Low-carbon environment-friendly geopolymer sleeve grouting material as well as preparation method and application method thereof

Abstract

The invention belongs to the technical field of grouting materials, and particularly relates to a low-carbon environment-friendly geopolymer sleeve grouting material as well as a preparation method and an application method thereof. The grouting material comprises the following components in parts by weight: a solid waste-based cementing material system: 250-300 parts of F-type fly ash, 150-200 parts of S95-grade granulated blast furnace slag micro powder, 80-120 parts of construction waste regenerated micro powder and 30-50 parts of metakaolin; an alkali activator system: 80-120 parts of solid sodium silicate, 15-25 parts of solid sodium hydroxide, 5-10 parts of potassium carbonate, and 20-35 parts of nano silica sol; the early strength synergistic component comprises the following components in parts by weight: 3-6 parts of nano C-S-H seed crystal, 2-4 parts of aluminum sulfate and 1.5-2.5 parts of triethanolamine; an aggregate and admixture system: 400-500 parts of graded quartz sand, 4-6 parts of a polycarboxylate superplasticizer, 12-18 parts of a composite expanding agent, 0.8-1.2 parts of polypropylene fiber, and 25-8 parts of nano SiO2; and the CO2 mineralization component comprises 15-25 parts of calcium silicate and 8-12 parts of magnesium oxide. According to the low-carbon environment-friendly geopolymer sleeve grouting material as well as the preparation method and the application method thereof, on the premise that excellent construction performance and mechanical performance are guaranteed, carbon emission is reduced by 70% or above, and active carbon sequestration capacity is achieved.

Description

Technical Field

[0001] This invention belongs to the field of grouting material technology, and specifically relates to a low-carbon and environmentally friendly geopolymer sleeve grouting material and its preparation and application methods. Background Technology

[0002] Grouting materials for steel bar connection sleeves in prefabricated buildings need to meet multiple requirements, including good workability, high early strength, and strong long-term durability. At the same time, the construction industry urgently needs to reduce carbon emissions. This invention proposes solutions to the following core problems: 1. Carbon emissions issue: The carbon emission intensity of traditional cement-based grouting materials is as high as 0.8-1.0 kgCO2 / kg, mainly due to: the release of a large amount of CO2 during the calcination of limestone in the production of silicate cement; the consumption of a large amount of fossil energy during high-temperature calcination (1450°C); and the surge in the use of grouting materials due to the promotion of prefabricated buildings, resulting in a continuous increase in total carbon emissions.

[0003] 2. Performance balance issue: Existing low-carbon alternative materials (such as cement with high fly ash content) have performance defects: slow early strength development, with 24-hour compressive strength often below 50 MPa, which does not meet the requirements for rapid construction; poor fluidity retention, with fluidity loss exceeding 20% ​​within 30 minutes; and unstable micro-expansion performance, making it difficult to ensure effective connection between the sleeve and the reinforcing bar.

[0004] 3. Low utilization rate of industrial solid waste: Currently, the amount of industrial solid waste (fly ash, slag) in sleeve grouting materials is usually no more than 30%, resulting in a large amount of solid waste not being effectively utilized, causing resource waste and environmental pressure.

[0005] 4. Lack of active carbon sequestration mechanisms: Existing materials only passively reduce carbon by reducing cement usage, lacking the ability to actively absorb and fix CO2 during use, thus failing to fully realize the carbon sequestration potential of the materials.

[0006] 5. Cost versus performance conflict: Low-carbon materials often require the addition of expensive additives to compensate for performance issues, leading to an increase in overall costs rather than a decrease, which limits their widespread application. Summary of the Invention

[0007] In order to solve the above-mentioned problems in the existing technology, the purpose of this invention is to provide a low-carbon and environmentally friendly geopolymer sleeve grouting material and its preparation and application methods, which can reduce carbon emissions by more than 70% while ensuring excellent construction performance and mechanical properties, and has the ability to actively fix carbon.

[0008] The technical solution adopted in this invention is as follows: A low-carbon, environmentally friendly geopolymer sleeve grouting material, comprising the following components by weight: Solid waste-based cementitious material system: 250-300 parts of F-type fly ash, 150-200 parts of S95 grade granulated blast furnace slag powder, 80-120 parts of recycled construction waste powder, and 30-50 parts of metakaolin. Alkali activator system: 80-120 parts solid sodium silicate, 15-25 parts solid sodium hydroxide, 5-10 parts potassium carbonate, and 20-35 parts nano silica sol; Early-strength synergistic components: 3-6 parts nano-CSH seed crystals, 2-4 parts aluminum sulfate, and 1.5-2.5 parts triethanolamine; Aggregate and admixture system: 400-500 parts graded quartz sand, 4-6 parts polycarboxylate superplasticizer, 12-18 parts composite expansion agent, 0.8-1.2 parts polypropylene fiber, and 5-8 parts nano-SiO2; CO2 mineralization components: 15-25 parts calcium silicate, 8-12 parts magnesium oxide.

[0009] As a preferred embodiment of the present invention, the fineness of the F-type fly ash is <15μm; the specific surface area of ​​the S95 grade granulated blast furnace slag powder is 400-450m². 2 / kg; Specific surface area of ​​recycled construction waste powder ≥450m² 2 / kg; the al2O3 content in metakaolin is ≥38%, the SiO2 content is ≥50%, and the specific surface area of ​​metakaolin is ≥12000m². 2 / kg.

[0010] As a preferred embodiment of the present invention, the solid sodium silicate has a SiO2 / Na2O molar ratio of 2.0-2.5, a water content of <5%, a purity of ≥96%, and a nano-silica sol with a SiO2 content of 30%, a particle size of 10-20 nm, and a pH of 9-10.

[0011] As a preferred embodiment of the present invention, the nano-CSH seed crystals have a particle size of <50nm and a Ca / Si molar ratio of 0.8-1.2.

[0012] As a preferred embodiment of the present invention, the graded quartz sand has a particle size range of 0.3-2.0 mm; the polycarboxylate superplasticizer has a water reduction rate ≥30%, a solid content of 40%, and a pH of 6-8; the composite expanding agent comprises 60% magnesium expanding agent and 40% calcium sulfoaluminate by weight; the polypropylene fiber has a length of 12 mm, a diameter of 20-30 μm, and a tensile strength ≥350 MPa; the nano-SiO2 has a particle size of 7-15 nm and a specific surface area of ​​200±25 m². 2 / kg, purity ≥99.8%.

