Aerogel foamed cement composite board, preparation method and application thereof

Abstract

The application discloses aerogel foamed cement composite board, a preparation method and application thereof, which is composed of a foamed cement base and in-situ formed silica aerogel in the pores thereof; the silica aerogel is a hollow mesoporous structure modified by a silane coupling agent, and accounts for 0.5-2.5 wt% of the total mass of the cementitious material. The application has the beneficial effects that: a composite structure with a foamed cement skeleton support and in-pore aerogel filling is constructed by a vacuum impregnation method; the foamed cement provides macroscopic mechanical strength, while the nanopore aerogel divides the millimeter-level pores into multi-level pores of micro-nano scale, greatly increases the heat flow path, and significantly reduces the thermal conductivity; the in-situ formed nano-aerogel can fill and bridge the micro-cracks of the foamed cement pore wall, plays a reinforcing role, and makes the compressive strength increase by 27.3% to more than 0.56 MPa; and the thermal insulation performance stability and the freeze-thaw resistance of the material in a humid environment are improved.

Description

Technical Field

[0001] This invention relates to the field of building energy-saving materials technology, and in particular to an aerogel foamed cement composite board, its preparation method and its application. Background Technology

[0002] Foamed cement is widely used in building insulation due to its advantages such as being lightweight, non-combustible, and low-cost. However, traditional foamed cement has drawbacks such as high thermal conductivity (typically ≥0.065 W / (m·K)) and low compressive strength (≤0.44 MPa), which limit its application in buildings with high energy efficiency requirements. Silica aerogel, as a nanoporous material, has extremely low thermal conductivity (≤0.018 W / (m·K)) and is an ideal insulation reinforcement material.

[0003] In existing technologies, the composite of aerogels with cement-based materials is mostly achieved through physical blending. For example, patent CN107858050A proposes a method of directly incorporating aerogel powder into cement paste. However, this method has significant drawbacks: aerogel nanoparticles tend to agglomerate during stirring, making uniform dispersion difficult; simultaneously, the high specific surface area of ​​aerogels drastically increases the water demand for cement hydration and may disrupt the formation of cement hydration products, leading to a significant decrease in the mechanical strength of the composite material. Another patent, CN114592354A, proposes the preparation of SiO2-Al2O3 composite aerogels, but its application focuses on flexible fabric coatings, failing to address the issues of dispersibility, compatibility, and strength loss in rigid cement matrices. Furthermore, the hydrophilicity of aerogels leads to a decline in their thermal insulation performance in humid environments.

[0004] Therefore, it is necessary to propose an aerogel foamed cement composite board, its preparation method and its application to address the above-mentioned technical problems. This board can effectively combine the excellent thermal insulation properties of aerogel with the structural advantages of foamed cement, while also taking into account mechanical strength and durability. Summary of the Invention

[0005] To address the shortcomings of the existing technologies, the present invention aims to provide an aerogel foamed cement composite board, its preparation method, and its application. The invention employs a vacuum impregnation process to effectively introduce a modified silica aerogel precursor solution into the pores of a pre-prepared foamed cement matrix under negative pressure, thereby achieving in-situ gelation and fixation of the aerogel within the pores and avoiding the defects of physical blending methods.

[0006] An aerogel foamed cement composite insulation board is composed of a foamed cement matrix and silica aerogel formed in situ within its pores; the silica aerogel is a hollow mesoporous structure modified with a silane coupling agent, accounting for 0.5-2.5 wt% of the total mass of the cementitious material.

[0007] The density of the composite insulation board is ≤310kg / m³. 3 Compressive strength ≥ 0.56 MPa, thermal conductivity ≤ 0.058 W / (m·K).

[0008] The raw materials of the foamed cement matrix, by mass parts, include: 100 parts of silicate cement, 20-40 parts of fly ash, 7-9 parts of foaming agent (hydrogen peroxide, concentration 30%), 0.5-1 parts of water-reducing agent, and a water-cement ratio of 0.5.

[0009] The foaming agent used is 30% hydrogen peroxide.

[0010] The silica aerogel is an ultralight aerogel modified with silane coupling agent HY-6085, with a density of 75 kg / m³. 3 Specific surface area ≥600m² 2 / g.

