emulsion, the stirring rate is 500 rpm; in the preparation of superhydrophobic self-cleaning hydraulic lime mortar, the low-speed stirring rate is 140 rpm and the high-speed stirring rate is 285 rpm.

[0069] Example 1

[0070] The preparation method of silicon-titanium aerogel is as follows:

[0071] Ten parts of tetraethyl orthosilicate and 30 parts of anhydrous ethanol were stirred until homogeneous to obtain a silicon solution. Twenty parts of deionized water were added dropwise to the silicon solution at a rate of 1.5 mL / min, causing the tetraethyl orthosilicate to undergo hydrolysis and condensation reactions to form a silica sol. Ten parts of tetrabutyl titanate were added to 35 parts of anhydrous ethanol and stirred until homogeneous to obtain a titanium solution. Under stirring conditions, 30 parts of deionized water were added dropwise at a rate of 0.8 mL / min, causing the tetrabutyl titanate to hydrolyze and form a titanium dioxide sol.

[0072] Ten parts of silica sol and twelve parts of titanium dioxide sol were mixed and stirred until homogeneous to obtain a silica-titanium cosol. The silica-titanium cosol was allowed to stand for 6 hours to undergo spontaneous condensation reaction, forming a three-dimensional network structure and gradually transforming into a silica-titanium gel. The silica-titanium gel was then aged in anhydrous ethanol at 30°C for 12 hours.

[0073] After aging, the gel is washed and carefully placed into a supercritical drying vessel. Liquid carbon dioxide is slowly introduced into the vessel, and the pressure is gradually increased to above the critical pressure of carbon dioxide (7.38 MPa). Simultaneously, the system temperature is maintained below the critical temperature of carbon dioxide (31.1 °C) to keep the carbon dioxide in a liquid state. While maintaining constant pressure, the temperature is gradually increased to above the critical temperature of carbon dioxide (31.1 °C). During this process, the carbon dioxide transitions from a liquid to a supercritical state, eliminating the liquid-gas interface and thus avoiding capillary action. The temperature and pressure are maintained in the supercritical region, and then the pressure is slowly reduced, allowing the supercritical carbon dioxide to be released slowly through the exhaust port. In this process, the carbon dioxide directly transitions from a supercritical state to a gaseous state without passing through a liquid state, thus preventing the collapse of the gel structure. After the carbon dioxide in the system has been completely released, the temperature is gradually reduced to obtain the dried silicon-titanium aerogel.

[0074] The preparation method of silicon-titanium aerogel modified silane emulsion is as follows:

[0075] Five parts of silicon-titanium aerogel powder were added to 10 parts of deionized water and ultrasonically dispersed at 200kW for 0.5h to ensure that the aerogel particles were uniformly dispersed in the water without agglomeration, thus obtaining a silicon-titanium aerogel dispersion.

[0076] 30 parts of silane coupling agent (composed of trimethylolpropane trimethacrylate, ethylene glycol dimethacrylate, and 1,4-butanediol n-methacrylate in a mass ratio of 1:1:1) were added to 20 parts of water and stirred until homogeneous to form a silane solution. 2 parts of Tween-80 were dissolved in 10 parts of deionized water and stirred until completely dissolved to obtain an emulsifier aqueous solution. Under stirring conditions, the silane solution was added dropwise to the emulsifier aqueous solution at a rate of 1 mL / min, and stirring was continued to form a homogeneous silane emulsion.

[0077] The silicon-titanium aerogel dispersion was added to the silane emulsion at a rate of 1.5 mL / min while stirring. The mixture was stirred and reacted at 40 °C for 1.5 h to ensure that the aerogel was uniformly dispersed in the emulsion and reacted with the silane, thus obtaining the silicon-titanium aerogel modified silane emulsion.

[0078] The preparation method of superhydrophobic self-cleaning natural hydraulic lime plastering mortar is as follows:

[0079] Add 40 parts of natural hydraulic lime, 1 part of nano silica and 20 parts of water to a mortar mixer and mix at high speed for 5 minutes; slowly add 60 parts of fine aggregate to the mortar mixer and mix at low speed for 5 minutes; then add 4 parts of silicon-titanium aerogel modified silane emulsion, 1 part of water-reducing agent and 0.5 parts of dispersant, and mix at high speed for 17 minutes to obtain superhydrophobic self-cleaning natural hydraulic lime plastering mortar.

