Alkali-activated multi-component slow-release geopolymer grouting material and preparation method thereof

Abstract

The invention discloses an alkali-activated multi-component slow-release geopolymer grouting material and a preparation method thereof, and the alkali-activated multi-component slow-release geopolymer grouting material is prepared from the following components in parts by mass: 40 to 70 parts of a cementing material, 10 to 40 parts of a multi-component alkali activator, 10 to 30 parts of water, 0 to 5 parts of optional components and 15 to 35 parts of aggregate. The multi-component alkali activator comprises a first alkaline component and a second alkaline component, and the excitation speed of the first alkaline component is superior to that of the second alkaline component. The optional components include additives and / or reinforcing materials. The multi-component alkali activator is adopted, and the variety, proportion and slow release characteristic of each component are accurately regulated and controlled, so that accurate and controllable transformation of the slurry from long-time high fluidity to rapid coagulation is realized. Therefore, the setting time of the grouting material can be flexibly adjusted according to different engineering requirements, and the problem that a traditional geopolymer is too fast in setting or inaccurate in control is solved.

Description

Technical Field

[0001] This invention relates to the field of geopolymer materials, and more particularly to an alkali-activated multi-component slow-release geopolymer grouting material and its preparation method. Background Technology

[0002] Geopolymer materials, due to their excellent mechanical properties, durability, low carbon footprint, and environmental friendliness, are considered an ideal alternative to traditional silicate cement, showing broad application prospects in fields such as solid waste resource utilization, structural reinforcement, and geological grouting. Especially in the field of geological grouting, geopolymer grouting materials have gained increasing attention for their rapid setting, high early strength, and good compatibility with the substrate, particularly in soil consolidation, fissure filling, mine water shut-off, and tunnel lining repair.

[0003] However, geopolymer grouting materials still face numerous technical challenges in practical applications. One significant issue is the precise control of their performance and setting time. Traditional alkali-activated geopolymer grouts typically employ high-concentration or highly reactive alkali activators (such as sodium hydroxide or sodium silicate solutions) to ensure final consolidation strength and efficiency. This often results in rapid activation of the grout after mixing, leading to a short working time and rapid loss of fluidity. While this rapid setting characteristic helps achieve early consolidation, it significantly limits the effective penetration of the grout into complex, fine, or distant strata. The grout may set prematurely before reaching the target area, causing grouting pipe blockage, insufficient grouting distance, or uneven grouting, thereby affecting the consolidation effect and economic benefits of the project.

[0004] To address the aforementioned issues, various methods for controlling setting time have been attempted in existing technologies. For example, patents such as CN112250366A and CN110092618A extend the working time of the grout by adding retarders. However, this method often simply slows down the entire setting process, potentially leading to excessively long setting times, affecting early strength development, and in some cases, even adversely impacting the final properties of the geopolymer. Other technologies, such as CN116891354A, influence setting time by adjusting the raw material ratio, but their control range and precision are limited, making it difficult to meet the dynamic and precise transition requirements from high fluidity to rapid setting during grouting.

[0005] To balance initial fluidity and rapid hardening of the grout, existing technologies have developed two-component or multi-component grouting materials (e.g., CN114477867A, CN113651587A). These solutions typically store the reactive components of the grout separately and mix them using specialized equipment before or during grouting. While this macroscopic two-component system can achieve some degree of initial separation to maintain fluidity and rapid reaction after mixing, its drawbacks include the need for more complex grouting equipment, additional mixing devices, and precise pump control, increasing construction costs and operational difficulty. Furthermore, it carries the risk of uneven mixing under complex conditions. More importantly, this approach fails to address the issue of achieving dynamic controllability of grout performance within a single mixing system through the sophisticated design of the activator itself.

