A high performance low carbon aerated concrete and preparation method thereof

Abstract

The invention discloses a high-performance low-carbon aerated concrete and a preparation method thereof, which relates to the technical field of aerated concrete. In the manufacturing process of existing aerated concrete products, a new type of additional material is added. The new type of additional material consists of sodium hydroxide, bauxite and water, which can improve the pore microstructure of autoclaved aerated concrete and reduce the thermal conductivity coefficient, so as to prepare a high-performance low-carbon aerated concrete product with low bulk density, high strength and good thermal insulation performance, which has a subversive change on the existing ultra-low energy consumption wall in terms of safety, fire prevention and durability.

Description

Technical Field

[0001] The invention relates to the technical field of aerated concrete, in particular to a high-performance low-carbon aerated concrete and a preparation method thereof. Background Art

[0002] Unlike single-family buildings in Europe and the United States, most of my country's ultra-low energy consumption buildings are multi-story buildings. With the implementation of increasingly stringent energy-saving policies, the safety and durability of the thick insulation in ultra-low energy consumption walls in building applications have become technical difficulties that need to be solved for ultra-low energy consumption walls.

[0003] In order to meet the needs of sustainable development and energy conservation, low-energy consumption aerated concrete products for building walls are developed. According to building standards and requirements, the current common autoclaved aerated concrete has a high thermal conductivity coefficient on the basis of ensuring that the load-bearing strength of the building's exterior wall is not less than 3.5Mpa and the thickness of the exterior wall is 300mm, but it cannot meet the requirement of 80% of the energy saving effect of the self-insulation of a single wall. Aerated concrete is applied externally or sandwich composites are used to replace other insulation materials, such as polystyrene boards, rock wool and other insulation materials. However, polystyrene boards cannot meet the fire protection requirements and there are many fire hazards. Although rock wool has improved in fire protection, there is still the problem of cracking of heavy insulation walls, especially the insulation of high-rise building exterior walls falling off, which brings safety hazards. Whether it is the exterior wall of the building that is applied externally with aerated concrete or sandwich composites with other insulation products, there are quality problems of aging and powdering, which cannot meet the requirements of the same life as the building, and there are also other defects such as condensation and cold and hot bridges.

[0004] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention and should not be regarded as an acknowledgment or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art. Summary of the invention

[0005] The object of the present invention is to provide a high-performance low-carbon aerated concrete and a preparation method thereof, which can solve the problems of poor strength and high thermal conductivity of ordinary autoclaved aerated concrete.

[0006] To achieve the above-mentioned object, the present invention provides a high-performance low-carbon aerated concrete, comprising dry material and wet material, wherein the dry material comprises cement and lime, and the wet material comprises mortar, waste slurry and a gas generating agent. The high-performance low-carbon aerated concrete further comprises a new type of additive, wherein the new type of additive is prepared by hydrothermal polymerization of sodium hydroxide, bauxite and water at a temperature of 160°C for 0.5-2 hours, wherein the mass ratio of bauxite to sodium hydroxide is 1:1-4, and the mass ratio of the sum of the masses of bauxite and sodium hydroxide to water is 1:1-2.

[0007] Preferably, the gas generating agent is aluminum paste.

[0008] Preferably, the sodium hydroxide, bauxite and water are subjected to hydrothermal polymerization in a sealed stirred reactor.

[0009] The present invention also provides a method for preparing high-performance low-carbon aerated concrete, comprising the following steps:

[0010] (1) preparing a novel additive material, comprising mixing sodium hydroxide, bauxite and water to form a mixed slurry, wherein the mass ratio of bauxite to sodium hydroxide is 1:1-4, and the mass ratio of the sum of the mass of bauxite and sodium hydroxide to water is 1:1-2, and the mixed slurry is heated to 160° C. in a sealed stirred reactor for hydrothermal polymerization, and the reaction is carried out at a constant temperature for 0.5-2 hours to obtain a novel additive material;

[0011] (2) preparing high-performance low-carbon aerated concrete by mixing dry materials, wet materials and the novel admixture, wherein the dry materials include cement and lime, and the wet materials include mortar, waste slurry and gas generating agent, and performing pouring, pre-curing, cutting and steam-curing to prepare a finished high-performance low-carbon aerated concrete.

