Gel nano thermal insulation mortar and preparation method thereof

Abstract

The application relates to the technical field of building thermal insulation materials, and particularly discloses a gel nano thermal insulation mortar and a preparation method thereof. The gel nano thermal insulation mortar is prepared from the following raw materials in parts by mass: vitrified microbeads 75-85 parts, hydrophobic pretreated nano silicon dioxide aerogel 90-110 parts, modified potassium silicate solution 310-330 parts, deionized water 430-470 parts, dispersant 4-6 parts, wetting agent 1.5-2 parts, composite defoaming agent 4-5 parts, hydroxyethyl cellulose 2.5-3.5 parts, quaternary ammonium salt 9-11 parts, thickening agent 2-4 parts, mildewproof and alga-resistant agent 2-4 parts, preservative 2-4 parts, bactericide 0.4-0.6 parts and isobutanol amine 0.8-1.2 parts. The gel nano thermal insulation mortar prepared by the application realizes synchronous optimization of thermal insulation performance and mechanical performance.

Description

Technical Field

[0001] This application relates to the technical field of building insulation materials, and more specifically, it relates to a gel nano-insulating mortar and its preparation method. Background Technology

[0002] Building energy conservation is a key area for achieving the "dual carbon" strategic goals, and developing high-performance external wall insulation materials is an effective way to reduce building energy consumption. Nano-silica aerogel, with its unique nanoporous three-dimensional network structure, can effectively reduce convection and solid-state heat conduction, exhibiting extremely excellent thermal insulation performance. Its application in building insulation is expected to significantly reduce insulation layer thickness and improve energy efficiency.

[0003] Currently, to improve the performance of traditional thermal insulation mortar, it is widely explored to combine nano-silica aerogel as a functional filler with inorganic cementitious materials. Among them, silicate cement is the most commonly chosen cementitious matrix due to its wide availability, low cost, and high strength. The typical approach is as follows: cement is used as the main cementitious material, supplemented with mineral admixtures such as fly ash and silica fume, and vitrified microspheres are used as lightweight aggregates to provide basic thermal insulation. Finally, a small amount of nano-aerogel powder is added through physical mixing to further reduce the thermal conductivity of the composite material.

[0004] Patent application CN102910870A discloses a nano-silica aerogel / vitrified microsphere composite thermal insulation mortar, which is composed of the following raw materials in parts by weight: silicate cement 70-80, fly ash 15-20, modified diatomaceous earth 10-20, heavy calcium carbonate 10-15, nano-silica aerogel 10-20, vitrified microspheres 10-20, redispersible latex powder 0.5-1, cellulose ether 0.5-1, wood fiber 0.2-0.3, and polyimide fiber 0.1-0.2.

[0005] In this technical solution, the cement hydration process creates a strongly alkaline environment. The surface of the nano-silica aerogel is rich in silanol groups, which are prone to hydrolysis under strongly alkaline conditions. This leads to the erosion and collapse of its three-dimensional nanoporous framework, resulting in a significant decrease in thermal insulation performance over time. Furthermore, the hydrophilic cement matrix and the hydrophobic nano-aerogel have poor interfacial compatibility, exhibiting significant phase separation and low stress transfer efficiency, making it difficult to improve the material's mechanical strength. Summary of the Invention

[0006] In order to simultaneously optimize the thermal insulation performance and mechanical properties of thermal insulation mortar, this application provides a gel nano-thermal insulation mortar and its preparation method.

[0007] In the first aspect, this application provides a gel nano-insulating mortar, which adopts the following technical solution:

[0008] A gel nano-insulating mortar is prepared from the following raw materials in parts by weight:

[0009] The composition includes: 75-85 parts vitrified microspheres, 90-110 parts hydrophobically pretreated nano-silica aerogel, 310-330 parts modified potassium silicate solution, 430-470 parts deionized water, 4-6 parts dispersant, 1.5-2 parts wetting agent, 4-5 parts composite defoamer, 2.5-3.5 parts hydroxyethyl cellulose, 9-11 parts quaternary ammonium salt, 2-4 parts thickener, 2-4 parts antifungal and antialgae agent, 2-4 parts preservative, 0.4-0.6 parts bactericide, and 0.8-1.2 parts isobutanolamine.

