Protective material for cutting slope and preparation method of protective material

Abstract

The invention belongs to the technical field of road materials, and particularly relates to a protective material for a cutting slope and a preparation method of the protective material. The modified bentonite and the bio-based binder form a compact matrix, so that the compressive strength is improved; the basalt fibers and the modified PHB fibers have a synergistic effect, the tensile strength is improved to 18-20 MPa, and the deformation requirement of + / -5% of the slope is met; the bio-based binder (starch-PLA) and the modified PHB fiber (the degradation period is 9-12 months) provide initial support for plant roots, degradation products are non-toxic and harmless, and the vegetation coverage rate is increased within one year.

Description

Technical Field

[0001] The invention belongs to the technical field of road materials, and more specifically relates to a protective material for a road cutting slope and a preparation method thereof. Background Art

[0002] In recent years, with the rapid development of infrastructure construction, the performance requirements of road cut slope protection materials have been increasing. They are not only required to have excellent mechanical strength and durability, but also to take into account ecological restoration functions and environmental protection properties. Although traditional protective materials such as cement concrete and shotcrete can provide higher strength, they have significant defects such as high brittleness, poor permeability, and high carbon emissions, which make it difficult to meet the needs of complex geological conditions and ecologically sensitive areas. For example, cement-based materials are prone to cracks in freeze-thaw cycles or alternating dry and wet environments, and after hardening, they inhibit plant growth, resulting in slow ecological recovery of the slope. In addition, the extensive use of cement has aggravated resource consumption and greenhouse gas emissions, which violates the concept of green and sustainable development.

[0003] In the prior art, some improvement schemes attempt to introduce ecological elements. For example, Chinese patent CN111662066A discloses an ecological concrete mixed with plant fibers. However, it relies on ordinary Portland cement as a cementitious material and still has problems such as high alkalinity and inhibition of microbial activity. It also lacks self-repairing ability and is prone to structural failure due to the expansion of microcracks after long-term use.

[0004] In response to the above problems, it is urgent to develop a new type of protective material that can achieve a balance between high strength, self-repair, ecological compatibility and resource recycling. Summary of the invention

[0005] 1. Technical issues to be resolved In view of the above-mentioned shortcomings and deficiencies of the prior art, the present invention provides a protective material for road cutting slopes and a preparation method thereof, which solves the technical problems that cement-based materials are prone to cracks and inhibit plant growth after hardening.

[0006] (II) Technical solution In a first aspect, the present invention provides a protective material for a road cut slope, comprising: cement, modified bentonite, industrial waste residue, a binder, basalt fiber, modified polyhydroxybutyrate fiber PHB, recycled rubber particles and a microcapsule self-healing agent; the modified bentonite is an organically modified sodium bentonite, the binder is a bio-based binder of starch-modified polylactic acid, and the modified polyhydroxybutyrate fiber is grafted with acrylate.

[0007] Optionally, the industrial waste slag is selected from at least one of fly ash and steel slag.

[0008] Optionally, the starch-modified polylactic acid is made of corn starch.

[0009] Optionally, by mass parts, the protective material for the cutting slope includes 40-50 parts of cement, 30-40 parts of modified bentonite, 30-40 parts of steel slag, 15-20 parts of starch-modified polylactic acid, 5-8 parts of basalt fiber, 5-8 parts of modified polyhydroxybutyrate fiber, 3-5 parts of recycled rubber particles, and 2-3 parts of microcapsule self-healing agent.

[0010] Optionally, the microcapsule self-healing agent uses sodium silicate as the core material and polyurethane as the wall material; The microcapsule self-healing agent is uniformly dispersed in the protective material. When cracks are generated in the slope under load, the stress at the crack tip exceeds the fracture strength of the polyurethane wall material, and the microcapsules rupture, releasing sodium silicate solution.

