Carbon dioxide foam concrete as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of concrete, and particularly relates to carbon dioxide foam concrete as well as a preparation method and application thereof. Comprising the following steps: obtaining a gel raw material comprising cement, a nano filler and a mineral admixture, and preparing the gel raw material into cement paste; the preparation method comprises the following steps: preparing a foaming solution from a hydrogel thickener, a water repellent agent, a foaming agent and water, and introducing gas containing carbon dioxide to prepare carbon dioxide foam; carbon dioxide foam and cement paste are mixed to prepare mixed paste, and the mixed paste is formed to obtain a formed concrete blank; and performing internal carbonization curing and external carbonization curing on the concrete green body, and performing natural curing to obtain the carbon dioxide foam concrete. Through internal and external carbonization maintenance, a large amount of carbon sequestration is realized, micropores are filled by virtue of a product generated by carbonization, the aperture is refined, the collapse of a foam structure is reduced, the foam concrete is enhanced, the compressive strength and durability of the carbon dioxide foam concrete are improved, and the durability of the carbon dioxide foam concrete can be enhanced.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of concrete, and particularly relates to a carbon dioxide foam concrete as well as a preparation method and application thereof. BACKGROUND

[0002] Carbon dioxide (CO2) is a major greenhouse gas, and its massive emission promotes global warming and causes great pressure on the environment. Reducing CO2 emission or sequestrating the emitted CO2 gas to achieve net zero emission has become the goal of the industry and stakeholders in formulating the carbon neutral roadmap. The construction industry is a major source of global carbon emission, accounting for about 40%, most of which comes from cement and concrete production. Therefore, it is imperative to develop effective carbon dioxide capture and utilization technology.

[0003] In recent years, concrete carbonation curing technology has attracted more and more attention as an efficient CO2 sequestration approach. The basic principle of this method is to capture CO2 by chemically converting cement minerals (such as C2S and C3S) and their hydration products (such as calcium hydroxide and C-S-H gel) into carbonates. Concrete carbonation solidification technology has three obvious advantages: first, the consumption of concrete is large, about 30 billion tons per year, which shows great potential for carbon dioxide utilization and storage. Second, carbonation can permanently sequester CO2 inside the concrete matrix, which guarantees long-term storage of CO2. Finally, carbonation curing can effectively improve the microstructure of concrete, thereby improving the mechanical properties and durability of concrete. However, the dense concrete matrix limits its effectiveness in capturing and sequestering carbon dioxide.

[0004] In recent years, the development of foam concrete that can sequester a large amount of carbon dioxide has attracted increasing interest from scholars and engineers. Foam concrete is a typical lightweight concrete material (density generally 500kg / m 3 ~ 1600kg / m 3 ), which has excellent properties such as low density, low thermal conductivity, good sound insulation and fireproof performance, and excellent CO2 capture capacity. By improving the porosity, pore specific surface area and other structures of concrete, the efficiency of CO2 capture and sequestration in concrete is improved. In addition to carbonation curing, the use of CO2 foam to manufacture foam concrete products also provides a potential way to stabilize CO2. However, to achieve efficient utilization of CO2 in foam concrete, several key issues need to be addressed: 1) the compressive strength of foam concrete is relatively low, which is increasingly difficult to meet the needs of modern buildings; 2) the porous nature of foam concrete makes it less durable; 3) due to the high water solubility and alkaline reactivity of CO2, the stability of CO2 foam is usually poor, and it will quickly break down after being mixed into the cement paste, causing the collapse of the foam structure and affecting the final performance of the product. SUMMARY

[0005] The application aims to provide a carbon dioxide foam concrete, a preparation method and application thereof, and aims to solve the problems of low compressive strength, poor durability and easy collapse of pore structure of the existing carbon dioxide foam concrete.

[0006] To achieve the above application purposes, the technical scheme adopted by the application is as follows.

[0007] In a first aspect, the application provides a preparation method of a carbon dioxide foam concrete, comprising the following steps:

[0008] Obtaining gel raw materials including cement, nano filler and mineral admixture, and preparing cement paste from the gel raw materials;

[0009] Preparing a foaming liquid from hydrogel thickening agent, hydrophobic agent, foaming agent and water, and preparing carbon dioxide foam by introducing carbon dioxide-containing gas;

[0010] Mixing and processing the carbon dioxide foam and the cement paste to prepare a mixed paste, and performing forming processing to obtain a formed concrete blank;

[0011] Performing internal carbonation curing and external carbonation curing on the concrete blank, and naturally curing to obtain the carbon dioxide foam concrete.

[0012] In some possible implementation manners, the proportion of each component in the gel raw materials is determined by using the close packing theory.

[0013] In some possible implementation manners, the volume ratio of the cement, the nano filler and the mineral admixture is (0.2-0.6):(0.05-0.2):(0.01-0.4).

[0014] In some possible implementation manners, the particle size D50 of the nano filler is 0.1-1 μm.

[0015] In some possible implementation manners, the particle size D50 of the cement is 10-25 μm.

[0016] In some possible implementation manners, the particle size D50 of the mineral admixture is 5-50 μm.

[0017] In some possible implementation manners, the apparent density of the cement is 3.0 g / cm 3 -3.2 g / cm 3 .

[0018] In some possible implementation manners, the apparent density of the nano filler is 1.8 g / cm 3 -2.2 g / cm 3 .

[0019] In some possible implementations, the apparent density of the mineral admixture is 1.5 g / cm 3 ~ 3.0 g / cm 3 .

[0020] In some possible implementations, the mass ratio of water to the gel raw material in the cement paste is (0.15~0.3):1.

[0021] In some possible implementations, the cement paste further comprises a water reducing agent.

[0022] In some possible implementations, the cement comprises at least one of Portland cement, composite Portland cement, aluminate cement, and sulfoaluminate cement.

[0023] In some possible implementations, the nano-filler comprises at least one of silica fume, glass powder, and metakaolin.

[0024] In some possible implementations, the mineral admixture comprises at least one of fly ash, granulated blast furnace slag, silica fume, limestone powder, steel slag powder, phosphorous slag powder, glass powder, zeolite powder, rice husk ash, calcined clay, and volcanic ash.

[0025] In some possible implementations, the water reducing agent comprises at least one of polycarboxylic ether water reducing agent, naphthalene series water reducing agent, and molasses series water reducing agent.

[0026] In some possible implementations, the mass percentage of the water reducing agent in the cement paste is 0.2%~0.6%.

[0027] In some possible implementations, the mass ratio of the hydrogel thickening agent, the hydrophobic agent, the foaming agent, and water is (0.5~3):(5~20):(0.2~5):100.

[0028] In some possible implementations, the porosity of the carbon dioxide foam is 80%~95%.

[0029] In some possible implementations, the average pore size of the pores in the carbon dioxide foam is 50 μm~300 μm.

[0030] In some possible implementations, the content of carbon dioxide in the carbon dioxide-containing gas is 10%~100%.

[0031] In some possible implementation manners, the hydrogel thickening agent comprises at least one of sodium hydroxypropyl cellulose, sodium methyl cellulose, sodium carboxymethyl cellulose, oxidized starch, calcium stearate, magnesium stearate, dimethicone, dodecanol, calcium stearate, zinc stearate, nano-silicon dioxide, sodium dodecyl sulfate, sodium alpha-alkenyl sulfonate, hydroxypropyl starch, methyl cellulose, sodium alginate, sodium carboxymethyl starch, and acrylic acid.

