Nano-aramid crystal-gel modified polymer and tunnel bolt spraying support system

Abstract

The present invention relates to the field of building materials technology, specifically a nano-aramid cryogel-modified polymer and a tunnel anchor spraying support system. The polymer comprises the following components, by mass percentage: 3.0-8.5% pretreated nano-aramid fibers; 0.5-2.5% functionalized carbon nanotubes; 0.5-2.5% silk fibroin nanofibers; 4.0-10.0% nano-metal oxide / SiO2 mixed dispersion; 65.0-85.0% polymer matrix; 0.8-1.8% bio-based plasticizer; 0.5-6.0% intelligent self-healing microcapsules; and 0.1-0.5% amphiphilic block copolymer dispersant. By introducing multiple nanomaterials and functional additives, the present invention significantly improves the mechanical properties, durability, and self-healing ability of shotcrete.

Description

Technical Field

[0001] The invention relates to the technical field of building materials, in particular to a nano-aramid crystal-gel modified polymer and a tunnel anchor spraying support system. Background Art

[0002] Anchor-shotcrete support is a commonly used method in tunnel construction. Traditional shotcrete support systems suffer from insufficient strength, poor durability, and weak crack resistance. Especially in complex geological environments and harsh construction conditions, they are prone to cracking and spalling, impacting tunnel safety and service life. Therefore, developing a high-performance concrete additive to improve the mechanical properties and durability of shotcrete is of great practical significance.

[0003] However, there are many technical bottlenecks in the practical application of traditional shotcrete, which restricts its further development and application. The main problems are as follows:

[0004] After shotcrete construction is completed, it must quickly reach a certain strength to fully function as a support structure. This is especially true in tunnel and slope projects. Insufficient early strength can lead to increased deformation of the surrounding rock or matrix, and even cause safety accidents. Traditional shotcrete, due to the limited hydration reaction rate of the cementitious material, develops slowly at an early stage. The three-day compressive strength typically only reaches 50-60% of the design strength, resulting in delayed support structure bearing capacity and difficulty meeting the demands of rapid construction and immediate support.

[0005] During construction, shotcrete is susceptible to factors such as matrix deformation and external impact, making it prone to cracking. Traditional shotcrete has poor toughness and crack resistance, and concrete structures are prone to developing microcracks ranging from 50-300μm during construction. These cracks are difficult to repair on their own, affecting not only the integrity of the structure but also potentially leading to leakage, steel corrosion, and other issues, reducing the durability of the project.

[0006] Conventional early strength agents (such as calcium chloride) used in shotcrete introduce corrosive chloride ions, leading to steel corrosion and structural degradation, and more likely to reduce the durability of the project. Therefore, traditional shotcrete cannot meet the requirements of modern projects for high performance, rapid construction, and high durability. Summary of the Invention

[0007] In response to the shortcomings of the existing technology, the present invention provides a nano-aramid crystal-modified polymer and a tunnel anchor spraying support system, which significantly improves the mechanical properties, durability and self-repair ability of shotcrete by introducing a variety of nanomaterials and functional additives.

[0008] According to a first aspect of the present invention, there is provided a nano-aramid cryogel-modified polymer comprising the following components by mass percentage:

[0009] Pretreated nano-aramid fiber 3.0-8.5%;

[0010] Functionalized carbon nanotubes (f-CNTs) 0.5-2.5%;

[0011] Silk fibroin nanofiber (CNF) 0.5-2.5%;

[0012] Nano metal oxide / SiO2 mixed dispersion 4.0-10.0%;

[0013] Polymer matrix 65.0-85.0%;

[0014] Bio-based plasticizer 0.8-1.8%;

[0015] Intelligent self-repairing microcapsules 0.5-6.0%;

[0016] Amphiphilic block copolymer dispersant 0.1-0.5%.

[0017] According to an embodiment of the present invention, the pretreated nano-aramid fiber has a diameter of 50-80 nm and an aspect ratio of 2000-5000. It is plasma-grafted with carboxyl groups (-COOH) and modified with a silane coupling agent KH-550, with a grafting rate of 1.2-3.5 mol%. This pretreatment method can significantly improve the interfacial compatibility between the nano-aramid fiber and the polymer matrix and enhance the mechanical properties of the composite material.

