An early high-strength low-rebound spray concrete material and a preparation method thereof

Abstract

The application relates to the technical field of road building materials, in particular to an early high-strength low-rebound shotcrete material and a preparation method thereof. The preparation method comprises the following steps: preparing a modified accelerator; preparing silicon dioxide nanowires; preparing magnetic silicon dioxide nanowires; and preparing the early high-strength low-rebound shotcrete material. In the preparation of the modified accelerator, sodium alginate and sodium carboxymethyl cellulose are added, and the sodium alginate and the sodium carboxymethyl cellulose can synergize with each other when used together. The colloidal network formed by the sodium alginate can wrap and stably disperse the particles of the dispersed phase, and the sodium carboxymethyl cellulose further enhances the viscosity and stability of the dispersion system through the winding and interweaving between the high molecular chains of the sodium carboxymethyl cellulose, so that the concrete material rapidly forms a gel state, the rebound is reduced, and the concrete strength is improved.

Description

Technical Field

[0001] This invention relates to the field of road construction materials technology, specifically to an early-strength, low-rebound shotcrete material and its preparation method. Background Technology

[0002] High-strength, low-rebound shotcrete is a high-performance concrete material developed to meet the needs of special engineering projects. It is especially suitable for rapid construction occasions such as mines, tunnels, underground engineering, and emergency repairs. In order to achieve sufficient strength in a short time so as to quickly support subsequent construction or restore traffic and reduce the construction cycle, high-strength, low-rebound shotcrete generally uses fast-hardening or ultra-fast-hardening cement as the base. Sometimes, mineral admixtures such as silica fume and slag powder are added to adjust the early strength and workability. Accelerators are also added to speed up the setting speed.

[0003] Existing technologies involve adding fluorosilicate-based accelerators to early-strength, low-rebound shotcrete materials to increase the setting speed of the concrete. However, fluorosilicate accelerators may cause the final compressive strength and flexural strength of the concrete to decrease compared to conventional concrete. Concrete using fluorosilicate accelerators often exhibits poor corrosion resistance and impermeability, resulting in a reduction in its long-term strength. Therefore, this invention provides an early-strength, low-rebound shotcrete material and its preparation method to solve the problems existing in the prior art. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide an early-strength, low-rebound shotcrete material and its preparation method.

[0005] A method for preparing early-strength, low-resilience shotcrete material includes the following steps:

[0006] S1: Preparation of modified quick-setting agent

[0007] Fluorosilicic acid was added to a reactor, and aluminum hydroxide was slowly added. The mixture was magnetically stirred to obtain a suspension. Deionized water was heated, aluminum sulfate was added, and then the suspension and sodium aluminate were added. After stirring evenly, the mixture was heated to obtain a reaction solution. Sodium alginate and sodium carboxymethyl cellulose were added to the reaction solution and cooled. Stirring was maintained during the cooling process until the mixture was cooled to room temperature to obtain an accelerator. Nano silica was added to the accelerator and stirred evenly to obtain a modified accelerator.

[0008] S2: Preparation of silica nanowires

[0009] A microemulsion was obtained by mixing deionized water, sodium citrate solution, anhydrous ethanol, 25% ammonia water and 50% polyvinylpyrrolidone alcohol solution. TEOS was added to the microemulsion and the reaction was heated to obtain a white product. The white product was washed with anhydrous ethanol and deionized water and dried to obtain silica nanowires.

[0010] S3: Preparation of magnetic silica nanowires

[0011] Silica nanowires were immersed in deionized water, ultrasonically dispersed, and purged with nitrogen to obtain treated silica nanowires. FeCl3·6H2O and FeSO4·7H2O were mixed and added to deionized water, purged with nitrogen, and then the treated silica nanowires were added. The mixture was heated in a water bath, and ammonia was added during stirring to obtain a final mixture. The final mixture was then kept in a water bath at 65°C for 2 hours. Finally, it was thoroughly washed with water until neutral and dried to obtain magnetic silica nanowires.