[0013] As a preferred embodiment of the present invention, the citric acid activity in the magnesium oxide is ≥60 seconds.

[0014] A method for preparing a low-carbon and environmentally friendly geopolymer sleeve grouting material includes the following steps: S1: Pre-prepared alkaline activator: Weigh out solid sodium silicate, sodium hydroxide, and potassium carbonate according to the formula; put them into a planetary mixer and dry mix for 10 minutes until uniform; slowly add nano silica sol while stirring; transfer the mixture to an oven and dry at 50-60°C for 6-8 hours; crush and sieve to obtain solid alkali activator particles with a particle size <5mm; seal and package to prevent moisture absorption; S2: Solid waste pretreatment: Combined grinding of fly ash, slag, and recycled micro powder: Ingredients are proportioned by weight: fly ash 50-55%, slag 30-35%, recycled micro powder 15-20%; fed into a ball mill, with a grinding aid dosage of 0.05%; ground to a specific surface area ≥400 m². 2 / kg; Particle size distribution: <10μm accounts for 60%, <20μm accounts for 85%; Iron removal treatment: removes metal impurities by magnetic separation; Preparation of metakaolin: Kaolin is dried to remove surface water; it is then placed in a rotary kiln and calcined at 800°C for 2 hours; it loses structural water and transforms into metakaolin; it is rapidly cooled to room temperature and pulverized to a specific surface area ≥12000 m². 2 / kg; Activity test: Reactivity index with Ca(OH)2 ≥90%; S3: Dry Mixture Preparation: The first stage is the mixing of the main materials: Weigh the solid waste cementitious material and graded quartz sand according to the formula; put them into a forced mixer; add polypropylene fiber and stir at low speed; mix for 20 minutes until the color is uniform and the fiber is dispersed; The second stage involves the incorporation of activators: adding pre-prepared solid alkali activators; adding early-strength enhancing components; adding CO2 mineralization components; and stirring at medium speed for 10 minutes. The third stage is the mixing of additives: premix the polycarboxylate superplasticizer, composite expansion agent and a small amount of sand; add them to the main material; add nano SiO2; stir at high speed for 5 minutes.

[0015] As a preferred embodiment of the present invention, the preparation method of the present invention further includes the following steps: S4: Quality Inspection Sampling and uniformity testing: chloride ion content deviation ≤0.01%, fineness deviation ≤5%; moisture content <0.5%; appearance: grayish-green powder, no lumps; S5: Packaging and Storage: The packaging uses a three-layer composite bag consisting of an outer PE layer, a middle aluminum foil layer, and an inner PP layer; each bag weighs 25kg or 50kg; store in a dry and ventilated place, with a shelf life of 6 months.

[0016] A method for applying a low-carbon, environmentally friendly geopolymer sleeve grouting material includes the following steps: Y1: Mixing preparation: Construction ambient temperature 5-35°C, relative humidity ≤85%; prepare a forced mixer or electric drill + mixing head; water temperature control: 5-10°C in summer, 20-30°C in winter; Y2: Add water and mix: water-to-material mass ratio: 0.12-0.15; first add 70% water, then add the dry mix and mix for 3 minutes; add the remaining 30% water and continue mixing for 5-7 minutes; total mixing time is 8-10 minutes, until the slurry is uniform and free of particles; Y3: Flowability test: Measure the flowability on the swivel table; the initial flowability should be ≥340mm; the flowability after 30 minutes should be ≥320mm. Y4: Sleeve grouting operation: Clean the inner wall of the sleeve to remove oil and debris; slowly inject grout through the grouting hole at a speed of about 1-2L / min; after filling, overflow the grout from the vent hole to confirm fullness; seal the grouting hole and vent hole. Y5: CO2 curing process: 0-1h: CO2 concentration gradually increases to 20%, relative humidity increases to 70%; 1-5h: maintain stable CO2 concentration, pressure, and humidity; 5-6h: slowly reduce CO2 concentration to 5%, depressurize; end curing, remove the device; Y6: Subsequent maintenance: After CO2 curing, proceed to standard curing; cover with plastic film to retain moisture for 7 days; temperature 20±2°C, relative humidity ≥95%; curing until the designed age.

[0017] As a preferred embodiment of the present invention, in step Y5: Curing time: Let stand for 2 hours after grouting is completed; Curing equipment: Uses CO2 curing hoods or curing boxes to seal the sleeve area; equipped with a CO2 supply system; equipped with a humidity control system; Maintenance parameters: CO2 volume fraction concentration: 20%; pressure: 0.1-0.2 MPa; relative humidity: 60-75%; temperature: 20±5°C; maintenance time: 3-6 hours.

[0018] The beneficial effects of this invention are as follows: 1. This invention significantly reduces carbon emissions: achieving a reduction to 0.15-0.25 kg CO2 / kg, a 70-80% reduction compared to traditional materials; through alkali activation technology, cement usage is reduced to near zero; industrial solid waste utilization rate is increased to over 85%; combined with CO2 mineralization curing, active carbon sequestration of 50-80 kg CO2 / m³ is achieved. 3 .

[0019] 2. This invention guarantees excellent construction performance: the fluidity remains ≥320mm after 3 hours, meeting the requirements for long-term construction; it has good self-flowability and requires no vibration; there is no bleeding or segregation; and it is suitable for construction temperature ranges of 5-40°C.

[0020] 3. This invention meets the requirements for high early strength: through the synergistic effect of nano CSH seed crystals and early strength agent, the compressive strength at 24 hours is ≥65 MPa; the strength at 3 days is ≥80 MPa, meeting the requirements for rapid construction; and the strength at 28 days is ≥100 MPa, ensuring long-term performance.

[0021] 4. This invention achieves high durability: the chloride ion permeability coefficient is <800°C, which is superior to traditional cement-based materials; the dense microstructure provides good resistance to freeze-thaw cycles; it does not corrode steel bars and meets the 50-year design service life requirement.

[0022] 5. This invention can reduce overall costs: the extensive use of industrial solid waste reduces raw material costs; solid alkali activators are easy to transport and use; overall costs are reduced by 15-20%, improving economic competitiveness.

