An ultra-high strength carbon sequestration cementitious material and a method of making the same

Abstract

The application discloses an ultrahigh-strength carbon sequestration cementing material and a preparation method thereof. The preparation method comprises the following steps: uniformly mixing the carbon sequestration cementing material, amphiphilic hydrophilic block copolymer and water to obtain a mixture; and performing molding and carbonization curing on the mixture to obtain the ultrahigh-strength carbon sequestration cementing material. The application creatively uses the amphiphilic hydrophilic block copolymer as a carbonization enhancer of the carbon sequestration cementing material, greatly improves the mechanical property of the carbon sequestration cementing material, and the amphiphilic hydrophilic block copolymer can regulate the crystal form of carbonization products, combines with calcium ions to form a hydrogel with an ionic crosslinking network and filled in pores, can be used as a template for calcium carbonate crystallization to form a carbon organic-inorganic composite structure, makes calcium carbonate grains grow in an orientation manner, improves the combination between calcium carbonate crystals, and greatly improves the mechanical property of the material. The enhancement technology is simple in process and low in cost, widens the application range of the carbon sequestration cementing material, and has a good application prospect.

Description

Technical Field

[0001] This invention relates to the field of carbon-fixing cementitious materials technology, specifically to an ultra-high strength carbon-fixing cementitious material and its preparation method. Background Technology

[0002] The cement industry is a recognized major emitter of carbon dioxide. Statistics show that the global cement industry's annual carbon dioxide emissions exceed 2 billion metric tons, accounting for 8% of total global carbon emissions. With the intensifying greenhouse effect, reducing carbon dioxide emissions is imperative. The preparation and application of carbon-fixed cementitious materials have become one of the important measures to achieve energy conservation and emission reduction in the cement building materials industry. The origins of carbon-fixed cementitious materials can be traced back to the 1970s. R.L. Berger et al. discovered that carbonization can promote the hydration reaction of calcium silicate minerals, and even calcium silicate minerals with extremely low hydration activity, such as CS and γ-C2S, possess high carbonization activity and can achieve high strength in a very short time. This series of studies demonstrates that almost all alkaline calcium silicate minerals in cement have carbonization activity, opening a new door for the development of building materials.

[0003] In recent years, due to improvements in carbonization processes, the carbonization of calcium silicate minerals has become a research hotspot. Sixue Zhao et al. (Carbonation reactivity enhancement of γ-C2S through biomineralization. Journal of CO2 Utilization, 2020, 39:101183) accelerated the nucleation and growth of carbonization products by adding calcite seed crystals as nucleation sites, thereby giving γ-C2S higher carbonization activity. Chinese invention patent CN111393049A discloses an activation modification method for γ-C2S. After γ-C2S is doped with metal ions and sintered, the metal ions are enriched at the grain boundaries and replace some calcium ions to form a continuous solid solution. The compressive strength of the carbonized products prepared by the activated γ-C2S is increased from 50 MPa to 70 MPa. Chinese invention patent CN111574137A discloses a layered shell-like nacre material and its preparation method. By combining cryogenic casting technology and carbonization technology, a layered shell-like nacre material is obtained. The resulting material has high fracture toughness and durability, with a compressive strength of 160 MPa and a tensile strength of 60 MPa. Chinese invention patent CN111018383A discloses a preparation method for chitosan-reinforced carbonized hardened bodies. It utilizes chitosan to regulate the crystal form of carbonized products, promotes the dissolution of calcium ions, and thus promotes the carbonization reaction, increasing the 24-hour compressive strength of the carbonized hardened body from 86 MPa to 144 MPa.

[0004] Mechanical properties, as one of the most important indicators of building materials, have always been a focus of scientific research. However, the mechanical properties of materials prepared by carbonization curing in current research still cannot meet market demands, and there is still much room for improvement. Summary of the Invention

[0005] The purpose of this invention is to overcome the above-mentioned technical deficiencies and propose an ultra-high strength carbon-fixed cementitious material and its preparation method, thereby solving the technical problem that the mechanical properties of carbon-fixed cement in the prior art still need to be improved.

[0006] In a first aspect, the present invention provides a method for preparing an ultra-high strength carbon-fixing cementitious material, comprising the following steps:

[0007] The carbon-fixing cementitious material, the amphiphilic block copolymer, and water are mixed evenly to obtain a mixture;

[0008] The mixture is molded and carbonized to obtain an ultra-high strength carbon-fixed cementitious material.