[0012] Furthermore, in step (2), the pouring temperature is 40-50° C., and the diffusion of the pouring slurry is 300 mm; the pre-curing temperature is 45-55° C., the pre-curing humidity is not less than 30%, the pre-curing time is controlled at 210-240 minutes, and a blank mold is obtained after pre-curing; the blank mold cutting hardness is 350-450 mm, and the blank mold cutting temperature is controlled at about 70° C.; vacuum is drawn for 0.5 hour before steam curing, the steam curing temperature is raised for 2 hours, and during the steam curing process, the steam curing pressure is not less than 1.2 MPa, the constant temperature of steam curing is 190° C., the constant temperature time of steam curing is not less than 6 hours, and after the steam curing is completed, the temperature is lowered for 2 hours.

[0013] Compared with the prior art, the high-performance low-carbon aerated concrete and the preparation method thereof according to the present invention have the following beneficial effects:

[0014] The new admixture is composed of sodium hydroxide, bauxite and water. The new admixture is added to the reaction system of dry and wet materials of aerated concrete, which effectively improves the stability of the castable of aerated concrete and reduces the pore defects in the gasification process of aluminum paste or aluminum powder, so as to achieve the purpose of improving the compressive strength of aerated concrete and reducing the thermal conductivity, and obtain high-performance low-carbon aerated concrete with low bulk density, high strength and low thermal conductivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a process flow chart of a method for preparing high-performance low-carbon aerated concrete according to one embodiment of the present invention;

[0016] Figure 2 This is a thermal conductivity test trend chart of thermal conductivity analysis data of autoclaved aerated concrete B04A3.5 according to one embodiment of the present invention.

[0017] Figure 3 5 μm microscopic picture of a novel additional material according to an embodiment of the present invention.

[0018] Figure 4 20 μm microscopic picture of a novel additional material according to an embodiment of the present invention.

[0019] Figure 5 This is a 5 μm microscopic picture of high-performance low-carbon aerated concrete according to one embodiment of the present invention.

[0020] Figure 6 This is a 20 μm microscopic picture of high performance low carbon aerated concrete according to one embodiment of the present invention. DETAILED DESCRIPTION

[0021] The specific implementation modes of the present invention are described in detail below in conjunction with the accompanying drawings, but it should be understood that the protection scope of the present invention is not limited by the specific implementation modes.

[0022] Unless explicitly stated otherwise, throughout the specification and claims, the term “comprise” or variations such as “include” or “comprising”, etc., will be understood to include the stated elements or components but not to exclude other elements or components.

[0023] According to a preferred embodiment of the present invention, a high-performance low-carbon aerated concrete and a preparation method thereof are provided. In the manufacturing process of existing aerated concrete products, new external materials are added to improve the pore microstructure of autoclaved aerated concrete and reduce the thermal conductivity coefficient, so as to prepare high-performance low-carbon aerated concrete products with low bulk density, high strength and good thermal insulation performance, which have subversive changes to existing ultra-low energy consumption walls in terms of safety, fire prevention and durability.

[0024] High-performance low-carbon aerated concrete includes dry materials, wet materials and new admixtures. The weight of dry materials accounts for about 20%, the weight of wet materials accounts for about 79%, and the weight of new admixtures accounts for about 1%. The dry materials include cement and lime, and the wet materials include mortar, waste slurry and gas generating agents, among which aluminum paste is selected as the gas generating agent.

