Method for preparing steel slag-based cementitious material using indirect carbonation technique

Abstract

The application discloses a method for preparing a steel slag-based cementitious material by using an indirect carbonation technology, and comprises the following steps: providing a steel slag in a powder form; mixing the steel slag with a carbonation carrier, an aluminum-containing activator, water and an optional water reducing agent to obtain a slurry material; placing the slurry material into a forming mold for forming; and obtaining a rough blank after demolding; and performing a curing treatment on the rough blank to obtain the steel slag-based cementitious material. The main component of the carbonation carrier is calcium carbonate, and the aluminum-containing activator is used to activate the calcium carbonate to release carbonate ions, so as to indirectly carbonize free calcium oxide, magnesium oxide and silicates in the steel slag, thereby preparing the steel slag-based cementitious material with good cementitious properties and high strength. The application provides a new way for the production of carbonated steel slag products, and has the characteristics of environmental protection, waste utilization, energy saving and low cost.

Description

Technical Field

[0001] This invention relates to a method for preparing steel slag-based cementitious materials, and more particularly to a method for preparing steel slag-based cementitious materials using indirect carbonization technology, belonging to the field of building materials technology. Background Technology

[0002] The direct use of steel slag in concrete production suffers from low hydration activity and poor stability. In recent years, carbonation treatment has been considered an effective way to realize the engineering applications of steel slag. In a carbon dioxide environment, free calcium oxide and magnesium oxide, tricalcium silicate, dicalcium silicate, and other calcium-containing mineral phases within the steel slag can react to form calcium carbonate, magnesium carbide, and silica gel (as shown in formulas 1-4). These transformations not only avoid the problem of hydration expansion and cracking in steel slag-based cementitious materials but also enable them to achieve strength at an early age.

[0004] CaO + H₂O + CO₂ → CaCO₃ + H₂O (1)

[0005] MgO + H₂O + CO₂ → MgCO₃ + H₂O (2)

[0006] Ca3SiO5+nH2O+3CO2→SiO2·nH2O(gel)+3CaCO3 (3)

[0007] Ca2SiO4+nH2O+2CO2→SiO2·nH2O(gel)+2CaCO3 (4)

[0008] Currently, existing steel slag carbonization technologies mainly utilize dry carbonization curing with carbon dioxide-containing gas. For example, patent CN109574610B promotes steel slag carbonization by adding gypsum and then preparing carbonized steel slag bricks through pressing. Under dry carbonization curing, the product can achieve a 1-day compressive strength of approximately 75 MPa. Patent CN112430051A increases the gas pressure and curing temperature during the carbonization process, achieving a 1-day compressive strength of approximately 60 MPa for carbonized steel slag bricks. Patent CN110818356B proposes a synergistic control method that utilizes water-reducing agents to lower the water-cement ratio, optimizes fine aggregate particle size, uses auxiliary hydraulic cementitious materials, and pre-drying to achieve an early strength of approximately 100 MPa for steel slag-based concrete after dry carbonization curing.

[0009] While the aforementioned technologies can achieve high degrees of steel slag carbonization, they still have some drawbacks. First, dry carbonization of steel slag products requires a series of methods to improve the diffusion efficiency of carbon dioxide gas, including adjusting material ratios, pressing and molding, and optimizing curing conditions. This process is complex and affected by product size, and the purchase of corresponding equipment increases production costs. Second, carbonized steel slag products cannot be formed on-site, limiting their flexibility and applicability in some engineering applications. Third, dry carbonization curing of steel slag is a passive carbon fixation process, making it difficult to actively design and precisely control the amount of carbon fixed in the steel slag product. Furthermore, in traditional dry carbonization processes, carbon dioxide diffuses and dissolves, generating carbonic acid in the pore solution of the steel slag product, thereby reducing internal alkalinity.

[0010] Therefore, it is necessary to develop a new carbonization technology to replace the traditional dry carbonization curing method, simplify the production process and cost of steel slag products, and achieve proactive control over the carbon fixation content of steel slag products. Summary of the Invention

[0011] The purpose of this invention is to address at least one problem existing in the prior art by providing a method for preparing steel slag-based cementitious materials using indirect carbonation technology. This method uses a calcium-containing active material as raw material to prepare a highly active carbonation carrier (mainly composed of calcium carbonate). An aluminum-containing alkaline activator is used to activate the calcium carbonate in the carbonation carrier, releasing carbonate ions, thereby indirectly carbonizing the free calcium oxide, magnesium oxide, tricalcium silicate, and dicalcium silicate within the steel slag, thus preparing a steel slag-based cementitious material with good cementing properties and high strength.

[0012] This invention effectively simplifies the production process of carburized steel slag products, reduces equipment requirements and overall costs, and avoids the problem of severe alkalinity reduction during traditional dry carbonization. Furthermore, this invention allows for on-site preparation of carburized steel slag products, increasing their flexibility and applicability in engineering applications, while also enabling proactive control over the carbon sequestration content of the steel slag products. Overall, indirect carbonization technology provides a new approach to the production of carburized steel slag products, featuring environmental friendliness, waste utilization, energy conservation, and low cost.

[0013] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0014] According to a first aspect of the present invention, a method for preparing a steel slag-based cementitious material is provided, comprising:

[0015] Steel slag is provided in powder form;

[0016] The steel slag is mixed with a carbonization carrier, an aluminum-containing activator, water, and an optional water-reducing agent to obtain a slurry material;

[0017] The slurry material is placed into a molding mold and shaped. After demolding, a rough blank is obtained.

[0018] The rough billet is cured to obtain the steel slag-based cementitious material.

[0019] In some embodiments, the particle size of the steel slag is no greater than 75 μm.

[0020] In some embodiments, the specific surface area of ​​the steel slag is not less than 300 m². 2 / kg.

[0021] In some embodiments, the steel slag is converter steel slag.

[0022] In some embodiments, the carbonization support comprises one or more of calcite, aragonite, aragonite, and amorphous calcium carbonate.

[0023] In some embodiments, the content of one or more of calcite, aragonite, aragonite and amorphous calcium carbonate in the carbonization carrier is not less than 50 wt%.

[0024] In some embodiments, the mass ratio of the steel slag to the carbonization carrier is (50-100):(10-50).

[0025] In some embodiments, the carbonization support is prepared by the following method:

[0026] Calcium-containing active materials are pulverized to obtain calcium-containing active powder;

[0027] The calcium-containing active powder is mixed with a carbonization reaction solution, and carbon dioxide gas is introduced into it for carbonization treatment to obtain a suspension.

[0028] The suspension was filtered, and the filtered product was dried to obtain the carbonized support.