[0011] Optionally, the preparation method of the modified bentonite includes the steps: S1, Soak calcium-based bentonite, remove impurities, and centrifuge to dehydrate; S2, Mix the bentonite obtained in S1 with a 4% sodium carbonate solution; stir and react for 2 hours to obtain sodium-modified bentonite; S3, Add 5% cetyltrimethylammonium bromide to the sodium-modified bentonite, and stir and react at 50-100 °C to form organic bentonite; S4, Wash, dry at 110 °C, and then grind.

[0012] Optionally, the preparation method of the starch-modified polylactic acid includes the steps, S1, Dry corn starch at 50-100 °C for 4 hours; S2, Dissolve polylactic acid particles in dichloromethane with a concentration of 10% to form a polylactic acid solution; S3, Mix the dried starch with the polylactic acid solution, and add 0.5 wt% p-toluenesulfonic acid as a catalyst; S4, Under nitrogen protection, stir and react at 50-100 °C for 4-8 hours to generate a starch-polylactic acid copolymer.

[0013] Optionally, the preparation method of the microcapsule self-healing agent includes the steps: S1, Mix a 20% sodium silicate solution with Span-80 emulsifier, and shear and emulsify at 8000-10000 rpm to form an emulsified core material emulsion; S2, Mix toluene diisocyanate TDI with polyether polyol PPG2000, add dibutyltin dilaurate as a catalyst, and react at 50-80 °C to generate a terminal isocyanate group prepolymer; S3, Dissolve the prepolymer in 15% xylene, and add the emulsified core material emulsion; S4, Stir and react at 30-60 °C, and the isocyanate group reacts with water to generate a polyurethane wall material; S5, The centrifuged microcapsules are washed with acetone and dried under vacuum.

[0014] Optionally, the preparation method of the modified polyhydroxybutyrate fiber comprises the following steps: S1. Immerse the PHB fiber in a 5% sodium hydroxide solution for impurity removal; rinse with deionized water until neutral and dry. S2. Prepare an ethanol solution containing hydroxyethyl acrylate monomer and potassium persulfate initiator, immerse the PHB fiber in the solution, and perform ultrasonic treatment for 25 - 35 min. S3. Under nitrogen protection, react at 70 °C for 3 hours, then wash with ethanol and dry under vacuum to obtain the modified polyhydroxybutyrate fiber.

[0015] Optionally, the preparation method of the protective material for the cut slope comprises the steps of: Put cement, modified bentonite, and industrial waste residue into a mixer for dry mixing to obtain a dry mixture. Dissolve the bio - based binder in water, spray it onto the dry mixture, and stir until wet particles are formed. Add basalt fiber, modified PHB fiber, and recycled rubber particles in sequence, and mix by oscillation. Sprinkle the microcapsule self - repairing agent, and stir at low speed to obtain a mixture. Vacuum - degas the mixture, extrude it into a honeycomb - shaped board or a slope - protection brick blank; cure the formed blank at a constant temperature, and then naturally cure until the moisture content < 5%.

[0016] (III) Beneficial effects The modified bentonite and the bio - based binder form a dense matrix, improving the compressive strength; the basalt fiber and the modified PHB fiber act synergistically, increasing the tensile strength to 18 - 20 MPa, meeting the deformation requirements of the slope of ±5%.

[0017] The bio - based binder (starch - PLA) and the modified PHB fiber (degradation period of 9 - 12 months) provide initial support for plant roots, and the degradation products are non - toxic and harmless, increasing the vegetation coverage rate within 1 year.

[0018] The water - absorption swelling and water - locking ability of the organically modified bentonite promote plant germination and reduce soil erosion.

[0019] The expansion of cracks triggers the rupture of the polyurethane wall material of the microcapsule self - repairing agent, generating SiO2 gel from the sodium silicate solution, closing cracks of 0.3 - 0.5 mm within 24 hours, and improving the repair efficiency. Specific embodiments

[0020] To better explain the present invention for easy understanding, the present invention will be described in detail below through specific embodiments.