[0080] Example 2

[0081] The preparation method of silicon-titanium aerogel is as follows:

[0082] Ten parts of methyl orthosilicate and 35 parts of anhydrous ethanol were stirred until homogeneous to obtain a silica solution. Twenty parts of deionized water were added dropwise to the silica solution at a rate of 1.2 mL / min, causing methyl orthosilicate to undergo hydrolysis and condensation reactions to form a silica sol. Ten parts of tetraisopropyl titanate were added to 30 parts of anhydrous ethanol and stirred until homogeneous to obtain a titanium solution. Under stirring conditions, 30 parts of deionized water were added dropwise at a rate of 0.6 mL / min, causing tetraisopropyl titanate to hydrolyze and form a titanium dioxide sol.

[0083] Ten parts of silica sol and twelve parts of titanium dioxide sol were mixed and stirred until homogeneous to obtain a silica-titanium cosol. The silica-titanium cosol was allowed to stand for 6 hours to undergo spontaneous condensation reaction, forming a three-dimensional network structure and gradually transforming into a silica-titanium gel. The silica-titanium gel was then aged in anhydrous ethanol at 30°C for 12 hours.

[0084] After aging, the gel is washed and carefully placed into a supercritical drying vessel. Liquid carbon dioxide is slowly introduced into the vessel, and the pressure is gradually increased to above the critical pressure of carbon dioxide (7.38 MPa). Simultaneously, the system temperature is maintained below the critical temperature of carbon dioxide (31.1 °C) to keep the carbon dioxide in a liquid state. While maintaining constant pressure, the temperature is gradually increased to above the critical temperature of carbon dioxide (31.1 °C). During this process, the carbon dioxide transitions from a liquid to a supercritical state, eliminating the liquid-gas interface and thus avoiding capillary action. The temperature and pressure are maintained in the supercritical region, and then the pressure is slowly reduced, allowing the supercritical carbon dioxide to be released slowly through the exhaust port. In this process, the carbon dioxide directly transitions from a supercritical state to a gaseous state without passing through a liquid state, thus preventing the collapse of the gel structure. After the carbon dioxide in the system has been completely released, the temperature is gradually reduced to obtain the dried silicon-titanium aerogel.

[0085] The preparation method of silicon-titanium aerogel modified silane emulsion is as follows:

[0086] Five parts of silicon-titanium aerogel powder were added to 12 parts of deionized water and ultrasonically dispersed at 180kW for 0.5h to ensure that the aerogel particles were uniformly dispersed in the water without agglomeration, thus obtaining a silicon-titanium aerogel dispersion.

[0087] Add 30 parts of silane coupling agent (trimethylolpropane trimethacrylate) to 25 parts of water and stir until homogeneous to form a silane solution. Dissolve 2 parts of sodium dodecyl sulfate in 10 parts of deionized water and stir until completely dissolved to obtain an emulsifier aqueous solution. Under stirring conditions, add the silane solution dropwise to the emulsifier aqueous solution at a rate of 0.8 mL / min and continue stirring to form a homogeneous silane emulsion.

[0088] The silicon-titanium aerogel dispersion was added to the silane emulsion at a rate of 1.2 mL / min while stirring. The mixture was stirred and reacted at 40 °C for 1.5 h to ensure that the aerogel was uniformly dispersed in the emulsion and reacted with the silane, thus obtaining the silicon-titanium aerogel modified silane emulsion.

[0089] The preparation method of superhydrophobic self-cleaning natural hydraulic lime plastering mortar is as follows:

[0090] Add 40 parts of natural hydraulic lime, 2 parts of nano silica and 20 parts of water to a mortar mixer and mix at high speed for 4 minutes; slowly add 60 parts of fine aggregate to the mortar mixer and mix at low speed for 4 minutes; then add 4 parts of silicon-titanium aerogel modified silane emulsion, 1.5 parts of water-reducing agent and 0.6 parts of dispersant and mix at high speed for 15 minutes to obtain superhydrophobic self-cleaning natural hydraulic lime plastering mortar.

