A kind of mine shotcrete based on coal gangue and its preparation method

Abstract

The present application relates to the technical field of shotcrete, and specifically provides a mine-used shotcrete based on coal gangue and a preparation method thereof. Wherein, the shotcrete includes component A and component B in a weight ratio of 100: (3-9); wherein component A includes the following components in parts by weight: 100-140 parts of cement, 135-150 parts of coal gangue, 50-70 parts of water, 15-20 parts of admixture, 1-5 parts of calcium formate, 4-5 parts of water reducer, and 1-2 parts of air entraining agent; component B includes the following components in parts by weight: 4-10 parts of polyaluminium sulfate, 1-9 parts of triisopropanolamine, 1-4 parts of aluminium sulfate 18hydrate, 1-4 parts of ethylene glycol, 2-5 parts of nano-aluminium hydroxide, and 3-5 parts of triisopropanolamine octanoate. The shotcrete provided in the present application still has better mechanical properties while using coal gangue as aggregate.

Description

Technical Field

[0001] The present invention relates to the technical field of concrete materials, and in particular to a gangue-based mine shotcrete and a preparation method thereof. Background Art

[0002] Shotcrete for mining is a special concrete material used in mining projects. It primarily uses a mixture of raw materials, such as cement, mineral admixtures, additives, and an appropriate amount of aggregate, after being properly proportioned. Using a spraying technique, the concrete is sprayed onto mine tunnels, ramps, and mine support structures, forming a hard, smooth protective layer with high wear resistance and durability. Shotcrete for mining exhibits excellent compression, bending, impact, and wear resistance, effectively improving the load-bearing capacity and service life of tunnels and ramps, and preventing geological disasters such as rockfall and landslides. Furthermore, shotcrete for mining offers special features such as fire resistance, explosion resistance, waterproofing, and sound insulation, enhancing the safety and environmental protection capabilities of mining projects. Shotcrete for mining has widespread and important applications in mining projects and is a specialty concrete material with excellent performance and special functions.

[0003] Gangue refers to coal-containing waste or byproducts generated during coal mining and processing. It primarily consists of the non-economic components of coal formations, including charcoal, carbonaceous roof, rock debris, mudstone, and quartz. Gangue has a significant impact on the environment because it often occurs in large quantities and contains a certain proportion of sulfur, ash, and other substances. When stored or dumped, gangue can waste land resources and contaminate surrounding soil and water sources. Furthermore, when gangue comes into contact with oxygen and water, it can form acidic solutions, leading to acid mine drainage (AMD), which negatively impacts aquatic environments and ecosystems. To mitigate the environmental impact of gangue, various treatment measures are often implemented. For example, gangue can be used for backfill, land reclamation, or solid waste landfills; advanced gangue preparation technologies can be used to recover coal from gangue; and gangue can be processed and treated through physical and chemical methods to improve its environmental friendliness. These measures aim to minimize the harm of coal gangue to the environment and achieve efficient use of resources.

[0004] In recent years, researchers have begun researching the use of coal gangue as a coarse aggregate in the production of gangue shotcrete, aiming to utilize solid waste and reduce shotcrete production costs. However, as a weak aggregate, gangue in shotcrete typically significantly weakens the concrete's strength when added to it. Therefore, finding a way to incorporate gangue as a weak aggregate into concrete without compromising its mechanical properties has become a pressing challenge for those skilled in the art. Summary of the Invention

[0005] In order to solve the above problems, the embodiments of the present application provide a coal gangue-based mine shotcrete and a preparation method thereof. The shotcrete provided in the embodiments of the present application uses coal gangue as aggregate while still having excellent mechanical properties.

[0006] To this end, the following technical solutions are adopted in the embodiments of the present application:

[0007] In the first aspect, the present application provides a coal gangue-based shotcrete for mining, the shotcrete comprising component A and component B in a weight ratio of 100:(3-9); wherein component A comprises the following components in parts by weight: 100-140 parts of cement, 135-150 parts of coal gangue, 50-70 parts of water, 15-20 parts of admixture, 1-5 parts of calcium formate, 4-5 parts of water reducer, and 1-2 parts of air entraining agent; component B comprises the following components in parts by weight: 4-10 parts of polyaluminum sulfate, 1-9 parts of triisopropanolamine, 1-4 parts of aluminum sulfate 18hydrate, 1-4 parts of ethylene glycol, 2-5 parts of nano-aluminum hydroxide, and 3-5 parts of triisopropanolamine octanoate.