[0012] S4: Preparation of early-strength, low-resilience shotcrete materials

[0013] Mix 100 parts by weight of silicate cement, 10-15 parts by weight of fly ash, 15-40 parts by weight of calcium carbonate, 1-1.5 parts by weight of carbon fiber, 4-7 parts by weight of magnetic silica nanowires, 10-15 parts by weight of polycarboxylate superplasticizer, 25-35 parts by weight of modified quick-setting agent and 150-200 parts by weight of mixing water for 30-35 minutes to obtain early high-strength low-resilience shotcrete material.

[0014] Further, step S1, preparing the modified accelerator, includes the following steps:

[0015] S1.1: Add 50 parts by weight of fluorosilicic acid to the reactor, and slowly add 25 parts by weight of aluminum hydroxide. Stir with a magnetic stirrer at 150-200 r / min for 30-35 min to obtain a suspension.

[0016] S1.2: Heat 200 parts by mass of deionized water to 60-65℃, add 84-85 parts by mass of aluminum sulfate while stirring, continue stirring until the aluminum sulfate dissolves, then add 17 parts by mass of suspension and 1.7 parts by mass of sodium aluminate, stir evenly, heat the solution to 80-85℃, keep the temperature for 30-40 minutes to obtain the reaction solution;

[0017] S1.3: Add 1 part by mass of sodium alginate and 2 parts by mass of sodium carboxymethyl cellulose to the reaction solution and place it in a 0-4℃ environment to cool. Keep stirring during the cooling process until it cools to room temperature to obtain the quick-setting agent.

[0018] S1.4: Add 1.5-4.5% by mass of nano-silica to the quick-setting agent, stir evenly, and obtain the modified quick-setting agent.

[0019] Furthermore, in step S1.4, the diameter of the nano-silica is 20-50 nm.

[0020] Further, step S2 prepares silica nanowires, including the following steps:

[0021] S2.1: A microemulsion is obtained by mixing deionized water, sodium citrate solution, anhydrous ethanol, 25% ammonia water and 50% polyvinylpyrrolidone alcohol solution in a volume ratio of 3:1:10:1:100.

[0022] S2.2: Add TEOS to the microemulsion, heat to 40℃, centrifuge at 800-1000 r / min for 10-15 min, react for 4 h, and obtain a white product;

[0023] S2.3: The white product was washed with anhydrous ethanol and deionized water, and then placed in an electric thermostatic drying oven at 60°C for 12 hours to obtain silica nanowires.

[0024] Furthermore, in step S2.2, the volume ratio of microemulsion to TEOS is 4:1.

[0025] Further, step S3 prepares magnetic silica nanowires, including the following steps:

[0026] S3.1: Immerse silica nanowires in deionized water, ultrasonically disperse for 1-1.5 h, and then dry by purging with nitrogen for 30 min to obtain treated silica nanowires;

[0027] S3.2: FeCl3·6H2O and FeSO4·7H2O were mixed and added to 50 parts by mass of deionized water. The mixture was purged with nitrogen for 30 min. Then, the treated silica nanowires were added to the mixture. The mixture was heated to 30°C in a water bath and stirred continuously. During the stirring process, 20% of the total mass of ammonia water was added until the pH of the system reached 12, and the final mixture was obtained.

[0028] S3.3: The final mixture was then kept in a water bath at 65°C for 2 hours, and finally washed thoroughly with water until neutral. It was then dried in a vacuum oven at 60°C for 12 hours to obtain magnetic silica nanowires.

[0029] Furthermore, in step S3.1, the solid-liquid ratio of silica nanowires to deionized water is 1:10.

[0030] Furthermore, in step S3.2, the mass ratio of FeCl3·6H2O to FeSO4·7H2O is 1:5.

[0031] Furthermore, the concentration of ammonia in step S3.2 is 10-25 wt%.

[0032] An early high-strength low-rebound shotcrete material is prepared by any of the above-mentioned methods for preparing early high-strength low-rebound shotcrete materials.

