A high-carbon sequestration high-connection magnesium slag-steel slag-based artificial aggregate, pre-paved aggregate concrete and a preparation method thereof

Abstract

This invention relates to the field of industrial solid waste resource utilization, specifically to a high-carbon-solidification, highly interconnected magnesium slag-steel slag-based artificial aggregate, pre-laid aggregate concrete, and their preparation methods. The artificial aggregate comprises magnesium slag-steel slag composite powder pre-treated by two stages of carbonation mechanical grinding and suspended microbial carbonization, a pore structure regulator, reinforcing components, a hydration accelerator, and mixing water. The core of this invention lies in: 1) using a two-stage pre-treatment process of carbonation mechanical grinding and suspended microbial carbonization to deeply activate the slag material; 2) using the activated slag material as the main raw material, introducing pore structure regulator components, and combining hydrothermal evaporation dehydration and pressure carbonization strengthening to prepare artificial aggregate with a highly interconnected pore network and high reactivity; 3) using a pre-laid aggregate molding process to prepare concrete, leveraging the advantages of highly interconnected aggregate to obtain concrete products with both good mechanical properties and high carbon sequestration capacity.

Description

Technical Field

[0001] This invention relates to the field of industrial solid waste resource utilization and low-carbon building materials technology, specifically to a method for preparing high-carbon, highly interconnected artificial aggregates and concrete through carbonation mechanical grinding, suspended microbial carbonization, hydrothermal evaporation dehydration and pore-forming, and pre-laying aggregate processes. Background Technology

[0002] Magnesium slag and steel slag are rich in active calcium and magnesium oxides, possessing theoretically high carbonization potential. Utilizing industrial solid wastes such as magnesium slag and steel slag to prepare carbonizable cementitious materials or aggregates, and then producing building materials through carbon dioxide mineralization and sequestration technology, is an effective pathway to achieve "carbon capture, utilization, and storage."

[0003] However, in practical applications, both materials face key bottlenecks: First, the early carbonation efficiency of the raw materials is low. In traditional carbonation processes, a dense carbonate coating layer easily forms on the surface of magnesium slag and steel slag, hindering CO2 diffusion and ion dissolution, leading to premature termination of the carbonation reaction and low carbon fixation efficiency. Second, the pore network connectivity of the finished product is poor. When these solid wastes are prepared into artificial aggregates, it is difficult to construct an efficient and interconnected pore network, resulting in the inability to form effective CO2 transport channels in concrete. When carbonized concrete is prepared using ordinary mixing processes, poor pore connectivity leads to insufficient CO2 diffusion paths, resulting in limited carbonation depth, uneven structure, and limited improvement in the overall performance of the concrete.

[0004] Existing technologies are mostly limited to small products such as bricks, making them difficult to apply to large components. Furthermore, the carbon capture capacity is generally only 35-120 kg / m³, which severely restricts the large-scale application of solid waste-based carbonized concrete. On the other hand, existing pre-activation methods (such as simple mechanical grinding or ordinary carbonization) are difficult to effectively break through the product coating layer; conventional mixing processes also cannot build an orderly CO2 transport channel, which restricts the overall carbonization effect of concrete.

[0005] Therefore, there is an urgent need for a complete solution that covers the entire process from deep activation of raw materials, aggregate structure design, and macroscopic structural control of concrete. Summary of the Invention

[0006] This invention aims to overcome the shortcomings of existing technologies and provide a systematic approach to preparing high-carbon, highly interconnected concrete using industrial solid wastes such as magnesium slag and steel slag. 1) A two-stage pretreatment process of carbonation mechanical grinding and suspended microbial carbonization is used to deeply activate the slag material; 2) Using the activated slag material as the main raw material, pore structure regulating components are introduced, combined with hydrothermal evaporation dehydration and pressurized carbonization strengthening, to prepare artificial aggregates with a highly interconnected pore network and high reactivity; 3) A pre-laid aggregate molding process is used to prepare concrete, leveraging the advantages of highly interconnected aggregates to obtain concrete products with both good mechanical properties and high carbon sequestration capacity.

[0007] A second objective of this invention is to provide a pre-laid aggregate concrete prepared from the aforementioned high-carbon, high-connectivity magnesium slag-steel slag-based artificial aggregate. This concrete uses the aforementioned high-carbon, high-connectivity magnesium slag-steel slag-based artificial aggregate as coarse aggregate and fills its pores with a specific proportion of cementitious paste.