[0029] In some embodiments, the calcium-containing active material comprises one or more of the following: calcium oxide, calcium chloride, calcium hydroxide, dicalcium silicate, tricalcium silicate, hydrated calcium silicate, hydrated calcium aluminate, hydrated calcium aluminosilicate, hydrated calcium ferrite, hydrated calcium sulfoaluminate, and hydrated calcium fluoroaluminate.

[0030] In some embodiments, the particle size of the calcium-containing active powder is no greater than 75 μm.

[0031] In some embodiments, the carbonization reaction solution includes one or more of water, magnesium chloride solution, magnesium nitrate solution, sodium carbonate solution, sodium bicarbonate solution, ammonium nitrate solution, ammonium chloride solution, sodium hydroxide solution, potassium hydroxide solution, and ammonia solution.

[0032] In some embodiments, the mass ratio of the calcium-containing active powder to the carbonization reaction solution is 1:(10-20).

[0033] In some embodiments, the reaction temperature of the carbonization treatment is 20-80°C.

[0034] In some embodiments, the carbonization process takes 0.5-3 hours.

[0035] In some embodiments, the carbonization process is carried out at a stirring speed of 300-1000 rpm.

[0036] In some embodiments, the aluminum-containing activator includes, but is not limited to, sodium aluminate, potassium aluminate, aluminum hydroxide, and any combination thereof, or one or more of these.

[0037] In some embodiments, the mass ratio of the steel slag to the aluminum-containing activator is (50-100):(3-50).

[0038] In some embodiments, the water-reducing agent includes one or more of polycarboxylate water-reducing agents, calcium lignosulfonate water-reducing agents, and aliphatic high-efficiency water-reducing agents.

[0039] In some embodiments, the mass ratio of the water-reducing agent to the sum of steel slag, carbonization carrier and aluminum-containing activator is (0-3):100.

[0040] In some embodiments, the slurry material comprises: 50-100 parts steel slag, 10-50 parts carbonization carrier, 3-50 parts aluminum-containing activator, 15-60 parts water, and 0-3 parts water-reducing agent.

[0041] In some embodiments, the curing humidity of the curing treatment is 30%-100% RH; and / or, the curing temperature is 20-80°C.

[0042] According to a second aspect of the present invention, a method for preparing a steel slag-based cementitious material is provided, comprising:

[0043] Calcium-containing active materials are pulverized to obtain calcium-containing active powder. Then, the calcium-containing active powder is mixed with a carbonization reaction solution, and carbon dioxide gas is introduced into it for carbonization treatment. The resulting suspension is filtered, and the filtered product is dried to obtain a carbonized carrier.

[0044] Steel slag is pulverized to obtain steel slag powder, which is then mixed with a carbonization carrier, an aluminum-containing activator, water, and an optional water-reducing agent to obtain a slurry material.

[0045] The slurry material is placed into a molding mold and shaped. After demolding, it is cured to obtain the steel slag-based cementitious material.

[0046] According to a third aspect of the present invention, a steel slag-based cementitious material prepared according to the method of the first or second aspect of the present invention is provided.

[0047] In some embodiments, the setting time of the steel slag-based cementitious material is no more than 50 minutes, and the 28-day compressive strength is no less than 20 MPa.

[0048] According to a fourth aspect of the invention, the use of steel slag-based cementitious materials prepared by the method according to the first aspect of the invention, or by the method according to the first or second aspect of the invention, in the production of concrete is provided.

[0049] The method of the present invention has at least the following advantages:

[0050] 1. The method of the present invention effectively simplifies the production process of carbonized steel slag products. The method is simple and easy to implement, and does not require complex supporting equipment, thus reducing equipment requirements and overall costs.

[0051] 2. The method of the present invention can prepare carbide steel slag products on site, which increases its flexibility and applicability in engineering applications.

[0052] 3. The method of the present invention uses an aluminum-containing activator to activate the carbonation carrier to generate carbonate ions, which then react with calcium-containing minerals in the steel slag to generate calcium carbonate. During this process, hydroxide ions can be generated, which increases the alkalinity of the pore solution inside the steel slag product, thereby avoiding the problem of severe alkalinity reduction in the traditional dry carbonation process.

[0053] 4. The method of this invention uses a wet carbonization process to prepare a carbonization carrier from calcium-containing active materials, thus allowing for the detection of the amount of carbon dioxide captured in the carbonization carrier. Subsequently, when mixing the carbonization carrier with steel slag to prepare carbonized steel slag products, the amount of carbon fixed in the carbonized steel slag products can be actively controlled by adjusting the amount of carbonization carrier used. Attached Figure Description

[0054] Figure 1 The XRD pattern of a steel slag-based cementitious material prepared according to one embodiment of the present invention.

[0055] Figure 2 SEM image of a steel slag-based cementitious material prepared according to an embodiment of the present invention. Detailed Implementation

[0056] The following describes exemplary embodiments of the present invention, but these should not be construed as limiting the invention. The scope of the invention should be defined by the scope of the claims (including equivalents). Various changes can be made to the invention without departing from the scope of this specification and the claims (including equivalents), and all such changes fall within the scope of protection of this invention. In some cases, well-known materials and techniques are not shown or described in detail in order not to obscure the scope of the invention. Furthermore, materials, methods, or steps described in detail with reference to one embodiment can be included in other embodiments where they are not specifically shown or described, provided that it is feasible.

[0057] definition

[0058] In the specification, references to "an embodiment," "preferred embodiment," "exemplary embodiment," etc., indicate that the described embodiment may include specific features, structures, or characteristics, but not every embodiment may include specific features, structures, or characteristics. Furthermore, such phrases do not necessarily refer to the same embodiment. Additionally, when a specific feature, structure, or characteristic is described in connection with an embodiment, whether or not it is explicitly described, it is assumed that the effect of applying that feature, structure, or characteristic to other embodiments is within the knowledge of those skilled in the art.

[0059] Any numerical value mentioned in this invention, if there is only a two-unit interval between any minimum and any maximum value, includes all values ​​that increase by one unit each time from the minimum to the maximum value. For example, if the amount of a component, or the value of a process variable such as temperature, pressure, or time, is stated as 50-90, in this specification it means specifically listing values ​​such as 51-89, 52-88… and 69-71 and 70-71, etc. For non-integer values, it may be appropriately considered that a unit is 0.1, 0.01, 0.001, or 0.0001. These are merely some specifically specified examples. In this application, in a similar manner, all possible combinations of numerical values ​​between the listed minimum and maximum values ​​are considered to have been disclosed.

