Process method for realizing carbon dioxide sequestration and mineralization in whole concrete preparation process

Abstract

The invention provides a process method for realizing carbon dioxide sequestration and mineralization in a whole concrete preparation process, and belongs to the technical field of concrete preparation. Comprising the following steps: S1, preparing raw materials; s2, carrying out pre-carbonization treatment; s3, mixing and stirring; s4, forming; s5, performing multi-stage carbonization maintenance; and S6, carrying out post-treatment. Carbon dioxide is introduced in the whole process of concrete preparation, and maximum utilization and storage of carbon dioxide are achieved. The reaction activity of the material is improved by adopting pre-carbonization treatment, full reaction is ensured by injecting carbon dioxide in stages, and deep carbonization is promoted by multi-stage carbonization maintenance. According to the method, the storage amount of carbon dioxide is remarkably increased, the mechanical property, durability and carbonization resistance of the concrete are greatly improved, and a new technical path is provided for low-carbon development of the concrete industry.

Description

Technical Field

[0001] This invention relates to the field of concrete preparation technology, and in particular to a process for achieving carbon dioxide sequestration and mineralization throughout the entire concrete preparation process. Background Technology

[0002] Concrete is one of the most widely used man-made materials in the world today, playing an indispensable role in global infrastructure construction. However, traditional concrete production processes generate significant amounts of carbon dioxide emissions, placing immense pressure on the environment. Statistics show that global cement production contributes approximately 8% of total anthropogenic carbon dioxide emissions annually, and this figure continues to rise.

[0003] Faced with the increasingly severe problem of climate change, reducing carbon emissions from the concrete industry has become an international consensus and an urgent need. Currently, scholars and companies both domestically and internationally have conducted extensive research attempting to achieve carbon dioxide sequestration and utilization during concrete production. This research mainly focuses on the following aspects: 1. Raw material substitution: Using industrial by-products such as fly ash and slag to partially replace cement reduces cement usage and thus lowers carbon emissions.

[0004] 2. Improve cement production process: Develop new low-carbon cement, optimize clinker calcination process, and reduce carbon emissions during cement production.

[0005] 3. Concrete mix design optimization: By optimizing the concrete mix design, cement utilization efficiency can be improved, indirectly reducing carbon emissions.

[0006] 4. Carbon capture and storage: Capturing carbon dioxide during cement production and storing it or using it in other industrial processes.

[0007] However, the above methods still have some limitations in practical applications. For example, raw material substitution may affect the early strength development of concrete; the production cost of new low-carbon cement is high, making it difficult to promote on a large scale; carbon capture technology is still in the experimental stage, with high costs and energy consumption.

[0008] In recent years, a new approach has gradually attracted researchers' attention: directly utilizing carbon dioxide for mineralization reactions during concrete preparation. The principle behind this method is to use carbon dioxide to chemically react with cement hydration products or elements such as calcium and magnesium in aggregates to generate carbonate minerals, thereby achieving carbon dioxide fixation. This method can not only reduce carbon dioxide emissions but also promises to improve the performance of concrete.

[0009] In the existing technology, there are many patents involving the use of carbon dioxide for sequestration and mineralization during the concrete preparation process. Based on their technical characteristics, they can be roughly divided into two categories: one is adding carbon dioxide during the concrete mixing stage, and the other is carbon dioxide curing after the concrete has been formed.

[0010] Representative patents for the first type of method include CN113816767A and CN113650160A. The technical feature of this type of method is the injection of carbon dioxide into cement-based materials in a closed mixing device, allowing it to fully contact the materials and achieve early carbonization and uniform overall carbonization. Its advantages are: 1) it can improve the mechanical properties and long-term durability of hardened cement-based materials; 2) it has lower process requirements, is easier to control, and has certain economic benefits. However, this type of method also has significant shortcomings: 1) due to the limited mixing time, the reaction time between carbon dioxide and cement-based materials is insufficient, which may lead to less than ideal carbon dioxide absorption; 2) introducing carbon dioxide only during the mixing stage fails to fully utilize the carbonization potential in the subsequent curing stage, limiting the maximum amount of carbon dioxide sequestrated.

[0011] Representative patents for the second type of method include CN111217566A and CN112266204A. The technical feature of this type of method is carbon dioxide curing after the concrete product is formed. CN111217566A improves the high-temperature resistance of concrete blocks through carbon dioxide curing; CN112266204A optimizes the porosity of the blocks by controlling the water-to-solid ratio and molding pressure to enhance the carbon dioxide curing effect. The advantages of this type of method are: 1) it can achieve carbonation without affecting the early strength of the concrete; 2) it can be optimized for specific properties (such as high-temperature resistance). However, this type of method also faces common technical problems: 1) carbon dioxide has difficulty penetrating deeply into the interior of the product, resulting in the carbonation reaction being mainly limited to the surface area, leading to low overall sealing efficiency; 2) it requires additional curing equipment and processes, increasing production costs and complexity.

