High-adhesion impervious coal seam extraction grouting hole sealing material and preparation method thereof
By leveraging the synergistic effects of components such as nano-silica, polymer emulsion, and fibers, a highly adhesive and impermeable coal seam extraction grouting sealing material has been developed. This solves the problem of poor sealing effect of traditional materials in underground coal mines, achieving efficient and long-term sealing effect as well as environmental friendliness and economy.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHANXI HAOBORUI NEW MATERIAL CO LTD
- Filing Date
- 2026-04-13
- Publication Date
- 2026-05-15
AI Technical Summary
Existing coal seam extraction grouting sealing materials are prone to debonding and have poor permeability under high ground stress and mining influence, and lack flexibility, making it difficult to effectively seal holes in the complex environment of underground coal mines for a long time.
Using components such as nano-silica, polymer emulsion, polypropylene fiber and calcium-based expanding agent, a highly adhesive and impermeable coal seam extraction grouting sealing material is formed through nano-filling, film formation and toughening effects, combined with micro-reinforcement and shrinkage compensation.
It achieves a synergistic improvement in high adhesion and high impermeability, extends the effective service cycle of the extraction borehole, reduces maintenance costs, and is both environmentally friendly and economical.
Smart Images
Figure CN122037896A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of coal mine engineering materials technology, and more specifically, to a high-bonding, impermeable coal seam extraction grouting sealing material and its preparation method. Background Technology
[0002] Coal seam gas extraction is a key technology for preventing coal mine gas disasters and promoting the utilization of gas resources. In this process, injecting grouting material into the borehole to seal the annular gap between the borehole and the coal and rock mass to form a highly efficient sealed section is the core link to ensure the concentration and efficiency of gas extraction. The quality of the sealing is directly related to the gas extraction effect and the safety of underground operations.
[0003] Currently, the coal seam extraction grouting sealing materials widely used in engineering are mainly ordinary cement-based materials, or simply mixed with cheap fillers such as fly ash and bentonite. However, these traditional materials have revealed many limitations in practical applications: First, their bonding strength with coal and rock mass is generally low. Under high ground stress and mining influence, they are prone to debonding and cracking at the interface between the grouting body and the coal and rock mass, forming gas leakage channels. Second, the materials themselves have poor impermeability, and the inherent shrinkage cracking tendency of cement-based materials will further aggravate the penetration, leading to sealing failure. Furthermore, traditional materials are not flexible enough and are brittle, making it difficult to adapt to the complex surrounding rock deformation in coal mines.
[0004] In addition, although some improvement technologies attempt to improve adhesion or crack resistance by adding polymer emulsions or fibers, they often fail to achieve synergistic improvement of various properties and fail to effectively optimize the porosity characteristics of the material from the microstructure, resulting in unsatisfactory durability and long-term sealing effect under harsh coal seam conditions.
[0005] Therefore, this application addresses the shortcomings of existing methods by providing a high-bonding, impermeable coal seam extraction grouting sealing material and its preparation method. Summary of the Invention
[0006] In order to overcome the above-mentioned defects of the prior art, the present invention provides a high-bonding and impermeable coal seam extraction grouting sealing material and its preparation method, so as to solve the problems mentioned in the background art.
[0007] To achieve the above objectives, the present invention provides the following technical solution: a high-bonding, impermeable coal seam extraction grouting and sealing material, which, by weight, is composed of the following components: Basic cementitious materials: 100 parts ordinary Portland cement and 20-30 parts blast furnace slag powder; Nanoscale functional filler: 3-5 parts nano-silica; Polymer modifier: 8-12 parts polymer emulsion; Chemical admixtures: 0.8-1.2 parts polycarboxylate superplasticizer and 0.3-0.5 parts cellulose ether; Physical reinforcement components: 0.8-1.5 parts polypropylene fiber and 4-6 parts calcium-based expanding agent; Mixing water: 35-45 parts water; The material has a water-cement ratio of 0.35 to 0.40, a 28-day compressive strength of not less than 40 MPa, a bond strength with coal and rock mass of not less than 2 MPa, and a permeability grade of not less than P12.
[0008] Preferably, the specific surface area of the blast furnace slag powder is not less than 400 m² / kg, and the particle size range of the nano-silica is 10-20 nm.
[0009] Preferably, the polymer emulsion is a styrene-acrylic emulsion with a solid content of 50%, and the viscosity of the cellulose ether is 4000 mPa·s.
[0010] Preferably, the polypropylene fiber has a length of 6-12 mm, and the calcium-based expansive agent is a UEA-type concrete expansive agent.
[0011] Preferably, the material has a slurry fluidity of not less than 180 mm and a strength loss of not more than 10% after 50 freeze-thaw cycles.