[0008] In this embodiment, the mineral components in the gangue are mainly composed of kaolin, quartz, montmorillonite, feldspar, illite, limestone, iron sulfide, and aluminum oxide; the compounds in the gangue are mainly composed of oxides such as SiO2, Al2O3, K2O, Fe2O3, CaO, MgO, SO3, and P2O5. The content of SiO2 in the gangue is between 40% and 70%, and the content of Al2O3 is between 15% and 30%. In the embodiment of the present application, gangue is used as aggregate to achieve effective utilization of solid waste and reduce the production cost of shotcrete. Among them, the cement, admixtures, and additives in component A can provide the bonding and workability of concrete, allowing the gangue to be fully combined with other materials; specifically, the added calcium formate can improve the early strength of shotcrete, and the water reducer and air entraining agent can adjust the fluidity and density of concrete, thereby improving the workability and mechanical properties of shotcrete. The polyaluminium sulfate, triisopropanolamine and nano-aluminium hydroxide in component B enhance the mechanical and impermeability properties of concrete, improving the durability and stability of gangue shotcrete. Components A and B react rapidly after mixing during shotcrete construction, forming a hard protective layer that improves the mechanical and impermeability properties of the shotcrete.

[0009] As a feasible embodiment, the sprayed concrete includes component A and component B in a weight ratio of 100:(3-9); wherein component A includes the following components in parts by weight: 100 parts of cement, 135-140 parts of coal gangue, 50-60 parts of water, 2-4 parts of calcium formate, 4-5 parts of water reducer, and 1-2 parts of air entraining agent; component B includes the following components in parts by weight: 6-8 parts of polyaluminum sulfate, 4-6 parts of triisopropanolamine, 1-3 parts of aluminum sulfate 18hydrate, 2-3 parts of ethylene glycol, 3-4 parts of nano-aluminum hydroxide, and 3-4 parts of triisopropanolamine octanoate.

[0010] As a feasible embodiment, the sprayed concrete includes component A and component B in a weight ratio of 100:(3-9); wherein component A includes the following components in parts by weight: 100 parts of cement, 135 parts of coal gangue, 55 parts of water, 3 parts of calcium formate, 4 parts of water reducer, and 1 part of air entraining agent; component B includes the following components in parts by weight: 6 parts of polyaluminum sulfate, 6 parts of triisopropanolamine, 1 part of aluminum sulfate 18hydrate, 2 parts of ethylene glycol, 4 parts of nano-aluminum hydroxide, and 4 parts of triisopropanolamine octanoate.

[0011] In this embodiment, the applicant has found through research that the use of shotcrete with the above-mentioned proportion can give full play to the advantages of each component, so that the shotcrete has better mechanical properties while using coal gangue as aggregate.

[0012] As a feasible embodiment, the B component is prepared by the following steps: polyaluminum sulfate is heated and dissolved in water at a temperature of 55-65°C, and then triisopropanolamine and ethylene glycol are added at the same temperature and stirred for 30 minutes, followed by adding aluminum sulfate 18hydrate and stirring for 30 minutes, and then adding nano aluminum hydroxide and stirring for 30 minutes, and adding triisopropanolamine octanoate dropwise while stirring to obtain component B.

[0013] In this embodiment, the preparation method is simple and easy, easy to operate, and the quality of the B component prepared is stable and reliable, which can meet actual production needs. Wherein, polyaluminium sulfate and aluminium sulfate 18hydrate, as the main accelerating coagulant components, can make sprayed concrete produce a quick-setting effect. Triisopropanolamine can improve the early strength performance and the accelerating coagulant effect of sprayed concrete, and also plays the role of complexing aluminium ions to form a stable complex, and cooperates with triisopropanolamine octanoate to make the B component more stable. Ethylene glycol can improve the late strength of sprayed concrete. And nano-aluminium hydroxide can enhance the shrinkage and impermeability of concrete, improve the durability and stability of sprayed concrete. Triisopropanolamine octanoate, as an accelerating coagulant, can react rapidly after concrete spraying construction, and forms a hard protective layer, improves the early strength and durability of concrete, and simultaneously, triisopropanolamine octanoate can also play the role of a stabilizer, improves the stability of the B component.

