High solid waste utilization rate external wall self-insulation environment-friendly building block and preparation method thereof

Abstract

The application discloses a kind of high solid waste utilization rate outer wall self-insulation environmental protection block and preparation method thereof, especially suitable for the outer wall structure of low-rise building in severe cold area, with high compressive strength, low thermal conductivity, excellent frost resistance and safe environmental protection characteristics, including dense outer layer, transition layer and foamed core layer, the thickness of the foamed core layer 182mm, is the main body of heat preservation, closed porosity ≥80%, thermal conductivity ≤0.085W / (m·K);The transition layer is arranged outside the foamed core layer and each thickness is 3mm, for blocking thermal bridge, interface bonding strength ≥1.2MPa, thermal resistance value ≥0.15m²·K / W;The dense outer layer is arranged outside the transition layer and the thickness is 6mm, compressive strength ≥20MPa.The application realizes compressive strength ≥10MPa, thermal conductivity ≤0.085W / (m·K), solid waste utilization rate ≥80% by polymer recycled fiber reinforcement, layered composite design and CO2 carbonization process, block is adapted to severe cold to moderate climate zone, comprehensive cost is reduced by 40% compared with traditional external insulation system, with environmental protection, safety and economic benefits.

Description

Technical Field

[0001] This invention relates to the field of building materials technology, specifically to a high solid waste utilization rate self-insulating environmentally friendly building block for exterior walls and its preparation method, which is particularly suitable for the exterior wall structure of buildings in frigid regions, and has the characteristics of high compressive strength, low thermal conductivity, excellent frost resistance and safety and environmental protection. Background Technology

[0002] Self-insulating environmentally friendly blocks refer to a new type of wall material that integrates insulation function into the block body, eliminating the need for an additional external wall insulation layer to meet the building's energy-saving and insulation requirements. It is made from environmentally friendly raw materials or by-product resources and has advantages such as energy saving, environmental protection, and convenient construction.

[0003] Traditional exterior wall materials have the following problems:

[0004] 1. Performance imbalance: Insulation materials (such as polystyrene boards) have low strength (compressive strength ≤3MPa) and cannot bear weight; high-strength blocks (such as hollow concrete bricks) have high thermal conductivity (≥0.6 W / (m·K)) and require an additional external insulation layer, increasing construction costs by 35% (Ministry of Housing and Urban-Rural Development's "White Paper on the Economic Efficiency of External Wall Insulation" 2022), accompanied by a high incidence of common quality problems such as external wall cracking, hollowing, leakage, and even insulation layer detachment.

[0005] 2. Low solid waste utilization rate: The amount of construction waste in conventional blocks is less than 20%, and the performance of recycled aggregates is unstable, which easily leads to cracking.

[0006] 3. Health risks: Some materials (such as fiberglass) release harmful dust during processing, which may endanger human health.

[0007] 4. Insufficient durability: After freeze-thaw cycles, the mass loss rate is ≥8%, the water absorption rate is ≥10%, and the thermal insulation performance declines significantly after long-term use. Therefore, there is an urgent need to design a high solid waste utilization rate self-insulating environmentally friendly exterior wall block and its preparation method. Summary of the Invention

[0008] (a) Technical problems to be solved

[0009] To address the shortcomings of existing technologies, this invention provides an environmentally friendly self-insulating exterior wall block with high solid waste utilization rate, solving the problems of performance imbalance, low solid waste utilization rate, health risks, and insufficient durability in existing technologies.

[0010] (II) Technical Solution

[0011] To achieve the above objectives, the present invention provides the following technical solution: a high solid waste utilization rate self-insulating environmentally friendly exterior wall block, comprising a dense outer layer, a transition layer, and a foamed core layer. The foamed core layer is 182mm thick, serves as the main insulation layer, has a closed-cell rate ≥80%, and a thermal conductivity ≤0.085W / (m·K). The transition layer is disposed outside the foamed core layer and is 3mm thick, used to block thermal bridges, with an interfacial bonding strength ≥1.2MPa and a thermal resistance ≥0.15m²·K / W. The dense outer layer is disposed outside the transition layer and is 6mm thick, with a compressive strength ≥20MPa.

