Light high-strength cement-based composite material doped with cement aerogel and preparation method thereof

Abstract

The invention belongs to the technical field of thermal insulation materials, and relates to a cement aerogel-doped lightweight high-strength cement-based composite material and a preparation method thereof, and the material comprises the following components: cement aerogel powder, hollow glass beads, Portland cement, aluminate cement, silica fume, organic fibers, water and a water reducer in a mass ratio of (6-8): (20-30): (45-65): (2-4): (4-6): (2-3): (8-10): (0.5-1). The preparation method comprises the following steps: (1) preparing raw materials; (2) mixing and stirring; (3) molding by a hot-pressing method; and (4) curing and molding. According to the lightweight high-strength cement-based composite material doped with the cement aerogel prepared by the method, the cement aerogel powder and the lightweight cement-based matrix are cooperated, the performance advantages of the cement aerogel powder and the lightweight cement-based matrix are exerted, the specification requirements of diversified products can be met, and the application prospect is wide.

Description

Technical Field

[0001] This invention relates to a lightweight, high-strength cement-based composite material doped with cement aerogel and its preparation method, belonging to the field of thermal insulation materials technology. Background Technology

[0002] With the advancement of global sustainable development strategies, the demand for energy conservation and emission reduction in the construction sector is becoming increasingly urgent, and the development of high-performance thermal insulation materials has become a key link in achieving green and low-carbon goals.

[0003] Currently, mainstream building insulation materials on the market can be divided into two main categories: organic insulation materials and inorganic insulation materials. Organic insulation materials (such as molded polystyrene boards and extruded polystyrene boards) have advantages such as being lightweight, having low thermal conductivity, and being easy to process. However, their raw material production consumes a lot of energy, and they generally have insufficient high-temperature resistance and fire resistance, posing certain risks to building safety. Inorganic insulation materials (such as rock wool and foamed concrete) have advantages such as being non-combustible, having good durability, and relatively low production costs, making them more in line with the requirements of building fire safety and sustainable development.

[0004] Foamed concrete, as a typical inorganic thermal insulation material, has been widely used in engineering due to its excellent thermal insulation performance, readily available raw materials, and environmental friendliness. However, in order to obtain lower density and thermal conductivity, a large number of pores need to be introduced into foamed concrete, which directly leads to a significant reduction in its mechanical strength, resulting in the common drawbacks of "low strength, high brittleness, and easy cracking." Therefore, how to overcome the technical bottleneck of the difficulty in achieving both lightweight and high strength is the core challenge in developing the next generation of high-performance inorganic thermal insulation materials.

[0005] Aerogel, a solid material with a nanoporous network structure, is hailed as the lightest solid in the world. Its extremely low thermal conductivity makes it an ideal super-insulating material. Theoretically, introducing aerogel particles into a cement matrix could create composite materials with excellent thermal insulation properties. However, in practical applications, this approach faces significant obstacles: First, aerogel itself has extremely low strength, and its surface is typically hydrophobic, resulting in poor compatibility and weak bonding with the hydrophilic cement matrix. Second, incorporating large amounts of aerogel severely compromises the integrity of the cement paste, leading to a sharp decline in the mechanical properties of the composite material (especially compressive and flexural strength). Therefore, commercially available aerogel-based cementitious insulation materials often sacrifice strength to maintain a certain level of insulation, making them unsuitable for applications requiring load-bearing capacity or specific mechanical properties.

[0006] In summary, under the current technological background, it is difficult to prepare cement-based composite materials that simultaneously meet the three key indicators of "low density, high strength, and low thermal conductivity" by simply introducing aerogel or using foaming processes. Developing a novel composite material system and preparation method that can synergistically leverage the excellent thermal insulation properties of aerogel while ensuring sufficient mechanical properties and durability is of significant technological importance and application value. Summary of the Invention

