Solid waste-based carbon sequestration member concrete and preparation method thereof

Abstract

The invention discloses solid waste-based carbon sequestration member concrete and a preparation method thereof, and relates to the technical field of building materials. The solid waste-based carbon sequestration member concrete comprises the following raw materials: 320-380 kg / m < 3 > of a novel carbon sequestration rubber material, 750-800 kg / m < 3 > of sand, 1010-1060 kg / m < 3 > of stone, 144-159.6 kg / m < 3 > of water, 0.48-0.57 kg / m < 3 > of a water reducing agent, 1.6-1.9 kg / m < 3 > of an early strength agent and 25.6-30.4 kg / m < 3 > of a carbonizer. The method comprises the following steps: preparing the raw materials in proportion, mixing, stirring to obtain a concrete mixture, pouring, and carrying out vibration molding. The mold is put into a standard curing box to be cured and then demolded; kiln tail flue gas normal-pressure curing is firstly adopted, then pressurization is conducted, pressurization curing is conducted, and the solid-waste-based carbon sequestration member concrete is obtained. According to the invention, various solid wastes are comprehensively utilized, a calcining process is optimized, the surface modification admixture is introduced, and the special cement clinker, the composite early strength agent and the like are selected, so that the carbon emission in cement production is reduced, and the carbon sequestration capacity of cement concrete is improved; cement kiln tail flue gas is adopted for carbonization curing, and the dual purposes of solid waste resource utilization and low-cost carbon sequestration are achieved.

Description

Technical Field

[0001] This invention relates to the field of building materials technology, and in particular to a solid waste-based carbon-fixing concrete component and its preparation method. Background Technology

[0002] Red mud is an alkaline solid waste generated during the dissolution of bauxite. Currently, the cumulative amount accumulated in my country has reached 790 million tons. Its long-term accumulation not only occupies a large amount of land resources but also poses a serious threat to the ecological environment due to its strong alkalinity. Although red mud contains various valuable metals and components, and theoretically can be used to recover metals or prepare building and environmental materials, its strong alkalinity greatly limits the scale and efficiency of its resource utilization, resulting in an extremely low overall recycling rate. Therefore, developing large-scale, high-value-added red mud resource utilization pathways is urgently needed.

[0003] Meanwhile, the cement industry, as a major consumer of energy and a major emitter of carbon dioxide, faces enormous pressure to reduce emissions. Taking China as an example, its cement production in 2023 (approximately 2.02 billion tons) accounted for more than half of the global total, making its emission reduction task particularly challenging. Reducing carbon emissions from the cement industry through carbon capture and storage (CCS) technology is now urgent. Among these approaches, replacing hydration with carbonization as the hardening mechanism of cementitious materials is considered a potential carbon reduction pathway. Carbon-fixed cementitious materials refer to materials that, after being mixed with water and non-hydraulic calcium silicate minerals, spontaneously react with carbon dioxide to bind other substances into a cohesive whole, possessing a certain mechanical strength. These mainly include three major systems: γ-C2S, C3S2, and CS. These low-calcium minerals have weak reactivity during early hydration; if their content in silicate cement is too high, it may affect strength development. However, early carbonization and solidification processes can significantly improve the material properties of these low-calcium minerals, making them a viable alternative to traditional cementitious materials. Among them, γ-C2S is the most stable of the five crystal forms in the C2S series at room temperature, exhibiting high carbonization reactivity.