[0032] In some possible implementation manners, the hydrophobic agent comprises at least one of organosiloxane, dimethicone, carboxyl-containing silicone oil, and hydroxyl-containing silicone oil.

[0033] In some possible implementation manners, the foaming agent comprises at least one of animal and plant protein, animal plasma, sodium dodecyl benzene sulfonate, sodium dodecyl sulfate, and cetyl trimethyl ammonium bromide.

[0034] In some possible implementation manners, the blowing pressure of the carbon dioxide-containing gas in the foaming liquid is 1 bar to 100 bar.

[0035] In some possible implementation manners, in the mixed slurry, the volume ratio of the carbon dioxide foam to the cement slurry is (0.2 to 0.8):(0.8 to 0.2).

[0036] In some possible implementation manners, the stirring speed of the mixing treatment is 60 rpm to 120 rpm, and the stirring time is 2 min to 5 min.

[0037] In some possible implementation manners, the conditions of the forming treatment comprise: pouring the mixed slurry into a forming mold, and standing for 1 day to 2 days at a temperature of 20°C to 25°C.

[0038] In some possible implementation manners, the conditions of the internal carbonation curing comprise: curing for 0.5 to 2 days at a temperature of 20°C to 25°C.

[0039] In some possible implementation manners, the conditions of the external carbonation curing comprise: naturally curing for 1 hour to 7 days under the conditions of a gas pressure of 0.2 bar to 1.5 bar, a carbon dioxide concentration of 10% to 100%, a humidity of 50% to 80%, and a temperature of 20°C to 25°C.

[0040] In some possible implementation manners, the conditions of the curing comprise: naturally curing for 28 days under the conditions of a temperature of 18°C to 22°C and a humidity of greater than 95%.

[0041] In a second aspect, the present application provides a carbon dioxide foam concrete, which is prepared by the method for preparing the carbon dioxide foam concrete.

[0042] In some possible implementation manners, the carbon dioxide foam concrete has a compressive strength of not less than 5 MPa.

[0043] In some possible implementation manners, the carbon dioxide foam concrete has a water absorption of less than 10%.

[0044] In some possible implementation manners, the carbon dioxide foam concrete has a density of less than 1200 kg / m 3 .

[0045] In some possible implementation manners, the carbon dioxide foam concrete has a porosity of 10% to 90%.

[0046] In some possible implementation manners, the carbon dioxide foam concrete has an average pore size of 50 μm to 500 μm.

[0047] In a third aspect, the present application provides a use of the carbon dioxide foam concrete. The carbon dioxide foam concrete is applied to at least one of the following fields: light building materials, sound insulation and noise reduction building materials, and thermal insulation building materials.

[0048] The preparation method of the carbon dioxide foam concrete provided in the first aspect of the present application is simple, and is suitable for industrialized mass production and application. In the gel raw material, the nano filler and the mineral admixture are added, which not only fills the gaps between the larger particles, but also makes the cement matrix more dense through the hydration reaction. In the carbon dioxide foam, the hydrogel thickening agent acts as a foam stabilizer, which can enhance the mechanical properties of the foam wall and inhibit the dissolution of CO2 to stabilize the foam. The hydrophobic agent can easily chemically graft with the molecular structure of the hydrogel thickening agent, form a hydrophobic layer on the surface of the foam wall, enhance the stability of the foam, and modify the hydrophobicity of the foam concrete, so as to reduce the diffusion behavior of water molecules between the foams and achieve the effect of stabilizing the foam. Moreover, when the hydrophobic modified foam is solidified, the hydrophobic layer remains in the pores of the concrete to form a hydrophobic film layer, so that the foam concrete obtains overall hydrophobicity. Moreover, the CO2 in the carbon dioxide foam can react with the hydration products of the cement base to generate calcium carbonate to enhance the pores and realize the internal carbonation reinforcement effect. Through internal and external carbonation curing, not only a large amount of carbon can be fixed, but also the products generated by the carbonation of CO2 can fill the micropores, refine the pore size, and reduce the collapse of the pore structure, thereby realizing the reinforcement of the foam concrete and improving the compressive strength and durability of the carbon dioxide foam concrete. Moreover, the hydrophobic film layer can be generated in the pores to achieve the effect of improving the durability of the carbon dioxide foam concrete.

[0049] The carbonation enhancement of carbon dioxide and the foam hydrophobic modification function are combined in the carbon dioxide foam concrete prepared in the application, and the carbon dioxide foam concrete with high strength, hydrophobicity, stable pore size, adjustable and controllable density is successfully prepared. By using the CO2 foam and carbonation curing technology, carbon capture and utilization can be achieved to the greatest extent, and the carbon dioxide foam concrete has a significant carbon capture capacity. The porous structure has a great carbon sequestration potential, and the foam / pore in the concrete helps the diffusion and penetration of CO2 in the material, directly promoting the reaction of CO2 and cement paste. In addition, the presence of foam / pore in the concrete matrix increases the surface area in the porous structure, thereby promoting the physical and chemical adsorption of CO2. The enlarged surface area makes the interaction between carbon dioxide and the concrete matrix greater, thereby enhancing the capture and storage of carbon dioxide.

[0050] The carbon dioxide foam concrete has high compressive strength, high hydrophobicity, stable pore size, high durability, low density, light texture, excellent CO2 capture capacity and other characteristics, and thus the carbon dioxide foam concrete and its derivative products belong to multifunctional high value-added products, which can be applied in the fields of lightweight building materials, sound insulation and noise reduction building materials, thermal insulation building materials and the like, and have very high commercial application value. BRIEF DESCRIPTION OF DRAWINGS

[0051] In order to more clearly illustrate the technical solutions in the embodiments of the application, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor.

[0052] Figure 1 is a flowchart of the preparation method of the carbon dioxide foam concrete provided by the embodiments of the application;

[0053] Figure 2 is a schematic diagram of the preparation method of the carbon dioxide foam concrete provided by Embodiment 1 of the application;

[0054] Figure 3 is a particle size distribution diagram of cement, fly ash and silica fume used in the preparation of the carbon dioxide foam concrete in Embodiment 1 of the application;

[0055] Figure 4 is a scanning electron microscope diagram of the carbon dioxide foam concrete provided by Embodiment 1 of the application;

[0056] Figure 5 is a surface contact angle and water floating test diagram of the CO2 foam after freeze-drying provided by Embodiment 4 of the application;

[0057] Figure 6is a water droplet repellency test diagram of the carbon dioxide foam concrete provided by Embodiments 1-4 and Comparative Example 2 of the present application;

[0058] Figure 7 is a tomographic diagram (D1) of the carbon dioxide foam concrete provided by Embodiment 4 of the present application and a tomographic diagram (D2) of the carbon dioxide foam concrete provided by Comparative Example 3 of the present application. DETAILED DESCRIPTION

[0059] In order to make the technical problems to be solved, technical solutions and beneficial effects of the present application clearer, the present application will be further described in detail below in combination with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and do not limit the present application.

[0060] In the present application, the term "and / or" describes the association relationship of the associated objects, which means that there can be three kinds of relationships, for example, A and / or B can mean that A exists alone, A and B exist together, and B exists alone. Wherein A and B can be singular or plural. The character " / " generally represents an "or" relationship between the associated objects before and after it.