[0006] While the concept of "composite alkali activators" exists in existing technologies (such as CN119490326A and CN109053078A), these composite activators often focus on improving the overall performance of the geopolymer or achieving rapid setting. Their component design typically does not explicitly consider the differentiated utilization of dissolution rates or activation characteristics among different activating components to achieve a precise and controllable transition of the slurry "from high fluidity to rapid setting" during infiltration. For example, although CN119490326A discloses a composite activator, its purpose is to "significantly improve the setting rate and mechanical strength of red mud-fly ash geopolymers," emphasizing rapid setting rather than a dynamic control mechanism that first provides early fluidity and then triggers setting through slow release. Therefore, existing technologies lack a solution that can effectively extend the effective infiltration distance of the slurry within a single activator system by designing multi-component slow-release alkali activators with different dissolution rates or activation characteristics, while simultaneously ensuring rapid hardening and consolidation after injection to meet the dual requirements of high permeability and rapid consolidation under complex geological conditions. Summary of the Invention

[0007] This invention provides an alkali-activated multi-component slow-release geopolymer grouting material and its preparation method, which can solve the problems of difficult precise control of setting time, limited penetration distance, and easy premature setting and blockage in existing geopolymer grouting materials.

[0008] The present invention adopts the following technical solutions:

[0009] This invention provides an alkali-activated multi-component slow-release geopolymer grouting material, comprising the following components by weight: 40-70 parts by weight of cementitious material, 10-40 parts by weight of a multi-component alkali activator, 10-30 parts by weight of water, 0-5 parts by weight of optional components, and 15-35 parts by weight of aggregate. The multi-component alkali activator includes a first alkaline component and a second alkaline component, wherein the activation rate of the first alkaline component is superior to that of the second alkaline component. Optional components include admixtures and / or reinforcing materials.

[0010] Furthermore, the mass of the first alkaline component accounts for 30% to 70% of the mass of the multi-component alkaline activator, and the mass of the second alkaline component accounts for 70% to 30% of the mass of the multi-component alkaline activator.

[0011] Furthermore, the first alkaline component includes one or more of sodium hydroxide, potassium hydroxide, liquid sodium silicate, and liquid potassium silicate.

[0012] Furthermore, the second alkaline component includes one or more of the following: anhydrous sodium carbonate, γ-Na2SiO3 with a particle size of 50-150 μm, and alkaline substances that have undergone microencapsulation.

[0013] Furthermore, alkaline substances include one or more of sodium hydroxide, calcium hydroxide, and sodium carbonate.

[0014] Furthermore, the encapsulation material used in the microencapsulation process includes one or more of polyvinyl alcohol, polylactic acid, and acrylic resin.

[0015] Furthermore, the cementing material includes ultrafine slag and / or fly ash.

[0016] Furthermore, the admixtures include one or more of water-reducing agents, defoamers, and thickeners. The reinforcing material includes fibers.

[0017] Furthermore, the aggregate includes river sand.

[0018] This invention provides a method for preparing an alkali-activated multi-component slow-release polymer grouting material, comprising the following steps: completely dissolving a first alkaline component in water to obtain an activation solution; thoroughly mixing a cementitious material, aggregate, a second alkaline component, and optional components to obtain a dry mix; and thoroughly mixing the activation solution with the dry mix to obtain the alkali-activated multi-component slow-release polymer grouting material.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1. Precise and controllable setting time: By employing a multi-component alkali activator and precisely controlling the type, proportion, and slow-release characteristics of each component, a precise and controllable transition from prolonged high fluidity to rapid setting of the grout is achieved. This allows the setting time of the grouting material to be flexibly adjusted according to different engineering requirements (such as grouting depth, formation permeability, fracture width, groundwater flow rate, etc.), avoiding the problems of excessively rapid setting or inaccurate control found in traditional geopolymers.

[0021] 2. Significantly improves penetration distance and penetration efficiency: The grout can maintain high fluidity for a longer period of time in the initial stage of injection, which effectively extends the effective penetration distance of the grout in complex formations, avoids premature solidification and blockage of pipelines or fissures, and greatly improves the penetration efficiency and construction feasibility of grouting.

[0022] 3. Rapid hardening and excellent consolidation effect after grouting: After the grout penetrates into place, the triggering release of the second alkaline component ensures that the geopolymer system can quickly solidify and harden, rapidly forming a solidified body, thereby improving the timeliness and reliability of formation reinforcement and seepage prevention.

[0023] 4. Simplified construction operation and wide adaptability: Compared with complex two-component grouting systems, this invention can achieve stable storage and fluidity of single-component grout for a longer period before injection, simplifying grouting equipment and operation procedures. At the same time, its adjustable setting characteristics enable it to be widely applied to various geological conditions and engineering environments.

