Coal mine roof fissure repairing grouting material, preparation method and application thereof

Abstract

The present application provides a kind of coal mine roof fissure repair grouting material, comprising the following raw material components: fly ash 100 parts, bentonite 3-8 parts, flexible component 10-16 parts, self-expanding component 3-8 parts and water 50-70 parts. Among them, the flexible component includes the following raw material components by weight fraction: acrylamide monomer 10-20 parts, N,N-methylene bisacrylamide 0.1-1 part, and persulfate 0.1-0.5 part;The persulfate is selected from one of ammonium persulfate or potassium persulfate;The self-expanding component includes the following raw material components by weight fraction: sodium bicarbonate 10-20 parts, aluminum sulfate 8-12 parts and HPMC 0.1-0.3 parts. The present application utilizes the morphological effect of fly ash spherical particles, the particle dispersion effect of bentonite and the micro-foaming effect of self-expanding material, under the joint action of the three, the flexible component is dispersed more uniformly, and then ensures that in the case of using low dosage of flexible component, three-dimensional network structure can also be formed in the material system, and the prepared grouting material has more excellent performance.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of grouting and water disaster control, and relates to a grouting material, in particular to a coal mine roof crack repair grouting material, a preparation method and application. BACKGROUND

[0002] A certain amount of primary cracks naturally exist in rock mass, and under the disturbance of coal mining, the primary cracks will further develop and expand, and when the cracks in the rock mass develop to the overburden aquifer or surface phreatic water, a seepage channel will be formed. In the engineering practice of coal mining, it is found that the overburden damage caused by coal mining will produce a certain degree of self-repairing effect, and the rock mass damaged by mining disturbance is compacted and cemented into rock again under the long-term gravity settlement of the overburden, and the broken cracks are healed, so that the development range and opening degree of the overburden water-conducting cracks are reduced, and the underground water level rises. However, the self-repairing effect of the damaged overburden caused by mining will not be obvious until several years or even decades. If the self-repairing characteristics of the mining rock mass can be fully utilized and corresponding measures are taken to guide or accelerate the self-repairing process, it will provide a convenient way to realize the sealing of the water-conducting channel of the mining rock mass and the repair of the aquifer. At present, the bottleneck of the ecological function repair of the mining overburden aquifer is that it is difficult to find a sealing material suitable for the development conditions of the water-conducting channel of the mining roof and a method for artificially inducing the repair of the overburden water-conducting cracks, and improvement is urgently needed. SUMMARY

[0003] In view of the deficiencies in the prior art, the purpose of the present application is to provide a coal mine roof crack repair grouting material, a preparation method and application. The repair grouting material takes solid waste as the main raw material, has flexibility, water absorption and expansion, and self-expansion capacity, and is suitable for the grouting repair of coal mine roof and floor cracks, thereby solving the technical problem of the lack of a sealing material suitable for the development conditions of the water-conducting channel of the mining roof in the prior art.

[0004] In order to solve the above technical problems, the present application adopts the following technical solutions:

[0005] A coal mine roof crack repair grouting material, in terms of weight parts, comprises the following raw material components: fly ash 100 parts, bentonite 3-8 parts, flexible component 10-16 parts, self-expanding component 3-8 parts and water 50-70 parts.

[0006] The present application also has the following technical features:

[0007] Specifically, the flexible component comprises the following raw material components in terms of weight parts: acrylamide monomer 10-20 parts, N,N-methylene bisacrylamide 0.1-1.0 parts, and persulfate 0.1-0.5 parts.

[0008] Further, the persulfate salt is selected from one of ammonium persulfate or potassium persulfate.

[0009] Further, the self-expanding component includes the following raw material components in parts by weight: sodium bicarbonate 10-20 parts, aluminum sulfate 8-12 parts, and HPMC 0.1-0.3 parts.

[0010] Further, the fly ash has a particle size of less than 200 mesh.