[0010] The modified potassium silicate solution is prepared by modifying a potassium silicate solution with a mass concentration of 30%~35% with vinylsilane and tetraethoxysilane.

[0011] In this technical solution, firstly, a stable interfacial protective layer is constructed through hydrophobic functionalization of the aerogel surface, effectively reducing the erosion of the nanostructure by the alkaline environment and ensuring the ultra-low thermal conductivity of the material during long-term service. Secondly, the bonding system is molecularly designed using organic-inorganic hybrid technology, significantly enhancing the interfacial compatibility between the aerogel and the potassium silicate matrix, achieving efficient stress transfer. Furthermore, the cross-linking network formed by tetraethoxysilane strengthens the mortar's framework system, greatly improving the overall mechanical properties. Ultimately, the prepared thermal insulation mortar possesses both excellent mechanical strength and superior thermal insulation performance.

[0012] Preferably, the specific preparation method of the modified potassium silicate solution includes the following steps:

[0013] Add potassium silicate solution to the reactor, heat to 50-70℃, add vinylsilane and tetraethoxysilane, adjust the pH to 8-9, react for 3-5 hours, cool, and obtain modified potassium silicate solution.

[0014] Preferably, the mass ratio of the potassium silicate solution, vinylsilane and tetraethoxysilane is 100:(3~5):(2~4).

[0015] In this technical solution, based on potassium silicate solution, under mild alkaline conditions, vinyl silane incorporates organic vinyl groups into the potassium silicate molecular chain through hydrolysis and condensation, enhancing its interfacial compatibility with hydrophobic aerogel. Meanwhile, tetraethoxysilane, with its multifunctional advantages, can generate polyhydroxysiloxanes after hydrolysis that can simultaneously condense with multiple potassium silicate molecular chains, crosslinking the originally linear potassium silicate structure into a denser three-dimensional network structure, significantly improving the strength and stability of the binder skeleton.

[0016] Preferably, the quaternary ammonium salt is 2-hydroxypropyltrimethylammonium chloride.

[0017] Preferably, the method for preparing the hydrophobically pretreated nano-silica aerogel includes the following steps:

[0018] S1: Mix the modified component containing hydrophobic groups with an aqueous ethanol solution until homogeneous, adjust the pH to 4-5, heat to 50-70℃, react for 3-5 hours, cool, and obtain a pre-hydrolyzed solution;

[0019] S2: Place the nano-silica aerogel in a reactor, heat it to 50~70℃, spray in the pre-hydrolyzed solution, keep it at the temperature for 40~60min, cool it, and dry it to obtain the hydrophobic pretreated nano-silica aerogel.

[0020] Preferably, the modified component containing hydrophobic groups is selected from at least one of methyltrimethoxysilane and polydimethylsiloxane.

[0021] Preferably, the mass ratio of the nano-silica aerogel, the modified component containing hydrophobic groups, and the ethanol aqueous solution is 100:(3~5):(40~60).

[0022] In this technical solution, hydrophobic groups are firmly grafted onto the aerogel framework through liquid phase surface modification, which effectively reduces its surface energy and enables it to exist stably in the subsequent aqueous slurry system, reducing the collapse of the nanoporous structure and the increase in thermal conductivity caused by water intrusion.

[0023] More preferably, the modified component containing hydrophobic groups is composed of methyltrimethoxysilane and polydimethylsiloxane in a mass ratio of (3~4):1.