[0021] Starch is a natural polymer composed of glucose units and contains a large number of hydroxyl groups (-OH), so it has strong hydrophilicity. However, this also results in poor mechanical properties, easy water absorption and swelling, and it is not suitable for use alone as a structural material. On the other hand, PLA is a synthetic biodegradable material polymerized from lactic acid, with good mechanical strength and hydrophobicity, but it is brittle, lacks toughness, and is prone to fracture.

[0022] When starch and PLA are mixed, due to the incompatibility between hydrophilic starch and hydrophobic PLA, the interfacial bonding force between the two is weak, resulting in poor overall material performance. Therefore, chemical modification is needed to enhance their compatibility. The core of esterification graft modification is to form covalent bonds between starch and PLA through chemical reactions. Specifically, the hydroxyl groups (-OH) on the starch molecular chain react with the carboxyl groups (-COOH) on the PLA molecular chain under appropriate conditions to form ester bonds (-COO-). In this way, the combination between starch and PLA is no longer a simple physical mixture, but is connected by chemical bonds, significantly improving the compatibility and bonding strength between the two.

[0023] Organically modified sodium bentonite significantly improves the engineering properties of bentonite in slope protection materials through two-step modification of sodium modification - organic intercalation. The mechanism of action is as follows: First, sodium modification improves the swelling property and cation exchange capacity The original calcium-based bentonite mainly adsorbs Ca 2+ , and its layer spacing is relatively small (about 1.2 nm), and the water absorption and swelling ability is limited (swelling capacity 8 - 10 mL / g). Through sodium modification, Ca 2+ is replaced by Na + . Due to the hydration of Na + in the interlayer of sodium-based bentonite, a thicker hydration film is formed, and the layer spacing expands to 1.5 - 2.0 nm. After sodium modification, the swelling capacity is increased to 15 - 20 mL / g. When encountering water, the bentonite quickly swells, fills the micro-cracks of the material (swelling rate ≥ 150%), and inhibits the crack propagation.

[0024] Secondly, organic intercalation modification enhances the hydrophobicity and interfacial compatibility Sodium bentonite further reacts with cetyltrimethylammonium bromide. The cationic end is embedded in the interlayer of bentonite through electrostatic interaction, and the long-chain alkyl group extends outward to form an organic-inorganic hybrid structure. This process causes the following key changes: The alkyl chains cover the surface of bentonite, increasing the contact angle from <10° (hydrophilic) to >90° (hydrophobic), significantly reducing the water absorption rate (from 80% to 30%), and preventing the material from softening during the rainy season; after organic intercalation modification, the interlayer spacing increases to 2.5 - 3.0 nm, forming "molecular channels", which are more likely to adsorb long-chain molecules of organic binders (such as starch-PLA), and improving the interfacial bonding strength; the alkyl chains on the surface of bentonite combine with organic components such as recycled rubber particles and PHB fibers through van der Waals forces to form a dense composite structure, and the compressive strength is increased to 18 - 20 MPa.

[0025] The working principle of the microcapsule self-healing agent is as follows: The microcapsule self-healing agent is uniformly dispersed in the matrix of the protective material (addition amount 2 - 3%). When cracks are generated in the slope under load, the stress at the crack tip exceeds the fracture strength of the polyurethane wall material, and the microcapsules rupture, releasing sodium silicate solution. In addition, a high-humidity environment (RH > 80%) accelerates the swelling of the wall material and promotes the release of the core material; in an acid rain (pH < 5) environment, the hydrolysis rate of the polyurethane wall material increases, assisting in the release of the healing agent.

[0026] The repair process can be divided into the first stage and the second stage. Among them, the first stage (0 - 24 hours): The sodium silicate solution penetrates along the crack and reacts with CO2 or moisture in the environment to form SiO2 gel, initially sealing the crack; the second stage (24 - 72 hours): The gel further dehydrates and hardens, forming a chemical bond (Si - O - Si bond) with the matrix, restoring the integrity of the material.