[0033] Compared with the prior art, the present invention has at least the following beneficial effects:

[0034] 1. This invention incorporates sodium alginate and sodium carboxymethyl cellulose into the preparation of a modified quick-setting agent. Sodium alginate can form an irreversible thermal gel when it encounters calcium ions. After being prepared as a quick-setting agent, it can react with calcium in concrete materials to form a stable gel more quickly. Sodium carboxymethyl cellulose can significantly increase the viscosity of the solution, which helps to maintain the uniform distribution of solid particles in the system and prevent sedimentation. When sodium alginate and sodium carboxymethyl cellulose are used together, they can work synergistically. The colloidal network formed by sodium alginate can encapsulate and stabilize the particles of the dispersed phase, while sodium carboxymethyl cellulose, through the entanglement and interweaving between its polymer chains, further enhances the viscosity and stability of the dispersion system, thereby enabling the concrete material to quickly form a gel state, reducing rebound, and improving the strength of the concrete.

[0035] 2. In this invention, magnetic silica nanowires are added during the preparation of concrete. Due to the embedded or surface-modified magnetic particles, the magnetic silica nanowires can fill the cement pores in the concrete material, forming an integral gel material with the cement, thereby improving the density and durability of the concrete material. Furthermore, the magnetic silica nanowires can move, separate, or orient themselves under the action of a magnetic field, thereby controlling the arrangement of the concrete material and improving the strength of the concrete material through crack deflection and plastic deformation, reducing destructive fracture of the concrete material, and thus improving the mechanical properties of the concrete material in a specific direction. Attached Figure Description

[0036] The accompanying drawings, which are incorporated herein and form part of the specification, illustrate embodiments of the present disclosure and, together with the specification, further serve to explain the principles of the present disclosure and enable those skilled in the art to implement and use the present disclosure.

[0037] Figure 1 This is a flowchart illustrating a method for preparing early-strength, low-rebound shotcrete material used in an embodiment of the present invention. Detailed Implementation

[0038] The following detailed description, in conjunction with the accompanying drawings and specific embodiments, describes an early-strength, low-rebound shotcrete material and its preparation method provided by the present invention. It should be noted that, to make the embodiments more detailed, the following embodiments are the best and preferred embodiments; those skilled in the art can also use other alternative methods to implement some known technologies; and the accompanying drawings are only for more specific description of the embodiments and are not intended to specifically limit the present invention.

[0039] Example 1:

[0040] A method for preparing early high-strength, low-rebound shotcrete material, such as Figure 1 As shown, it includes the following steps:

[0041] S1: Preparation of modified quick-setting agent

[0042] S1.1: Add 50 parts by weight of fluorosilicic acid to the reactor, and slowly add 25 parts by weight of aluminum hydroxide. Stir with a magnetic stirrer at 200 r / min for 30 min to obtain a suspension.

[0043] S1.2: Heat 200 parts by mass of deionized water to 60°C, add 84 parts by mass of aluminum sulfate while stirring, continue stirring until the aluminum sulfate dissolves, then add 17 parts by mass of suspension and 1.7 parts by mass of sodium aluminate, stir evenly, heat the solution to 80°C, keep the temperature for 30 minutes to obtain the reaction solution;

[0044] S1.3: Add 1 part by mass of sodium alginate and 2 parts by mass of sodium carboxymethyl cellulose to the reaction solution and place it in a 0°C environment to cool. Keep stirring during the cooling process until it cools to room temperature to obtain the quick-setting agent.

[0045] S1.4: Add 1.5% by mass of nano-silica to the accelerator. The diameter of the nano-silica is 20-50 nm. After stirring evenly, the modified accelerator is obtained.

[0046] S2: Preparation of silica nanowires

[0047] S2.1: A microemulsion is obtained by mixing deionized water, sodium citrate solution, anhydrous ethanol, 25% ammonia water and 50% polyvinylpyrrolidone alcohol solution in a volume ratio of 3:1:10:1:100.

