Self-compacting prestressed guniting material and preparation method thereof

Abstract

The invention provides a self-compacting prestressed guniting material and a preparation method thereof, and the self-compacting prestressed guniting material comprises the following components in parts by mass: 12-15 parts of a self-compacting mixture, 1 part of a dispersant, 1-2 parts of a first interface stabilizer and 100 parts of magnesium aluminate cement, the self-compacting mixture comprises 10-15 parts of a self-compacting active material, 1-3 parts of a second interface stabilizer, 1-2 parts of a self-compacting accelerant and 1 part of a toughening agent. When the guniting material is used on site, water is added for stirring to generate micro-nano NH3 bubbles; the guniting material covers the surface of the surrounding rock of the roadway and spontaneously expands, and can automatically flow into and completely fill all cracks and recesses, so that all-directional tight fit with the surrounding rock is realized, the interface defects are eliminated, and uniform load transmission is ensured. The invention further provides a preparation method of the guniting material, and the preparation method has the characteristics of simple process, low cost and easiness in popularization and application.

Description

Technical Field

[0001] This application relates to the field of shotcrete materials technology, and in particular to a self-compacting prestressed shotcrete material and its preparation method. Background Technology

[0002] Shotcrete support is an important method of supporting the surrounding rock in coal mines in my country. Traditional shotcrete materials are prone to "bridging" and voids on the uneven surface of the surrounding rock due to insufficient fluidity and density. This results in incomplete bonding between the shotcrete support layer and the rock mass, forming local stress concentration and water seepage channels, which seriously affects the integrity and durability of the support.

[0003] Related technologies attempt to optimize concrete mix proportions. For example, by using a high-bonding mix proportion, appropriately increasing the amount of cementitious materials (cement), and incorporating high-quality silica fume and fine steel fibers, the cohesiveness, early strength, and toughness of concrete can be significantly improved. Related technologies also strictly control accelerators, precisely adding high-efficiency, alkali-free or low-alkali accelerators matched to cement according to ambient temperature and construction requirements, ensuring controllable initial setting time and reducing rebound. However, conventional concrete mix proportions are difficult to adapt to extreme conditions such as high ground temperatures (rapid water loss and cracking), abundant water (dilution by scouring), and corrosive environments (chemical erosion), and the grouting materials lack environmental compatibility. Furthermore, in the early stages of grouting, accelerators are often added to improve early strength, but this may sacrifice later strength and bond strength; pursuing fluidity may reduce segregation resistance.

[0004] Therefore, those skilled in the art need to further optimize the grouting material to overcome the technical defects in related technologies that lead to incomplete bonding between the shotcrete support layer and the rock mass, resulting in local stress concentration and seepage channels. Summary of the Invention

[0005] This application aims to at least partially solve one of the technical problems in the related art. This application proposes a self-compacting prestressed shotcrete material and its preparation method. The shotcrete material provided in this application generates micro-nano NH3 bubbles when water is added; this causes the shotcrete material to cover the surface of the surrounding rock in the tunnel and spontaneously expand. Based on the self-expansion characteristics, high fluidity, anti-segregation, and filling properties of the shotcrete slurry generated by adding water to the shotcrete material, it can automatically flow in and completely fill all cracks and depressions, achieving comprehensive and tight adhesion with the surrounding rock, thereby eliminating interface defects and ensuring uniform load transfer.

[0006] According to an embodiment of the first aspect of this application, a self-compacting prestressed shotcrete material is provided, comprising the following components in parts by weight: 12-15 parts of self-compacting mixture, 1 part of dispersant, 1-2 parts of first interface stabilizer, and 100 parts of magnesium aluminate cement. The self-compacting mixture comprises 10-15 parts of self-compacting active material, 1-3 parts of second interface stabilizer, 1-2 parts of self-compacting accelerator, and 1 part of toughening agent.

[0007] In some embodiments, the self-compacting active material comprises magnesium nitride and calcium nitride in a mass ratio of 1:2.

[0008] In some embodiments, the dispersant comprises sodium perfluoro-1-octanesulfonate and calcium 2-aminoethanesulfonate in equal weight.

[0009] In some embodiments, both the first interface stabilizer and the second interface stabilizer are 5-eicosyl-1,3-benzenediol.