[0008] On the one hand, the present invention provides a high carbon-solidified and highly interconnected magnesium slag-steel slag-based artificial aggregate, comprising the following raw materials: dry aggregate basis: magnesium slag-steel slag composite powder after two-stage pretreatment of carbonation mechanical grinding and suspension microbial carbonization, pore structure regulator, and reinforcing component; water agent: first hydration accelerator and first mixing water.

[0009] Based on the dry weight percentage of the aggregate, the raw material composition is as follows: magnesium slag-steel slag composite powder after two-stage pretreatment: 75%~95%; silica fume as a pore structure regulator: 2%~15%; sulfoaluminate cement as a reinforcing component: 3%~10%; first hydration accelerator: 0.01%~0.1%; mixing water: with a mass ratio of water to the total mass of the above solids of 0.30~0.50; the first hydration accelerator is at least one of triethanolamine and triethanolamine-gallate. In a second aspect, the present invention provides a pre-laid aggregate concrete based on high-carbon, high-connectivity magnesium slag-steel slag-based artificial aggregate, comprising the above-mentioned high-carbon, high-connectivity magnesium slag-steel slag-based artificial aggregate coarse aggregate and cementitious paste. Magnesium slag-steel slag based artificial aggregate coarse aggregate accounts for 40% to 60% of the total volume of concrete.

[0010] The cementitious slurry comprises a cementitious dry base, a second mixing water, and admixtures, with a water-cement ratio of 0.25~0.35. The cementitious dry base, by mass fraction, includes: a mixture of magnesium slag and steel slag: 60%~80%; sulfoaluminate cement: 15%~25%; and silica fume: 5%~15%. Additives include a water-retaining agent and a second hydration accelerator; the water-retaining agent is hydroxypropyl methylcellulose ether; the second hydration accelerator is at least one of triethanolamine and triethanolamine-gallate; the total amount of additives is 0.5% to 1.5% of the total mass of the gel.

[0011] Thirdly, embodiments of the present invention provide a method for preparing the above-mentioned pre-laid aggregate concrete, the specific steps of which are as follows: S1 magnesium slag-steel slag mixture carbonation mechanical grinding Magnesium slag and steel slag are mixed at a predetermined mass ratio to obtain an initial mixture. A portion of the first hydration accelerator (triethanolamine or its derivative) is dissolved in the first mixing water and added to the ball mill along with the mixed slag at a solid-liquid mass ratio of 1:1. Simultaneously, a mixed gas of CO2 and N2 is continuously introduced into the ball mill, with a CO2 volume concentration of 15-20% and a gas flow rate controlled at 10-20 mL / min per gram of slag. Stainless steel or zirconia balls with a diameter of 3 mm are used as the grinding media, with a ball-to-material ratio (mass ratio of grinding media to the magnesium slag-steel slag mixture) set at 1:1. The ball mill speed is controlled at 400-600 r / min, and the grinding and carbonation reaction is carried out continuously for 15-30 minutes. During this process, triethanolamine or its derivative acts as a grinding aid and CO2 absorbent, effectively reducing slag powder agglomeration and improving grinding efficiency. Simultaneously, its amine groups absorb and fix CO2, providing an internal carbon source precursor for the subsequent S2 suspended microbial carbonization step. Mechanical grinding continuously exposes the surface of newly formed particles, and the immediate introduction of CO2 induces preliminary carbonation of the slag, generating loose initial carbonate products. This inhibits the subsequent formation of a dense passivation layer and improves the conversion rate of the steel slag-magnesium slag mixture into a highly active auxiliary cementitious material. After the reaction is complete, the mixed slurry is discharged.