[0091] Example 3

[0092] The preparation method of silicon-titanium aerogel is as follows:

[0093] A silica solution was obtained by mixing 12 parts methyltriethoxysilane and 30 parts anhydrous ethanol. 25 parts deionized water were added dropwise to the silica solution at a rate of 1.8 mL / min, causing the methyltriethoxysilane to undergo hydrolysis and condensation to form a silica sol. A titanium isopropoxide solution was obtained by adding 12 parts titanium isopropoxide to 40 parts anhydrous ethanol and stirring until homogeneous. Under stirring conditions, 40 parts deionized water were added dropwise at a rate of 1 mL / min, causing the titanium isopropoxide to hydrolyze and form a titanium dioxide sol.

[0094] Twelve parts of silica sol and twelve parts of titanium dioxide sol were mixed and stirred until homogeneous to obtain a silica-titanium cosol. The silica-titanium cosol was allowed to stand for 8 hours to undergo a spontaneous condensation reaction, forming a three-dimensional network structure and gradually transforming into a silica-titanium gel. The silica-titanium gel was then aged in anhydrous ethanol at 40°C for 12 hours.

[0095] After aging, the gel is washed and carefully placed into a supercritical drying vessel. Liquid carbon dioxide is slowly introduced into the vessel, and the pressure is gradually increased to above the critical pressure of carbon dioxide (7.38 MPa). Simultaneously, the system temperature is maintained below the critical temperature of carbon dioxide (31.1 °C) to keep the carbon dioxide in a liquid state. While maintaining constant pressure, the temperature is gradually increased to above the critical temperature of carbon dioxide (31.1 °C). During this process, the carbon dioxide transitions from a liquid to a supercritical state, eliminating the liquid-gas interface and thus avoiding capillary action. The temperature and pressure are maintained in the supercritical region, and then the pressure is slowly reduced, allowing the supercritical carbon dioxide to be released slowly through the exhaust port. In this process, the carbon dioxide directly transitions from a supercritical state to a gaseous state without passing through a liquid state, thus preventing the collapse of the gel structure. After the carbon dioxide in the system has been completely released, the temperature is gradually reduced to obtain the dried silicon-titanium aerogel.

[0096] The preparation method of silicon-titanium aerogel modified silane emulsion is as follows:

[0097] Eight parts of silicon-titanium aerogel powder were added to 15 parts of deionized water and ultrasonically dispersed at 300kW for 0.5h to ensure that the aerogel particles were uniformly dispersed in the water without agglomeration, thus obtaining a silicon-titanium aerogel dispersion.

[0098] 40 parts of silane coupling agent (ethylene glycol dimethacrylate) were added to 30 parts of water and stirred until homogeneous silane solution was formed. 4 parts of hexadecyltrimethylammonium chloride were dissolved in 12 parts of deionized water and stirred until completely dissolved to obtain an aqueous emulsifier solution. Under stirring conditions, the silane solution was added dropwise to the aqueous emulsifier solution at a rate of 1.5 mL / min, and stirring was continued to form a homogeneous silane emulsion.

[0099] The silicon-titanium aerogel dispersion was added to the silane emulsion at a rate of 2 mL / min while stirring. The mixture was stirred and reacted at 40 °C for 2 h to ensure that the aerogel was uniformly dispersed in the emulsion and reacted with the silane, thus obtaining the silicon-titanium aerogel modified silane emulsion.

[0100] The preparation method of superhydrophobic self-cleaning natural hydraulic lime plastering mortar is as follows:

[0101] Add 40 parts of natural hydraulic lime, 3 parts of nano silica and 24 parts of water to a mortar mixer and mix at high speed for 6 minutes; slowly add 80 parts of fine aggregate to the mortar mixer and mix at low speed for 6 minutes; then add 5 parts of silicon-titanium aerogel modified silane emulsion, 1.5 parts of water-reducing agent and 1 part of dispersant, and mix at high speed for 20 minutes to obtain superhydrophobic self-cleaning natural hydraulic lime plastering mortar.

