Composite system geopolymer grouting material and preparation method thereof

Abstract

The invention discloses a composite system geopolymer grouting material and a preparation method thereof. The composite system geopolymer grouting material comprises the following raw materials in percentage by mass: 50-70% of coal gangue, 10-30% of fly ash and 10-30% of cement. Functional additives: 5%-20% of desulfurized gypsum and 5%-15% of bentonite; the composite exciting agent is formed by compounding carbide slag and sodium silicate according to the mass ratio of 1: 1-1: 2. The geopolymer is excellent in mechanical property, meets engineering requirements, is remarkable in environmental protection benefit, conforms to double-carbon target low-carbon process innovation: a calcination-free process: traditional high-temperature calcination is abandoned (the temperature needs to be 550-900 DEG C), carbon emission is reduced by more than 30% (compared with a contrast, the carbon emission of a traditional process is increased by 35%), and the geopolymer conforms to the green positioning of low energy consumption and low three wastes of geopolymers. The cost advantage is prominent, the economic value is remarkable, the raw material cost is reduced, specifically, the coal gangue (low-cost solid waste) is used for replacing 30%-50% of cement, and the comprehensive raw material cost is reduced by 40% (compared with a traditional cement-based grouting material).

Description

Technical Field

[0001] The invention relates to a polymer grouting material, in particular to a composite system geopolymer grouting material and a preparation method thereof. Background Art

[0002] Industry status and pressure on solid waste treatment: Coal, as the main energy source in my country, generates a large amount of coal-based solid waste (such as coal gangue, fly ash, desulfurization gypsum, etc.) during production, processing and consumption. Its annual emission exceeds 10 billion tons, and the accumulated stockpile has reached hundreds of billions of tons. This type of solid waste has the characteristics of large emission, wide distribution, high inertness and difficulty in treatment. Long-term storage not only occupies land and pollutes the water and soil environment, but also has the risk of spontaneous combustion and release of CO2 and SO2

[0003] Although existing technologies attempt to use coal-based solid waste in power generation, building materials, fertilizers and other fields, the complex mineral composition and large differences in activity limit actual consumption, with a comprehensive utilization rate of less than 40%. In particular, coal gangue is rich in inert clay minerals (such as kaolinite), which are difficult to activate without calcination, resulting in long-term restrictions on its large-scale application.

[0004] Technical bottlenecks of traditional grouting materials:

[0005] In grouting projects such as mine filling and foundation reinforcement, traditional materials are mainly cement-based grouting fluids, which have the following defects:

[0006] High energy consumption and high carbon emissions: Cement production requires high-temperature calcination (energy consumption accounts for 7% of the world's total industrial energy consumption and carbon emissions account for 8%), which is contrary to the concept of green building materials.

[0007] Low solid waste utilization rate: The dependence on inert solid waste such as coal gangue is low, and it needs to be activated through high-temperature calcination (550-900℃), which not only increases the cost, but may also generate inert mullite (2SiO2+3Al2O3→3Al2O3·2SiO2) due to excessive calcination, further reducing the activity.

[0008] The performance contradiction is prominent: a single gangue-based geopolymer needs to rely on a strong activator, and the strength-fluidity antagonism is significant: when the water-solid ratio is low, the fluidity is insufficient (<180mm) and it cannot be pumped; when the water-solid ratio is high, the polycondensation reaction is hindered, and the 28-day compressive strength is often lower than 2MPa, which is difficult to meet engineering standards (such as the "Technical Code for Grouting Materials" requires ≥2MPa).

[0009] Limitations of existing technologies: Existing gangue-based grouting material technologies mainly focus on a single excitation system (such as single-alkali excitation or calcium excitation), which has the following problems:

[0010] Insufficient activity stimulation: The silicon and aluminum components in uncalcined coal gangue are difficult to dissolve, and a single activator (such as NaOH or carbide slag) cannot synergistically solve the core contradiction of "high inertness and slow reaction".

[0011] Microstructural defects: lack of functional additive regulation, poor slurry rheology, high porosity of hardened body, weak interface bonding, resulting in slow strength growth in the later stage.

[0012] The process is complex and costly: The calcination process requires additional equipment investment, and energy consumption costs account for more than 30%, which restricts large-scale application.