[0010] In some embodiments, the self-compacting accelerator comprises ammonium chloride and ammonium nitrate in a mass ratio of 1:4.

[0011] In some embodiments, the toughening agent comprises 1-methyltripyrimidinone and dihydro-6-methyl-2,4-diprimidinone in a mass ratio of 2:1.

[0012] According to an embodiment of the second aspect of this application, a method for preparing a self-compacting prestressed shotcrete material is provided, comprising the following steps: The self-compacting active material, interface stabilizer, self-compacting accelerator and toughening agent are mixed according to stoichiometry to obtain a self-compacting mixture. The self-compacting mixture, dispersant, interface stabilizer and magnesium aluminate cement are mixed according to stoichiometry to obtain the spraying material described in any of the embodiments of the first aspect of this application.

[0013] In some embodiments, the self-compacting mixture, the dispersant, the interface stabilizer, and the magnesium aluminate cement are dry-mixed for 30-40 minutes.

[0014] In some embodiments, the sprayed material is mixed with water during on-site use to generate micro-nano NH3 bubbles; this causes the sprayed material to cover the surface of the surrounding rock in the tunnel and spontaneously expand.

[0015] The sprayed grout material of this application reacts with water during application to generate a large number of micro- and nano-NH3 bubbles. These micro- and nano-bubbles produce a "ball effect" during the flow of the sprayed grout material, improving its fluidity. Simultaneously, alkaline substances such as calcium hydroxide and magnesium hydroxide are generated during the formation of these micro- and nano-NH3 bubbles. The alkaline hydroxide ions attack and break stable chemical bonds (such as Si-O and Al-O bonds) on the surface of the cementitious material's minerals or compounds, lowering the reaction activation energy. Furthermore, the alkaline hydroxide ions act as heterogeneous crystal nuclei during the hydration process of the cementitious material, promoting crystal nucleation and also acting as catalysts in the formation of intermediates, promoting the rapid nucleation and growth of more stable hydration products (such as CSH gel and ettringite). This overall accelerates the hydration process and increases the degree of hydration and stone formation of the sprayed grout material, thereby improving its mechanical strength.

[0016] Therefore, the shotcrete material of this application covers and spontaneously expands on the surface of the surrounding rock in the tunnel, effectively filling the uneven pores on the surface of the surrounding rock. At the same time, the airlift effect of the micro-nano bubbles generated by the shotcrete material can produce micro-convection in the slurry, significantly reducing the amount of solutes (such as calcium ions, OH-) - The increased diffusion boundary layer thickness (of silicate ions) allows ions to reach the reaction interface more quickly, accelerating the dissolution and precipitation process and promoting the hydration and hardening of the sprayed material. Simultaneously, the presence of numerous deformable soft interfaces via micro- and nano-bubbles creates high stress concentration around these bubbles when the sprayed material is subjected to stress, inducing plastic deformation in the surrounding matrix and preventing the propagation of a single master crack. Furthermore, the presence of bubble interfaces increases the actual load-bearing interface area, allowing energy dissipation mechanisms to occur within a larger volume, thereby significantly improving the fracture toughness and impact resistance of the sprayed material and enhancing the spraying effect.

[0017] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0018] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein: Figure 1 This is a flowchart of a method for preparing sprayed material according to one embodiment of this application. Detailed Implementation

[0019] Embodiments of this application are described in detail below. Examples of these embodiments are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application. Rather, this application includes all variations, modifications, and equivalents falling within the spirit and scope of the appended claims.

[0020] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0021] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0022] To achieve the above objectives, an embodiment of the first aspect of this application provides a self-compacting prestressed shotcrete material comprising the following components in parts by weight: 12-15 parts of self-compacting mixture, 1 part of dispersant, 1-2 parts of first interface stabilizer, and 100 parts of magnesium aluminate cement. The self-compacting mixture comprises 10-15 parts of self-compacting active material, 1-3 parts of second interface stabilizer, 1-2 parts of self-compacting accelerator, and 1 part of toughening agent.