[0012] As a further preferred embodiment of the present invention, the mass percentage of the dense outer layer is:

[0013] 40-50% recycled coarse aggregate from 3-5mm construction waste;

[0014] S95 grade slag powder 25-35%;

[0015] Regenerated micro powder 15-25%;

[0016] Sodium methylsilicate waterproofing agent 0.5-1.5%;

[0017] Polypropylene fiber 3-5%.

[0018] As a further preferred embodiment of the present invention, the mass percentage of the transition layer is,

[0019] 35-45% fine aggregate from construction waste with a thickness of 0-1.5mm;

[0020] Inorganic lightweight aggregate 15-25%;

[0021] Polymer recycled fiber 6-9%;

[0022] Calcinated kaolin content: 12-22%;

[0023] Silane coupling agent 0.3-0.7%;

[0024] The remaining recycled micro powder;

[0025] The polymer recycled fiber is selected from recycled PET, PP or PA fiber, with a length ≤3mm and a tensile strength ≥300MPa; the fiber surface is modified with a silane coupling agent, and the coating amount is 0.3-0.7% of the fiber mass;

[0026] The inorganic lightweight aggregate is expanded vermiculite or vitrified microspheres with a particle size of 0.1-2 mm; the expanded vermiculite is calcined at a temperature of 800-1000℃ and has a specific surface area ≥5 m² / g.

[0027] As a further preferred embodiment of the present invention, the mass percentage of the foamed core layer is [value missing].

[0028] S95 grade slag powder 20-30%;

[0029] 35-45% recycled micro powder;

[0030] Expanded vitrified microspheres 10-20%;

[0031] H2O2 foaming agent 0.3-0.8%;

[0032] Silica fume 3-6%;

[0033] Alkali metal salt activators 1-2%.

[0034] As a further preferred embodiment of the present invention, the alkali metal salt activator is NaOH or KOH, the slag powder has a specific surface area ≥400m² / kg, and a 7-day activity index ≥95%; the recycled micro powder is a product of construction waste grinding, with a 45μm sieve residue ≤15%, a water requirement ratio ≤105%, and the mass ratio of the S95 grade slag powder to the recycled micro powder is 1:1.2-1:1.8.

[0035] As a further preferred embodiment of the present invention, the specific steps include the following steps.

[0036] S1, Raw material pretreatment:

[0037] Construction waste aggregates are acid-washed at a concentration of 3-7% for 1-3 hours to remove surface impurities. Polymer recycled fibers are pre-treated by cutting them to ≤3mm and then immersing them in a silane coupling agent solution at a concentration of 1-3% for 10-20 minutes; finally, they are dried at 60-80℃ until the moisture content is ≤1%.

[0038] S2, Layered molding:

[0039] Dense outer layer: The slurry is compacted by high-frequency vibration after wet mixing, 25-35Hz, 50-70s, pressure 0.05-0.15MPa;

[0040] Transition layer: High-pressure spraying at a pressure of 0.3MPa, followed by gentle vibration to remove bubbles;

[0041] Core layer: The core layer is foamed under low pressure, with a pressure of 0.05-0.1MPa and a rolling speed of 2-5m / min;

[0042] S3, Maintenance Process:

[0043] Steam curing: 70-85℃, 8-12h, humidity ≥90%;

[0044] Carbonization curing: CO2 carbonization curing, concentration 18-22%, 4-6 hours, pressure 0.1-0.2 MPa;

[0045] Natural care: Keep at room temperature for 28 days.

[0046] As a further preferred embodiment of the present invention, in step S3, during the carbonization curing process, CO2 carbonization is carried out in two stages: Stage 1: concentration 15-18%, pressure 0.1MPa, time 2h; Stage 2: concentration 20-25%, pressure 0.2MPa, time 4h; after carbonization curing, the surface CaCO3 generation rate is ≥60%, and the carbonization depth is ≥3mm.

