A method for preparing a projectile stun agent

Abstract

A method for preparing a shotcrete agent includes the following steps: Step 1, weighing 4%-15% of a sulfonic acid-based water-reducing agent, 15%-30% of a rheology modifier, and 20%-40% of a modifier by weight; Step 2, adding the sulfonic acid-based water-reducing agent, rheology modifier, and modifier weighed in Step 1 into a mixing container, and injecting water into the mixing container; Step 3, stirring the mixture obtained in Step 2 to obtain the shotcrete agent. The shotcrete agent prepared by this invention, when mixed into shotcrete, can effectively improve the over-pumping rate of the shotcrete, further improve the shotcrete shrinkage rate, and achieve more efficient shotcreting operations.

Description

Technical Field

[0001] This invention relates to the field of concrete technology, and in particular to a method for preparing a shotcrete agent. Background Technology

[0002] Shotcrete, as one of the main forms of support for tunnels and underground engineering projects, has seen a dramatic increase in usage with the further development of high-speed railway construction. However, in current shotcrete construction in my country, unreasonable mix proportions and unclear control parameters of the shotcrete machine lead to excessively high rebound rates during the spraying process. Statistics from numerous shotcrete-related railway tunnel projects show that the rebound rate is generally above 30%, often necessitating secondary pouring. This significantly increases construction costs and extends the construction period of shotcrete support, affects the quality of shotcrete, poses safety hazards to construction personnel operating the spraying equipment, and causes unnecessary material recycling, impacting construction efficiency, wasting materials, and placing significant pressure on the environment.

[0003] The rebound rate of shotcrete is affected by various factors, which can be mainly summarized into four categories: first, the surrounding rock conditions, environmental conditions, and construction conditions of the tunnel; second, the reasons for the shotcrete process, such as the shotcrete position and angle, shotcrete speed, and shotcrete thickness in one pass; third, the type of shotcrete equipment and nozzle type; and fourth, the reasons for the composition of shotcrete, such as the characteristics and proportion of aggregates, mix design parameters (water-cement ratio, cement dosage), and the types and dosages of mineral admixtures and polymer materials. Of the four categories of factors mentioned above, attempting to reduce rebound rate by altering the first category is difficult, costly, and lacks practical engineering significance. Current research findings on the second and third categories of influencing factors lack universality. For example, many shotcrete experts have conducted research on the spraying speed of shotcrete, but due to the influence of the type of spraying machine and the diameter and length of the conveying pipe, the working pressure corresponding to the optimal spraying speed of shotcrete aggregate is often only applicable to specific types of spraying machines and working conditions. Most railway tunnels are located in remote mountainous areas, often relying on locally sourced materials, resulting in low flexibility in the selection of shotcrete constituent materials. Therefore, the feasibility and economic efficiency of batch replacement or screening of constituent materials to reduce shotcrete rebound rate, as mentioned in the fourth category of influencing factors, are not ideal. Therefore, the main technical approach to achieving low-rebound-rate shotcrete relies on the use of polymer materials and functional admixtures. Current research has shown that incorporating ultrafine mineral admixtures such as microsilica, micro-fly ash, and ultrafine limestone powder has a good inhibitory effect on the rebound of shotcrete, but it is not conducive to the early strength development of shotcrete. Meanwhile, the application of polymer materials in shotcrete is becoming increasingly widespread, primarily in liquid form. Currently, incorporating polymer materials into shotcrete can accelerate cement hardening, improve early-stage strength, and minimize or even eliminate later-stage strength loss. Furthermore, polymer materials can alter the viscosity of the shotcrete through their physical properties, significantly improving the bond strength, reducing rebound rate, and effectively minimizing material loss caused by rebound, thus improving economic efficiency. These polymer materials mainly include: polyvinyl alcohol, polyacrylamide, polyethylene oxide, styrene-carboxylated copolymers, acrylic polymers, natural soluble resins, alkanolamines, and formates. In addition, some polymer materials possess micro-expansion, shrinkage reduction, and crack resistance properties, which can significantly improve the impermeability of shotcrete. However, the effectiveness of polymer materials is currently influenced by many factors, such as cement clinker, the type and dosage of admixtures, and cement fineness. They also suffer from drawbacks such as poor product stability, short shelf life, and high production costs, which have slowed their widespread application and development in shotcrete. Summary of the Invention

[0004] This invention provides a method for preparing a shotcrete rebound agent to overcome the shortcomings of existing technologies. The resulting shotcrete rebound agent is characterized by high efficiency, low cost, convenience, and stability. Combined with high-quality ultrafine mineral admixtures, it effectively improves the mechanical properties, workability, and durability of shotcrete while reducing its rebound rate. This invention represents a significant breakthrough and has practical implications for solving practical engineering problems such as high rebound rate in shotcrete and ensuring construction quality in tunnels.