[0023] In this embodiment, the shotcrete material includes 12-15 parts by weight of a self-compacting mixture. The self-compacting mixture comprises a self-compacting active material, a second interface stabilizer, a self-compacting accelerator, and a toughening agent. Specifically, based on the self-compacting mixture, it comprises 10-15 parts by weight of the self-compacting active material, 1-3 parts by weight of the second interface stabilizer, 1-2 parts by weight of the self-compacting accelerator, and 1 part by weight of the toughening agent. The self-compacting mixture in this embodiment is the core component of the shotcrete material. Through its built-in chemical expansion source, it actively applies continuous prestress to the surrounding rock during the shotcrete hardening process, effectively offsetting the unloading tensile stress after tunnel excavation, inhibiting the development of the loosened rock zone, and significantly improving the active bearing capacity and crack resistance of the support system. In some embodiments, the mass percentage of the self-compacting mixture can be 12, 13, 14, or 15 parts. If the mass percentage of the self-compacting mixture is small, such as less than 12 parts, the shotcrete material will not be sufficiently dense and will not adhere tightly to the coal and rock mass. If the self-compacting mixture has a large proportion, such as more than 15 parts, more expanding gas will be generated, and the mechanical strength of the shotcrete material will be reduced.

[0024] In this embodiment, based on the self-compacting mixture by mass, the self-compacting mixture includes 10-15 parts of self-compacting active material, which comprises magnesium nitride and calcium nitride in a mass ratio of 1:2. When applied to the sprayed material, magnesium nitride and calcium nitride react with water to generate a large number of micro-nano NH3 bubbles, producing a "ball effect" that improves the fluidity of the sprayed material. Simultaneously, calcium hydroxide and magnesium hydroxide are generated, which can act as heterogeneous crystal nuclei, promoting crystal nucleation in the cementitious material and increasing its mechanical strength. In some embodiments, the mass percentage of the self-compacting active material can be 10, 11, 12, 13, 14, or 15 parts, etc. If the mass percentage of the self-compacting active material is small, such as less than 10 parts, the sprayed material will not be sufficiently compacted and will not adhere tightly to the coal and rock mass. If the mass percentage of the self-compacting active material is large, such as greater than 15 parts, there will be many stress concentration areas, reducing the mechanical strength of the sprayed material.

[0025] The mechanism by which the dispersants and interface stabilizers in this application regulate the reaction of magnesium nitride (Mg3N2) and calcium nitride (Ca3N2) lies in forming a kinetic barrier and a controlled release layer through physical adsorption and chemical isolation. Specifically, the molecular structure of these additives contains both hydrophilic groups and hydrophobic long chains. When added to the nitride powder system, their hydrophobic segments are anchored to the surface of the nitride particles through physical adsorption or weak chemical interaction, while the hydrophilic groups extend outward. This process first forms a dense hydrophobic protective film on the particle surface, effectively preventing direct, large-area contact between water molecules and active nitrides, transforming the violent overall reaction into a controlled process that requires diffusion through the protective film. Secondly, these adsorbed molecules significantly reduce the surface energy of the particles and prevent particle aggregation through steric hindrance, ensuring uniform dispersion rather than clumping in water. This avoids explosive reactions caused by localized concentrated exothermic reactions and the instantaneous generation of large amounts of hydrogen and ammonia, thus smoothing out the reaction rate and exothermic peak. Ultimately, the reaction proceeded at a controllable rate, hydrogen was released gradually, and the temperature rise of the reaction system slowed down, achieving a safe transition from "explosive contact" to "mild and gradual reaction".

[0026] In some embodiments, based on the self-compacting mixture by weight, the self-compacting mixture includes 1-3 parts of a second interface stabilizer, which is 5-eicosyl-1,3-benzenediol. Its function is to precisely control rheological properties. By adsorbing onto the surface of cement and fine particles, it provides steric hindrance and electrostatic repulsion, effectively disintegrating the flocculated structure and significantly reducing the yield stress of the slurry, thereby giving the material excellent self-leveling and pumpability. Simultaneously, it moderately increases plastic viscosity, ensuring aggregate suspension and preventing segregation and bleeding. When the dosage is precise, it can achieve low rebound, high density, and a uniform microstructure; however, excessive or insufficient dosage will directly lead to construction problems and performance defects such as segregation, pipe blockage, or a surge in rebound rate. In some embodiments, the weight percentage of the second interface stabilizer can be 1 part, 2 parts, or 3 parts, etc. If the weight percentage of the second interface stabilizer is small, such as less than 1 part, the internal flocculated structure of the slurry is strong, the fluidity is poor, and the yield stress is too high, resulting in high pumping resistance and poor pipe discharge. Poor atomization and high rebound rate during spraying make it difficult to form a dense and smooth coating. If the amount of the second interface stabilizer is too large, such as more than 3 parts, it leads to excessive lubrication of the slurry, abnormally high viscosity, and excessive decrease in yield stress, which may cause aggregate sedimentation, segregation, and bleeding, thus damaging uniformity and affecting final strength and durability. Dripping and increased rebound are also likely to occur during spraying.