[0012] This invention also provides a preparation method for preparing the above-mentioned high-bonding, impermeable coal seam extraction grouting and sealing material, specifically including the following steps: S1. Dry mixing pretreatment: Put ordinary silicate cement, blast furnace slag powder, nano silica and calcium-based expansion agent into a mixer and dry mix at a speed of 200-300 rpm for 5-10 minutes until the mixture is uniform. S2. Liquid preparation: In another container, mix the polymer emulsion, polycarboxylate superplasticizer, cellulose ether and water, and stir at medium speed for 3-5 minutes to form a homogeneous solution. S3. Mix and stir: Slowly add the liquid material prepared in S2 to the dry mixture in S1, and stir at a speed of 200-300 rpm for 10-15 minutes to form a uniform and lump-free slurry. S4. Fiber dispersion: Add polypropylene fiber to the slurry obtained in S3 and continue stirring for 5 minutes to ensure that the fiber is evenly dispersed in the slurry. S5. Quality Inspection and Application: The fluidity, setting time, and density of the obtained slurry are tested. Once qualified, it is immediately used for grouting and sealing of coal seam boreholes.
[0013] Preferably, in the dry mixing pretreatment in step S1, the nano-silica is added in steps, first premixed with blast furnace slag powder for 30 seconds, and then other dry powder components are added.
[0014] Preferably, during the mixing and stirring process in step S3, the temperature of the slurry is controlled between 5-30°C.
[0015] Preferably, in the quality inspection of step S5, the initial setting time of the slurry is not earlier than 45 min, the final setting time is not later than 10 h, and the density range is 1.8-2.2 g / cm³.
[0016] Preferably, in step S5, the grout is injected into the coal seam extraction borehole by a pressure grouting pump, and the grouting pressure is 0.5-1.0 MPa.
[0017] The technical effects and advantages of this invention are as follows: 1. This invention successfully solves the technical contradiction of high adhesion and high impermeability in traditional materials by combining the multiple composite synergistic effects of nano-filling and volcanic ash effect of nano-silica, film formation and toughening effect of polymer emulsion, and crack resistance and shrinkage compensation effect of fiber and expansion agent. It can effectively cope with the harsh conditions of high ground pressure and high permeability in coal seams and prevent gas leakage and water seepage. 2. This invention significantly improves the crack resistance of the material by introducing the micro-reinforcing effect of polypropylene fibers and the shrinkage compensation function of calcium-based expanding agents, and combining them with the flexibility of polymer emulsions. This greatly extends the effective service cycle of the extraction borehole and reduces maintenance costs. 3. The material of this invention achieves high performance while maintaining excellent fluidity and reasonable setting time. It is fully compatible with existing grouting equipment and processes, and is easy to prepare and pump on-site. At the same time, the formula makes extensive use of blast furnace slag powder, an industrial by-product, which is in line with the development direction of green building materials. While improving performance, it reduces raw material costs and environmental impact, and has significant economic and social benefits. Attached Figure Description
[0018] Figure 1 This is a flowchart illustrating the overall steps of the present invention. Detailed Implementation
[0019] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.
[0020] Example 1 This invention provides a high-bonding, impermeable coal seam extraction grouting and sealing material, which, by weight, consists of the following components: 100 parts of ordinary Portland cement; 20 parts of blast furnace slag powder, with a specific surface area of 450 m² / kg; Three parts of nano-silica, with a particle size of 15nm and a purity of 99.8%; 8 parts of styrene-acrylic emulsion, solid content 50%, glass transition temperature -5℃; 0.8 parts of polycarboxylate superplasticizer, water reduction rate 30%; 0.3 parts of cellulose ether, viscosity 4000 mPa·s; 0.8 parts of polypropylene fiber, 8 mm in length, 18 μm in diameter, tensile strength 550 MPa; Four parts of UEA-type calcium-based expanding agent, with a magnesium oxide content of 8%; 35 parts water; Water-cement ratio: 0.35.
[0021] Based on this embodiment, the present invention also provides a preparation method for preparing the above-mentioned high-bonding, impermeable coal seam extraction grouting sealing material. The specific preparation method is as follows: S1. Dry mixing pretreatment: Premix nano-silica with blast furnace slag powder in a dry state for 30 seconds to ensure that the nano particles are evenly dispersed in the slag powder. Put the pretreated mixture, ordinary silicate cement and UEA expansion agent into a forced mixer and dry mix at 250±10 rpm for 8 minutes until the material color is uniform. S2. Liquid preparation: In another plastic container, add tap water, styrene-acrylic emulsion, polycarboxylate superplasticizer and cellulose ether in sequence, and stir with a mechanical stirrer at 800 rpm for 4 minutes to form a homogeneous and stable emulsion system. S3. Mix and stir: Slowly add the prepared liquid to the dry mixture within 1 minute, keep the mixer speed at 250±10 rpm, and continue stirring for 12 minutes to form a uniform, lump-free, and fluid slurry. S4. Fiber dispersion: Add polypropylene fiber to the slurry and continue stirring for 5 minutes to ensure that the fiber is dispersed monofilamentally in the slurry without agglomeration.