[0014] As a feasible implementation method, the coal gangue is divided into coal gangue aggregates with different particle size ranges of 0-2.5mm, 2.5-5mm, 5-10mm, and 10-15mm, and the weight percentages of coal gangue aggregates in each particle size range are 0-2.5mm: 28.1-57.4%, 2.5-5mm: 13.8-17.6%, 5-10mm: 15.1-28.5%, and 10-15mm: 13.7-25.8%.

[0015] In this embodiment, the embodiment of the present application uses coal gangue to completely replace the coarse and fine aggregates in shotcrete. It has been verified that under the above-mentioned gradation, the large particles form a skeleton by being embedded in each other, and a sufficient number of fine aggregates fill the gaps between the skeletons, thereby forming a continuous gradation. This structure has a high internal friction angle and high cohesion in the shotcrete after adding the cementitious material. Therefore, the above-mentioned reasonable continuous gradation has a better density, a better packing density, reduces the gaps between particles, enhances the meshing effect between particles, can give full play to the bonding effect of cement and the skeleton effect of aggregate, and is more obvious for the increase in concrete strength. At the same time, suitable gradation can improve the pumpability of shotcrete and reduce the rebound rate.

[0016] As a feasible implementation method, the admixture includes silica fume, nano silicon dioxide and nano aluminum silicate in a weight ratio of 3-5:2-4:1-2.

[0017] In this embodiment, by compounding silica fume, nano-silica and nano-aluminum silicate as admixtures, the reduction in the strength of shotcrete caused by coal gangue can be effectively suppressed, and the early strength and late strength of shotcrete can be effectively guaranteed.

[0018] As a feasible embodiment, the air entraining agent includes any one of sodium alkyl sulfonate, sodium alkyl sulfate, sodium alkylbenzene sulfonate, and fatty alcohol polyoxyethylene ether.

[0019] In this embodiment, the air entraining agent is an admixture that can introduce a large number of small, uniform bubbles during the concrete mixing process. By introducing bubbles of appropriate size and amount, the workability of the concrete mixture can be significantly improved and the slump loss can be reduced, thereby improving the strength of the concrete and its durability such as anti-freeze, anti-permeability, and anti-carbonation.

[0020] As a feasible implementation method, the cement is P.O42.5 ordinary Portland cement.

[0021] In this embodiment, P.O42.5 ordinary Portland cement is used as the main cementitious material of shotcrete, which can ensure the mechanical properties, durability and construction quality of concrete, and also has high economic benefits and practical value.

[0022] As a feasible implementation, the water reducer is a polycarboxylic acid high performance water reducer.

[0023] In this embodiment, since the aggregate in this application is coal gangue, which requires a large amount of water, a polycarboxylic acid high-performance water reducer is added to reduce the water content in the concrete while maintaining the fluidity and pumpability of the concrete, thereby improving the construction performance, strength and durability of the concrete.

[0024] In a second aspect, the present application provides a method for preparing shotcrete for mining based on coal gangue, comprising the following steps:

[0025] (1) According to the required ratio of raw materials, 100-140 parts of cement, 135-150 parts of coal gangue, 50-70 parts of water, 15-20 parts of admixture, 1-5 parts of calcium formate, 4-5 parts of water reducer, and 1-2 parts of air entraining agent are mixed uniformly to obtain component A;

[0026] (2) 4-10 parts of polyaluminum sulfate are heated and dissolved in 10-20 parts of water at a temperature of 55-65° C., and then 1-9 parts of triisopropanolamine and 1-4 parts of ethylene glycol are added at the same temperature and stirred for 30 minutes. Then, 1-4 parts of aluminum sulfate 18hydrate are added and stirred for 30 minutes, and then 2-5 parts of nano-aluminum hydroxide are added and stirred for 30 minutes. 3-5 parts of triisopropanolamine octanoate are added dropwise while stirring to obtain component B;

[0027] (3) Mix component A and component B evenly in a weight ratio of 100:(3-9).