[0061] In the present application, "at least one" means one or more, and "multiple" means two or more. "At least one of the following" or the like means any combination of these items, including any combination of single item or multiple items. For example, "at least one of a, b or c", or "at least one of a, b and c", can mean a, b, c, a-b (i.e. a and b), a-c, b-c, or a-b-c, wherein a, b and c can be single or multiple.

[0062] It should be understood that in various embodiments of the present application, the size of the sequence number of the above-mentioned processes does not mean the order of execution, and part or all of the steps can be executed in parallel or in sequence, and the execution order of the processes should be determined according to its function and inherent logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0063] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a" and "the" used in the embodiments of the present application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise.

[0064] The weight of the related components mentioned in the embodiments of the present application can not only refer to the specific content of each component, but also represent the proportional relationship between the weights of each component. Therefore, as long as the content of the related components in the embodiments of the present application is enlarged or reduced in proportion, it is within the scope disclosed by the embodiments of the present application. Specifically, the mass mentioned in the embodiments of the present application can be μg, mg, g, kg and other mass units commonly known in the chemical field.

[0065] The terms "first", "second" are only used for description purposes, to distinguish objects such as substances from each other, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. For example, without departing from the scope of the embodiments of the present application, the first XX can also be referred to as the second XX, and similarly, the second XX can also be referred to as the first XX. Therefore, the features defined with "first" and "second" can explicitly or implicitly include one or more of the features.

[0066] The first aspect of the embodiments of the present application provides a preparation method of carbon dioxide foam concrete, as shown in the accompanying drawings, comprising the following steps: Figure 1

[0067] S10. Obtain a gel raw material including cement, nano filler and mineral admixture, and prepare a cement paste from the gel raw material;

[0068] S20. Prepare a foaming liquid from a hydrogel thickening agent, a hydrophobic agent, a foaming agent and water, and prepare a carbon dioxide foam by introducing a gas containing carbon dioxide;

[0069] S30. Mix the carbon dioxide foam with the cement paste to prepare a mixed paste, and perform shaping treatment to obtain a shaped concrete blank;

[0070] S40. Perform internal carbonation curing and external carbonation curing on the concrete blank, and naturally cure to obtain carbon dioxide foam concrete.

[0071] ​The preparation method of the carbon dioxide foam concrete provided in the first aspect of the embodiment of the present application is as follows: cement paste and carbon dioxide foam are prepared respectively, and then the two are mixed into a mixed paste, and after molding, internal carbonation curing and external carbonation curing are performed, and natural curing is performed to obtain the carbon dioxide foam concrete. The preparation process is simple, and is suitable for industrialized mass production and application. In the gel raw material, the addition of the nano filler and the mineral admixture not only fills the gaps between larger particles, but also makes the cement matrix more dense through the hydration reaction. In the carbon dioxide foam, the hydrogel thickening agent as a foam stabilizer can enhance the mechanical properties of the foam wall and inhibit the dissolution of CO2. Specifically, the hydrogel thickening agent is intertwined in the gel layer to form a rigid foam wall, so that the foam wall is composed of a hydrogel thickening agent layer, which can resist the disturbance and deformation of the foam by external force; in addition, the hydrogel molecular chain fixes H2O molecules through hydrogen bonds, thereby inhibiting the dissolution and penetration of CO2 gas on the foam wall by inhibiting the free movement of water molecules and reducing the active hydrogen bond sites of water molecules and CO2 molecules. The hydrophobic agent can be easily chemically grafted with the molecular structure of the hydrogel thickening agent to form a hydrophobic layer on the surface of the foam wall, thereby enhancing the stability of the foam and the hydrophobic modification of the foam concrete, thereby reducing the diffusion behavior of water molecules between the foams to achieve the effect of stabilizing the foam. Moreover, when the hydrophobically modified foam is solidified, the hydrophobic layer is retained in the pore of the concrete to form a hydrophobic membrane layer, thereby enabling the foam concrete to have overall hydrophobic properties. Moreover, the CO2 in the carbon dioxide foam can react with the cement-based hydration products to generate calcium carbonate to enhance the pore, thereby realizing the internal carbonation reinforcement effect. Through internal and external carbonation curing, not only a large amount of carbon can be fixed, but also the products generated by the carbonation of CO2 can fill the micropores, refine the pore size, and reduce the collapse of the pore structure, thereby realizing the reinforcement of the foam concrete and improving the compressive strength and durability of the carbon dioxide foam concrete. Moreover, a hydrophobic membrane layer can be generated in the pore to achieve the effect of enhancing the durability of the carbon dioxide foam concrete. The embodiment of the present application combines the carbonation reinforcement effect of carbon dioxide and the foam hydrophobic modification function, and successfully prepares the carbon dioxide foam concrete with high strength, hydrophobicity, stable pore size, high durability, adjustable and controllable density, and excellent CO2 capture capacity.

[0072] In the step S10, the gel raw material includes cement, a nano filler, and a mineral admixture. The mineral admixture can participate in the hydration reaction of the cement to play the effects of adjusting the viscosity of the paste and eliminating the thermodynamic instability of the foam. At the same time, the mineral admixture can enhance the mechanical properties of the cement matrix. Meanwhile, the nano filler has a small particle size and can fill the pores of other powders, thereby improving the density of the cement paste. The addition of the nano filler and the mineral admixture in the gel raw material not only fills the gaps between larger particles, but also makes the cement matrix more dense through the hydration reaction.

[0073] In some possible implementations, the proportion of each component in the gel raw material is determined by using the close packing theory. The target packing curve is determined by the close packing theory, and the optimal mixing ratio is obtained by adjusting the relative proportions of cement, mineral admixtures and nano fillers so that the actual packing curve approximates the target packing curve, which is conducive to designing a dense cement matrix, thereby ensuring excellent strength and durability of the carbon dioxide foam concrete.

[0074] In some possible implementations, the close packing model formula is as follows:

[0075]

[0076] wherein F(S) is the cumulative proportion of particles below the current particle size S; S is the current particle size; S min is the minimum particle size in all particles; S max is the maximum particle size; and m is the distribution modulus, which is 0.17-0.25. The target packing curve is determined by the close packing formula, and the actual packing curve is adjusted by adjusting the relative proportions of cement, mineral admixtures and nano fillers so that the actual packing curve approximates the target packing curve. The approximation degree of the actual packing curve to the target packing curve is evaluated by the determination coefficient (R 2 ). Generally, R 2 higher than 0.95 can be considered to meet the requirement of the closest packing. Based on the particle close packing theory, it is conducive to designing a dense cement matrix and ensuring excellent strength and durability of the carbon dioxide foam concrete.

[0077] In some possible implementations, the volume ratio of cement, nano filler and mineral admixture is (0.2-0.6):(0.05-0.2):(0.01-0.4). In this case, the mixing ratio of cement, nano filler and mineral admixture is conducive to obtaining a dense and high-strength cement paste, thereby ensuring the high-strength characteristics of the carbon dioxide foam concrete. Exemplarily, the volume ratio of cement, nano filler and mineral admixture can be 0.2:0.05:0.01, 0.3:0.1:0.1, 0.4:0.15:0.2, 0.5:0.18:0.3, 0.6:0.2:0.4, and the like, which are typical but non-limiting point values or interval values between any two point values.