[0022] Throughout the preparation process, the slurry temperature was controlled within the range of 20±5℃ using a water bath.
[0023] The material obtained in Example 1 was tested, and its performance data are as follows: Performance characteristics: Flowability 185±3mm, initial setting time 65±5min, final setting time 8.5±0.3h, density 2.05±0.02g / cm³, water bleeding rate 0.8%, 30min flowability retention value 175mm; Mechanical properties: 3d compressive strength 25.8±0.8MPa, 7d compressive strength 36.2±1.2MPa, 28d compressive strength 42.5±1.5MPa, bond strength 2.1±0.2MPa, elastic modulus 18.5±0.5GPa, flexural-compression ratio 0.28; Durability: Impermeability grade P12, strength loss after 50 freeze-thaw cycles 8.5±0.5%, relative dynamic modulus of elasticity 92.5%, 28-day shrinkage 285±15×10 -6 The chloride ion diffusion coefficient is 3.2 ± 0.3 × 10⁻⁶. -12 m² / s, carbonization depth 1.2 mm.
[0024] Example 2 This invention provides a high-bonding, impermeable coal seam extraction grouting and sealing material, which, by weight, consists of the following components: 100 parts of ordinary Portland cement; 25 parts of blast furnace slag powder, with a specific surface area of 420 m² / kg; Four parts of nano-silica, with a particle size of 12nm and a purity of 99.8%; 10 parts of styrene-acrylic emulsion, solid content 50%, glass transition temperature -5℃; One part of polycarboxylate superplasticizer, water reduction rate 30%; 0.4 parts of cellulose ether, viscosity 4000 mPa·s; 1.2 parts of polypropylene fiber, 10 mm in length, 18 μm in diameter, tensile strength 550 MPa; 5 parts of UEA type calcium-based expanding agent, with a magnesium oxide content of 8%; 40 parts water; Water-cement ratio: 0.38.
[0025] This embodiment also provides a preparation method. The difference between Example 2 and Example 1 is that the dry mixing time is 7 min, the liquid stirring time is 3.5 min, the mixing time is 13 min, and the slurry temperature is controlled at 18±3℃. All other aspects are the same as in Example 1.
[0026] The material obtained in Example 2 was tested, and its performance data are as follows: Performance characteristics: Flowability 192±2mm, initial setting time 70±4min, final setting time 9.0±0.2h, density 2.08±0.01g / cm³, water bleeding rate 0.5%, 30min flowability retention value 185mm; Mechanical properties: 3d compressive strength 28.5±0.6MPa, 7d compressive strength 39.8±1MPa, 28d compressive strength 45.8±1.2MPa, bond strength 2.4±0.1MPa, elastic modulus 19.2±0.4GPa, flexural-compression ratio 0.3; Durability: Impermeability grade P14, strength loss after 50 freeze-thaw cycles 7.2±0.4%, relative dynamic modulus of elasticity 94.8%, 28-day drying shrinkage 265±12×10 -6 The chloride ion diffusion coefficient is 2.8 ± 0.2 × 10⁻⁶.-12 m² / s, carbonization depth 0.8 mm; Microstructure: Total porosity 12.5±0.5%, harmless pores (<20nm) proportion 45.2%, less harmful pores (20-50nm) proportion 36.5%, harmful pores (>50nm) proportion 18.3%, most probable pore size 25.6nm, average pore size 32.8nm.
[0027] The material used in this embodiment is a preferred embodiment of the present invention and has excellent performance in various aspects.
[0028] Example 3 This invention provides a high-bonding, impermeable coal seam extraction grouting and sealing material, which, by weight, consists of the following components: 100 parts of ordinary Portland cement; 30 parts of blast furnace slag powder, with a specific surface area of 480 m² / kg; Five parts of nano-silica, with a particle size of 18 nm and a purity of 99.8%; 12 parts of styrene-acrylic emulsion, solid content 50%, glass transition temperature -5℃; 1.2 parts of polycarboxylate superplasticizer, water reduction rate 30%; 0.5 parts of cellulose ether, viscosity 4000 mPa·s; 1.5 parts of polypropylene fiber, 12 mm in length, 18 μm in diameter, tensile strength 550 MPa; 6 parts of UEA type calcium-based expanding agent, with a magnesium oxide content of 8%; 45 parts water; Water-cement ratio: 0.4.
[0029] This embodiment also provides a preparation method. The difference between Example 3 and Example 1 is that the dry mixing time is 9 min, the liquid stirring time is 4.5 min, the mixing time is 14 min, and the slurry temperature is controlled at 22±4℃. All other aspects are the same as in Example 1.