[0012] In summary, while existing technologies have made some progress in carbon dioxide sequestration and concrete performance improvement, the following technical problems still exist: 1. The utilization of carbon dioxide is limited to the single stage of concrete preparation, and the carbon dioxide sequestration and mineralization of the entire process cannot be realized, resulting in less than ideal sequestration efficiency.

[0013] 2. The amount of carbon dioxide injected and the reaction conditions are not precisely controlled, making it difficult to maximize the amount of carbon dioxide sequestration while ensuring the performance of concrete.

[0014] 3. There is a lack of systematic technological methods to coordinate the relationship between carbon dioxide sequestration and concrete performance improvement, making it difficult to achieve the best balance between the two.

[0015] Therefore, there is an urgent need in this field to develop a process that can achieve efficient carbon dioxide sequestration and mineralization throughout the entire concrete preparation process. Summary of the Invention

[0016] The purpose of this invention is to provide a process for achieving carbon dioxide sequestration and mineralization in the entire process of concrete preparation, in order to solve the above-mentioned technical problems.

[0017] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a process for achieving carbon dioxide sequestration and mineralization throughout the entire concrete preparation process, comprising the following steps: 1) Place cement and mineral admixtures in a pre-carbonization reactor, introduce carbon dioxide gas of a preset concentration, and carry out pre-carbonization treatment under preset temperature and humidity conditions to form pre-carbonized powder material. 2) Add the pre-carbonized powder material, aggregate, special admixture and water into a closed forced mixer according to the preset ratio, and inject carbon dioxide gas in stages during the mixing process; 3) Pour the mixed concrete slurry into the mold, use vibration and pressure to form the molded part, and then perform multi-stage carbonation curing.

[0018] Furthermore, the cement is ordinary Portland cement with a C3S content of not less than 60%, the mineral admixtures are granulated blast furnace slag powder and Class F fly ash, the special admixtures include carbonate seed crystals and alkali activators, and the aggregates are natural river sand and crushed stone.

[0019] Furthermore, in step 1), the concentration of carbon dioxide gas is 10-20%; the preset temperature is 40-60℃, the relative humidity is 60-80%, and the processing time is 30-60 minutes.

[0020] Furthermore, in step 2), the water-cement ratio is 0.3~0.4, and the phased injection of carbon dioxide gas is as follows: the first stage is dry mixing for 2~5 minutes; the second stage is adding admixtures and water and wet mixing for 3~5 minutes; the third stage is injecting carbon dioxide gas and continuing to stir for 5~10 minutes; the amount of carbon dioxide gas injected is 2~5% of the total mass of the cementitious material.

[0021] Furthermore, the multi-stage carbonization curing is divided into: high-pressure carbonization, normal-pressure carbonization, and wet-heat carbonization; The conditions for high-pressure carbonization are: carbon dioxide gas concentration of 80-100%, pressure of 0.5-2 MPa, temperature of 40-60℃, and processing time of 2-4 hours.

[0022] Furthermore, the conditions for atmospheric pressure carbonization are: a carbon dioxide gas concentration of 20-40%, a temperature of 20-30°C, a relative humidity of 60-80%, and a processing time of 24-48 hours.

[0023] Furthermore, the conditions for the wet heat carbonization are: a carbon dioxide gas concentration of 5-10%, a temperature of 60-80°C, a relative humidity of 90-100%, and a processing time of 48-72 hours.

[0024] Furthermore, the conditions for vibration-pressurization molding are: frequency 40~60Hz, pressure 1~5MPa.

[0025] Furthermore, the mass ratio of the cement, granulated blast furnace slag powder, and F-type fly ash is 3~5:3~5:1~3.

[0026] The beneficial effects of this invention are: 1. Full-process carbonization: This invention maximizes the utilization and sequestration of carbon dioxide by introducing it throughout the entire concrete preparation process (including raw material pretreatment, mixing, molding, and curing stages). This full-process carbonization method significantly improves carbon dioxide sequestration efficiency and overcomes the limitations of existing technologies that only perform carbonization in a single stage.

[0027] 2. Pre-carbonation treatment: By pre-carbonizing cement and mineral admixtures, the specific surface area and reactivity of the materials are increased, laying the foundation for the subsequent carbonation process. This is an innovative step not found in existing technologies.