[0060] As stated herein, unless otherwise specified, the term "an / a" is used to include one / a or more / a, and the term "or" is used to indicate a non-exclusive "or". Furthermore, when terms used herein are not otherwise defined, they should be understood as being for descriptive purposes only and not for limiting purposes. Additionally, all publications, patents, and patent documents mentioned in the specification are incorporated herein by reference in their entirety as if individually incorporated by reference. If there is any inconsistency between the usage in this document and those documents incorporated by reference, the usage in the cited references shall be considered supplementary to this document. In the event of irreconcilable inconsistencies, the usage herein shall prevail.

[0061] In the manufacturing method described in the specification, the steps may be performed in any order without departing from the principles of the invention, except where the timing or sequence of operations is explicitly stated. The claims state that a step is performed first, followed by several other steps. It should be understood that the first step is performed before any other step, and other steps may be performed within any other step unless the order is further specified in that step. For example, a claim stating "step A, step B, step C, step D, and step E" should be interpreted as meaning that step A is performed first, step E is performed last, and steps B, C, and D are performed within steps A and E. They may be performed in any order, and such order still falls within the literal scope of the process claimed in the claims. Similarly, a given step or sub-step may be repeated.

[0062] Unless otherwise specified, the term "parts" as used in this invention refers to the number of parts by mass of the ingredients.

[0063] In some embodiments, the present invention provides a method for preparing steel slag-based cementitious materials, comprising:

[0064] Steel slag is provided in powder form;

[0065] The steel slag is mixed with a carbonization carrier, an aluminum-containing activator, water, and an optional water-reducing agent to obtain a slurry material;

[0066] The slurry material is placed into a molding mold and shaped. After demolding, a rough blank is obtained.

[0067] The rough billet is cured to obtain the steel slag-based cementitious material.

[0068] In some embodiments, the steel slag raw material is crushed, ground, and then sieved to retain particles with a particle size of less than 75 μm, thereby obtaining the steel slag in powder form.

[0069] In some embodiments, the particle size of the steel slag is not greater than 75 μm, for example, 0.1-75 μm.

[0070] In some embodiments, the specific surface area of ​​the steel slag is not less than 300 m². 2 / kg.

[0071] In some embodiments, the specific surface area of ​​the steel slag is determined by a Blaine surface area analyzer.

[0072] The steel slag, which is in powder form, can also be called steel slag powder.

[0073] While not wishing to be bound by any theoretical framework, the inventors have discovered that the specific surface area of ​​steel slag powder affects the effectiveness of indirect carbonization. It has been found that the larger the specific surface area of ​​the steel slag powder, the faster the indirect carbonization rate, and the faster the setting time and higher the strength of the prepared product. In some embodiments, the steel slag is converter steel slag. Converter steel slag is a byproduct of the iron and steel industry, containing a large amount of free calcium oxide, magnesium oxide, and silicates, and its carbonization products possess high cementing properties.

[0074] In some embodiments, the carbonization support comprises one or more of calcite, aragonite, aragonite, and amorphous calcium carbonate.

[0075] In some embodiments, the content of one or more of calcite, aragonite, aragonite and amorphous calcium carbonate in the carbonization carrier is not less than 50 wt%, preferably not less than 60 wt%.

[0076] In some embodiments, the carbonization carrier contains one or more of calcite, aragonite, aragonite, and amorphous calcium carbonate in an amount of not less than 50 wt%, for example, more than 60 wt%, more than 70 wt%, or more than 80 wt%.

[0077] In some embodiments, the carbonation carrier is a highly active calcium carbonate carrier, which is activated by an aluminum-containing activator (which, upon mixing with water or other solutions, undergoes a hydrolysis reaction to further generate aluminum-containing basic groups, yielding an aluminum-containing basic activator solution) to release carbonate ions, indirectly carbonizing the free calcium oxide, magnesium oxide, tricalcium silicate, and dicalcium silicate within the steel slag, thus preparing a steel slag-based cementitious material with good cementitious properties and high strength. In some embodiments, the reactions occurring during the carbonization of steel slag are shown in equations 5 to 9 below:

[0078]

[0079] In some embodiments, the mass ratio of steel slag to carbide carrier is (50-100):(10-50). For example, the mass ratio of steel slag to carbide carrier can be (60-100):(10-50), (70-100):(10-50), (80-100):(10-50), (50-90):(10-50), (50-80):(10-50), (50-100):(10-40), (50-100):(10-30), (50-100):(10-20), (50-100):(20-50), (70-100):(10-40), (70-90):(10-30), (70-80):(20-30), and any value or range therebetween.

[0080] In some preferred embodiments, the mass ratio of the steel slag to the carbonization carrier is (75-85):(15-25).

[0081] In some embodiments, the carbonization support is prepared by the following method:

[0082] Calcium-containing active materials are pulverized to obtain calcium-containing active powder;

[0083] The calcium-containing active powder is mixed with a carbonization reaction solution, and carbon dioxide gas is introduced into it for carbonization treatment to obtain a suspension.

[0084] The suspension was filtered, and the filtered product was dried to obtain the carbonized support.

[0085] In some embodiments, the calcium-containing active material comprises one or more of the following: calcium oxide, calcium chloride, calcium hydroxide, dicalcium silicate, tricalcium silicate, hydrated calcium silicate, hydrated calcium aluminate, hydrated calcium aluminosilicate, hydrated calcium ferrite, hydrated calcium sulfoaluminate, and hydrated calcium fluoroaluminate.

[0086] In some embodiments, the calcium-containing active material may be, but is not limited to, silicate cement and clinker, aluminate cement and clinker, sulfoaluminate cement and clinker, ferroaluminate cement and clinker, fluoroaluminate cement and clinker, or one or more combinations thereof, or may be, but is not limited to, waste concrete powder, carbide slag, steel slag, blast furnace slag, fly ash, municipal solid waste incineration ash, or one or more combinations thereof.

[0087] In some embodiments, the calcium-containing active material is crushed, ground, and then sieved to retain particles with a particle size of less than 75 μm to obtain the calcium-containing active powder.

[0088] In some embodiments, the particle size of the calcium-containing active powder is not greater than 75 μm, for example, 0.1-75 μm.

[0089] In some embodiments, the carbonation reaction solution includes one or more of the following: water, magnesium chloride solution, magnesium nitrate solution, sodium carbonate solution, sodium bicarbonate solution, ammonium nitrate solution, ammonium chloride solution, sodium hydroxide solution, potassium hydroxide solution, and ammonia solution. In some embodiments, when the carbonation reaction solution includes one or more of the following: magnesium chloride solution, magnesium nitrate solution, sodium carbonate solution, sodium bicarbonate solution, ammonium nitrate solution, ammonium chloride solution, sodium hydroxide solution, potassium hydroxide solution, and ammonia solution, the molar concentration of each solution is 0.05-1.0 mol / L.