[0028] In summary, this application has the following beneficial effects:

[0029] 1. In the embodiment of the present application, coal gangue is used as aggregate, which realizes the effective utilization of solid waste and reduces the production cost of shotcrete;

[0030] 2. In the embodiment of the present application, the addition of admixtures can effectively suppress the reduction in the strength of shotcrete caused by coal gangue, and can effectively ensure the early strength and late strength of shotcrete;

[0031] 3. The polyaluminum sulfate, triisopropanolamine, aluminum sulfate 18-hydrate, ethylene glycol, nano-aluminum hydroxide, and triisopropanolamine octanoate in component B of the present invention can work together with the admixture to effectively ensure the early and late strengths of the shotcrete, so that the shotcrete has better mechanical properties while using coal gangue as aggregate. DETAILED DESCRIPTION

[0032] The technical solutions in the embodiments of the present application are described below.

[0033] It is particularly noted that, unless otherwise defined, the technical terms used in the following examples have the same meanings as commonly understood by those skilled in the art to which this invention belongs. The experimental reagents used in the following examples, unless otherwise specified, are all conventional biochemical reagents; the raw materials, instruments, and equipment used in the following examples are all commercially available or can be obtained through existing methods; the amounts of the experimental reagents used, unless otherwise specified, are those used in conventional experimental procedures; and the experimental methods described, unless otherwise specified, are all conventional methods.

[0034] The cement in the embodiment of the present application is P.O42.5 ordinary Portland cement; the water reducer is a polycarboxylic acid high-performance water reducer with a water reduction rate of 26.8%; and the air entraining agent is sodium alkyl sulfate.

[0035] Example 1

[0036] A coal gangue-based shotcrete for mining comprises component A and component B in a weight ratio of 100:3; component A comprises the following components in parts by weight: 100 parts of cement, 135 parts of coal gangue, 50 parts of water, 15 parts of admixture, 1 part of calcium formate, 4 parts of water reducer, and 1 part of air entraining agent; and component B comprises the following components in parts by weight: 4 parts of polyaluminum sulfate, 1 part of triisopropanolamine, 1 part of aluminum sulfate 18hydrate, 1 part of ethylene glycol, 2 parts of nano-aluminum hydroxide, and 3 parts of triisopropanolamine octanoate. The gangue is divided into different particle size ranges of 0-2.5mm, 2.5-5mm, 5-10mm, and 10-15mm. The weight percentages of the gangue aggregates in each particle size range are 57.4% for 0-2.5mm, 13.8% for 2.5-5mm, 15.1% for 5-10mm, and 13.7% for 10-15mm. The admixtures include silica fume, nano-silicon dioxide, and nano-aluminum silicate in a weight ratio of 3:2:2.

[0037] The above-mentioned shotcrete is prepared by the following method:

[0038] (1) According to the required ratio of raw materials, 100 parts of cement, 135 parts of coal gangue, 50 parts of water, 15 parts of admixture, 1 part of calcium formate, 4 parts of water reducer, and 1 part of air entraining agent were mixed uniformly to obtain component A;

[0039] (2) 4 parts of polyaluminum sulfate were heated and dissolved in 10 parts of water at a temperature of 60° C., and then 1 part of triisopropanolamine and 1 part of ethylene glycol were added at the same temperature and stirred for 30 minutes. Then, 1 part of aluminum sulfate 18hydrate was added and stirred for 30 minutes. Then, 2 parts of nano-aluminum hydroxide were added and stirred for 30 minutes. 3 parts of triisopropanolamine octanoate were added dropwise while stirring to obtain component B;

[0040] (3) Mix component A and component B evenly in a weight ratio of 100:3.

[0041] Examples 2-8

[0042] The difference between Example 2-8 and Example 1 is that the ratio of the particle size range of the coal gangue is different, as shown in Table 1.