[0009] In a second aspect, the present invention provides an ultra-high strength carbon-fixing cementitious material, which is obtained by the preparation method of the ultra-high strength carbon-fixing cementitious material provided in the first aspect of the present invention.

[0010] Compared with the prior art, the beneficial effects of the present invention include:

[0011] This invention creatively utilizes amphiphilic block copolymers as carbonation reinforcing agents for solid carbon cementitious materials, significantly improving their mechanical properties. The amphiphilic block copolymers can regulate the crystal form of the carbonation products, combining with calcium ions to form a hydrogel with an ionic cross-linking network that fills the pores. This hydrogel can serve as a template for calcium carbonate crystallization, forming a carbon-organic-inorganic composite structure, enabling the oriented growth of calcium carbonate grains, improving the bonding between calcium carbonate crystals, and greatly enhancing the mechanical properties of the material. This reinforcing technology is simple, low-cost, and broadens the application range of solid carbon cementitious materials, showing promising application prospects. Attached Figure Description

[0012] Figure 1 These are the stress-strain curves of the compressive strength of the materials after carbonization in Examples 3, 5, and 6 of this invention, as well as Comparative Example 1.

[0013] Figure 2 These are SEM images of the carbonized materials in Examples 3, 5, and 6 of this invention, as well as Comparative Example 1. Detailed Implementation

[0014] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0015] In a first aspect, the present invention provides a method for preparing an ultra-high strength carbon-fixing cementitious material, comprising the following steps:

[0016] S1. Mix the carbon-fixing cementitious material, the amphiphilic block copolymer, and water evenly to obtain a mixture;

[0017] S2. The mixture is molded and carbonized to obtain an ultra-high strength carbon-fixed cementitious material.

[0018] In this invention, the aforementioned amphiphilic block copolymers all contain two types of segments. Segment one contains carboxyl groups and / or carboxylate ions, which can combine with calcium ions to form ionic bonds, thereby forming a hydrogel with ordered molecular chains. This serves as a template for calcium carbonate crystal growth, inducing directional crystallization and promoting oriented growth of calcium carbonate crystals, thus enhancing mechanical properties. Segment two contains polar groups, such as hydroxyl, carboxyl, and carboxylate ions, which utilize the complexation effect of polar groups with calcium ions to enrich calcium ions, ensuring that the calcium carbonate crystals in the hydrogel grow in an orderly manner using organic molecular chains as templates. Conventional carbonation reinforcing agents are polymers with certain polar groups, including chitosan and polyacrylamide. These polymers have only one structural unit and utilize the complexation effect of polar groups on calcium ions to promote carbonation. Therefore, the reinforcing mechanisms of the two are completely different.

[0019] In some specific embodiments of the present invention, the amphiphilic block copolymer is at least one of carboxylated cellulose, low-ester pectin, and gellan gum, more preferably carboxylated cellulose.

[0020] In some preferred embodiments of the present invention, the molecular weight of the amphiphilic block copolymer is 4,000-200,000, more preferably 40,000-120,000, and even more preferably 50,000-100,000.

[0021] The carbon-fixing cementing material is a calcium silicate mineral with strong carbonization reactivity. This invention does not limit the specific type of carbon-fixing cementing material used; those skilled in the art can select it according to actual needs. For example, the carbon-fixing cementing material can be at least one of calcium silicate minerals with strong carbonization reactivity, such as γ-type dicalcium silicate (γ-C2S), monocalcium silicate (CS), and tricalcium disilicate (C3S2). It can also be at least one of industrial solid wastes (such as steel slag powder) with calcium silicate minerals with strong carbonization reactivity as the main mineral phase (content not less than 50%). Alternatively, it can be a mixture of calcium silicate minerals with strong carbonization reactivity and industrial solid waste.

[0022] In this embodiment, the particle size of the carbon-fixing cementitious material is 5-15 μm.

[0023] In this embodiment, the amount of the amphiphilic block copolymer is 0.1%-3% of the carbon-fixing cementitious material, including but not limited to 0.1%, 0.3%, 0.5%, 0.8%, 1%, 1.2%, 1.5%, 1.8%, 2%, 2.3%, 2.5%, 2.8%, 3%, etc.

[0024] In some preferred embodiments of the present invention, the amount of the amphiphilic block copolymer is 1.5%-2.5% of the carbon-fixing cementitious material.

[0025] This invention does not limit the process of uniformly mixing the carbon-fixing cementitious material, the amphiphilic block copolymer, and water; those skilled in the art can choose the appropriate method based on the actual situation.