[0013] Technical Contribution of the Present Invention: To address the above-mentioned issues, the present invention provides a calcination-free composite geopolymer grouting material and a preparation method thereof, which breaks through the bottleneck of existing technologies through the following innovations:

[0014] Multi-solid waste synergistic composite system: Construct a basic framework of "coal gangue + fly ash + cement", use the active compensation effect of fly ash and cement to stimulate the potential activity of coal gangue, and at the same time introduce desulfurization gypsum (promote coagulation) and bentonite (rheology control) to form a functional system with synergistic optimization of "strength-fluidity-durability".

[0015] Dual activator synergistic effect: carbide slag and sodium silicate are compounded in a mass ratio of 1:1 to 1:2 to promote the dissolution of silicon and aluminum through the synergistic effect of calcium and alkali, avoiding the limitations of a single activator.

[0016] Calcination-free green process: Abandoning the high-temperature activation step, directly utilizing undisturbed coal gangue, reducing carbon emissions by more than 30%, while increasing the utilization rate of coal gangue to more than 70%, achieving the triple goals of "solid waste disposal - low-carbon production - performance compliance".

[0017] Microstructure strengthening mechanism: SEM-EDS confirmed that fly ash and cement formed Si-O-Al network in the early stage, and bentonite densely compacted the interface through interlayer adsorption in the later stage, so that the strength at 28 days was ≥2MPa, and it could reach 4.5MPa at 55 days. The fluidity was ≥180mm, which fully met the needs of grouting engineering. Summary of the Invention

[0018] The technical problem to be solved by the present invention is to overcome the defects of the above-mentioned technology and provide a composite system geopolymer grouting material and a preparation method thereof.

[0019] To solve the above technical problems, the present invention provides a technical solution comprising a composite geopolymer grouting material and a preparation method thereof:

[0020] A composite system geopolymer grouting material includes the following raw material components and mass percentages:

[0021] Gangue 50%-70%, fly ash 10%-30%, cement 10%-30%;

[0022] Functional additives: desulfurized gypsum 5% to 20%, bentonite 5% to 15%;

[0023] Composite activator: carbide slag and sodium silicate are compounded in a mass ratio of 1:1 to 1:2.

[0024] As an improvement, the gangue is uncalcined original gangue, and the specific surface area of ​​the raw material after grinding is ≥400m 2 / kg.

[0025] As an improvement, the cement is PC 42.5 grade cement, and the fly ash and cement improve the early strength through active compensation.

[0026] As an improvement, the desulfurized gypsum is used to promote the formation of ettringite, and the bentonite is used to optimize the rheological properties of the slurry through ion exchange, so that the initial fluidity is ≥180 mm.

[0027] The preparation method of the composite system geopolymer grouting material is characterized by comprising the following steps:

[0028] (1) Raw material pretreatment: Grind the coal gangue, fly ash, cement, desulfurized gypsum and bentonite to a specific surface area of ​​≥400m 2 / kg;

[0029] (2) Mixing ingredients: Weigh the solid raw materials and composite activator in proportion, add water and stir after mixing, control the water-solid ratio to 0.6-0.7, and stir for 10 minutes;

[0030] (3) Vibration molding: the slurry is injected into the mold and vibrated and compacted by a vibration table;

[0031] (4) Curing process: Curing at room temperature for 3 days before demoulding, followed by wet curing for 28 days or 55 days.

[0032] As an improvement, during the vibration compaction molding process, the mold size is 40×40×40mm 3 The vibration time is based on the fact that the slurry surface is covered with slurry and there are no bubbles overflowing.

[0033] As an improvement, the wet curing conditions are a temperature of 20±1°C and a humidity ≥98% RH.

[0034] As an improvement, the performance indicators of the grouting material are: 28-day compressive strength ≥ 2MPa, 55-day compressive strength ≥ 4.5MPa, and initial fluidity ≥ 180mm.

[0035] As an improvement, in the microstructure of the material, the early hydration products of fly ash and cement form a Si-O-Al network with the coal gangue particles, and the later bentonite strengthens the interface bonding through interlayer adsorption.

[0036] As an improvement, the material is used for mine filling, foundation reinforcement or environmental restoration projects.

[0037] The advantages of the present invention compared with the prior art are: superior mechanical properties and meeting engineering requirements:

[0038] The strength meets the standard and continues to grow: Early strength: The 14-day compressive strength generally reaches 2MPa, and some samples exceed 3MPa (such as group A and group B test blocks), meeting the early consolidation requirements of grouting materials.