[0012] Suspended microbial carbonization of S2 magnesium slag-steel slag mixture The slurry containing magnesium slag-steel slag mixed powder, treated with S1, is stirred evenly with a carbonic anhydrase-producing bacterial solution to form a moist pretreated material. The water-to-solid mass ratio of the pretreated material is 1.5:1. The bacterial solution is preferably a suspension of one or more of Bacillus subtilis, Bacillus safoetida, or Bacillus pasteurellii. The pretreated material is placed in a pneumatically driven suspension carbonization reactor capable of airflow fluidization. A grate cooler temperature control device is used to maintain a constant temperature of 30±5℃ (this temperature range is beneficial for maintaining the activity of carbonic anhydrase in the bacterial strain). Under this constant temperature condition, a mixture of CO2 and N2 gas is introduced into the reactor. The CO2 gas is industrial-grade or food-grade CO2 with a volume concentration of not less than 20%, and the gas flow rate is controlled at 0.05-0.2 L·min. - ¹, at a relative humidity of 90%, a microbial-catalyzed suspension carbonization reaction was carried out for 5-15 minutes. During this process, the intermediate formed from triethanolamine or its derivatives from step S1, acting as an internal carbon source, decomposed and released CO2 under the microbial environment and temperature and humidity conditions. This CO2 synergistically combined with externally introduced CO2 to enhance the local carbonization microenvironment. Carbonic anhydrase in the bacterial solution efficiently promoted the carbonization transformation of mineral phases in steel slag-magnesium slag, inducing carbonation erosion and mineral deposition on the particle surface. Simultaneously, the microorganisms adsorbed Ca²⁺ through their cell walls. +It also provides nucleation sites, accelerating carbonate crystal growth. Under isothermal and fluidized conditions, the powder particles are in a highly dispersed suspension state, increasing the contact probability and interfacial area between the particles and CO2, thus improving the carbonization efficiency of the reaction process. After the reaction, the suspended solids are collected by centrifugation and dried to obtain a pretreated composite powder with high reactivity.

[0013] Preparation of S3 Magnesium Slag-Steel Slag Based Artificial Aggregate Using the pretreated magnesium slag-steel slag composite powder obtained from S2 as the main raw material, silica fume (pore structure regulator) and sulfoaluminate cement (reinforcing component) are added according to the specified ratio and dry-mixed evenly. Subsequently, the remaining first hydration accelerator (triethanolamine or its derivative) is dissolved in the first mixing water and added to the above-mentioned dry mixture at a water-to-solid ratio of 0.3~0.5. The mixture is then formed into raw meal granules by disc granulation or extrusion granulation. The raw meal granules are subjected to hydrothermal evaporation dehydration treatment at 105℃ to rapidly evaporate the internal moisture of the aggregate, forming an interconnected initial pore channel network. Subsequently, the dehydrated aggregate is placed in an autoclave at 0.2-0.4MPa and a CO2 concentration of 99.9% for pressurized carbonization curing for 10-14 hours. During this process, CO2 diffuses rapidly along the initial pores under pressure, reacting with the active substances inside the aggregate. The carbonization products further fill and strengthen the pore walls, ultimately forming a highly interconnected magnesium slag-steel slag-based artificial aggregate with a high pore connectivity coefficient (up to 75% or more) and high carbonization reactivity. The pore connectivity coefficient of the aforementioned magnesium slag-steel slag-based artificial aggregate is significantly higher than that of solid waste aggregates prepared by conventional sintering or cold bonding methods (typically below 50%).

[0014] Preparation of S4 precast aggregate concrete A pre-laid aggregate molding process is employed, using artificial aggregate prepared from S3 as coarse aggregate. This coarse aggregate is pre-filled tightly into molds at a volume fraction of 40%-60%, and compacted through moderate vibration to form a stable, rigid skeleton with interconnected internal voids. Subsequently, magnesium slag, steel slag, silica fume, and sulfoaluminate cement are dry-mixed uniformly according to the cementitious slurry mix ratio. A solution containing a water-retaining agent and a second hydration accelerator is then added along with the second mixing water, and the mixture is stirred to produce a highly fluid cementitious slurry. This slurry is injected into the pre-filled aggregate skeleton using low-pressure grouting or self-leveling methods. The slurry flows and fully fills the voids in the aggregate. The water-retaining agent ensures good fluidity and water retention, while the hydration accelerator effectively alleviates the inhibition of early hydration of sulfoaluminate cement by steel slag, ensuring the normal strength development of the cementitious system within the porous network constructed by the aggregate. The resulting concrete component exhibits a three-dimensional, continuous macroporous network constructed from highly interconnected aggregates. This structure not only provides an excellent physical framework for concrete, but the high activity and connectivity of its aggregates also provide efficient CO2 diffusion channels for subsequent overall carbonation curing or natural carbonation, thereby enabling concrete to achieve rapid and uniform carbonation and significantly improve early strength and final carbon sequestration capacity.

[0015] In step S1, the mass ratio of magnesium slag to steel slag in the mixture is 1:0.5 to 1:2.