[0024] In this technical solution, methyltrimethoxysilane is used to permanently anchor the hydrophobic methyl group with Si-O-Si covalent bonds through the condensation reaction of methoxy groups with silanol groups on the surface of the aerogel, thus constructing a basic hydrophobic layer and ensuring hydrophobic durability. Polydimethylsiloxane, on the other hand, is physically adsorbed on the surface and pores of the aerogel due to its low surface energy characteristics, filling the hydrophobic blind zone and enhancing the anti-water adhesion ability. The two work together to achieve an all-round and durable hydrophobic effect.

[0025] Preferably, the composite defoamer includes polyether-modified siloxanes, polyethylene glycol dioleate, and hydrophobic nano-silica.

[0026] More preferably, the polyether-modified siloxane is a polyether-modified heptamethyltrisiloxane.

[0027] In this technical solution, polyether-modified siloxanes can rapidly disrupt large bubble liquid films and reduce the generation of new bubbles; polyethylene glycol dioleate, in synergy with hydrophobic nano-silica, targets microbubbles by reducing surface tension and the intervention of nanoparticles, promoting microbubble coalescence and escape. This synergistic approach achieves highly efficient defoaming throughout the mixing, transportation, and application processes, ensuring high density of the slurry and uniform performance of the final product.

[0028] Preferably, the bactericide is Hoffmann QB-20.

[0029] Preferably, the preservative is Hoffmann Defros BM.

[0030] Preferably, the wetting agent is Dow BD-109.

[0031] Preferably, the gel nano-insulating mortar further includes 1.5 to 3 parts by weight of wollastonite fiber.

[0032] Preferably, the wollastonite fibers undergo the following pretreatment steps before use:

[0033] S11: Add aminosilane to an aqueous ethanol solution, adjust the pH to 4-5, heat to 60-70℃, react for 3-5 hours, cool, and obtain aminosilane hydrolysate;

[0034] S12: Place wollastonite fibers in a reactor, spray in aminosilane hydrolysate, and then dry to obtain pretreated wollastonite fibers.

[0035] Preferably, the mass ratio of wollastonite fiber to aminosilane is 1:(0.2~0.3).

[0036] Preferably, the gel nano-insulating mortar further includes 0.8 to 1.5 parts by weight of hemihydrate gypsum and 0.3 to 0.5 parts by weight of calcium formate.

[0037] Secondly, this application provides a method for preparing gel nano-insulating mortar, comprising the following steps:

[0038] Deionized water, bactericide, hydroxyethyl cellulose, quaternary ammonium salt, isobutanolamine, dispersant, wetting agent, antifungal and antialgae agent, preservative and part of the composite defoamer are mixed evenly, nano silica aerogel and vitrified microspheres are added and mixed evenly, modified potassium silicate solution, thickener and the remaining defoamer are added and mixed evenly to obtain gel nano thermal insulation mortar.

[0039] In this technical solution, an aqueous dispersion system is first pre-constructed to create a uniform medium environment for the subsequent difficult-to-disperse lightweight fillers. Then, nano-silica aerogel and vitrified microspheres are introduced to achieve complete wetting and encapsulation of the vitrified microsphere particles, maximizing the preservation of their thermal insulation performance. Next, a modified potassium silicate solution is introduced, which can spread and penetrate more evenly after contacting the pre-wetted vitrified microspheres, forming a dense encapsulated and bonded network through gradual gelation. Finally, the final adjustment and defoaming operations optimize the slurry's construction performance while ensuring the compactness of the material's internal structure.

[0040] Preferably, after adding the modified potassium silicate solution, the step of adding wollastonite fibers is also included.

[0041] Preferably, after adding the modified potassium silicate solution, the method further includes adding hemihydrate gypsum and calcium formate.

[0042] In summary, this application has the following beneficial effects:

[0043] 1. This application constructs a stable hydrophobic protective layer on the surface of nano-silica aerogel by performing hydrophobic pretreatment, which effectively reduces the erosion of the nanoporous structure by the alkaline environment and ensures the long-term stability of the material's ultra-low thermal conductivity. Furthermore, it uses vinylsilane and tetraethoxysilane to synergistically modify potassium silicate solution. Vinylsilane enhances the interfacial compatibility between the binder and the hydrophobic aerogel, while tetraethoxysilane significantly strengthens the bonding skeleton by forming a three-dimensional cross-linked network, thereby enabling the material to still have high compressive strength at low dry density.