[0011] The application also protects a preparation method of the coal mine roof fracture repair grouting material, including the following steps:

[0012] Step 1, mix and stir the formula amount of fly ash and bentonite at a speed of 100-200 r / min for 1-2 min to obtain a mixed material A; mix the mixed material A with the formula amount of water, and mix and stir at a speed of 100-200 r / min for 1-2 min to obtain a slurry A;

[0013] Step 2, add the formula amount of the flexible component to the slurry A, and mix and stir at a speed of 100-200 r / min for 1-3 min to obtain a slurry B;

[0014] Step 3, add the formula amount of the self-expanding component to the slurry B, and mix and stir at a speed of 100-300 r / min for 1-3 min to obtain the coal mine roof fracture repair grouting material;

[0015] Wherein, the fly ash is 100 parts, the bentonite is 3-8 parts, the flexible component is 10-16 parts, the self-expanding component is 3-8 parts, and the water is 50-70 parts by weight.

[0016] Further, the flexible component includes the following raw material components in parts by weight: acrylamide monomer 10-20 parts, N,N-methylene bisacrylamide 0.1-1.0 parts, and persulfate salt 0.1-0.5 parts; the persulfate salt is selected from one of ammonium persulfate or potassium persulfate.

[0017] Further, specifically includes the following steps:

[0018] Step 1, mix and stir the fly ash with a particle size of less than 200 mesh and the bentonite with a particle size of less than 200 mesh at a speed of 50 r / min for 3 min to obtain a mixed material A; mix the mixed material A with water, and mix and stir at a speed of 100 r / min for 2 min to obtain a slurry A;

[0019] Step 2, add the formula amount of the flexible component to the slurry A, and mix and stir at a speed of 200 r / min for 2 min to obtain a slurry B;

[0020] Step 3: Add the self-expanding component of the formula to slurry B, and mix and stir at a rate of 200 r / min for 2 min to obtain the final product;

[0021] The composition, by weight, consists of 100 parts fly ash, 5 parts bentonite, 15 parts flexible components, 6.4 parts self-expanding components, and 56 parts water.

[0022] Furthermore, the flexible component, by weight, comprises the following raw material components: 14 parts acrylamide monomer, 0.68 parts N,N-methylenebisacrylamide, and 0.34 parts ammonium persulfate.

[0023] This invention also protects the application of the above-mentioned coal mine roof crack repair grouting material for coal mine roof management; or the application of the coal mine roof crack repair grouting material prepared by the above-mentioned method for coal mine roof management.

[0024] Compared with the prior art, the present invention has the following technical effects:

[0025] (I) This invention uses fly ash as the basic material, bentonite as the dispersion and adjustment material, and self-expanding component as the expansion adjustment material, and adds a flexible component with adjustment function to prepare a grouting material that can be used for the repair of cracks in the roof of coal mines. This invention utilizes the morphological effect of spherical particles of fly ash, the particle dispersion effect of bentonite, and the micro-foaming effect of self-expanding material. Under the combined effect of the three, the flexible component is more uniformly dispersed, thereby ensuring that a three-dimensional network structure can be formed in the material system even when using a low amount of flexible component. The grouting material has excellent performance and can guarantee the repair effect of roof cracks.

[0026] (II) The coal mine roof crack repair grouting material provided by the present invention has excellent flexibility and water absorption expansion properties, has the same fluidity as commonly used grouting materials, can solidify in a short time, and the micro foaming components form a secondary expansion after grouting, which effectively ensures the grouting effect.

[0027] (III) The preparation method of the coal mine roof crack repair grouting material of the present invention is simple and highly operable. The proportion of each group can be adjusted according to the needs of the site to match different grouting processes. Attached Figure Description

[0028] Figure 1 This is a 50μm microstructure diagram of the grouting material for repairing cracks in the coal mine roof in Example 1;

[0029] Figure 2 This is a 10μm microstructure diagram of the grouting material for repairing cracks in the coal mine roof in Example 1;

[0030] Figure 3This is a 2μm microstructure diagram of the grouting material for repairing cracks in the coal mine roof in Example 1;

[0031] Figure 4 The image shows the microstructure of the grouting material used for repairing cracks in the coal mine roof in Comparative Example 1.