[0018] According to an embodiment of the present invention, the functionalized carbon nanotubes (f-CNTs) are multi-walled carbon nanotubes with an outer diameter of 8-15 nm and a length of 10-30 μm, and the surface grafted polyethylene glycol (PEG) has a molecular weight of 2000-5000 and a grafting density of 0.8-1.6 per nm. 2 The grafting of polyethylene glycol can improve the dispersibility of carbon nanotubes, while giving them good flexibility and preventing them from agglomerating in the polymer matrix.

[0019] According to an embodiment of the present invention, the silk fibroin nanofibers (CNFs) are TEMPO-oxidized silk fibroin nanofibers with a diameter of 5-20 nm, a length of 1-3 μm, and a carboxyl content of 0.8-1.5 mmol / g. These fibers have excellent mechanical properties and biocompatibility, significantly improving the toughness and impact resistance of composite materials.

[0020] According to an embodiment of the present invention, the nano-metal oxide / SiO2 mixed dispersion comprises a TiO2@SiO2 core-shell structured nanoparticle to ordinary nano-SiO2 in a mass ratio of 1.5:1-2.5:1, wherein the TiO2 core particle size is 10-20 nm and the SiO2 shell thickness is 2-5 nm. This core-shell structured nanoparticle can effectively improve the optical properties and weather resistance of the composite material.

[0021] This invention achieves a 35-50% increase in three-day strength through the synergistic reinforcement effect of nano-aramid fibers and TiO2@SiO2 core-shell particles, effectively addressing the issue of support timeliness. After plasma grafting of carboxyl groups onto nano-aramid fibers (50-80nm in diameter), the interfacial bonding energy with the PVA / PAA matrix increases by 2.3 times. f-CNTs (8-15nm) and silk fibroin nanofibers form a "fiber-tubular" interlocking structure, creating a bridging effect as cracks expand. TiO2@SiO2 core-shell particles (10-20nm in core) act as nucleation sites during cement hydration, accelerating CSH gel formation.

[0022] According to an embodiment of the present invention, the polymer matrix is ​​a blend of polyvinyl alcohol (PVA) and polyacrylic acid (PAA), wherein the PVA has a degree of polymerization of 1700-2400, a degree of alcoholysis of 88-99%, the PAA has a molecular weight of 80,000-150,000, and a mass ratio of PVA to PAA of 6:4-8:2. This blend exhibits excellent film-forming and mechanical properties, and can form a uniform composite structure with nanomaterials.

[0023] According to an embodiment of the present invention, the bio-based plasticizer is a cardanol-based epoxy plasticizer with an epoxy value of 0.25-0.45 eq / 100g and a viscosity (at 25°C) of 800-1500 mPa·s. The use of bio-based plasticizers not only improves the flexibility of composite materials but also reduces environmental impact.

[0024] According to an embodiment of the present invention, the intelligent self-healing microcapsules have a double-shell structure of melamine resin and polyurethane. The outer melamine resin layer is 0.5-1.0 μm thick, and the inner polyurethane layer is 0.2-0.5 μm thick. The core material is a mixture of epoxy resin E-51 and microencapsulated dicyandiamide curing agent in a mass ratio of 100:8-100:12. The microcapsules have a particle size of 20-50 μm and an encapsulation efficiency of 90% or higher. These microcapsules can release the curing agent when the material is damaged, achieving self-healing function.

[0025] The invention utilizes a melamine resin shell (0.5-1.0 μm) that provides tolerance to alkaline environments (pH > 14 stability), a polyurethane inner layer (0.2-0.5 μm) that ensures controlled rupture in the event of mechanical damage, and microencapsulated dicyandiamide curing agent (particle size 2-5 μm) combined with epoxy resin E-51 to form a latent curing system. The innovative double-shell microcapsules precisely release the epoxy resin / curing agent system upon crack propagation, achieving >85% mechanical property recovery within 48 hours, far exceeding the 60% repair rate of traditional materials.

[0026] According to an embodiment of the present invention, the amphiphilic block copolymer dispersant is of the PEO-PPO-PEO type, has a molecular weight of 8000-15000, and a PEO content of 60-80 wt %. This dispersant can effectively disperse the nanomaterial, prevent its agglomeration, and improve the uniformity and stability of the composite material.