[0023] 6. This invention innovates the CO2 curing process: it develops a CO2 curing method suitable for sleeve grouting; the curing time is shortened to 3-6 hours; and it achieves the dual effects of carbon fixation and performance improvement. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the geopolymerization reaction mechanism; Figure 2 This is a maintenance diagram; Figure 3 This is a schematic diagram of the carbonation reaction pathway; Figure 4 It is a time curve of compressive strength; Figure 5 It is a flowability retention curve; Figure 6 This is a comparison chart of carbon emissions throughout the entire life cycle. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0026] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention. It should be noted that, unless otherwise specified, the embodiments and features described in the embodiments of the invention can be combined with each other.

[0027] I. Overall Technical Concept This invention adopts a three-pronged technical approach of "geopolymer gelation + nano-regulation + CO2 mineralization curing", with the core idea being: Polymer-based cement replacement in solid waste bases: Polymer gels formed from industrial solid wastes such as alkali-activated fly ash, slag, and recycled construction waste powder are used as the main cementing material.

[0028] Nanocrystal seed-induced rapid reaction: Adding nano-CSH seeds as nucleation centers accelerates the polymerization reaction and hydration process.

[0029] Solid alkali activators are easy to use: they adopt a solid sodium silicate + sodium hydroxide system, avoiding the inconvenience of transportation and use caused by liquid alkali.

[0030] 1. CO2 mineralization synergistic curing: CO2 curing is carried out after grouting. On the one hand, CO2 is solidified to reduce the carbon footprint, and on the other hand, the generated carbonates provide additional strength.

[0031] 2. Multi-component synergistic enhancement: The synergistic effect of multiple functional components such as composite expander, fiber, and nano-SiO2 comprehensively improves performance.

[0032] II. Material Composition and Formula 2.1 Solid waste-based cementitious material system (total 430-570 parts) This system is the core cementitious source for the material, completely replacing traditional silicate cement: Class F fly ash (250-300 parts): Technical specifications: Fineness <15μm percentage ≥80%, SiO2+Al2O3+Fe2O3 ≥70%, Loss on ignition ≤5%; Mechanism of action: Provides active aluminosilicates, which form a geopolymer gel under alkali activation; spherical particles improve flowability; low water requirement.

[0033] Reasons for selection: Type F fly ash has low CaO content (<10%), controllable reaction rate, and stable product.

[0034] S95 grade granulated blast furnace slag powder (150-200 parts): Technical specifications: Specific surface area 400-450 m²2 / kg, activity index ≥75% after 7 days and ≥95% after 28 days.

[0035] Mechanism of action: High CaO content (35-45%) rapidly generates CSH gel after alkali activation; contributes significantly to early strength; reacts synergistically with fly ash to form a dense structure; dosage control: 35-40% to balance early strength and later strength development.

[0036] Recycled construction waste powder (80-120 parts): Technical specifications: Specific surface area ≥ 450 m² 2 / kg, the main component is the product of crushing and grinding waste concrete.

[0037] Mechanism of action: Contains unhydrated cement particles, which have secondary hydration activity; provides additional calcium source and silicate; micro-filling effect, which improves density.

[0038] Environmental significance: Resource utilization is of great importance.

[0039] Metakaolin (30-50 parts): Preparation process: Kaolin is obtained by calcining at 800°C for 2 hours.

[0040] Technical specifications: Al2O3 content ≥38%, SiO2 content ≥50%, specific surface area ≥12000 m² 2 / kg.

[0041] Mechanism of action: It provides a highly active aluminum source, promoting the formation of geopolymer networks; after the layered structure of metakaolinite disintegrates, the Si-O and Al-O bonds are easily broken, resulting in extremely high reactivity; it improves early strength and structural compactness.

[0042] Dosage notes: Although metakaolin has a higher cost, it only accounts for 5-8% of the total cost and has a limited impact on the overall cost.

[0043] 2.2 Alkali activator system (total 120-180 parts) Alkali activators are key to initiating solid waste water treatment and geopolymerization reactions.

[0044] Solid sodium silicate (80-120 parts): Technical parameters: Modulus (SiO2 / Na2O molar ratio) = 2.0-2.5, moisture content <5%.

[0045] Mechanism of action: Provides an alkaline environment (pH>13) to promote the dissolution of aluminosilicates; provides soluble silicates to participate in the polymerization reaction; the modulus of 2.0-2.5 balances solubility and degree of polymerization.

[0046] Solidification advantages: easy to transport and store, no special protection required; simple to use, just add water to dissolve; avoids the problems of high viscosity and easy pipe blockage of liquid water glass.

[0047] Solid sodium hydroxide (15-25 parts): Specifications: Industrial grade, purity ≥96%, in flakes or granules.

[0048] Mechanism of action: Provides a strongly alkaline environment, accelerating the dissolution of solid waste; replenishes sodium. + Balances the negative charge in the polymer structure; synergistically with sodium silicate, it regulates the basicity and modulus of the activator.

[0049] Dosage control: Excessive dosage will lead to alkaline corrosion and subsequent efflorescence. The preferred dosage is 3-5%.

[0050] Potassium carbonate (5-10 parts): Mechanism of action: Slow-release alkali source, prolonging the alkali activation time; provides potassium. + Ions, optimizing the microstructure of geopolymers; K + Radius smaller than Na + It is easier to enter the polymer framework and improve structural stability.

[0051] Synergistic effect: When combined with Na-based activators, it improves rheological properties.

[0052] Nano silica sol (20-35 parts): Technical parameters: SiO2 content 30%, particle size 10-20nm, pH=9-10.

[0053] Mechanism of action: It provides a highly active nanoscale silicon source that rapidly participates in the reaction; it acts as a nucleation site to induce the growth of geopolymer gels; and it fills nanoscale pores to create a dense microstructure.

[0054] Dispersibility: In hydrosol form, it is uniformly dispersed in the system.

[0055] 2.3 Early-strength synergistic components (total 6.5-12.5 parts) This component system addresses the problem of low early strength in geopolymers.

[0056] Nano CSH seed crystals (3-6 parts): Preparation method: It is prepared by chemical precipitation method, which involves the reaction of CaCl2 and Na2SiO3.

[0057] Technical parameters: Particle size <50nm, Ca / Si molar ratio = 0.8-1.2.

[0058] Mechanism of action: Provides a large number of nucleation centers and lowers the nucleation barrier; induces rapid precipitation and growth of CSH gel; accelerates polymerization reaction and slag hydration.

[0059] Effect: Strength increases by 30-40% within 24 hours after addition.

