Underwater non-dispersible quick-hardening early-strength cement-based plugging material and preparation method thereof

Abstract

The invention discloses an underwater non-dispersible quick-hardening early-strength cement-based plugging material and a preparation method thereof, and belongs to the technical field of building materials. The material is prepared from 60%-70% of sulphoaluminate cement, 0.01%-0.02% of silane modified hydroxypropyl methyl cellulose, 0.1%-0.2% of a lithium salt coagulant, 1%-2% of a water reducing agent, 0.01%-0.02% of a retarder and 30%-40% of iron tailings (the fineness is 100-200 meshes, and SiO2 is larger than or equal to 65%), and the on-site water-binder ratio is 28%-32%. The material is suitable for karst water burst, cofferdam piping and other flowing water scenes, the plugging success rate reaches 98%, compared with a traditional scheme, the cost is reduced by 80%, and industrial solid waste is consumed by 30% or above.

Description

Technical Field

[0001] This invention belongs to the field of new materials, and specifically discloses an underwater non-dispersible, fast-hardening, early-strength cement-based plugging material and its preparation method. Background Technology

[0002] In scenarios such as karst geological seepage and emergency repairs of cofferdams in water conservancy projects, underwater rapid plugging materials must simultaneously meet multiple stringent performance requirements: resistance to water erosion and non-dispersion, rapid setting and hardening capacity, early high strength development characteristics, and environmental adaptability. Traditional silicate cement-based materials face a core contradiction in underwater environments—to improve anti-dispersion properties, thickening components (such as cellulose ethers) need to be added, but high dosages will significantly delay setting and weaken early strength; while relying solely on special cements (such as sulfoaluminate cement) can shorten setting time, the hydration products are easily washed away by water flow due to insufficient stability.

[0003] Current mainstream technologies have significant limitations: while polymer-modified cement systems improve underwater adhesion, the retarding effect of polymers leads to slow strength development, making it difficult to meet the requirements for rapid water sealing; chemical grouting materials (such as polyurethane) possess instantaneous expansion characteristics, but are costly and pose environmental risks; rapid-setting cement-based materials often rely on high-alkalinity activators (such as sodium aluminate), which exacerbate material shrinkage and reduce long-term durability. Furthermore, existing technologies mostly use high-cost aggregates such as quartz sand, failing to effectively address the issue of industrial solid waste resource utilization.

[0004] Therefore, there is an urgent need to develop a cement-based plugging material that combines underwater anti-dispersion properties, minute-level rapid setting ability, and hour-level high strength development, while also realizing the high-value-added utilization of industrial solid waste, in order to meet the rapid plugging needs of complex dynamic water environments. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention discloses an underwater non-dispersible, fast-hardening, early-strength cement-based plugging material and its preparation method.

[0006] To achieve the above objectives, the present invention includes the following technical solutions.

[0007] An underwater non-dispersible, fast-hardening, early-strength cement-based sealing material, composed of the following components by mass percentage:

[0008]

[0009]

[0010] In the above scheme, sulfoaluminate cement provides a fast-hardening skeleton, lithium salt accelerator accelerates hydration, and silane-modified hydroxypropyl methylcellulose and iron tailings powder synergistically increase viscosity and resist dispersion. In some embodiments, minute-level setting (≤20min) and underwater strength retention rate ≥90% are achieved (Test Example 2), and the overall cost is reduced by 80%.

[0011] Furthermore, in the aforementioned underwater non-dispersible, fast-hardening, early-strength cement-based plugging material, the preparation method of the silane-modified hydroxypropyl methylcellulose is as follows: 5g of hydroxypropyl methylcellulose is added to 100mL of methanol, stirred and dispersed at 400r / min for 8min, 1g of composite silane coupling agent is added, heated to 45℃, stirred and reacted for 1h, filtered, washed, and dried to obtain silane-modified hydroxypropyl methylcellulose; the composite silane coupling agent is composed of KH550 and KH570 in a mass ratio of 1:1; the synergistic effect of silane-modified hydroxypropyl methylcellulose and iron tailings micropowder significantly improves the cohesiveness of the slurry.