[0090] While not wanting to be bound by theory, it was found that using the above-mentioned carbonation reaction solution can improve the carbon dioxide capture efficiency of steel slag, or can regulate the crystal form of calcium carbonate to further enhance the activity of the carbonation carrier.

[0091] In some embodiments, the mass ratio of the calcium-containing active powder to the carbonization reaction solution is 1:(10-20), for example, 1:10, 1:12, 1:15, 1:18, 1:20 or any value or range thereof.

[0092] In some embodiments, the carbon dioxide-containing gas may be commercially available carbon dioxide or carbon dioxide-rich tail gas from cement industry exhaust gas, power plant exhaust gas, or a combination thereof, wherein the volume concentration of carbon dioxide is not less than 20%, for example 30%, 50%, 70%, 90%, 95%, 99% or higher.

[0093] In some implementations, the ventilation rate of the carbon dioxide-containing gas is 5-20 ml / min / g.

[0094] In some embodiments, the carbonization treatment is carried out at a reaction temperature of 20-80°C, for example, 20-70°C, 20-60°C, 20-50°C, 20-40°C, 20-30°C, or any value or range thereof. In some embodiments, the carbonization treatment is carried out at room temperature (25-35°C).

[0095] In some embodiments, the carbonization process takes 0.5-3 hours, for example, 0.5-2.5 hours, 0.5-2 hours, 1-2.5 hours, 1-2 hours or any value or range therebetween.

[0096] In some embodiments, the carbonization process is carried out at a stirring speed of 300-1000 rpm. In some embodiments, the stirring speed can be any value or range between 300-900 rpm, 300-800 rpm, 400-1000 rpm, 400-900 rpm, 400-800 rpm, 500-1000 rpm, 500-900 rpm, 500-800 rpm, 600-1000 rpm, 600-900 rpm, 600-800 rpm, 700-1000 rpm, 700-900 rpm, 700-800 rpm, or any value or range therebetween.

[0097] In some embodiments, the filtered product is dried at -80 to 105°C.

[0098] In some embodiments, the aluminum-containing activator, upon mixing with water or other solutions, undergoes a hydrolysis reaction to further generate aluminum-containing basic groups, yielding an aluminum-containing basic activator solution, thereby activating the carbonation support to release carbonate ions (as shown in Equation 5). In some embodiments, the aluminum-containing activator includes, but is not limited to, sodium aluminate, potassium aluminate, aluminum hydroxide, and one or more combinations thereof. In one embodiment, the aluminum-containing activator is sodium aluminate, which, upon mixing with water, undergoes hydrolysis to further generate aluminate ions and hydroxide ions, thereby activating the carbonation support to release carbonate ions.

[0099] In some embodiments, the mass ratio of the steel slag to the aluminum-containing activator is (50-100):(3-50). For example, the mass ratio of the steel slag to the aluminum-containing activator can be (60-100):(3-50), (70-100):(3-50), (80-100):(3-50), (50-90):(3-50), (50-80):(3-50), (50-100):(3-40), (50-100):(3-30), (50-100):(3-20), (50-100):(10-20), (60-100):(5-50), (70-100):(3-40), (70-90):(3-30), (70-80):(10-20), and any value or range therebetween.

[0100] In some preferred embodiments, the mass ratio of the steel slag to the aluminum-containing activator is (75-85):(10-15).

[0101] To avoid being bound by theory, the use of water-reducing agents in this invention can improve the fluidity of the slurry, appropriately reduce the amount of water in the cementitious material, and thus improve the strength of the resulting cementitious material.

[0102] There are no particular restrictions on the type of water-reducing agent. Most water-reducing agents in the art are applicable to this invention, as long as they can achieve the above-mentioned effects.

[0103] In some embodiments, the water-reducing agent includes one or more of polycarboxylate water-reducing agents, calcium lignosulfonate water-reducing agents, and aliphatic high-efficiency water-reducing agents.

[0104] In some embodiments, the mass ratio of the water-reducing agent to the sum of the steel slag powder, carbonization carrier and aluminum-containing activator is (0-3):100, for example (0.5-2):100.

[0105] In some embodiments, the water is in a mass ratio of (0.3-0.6):1 to other solid raw materials (the sum of steel slag powder, carbonization carrier, aluminum-containing activator, and optional water-reducing agent).

[0106] In some embodiments, the slurry material comprises: 50-100 parts steel slag, 10-50 parts highly active calcium carbonate powder, 3-50 parts aluminum-containing activator, 15-60 parts water, and 0-3 parts water-reducing agent.

[0107] In some embodiments, the slurry material contains the following parts by weight of steel slag: 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, or any value or range thereof. In some preferred embodiments, the slurry material contains 60-90 parts, preferably 75-85 parts, more preferably 80 parts of steel slag.

[0108] In some embodiments, the slurry material contains the following parts by weight of carbonization carrier: 10, 15, 20, 25, 30, 35, 40, 45, 50, or any value or range thereof. In some preferred embodiments, the slurry material contains 10-30 parts, preferably 15-25 parts, more preferably 20 parts of carbonization carrier.

[0109] In some embodiments, the slurry material contains the following parts by weight of an aluminum-containing activator: 3, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, or any value or range thereof. In some preferred embodiments, the slurry material contains 5-20 parts, preferably 10-15 parts, more preferably 13.3 parts of an aluminum-containing activator.

[0110] In some embodiments, the slurry material contains the following parts by weight of water: 115, 20, 25, 30, 35, 40, 45, 50, 55, 60, or any value or range thereof. In some preferred embodiments, the slurry material contains 30-50 parts, preferably 35-45 parts, of water.

[0111] In some embodiments, the slurry material contains the following parts by weight of water-reducing agent: 0, 0.5, 1, 1.5, 2, 2.5, 3, or any value or range thereof. In some preferred embodiments, the slurry material contains 1-3 parts, preferably 1.5-2.5 parts, more preferably 2 parts of water-reducing agent.

[0112] In some embodiments, the slurry material comprises steel slag, a carbonization carrier, an aluminum-containing activator, and water, or is composed of steel slag, a carbonization carrier, an aluminum-containing activator, and water.

[0113] In some embodiments, the slurry material comprises steel slag, a carbonization carrier, an aluminum-containing activator, water, and a water-reducing agent, or is composed of steel slag, a carbonization carrier, an aluminum-containing activator, water, and a water-reducing agent.

[0114] In some embodiments, the slurry material comprises, or is composed of, the above-mentioned parts by weight of steel slag, carbonization carrier, aluminum-containing activator, water and water-reducing agent.

[0115] In some embodiments, the curing humidity of the curing treatment is 30%-100%RH, and the curing temperature is 20-80℃.