[0005] In order to achieve the objectives of this invention, the following technologies are proposed: A method for preparing a projectile-resistant propellant, comprising the following steps: Step 1: Weigh out 4%-15% of sulfonic acid-based water-reducing agent, 15%-30% of rheology modifier, and 20%-40% of regulator according to the weight fraction. Step 2: Add the sulfonic acid-based water-reducing agent, rheology modifier, and regulator weighed in Step 1 into the compounding container, and then add water into the compounding container; Step 3: Stir the mixture obtained in Step 2 to obtain a ballistic inhibitor.

[0006] Further, the sulfonic acid-based water-reducing agent is polymerized from 40%-41% polyether, 0.05%-0.055% vitamin C, 0.3%-0.35% hydrogen peroxide, 4%-4.2% acrylic acid, 0.5% 2-acrylamide-2-methylpropanesulfonic acid, 0.15%-0.18% mercaptoacetic acid or mercaptopropionic acid, 2.5%-3% sodium hydroxide, and the balance being water. The water-reducing agent prepared in this manner reduces the surface tension of the concrete mixture and increases the repulsive force between cement particles, thereby reducing water consumption while maintaining or increasing the fluidity of the concrete. This makes the concrete easier to pour and finish, especially in complex or densely reinforced structures, effectively filling the formwork and flowing around the reinforcement without adding additional water. It also improves the early and final strength of the concrete. The use of sulfonic acid-based high-efficiency water-reducing agents maintains good workability even while reducing the water content of cement paste. This allows cement particles to interact more closely, increasing the efficiency of the hydration reaction and the quality of the products, thereby enhancing the compressive and flexural strength of concrete. By reducing the water content in the cement paste, it lowers the capillary porosity of the concrete, making it more compact. This increased compactness reduces the permeability of chloride ions, carbon dioxide, and other harmful substances, thus improving the durability and resistance to environmental erosion of the concrete. This water-reducing agent accelerates the hydration reaction, allowing the concrete to reach higher initial strength in a shorter time. This is significant for accelerating construction progress and allowing for earlier formwork removal and loading. The use of this water-reducing agent reduces segregation during concrete pouring and curing, thereby reducing the risk of cracking due to uneven drying shrinkage. This water-reducing agent can reduce carbon dioxide emissions and other environmental impacts by reducing cement usage while achieving the same strength, as cement production is an energy-intensive and carbon-intensive process. The addition of this water-reducing agent further enhances the adaptability of the elastic modifier in concrete and gives it the aforementioned advantages.

[0007] Furthermore, sulfonic acid-based water-reducing agents are acidic.

[0008] Furthermore, the preparation steps of the sulfonic acid-based water-reducing agent are as follows: Step 11, Preparation of the base material: Add 40%-41% by weight of polyether, deionized water and 0.3%-0.35% by weight of hydrogen peroxide solution to the reaction vessel. After stirring evenly, add 0.5% by weight of 2-acrylamide-2-methylpropanesulfonic acid to the solution. Step 12, Preparation of Material A: Add 4%-4.2% by weight of acrylic acid to deionized water and mix evenly by stirring. Step 13, Preparation of Material B: Add 0.05%-0.055% by weight of vitamin C and 0.15%-0.18% by weight of mercaptoacetic acid or mercaptopropionic acid to deionized water and mix evenly by stirring. Step 14: Add material A (10.7% by weight) to the base material obtained in step 11 at a uniform rate for 2.5 hours, and add material B (10% by weight) at a uniform rate for 3 hours. Adjust the pH of the solution to 4 by adding sodium hydroxide (2.5%-3% by weight).

[0009] Furthermore, the rheology modifier is composed of 0.8%-1% xanthan gum and 0.8%-1% polyacrylamide by weight, with the balance being water. This rheology modifier, prepared according to the above composition ratio, significantly improves the bond strength of concrete. In shotcrete, the rheology modifier increases the viscosity and cohesiveness of the mixture, helping the concrete maintain a certain thickness and uniformity when sprayed onto the substrate, thereby improving the bond with the substrate. This is particularly important for shotcrete applications in tunnels, mines, and slope reinforcement, as good bond performance ensures the stability and durability of the structure. Secondly, the high solubility and colloidal properties of the rheology modifier in water improve the flowability of concrete. During shotcrete application, good flowability ensures that the concrete flows smoothly in the pipes and is sprayed evenly through the nozzles, reducing clogging and uneven spraying. Moreover, a certain proportion of material is typically lost during shotcrete construction due to bounce (concrete particles rebounding from the construction surface). The rheology modifier effectively reduces this bounce phenomenon by increasing the viscosity and bond strength of the concrete, improving material utilization and reducing waste. It enhances the stability of concrete mixtures and prevents segregation of moisture and solid components. This is crucial for maintaining the uniformity and continuity of shotcrete, especially during long-distance transport or construction in high-temperature and high-humidity environments. Finally, through these effects, rheology modifiers not only improve the workability of shotcrete but also increase overall construction efficiency and cost-effectiveness by reducing material loss and improving structural performance. Therefore, xanthan gum is a commonly used performance modifier in shotcrete, particularly important in engineering applications requiring high adhesion and stability.