[0078] In some possible implementations, the particle size D50 of the cement is 10-25 μm. Specifically, it can be 10 μm, 15 μm, 20 μm, 25 μm, and the like, which are typical but non-limiting point values or interval values between any two point values.

[0079] In some possible implementation manners, the particle size D50 of the nanofiller is 0.1 μm to 1 μm. Specifically, it can be 0.1 μm, 0.3 μm, 0.5 μm, 0.7 μm, 0.9 μm, 1.0 μm, or an interval value between any two point values of the above typical but non-limiting point values.

[0080] In some possible implementation manners, the particle size D50 of the mineral admixture is 5 μm to 50 μm. Specifically, it can be 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 40 μm, 50 μm, or an interval value between any two point values of the above typical but non-limiting point values.

[0081] In the above embodiments of the present application, the particle size of the nanofiller is a nanoscale ultrafine powder less than 1 μm, which can play a role in filling the pores of other powders, thereby improving the compactness of the cement paste. The particle size between the cement powder and the mineral admixture can also form a gradation to further improve the strength of the cement matrix.

[0082] In some possible implementation manners, the apparent density of the cement is 3.0 g / cm 3 ~ 3.2 g / cm 3 . Specifically, it can be 3 g / cm 3 , 3.1 g / cm 3 , 3.2 g / cm 3 , or an interval value between any two point values of the above typical but non-limiting point values.

[0083] In some possible implementation manners, the apparent density of the nanofiller is 1.8 g / cm 3 ~ 2.2 g / cm 3 . Specifically, it can be 1.8 g / cm 3 , 1.9 g / cm 3 , 2.0 g / cm 3 , 2.1 g / cm 3 , 2.2 g / cm 3 , or an interval value between any two point values of the above typical but non-limiting point values.

[0084] In some possible implementation manners, the apparent density of the mineral admixture is 1.5 g / cm 3 ~ 3.0 g / cm 3 . Specifically, it can be 1.5 g / cm 3 , 1.8 g / cm 3 , 2.0 g / cm 3 , 2.2 g / cm 3 , 2.5 g / cm 3 , 2.8 g / cm 3 , 3.0 g / cm 3interval values between any two point values.

[0085] In the above embodiments of the present application, the apparent density of each component affects the volume ratio in the process of close packing design, because the volume of different components is calculated in the process of close packing design, and then the volume ratio is converted into the mass ratio of the mixture through the apparent density of the raw material. Cement, nano-filler and mineral admixture all have high surface density, which is beneficial to improve the compressive strength of the carbon dioxide foam concrete.

[0086] In some possible implementation manners, the mass ratio of water to gel raw material in the cement paste is (0.15-0.3):1. In this case, the low water-binder ratio is adopted, which is helpful to prepare a dense cement matrix to ensure the high strength of the carbon dioxide foam concrete. For example, the mass ratio of water to gel raw material in the cement paste can be 0.15:1, 0.2:1, 0.25:1, 0.3:1, and the like typical but non-limiting arbitrary point values or interval values between any two point values.

[0087] In some possible implementation manners, the cement includes at least one of Portland cement, composite Portland cement, aluminate cement, and sulfoaluminate cement. These cements adopted in the embodiments of the present application have the characteristics of high strength, high hydration heat, good frost resistance, small dry shrinkage, good wear resistance, and the like.

[0088] In some possible implementation manners, the nano-filler includes at least one of silica fume, glass powder, and metakaolin. These nano-fillers in the embodiments of the present application all have ultra-fine particle size, which can play a role in filling the pores of other powders, thereby improving the density of the cement paste.

[0089] In some possible implementation manners, the mineral admixture includes at least one of fly ash, granulated blast furnace slag, silica fume, limestone powder, steel slag powder, phosphorous slag powder, glass powder, zeolite powder, rice husk ash, calcined clay, and volcanic ash. These mineral admixtures adopted in the embodiments of the present application can participate in the hydration reaction of cement, play the role of adjusting the viscosity of the paste and eliminating the thermodynamic instability of the foam, and at the same time, can enhance the mechanical properties of the cement matrix.

[0090] In some possible implementation manners, the cement paste further contains a water reducing agent. In this case, the water reducing agent in the cement paste can improve the workability of the carbon dioxide foam concrete, so that the carbon dioxide foam concrete material still has excellent workability under the condition of low water-binder ratio.

[0091] In some possible implementation manners, the water reducing agent includes at least one of polycarboxylate ether type water reducing agent, naphthalene type water reducing agent, and molasses type water reducing agent. These water reducing agents can all improve the workability of the carbon dioxide foam concrete.

[0092] In some possible implementation manners, the mass percentage content of the water reducing agent in the cement paste is 0.2% to 0.6%. In this case, the content of the water reducing agent can effectively improve the workability of the carbon dioxide foam concrete, while ensuring the compressive strength, durability and other characteristics of the carbon dioxide foam concrete. For example, the mass percentage content of the water reducing agent in the cement paste can be 0.2%, 0.3%, 0.4%, 0.5%, 0.6% and the like, or an interval value between any two point values.

[0093] In the step S20, the hydrogel thickening agent, the hydrophobic agent, the foaming agent and water are prepared into a foaming liquid. The hydrogel thickening agent, also referred to as a “foam stabilizer”, means a chemical agent that can enhance the stability of the foam and control the size of the foam, including various types of viscosity-enhancing modifiers. The foaming agent refers to a surfactant with an amphiphilic chemical structure, which can reduce the interfacial tension of the foaming liquid, including various types of organic, inorganic, cationic, anionic, non-ionic, high molecular and small molecular surfactants and their compounded surfactants, or other surfactants such as various types of animal and plant proteins, blood plasma and the like. The hydrophobic agent can be easily chemically grafted with the molecular structure of the hydrogel thickening agent to form a hydrophobic layer on the surface of the foam wall, thereby enhancing the stability of the foam and the hydrophobic modification of the foam concrete, reducing the diffusion behavior of water molecules between the foams, and achieving the foam stabilization effect.

[0094] In some possible implementation manners, the mass ratio of the hydrogel thickening agent, the hydrophobic agent, the foaming agent and water is (0.5 to 3):(5 to 20):(0.2 to 5):100. In this ratio, the stability of the carbon dioxide foam is maintained, the foam stabilization effect is good, the CO2 foam with the hydrophobic function is used, the internal carbonation of the pore wall of the concrete is enhanced, and the overall waterproof performance of the concrete is improved. Moreover, the cement hydration, the strength and durability of the foam concrete and other performances are not affected. For example, the mass ratio of the hydrogel thickening agent, the hydrophobic agent, the foaming agent and water can be 0.5:5:0.2:100, 1:10:1:100, 2:15:3:100, 3:20:5:100 and the like, or an interval value between any two point values.