[0030] The material obtained in Example 3 was tested, and its performance data are as follows: Performance characteristics: Flowability 188±4mm, initial setting time 68±3min, final setting time 8.8±0.4h, density 2.1±0.03g / cm³, water bleeding rate 0.6%, 30min flowability retention value 178mm; Mechanical properties: 3d compressive strength 27.2±0.9MPa, 7d compressive strength 38.5±1.1MPa, 28d compressive strength 44.2±1.3MPa, bond strength 2.3±0.2MPa, elastic modulus 18.8±0.6GPa, flexural-compression ratio 0.29; Durability: Impermeability grade P13, strength loss after 50 freeze-thaw cycles 7.8±0.6%, relative dynamic modulus of elasticity 93.6%, 28-day shrinkage 275±14×10 -6 The chloride ion diffusion coefficient is 3.0 ± 0.3 × 10⁻⁶. -12 m² / s, carbonization depth 1 mm.
[0031] Example 4 This invention provides a high-bonding, impermeable coal seam extraction grouting and sealing material, which, by weight, consists of the following components: 100 parts of ordinary Portland cement; 28 parts of blast furnace slag powder, with a specific surface area of 460 m² / kg; 4.5 parts of nano-silica, particle size 15nm, purity 99.8%; 11 parts of styrene-acrylic emulsion, solid content 50%, glass transition temperature -5℃; 1.1 parts of polycarboxylate superplasticizer, water reduction rate 30%; 0.45 parts of cellulose ether, viscosity 4000 mPa·s; One part of polypropylene fiber, 9 mm in length, 18 μm in diameter, and tensile strength of 550 MPa; 5.5 parts of UEA type calcium-based expanding agent, with a magnesium oxide content of 8%; 42 parts water; Water-cement ratio: 0.39.
[0032] This embodiment also provides a preparation method. Example 4 is basically the same as Example 1, but adopts an optimized step-by-step feeding process: Nano-silica is added in two stages: 50% is premixed with slag and 50% is added to water during liquid preparation. The polymer emulsion is added in the later stage of stirring to reduce the risk of demulsification. The fibers are dispersed using a vibration dispersion device.
[0033] The material obtained in Example 4 was tested, and its performance data are as follows: Performance characteristics: Flowability 195±2mm, initial setting time 72±2min, final setting time 9.2±0.2h, density 2.09±0.02g / cm³, water bleeding rate 0.4%, 30min flowability retention value 188mm; Mechanical properties: 3d compressive strength 29.8±0.7MPa, 7d compressive strength 41.2±0.9MPa, 28d compressive strength 47.5±1.1MPa, bond strength 2.6±0.1MPa, elastic modulus 19.5±0.3GPa, flexural-compression ratio 0.31; Durability: Impermeability grade P15, strength loss after 50 freeze-thaw cycles 6.5±0.3%, relative dynamic elastic modulus 96.2%, 28-day drying shrinkage 255±10×10 -6 The chloride ion diffusion coefficient is 2.5 ± 0.2 × 10⁻⁶. -12 m² / s, carbonization depth 0.6 mm; Microstructure: Total porosity 11.8±0.4%, harmless pores (<20nm) proportion 48.6%, less harmful pores (20-50nm) proportion 38.2%, harmful pores (>50nm) proportion 13.2%, most probable pore size 22.3nm, average pore size 28.5nm; This example demonstrates the optimal performance after process optimization.
[0034] Comparative Example 1 Comparative Example 1 was identical to Example 2 except that no nano-silica was added. The blast furnace slag powder was increased to 29 parts to maintain a consistent total powder volume. The preparation method is the same as in Example 2.
[0035] The material obtained in Comparative Example 1 was tested, and its performance data are as follows: Performance characteristics: Flowability 195±3mm, initial setting time 55±4min, final setting time 7.2±0.3h, density 2.02±0.02g / cm³, water bleeding rate 1.2%, 30min flowability retention value 180mm; Mechanical properties: 3d compressive strength 20.5±1.2MPa, 7d compressive strength 29.8±1.5MPa, 28d compressive strength 36.2±1.8MPa, bond strength 1.5±0.3MPa, elastic modulus 22.3±0.8GPa, flexural-compression ratio 0.22; Durability: Impermeability grade P8, strength loss after 50 freeze-thaw cycles 12.5±1.2%, relative dynamic modulus of elasticity 85.2%, 28-day shrinkage 320±20×10 -6 The chloride ion diffusion coefficient is 5.6±0.5×10-12m² / s, and the carbonization depth is 2.8mm; Microstructure: Total porosity 16.8±0.8%, harmless pores 32.5%, less harmful pores 39%, harmful pores 28.5%, most probable pore size 45.2nm, average pore size 52.6nm.