[0048] S2.2: Add TEOS to the microemulsion at a volume ratio of 4:1, heat to 40℃, centrifuge at 1000 r / min for 10 min, and react for 4 h to obtain a white product;

[0049] S2.3: The white product was washed with anhydrous ethanol and deionized water, and then placed in an electric thermostatic drying oven at 60°C for 12 hours to obtain silica nanowires.

[0050] S3: Preparation of magnetic silica nanowires

[0051] S3.1: Immerse silica nanowires in deionized water with a solid-liquid ratio of 1:10, ultrasonically disperse for 1 hour, and then dry by purging with nitrogen for 30 minutes to obtain treated silica nanowires.

[0052] S3.2: FeCl3·6H2O and FeSO4·7H2O were mixed and added to 50 parts by mass of deionized water. The mass ratio of FeCl3·6H2O to FeSO4·7H2O was 1:5. The mixture was purged with nitrogen for 30 min. Then, the treated silica nanowires were added to the mixture. The mixture was heated to 30°C in a water bath and stirred continuously. During the stirring process, 20% of the total mass of ammonia water was added until the pH of the system reached 12. The concentration of ammonia water was 25 wt%. The final mixture was obtained.

[0053] S3.3: The final mixture was then kept in a water bath at 65°C for 2 hours, and finally washed thoroughly with water until neutral. It was then dried in a vacuum oven at 60°C for 12 hours to obtain magnetic silica nanowires.

[0054] S4: Preparation of early-strength, low-resilience shotcrete materials

[0055] 100 parts by weight of silicate cement, 15 parts by weight of fly ash, 40 parts by weight of calcium carbonate, 1.5 parts by weight of carbon fiber, 7 parts by weight of magnetic silica nanowires, 15 parts by weight of polycarboxylate superplasticizer, 35 parts by weight of modified quick-setting agent and 150 parts by weight of mixing water are mixed for 30 minutes to obtain early high-strength low-rebound shotcrete material.

[0056] Example 2:

[0057] A method for preparing early high-strength, low-rebound shotcrete material, such as Figure 1 As shown, it includes the following steps:

[0058] S1: Preparation of modified quick-setting agent

[0059] S1.1: Add 50 parts by weight of fluorosilicic acid to the reactor, and slowly add 25 parts by weight of aluminum hydroxide. Stir with a magnetic stirrer at 200 r / min for 30 min to obtain a suspension.

[0060] S1.2: Heat 200 parts by mass of deionized water to 60°C, add 85 parts by mass of aluminum sulfate while stirring, continue stirring until the aluminum sulfate dissolves, then add 17 parts by mass of suspension and 1.7 parts by mass of sodium aluminate, stir evenly, heat the solution to 80°C, keep the temperature for 30 minutes to obtain the reaction solution;

[0061] S1.3: Add 1 part by mass of sodium alginate and 2 parts by mass of sodium carboxymethyl cellulose to the reaction solution and place it in a 0°C environment to cool. Keep stirring during the cooling process until it cools to room temperature to obtain the quick-setting agent.

[0062] S1.4: Add 4.5% by mass of nano-silica to the quick-setting agent. The diameter of the nano-silica is 20-50 nm. After stirring evenly, the modified quick-setting agent is obtained.

[0063] S2: Preparation of silica nanowires

[0064] S2.1: A microemulsion is obtained by mixing deionized water, sodium citrate solution, anhydrous ethanol, 25% ammonia water and 50% polyvinylpyrrolidone alcohol solution in a volume ratio of 3:1:10:1:100.

[0065] S2.2: Add TEOS to the microemulsion at a volume ratio of 4:1, heat to 40℃, centrifuge at 1000 r / min for 10 min, and react for 4 h to obtain a white product;

[0066] S2.3: The white product was washed with anhydrous ethanol and deionized water, and then placed in an electric thermostatic drying oven at 60°C for 12 hours to obtain silica nanowires.

[0067] S3: Preparation of magnetic silica nanowires

[0068] S3.1: Immerse silica nanowires in deionized water with a solid-liquid ratio of 1:10, ultrasonically disperse for 1 hour, and then dry by purging with nitrogen for 30 minutes to obtain treated silica nanowires.