[0012] Furthermore, in the aforementioned underwater non-dispersible, fast-hardening, early-strength cement-based plugging material, the lithium salt accelerator is selected from at least one of lithium silicate or lithium carbonate. In the above scheme, lithium silicate / lithium carbonate has a specific activating effect on the hydration phase (ettringite) of sulfoaluminate cement, which can avoid the shrinkage risk of high-alkalinity accelerators (such as sodium aluminate) and ensure low-temperature final setting ≤45min (see Test Example 3 in the specific implementation).

[0013] Furthermore, in the aforementioned underwater non-dispersible, fast-hardening, early-strength cement-based sealing material, the retarder is selected from at least one of boric acid, sodium gluconate, or sodium citrate. In the above scheme, boric acid / sodium gluconate / sodium citrate selectively inhibit the early hydration peak of aluminate, which can precisely control the setting gradient and avoid the failure mechanism caused by excessive retarder addition, which leads to initial setting >20 min (see Comparative Example 4).

[0014] Furthermore, in the aforementioned underwater non-dispersible, fast-hardening, early-strength cement-based sealing material, the water-reducing agent is a polycarboxylate-based high-efficiency water-reducing agent or a naphthalene-based water-reducing agent. The polycarboxylate / naphthalene-based water-reducing agent is suitable for low water-cement ratio (28-32%) systems, ensuring a slurry flowability ≥200mm and overcoming the pumping resistance caused by the thickening effect of silane-modified hydroxypropyl methylcellulose.

[0015] Furthermore, the aforementioned underwater non-dispersible, fast-hardening, early-strength cement-based plugging material has an initial setting time of ≤20 minutes and a final setting time of ≤40 minutes; a 1-hour compressive strength of ≥5MPa and a 24-hour compressive strength of ≥15MPa.

[0016] Furthermore, the aforementioned underwater non-dispersible, fast-hardening, early-strength cement-based plugging material has iron tailings with a fineness of 100-200 mesh, SiO2 content ≥65%, and Fe2O3 content ≤10%. The fineness of the iron tailings (100-200 mesh) matches the particle size distribution of cement, and the active SiO2 participates in secondary hydration, resulting in the following beneficial effects: reduced bleeding of micro-aggregates (bleeding rate ≤0.8%) and a 15.4% increase in strength (see Test Example 4), while reducing costs by 27.6%.

[0017] This invention also discloses a method for preparing the above-mentioned sealing material, comprising the following steps:

[0018] (a) Sulfoaluminate cement, silane-modified hydroxypropyl methylcellulose, lithium salt accelerator, water-reducing agent, retarder and iron tailings are dry-mixed evenly according to the proportion to obtain premixed powder;

[0019] (b) During on-site construction, the premixed powder and water are added to a high-speed mixer with a speed of ≥1000 rpm and stirred to form a uniform slurry; the mass ratio of water to premixed powder is 28-32:100.

[0020] (c) Inject the grout into the leaking area using a pressure grouting device.

[0021] The preparation method uses dry pre-dispersion + high-speed wet mixing (≥1000rpm) to solve the problem of clumping of silane-modified hydroxypropyl methylcellulose, achieving a slurry uniformity variation coefficient ≤5% and ensuring stable anti-dispersion properties.

[0022] Furthermore, in the above preparation method, step (a) dry mixing process uses a double-helix conical mixer, with a mixing time ≥15 minutes and a mixing uniformity variation coefficient ≤5%. The double-helix conical mixer is used to eliminate component segregation caused by differences in specific gravity.

[0023] Furthermore, in the above preparation method, the stirring time in step (b) is controlled within 1-3 minutes, and the slurry fluidity is ≥200mm. In this scheme, the high-speed stirring shear force for 1-3 minutes breaks the air bubbles encapsulated in the silane-modified hydroxypropyl methylcellulose, resulting in a dense slurry without pores, thus avoiding water seepage channels after slurrying.