[0095] In some possible implementations, the hydrogel thickening agent includes at least one of sodium hydroxypropyl cellulose, sodium methyl cellulose, sodium carboxymethyl cellulose, oxidized starch, calcium stearate, magnesium stearate, polymethyl hydrogen silicone oil, dodecanol, calcium stearate, zinc stearate, nano-silicon dioxide, sodium dodecyl sulfate, sodium alpha-alkenyl sulfonate, hydroxypropyl starch, methyl cellulose, sodium alginate, sodium carboxymethyl starch, and acrylic acid. In this case, these hydrogel thickening agents all have a foam stabilizing effect, and the hydrogel thickening agents are intertwined in the gel layer, so that a rigid foam wall is formed, the foam wall is composed of a hydrogel thickening agent layer, and the foam wall can resist deformation caused by external force disturbance; in addition, the hydrogel molecular chain fixes H2O molecules through hydrogen bonds, and inhibits the dissolution and penetration of CO2 gas on the foam wall by inhibiting the free movement of water molecules and reducing the active hydrogen bond sites of water molecules and CO2 molecules.

[0096] In some possible implementations, the hydrophobic agent includes at least one of organosiloxane, polydimethylsiloxane, carboxyl-containing silicone oil, and hydroxyl-containing silicone oil. In this case, these hydrophobic agents can be easily chemically grafted with the molecular structure of the hydrogel thickening agent, form a hydrophobic layer on the surface of the foam wall, enhance the stability of the foam, and hydrophobically modify the foam concrete, so as to reduce the diffusion behavior of water molecules between the foams and achieve the foam stabilizing effect. Moreover, when the hydrophobically modified foam is solidified, the hydrophobic layer remains in the pores of the concrete to form a hydrophobic film layer, so that the foam concrete has overall hydrophobic performance.

[0097] In some possible implementations, the foaming agent includes at least one of animal and plant proteins, animal plasma, sodium dodecyl benzene sulfonate, sodium dodecyl sulfate, and cetyltrimethylammonium bromide. In this case, these foaming agents can be used to stably prepare carbon dioxide foam, and better ensure that the morphology of the carbon dioxide foam is not destroyed during the mixing process of the carbon dioxide foam and the cement slurry.

[0098] In some possible implementations, the blowing pressure of the carbon dioxide-containing gas in the foaming liquid is 1-100 bar, and can be 1 bar, 10 bar, 20 bar, 50 bar, 80 bar, 100 bar, or any interval value between any two point values. In this case, the gas blowing pressure makes the foaming liquid have better foaming effect, and improves the stability and uniformity of the carbon dioxide foam.

[0099] In some possible implementations, the carbon dioxide content in the carbon dioxide-containing gas is 10% to 100%. In this case, the carbon dioxide content in the gas is conducive to the preparation of the carbon dioxide foam, and is conducive to the construction of micron-rough calcium carbonate particles on the pore wall interface by means of the principle of carbonation of CSH (calcium silicate hydrate) / CASH (calcium alumino-silicate hydrate) hydration products on the pore wall by means of CO2 in the subsequent mixing with the cement paste to prepare the carbon dioxide foam concrete, and the combination of the dense hydrophobic layer on the pore wall can significantly strengthen the water-repellent ability of the pore structure, and greatly enhance the overall durability of the concrete. Therefore, the CO2-prepared foam concrete has obvious internal carbonation benefits, that is, the basic performance of the foam concrete can be significantly improved, and other additional functional properties such as hydrophobicity and durability are also given. Exemplarily, the carbon dioxide content in the carbon dioxide-containing gas can be 10%, 12%, 15%, 20%, 25%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100%, or an interval value between any two point values.

[0100] In some possible implementations, the porosity of the carbon dioxide foam is 80% to 95%. In this case, the high porosity of the carbon dioxide foam is conducive to the enrichment of the pore structure in the foam concrete and the increase of the carbonation activity specific surface area of the concrete. Exemplarily, the porosity of the carbon dioxide foam can be 80%, 83%, 85%, 88%, 90%, 92%, 95%, or an interval value between any two point values.

[0101] In some possible implementations, the average pore size of the pores in the carbon dioxide foam is 50 μm to 300 μm. In this case, the pores in the carbon dioxide foam are rich and have a large pore size. This is conducive to the improvement of the pore structure in the carbon dioxide foam concrete, and the foam / pores in the concrete help the diffusion and penetration of CO2 in the material, directly promoting the reaction of CO2 with the cement paste. In addition, the increase of the foam / pores in the concrete matrix increases the surface area in the porous structure, promoting the physical and chemical adsorption of CO2. The enlarged surface area makes the interaction between the carbon dioxide and the concrete matrix greater, thereby enhancing the capture and storage of carbon dioxide. Exemplarily, the average pore size of the pores in the carbon dioxide foam can be 50 μm, 100 μm, 150 μm, 200 μm, 250 μm, 300 μm, or an interval value between any two point values.

[0102] In the above step S30:

[0103] In some possible implementation manners, the volume ratio of the carbon dioxide foam to the cement slurry in the mixed slurry is (0.2-0.8):(0.8-0.2). Specifically, taking the total volume of the carbon dioxide foam and the cement slurry in the mixed slurry as 1, the volume ratio of the carbon dioxide foam to the cement slurry can be 0.2:0.8, 0.3:0.7, 0.4:0.6, 0.5:0.5, 0.6:0.4, 0.7:0.3, 0.8:0.2, or any ratio between any two of the above ratios. In this case, the pore structure of the foam concrete can be improved, and the compressive strength and durability of the foam concrete can be ensured.

[0104] In some possible implementation manners, the stirring speed of the mixing treatment is 60 rpm-120 rpm, and the stirring time is 2 min-5 min. In this case, the carbon dioxide foam and the cement slurry are quickly and uniformly mixed at a low and appropriate stirring speed, so that the form of the carbon dioxide foam is not damaged during the mixing process, and the carbon dioxide foam is less broken during the stirring into the cement slurry. For example, the stirring speed of the mixing treatment can be 60 rpm, 80 rpm, 100 rpm, 120 rpm, or any ratio between any two of the above ratios, and the stirring time can be 2 min, 3 min, 4 min, 5 min, or any ratio between any two of the above ratios.

[0105] In some possible implementation manners, the forming treatment includes pouring the mixed slurry into a forming mold and placing the mixed slurry at a temperature of 20-25°C for 1-2 days. In this case, the mixed slurry of the carbon dioxide foam and the cement slurry is solidified and formed.

[0106] In the step S40, the following steps are performed:

[0107] In some possible implementation manners, the internal carbonation curing includes curing at a temperature of 20-25°C for 0.5-2 days. In this case, by means of the principle that the CO2 in the bubbles carbonates the CSH (calcium silicate hydrate) / CASH (calcium silicate aluminate hydrate) hydration products on the pore wall, the micron rough calcium carbonate particles are constructed on the pore wall interface, and the dense hydrophobic layer on the pore wall can significantly strengthen the water-repellent ability of the pore structure and greatly enhance the overall durability of the concrete. For example, the curing temperature can be 20°C, 21°C, 22°C, 23°C, 24°C, 25°C, or any ratio between any two of the above ratios, and the natural curing time can be 0.5 days, 1 day, 1.5 days, 2 days, or any ratio between any two of the above ratios.