[0026] In some specific embodiments of the present invention, the process of uniformly mixing the carbon-fixing cementitious material, the amphiphilic block copolymer, and water includes:

[0027] The amphiphilic block copolymer was mixed with water to prepare an aqueous solution, and then the carbon-fixing cementitious material was mixed with the aqueous solution.

[0028] Furthermore, the concentration of the aqueous solution of the amphiphilic block copolymer is 0.005-0.5 g / mL, specifically 0.02-0.2 g / mL.

[0029] Furthermore, during the process of uniformly mixing the amphiphilic block copolymer with water to prepare an aqueous solution, the stirring temperature is 40-60℃, the stirring rate is 200-400 r / min, and the stirring time is 2-4 h.

[0030] Furthermore, during the process of uniformly mixing the amphiphilic block copolymer with water to prepare an aqueous solution, a water bath heating method was used, and the mixture was stirred at 60°C for 4 hours at a stirring speed of 400 r / min.

[0031] Furthermore, during the process of uniformly mixing the carbon-fixing cementitious material with the aqueous solution, the stirring temperature is room temperature, the stirring rate is 500-800 r / min, and the stirring time is 10-15 min.

[0032] In this embodiment, the mass ratio of carbon-fixing cementitious material to water is 1:(0.1-0.2), including but not limited to 1:0.1, 1:0.13, 1:0.15, 1:0.18, 1:0.2, etc.

[0033] This invention does not limit the molding method, and those skilled in the art can choose according to the actual situation. For example, the molding method can be compression molding, casting molding, kneading molding, etc.

[0034] In some specific embodiments of the present invention, the molding method is compression molding.

[0035] In some more specific embodiments of the present invention, the pressing pressure is 30-100MPa, including but not limited to 30MPa, 40MPa, 50MPa, 60MPa, 70MPa, 80MPa, 90MPa, 100MPa, etc.; the holding time is 1-5min, including but not limited to 1min, 2min, 3min, 4min, 5min, etc.

[0036] This invention does not limit the conditions for carbonization curing, and those skilled in the art can select the appropriate conditions based on the actual situation. In some specific embodiments of this invention, the conditions for carbonization curing are as follows: gas pressure of 0.1-0.5 MPa, including but not limited to 0.1 MPa, 0.2 MPa, 0.3 MPa, 0.4 MPa, 0.5 MPa, etc.; carbon dioxide concentration of 5%-100%, including but not limited to 5%, 10%, 15%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 99%, 100%, etc.; and time of 1-24 hours, including but not limited to 1 hour, 2 hours, 4 hours, 6 hours, 8 hours, 10 hours, 12 hours, 14 hours, 16 hours, 18 hours, 20 hours, 22 hours, 24 hours, etc.

[0037] This invention does not impose any particular limitation on the source of carbon dioxide gas or its carbon dioxide content; it can be obtained in a manner well known in the art. In some specific embodiments of this invention, the source of carbon dioxide gas used for carbonization curing is preferably industrial waste gas rich in carbon dioxide, and more specifically, high-concentration carbon dioxide gas enriched from various types of industrial waste gas.

[0038] Unless otherwise specified, all raw materials required for preparation in this invention are commercially available products well known to those skilled in the art.

[0039] In a second aspect, the present invention provides an ultra-high strength carbon-fixing cementitious material, which is obtained by the preparation method of the ultra-high strength carbon-fixing cementitious material provided in the first aspect of the present invention.

[0040] Example 1

[0041] A method for preparing an ultra-high strength carbon-fixing cementitious material includes the following steps:

[0042] Weigh 10g of γ-C2S and mix it with an aqueous solution of carboxylated cellulose (molecular weight 50000) with a concentration of 0.03g / mL at a water-cement ratio of 0.15. Stir the mixture evenly, then press it into shape under a molding pressure of 60MPa. After holding the pressure for 3 minutes, cure it for 24 hours in a carbon dioxide atmosphere with a pressure of 0.3MPa and a concentration of 99%.

[0043] Example 2

[0044] A method for preparing an ultra-high strength carbon-fixing cementitious material includes the following steps:

[0045] Weigh 10g of γ-C2S and mix it with an aqueous solution of carboxylated cellulose (molecular weight 50000) with a concentration of 0.06g / mL at a water-cement ratio of 0.15. Stir the mixture evenly, then press it into shape under a molding pressure of 60MPa. After holding the pressure for 3 minutes, cure it for 24 hours in a carbon dioxide atmosphere with a pressure of 0.3MPa and a concentration of 99%.