[0027] In some embodiments, based on the self-compacting mixture, the self-compacting mixture includes 1-2 parts by weight of a self-compacting accelerator. The self-compacting accelerator comprises ammonium chloride and ammonium nitrate in a mass ratio of 1:4, and its function is to promote the reaction between the self-compacting active material and water, thereby promoting self-expansion and self-compacting. In some embodiments, the mass percentage of the self-compacting accelerator may be 1 or 2 parts. If the mass percentage of the self-compacting accelerator is small, such as less than 1 part, the self-compacting effect is poor, and the coal and rock mass does not adhere tightly to the shotcrete material. If the mass percentage of the self-compacting accelerator is large, such as greater than 2 parts, the toughness of the shotcrete material is reduced.

[0028] In some embodiments, based on a self-compacting mixture, the self-compacting mixture includes 1 part toughening agent by mass. The toughening agent comprises 1-methyltripyrimidinone and dihydro-6-methyl-2,4-diamyrimidinone in a mass ratio of 2:1. Its function is to effectively disperse and absorb stress when the material is under stress by introducing flexible molecular chains or energy dissipation mechanisms (such as microcrack bridging and shear yielding), transforming brittle fracture into ductile failure, thereby significantly improving the material's impact resistance, fracture toughness, and durability. In some embodiments, if the amount of toughening agent is small, such as less than 1 part, insufficient toughening agent will prevent the effective formation of an energy dissipation network. The internal stress concentration of the material cannot be alleviated, exhibiting typical brittle characteristics: poor impact resistance, easy crack formation and rapid crack propagation, and extreme susceptibility to failure under dynamic loads or temperature changes. If the toughening agent is used in large quantities, such as more than 1 part, the excessive amount of toughening agent will over-dilute the material matrix, resulting in a significant decrease in core mechanical properties and durability indicators such as modulus, strength, hardness and heat resistance. The material may become too soft and unable to meet the load-bearing requirements.

[0029] In some embodiments, the sprayed slurry material includes 1 part of a dispersant, wherein the dispersant comprises sodium perfluoro-1-octanesulfonate and calcium 2-aminoethanesulfonate by equal mass. Its function is to ensure uniform dispersion of self-compacting molecules within the matrix. In some embodiments, if the amount of the self-compacting accelerator is small, such as less than 1 part, the dispersion effect is poor, and the self-compacting effect is minimal. If the amount of the self-compacting accelerator is large, such as greater than 1 part, it affects the flowability of the sprayed slurry, making pumping difficult.

[0030] In some embodiments, the sprayed slurry material includes 1-2 parts of a first interface stabilizer, wherein the first interface stabilizer is 5-eicosyl-1,3-benzenediol, which significantly reduces the yield stress of the slurry, thereby imparting excellent self-leveling and pumpability to the material. In some embodiments, the first interface stabilizer may be 1 part or 2 parts. If the amount of the first interface stabilizer is small, such as less than 1 part, the self-leveling and pumpability will be insufficient. If the amount of the first interface stabilizer is large, such as more than 2 parts, the slurry will have a slow setting rate and a long curing time.

[0031] In some embodiments, the shotcrete material includes 100 parts of magnesium aluminate cement, which acts as the matrix of the shotcrete material, providing it with basic mechanical strength, toughness, etc. If the amount of magnesium aluminate cement is small, such as less than 100 parts, the mechanical strength of the shotcrete material will be insufficient. If the amount of magnesium aluminate cement is large, such as greater than 100 parts, the prestress will be low and the self-compacting effect will be poor.