[0027] The functions of cement, modified bentonite, industrial waste residue, binder, basalt fiber, modified polyhydroxybutyrate fiber PHB, recycled rubber particles and microcapsule self-healing agent in the protective material for the cutting slope of the present invention are as follows: As a gelling material, cement provides basic compressive strength (15 - 18 MPa), forms a rigid framework, and stabilizes the slope structure.

[0028] Industrial waste residues (fly ash / steel slag) replace part of the cement, reducing carbon emissions; the SiO2 in fly ash reacts with the hydration products of cement to improve the late strength; the Fe2O3 in steel slag enhances wear resistance. The utilization rate of the waste residues reaches 90%, reducing the accumulation of solid waste. Synergistic effect: The active components in cement and industrial waste residues (such as SiO2 and Al2O3 in fly ash) react to form calcium silicate hydrate (C - S - H) gel, improving the long-term strength.

[0029] The starch-modified polylactic acid binder forms a covalent bond between the hydroxyl group of starch and the carboxyl group of PLA through an esterification grafting reaction, and the bonding strength reaches 3.5 MPa; it is a 100% bio-based material with a degradation period of 2 - 3 years, synchronized with the growth of plant roots. The advantage is the improved water resistance (water absorption rate < 15%), avoiding the failure of traditional starch binders when exposed to water.

[0030] The fiber tensile strength of basalt fiber > 2000 MPa, which inhibits crack propagation; disperses stress waves and enhances stability under dynamic loads (such as vehicle vibrations); is resistant to acids and alkalis, resists ultraviolet rays, and has a service life > 50 years.

[0031] Recycled rubber particles have buffering and energy absorption capabilities. Their elastic modulus is low (1 - 3 MPa), which can absorb impact energy and reduce fatigue damage; fill the voids of the material and reduce the fluctuation of the permeability coefficient (stabilized at 5×10 -3 cm / s). It achieves the purpose of recycling tire rubber and reducing "black pollution".

[0032] Acrylate-grafted PHB fiber can toughen and resist cracking. Its elongation at break is 25%, which can absorb deformation energy and reduce brittle failure; it degrades by 30% in 9 - 12 months and is gradually replaced by plant roots, forming a "material-ecology" relay reinforcement. After acrylate grafting, the interfacial bonding strength with the binder is increased by 60%.

[0033] The synergistic effect among the substances of the present invention: As a rigid reinforcement material, basalt fiber has a tensile strength as high as 2000 MPa, which can quickly bear external loads and prevent structural damage of the slope under instantaneous impacts (such as falling rocks or vehicle vibrations). After acrylate grafting modification, the elongation at break of PHB fiber is increased to 25%, which can significantly absorb deformation energy, inhibit crack propagation, and avoid brittle fracture of the material. Recycled rubber particles (elastic modulus 1 - 3 MPa) are filled in the pores of the material, effectively buffering the stress fluctuations caused by periodic loads (such as freeze-thaw cycles or traffic vibrations). The three work together to form a "rigid-flexible-elastic" composite system, which increases the tensile strength of the material to 18 - 20 MPa and extends the dynamic fatigue life by more than 3 times (no macroscopic cracks after 10 6 cycle tests).

[0034] The bio-based binder (starch-modified polylactic acid) releases small molecule organic substances such as lactic acid during the degradation process, providing initial nutrition for plant roots. At the same time, its porous structure promotes the circulation of water and air, accelerating seed germination. The modified PHB fiber is gradually replaced by plant roots with a degradation cycle of 9 - 12 months, forming a dynamic reinforcement mechanism of "fiber degradation-root anchoring".

[0035] The microcapsule self-healing agent ruptures when the crack width reaches 0.1 - 0.3 mm through the mechanical response characteristics of the polyurethane wall material, releasing sodium silicate solution to generate SiO2 gel, sealing the crack within 24 hours, and the repair efficiency is over 85%. The water absorption and swelling property of bentonite (swelling rate ≥ 150%) further extrudes the crack edge, assisting the gel to fill and compact the repair area. The two work together to form a dual mechanism of "active repair (chemical gel) + passive filling (physical swelling)".