[0046] Example 3

[0047] A method for preparing an ultra-high strength carbon-fixing cementitious material includes the following steps:

[0048] Weigh 10g of γ-C2S and mix it with an aqueous solution of carboxylated cellulose (molecular weight 50000) with a concentration of 0.12g / mL at a water-cement ratio of 0.15. Stir the mixture evenly, then press it into shape under a molding pressure of 60MPa. After holding the pressure for 3 minutes, cure it for 24 hours in a carbon dioxide atmosphere with a pressure of 0.3MPa and a concentration of 99%.

[0049] Example 4

[0050] A method for preparing an ultra-high strength carbon-fixing cementitious material includes the following steps:

[0051] Weigh 10g of γ-C2S and mix it with an aqueous solution of carboxylated cellulose (molecular weight 50000) with a concentration of 0.18g / mL at a water-cement ratio of 0.15. Stir the mixture evenly, then press it into shape under a molding pressure of 60MPa. After holding the pressure for 3 minutes, cure it for 24 hours in a carbon dioxide atmosphere with a pressure of 0.3MPa and a concentration of 99%.

[0052] Example 5

[0053] A method for preparing an ultra-high strength carbon-fixing cementitious material includes the following steps:

[0054] Weigh 10g of γ-C2S and mix it with a low-ester pectin (molecular weight 100,000) aqueous solution with a concentration of 0.12g / mL at a water-cement ratio of 0.15. Stir the mixture evenly, then press it into shape under a molding pressure of 60MPa. After holding the pressure for 3 minutes, cure it for 24 hours in a carbon dioxide atmosphere with a pressure of 0.3MPa and a concentration of 99%.

[0055] Example 6

[0056] A method for preparing an ultra-high strength carbon-fixing cementitious material includes the following steps:

[0057] Weigh 10g of γ-C2S and mix it with a 0.12g / mL aqueous solution of gellan gum (molecular weight 100,000) at a water-cement ratio of 0.15. Stir the mixture evenly, then press it into shape under a molding pressure of 60MPa. After holding the pressure for 3 minutes, cure it for 24 hours in a carbon dioxide atmosphere with a pressure of 0.3MPa and a concentration of 99%.

[0058] Example 7

[0059] A method for preparing an ultra-high strength carbon-fixing cementitious material includes the following steps:

[0060] Weigh 10g of C3S2 and mix it with a carboxylated cellulose (molecular weight 50000) aqueous solution with a concentration of 0.12g / mL at a water-cement ratio of 0.15. Stir the mixture evenly, then press it into shape under a molding pressure of 60MPa. After holding the pressure for 3 minutes, cure it for 24 hours in a carbon dioxide atmosphere with a pressure of 0.3MPa and a concentration of 99%.

[0061] Example 8

[0062] A method for preparing an ultra-high strength carbon-fixing cementitious material includes the following steps:

[0063] Weigh 10g of CS and mix it with a carboxylated cellulose (molecular weight 50000) aqueous solution with a concentration of 0.12g / mL at a water-cement ratio of 0.15. Stir the mixture evenly, then press it into shape under a molding pressure of 60MPa. After holding the pressure for 3 minutes, cure it for 24 hours in a carbon dioxide atmosphere with a pressure of 0.3MPa and a concentration of 99%.

[0064] Comparative Example 1

[0065] Compared with the preparation process of Example 1, the only difference is that deionized water was used instead of carboxylated cellulose solution in Comparative Example 1, and the remaining steps were the same as in Example 1.

[0066] Comparative Example 2

[0067] The only difference between Comparative Example 2 and Example 3 is that Comparative Example 2 uses carboxylated cellulose with a molecular weight of 4000.

[0068] Comparative Example 3

[0069] The only difference between Comparative Example 3 and Example 3 is that Comparative Example 3 uses carboxylated cellulose with a molecular weight of 200,000.

[0070] experimental group

[0071] The mechanical properties and surface morphology of the carbon-fixing cementitious materials obtained in Examples 1-8 and Comparative Examples 1-3 were tested. The test results are shown in Table 1 and 2. Figure 1-2 .