[0004] In the construction industry, prefabricated buildings are becoming a key focus of industrialized construction due to their advantages in energy conservation, emission reduction, and construction efficiency. Precast concrete (PC) components are made from concrete and prefabricated in factories before being assembled on-site. They mainly include shear walls, interior partition walls, solid slabs, composite slabs, and stairs. Compared to traditional on-site concrete casting, PC components offer significant advantages in energy conservation, emission reduction, and cost reduction. However, to accelerate demolding and improve mold turnover and production efficiency, factories commonly use steam curing. Steam curing is energy-intensive, significantly increasing the production cost of PC components. Furthermore, the kiln tail gas emitted during cement production contains high concentrations of CO2 (typically 10%-30%), as well as water vapor, NOx, and dust. Utilizing cement kiln tail gas instead of steam for carbonation curing of PC components is considered a highly promising solution: firstly, it directly utilizes CO2 from industrial waste gas, reducing curing energy consumption and costs; secondly, the carbonates generated by the reaction of CO2 with cementitious materials help improve the early strength and durability of the components. Patent CN117534379A discloses a method for preparing low-carbon concrete using cement kiln tail flue gas curing. The method proposes pre-carbonizing cementitious materials to form nano-calcium carbonate, followed by distributed carbonization curing of the concrete using cement kiln tail flue gas to produce the finished low-carbon concrete. However, the method described in this invention is overly complex and not conducive to large-scale factory production.

[0005] Developing an innovative technical solution that can synergistically address the needs of red mud resource utilization, CO2 utilization at cement kiln tail, and low-cost, high-efficiency maintenance of PC components, while being simple in process and easy to implement industrially, has become an urgent technical problem for researchers in this field. Summary of the Invention

[0006] The purpose of this invention is to provide a solid waste-based carbon-fixing concrete component and its preparation method, and to utilize cement kiln tail gas for curing the concrete component, thereby achieving synergistic development of carbonization and hydration.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] The first aspect of this invention discloses a solid waste-based carbon sequestration concrete component, comprising the following raw materials: a novel carbon sequestration adhesive of 320-380 kg / m³. 3 , sand 750~800kg / m 3 Gravel: 1010-1060 kg / m³ 3 Water content: 144–159.6 kg / m³ 3 Water-reducing agent 0.48~0.57kg / m³ 3 Early strength agent: 1.6–1.9 kg / m² 3 Carbonizing agent 25.6~30.4kg / m 3 .

[0009] In some embodiments of the present invention, the novel carbon-fixing adhesive comprises 2-5 wt% gypsum, 60-80 wt% clinker, and 15-38 wt% calcined solid waste.

[0010] In some embodiments of the present invention, the clinker is silicate microparticle special cement clinker with a specific surface area ≥320 kg / m². 3 ;

[0011] Preferably, the clinker contains 55-60 wt% tricalcium silicate, 5%-18 wt% dicalcium silicate, 7-10 wt% tricalcium aluminate, and 10-12 wt% tetracalcium aluminoferrite.

[0012] The silicate microparticle special cement clinker adopts ion activation technology, which not only increases the content of tricalcium silicate in the clinker, but also makes its hydration activity higher, its early strength development faster, and its early strength effect obvious.

[0013] In some embodiments of the present invention, the calcined solid waste contains a large amount of active silica and γ-C2S, wherein the γ-C2S content is 10-15 wt%. γ-C2S has poor hydration activity but exhibits high carbonization activity.

[0014] Preferably, the calcined solid waste is made from low-grade limestone, red mud, and waste soil, calcined at 800-900℃.

[0015] The low-grade limestone has a CaO content ≤45wt%. The red mud contains 39-47wt% CaO, 20-25wt% SiO2, and 8-12wt% Al2O3, preferably 10wt%. The waste soil is construction waste, mainly composed of SiO2, with a content of approximately 35-45wt%, preferably 40wt%.

[0016] Preferably, the proportions of low-grade limestone, red mud, and waste soil are determined by three ratio values: KH = 0.41–0.44; SM = 1.33–1.39; IM = 0.85–0.89.

[0017] In some embodiments of the present invention, the sand is manufactured sand with a particle size range of 0.075 to 2.36 mm and a fineness modulus of 3.34.

[0018] In some embodiments of the present invention, the stones meet the requirements of 5-20mm continuously graded crushed stone and have a mud content of ≤1.5wt%.

[0019] In some embodiments of the present invention, the water-reducing agent is Sika 540P polycarboxylate high-performance water-reducing agent.