[0069] S3.2: FeCl3·6H2O and FeSO4·7H2O were mixed and added to 50 parts by mass of deionized water. The mass ratio of FeCl3·6H2O to FeSO4·7H2O was 1:5. The mixture was purged with nitrogen for 30 min. Then, the treated silica nanowires were added to the mixture. The mixture was heated to 30°C in a water bath and stirred continuously. During the stirring process, 20% of the total mass of ammonia water was added until the pH of the system reached 12. The concentration of ammonia water was 10 wt%. The final mixture was obtained.

[0070] S3.3: The final mixture was then kept in a water bath at 65°C for 2 hours, and finally washed thoroughly with water until neutral. It was then dried in a vacuum oven at 60°C for 12 hours to obtain magnetic silica nanowires.

[0071] S4: Preparation of early-strength, low-resilience shotcrete materials

[0072] 100 parts by weight of silicate cement, 10 parts by weight of fly ash, 15 parts by weight of calcium carbonate, 1 part by weight of carbon fiber, 4 parts by weight of magnetic silica nanowires, 10 parts by weight of polycarboxylate superplasticizer, 25 parts by weight of modified quick-setting agent and 200 parts by weight of mixing water are mixed for 30 minutes to obtain early high-strength low-rebound shotcrete material.

[0073] Example 3:

[0074] A method for preparing early high-strength, low-rebound shotcrete material, such as Figure 1 As shown, it includes the following steps:

[0075] S1: Preparation of modified quick-setting agent

[0076] S1.1: Add 50 parts by weight of fluorosilicic acid to the reactor, and slowly add 25 parts by weight of aluminum hydroxide. Stir with a magnetic stirrer at 150 r / min for 35 min to obtain a suspension.

[0077] S1.2: Heat 200 parts by mass of deionized water to 65°C, add 84 parts by mass of aluminum sulfate while stirring, continue stirring until the aluminum sulfate dissolves, then add 17 parts by mass of suspension and 1.7 parts by mass of sodium aluminate, stir evenly, heat the solution to 85°C, keep the temperature for 40 min to obtain the reaction solution;

[0078] S1.3: Add 1 part by mass of sodium alginate and 2 parts by mass of sodium carboxymethyl cellulose to the reaction solution and place it in a 4°C environment to cool. Keep stirring during the cooling process until it cools to room temperature to obtain the quick-setting agent.

[0079] S1.4: Add 1.5% by mass of nano-silica to the accelerator. The diameter of the nano-silica is 20-50 nm. After stirring evenly, the modified accelerator is obtained.

[0080] S2: Preparation of silica nanowires

[0081] S2.1: A microemulsion is obtained by mixing deionized water, sodium citrate solution, anhydrous ethanol, 25% ammonia water and 50% polyvinylpyrrolidone alcohol solution in a volume ratio of 3:1:10:1:100.

[0082] S2.2: Add TEOS to the microemulsion at a volume ratio of 4:1, heat to 40℃, centrifuge at 800 r / min for 15 min, and react for 4 h to obtain a white product;

[0083] S2.3: The white product was washed with anhydrous ethanol and deionized water, and then placed in an electric thermostatic drying oven at 60°C for 12 hours to obtain silica nanowires.

[0084] S3: Preparation of magnetic silica nanowires

[0085] S3.1: Immerse silica nanowires in deionized water with a solid-liquid ratio of 1:10, ultrasonically disperse for 1.5 h, and then dry by purging with nitrogen for 30 min to obtain treated silica nanowires.

[0086] S3.2: FeCl3·6H2O and FeSO4·7H2O were mixed and added to 50 parts by mass of deionized water. The mass ratio of FeCl3·6H2O to FeSO4·7H2O was 1:5. The mixture was purged with nitrogen for 30 min. Then, the treated silica nanowires were added to the mixture. The mixture was heated to 30°C in a water bath and stirred continuously. During the stirring process, 20% of the total mass of ammonia water was added until the pH of the system reached 12. The concentration of ammonia water was 25 wt%. The final mixture was obtained.

