A negative carbon type composite material and a method for preparing the same

Abstract

The application discloses a kind of negative carbon type composite materials, composition is as follows according to weight fraction: 50~130 parts of calcite type calcium carbonate, 0.2~2.5 parts of magnesium salt, 1.0~4.5 parts of strontium salt, 10~70 parts of water, 0.03~4 parts of organic filling material;The organic filling material is triethanolamine;Magnesium salt and strontium salt are dissolved in water, organic filling material is stirred and dispersed to obtain homogeneous mixed solution;Calcite type calcium carbonate is stirred and mixed with the above homogeneous mixed solution until slurry state appears;The above slurry is poured into mold and cured to form;The organic filling material used in the application can not only be compatible with other components in cementitious materials, but also form a stable network structure during drying, effectively reducing porosity and improving the overall density and mechanical strength of the material. This improvement makes the material perform well in heavy load-bearing or high durability engineering applications.

Description

Technical Field

[0001] This invention belongs to the field of building materials technology, specifically relating to a negative carbon composite material and its preparation method. Background Technology

[0002] Traditional materials such as cement and steel, as well as modern materials such as organic and composite materials, pose significant challenges to environmental sustainability due to their carbon footprints generated during production and use. To address this challenge, the industry is exploring low-carbon solutions, including the adoption of renewable energy, optimization of production processes, and the use of novel catalysts and additives to reduce the carbon footprint of production. Despite challenges related to cost, performance, and large-scale production, developing environmentally friendly new materials is crucial for the materials industry's low-carbon transformation. This is not only a responsible approach to the environment but also an essential path towards a more sustainable future for the industry. With the global pursuit of a low-carbon economy, this transformation in the materials industry has become an irreversible trend, providing vast development opportunities for the future development of environmentally friendly new materials.

[0003] Recently, a novel carbon-negative cementitious material has emerged. This material utilizes soluble calcium resources from industrial byproducts to achieve negative carbon emissions through chemical CO2 fixation, thus combating global climate change. This material not only reduces dependence on natural resources but also has the potential for application in multiple fields due to its environmental friendliness and cost-effectiveness. However, despite its significant advantages in environmental protection, this novel cementitious material has certain limitations in terms of mechanical properties.

[0004] Specifically, during the transformation of aragonite into aragonite, the resulting needle-like aragonite crystals overlap, which, while providing some strength, results in imperfect crystal bonding and numerous pores. These pores significantly reduce the material's density, thus affecting its mechanical properties. This deficiency in mechanical properties limits the wider application of this novel cementitious material, particularly in engineering projects involving heavy loads or requiring high durability.

[0005] To address this problem, the inventors tried various methods, including optimizing the growth conditions of aragonite crystals and adding different types of admixtures. However, these methods often only brought limited improvements and might increase production costs or introduce new environmental problems. Therefore, how to effectively improve the mechanical properties of novel cementitious materials while maintaining their environmentally friendly characteristics has become an urgent technical challenge. Summary of the Invention

[0006] The purpose of this invention is to provide a carbon-negative composite material and its preparation method. By adding specific organic fillers during the molding and stirring process to fill the internal pores, the mechanical properties of the carbon-negative cementitious material are significantly improved.

[0007] A carbon-negative composite material, the composition of which is as follows by weight:

[0008] The composition includes 50-130 parts of aragonite-type calcium carbonate, 0.2-2.5 parts of magnesium salt, 1.0-4.5 parts of strontium salt, 10-70 parts of water, and 0.03-4 parts of organic filler; the organic filler is triethanolamine.

[0009] According to the above scheme, the magnesium salt is one or a mixture of MgCl2 and Mg(NO3)2.

[0010] According to the above scheme, the strontium salt is one or a mixture of SrCl2 and Sr(NO3)2.

[0011] According to the above scheme, the aragonite-type calcium carbonate is prepared in the following manner:

[0012] The CO2-containing tail gas was passed into the calcium-rich solution after water washing and salt extraction using the bubbling method to obtain a suspension containing calcium carbonate precipitate.

[0013] The suspension was filtered and dried to obtain spheroidal calcium carbonate.

[0014] According to the above scheme, the calcium-rich solution is the filtrate obtained after washing and salt extraction of the ash from the kiln bypass vent, wherein Ca... 2+ Concentration ≥ 0.05 mol / L.

[0015] According to the above scheme, the CO2-containing exhaust gas is industrial flue gas, wherein the CO2 concentration is 10vt% to 37vt%.