[0020] In some embodiments of the present invention, the early-strength agent is obtained by compounding a CSH seed-type early-strength agent and calcium formate at a mass ratio of 2:0.5-1.2, preferably 2:1. The CSH seed-type early-strength agent mainly provides nucleation sites for the CSH gel produced by cement hydration, accelerates the cement hydration process, improves early strength, and does not affect the later performance of concrete. Calcium formate can accelerate the hydration rate of tricalcium silicate, ensuring the concentration of calcium ions in the liquid phase. The compounding of the two promotes each other, greatly enhancing the early-strength effect of the early-strength agent.

[0021] In some embodiments of the present invention, the carbonizing agent is a modified mineral admixture, which includes at least one of limestone powder, fly ash, steel slag, and manganese slag.

[0022] Preferably, the method for modifying mineral admixtures includes the following steps: soaking the mineral admixtures in a saturated limewater solution, introducing carbon dioxide under heating and stirring conditions, and then drying to obtain the modified mineral admixtures;

[0023] Preferably, the mass ratio of the mineral admixture to the saturated lime water solution is 1:0.8 to 1.2, more preferably 1:1;

[0024] Preferably, the heating temperature is 85–95°C, more preferably 90°C;

[0025] Preferably, the carbon dioxide introduction rate is 1-4 L / min, more preferably 2 L / min, and the introduction time is 15-60 min, more preferably 30 min.

[0026] A second aspect of the present invention provides a method for preparing the above-mentioned solid waste-based carbon sequestration component concrete, comprising the following steps:

[0027] S1. Molding: Prepare the raw materials according to the proportion, mix the new carbon-fixing adhesive, water, sand and gravel evenly, add water-reducing agent, early strength agent and carbonizing agent and stir to obtain concrete mixture, pour, and vibrate to form;

[0028] S2. Curing: Place the mold in a standard curing chamber for curing, and then demold;

[0029] S3. Carbonization and carbon fixation: First, the kiln tail flue gas is used for normal pressure curing, and then the pressure is increased for pressurized curing to obtain the solid waste-based carbon-fixed component concrete.

[0030] In some embodiments of the present invention, the CO2 concentration of the kiln tail flue gas is 10-30 vol%, the temperature is 70-100℃, and the humidity is 40-80%.

[0031] Preferably, the curing time under normal pressure is 2–4 hours;

[0032] Preferably, the pressure for pressure curing is 0.3–0.6 MPa, and the curing time is 8–12 hours.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] This invention, with its scientific design and ingenious conception, provides a solid waste-based carbon sequestration concrete component and its preparation method. This invention comprehensively utilizes various solid wastes to replace a portion of cement clinker, and through optimized calcination processes, the introduction of surface-modified admixtures, the selection of special cement clinker, and the use of composite early-strength agents, it significantly reduces carbon emissions from cement production while substantially enhancing the carbon sequestration capacity of cement concrete. Furthermore, this invention utilizes cement kiln tail gas for carbonization curing of the solid waste-based concrete, achieving the dual goals of solid waste resource utilization and low-cost carbon sequestration, providing an effective technical path for the cement concrete industry to implement relevant policies.

[0035] (1) This invention uses a combination of various solid wastes and prepares alternative materials through a low-temperature calcination process, which can replace 15% to 38% of cement clinker. This effectively reduces the amount of clinker used, indirectly reducing carbon emissions in the cement concrete industry, which is in line with national policies. At the same time, by reasonably controlling the three ratios of calcined solid waste, a certain amount of carbonization-active γ-C2S is generated while ensuring its activity. Adding γ-C2S to cement can significantly improve the carbon sequestration capacity of cement concrete and broaden the technical approach for carbon dioxide utilization and storage.

[0036] (2) This invention utilizes low-activity mineral admixtures to prepare carbonation agents, further enhancing the carbon fixation performance of concrete. Specifically, the mineral admixtures are immersed in a saturated limewater solution, and carbon dioxide is continuously introduced under water bath heating conditions, causing nano-calcium carbonate to form on their surface. These nano-calcium carbonate particles can serve as nucleation sites for subsequent concrete carbonation reactions, promoting the carbonation process.