[0036] Preparation Example 1 The preparation method of the modified bentonite includes the steps: Select calcium-based bentonite with a montmorillonite content of ≥80%, crush it and pass through a 200-mesh sieve; soak it for 24 hours according to the ratio of calcium-based bentonite: water = 1:5, remove impurities and then centrifuge to dehydrate (the moisture content drops to 30%).

[0037] Mix the pretreated bentonite with a 4% sodium carbonate solution at a mass ratio of 1:3, and mechanically stir and react at 60°C for 2 hours.

[0038] Add 5% cetyltrimethylammonium bromide with a concentration to the sodium-modified bentonite, stir at 80°C for 1 hour to form an organic bentonite (the layer spacing expands from 1.2 nm to 2.8 nm).

[0039] Wash with deionized water until there is no Br - residue (no precipitation detected by silver nitrate), dry at 110°C and then grind to 300 meshes, and store in a sealed manner.

[0040] Preparation Example 2 The preparation method of the starch-modified polylactic acid includes the steps, Dry corn starch in an oven at 80°C for 4 hours to remove moisture.

[0041] Dissolve polylactic acid (PLA) particles in dichloromethane with a concentration of 10% to form a homogeneous solution.

[0042] Mix the dry starch and the PLA solution at a mass ratio of 1:3, add 0.5 wt% of the catalyst p-toluenesulfonic acid, and stir and react at 70°C for 6 hours under nitrogen protection to generate a starch-PLA graft copolymer.

[0043] Pour the reaction solution into cold ethanol for precipitation, filter and then vacuum dry for 24 hours, crush and pass through a sieve (200 meshes) to obtain a white powdery binder.

[0044] Preparation Example 3 The preparation method of the microcapsule self-healing agent includes the steps: Mix a 20% sodium silicate solution and Span-80 emulsifier at a mass ratio of 5:1, and perform high-speed shear emulsification at 10000 rpm for 10 minutes to form aqueous microdroplets.

[0045] Mix toluene diisocyanate (TDI) and polyether polyol (PPG2000) at a molar ratio of 1:2, add 0.1% of the catalyst dibutyltin dilaurate, and react at 60°C for 2 hours to generate a terminal isocyanate prepolymer; Dissolve the prepolymer in 15% xylene by concentration, and slowly add the emulsified core material emulsion; stir and react at 40 °C for 4 hours, and the isocyanate group reacts with water to form a polyurethane wall material.

[0046] Centrifuge and separate the microcapsules, wash them 3 times with acetone, dry them in vacuum at 40 °C, and screen the microcapsules with a particle size of 200 - 400 μm.

[0047] Preparation Example 4 The preparation method of the modified polyhydroxybutyrate fiber includes the following steps: Immerse the PHB fiber in a 5% sodium hydroxide solution, and treat it at 60 °C for 20 minutes to remove surface impurities; rinse it with deionized water until neutral, and dry it at 60 °C; Prepare an ethanol solution containing 10% hydroxyethyl acrylate monomer and 0.5% potassium persulfate initiator, immerse the fiber in the solution, and perform ultrasonic treatment for 30 minutes; Under nitrogen protection, react at 70 °C for 3 hours to graft acrylate onto the fiber surface; wash with ethanol and then dry in vacuum to obtain the modified PHB fiber.

[0048] Example 1

[0049] The protective material for the cutting slope includes 45 parts by mass of cement, 35 parts by mass of modified bentonite, 35 parts by mass of steel slag, 18 parts by mass of corn starch modified polylactic acid, 7 parts by mass of basalt fiber, 7 parts by mass of modified polyhydroxybutyrate fiber, 4 parts by mass of recycled rubber particles, and 2.5 parts by mass of microcapsule self - repairing agent.