[0032] Figure 5 The image shows the microstructure of the grouting material used for repairing cracks in the coal mine roof in Comparative Example 2.

[0033] Figure 6 The image shows the microstructure of the grouting material used for repairing cracks in the coal mine roof in Comparative Example 3.

[0034] The specific content of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Detailed Implementation

[0035] The technical solutions 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. Based on the embodiments of the present invention, any other embodiments obtained by those skilled in the art are within the scope of protection of the present invention.

[0036] It should be noted that, unless otherwise specified, all raw materials used in this invention are those known in the art.

[0037] The technical concept of this application is as follows: Grouting of cracks in coal mine roof requires grouting materials with high injectability, flexibility, and water-absorbing and swelling properties. High injectability ensures the filling and sealing of minute cracks, flexibility resists stress disturbances generated during coal mining, and water-absorbing and swelling properties further ensure the sealing effect of water-conducting channels. Due to its spherical particle morphology, fly ash reduces the friction between grout particles and cracks during grouting, thus effectively sealing minute water-conducting cracks. The presence of flexible components endows the grouting material with excellent flexibility and water-absorbing and swelling properties. The presence of bentonite ensures more uniform dispersion of the system components, thereby ensuring contact and reaction of the admixture components. The presence of self-expanding components strongly guarantees the grouting effect and material performance. The self-expanding components begin to react after the grout is injected into the water-conducting cracks, and the generated bubbles form a secondary agitation of the grout, making the grout mixture more uniform. When encountering minute cracks that are difficult to inject with conventional materials, the bubbles generated by the reaction of the self-expanding components will push the grout particles, thereby prompting the grout particles to enter the minute cracks and achieve efficient sealing. The self-expanding component includes aluminum sulfate and sodium bicarbonate, which react upon contact: Al2(SO4)3 + NaHCO3 → Al(OH)3↓ + CO2↑ + Na2SO4. The generated CO2 gas forms bubbles, and the foaming process is equivalent to secondary stirring, ensuring sufficient contact between the components in the system. This ensures that the flexible component can more easily contact and react even at low dosages. Furthermore, CO2 dissolves in water and undergoes a mineralization reaction with the alkaline components in fly ash, improving the pH value of the slurry and providing favorable conditions for the polymerization reaction of the flexible component. The acrylamide monomer in the flexible component undergoes a polymerization reaction under the action of ammonium persulfate or potassium persulfate to generate a two-dimensional polyacrylamide gel. Then, under the action of N,N-methylenebisacrylamide, a cross-linking reaction occurs to generate a three-dimensional polyacrylamide gel. However, this material is expensive, and in existing grouting material systems, the dosage of the flexible component, by mass percentage, is often greater than 20%, making it difficult to effectively generate a three-dimensional polyacrylamide gel at low dosages. This invention utilizes the spherical effect of fly ash particles, the dispersion effect of bentonite, and the foaming effect of self-expanding components to make the components in the grout system more uniformly mixed and dispersed. This allows the flexible components to react efficiently and generate a three-dimensional polyacrylamide gel even at low dosages, thereby giving the grouting material excellent performance and ensuring the repair effect of roof cracks.

[0038] In this application, the materials used are as follows:

[0039] Fly ash is a solid waste product from coal mining. After crushing, grinding, and screening, the particle size of the ground coal gangue powder is less than 200 mesh.

[0040] Following the above technical solution, this invention discloses a grouting material for repairing cracks in the roof of a coal mine, comprising the following raw material components by weight: 100 parts fly ash, 3-8 parts bentonite, 10-16 parts flexible component, 3-8 parts self-expanding component, and 50-70 parts water.

[0041] Preferably, the flexible component comprises, by weight, the following raw material components: 10-20 parts of acrylamide monomer, 0.1-1.0 parts of N,N-methylenebisacrylamide, and 0.1-0.5 parts of persulfate.

[0042] Preferably, the persulfate is selected from either ammonium persulfate or potassium persulfate.