[0037] (3) The cement clinker used in the solid waste-based carbon fixation component concrete of the present invention is silicate microparticle special cement clinker. This cement clinker adopts ion activation technology, which not only increases the content of tricalcium silicate in the clinker, but also significantly enhances its hydration activity, giving the cement the advantages of rapid early strength development and outstanding early strength effect.

[0038] (4) This invention uses a combination of CSH seed crystal early strength agent and calcium formate as a novel early strength agent. This combination effectively compensates for the shortcomings of traditional early strength agents that may inhibit the later strength development of concrete, while achieving a better early strength effect.

[0039] (5) This invention utilizes a large amount of solid waste to prepare concrete and uses the flue gas emitted from the cement kiln tail to perform carbonization curing. On the one hand, it realizes the large-scale resource reuse of solid waste, and on the other hand, it significantly reduces the cost of concrete carbonization curing, forming a synergistic benefit of resource recycling and carbon emission reduction. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0041] The clinker described in this embodiment of the invention is silicate microparticle special cement clinker with a specific surface area ≥320 kg / m². 3 Provided by Jiahua Special Cement Co., Ltd.

[0042] In the clinker of this invention, the content of tricalcium silicate is 55-60 wt%, the content of dicalcium silicate is 5%-18 wt%, the content of tricalcium aluminate is 7-10 wt%, and the content of tetracalcium aluminoferrite is 10-12 wt%.

[0043] The stones described in this embodiment of the invention meet the requirements of 5-20mm continuous gradation crushed stone and have a mud content of ≤1.5wt%.

[0044] In this embodiment of the invention, the low-grade limestone has a CaO content of ≤45wt%; the red mud has a CaO content of 39-47wt%, a SiO2 content of 20-25wt%, and an Al2O3 content of 8-12wt%; the waste soil is construction waste soil, the main component of which is SiO2, with a content of approximately 35-45wt%.

[0045] The sand described in this embodiment of the invention is manufactured sand with a particle size range of 0.075 to 2.36 mm and a fineness modulus of 3.34.

[0046] The stones described in this embodiment of the invention meet the requirements of 5-20mm continuous gradation crushed stone and have a mud content of ≤1.5%.

[0047] The water-reducing agent described in this embodiment of the invention is Sika 540P polycarboxylate high-performance water-reducing agent, a white powder with high water reduction rate and high plasticity retention.

[0048] The CSH seed-type early strength agent in this embodiment of the invention was commercially available.

[0049] Example 1

[0050] This embodiment discloses the solid waste-based carbon sequestration component concrete of the present invention, the raw material composition of which is as follows:

[0051] New type of carbon-fixing adhesive material 320kg / m 3 , sand 800kg / m 3 1060 kg / m³ of gravel 3 Water 144kg / m 3 Water-reducing agent 0.48 kg / m³ 3 Early strength agent 1.6kg / m 3 Carbonizing agent 25.6 kg / m 3 .

[0052] The raw material composition of the novel carbon-fixing adhesive in this embodiment is as follows: 5 wt% gypsum, 80 wt% clinker, and 15 wt% calcined solid waste.

[0053] In some embodiments of the present invention, the calcined solid waste contains 15 wt% γ-C2S.

[0054] The calcined solid waste is produced by calcining low-grade limestone, red mud, and waste soil at 850℃. The calcination process is as follows: the high-temperature furnace temperature is set at 850℃, the heating rate is 20℃ / min, the holding time is 45min, and finally, the furnace is cooled to room temperature. After grinding, the calcined solid waste is obtained, and the grinding fineness is controlled so that the residue on a 45μm square-hole sieve is no more than 45%.

[0055] The proportions of low-grade limestone, red mud, and waste soil are determined by the three ratios. In this embodiment, the three ratios are KH = 0.41, SM = 1.33, and IM = 0.89.

[0056] In this embodiment, the early strength agent is a mixture of CSH seed-type early strength agent and calcium formate at a mass ratio of 2:1.