[0024] This invention also discloses the application of the aforementioned sealing material for rapid sealing of karst geological fissures, underground engineering water inrush, or construction cofferdams under dynamic water conditions, with a grouting pressure range of 0.2-1.0 MPa. The grouting pressure of 0.2-1.0 MPa drives the grout to penetrate deep into the fissure. In some test cases, a 98% sealing success rate was achieved in dynamic water with a flow velocity of 2.8 m / s, reducing emergency response costs.

[0025] Compared with the prior art, the present invention has the following outstanding advantages:

[0026] This invention fundamentally solves the industry dilemma of underwater plugging materials' inability to coexist in terms of anti-dispersion, rapid setting, and early strength through multi-level synergy of sulfoaluminate cement, lithium salt accelerator, iron tailings powder, and silane-modified hydroxypropyl methylcellulose. The specific activation of cement hydration by lithium salts enables the material to solidify rapidly within minutes in a dynamic water environment, reducing material loss rate by over 80% under traditional processes and significantly improving emergency response efficiency. The synergistic effect of silane-modified hydroxypropyl methylcellulose and iron tailings powder significantly improves the slurry's cohesiveness (flowability ≥200mm, bleeding rate ≤0.8%). The fineness of the iron tailings (100-200 mesh) and the active components (SiO2 ≥65%) result in a 1-hour strength ≥5MPa and a 24-hour strength ≥15MPa, giving the slurry excellent underwater forming stability and effectively resisting high-speed water flow erosion. The value-added application of iron tailings as industrial solid waste not only enhances density through the micro-aggregate filling effect but also significantly reduces resource consumption costs, promoting a green transformation of "using waste to treat leaks." This material exhibits strong adaptability under harsh conditions such as low temperatures in cold regions and high pressure in karst formations, and its reliable performance is ensured by high-speed mixing technology. Ultimately, its rapid sealing characteristics and cost advantages throughout its entire life cycle enable an order-of-magnitude increase in engineering maintenance benefits, achieving a dual benefit of technological breakthrough and economic and environmental protection. Detailed Implementation

[0027] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] The following is the raw material list for the examples.

[0029] Table 1 Raw materials for the examples

[0030]

[0031] Table 2: Raw Materials for Comparative Examples

[0032] control group Replacement materials parameter Comparative Example 1 Ordinary Portland cement P·O 42.5 <![CDATA[Specific surface area 350 m 2 / kg]]> Comparative Example 2 Sodium sulfate (as a substitute for lithium salts) <![CDATA[Na2SO4≥99%, D50 particle size 10 - 20μm]]> Comparative Example 4 crude iron tailings <![CDATA[SiO2 68%, fineness 60 mesh]]> Comparative Example 3 Quartz sand <![CDATA[SiO2≥98%, fineness 100 mesh]]>

[0033] Example 1

[0034] 1. Material composition (mass%):

[0035] Sulfoaluminate cement: 65%

[0036] Silane-modified hydroxypropyl methylcellulose: 0.015%

[0037] Lithium silicate (accelerator): 0.15%

[0038] Polycarboxylate superplasticizer: 1.5%

[0039] Sodium gluconate (retarder): 0.015%

[0040] Iron tailings (fineness 150 mesh, SiO2 68%, Fe2O3 38%): 33.32%

[0041] Water-to-binder ratio: 30%

[0042] 2. Preparation method:

[0043] Dry mixing: Add each component to a twin-helix mixer (20 rpm, 20 minutes);

[0044] Pulping: Mix the powder and water in a high-speed mixer at 1200 rpm for 2 minutes;

[0045] Grouting: The grout is injected into simulated karst fissures at a pressure of 0.5 MPa using a grouting pump (flow rate 1.5 m / s).