[0044] 2. The optimized composite defoamer system and formulation process in this application ensure the high density of the internal structure of the material, giving it excellent water resistance, alkali resistance, washability and artificial weathering resistance. Detailed Implementation

[0045] The present application will be further described in detail below with reference to the embodiments.

[0046] Unless otherwise specified, the raw materials used in the embodiments and comparative examples of this application are all commercially available.

[0047] The particle size distribution of the vitrified microspheres is 40 mesh to 70 mesh;

[0048] Polydimethylsiloxane, with a number average molecular weight of 5000~20000 g / mol; polyethylene glycol dioleate, with a molecular weight of 400~600 g / mol for the hydrophilic polyethylene glycol portion; and polyether-modified heptamethyltrisiloxane, with a molecular weight of 800~1200 g / mol.

[0049] Preparation Examples 1-3: Modified Potassium Silicate Solutions

[0050] Preparation Example 1

[0051] The preparation method of the modified potassium silicate solution in this preparation example includes the following steps:

[0052] Add 1000g of potassium silicate solution to the reactor, heat to 60℃, add 40g of vinyltrimethoxysilane and 30g of tetraethoxysilane, adjust the pH to 8.5 with 5% hydrochloric acid, stir the reaction for 4 hours, and cool to room temperature to obtain modified potassium silicate solution.

[0053] The potassium silicate solution has a mass concentration of 35%.

[0054] Preparation Example 2

[0055] The preparation method of the modified potassium silicate solution in this preparation example includes the following steps:

[0056] Add 1000g of potassium silicate solution to the reactor, heat to 50℃, add 30g of vinyltrimethoxysilane and 40g of tetraethoxysilane, adjust the pH to 8 with 5% hydrochloric acid, stir the reaction for 5h, cool to room temperature, and obtain modified potassium silicate solution.

[0057] The potassium silicate solution has a mass concentration of 30%.

[0058] Preparation Example 3

[0059] The preparation method of the modified potassium silicate solution in this preparation example includes the following steps:

[0060] Add 1000g of potassium silicate solution to the reactor, heat to 70℃, add 50g of vinyltrimethoxysilane and 20g of tetraethoxysilane, adjust the pH to 9 with 5% hydrochloric acid, stir the reaction for 3 hours, cool to room temperature, and obtain modified potassium silicate solution.

[0061] The potassium silicate solution has a mass concentration of 35%.

[0062] Preparation Examples 4-6: Hydrophobic Pretreated Nano-Silica Aerogels

[0063] Preparation Example 4

[0064] The preparation method of the hydrophobically pretreated nano-silica aerogel in this example includes the following steps:

[0065] S1: Mix 6g of methyltrimethoxysilane and 40g of aqueous ethanol solution in a container, adjust the pH to 5 with 5% dilute hydrochloric acid, heat to 50℃, stir for 5h, cool to room temperature to obtain pre-hydrolyzed solution;

[0066] S2: Place 200g of nano-silica aerogel powder in a rotary instrument, heat it to 50℃, spray it evenly with pre-hydrolyzed liquid, keep it at the temperature for 60min after spraying, cool it to room temperature, and dry it with supercritical carbon dioxide to obtain hydrophobic pretreated nano-silica aerogel.

[0067] In the ethanol-water solution, the volume ratio of ethanol to water is 4:1.