[0047] (III) Beneficial Effects

[0048] This invention provides an environmentally friendly self-insulating exterior wall block with high solid waste utilization rate and its preparation method. It has the following beneficial effects:

[0049] I. Environmental Protection and Safety: Solid waste utilization rate ≥80% (recycled aggregate + slag + recycled PET fiber), annual disposal of 12,000 tons of construction waste per production line; meets green building material standards; safe and environmentally friendly: uses recycled PET fiber to replace glass fiber, avoiding dust hazards. The leachate of recycled PET fiber is free of heavy metals (GB / T 30810-2014), construction dust concentration ≤1mg / m³, and the carbon emission throughout the entire life cycle is 28kg CO2 / m³ (compared to 85kg CO2 / m³ in the traditional system), reducing carbon emissions by 67%, and reducing carbon emissions by 5,200 tons per 100,000㎡ of building area (equivalent to the annual carbon sequestration of 290,000 trees).

[0050] II. Carbon Reduction Benefits: Through high-component solid waste, application of recycled fibers, and CO2 carbonization curing process, the blocks achieve a total life-cycle carbon emission of ≤32kg CO2 / m³, which is 65-68% lower than traditional exterior wall systems. A single project (100,000 m² building) can reduce CO2 emissions by approximately 5,200 tons, equivalent to the annual carbon sequestration of planting 290,000 mature trees.

[0051] III. Construction and Durability Advantages, Shortened Construction Period: The one-piece molding process reduces 3 construction steps and shortens the construction period by 50%; Durability Guarantee: Strength retention rate ≥90% after 100 cycles of damp heat cycling (70℃ / 95%RH); Surface chalking grade ≤1 (ASTM D4214) after UV aging (QUV 2000h). Attached Figure Description

[0052] Figure 1 This is a schematic diagram of the cross-sectional structure of the block of the present invention;

[0053] Figure 2 This is a schematic diagram of the method flow of the present invention.

[0054] 1-Dense outer layer, 2-Transition layer, 3-Foamed core layer. Detailed Implementation

[0055] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0056] Please see Figure 1-2 This invention provides a technical solution: a high solid waste utilization rate self-insulating environmentally friendly exterior wall block, comprising a dense outer layer, a transition layer, and a foamed core layer. The foamed core layer is 182mm thick and serves as the main insulation layer, with a closed-cell rate ≥80% and a thermal conductivity ≤0.085W / (m·K). The transition layer is disposed outside the foamed core layer and is 3mm thick, used to block thermal bridges, with an interfacial bonding strength ≥1.2MPa and a thermal resistance ≥0.15m²·K / W. The dense outer layer is disposed outside the transition layer and is 6mm thick, with a compressive strength ≥20MPa.

[0057] The percentage of the dense outer layer mass is:

[0058] 40-50% recycled coarse aggregate from 3-5mm construction waste;

[0059] S95 grade slag powder 25-35%;

[0060] Regenerated micro powder 15-25%;

[0061] Sodium methylsilicate waterproofing agent 0.5-1.5%;

[0062] Polypropylene fiber 3-5%.

[0063] The transition layer mass percentage is,

[0064] 35-45% fine aggregate from construction waste with a thickness of 0-1.5mm;

[0065] Inorganic lightweight aggregate 15-25%;

[0066] Polymer recycled fiber 6-9%;

[0067] Calcinated kaolin content: 12-22%;

[0068] Silane coupling agent 0.3-0.7%;

[0069] The remaining recycled micro powder;

[0070] The polymer recycled fiber is selected from recycled PET, PP or PA fiber, with a length ≤3mm and a tensile strength ≥300MPa; the fiber surface is modified with a silane coupling agent, and the coating amount is 0.3-0.7% of the fiber mass;

[0071] The inorganic lightweight aggregate is expanded vermiculite or vitrified microspheres with a particle size of 0.1-2 mm. The expanded vermiculite is calcined at a temperature of 800-1000℃ and has a specific surface area ≥5 m² / g.

[0072] The mass percentage of the foamed core layer is,

[0073] S95 grade slag powder 20-30%;

[0074] 35-45% recycled micro powder;

[0075] Expanded vitrified microspheres 10-20%;

[0076] H2O2 foaming agent 0.3-0.8%;

[0077] Silica fume 3-6%;

[0078] Alkali metal salt activators 1-2%.