[0116] Indirect carbonization is effectively carried out during the curing process. Not wanting to be bound by theory, the inventors discovered that curing at the aforementioned humidity and temperature yields satisfactory results. Too low a humidity level will cause the interior of the block to become too dry, preventing carbonate ions from carbonizing the steel slag powder through the solution. Too low a temperature may cause the reaction to stop or slow down, while too high a temperature may cause some carbonization products to dehydrate or decompose.

[0117] In some embodiments, the present invention provides a method for preparing steel slag-based cementitious materials, comprising:

[0118] Calcium-containing active materials are pulverized to obtain calcium-containing active powder. Then, the calcium-containing active powder is mixed with a carbonization reaction solution, and carbon dioxide gas is introduced into it for carbonization treatment. The resulting suspension is filtered, and the filtered product is dried to obtain a carbonized carrier.

[0119] Steel slag is pulverized to obtain steel slag powder, which is then mixed with a carbonization carrier, an aluminum-containing activator, water, and an optional water-reducing agent to obtain a slurry material.

[0120] The slurry material is placed into a molding mold and shaped. After demolding, it is cured to obtain the steel slag-based cementitious material.

[0121] The process conditions, specific selection of raw materials, and mass fractions for each step are as specified above.

[0122] In some embodiments, the present invention provides a steel slag-based cementitious material prepared according to the foregoing method.

[0123] In some embodiments, the setting time of the steel slag-based cementitious material is no more than 50 minutes, and the 28-day compressive strength is no less than 20 MPa.

[0124] In some embodiments, the setting time of the steel slag-based cementitious material is no more than 50 minutes, no more than 48 minutes, no more than 45 minutes, no more than 43 minutes, no more than 40 minutes, no more than 38 minutes, no more than 35 minutes, or no more than 30 minutes.

[0125] In some embodiments, the 28-day compressive strength of the steel slag-based cementitious material is not less than 20 MPa, not less than 22 MPa, not less than 25 MPa, not less than 30 MPa, not less than 32 MPa, not less than 35 MPa, not less than 40 MPa, not less than 45 MPa, or not less than 50 MPa.

[0126] In some embodiments, the present invention provides the use of the aforementioned method and the steel slag-based cementitious material prepared according to the aforementioned method in the production of concrete.

[0127] Example

[0128] The technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application. To avoid redundancy, the raw materials or reagents used in the following embodiments are all commercially available or self-made.

[0129] In the embodiments, the crystal phase composition of the product was determined using a Rigaku Smart-Lab 9kW X-ray diffractometer; the microstructure of the product was observed using a Tescan VEGA3 scanning electron microscope.

[0130] In the examples, the setting time of the prepared steel slag-based cementitious material was determined using a cement Vicat apparatus according to the method of GB / T 1346-2011; the compressive strength of the prepared steel slag-based cementitious material was determined using a Testometric X350 universal testing machine, wherein a 2cm cubic specimen was used and the loading rate was 0.5mm / min.

[0131] Example 1

[0132] Waste cement blocks and converter steel slag produced by Guangxi Liuzhou Iron and Steel Group were selected as the main raw materials. The Blaine specific surface area of ​​the steel slag was 412 kg / m². 2 The main chemical components of waste cement blocks and steel slag are:

[0133]

[0134] The specific steps include:

[0135] Step 1: Crush, grind, and sieve the waste cement blocks to obtain fine powder with a particle size of less than 75 μm. Take 10 parts of waste cement block powder and mix it with 100 parts of pure water in a carbonation stirring device. Introduce gas containing 99.9% carbon dioxide at a flow rate of 0.02 L / min / g and a stirring speed of 800 rpm. React at room temperature for 2 hours. Filter and freeze-dry the resulting solid to obtain carbonized cement powder with calcite as the main component, wherein the calcite content is approximately 83 wt%.

[0136] Step 2: Dissolve 13.3 parts of sodium aluminate powder in 45 parts of water and allow to cool to obtain an aluminum-containing alkaline activator solution. Crush, grind, and sieve the steel slag to obtain fine powder with a particle size of less than 75 μm. Premix 20 parts of carbonized cement powder from Step 1 with 80 parts of steel slag powder using a mixer. Stir the aluminum-containing alkaline activator solution and the premixed powder material evenly at a stirring speed of 500 rpm to obtain a steel slag-based cementitious material slurry.

[0137] Step 3: Pour the steel slag-based cementitious material slurry into a mold and place it at room temperature to set before demolding. Then, transfer it to a concrete curing chamber with a relative humidity of not less than 95% RH for room temperature curing to develop strength. The resulting steel slag-based cementitious material's crystalline phase composition and microstructure are as follows: Figure 1 and Figure 2 As shown in Table 1, the setting time and 28-day compressive strength are as follows.

[0138] Example 2

[0139] The same waste cement blocks as in Example 1 and converter steel slag produced by Guangxi Liugang Group were selected as the main raw materials.

[0140] The specific steps include:

[0141] Step 1: Crush, grind, and sieve the waste cement blocks to obtain fine powder with a particle size of less than 75 μm. Take 10 parts of waste cement block powder and mix it with 100 parts of pure water in a carbonization stirring device. Introduce gas containing 99.9% carbon dioxide into the mixture. React for 2 hours at room temperature with a gas flow rate of 0.02 L / min / g and a stirring speed of 800 rpm. Filter the mixture and freeze-dry the resulting solid to obtain carbonized cement powder with calcite as the main component, wherein the calcite content is approximately 83 wt%.

[0142] Step 2: Dissolve 20 parts of sodium aluminate powder in 45 parts of water and allow to cool to obtain an aluminum-containing alkaline activator solution. Crush, grind, and sieve the steel slag to obtain fine powder with a particle size of less than 75 μm. Premix 20 parts of carbonized cement powder from Step 1 with 80 parts of steel slag powder using a mixer. Stir the aluminum-containing alkaline activator solution and the premixed powder material evenly at a stirring speed of 500 rpm to obtain a steel slag-based cementitious material slurry.

[0143] Step 3: Pour the steel slag-based cementitious material slurry into a mold, place it at room temperature to allow it to set, then remove the mold and transfer it to a concrete curing chamber with a relative humidity of not less than 95% RH for room temperature curing to develop strength. The setting time and 28-day compressive strength of the obtained steel slag-based cementitious material are shown in Table 1.

[0144] Example 3

[0145] The same waste cement blocks as in Example 1 and converter steel slag produced by Guangxi Liugang Group were selected as the main raw materials.