[0016] Compared with the prior art, the embodiments of the present invention have at least the following advantages or beneficial effects: A synergistic activation pathway of "physical crushing-instant carbonization-air-driven suspension-biocarbonation" was constructed through a two-stage coupling activation of carbonation-mechanical grinding and microbial catalytic suspension carbonization. First, surface carbonization is performed simultaneously with physical crushing to prevent passivation of active sites; then, air-driven suspension is used to enhance the activation process. solid Liquid multiphase mass transfer is used to achieve rapid and uniform carbonization with the help of carbonic anhydrase produced by specific strains.

[0017] By using triethanolamine or its derivatives as a key component throughout the entire process of mechanical grinding-biocarbonization-gelling and solidification, it can exert multiple synergistic effects as a grinding aid, an internal carbon source precursor, and a hydration promoter, thereby achieving efficient integration of materials, functions, and processes.

[0018] By combining hydrothermal evaporation dehydration and pore-forming with pressure carbonization for strengthening, artificial aggregates with high connectivity, high activity, and certain mechanical strength were prepared.

[0019] By constructing a three-dimensional, interconnected, and structurally stable macroporous network skeleton through pre-laid aggregate molding process, uniform carbonization is achieved inside the concrete, while taking into account both strength performance and carbon sequestration capacity. This provides a reference solution for the high-value utilization of bulk industrial solid wastes such as magnesium slag and steel slag and the preparation of low-carbon building materials. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the carbonation mechanical grinding synchronous processing device involved in the present invention.

[0022] Figure 2 This is a schematic diagram of the suspended microbial carbonization reactor used in this invention.

[0023] Figure 3 This is a flowchart illustrating the overall process flow of the present invention.

[0024] Figure 4 This is an XCT scan three-dimensional pore distribution diagram of the magnesium slag-steel slag-based artificial aggregate in Example 1 of the present invention.

[0025] Figure 5 The carbon fixation per unit of concrete specimens in the embodiments and comparative examples of this invention.

[0026] Figure 6 The 28-day compressive strength of the concrete specimens in the embodiments and comparative examples of this invention.

[0027] Figure 7 The images shown are physical pictures of magnesium slag-steel slag-based artificial aggregates used in embodiments and comparative examples of the present invention.

[0028] Icons: 1. Magnesium slag-steel slag; 2. First mixing water containing the first hydration accelerator; 3. Grinding ball; 4. Mechanical grinder; 5. Gas storage tank; 6. Blower; 7. Suspension carbonization reaction tank; 8. Heater; 9. Grate cooler temperature control equipment; 10. Recoverer. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0030] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to specific embodiments.

[0031] Example 1 As attached Figure 1-3 The pre-laid aggregate concrete is prepared according to the following steps and proportions: S1 magnesium slag-steel slag mixture carbonation mechanical grinding Magnesium slag and converter steel slag from a steel plant were dried, crushed, and mixed at a mass ratio of 1:1 to obtain a magnesium slag-steel slag mixture 1. 1000g of the above mixed slag material was weighed and added to the grinding jar of a laboratory mechanical grinder 4 along with 1000g of deionized water (containing 0.05g of triethanolamine and the first mixing water 2 containing the first hydration accelerator). 1000g of stainless steel grinding balls 3 (3mm diameter, ball-to-material mass ratio 1:1) were added to the jar. The mill speed was set to 500 r / min. After sealing the grinding jar, a gas line was connected, and a mixed gas consisting of 15% CO2 and 85% N2 (volume ratio) (located in a gas storage tank 5) was introduced. The total gas flow rate was controlled at 15 L / min (i.e., 15 mL / min / g based on the slag material). Under the condition of introducing the mixed gas, the mechanical grinder 4 was started and operated continuously for 20 minutes. During this process, triethanolamine acts as a grinding aid, improving grinding efficiency. Simultaneously, the mechanical force continuously exposes fresh surfaces of the slag, while the introduced CO2 reacts with these new surfaces to undergo preliminary carbonation, generating loose, initial carbonate products. After the reaction is complete, a mixed slurry A is obtained.