[0079] The alkali metal salt activator is NaOH or KOH, the specific surface area of ​​the slag powder is ≥400m² / kg, and the 7-day activity index is ≥95%; the recycled micro powder is the product of construction waste grinding, with ≤15% residue on a 45μm sieve, and a water requirement ratio of ≤105%. The mass ratio of S95 grade slag powder to recycled micro powder is 1:1.2-1:1.8.

[0080] A method for preparing a high-solid-waste-utilization-rate self-insulating environmentally friendly exterior wall block includes the following steps:

[0081] S1, Raw material pretreatment:

[0082] Construction waste aggregates are acid-washed at a concentration of 3-7% for 1-3 hours to remove surface impurities. Polymer recycled fibers are pre-treated by cutting them to ≤3mm and then immersing them in a silane coupling agent solution at a concentration of 1-3% for 10-20 minutes; finally, they are dried at 60-80℃ until the moisture content is ≤1%.

[0083] S2, Layered molding:

[0084] Dense outer layer: The slurry is compacted by high-frequency vibration after wet mixing, 25-35Hz, 50-70s, pressure 0.05-0.15MPa;

[0085] Transition layer: High-pressure spraying at a pressure of 0.3MPa, followed by gentle vibration to remove bubbles;

[0086] Core layer: The core layer is foamed under low pressure, with a pressure of 0.05-0.1MPa and a rolling speed of 2-5m / min;

[0087] S3, Maintenance Process:

[0088] Steam curing: 70-85℃, 8-12h, humidity ≥90%;

[0089] Carbonization curing: CO2 carbonization curing, concentration 18-22%, 4-6 hours, pressure 0.1-0.2 MPa;

[0090] Natural care: Keep at room temperature for 28 days.

[0091] In step S3, during the carbonization curing process, CO2 carbonization is carried out in two stages: Stage 1: concentration 15-18%, pressure 0.1MPa, time 2h; Stage 2: concentration 20-25%, pressure 0.2MPa, time 4h; After carbonization curing, the surface CaCO3 formation rate is ≥60%, and the carbonization depth is ≥3mm.

[0092] Example 1

[0093] Heavy-duty exterior wall blocks for frigid regions

[0094] Raw material pretreatment: Construction waste coarse aggregate (3-5mm) is soaked in 5% hydrochloric acid for 2 hours to remove mud impurities and heavy metal attachments, and then dried after washing for later use.

[0095] Polypropylene recycled fibers were cut to 2 mm, immersed in a 2% γ-aminopropyltriethoxysilane solution for 15 minutes, and dried until the moisture content was ≤1%.

[0096] Layered molding:

[0097] Percentage of mass of dense outer layer (6mm thick):

[0098] Recycled coarse aggregate from construction waste: 45%

[0099] S95 grade slag powder: 30%

[0100] Regenerated micro powder: 20%

[0101] Sodium methylsilicate waterproofing agent: 1%

[0102] Polypropylene fiber: 4%

[0103] After wet mixing, the mixture is compacted by high-frequency vibration at 30Hz for 60 seconds, and the molding pressure is 0.1MPa.

[0104] Transition layer (3mm thick) material mass percentage:

[0105] Construction waste fine aggregate (≤1.5mm): 40%

[0106] Expanded vermiculite (calcined at 900℃): 20%

[0107] Recycled polyester fiber: 8%, tensile strength approximately 380 MPa

[0108] Calcinated kaolin: 15%

[0109] Regenerated micro powder: 16.5%

[0110] Silane coupling agent (for fiber surface): 0.5%

[0111] High-pressure spraying molding, spraying pressure 0.3MPa;

[0112] Percentage of material mass of foamed core layer (182mm thick):

[0113] S95 slag powder: 25%

[0114] Regenerated micro powder: 40%

[0115] Expanded vitrified microspheres: 15%

[0116] Silica fume: 4%

[0117] H2O2 foaming agent: 0.5%

[0118] NaOH activator: 1.5%

[0119] The mixture is injected into the mold under low pressure, with a rolling speed of 4m / min and a closed-cell rate of 82%.

[0120] Maintenance process:

[0121] Steam curing: 80℃, 10h, humidity ≥95%;

[0122] Carbonization curing: CO2 concentration 20%, pressure 0.2MPa, 4h;

[0123] Natural care: 28 days;

[0124] The final surface CaCO3 formation rate reached 65%, with a carbonization depth of approximately 3.5 mm.