[0043] Preferably, the self-expanding component comprises, by weight, the following raw material components: 10-20 parts sodium bicarbonate, 8-12 parts aluminum sulfate, and 0.1-0.3 parts HPMC.

[0044] Preferably, the fly ash particle size is less than 200 mesh.

[0045] This invention also discloses a method for preparing a grouting material for repairing cracks in coal mine roofs, the method comprising the following steps:

[0046] Step 1: Mix the prescribed amount of fly ash and bentonite at a speed of 100-200 r / min for 1-2 min to obtain mixture A; mix mixture A with the prescribed amount of water at a speed of 100-200 r / min for 1-2 min to obtain slurry A.

[0047] Step 2: Add the amount of the flexible component in the formula to slurry A, and mix and stir at a rate of 100-200 r / min for 1-3 min to obtain slurry B;

[0048] Step 3: Add the self-expanding component of the formula to slurry B, and mix and stir at a rate of 100-300 r / min for 1-3 min to obtain the final product;

[0049] The composition, by weight, consists of 100 parts fly ash, 3-8 parts bentonite, 10-16 parts flexible components, 3-8 parts self-expanding components, and 50-70 parts water.

[0050] Preferably, the flexible component comprises, by weight, the following raw material components: 10-20 parts of acrylamide monomer, 0.1-1.0 parts of N,N-methylenebisacrylamide, and 0.1-0.5 parts of persulfate; wherein the persulfate is selected from either ammonium persulfate or potassium persulfate.

[0051] This invention also protects the application of the above-mentioned coal mine roof crack repair grouting material for coal mine roof management; or the application of the coal mine roof crack repair grouting material prepared by the above-mentioned method for coal mine roof management.

[0052] The following are specific embodiments of the present invention. It should be noted that the present invention is not limited to the following specific embodiments. All equivalent modifications made based on the technical solutions of this application fall within the protection scope of the present invention.

[0053] In this invention, the flowability test is conducted in accordance with GB / T 8077-2023 "Test Method for Homogeneity of Concrete Admixtures". The expansion ratio is determined by the ratio of "volume after expansion / volume before expansion". The water absorption expansion rate is determined by the ratio of "volume after water absorption expansion / volume before water absorption expansion". The compressive deformation rate is determined by the "force-displacement" curve obtained during the ballast process of a universal testing press. The 3d compressive strength is obtained by testing with a universal testing press.

[0054] Example 1

[0055] This embodiment provides a method for preparing a grouting material for repairing cracks in the roof of a coal mine, specifically including the following steps:

[0056] Step 1: Mix fly ash with a particle size of less than 200 mesh and bentonite with a particle size of less than 200 mesh at a speed of 50 r / min for 3 min to obtain mixture A; mix mixture A with water and mix at a speed of 100 r / min for 2 min to obtain slurry A;

[0057] Step 2: Add the amount of the flexible component in the formula to slurry A, and mix and stir at a rate of 200 r / min for 2 min to obtain slurry B;

[0058] Step 3: Add the self-expanding component of the formula to slurry B, and mix and stir at a rate of 200 r / min for 2 min to obtain the final product;

[0059] The composition, by weight, consists of 100 parts fly ash, 5 parts bentonite, 15 parts flexible components, 6.4 parts self-expanding components, and 56 parts water.

[0060] The flexible component, by weight, includes the following raw material components: 14 parts acrylamide monomer, 0.68 parts N,N-methylenebisacrylamide, and 0.34 parts ammonium persulfate.

[0061] The self-expanding component, by weight, includes the following raw material components: 15 parts sodium bicarbonate, 10.5 parts aluminum sulfate, and 0.15 parts HPMC.

[0062] The microstructure of the coal mine roof crack repair grouting material prepared in this embodiment at different microscales is as follows: Figures 1-3 As shown.

[0063] The performance of the grouting material for repairing cracks in the coal mine roof prepared in this embodiment was tested, and the results are shown in Table 1.

[0064] The grouting material for repairing cracks in the coal mine roof prepared in this embodiment can be used for repairing cracks in the coal mine roof, and can also be used for other working conditions as needed, such as grouting of the coal mine floor and grouting for roadway reinforcement.