[0039] Late strength: 28-day strength ≥ 2MPa, 55-day maximum strength reaches 4.5MPa (as in Example 3), with a long strength growth cycle to meet long-term load-bearing requirements.

[0040] High gangue ratio performance: When the gangue accounts for 70%, through bentonite adjustment (such as C3 and C6 test blocks), the 28-day strength still reaches 2MPa and the fluidity is 210mm, breaking through the limitations of traditional inert materials.

[0041] Fluidity and construction adaptability: initial fluidity ≥ 180 mm (water-solid ratio 0.6-0.7), up to 210 mm (as in Example 2), meeting the requirements of the pumping grouting process for slurry fluidity and avoiding the risk of pipe blockage.

[0042] Significant environmental benefits, in line with the "dual carbon" goals:

[0043] Efficient utilization of solid waste: The utilization rate of coal gangue exceeds 70%: the original coal gangue can be directly used without calcination, and a single ton of material can absorb 0.5 to 0.7 tons of coal gangue, significantly reducing the accumulation of solid waste in mines (my country's annual increase in coal-based solid waste exceeds 10 billion tons).

[0044] Synergistic utilization of multiple solid wastes: Simultaneously consume industrial by-products such as fly ash, desulfurization gypsum, and carbide slag to form a multi-solid waste composite system of "coal gangue + fly ash + cement + desulfurization gypsum + bentonite + carbide slag", realizing "waste treatment with waste".

[0045] Low-carbon process innovation: Calcination-free process: abandoning traditional high-temperature calcination (requires 550-900°C), reducing carbon emissions by more than 30% (compared with the control ratio, the traditional process carbon emissions are 35% higher), in line with the green positioning of geopolymers "low energy consumption, low three wastes".

[0046] Outstanding cost advantages and significant economic value:

[0047] Reduced raw material costs: Gangue (low-cost solid waste) replaces 30% to 50% of cement, reducing overall raw material costs by 40% (compared to traditional cement-based grouting materials).

[0048] The calcination-free process eliminates the high-temperature energy consumption cost and further reduces production investment.

[0049] High cost-effectiveness throughout the entire life cycle: The strength continues to increase in the later stage (strength reaches 4.5MPa after 55 days), which can reduce material consumption; excellent fluidity reduces construction difficulty and significantly optimizes the overall project cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 The present invention is a schematic diagram of the raw material composition and mass percentage of a composite system geopolymer grouting material and a preparation method thereof.

[0051] Figure 2 The present invention is a preparation process flow chart of a composite system geopolymer grouting material and a preparation method thereof.

[0052] Figure 3 The present invention is a microstructure schematic diagram of a composite system geopolymer grouting material and a preparation method thereof.

[0053] Figure 4 This is a performance index comparison table of a composite system geopolymer grouting material and a preparation method thereof of the present invention.

[0054] Figure 5 This is a schematic diagram of an application scenario of a composite system geopolymer grouting material and a preparation method thereof according to the present invention. DETAILED DESCRIPTION

[0055] To facilitate understanding of the present application, the present application will be described more fully below with reference to the accompanying drawings. The accompanying drawings provide embodiments of the present application. However, the present application may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to make the disclosure of the present application more thorough and comprehensive.

[0056] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application.

[0057] It will be understood that spatial relational terms such as "under," "beneath," "beneath," "under," "above," "above," etc., may be used herein to describe the relationship of an element or feature shown in the figures to other elements or features. It will be understood that in addition to the orientations shown in the figures, spatial relational terms also include different orientations of the device in use and operation. For example, if the device in the drawings is turned over, the element or feature described as "under" or "beneath" or "beneath" the other elements will be oriented as "above" the other elements or features. Thus, the exemplary terms "under" and "under" may include both the above and below orientations. In addition, the device may also include alternative orientations, such as, rotated 90 degrees or other orientations, and the spatial descriptors used herein are to be interpreted accordingly.

[0058] It should be noted that when an element is considered to be "connected" to another element, it can be directly connected to the other element or connected to the other element through an intermediate element. In the following embodiments, "connection" should be understood as "electrical connection", "communication connection", etc., if the connected circuits, modules, units, etc. can transmit electrical signals or data to each other.