[0102] Example 4

[0103] The preparation method of silicon-titanium aerogel is as follows:

[0104] A silica solution was obtained by mixing 12 parts propyltrimethoxysilane and 35 parts anhydrous ethanol. 40 parts deionized water were added dropwise to the silica solution at a rate of 1.5 mL / min, causing the propyltrimethoxysilane to undergo hydrolysis and condensation to form a silica sol. A titanium solution was obtained by adding 15 parts tetrabutyl titanate to 45 parts anhydrous ethanol and stirring until homogeneous. Under stirring conditions, 40 parts deionized water were added dropwise at a rate of 0.8 mL / min, causing the tetrabutyl titanate to hydrolyze and form a titanium dioxide sol.

[0105] 15 parts of silica sol and 10 parts of titanium dioxide sol were mixed and stirred until homogeneous to obtain a silica-titanium cosol. The silica-titanium cosol was allowed to stand for 6 hours to undergo a spontaneous condensation reaction, forming a three-dimensional network structure and gradually transforming into a silica-titanium gel. The silica-titanium gel was then aged in anhydrous ethanol at 45°C for 12 hours.

[0106] After aging, the gel is washed and carefully placed into a supercritical drying vessel. Liquid carbon dioxide is slowly introduced into the vessel, and the pressure is gradually increased to above the critical pressure of carbon dioxide (7.38 MPa). Simultaneously, the system temperature is maintained below the critical temperature of carbon dioxide (31.1 °C) to keep the carbon dioxide in a liquid state. While maintaining constant pressure, the temperature is gradually increased to above the critical temperature of carbon dioxide (31.1 °C). During this process, the carbon dioxide transitions from a liquid to a supercritical state, eliminating the liquid-gas interface and thus avoiding capillary action. The temperature and pressure are maintained in the supercritical region, and then the pressure is slowly reduced, allowing the supercritical carbon dioxide to be released slowly through the exhaust port. In this process, the carbon dioxide directly transitions from a supercritical state to a gaseous state without passing through a liquid state, thus preventing the collapse of the gel structure. After the carbon dioxide in the system has been completely released, the temperature is gradually reduced to obtain the dried silicon-titanium aerogel.

[0107] The preparation method of silicon-titanium aerogel modified silane emulsion is as follows:

[0108] Eight parts of silicon-titanium aerogel powder were added to 15 parts of deionized water and ultrasonically dispersed at 200kW for 0.5h to ensure that the aerogel particles were uniformly dispersed in the water without agglomeration, thus obtaining a silicon-titanium aerogel dispersion.

[0109] Add 40 parts of silane coupling agent (vinyltriisopropoxysilane) to 40 parts of water and stir until homogeneous to form a silane solution. Dissolve 4 parts of Tween-80 in 12 parts of deionized water and stir until completely dissolved to obtain an emulsifier aqueous solution. Under stirring conditions, add the silane solution dropwise to the emulsifier aqueous solution at a rate of 1 mL / min and continue stirring to form a homogeneous silane emulsion.

[0110] The silicon-titanium aerogel dispersion was added to the silane emulsion at a rate of 1.5 mL / min while stirring. The mixture was stirred and reacted at 40 °C for 2 h to ensure that the aerogel was uniformly dispersed in the emulsion and reacted with the silane, thus obtaining the silicon-titanium aerogel modified silane emulsion.

[0111] The preparation method of superhydrophobic self-cleaning natural hydraulic lime plastering mortar is as follows:

[0112] Add 40 parts of natural hydraulic lime, 3 parts of nano silica and 20 parts of water to a mortar mixer and mix at high speed for 5 minutes; slowly add 40 parts of fine aggregate to the mortar mixer and mix at low speed for 5 minutes, then add 5 parts of silicon-titanium aerogel modified silane emulsion, 2 parts of water-reducing agent and 1 part of dispersant, and mix at high speed for 17 minutes to obtain superhydrophobic self-cleaning natural hydraulic lime plastering mortar.

[0113] Example 5

[0114] The preparation method of silicon-titanium aerogel is as follows:

[0115] 12 parts colloidal silica and 36 parts anhydrous ethanol were stirred until homogeneous to obtain a silica solution. 40 parts deionized water were added dropwise to the silica solution at a rate of 1.7 mL / min, causing the colloidal silica to undergo hydrolysis and condensation reactions to form a silica sol. 15 parts tetraisopropyl titanate were added to 50 parts anhydrous ethanol and stirred until homogeneous to obtain a titanium solution. Under stirring conditions, 40 parts deionized water were added dropwise at a rate of 0.7 mL / min, causing the tetraisopropyl titanate to hydrolyze and form a titanium dioxide sol.