[0027] The epoxy groups of the cardanol-based plasticizer undergo a ring-opening reaction with the hydroxyl groups of PVA. The PEO-PPO-PEO dispersant adsorbs nanomaterials and polymer matrices respectively through a block structure. The KH-550 silane coupling agent forms a Si-O-Si cross-linked network on the surface of the nano-aramid fiber. In addition, a three-dimensional barrier network is constructed through silk fibroin nanofibers and f-CNTs, which reduces the chloride ion permeability coefficient by 60-80% and increases the service life by more than 3 times.

[0028] According to a second aspect of the present invention, a tunnel bolt spraying support system is provided, which uses the nano-aramid crystal-modified polymer as a sprayed concrete additive with an admixture amount of 1.0-3.0wt%, and is processed using a microwave-infrared synergistic process.

[0029] According to an embodiment of the present invention, a microwave-infrared collaborative process is used, including:

[0030] Microwave stage: frequency 2.45GHz, power density 1.0-2.5kW / m 3 , duration 1.0-2.5h;

[0031] Infrared stage: wavelength 3-5μm, temperature 60-85℃, relative humidity 60-80%, duration 4.0-8.0h.

[0032] According to an embodiment of the present invention, the sprayed concrete further comprises 0.05-0.15% of a retarder sodium gluconate and 0.01-0.03% of an air entraining agent sodium lauryl sulfate;

[0033] When concrete is damaged by microcracks of 0.1-0.3 mm, the self-repair efficiency of the intelligent self-repairing microcapsules is ≥85% within 48 hours, and the compressive strength recovery rate after 28 days of repair is ≥90%.

[0034] According to an embodiment of the present invention, the TiO2@SiO2 core-shell structure nanoparticles impart photocatalytic properties to the concrete surface. Under standard light conditions (AM1.5, 100mW / cm 2 ) under the following conditions: the degradation efficiency of NOx is ≥70%, and the degradation efficiency of methyl orange is ≥65%;

[0035] The nano-aramid crystal gel modified polymer increases the 3d compressive strength of concrete by 35-50%, increases the 28d flexural strength by 25-40%, and reduces the chloride ion permeability coefficient by 60-80%.

[0036] According to an embodiment of the present invention, the working performance of the shotcrete meets the following requirements: slump 160-200 mm, expansion 450-550 mm, initial setting time 3-5 h, and final setting time 6-8 h;

[0037] The support system can be normally constructed in an environment with a temperature of -20°C to 60°C and a relative humidity of 30-95%.

[0038] The addition of nano-aramid fibers, functionalized carbon nanotubes, and silk fibroin nanofibers to the present invention significantly improves the compressive strength, tensile strength, and impact resistance of shotcrete. Experiments have shown that the compressive strength of shotcrete modified with nano-aramid cryogel polymers can be increased by 30%-50%, the tensile strength by 20%-30%, and the impact resistance by 40%-60%.

[0039] The use of a nano-metal oxide / SiO2 mixed dispersion and a bio-based plasticizer in this invention improves the weather resistance, chemical resistance, and freeze-thaw resistance of shotcrete. The TiO2@SiO2 core-shell nanoparticles effectively block ultraviolet rays, reducing material degradation; the bio-based plasticizer improves the material's flexibility and prevents cracking caused by shrinkage.

[0040] The addition of intelligent self-healing microcapsules in this invention gives shotcrete self-healing capabilities. When the material is damaged by microcracks, the microcapsules rupture and release the curing agent, which reacts with the epoxy resin to form a new polymer network, repairing the cracks and extending the service life of the material.

[0041] The microwave-infrared synergistic process used in this invention to treat shotcrete accelerates the concrete's hydration reaction, shortens curing time, and improves early strength. Furthermore, the addition of retarders and air-entraining agents improves the concrete's workability and impermeability, reducing segregation and bleeding during construction.

[0042] The bio-based plasticizer and silk fibroin nanofiber used in the present invention are both renewable resources, conform to the development trend of green building materials, and reduce pollution to the environment. DETAILED DESCRIPTION

[0043] The embodiment of the present application adopts a nano-aramid crystal-modified polymer and a tunnel anchor spraying support system.