[0059] When used herein, the singular forms "a", "an", and "the" may also include the plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "include / comprise" or "have" and the like specify the presence of stated features, integers, steps, operations, components, parts, or combinations thereof, but do not preclude the possibility of the presence or addition of one or more other features, integers, steps, operations, components, parts, or combinations thereof.

[0060] In conjunction with the accompanying drawings, a composite system geopolymer grouting material and a preparation method thereof, a composite system geopolymer grouting material, including the following raw material composition and mass percentage:

[0061] Gangue 50%-70%, fly ash 10%-30%, cement 10%-30%;

[0062] Functional additives: desulfurized gypsum 5% to 20%, bentonite 5% to 15%;

[0063] Composite activator: carbide slag and sodium silicate are compounded in a mass ratio of 1:1 to 1:2.

[0064] As an improvement, the gangue is uncalcined original gangue, and the specific surface area of ​​the raw material after grinding is ≥400m 2 / kg.

[0065] As an improvement, the cement is PC 42.5 grade cement, and the fly ash and cement improve the early strength through active compensation.

[0066] As an improvement, the desulfurized gypsum is used to promote the formation of ettringite, and the bentonite is used to optimize the rheological properties of the slurry through ion exchange, so that the initial fluidity is ≥180 mm.

[0067] The preparation method of the composite system geopolymer grouting material is characterized by comprising the following steps:

[0068] (1) Raw material pretreatment: Grind the coal gangue, fly ash, cement, desulfurized gypsum and bentonite to a specific surface area of ​​≥400m 2 / kg;

[0069] (2) Mixing ingredients: Weigh the solid raw materials and composite activator in proportion, add water and stir after mixing, control the water-solid ratio to 0.6-0.7, and stir for 10 minutes;

[0070] (3) Vibration molding: the slurry is injected into the mold and vibrated and compacted by a vibration table;

[0071] (4) Curing process: Curing at room temperature for 3 days before demoulding, followed by wet curing for 28 days or 55 days.

[0072] As an improvement, during the vibration compaction molding process, the mold size is 40×40×40mm 3 The vibration time is based on the fact that the slurry surface is covered with slurry and there are no bubbles overflowing.

[0073] As an improvement, the wet curing conditions are a temperature of 20±1°C and a humidity ≥98% RH.

[0074] As an improvement, the performance indicators of the grouting material are: 28-day compressive strength ≥ 2MPa, 55-day compressive strength ≥ 4.5MPa, and initial fluidity ≥ 180mm.

[0075] As an improvement, in the microstructure of the material, the early hydration products of fly ash and cement form a Si-O-Al network with the coal gangue particles, and the later bentonite strengthens the interface bonding through interlayer adsorption.

[0076] As an improvement, the material is used for mine filling, foundation reinforcement or environmental restoration projects.

[0077] 1. Raw material composition and ratio range:

[0078] The composite system geopolymer grouting material of the present invention is composed of the following raw materials (mass percentage):

[0079] Basic raw materials: coal gangue 50%-70%, fly ash 10%-30%, cement 10%-30%;

[0080] Functional additives: desulfurized gypsum 5% to 20%, bentonite 5% to 15%;

[0081] Composite activator: carbide slag and sodium silicate are compounded in a mass ratio of 1:11:2, accounting for 3% to 8% of the total mass of the raw materials.

[0082] Key Qualifications:

[0083] The coal gangue is uncalcined raw coal gangue and needs to be ground to a specific surface area of ​​≥400m 2 / kg to increase the reactivity of the particles.

[0084] PC 42.5 grade Portland cement is used, and fly ash must meet the GB / T 1596-2017 "Fly ash used in cement and concrete" standard.

[0085] 2. Preparation method steps:

[0086] 2.1 Raw material pretreatment:

[0087] Grind the coal gangue, fly ash, cement, desulfurized gypsum and bentonite separately through ball mills, and control the specific surface area to be ≥400m 2 / kg, ensuring uniform dispersion of particles and improving the efficiency of subsequent hydration reactions.

[0088] 2.2 Ingredients and mixing:

[0089] Weigh all solid raw materials and composite activator (carbide slag and sodium silicate) according to the designed ratio, pour them into the cement mortar mixer and dry mix for 2 minutes, then add drinking water, control the water-solid ratio to 0.6-0.7, and stir for 10 minutes until the slurry is uniform and free of lumps.