[0116] 12 parts of silica sol and 15 parts of titanium dioxide sol were mixed and stirred until homogeneous to obtain a silica-titanium cosol. The silica-titanium cosol was allowed to stand for 6 hours to allow it to spontaneously undergo a condensation reaction, forming a three-dimensional network structure and gradually transforming into a silica-titanium gel. The silica-titanium gel was then aged in anhydrous ethanol at 40°C for 24 hours.

[0117] After aging, the gel is washed and carefully placed into a supercritical drying vessel. Liquid carbon dioxide is slowly introduced into the vessel, and the pressure is gradually increased to above the critical pressure of carbon dioxide (7.38 MPa). Simultaneously, the system temperature is maintained below the critical temperature of carbon dioxide (31.1 °C) to keep the carbon dioxide in a liquid state. While maintaining constant pressure, the temperature is gradually increased to above the critical temperature of carbon dioxide (31.1 °C). During this process, the carbon dioxide transitions from a liquid to a supercritical state, eliminating the liquid-gas interface and thus avoiding capillary action. The temperature and pressure are maintained in the supercritical region, and then the pressure is slowly reduced, allowing the supercritical carbon dioxide to be released slowly through the exhaust port. In this process, the carbon dioxide directly transitions from a supercritical state to a gaseous state without passing through a liquid state, thus preventing the collapse of the gel structure. After the carbon dioxide in the system has been completely released, the temperature is gradually reduced to obtain the dried silicon-titanium aerogel.

[0118] The preparation method of silicon-titanium aerogel modified silane emulsion is as follows:

[0119] Ten parts of silicon-titanium aerogel powder were added to 12 parts of deionized water and ultrasonically dispersed at 250kW for 1 hour to ensure that the aerogel particles were uniformly dispersed in the water without agglomeration, thus obtaining a silicon-titanium aerogel dispersion.

[0120] 40 parts of silane coupling agent (vinyltriisopropoxysilane) were added to 30 parts of water and stirred until homogeneous silane solution was formed. 4 parts of sodium dodecyl sulfate were dissolved in 12 parts of deionized water and stirred until completely dissolved to obtain an aqueous emulsifier solution. Under stirring conditions, the silane solution was added dropwise to the aqueous emulsifier solution at a rate of 0.8 mL / min, and stirring was continued to form a homogeneous silane emulsion.

[0121] The silicon-titanium aerogel dispersion was added to the silane emulsion at a rate of 1.2 mL / min while stirring. The mixture was stirred and reacted at 40 °C for 2 h to ensure that the aerogel was uniformly dispersed in the emulsion and reacted with the silane, thus obtaining the silicon-titanium aerogel modified silane emulsion.

[0122] The preparation method of superhydrophobic self-cleaning natural hydraulic lime plastering mortar is as follows:

[0123] Add 40 parts of natural hydraulic lime, 3 parts of nano silica and 24 parts of water to a mortar mixer and mix at high speed for 5 minutes; slowly add 40 parts of fine aggregate to the mortar mixer and mix at low speed for 5 minutes, then add 5 parts of silicon-titanium aerogel modified silane emulsion, 2 parts of water-reducing agent and 1 part of dispersant, and mix at high speed for 16 minutes to obtain superhydrophobic self-cleaning natural hydraulic lime plastering mortar.

[0124] Example 6

[0125] The preparation method of silicon-titanium aerogel is as follows:

[0126] 15 parts of methyl orthosilicate and 30 parts of anhydrous ethanol were stirred until homogeneous to obtain a silica solution. 40 parts of deionized water were added dropwise to the silica solution at a rate of 1.5 mL / min, causing methyl orthosilicate to undergo hydrolysis and condensation reactions to form a silica sol. 20 parts of tetrabutyl titanate were added to 60 parts of anhydrous ethanol and stirred until homogeneous to obtain a titanium solution. Under stirring conditions, 50 parts of deionized water were added dropwise at a rate of 0.8 mL / min, causing the tetrabutyl titanate to hydrolyze and form a titanium dioxide sol.