[0060] Aluminum sulfate (2-4 parts): Mechanism of action: Aluminum ions promote the formation of geopolymer networks; sulfate ions react with calcium ions to form gypsum (ettringite), contributing to early strength; and the setting time is regulated to avoid being too fast or too slow.

[0061] Dosage control: Excessive dosage will cause expansion and cracking; 2-3% is preferred.

[0062] Triethanolamine (1.5-2.5 parts): Chemical formula: N(CH2CH2OH)3.

[0063] Mechanism of action: Strongly promotes the hydration of C3S and C3A; complexes Ca²⁺ + It promotes CSH gel formation; in synergy with aluminum sulfate, it significantly enhances early strength.

[0064] Composite effect: The triethanolamine + aluminum sulfate system can increase the strength by 40-50% in 24 hours.

[0065] 2.4 Aggregate and Admixture System (Total 422-532 parts) Graded quartz sand (400-500 parts): Particle size range: 0.3-2.0mm, using continuous gradation.

[0066] Grading scheme: 0.3-0.6mm: 20%; 0.6-1.18mm: 40%; 1.18-2.0mm: 40%.

[0067] Technical requirements: SiO2 content ≥96%, mud content ≤1%, mud lump content ≤0.5%.

[0068] Functions: Provides skeletal support, reduces shrinkage, optimizes gradation, and increases density. Polycarboxylate superplasticizer (4-6 parts): Technical specifications: Water reduction rate ≥30%, solid content 40%, pH=6-8.

[0069] Molecular design: The main chain is acrylic acid, and the side chain is polyoxyethylene ether (PEO).

[0070] Mechanism of action: The main chain carboxyl groups are adsorbed on the surface of solid waste particles; the side chain PEO provides steric hindrance to prevent particle agglomeration; and free water is released to improve fluidity.

[0071] Dosage optimization: The fluidity is optimal at 4-6%, and further increases have no significant effect.

[0072] Composite expanding agent (12-18 parts): Composition: 60% magnesium expander (MgO) + 40% calcium sulfoaluminate.

[0073] Mechanism of action: MgO hydrates to form Mg(OH)2, which expands in volume by about 2.5 times, compensating for shrinkage; calcium sulfoaluminate reacts with gypsum to form ettringite (AFt), which also expands in volume; the combined use achieves early plastic expansion + later hardening expansion.

[0074] Expansion rate control: 0.02-0.04% vertical expansion rate for 1 day, and 0.04-0.06% for 28 days.

[0075] Polypropylene fiber (0.8-1.2 parts): Specifications: Length 12mm, diameter 20-30μm, tensile strength ≥350Mpa.

[0076] Functions: It inhibits cracking and controls plastic shrinkage cracks; it bridges microcracks and improves toughness; it improves impact resistance.

[0077] Dispersibility: After surface treatment, it disperses well in alkaline environments.

[0078] Nano SiO2 (5-8 parts): Type: Hydrophilic fumed silica.

[0079] Technical parameters: Particle size 7-15nm, specific surface area 200±25m² 2 / kg, purity ≥99.8%.

[0080] Mechanism of action: Nanofilling effect, clogging capillaries; promoting volcanic ash effect, consuming Ca(OH)2; increasing density, reducing permeability.

[0081] Dispersion treatment: Premix with water-reducing agent and disperse using ultrasound for 30 minutes.

[0082] 2.5CO2 mineralization components (total 23-37 parts) This is the innovative highlight of the invention, enabling active carbon sequestration.

[0083] Calcium silicate (β-C2S) (15-25 parts): Source: Extracted from steel slag or chemically synthesized.

[0084] Chemical formula: 2CaO·SiO2.

[0085] Mechanism of action: Reaction with CO2: 2CaO·SiO2 + 2CO2 → 2CaCO3 + SiO2; CaCO3 microcrystals formed after carbonation fill the pores; SiO2 gel participates in the polymerization reaction.

[0086] Carbon fixation effect: The theoretical carbon fixation amount of each β-C2S is 0.51 parts.

[0087] Magnesium oxide (lightly calcined) (8-12 parts): Preparation: Magnesite is obtained by calcination at 800-1000°C.

[0088] Activity index: Citric acid activity ≥ 60 seconds.

[0089] Mechanism of action: Reaction with CO2: MgO + CO2 → MgCO3; slow hydration to generate Mg(OH)2, long-term expansion to compensate for contraction; carbonation products provide strength.

[0090] Carbon fixation effect: The theoretical carbon fixation amount of each part of MgO is 1.1 parts.

[0091] Synergistic effect: β-C2S and MgO react synergistically in a CO2-cured environment; the generated carbonate network combines with geopolymer gel to form a dense structure; the total carbon fixation capacity can reach 50-80 kg CO2 / m³. 3 Material.

[0092] III. Preparation Process Flow 3.1 Preparation of Alkali Activator (Step 1) Operating procedure: 1. Weigh out solid sodium silicate, sodium hydroxide, and potassium carbonate according to the formula; 2. Put them into a planetary mixer and dry mix for 10 minutes until uniform; 3. Slowly add nano silica sol while stirring, mixing continuously; 4. Transfer the mixture to an oven and dry at 50-60°C for 6-8 hours; 5. Crush and sieve to obtain solid alkali activator particles with a particle size <5mm; 6. Seal and package to prevent moisture absorption.

[0093] Key process points: The drying temperature should not be too high to prevent sodium silicate from dehydrating and denaturing; nano-silica sol should be added in batches to prevent local agglomeration; the moisture content of the finished product should be controlled at 3-5%.

[0094] Quality inspection: Modulus determination: 2.0-2.5; pH value (10% solution): 13-14; Appearance: grayish-white granules, no lumps.

[0095] 3.2 Solid waste pretreatment (step 2) Combined grinding of fly ash, slag, and recycled powder: 1. Proportioning: fly ash 50-55%, slag 30-35%, recycled powder 15-20%; 2. Feeding into a ball mill, with a grinding aid (triethanolamine) dosage of 0.05%; 3. Grinding until a specific surface area ≥ 400 m². 2 / kg (Blazinger process); 4. Particle size distribution: <10μm accounts for 60%, <20μm accounts for 85%; 5. Iron removal treatment: remove metal impurities by magnetic separation.

[0096] Preparation of metakaolin: 1. Dry kaolin (Al2O3·2SiO2·2H2O) to remove surface water; 2. Place in a rotary kiln and calcine at 800°C for 2 hours; 3. Lose structural water and transform into metakaolin (Al2O3·2SiO2); 4. Rapidly cool to room temperature and pulverize to a specific surface area ≥12000 m². 2 / kg; 5. Activity test: Reactivity index with Ca(OH)2 ≥90%.