[0046] 3. Performance Testing:

[0047] Setting time: initial setting 18 min, final setting 35 min (GB / T 1346)

[0048] Underwater strength: 5.8 MPa compressive strength after 1 hour, 16.3 MPa after 24 hours (GB / T 50080)

[0049] Anti-dispersion properties: The strength retention rate of underwater-formed specimens was 93% (JTG 3420-2020).

[0050] Sealing effect: The flow stops 40 seconds after grouting and there is no leakage after 1 hour.

[0051] Example 2

[0052] 1. Material composition (mass%):

[0053] Sulfoaluminate cement: 60%

[0054] Silane-modified hydroxypropyl methylcellulose: 0.02%

[0055] Lithium carbonate (coagulant): 0.2%

[0056] Naphthalene-based water-reducing agent: 2%

[0057] Boric acid (retarder): 0.01%

[0058] Iron tailings (fineness 200 mesh, SiO2 70%, Fe2O3 6%): 37.77%

[0059] Water-to-binder ratio: 28%

[0060] 2. Preparation method:

[0061] The dry mixing process is the same as in Example 1;

[0062] Pulping: Stir at 1500 rpm for 1.5 minutes (pulp fluidity 230mm);

[0063] Grouting: Grouting is performed at the piping point of the cofferdam (water pressure 0.3MPa).

[0064] 3. Performance Testing:

[0065] Setting time: Initial setting 15 min, final setting 32 min

[0066] Underwater strength: 6.2 MPa after 1 hour, 17.1 MPa after 24 hours.

[0067] Volume stability: 0.018% shrinkage after 28 days (GB / T 50082)

[0068] Solid waste utilization rate: Iron tailings content 37.77%.

[0069] Example 3

[0070] 1. Material composition (mass%):

[0071] Sulfoaluminate cement: 70%

[0072] Silane-modified hydroxypropyl methylcellulose: 0.01%

[0073] Lithium carbonate (coagulant): 0.1%

[0074] Polycarboxylate superplasticizer: 1%

[0075] Sodium citrate (retarder): 0.02%

[0076] Iron tailings (fineness 100 mesh, SiO2 65%, Fe2O3 9%): 28.87%

[0077] Water-to-binder ratio: 32%

[0078] 2. Preparation method:

[0079] Iron tailings pretreatment: ball milling to a fineness ≥200 mesh (screen residue ≤5%);

[0080] Pulping: Stir at 1000 rpm for 3 minutes (for construction in low-temperature environments of 5℃);

[0081] Grouting: Grouting of inclined holes in karst water inflow channels (flow velocity 2.8m / s).

[0082] 3. Performance Testing:

[0083] Low temperature adaptability: Final setting time at 5℃ ≤ 45 min

[0084] Erosion resistance: Material retention rate >95% at a flow velocity of 2.8 m / s.

[0085] Long-term durability: No shrinkage in underwater strength after 90 days (GB / T 50082).

[0086] Comparative Example 1

[0087] Traditional silicate cement-based materials

[0088] Composition: 100% P·O 42.5 cement + 0.5% silane-modified hydroxypropyl methylcellulose, water-binder ratio 40%. Properties:

[0089] Initial setting time > 120 min, final setting time > 240 min

[0090] 1-hour strength: 0 MPa; 24-hour strength: 3.2 MPa

[0091] Underwater molding results in collapse (strength retention rate <20%).

[0092] Comparative Example 2

[0093] Lithium salt accelerator missing

[0094] Composition: Same as in Example 1, but lithium silicate is removed.

[0095] performance:

[0096] Initial setting time extended to 55 min, final setting time > 90 min

[0097] The strength after 1 hour is only 1.3 MPa (compared to 5.8 MPa in Example 1).

[0098] Grout loss due to water flow after injection >50%.

[0099] Comparative Example 3

[0100] Iron tailings replacing quartz sand

[0101] Composition: Same as in Example 1, but iron tailings are replaced with an equal amount of 100-mesh quartz sand.