[0127] 15 parts of silica sol and 20 parts of titanium dioxide sol were mixed and stirred until homogeneous to obtain a silica-titanium cosol. The silica-titanium cosol was allowed to stand for 6 hours to undergo a spontaneous condensation reaction, forming a three-dimensional network structure and gradually transforming into a silica-titanium gel. The silica-titanium gel was then aged in anhydrous ethanol at 40°C for 24 hours.

[0128] After aging, the gel is washed and carefully placed into a supercritical drying vessel. Liquid carbon dioxide is slowly introduced into the vessel, and the pressure is gradually increased to above the critical pressure of carbon dioxide (7.38 MPa). Simultaneously, the system temperature is maintained below the critical temperature of carbon dioxide (31.1 °C) to keep the carbon dioxide in a liquid state. While maintaining constant pressure, the temperature is gradually increased to above the critical temperature of carbon dioxide (31.1 °C). During this process, the carbon dioxide transitions from a liquid to a supercritical state, eliminating the liquid-gas interface and thus avoiding capillary action. The temperature and pressure are maintained in the supercritical region, and then the pressure is slowly reduced, allowing the supercritical carbon dioxide to be released slowly through the exhaust port. In this process, the carbon dioxide directly transitions from a supercritical state to a gaseous state without passing through a liquid state, thus preventing the collapse of the gel structure. After the carbon dioxide in the system has been completely released, the temperature is gradually reduced to obtain the dried silicon-titanium aerogel.

[0129] The preparation method of silicon-titanium aerogel modified silane emulsion is as follows:

[0130] Eight parts of silicon-titanium aerogel powder were added to 15 parts of deionized water and ultrasonically dispersed at 200kW for 0.5h to ensure that the aerogel particles were uniformly dispersed in the water without agglomeration, thus obtaining a silicon-titanium aerogel dispersion.

[0131] Add 40 parts of silane coupling agent (polydimethylsiloxane) to 40 parts of water and stir until homogeneous to form a silane solution. Dissolve 3 parts of Tween-80 in 15 parts of deionized water and stir until completely dissolved to obtain an emulsifier aqueous solution. Under stirring conditions, add the silane solution dropwise to the emulsifier aqueous solution at a rate of 1 mL / min and continue stirring to form a homogeneous silane emulsion.

[0132] The silicon-titanium aerogel dispersion was added to the silane emulsion at a rate of 1.5 mL / min while stirring. The mixture was stirred and reacted at 40 °C for 2 h to ensure that the aerogel was uniformly dispersed in the emulsion and reacted with the silane, thus obtaining the silicon-titanium aerogel modified silane emulsion.

[0133] The preparation method of superhydrophobic self-cleaning natural hydraulic lime plastering mortar is as follows:

[0134] Add 40 parts of natural hydraulic lime, 3 parts of nano silica and 20 parts of water to a mortar mixer and mix at high speed for 5 minutes; slowly add 40 parts of fine aggregate to the mortar mixer and mix at low speed for 5 minutes, then add 5 parts of silicon-titanium aerogel modified silane emulsion, 2 parts of water-reducing agent and 1 part of dispersant, and mix at high speed for 17 minutes to obtain superhydrophobic self-cleaning natural hydraulic lime plastering mortar.

[0135] Example 7

[0136] The preparation method of silicon-titanium aerogel is as follows:

[0137] 15 parts of tetraethyl orthosilicate and 45 parts of anhydrous ethanol were stirred until homogeneous to obtain a silicon solution. 50 parts of deionized water were added dropwise to the silicon solution at a rate of 1.5 mL / min, causing the tetraethyl orthosilicate to undergo hydrolysis and condensation reactions to form a silica sol. 15 parts of tetrabutyl titanate were added to 45 parts of anhydrous ethanol and stirred until homogeneous to obtain a titanium solution. Under stirring conditions, 50 parts of deionized water were added dropwise at a rate of 0.8 mL / min, causing the tetrabutyl titanate to hydrolyze and form a titanium dioxide sol.

[0138] 15 parts of silica sol and 20 parts of titanium dioxide sol were mixed and stirred until homogeneous to obtain a silica-titanium cosol. The silica-titanium cosol was allowed to stand for 6 hours to undergo a spontaneous condensation reaction, forming a three-dimensional network structure and gradually transforming into a silica-titanium gel. The silica-titanium gel was then aged in anhydrous ethanol at 40°C for 24 hours.