[0032] Suspended microbial carbonization of S2 magnesium slag-steel slag mixed powder Take the mixed slurry A obtained from S1, add 100g of Bacillus sabinatus bacterial solution producing carbonic anhydrase, and stir in a beaker until a uniformly moistened pretreatment material (water-to-solid mass ratio of 1.5:1) is formed. Transfer the pretreatment material to... Figure 2In the suspended microbial carbonization reactor shown, the built-in grate cooler temperature control device 9 and heater 8 are activated to stabilize the temperature inside the suspended carbonization reactor 7 at 30±5℃. A mixed gas with a concentration of 20% industrial-grade CO2 is introduced into the suspended carbonization reactor 7, with the gas flow rate controlled at 0.1 L / min and the relative humidity at 90%. Under the action of the blower 6, the airflow causes the powder particles to be in a fluidized suspension state within the reactor. The triethanolamine reacts with CO2 during the S1 carbonation mechanical grinding process to generate a carbamate intermediate. This intermediate can decompose and release CO2 under the mild conditions of suspended microbial carbonization, thereby serving as an internal carbon source to enhance the local carbonization microenvironment. After 10 minutes of reaction, rapid and uniform carbonization of the particle surface and near-surface is achieved. After the reaction is completed, the gas source is turned off, the composite material B is removed, and the unreacted carbon dioxide is recovered through the recovery device 10.

[0033] The autoclaving expansion rate of composite material B was measured to be 0.31%, which meets the requirements of GB / T 13590-2022 standard and has no risk of volume stability.

[0034] Preparation of S3 Magnesium Slag-Steel Slag Based Artificial Aggregate Using composite material B obtained from S2 as the base material, 5% silica fume (pore structure regulator) and 10% sulfoaluminate cement (reinforcing component) were added by dry weight, and the mixture was dry-mixed in a mixer for 5 minutes until homogeneous. Water pre-dissolved in residual triethanolamine was added to the above dry mixture at a water-to-solid mass ratio of 0.35, and after thorough mixing, the mixture was granulated using a disc granulator to prepare wet aggregate particles. The granulation process was controlled to ensure that the particle size of the spherical pellets after granulation ranged from 5 to 10 mm. The wet aggregate was spread evenly on a tray and placed in a 105°C forced-air drying oven for 4 hours. During this process, the internal moisture of the aggregate evaporated rapidly, forming an interconnected initial pore network. The dehydrated aggregate was then placed in a pressurized carbonization reactor. 99.9% CO2 gas was introduced into the reactor, and the pressure inside the reactor was adjusted to 0.25 MPa and maintained constant. Carbonization was carried out at room temperature (approximately 25°C) for 12 hours. Carbonation products (such as calcium carbonate) are deposited inside and on the surface of the pores, strengthening the pore wall structure. After carbonation curing, the aggregate is removed after depressurization, yielding highly interconnected magnesia slag-steel slag-based artificial aggregate C, as shown in the image. Figure 1 As shown.

[0035] A 3D high-resolution X-ray micro-imaging system was used to scan the artificial aggregate C sample. X-ray beams were generated by adjusting the electron tube voltage and current to irradiate the sample, obtaining projections of each sample from different angles. CT and 3D software were used to read the raw data, reconstruct CT images, and perform detailed model reconstruction. The pore structure of the 3D reconstruction was then analyzed, and the calculated pore connectivity coefficient (connected pore volume / aggregate volume) was 78%. Figure 4 As shown, Figure 4 a is the XCT scan image of the connected pores; Figure 4 b shows the XCT scan images of isolated pores (red) and connected pores (blue).

[0036] Preparation of S4 precast aggregate concrete Artificial aggregate C obtained from S3 was used as coarse aggregate, weighing 1100g. It was pre-filled tightly into a 100mm×100mm×100mm cubic steel mold, with the filling volume accounting for 50% of the total mold volume. It was then thoroughly vibrated on a vibrating table to form a stable, rigid skeleton. Separately, 455g of a mixture of magnesium slag and steel slag (mass ratio 1:1) powder was mixed with 58g of silica fume, 128g of sulfoaluminate cement, 205g of mixing water, 0.5% triethanolamine hydration accelerator, and 0.5% hydroxypropyl methylcellulose ether water-retaining agent. This mixture was then stirred to form a well-flowing cementitious slurry. The prepared slurry was slowly poured into the mold from the top until it completely submerged the aggregate and filled all visible voids. The slurry was lightly tamped to remove air bubbles. After standing at room temperature for 24 hours, the mold was removed, and the specimens were transferred to a standard curing room (temperature 20±2℃, relative humidity ≥95%) for curing to the specified age.