[0010] Furthermore, the rheology modifier is prepared at a temperature of 40°C and obtained by shearing and stirring for 4 to 5 hours.

[0011] Furthermore: The modifier is composed of 20%-40% magnesium fluorosilicate and 20%-40% nano-silica by weight, with the balance being water, and is prepared by stirring and synthesis. The mechanism of action of magnesium fluorosilicate and nano-silica in the elastic modifier is explained in detail. Specifically, magnesium fluorosilicate is used to improve the hardness and wear resistance of concrete surfaces. It reacts with free calcium in concrete to form calcium silicate and calcium fluoride. These compounds can fill the original capillary pores, thereby enhancing the surface structural strength and wear resistance. Magnesium fluorosilicate not only improves the surface wear resistance but also significantly enhances the resistance to chemical erosion, especially in environments with harsh chemicals, such as industrial floors, warehouses, and garages. This improvement makes the concrete surface more resistant to various chemical erosions, extending the service life of the structure. Shotcrete surfaces treated with magnesium fluorosilicate form a smooth and continuous hardened layer, which effectively reduces surface dust generation. This is particularly important in enclosed environments such as underground parking lots or warehouses, helping to maintain environmental cleanliness and reduce maintenance costs. Magnesium fluorosilicate increases the density of concrete by filling its micropores, significantly improving its waterproofing and reducing the penetration of water and other harmful substances. As a surface treatment agent, magnesium fluorosilicate effectively enhances the surface properties of shotcrete, making it particularly suitable for applications requiring increased durability and reduced maintenance. Specifically, nano-silica, with its highly active surface area, reacts with calcium ions in the cement matrix to generate more calcium silicate hydrate (CSH), a major component of hardened concrete. This increased CSH content significantly improves the compressive and flexural strength of concrete. Nano-silica fills the micropores in concrete, reducing the number and size of capillaries, thereby reducing the permeability of water and harmful substances. This property improves the durability of shotcrete, especially in resistance to freeze-thaw cycles, sulfate attack, and chloride ion penetration. Nano-silica increases the fluidity and stability of concrete, contributing to the uniformity and continuity of shotcrete construction and reducing segregation and sedimentation. This is particularly important for shotcrete applications in complex or confined spaces. During the construction of shotcrete, some material bounces back from the construction surface, resulting in material waste. The addition of nano-silica effectively improves the bonding strength and adhesion of concrete, thereby reducing the bounce rate and improving construction efficiency and material utilization. Nano-silica accelerates the cement hydration process, enabling concrete to reach initial strength in a shorter time, which is particularly advantageous for structures requiring rapid demolding or early use.

[0012] Furthermore, the dosage of shotcrete inhibitor in shotcrete is 2%-6%.

[0013] The advantages of the above technical solution are: The shot-throwing ballistic agent prepared by this invention can effectively extend the slump retention time by 4 to 8 hours when mixed into concrete.

[0014] When the shotcrete agent prepared by this invention is mixed with national standard and iron standard quick-setting agent and shotcrete, the shotcrete can provide compressive strength for 8 hours.

[0015] When the shotcrete inhibitor prepared by this invention is mixed with national standard and iron standard quick-setting agent and applied to concrete, the strength of the shotcrete after 8 hours can reach 150%-180% of that of ordinary shotcrete at the same age. The strength after 24 hours can reach 150-220% of that of ordinary shotcrete at the same age, which is conducive to efficient and rapid construction, saves construction time, and has significant economic benefits.

[0016] The shotcrete agent prepared by this invention, when mixed into the shotcrete, can effectively improve the over-pumping rate of the shotcrete, further improve the shotcrete shrinkage rate, and complete the shotcrete operation more efficiently.

[0017] The shotcrete prepared by this invention produces shotcrete with dormant-like properties when mixed into concrete. It can effectively solve the problem of long-term slump retention without the need for accelerator activation, and can also rapidly accelerate setting and increase the strength of the ultra-early 8-hour stage after being activated by national standard and iron standard accelerators.

[0018] Furthermore, this invention achieves the following effects: highly efficient water reduction, with a water reduction rate of 25%-40%; high fluidity and high slump retention, resulting in minimal slump loss over time; significant strengthening effect on hardened concrete, increasing 1-day strength by 80%-100%, with stable strength growth in later stages; good workability of the high-mix concrete, preventing segregation and bleeding, and ensuring good pumpability, resulting in a smooth exterior and solid interior after hardening; chloride-free, low-alkali, and non-corrosive to reinforcing steel; air content adjustable according to project requirements; significantly improved concrete's resistance to freezing, impermeability, carbonation, and shrinkage, greatly extending its service life; broad applicability, adaptable to various cement types; non-toxic, odorless, harmless to humans, and environmentally safe; reduced concrete rebound, with a rebound rate ≤5%; effectively solves pipe blockage problems during shotcrete construction; and the dosage of accelerator can be reduced to 4%-5%. Detailed Implementation

[0019] Example 1 A method for preparing a projectile-resistant propellant, comprising the following steps: Step 1: Weigh out 15% of sulfonic acid-based water-reducing agent, 30% of rheology modifier, and 40% of regulator according to the weight fraction. Step 2: Add the sulfonic acid-based water-reducing agent, rheology modifier and regulator weighed in Step 1 into the compounding container, and inject 15% water into the compounding container; Step 3: Stir the mixture obtained in Step 2 to obtain a ballistic inhibitor.