[0139] After aging, the gel is washed and carefully placed into a supercritical drying vessel. Liquid carbon dioxide is slowly introduced into the vessel, and the pressure is gradually increased to above the critical pressure of carbon dioxide (7.38 MPa). Simultaneously, the system temperature is maintained below the critical temperature of carbon dioxide (31.1 °C) to keep the carbon dioxide in a liquid state. While maintaining constant pressure, the temperature is gradually increased to above the critical temperature of carbon dioxide (31.1 °C). During this process, the carbon dioxide transitions from a liquid to a supercritical state, eliminating the liquid-gas interface and thus avoiding capillary action. The temperature and pressure are maintained in the supercritical region, and then the pressure is slowly reduced, allowing the supercritical carbon dioxide to be released slowly through the exhaust port. In this process, the carbon dioxide directly transitions from a supercritical state to a gaseous state without passing through a liquid state, thus preventing the collapse of the gel structure. After the carbon dioxide in the system has been completely released, the temperature is gradually reduced to obtain the dried silicon-titanium aerogel.

[0140] The preparation method of silicon-titanium aerogel modified silane emulsion is as follows:

[0141] Ten parts of silicon-titanium aerogel powder were added to 15 parts of deionized water and ultrasonically dispersed at 200kW for 0.5h to ensure that the aerogel particles were uniformly dispersed in the water without agglomeration, thus obtaining a silicon-titanium aerogel dispersion.

[0142] Add 40 parts of silane coupling agent (trimethylolpropane trimethacrylate) to 40 parts of water and stir until homogeneous to form a silane solution. Dissolve 3 parts of Tween-80 in 12 parts of deionized water and stir until completely dissolved to obtain an emulsifier aqueous solution. Under stirring conditions, add the silane solution dropwise to the emulsifier aqueous solution at a rate of 1 mL / min and continue stirring to form a homogeneous silane emulsion.

[0143] The silicon-titanium aerogel dispersion was added to the silane emulsion at a rate of 1.5 mL / min while stirring. The mixture was stirred and reacted at 40 °C for 1.5 h to ensure that the aerogel was uniformly dispersed in the emulsion and reacted with the silane, thus obtaining the silicon-titanium aerogel modified silane emulsion.

[0144] The preparation method of superhydrophobic self-cleaning natural hydraulic lime plastering mortar is as follows:

[0145] Add 40 parts of natural hydraulic lime, 3 parts of nano silica and 20 parts of water to a mortar mixer and mix at high speed for 5 minutes; slowly add 40 parts of fine aggregate to the mortar mixer and mix at low speed for 5 minutes, then add 5 parts of silicon-titanium aerogel modified silane emulsion, 2 parts of water-reducing agent and 1 part of dispersant, and mix at high speed for 17 minutes to obtain superhydrophobic self-cleaning natural hydraulic lime plastering mortar.

[0146] Performance tests were conducted on the superhydrophobic self-cleaning natural hydraulic lime plastering mortars of Examples 1-7. The fluidity was determined according to GB / T 2419-2005 "Method for Determination of Flowability of Cement Mortar"; the setting time was determined according to Part VIII of JGJ / T70-2009 "Test Methods for Basic Properties of Building Mortar"; the compressive strength was determined according to Part IX of JGJ / T 70-2009 "Test Methods for Basic Properties of Building Mortar"; the bond strength was determined according to Part X of JGJ / T 70-2009 "Test Methods for Basic Properties of Building Mortar"; and the drying shrinkage rate was determined according to Part XII of JGJ / T 70-2009 "Test Methods for Basic Properties of Building Mortar". The test results are shown in Table 1.

[0147] Table 1. Performance test results of the superhydrophobic self-cleaning natural hydraulic lime mortar in the embodiments.