[0097] Quality control: fly ash water requirement ratio ≤ 95%; slag activity index ≥ 75% at 7d and ≥ 95% at 28d; metakaolin purity: Al2O3 ≥ 38%, SiO2 ≥ 50%.

[0098] 3.3 Dry Mixture Preparation (Step 3) Phase 1: Mixing of main materials (20 minutes): 1. Weigh solid waste cementitious materials and graded quartz sand according to the formula; 2. Put them into a forced mixer (twin-shaft or planetary type); 3. Add polypropylene fibers and stir at low speed (60 rpm); 4. Mix for 20 minutes until the color is uniform and the fibers are dispersed.

[0099] Second stage: Activator incorporation (10 minutes): 1. Add pre-prepared solid alkali activator; 2. Add early strength enhancing components (nano CSH seed crystals, aluminum sulfate, triethanolamine); 3. Add CO2 mineralization components (β-C2S, MgO); 4. Stir at medium speed (100 rpm) for 10 minutes.

[0100] Third stage: Mixing of admixtures (5 minutes): 1. Premix polycarboxylate superplasticizer, composite expansion agent and a small amount of sand; 2. Add to the main material; 3. Add nano SiO2 (pre-dispersed with superplasticizer); 4. Stir at high speed (150 rpm) for 5 minutes.

[0101] Total mixing time: 35 minutes.

[0102] Quality inspection: Sampling and uniformity testing: chloride ion content deviation ≤0.01%, fineness deviation ≤5%; moisture content <0.5%; appearance: gray-green powder, no lumps.

[0103] Packaging and storage: Three-layer composite packaging bag (outer layer PE + middle layer aluminum foil + inner layer PP); 25kg or 50kg per bag; store in a dry and ventilated place, shelf life 6 months.

[0104] 3.4 On-site application and CO2 curing (Step 4) Preparation for mixing: 1. Construction environment temperature: 5-35°C, relative humidity: ≤85%; 2. Prepare a forced mixer (capacity ≥30L) or a hand drill + mixing head; 3. Water temperature control: 5-10°C in summer, 20-30°C in winter.

[0105] Add water and stir: 1. Water-to-material ratio: 0.12-0.15 (mass ratio): Ambient temperature <15°C: 0.15; Ambient temperature 15-25°C: 0.13-0.14; Ambient temperature >25°C: 0.12-0.13; 2. First add 70% water, then add the dry mixture and stir for 3 minutes; 3. Add the remaining 30% of water and continue stirring for 5-7 minutes; 4. The total stirring time is 8-10 minutes, until the slurry is uniform and free of particles.

[0106] Flowability test: Measure the flowability on the swivel table according to GB / T2419 method; the initial flowability should be ≥340mm; the flowability after 30 minutes should be ≥320mm.

[0107] Sleeve grouting operation: 1. Clean the inner wall of the sleeve to remove oil and debris; 2. Slowly inject grout through the grouting hole at a speed of about 1-2 L / min; 3. After filling, overflow the grout from the vent hole to confirm fullness; 4. Seal the grouting hole and vent hole.

[0108] CO2 curing process (key innovation): 1. Curing time: After grouting is completed, let it stand for 2 hours (when the material has initially set).

[0109] 2. Curing equipment: Use CO2 curing hoods or curing boxes to seal the sleeve area; equipped with a CO2 supply system (cylinder + pressure reducing valve + flow meter); equipped with a humidity control system (spray humidification).

[0110] 3. Curing parameters: CO2 concentration: 20% (volume fraction); pressure: 0.1-0.2MPa (slight positive pressure to prevent air infiltration); relative humidity: 60-75% (CO2 dissolves in the water film to promote the reaction); temperature: 20±5°C; curing time: 3-6 hours.

[0111] 4. Process flow: 0-1h: CO2 concentration gradually increases to 20%, relative humidity increases to 70%; 1-5h: maintain stable CO2 concentration, pressure, and humidity; 5-6h: slowly reduce CO2 concentration to 5%, depressurize; end curing, dismantle the device.

[0112] Follow-up maintenance: After CO2 curing, proceed to standard curing; cover with plastic film to retain moisture for 7 days; temperature 20±2°C, relative humidity ≥95%; curing until the designed age (usually 28 days).

[0113] IV. Detailed Explanation of Technical Principles (with accompanying diagrams) 4.1 Geopolymerization mechanism (e.g.) Figure 1 (As shown) Figure 1 In the middle, on the left: the initial state of solid waste particles such as fly ash and slag; in the middle: under the action of alkali activator, the particle surface dissolves and releases Si-OH and Al-OH; on the right: the three-dimensional network structure of the geopolymer (Si-O-Al-O framework) formed.

[0114] The reaction process is divided into three stages: Phase 1: Dissolution and Depolymerization (0-2 hours): Alkali activator (OH) - SiO3² - ) + aluminosilicate solid waste → Si-OH + Al-OH (monomers and oligomers).

[0115] The Si-O-Si and Al-O-Al bonds on the surface of solid waste break under the action of strong alkali, releasing soluble silicate and aluminate ions; pH>13 is the key condition for the reaction.

[0116] Stage 2: Condensation polymerization (2-12 hours): Si-OH + Al-OH → Si-O-Al + H2O → Continued condensation → Three-dimensional network structure.

[0117] Monomers form dimers and trimers through dehydration condensation; gradually constructing a three-dimensional geopolymer framework; Na + Entering skeletal equilibrium Al³ + The resulting negative charge.

[0118] Stage 3: Hardening and Shaping*> (After 12 hours): Geopolymer gels continue to grow; pore water gradually decreases; the structure becomes denser, and the strength increases.

[0119] 4.2 CO2 mineralization maintenance mechanism (e.g.) Figure 2 (As shown) Device components: 1. Sealed curing cover: made of transparent acrylic or stainless steel; 2. CO2 supply pipeline: controls flow rate and concentration; 3. Pressure monitoring: maintains a slight positive pressure; 4. Humidity regulation: ultrasonic atomization humidification; 5. Temperature control: heating / cooling system; 6. Exhaust gas treatment: alkaline solution absorbs residual CO2.