[0020] The sulfonic acid-based water-reducing agent is polymerized from 40% polyether, 0.055% vitamin C, 0.3% hydrogen peroxide, 4% acrylic acid, 0.5% 2-acrylamide-2-methylpropanesulfonic acid, 0.15% mercaptoacetic acid or mercaptopropionic acid, 3% sodium hydroxide, and the balance being water.

[0021] The preparation steps of sulfonic acid-based water-reducing agents are as follows: Step 11, Preparation of the base material: Add 40% by weight of polyether, 30% by weight of deionized water and 0.3% by weight of hydrogen peroxide solution to the reaction vessel. After stirring evenly, add 0.5% by weight of 2-acrylamide-2-methylpropanesulfonic acid to the solution. Step 12, Preparation of Material A: Add 4% by weight of acrylic acid to deionized water and mix evenly by stirring. Step 13, Preparation of Material B: Add 0.055% by weight of vitamin C and 0.15% by weight of mercaptoacetic acid or mercaptopropionic acid to deionized water and mix them evenly by stirring. Step 14: Add component A (10.7% by weight) to the base material obtained in Step 11 at a uniform rate for 2.5 hours, and add component B (10% by weight) at a uniform rate for 3 hours, and adjust the pH of the solution to 4 using sodium hydroxide (3% by weight).

[0022] The rheology modifier consists of 1% xanthan gum and 1% polyacrylamide by weight, with the balance being water. The rheology modifier is prepared at 40°C and obtained by shearing and stirring for 4 to 5 hours. Specifically, sufficient water is added to a mixing container, and 1% xanthan gum is slowly and evenly added and stirred until homogeneous. The heating device is then turned on, and the temperature is slowly raised to 40°C until the xanthan gum is completely dissolved. After dissolution, 1% polyacrylamide is added, and stirring continues until a melt emulsion is formed.

[0023] The regulator consists of 40% magnesium fluorosilicate and 40% nano silica by weight, with the remainder being water. During preparation, sufficient water is added to the stirring container, and the stirring is started while adding 40% magnesium fluorosilicate and 40% nano silica at a uniform speed. Stirring continues until the solution is clear and free of residual particles.

[0024] The dosage of this shotcrete inhibitor in shotcrete is 4%-6%.

[0025] Example 2 A method for preparing a projectile-resistant propellant, comprising the following steps: Step 1: Weigh out 5% sulfonic acid-based water-reducing agent, 30% rheology modifier, and 40% regulator according to their weight fractions. Step 2: Add the sulfonic acid-based water-reducing agent, rheology modifier and regulator weighed in Step 1 into the compounding container, and inject 25% water into the compounding container; Step 3: Stir the mixture obtained in Step 2 to obtain a ballistic inhibitor.

[0026] The sulfonic acid-based water-reducing agent is polymerized from 40% polyether, 0.055% vitamin C, 0.3% hydrogen peroxide, 4% acrylic acid, 0.5% 2-acrylamide-2-methylpropanesulfonic acid, 0.15% mercaptoacetic acid or mercaptopropionic acid, 3% sodium hydroxide, and the balance being water.

[0027] The preparation steps of sulfonic acid-based water-reducing agents are as follows: Step 11, Preparation of the base material: Add 40% by weight of polyether, 30% by weight of deionized water and 0.3% by weight of hydrogen peroxide solution to the reaction vessel. After stirring evenly, add 0.5% by weight of 2-acrylamide-2-methylpropanesulfonic acid to the solution. Step 12, Preparation of Material A: Add 4% by weight of acrylic acid to deionized water and mix evenly by stirring. Step 13, Preparation of Material B: Add 0.055% by weight of vitamin C and 0.15% by weight of mercaptoacetic acid or mercaptopropionic acid to deionized water and mix them evenly by stirring. Step 14: Add component A (10.7% by weight) to the base material obtained in Step 11 at a uniform rate for 2.5 hours, and add component B (10% by weight) at a uniform rate for 3 hours, and adjust the pH of the solution to 4 using sodium hydroxide (3% by weight).

[0028] The rheology modifier consists of 1% xanthan gum and 1% polyacrylamide by weight, with the balance being water. The rheology modifier is prepared at 40°C and obtained by shearing and stirring for 4 to 5 hours. Specifically, sufficient water is added to a mixing container, and 1% xanthan gum is slowly and evenly added and stirred until homogeneous. The heating device is then turned on, and the temperature is slowly raised to 40°C until the xanthan gum is completely dissolved. After dissolution, 1% polyacrylamide is added, and stirring continues until a melt emulsion is formed.