[0148]

[0149] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A superhydrophobic self-cleaning hydraulic lime mortar based on a silicon-titanium aerogel-modified silane emulsion, characterized in that, The superhydrophobic self-cleaning hydraulic lime mortar comprises the following components in parts by weight: 40-50 parts of natural hydraulic lime, 40-100 parts of fine aggregate, 3-10 parts of silicon-titanium aerogel modified silane emulsion, 1-3 parts of nano silica, 0.5-2 parts of water-reducing agent, 0.1-1 parts of dispersant, and 20-30 parts of water. The preparation method of the silicon-titanium aerogel modified silane emulsion includes the following steps: (1) The silicon-titanium aerogel was ultrasonically dispersed in water to obtain a silicon-titanium aerogel dispersion; the silane solution was added dropwise to the emulsifier aqueous solution and stirred to form a silane emulsion; (2) The silicon-titanium aerogel dispersion was added dropwise to the silane emulsion for reaction to obtain a silicon-titanium aerogel modified silane emulsion; The mass ratio of silicon-titanium aerogel to water in step (1) is 5~10:10~15; the silane solution is obtained by mixing silane coupling agent and water, with a mass ratio of silane coupling agent to water of 30~40:20~40; the emulsifier aqueous solution is obtained by dissolving emulsifier in water, with a mass ratio of emulsifier to water of 2~5:10~15. The mass ratio of the silicon-titanium aerogel, silane coupling agent and emulsifier in step (1) is 5~10:30~40:2~5; The silane coupling agent mentioned in step (1) is vinyltriisopropoxysilane; The preparation method of the silicon-titanium aerogel in step (1) is as follows: 1) Mix the silicon source and anhydrous ethanol to obtain a silicon solution, and add water droplets to the silicon solution to form a silica sol; A titanium source and anhydrous ethanol are mixed to obtain a titanium solution. Water is then added to the titanium solution to form a titanium dioxide sol. 2) Silica sol and titanium dioxide sol are mixed to obtain a silica-titanium cosol. The silica-titanium cosol is then subjected to static standing and aging to obtain a gel. 3) The gel is dried by supercritical carbon dioxide to obtain dried silicon-titanium aerogel; In step 1), the mass ratio of silicon source, anhydrous ethanol, and water in the silica sol is 10~15:30~45:20~50, and the dropping rate is 1~2 mL / min; in the titanium dioxide sol, the mass ratio of titanium source, anhydrous ethanol, and water is 10~20:30~60:30~50, and the dropping rate is 0.5~1 mL / min. Step 2) The mass ratio of silica sol to titanium dioxide sol is 10~15:10~20, and the aging time is 12~36h.

2. The superhydrophobic self-cleaning hydraulic lime mortar based on the silicon-titanium aerogel-modified silane emulsion according to claim 1, characterized in that, The silicon source comprises one or more of tetraethyl orthosilicate, methyl orthosilicate, methyltriethoxysilane, propyltrimethoxysilane, and colloidal silica; the titanium source comprises one or two of tetrabutyl titanate and titanium isopropoxide.

3. The superhydrophobic self-cleaning hydraulic lime mortar based on the silicon-titanium aerogel-modified silane emulsion according to claim 1, characterized in that, Step 2) The settling time is 6~12 hours; The aging process is carried out in an aging solution containing one or more of anhydrous ethanol, methanol, isopropanol, and propanol; the aging temperature is 20~60℃.

4. The superhydrophobic self-cleaning hydraulic lime mortar based on the silicon-titanium aerogel-modified silane emulsion according to claim 1, characterized in that, In step 3), during the supercritical carbon dioxide drying process, the system pressure is first controlled to be >7.38MPa and the system temperature to be <31.1℃ to keep the carbon dioxide in a liquid state; then, the temperature and pressure are sequentially increased and decreased. During the heating process, the pressure remains constant and the target temperature is >31.1℃.

5. The superhydrophobic self-cleaning hydraulic lime mortar based on the silicon-titanium aerogel-modified silane emulsion according to claim 1, characterized in that, The emulsifier in step (1) is one or more of Tween-80, sodium dodecyl sulfate, fatty alcohol polyoxyethylene ether, and hexadecyltrimethylammonium chloride.

6. The superhydrophobic self-cleaning hydraulic lime mortar based on the silicon-titanium aerogel-modified silane emulsion according to claim 1, characterized in that, The ultrasonic dispersion power in step (1) is 150~300kW, the ultrasonic dispersion time is 0.5~1h; the dropping rate is 0.5~1.5mL / min, and the stirring rate is 300~600rpm; The dropping rate in step (2) is 1~2 mL / min, the reaction temperature is 30~50℃, the reaction time is 1~3 h, and the stirring rate during the reaction is 400~600 rpm.

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