[0028] 3. Staged carbon dioxide injection: The staged carbon dioxide injection method during the mixing process ensures sufficient contact and reaction between carbon dioxide and concrete paste, while avoiding the adverse effects of premature carbonation on concrete fluidity.

[0029] 4. Multi-stage carbonation curing: An innovative multi-stage carbonation curing system combining high-pressure carbonation, normal-pressure carbonation, and wet-heat carbonation is proposed. This method can promote the deep penetration and reaction of carbon dioxide under different temperature, pressure, and humidity conditions, overcoming the problem of carbon dioxide's difficulty in penetrating the interior of concrete in existing technologies.

[0030] 5. Specialized additives: Specialized additives such as carbonate seed crystals and alkali activators are used to further promote the carbonation reaction and the formation of carbonate minerals, thereby improving the carbon dioxide sequestration efficiency.

[0031] 6. Performance optimization: Through full-process carbonization and multi-stage carbonization curing, not only is the carbon dioxide sequestration maximized, but the mechanical properties, durability and impermeability of concrete are also significantly improved, achieving the dual goals of carbon emission reduction and performance improvement.

[0032] 7. Technological Feasibility: All steps of this invention can be implemented on existing concrete production equipment with only appropriate modifications, and it has good prospects for engineering applications.

[0033] In summary, the carbon dioxide sequestration and mineralization process for the entire concrete preparation process provided by this invention achieves efficient carbon dioxide sequestration and comprehensive improvement of concrete performance through innovative technical means, providing a new technical path for the low-carbon development of the concrete industry. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the process flow of the present invention; Figure 2 This is a schematic diagram of the multi-stage carbonization curing system in this invention; In the diagram: 1-Pre-carbonization reactor, 2-Closed forced mixer, 3-Vibration pressure molding equipment, 4-High-pressure carbonization kettle, 5-Atmospheric pressure carbonization chamber, 6-Wet heat carbonization chamber; Figure 3 This is a comparison chart of the properties of concrete prepared by the method of this invention and by conventional methods; Figure 4 The graph shows the concrete performance test results for Example 2. Detailed Implementation

[0035] This invention provides a process for achieving carbon dioxide sequestration and mineralization throughout the entire concrete preparation process, comprising the following steps: 1) Place cement and mineral admixtures in a pre-carbonization reactor, introduce carbon dioxide gas of a preset concentration, and carry out pre-carbonization treatment under preset temperature and humidity conditions to form pre-carbonized powder material. 2) Add the pre-carbonized powder material, aggregate, special admixture and water into a closed forced mixer according to the preset ratio, and inject carbon dioxide gas in stages during the mixing process; 3) Pour the mixed concrete slurry into the mold, use vibration and pressure to form the molded part, and then perform multi-stage carbonation curing.

[0036] In this invention, the cement is ordinary Portland cement with a C3S content of not less than 60%, the mineral admixtures are granulated blast furnace slag powder and Class F fly ash, the special admixtures include carbonate seed crystals and alkali activators, and the aggregates are natural river sand and crushed stone.

[0037] In this invention, in step 1), the concentration of carbon dioxide gas is 10-20%, preferably 12-18%, and more preferably 15%; the preset temperature is 40-60℃, preferably 45-55℃, and more preferably 50℃; the relative humidity is 60-80%, preferably 65-75%, and more preferably 70%; and the processing time is 30-60 min, preferably 40-50 min.

[0038] In this invention, in step 2), the water-cement ratio is 0.3~0.4, preferably 0.35; the staged injection of carbon dioxide gas is as follows: the first stage is dry mixing for 2~5 minutes; the second stage is adding admixtures and water, and wet mixing for 3~5 minutes; the third stage is injecting carbon dioxide gas and continuing to stir for 5~10 minutes; the amount of carbon dioxide gas injected is 2~5% of the total mass of the cementitious material, preferably 3~4%.

[0039] In this invention, the multi-stage carbonization curing is divided into: high-pressure carbonization, normal-pressure carbonization, and wet-heat carbonization; The conditions for high-pressure carbonization are as follows: carbon dioxide gas concentration of 80-100%, pressure of 0.5-2 MPa, temperature of 40-60°C, and processing time of 2-4 hours; preferably, carbon dioxide gas concentration of 85-95%, pressure of 1-2 MPa, temperature of 45-55°C, and processing time of 3-4 hours; more preferably, carbon dioxide gas concentration of 90%, pressure of 1.5 MPa, temperature of 50°C, and processing time of 3 hours.