[0024] 5. Excellent mechanical properties and durability: While achieving precise control of setting time, the material of this invention uses ultrafine slag / fly ash as the main cementing material. The geopolymer solidified body has good compressive strength, durability, corrosion resistance and environmental friendliness, ensuring the long-term stability and safety of the project.

[0025] 6. Reduced project costs: Improved grouting efficiency and reduced blockages and rework help reduce the overall project cost in the long run. Detailed Implementation

[0026] The technical methods in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0027] Geopolymer grouting materials have shown great application potential in geotechnical engineering consolidation, seepage prevention, and remediation due to their excellent mechanical properties, durability, and environmental friendliness. However, existing geopolymer grouting technologies still face a series of challenges in practical applications. Traditional alkali-activated geopolymer grouting materials typically have short setting times that are difficult to control precisely. Single or fixed-ratio alkali activator systems often lead to rapid grouting after mixing, making it difficult for the grout to achieve sufficient penetration distance and time in complex formations, especially in fine fractures or deep formations. This can easily result in premature setting and blockage, thus limiting its application in long-distance, high-permeability grouting projects.

[0028] While existing technologies attempt to control setting time by adding retarders or adjusting component ratios, these methods often have limitations: some retarders may affect the final mechanical properties of the geopolymer; and setting time control achieved by simply adjusting the ratio is not precise enough to meet the differentiated performance requirements of grout under different geological conditions. Furthermore, although two-component grouting systems can achieve long-term fluidity and rapid setting after mixing, they require complex grouting equipment, increasing construction difficulty and cost, and uneven mixing can lead to performance instability. Therefore, developing a geopolymer grouting material that can maintain high fluidity in a single system for a long time to meet the permeation needs of deep or complex formations, while being effectively triggered and rapidly hardening after injection into the target area, achieving a precise and controllable change in setting time, is a pressing technical challenge in the field of geopolymer grouting.

[0029] To address the problem that existing geopolymer grouting materials struggle to balance fluidity during long-distance penetration in complex formations with rapid setting and solidification after injection, and that setting time control is imprecise, embodiments of the present invention provide an alkali-activated multi-component slow-release geopolymer grouting material, comprising the following components by weight: 40-70 parts by weight of cementitious material, 10-40 parts by weight of multi-component alkali activator, 10-30 parts by weight of water, 0-5 parts by weight of optional components, and 15-35 parts by weight of aggregate.

[0030] The cementing material may include ultrafine slag and / or fly ash; that is, the cementing material can be ultrafine slag, fly ash, or a mixture of ultrafine slag and fly ash. The amount of cementing material used can be 40, 50, 60, 70 parts by weight, etc.

[0031] The multi-component alkaline activator includes a first alkaline component and a second alkaline component. The activation rate of the first alkaline component is superior to that of the second alkaline component; that is, the dissolution rate or activation characteristics of the first alkaline component are stronger than those of the second alkaline component. Under these conditions, the first alkaline component is also called the rapid-release activating component, and the second alkaline component is also called the slow-release activating component. The first alkaline component is an alkaline component that provides initial activation to ensure the early fluidity of the slurry through rapid dissolution. The second alkaline component is an alkaline component that is gradually released or triggered for activation under specific conditions (such as pH changes, temperature increases, or after a specific time delay). The dosage of the multi-component alkaline activator can be 10, 20, 30, or 40 parts by weight.

[0032] The first alkaline component may include one or more of sodium hydroxide, potassium hydroxide, liquid sodium silicate, and liquid potassium silicate. That is, the first alkaline component can be sodium hydroxide or a mixture of sodium hydroxide and liquid sodium silicate. These components exhibit rapid dissolution and strong alkalinity, quickly providing a high pH environment (e.g., pH > 13.0) in the initial stage of slurry mixing, promoting preliminary activation of the cementitious materials, and ensuring good fluidity and a long effective penetration distance in the initial stage of the slurry. The mass of the first alkaline component can account for 30% to 70% of the multi-component alkaline activator, such as 30%, 50%, or 70%.