[0011] A method for preparing an aerogel-foamed cement composite insulation board, comprising the following steps: S1. Preparation of foamed cement matrix: Cement, fly ash, water and water-reducing agent are mixed and stirred, foaming agent is added and foamed, then injected into mold and cured to obtain porous foamed cement board; S2. Vacuum impregnation: Place the foamed cement board in a vacuum tank and inject an aerogel precursor solution prepared by tetraethyl orthosilicate, ethanol, deionized water and hydrochloric acid in proportion under a negative pressure of -0.08MPa. Maintain the negative pressure for 30 minutes to allow the solution to fully penetrate. S3. Gelification and hydrophobic modification: The impregnated board is allowed to stand at 25°C to complete gelation, and then immersed in an ethanol solution containing 5wt% hexamethyldisilazane (HMDS) for 24 hours to age and perform hydrophobic modification. S4. Drying and curing: The modified board is dried at 60°C and normal pressure for 48 hours to obtain the composite insulation board.

[0012] The aerogel precursor solution described in step S2 has the following composition ratio: tetraethyl orthosilicate (TEOS): anhydrous ethanol: deionized water: HCl (catalyst) = 1:4:2:0.01 (molar ratio).

[0013] Application of an aerogel foamed cement composite insulation board in building exterior wall insulation systems.

[0014] Compared with the prior art, the present invention has the following advantages: 1. Synergistic Composite Structure: A composite structure consisting of "foamed cement skeleton support + aerogel filling within the pores" was constructed using a vacuum impregnation method. Foamed cement provides macroscopic mechanical strength, while the nanoporous aerogel divides millimeter-sized pores into multi-level pores at the micro-nano scale, greatly increasing the heat flow path and significantly reducing the thermal conductivity (29.2% lower than traditional foamed cement).

[0015] 2. Excellent mechanical properties: The in-situ formed nano-aerogel can fill and bridge the microcracks in the pore walls of foamed cement, playing a reinforcing role and increasing the compressive strength by 27.3% to over 0.56MPa, overcoming the drawback of strength reduction caused by physical blending.

[0016] 3. Environmental adaptability: The thermochromic properties enable intelligent temperature regulation, and the performance remains stable in environments ranging from -40℃ to 120℃. Attached Figure Description

[0017] Figure 1 This is a flowchart of the preparation method of the present invention. Detailed Implementation

[0018] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0019] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings, but the present invention can be implemented in many different ways as defined and covered by the claims.

[0020] like Figure 1 As shown, an aerogel foamed cement composite insulation board is composed of a foamed cement matrix and silica aerogel formed in situ within its pores; the silica aerogel is a hollow mesoporous structure modified with a silane coupling agent, accounting for 0.5-2.5 wt% of the total mass of the cementitious material.

[0021] The density of the composite insulation board is ≤310kg / m³. 3 Compressive strength ≥ 0.56 MPa, thermal conductivity ≤ 0.058 W / (m·K).

[0022] The raw materials of the foamed cement matrix, by mass parts, include: 100 parts of silicate cement, 20-40 parts of fly ash, 7-9 parts of foaming agent (hydrogen peroxide, concentration 30%), 0.5-1 parts of water-reducing agent, and a water-cement ratio of 0.5.

[0023] The foaming agent used is 30% hydrogen peroxide.

[0024] The silica aerogel is an ultralight aerogel modified with silane coupling agent HY-6085, with a density of 75 kg / m³. 3 Specific surface area ≥600m²2 / g.

[0025] A method for preparing an aerogel-foamed cement composite insulation board, comprising the following steps: S1. Preparation of foamed cement matrix: Cement, fly ash, water and water-reducing agent are mixed and stirred, foaming agent is added and foamed, then injected into mold and cured to obtain porous foamed cement board; S2. Vacuum impregnation: Place the foamed cement board in a vacuum tank and inject an aerogel precursor solution prepared by tetraethyl orthosilicate, ethanol, deionized water and hydrochloric acid in proportion under a negative pressure of -0.08MPa. Maintain the negative pressure for 30 minutes to allow the solution to fully penetrate. S3. Gelification and hydrophobic modification: The impregnated board is allowed to stand at 25°C to complete gelation, and then immersed in an ethanol solution containing 5wt% hexamethyldisilazane (HMDS) for 24 hours to age and perform hydrophobic modification. S4. Drying and curing: The modified board is dried at 60°C and normal pressure for 48 hours to obtain the composite insulation board.

[0026] The aerogel precursor solution described in step S2 has the following composition ratio: tetraethyl orthosilicate (TEOS): anhydrous ethanol: deionized water: HCl (catalyst) = 1:4:2:0.01 (molar ratio).

[0027] Application of an aerogel foamed cement composite insulation board in building exterior wall insulation systems.

[0028] Compared with the prior art, the present invention has the following advantages: 1. Synergistic Composite Structure: A composite structure consisting of "foamed cement skeleton support + aerogel filling within the pores" was constructed using a vacuum impregnation method. Foamed cement provides macroscopic mechanical strength, while the nanoporous aerogel divides millimeter-sized pores into multi-level pores at the micro-nano scale, greatly increasing the heat flow path and significantly reducing the thermal conductivity (29.2% lower than traditional foamed cement).