[0050] Put cement, modified bentonite, and steel slag into a mixer and dry - mix for 15 minutes; Dissolve the bio - based binder (starch - PLA) in warm water, uniformly spray it onto the dry - mixed material, and stir until wet particles are formed; Add basalt fiber, modified PHB fiber, and recycled rubber particles in sequence, and oscillate and mix for 20 minutes to ensure uniform dispersion of the fibers; Uniformly sprinkle the microcapsule self - repairing agent, and stir at low speed to avoid capsule rupture; Send the mixture into a twin - screw extruder, degas at a vacuum degree of - 0.08 MPa, and extrude it into a honeycomb - shaped plate or slope protection brick blank; place the formed blank in a constant - temperature oven at 60 °C for 24 hours of curing, and then naturally cure for 7 days until the moisture content < 5%.

[0051] Example 2

[0052] The protective material for the cutting slope includes 40 parts by mass of cement, 30 parts by mass of modified bentonite, 30 parts by mass of fly ash, 15 parts by mass of corn starch modified polylactic acid, 5 parts by mass of basalt fiber, 5 parts by mass of modified polyhydroxybutyrate fiber, 3 parts by mass of recycled rubber particles, and 2 parts by mass of microcapsule self - repairing agent.

[0053] The preparation method of this embodiment is the same as that of Example 1 Example 3

[0054] The protective material for the cutting slope includes 50 parts by mass of cement, 40 parts by mass of modified bentonite, 40 parts by mass of steel slag and fly ash, 20 parts by mass of corn starch modified polylactic acid, 8 parts by mass of basalt fiber, 8 parts by mass of modified polyhydroxybutyrate fiber, 5 parts by mass of recycled rubber particles and 3 parts by mass of microcapsule self-healing agent.

[0055] The preparation method of this embodiment is the same as that of Example 1 Comparative Example 1 (lacking modified polyhydroxybutyrate fiber) The protective material for the cutting slope includes 45 parts by mass of cement, 35 parts by mass of modified bentonite, 35 parts by mass of steel slag and fly ash, 18 parts by mass of corn starch modified polylactic acid, 7 parts by mass of basalt fiber, 4 parts by mass of recycled rubber particles and 2.5 parts by mass of microcapsule self-healing agent.

[0056] The preparation method of this comparative example is the same as that of Example 1 Comparative Example 2 (lacking microcapsule self-healing agent) The protective material for the cutting slope includes 45 parts by mass of cement, 35 parts by mass of modified bentonite, 35 parts by mass of steel slag, 18 parts by mass of corn starch modified polylactic acid, 7 parts by mass of basalt fiber, 7 parts by mass of modified polyhydroxybutyrate fiber and 4 parts by mass of recycled rubber particles.

[0057] The preparation method of this comparative example is the same as that of Example 1 In order to further illustrate the technical effects of the protective materials for the cutting slopes in the embodiments and comparative examples of the present invention, relevant performance tests were carried out on the protective materials obtained in the embodiments and comparative examples. The test standard for the compressive strength is "Standard for Test Methods of Mechanical Properties of Ordinary Concrete" (GB / T 50081), and the test standard for the impermeability pressure is "Standard for Test Methods of Long-Term Performance and Durability of Ordinary Concrete" (GB / T 50082). The test results are shown in Table 1, and each embodiment was carried out under the same experimental environment.

[0058] Table 1: Test results of relevant properties of the protective materials obtained in the embodiments and comparative examples

[0059] As can be seen from the table, compared with the comparative examples, the protective materials in the embodiments of the present invention have better bearing capacity and impermeability performance, and basalt fiber, modified polyhydroxybutyrate fiber and microcapsule self-healing agent are more beneficial to improving the performance of the protective materials.

[0060] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A protective material for a cutting slope, comprising: Cement, modified bentonite, industrial waste residue, binder, basalt fiber, modified polyhydroxybutyrate fiber PHB, recycled rubber particles and microcapsule self-healing agent; it is characterized in that the modified bentonite is organically modified sodium bentonite, the binder is a bio-based binder of starch-modified polylactic acid, and the modified polyhydroxybutyrate fiber PHB is treated by acrylate grafting.

2. The protective material according to claim 1, characterized in that: The industrial waste residue is selected from at least one of fly ash and steel slag.