[0016] The preparation method of the above-mentioned carbon-negative composite material includes the following steps:

[0017] (1) Dissolve magnesium salt and strontium salt in water, add organic filler material and stir to disperse to obtain a homogeneous mixed solution;

[0018] (2) Stir the ball-shaped calcium carbonate with the above homogeneous mixed solution until a slurry is formed;

[0019] (3) Pour the above slurry into the mold and cure it.

[0020] According to the above scheme, the curing conditions include: steam curing at 50-90℃ for 1-8 hours, followed by demolding; and drying at 90-130℃ for 8-20 hours to obtain the negative carbon composite material.

[0021] This invention achieves strength by adding magnesium salts to the system to directionally regulate the transformation of aragonite into aragonite. The resulting needle-like aragonite crystals interlock, thus enhancing the system's strength. Furthermore, due to the highly consistent crystal structures of strontium carbonate and aragonite-type calcium carbonate, strontium atoms can occupy some calcium atom sites in the aragonite during the crystal transformation, forming a solid solution and further increasing the system's strength. Because the nitrogen atom in the triethanolamine group possesses a lone pair of electrons, it readily forms complexes with metal ions, a property widely used in biomedicine and industrial fields. In this invention, triethanolamine first participates in the dissolution-reconstruction process of the aragonite-aragonite transformation, complexing with calcium ions dissolved from the aragonite, slowing the transformation rate, thereby reducing the system's water requirement and consequently decreasing internal porosity. Additionally, during aragonite reconstruction, triethanolamine may promote radial crystal growth, increasing the aragonite crystal's aspect ratio and enhancing the mechanical interlocking effect. Finally, after curing and drying the sample, triethanolamine can fill the pores created by moisture evaporation.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] The organic filler material used in this invention is not only compatible with other components in the cementitious material, but also forms a stable network structure during the drying process, effectively reducing porosity and improving the overall density and mechanical strength of the material. This improvement makes the material perform excellently in engineering applications that bear heavy loads or require high durability.

[0024] The addition of organic filler materials significantly improves the mechanical properties of the novel negative carbon cementitious material, which not only broadens its application range, such as building structures, road construction, and water conservancy projects, but also meets the high requirements for the mechanical properties of materials in these fields.

[0025] This invention addresses the shortcomings of existing carbon-negative cementitious materials in terms of mechanical properties through the addition of organic fillers, resulting in a novel carbon-negative composite material. This technological innovation provides a new direction for the research and development of carbon-negative materials and helps to promote technological progress in the industry.

[0026] The method of this invention is compatible with existing production processes and can be easily integrated into existing production lines without large-scale modifications or additional production steps, which helps reduce the complexity and risks of technology transformation.

[0027] By filling the pores with organic filler materials, the material of this invention exhibits better durability and stability during long-term use, reduces maintenance costs, and improves the economic benefits of the project. Attached Figure Description

[0028] Figure 1Scanning electron microscope images of the negative carbon composite materials obtained in Examples 1-3.

[0029] Figure 2 Scanning electron microscope image of the negative carbon material obtained in Comparative Example 1. Detailed Implementation

[0030] The following embodiments further illustrate the technical solution of the present invention, but are not intended to limit the scope of protection of the present invention.

[0031] Example

[0032] This embodiment provides a carbon-negative composite material, the components of which include aragonite-type calcium carbonate, magnesium salt, strontium salt, water, and organic filler. The aragonite-type calcium carbonate is prepared as follows: 20% CO2 gas is passed into a calcium-rich solution (Ca) after water washing and salt extraction using a bubbling method. 2+ Precipitate was obtained by filtration and drying of the suspension after the reaction (concentration = 0.23 mol / L) to obtain aragonite-type calcium carbonate.

[0033] Four groups of negative carbon composite materials with different proportions were designed, numbered 1-1, 1-2, 1-3, and 1-4. The content of each component is given in parts by mass in Table 1.

[0034] The preparation process is as follows:

[0035] Magnesium salt and strontium salt are dissolved in water to prepare a mixed solution containing magnesium ions and strontium ions. Then, triethanolamine is added to the above mixed solution containing magnesium ions and strontium ions and stirred to disperse, thereby obtaining a homogeneous mixed solution.