[0146] The specific steps include:

[0147] Step 1: Crush, grind, and sieve the waste cement blocks to obtain fine powder with a particle size of less than 75 μm. Take 10 parts of waste cement block powder and mix it with 100 parts of pure water in a carbonization stirring device. Introduce gas containing 99.9% carbon dioxide into the mixture. React for 2 hours at room temperature with a gas flow rate of 0.02 L / min / g and a stirring speed of 800 rpm. Filter the mixture and freeze-dry the resulting solid to obtain carbonized cement powder with calcite as the main component, wherein the calcite content is approximately 83 wt%.

[0148] Step 2: Dissolve 6.67 parts of sodium aluminate powder in 45 parts of water and allow to cool to obtain an aluminum-containing alkaline activator solution. Crush, grind, and sieve the steel slag to obtain fine powder with a particle size of less than 75 μm. Premix 20 parts of carbonized cement powder from Step 1 with 80 parts of steel slag powder using a mixer. Stir the aluminum-containing alkaline activator solution and the premixed powder material evenly at a stirring speed of 500 rpm to obtain a steel slag-based cementitious material slurry.

[0149] Step 3: Pour the steel slag-based cementitious material slurry into a mold, place it at room temperature to allow it to set, then remove the mold and transfer it to a concrete curing chamber with a relative humidity of not less than 95% RH for room temperature curing to develop strength. The setting time and 28-day compressive strength of the obtained steel slag-based cementitious material are shown in Table 1.

[0150] Example 4

[0151] The same waste cement blocks as in Example 1 and converter steel slag produced by Guangxi Liugang Group were selected as the main raw materials.

[0152] The specific steps include:

[0153] Step 1: Crush, grind, and sieve the waste cement blocks to obtain fine powder with a particle size of less than 75 μm. Take 10 parts of waste cement block powder, 3.8 parts of magnesium chloride powder, and 100 parts of pure water and mix them in a carbonization stirring device. Introduce a gas containing 99.9% carbon dioxide into the carbonization stirring device. React for 1 hour at a gas flow rate of 0.02 L / min / g, a stirring speed of 800 rpm, and 80°C. Filter and freeze-dry the obtained solid to obtain carbonized cement powder with aragonite as the main component, wherein the aragonite content is approximately 68 wt%.

[0154] Step 2: Dissolve 20 parts of sodium aluminate powder in 45 parts of water and allow to cool to obtain an aluminum-containing alkaline activator solution. Crush, grind, and sieve the steel slag to obtain fine powder with a particle size of less than 75 μm. Premix 20 parts of carbonized cement powder from Step 1 with 80 parts of steel slag powder using a mixer. Stir the aluminum-containing alkaline activator solution and the premixed powder material evenly at a stirring speed of 500 rpm to obtain a steel slag-based cementitious material slurry.

[0155] Step 3: Pour the steel slag-based cementitious material slurry into a mold, place it at room temperature to allow it to set, then remove the mold and transfer it to a concrete curing chamber with a relative humidity of not less than 95% RH for room temperature curing to develop strength. The setting time and 28-day compressive strength of the obtained steel slag-based cementitious material are shown in Table 1.

[0156] Example 5

[0157] Converter slag produced by Guangxi Liugang Group, the same as in Example 1, was selected as the main raw material.

[0158] The specific steps include:

[0159] Step 1: Prepare the carbonation reaction solution by dissolving ammonium nitrate in water to obtain an ammonium nitrate solution. The molar concentration of ammonium nitrate is 1.0 mol / L.

[0160] Step 2: Crush, grind, and sieve the steel slag to obtain fine powder with a particle size of less than 75 μm. Take 10 parts of the steel slag powder and mix it with 200 parts of the carbonization reaction solution from Step 1 in a carbonization stirring device. Introduce a gas containing 99.9% carbon dioxide into the mixture. React for 1 hour at a gas flow rate of 0.02 L / min / g and a stirring speed of 800 rpm at room temperature. Filter the mixture and freeze-dry the resulting solid to obtain carbonized steel slag powder with aragonite as the main component, wherein the aragonite content is approximately 62 wt%.

[0161] Step 3: Dissolve 13.3 parts of sodium aluminate powder in 45 parts of water and allow to cool to obtain an aluminum-containing alkaline activator solution. Premix 20 parts of carbide steel slag powder from Step 2 with 80 parts of uncarbide steel slag powder using a mixer. Stir the aluminum-containing alkaline activator solution and the premixed powder materials evenly at a stirring speed of 500 rpm to obtain a steel slag-based cementitious material slurry.

[0162] Step 4: Pour the steel slag-based cementitious material slurry into a mold and place it at room temperature to set before demolding. Then transfer it to a concrete curing chamber with a relative humidity of not less than 95% RH for room temperature curing to develop strength. The setting time and 28-day compressive strength of the resulting steel slag-based cementitious material are shown in Table 1.

[0163] Example 6

[0164] The same waste cement blocks as in Example 1 and converter steel slag produced by Guangxi Liugang Group were selected as the main raw materials.

[0165] The specific steps include:

[0166] Step 1: Crush, grind, and sieve the waste cement blocks to obtain fine powder with a particle size of less than 75 μm. Take 10 parts of waste cement block powder and mix it with 100 parts of pure water in a carbonization stirring device. Introduce gas containing 99.9% carbon dioxide at a flow rate of 0.02 L / min / g and a stirring speed of 800 rpm. React at room temperature for 2 hours. Filter and freeze-dry the resulting solid to obtain carbonized cement powder with calcite as the main component, wherein the calcite content is approximately 83 wt%.

[0167] Step 2: Dissolve 13.3 parts of sodium aluminate powder in 38 parts of water and allow to cool to obtain an aluminum-containing alkaline activator solution. Crush, grind, and sieve the steel slag to obtain fine powder with a particle size of less than 75 μm. Add 20 parts of carbonized cement powder from Step 1 and 2 parts of polycarboxylate superplasticizer ( - Type I polycarboxylate superplasticizer (Subote Company, Jiangsu, China) was premixed with 80 parts of steel slag powder using a mixer. The aluminum-containing alkaline activator solution was then uniformly stirred with the premixed powder material at a stirring speed of 500 rpm to obtain a steel slag-based cementitious material slurry.

[0168] Step 3: Pour the steel slag-based cementitious material slurry into a mold, place it at room temperature to allow it to set, then remove the mold and transfer it to a concrete curing chamber with a relative humidity of not less than 95% RH for room temperature curing to develop strength. The setting time and 28-day compressive strength of the obtained steel slag-based cementitious material are shown in Table 1.

[0169] Example 7

[0170] The same waste cement blocks as in Example 1 and converter steel slag produced by Guangxi Liugang Group were selected as the main raw materials.