[0033] The second alkaline component may include one or more of anhydrous sodium carbonate, γ-Na₂SiO₃ with a particle size of 50-150 μm, and microencapsulated alkaline substances. That is, the second alkaline component can be anhydrous sodium carbonate powder or a mixture of anhydrous sodium carbonate powder and microencapsulated alkaline substances. These components are inert or poorly activated in the initial stage of slurry mixing, and are only triggered under specific preset conditions (such as a decrease in the internal pH of the slurry from an initial value >13.0 to a threshold range of 12.0-12.5, an increase in temperature of 5-15°C due to hydration exothermic reaction, or a preset time delay of 30-90 minutes after slurry mixing), gradually releasing alkaline substances or becoming activated, thereby promoting the rapid coagulation and hardening of the geopolymer system. The alkaline substance may include one or more of sodium hydroxide, calcium hydroxide, and sodium carbonate; that is, the alkaline substance can be sodium hydroxide or a mixture of sodium hydroxide and sodium carbonate. The encapsulation materials used in microencapsulation include one or more of polyvinyl alcohol, polylactic acid, and acrylic resin. In other words, the encapsulation material can be polyvinyl alcohol, or a mixture of polylactic acid and acrylic resin, etc. Acrylic resin can be... L-series polyacrylate copolymers. The mass of the second alkaline component can account for 70% to 30% of the multi-component alkaline activator, such as 30%, 50%, 70%, etc.

[0034] It should be noted that anhydrous sodium carbonate has a slower dissolution rate than sodium hydroxide, and its solubility is limited at the initial high pH, ​​thus playing a role in slow release.

[0035] γ-Na₂SiO₃, also known as γ-phase anhydrous sodium metasilicate, has a dense crystal structure and a significantly lower dissolution rate than the common α-phase or β-phase. By controlling its particle size within the range of 50–150 μm, a predictable slow-dissolution effect can be achieved, and its dissolution activation can be accelerated by increasing the system temperature or reaching a specific time delay. Specifically, the preparation and properties of γ-phase anhydrous sodium metasilicate are as follows: Industrial-grade anhydrous sodium metasilicate (mainly α-phase) is subjected to high-temperature heat treatment, followed by controlled crystallization through high-temperature melting and a specific cooling rate. Specifically, anhydrous sodium metasilicate powder is calcined at a specific temperature range (e.g., 800–950 °C) for a certain time (e.g., 2–4 hours), followed by rapid cooling. By controlling the calcination temperature, time, and cooling rate, the transformation from α-phase to γ-phase can be effectively induced, yielding high-purity γ-phase anhydrous sodium metasilicate. The particle size of the obtained γ-phase anhydrous sodium metasilicate can be further controlled through grinding and classification. The preferred γ-phase anhydrous sodium metasilicate exhibits a dissolution rate in water at 25°C that is approximately 70% lower than that of conventional α-phase anhydrous sodium metasilicate. Its crystal structure decomposes significantly in the slurry only after a slight increase in system temperature (e.g., 5-10°C) or a time delay of approximately 60-90 minutes, gradually releasing the alkaline activator and silicon-aluminum source. Optionally, the preparation process of γ-phase anhydrous sodium metasilicate involves calcining anhydrous sodium metasilicate powder at 800-950°C for 2-4 hours, followed by cooling at a rate of 100-120°C / h to obtain γ-phase anhydrous sodium metasilicate.

[0036] In addition to anhydrous sodium carbonate and γ-Na2SiO3, other pH / temperature-sensitive alkaline sources can also be used to accelerate dissolution or decomposition when the pH value inside the polymer system reaches a preset threshold (e.g., from an initial >13.0 to 12.0-12.5) or when the ambient temperature rises to 30-45°C due to exothermic reaction, thereby releasing alkaline substances.