[0087] S3.3: The final mixture was then kept in a water bath at 65°C for 2 hours, and finally washed thoroughly with water until neutral. It was then dried in a vacuum oven at 60°C for 12 hours to obtain magnetic silica nanowires.

[0088] S4: Preparation of early-strength, low-resilience shotcrete materials

[0089] 100 parts by weight of silicate cement, 15 parts by weight of fly ash, 40 parts by weight of calcium carbonate, 1.5 parts by weight of carbon fiber, 7 parts by weight of magnetic silica nanowires, 15 parts by weight of polycarboxylate superplasticizer, 35 parts by weight of modified quick-setting agent and 150 parts by weight of mixing water are mixed for 35 minutes to obtain early high-strength low-rebound shotcrete material.

[0090] Comparative Example 1:

[0091] Compared with Example 1, the difference of Comparative Example 1 is that sodium alginate is not added in step S1. Specifically, "S1.1: Take 50 parts by mass of fluorosilicic acid and add it to the reactor, and slowly add 25 parts by mass of aluminum hydroxide. Stir with a magnetic stirrer at 200 r / min for 30 min to obtain a suspension."

[0092] S1.2: Heat 200 parts by mass of deionized water to 60°C, add 84 parts by mass of aluminum sulfate while stirring, continue stirring until the aluminum sulfate dissolves, then add 17 parts by mass of suspension and 1.7 parts by mass of sodium aluminate, stir evenly, heat the solution to 80°C, keep the temperature for 30 minutes to obtain the reaction solution;

[0093] S1.3: Add 3 parts by mass of sodium carboxymethyl cellulose to the reaction solution and place it in a 0°C environment to cool. Keep stirring during the cooling process until it cools to room temperature to obtain the quick-setting agent.

[0094] S1.4: Add 1.5% by mass of nano-silica to the quick-setting agent. The diameter of the nano-silica is 20-50 nm. After stirring evenly, a modified quick-setting agent is obtained. The prepared early high-strength low-rebound shotcrete material is referred to as Comparative Example 1.

[0095] Comparative Example 2:

[0096] Compared with Example 1, the difference of Comparative Example 2 is that sodium carboxymethyl cellulose is not added in step S1. Specifically: "S1.1: Take 50 parts by mass of fluorosilicic acid and add it to the reactor, and slowly add 25 parts by mass of aluminum hydroxide. Stir with a magnetic stirrer at 200 r / min for 30 min to obtain a suspension.

[0097] S1.2: Heat 200 parts by mass of deionized water to 60°C, add 84 parts by mass of aluminum sulfate while stirring, continue stirring until the aluminum sulfate dissolves, then add 17 parts by mass of suspension and 1.7 parts by mass of sodium aluminate, stir evenly, heat the solution to 80°C, keep the temperature for 30 minutes to obtain the reaction solution;

[0098] S1.3: Add 3 parts by mass of sodium alginate to the reaction solution and place it in a 0°C environment to cool. Keep stirring during the cooling process until it cools to room temperature to obtain the quick-setting agent.

[0099] S1.4: Add 1.5% by mass of nano-silica to the accelerator. The diameter of the nano-silica is 20-50 nm. After stirring evenly, a modified accelerator is obtained. The prepared early high-strength low-rebound shotcrete material is designated as Comparative Example 2.

[0100] Comparative Example 3:

[0101] Compared with Example 1, the difference of Comparative Example 3 is that sodium alginate and sodium carboxymethyl cellulose are not added. Specifically: "S1.1: Take 50 parts by weight of fluorosilicic acid and add it to the reactor, and slowly add 25 parts by weight of aluminum hydroxide. Stir with a magnetic stirrer at 200 r / min for 30 min to obtain a suspension.