[0102] performance:

[0103] 1-hour strength: 4.1 MPa (↓29%), 24-hour strength: 12.7 MPa (↓22%)

[0104] Slurry sedimentation and segregation (bleeding rate >15% after standing for 10 minutes)

[0105] Costs increased by 40% (iron tailings ¥80 / ton vs. quartz sand ¥350 / ton).

[0106] Comparative Example 4

[0107] Incorrect lithium salt type + insufficient fineness of iron tailings

[0108] 1. Material composition (mass%):

[0109] Sulfoaluminate cement: 65%

[0110] Silane-modified hydroxypropyl methylcellulose: 0.015%

[0111] Sodium sulfate (alternative lithium salt coagulant): 0.15% (incorrect coagulant type).

[0112] Polycarboxylate superplasticizer: 1.5%

[0113] Sodium gluconate: 0.015%

[0114] Iron tailings (fineness 60 mesh, SiO2 68%, Fe2O3 8%): 33.32% (fineness less than 100 mesh)

[0115] Water-to-binder ratio: 30%

[0116] Preparation method: Same as in Example 1 (stir at 1200 rpm for 2 minutes)

[0117] The performance test results are shown in Table 3.

[0118] Table 3: Performance Comparison of Example 1

[0119]

[0120]

[0121] Comparative Example 5

[0122] Out of range water-cement ratio

[0123] Composition: Same as Example 1, but the water-to-binder ratio is increased to 38%.

[0124] performance:

[0125] Insufficient slurry viscosity (failure of anti-dispersion properties, strength retention rate ↓ to 65%)

[0126] The 24-hour strength is only 9.8 MPa (↓40%).

[0127] Water seepage channels appeared after grouting.

[0128] Test Example 1

[0129] Verification of dynamic water condensation characteristics

[0130] 1. Objective: To verify the material's rapid solidification and erosion resistance in a flowing water environment.

[0131] 2. Method:

[0132] Build a circulating water tank (flow rate 2.0m / s, water depth 30cm).

[0133] Slurries were prepared according to Examples 1-3 and Comparative Examples 1-5 and poured into a mold (10×10×10cm).

[0134] Record the initial setting time (the surface of the slurry resists water erosion without damage).

[0135] Determination of underwater strength after 1 hour (GB / T 50081)

[0136] The results are shown in Table 4.

[0137] Table 4: Test of condensation characteristics of dynamic water

[0138] Group Initial setting time (min) 1-hour compressive strength (MPa) erosion resistance Example 1 18 5.8 Surface intact and free from corrosion Example 2 15 6.2 Slight wear on the edges Comparative Example 1 >120* 0 (collapse) Complete dissolution and loss Comparative Example 4 42 2.1 honeycomb-like erosion pits on the surface

[0139] Note: Traditional silicate cement cannot be molded in moving water.

[0140] The following conclusions can be drawn from Table 4:

[0141] The combination of lithium salt accelerator and sulfoaluminate cement resulted in an initial setting time of ≤20 min (133% longer than in Comparative Example 4), and a strength of >5 MPa at 1 hour, meeting the requirements for rapid sealing of flowing water.

[0142] Test Example 2

[0143] Anti-dispersion quantification test

[0144] Objective: To evaluate the material retention rate during underwater molding.

[0145] method:

[0146] Underwater anti-dispersion test was conducted according to JTG 3420-2020 "Specifications for Cement Testing in Highway Engineering":

[0147] The slurry is poured into a standard mold in still / flowing water (1.5 m / s).

[0148] Calculate the strength retention rate = (underwater strength / air strength) × 100%

[0149] Measurement of suspended solids concentration (filtration and drying method)

[0150] The results are shown in Table 5.

[0151] Table 5 Quantitative Tests of Anti-dispersion

[0152] Group Static water strength retention rate Dynamic water strength retention rate Suspended solids (mg / L) Example 3 97％ 95％ 28 Comparative Example 2 65％ 58％ 152 Comparative Example 5 72％ 65％ 89

[0153] From Table 5, we can draw the following conclusions:

[0154] Silane-modified hydroxypropyl methylcellulose and iron tailings powder synergistically form a spatial network (the suspended solids in Example 3 were only 28 mg / L), which, compared with Comparative Example 2 which lacked lithium salt, showed an improvement in anti-dispersion properties of >35%.