[0029] The regulator consists of 40% magnesium fluorosilicate and 40% nano silica by weight, with the remainder being water. During preparation, sufficient water is added to the stirring container, and the stirring is started while adding 40% magnesium fluorosilicate and 40% nano silica at a uniform speed. Stirring continues until the solution is clear and free of residual particles.

[0030] The dosage of this shotcrete inhibitor in shotcrete is 4%-6%.

[0031] Example 3 A method for preparing a projectile-resistant propellant, comprising the following steps: Step 1: Weigh out 25% of sulfonic acid-based water-reducing agent, 15% of rheology modifier, and 50% of regulator according to the weight fraction. Step 2: Add the sulfonic acid-based water-reducing agent, rheology modifier and regulator weighed in Step 1 into the compounding container, and inject 10% water into the compounding container; Step 3: Stir the mixture obtained in Step 2 to obtain a ballistic inhibitor.

[0032] The sulfonic acid-based water-reducing agent is polymerized from 40% polyether, 0.055% vitamin C, 0.3% hydrogen peroxide, 4% acrylic acid, 0.5% 2-acrylamide-2-methylpropanesulfonic acid, 0.15% mercaptoacetic acid or mercaptopropionic acid, 3% sodium hydroxide, and the balance being water.

[0033] The preparation steps of sulfonic acid-based water-reducing agents are as follows: Step 11, Preparation of the base material: Add 40% by weight of polyether, 30% by weight of deionized water and 0.3% by weight of hydrogen peroxide solution to the reaction vessel. After stirring evenly, add 0.5% by weight of 2-acrylamide-2-methylpropanesulfonic acid to the solution. Step 12, Preparation of Material A: Add 4% by weight of acrylic acid to deionized water and mix evenly by stirring. Step 13, Preparation of Material B: Add 0.055% by weight of vitamin C and 0.15% by weight of mercaptoacetic acid or mercaptopropionic acid to deionized water and mix them evenly by stirring. Step 14: Add component A (10.7% by weight) to the base material obtained in Step 11 at a uniform rate for 2.5 hours, and add component B (10% by weight) at a uniform rate for 3 hours, and adjust the pH of the solution to 4 using sodium hydroxide (3% by weight).

[0034] The rheology modifier consists of 1% xanthan gum and 1% polyacrylamide by weight, with the balance being water. The rheology modifier is prepared at 40°C and obtained by shearing and stirring for 4 to 5 hours. Specifically, sufficient water is added to a mixing container, and 1% xanthan gum is slowly and evenly added and stirred until homogeneous. The heating device is then turned on, and the temperature is slowly raised to 40°C until the xanthan gum is completely dissolved. After dissolution, 1% polyacrylamide is added, and stirring continues until a melt emulsion is formed.

[0035] The regulator consists of 40% magnesium fluorosilicate and 40% nano silica by weight, with the remainder being water. During preparation, sufficient water is added to the stirring container, and the stirring is started while adding 40% magnesium fluorosilicate and 40% nano silica at a uniform speed. Stirring continues until the solution is clear and free of residual particles.

[0036] The dosage of this shotcrete inhibitor in shotcrete is 2%-3%.

[0037] Example 4 A method for preparing a projectile-resistant propellant, comprising the following steps: Step 1, taking the production of 10 tons as an example, weigh out 2500 kg of sulfonic acid-based water-reducing agent, 1500 kg of rheology modifier, and 5000 kg of regulator. Step 2: Add the sulfonic acid-based water-reducing agent, rheology modifier, and regulator weighed in Step 1 into the compounding container, and inject 1000 kg of water into the compounding container; Step 3: Stir the mixture obtained in Step 2 to obtain a ballistic inhibitor.

[0038] The sulfonic acid-based water-reducing agent is polymerized from 40% polyether, 0.055% vitamin C, 0.3% hydrogen peroxide, 4% acrylic acid, 0.5% 2-acrylamide-2-methylpropanesulfonic acid, 0.15% mercaptoacetic acid or mercaptopropionic acid, 3% sodium hydroxide, and the balance being water.

[0039] The preparation steps of sulfonic acid-based water-reducing agents are as follows: Step 11, Preparation of the base material: Add 40% by weight of polyether, 30% by weight of deionized water and 0.3% by weight of hydrogen peroxide solution to the reaction vessel. After stirring evenly, add 0.5% by weight of 2-acrylamide-2-methylpropanesulfonic acid to the solution. Step 12, Preparation of Material A: Add 4% by weight of acrylic acid to deionized water and mix evenly by stirring. Step 13, Preparation of Material B: Add 0.055% by weight of vitamin C and 0.15% by weight of mercaptoacetic acid or mercaptopropionic acid to deionized water and mix them evenly by stirring. Step 14: Add component A (10.7% by weight) to the base material obtained in Step 11 at a uniform rate for 2.5 hours, and add component B (10% by weight) at a uniform rate for 3 hours, and adjust the pH of the solution to 4 using sodium hydroxide (3% by weight).