[0007] In view of the shortcomings of the prior art, the present invention aims to solve the core technical problem that it is difficult to simultaneously achieve both strength and thermal insulation performance in aerogel cement-based composite materials. Specifically, it overcomes the defects of significantly reduced mechanical properties of composite materials caused by poor interfacial bonding between aerogel and cement matrix and low inherent strength, and provides a lightweight, high-strength cement-based composite material with low density, high compressive strength, low thermal conductivity and good toughness, as well as an efficient preparation method thereof.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] On the one hand, a lightweight, high-strength cement-based composite material incorporating cement aerogel is provided. This composite material is composed of raw materials including cement aerogel powder, hollow vitrified microspheres, silicate cement, aluminate cement, silica fume, organic fibers, water, and a water-reducing agent, compounded in a specific ratio. The components work synergistically within the system: the cement aerogel powder serves as the core insulation component; the hollow vitrified microspheres act as lightweight, high-strength aggregate; the silicate cement and aluminate cement form a composite cementitious system; the silicate fume acts as an active auxiliary cementitious material; and the organic fibers act as a toughening component.

[0010] Preferably, the cement aerogel powder has hydrophobic properties (contact angle ≥140°) and a suitable particle size. The hollow vitrified microspheres have low bulk density and high compressive strength. The organic fiber is preferably high-strength, high-modulus polyvinyl alcohol fiber. The final properties of the composite material meet the following requirements: apparent density of 700–1000 kg / m³. 3 The compressive strength is not less than 30 MPa, and the thermal conductivity is not higher than 0.25 W / (m·K).

[0011] On the other hand, a method for preparing the aforementioned composite material is provided. The core of this method lies in employing a special process combining hot pressing and high-temperature curing, mainly including the following steps:

[0012] (1) Mixing and stirring: After the dry powder raw materials (cement aerogel powder, cement, silica fume, hollow vitrified microspheres) are mixed evenly in sequence, water and water-reducing agent are added for wet mixing, and organic fibers are added during the stirring process to obtain a semi-dry mixture;

[0013] (2) Hot pressing: The above mixture is placed in a mold and hot pressed under a certain temperature and pressure. After holding the pressure for a period of time, it is demolded.

[0014] (3) High temperature curing: The demolded blank is placed in a high temperature and high humidity environment for curing to obtain the final product.

[0015] Preferably, in the mixing step, the organic fibers are added slowly and in batches to ensure uniform dispersion. Preferably, the hot pressing process uses a specific combination of pressure and temperature ranges.

[0016] On the other hand, specific applications of the aforementioned composite material are provided, namely, its use in the preparation of building exterior wall insulation panels or fireproof isolation strips.

[0017] The advantages of this application, which differ from existing technologies, include:

[0018] 1. Through unique component design and processing, this invention successfully breaks through the traditional limitation that lightweight thermal insulation materials are "lighter means weaker." The resulting composite material maintains a low density (700-1000 kg / m³). 3 While possessing excellent thermal insulation performance (thermal conductivity ≤0.25W / (m·K)), it also has high compressive strength (≥30 MPa), achieving a balance between lightweight, high strength, and thermal insulation.

[0019] 2. Cement aerogel powder with specific particle size and hydrophobicity, combined with dry mixing and specific stirring processes, improves its dispersibility in the cement matrix and reduces defects introduced by agglomeration. The synergy between hollow vitrified microspheres and the composite cementitious system, while introducing pores to reduce density, effectively enhances the overall mechanical properties of the material by contributing its own strength and supporting the matrix.

[0020] 3. The hot pressing molding process adopted significantly improves the initial density of the mixture under the combined effect of temperature and pressure, promotes early hydration, not only shortens the molding cycle, but also makes the internal structure of the product more uniform and has fewer defects, thus obtaining higher early strength and better durability.

[0021] 4. The introduction of high-strength and high-modulus organic fibers (such as polyvinyl alcohol fibers) can form an effective bridging effect in the matrix, inhibit the propagation of cracks, thereby significantly improving the bending toughness and crack resistance of composite materials and enhancing their service reliability.

[0022] 5. The composite material provided by this invention has excellent comprehensive performance and a controllable preparation method. It is very suitable for building components with high requirements for self-weight, thermal insulation, strength and fire resistance, such as integrated thermal insulation panels for building exterior walls, fireproof isolation strips, and lightweight prefabricated walls. It has important engineering application value and market potential. Detailed Implementation

[0023] The following description of the embodiments will provide a more detailed explanation of the specific implementation of the present invention, in order to help those skilled in the art to have a more complete, accurate and in-depth understanding of the inventive concept and technical solution of the present invention.