[0065] Example 2

[0066] This embodiment provides a method for preparing a grouting material for repairing cracks in the roof of a coal mine. The raw material components and preparation steps are the same as in Example 1. The difference is that the amount of some raw material components is different in this embodiment. Specifically, in this embodiment, the flexible component is 10 parts and the self-expanding component is 8 parts.

[0067] The performance of the grouting material for repairing cracks in the coal mine roof prepared in this embodiment was tested, and the results are shown in Table 1.

[0068] Example 3

[0069] This embodiment provides a method for preparing a grouting material for repairing cracks in the roof of a coal mine. The raw material components and preparation steps are the same as in Embodiment 1. The difference is that the amount of some raw material components is different in this embodiment. Specifically, in this embodiment, the flexible component is 13 parts and the self-expanding component is 6.4 parts.

[0070] The performance of the grouting material for repairing cracks in the coal mine roof prepared in this embodiment was tested, and the results are shown in Table 1.

[0071] Example 4

[0072] This embodiment provides a method for preparing a grouting material for repairing cracks in the roof of a coal mine. The raw material components and preparation steps are the same as in Example 1. The difference is that the amount of some raw material components is different in this embodiment. Specifically, in this embodiment, bentonite is used in 3 parts.

[0073] The performance of the grouting material for repairing cracks in the coal mine roof prepared in this embodiment was tested, and the results are shown in Table 1.

[0074] Comparative Example 1

[0075] This embodiment provides a method for preparing a grouting material for repairing cracks in the roof of a coal mine. The raw material components and preparation steps are basically the same as in Example 1. The difference is that coal gangue powder is used instead of fly ash in this comparative example.

[0076] The microstructures of the coal mine roof crack repair grouting material prepared in this comparative example at different microscales are as follows: Figure 4 As shown.

[0077] The performance of the grouting material for repairing cracks in the coal mine roof prepared in this comparative example was tested, and the results are shown in Table 1.

[0078] Comparative Example 2

[0079] This embodiment provides a method for preparing a grouting material for repairing cracks in the roof of a coal mine. The raw material components and preparation steps are basically the same as those in Example 1. The difference is that bentonite was not added in this comparative example.

[0080] The microstructures of the coal mine roof crack repair grouting material prepared in this comparative example at different microscales are as follows: Figure 4 As shown.

[0081] The performance of the grouting material for repairing cracks in the coal mine roof prepared in this comparative example was tested, and the results are shown in Table 1.

[0082] Comparative Example 3

[0083] This comparative example provides a method for preparing a grouting material for repairing cracks in the roof of a coal mine. The raw material components and preparation steps are basically the same as those in Example 1. The difference is that no self-expanding component is added in this comparative example.

[0084] The microstructures of the coal mine roof crack repair grouting material prepared in this comparative example at different microscales are as follows: Figure 4 As shown.

[0085] The performance of the grouting material for repairing cracks in the coal mine roof prepared in this comparative example was tested, and the results are shown in Table 1.

[0086]

[0087] Table 1. Test results of grouting materials in Examples 1-4 and Comparative Examples 1-3

[0088] As can be seen from Table 1, the expansion ratio, water absorption expansion rate, compressive deformation rate and 3d compressive strength of the grouting materials for repairing cracks in coal mine roofs prepared in Examples 1 to 4 are all better than those in Comparative Examples 1 to 3. Among them, Comparative Example 1 replaced fly ash with coal gangue powder of the same particle size compared with the examples, Comparative Example 2 lacked bentonite component, and Comparative Example 3 lacked self-expanding component.

[0089] The comparison between Example 1 and Comparative Example 1 shows that, with other components being equal, the spherical effect of fly ash particles can improve the fluidity of the grouting material, resulting in a grouting material with superior performance.

[0090] As can be seen from Examples 1, 2, and 3, the dispersion effect of bentonite can improve the uniform dispersion of each component in the grouting material, and the micro-foaming effect of the self-expanding component improves the mixing degree of the grout, ensuring that the flexible component is more uniformly dispersed in the system, generating more three-dimensional polyacrylamide gels, thereby making the performance of the prepared grout material better.