[0125] Performance testing:

[0126] Compressive strength: 12.2 MPa;

[0127] Heat transfer coefficient: 0.419 W / (m²·K);

[0128] Freeze-thaw mass loss: 4.2%. Calculations show that the carbon emission of the blocks in this embodiment is 28 kg CO2 / m³, of which 4.2 kg / m³ is carbon sequestration due to CO2 carbonization curing.

[0129] Example 2

[0130] Reinforced block products suitable for temperate climate zones and high-rise buildings, ideal for rainy southern environments:

[0131] Raw material ratio and processing:

[0132] Dense outer layer: 50% coarse aggregate, 25% S95 slag powder, 15% recycled micro powder, 1.2% waterproofing agent, 3.8% polypropylene fiber;

[0133] Transition layer: 45% fine aggregate from construction waste, 15% vitrified microspheres, 9% PET fiber (tensile strength > 320MPa), 13% calcined kaolin, 17% recycled micro powder, and 0.6% silane coupling agent;

[0134] Foamed core layer: 22% S95 slag powder, 40% recycled micro powder, 18% vitrified microspheres, 3% silica fume, 0.4% H2O2, 1.6% KOH;

[0135] Molding process:

[0136] Surface high-frequency vibration 32Hz, 55s;

[0137] High-pressure spraying of transition layer + rotary atomization device;

[0138] Core layer low-pressure injection + dynamic rheology control system;

[0139] Maintenance methods:

[0140] Steam curing: 75℃, 12h;

[0141] Carbonization curing has two stages:

[0142] Stage 1: Concentration 18%, pressure 0.1 MPa, 2 hours;

[0143] Stage 2: Concentration 23%, pressure 0.2 MPa, 4 hours;

[0144] The CaCO3 formation rate reached 62%, and the carbonization depth was 3.8 mm.

[0145] Example 3

[0146] Lightweight thermal insulation walls with high frost resistance are suitable for energy-efficient buildings in cold regions.

[0147] Raw material composition:

[0148] Dense outer layer:

[0149] Coarse aggregate 40%, slag powder 33%, recycled micro powder 20%, waterproofing agent 1.3%, polypropylene fiber 4.7%;

[0150] Transition layer: 38% fine aggregate for construction, 22% expanded vermiculite, 7% PP fiber (silane modified), 18% kaolin, 14% recycled micro powder, and 0.5% silane coupling agent;

[0151] Foamed core layer: 30% S95 slag powder, 36% recycled micro powder, 12% vitrified microspheres, 0.7% H2O2, 5% silica fume, 1.2% NaOH;

[0152] Process control:

[0153] The outer layer pressure is 0.15 MPa, and the high-frequency vibration is 35 Hz.

[0154] The core layer foaming pressure is controlled at 0.08 MPa, and the foaming time is 20 minutes;

[0155] The defoaming vibration of the transition layer is controlled at 15Hz for 30 seconds.

[0156] Maintenance parameters:

[0157] Steam curing: 85℃, 8 hours;

[0158] CO2 carbonization curing: concentration 21%, pressure 0.2MPa, 5h;

[0159] The surface CaCO3 deposition rate reached 68%, and the carbonization depth was 4.1 mm.

[0160] Performance comparison of this block with traditional exterior wall systems:

[0161]

[0162] Performance Breakthrough:

[0163] Compressive strength ≥10MPa, meeting the load-bearing requirements of low-rise buildings;

[0164] The heat transfer coefficient is ≤0.45 W / (m²·K), and no additional external insulation layer is required;

[0165] Excellent freeze resistance: mass loss ≤5% after 50 freeze-thaw cycles;

[0166] Fire resistance limit ≥2.5h (ISO 834).