[0040] The rheology modifier consists of 1% xanthan gum and 1% polyacrylamide by weight, with the balance being water. The rheology modifier is prepared at 40°C and obtained by shearing and stirring for 4 to 5 hours. Specifically, sufficient water is added to a mixing container, and 1% xanthan gum is slowly and evenly added and stirred until homogeneous. The heating device is then turned on, and the temperature is slowly raised to 40°C until the xanthan gum is completely dissolved. After dissolution, 1% polyacrylamide is added, and stirring continues until a melt emulsion is formed.

[0041] The regulator consists of 40% magnesium fluorosilicate and 40% nano silica by weight, with the remainder being water. During preparation, sufficient water is added to the stirring container, and the stirring is started while adding 40% magnesium fluorosilicate and 40% nano silica at a uniform speed. Stirring continues until the solution is clear and free of residual particles.

[0042] To investigate the effects of different dosages of shotcrete inhibitor on various properties of shotcrete, the following application examples were implemented. To control the influence of variables on the test results, the shotcrete inhibitor was tested using the component ratios shown in Example 3 or Example 4. Since this inhibitor is primarily used in concrete, testing its individual properties is not practically meaningful; therefore, the following application examples were used. These examples, along with corresponding performance tests, highlight the performance characteristics of the inhibitor.

[0043] Application Example 1 A type of shotcrete, comprising 390 kg / m³ 3 Cement, 98kg / m 3 fly ash, 174 kg / m³ 3 Water, 856 kg / m 3 Fine sand, 857 kg / m 3 Coarse aggregate, 4.88 kg / m³ 3 Water-reducing agent, 8kg / m 3 Alkali-free quick-setting agent, 0 kg / m 3 Projectile stunner.

[0044] in, Cement: Meets the technical requirements for PO42.5 grade cement in GB175-2007 "General Portland Cement" standard.

[0045] Fly ash: Grade I low-calcium fly ash is used, which meets the requirements of GBJ-1146 "Technical Specification for Application of Fly Ash in Concrete" and JGJ-28 "Technical Specification for Application of Fly Ash in Concrete and Mortar".

[0046] Water: Drinking water, conforming to JGJ63-2006 "Standard for Water Used in Concrete Mixing".

[0047] Fine sand: Particle size range of 0-4.75mm, conforming to the requirements of JTG / T3650-2020 "Technical Specifications for Construction of Highway Bridges and Culverts".

[0048] Coarse aggregate: Continuously graded stone with a particle size range of 5-10mm, which meets the requirements of JTG / T3650-2020 "Technical Specifications for Construction of Highway Bridges and Culverts".

[0049] Water-reducing agent: High-performance polycarboxylate water-reducing agent is used, and the water reduction rate can reach 25% under a certain dosage.

[0050] Alkali-free quick-setting agent: It shall meet the technical requirements for alkali-free quick-setting agents in GB / T35159-2017 "Quick-setting agents for shotcrete".

[0051] Application Example 2 A type of shotcrete, comprising 390 kg / m³ 3 Cement, 98kg / m 3 fly ash, 174 kg / m³ 3 Water, 856 kg / m 3 Fine sand, 857 kg / m 3 Coarse aggregate, 4.88 kg / m³ 3 It contains water-reducing agent, 8% alkali-free quick-setting agent, and 2% shotcrete agent.

[0052] Application Example 3 A type of shotcrete, comprising 390 kg / m³ 3 Cement, 98kg / m 3 fly ash, 174 kg / m³ 3 Water, 856 kg / m 3 Fine sand, 857 kg / m 3 Coarse aggregate, 4.88 kg / m³ 3 It contains water-reducing agent, 8% alkali-free quick-setting agent, and 4% shotcrete agent.

[0053] Application Example 4 A type of shotcrete, comprising 390 kg / m³ 3Cement, 98kg / m 3 fly ash, 174 kg / m³ 3 Water, 856 kg / m 3 Fine sand, 857 kg / m 3 Coarse aggregate, 4.88 kg / m³ 3 It contains water-reducing agent, 8% alkali-free quick-setting agent, and 6% shotcrete agent.

[0054] Application Example 5 A type of shotcrete, comprising 393 kg / m³ 3 Cement, 69kg / m 3 fly ash, 180kg / m 3 Water, 948kg / m 3 Fine sand, 716kg / m 3 Coarse aggregate, 4.88 kg / m³ 3 It contains water-reducing agent, 8% alkali-free quick-setting agent, and 0% shotcrete agent.

[0055] Application Example 6 A type of shotcrete, comprising 393 kg / m³ 3 Cement, 69kg / m 3 fly ash, 180kg / m 3 Water, 948kg / m 3 Fine sand, 716kg / m 3 Coarse aggregate, 4.88 kg / m³ 3 It contains water-reducing agent, 8% alkali-free quick-setting agent, and 4% shotcrete agent.