[0057] In this embodiment, the carbonizing agent is modified steel slag. The modification method is as follows: the steel slag is immersed in a saturated limewater solution at a mass ratio of 1:1; the mixture is stirred continuously until homogeneous, and heated in a 90°C water bath while carbon dioxide is introduced at a rate of 2 L / min for 30 minutes. After completion, the mixture is dried in a vacuum drying oven to obtain the modified mineral admixture.

[0058] The preparation method of solid waste-based carbon sequestration component concrete in this embodiment is as follows:

[0059] S1. Molding: Prepare the raw materials according to the proportion, mix the new carbon-fixing adhesive, water, sand and gravel evenly, add water-reducing agent, early strength agent and carbonizing agent and stir to obtain concrete mixture, pour, and vibrate to form;

[0060] S2. Curing: Place the mold in a standard curing chamber and cure at 20-25℃ for 24 hours. Then remove it and demold.

[0061] S3. Carbonation and Carbon Fixation: The concrete is transferred into a reaction vessel equipped with an inlet valve and an outlet valve for vacuum treatment; then, kiln tail gas is continuously introduced until the pressure inside the reaction vessel reaches atmospheric pressure; the outlet valve is opened, and kiln tail gas is continued to be introduced, forming circulating kiln tail gas in the reaction vessel, and atmospheric pressure curing is carried out for 2 hours; the outlet valve is closed, and kiln tail gas is continued to be introduced until the pressure inside the carbonization kettle is 0.3 MPa, and then pressure curing is carried out in a closed reaction environment for 12 hours to obtain the solid waste-based carbon fixation component concrete.

[0062] The CO2 concentration of the kiln tail flue gas is 30 vol%, the temperature is 95-100℃, and the humidity is 80%.

[0063] Example 2

[0064] This embodiment discloses the solid waste-based carbon sequestration component concrete of the present invention, the raw material composition of which is as follows:

[0065] New type of carbon-fixing adhesive material 350kg / m 3 776 kg / m³ of sand 3 1036 kg / m³ of gravel 3 Water 150.5 kg / m 3 Water-reducing agent 0.38kg / m 3 Early strength agent 1.75 kg / m 3 Carbonizing agent 28kg / m 3 .

[0066] The raw material composition of the novel carbon-fixing adhesive in this embodiment is as follows: 2 wt% gypsum, 60 wt% clinker, and 38 wt% calcined solid waste.

[0067] In some embodiments of the present invention, the calcined solid waste contains 10 wt% γ-C2S.

[0068] The calcined solid waste is produced by calcining low-grade limestone, red mud, and waste soil at 800℃. The calcination process is as follows: the high-temperature furnace temperature is set at 800℃, the heating rate is 20℃ / min, the holding time is 60min, and finally, the furnace is cooled to room temperature. After grinding, the calcined solid waste is obtained, and the grinding fineness is controlled so that the residue on a 45μm square-hole sieve is no more than 45%.

[0069] The proportions of low-grade limestone, red mud, and waste soil are determined by the three ratios. In this embodiment, the three ratios are KH = 0.44, SM = 1.39, and IM = 0.85.

[0070] In this embodiment, the early strength agent is a mixture of CSH seed-type early strength agent and calcium formate at a mass ratio of 2:1.2.

[0071] In this embodiment, the carbonizing agent is modified manganese slag. The modification method is as follows: the manganese slag is soaked in a saturated limewater solution at a mass ratio of 1:1.2; the mixture is stirred continuously until homogeneous, and heated in a water bath at a constant temperature of 85°C. Carbon dioxide is introduced during the process at a rate of 4 L / min for 15 minutes. After completion, the mixture is dried in a vacuum drying oven to obtain the modified mineral admixture.

[0072] The preparation method of solid waste-based carbon sequestration component concrete in this embodiment is as follows:

[0073] S1. Molding: Prepare the raw materials according to the proportion, mix the new carbon-fixing adhesive, water, sand and gravel evenly, add water-reducing agent, early strength agent and carbonizing agent and stir to obtain concrete mixture, pour, and vibrate to form;

[0074] S2. Curing: Place the mold in a standard curing chamber and cure at 20-25℃ for 24 hours. Then remove it and demold.