[0036] Comparative Example 2 Comparative Example 2 was identical to Example 2 except that no styrene-acrylic emulsion was added, and the amount of water was adjusted to 45 parts to maintain the same water-cement ratio.
[0037] The preparation method is the same as in Example 2.
[0038] The material obtained in Comparative Example 2 was tested, and its performance data are as follows: Performance characteristics: Flowability 180±5mm, initial setting time 75±5min, final setting time 9.5±0.5h, density 2.15±0.04g / cm³, water bleeding rate 2.5%, 30min flowability retention value 165mm; Mechanical properties: 3d compressive strength 18.2±1.5MPa, 7d compressive strength 26.5±1.8MPa, 28d compressive strength 32.8±2.0MPa, bond strength 1.2±0.4MPa, elastic modulus 25.6±1.2GPa, flexural-compression ratio 0.18; Durability: Impermeability grade P6, strength loss after 50 freeze-thaw cycles 15.8±1.5%, relative dynamic modulus of elasticity 78.5%, 28-day shrinkage 385±25×10 -6 The chloride ion diffusion coefficient is 8.2 ± 0.8 × 10⁻⁶. -12 m² / s, carbonization depth 3.5 mm; Microstructure: Total porosity 18.2±0.9%, harmless pores 28.8%, less harmful pores 38.6%, harmful pores 32.6%, most probable pore size 52.8nm, average pore size 58.3nm.
[0039] Comparative Example 3 Comparative Example 3 was identical to Example 2 except that no polypropylene fiber was added.
[0040] The preparation method is the same as in Example 2.
[0041] The material obtained in Comparative Example 3 was tested, and its performance data are as follows: Performance characteristics: Flowability 190±3mm, initial setting time 68±3min, final setting time 8.6±0.3h, density 2.06±0.02g / cm³, water bleeding rate 1.8%, 30min flowability retention value 175mm; Mechanical properties: 3d compressive strength 22.8±1MPa, 7d compressive strength 32.5±1.4MPa, 28d compressive strength 38.5±1.6MPa, bond strength 1.8±0.3MPa, elastic modulus 19.5±0.7GPa, flexural-compression ratio 0.2; Durability: Impermeability grade P4, strength loss after 50 freeze-thaw cycles 18.2±1.8%, relative dynamic modulus of elasticity 72.3%, 28-day shrinkage 450±30×10 -6 The chloride ion diffusion coefficient is 12.5 ± 1.2 × 10⁻⁶. -12 m² / s, carbonization depth 4.2 mm.
[0042] Comparative Example 4 Comparative Example 4 was identical to Example 2 except that no UEA expansion agent was added, with the ordinary silicate cement increased to 105 parts to maintain the total amount of cementitious materials.
[0043] The preparation method is the same as in Example 2.
[0044] The material obtained in Comparative Example 4 was tested, and its performance data are as follows: Working performance: Flowability 185±4mm, initial setting time 60±4min, final setting time 7.8±0.4h, density 2.07±0.03g / cm³, water bleeding rate 1.5%, 30min flowability retention value 170mm; Mechanical properties: 3d compressive strength 21.5±1.1MPa, 7d compressive strength 30.8±1.6MPa, 28d compressive strength 37.2±1.7MPa, bond strength 1.6±0.3MPa, elastic modulus 20.8±0.9GPa, flexural-compression ratio 0.21; Durability: Impermeability grade P7, strength loss after 50 freeze-thaw cycles 13.2±1.3%, relative dynamic elastic modulus 83.6%, 28-day drying shrinkage 355±22×10 -6 The chloride ion diffusion coefficient is 6.8 ± 0.6 × 10⁻⁶. -12 m² / s, carbonization depth 3mm.
[0045] Comparative Example 5 Comparative Example 5 uses a traditional formula: 100 parts of ordinary silicate cement, 30 parts of grade II fly ash, 1.5 parts of ordinary water-reducing agent (naphthalene-based) and 50 parts of water.
[0046] The preparation method employs a conventional stirring process.
[0047] The material obtained in Comparative Example 5 was tested, and its performance data are as follows: Performance characteristics: Flowability 165±8mm, initial setting time 45±6min, final setting time 6.5±0.6h, density 1.95±0.05g / cm³, water bleeding rate 3.8%, 30min flowability retention value 140mm; Mechanical properties: 3d compressive strength 15.2±2MPa, 7d compressive strength 21.8±2.2MPa, 28d compressive strength 28.5±2.5MPa, bond strength 0.8±0.5MPa, elastic modulus 28.0±1.5GPa, flexural-compression ratio 0.15; Durability: Impermeability grade P2, strength loss after 50 freeze-thaw cycles 25.5±2.5%, relative dynamic modulus of elasticity 62.8%, 28-day shrinkage 520±35×10 -6 The chloride ion diffusion coefficient is 25.3 ± 2.5 × 10⁻⁶. -12 m² / s, carbonization depth 6.5 mm; Microstructure: Total porosity 25.6±1.2%, harmless pores 18.5%, less harmful pores 35.7%, harmful pores 45.8%, most probable pore size 85.3 nm, average pore size 92.5 nm.