[0068] Preparation Example 5

[0069] The preparation method of the hydrophobically pretreated nano-silica aerogel in this example includes the following steps:

[0070] S1: Mix 6g of methyltrimethoxysilane, 2g of polydimethylsiloxane and 50g of ethanol aqueous solution in a container, adjust the pH to 4.5 with 5% hydrochloric acid, heat to 60℃, stir and react for 4h, cool to room temperature to obtain pre-hydrolyzed solution;

[0071] S2: Place 200g of nano-silica aerogel powder in a rotary instrument, heat it to 60℃, spray it evenly with pre-hydrolyzed solution, keep it warm for 50min after spraying, cool it to room temperature, and dry it with supercritical carbon dioxide to obtain hydrophobic pretreated nano-silica aerogel.

[0072] In the ethanol-water solution, the volume ratio of ethanol to water is 4:1.

[0073] Preparation Example 6

[0074] The preparation method of the hydrophobically pretreated nano-silica aerogel in this example includes the following steps:

[0075] S1: Mix 8g of methyltrimethoxysilane, 2g of polydimethylsiloxane and 60g of ethanol aqueous solution in a container, adjust the pH to 4 with 5% dilute hydrochloric acid, heat to 70℃, stir for 3h, cool to room temperature to obtain pre-hydrolyzed solution.

[0076] S2: Place 200g of nano-silica aerogel powder in a rotary instrument, heat it to 70℃, spray it evenly with pre-hydrolyzed solution, keep it at the temperature for 50min after spraying, cool it to room temperature, and dry it with supercritical carbon dioxide to obtain hydrophobic pretreated nano-silica aerogel.

[0077] In the ethanol-water solution, the volume ratio of ethanol to water is 5:1.

[0078] Example 1

[0079] The preparation method of gel nano-insulating mortar in this embodiment includes the following steps:

[0080] Add 450g of deionized water to a mixer, turn on the mixer, and set the speed to 500 rpm. Then, add 0.5g of bactericide, 3g of hydroxyethyl cellulose, 10g of quaternary ammonium salt, 1g of isobutanolamine, 5g of dispersant, 1.8g of wetting agent, 3g of antifungal and antialgae agent, 3g of preservative, and 3g of polyether-modified heptamethyltrisiloxane in sequence. Stir and mix for 5 minutes. Slowly add 100g of nano-silica aerogel and 80g of vitrified microspheres. Increase the speed to 800 rpm and stir and mix for 20 minutes. Then, adjust the speed to 300 rpm and add 320g of modified potassium silicate solution and premix (1.4g of polyethylene glycol dioleate, 0.1g of hydrophobic nano-silica, 3g of thickener, and 10g of deionized water, which are stirred and mixed evenly at 1000 rpm). Continue stirring and mixing for 10 minutes to obtain gel nano-insulating mortar.

[0081] The dispersant was sodium polycarboxylate; the wetting agent was Dow BD-109; the quaternary ammonium salt was 2-hydroxypropyltrimethylammonium chloride; the nano-silica aerogel was from Preparation Example 4; the modified potassium silicate solution was from Preparation Example 1; the thickener was Dow TT-935; the preservative was Hoffmann Defros BM; the antifungal and antialgal agents were 2g of isothiazolinone and 1g of benzimidazole; and the bactericide was Hoffmann QB-20.

[0082] Example 2

[0083] The preparation method of gel nano-insulating mortar in this embodiment includes the following steps:

[0084] Add 430g of deionized water to a mixer, turn on the mixer, and set the speed to 500 rpm. Then add 0.4g of bactericide, 2.5g of hydroxyethyl cellulose, 9g of quaternary ammonium salt, 0.8g of isobutanolamine, 4g of dispersant, 1.5g of wetting agent, 2g of antifungal and antialgae agent, 2g of preservative, and 2.7g of polyether-modified heptamethyltrisiloxane in sequence. Stir and mix for 5 minutes. Slowly add 90g of nano-silica aerogel and 75g of vitrified microspheres. Increase the speed to 800 rpm and stir and mix for 20 minutes. Then adjust the speed to 300 rpm and add 310g of modified potassium silicate solution and premix (1.2g of polyethylene glycol dioleate, 0.1g of hydrophobic nano-silica, 2g of thickener, and 10g of deionized water, which are stirred and mixed evenly at 1200 rpm). Continue stirring and mixing for 10 minutes to obtain gel nano-insulating mortar.