[0037] Referring to GB / T 50081-2019 "Standard for Test Methods of Mechanical Properties of Ordinary Concrete", a 100kN microcomputer-controlled electronic universal testing machine was used for testing. During the entire loading process, the load was uniformly and continuously applied at a rate of 250 N / s until the specimen failed, and the maximum failure load was recorded. A differential thermal-thermogravimetric analyzer was used. The prepared sample was placed in a crucible, and the heating range was set to 25~900℃ at a heating rate of 10℃ / min, with a nitrogen atmosphere. Three parallel specimens were used for each test, and the average value was used for performance comparison and analysis. The 28-day compressive strength of the concrete specimen was measured to be 38.7 MPa, and the carbon fixation per unit volume reached 162 kg / m³. Figure 5-6 As shown.

[0038] Example 2 The main difference between this embodiment and Embodiment 1 lies in the proportion of artificial aggregate S3 and the volume fraction of aggregate in concrete S4, as detailed below: In S3, the proportions of composite material B, regulator, and reinforcing components were adjusted as follows: composite material B accounted for 80%, silica fume for 10%, sulfoaluminate cement for 10%, and the water-to-solid ratio was 0.40. The hydrothermal evaporation dehydration and pressurized carbonation curing conditions were the same as in Example 1. The resulting artificial aggregate had a pore connectivity coefficient of 76%, as shown in the physical image. Figure 7 As shown in b.

[0039] In S4, artificial aggregate was pre-laid into the mold at a volume fraction of 60% to construct the skeleton. The composition of the cementitious paste was the same as in Example 1. The resulting concrete specimens had a 28-day compressive strength of 36.2 MPa and a carbon sequestration of 158 kg / m³. 3 ,like Figure 5-6 As shown.

[0040] Comparative Example Magnesium slag-steel slag mixed powder, which had not undergone the two-stage pretreatment of this invention (i.e., only ordinary mechanical grinding), was directly mixed and granulated with silica fume, sulfoaluminate cement, and water in the same proportions. After hydrothermal dehydration and pressurized carbonation curing under the same conditions, comparative aggregate D was prepared. A physical image is shown below. Figure 7 c. Its pore connectivity coefficient is only 48%. Using aggregate D, concrete was prepared with the same pre-laid volume fraction (50%) and cementitious paste as in Example 1. Its 28-day compressive strength was 30.5 MPa, and its carbon sequestration per unit volume was 98 kg / m³. Figure 5-6 As shown.

[0041] Effect comparison: such as Figure 5-6 As shown in the comparison of data from Examples 1 and 2 with the comparative examples, it can be seen that the two-stage pretreatment process of carbonation mechanical grinding and suspended microbial carbonization provided by this invention can significantly improve the activity of raw materials, thereby producing artificial aggregates with high pore connectivity (>75%) and good strength in subsequent processes. Using this highly connected aggregate in pre-laid aggregate concrete can construct efficient CO2 transport channels, ultimately enabling the concrete to maintain high strength while achieving a higher carbon sequestration capacity (carbon sequestration >150 kg / m³), with overall performance significantly superior to traditional methods.

[0042] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

[0043] The embodiments described above are some, but not all, embodiments of the present invention. The detailed description of the embodiments of the present invention is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

Claims

1. A high carbon sequestration high connectivity magnesium slag-steel slag based artificial aggregate, characterized in that, Includes dry aggregate: magnesium slag-steel slag composite powder pretreated by two stages of carbonation mechanical grinding and suspension microbial carbonization, pore structure regulator, and reinforcing components; Aqueous agent: First hydration accelerator, first mixing water.

2. The high carbonation high interconnectedness magnesium-slag-steel-slag-based artificial aggregate according to claim 1, characterized in that, The aggregate dry basis, by mass fraction, comprises 75%~95% magnesium slag-steel slag composite powder, 2%~15% pore structure regulator, 3%~10% reinforcing component, and 0.01-0.1% hydration accelerator by mass of the aggregate dry basis. The pore structure regulator is silica fume; the reinforcing component is sulfoaluminate cement; and the first hydration accelerator is at least one of triethanolamine and triethanolamine-gallate.

3. A pre-paved aggregate concrete based on high carbonation and high connectivity magnesium slag-steel slag-based artificial aggregate, characterized in that, It includes the high-carbon, high-connectivity magnesium slag-steel slag-based artificial aggregate coarse aggregate as described in claim 1 or 2, and the cementitious paste.