[0043] Table 1 Aggregate proportions of coal gangue in various particle size ranges in shotcrete of Examples 1-8

[0044] Example 0-2.5mm(%) 2.5-5mm(%) 5-10mm(%) 10-15mm(%) 1 57.4 13.8 15.1 13.7 2 48.1 15.4 19.8 16.7 3 39.9 16.9 22.8 20.4 4 34.5 17.1 26.2 22.2 5 28.1 17.6 28.5 25.8 6 100 / / / 7 68.7 31.3 / / 8 49.8 19.5 30.7 /

[0045] Note: “ / ” in the table means not added.

[0046] Performance testing of shotcrete for mining

[0047] According to the requirements of Appendix B of JGJ / T 372-2016 "Technical Specification for Application of Shotcrete", shotcrete specimens were prepared and the performance of the shotcrete specimens was tested according to the following method:

[0048] 1. Slump: Test the slump of concrete mixture at room temperature (20±5)℃ according to the slump test in GB / T50080-2016 "Standard for Test Methods of Performance of Ordinary Concrete Mixtures".

[0049] 2. Compressive strength: Prepare standard test blocks according to the method in GB / T50081-2016 "Standard for Test Methods of Mechanical Properties of Ordinary Concrete" and measure the compressive strength of the standard test blocks after curing for 1d, 7d, and 28d.

[0050] 3. Chloride ion diffusion coefficient: The chloride ion diffusion coefficient of the standard test block is tested according to the RCM method in GB / T50082-2009 "Standard for Test Methods for Long-term Performance and Durability of Ordinary Concrete".

[0051] 4. Water penetration resistance: Test the water penetration depth of the standard test block using the step-by-step pressure method specified in GB / T50082-2009, "Standard for Test Methods for Long-term Performance and Durability of Ordinary Concrete."

[0052] Table 2 Performance test results of mine shotcrete in Examples 1-8

[0053]

[0054] As can be seen from Examples 1-8 and Table 2, the present invention improves the impermeability of shotcrete while maintaining mechanical properties by compounding coal gangue with particle sizes of 0-2.5 mm, 2.5-5 mm, 5-10 mm, and 10-15 mm. Furthermore, the shotcrete prepared in the present invention meets the requirements of JGJ / T 372-2016, "Technical Specification for the Application of Shotcrete," with a slump of 80-120 mm, ensuring the workability and pumpability of the shotcrete. In Example 4, the coal gangue with particle sizes of 0-2.5 mm (34.5%), 2.5-5 mm (17.1%), 5-10 mm (26.2%), and 10-15 mm (22.2%) was compounded to prepare a shotcrete with a slump of 120 mm, a 1-day compressive strength of 13.1 MPa, a 7-day compressive strength of 48.1 MPa, a 28-day compressive strength of 61.1 MPa, and a chloride ion diffusion coefficient of 1.05×10 -12 m 2 / s, the water penetration depth is 2.8mm.

[0055] It can be seen from Examples 1 and 6-8 in combination with Table 2 that compared with the coal gangue lacking one, two, or three particle size compounds, the shotcrete prepared from the coal gangue with four particle size compounds has better mechanical properties and construction performance. That is to say, on the basis of ensuring the mechanical properties, in order to improve the impermeability of the shotcrete, coal gangue with particle sizes of 0-2.5 mm, 2.5-5 mm, 5-10 mm, and 10-15 mm are indispensable.

[0056] The shotcrete in Example 4 was sprayed onto the construction surface using a SPJ2010 mining wet spraying machine. The rebound rate of the shotcrete was 6.0%.

[0057] Next, based on Example 4, the effect of the weight ratio of component A to component B on shotcrete was investigated.

[0058] Examples 9-10

[0059] Examples 9-10 provide a gangue-based shotcrete for mining. The difference from Example 4 is that the weight ratio of component A to component B in the shotcrete is different. At the same time, the performance of the shotcrete for mining in Examples 9-10 was tested, as shown in Table 3.

[0060] Comparative Examples 1-3

[0061] Comparative Examples 1-3 provide a coal gangue-based shotcrete for mining. The difference from Example 1 is that the weight ratio of component A to component B in the shotcrete is different. At the same time, the performance of the shotcrete for mining in Comparative Examples 1-3 was tested, as shown in Table 3.