[0171] The specific steps include:

[0172] Step 1: Crush, grind, and sieve the waste cement blocks to obtain fine powder with a particle size of less than 75 μm. Take 10 parts of waste cement block powder and mix it with 100 parts of pure water in a carbonization stirring device. Introduce gas containing 99.9% carbon dioxide into the carbonization stirring device at a flow rate of 0.02 L / min / g and a stirring speed of 800 rpm. React at room temperature for 2 hours, filter, and freeze-dry the resulting solid to obtain carbonized cement powder with calcite as the main component, wherein the calcite content is approximately 83 wt%.

[0173] Step 2: Dissolve 13.3 parts of sodium aluminate powder in 40 parts of water and allow to cool to obtain an aluminum-containing alkaline activator solution. Crush, grind, and sieve the steel slag to obtain fine powder with a particle size of less than 75 μm. Add 20 parts of carbonized cement powder from Step 1 and 1 part of polycarboxylate superplasticizer ( - Type I polycarboxylate superplasticizer (Subote Company, Jiangsu, China) was premixed with 80 parts of steel slag powder using a mixer. The aluminum-containing alkaline activator solution was then uniformly stirred with the premixed powder material at a stirring speed of 500 rpm to obtain a steel slag-based cementitious material slurry.

[0174] Step 3: Pour the steel slag-based cementitious material slurry into a mold, place it at room temperature to allow it to set, then remove the mold and transfer it to a concrete curing chamber with a relative humidity of not less than 95% RH for room temperature curing to develop strength. The setting time and 28-day compressive strength of the obtained steel slag-based cementitious material are shown in Table 1.

[0175] Example 8

[0176] The same waste cement blocks as in Example 1 and converter steel slag produced by Guangxi Liugang Group were selected as the main raw materials.

[0177] The specific steps include:

[0178] Step 1: Crush, grind, and sieve the waste cement blocks to obtain fine powder with a particle size of less than 75 μm. Take 10 parts of waste cement block powder and mix it with 100 parts of pure water in a carbonization stirring device. Introduce gas containing 99.9% carbon dioxide into the carbonization stirring device at a flow rate of 0.02 L / min / g and a stirring speed of 800 rpm. React at room temperature for 2 hours, filter, and freeze-dry the resulting solid to obtain carbonized cement powder with calcite as the main component, wherein the calcite content is approximately 83 wt%.

[0179] Step 2: Dissolve 13.3 parts of sodium aluminate powder in 35 parts of water and allow to cool to obtain an aluminum-containing alkaline activator solution. Crush, grind, and sieve the steel slag to obtain fine powder with a particle size of less than 75 μm. Add 20 parts of carbonized cement powder from Step 1 and 3 parts of polycarboxylate superplasticizer ( - Type I polycarboxylate superplasticizer (Subote Company, Jiangsu, China) was premixed with 80 parts of steel slag powder using a mixer. The aluminum-containing alkaline activator solution was then uniformly stirred with the premixed powder material at a stirring speed of 500 rpm to obtain a steel slag-based cementitious material slurry.

[0180] Step 3: Pour the steel slag-based cementitious material slurry into a mold, place it at room temperature to allow it to set, then remove the mold and transfer it to a concrete curing chamber with a relative humidity of not less than 95% RH for room temperature curing to develop strength. The setting time and 28-day compressive strength of the obtained steel slag-based cementitious material are shown in Table 1.

[0181] Example 9

[0182] The same waste cement blocks as in Example 1 and converter steel slag produced by Guangxi Liugang Group were selected as the main raw materials.

[0183] The specific steps include:

[0184] Step 1: Crush, grind, and sieve the waste cement blocks to obtain fine powder with a particle size of less than 75 μm. Take 10 parts of waste cement block powder, 3.8 parts of magnesium chloride powder, and 100 parts of pure water and mix them in a carbonization stirring device. Introduce a gas containing 99.9% carbon dioxide into the carbonization stirring device. React for 1 hour at a gas flow rate of 0.02 L / min / g, a stirring speed of 800 rpm, and 80°C. Filter and freeze-dry the obtained solid to obtain carbonized cement powder with aragonite as the main component, wherein the aragonite content is approximately 68 wt%.

[0185] Step 2: Dissolve 13.3 parts of sodium aluminate powder in 38 parts of water and allow to cool to obtain an aluminum-containing alkaline activator solution. Crush, grind, and sieve the steel slag to obtain fine powder with a particle size of less than 75 μm. Add 20 parts of carbonized cement powder from Step 1 and 2 parts of polycarboxylate superplasticizer ( - Type I polycarboxylate superplasticizer (Subote Company, Jiangsu, China) was premixed with 80 parts of steel slag powder using a mixer. The aluminum-containing alkaline activator solution was then uniformly stirred with the premixed powder material at a stirring speed of 500 rpm to obtain a steel slag-based cementitious material slurry.

[0186] Step 3: Pour the steel slag-based cementitious material slurry into a mold, place it at room temperature to allow it to set, then remove the mold and transfer it to a concrete curing chamber with a relative humidity of not less than 95% RH for room temperature curing to develop strength. The setting time and 28-day compressive strength of the obtained steel slag-based cementitious material are shown in Table 1.

[0187] Comparative Example 1

[0188] The same waste cement blocks as in Example 1 and converter steel slag produced by Guangxi Liugang Group were selected as the main raw materials.

[0189] Step 1: Crush, grind, and sieve the waste cement blocks to obtain fine powder with a particle size of less than 75 μm. Take 10 parts of waste cement block powder and mix it with 100 parts of pure water in a carbonization stirring device. Introduce gas containing 99.9% carbon dioxide at a flow rate of 0.02 L / min / g and a stirring speed of 800 rpm. React at room temperature for 2 hours. Filter and freeze-dry the resulting solid to obtain carbonized cement powder with calcite as the main component, wherein the calcite content is approximately 83 wt%.

[0190] Step 2: Crush, grind, and sieve the steel slag to obtain fine powder with a particle size of less than 75 μm. Premix 20 parts of carbonized cement powder from Step 1 with 80 parts of steel slag powder using a mixer. Then, mix the mixed powder with 45 parts of purified water at a stirring speed of 500 rpm to obtain a steel slag-based cementitious material slurry.

[0191] Step 3: Pour the steel slag-based cementitious material slurry into a mold, place it at room temperature to allow it to set, then remove the mold and transfer it to a concrete curing chamber with a relative humidity of not less than 95% RH for room temperature curing to develop strength. The setting time and 28-day compressive strength of the obtained steel slag-based cementitious material are shown in Table 1.

[0192] Comparative Example 2

[0193] Converter slag produced by Guangxi Liugang Group, the same as in Example 1, was selected as the main raw material.

[0194] Step 1: Crush, grind and sieve the steel slag to obtain fine powder with a particle size of less than 75μm.