[0056] Application Examples 1 to 4 involve indoor shotcrete testing. These examples test concrete prepared with different amounts of shotcrete inhibitor added indoors to verify the effect of varying amounts of shotcrete inhibitor on the concrete. Application Examples 5 and 6 involve field testing of concrete prepared with different amounts of shotcrete inhibitor added to verify the effect of shotcrete inhibitor on the concrete.

[0057] Table 1. Indoor Shotcrete Mix Proportions (kg / m³) 3 ) According to the "Test Procedures for Cement and Cement Concrete in Highway Engineering" (JTG E30-2005), concrete cube specimens were prepared, and standard curing was carried out for a specified age. The splitting tensile and compressive strength values ​​were measured by standard test methods. The compressive strength of shotcrete cubes at different ages is shown in Table 2, and the splitting tensile strength is shown in Table 3.

[0058] Table 2 Compressive strength of cubes at different ages Application Example 1 9.06MPa 22.71MPa 30.74MPa Application Example 2 12.15MPa 26.28MPa 39.16MPa Application Example 3 11.72MPa 24.36MPa 43.22MPa Application Example 4 10.56MPa 21.71MPa 41.10MPa Table 2 shows the experimental results. The purpose of this study is to investigate the effect of different dosages of shotcrete on the compressive strength of concrete cubes at different ages. As can be seen from Table 2, the compressive strength after curing with shotcrete can reach more than 10 MPa after one day. In particular, the strength after 1 day and 7 days is improved when shotcrete is added at dosages of 2% and 4%.

[0059] Table 3. Experimental values ​​of splitting tensile strength Application Example 1 0.60MPa 1.95MPa 3.28MPa Application Example 2 0.61MPa 1.92MPa 3.38MPa Application Example 3 0.89MPa 2.02MPa 3.50MPa Application Example 4 0.87MPa 2.01MPa 3.41MPa Table 3 shows the experimental results, primarily to investigate the effect of different dosages of shotcrete admixture on the splitting tensile strength of cubic concrete after curing to the target age. As can be seen from Table 3, the 1-day splitting tensile strength of concrete with 4% shotcrete admixture increased by nearly 50% compared to ordinary concrete, indicating that the addition of shotcrete admixture is beneficial to the cohesion of the concrete and increases its bond strength. Compared to ordinary concrete, the splitting tensile strength of concrete with shotcrete admixture was increased in all cases.

[0060] Table 4. Tensile Strength of Wedge Splitting Application Example 1 1.07MPa Application Example 3 1.66MPa Table 4 shows that the interfacial bond strength of the group with 4% shotcrete inhibitor increased by about 50% compared with the group without the inhibitor, which is beneficial to the development of the bond strength between concrete and rock.

[0061] Wet shotcrete is produced by spraying concrete onto a rock surface using specialized equipment. Good mixture properties are a prerequisite for successful shotcreting. The workability of shotcrete can be categorized into pumpability and sprayability. Pumpability is determined by the fluidity of the concrete, while sprayability is determined by its viscosity.

[0062] Generally, poured concrete is pumped, filling the entire delivery pipe and flowing uniformly within it. Shotcrete, however, is pumped in a solid-air coexisting state within the pipe, making it prone to losing homogeneity. If the concrete mix proportion is inappropriate, the shotcrete may become excessively viscous and have poor flowability, significantly losing its homogeneity within the pipe. This causes material to deviate along the pipe axis, resulting in coarse aggregate settling at the bottom and ultimately causing pipe blockage, severely impacting construction progress. Improving the flowability of shotcrete is typically achieved by increasing water content and using water-reducing agents. However, increasing water content raises the water-cement ratio, reducing the shotcrete's viscosity and strength, and may cause bleeding and segregation, preventing the cement paste from effectively encapsulating the concrete aggregate and resulting in a higher rebound rate during spraying. Therefore, the performance of the shotcrete mix is ​​primarily aimed at balancing the trade-off between pumpability and sprayability. Currently, the main method for determining the performance of concrete mixtures is by measuring the slump of shotcrete, as the slump index can well reflect the workability and fluidity of shotcrete. The test methods for slump and spread of concrete are specified in JTG E30-2005 "Test Procedures for Cement and Cement Concrete in Highway Engineering".

[0063] Table 5 Test results of concrete mixture properties Application Example 1 215mm 580mm Application Example 2 220mm 586mm Application Example 3 237mm 592mm Application Example 4 261mm 600mm As shown in Table 5, the addition of shotcrete inhibitors can effectively improve the fluidity of shotcrete mixtures and enhance the viscosity of shotcrete, thus achieving a better balance between shotcrete's sprayability and pumpability. This helps reduce the rebound rate of shotcrete, prevents pump pipe blockage during construction, and improves construction efficiency. Shotcrete inhibitors have a significant impact on improving the workability of shotcrete.