[0075] S3. Carbonation and Carbon Fixation: The concrete is transferred into a reaction vessel equipped with an inlet valve and an outlet valve for vacuum treatment; then, kiln tail gas is continuously introduced until the pressure inside the reaction vessel reaches atmospheric pressure; the outlet valve is opened, and kiln tail gas is continued to be introduced, forming circulating kiln tail gas in the reaction vessel, and atmospheric pressure curing is carried out for 4 hours; the outlet valve is closed, and kiln tail gas is continued to be introduced until the pressure inside the carbonization kettle is 0.6 MPa, and then pressure curing is carried out in a closed reaction environment for 8 hours to obtain the solid waste-based carbon fixation component concrete.

[0076] The CO2 concentration of the kiln tail flue gas is 10 vol%, the temperature is 70-75℃, and the humidity is 60%.

[0077] Example 3

[0078] This embodiment discloses the solid waste-based carbon sequestration component concrete of the present invention, the raw material composition of which is as follows:

[0079] New type of carbon-fixing adhesive material 380kg / m 3 750kg / m³ of sand 3 1010 kg / m³ of gravel 3 Water 159.6 kg / m 3 Water-reducing agent 0.57 kg / m³ 3 Early strength agent 1.9 kg / m 3 Carbonizing agent 30.4 kg / m 3 .

[0080] The raw material composition of the novel carbon-fixing adhesive in this embodiment is as follows: 4 wt% gypsum, 70 wt% clinker, and 26 wt% calcined solid waste.

[0081] In some embodiments of the present invention, the calcined solid waste contains 12 wt% γ-C2S.

[0082] The calcined solid waste is produced by calcining low-grade limestone, red mud, and waste soil at 900℃. The calcination process is as follows: the high-temperature furnace temperature is set at 900℃, the heating rate is 20℃ / min, the holding time is 30min, and finally, the furnace is cooled to room temperature. After grinding, the calcined solid waste is obtained, and the grinding fineness is controlled so that the residue on a 45μm square-hole sieve is no more than 45%.

[0083] The proportions of low-grade limestone, red mud, and waste soil are determined by the three ratios. In this embodiment, the three ratios are KH = 0.43, SM = 1.35, and IM = 0.87.

[0084] In this embodiment, the early strength agent is prepared by mixing CSH seed-type early strength agent and calcium formate at a mass ratio of 2:0.8.

[0085] In this embodiment, the carbonizing agent is modified fly ash. The modification method is as follows: fly ash is soaked in a saturated limewater solution at a mass ratio of 1:0.8; the mixture is stirred continuously until homogeneous, and heated in a 95°C water bath while carbon dioxide is introduced at a rate of 1 L / min for 60 minutes. After completion, the mixture is dried in a vacuum drying oven to obtain the modified mineral admixture.

[0086] The preparation method of solid waste-based carbon sequestration component concrete in this embodiment is as follows:

[0087] S1. Molding: Prepare the raw materials according to the proportion, mix the new carbon-fixing adhesive, water, sand and gravel evenly, add water-reducing agent, early strength agent and carbonizing agent and stir to obtain concrete mixture, pour, and vibrate to form;

[0088] S2. Curing: Place the mold in a standard curing chamber and cure at 20-25℃ for 24 hours. Then remove it and demold.

[0089] S3. Carbonation and Carbon Fixation: The concrete is transferred into a reaction vessel equipped with an inlet valve and an outlet valve for vacuum treatment; then, kiln tail gas is continuously introduced until the pressure inside the reaction vessel reaches atmospheric pressure; the outlet valve is opened, and kiln tail gas is continued to be introduced, forming circulating kiln tail gas in the reaction vessel, and atmospheric pressure curing is carried out for 3 hours; the outlet valve is closed, and kiln tail gas is continued to be introduced until the pressure inside the carbonization kettle is 0.4 MPa, and then pressure curing is carried out in a closed reaction environment for 10 hours to obtain the solid waste-based carbon fixation component concrete.