[0108] In some possible implementations, the conditions of the external carbonation curing include: natural curing for 1 hour to 7 days under the conditions of a gas pressure of 0.2-1.5 bar, a carbon dioxide concentration of 10%-100%, a humidity of 50%-80%, and a temperature of 20-25 ℃. In this case, the external carbonation curing is used to further enhance the mechanical properties of the carbon dioxide foam concrete. First, the carbonation reaction product has a filling effect, which fills the micro voids and cracks of the foam concrete, can reduce the porosity and refine the pore size structure. At the same time, the calcium carbonate product will also grow on the cell wall, enhancing the strength of the bubble wall structure. Finally, the water generated by the carbonation reaction can promote the hydration of the unhydrated cement particles, generating more CSH gel, which is beneficial to the strength growth of the concrete. Among them, the gas pressure range ensures sufficient carbonation, and higher gas pressure helps CO2 to better penetrate the inside of the foam concrete, promoting the carbonation reaction and thus improving the early strength of the foam concrete. A sufficient CO2 concentration ensures the carbonation efficiency, and a higher CO2 concentration can accelerate the carbonation reaction in the concrete and promote the early strength development of the concrete. The appropriate humidity helps to maintain the appropriate moisture of the concrete, promote the carbonation reaction, and at the same time ensure the diffusion of carbon dioxide. The temperature ensures the carbonation reaction rate, and an appropriate increase in temperature helps to accelerate the carbonation reaction and improve the early strength development of the concrete.

[0109] For example, the gas pressure of the external carbonation curing can be 0.2 bar, 0.5 bar, 0.8 bar, 1.0 bar, 1.2 bar, 1.5 bar, etc. Typical but non-limiting arbitrary ratio or interval value between any two ratios, the carbon dioxide concentration can be 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100%, the humidity is 50%, 60%, 70%, 80%, etc. Typical but non-limiting arbitrary ratio or interval value between any two ratios, the temperature is 20℃, 21℃, 22℃, 23℃, 24℃, 25℃, etc. Typical but non-limiting arbitrary ratio or interval value between any two ratios, natural curing for 1 hour, 6 hours, 12 hours, 1 day, 2 days, 3 days, 4 days, 5 days, 6 days, 7 days, etc. Typical but non-limiting arbitrary ratio or interval value between any two ratios.

[0110] In some possible implementations, the conditions of the natural curing include: natural curing for 28 days under the conditions of a temperature of 18-22 ℃ and a humidity of greater than 95%. In this case, the natural curing can further improve the strength, durability, stability and other properties of the carbon dioxide foam concrete.

[0111] The preparation method of the carbon dioxide foam concrete in the above embodiments of the present application has at least the following beneficial effects: (1) The carbon dioxide foam concrete prepared according to the method of the embodiments of the present application not only has the characteristics of high strength, light weight and hydrophobicity, but also ingeniously utilizes the carbonation reaction of the concrete itself to enhance the structure. The preparation strategy has ultra-high carbon capture / carbon sequestration capacity. Therefore, the carbon dioxide foam concrete prepared by the present technology is more conducive to achieving the goal of “carbon neutralization”. (2) The embodiments of the present application ingeniously utilize the high-molecular hydrogel thickening agent to prepare high-modulus foam, and utilize the hydrophobic modifier to modify the foam. This method can easily prepare carbon dioxide foam concrete with three-dimensional hydrophobic structure, greatly reducing the water absorption of the material and enhancing the durability. (3) The embodiments of the present application can realize the synchronous preparation of internal and external carbonation enhancement and overall hydrophobic modification of the foam concrete, without the need for additional chemical reagents and expensive production equipment. The present application has the advantages of simple manufacturing process, short production cycle and high yield, and has the feasibility of large-scale industrial production. (4) The embodiments of the present application break through the problems of low strength, poor durability, difficult hydrophobic modification, and unsatisfactory waterproof / anti-permeation modification effect of the current foam concrete, greatly solving the functional weakening problem caused thereby, and having important significance for expanding the application field of foam concrete.

[0112] In a second aspect, the embodiments of the present application provide a carbon dioxide foam concrete prepared by the above-mentioned preparation method of carbon dioxide foam concrete.

[0113] The carbon dioxide foam concrete prepared by the above embodiments of the present application combines the carbonation enhancement of carbon dioxide and the foam hydrophobic modification function, and successfully prepares carbon dioxide foam concrete with high strength, hydrophobicity, stable pore size, and adjustable and controllable density. By using CO2 foam and carbonation curing technology, carbon capture and utilization can be achieved to the greatest extent, and the carbon capture capacity is significantly improved. The porous structure has great carbon sequestration potential. The foam / pores in the concrete help the diffusion and penetration of CO2 in the material, directly promoting the reaction of CO2 and cement paste. In addition, the presence of foam / pores in the concrete matrix increases the surface area in the porous structure, thereby promoting the physical and chemical adsorption of CO2. This enlarged surface area makes the interaction between carbon dioxide and the concrete matrix greater, thereby enhancing the capture and sequestration of carbon dioxide.

[0114] In some possible implementation manners, the compressive strength of the carbon dioxide foam concrete is not less than 5 MPa. Specifically, the compressive strength can be 5 MPa, 10 MPa, 15 MPa, 20 MPa, 25 MPa, 30 MPa, 35 MPa, 40 MPa, 45 MPa, 50 MPa, 60 MPa, 70 MPa, 80 MPa, 90 MPa, 100 MPa, or any interval value between any two of the foregoing values. The carbon dioxide foam concrete has high compressive strength and good structural stability.

[0115] In some possible implementation manners, the water absorption of the carbon dioxide foam concrete is less than 10%. Specifically, the water absorption can be 10%, 9%, 8%, 7%, 7.5%, 6%, 5%, 4%, 3%, 2%, or any interval value between any two of the foregoing values. The carbon dioxide foam concrete has low water absorption, good hydrophobicity, and high durability.

[0116] In some possible implementation manners, the density of the carbon dioxide foam concrete is less than 1200 kg / m 3 . Specifically, the density can be 1150 kg / m 3 , 1100 kg / m 3 , 1000 kg / m 3 , 900 kg / m 3 , 800 kg / m 3 , 700 kg / m 3 , 600 kg / m 3 , 500 kg / m 3 , 400 kg / m 3 , or any interval value between any two of the foregoing values. The carbon dioxide foam concrete has low density and light texture.

[0117] In some possible implementation manners, the porosity of the carbon dioxide foam concrete is 10% to 90%. For example, the porosity of the carbon dioxide foam concrete can be 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, or any interval value between any two of the foregoing values. The carbon dioxide foam concrete has rich pores, which is conducive to reducing the density of the carbon dioxide foam concrete and improving the carbon dioxide capturing capacity.

[0118] In some possible implementations, the average pore size of the pores in the carbon dioxide foam concrete is 50 μm to 500 μm. Exemplarily, the average pore size of the pores in the carbon dioxide foam concrete can be 50 μm, 100 μm, 200 μm, 300 μm, 400 μm, 500 μm, or any ratio or interval between any two ratios. The carbon dioxide foam concrete has abundant pores and stable pore size.

[0119] The carbon dioxide foam concrete provided in the embodiments of the present application has high compressive strength, high hydrophobicity, stable pore size, high durability, low density, light texture, and excellent CO2 capture capacity, and thus has low thermal conductivity, good sound insulation and fireproof performance, and excellent CO2 capture capacity.

[0120] In a third aspect, the embodiments of the present application provide an application of the carbon dioxide foam concrete. The carbon dioxide foam concrete is applied to at least one of the fields of light building materials, sound insulation and noise reduction building materials, and thermal insulation building materials.