[0048] Comparative Example 6 Comparative Example 6: Purchase grouting and sealing materials for coal mines from the market and prepare and use them according to the product instructions.
[0049] The material obtained in Comparative Example 6 was tested, and its performance data are as follows: Performance characteristics: Flowability 175±5mm, initial setting time 50±5min, final setting time 7.0±0.5h, density 2.01±0.04g / cm³, water bleeding rate 2.2%, 30min flowability retention value 155mm; Mechanical properties: 3d compressive strength 17.5±1.8MPa, 7d compressive strength 25.2±2MPa, 28d compressive strength 31.2±2.3MPa, bond strength 1.0±0.4MPa, elastic modulus 26.5±1.3GPa, flexural-compression ratio 0.16; Durability: Impermeability grade P3, strength loss after 50 freeze-thaw cycles 22.8±2.2%, relative dynamic modulus of elasticity 68.5%, 28-day shrinkage 485±32×10 -6 The chloride ion diffusion coefficient is 18.5±1.8×10-12m² / s, and the carbonization depth is 5.8mm; The test methods for the above embodiments and comparative examples are as follows: 1. Slurry workability test: Flowability test: According to GB / T2419-2005 "Method for Determination of Flowability of Cement Mortar", the slurry diffusion diameter was determined by the jumping table method, and the test environment temperature was 20±2℃. Setting time test: According to GB / T1346-2011 "Test methods for standard consistency water requirement, setting time and soundness of cement", the initial setting and final setting times were determined using a Vicat apparatus. Density test: The density of fresh pulp was determined using a 1000mL volumetric cylinder, accurate to 0.01g / cm³; Bleeding rate test: according to the bleeding rate test method in JC / T985-2017 "Cement-based Self-leveling Mortar for Floors".
[0050] The overall test data is as follows: Table 1 shows the test results of the slurry workability of the examples and comparative examples. Flowability (mm) Initial setting time (min) Final setting time (h) Density (g / cm³) Water exudation rate (%) 30-minute flowability retention value (mm) Example 1 185±3 65±5 8.5±0.3 2.05±0.02 0.8 175 Example 2 192±2 70±4 9±0.2 2.08±0.01 0.5 185 Example 3 188±4 68±3 8.8±0.4 2.1±0.03 0.6 178 Example 4 195±2 72±2 9.2±0.2 2.09±0.02 0.4 188 Comparative Example 1 195±3 55±4 7.2±0.3 2.02±0.02 1.2 180 Comparative Example 2 180±5 75±5 9.5±0.5 2.15±0.04 2.5 165 Comparative Example 3 190±3 68±3 8.6±0.3 2.06±0.02 1.8 175 Comparative Example 4 185±4 60±4 7.8±0.4 2.07±0.03 1.5 170 Comparative Example 5 165±8 45±6 6.5±0.6 1.95±0.05 3.8 140 Comparative Example 6 175±5 50±5 7.0±0.5 2.01±0.04 2.2 155 2. Mechanical property testing, the specific testing methods are as follows: Prepare 40mm×40mm×160mm prism specimens according to GB / T17671-1999 "Test Method for Strength of Cement Mortar (ISO Method)" and cure under standard conditions (20±1℃, RH≥95%). Compressive strength test: A compression testing machine was used with a loading rate of 2.4 kN / s to test the strength at 3d, 7d and 28d respectively; Bond strength test: The figure-eight method was used, with one half filled with C30 concrete and the other half filled with test grout. After curing for 28 days, the failure load was tested. Elastic modulus test: The static compressive elastic modulus was determined by dial gauge method according to GB / T50081-2019 "Standard for Test Methods of Physical and Mechanical Properties of Concrete".