[0062] Table 3 Test results of various properties of shotcrete in Example 10 and Comparative Examples 1-3

[0063]

[0064] From Examples 4, 9-10 and Table 3, it can be seen that the weight ratio of component A to component B in shotcrete has little effect on slump, but has a greater effect on compressive strength. At the same time, combined with comparisons 1-3, it can be seen that the weight ratio of component A to component B is between 100:(3-9), which can make the shotcrete have better mechanical properties and impermeability. Among them, in Example 9, the slump of the shotcrete is 122mm, the 1d compressive strength is 14.5Mpa, the 7d compressive strength is 52.4Mpa, the 28d compressive strength is 63.2Mpa, and the chloride ion diffusion coefficient is 1.02×10 -12 m 2 / s, the water penetration depth is 2.6mm.

[0065] Next, we will explore the effects of the presence or absence of components in component B on the properties of shotcrete.

[0066] Comparative Example 4

[0067] Comparative Example 4 provides a coal gangue-based shotcrete for mining, which differs from Example 6 in that triisopropanolamine is not added to component B.

[0068] Comparative Example 5

[0069] Comparative Example 5 provides a coal gangue-based shotcrete for mining, which differs from Example 6 in that no polyaluminum sulfate and aluminum sulfate 18-hydrate are added to component B.

[0070] Comparative Example 6

[0071] Comparative Example 6 provides a coal gangue-based shotcrete for mining, which differs from Example 6 in that no ethylene glycol is added to component B.

[0072] Comparative Example 7

[0073] Comparative Example 7 provides a coal gangue-based shotcrete for mining, which differs from Example 6 in that no nano-aluminum hydroxide is added to component B.

[0074] Comparative Example 8

[0075] Comparative Example 8 provides a coal gangue-based shotcrete for mining, which differs from Example 6 in that triisopropylamine octanoate is not added to component B.

[0076] Table 4 Test results of various properties of shotcrete in comparative examples 4-8

[0077]

[0078] According to Example 6 and Comparative Examples 4-8 and in conjunction with Table 4, the presence or absence of each component in the B component, for the ultimate compressive strength of shotcrete, there is a relatively obvious impact, it can be said that shotcrete, while using coal gangue as aggregate, still has the reason of preferably mechanical property, and a large part comes from the coordination of each component in the B component. Wherein, triisopropanolamine, nano-aluminum hydroxide and triisopropanolamine octanoate are larger than the impact of later 28d ultimate compressive strength on the early 1d ultimate compressive strength of shotcrete; Ethylene glycol has less impact on the early 1d ultimate compressive strength of shotcrete, and has a larger impact on later 28d ultimate compressive strength; And polyaluminum sulfate and aluminum sulfate 18 hydrate are larger for the early 1d ultimate compressive strength and later 28d ultimate compressive strength of shotcrete. Therefore, in the B component, each component needs to be used in a coordinated manner, to improve the mechanical property of the mine-used shotcrete based on coal gangue.

[0079] Since the sprayed concrete obtained in Example 9 has better compressive strength, the content of each component in component A and component B in the sprayed concrete was explored based on Example 9.

[0080] Example 11

[0081] Example 11 provides a gangue-based shotcrete for mining, comprising component A and component B in a weight ratio of 100:6. This differs from Example 9 in that the proportions of the components in component A and component B are different. Specifically, component A comprises the following components in parts by weight: 100 parts cement, 140 parts gangue, 60 parts water, 18 parts admixture, 3 parts calcium formate, 4 parts water reducer, and 1 part air-entraining agent; and component B comprises the following components in parts by weight: 6 parts polyaluminum sulfate, 6 parts triisopropanolamine, 3 parts aluminum sulfate 18-hydrate, 2 parts ethylene glycol, 4 parts nano-aluminum hydroxide, and 4 parts triisopropanolamine octanoate.

[0082] Example 12

[0083] Example 12 provides a gangue-based shotcrete for mining, comprising component A and component B in a weight ratio of 100:6. This differs from Example 9 in that the proportions of the components in component A and component B are different. Specifically, component A comprises the following components in parts by weight: 140 parts cement, 150 parts gangue, 70 parts water, 20 parts admixture, 5 parts calcium formate, 5 parts water reducer, and 2 parts air-entraining agent; and component B comprises the following components in parts by weight: 10 parts polyaluminum sulfate, 9 parts triisopropanolamine, 4 parts aluminum sulfate 18-hydrate, 4 parts ethylene glycol, 5 parts nano-aluminum hydroxide, and 5 parts triisopropanolamine octanoate.