[0024] In the following specific implementation plan, all materials include the following components by mass ratio: cement aerogel powder: hollow vitrified microspheres: silicate cement: aluminate cement: silica fume: organic fiber: water: water-reducing agent = 6~8: 20~30: 45~65: 2~4: 4~6: 2~3: 8~10: 0.5~1.

[0025] The cement aerogel powder was purchased from Jiangsu Subote Co., Ltd., the hollow vitrified microspheres were purchased from 3M Technology Co., Ltd., the polyvinyl alcohol fiber was purchased from Kuraray (Shanghai) Co., Ltd., and the water-reducing agent was purchased from Jiangsu Subote Co., Ltd.

[0026] Example 1:

[0027] In this embodiment, the composite material comprises the following components by mass ratio: cement aerogel powder: hollow vitrified microspheres: silicate cement: aluminate cement: silica fume: organic fiber: water: water-reducing agent = 8:30:45:2:4:2:8:0.7.

[0028] in:

[0029] The cement aerogel particles are preferably ball-milled, wherein the grinding is performed using a planetary ball mill at a speed of 500 rpm for 3 hours, and the grinding media is 3-5 mm agate balls.

[0030] The silicate cement is P•Ⅰ 52.5 type reference cement, and the aluminate cement is CA-50 type.

[0031] The hollow vitrified microspheres have a median particle size of 35 μm and an apparent density of 450 kg / m³. 3 Its compressive strength is 85 MPa.

[0032] The organic fiber is polyvinyl alcohol fiber with a tensile strength of 1200 MPa, a length of 12 mm, and a single filament diameter of 40 µm.

[0033] The water-reducing agent is a polycarboxylate water-reducing agent, in powder form, with a water reduction rate of 30%.

[0034] The method for preparing the composite material in this embodiment includes the following steps:

[0035] S1. Raw material preparation: Select cement aerogel powder as raw material; select silicate cement and aluminate cement as cementing materials; select silica fume with a particle size of 10-500 nm as auxiliary cementing material; select hollow vitrified microspheres as lightweight aggregate; select polyvinyl alcohol fiber as reinforcing fiber;

[0036] S2. Mixing and Stirring: Weigh out cement aerogel powder, silicate cement, aluminate cement, and silica fume according to the proportion, and dry mix thoroughly to initially disperse the cement aerogel powder; weigh out hollow vitrified microspheres according to the proportion, and dry mix thoroughly; weigh out water and water-reducing agent according to the proportion and add them to the mixed dry materials, and stir at a speed of 200-300 r / min for 3-5 min, during which organic fibers are sprinkled in batches; stir at a speed of 350 r / min for 2-4 min to obtain a semi-dry powder mixture;

[0037] S3. Hot pressing molding: The semi-dry powder mixture obtained in step S2 is placed into the molding mold, the molding parameters are set, a pressure of 20 MPa is applied, the temperature is set to 60℃, and the pressure is held for 25 min. After ensuring that the molding is tight, the mold is demolded to obtain a lightweight high-strength cement-based composite material doped with cement aerogel.

[0038] S4. Curing and Shaping: Place in a high-temperature curing environment of 60℃ and 90-95% RH for 60 hours. Afterward, it can be cured under standard curing conditions of 20 ± 2℃ and 90-95% RH. It can be used for testing and application after one week of curing. The measured properties are as follows: density 700 kg / m³. 3 It has a compressive strength of 32 MPa, a flexural strength of 7.2 MPa, and a thermal conductivity of 0.16 W / (m·K).

[0039] Example 2:

[0040] In this embodiment, the composite material comprises the following components by mass ratio: cement aerogel powder: hollow vitrified microspheres: silicate cement: aluminate cement: silica fume: organic fiber: water: water-reducing agent = 7:25:55:3:5:3:9:0.8.

[0041] in:

[0042] The cement aerogel particles are preferably ball-milled, wherein the grinding is performed using a planetary ball mill at a speed of 500 rpm for 3 hours, and the grinding media is 3-5 mm agate balls.

[0043] The silicate cement is P•Ⅰ 52.5 type reference cement, and the aluminate cement is CA-50 type.