[0032] In some embodiments, the self-compacting mixture utilizes a built-in chemical expansion source coupled with a mechanical means of anchor bolt / net coordination. This combination of material and technology can further solve the construction problem of incomplete coverage and transform passive support into active reinforcement. It is irreplaceable and necessary for ensuring the long-term stability and safety of deep, high-stress, and strongly mining-affected roadways, and for reducing later maintenance costs.

[0033] According to an embodiment of the second aspect of this application, a method for preparing a self-compacting prestressed shotcrete material is provided, such as... Figure 1 As shown, it includes the following steps: S1: The self-compacting active material, interface stabilizer, self-compacting accelerator and toughening agent are mixed according to stoichiometry to obtain a self-compacting mixture; S2: The self-compacting mixture, dispersant, interface stabilizer and magnesium aluminate cement are mixed according to stoichiometry to obtain any of the spraying materials in the embodiments of the first aspect of this application.

[0034] Specifically, in step S1, 10-15 parts by weight of the self-compacting active material, 1-3 parts by weight of the second interface stabilizer, 1-2 parts by weight of the self-compacting accelerator, and 1 part by weight of the toughening agent are weighed and mixed evenly to obtain a self-compacting mixture. In step S, 12-15 parts by weight of the self-compacting mixture, 1 part by weight of the dispersant, 1-2 parts by weight of the first interface stabilizer, and 100 parts by weight of the magnesium aluminate cement are weighed and placed in a dry powder mixer and dry-mixed for 30-40 minutes. Ultimately, the preparation method of this embodiment is simple, low-cost, provides effective sprayed grout support, and is easy to promote and apply.

[0035] To facilitate a further understanding of this application, the solutions described below are further described in conjunction with embodiments. Those skilled in the art will understand that the examples described in this application are only a portion of the examples, and any other suitable specific examples are within the scope of this application.

[0036] Example 1 This embodiment provides a self-compacting prestressed shotcrete material, the preparation method and specific operating parameters of which are as follows: 12 kg of self-compacting active material, 1 kg of second interface stabilizer, 1 kg of self-compacting accelerator and 1 kg of toughening agent are weighed according to the mass fractions, and mixed evenly to obtain a self-compacting mixture.

[0037] Then, weigh out 15 kg of self-compacting mixture, 1 kg of dispersant, 2 kg of first interface stabilizer and 100 parts of magnesium aluminate cement according to the mass ratio, put them into a dry powder mixer and dry mix for 30 min to prepare self-compacting prestressed sprayed grout material.

[0038] Example 2 This embodiment differs from Embodiment 1 in the following ways: 11 kg of self-compacting active material, 2 kg of second interface stabilizer, 1 kg of self-compacting accelerator and 1 kg of toughening agent were weighed according to the mass fractions and mixed evenly to obtain a self-compacting mixture.

[0039] Example 3 This embodiment differs from Embodiment 1 in the following ways: 10 kg of self-compacting active material, 1 kg of second interface stabilizer, 1 kg of self-compacting accelerator, and 1 kg of toughening agent are weighed according to their mass weight and mixed evenly to obtain a self-compacting mixture. Then, 13 kg of the self-compacting mixture, 1 kg of dispersant, 2 kg of first interface stabilizer, and 100 kg of magnesium aluminate cement are weighed according to their mass weight and placed in a dry powder mixer and dry-mixed for 30 minutes to prepare a self-compacting prestressed shotcrete material.

[0040] Example 4 This embodiment differs from Embodiment 1 in the following ways: 15 kg of self-compacting mixture, 1 kg of dispersant, 1 kg of first interface stabilizer and 100 kg of magnesium aluminate cement are weighed according to their mass weight in kilograms and put into a dry powder mixer and dry-mixed for 30 minutes to prepare a self-compacting prestressed sprayed grout material.

[0041] Example 5 This embodiment differs from Embodiment 1 in the following ways: 10 kg of self-compacting active material, 2 kg of second interface stabilizer, 2 kg of self-compacting accelerator and 1 kg of toughening agent are weighed according to their mass in kilograms and mixed evenly to obtain a self-compacting mixture.