[0120] Carbonation reaction pathway: Pathway 1: Carbonation of β-C2S Step 1: 2CaO·SiO2 + CO2 → CaCO3 + CaO·SiO2; Step 2: CaO·SiO2+CO2→CaCO3+SiO2 (gel); Overall reaction: 2CaO·SiO2 + 2CO2 → 2CaCO3 + SiO2.

[0121] A CaCO3 shell first forms on the β-C2S surface; CO2 continues to diffuse into the interior through the shell; eventually, it is completely transformed into CaCO3 and amorphous SiO2 gel.

[0122] Path 2: Carbonation of MgO Step 1: MgO + H₂O → Mg(OH)₂; Step 2: Mg(OH)₂ + CO₂ → MgCO₃ + H₂O; Overall reaction: MgO + CO2 → MgCO3.

[0123] Lightly calcined MgO has high activity and rapidly hydrates to form Mg(OH)2; Mg(OH)2 reacts with CO2 to form MgCO3; MgCO3 has various crystal forms (magnesite, brucite, etc.).

[0124] Synergistic effect: CaCO3 and MgCO3 crystals fill the pores of the geopolymer gel; SiO2 gel participates in the geopolymerization reaction and enhances the structure; the carbonate layer protects the internal steel reinforcement and improves durability.

[0125] Figure 3 This is a schematic diagram of the carbonation reaction pathway.

[0126] Summary of Technological Innovations: 1. Zero-cement polymer cementing system: 87% utilization rate of industrial solid waste, completely replacing traditional silicate cement.

[0127] 2. Nanocrystal seed synergistic early strength technology: Strength increases by 40-50% in 24 hours, reaching over 65MPa.

[0128] 3. CO2 mineralization and maintenance dual-effect technology: active carbon sequestration of 50-80 kg / m³ 3 This improves both strength and durability.

[0129] 4. Carbon emissions reduced by 76%: from 0.92 to 0.22 kg CO2 / kg, with an annual emission reduction potential of 3.5 million tons.

[0130] 5. Superior overall performance: Its strength, durability, and rheological properties are all superior to those of traditional cement-based materials.

[0131] 4.3 Performance Development Patterns Figure 4 This is a graph showing the compressive strength time curve and strength development comparison data. Strength development characteristics: 0-6h: initial setting period, slow strength growth; 6-24h: rapid growth period, synergistic effect of geopolymerization reaction and slag hydration; 1-3d: continuous growth, CO2 curing effect becomes apparent; 3-28d: stable growth, later strength development is stable.

[0132] Figure 5 Maintain a flowability curve.

[0133] Flowability analysis: Initial flowability: 350±10mm; 30min flowability: 320±10mm (loss <10%); 60min flowability: 310±10mm (still workable); Traditional cement-based materials lose 15-20% in 30min, this material has obvious advantages.

[0134] Mechanism explanation: Geopolymer gels form slowly and do not rapidly absorb water and solidify in the early stages; polycarboxylate superplasticizers have good compatibility with geopolymer systems; and nano-SiO2 has a water-retaining effect.

[0135] 4.4 Carbon Footprint Comparison like Figure 6 As shown, the emission reduction effect is: compared with traditional materials, emissions are reduced by (0.92-0.22) / 0.92=76%; based on an annual usage of 5 million tons, annual CO2 emissions are reduced by 350 tons; equivalent to the annual emissions of 760,000 cars; CO2 maintenance actively sequesters 50-80 kg / m³ of carbon. 3 .

[0136] Detailed carbon emission accounting: Traditional cement-based materials (0.92 kg CO2 / kg): Cement production: 0.45 kg × 0.85 = 0.76 kg; Mineral admixtures: 0.05 kg × 0.05 = 0.0025 kg; Aggregate mining and transportation: 0.50 kg × 0.02 = 0.01 kg; Admixture production: 0.02 kg × 2.0 = 0.04 kg; Mixing and stirring: 0.05 kg; Transportation: 0.06 kg; Total: 0.92 kg CO2 / kg.

[0137] Materials used in this invention (0.22 kg CO2 / kg, 0.14 kg after deducting carbon fixation): Solid waste (fly ash, slag, etc.): 0.55 kg × 0.02 = 0.011 kg (transportation only); Metakaolin (calcined at 800°C): 0.05 kg × 0.50 = 0.025 kg; Alkali activator (NaOH, Na2SiO3): 0.15 kg × 0.80 = 0.12 kg; β-C2S (extracted from steel slag): 0.02 kg × 0.02 kg. 30 = 0.006 kg; MgO (lightly calcined): 0.01 kg × 0.70 = 0.007 kg; Aggregate: 0.50 kg × 0.02 = 0.01 kg; Admixture: 0.03 kg × 2.0 = 0.06 kg; Mixing: 0.05 kg; Transportation: 0.06 kg; Subtotal (emissions): 0.35 kg CO2 / kg; CO2 carbon fixation: -0.08 kg (active absorption); Net emissions: 0.22 kg CO2 / kg.

[0138] V. Technical Effects and Performance Indicators 5.1 Overall Performance Indicators Table 1 shows the comprehensive performance indicators.

[0139]

[0140] 5.2 Durability Indicators Table 2 shows the durability indicators.

[0141]

[0142] Mechanism of durability advantage: 1. Resistance to chloride ion penetration: Geopolymer gel has smaller pore size (high proportion <10nm), making chloride ion diffusion difficult.

[0143] 2. Freeze-thaw resistant: The dense structure reduces the amount of water that frosts, and the carbonate layer provides additional protection.

[0144] 3. Carbonization depth: CO2 has already reacted during the curing stage, so the natural carbonization depth is small in the later stage.

[0145] 4. Sulfate resistant: Free of Ca(OH)2 and C3A, avoiding the formation of expansive gypsum and ettringite.

[0146] 5. Low shrinkage: The geopolymer gel has low self-shrinkage, which is effectively compensated by the swelling agent.

[0147] 6. Reinforcing steel protection: dual protection of alkaline environment and carbonate passivation layer.

[0148] 5.3 Comparison of Environmental Indicators Table 3 is a comparison table of environmental protection indicators.

[0149]

[0150] VI. Core Innovation Points Innovation Point 1: Zero-Cement Polymer Cementing System The technology essentially uses alkali-activated industrial solid waste (fly ash, slag, recycled construction waste powder, metakaolin) to completely replace traditional silicate cement, forming a geopolymer gel network as the cementitious matrix.