[0085] The dispersant was sodium polycarboxylate; the wetting agent was Dow BD-109; the quaternary ammonium salt was 2-hydroxypropyltrimethylammonium chloride; the nano-silica aerogel was from Preparation Example 5; the modified potassium silicate solution was from Preparation Example 2; the thickener was Dow TT-935; the preservative was Hoffmann Defros BM; the antifungal and antialgal agents were 1.5g of isothiazolinone and 0.5g of benzimidazole; and the bactericide was Hoffmann QB-20.

[0086] Example 3

[0087] The preparation method of gel nano-insulating mortar in this embodiment includes the following steps:

[0088] Add 470g of deionized water to a mixer, turn on the mixer, and set the speed to 500 rpm. Then add 0.6g of bactericide, 3.5g of hydroxyethyl cellulose, 11g of quaternary ammonium salt, 1.2g of isobutanolamine, 6g of dispersant, 2g of wetting agent, 4g of antifungal and antialgae agent, 4g of preservative, and 3g of polyether-modified heptamethyltrisiloxane in sequence. Stir and mix for 5 minutes. Slowly add 110g of nano-silica aerogel and 85g of vitrified microspheres. Increase the speed to 800 rpm and stir and mix for 20 minutes. Then adjust the speed to 300 rpm and add 330g of modified potassium silicate solution and premix (1.85g of polyethylene glycol dioleate, 0.15g of hydrophobic nano-silica, 4g of thickener, and 10g of deionized water, which are stirred and mixed evenly at 1200 rpm). Continue stirring and mixing for 10 minutes to obtain gel nano-insulating mortar.

[0089] The dispersant was sodium polycarboxylate; the wetting agent was Dow BD-109; the quaternary ammonium salt was 2-hydroxypropyltrimethylammonium chloride; the nano-silica aerogel was from Preparation Example 6; the modified potassium silicate solution was from Preparation Example 3; the thickener was Dow TT-935; the preservative was Hoffmann Defros BM; the antifungal and antialgal agents were 3g of isothiazolinone and 1g of benzimidazole; and the bactericide was Hoffmann QB-20.

[0090] Example 4

[0091] The difference between this embodiment and embodiment 3 is as follows:

[0092] After adding the modified potassium silicate solution, the process also includes adding 1.5g of wollastonite fiber.

[0093] Before use, wollastonite fibers undergo the following pretreatment steps:

[0094] S11: Add 0.3g of 3-aminopropyltriethoxysilane to 10g of ethanol aqueous solution, adjust the pH to 4 with 5% dilute hydrochloric acid, heat to 60℃, stir for 5h, cool to room temperature to obtain aminosilane hydrolysate.

[0095] S12: Add 1.5g of wollastonite fiber to a rotary instrument, spray aminosilane hydrolysate evenly, and dry at 60℃ for 1.5h to obtain pretreated wollastonite fiber.

[0096] In the ethanol-water solution, the volume ratio of ethanol to water is 1:3; all the pretreated wollastonite fibers are added, and the particle size distribution of the wollastonite fibers is 30~70μm; the modified potassium silicate solution is from Preparation Example 1.

[0097] Everything else is the same as in Example 3.

[0098] Example 5

[0099] The difference between this embodiment and embodiment 4 is that:

[0100] The amount of wollastonite fiber used is 3g;

[0101] Before use, wollastonite fibers undergo the following pretreatment steps:

[0102] S11: Add 0.9g of 3-aminopropyltriethoxysilane to 20g of ethanol aqueous solution, adjust the pH to 5 with 5% dilute hydrochloric acid, heat to 70℃, stir for 3h, cool to room temperature to obtain aminosilane hydrolysate.