[0051] The overall test data is as follows: Table 2 shows the mechanical property test results for the examples and comparative examples. 3D compressive strength (MPa) 7-day compressive strength (MPa) 28-day compressive strength (MPa) Bond strength (MPa) Elastic modulus (GPa) folding ratio Example 1 25.8±0.8 36.2±1.2 42.5±1.5 2.1±0.2 18.5±0.5 0.28 Example 2 28.5±0.6 39.8±1 45.8±1.2 2.4±0.1 19.2±0.4 0.3 Example 3 27.2±0.9 38.5±1.1 44.2±1.3 2.3±0.2 18.8±0.6 0.29 Example 4 29.8±0.7 41.2±0.9 47.5±1.1 2.6±0.1 19.5±0.3 0.31 Comparative Example 1 20.5±1.2 29.8±1.5 36.2±1.8 1.5±0.3 22.3±0.8 0.22 Comparative Example 2 18.2±1.5 26.5±1.8 32.8±2 1.2±0.4 25.6±1.2 0.18 Comparative Example 3 22.8±1 32.5±1.4 38.5±1.6 1.8±0.3 19.5±0.7 0.2 Comparative Example 4 21.5±1.1 30.8±1.6 37.2±1.7 1.6±0.3 20.8±0.9 0.21 Comparative Example 5 15.2±2 21.8±2.2 28.5±2.5 0.8±0.5 28±1.5 0.15 Comparative Example 6 17.5±1.8 25.2±2 31.2±2.3 1±0.4 26.5±1.3 0.16 4. Durability test Permeability test: According to GB / T23440-2009 "Inorganic Waterproofing and Leak-stopping Materials", a concrete permeability tester was used, and the pressure was gradually increased (0.1MPa / 8h) until the specimens leaked water; Freeze-thaw resistance test: According to GB / T50082-2009 "Standard for Test Methods of Long-term Performance and Durability of Ordinary Concrete", the rapid freezing method was used for 50 cycles to test the mass loss rate and relative dynamic modulus of elasticity. Drying shrinkage test: The length change of a 100mm×100mm×515mm prism specimen was measured by contact method according to GB / T50082-2009. Chloride ion diffusion coefficient: According to the NTBUILD492 Nordic standard, the rapid chloride ion migration coefficient method (RCM method) was used.
[0052] The overall test data is as follows: Table 3 shows the durability performance test results for the examples and comparative examples. impermeability grade Strength loss after 50 freeze-thaw cycles (%) Relative dynamic modulus of elasticity (%) <![CDATA[Dry shrinkage rate (×10 -6 )]]> <![CDATA[Chloride ion diffusion coefficient (×10 -12 m² / s)]]> Carbonization depth (28d, mm) Example 1 P12 8.5±0.5 92.5 285±15 3.2±0.3 1.2 Example 2 P14 7.2±0.4 94.8 265±12 2.8±0.2 0.8 Example 3 P13 7.8±0.6 93.6 275±14 3±0.3 1 Example 4 P15 6.5±0.3 96.2 255±10 2.5±0.2 0.6 Comparative Example 1 P8 12.5±1.2 85.2 320±20 5.6±0.5 2.8 Comparative Example 2 P6 15.8±1.5 78.5 385±25 8.2±0.8 3.5 Comparative Example 3 P4 18.2±1.8 72.3 450±30 12.5±1.2 4.2 Comparative Example 4 P7 13.2±1.3 83.6 355±22 6.8±0.6 3 Comparative Example 5 P2 25.5±2.5 62.8 520±35 25.3±2.5 6.5 Comparative Example 6 P3 22.8±2.2 68.5 485±32 18.5±1.8 5.8 5. Microstructure analysis Scanning electron microscopy analysis: Field emission scanning electron microscopy was used to observe the morphology, interface structure and fiber distribution of hydration products; Mercury porosimetry: The pore structure parameters are tested using a mercury porosimetry instrument. X-ray diffraction analysis: The composition of hydration products was analyzed using an X-ray diffractometer.
[0053] The overall test data is as follows: Table 4 shows the microstructure analysis results of the examples and comparative examples. Total porosity (%) Harmless pores (<20nm) percentage (%) The proportion of pores with fewer harmful particles (20-50nm) (%) Harmful pores (>50nm) percentage (%) Most probable aperture (nm) Average pore size (nm) Example 2 12.5±0.5 45.2 36.5 18.3 25.6 32.8 Example 4 11.8±0.4 48.6 38.2 13.2 22.3 28.5 Comparative Example 1 16.8±0.8 32.5 39 28.5 45.2 52.6 Comparative Example 2 18.2±0.9 28.8 38.6 32.6 52.8 58.3 Comparative Example 5 25.6±1.2 18.5 35.7 45.8 85.3 92.5 By comparing the test data and tabular data of the above embodiments and comparative examples, the outstanding effects and synergistic effects of the present invention can be clearly seen: 1. Synergistic effect verification: Example 2 is significantly better than Comparative Example 1, Comparative Example 2, Comparative Example 3, and Comparative Example 4 in terms of bonding strength, impermeability, and crack resistance, proving that there is a synergistic effect among the components, rather than a simple additive effect. In particular, the combination of nano-silica and polymer emulsion significantly improves impermeability while improving bonding strength, thus resolving the contradiction in traditional technology. 2. Breakthrough performance improvement: The performance of all embodiments is far superior to that of Comparative Example 5 and Comparative Example 6. Compared with Comparative Example 5, the bonding strength of the embodiments is increased by 110%-160%, the impermeability grade is increased by 4-6 grades, and the 28-day compressive strength is increased by 50%-67%, achieving unexpected technical progress. 3. Microscopic mechanism confirmation: Microscopic structure data shows that the material of the present invention has lower porosity and more optimized pore size distribution, which explains the reason for its macroscopic high performance from the microscopic level. The filling effect of nano-silica and the film-forming effect of polymer emulsion work together to achieve fine control of pore structure. 4. Strong engineering applicability: While achieving high performance, the material of this invention maintains excellent construction performance and is fully compatible with existing grouting equipment. At the same time, it utilizes industrial by-product slag powder, which is both environmentally friendly and economical.