[0167] Cost optimization

[0168]

[0169] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0170] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A high-solid-waste-utilization-rate self-insulating environmentally friendly exterior wall block, characterized in that: It comprises a dense outer layer, a transition layer, and a foamed core layer. The foamed core layer is 182 mm thick and serves as the main insulation layer, with a closed-cell rate ≥80% and a thermal conductivity ≤0.085 W / (m·K). The transition layer is located outside the foamed core layer and is 3 mm thick, used to block thermal bridges, with an interfacial bonding strength ≥1.2 MPa and a thermal resistance ≥0.15 m²·K / W. The dense outer layer is located outside the transition layer and is 6 mm thick, with a compressive strength ≥20 MPa. The mass percentage of the transition layer is, 35-45% fine aggregate from construction waste with a thickness of 0-1.5mm; Inorganic lightweight aggregate 15-25%; Polymer recycled fiber 6-9%; Calcinated kaolin content: 12-22%; Silane coupling agent 0.3-0.7%; The remaining recycled micro powder; The polymer recycled fiber is selected from recycled PET, PP or PA fiber, with a length ≤3mm and a tensile strength ≥300MPa; the fiber surface is modified with a silane coupling agent, and the coating amount is 0.3-0.7% of the fiber mass; the inorganic lightweight aggregate is expanded vermiculite or vitrified microspheres with a particle size of 0.1-2mm; the expanded vermiculite is calcined at a temperature of 800-1000℃ and has a specific surface area ≥5m² / g.

2. The high solid waste utilization rate self-insulation environment-friendly exterior wall building block according to claim 1, characterized in that: The mass percentage of the dense outer layer is: 40-50% recycled coarse aggregate from 3-5mm construction waste; S95 grade slag powder 25-35%; Regenerated micro powder 15-25%; Sodium methylsilicate waterproofing agent 0.5-1.5%; Polypropylene fiber 3-5%.

3. The high solid waste utilization rate self-insulation environment-friendly exterior wall building block according to claim 1, characterized in that: The mass percentage of the foamed core layer is: S95 grade slag powder 20-30%; 35-45% recycled micro powder; Expanded vitrified microspheres 10-20%; H2O2 foaming agent 0.3-0.8%; Silica fume 3-6%; Alkali metal salt activators 1-2%.

4. The high solid waste utilization rate self-insulation environment-friendly exterior wall building block according to claim 3, characterized in that: The alkali metal salt activator is NaOH or KOH, the slag powder has a specific surface area ≥400m² / kg, and a 7-day activity index ≥95%; the recycled micro powder is a product of construction waste grinding, with a 45μm sieve residue ≤15%, a water requirement ratio ≤105%, and the mass ratio of the S95 grade slag powder to the recycled micro powder is 1:1.2-1:1.

8.

5. A method for preparing the high solid waste utilization rate self-insulation environment-friendly exterior wall building block according to any one of claims 1-4, characterized in that: The specific steps include the following: S1, Raw material pretreatment: Construction waste aggregates are acid-washed with an acid concentration of 3-7% for 1-3 hours to remove surface impurities. Pretreatment of polymer regenerated fibers: After cutting to ≤3mm, immerse in a silane coupling agent solution with a concentration of 1-3% for 10-20 minutes; Dry at 60-80℃ until the moisture content is ≤1%; S2, Layered molding: Dense outer layer: The slurry is compacted by high-frequency vibration after wet mixing, 25-35Hz, 50-70s, pressure 0.05-0.15MPa; Transition layer: High-pressure spraying at a pressure of 0.3MPa, followed by gentle vibration to remove bubbles; Core layer: The core layer is foamed under low pressure, with a pressure of 0.05-0.1MPa and a rolling speed of 2-5m / min; S3, Maintenance Process: Steam curing: 70-85℃, 8-12h, humidity ≥90%; Carbonization curing: CO2 carbonization curing, concentration 18-22%, 4-6 hours, pressure 0.1-0.2 MPa; Natural care: Keep at room temperature for 28 days.

6. The method for preparing a high solid waste utilization rate self-insulating environmentally friendly exterior wall block according to claim 5, characterized in that: In step S3, during the carbonization curing process, CO2 carbonization is carried out in two stages: Stage 1: concentration 15-18%, pressure 0.1MPa, time 2h; Stage 2: concentration 20-25%, pressure 0.2MPa, time 4h; After carbonization curing, the surface CaCO3 formation rate is ≥60%, and the carbonization depth is ≥3mm.

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