[0090] The CO2 concentration of the kiln tail flue gas is 20 vol%, the temperature is 85-90℃, and the humidity is 40%.

[0091] Comparative Example 1

[0092] Compared with Example 3, Comparative Example 1 uses ordinary 42.5R cement (provided by Sichuan Esheng Cement Co., Ltd.) instead of the new carbon-fixing adhesive, while all other conditions are the same.

[0093] Comparative Example 2

[0094] Compared with Example 3, Comparative Example 2 uses calcium formate as the early strength agent, while all other conditions are the same.

[0095] Comparative Example 3

[0096] Compared with Example 3, no carbonizing agent was added in Comparative Example 3, but all other conditions were the same.

[0097] Test case

[0098] The compressive strength of the solid waste-based carbon-fixing concrete components prepared in Examples 1-3 and Comparative Examples 1-3 was tested. The testing method was carried out in accordance with the national standard GB / T50081-2019 "Standard for Test Methods of Physical and Mechanical Properties of Concrete". The results are shown in Table 1.

[0099] In addition, the compressive strength of solid waste-based carbonized component concrete (i.e. concrete cured in step S2) before carbonization in Examples 1-3 and Comparative Examples 1-3 was tested using the same method, and the results are shown in Table 1.

[0100] The test blocks, after undergoing the compressive strength test, were placed in an oven and dried at 105℃ for 12 hours. They were weighed every half hour until the error between two consecutive weighings was ≤5%. Finally, the dried test blocks were subjected to thermogravimetric analysis. The carbon sequestration of the concrete was characterized by the change in the mass of the test blocks between 600℃ and 800℃. The results are shown in Table 1.

[0101] Table 1. Test results of compressive strength and carbon fixation content

[0102] serial number Compressive strength / MPa (before carbonization) Compressive strength / MPa (after carbonization) Carbon sequestration (g / kg) Example 1 17.5 23.6 89.1 Example 2 18.6 25.1 95.3 Example 3 21.5 26.7 101.9 Comparative Example 1 24.7 25.4 42.1 Comparative Example 2 19.9 23.1 99.1 Comparative Example 3 20.3 22.1 49.6

[0103] As shown in the table above, the concrete strength of the solid waste-based carbon fixation component of the present invention meets the concrete strength requirements of PC components. Furthermore, with the increase of the amount of carbon fixation adhesive, the compressive strength of the concrete gradually increases, and the carbon fixation capacity also gradually strengthens.

[0104] Comparing the data of Example 3 and Comparative Example 1, it can be seen that although the concrete strength of the novel carbon-fixing cementitious material of the present invention is lower than that of ordinary cement under standard curing, the concrete strength of the novel carbon-fixing cementitious material is improved after carbonization curing, and is basically equivalent to that of ordinary cement concrete. Furthermore, the carbon fixation amount of Comparative Example 1 is the lowest (42.1 g / kg), indicating that the novel carbon-fixing cementitious material of the present invention is crucial to the carbon fixation ability.

[0105] Comparing the data of Example 3 and Comparative Example 2, it can be seen that the early strength effect of the CSH seed crystal early strength agent combined with calcium formate in this invention is higher than that of calcium formate.

[0106] Comparing the data of Example 3 and Comparative Example 3, it can be seen that the concrete has a stronger carbon fixation ability after adding carbonizing agent.

[0107] Finally, it should be noted that the above embodiments are merely preferred embodiments of the present invention used to illustrate the technical solutions of the present invention, and are not intended to limit the invention, nor are they intended to limit the patent scope of the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention. That is to say, any changes or refinements made to the main design concept and spirit of the present invention that are not of substantial significance, but whose technical problems are still consistent with the present invention, should be included within the protection scope of the present invention. In addition, the direct or indirect application of the technical solutions of the present invention to other related technical fields are similarly included within the patent protection scope of the present invention.