[0102] S1.2: Heat 200 parts by mass of deionized water to 60°C, add 84 parts by mass of aluminum sulfate while stirring, continue stirring until the aluminum sulfate dissolves, then add 17 parts by mass of suspension and 1.7 parts by mass of sodium aluminate, stir evenly, heat the solution to 80°C, keep the temperature for 30 minutes to obtain the reaction solution;

[0103] S1.3: Place the reaction solution in a 0°C environment to cool, and keep stirring during the cooling process until it cools to room temperature to obtain the quick-setting agent;

[0104] S1.4: Add 1.5% by mass of nano-silica to the quick-setting agent. The diameter of the nano-silica is 20-50nm. After stirring evenly, a modified quick-setting agent is obtained. The prepared early high-strength low-rebound shotcrete material is designated as Comparative Example 3.

[0105] Comparative Example 4:

[0106] Compared with Example 1, Comparative Example 4 differs in that magnetic silica nanowires are not added in step S4. Specifically, "S4: Preparation of early high-strength low-resilience shotcrete material"

[0107] 100 parts by weight of silicate cement, 15 parts by weight of fly ash, 40 parts by weight of calcium carbonate, 1.5 parts by weight of carbon fiber, 15 parts by weight of polycarboxylate superplasticizer, 35 parts by weight of modified quick-setting agent and 150 parts by weight of mixing water were mixed for 30 minutes to obtain early high-strength low-rebound shotcrete material. The prepared early high-strength low-rebound shotcrete material is referred to as Comparative Example 4.

[0108] The compressive strength values ​​of Examples 1-3 and Comparative Examples 1-4 were measured using standard test methods as specified in JTGE30-2005.

[0109] Table 1

[0110]

[0111] The compressive strengths of Examples 1-3 were 43.45 MPa, 42.98 MPa and 43.18 MPa, respectively. Among them, the compressive strength of Example 1 was the highest among all samples, and the slump of Example 1 was 20 mm, which was also the lowest among all samples. It can be seen that Example 1 is the optimal formulation.

[0112] The compressive strength of Comparative Example 1 was 33.61 MPa, that of Comparative Example 2 was 32.29 MPa, and that of Comparative Example 3 was 26.74 MPa. It can be seen that both sodium alginate and sodium carboxymethyl cellulose can enhance the viscosity and stability of the dispersion system, thereby enabling concrete materials to quickly form a gel state, reducing rebound, and improving the strength of concrete. Moreover, the effect is further enhanced when the two are used together compared with using them alone.

[0113] The compressive strength of Comparative Example 4 was 27.67 MPa. It can be seen that the addition of magnetic silica nanowires improved the mechanical properties of concrete materials in a specific direction, thereby increasing the compressive strength of concrete materials.

[0114] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A method of producing an early high strength low rebound shotcrete material, characterized in that, Includes the following steps: S1: Preparation of modified quick-setting agent S1.1: Add 50 parts by weight of fluorosilicic acid to the reactor, and slowly add 25 parts by weight of aluminum hydroxide. Stir with a magnetic stirrer at 150-200 r / min for 30-35 min to obtain a suspension. S1.2: Heat 200 parts by mass of deionized water to 60-65℃, add 84-85 parts by mass of aluminum sulfate while stirring, continue stirring until the aluminum sulfate dissolves, then add 17 parts by mass of suspension and 1.7 parts by mass of sodium aluminate, stir evenly, heat the solution to 80-85℃, keep the temperature for 30-40 minutes to obtain the reaction solution; S1.3: Add 1 part by mass of sodium alginate and 2 parts by mass of sodium carboxymethyl cellulose to the reaction solution and place it in a 0-4℃ environment to cool. Keep stirring during the cooling process until it cools to room temperature to obtain the quick-setting agent. S1.4: Add 1.5-4.5% by mass of nano-silica to the quick-setting agent, stir evenly, and obtain the modified quick-setting agent; S2: Preparation of silica nanowires A microemulsion was obtained by mixing deionized water, sodium citrate solution, anhydrous ethanol, 25% ammonia water and 50% polyvinylpyrrolidone alcohol solution. TEOS was added to the microemulsion and the reaction was heated to obtain a white product. The white product was washed with anhydrous ethanol and deionized water and dried to obtain silica nanowires. S3: Preparation of magnetic silica nanowires Silica nanowires were immersed in deionized water, ultrasonically dispersed, and purged with nitrogen to obtain treated silica nanowires. FeCl3·6H2O and FeSO4·7H2O were mixed and added to deionized water, purged with nitrogen, and then the treated silica nanowires were added. The mixture was heated in a water bath, and ammonia was added during stirring to obtain a final mixture. The final mixture was then kept in a water bath at 65°C for 2 hours. Finally, it was thoroughly washed with water until neutral and dried to obtain magnetic silica nanowires. S4: Preparation of early-strength, low-resilience shotcrete materials Mix 100 parts by weight of silicate cement, 10-15 parts by weight of fly ash, 15-40 parts by weight of calcium carbonate, 1-1.5 parts by weight of carbon fiber, 4-7 parts by weight of magnetic silica nanowires, 10-15 parts by weight of polycarboxylate superplasticizer, 25-35 parts by weight of modified quick-setting agent and 150-200 parts by weight of mixing water for 30-35 minutes to obtain early high-strength low-resilience shotcrete material.