[0042] Experimental Example After using the sprayed materials in each embodiment, the material viscosity, compressive strength, flexural strength, and surface coverage of the sprayed materials were tested, and the results are shown in Table 1.

[0043] The material viscosity test uses the rotational viscometer method. The principle is to immerse the rotor in the material to be tested and rotate it at a constant speed. The viscous resistance torque on the rotor is measured, and the viscosity value is directly calculated. It is suitable for a wide range of measurements from low viscosity liquids to high viscosity pastes.

[0044] The method for testing the compressive strength of materials is as follows: The grout is poured into standard prismatic specimens (usually 40mm × 40mm × 160mm) and cured under standard conditions. Using a pressure testing machine, axial pressure is applied to the specimen at a constant rate until failure. The compressive strength value is the maximum failure load divided by the bearing area of ​​the specimen (unit: MPa).

[0045] The method for checking the flexural strength of materials is as follows: The grout is poured into standard prism specimens (usually 40mm × 40mm × 160mm), cured under standard conditions, and a three-point bending test is performed on a material testing machine. The load at which the specimen breaks is recorded. The flexural strength value is calculated using the three-point bending formula (unit: MPa).

[0046] The surface coverage test method for sprayed grout mainly adopts a combination of direct observation and grid measurement. First, a representative test surface (usually 1m × 1m) is set in the area to be sprayed, and a standard grid (e.g., 10cm × 10cm) or an equivalent reference grid is fixed in this area before spraying. After spraying is completed, immediately or after initial curing, high-resolution images of the grid area are taken visually or with a high-definition digital camera. Experienced inspectors or image analysis software are used to identify and count the number of grid nodes effectively covered by the sprayed grout material (defined as the grout thickness meeting design requirements and being firmly bonded). The surface coverage rate is calculated as: (Number of effectively covered grid nodes / Total number of grid nodes) × 100%.

[0047] Table 1 Performance results of shotcrete materials in each embodiment

[0048] As shown in Table 1, the shotcrete material provided in this application significantly improves the grouting reinforcement effect.

[0049] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0050] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A self-compacting prestressed shotcrete material, characterized in that, The mixture comprises the following components in parts by weight: 12-15 parts of self-compacting mixture, 1 part of dispersant, 1-2 parts of first interface stabilizer, and 100 parts of magnesium aluminate cement. The self-compacting mixture includes 10-15 parts of self-compacting active material, 1-3 parts of second interface stabilizer, 1-2 parts of self-compacting accelerator, and 1 part of toughening agent.

2. The spraying material according to claim 1, characterized in that, The self-compacting active material comprises magnesium nitride and calcium nitride in a mass ratio of 1:

2.

3. The spraying material according to claim 1, characterized in that, The dispersant comprises sodium perfluoro-1-octanesulfonate and calcium 2-aminoethanesulfonate in equal amounts.

4. The shotcrete material according to claim 1, characterized in that, Both the first interface stabilizer and the second interface stabilizer are 5-eicosyl-1,3-benzenediol.

5. The shotcrete material according to claim 1, characterized in that, The self-compacting accelerator comprises ammonium chloride and ammonium nitrate in a mass ratio of 1:

4.

6. The shotcrete material according to claim 1, characterized in that, The toughening agent comprises 1-methyltripyrimidinone and dihydro-6-methyl-2,4-diprimidinone in a mass ratio of 2:

1.

7. A method for preparing a self-compacting prestressed shotcrete material, characterized in that, Includes the following steps: The self-compacting active material, interface stabilizer, self-compacting accelerator and toughening agent are mixed according to stoichiometry to obtain a self-compacting mixture. The self-compacting mixture, dispersant, interface stabilizer and magnesium aluminate cement are mixed according to stoichiometry to obtain the spraying material as described in any one of claims 1-6.

8. The preparation method according to claim 7, characterized in that, The self-compacting mixture, the dispersant, the interface stabilizer, and the magnesium aluminate cement are dry-mixed for 30-40 minutes.

9. The preparation method according to claim 7, characterized in that, When the sprayed material is used on site, water is added and stirred to generate micro-nano NH3 bubbles; this causes the sprayed material to cover the surface of the surrounding rock in the tunnel and expand spontaneously.

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