[0103] S12: Add 3g of wollastonite fiber to a rotary instrument, spray aminosilane hydrolysate evenly, and dry at 60℃ for 3h to obtain pretreated wollastonite fiber.

[0104] In the ethanol-water solution, the volume ratio of ethanol to water is 1:4; all the pretreated wollastonite fibers are added, and the particle size distribution of the wollastonite fibers is 30~70μm.

[0105] The rest is the same as in Example 4.

[0106] Example 6

[0107] The difference between this embodiment and embodiment 5 is as follows:

[0108] After adding the modified potassium silicate solution, the steps also include adding 0.8g of hemihydrate gypsum powder and 0.3g of calcium formate;

[0109] The rest is the same as in Example 5.

[0110] Example 7

[0111] The difference between this embodiment and embodiment 6 is that:

[0112] The dosage of hemihydrate gypsum powder is 1.5g; the dosage of calcium formate is 0.5g.

[0113] The rest is the same as in Example 6.

[0114] Comparative Example 1

[0115] The difference between this comparative example and Example 1 is as follows:

[0116] The preparation method of the modified potassium silicate solution in this comparative example includes the following steps:

[0117] Add 1000g of potassium silicate solution to the reactor, heat to 60℃, add 70g of vinyltrimethoxysilane, adjust the pH to 8.5 with 5% hydrochloric acid, stir the reaction for 4 hours, and cool to room temperature to obtain modified potassium silicate solution.

[0118] The potassium silicate solution has a mass concentration of 35%.

[0119] Everything else is the same as in Example 1.

[0120] Comparative Example 2

[0121] The difference between this comparative example and Example 1 is as follows:

[0122] Nano-silica aerogels were not pretreated for hydrophobicity;

[0123] Everything else is the same as in Example 1.

[0124] Comparative Example 3

[0125] The difference between this comparative example and Example 1 is as follows:

[0126] The composite defoamer consists of 3g of polyether-modified heptamethyltrisiloxane and 1.4g of polyethylene glycol dioleate.

[0127] Everything else is the same as in Example 1.

[0128] Performance testing

[0129] Based on GB / T 20473-2021 "Building Thermal Insulation Mortar" and industry requirements for thermal insulation materials, the gel nano thermal insulation mortars prepared in Examples 1-7 and Comparative Examples 1-3 were prepared and cured to the specified age (28 days) in a standard laboratory environment (temperature 23±2℃, relative humidity 50±5%) and then tested. The test results are shown in Tables 1 and 2.

[0130] Table 1. Basic physical properties and short-term durability tests of gel nano-insulating mortars prepared in Examples 1-7 and Comparative Examples 1-3

[0131]

[0132] Table 2. Long-term durability and environmental performance tests of gel nano-insulating mortars prepared in Examples 1-7 and Comparative Examples 1-3.

[0133]

[0134] Analysis of the performance test data in Tables 1-2 shows that the gel nano-insulating mortars prepared in Examples 1-7 all exhibit low dry density, high compressive strength, and relatively low thermal conductivity, while also possessing excellent water resistance, alkali resistance, washability, and aging resistance. This is mainly attributed to the hydrophobic pretreatment of the nano-silica aerogel, which effectively maintains the nanoporous structure to ensure thermal insulation. The potassium silicate solution modified by vinyltrimethoxysilane and tetraethoxysilane constructs a high-strength, highly compatible inorganic-organic hybrid bonding network, achieving a firm encapsulation and stress transfer of the functional filler. The introduction of wollastonite fiber, hemihydrate gypsum powder, and calcium formate significantly improves compressive strength while maintaining low dry density and ultra-low thermal conductivity, indicating that the introduction of wollastonite fiber, hemihydrate gypsum powder, and calcium formate effectively optimizes the pore structure and solid-phase skeleton strength of the mortar, achieving simultaneous optimization of mechanical and thermal insulation properties.