2. The method for preparing early-strength, low-resilience shotcrete material according to claim 1, characterized in that, In step S1.4, the diameter of the nano-silica is 20-50 nm.

3. The method for preparing an early-strength, low-rebound shotcrete material according to claim 2, characterized in that, Step S2, which involves the preparation of silica nanowires, includes the following steps: S2.1: Mix deionized water, sodium citrate solution, anhydrous ethanol, 25% ammonia water and 50% polyvinylpyrrolidone alcohol solution in a volume ratio of 3:1:10:1:100 to obtain a microemulsion; S2.2: Add TEOS to the microemulsion, heat to 40℃, centrifuge at 800-1000 r / min for 10-15 min, react for 4 h, and obtain a white product; S2.3: The white product was washed with anhydrous ethanol and deionized water, and then placed in an electric thermostatic drying oven at 60°C for 12 hours to obtain silica nanowires.

4. A method of producing an early high strength low rebound shotcrete material according to claim 3, characterized in that, In step S2.2, the volume ratio of microemulsion to TEOS is 4:

1.

5. The method for preparing an early-strength, low-resilience shotcrete material according to claim 4, characterized in that, Step S3 involves preparing magnetic silica nanowires, including the following steps: S3.1: Immerse silica nanowires in deionized water, ultrasonically disperse for 1-1.5 h, and then dry by purging with nitrogen for 30 min to obtain treated silica nanowires; S3.2: FeCl3·6H2O and FeSO4·7H2O were mixed and added to 50 parts by mass of deionized water. The mixture was purged with nitrogen for 30 min. Then, the treated silica nanowires were added to the mixture. The mixture was heated to 30°C in a water bath and stirred continuously. During the stirring process, 20% of the total mass of ammonia was added until the pH of the system reached 12, and the final mixture was obtained. S3.3: The final mixture was then kept in a water bath at 65°C for 2 hours, and finally washed thoroughly with water until neutral. It was then dried in a vacuum oven at 60°C for 12 hours to obtain magnetic silica nanowires.

6. A method of producing an early high strength low rebound shotcrete material according to claim 5, characterized in that, In step S3.1, the solid-liquid ratio of silica nanowires to deionized water is 1:

10.

7. A method of producing an early high strength low rebound shotcrete material according to claim 6, characterized in that, In step S3.2, the mass ratio of FeCl3·6H2O to FeSO4·7H2O is 1:

5.

8. A method of producing an early high strength low rebound shotcrete material according to claim 7, characterized in that, The concentration of ammonia in step S3.2 is 10-25 wt%.

9. An early high-strength low-rebound shotcrete material, which is prepared by the preparation method of the early high-strength low-rebound shotcrete material according to any one of claims 1-8.

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