[0072] Table 1

[0073]

[0074] Please refer to Table 1. The comparison of the mechanical properties of the carbon-fixed cementitious materials after carbonization curing in Examples 1-6 and Comparative Example 1 in Table 1 shows that the amphiphilic block copolymer has a significant promoting effect on the strength of the carbon-fixed cementitious materials. Compared with the blank group's 90 MPa, the compressive strength of the material after adding carboxylated cellulose can reach 273 MPa, the compressive strength of the material after adding low-ester pectin can reach 194 MPa, and the compressive strength of the material after adding gellan gum can reach 226 MPa. This is attributed to the oriented crystallization of calcium carbonate crystals and the formation of organic-inorganic composite materials, indicating that the amphiphilic block copolymer can act as a carbonization reinforcing agent for carbon-fixed cementitious materials and greatly improve the mechanical properties of the carbon-fixed cementitious materials after carbonization.

[0075] Please refer to Table 1. From the comparison of the mechanical properties of the carbon-fixed cementitious materials after carbonization curing in Examples 1-4 in Table 1, it can be seen that the material has the best mechanical properties when the concentration of carboxylated cellulose is 0.12 g / mL, with the compressive strength increasing from 90 MPa to 273 MPa and the flexural strength increasing from 20 MPa to 43 MPa.

[0076] Please refer to Table 1. The mechanical properties of the carbon-fixing gelling materials of Example 3 and Comparative Examples 2 and 3 in Table 1 show that the material with a molecular weight of 50,000 of carboxylated cellulose has the best mechanical properties. This indicates that if the molecular weight of carboxylated cellulose is too high or too low, it will not be conducive to further improvement of the material strength. However, it is still significantly higher than that of Comparative Example 1, which did not use amphiphilic block copolymer as carbonization reinforcing agent.

[0077] Please see Figure 1 , Figure 1 The figures in the middle show the stress-strain curves of the blank group (Comparative Example 1) and the materials after adding carboxylated cellulose (Example 3), low-ester pectin (Example 5), and gellan gum (Example 6). Figure 1 It can be seen that the compressive strength and elastic modulus of the material after adding carboxylated cellulose, low-ester pectin, and gellan gum are significantly improved compared with the blank group.

[0078] Please see Figure 2 , Figure 2 These are SEM images of the carbonized materials from Examples 3, 5, and 6 of this invention, as well as Comparative Example 1. Figure 2 It can be seen that the calcium carbonate carbonation products obtained in the examples of adding amphiphilic block copolymers in this invention can all be arranged in an orderly manner and grow in orientation under the template of the amphiphilic block copolymer.

[0079] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing an ultra-high strength carbon-fixing cementitious material, characterized in that, Includes the following steps: The carbon-fixing cementitious material, the amphiphilic block copolymer, and water are mixed evenly to obtain a mixture; The mixture is then molded and carbonized to obtain an ultra-high strength carbon-fixed cementitious material. The carbon-fixing cementitious material is at least one of calcium silicate mineral and industrial solid waste with a calcium silicate mineral content of not less than 50%; wherein the calcium silicate mineral is at least one of γ-type dicalcium silicate, monocalcium silicate, and tricalcium disilicate. The amphiphilic block copolymers all contain two types of segments: segment one contains carboxyl groups and / or carboxylate ions, and segment two contains polar groups; the amphiphilic block copolymers are at least one of carboxylated cellulose and low-ester pectin. The molecular weight of the amphiphilic block copolymer is 4,000-200,000.

2. The preparation method of the ultra-high strength carbon-fixing cementitious material according to claim 1, characterized in that, The molecular weight of the amphiphilic block copolymer is 50,000-100,000.

3. The preparation method of the ultra-high strength carbon-fixing cementitious material according to claim 1, characterized in that, The amount of the amphiphilic block copolymer is 0.1%-3% of the carbon-fixing cementitious material.

4. The preparation method of the ultra-high strength carbon-fixing cementitious material according to claim 1, characterized in that, The amount of the amphiphilic block copolymer is 1.5%-2.5% of the carbon-fixing cementitious material.

5. The preparation method of the ultra-high strength carbon-fixing cementitious material according to claim 1, characterized in that, The mass ratio of the carbon-fixing cementitious material to water is 1:(0.1-0.2).

6. The preparation method of the ultra-high strength carbon-fixing cementitious material according to claim 1, characterized in that, The molding method is compression molding, the compression molding pressure is 30-100MPa, and the holding time is 1-5min; the carbonization curing conditions are: air pressure 0.1-0.5MPa, carbon dioxide concentration 5%-100%, and time 1-24h.

7. A high-strength carbon-fixing cementitious material, characterized in that, The ultra-high strength carbon-fixing cementitious material is obtained by the preparation method of the ultra-high strength carbon-fixing cementitious material according to any one of claims 1-6.

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