Claims

1. A solid waste-based carbon sequestration component concrete, characterized in that, Including the following raw materials: New type of carbon-fixing adhesive 320~380kg / m 3 , sand 750~800kg / m 3 Gravel: 1010-1060 kg / m³ 3 Water content: 144–159.6 kg / m³ 3 Water-reducing agent 0.48~0.57kg / m³ 3 Early strength agent: 1.6–1.9 kg / m² 3 Carbonizing agent 25.6~30.4kg / m 3 .

2. The solid waste-based carbon sequestration component concrete according to claim 1, characterized in that, The novel carbon-fixing adhesive comprises 2-5 wt% gypsum, 60-80 wt% clinker, and 15-38 wt% calcined solid waste.

3. The solid waste-based carbon sequestration component concrete according to claim 2, characterized in that, The clinker is a silicate microparticle special cement clinker. Preferably, the clinker contains 55-60 wt% tricalcium silicate, 5%-18 wt% dicalcium silicate, 7-10 wt% tricalcium aluminate, and 10-12 wt% tetracalcium aluminoferrite. The γ-C2S content in the calcined solid waste is approximately 10–15 wt%. Preferably, the calcined solid waste is made from low-grade limestone, red mud, and waste soil, calcined at 800-900℃. Preferably, the proportions of low-grade limestone, red mud, and waste soil are determined by three ratio values: KH = 0.41–0.44; SM = 1.33–1.39; IM = 0.85–0.

89.

4. The solid waste-based carbon sequestration component concrete according to claim 1, characterized in that, The sand is manufactured sand with a particle size range of 0.075–2.36 mm and a fineness modulus of 3.

34.

5. The solid waste-based carbon sequestration component concrete according to claim 1, characterized in that, The stones are 5-20mm continuously graded crushed stone with a mud content of ≤1.5wt%.

6. The solid waste-based carbon sequestration component concrete according to claim 1, characterized in that, The water-reducing agent is Sika 540P polycarboxylate high-performance water-reducing agent.

7. The solid waste-based carbon sequestration component concrete according to claim 1, characterized in that, The early strength agent is obtained by compounding CSH seed-type early strength agent and calcium formate in a mass ratio of 2:0.5-1.2, preferably 2:

1.

8. The solid waste-based carbon sequestration component concrete according to claim 1, characterized in that, The carbonizing agent is a modified mineral admixture, which includes at least one of limestone powder, fly ash, steel slag, and manganese slag. Preferably, the method for modifying mineral admixtures includes the following steps: soaking the mineral admixtures in a saturated limewater solution, introducing carbon dioxide under heating and stirring conditions, and then drying to obtain the modified mineral admixtures; Preferably, the mass ratio of the mineral admixture to the saturated lime water solution is 1:0.8 to 1.2, more preferably 1:1; Preferably, the heating temperature is 85–95°C, more preferably 90°C; Preferably, the carbon dioxide introduction rate is 1-4 L / min, more preferably 2 L / min, and the introduction time is 15-60 min, more preferably 30 min.

9. A method for preparing solid waste-based carbon sequestration concrete according to any one of claims 1 to 8, characterized in that, Includes the following steps: S1. Molding: Prepare the raw materials according to the proportion, mix the new carbon-fixing adhesive, water, sand and gravel evenly, add water-reducing agent, early strength agent and carbonizing agent and stir to obtain concrete mixture, pour, and vibrate to form; S2. Curing: Place the mold in a standard curing chamber for curing, and then demold; S3. Carbonization and carbon fixation: First, the kiln tail flue gas is used for normal pressure curing, and then the pressure is increased for pressurized curing to obtain the solid waste-based carbon-fixed component concrete.

10. The method for preparing solid waste-based carbon sequestration concrete according to claim 9, characterized in that, The CO2 concentration of the kiln tail flue gas is 10-30 vol%, the temperature is 70-100℃, and the humidity is 40-80%. Preferably, the curing time under normal pressure is 2–4 hours; Preferably, the pressure for pressure curing is 0.3–0.6 MPa, and the curing time is 8–12 hours.