[0195] Step 2: Dissolve 13.3 parts of sodium aluminate powder in 45 parts of water and allow to cool to obtain an aluminum-containing alkaline activator solution. Mix 100 parts of steel slag powder with the aluminum-containing alkaline activator solution at a stirring speed of 500 rpm to obtain a steel slag-based cementitious material slurry.

[0196] Step 3: Pour the steel slag-based cementitious slurry into the mold, place it at room temperature to set and solidify, then remove the mold. Transfer it to a concrete curing box with a relative humidity of not less than 95% RH for room temperature curing to develop strength. The setting time and 28-day compressive strength of the resulting steel slag-based cementitious material are shown in Table 1.

[0197] Table 1 - Comparison of setting time and compressive strength of steel slag-based cementitious materials

[0198]

[0199] A comparison of Example 1 and Comparative Example 1 shows that, during the carbonization of steel slag, the addition of an aluminum-containing activator can activate the carbonization carrier to release carbonate ions, thereby indirectly carbonizing the steel slag, which shortens the setting time of the product and improves its compressive strength. A comparison of Examples 1-3 shows that adjusting the amount of aluminum-containing activator can further affect the performance of the product.

[0200] A comparison of Examples 2 and 4 shows that using aragonite as the carbonization carrier, compared to using calcite, can improve the compressive strength of the product under essentially the same setting time. A comparison of Examples 1 and 5 shows that using aragonite as the carbonization carrier, compared to using calcite, can shorten the setting time and improve the compressive strength of the product. These results indicate that changing the type of carbonization carrier affects the final performance of the product. Without being bound by theory, it is speculated that the above results are due to the different reactivity of different crystal forms of calcium carbonate in the carbonization carrier. Unstable calcium carbonate such as aragonite / aragonite may accelerate the decomposition of the carbonization carrier in aluminum-containing alkaline solutions, thereby increasing the rate / degree of indirect carbonization reaction. Furthermore, some residual aragonite that has not been decomposed can also act as microfibers in the internal structure of steel slag, thus significantly improving the mechanical properties of the steel slag paste.

[0201] A comparison of Examples 1 and 6-8 shows that adding a water-reducing agent can improve the fluidity of the slurry, thereby reducing the amount of water used in the carbonation process. It can also significantly shorten the setting time of the product and improve its compressive strength. Furthermore, a comparison of Examples 6-8 shows that adjusting the amount of water-reducing agent can further affect the performance of the product, namely the setting time and compressive strength.

[0202] It should be noted that the embodiments described above are only for explaining the present invention and do not constitute any limitation on the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications with the same function.

Claims

1. A method for preparing steel slag-based cementitious materials, comprising: Steel slag is provided in powder form; The steel slag is mixed with a carbonization carrier, an aluminum-containing activator, water, and an optional water-reducing agent to obtain a slurry material; The slurry material is placed into a molding mold and shaped. After demolding, a rough blank is obtained. The rough billet is cured to obtain the steel slag-based cementitious material.

2. The method according to claim 1, characterized in that, The steel slag is converter steel slag; and / or, the particle size of the steel slag is not greater than 75 μm; and / or, the specific surface area of ​​the steel slag is not less than 300 m². 2 / kg.

3. The method according to claim 1 or 2, characterized in that, The carbonization carrier comprises one or more of calcite, aragonite, aragonite, and amorphous calcium carbonate; and / or, the content of one or more of calcite, aragonite, aragonite, and amorphous calcium carbonate in the carbonization carrier is not less than 50 wt%; and / or, the mass ratio of steel slag to carbonization carrier is (50-100):(10-50).

4. The method according to any one of claims 1-3, characterized in that, The carbonized support is prepared by the following method: Calcium-containing active materials are pulverized to obtain calcium-containing active powder; The calcium-containing active powder is mixed with a carbonization reaction solution, and carbon dioxide gas is introduced into it for carbonization treatment to obtain a suspension. The suspension was filtered, and the filtered product was dried to obtain the carbonized support.

5. The method according to any one of claims 1-4, characterized in that, The calcium-containing active material comprises one or more of the following: calcium oxide, calcium chloride, calcium hydroxide, dicalcium silicate, tricalcium silicate, hydrated calcium silicate, hydrated calcium aluminate, hydrated calcium aluminosilicate, hydrated calcium ferrite, hydrated calcium sulfoaluminate, and hydrated calcium fluoroaluminate; and / or the particle size of the calcium-containing active powder is not greater than 75 μm.

6. The method according to claim 4 or 5, characterized in that, The mass ratio of the calcium-containing active powder to the carbonization reaction solution is 1:(10-20); and / or, the reaction temperature of the carbonization treatment is 20-80℃; and / or, the reaction time of the carbonization treatment is 0.5-3 hours; and / or, the carbonization treatment is carried out at a stirring speed of 300-1000 rpm; and / or, the carbonization reaction solution includes one or more of the following: water, magnesium chloride solution, magnesium nitrate solution, sodium carbonate solution, sodium bicarbonate solution, ammonium nitrate solution, ammonium chloride solution, sodium hydroxide solution, potassium hydroxide solution, and ammonia solution.

7. The method according to any one of claims 1-6, characterized in that, The aluminum-containing activator includes, but is not limited to, sodium aluminate, potassium aluminate, aluminum hydroxide, and any combination thereof, or one or more of these; and / or, the mass ratio of the steel slag to the aluminum-containing activator is (50-100):(3-50).

8. The method according to any one of claims 1-7, characterized in that, The water-reducing agent includes one or more of polycarboxylate water-reducing agents, calcium lignosulfonate water-reducing agents, and aliphatic high-efficiency water-reducing agents; and / or, the mass ratio of the water-reducing agent to the sum of steel slag, carbonization carrier, and aluminum-containing activator is (0-3):

100.

9. The method according to any one of claims 1-8, characterized in that, The slurry material comprises: 50-100 parts steel slag, 10-50 parts carbonization carrier, 3-50 parts aluminum-containing activator, 15-60 parts water, and 0-3 parts water-reducing agent.

10. The method according to any one of claims 1-9, characterized in that, The curing humidity for the curing treatment is 30%-100%RH; and / or, the curing temperature is 20-80℃.

11. A steel slag-based cementitious material prepared by the method according to any one of claims 1-10.

12. The steel slag-based cementitious material according to claim 11, wherein the setting time of the steel slag-based cementitious material is not more than 50 min and the 28-day compressive strength is not less than 20 MPa.

13. Use of the method of any one of claims 1-10, the steel slag-based cementitious material prepared by the method of any one of claims 1-10, or the steel slag-based cementitious material of claim 11 or 12 in the production of concrete.

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