[0155] Test Example 3

[0156] Low-temperature early strength performance verification

[0157] Objective: To test the strength development rate at a low temperature of 5℃.

[0158] method:

[0159] Molded specimens in a constant temperature water bath (5±0.5℃)

[0160] Determination of setting time (penetration resistance method, GB / T 1346)

[0161] Compressive strength tested at 1h / 3h / 24h (GB / T 50081)

[0162] The results are shown in Table 6.

[0163] Table 6 Low-Temperature Early Strength Performance Verification

[0164] Group Final setting time at 5℃ (min) 1-hour intensity (MPa) 3-hour strength (MPa) Example 1 40 3.5 8.2 Example 3 45 3.1 7.6 Comparative Example 4 >180 0.8 2.3 Comparative Example 5 90 1.9 4.0

[0165] From Table 6, we can conclude that:

[0166] Strictly control the water-cement ratio (28-32%) to ensure low-temperature hydration efficiency, with a 3-hour strength >7MPa (90% improvement compared to control 5), meeting the requirements for emergency rescue in cold regions.

[0167] Test Example 4

[0168] Validation of the synergistic effect of iron tailings

[0169] Objective: To quantify the contribution of iron tailings to the stability and strength of slurry.

[0170] method:

[0171] Slurry stability: Bleeding rate measured after standing for 30 minutes (GB / T 50080)

[0172] Economic calculation: Material cost (iron tailings ¥80 / ton vs. quartz sand ¥350 / ton)

[0173] The results are shown in Table 7.

[0174] Table 7. Verification of the Synergistic Effect of Iron Tailings

[0175] index Example 1 (Iron Tailings) Comparative Example 3 (quartz sand) difference 28-day intensity 48.7MPa 42.1MPa ↑15.7％ Perfusion rate 0.8％ 5.2％ ↓84.6％ Cost per ton of material ￥420 ￥580 ↓27.6％

[0176] in conclusion:

[0177] Iron tailings powder (100-200 mesh) serves as both a micro-aggregate to reduce bleeding and a component in the hydration reaction to enhance strength, offering both performance and economic advantages.

[0178] Test Example 5

[0179] Environmental impact and solid waste utilization assessment

[0180] Objective: To verify the environmental compatibility and resource utilization benefits of the materials.

[0181] method:

[0182] Heavy metal leaching: Cd / Pb / Cr / Ni leaching concentration was tested according to GB 5085.3.

[0183] CO2 Emission Accounting: Comparison of Carbon Footprint of Sulfoaluminate Cement (Example) and Silicate Cement (Comparative Example 1)

[0184] Solid waste disposal volume: Iron tailings consumption per ton of material

[0185] The results are shown in Table 8.

[0186] Table 8 Comparison of Environmental Friendliness and Solid Waste Utilization Assessments

[0187]

[0188]

[0189] Conclusion: Replacing natural aggregate with iron tailings reduced carbon emissions by 43%, and no heavy metal leaching was detected, achieving "treating leakage with waste".

[0190] Test Example 6

[0191] Comprehensive construction benefit simulation

[0192] Objective: To quantify the engineering benefits of rapid leak sealing.

[0193] Model:

[0194] Scenario: Piping of a cofferdam at a hydropower station (water inflow of 50m³) 3 / h, water pressure 0.4MPa)

[0195] Parameter: Blocking success rate × unit time loss (electricity cost ¥0.3 / kWh + downtime loss)

[0196] ¥10,000 / h

[0197] The results are shown in Table 9.

[0198] Table 9. Simulation of Comprehensive Construction Benefits

[0199] Group Average sealing time Success rate Cost per repair (ten thousand yuan) Example 2 35min 98％ 0.85 Comparative Example 1 >24h* 30％ 24.6 Comparative Example 4 120min 65％ 3.2

[0200] Note: Traditional materials require dewatering after the well is built in advance.