[0037] Microencapsulated alkaline substances can be formed by encapsulating alkaline substances (such as sodium hydroxide and sodium carbonate) inside one or more layers of coating materials (such as polyvinyl alcohol, polylactic acid, and acrylic resin). The coating layer of these microcapsules can rupture at specific pH values ​​(e.g., 12.0–12.5), temperatures (e.g., 30–45°C), or under shear force, releasing the internal alkaline substance and achieving delayed activation. Specifically, the preparation and properties of microencapsulated sodium carbonate are as follows: Sodium carbonate is dissolved in deionized water to form an inner phase solution; a suitable coating material (such as polyvinyl alcohol, polylactic acid, or acrylic resin) is dissolved in an appropriate organic solvent to form an outer phase solution. The inner phase solution is added to the outer phase solution via emulsification or dispersion, and microemulsions or microsuspensions are formed through high-speed shearing or ultrasonication. Subsequently, the coating material is cured by methods such as spray drying, solvent evaporation, or interfacial polymerization to form microcapsules with specific wall thickness and pH-sensitive properties. The wall material of this microencapsulated sodium carbonate is designed to remain stable in a strongly alkaline environment with pH > 13.0, when the OH- in the slurry... - When the pH drops below 12.5 due to the consumption of ion-dependent polymerization, the capsule wall begins to rapidly dissolve and rupture, releasing the internal sodium carbonate, thus achieving precise pH-triggered activation. Optionally, sodium carbonate is dissolved in deionized water to form an inner phase solution, which is a saturated solution. Polyvinyl alcohol is selected as the coating material and dissolved in glycerol to form an outer phase solution with a polyvinyl alcohol concentration of 10%. The inner phase solution is dispersed in the outer phase solution, wherein the mass ratio of the inner phase solution to the outer phase solution is 1:2, and then a microemulsion is formed by shearing at 500-600 r / min. Subsequently, the coating material is cured by spray drying to form microencapsulated sodium carbonate.

[0038] The amount of water used can be 10, 20, 30 parts by weight, etc.

[0039] Optional components include admixtures and / or reinforcing materials. Admixtures may include one or more of water-reducing agents, defoamers, and thickeners; that is, the admixture may be a water-reducing agent or a mixture of water-reducing agents and defoamers. The water-reducing agent may be a conventional polycarboxylate water-reducing agent. Reinforcing materials may include fibers. The amount of optional components may be 0, 1, 3, or 5 parts by weight.

[0040] Aggregates may include river sand. The amount of aggregate used can be 15, 25, 35 parts by weight, etc.

[0041] An embodiment of the present invention provides a method for preparing the above-mentioned alkali-activated multi-component slow-release geopolymer grouting material, comprising the following steps:

[0042] (1) Dissolve the first alkaline component completely in water to obtain an activation solution.

[0043] In the above steps, the excitation solution is cooled to room temperature for later use.

[0044] (2) Mix the cementitious material, aggregate, second alkaline component and optional component thoroughly to obtain dry mix.

[0045] (3) The activation solution and the dry mixture are thoroughly mixed to obtain an alkali-activated multi-component slow-release polymer grouting material.

[0046] In summary, by adjusting the types, ratios, and slow-release activating components (such as the shell material, thickness, and triggering conditions of the microcapsules) in the multi-component alkaline activator, precise control of the setting time of the grouting material can be achieved. Specific control strategies include: 1. Adjusting the ratio of fast-release to slow-release activating components: With the total activator dosage remaining constant, increasing the proportion of fast-release components can shorten the grout flow time and accelerate initial setting; increasing the proportion of slow-release activating components can prolong the grout flow time, allowing setting to occur more rapidly in the later stages. 2. Selecting slow-release activating components with different slow-release characteristics: Based on the different setting time requirements of the grouting project, slow-release activating components with different slow-release rates and triggering conditions (such as sensitivity to pH or temperature) can be selected. For example, for projects requiring longer flow times, slow-release components with more stringent triggering conditions or slower release rates can be selected. 3. Optimizing the microstructure of the slow-release activating component: For microencapsulated or coated slow-release components, the release rate and triggering conditions of alkaline substances can be precisely controlled by changing the properties (such as solubility and toughness), thickness, and design of the coating material. Through the above technical solution, the geopolymer grouting material of this invention provides an initial high-alkalinity environment through the rapid activation component before or at the initial stage of injection, maintaining high fluidity of the grout and ensuring its effective penetration in complex formations. Once the grout penetrates to the target area or reaches the preset triggering conditions, the slow-release activating component begins to gradually release alkalinity or is activated, thereby rapidly increasing the reactivity of the system and promoting the rapid coagulation and hardening of the geopolymer. This "slow-to-fast" coagulation mode perfectly solves the contradiction between permeability and coagulation and hardening in traditional geopolymer grouting materials. This invention achieves a precise and controllable transformation of grout from high fluidity to rapid solidification through the synergistic effect and differentiated activation characteristics among the components of a multi-component alkali activator. This effectively extends the effective penetration distance of the grout in complex strata, avoids premature solidification and blockage, and allows for rapid hardening after injection, thereby improving penetration efficiency and consolidation effect. It is particularly suitable for deep grouting, foundation reinforcement, and tunnel repair.