[0054] in conclusion: This invention, through specific component design and optimized preparation process, has successfully developed a coal seam extraction grouting sealing material with excellent comprehensive performance. It solves the technical problem that traditional materials cannot simultaneously achieve good adhesion, impermeability and durability, and fully meets the usage requirements of the complex and harsh environment in underground coal mines. It has important value for promotion and application.
[0055] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A high-bonding, impermeable coal seam extraction grouting and sealing material, characterized in that: It consists of the following components in parts by weight: Basic cementitious materials: 100 parts ordinary Portland cement and 20-30 parts blast furnace slag powder; Nanoscale functional filler: 3-5 parts nano-silica; Polymer modifier: 8-12 parts polymer emulsion; Chemical admixtures: 0.8-1.2 parts polycarboxylate superplasticizer and 0.3-0.5 parts cellulose ether; Physical reinforcement components: 0.8-1.5 parts polypropylene fiber and 4-6 parts calcium-based expanding agent; Mixing water: 35-45 parts water; The material has a water-cement ratio of 0.35 to 0.40, a 28-day compressive strength of not less than 40 MPa, a bond strength with coal and rock mass of not less than 2 MPa, and a permeability grade of not less than P12.
2. The high-bonding, impermeable coal seam extraction grouting and sealing material according to claim 1, characterized in that: The specific surface area of the blast furnace slag powder is not less than 400 m² / kg, and the particle size range of the nano-silica is 10-20 nm.
3. The high-bonding, impermeable coal seam extraction grouting and sealing material according to claim 2, characterized in that: The polymer emulsion is a styrene-acrylic emulsion with a solid content of 50%, and the viscosity of the cellulose ether is 4000 mPa·s.
4. The high-bonding, impermeable coal seam extraction grouting and sealing material according to claim 3, characterized in that: The polypropylene fiber has a length of 6-12 mm, and the calcium-based expansive agent is a UEA type concrete expansive agent.
5. The high-bonding, impermeable coal seam extraction grouting and sealing material according to claim 4, characterized in that: The material's slurry fluidity is not less than 180 mm, and its strength loss after 50 freeze-thaw cycles is not greater than 10%.
6. A preparation method for preparing the high-bonding, impermeable coal seam extraction grouting sealing material as described in claim 5, characterized in that: Specifically, the following steps are included: S1. Dry mixing pretreatment: Put ordinary silicate cement, blast furnace slag powder, nano silica and calcium-based expansion agent into a mixer and dry mix at a speed of 200-300 rpm for 5-10 minutes until the mixture is uniform. S2. Liquid preparation: In another container, mix the polymer emulsion, polycarboxylate superplasticizer, cellulose ether and water, and stir at medium speed for 3-5 minutes to form a homogeneous solution. S3. Mix and stir: Slowly add the liquid material prepared in S2 to the dry mixture in S1, and stir at a speed of 200-300 rpm for 10-15 minutes to form a uniform and lump-free slurry. S4. Fiber dispersion: Add polypropylene fiber to the slurry obtained in S3 and continue stirring for 5 minutes to ensure that the fiber is evenly dispersed in the slurry. S5. Quality Inspection and Application: The fluidity, setting time, and density of the obtained slurry are tested. Once qualified, it is immediately used for grouting and sealing of coal seam boreholes.
7. The preparation method according to claim 6, characterized in that: In the dry mixing pretreatment in step S1, the nano-silica is added in steps, first premixed with blast furnace slag powder for 30 seconds, and then other dry powder components are added.
8. The preparation method according to claim 7, characterized in that: During the mixing process in step S3, the temperature of the slurry is controlled between 5-30℃.
9. The preparation method according to claim 8, characterized in that: In the quality inspection of step S5, the initial setting time of the slurry shall not be earlier than 45 min, the final setting time shall not be later than 10 h, and the density range shall be 1.8-2.2 g / cm³.
10. The preparation method according to claim 9, characterized in that: In step S5, the grout is injected into the coal seam extraction borehole by a pressure grouting pump at a pressure of 0.5-1.0 MPa.