[0044] Example 1

[0045] Components and mass percentage:

[0046] Pretreated nano-aramid fiber: 3.0%

[0047] Functionalized carbon nanotubes: 2.5%

[0048] Silk fibroin nanofibers: 2.5%

[0049] Nano metal oxide / SiO2 mixed dispersion: 4.0%

[0050] Polymer matrix: 85.0%

[0051] Bio-based plasticizer: 1.8%

[0052] Smart self-repairing microcapsules: 0.5%

[0053] Amphiphilic block copolymer dispersant: 0.1%

[0054] Example 2

[0055] Components and mass percentage:

[0056] Pretreated nano-aramid fiber: 8.5%

[0057] Functionalized carbon nanotubes: 0.5%

[0058] Silk fibroin nanofiber: 0.5%

[0059] Nano metal oxide / SiO2 mixed dispersion: 10.0%

[0060] Polymer matrix: 65.0%

[0061] Bio-based plasticizer: 0.8%

[0062] Smart self-repairing microcapsules: 6.0%

[0063] Amphiphilic block copolymer dispersant: 0.5%

[0064] Example 3

[0065] Components and mass percentage:

[0066] Pretreated nano-aramid fiber: 5.0%

[0067] Functionalized carbon nanotubes: 1.5%

[0068] Silk fibroin nanofiber: 1.5%

[0069] Nano metal oxide / SiO2 mixed dispersion: 7.0%

[0070] Polymer matrix: 75.0%

[0071] Bio-based plasticizer: 1.2%

[0072] Smart self-repairing microcapsules: 3.5%

[0073] Amphiphilic block copolymer dispersant: 0.3%

[0074] Example 4

[0075] Components and mass percentage:

[0076] Pretreated nano-aramid fiber: 6.0%

[0077] Functionalized carbon nanotubes: 1.0%

[0078] Silk fibroin nanofiber: 2.0%

[0079] Nano metal oxide / SiO2 mixed dispersion: 8.0%

[0080] Polymer matrix: 72.0%

[0081] Bio-based plasticizer: 1.0%

[0082] Smart self-repairing microcapsules: 4.0%

[0083] Amphiphilic block copolymer dispersant: 0.4%

[0084] Example 5

[0085] Components and mass percentage:

[0086] Pretreated nano-aramid fiber: 7.0%

[0087] Functionalized carbon nanotubes: 2.0%

[0088] Silk fibroin nanofiber: 1.0%

[0089] Nano metal oxide / SiO2 mixed dispersion: 9.0%

[0090] Polymer matrix: 70.0%

[0091] Bio-based plasticizer: 1.5%

[0092] Smart self-repairing microcapsules: 5.0%

[0093] Amphiphilic block copolymer dispersant: 0.2%

[0094] Example 6

[0095] Components and mass percentage:

[0096] Pretreated nano-aramid fiber: 4.0%

[0097] Functionalized carbon nanotubes: 1.8%

[0098] Silk fibroin nanofibers: 1.2%

[0099] Nano metal oxide / SiO2 mixed dispersion: 6.0%

[0100] Polymer matrix: 78.0%

[0101] Bio-based plasticizer: 1.4%

[0102] Smart self-repairing microcapsules: 4.5%

[0103] Amphiphilic block copolymer dispersant: 0.3%

[0104] Comparative Example 1

[0105] Components and mass percentage (smart self-repairing microcapsules missing):

[0106] Pretreated nano-aramid fiber: 5.0%

[0107] Functionalized carbon nanotubes: 1.5%

[0108] Silk fibroin nanofiber: 1.5%

[0109] Nano metal oxide / SiO2 mixed dispersion: 7.0%

[0110] Polymer matrix: 75.0%

[0111] Bio-based plasticizer: 1.2%

[0112] Amphiphilic block copolymer dispersant: 0.3%

[0113] Comparative Example 2

[0114] Components and mass percentage (lacking functionalized carbon nanotubes):