3. The protective material according to claim 1, characterized in that: The starch-modified polylactic acid uses corn starch.

4. The protective material according to claim 1, wherein: Calculated according to the following mass parts, the protective material for the cutting slope includes 40-50 parts of cement, 30-40 parts of modified bentonite, 30-40 parts of steel slag, 15-20 parts of starch-modified polylactic acid, 5-8 parts of basalt fiber, 5-8 parts of modified polyhydroxybutyrate fiber, 3-5 parts of recycled rubber particles and 2-3 parts of microcapsule self-healing agent.

5. The protective material according to claim 1, wherein: The microcapsule self-healing agent uses sodium silicate as the core material and polyurethane as the wall material; The microcapsule self-healing agent is uniformly dispersed in the protective material. When cracks are generated in the slope under load, the stress at the crack tip exceeds the fracture strength of the polyurethane wall material, and the microcapsules rupture, releasing sodium silicate solution.

6. The protective material according to claim 1, characterized in that: The preparation method of the modified bentonite includes the steps: S1, soak the calcium-based bentonite, remove impurities, and centrifuge for dehydration; S2, mix the bentonite obtained in S1 with a 4% sodium carbonate solution; stir and react for 2 hours to obtain sodium bentonite; S3, add 5% cetyltrimethylammonium bromide to the sodium bentonite, and stir and react at 50-100 °C to form organobentonite; S4, wash, dry at 110 °C and then grind.

7. The protective material according to claim 1, characterized in that: The preparation method of the starch-modified polylactic acid includes the steps, S1, dry corn starch at 50-100 °C for 4 hours; S2, dissolve polylactic acid particles in 10% dichloromethane to form a polylactic acid solution; S3, mix the dried starch with the polylactic acid solution, and add 0.5 wt% p-toluenesulfonic acid as a catalyst; S4, under nitrogen protection, stir and react at 50-100 °C for 4-8 hours to generate a starch-polylactic acid copolymer.

8. The protective material according to claim 1, characterized in that: The preparation method of the microcapsule self-healing agent includes the steps: S1, mix a 20% sodium silicate solution with Span-80 emulsifier, and shear and emulsify at 8000-10000 rpm to form an emulsified core material emulsion; S2, mix toluene diisocyanate TDI with polyether polyol PPG2000, add dibutyltin dilaurate as a catalyst, and react at 50-80 °C to generate a terminal isocyanate group prepolymer; S3, dissolve the prepolymer in 15% xylene, and add the emulsified core material emulsion; S4, stir and react at 30-60 °C, and the isocyanate group reacts with water to form a polyurethane wall material; S5, centrifuge to separate the microcapsules, wash with acetone, and vacuum dry.

9. The protective material according to claim 1, characterized in that: The preparation method of the modified polyhydroxybutyrate fiber PHB includes the following steps: S1. Immerse the PHB fiber in a 5% sodium hydroxide solution to remove impurities; rinse with deionized water until neutral, and dry. S2. Prepare an ethanol solution containing hydroxyethyl acrylate monomer and potassium persulfate initiator, immerse the PHB fibers in the solution, and perform ultrasonic treatment for 25 - 35 min; S3. React at 70 °C for 3 hours under nitrogen protection, then wash with ethanol and dry under vacuum to obtain modified polyhydroxybutyrate fibers.

10. The protective material according to claim 1, characterized in that: The preparation method of the protective material for the cut slope includes the steps: Put cement, modified bentonite, and industrial waste residue into a mixer for dry mixing to obtain a dry mixture; Dissolve the bio - based binder in water, spray it onto the dry mixture, and stir until wet particles are formed; Add basalt fibers, modified PHB fibers, and recycled rubber particles in sequence, and mix them by oscillation; Sprinkle the micro - capsule self - healing agent and stir at a low speed to obtain a mixture; Vacuum - degas the mixture, extrude it into a honeycomb - shaped board or a slope - protection brick blank; cure the formed blank at a constant temperature, and then naturally cure until the moisture content < 5%.

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