[0029] 2. Excellent mechanical properties: The in-situ formed nano-aerogel can fill and bridge the microcracks in the pore walls of foamed cement, playing a reinforcing role and increasing the compressive strength by 27.3% to over 0.56MPa, overcoming the drawback of strength reduction caused by physical blending.

[0030] 3. Environmental adaptability: The thermochromic properties enable intelligent temperature regulation, and the performance remains stable in environments ranging from -40℃ to 120℃.

[0031] Example 1: Coating Preparation Raw material ratio: 100kg P·O42.5 silicate cement, 30kg fly ash, water-cement ratio 0.5, 0.8kg water-reducing agent, 8kg 30% hydrogen peroxide (percentage of cementitious material mass). The aerogel precursor solution is prepared according to TEOS:ethanol:water:HCl=1:4:2:0.01 (molar ratio).

[0032] Preparation process: 1. Mix cement, fly ash, water, and water-reducing agent. Add hydrogen peroxide and stir quickly. Pour the mixture into a mold and cure at room temperature for 72 hours to obtain a density of approximately 400 kg / m³. 3 Porous foamed cement board.

[0033] 2. Place the cement board in a vacuum chamber, evacuate to -0.08MPa, inject the precursor solution and maintain the negative pressure for 30 minutes.

[0034] 3. Remove the board and let it stand at 25℃ for 30 minutes to complete the gelation.

[0035] 4. Immerse the gelled board in a 5% HMDS / ethanol solution and age it at 25°C for 24 hours.

[0036] 5. Place the board in a 60℃ oven and dry it under normal pressure for 48 hours to obtain the composite insulation board.

[0037] Performance test: The density of the obtained composite insulation board is 309.4 kg / m³. 3 It has a compressive strength of 0.56 MPa and a thermal conductivity of 0.046 W / (m·K).

[0038] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. An aerogel-foamed cement composite insulation board, characterized in that: The composite insulation board is composed of a foamed cement matrix and silica aerogel formed in situ within its pores; the silica aerogel is a hollow mesoporous structure modified with a silane coupling agent, accounting for 0.5-2.5 wt% of the total mass of the cementitious material.

2. The aerogel foamed cement composite insulation board according to claim 1, characterized in that: The density of the composite insulation board is ≤310kg / m³. 3 Compressive strength ≥ 0.56 MPa, thermal conductivity ≤ 0.058 W / (m·K).

3. The aerogel foamed cement composite insulation board according to claim 1, characterized in that: The raw materials of the foamed cement matrix, by mass parts, include: 100 parts of silicate cement, 20-40 parts of fly ash, 7-9 parts of foaming agent, 0.5-1 parts of water-reducing agent, and a water-cement ratio of 0.

5.

4. The aerogel foamed cement composite insulation board according to claim 3, characterized in that: The foaming agent used is 30% hydrogen peroxide.

5. The aerogel foamed cement composite insulation board according to claim 1, characterized in that: The silica aerogel is an ultralight aerogel modified with silane coupling agent HY-6085, with a density of 75 kg / m³. 3 Specific surface area ≥600m² 2 / g.

6. A method for preparing an aerogel-foamed cement composite insulation board as described in any one of claims 1-5, characterized in that: Its preparation method includes the following steps: S1. Preparation of foamed cement matrix: Cement, fly ash, water and water-reducing agent are mixed and stirred, foaming agent is added and foamed, then injected into mold and cured to obtain porous foamed cement board; S2. Vacuum impregnation: Place the foamed cement board in a vacuum tank and inject an aerogel precursor solution prepared by tetraethyl orthosilicate, ethanol, deionized water and hydrochloric acid in proportion under a negative pressure of -0.08MPa. Maintain the negative pressure for 30 minutes to allow the solution to fully penetrate. S3. Gelification and hydrophobic modification: The impregnated board is allowed to stand at 25°C to complete gelation, and then immersed in an ethanol solution containing 5wt% hexamethyldisilazane for 24 hours to age and perform hydrophobic modification. S4. Drying and curing: The modified board is dried at 60°C and normal pressure for 48 hours to obtain the composite insulation board.

7. The method for preparing an aerogel-foamed cement composite insulation board according to claim 6, characterized in that: The aerogel precursor solution described in step S2 has the following composition ratio: tetraethyl orthosilicate: anhydrous ethanol: deionized water: HCl = 1:4:2:0.

01.

8. The application of the aerogel foamed cement composite insulation board as described in any one of claims 1-5 in a building exterior wall insulation system.

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