[0025] The new additive material is a mixed slurry composed of sodium hydroxide, bauxite and water, wherein the mass ratio of bauxite to sodium hydroxide is 1:1-4; the mass ratio of bauxite to water is 1:3-5; the mass ratio of sodium hydroxide to water is 1:2-3; the mass ratio of the sum of the mass of bauxite and sodium hydroxide to water is 1:1-2; the mixed slurry is heated to 160°C under the condition of sealing in a stirred reactor for wet heat polymerization, and the reaction is carried out at a constant temperature for 0.5-2 hours to obtain the new additive material. The stirred reactor is a vertical stirred reactor, and a tubular fluidized bed reactor or other reaction device can also be used. The stirred reactor can be heated by electric heating or by other methods such as steam to ensure the heat for the reaction.

[0026] Adding new admixtures to the aerated concrete system effectively improves the stability of the aerated concrete castable, reduces the pore defects in the gasification process of aluminum paste or aluminum powder, and achieves the purpose of improving the compressive strength of aerated concrete and reducing the thermal conductivity. Ultimately, a functional building material with low bulk density, high strength and low thermal conductivity, high-performance low-carbon aerated concrete, is achieved.

[0027] like Figure 1 As shown, the preparation method of high-performance low-carbon aerated concrete comprises the following steps:

[0028] (1) preparing a novel additive material, preparing a mixed slurry of sodium hydroxide, bauxite and water, wherein the mass ratio of bauxite to sodium hydroxide is 1:1-4; the mass ratio of bauxite to water is 1:3-5; the mass ratio of sodium hydroxide to water is 1:2-3; the mass ratio of the sum of the mass of bauxite and sodium hydroxide to water is 1:1-2; raising the temperature of the mixed slurry to 160°C under the condition of sealing in a stirred reactor for wet thermal polymerization, and the reaction is carried out at a constant temperature for about 1 hour to obtain a novel additive material;

[0029] (2) Prepare high-performance low-carbon aerated concrete by mixing dry materials, wet materials and new admixtures in a weight ratio of 20:79:1, wherein the dry materials include cement and lime, and the wet materials include mortar, waste slurry and gas generating agent, wherein the gas generating agent is aluminum paste, and perform pouring, pre-curing, cutting and steam curing. The pouring temperature is 40-50°C, the casting material diffusion is 300 mm, the pre-curing temperature is 45-55°C, the pre-curing humidity is not less than 30%, and the pre-curing time is controlled at 210-240 minutes. The blank mold is obtained after pre-curing. The cutting hardness of the blank mold is 350-450mm. The cutting temperature of the blank mold is controlled at about 70℃. Vacuum is drawn for 0.5 hour before steam-curing to remove the air in the steam-curing kettle that affects the heat exchange, so as to improve the heat exchange effect between the water vapor and the blank. The steam-curing heating time is 2 hours, the steam-curing constant temperature is 190℃, the steam-curing pressure is not less than 1.2MPa, the steam-curing constant temperature time is not less than 6h, and the steam-curing is completed with a cooling time of 2 hours to make a finished high-performance low-carbon aerated concrete.

[0030] The new type of additive material is sodium hydroxide, bauxite and water, which are first subjected to a 160℃ wet heat polymerization reaction for about 1 hour in proportion to obtain a material, which is then fully mixed with dry and wet materials, poured, cured, cut and steamed to obtain high-performance low-carbon aerated concrete. Figure 3 As shown in the 5μm microscopic picture of the new added material, Figure 4 As shown in the 20μm microscopic picture of the new admixture, the microscopic characteristics of the new admixture are fiber bundles, which can play a good stabilizing and reinforcing role for low bulk density aerated concrete of grade B04 and below.

[0031] like Figure 5 As shown in the 5μm microscopic picture of high performance low carbon aerated concrete, Figure 6 As shown in the 20μm microscopic picture of high-performance low-carbon aerated concrete, the high-performance low-carbon aerated concrete produced is sand-based aerated concrete, whose main characteristics are low bulk density, high strength and low thermal conductivity.