[0151] Key technical parameters: Solid waste ratio: fly ash 50-58%, slag 30-40%, recycled micro powder 15-23%, metakaolin 6-10%; total solid waste accounts for more than 85% of the material mass; alkali activator modulus 2.0-2.5, dosage accounts for 25-30% of cementitious materials.

[0152] Technical benefits: Carbon emissions reduced by 76%; industrial solid waste utilization rate increased by 87%; cement consumption completely eliminated.

[0153] Scope of protection: including but not limited to any combination of the above-mentioned solid waste types; alkali activator modulus range of 1.8-3.0; and schemes with solid waste utilization rate ≥80%.

[0154] Innovation Point 2: Solid Alkali Activator Pre-fabrication Technology The essence of the technology is to pre-mix and dry liquid sodium silicate and sodium hydroxide solutions to produce solid granular alkali activators, which solves the problems of inconvenience in using liquid alkali and danger in transportation.

[0155] Key points of preparation method: The mass ratio of sodium silicate: sodium hydroxide: potassium carbonate is (16-24):(3-5):(1-2); nano silica sol is added to enhance the activation effect; low temperature drying at 50-60°C to maintain the activity of sodium silicate.

[0156] Technical benefits: easy to transport and store, high safety; only water needs to be added on-site for dissolution, simple operation; activation effect is no less than that of liquid alkali.

[0157] Scope of protection: composition and proportion of solid alkali activator; preparation method (mixing-drying-pulverizing); application method in sleeve grouting materials.

[0158] Innovation Point 3: Nanocrystal Seed Synergistic Early Strength Technology The technology essentially combines nano-CSH seed crystals, triethanolamine, and aluminum sulfate in a ternary composite to synergistically promote geopolymerization and slag hydration, thereby solving the problem of insufficient early strength of geopolymers.

[0159] Synergistic mechanism: Nano-CSH seed crystals: provide nucleation centers and lower the nucleation barrier; Triethanolamine: complex with Ca... 2+ Promotes rapid CSH gel formation; Aluminum sulfate: Al 3+ Accelerated polymer network formation, SO4 2- Genetic plaster provides early strength.

[0160] Key proportions: Nano CSH: 0.6-1.2% (mass fraction); Triethanolamine: 0.3-0.5%; Aluminum sulfate: 0.4-0.8%; The mass ratio of the three is (3-6):(1.5-2.5):(2-4).

[0161] Technical effects: Strength increases by 40-50% in 24 hours, reaching over 65MPa; does not affect subsequent strength development; does not increase the risk of shrinkage and cracking.

[0162] Scope of protection: Composition of the ternary early strength system; range of component ratios; methods for synergistically promoting the early strength of geopolymers.

[0163] Innovation Point 4: Dual-Effect Technology for CO2 Mineralization and Maintenance The essence of the technology is to incorporate β-C2S and lightly calcined MgO into the material, and then perform CO2 curing after grouting (concentration 20%, pressure 0.1-0.2MPa, 3-6h). On the one hand, CO2 is actively fixed, and on the other hand, the generated carbonates provide additional strength and a protective layer.

[0164] Reaction mechanisms: β-C2S carbonation: 2CaO·SiO2 + 2CO2 → 2CaCO3 + SiO2; MgO carbonation: MgO + CO2 → MgCO3.

[0165] Curing process parameters: Curing timing: 2 hours after grouting (initial setting); CO2 concentration: 20% (volume fraction); Pressure: 0.1-0.2 MPa; Humidity: 60-75%; Time: 3-6 hours.

[0166] Technical effects: Carbon fixation of 50-80 kg CO2 / m³; 28-day strength increase of 10-15%; formation of a 5-10 μm carbonate protective layer on the surface of the steel bar; reduced permeability and improved durability.

[0167] Protection scope: Ratio of β-C2S to MgO: (15-25): (8-12); Process parameter range for CO2 curing; Curing equipment and methods; Technical solution for carbon fixation ≥ 40 kg / m³.

[0168] Innovation Point 5: Multi-scale Composite Reinforcement Technology The technology essentially optimizes the density, toughness, and volume stability of materials through multi-scale synergy of nano-SiO2 (nanoscale), fibers (micrometer scale), and expansion agents (macroscale).

[0169] Functions of each component: Nano SiO2 (5-8 parts): fills nanopores and promotes the pozzolanic effect; Polypropylene fiber (0.8-1.2 parts, 12mm long): resists cracking and toughens; Composite expansion agent (12-18 parts): compensates for shrinkage and ensures density.

[0170] Synergistic effects: Porosity reduced to 8-12%; flexural strength increased by 20%; shrinkage reduced by 40%.

[0171] Scope of protection: composition of multi-scale composite systems; size range and proportion of each component; synergistic mechanism.

[0172] This invention is not limited to the above-described optional embodiments. Anyone can derive other various forms of products under the guidance of this invention. However, regardless of any changes made in their shape or structure, any technical solution that falls within the scope of the claims of this invention shall be protected by this invention.

Claims

1. A low-carbon, environmentally friendly geopolymer sleeve grouting material, characterized in that: Includes the following ingredients by weight: Solid waste-based cementitious material system: 250-300 parts of F-type fly ash, 150-200 parts of S95 grade granulated blast furnace slag powder, 80-120 parts of recycled construction waste powder, and 30-50 parts of metakaolin. Alkali activator system: 80-120 parts solid sodium silicate, 15-25 parts solid sodium hydroxide, 5-10 parts potassium carbonate, and 20-35 parts nano silica sol; Early-strength synergistic components: 3-6 parts nano-CSH seed crystals, 2-4 parts aluminum sulfate, and 1.5-2.5 parts triethanolamine; Aggregate and admixture system: 400-500 parts graded quartz sand, 4-6 parts polycarboxylate superplasticizer, 12-18 parts composite expansion agent, 0.8-1.2 parts polypropylene fiber, and 5-8 parts nano-SiO2; CO2 mineralization components: 15-25 parts calcium silicate, 8-12 parts magnesium oxide.

2. The low-carbon and environmentally friendly geopolymer sleeve grouting material according to claim 1, characterized in that: The fineness of the F-type fly ash is <15μm; the specific surface area of ​​the S95 grade granulated blast furnace slag powder is 400-450m². 2 / kg; Specific surface area of ​​recycled construction waste powder ≥450m² 2 / kg; the al2O3 content in metakaolin is ≥38%, the SiO2 content is ≥50%, and the specific surface area of ​​metakaolin is ≥12000m². 2 / kg.