[0201] Conclusion: This invention, through its rapid coagulation (≤20min) and early strength (≥5MPa in 1h) characteristics, reduces emergency response costs to 3.5% of traditional solutions, while increasing efficiency by 28 times.

[0202] Test data summary:

[0203] The core technological advantages of this invention have been fully verified through six test cases:

[0204] Rapid setting in flowing water: initial setting ≤20min (test example 1), solving the industry problem of material loss caused by water erosion;

[0205] Underwater anti-dispersion: Strength retention rate >90% (Test Example 2), breaking through the limitation of traditional materials collapsing during underwater molding;

[0206] Low-temperature early strength: Strength >7MPa after 3 hours at 5℃ (Test Example 3), enabling all-weather construction of projects in cold regions;

[0207] Solid waste value-added: Iron tailings content >30% improves performance by 15.7% (test example 4), resource utilization and high performance are synergistic;

[0208] Environmentally friendly: carbon emissions were reduced by 43% and heavy metals were not detected (test case 5), responding to the dual-carbon policy;

[0209] Economical and efficient: The cost of a single emergency repair is reduced by 96% (Test Case 6), reshaping the standards for the effectiveness of leak sealing projects.

[0210] The above are merely a few preferred embodiments of the present invention, described in a relatively specific and detailed manner, but they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention.

Claims

1. An underwater non-dispersible, fast-hardening, early-strength cement-based sealing material, characterized in that, It consists of the following components by mass percentage:

2. The underwater non-dispersible, fast-hardening, early-strength cement-based plugging material according to claim 1, characterized in that, The lithium salt coagulant is selected from at least one of lithium silicate or lithium carbonate.

3. The underwater non-dispersible, fast-hardening, early-strength cement-based plugging material according to claim 1, characterized in that, The retarder is selected from at least one of boric acid, sodium gluconate, or sodium citrate.

4. The underwater non-dispersible, fast-hardening, early-strength cement-based plugging material according to claim 1, characterized in that, The water-reducing agent is a polycarboxylate-based high-efficiency water-reducing agent or a naphthalene-based water-reducing agent.

5. The underwater non-dispersible, fast-hardening, early-strength cement-based plugging material according to claim 1, characterized in that, Initial setting time ≤ 20 minutes, final setting time ≤ 40 minutes; 1-hour compressive strength ≥ 5 MPa, 24-hour compressive strength ≥ 15 MPa.

6. The underwater non-dispersible, fast-hardening, early-strength cement-based plugging material according to claim 1, characterized in that, The iron tailings have a fineness of 100-200 mesh, a SiO2 content of ≥65%, and an Fe2O3 content of ≤10%.

7. The method for preparing the sealing material according to any one of claims 1-6, characterized in that, Includes the following steps: (a) Sulfoaluminate cement, silane-modified hydroxypropyl methylcellulose, lithium salt accelerator, water-reducing agent, retarder and iron tailings are dry-mixed evenly according to the proportion to obtain premixed powder; (b) During on-site construction, the premixed powder and water are added to a high-speed mixer with a speed of ≥1000 rpm and stirred to form a uniform slurry; the mass ratio of water to premixed powder is 28-32:

100. (c) Inject the grout into the leaking area using a pressure grouting device.

8. The preparation method according to claim 7, characterized in that, Step (a) The dry mixing process uses a double spiral conical mixer, with a mixing time of ≥15 minutes and a mixing uniformity variation coefficient of ≤5%.

9. The preparation method according to claim 7, characterized in that, The stirring time in step (b) should be controlled within 1-3 minutes, and the slurry fluidity should be ≥200mm.

10. The application of the sealing material according to any one of claims 1-6, characterized in that, It is used for rapid sealing of karst geological fissures, underground engineering water inrush, or construction cofferdam under dynamic water conditions, with a grouting pressure range of 0.2-1.0 MPa.

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