[0047] The following detailed description is provided with reference to specific embodiments:

[0048] Example 1

[0049] Raw material formula:

[0050]

[0051] Preparation method:

[0052] (1) Add water, water glass and sodium hydroxide to a stirring tank and stir until the sodium hydroxide is completely dissolved to form a uniform activation solution A. Cool the solution to room temperature and set aside.

[0053] (2) Pour the ultrafine slag powder, fly ash, river sand, γ-phase anhydrous sodium metasilicate, microencapsulated sodium carbonate and water-reducing agent into another mixing bucket and mix thoroughly to form dry mix A.

[0054] (3) Slowly add the activating solution A to the dry mixture A and stir at high speed for 3 minutes to make the resulting slurry fully mixed and uniform, and obtain the geopolymer grouting material A.

[0055] The performance of the geopolymer grouting material A is tested, or it is cast and cured according to standard conditions for subsequent mechanical property testing.

[0056] Example 2

[0057] Raw material formula:

[0058]

[0059] Preparation method:

[0060] (1) Add water, water glass and potassium hydroxide to a stirring tank and stir until the potassium hydroxide is completely dissolved to form a uniform activation solution B. Cool the solution to room temperature and set aside.

[0061] (2) Pour the ultrafine slag powder, fly ash, river sand, microencapsulated sodium carbonate, anhydrous sodium carbonate and water-reducing agent into another mixing bucket and mix thoroughly to form dry mix B.

[0062] (3) Slowly add the activation solution B to the dry mixture B and stir at high speed for 3 minutes to make the resulting slurry fully mixed and uniform, thus obtaining the geopolymer grouting material B.

[0063] The performance of the geopolymer grouting material B is tested, or it is cast and cured according to standard conditions for subsequent mechanical property testing.

[0064] Example 3

[0065] Raw material formula:

[0066]

[0067] Preparation method:

[0068] (1) Add water, water glass and sodium hydroxide to a stirring tank and stir until the sodium hydroxide is completely dissolved to form a uniform activation solution C. Cool the solution to room temperature and set aside.

[0069] (2) Pour the ultrafine slag powder, fly ash, river sand, γ-phase anhydrous sodium metasilicate, microencapsulated sodium carbonate and water-reducing agent into another mixing bucket and mix thoroughly to form dry mix C.

[0070] (3) Slowly add the activating solution C to the dry mixture C and stir at high speed for 3 minutes to make the resulting slurry fully mixed and uniform, thus obtaining the geopolymer grouting material C.

[0071] The performance of the geopolymer grouting material C is tested, or it is cast and cured according to standard conditions for subsequent mechanical property testing.

[0072] Comparative Example 1

[0073] Raw material formula:

[0074]

[0075]

[0076] Preparation method:

[0077] (1) Add water, water glass and sodium hydroxide to a stirring tank and stir until the sodium hydroxide is completely dissolved to form a uniform activation solution D. Cool the solution to room temperature and set aside.

[0078] (2) Pour the ultrafine slag powder, fly ash, river sand and water-reducing agent into another mixing bucket and mix them thoroughly to form dry mix D.

[0079] (3) Slowly add the activating solution D to the dry mixture D and stir at high speed for 3 minutes to make the resulting slurry fully mixed and uniform, thus obtaining the geopolymer grouting material D.

[0080] The performance of the geopolymer grouting material D is tested, or it is cast and cured according to standard conditions for subsequent mechanical property testing.

[0081] Experimental Example 1

[0082] The grouting materials prepared in Comparative Example 1, Example 1, Example 2, and Example 3 were subjected to performance tests, and the test methods are as follows:

[0083] 1. Flowability Test (Flowability Retention Rate): According to JTG 3420 "Test Procedures for Cement and Cement Concrete in Highway Engineering", the initial flowability of the slurry was tested using a small-sized truncated conical mold (36mm top, 60mm bottom, 60mm height) or an electric slurry table. Then, at 25℃, the flowability of the slurry was tested every 30 minutes, the changes in flowability were recorded, and the flowability retention rate at different times was calculated.