[0084] Example 13

[0085] Example 13 provides a coal gangue-based shotcrete for mining, which differs from Example 9 in that the admixture includes silica fume, nano-silicon dioxide and nano-aluminum silicate in a weight ratio of 4:3:2.

[0086] Example 14

[0087] Example 14 provides a coal gangue-based shotcrete for mining, which differs from Example 9 in that the admixture includes silica fume, nano-silicon dioxide and nano-aluminum silicate in a weight ratio of 5:4:1.

[0088] Example 15

[0089] Example 15 provides a coal gangue-based shotcrete for mining, which differs from Example 9 in that the admixture includes silica fume, nano-silicon dioxide and nano-aluminum silicate in a weight ratio of 1:6:3.

[0090] Example 16

[0091] Example 16 provides a coal gangue-based shotcrete for mining, which differs from Example 9 in that the admixture is silica fume.

[0092] Example 17

[0093] Example 17 provides a coal gangue-based shotcrete for mining, which differs from Example 9 in that the admixture is nano-silicon dioxide.

[0094] Example 18

[0095] Example 18 provides a coal gangue-based shotcrete for mining, which differs from Example 9 in that the admixture is nano-aluminum silicate.

[0096] The performance of the shotcrete prepared in Examples 11-18 was tested, and the test results are shown in Table 5.

[0097] Table 5 Performance test results of the mine shotcrete prepared in Examples 9, 11-18

[0098]

[0099] According to Examples 9, 11-12 and Table 5, it can be seen that the ratio of each component in Component A and Component B constituting the mine sprayed concrete can affect the compressive and impermeability properties of the sprayed concrete. In Example 11, the slump of the sprayed concrete is 150 mm, the 1-day compressive strength is 15.8 MPa, the 7-day compressive strength is 54.6 MPa, the 28-day compressive strength is 65.8 MPa, and the chloride ion diffusion coefficient is 0.88×10 -12 m 2 / s, water penetration depth is 2.1mm, and all performances are optimal.

[0100] According to Examples 9, 13-18 and Table 5, it can be seen that the weight ratio of silica fume, nano-silica and nano-aluminum silicate in the admixture can affect the compressive strength of the shotcrete, but has little effect on the anti-seepage performance. Among them, compared with Examples 9 and 14-18, in Example 13, when the weight ratio of silica fume, nano-silica and nano-aluminum silicate is 4:3:2, the compressive strength of the shotcrete is better, with a 1d compressive strength of 14.8 MPa, a 7d compressive strength of 53.8 MPa, and a 28d compressive strength of 64.6 MPa.

[0101] The shotcrete in Example 11 was sprayed onto the construction surface using a SPJ2010 mining wet spraying machine. The rebound rate of the shotcrete was 2.8%.

[0102] Finally, it should be noted that the above embodiments are merely illustrative of the technical solutions of the present application. Those skilled in the art should understand that, although the present application has been described in detail with reference to the aforementioned embodiments, the technical solutions described in the aforementioned embodiments may be modified or some of the technical features thereof may be replaced with equivalents. However, such modifications or replacements do not deviate from the spirit and scope of the technical solutions in the various embodiments of the present application.

Claims

1. A mine-use shotcrete based on coal gangue, characterized in that: The shotcrete comprises component A and component B in a weight ratio of 100:(3-9); wherein component A comprises the following components in parts by weight: 100-140 parts of cement, 135-150 parts of coal gangue, 50-70 parts of water, 15-20 parts of admixture, 1-5 parts of calcium formate, 4-5 parts of water reducer, and 1-2 parts of air entraining agent; Component B comprises the following components in parts by weight: 4-10 parts of polyaluminum sulfate, 1-9 parts of triisopropanolamine, 1-4 parts of aluminum sulfate 18hydrate, 1-4 parts of ethylene glycol, 2-5 parts of nano aluminum hydroxide, and 3-5 parts of triisopropanolamine octanoate.