[0032] like Figure 2 As shown in the figure, the thermal conductivity analysis data of autoclaved aerated concrete B04A3.5 shows that the thermal conductivity is 0.103W / mk. As shown in Table 1, the inspection data of high-performance low-carbon aerated concrete, including bulk density, strength and thermal conductivity, strictly follow the GB / T11969-2020 autoclaved aerated concrete performance test method, and conduct quality spot checks on different parts of GB / T 11968-2020 autoclaved aerated concrete blocks and GB / T 15762-2020 autoclaved aerated concrete boards. The thermal conductivity reaches 0.103W / mk, and the performance fully reaches and exceeds the quality standard of autoclaved aerated concrete B04A3.5.

[0033] Table 1 Test data of high performance low carbon aerated concrete

[0034]

[0035]

[0036] The foregoing description of specific exemplary embodiments of the present invention is for the purpose of illustration and demonstration. These descriptions are not intended to limit the present invention to the precise form disclosed, and it is clear that many changes and variations can be made based on the above teachings. The purpose of selecting and describing the exemplary embodiments is to explain the specific principles of the present invention and its practical application, so that those skilled in the art can realize and utilize various different exemplary embodiments of the present invention and various different selections and changes. The scope of the present invention is intended to be limited by the claims and their equivalents.

Claims

1. A high-performance low-carbon aerated concrete, comprising dry material and wet material, wherein the dry material comprises cement and lime, and the wet material comprises mortar, waste slurry and a gas generating agent, characterized in that: The high-performance low-carbon aerated concrete also includes a new type of additive material, which is prepared by hydrothermal polymerization of sodium hydroxide, bauxite and water at 160°C for 0.5-2 hours, wherein the mass ratio of bauxite to sodium hydroxide is 1:1-4, and the mass ratio of the sum of the masses of bauxite and sodium hydroxide to water is 1:1-2, and the microscopic feature of the new type of additive material is fiber bundle shape.

2. The high performance low carbon aerated concrete according to claim 1, characterized in that: The gas generating agent is aluminum paste.

3. The high performance low carbon aerated concrete according to claim 1, characterized in that: The sodium hydroxide, bauxite and water are subjected to hydrothermal polymerization in a sealed stirred reactor.

4. The method for preparing high-performance low-carbon aerated concrete according to claim 1, comprising the following steps: (1) preparing a novel additive material, comprising preparing a mixed slurry of sodium hydroxide, bauxite and water, wherein the mass ratio of bauxite to sodium hydroxide is 1:1-4, and the mass ratio of the sum of the mass of bauxite and sodium hydroxide to water is 1:1-2, and raising the temperature of the mixed slurry to 160° C. in a sealed stirred reactor for hydrothermal polymerization, and reacting at a constant temperature for 0.5-2 hours to obtain a novel additive material; (2) Preparing high-performance low-carbon aerated concrete by mixing dry materials, wet materials and the novel admixture, wherein the dry materials include cement and lime, and the wet materials include mortar, waste slurry and gas generating agent, and performing pouring, pre-curing, cutting and steam-curing to prepare a finished high-performance low-carbon aerated concrete.

5. The method for preparing high-performance low-carbon aerated concrete according to claim 4, characterized in that: In step (2), the pouring temperature is 40-50°C; the pre-curing temperature is 45-55°C, the casting material expansion is 300mm, the pre-curing humidity is not less than 30%, the pre-curing time is controlled at 210-240 minutes, and a blank mold is obtained after pre-curing; the blank mold cutting hardness is 350-450mm, and the blank mold cutting temperature is controlled at 70°C; vacuum is drawn for 0.5 hour before steam curing, the steam curing temperature is increased for 2 hours, the steam curing pressure is not less than 1.2MPa during the steam curing process, the constant temperature of the steam curing is 190°C, the constant temperature time of the steam curing is not less than 6h, and the steam curing is completed and the temperature is lowered for 2 hours.

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