[0084] Flowability retention rate = (flowability at time t / initial flowability) × 100%.

[0085] The time to achieve a 70% flowability retention rate is defined as the "effective pumping time".

[0086] 2. Setting time test: The initial setting time and final setting time of the slurry were tested according to the Vicat tester method in GB / T 1346 "Standard consistency water requirement, setting time and soundness test method of cement paste".

[0087] 3. Compressive strength test: The grout is poured into prism test blocks of 40mm×40mm×160mm and cured for 3 days, 7 days and 28 days under standard curing conditions (temperature 20±2℃, relative humidity ≥95%). Then, the compressive strength is tested according to GB / T 17671 "Test method for strength of cement mortar (ISO method)".

[0088] 4. Permeation Depth Simulation Test: Prepare a transparent acrylic tube with a diameter of 50 mm and a height of 300 mm, filled with tightly compacted standard sand (particle size 0.25-0.5 mm), and a permeable layer at the bottom. Slowly inject the prepared slurry from the top of the tube until the slurry solidifies or stops permeating. Measure the maximum permeation depth of the slurry in the sand layer.

[0089] The test results are shown in the table below:

[0090] Test Project Comparative Example 1 Example 1 Example 2 Example 3 Initial flowability (mm) 235 245 240 250 60-minute flow retention rate (%) 68 90 88 92 90-minute flow retention rate (%) 45 78 75 82 Effective pumping time (min) 50 85 80 95 Initial setting time (min) 80 115 105 125 Final setting time (min) 130 165 155 175 3-day compressive strength (MPa) 22 21.2 22.8 20.5 7-day compressive strength (MPa) 38.5 41.5 43.2 40.8 28-day compressive strength (MPa) 55.3 62.3 64.5 60.7 Penetration depth (cm) 15.8 22.5 21 25.2

[0091] As can be seen from the test results in the table above, compared with Comparative Example 1, the geopolymer grouting materials prepared in Examples 1, 2, and 3 of this invention exhibit significant performance advantages:

[0092] 1. Excellent fluidity retention: The fluidity retention rate of the slurry in Comparative Example 1 dropped to 68% after 60 minutes and only 45% after 90 minutes, with an effective pumping time of only 50 minutes. This indicates that its fluidity decays rapidly and is insufficient to meet the requirements of long-distance or complex formation grouting for a longer effective penetration time. In contrast, Examples 1, 2, and 3, due to the use of a multi-component alkaline activator, effectively maintain the initial high fluidity of the slurry. Their fluidity retention rates all exceed 88% after 60 minutes and remain above 75% after 90 minutes, significantly extending the effective pumping time. Example 3 even reaches 95 minutes, greatly extending the effective penetration distance of the slurry in complex formations and preventing premature solidification that could clog pipelines and formations.

[0093] 2. Precise and controllable setting time: The initial and final setting times of Comparative Example 1 were relatively short, at 80 minutes and 130 minutes respectively. This means that the transition from mixing to hardening of the slurry was relatively compact and difficult to control. In contrast, the embodiments of this invention, through the synergistic effect of rapid-release and slow-release activating components, extended both the initial and final setting times. The initial setting time was between 105-125 minutes, and the final setting time was between 155-175 minutes. This indicates that the slurry has a longer construction window, allowing for sufficient penetration, and achieving rapid and controlled hardening after penetration. For example, Example 2 utilizes a pH-sensitive microencapsulated sodium carbonate and anhydrous sodium carbonate composite system. This maintains high fluidity in the initial stage of the slurry, while the subsequent pH change and exothermic reaction trigger slow release, enabling the slurry to quickly set after reaching the penetration depth, achieving a "precise and controllable transition from high fluidity to rapid setting."