[0036] Add the aragonite-type calcium carbonate to the mixing pot and stir, then add the above homogeneous mixed solution and stir for 1 to 5 minutes until a slurry is formed;

[0037] The above slurry was poured into a mold, vibrated to remove bubbles, and 20×20×20mm test blocks were formed. After forming, the test blocks were steam cured at 90℃ for 1 hour and then demolded. The test blocks were then dried in an oven at 105℃ for 8 hours to obtain the negative carbon composite material.

[0038] Comparative Example 1

[0039] Compared to the embodiments, no organic filler material was added in Comparative Example 1, while the other components and steps remained the same as in Examples 1-3.

[0040] Comparative Example 2

[0041] Compared to the embodiments, in Comparative Example 2, the organic filler material was replaced with polypropylene glycol, and the amount of water used was the minimum amount of water required to produce rheological properties in the slurry.

[0042] Comparative Example 3

[0043] Compared to the embodiments, in Comparative Example 3, the organic filler material was replaced with chitosan, and the amount of water used was the minimum amount of water required to produce rheological properties in the slurry.

[0044] Table 1 (Dosage unit: g)

[0045]

[0046] The strength and phase composition of the test blocks obtained in Example 1 are shown in Table 2.

[0047] Table 2

[0048]

[0049] As shown in Table 2, the addition of organic fillers resulted in a certain degree of strength improvement compared to Comparative Example 1. When using polypropylene glycol, the strength improvement was the highest, approximately 7%. However, during the experiment, it was found that the addition of polyethylene glycol caused the slurry to eventually become creamy, which was not conducive to molding. For chitosan, simply mixing it with aragonite-type calcium carbonate and stirring it for molding could not achieve the high strength of natural seashells, and it seemed to induce the formation of some calcite. Triethanolamine, on the other hand, showed the highest compatibility with the system. The addition of triethanolamine reduced the water demand of the system and decreased the porosity inside the specimen after water evaporation, thereby significantly improving the mechanical properties of the specimen (by more than 60%). Although it also caused calcite formation, it did not seem to lead to a decrease in mechanical properties. Furthermore, the types of magnesium and strontium salts did not seem to have a significant impact on the material properties. Figure 1 and Figure 2 The images shown are scanning electron microscope images of Examples 1-3 and Comparative Example 1, respectively. It is clear that the addition of triethanolamine increases the aspect ratio of the aragonite crystals, which strengthens the mechanical interlocking between the crystals. In addition, the filling of the internal pores of the test block with gel-like substances may also be the reason for the increase in strength.

Claims

1. A method for preparing a carbon-negative composite material, characterized in that... Includes the following steps: (1) Dissolve magnesium salt and strontium salt in water, add organic filler material and stir to disperse to obtain a homogeneous mixed solution; (2) Stir the aragonite-type calcium carbonate with the above homogeneous mixed solution until a slurry is formed; (3) The above slurry is poured into a mold and cured; including steam curing at 50~90℃ for 1~8h, demolding, and then drying at 90~130℃ for 8~20h to obtain the negative carbon composite material; The raw material composition by weight is as follows: 50-130 parts of aragonite-type calcium carbonate, 0.2-2.5 parts of magnesium salt, 1.0-4.5 parts of strontium salt, 10-40 parts of water, and 0.87-4 parts of organic filler material; the organic filler material is triethanolamine; triethanolamine participates in the dissolution-reconstruction process of aragonite transformation into aragonite, and after the specimen is cured and dried, it can also fill the pores inside caused by moisture evaporation.

2. The method for preparing the negative carbon composite material as described in claim 1, characterized in that... The magnesium salt is one or a mixture of MgCl2 and Mg(NO3)2.

3. The method for preparing the negative carbon composite material as described in claim 1, characterized in that... The strontium salt is one or a mixture of SrCl2 and Sr(NO3)2.

4. The method for preparing the negative carbon composite material as described in claim 1, characterized in that... The aragonite-type calcium carbonate is prepared in the following manner: The CO2-containing tail gas was passed into the calcium-rich solution after water washing and salt extraction using the bubbling method to obtain a suspension containing calcium carbonate precipitate. The suspension was filtered and dried to obtain spheroidal calcium carbonate.

5. The method for preparing the negative carbon composite material as described in claim 4, characterized in that... The calcium-rich solution is the filtrate obtained after washing and salt extraction of ash from the kiln bypass vent, in which Ca... 2+ Concentration ≥ 0.05 mol / L.

6. The method for preparing the negative carbon composite material as described in claim 4, characterized in that... The CO2-containing exhaust gas is industrial flue gas, with a CO2 concentration of 10vt% to 37vt.

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