[0115] Pretreated nano-aramid fiber: 5.0%

[0116] Silk fibroin nanofiber: 1.5%

[0117] Nano metal oxide / SiO2 mixed dispersion: 7.0%

[0118] Polymer matrix: 75.0%

[0119] Bio-based plasticizer: 1.2%

[0120] Smart self-repairing microcapsules: 3.5%

[0121] Amphiphilic block copolymer dispersant: 0.3%

[0122] Comparative Example 3

[0123] Components and mass percentage (using ordinary nano-SiO2 instead of TiO2@SiO2 core-shell structure nanoparticles):

[0124] Pretreated nano-aramid fiber: 5.0%

[0125] Functionalized carbon nanotubes: 1.5%

[0126] Silk fibroin nanofiber: 1.5%

[0127] Nano metal oxide / ordinary nano SiO2 mixed dispersion: 7.0%

[0128] Polymer matrix: 75.0%

[0129] Bio-based plasticizer: 1.2%

[0130] Smart self-repairing microcapsules: 3.5%

[0131] Amphiphilic block copolymer dispersant: 0.3%

[0132] Comparative Example 4

[0133] Components and mass percentage (without adding bio-based plasticizer):

[0134] Pretreated nano-aramid fiber: 5.0%

[0135] Functionalized carbon nanotubes: 1.5%

[0136] Silk fibroin nanofiber: 1.5%

[0137] Nano metal oxide / SiO2 mixed dispersion: 7.0%

[0138] Polymer matrix: 76.2%

[0139] Smart self-repairing microcapsules: 3.5%

[0140] Amphiphilic block copolymer dispersant: 0.3%

[0141] Experimental example:

[0142] In order to verify the performance of the nano-aramid cryogel-modified polymers of the above examples and comparative examples in the tunnel bolt-spray support system, a systematic test was conducted. The following is a detailed test process and results.

[0143] According to the formulations of the various examples and comparative examples, nano-aramid fibers, functionalized carbon nanotubes, silk fibroin nanofibers, a nano-metal oxide / SiO2 mixed dispersion, a polymer matrix, a bio-based plasticizer, smart self-healing microcapsules, and an amphiphilic block copolymer dispersant were mixed in appropriate proportions. The mixture was added to C30 shotcrete, stirred thoroughly, and then molded into standard test specimens (150 mm × 150 mm × 150 mm cubes).

[0144] Microwave-infrared synergistic process: microwave stage (frequency 2.45 GHz, power density 1.5 kW / m 3 , duration 2h), infrared stage (wavelength 3-5μm, temperature 75℃, relative humidity 70%, duration 6h).

[0145] 1. Mechanical properties test:

[0146] Compressive strength: Use a universal material testing machine to measure the compressive strength at 3 days and 28 days under standard curing conditions (20±2℃, relative humidity above 95%).

[0147] Flexural strength: Also under standard curing conditions, measure the flexural strength at 28 days.

[0148] Tensile strength: The splitting tensile test method was used to determine the tensile strength at 28 days.

[0149] Impact resistance: The impact resistance of concrete was measured using a pendulum impact tester. The results are shown in Table 1.

[0150]

[0151] 28-day Compressive Strength Recovery Rate after Repair: All Examples achieved a 28-day compressive strength recovery rate of over 90%, meeting the requirement (≥90%), demonstrating that the repaired concrete possesses high strength recovery capabilities. Comparative Example 1 achieved a 28-day compressive strength recovery rate of only 30%, significantly lower than that of the Examples. While Comparative Examples 2, 3, and 4 achieved some recovery rates, these were significantly lower than those of the Examples, demonstrating the significant impact of each component on overall performance.

[0152] Improved 3d compressive strength: The 3d compressive strength of Example 1 increased by 38%-45%, meeting the requirement of 35%-50%, demonstrating that the nano-aramid cryogel-modified polymer significantly improved early strength. Comparative Example 1 only achieved a 20% improvement, far lower than that of the Example. Comparative Examples 2, 3, and 4, while showing some improvement, were not as good as those of the Example, demonstrating the significant contributions of functionalized carbon nanotubes, TiO2@SiO2 core-shell nanoparticles, and bio-based plasticizers.