[0090] 2.3 Vibration compaction molding:

[0091] Pour the stirred slurry into a 40×40×40mm 3 Place the slurry in a cast iron triple mold and vibrate it on a vibration table for 30 to 60 seconds until the slurry surface is covered with slurry and no bubbles overflow, ensuring the density of the molded body.

[0092] 2.4 Curing process:

[0093] Room temperature curing: After forming, the mold is left to stand at an ambient temperature of 20±1℃ for 3 days, and demoulding is carried out after the slurry has initially hardened.

[0094] Wet curing: The demoulded test pieces were placed in a curing box (temperature 20±1°C, humidity ≥98% RH) and cured for 28 days and 55 days, respectively, and the mechanical properties were tested.

[0095] 3. Typical embodiments:

[0096] The technical solution of the present invention is further illustrated by the following specific examples (the raw material ratios in each example are all in mass percentage):

[0097] Example 1:

[0098] Raw material composition: coal gangue 50%, fly ash 30%, cement 20%, desulfurized gypsum 20%, bentonite 15%, composite activator (carbide slag: sodium silicate = 1:1) 5%.

[0099] Preparation parameters: water-to-solid ratio 0.6, stirring time 10 minutes, and vibration time 40 seconds.

[0100] Performance testing:

[0101] 28-day compressive strength: 2.5MPa;

[0102] 55-day compressive strength: 3.8MPa;

[0103] Initial fluidity: 180mm.

[0104] Example 2:

[0105] Raw material composition: coal gangue 70%, fly ash 20%, cement 10%, bentonite 5%, composite activator (carbide slag: sodium silicate = 1:2) 5%.

[0106] Preparation parameters: water-to-solid ratio 0.7, stirring time 10 minutes, and vibration time 50 seconds.

[0107] Performance testing:

[0108] 28-day compressive strength: 2.0MPa;

[0109] Initial fluidity: 210mm;

[0110] 55-day compressive strength: 2.8MPa (strength continues to increase with curing time).

[0111] Example 3:

[0112] Raw material composition: coal gangue 60%, fly ash 15%, cement 25%, desulfurized gypsum 10%, bentonite 10%, composite activator (carbide slag: sodium silicate = 1:1.5) 6%.

[0113] Preparation parameters: water-to-solid ratio 0.65, stirring time 10 minutes, and vibration time 45 seconds.

[0114] Performance testing:

[0115] 28-day compressive strength: 3.0MPa;

[0116] 55-day compressive strength: 4.5MPa;

[0117] Initial fluidity: 190mm.

[0118] 4. Comparative Example (Traditional Calcination Process):

[0119] Raw material composition: 70% calcined coal gangue, 30% cement, 5% composite activator (carbide slag: sodium silicate = 1:1).

[0120] Preparation parameters: coal gangue was calcined at 800° C. for 2 hours, water-solid ratio was 0.6, and the rest of the process was the same as in Example 1.

[0121] Performance comparison:

[0122] 28-day compressive strength: 2.3MPa;

[0123] Carbon emissions: 35% higher than the present invention;

[0124] Comprehensive cost: 40% higher than that of the present invention (including calcination energy consumption cost).

[0125] Conclusion: The calcination-free process of the present invention significantly reduces energy consumption and costs while maintaining comparable strength, and is in line with the concept of green building materials.

[0126] 5. Performance characterization and mechanism of action:

[0127] 5.1 Macro performance:

[0128] Strength development law:

[0129] The compressive strength after 14 days generally reached 2 MPa, the strength after 28 days was ≥2 MPa, and the strength after 55 days was up to 4.5 MPa (as in Example 3).

[0130] When the proportion of coal gangue increases (such as in Example 2), the early strength is slightly lower, but by adjusting the rheology with bentonite and extending the curing time, the later strength can be close to the formula with medium and low coal gangue proportion.

[0131] Fluidity: When the water-solid ratio is 0.60.7, the initial fluidity is 180210mm, which meets the requirements of grouting engineering for pumping construction.

[0132] 5.2 Micro-mechanism:

[0133] SEM-EDS analysis:

[0134] Early stage (28 days): Fly ash and cement are hydrated to form CSH gel and ettringite, which form a Si-O-Al network structure on the surface of coal gangue particles, laying the foundation for strength.

[0135] Later stage (55 days): Bentonite fills the pores and strengthens the interface bonding through interlayer adsorption, and the microstructure becomes denser (such as Figure 1shown).