[0121] The carbon dioxide foam concrete provided in the embodiments of the present application has high compressive strength, high hydrophobicity, stable pore size, high durability, low density, light texture, and excellent CO2 capture capacity, and thus the carbon dioxide foam concrete and the derived products thereof belong to multifunctional high value-added products, can be applied to the fields of light building materials, sound insulation and noise reduction building materials, and thermal insulation building materials, and have very high commercial application value.

[0122] To enable the above-described implementation details and operations of the present application to be clearly understood by those skilled in the art, and the performance of the carbon dioxide foam concrete and the preparation method thereof provided in the embodiments of the present application is significantly embodied, the above technical solutions are illustrated by multiple embodiments as follows.

[0123] Embodiment 1

[0124] A carbon dioxide foam concrete, as shown in FIG. 1, is prepared by the following steps: Figure 2

[0125] 1. Cement paste raw materials: the main cementitious materials include ordinary Portland cement (OPC, CEM I N525), silica fume (SF) and fly ash (FA). The chemical composition of these powders is detected by x-ray fluorescence spectroscopy (Rigaku Supermini200). The particle size distribution of the cementitious materials is shown in FIG. 2. Figure 3 ​The working performance of the cement paste was adjusted by using a high-efficiency polycarboxylic ether superplasticizer (SP) with a solid content of 0.22 purchased from BASF (SKY 8588), and the proportion of the superplasticizer solid in the cement paste was 0.4%. The cementitious material composition was designed based on the close packing theory, and the mass ratio of cement, fly ash, and silica fume was 739:185:176, and the water-binder ratio was 0.22.

[0126] 2. Preparation of carbon dioxide foam: The foaming liquid was prepared according to the mass ratio of water: high molecular thickening agent: polydimethylsiloxane: sodium dodecyl sulfate = 100: 1.5: 10: 0.5. Pure CO2 gas was used to blow the foaming liquid at a pressure of 0.5 MPa, and a hydrophobic CO2 foam was prepared by using a foaming machine.

[0127] 3. Process for preparing high-strength hydrophobic carbon dioxide foam concrete: 1) preliminary mixing of cementitious materials for 1 min; 2) adding water and superplasticizer and stirring for 4-5 min to form a slurry; 3) adding the prepared CO2 foam and stirring at a speed of 120 rpm for 2 min, and the volume ratio of CO2 foam to cement paste was 3:7; 4) pouring the fresh foam concrete slurry into a mold and placing it in an environment at 20℃±2℃ for 24 h to form a shape. Then carbonation curing was performed to improve the performance of the foam concrete and maximize the capture of CO2. After 24 h of pouring, the test block was demolded and placed in a condition of 23±1℃ for internal carbonation curing for 1 day, followed by external carbonation curing / carbonation curing (conditions: P=0.8 bar, RH=65±5%, T=23±1℃). After 120 h of carbonation curing, the sample was moved to a standard curing room for curing for 28 days.

[0128] Examples 2-4 and Comparative Examples 1-3

[0129] Examples 2-4 and Comparative Examples 1-3 each provide a carbon dioxide foam concrete, and the main difference from Example 1 is that the proportions of water, high molecular thickening agent, polydimethylsiloxane, and sodium dodecyl sulfate in step 2 are different, and the gas composition and pressure for preparing the carbon dioxide foam are different. The specific details are shown in Table 1 below:

[0130] Table 1

[0131]

[0132] Examples 5-8 and Comparative Example 4

[0133] Examples 5-8 and Comparative Example 4 each provide a carbon dioxide foam concrete, and the main difference from Example 1 is that the proportions of cement, fly ash, and silica fume in step 1 are different, the water-binder ratio (i.e., the mass ratio of water to cementitious materials) is different, and the volume ratio of carbon dioxide foam to cement paste is different. The specific details are shown in Table 2 below:

[0134] Table 2

[0135]

[0136]

[0137] In order to verify the progressiveness of the embodiments of the present application, the following performance tests were conducted:

[0138] 1. The micro-morphology of the carbonated carbon dioxide foam concrete of Example 1 was observed, as shown in the scanning electron microscope images of the drawings, it can be seen that the distribution of the substances and pores in the carbon dioxide foam concrete is uniform. Figure 4

[0139] In addition, the compressive strength, density, thermal conductivity, specific strength, water absorption rate and contact angle of the carbon dioxide foam concrete before carbonation (i.e., the product directly naturally cured for 28 days after mixing of carbon dioxide foam and cement paste) and the carbon dioxide foam concrete after carbonation (i.e., the product cured by internal carbonation oxidation and external carbonation curing and naturally cured for 28 days) in Example 1 were tested, respectively, and the test results are shown in Table 3 below:

[0140] Table 3

[0141]

[0142] From the above test results, it can be seen that after carbonation, due to the absorption of a large amount of CO2 gas, the density of the concrete increases slightly from 1120 kg / m 3 to 1215 kg / m 3 , but the compressive strength of the sample increases from 16.23 MPa to 20.54 MPa. In addition, after carbonation, the carbon dioxide foam concrete presents hydrophobic effect, the contact angle of the sample before solidification is 121°, and after carbonation enhancement, the contact angle is increased to 152°, and the super-hydrophobic state is changed. The carbon dioxide foam concrete after carbonation has a low water absorption rate of only 7.5%.

[0143] The compressive strength, density, thermal conductivity, specific strength, water absorption rate and other properties of the carbon dioxide foam concrete prepared in the above examples and comparative examples were tested, and the test results are shown in Table 4 below:

[0144] Table 4

[0145]

[0146] From the above test results, it can be seen that the carbon dioxide foam concrete prepared in the embodiments of the present application has higher compressive strength, high durability, low density, light texture, low thermal conductivity and other characteristics.

[0147] ​2. The average diameter, contact angle, and average pore size of the carbon dioxide foam prepared in Examples 1-4 and Comparative Examples 1-3 were tested respectively. The test results are shown in Table 5 below:

[0148] Table 5

[0149] Foam average diameter / pm Contact angle of concrete / ° Average pore diameter of concrete / pm Example 1 102 152 124 Example 2 186 149 192 Example 3 189 152 196 Example 4 192 151 203 Comparative Example 1 176 153 180 Comparative Example 2 194 32 201 Comparative Example 3 321 132 451

[0150] The test results above show that, compared with the test results of Examples 1-4 and Comparative Examples 1-3, the foam prepared with different concentrations of CO2 in the gas has excellent thermodynamic stability and the average diameter of the foam pores is stable, ranging from 180 to 200 μm.

[0151] As attached Figure 5 As shown, in Example 4, after hydrophobic modification with polydimethylsiloxane, the foam structure exhibits excellent stability with a surface contact angle of 151°. The structure remained intact after floating on water for two months, without any damage or collapse.

[0152] The comparison revealed that in Comparative Example 2, without the addition of polydimethylsiloxane, the foamed concrete produced had a contact angle of 32°, exhibiting hydrophilicity. In Examples 1-4, the polydimethylsiloxane-modified carbon dioxide foamed concrete had a contact angle of approximately 150°, transforming into a superhydrophobic state while retaining overall hydrophobic properties, as shown in the attached figure. Figure 6 As shown.