[0040] In this invention, the atmospheric pressure carbonization conditions are as follows: carbon dioxide gas concentration of 20-40%, temperature of 20-30°C, relative humidity of 60-80%, and processing time of 24-48 hours; preferably, carbon dioxide gas concentration of 25-35%, temperature of 25-30°C, relative humidity of 65-75%, and processing time of 30-48 hours; more preferably, carbon dioxide gas concentration of 30%, temperature of 25°C, relative humidity of 70%, and processing time of 35 hours.

[0041] In this invention, the conditions for wet heat carbonization are: a carbon dioxide gas concentration of 5-10%, a temperature of 60-80°C, a relative humidity of 90-100%, and a processing time of 48-72 hours; preferably, a carbon dioxide gas concentration of 6-9%, a temperature of 65-75°C, a relative humidity of 95-100%, and a processing time of 50-72 hours; more preferably, a carbon dioxide gas concentration of 8%, a temperature of 70°C, a relative humidity of 95%, and a processing time of 60-72 hours.

[0042] In this invention, the conditions for vibration-pressurization molding are: frequency 40~60Hz, preferably 45~55Hz; pressure 1~5MPa, preferably 2~4MPa, and more preferably 3MPa.

[0043] In this invention, the mass ratio of cement, granulated blast furnace slag powder and F-type fly ash is 3~5:3~5:1~3, preferably 4:4:2.

[0044] The application scope of this invention includes, but is not limited to, the preparation of various concrete components, such as precast concrete slabs, concrete pipe piles, concrete blocks, etc., as well as on-site concrete casting projects. It can be widely used in infrastructure construction fields such as buildings, roads, bridges, and water conservancy.

[0045] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0046] Example 1

[0047] A process for achieving carbon dioxide sequestration and mineralization throughout the entire concrete preparation process, comprising the following steps: S1. Raw material preparation: Ordinary Portland cement with a C3S content of 65% is selected, along with granulated blast furnace slag powder (specific surface area 450 m² / kg), Class F fly ash, calcium carbonate seed crystals (particle size <1 μm), alkali activator (sodium metasilicate), natural river sand (fineness modulus 2.8), and crushed stone (particle size 5~20 mm).

[0048] S2. Pre-carbonization treatment: Cement, slag powder, and fly ash were mixed in a mass ratio of 4:4:2 and placed in a pre-carbonization reactor. A 15% concentration of carbon dioxide gas was introduced, and the mixture was treated at 50°C and 70% relative humidity for 45 minutes to form a pre-carbonized powder material.

[0049] S3. Mixing and stirring: The pre-carbonized powder material, aggregate, special admixture, and water are added to a closed forced mixer at a water-to-binder ratio of 0.35. The mixing process consists of three stages: (1) Dry mixing: 2.5 min; (2) Wet mixing: Add water and additives, and stir for 4 minutes; (3) Carbonization stirring: Inject 3% (relative to the mass of cementitious material) of carbon dioxide gas and continue stirring for 6 minutes.

[0050] S4. Molding: The mixed concrete slurry is poured into the mold and vibrated for 30 seconds using a vibrating table with a frequency of 50Hz and an amplitude of 0.5mm, while a pressure of 2MPa is applied to shape it.

[0051] S5. Multi-stage carbonization curing: (1) High-pressure carbonization: The molded concrete product is placed in a high-pressure carbonization kettle, and 90% carbon dioxide gas is introduced. It is treated for 3 hours at a pressure of 1 MPa and a temperature of 50°C. (2) Atmospheric pressure carbonization: The product is transferred to an atmospheric pressure carbonization chamber, and carbon dioxide gas with a concentration of 30% is introduced. The product is treated at 25°C and 70% relative humidity for 36 hours. (3) Moist heat carbonization: Finally, the product is placed in a moist heat carbonization chamber and 70% carbon dioxide gas is introduced. It is treated for 60 hours at 70°C and 95% relative humidity.

[0052] S6. Post-processing: The concrete products after carbonation curing are surface polished and tested for compressive strength, impermeability and carbonation depth.

[0053] Experimental results: The concrete test blocks prepared according to the above method were compared with the control group prepared by the traditional method. The test results are shown in Table 1. Figure 3 As shown.

[0054] Table 1. Comparison of concrete properties prepared by the method of this invention and conventional methods

[0055] Example 2

[0056] Based on Example 1, the pre-carbonization conditions were adjusted to: carbon dioxide concentration 18%, temperature 55°C, relative humidity 75%, and processing time 55 min. Other steps remained unchanged.