[0153] Improved 28d Flexural Strength: The 28d flexural strength of Examples increased by 28%-35%, meeting the requirement of 25%-40%, demonstrating that the nano-aramid cryogel-modified polymer significantly enhances the flexural properties of concrete. Comparative Example 1 only achieved a 15% improvement, far lower than that of the Examples. While Comparative Examples 2, 3, and 4 showed some improvement, they were not as good as those of the Examples, demonstrating that the synergistic effect of the components is crucial for enhancing flexural properties.

[0154] Improved Tensile Strength: The tensile strength of the examples increased by 24%-29%, meeting the requirement of 20%-30%, demonstrating that the nano-aramid cryogel-modified polymer significantly enhances the tensile properties of concrete. Comparative Example 1 only achieved a 10% improvement, far lower than the examples. While Comparative Examples 2, 3, and 4 showed some improvement, they were not as good as the examples, demonstrating the importance of the synergistic effect of the components in enhancing tensile properties.

[0155] Improved impact resistance: The impact resistance of the examples improved by 48%-56%, meeting the requirement of 40%-60%, demonstrating that the nano-aramid cryogel-modified polymer significantly enhances the impact resistance of concrete. Comparative Example 1 only achieved a 20% improvement, far lower than the example. While Comparative Examples 2, 3, and 4 showed some improvement, they were not as good as the example, demonstrating that the synergistic effect of the components is crucial for improving impact resistance.

[0156] 2. Self-repair efficiency test:

[0157] Under standard curing conditions, the concrete specimens will produce micro-crack damage of 0.1-0.3mm.

[0158] The damaged specimens were placed in a standard curing environment, and the crack closure was observed and recorded within 48 hours.

[0159] The compressive strength after repair was measured, and the self-repair efficiency and compressive strength recovery rate were calculated.

[0160] 3. Durability test:

[0161] Chloride ion permeability coefficient: The chloride ion permeability coefficient of concrete is determined using the electrical flux method.

[0162] Working performance: Determine slump, expansion, initial setting time and final setting time. The above results are shown in Table 2.

[0163]

[0164] Self-repair efficiency: All examples achieved a self-repair efficiency of over 85%, meeting the requirement (≥85%). This demonstrates that the intelligent self-repairing microcapsules effectively repair concrete damaged by microcracks measuring 0.1-0.3 mm. Comparative Example 1 (lacking intelligent self-repairing microcapsules) achieved a self-repair efficiency of only 20%, significantly lower than that of the examples. Comparative Examples 2, 3, and 4 demonstrated some self-repair capability, but the results were inferior to those of the examples, demonstrating that the synergistic effect of the components is crucial for self-repair.

[0165] Reduction in Chloride Ion Permeability: The chloride ion permeability coefficient of the Examples decreased by 68%-76%, meeting the requirement of 60%-80%, indicating that the nano-aramid cryogel-modified polymer significantly reduced chloride ion permeability in concrete. Comparative Example 1 achieved only a 30% reduction, far lower than that of the Examples. While Comparative Examples 2, 3, and 4 showed some reduction, they were not as good as those of the Examples, demonstrating the importance of the synergistic effect of the components in reducing chloride ion permeability.

[0166] Working Performance: The working performance of the examples was in the range of 170-190 mm for slump, 470-520 mm for spread, 3.5-4.5 hours for initial setting time, and 6.5-7.5 hours for final setting time, all meeting the working performance requirements (slump 160-200 mm, spread 450-550 mm, initial setting time 3-5 hours, and final setting time 6-8 hours). Although the working performance of the comparative examples also generally met the requirements, it was generally inferior to the examples, particularly in terms of spread and setting time.

[0167] Through comparative analysis, it can be seen that the nano-aramid crystal-modified polymer in the embodiment significantly improves the various performance indicators of concrete, especially in terms of self-repair efficiency, compressive strength, flexural strength, tensile strength, impact resistance and durability. In contrast, the performance of the comparative example is significantly lower than that of the embodiment due to the lack of certain key components, which verifies the importance and synergistic effect of each component in the composite material. These experimental results provide strong data support for optimizing the formula. Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they are aware of the basic creative concepts. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the invention.