[0064] To verify the effect of shotcrete inhibitors on the rebound rate of shotcrete, a 40m thick plastic film was used to cover the ground below the surface to be shotcreted. 2 -50m 2 The area. Mix until it is at least 1m. 3 The concrete mixture is fed into the shotcrete equipment, and testing begins after the spray output stabilizes. The nozzle should be held at a 90° angle to the surface being sprayed. The total spray thickness is 80mm-120mm, applied in two layers, each 40mm-60mm thick. Spraying must be continuous and uninterrupted, and the concrete in the hopper must remain uniform at the beginning and end of the test. After spraying, the rebound material is collected from the plastic film and weighed. The percentage of rebound material to the total sprayed mixture is the rebound rate. The amount sprayed before stabilization should be deducted from the total sprayed mixture.

[0065] Table 6 Results of Shotcrete Rebound Rate Test As shown in the table above, under the premise of the same design strength and construction process, adding 4% of shotcrete inhibitor can effectively reduce the rebound rate of shotcrete in the arch and sidewall parts. The rebound rate of the arch top is reduced from 8.30% to 4.01%, a reduction of about 50%; the rebound rate of the sidewall is reduced from 7.36% to 3.65%, a reduction of about 50%, which effectively reduces the amount of shotcrete rebound on the construction site and saves the waste of engineering materials.

[0066] To verify the effect of shotcrete inhibitors on the dust concentration generated by shotcrete in the field environment, dust concentration tests were conducted.

[0067] Table 7 Dust Concentration Test Results As can be seen from the table above, during the spraying process, the dust concentration of sprayed concrete mixed with 4% shotcrete agent is greatly reduced compared with ordinary shotcrete, which also greatly improves the working environment for tunnel construction workers.

[0068] To verify the effect of shotcrete on the bond strength between shotcrete and rock in the field environment, a shotcrete-rock bond strength test was conducted.

[0069] Table 8 Test values ​​of shotcrete-rock bond strength As shown in the table above, field tests revealed that shotcrete with 4% admixture for shotcreting achieved a bond strength of up to 2.27 MPa, compared to only 0.85 MPa for shotcrete without admixture – a three-fold increase. This improved bond strength ensures the shotcrete adheres firmly to the surface, reducing rebound during construction and mitigating the drawbacks of increased gaps, pores, and defects caused by high rebound rates. It also enhances impermeability, particularly in water-rich tunnel areas, effectively preventing water penetration and improving construction quality and efficiency.

[0070] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Obviously, those skilled in the art can make various modifications and variations to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention also intends to include these modifications and variations.

Claims

1. A method for preparing a projectile-resistant propellant, characterized in that, Including the following steps: Step 1: Weigh out 4%-15% of sulfonic acid-based water-reducing agent, 15%-30% of rheology modifier, and 20%-40% of regulator according to the weight fraction. Step 2: Add the sulfonic acid-based water-reducing agent, rheology modifier, and regulator weighed in Step 1 into the compounding container, and then add water into the compounding container; Step 3: Stir the mixture obtained in Step 2 to obtain a ballistic inhibitor; The sulfonic acid-based water-reducing agent is composed of 40%-41% polyether by weight, 0.05%-0.055% vitamin C by weight, 0.3%-0.35% hydrogen peroxide by weight, 4%-4.2% acrylic acid by weight, 0.5% 2-acrylamide-2-methylpropanesulfonic acid by weight, 0.15%-0.18% mercaptoacetic acid or mercaptopropionic acid by weight, 2.5%-3% sodium hydroxide by weight, and the balance being water, polymerized together. The preparation steps of sulfonic acid-based water-reducing agents are as follows: Step 11, Preparation of the base material: Add 40%-41% by weight of polyether, deionized water and 0.3%-0.35% by weight of hydrogen peroxide solution to the reaction vessel. After stirring evenly, add 0.5% by weight of 2-acrylamide-2-methylpropanesulfonic acid to the solution. Step 12, Preparation of Material A: Add 4%-4.2% by weight of acrylic acid to deionized water and mix evenly by stirring. Step 13, Preparation of Material B: Add 0.05%-0.055% by weight of vitamin C and 0.15%-0.18% by weight of mercaptoacetic acid or mercaptopropionic acid to deionized water and mix evenly by stirring. Step 14: Add material A (10.7% by weight) to the base material obtained in step 11 at a uniform rate for 2.5 hours and add material B (10% by weight) at a uniform rate for 3 hours, and adjust the pH of the solution to 4 by adding sodium hydroxide (2.5%-3% by weight). The rheology modifier consists of xanthan gum (0.8%-1% by weight), polyacrylamide (0.8%-1% by weight), and the balance being water. The regulator is composed of 20%-40% magnesium fluorosilicate and 20%-40% nano-silica by weight, with the balance being water, and is prepared by stirring and synthesis.

2. The method for preparing the projectile-resistant propellant according to claim 1, characterized in that, Sulfonic acid-based water-reducing agents are acidic.

3. The method for preparing the projectile-resistant propellant according to claim 1, characterized in that, The rheology modifier was prepared at a temperature of 40°C and obtained by shearing and stirring for 4 to 5 hours.

4. The method for preparing the projectile-resistant propellant according to claim 1, characterized in that, The dosage of shotcrete inhibitor in shotcrete is 4%-6%.

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