[0136] FTIR and XRD verification:

[0137] Infrared spectra showed that the Si-O-Al bond vibration peak was enhanced, indicating that the polymerization reaction was sufficient;

[0138] In the X-ray diffraction pattern, the intensity of the ettringite diffraction peak increases with the increase of desulfurized gypsum addition, confirming its accelerating effect.

[0139] 6. Application scenarios:

[0140] The grouting material of the present invention is applicable to the following fields:

[0141] Mine filling: used for grouting filling in coal mine goaf, replacing traditional cement-based materials, reducing the land occupied by coal gangue storage and the risk of spontaneous combustion.

[0142] Foundation reinforcement: Improve the mechanical properties of weak soil layers through pressure grouting and enhance the bearing capacity of the foundation.

[0143] Environmental remediation: As a solidification and stabilization material for heavy metal contaminated soil, the gelling properties of the composite system are used to fix pollutants.

[0144] Excellent mechanical properties to meet engineering needs:

[0145] The strength meets the standard and continues to grow: Early strength: The 14-day compressive strength generally reaches 2MPa, and some samples exceed 3MPa (such as group A and group B test blocks), meeting the early consolidation requirements of grouting materials.

[0146] Late strength: 28-day strength ≥ 2MPa, 55-day maximum strength reaches 4.5MPa (as in Example 3), with a long strength growth cycle to meet long-term load-bearing requirements.

[0147] High gangue ratio performance: When the gangue accounts for 70%, through bentonite adjustment (such as C3 and C6 test blocks), the 28-day strength still reaches 2MPa and the fluidity is 210mm, breaking through the limitations of traditional inert materials.

[0148] Fluidity and construction adaptability: initial fluidity ≥ 180 mm (water-solid ratio 0.6-0.7), up to 210 mm (as in Example 2), meeting the requirements of the pumping grouting process for slurry fluidity and avoiding the risk of pipe blockage.

[0149] Significant environmental benefits:

[0150] Efficient utilization of solid waste: The utilization rate of coal gangue exceeds 70%: the original coal gangue can be directly used without calcination, and a single ton of material can absorb 0.5 to 0.7 tons of coal gangue, significantly reducing the accumulation of solid waste in mines (my country's annual increase in coal-based solid waste exceeds 10 billion tons).

[0151] Synergistic utilization of multiple solid wastes: Simultaneously consume industrial by-products such as fly ash, desulfurization gypsum, and carbide slag to form a multi-solid waste composite system of "coal gangue + fly ash + cement + desulfurization gypsum + bentonite + carbide slag", realizing "waste treatment with waste".

[0152] Low-carbon process innovation: Calcination-free process: abandoning traditional high-temperature calcination (requires 550-900°C), reducing carbon emissions by more than 30% (compared with the control ratio, the traditional process carbon emissions are 35% higher), in line with the green positioning of geopolymers "low energy consumption, low three wastes".

[0153] Outstanding cost advantages and significant economic value:

[0154] Reduced raw material costs: Gangue (low-cost solid waste) replaces 30% to 50% of cement, reducing overall raw material costs by 40% (compared to traditional cement-based grouting materials).

[0155] The calcination-free process eliminates the high-temperature energy consumption cost and further reduces production investment.

[0156] High cost-effectiveness throughout the entire life cycle: The strength continues to increase in the later stage (strength reaches 4.5MPa after 55 days), which can reduce material consumption; excellent fluidity reduces construction difficulty and significantly optimizes the overall project cost.

[0157] Technological innovation and breakthrough, scientific and reliable mechanism:

[0158] Synergistic effect of the composite system: Active compensation mechanism: Fly ash and cement hydrate early to form CSH gel and ettringite, which form a Si-O-Al network with coal gangue particles (confirmed by SEM-EDS), compensating for the inertness defects of coal gangue.

[0159] Dual activator enhancement: Carbide slag (calcium source) and sodium silicate (alkali source) are compounded (mass ratio 1:1 to 1:2) to synergistically promote the dissolution of silicon and aluminum components in coal gangue and stimulate potential activity.

[0160] Optimization of functional additives: Desulfurized gypsum promotes the formation of ettringite and enhances structural density;

[0161] Bentonite improves the rheological properties of the slurry through ion exchange, while interlayer adsorption strengthens the later interfacial bonding (SEM shows a denser microstructure).