[0044] The hollow vitrified microspheres have a median particle size of 43 μm and an apparent density of 460 kg / m³. 3Its compressive strength is 41 MPa.

[0045] The organic fiber is polyvinyl alcohol fiber with a tensile strength of 1200 MPa, a length of 12 mm, and a single filament diameter of 40 µm.

[0046] The water-reducing agent is a polycarboxylate water-reducing agent, in powder form, with a water reduction rate of 35%.

[0047] The method for preparing the composite material in this embodiment includes the following steps:

[0048] S1. Raw material preparation: Select cement aerogel powder as raw material; select silicate cement and aluminate cement as cementing materials; select silica fume with a particle size of 10-500 nm as auxiliary cementing material; select hollow vitrified microspheres as lightweight aggregate; select polyvinyl alcohol fiber as reinforcing fiber;

[0049] S2. Mixing and Stirring: Weigh out cement aerogel powder, silicate cement, aluminate cement, and silica fume according to the proportion, and dry mix thoroughly to initially disperse the cement aerogel powder; weigh out hollow vitrified microspheres according to the proportion, and dry mix thoroughly; weigh out water and water-reducing agent according to the proportion and add them to the mixed dry materials, and stir at a speed of 200-300 r / min for 3-5 min, during which organic fibers are sprinkled in batches; stir at a speed of 350 r / min for 2-4 min to obtain a semi-dry powder mixture;

[0050] S3. Hot pressing molding: The semi-dry powder mixture obtained in step S2 is placed into the molding mold, the molding parameters are set, a pressure of 20 MPa is applied, the temperature is set to 60℃, and the pressure is held for 20 min. After ensuring that the molding is tight, the mold is demolded to obtain a lightweight high-strength cement-based composite material doped with cement aerogel.

[0051] S4. Curing and Shaping: Place in a high-temperature curing environment of 60℃ and 90-95% RH for 48 hours. Afterward, it can be cured under standard curing conditions of 20 ± 2℃ and 90-95% RH. It can be used for testing and application after one week of curing. The measured properties are as follows: density 850 kg / m³. 3 It has a compressive strength of 46 MPa, a flexural strength of 8.5 MPa, and a thermal conductivity of 0.20 W / (m·K).

[0052] Example 3:

[0053] In this embodiment, the composite material comprises the following components by mass ratio: cement aerogel powder: hollow vitrified microspheres: silicate cement: aluminate cement: silica fume: organic fiber: water: water-reducing agent = 6:20:65:3:5:2:10:1.

[0054] in:

[0055] The cement aerogel particles were not ball-milled and the particle size range was 20~80 μm.

[0056] The silicate cement is P•Ⅰ 42.5 type reference cement, and the aluminate cement is CA-50 type.

[0057] The hollow vitrified microspheres have a median particle size of 43 μm and an apparent density of 450 kg / m³. 3 Its compressive strength is 41 MPa.

[0058] The organic fiber is polyvinyl alcohol fiber, with a tensile strength exceeding 1600 MPa, a length of 12 mm, and a single filament diameter of 38 µm.

[0059] The water-reducing agent is a polycarboxylate water-reducing agent, in powder form, with a water reduction rate of 30%.

[0060] The method for preparing the composite material in this embodiment includes the following steps:

[0061] S1. Raw material preparation: Select cement aerogel powder as raw material; select silicate cement and aluminate cement as cementing materials; select silica fume with a particle size of 10-500 nm as auxiliary cementing material; select hollow vitrified microspheres as lightweight aggregate; select polyvinyl alcohol fiber as reinforcing fiber;

[0062] S2. Mixing and Stirring: Weigh out cement aerogel powder, silicate cement, aluminate cement, and silica fume according to the proportion, and dry mix thoroughly to initially disperse the cement aerogel powder; weigh out hollow vitrified microspheres according to the proportion, and dry mix thoroughly; weigh out water and water-reducing agent according to the proportion and add them to the mixed dry materials, and stir at a speed of 200-300 r / min for 3-5 min, during which organic fibers are sprinkled in batches; stir at a speed of 350 r / min for 2-4 min to obtain a semi-dry powder mixture;

[0063] S3. Hot pressing molding: The semi-dry powder mixture obtained in step S2 is placed into the molding mold, the molding parameters are set, a pressure of 15 MPa is applied, the temperature is set to 60 ℃, and the pressure is held for 20 min. After ensuring that the molding is tight, the mold is demolded to obtain a lightweight high-strength cement-based composite material doped with cement aerogel.