[0094] 3. Higher long-term strength: Although the 3-day compressive strength of the embodiments of the present invention is similar to or even slightly lower than that of Comparative Example 1, its 7-day and 28-day compressive strengths are both higher than those of Comparative Example 1. This indicates that the multi-component alkali activator of the present invention not only optimizes the early fluidity and setting time of the slurry, but also, through the continuous or staged release of the multi-component activator, facilitates the full progress of the geopolymer reaction, thereby promoting the continuous growth and densification of the gel structure, ultimately achieving higher long-term mechanical strength and better consolidation effect. Among them, the 28-day compressive strength of Example 2 reached 64.5 MPa, which is particularly outstanding.

[0095] 4. Significantly Improved Permeability: The simulation test results of the permeation depth clearly demonstrate the advantages of this invention in practical applications. Comparative Example 1 showed a permeation depth of only 15.8 cm, indicating that it quickly lost its fluidity during the permeation process. In contrast, Examples 1, 2, and 3 achieved permeation depths of 22.5 cm, 21.0 cm, and 25.2 cm, respectively, representing increases of 42.4%, 32.9%, and 59.5% compared to Comparative Example 1. This fully demonstrates that the multi-component alkali activator of this invention can effectively extend the effective permeation distance of the grout in highly permeable formations, thereby improving grouting efficiency and consolidation range. This has significant practical implications for grouting projects dealing with complex and fractured formations.

[0096] In summary, by introducing a multi-component alkali activator, this invention successfully achieves precise control of the setting time of geopolymer grouting materials, significantly extending the effective fluidity and penetration distance of the grout while ensuring excellent later-stage strength, demonstrating great potential for engineering applications.

[0097] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope. The scope of protection of the present invention is defined by the appended claims, specification, and their equivalents.

[0098] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. An alkali-activated multi-component slow-release polymer grouting material, characterized in that, Includes the following components by mass: 40-70 parts by weight of cementitious material, 10-40 parts by weight of multi-component alkali activator, 10-30 parts by weight of water, 0-5 parts by weight of optional components, and 15-35 parts by weight of aggregate. The multi-component alkaline activator includes a first alkaline component and a second alkaline component, wherein the activation rate of the first alkaline component is better than that of the second alkaline component. The optional components include additives and / or reinforcing materials.

2. The alkali-activated multi-component slow-release geopolymer grouting material as described in claim 1, characterized in that, The first alkaline component accounts for 30% to 70% of the mass of the multi-component alkaline activator, and the second alkaline component accounts for 70% to 30% of the mass of the multi-component alkaline activator.

3. The alkali-activated multi-component slow-release geopolymer grouting material as described in claim 1, characterized in that, The first alkaline component includes one or more of sodium hydroxide, potassium hydroxide, liquid sodium silicate, and liquid potassium silicate.

4. The alkali-activated multi-component slow-release geopolymer grouting material as described in claim 1, characterized in that, The second alkaline component includes one or more of the following: anhydrous sodium carbonate, γ-Na2SiO3 with a particle size of 50-150 μm, and alkaline substances that have undergone microencapsulation.

5. The alkali-activated multi-component slow-release geopolymer grouting material as described in claim 4, characterized in that... The alkaline substance includes one or more of sodium hydroxide, calcium hydroxide, and sodium carbonate.

6. The alkali-activated multi-component slow-release geopolymer grouting material as described in claim 4, characterized in that, The encapsulation material used in the microencapsulation process includes one or more of polyvinyl alcohol, polylactic acid, and acrylic resin.

7. The alkali-activated multi-component slow-release geopolymer grouting material as described in claim 1, characterized in that, The cementing material includes ultrafine slag and / or fly ash.

8. The alkali-activated multi-component slow-release geopolymer grouting material as described in claim 1, characterized in that, The additives include one or more of the following: water-reducing agents, defoamers, and thickeners; The reinforcing material includes fibers.

9. The alkali-activated multi-component slow-release geopolymer grouting material as described in claim 1, characterized in that, The aggregate includes river sand.

10. A method for preparing an alkali-activated multi-component slow-release geopolymer grouting material according to any one of claims 1-9, characterized in that, Includes the following steps: The first alkaline component is completely dissolved in water to obtain an activation solution; The cementitious materials, aggregates, second alkaline components, and optional components are thoroughly mixed to obtain a dry mixture; The activation solution and the dry mix are thoroughly mixed to obtain an alkali-activated multi-component slow-release polymer grouting material.

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