[0153] The test results of Comparative Example 4 and Comparative Example 3 are shown in the attached figure. Figure 7 As shown in Figure D1, the foam size of Comparative Example 3 without the addition of a polymeric thickener was larger, with an average foam diameter of 321 μm. Furthermore, the stability of the foam after being mixed into the cement paste was poor, and the average pore size in the concrete increased to 451 μm. The porosity of the carbon dioxide foam concrete was 24.53%. (See attached figure.) Figure 7 As shown in Figure (D2), the CO2 bubbles modified with the addition of a polymer thickener in Example 4 showed good stability, with an average foam diameter of 192 μm. The foam also exhibited excellent stability in the cement paste. The average pore size of the pores in the cured carbon dioxide foam concrete was comparable to the initial diameter of the carbon dioxide foam, with an average diameter of 203 μm. The porosity of the carbon dioxide foam concrete was 27.52%.

[0154] Comparing the test results of the above embodiments and comparative examples, it can be seen that the preparation method of carbon dioxide foamed concrete in this application can prepare ultra-stable hydrophobic CO2 foam. Furthermore, according to different application requirements, concrete with different mix proportions can be modified to produce lightweight, high-strength, hydrophobic carbon dioxide foamed concrete or other derivative products.

[0155] The above only describes preferred embodiments of the present application and is not used to limit the present application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A method of producing carbon dioxide foam concrete, characterized by, The method comprises the following steps: obtaining a gel raw material comprising cement, nano-filler and mineral admixture, and preparing a cement paste from the gel raw material; preparing a foaming liquid from a hydrogel thickening agent, a hydrophobic agent, a foaming agent and water, and preparing a carbon dioxide foam by introducing a carbon dioxide-containing gas; mixing the carbon dioxide foam and the cement paste to prepare a mixed paste, and performing a molding process to obtain a molded concrete blank; performing internal and external carbonation curing on the concrete blank, and naturally curing to obtain carbon dioxide foam concrete.

2. The method of claim 1, wherein the carbon dioxide foam concrete is prepared by mixing the carbon dioxide foam concrete mixture with the carbon dioxide gas at a temperature of 20 to 30°C and a pressure of 0.1 to 0.3 MPa. The proportions of the components in the gel raw material are determined according to the close packing theory; and / or, the volume ratio of the cement, the nano-filler and the mineral admixture is (0.2-0.6):(0.05-0.2):(0.01-0.4); and / or, in the cement paste, the mass ratio of water to the gel raw material is (0.15-0.3):1; and / or, the cement paste further comprises a water reducing agent.

3. The method of claim 2, wherein the carbon dioxide foam concrete is prepared by mixing the carbon dioxide foam concrete mixture with the water at a temperature of 20 to 30°C. The nano-filler has a particle size D50 of 0.1-1 μm; and / or, the cement has a particle size D50 of 10-25 μm; and / or, the mineral admixture has a particle size D50 of 5-50 μm; and / or the apparent density of the cement is 3.0 g / cm 3 ~ 3.2 g / cm 3 ; and / or the apparent density of the nanofiller is 1.8 g / cm 3 ~ 2.2 g / cm 3 ; and / or the apparent density of the mineral admixture is 1.5 g / cm 3 ~ 3.0 g / cm 3 ; and / or, the mass percentage of the water reducing agent in the cement paste is 0.2%-0.6%.

4. The method of claim 3, wherein the carbon dioxide foam concrete is prepared by mixing the carbon dioxide foam concrete mixture with the water at a temperature of 20 to 30°C. The cement comprises at least one of Portland cement, composite Portland cement, aluminate cement and sulfoaluminate cement; and / or, the nano-filler comprises at least one of silica fume, glass powder and metakaolin; and / or, the mineral admixture comprises at least one of fly ash, granulated blast furnace slag, silica fume, limestone powder, steel slag powder, phosphorous slag powder, glass powder, zeolite powder, rice husk ash, calcined clay and volcanic ash; and / or, the water reducing agent comprises at least one of polycarboxylic ether water reducing agent, naphthalene series water reducing agent and molasses series water reducing agent.

5. The method of claim 1 to 4, wherein the carbon dioxide foam concrete is prepared by mixing the carbon dioxide foam concrete raw material powder and the water, and then performing a foaming process. The mass ratio of the hydrogel thickening agent, the hydrophobic agent, the foaming agent and water is (0.5-3):(5-20):(0.2-5):100; and / or, the porosity of the carbon dioxide foam is 80%-95%; and / or, in the carbon dioxide foam, the average pore size is 50-300 μm; and / or, in the carbon dioxide-containing gas, the content of carbon dioxide is 10%-100%.

6. The method of claim 5, wherein the carbon dioxide foam concrete is prepared by mixing the carbon dioxide foam concrete mixture with the water at a temperature of 20 to 30°C. The hydrogel thickening agent comprises at least one of sodium hydroxypropyl cellulose, sodium methyl cellulose, sodium carboxymethyl cellulose, oxidized starch, calcium oxalate, magnesium oxalate, polymethyl hydrogen silicone oil, dodecanol, calcium stearate, zinc stearate, nano-silicon dioxide, sodium dodecyl sulfate, sodium alpha-alkenyl sulfonate, hydroxypropyl starch, methyl cellulose, sodium alginate, sodium carboxymethyl starch and acrylic acid; and / or, the hydrophobic agent comprises at least one of organosiloxane, polydimethyl silicone oil, carboxyl-containing silicone oil and hydroxyl-containing silicone oil; and / or, the foaming agent comprises at least one of animal and plant protein, animal plasma, sodium dodecyl benzene sulfonate, sodium dodecyl sulfate and cetyl trimethyl ammonium bromide. And / or, the blowing pressure of the carbon dioxide-containing gas in the foaming liquid is 1-100 bar.

7. A process for the production of carbon dioxide foam concrete as claimed in any one of claims 1 to 4 or 6, wherein, The volume ratio of the carbon dioxide foam to the cement slurry in the mixed slurry is (0.2-0.8):(0.8-0.2); And / or, the stirring speed of the mixing treatment is 60 rpm-120 rpm, and the stirring time is 2 min-5 min; And / or, the conditions of the forming treatment include pouring the mixed slurry into a forming mold and standing for 1-2 days at a temperature of 20-25℃.

8. A method of producing carbon dioxide foam concrete as claimed in any one of claims 1 to 4 or 6, characterised in that, The conditions of the internal carbonation curing include curing for 0.5-2 days at a temperature of 20-25℃. And / or, the conditions of the external carbonation curing include natural curing for 1 hour-7 days at a gas pressure of 0.2-1.5 bar, a carbon dioxide concentration of 10%-100%, a humidity of 50%-80%, and a temperature of 20-25℃. And / or, the conditions of the curing include natural curing for 28 days at a temperature of 18-22℃ and a humidity of more than 95%.

9. A carbon dioxide foam concrete, characterized by, The carbon dioxide foam concrete is prepared by the method of any one of claims 1-8.

10. The carbon dioxide foam concrete as claimed in claim 9, wherein, The compressive strength of the carbon dioxide foam concrete is not less than 5 MPa; And / or, the water absorption rate of the carbon dioxide foam concrete is less than 10%; and / or the density of the carbon dioxide foam concrete is less than 1200 kg / m 3 ; And / or, the porosity of the carbon dioxide foam concrete is 10%-90%; And / or, the average pore size of the carbon dioxide foam concrete is 50-500 μm.

11. Use of carbon dioxide foam concrete, characterized in that, The carbon dioxide foam concrete of any one of claims 9-10 is applied to at least one of light building materials, sound insulation and noise reduction building materials, and thermal insulation building materials.

Images