[0064] S4. Curing and Shaping: Place in a high-temperature curing environment of 80℃ and 90-95% RH for 48 hours. Afterward, it can be cured under standard curing conditions of 20 ± 2℃ and 90-95% RH. It can be used for testing and application after one week of curing. The measured properties are as follows: density 980 kg / m³. 3It has a compressive strength of 51 MPa, a flexural strength of 9.1 MPa, and a thermal conductivity of 0.25 W / (m·K).

[0065] Examples 1-3 above demonstrate that the composite material prepared by this invention possesses lightweight, high strength, and excellent thermal insulation properties. Based on these properties, this composite material is particularly suitable for building components with high requirements for weight, strength, and thermal insulation / fireproofing. For example, it can be directly used for molding or cutting to prepare high-performance building exterior wall insulation panels or fireproof barriers.

[0066] In summary, this invention provides a lightweight, high-strength cement-based composite material doped with cement aerogel and its preparation method. This material can provide the industry with new high-performance thermal insulation materials, which has important practical significance for promoting technological progress and innovation, achieving sustainable development goals, and facilitating the practical application of cement aerogel.

[0067] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A lightweight, high-strength cement-based composite material doped with cement aerogel, characterized in that, According to the mass ratio, it includes the following components: Cement aerogel powder: hollow vitrified microspheres: silicate cement: aluminate cement: silica fume: organic fiber: water: water-reducing agent = 6~8: 20~30: 45~65: 2~4: 4~6: 2~3: 8~10: 0.5~1.

2. The composite material according to claim 1, characterized in that: The cement aerogel powder has a particle size of 20~80 μm and a contact angle ≥140°.

3. The composite material according to claim 1, characterized in that: The hollow vitrified microspheres have a particle size of 1–100 μm and a bulk density of ≤500 kg / m³. 3 .

4. The composite material according to claim 1, characterized in that: The organic fiber is polyvinyl alcohol fiber, with a single filament diameter of 0.02-0.04 mm, a fiber length of 10-15 mm, a tensile strength ≥1200 MPa, and an elastic modulus ≥30 GPa.

5. The composite material according to claim 1, characterized in that: The water-reducing agent is a polycarboxylate-based water-reducing agent with a water reduction rate of 30-35%.

6. The composite material according to claim 1, characterized in that: The silicate cement has a strength grade of 42.5 or higher; the aluminate cement has a calcium aluminate content of ≥65% and a strength grade of 42.5 or higher; the silica fume has a SiO2 content of ≥65% and a specific surface area of ​​≥10000 m². 2 / kg.

7. The composite material according to claim 1, characterized in that: Its apparent density is 700–1000 kg / m³ 3 The compressive strength is not less than 30 MPa, and the thermal conductivity is not higher than 0.25 W / (m·K).

8. A method for preparing a lightweight, high-strength cement-based composite material doped with cement aerogel according to any one of claims 1 to 7, characterized in that: Includes the following steps: S1. Mixing and stirring: Weigh cement aerogel powder, silicate cement, aluminate cement and silica fume according to the proportions described in claim 1, and dry mix them; then add the weighed hollow vitrified microspheres and continue dry mixing; then add the weighed water and water-reducing agent, and stir at a speed of 200-300 r / min for 3-5 min, during which organic fibers are added; finally, stir at a speed of 350 r / min for 2-4 min to obtain a semi-dry powder mixture; S2. Hot pressing molding: The semi-dry powder mixture is placed into a molding mold and held under pressure of 15-20 MPa and temperature of 60-80°C for 20-30 min, and then demolded to obtain a composite material blank; S3. Curing and molding: The composite material preform is cured at 60-80℃ and 90-95% RH for 48-60 hours.

9. The preparation method according to claim 8, characterized in that, In step S1, the organic fiber is polyvinyl alcohol fiber, which is added slowly and in batches.

10. Use of the composite material according to any one of claims 1 to 7 in the preparation of building exterior wall insulation panels or fireproof isolation strips.