4. The pre-paved aggregate concrete based on high carbonation and high connectivity magnesium slag-steel slag based artificial aggregate according to claim 3, characterized in that, The volume of the high-carbon, high-connectivity magnesium slag-steel slag-based artificial aggregate coarse aggregate accounts for 40% to 60% of the total volume of concrete.

5. The pre-paved aggregate concrete based on high carbonation and high connectivity magnesium slag-steel slag based artificial aggregates according to claim 3, characterized by, The gelling paste comprises a gelling dry base, a second mixing water, and an admixture, with a water-to-binder ratio of 0.25 to 0.

35. The amount of admixture added is 0.5% to 1.5% of the total mass of the gelling paste. The gelled dry base, by mass percentage, comprises the following raw materials: A mixture of magnesium slag and steel slag, 60%–80%; sulfoaluminate cement, 15%–25%; silica fume, 5%–15%; The additives include a water-retaining agent and a second hydration accelerator; the water-retaining agent is hydroxypropyl methylcellulose ether. The second hydration promoter is at least one of triethanolamine and triethanolamine-gallate.

6. A method of manufacturing a pre-paved aggregate concrete based on high carbonation high connectivity magnesium slag-steel slag based artificial aggregates according to any one of claims 3-5, characterized in that, Includes the following steps: S1. A mixture of magnesium slag and steel slag, grinding media, and first mixing water containing a first hydration accelerator are placed in a ball mill, and a mixed gas containing CO2 is introduced to perform simultaneous mechanical grinding and carbonation to obtain a mixed slurry; S2. The mixed slurry obtained in S1 is mixed with carbonic anhydrase bacterial solution to form a pretreated material, which is then placed in a suspension carbonization reactor. The reaction system is kept at a constant temperature and humidity, and a mixed gas containing CO2 is introduced to carry out suspension microbial carbonization treatment to obtain magnesium slag-steel slag composite powder. S3. The magnesium slag-steel slag composite powder pretreated by S2 is dry-mixed with pore structure regulator and reinforcing component, and then the remaining first mixing water containing the first hydration accelerator is added. The mixture is then granulated, dehydrated by hydrothermal evaporation, and cured by pressure carbonization to obtain magnesium slag-steel slag-based artificial aggregate coarse aggregate. S4. The magnesium slag-steel slag-based artificial aggregate coarse aggregate obtained in S3 is pre-laid in the mold and vibrated to form a rigid skeleton. Then, cementitious slurry is injected and molded to obtain the pre-laid aggregate concrete.

7. The method of producing pre-paved aggregate concrete based on high carbonation and high connectivity magnesium slag-steel slag-based artificial aggregate according to claim 6, characterized in that, In step S1, the mass ratio of magnesium slag to steel slag in the mixture is 1:0.5 to 1:

2.

8. The method for preparing pre-laid aggregate concrete based on high-carbon, high-connectivity magnesium slag-steel slag-based artificial aggregate according to claim 6, characterized in that, In step S1, the grinding media is stainless steel balls, and the mass ratio of balls to slag is 1:1; the mixed gas containing CO2 is a mixture of CO2 and N2, wherein the volume concentration of CO2 is 15-20%, and the flow rate of the mixed gas is 10-20 mL per gram of slag per minute; the ball mill speed is 400-600 r / min, and the processing time is 15-30 minutes; the solid-liquid mass ratio of slag to first mixing water containing the first hydration accelerator is 1:

1.

9. The method for preparing pre-laid aggregate concrete based on high-carbon, high-connectivity magnesium slag-steel slag-based artificial aggregate according to claim 6, characterized in that, In S2, the water-to-solid mass ratio of the pretreated material is 1.5:1; the temperature of the suspension carbonization reactor is 30±5℃, the relative humidity is 90%, the CO2 volume concentration in the introduced mixed gas is not less than 20%, the flow rate is 0.05~0.2 L / min, and the reaction time is 5~15 minutes.

10. The method for preparing pre-laid aggregate concrete based on high-carbon, high-connectivity magnesium slag-steel slag-based artificial aggregate according to claim 6, characterized in that, In S3, the water-to-solid mass ratio of the mixture is 0.3~0.5; the temperature of the hydrothermal evaporation dehydration treatment is 105℃; and the pressurized carbonization curing is carried out in a closed reactor under the following conditions: pressure 0.2~0.4 MPa, CO2 concentration 99.9%, and curing time 10~14 hours.

Images