[0135] As shown in Comparative Example 1, the absence of tetraethoxysilane crosslinking in the modified potassium silicate solution resulted in a significant decrease in strength despite similar density. As shown in Comparative Example 2, the lack of hydrophobic treatment in the nano-silica aerogel led to a significant increase in dry density and thermal conductivity. As shown in Comparative Example 3, the absence of hydrophobic nano-silica in the composite defoamer had a relatively small impact on mechanical properties, but it resulted in microbubble residue, which in turn caused foaming in the aging resistance test.

[0136] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A gel nano-insulating mortar, characterized in that, It is prepared from the following raw materials in parts by weight: The composition includes: 75-85 parts vitrified microspheres, 90-110 parts hydrophobically pretreated nano-silica aerogel, 310-330 parts modified potassium silicate solution, 430-470 parts deionized water, 4-6 parts dispersant, 1.5-2 parts wetting agent, 4-5 parts composite defoamer, 2.5-3.5 parts hydroxyethyl cellulose, 9-11 parts quaternary ammonium salt, 2-4 parts thickener, 2-4 parts antifungal and antialgae agent, 2-4 parts preservative, 0.4-0.6 parts bactericide, 0.8-1.2 parts isobutanolamine, 1.5-3 parts wollastonite fiber, 0.8-1.5 parts hemihydrate gypsum, and 0.3-0.5 parts calcium formate; The method for preparing the modified potassium silicate solution includes the following steps: Add a 30%~35% potassium silicate solution to the reactor, heat to 50~70℃, add vinylsilane and tetraethoxysilane, adjust the pH to 8~9, react for 3~5 hours, cool, and the product is obtained. The composite defoamer includes polyether-modified siloxanes, polyethylene glycol dioleate, and hydrophobic nano silica. Before use, the wollastonite fibers undergo the following pretreatment steps: S11: Add aminosilane to an aqueous ethanol solution, adjust the pH to 4-5, heat to 60-70℃, react for 3-5 hours, cool, and obtain an aminosilane hydrolysate. S12: Place wollastonite fibers in a reactor, spray in aminosilane hydrolysate, and then dry to obtain pretreated wollastonite fibers.

2. The gel nano-insulating mortar according to claim 1, characterized in that, The mass ratio of the potassium silicate solution, vinylsilane and tetraethoxysilane is 100:(3~5):(2~4).

3. The gel nano-insulating mortar according to claim 1, characterized in that, The preparation method of the hydrophobically pretreated nano-silica aerogel includes the following steps: S1: Mix the modified component containing hydrophobic groups with an aqueous ethanol solution until homogeneous, adjust the pH to 4-5, heat to 50-70℃, react for 3-5 hours, cool, and obtain the pre-hydrolyzed solution; S2: Place the nano-silica aerogel in a reactor, heat it to 50~70℃, spray in the pre-hydrolyzed solution, keep it at the temperature for 40~60min, cool it, and dry it to obtain the hydrophobic pretreated nano-silica aerogel.

4. The gel nano-insulating mortar according to claim 3, characterized in that, The modified component containing hydrophobic groups is selected from at least one of methyltrimethoxysilane and polydimethylsiloxane.

5. The gel nano-insulating mortar according to claim 1, characterized in that, The polyether-modified siloxane is a polyether-modified heptamethyltrisiloxane.

6. A method for preparing gel nano-insulating mortar as described in any one of claims 1 to 5, characterized in that: The process includes the following steps: mixing deionized water, bactericide, hydroxyethyl cellulose, quaternary ammonium salt, isobutanolamine, dispersant, wetting agent, antifungal and antialgae agent, preservative and part of the composite defoamer evenly; adding hydrophobically pretreated nano silica aerogel and vitrified microspheres and mixing evenly; adding modified potassium silicate solution, thickener and the remaining composite defoamer and mixing evenly to obtain gel nano thermal insulation mortar; After adding the modified potassium silicate solution, the process also includes adding wollastonite fibers. After adding the modified potassium silicate solution, the process also includes adding hemihydrate gypsum and calcium formate.

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