[0057] The test results are shown in Table 2. Figure 4 As shown.

[0058] Table 2. Concrete performance test results of Example 2

[0059] As can be seen from the experimental data of the above embodiments, the carbon dioxide sequestration and mineralization process of the present invention in the entire concrete preparation process has the following significant advantages compared with traditional methods: 1. The carbon dioxide sequestration capacity is significantly increased. Each cubic meter of concrete can sequester 135-142 kg of carbon dioxide, which is more than three times that of traditional methods.

[0060] 2. The compressive strength increases by 28-34% after 28 days, significantly improving the mechanical properties of concrete.

[0061] 3. The impermeability has been improved from P8 to P12, an increase of 50%, which significantly enhances the durability of the concrete.

[0062] 4. By adjusting the pre-carbonation treatment conditions (as shown in Example 2), the concrete performance and carbon dioxide sequestration effect can be further optimized.

[0063] As can be seen from the above embodiments, the present invention provides a process method for realizing carbon dioxide sequestration and mineralization in the entire process of concrete preparation. This method can maximize the amount of carbon dioxide sequestrated, significantly improve the performance of concrete, and at the same time ensure the feasibility and economy of the process.

[0064] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A process for achieving carbon dioxide sequestration and mineralization throughout the entire concrete preparation process, characterized in that, Includes the following steps: 1) Place cement and mineral admixtures in a pre-carbonization reactor, introduce carbon dioxide gas of a preset concentration, and carry out pre-carbonization treatment under preset temperature and humidity conditions to form pre-carbonized powder material. 2) Add the pre-carbonized powder material, aggregate, special admixture and water into a closed forced mixer according to the preset ratio, and inject carbon dioxide gas in stages during the mixing process; 3) Pour the mixed concrete slurry into the mold, use vibration and pressure to form the molded part, and then perform multi-stage carbonation curing.

2. The process for achieving carbon dioxide sequestration and mineralization in the entire concrete preparation process according to claim 1, characterized in that, The cement is ordinary Portland cement with a C3S content of not less than 60%, the mineral admixtures are granulated blast furnace slag powder and Class F fly ash, the special admixtures include carbonate seed crystals and alkali activators, and the aggregates are natural river sand and crushed stone.

3. The process for achieving carbon dioxide sequestration and mineralization in the entire concrete preparation process according to claim 1 or 2, characterized in that, In step 1), the concentration of carbon dioxide gas is 10-20%; the preset temperature is 40-60℃, the relative humidity is 60-80%, and the processing time is 30-60 minutes.

4. The process for achieving carbon dioxide sequestration and mineralization in the entire concrete preparation process according to claim 3, characterized in that, In step 2), the water-cement ratio is 0.3-0.4, and the phased injection of carbon dioxide gas is as follows: the first stage is dry mixing for 2-5 minutes; the second stage is adding admixtures and water and wet mixing for 3-5 minutes; the third stage is injecting carbon dioxide gas and continuing to stir for 5-10 minutes; the amount of carbon dioxide gas injected is 2-5% of the total mass of the cementitious material.

5. The process for achieving carbon dioxide sequestration and mineralization in the entire concrete preparation process according to claim 1 or 4, characterized in that, The multi-stage carbonization curing process is divided into: high-pressure carbonization, normal-pressure carbonization, and wet-heat carbonization. The conditions for high-pressure carbonization are: carbon dioxide gas concentration of 80-100%, pressure of 0.5-2 MPa, temperature of 40-60℃, and processing time of 2-4 hours.

6. The process for achieving carbon dioxide sequestration and mineralization in the entire concrete preparation process according to claim 5, characterized in that, The conditions for atmospheric pressure carbonization are: carbon dioxide gas concentration of 20-40%, temperature of 20-30℃, relative humidity of 60-80%, and processing time of 24-48h.

7. The process for achieving carbon dioxide sequestration and mineralization in the entire concrete preparation process according to claim 5, characterized in that, The conditions for the wet heat carbonization are: a carbon dioxide gas concentration of 5-10%, a temperature of 60-80℃, a relative humidity of 90-100%, and a processing time of 48-72 hours.

8. The process for achieving carbon dioxide sequestration and mineralization in the entire concrete preparation process according to claim 1, 6, or 7, characterized in that, The conditions for vibration-pressurization molding are: frequency 40~60Hz, pressure 1~5MPa.

9. The process for achieving carbon dioxide sequestration and mineralization in the entire concrete preparation process according to claim 2, characterized in that, The mass ratio of the cement, granulated blast furnace slag powder and F-type fly ash is 3~5:3~5:1~3.

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