[0091] Depend on Figure 1 and Figure 4 , Figure 5 The comparison shows that the grouting material prepared in Example 1 has a denser and more uniform pore structure, while the grouting materials prepared in Comparative Examples 1 and 2 have a looser pore structure and a larger pore size. This indicates that the foaming effect of Example 1 is significantly better than that of Comparative Examples 1 and 2. This is because the presence of fly ash increases the fluidity of each component in the system, and the presence of bentonite promotes more uniform dispersion of each component. It is the synergistic effect of fly ash and bentonite that makes the self-expanding components in the system more evenly dispersed, resulting in more uniform and dense foaming. Furthermore, the excellent foaming effect of the system further agitates the flexible components within the system, making it easier to generate three-dimensional polyacrylamide gels (such as...). Figure 2 and Figure 3 (As shown).

[0092] Depend on Figure 1 and Figure 6 As can be seen from the comparison, compared with Example 1, Comparative Example 3, due to the lack of self-expanding components, although fly ash and bentonite were also used in the system, still had difficulty in effectively forming a three-dimensional polyacrylamide gel because the secondary stirring of the system during the reaction and foaming of the self-expanding components was not carried out.

[0093] In summary, it is precisely the synergistic effect of fly ash, bentonite, and the self-expanding component that promotes a more complete reaction of the flexible component in the system, forming a three-dimensional polyacrylamide gel. This ultimately ensures that the prepared grouting material possesses excellent flexibility (compressive deformation rate), water absorption and swelling (water absorption and swelling rate), and self-expansion (swelling ratio). The coordinated combination of components not only guarantees the new properties of the material but also significantly reduces the preparation cost of the grouting material, meeting the requirements for grouting materials used in coal mine roof crack repair.

[0094] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0095] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A coal mine roof fracture repair grouting material, characterized in that, The coal mine roof fissure repairing grouting material comprises, in parts by weight, fly ash 100 parts, bentonite 3-8 parts, a flexible component 10-16 parts, a self-expanding component 3-8 parts, and water 50-70 parts. The flexible component comprises, in parts by weight, acrylamide monomer 10-20 parts, N,N-methylene bisacrylamide 0.1-1.0 parts, and persulfate 0.1-0.5 parts. The self-expanding component comprises, in parts by weight, sodium bicarbonate 10-20 parts, aluminum sulfate 8-12 parts, and HPMC 0.1-0.3 parts.

2. The coal mine roof fracture repair grout material of claim 1, wherein, The persulfate is selected from one of ammonium persulfate or potassium persulfate.

3. The coal mine roof fracture repair grout material of claim 1, wherein, The fly ash has a particle size less than 200 mesh.

4. A method of preparing a coal mine roof fracture repair grouting material according to any one of claims 1 to 3, characterized in that, The method comprises the following steps: Step 1, mixing and stirring the formula amount of fly ash and bentonite at a speed of 100-200 r / min for 1-2 min to obtain a mixed material A; mixing the mixed material A with the formula amount of water at a speed of 100-200 r / min for 1-2 min to obtain a slurry A; Step 2, adding the formula amount of the flexible component to the slurry A and mixing and stirring at a speed of 100-200 r / min for 1-3 min to obtain a slurry B; Step 3, adding the formula amount of the self-expanding component to the slurry B and mixing and stirring at a speed of 100-300 r / min for 1-3 min to obtain the coal mine roof fissure repairing grouting material.

5. The preparation method of the coal mine roof crack repair grouting material as described in claim 4, characterized in that, The flexible component comprises, in parts by weight, acrylamide monomer 14 parts, N,N-methylene bisacrylamide 0.68 parts, and ammonium persulfate 0.34 parts.

6. Use of the coal mine roof fissure repairing grouting material according to any one of claims 1 to 3 for coal mine roof control; or use of the coal mine roof fissure repairing grouting material prepared by the method according to any one of claims 4 or 5 for coal mine roof control.

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