2. The sprayed concrete according to claim 1, characterized in that The shotcrete comprises component A and component B in a weight ratio of 100:(3-9); wherein component A comprises the following components in parts by weight: 100 parts cement, 135-140 parts coal gangue, 50-60 parts water, 18-20 parts admixture, 3-5 parts calcium formate, 4-5 parts water reducer, and 1-2 parts air entraining agent; Component B comprises the following components in parts by weight: 6-8 parts of polyaluminum sulfate, 4-6 parts of triisopropanolamine, 1-3 parts of aluminum sulfate 18hydrate, 2-3 parts of ethylene glycol, 3-4 parts of nano aluminum hydroxide, and 3-4 parts of triisopropanolamine octanoate.

3. The sprayed concrete according to claim 2, characterized in that The sprayed concrete comprises component A and component B in a weight ratio of 100:(3-9); wherein component A comprises the following components in parts by weight: 100 parts of cement, 140 parts of coal gangue, 60 parts of water, 18 parts of admixture, 3 parts of calcium formate, 4 parts of water reducer, and 1 part of air entraining agent; Component B includes the following components in parts by weight: 6 parts of polyaluminum sulfate, 6 parts of triisopropanolamine, 3 parts of aluminum sulfate 18hydrate, 2 parts of ethylene glycol, 4 parts of nano aluminum hydroxide, and 4 parts of triisopropanolamine octanoate.

4. The sprayed concrete according to any one of claims 1 to 3, characterized in that: The B component is prepared by the following steps: polyaluminum sulfate is heated and dissolved in water at a temperature of 55-65° C., triisopropanolamine and ethylene glycol are then added at the same temperature and stirred for 30 minutes, aluminum sulfate 18hydrate is then added and stirred for 30 minutes, nano aluminum hydroxide is then added and stirred for 30 minutes, and triisopropanolamine octanoate is added dropwise while stirring to obtain the B component.

5. The sprayed concrete according to any one of claims 1 to 3, characterized in that: The gangue is divided into gangue aggregates with different particle size ranges of 0-2.5mm, 2.5-5mm, 5-10mm, and 10-15mm, and the weight percentages of the gangue aggregates in each particle size range are 0-2.5mm: 28.1-57.4%, 2.5-5mm: 13.8-17.6%, 5-10mm: 15.1-28.5%, and 10-15mm: 13.7-25.8%.

6. The sprayed concrete according to any one of claims 1 to 3, characterized in that: The admixture comprises silica fume, nano silicon dioxide and nano aluminum silicate in a weight ratio of 3-5:2-4:1-2.

7. The sprayed concrete according to claim 1, characterized in that The air entraining agent includes any one of sodium alkyl sulfonate, sodium alkyl sulfate, sodium alkylbenzene sulfonate, and fatty alcohol polyoxyethylene ether.

8. The sprayed concrete according to claim 1, characterized in that The cement is P.O42.5 ordinary Portland cement.

9. The sprayed concrete according to claim 1, characterized in that The water reducer is a polycarboxylic acid high performance water reducer.

10. A method for preparing shotcrete for mining based on coal gangue, characterized in that: The following steps are involved: (1) According to the required ratio of raw materials, 100-140 parts of cement, 135-150 parts of coal gangue, 50-70 parts of water, 15-20 parts of admixture, 1-5 parts of calcium formate, 4-5 parts of water reducer, and 1-2 parts of air entraining agent are mixed uniformly to obtain component A; (2) 4-10 parts of polyaluminum sulfate are heated and dissolved in 10-20 parts of water at a temperature of 55-65° C., and then 1-9 parts of triisopropanolamine and 1-4 parts of ethylene glycol are added at the same temperature and stirred for 30 minutes. Then, 1-4 parts of aluminum sulfate 18hydrate are added and stirred for 30 minutes, and then 2-5 parts of nano-aluminum hydroxide are added and stirred for 30 minutes. 3-5 parts of triisopropanolamine octanoate are added dropwise while stirring to obtain component B; (3) Mix component A and component B evenly in a weight ratio of 100:(3-9).

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