[0162] The anti-antagonistic design cleverly balances the contradiction between water-solid ratio and strength-fluidity: when the water-solid ratio is 0.6-0.7, it not only ensures the fluidity of the slurry (≥180mm), but also suppresses the problem of "too much water will hinder the condensation reaction" through the composite system, thus achieving balanced performance.

[0163] Wide range of application scenarios and strong engineering adaptability:

[0164] Mining field: Suitable for filling coal mine goaf and reinforcing tailings ponds to reduce solid waste land occupation and geological disaster risks.

[0165] Construction projects: It can be used in foundation reinforcement, tunnel grouting and other scenarios to replace traditional cement slurry and improve the bearing capacity of weak strata.

[0166] Environmental remediation: Used as a solidifying material to treat heavy metal contaminated soil, using gelling properties to fix pollutants and expand ecological governance applications.

[0167] The present invention breaks through the technical bottleneck of high-temperature activation of traditional coal gangue through the design of a composite raw material system and a calcination-free green process, achieving multiple breakthroughs in "high solid waste utilization rate + low energy consumption + low cost + high performance". It not only provides a new path for large-scale resource utilization of coal-based solid waste, but also provides an environmentally friendly and efficient new material option for the grouting engineering field, with significant social, environmental and economic benefits.

[0168] The present invention and its embodiments are described above. This description is not restrictive. The drawings show only one embodiment of the present invention, and the actual structure is not limited thereto. In short, if a person skilled in the art is inspired by this and, without departing from the purpose of the present invention, designs structures and embodiments similar to this technical solution without inventiveness, they shall fall within the scope of protection of the present invention.

Claims

1. A composite system geopolymer grouting material, characterized in that: Including the following raw material composition and mass percentage: Gangue 50%-70%, fly ash 10%-30%, cement 10%-30%; Functional additives: desulfurized gypsum 5% to 20%, bentonite 5% to 15%; Composite activator: carbide slag and sodium silicate are compounded in a mass ratio of 1:1 to 1:

2.

2. The grouting material according to claim 1, characterized in that The coal gangue is uncalcined raw coal gangue, and the specific surface area of ​​the raw material after grinding is ≥400m 2 / kg.

3. The grouting material according to claim 1, characterized in that The cement is PC 42.5 grade cement, and the fly ash and cement improve early strength through active compensation.

4. The grouting material according to claim 1, characterized in that The desulfurized gypsum is used to promote the formation of ettringite, and the bentonite optimizes the rheological properties of the slurry through ion exchange, so that the initial fluidity is ≥180 mm.

5. A method for preparing a composite geopolymer grouting material according to any one of claims 1 to 4, characterized in that: The following steps are involved: (1) Raw material pretreatment: Grind the coal gangue, fly ash, cement, desulfurized gypsum and bentonite to a specific surface area of ​​≥400m 2 / kg; (2) Mixing ingredients: Weigh the solid raw materials and composite activator in proportion, add water and stir after mixing, control the water-solid ratio to 0.6-0.7, and stir for 10 minutes; (3) Vibration molding: the slurry is injected into the mold and vibrated and compacted by a vibration table; (4) Curing process: Curing at room temperature for 3 days before demoulding, followed by wet curing for 28 days or 55 days.

6. The preparation method according to claim 5, characterized in that During the vibration compaction molding process, the mold size is 40×40×40mm 3 The vibration time is based on the fact that the slurry surface is covered with slurry and there are no bubbles overflowing.

7. The preparation method according to claim 5, characterized in that The wet curing conditions are a temperature of 20±1° C. and a humidity of ≥98% RH.

8. The grouting material according to any one of claims 1 to 4 or the preparation method according to any one of claims 5 to 7, characterized in that: The performance indicators of the grouting material are: 28-day compressive strength ≥ 2MPa, 55-day compressive strength ≥ 4.5MPa, initial fluidity ≥ 180mm.

9. The grouting material according to any one of claims 1 to 4, characterized in that: In the microstructure of the material, early hydration products of fly ash and cement form a Si-O-Al network with coal gangue particles, and later bentonite strengthens the interface bonding through interlayer adsorption.

10. Application of the composite geopolymer grouting material according to any one of claims 1 to 4, characterized in that: The material is used for mine filling, foundation reinforcement or environmental restoration projects.

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