3. The low-carbon and environmentally friendly geopolymer sleeve grouting material according to claim 1, characterized in that: The solid sodium silicate has a SiO2 / Na2O molar ratio of 2.0-2.5 and a water content of <5%; the solid sodium hydroxide has a purity of ≥96%; and the nano silica sol has a SiO2 content of 30%, a particle size of 10-20 nm, and a pH of 9-10.

4. The low-carbon and environmentally friendly geopolymer sleeve grouting material according to claim 1, characterized in that: The nano-CSH seed crystals have a particle size of <50nm and a Ca / Si molar ratio of 0.8-1.

2.

5. The low-carbon and environmentally friendly geopolymer sleeve grouting material according to claim 1, characterized in that: The graded quartz sand has a particle size range of 0.3-2.0 mm; the polycarboxylate superplasticizer has a water reduction rate ≥30%, a solid content of 40%, and a pH of 6-8; the composite expanding agent comprises 60% magnesium expanding agent and 40% calcium sulfoaluminate by weight; the polypropylene fiber has a length of 12 mm, a diameter of 20-30 μm, and a tensile strength ≥350 MPa; the nano-SiO2 has a particle size of 7-15 nm and a specific surface area of ​​200±25 m². 2 / kg, purity ≥99.8%.

6. The low-carbon and environmentally friendly geopolymer sleeve grouting material according to claim 1, characterized in that: The citric acid activity in the magnesium oxide is ≥60 seconds.

7. A method for preparing a low-carbon and environmentally friendly geopolymer sleeve grouting material, used to prepare the low-carbon and environmentally friendly geopolymer sleeve grouting material according to any one of claims 1 to 6, characterized in that: Includes the following steps: S1: Pre-prepared alkaline activator: Weigh out solid sodium silicate, sodium hydroxide, and potassium carbonate according to the formula; put them into a planetary mixer and dry mix for 10 minutes until uniform; slowly add nano silica sol while stirring; transfer the mixture to an oven and dry at 50-60°C for 6-8 hours; crush and sieve to obtain solid alkali activator particles with a particle size <5mm; seal and package to prevent moisture absorption; S2: Solid waste pretreatment: Combined grinding of fly ash, slag, and recycled micro powder: Ingredients are proportioned by weight: fly ash 50-55%, slag 30-35%, recycled micro powder 15-20%; fed into a ball mill, with a grinding aid dosage of 0.05%; ground to a specific surface area ≥400 m². 2 / kg; Particle size distribution: <10μm accounts for 60%, <20μm accounts for 85%; Iron removal treatment: removes metal impurities by magnetic separation; Preparation of metakaolin: Kaolin is dried to remove surface water; it is then placed in a rotary kiln and calcined at 800°C for 2 hours; it loses structural water and transforms into metakaolin; it is rapidly cooled to room temperature and pulverized to a specific surface area ≥12000 m². 2 / kg; Activity test: Reactivity index with Ca(OH)2 ≥90%; S3: Dry Mixture Preparation: The first stage is the mixing of the main materials: Weigh the solid waste cementitious material and graded quartz sand according to the formula; put them into a forced mixer; add polypropylene fiber and stir at low speed; mix for 20 minutes until the color is uniform and the fiber is dispersed; The second stage involves the incorporation of activators: adding pre-prepared solid alkali activators; and adding early-strength synergistic components. Add CO2 mineralization components; stir at medium speed for 10 minutes; The third stage is the mixing of additives: premix the polycarboxylate superplasticizer, composite expansion agent and a small amount of sand; add them to the main material; add nano SiO2; stir at high speed for 5 minutes.

8. The preparation method of a low-carbon and environmentally friendly geopolymer sleeve grouting material according to claim 7, characterized in that: It also includes the following steps: S4: Quality Inspection Sampling uniformity testing: chloride ion content deviation ≤ 0.01%, fineness deviation ≤ 5%; moisture content < 0.5%; Appearance: Grayish-green powder, without lumps; S5: Packaging and Storage: The packaging uses a three-layer composite bag consisting of an outer PE layer, a middle aluminum foil layer, and an inner PP layer; each bag weighs 25kg or 50kg; store in a dry and ventilated place, with a shelf life of 6 months.

9. A method for applying a low-carbon and environmentally friendly geopolymer sleeve grouting material, using the low-carbon and environmentally friendly geopolymer sleeve grouting material according to any one of claims 1 to 6, characterized in that: Includes the following steps: Y1: Mixing preparation: Construction ambient temperature 5-35°C, relative humidity ≤85%; prepare a forced mixer or electric drill + mixing head; water temperature control: 5-10°C in summer, 20-30°C in winter; Y2: Add water and mix: water-to-material mass ratio: 0.12-0.15; first add 70% water, then add the dry mix and mix for 3 minutes; add the remaining 30% water and continue mixing for 5-7 minutes; total mixing time is 8-10 minutes, until the slurry is uniform and free of particles; Y3: Flowability test: Measure the flowability on the swivel table; the initial flowability should be ≥340mm; the flowability after 30 minutes should be ≥320mm. Y4: Sleeve grouting operation: Clean the inner wall of the sleeve to remove oil and debris; slowly inject grout through the grouting hole at a speed of about 1-2L / min; after filling, overflow the grout from the vent hole to confirm fullness; seal the grouting hole and vent hole. Y5: CO2 curing process: 0-1h: CO2 concentration gradually increases to 20%, relative humidity increases to 70%; 1-5h: maintain stable CO2 concentration, pressure, and humidity; 5-6h: slowly reduce CO2 concentration to 5%, depressurize; end curing, remove the device; Y6: Subsequent maintenance: After CO2 curing, proceed to standard curing; cover with plastic film to retain moisture for 7 days; temperature 20±2°C, relative humidity ≥95%; curing until the designed age.

10. The application method of the low-carbon and environmentally friendly geopolymer sleeve grouting material according to claim 9, characterized in that: In step Y5: Curing time: Let stand for 2 hours after grouting is completed; Curing equipment: Uses CO2 curing hoods or curing boxes to seal the sleeve area; equipped with a CO2 supply system; equipped with a humidity control system; Maintenance parameters: CO2 volume fraction concentration: 20%; pressure: 0.1-0.2 MPa; relative humidity: 60-75%; temperature: 20±5°C; maintenance time: 3-6 hours.

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