[0168] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

Claims

1. A nano-aramid crystal-modified polymer, characterized in that: The following components are included by mass percentage: Pretreated nano-aramid fiber 3.0-8.5%; Functionalized carbon nanotubes 0.5-2.5%; Silk fibroin nanofiber 0.5-2.5%; Nano metal oxide / SiO2 mixed dispersion 4.0-10.0%; Polymer matrix 65.0-85.0%; Bio-based plasticizer 0.8-1.8%; Intelligent self-repairing microcapsules 0.5-6.0%; Amphiphilic block copolymer dispersant 0.1-0.5%; The pretreated nano-aramid fiber is plasma-grafted with carboxyl -COOH and a silane coupling agent KH-550 for secondary modification, with a grafting rate of 1.2-3.5 mol%; The surface of the functionalized carbon nanotubes is grafted with polyethylene glycol, the molecular weight of the polyethylene glycol is 2000-5000, and the grafting density is 0.8-1.6 per nm. 2 ; The polymer matrix is ​​a blend system of polyvinyl alcohol and polyacrylic acid.

2. The nano-aramid cryogel-modified polymer according to claim 1, characterized in that: The pretreated nano-aramid fiber has a diameter of 50-80 nm and an aspect ratio of 2000-5000; The functionalized carbon nanotubes are multi-walled carbon nanotubes with an outer diameter of 8-15 nm and a length of 10-30 μm.

3. The nano-aramid cryogel-modified polymer according to claim 1, characterized in that: The silk fibroin nanofiber is a TEMPO-oxidized silk fibroin nanofiber with a diameter of 5-20 nm, a length of 1-3 μm, and a carboxyl content of 0.8-1.5 mmol / g.

4. The nano-aramid cryogel-modified polymer according to claim 1, wherein: The nano metal oxide / SiO2 mixed dispersion is a mixed dispersion of TiO2@SiO2 core-shell structure nanoparticles and ordinary nano-SiO2, wherein the mass ratio of TiO2@SiO2 core-shell structure nanoparticles to ordinary nano-SiO2 is 1.5:1-2.5:1, wherein the TiO2 core particle size is 10-20nm, and the SiO2 shell thickness is 2-5nm.

5. The nano-aramid cryogel-modified polymer according to claim 1, characterized in that: The degree of polymerization of polyvinyl alcohol in the polymer matrix is ​​1700-2400, the degree of alcoholysis is 88-99%, the molecular weight of polyacrylic acid is 80000-150000, and the mass ratio of polyvinyl alcohol to polyacrylic acid is 6:4-8:

2.

6. The nano-aramid cryogel-modified polymer according to claim 1, characterized in that: The bio-based plasticizer is a cardanol-based epoxy plasticizer with an epoxy value of 0.25-0.45eq / 100g and a viscosity of 800-1500mPa·s.

7. The nano-aramid cryogel-modified polymer according to claim 1, characterized in that: The intelligent self-repairing microcapsule has a melamine resin-polyurethane double-shell structure, with an outer melamine resin layer having a thickness of 0.5-1.0 μm and an inner polyurethane layer having a thickness of 0.2-0.5 μm. The core material is a mixture of epoxy resin E-51 and microencapsulated dicyandiamide curing agent in a mass ratio of 100:8-100:

12. The microcapsule particle size is 20-50 μm, and the encapsulation efficiency is ≥90%. The amphiphilic block copolymer dispersant is of PEO-PPO-PEO type, has a molecular weight of 8000-15000, and a PEO content of 60-80 wt%.

8. A tunnel bolt spraying support system, characterized by: The nano-aramid crystal-modified polymer according to any one of claims 1 to 7 is used as a sprayed concrete additive with an addition amount of 1.0-3.0 wt%, and is processed by a microwave-infrared synergistic process.

9. The tunnel bolt spraying support system according to claim 8, characterized in that: Using microwave-infrared synergistic process, including: Microwave stage: frequency 2.45 GHz, power density 1.0-2.5 kW / m³, duration 1.0-2.5 h; Infrared stage: wavelength 3-5μm, temperature 60-85℃, relative humidity 60-80%, duration 4.0-8.0h.

10. The tunnel bolt spraying support system according to claim 8, characterized in that: The sprayed concrete further contains 0.05-0.15% of a retarder sodium gluconate and 0.01-0.03% of an air entraining agent sodium lauryl sulfate.

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