A protective material for road cutting slope and preparation method thereof

Abstract

This invention belongs to the field of road material technology, and more specifically relates to a protective material for cutting slopes and its preparation method. The modified bentonite and bio-based binder form a dense matrix, enhancing compressive strength. The synergistic effect of basalt fiber and modified PHB fiber increases tensile strength to 18-20 MPa, adapting to slope deformation requirements of ±5%. The bio-based binder (starch-PLA) and modified PHB fiber (degradation cycle of 9-12 months) provide initial support for plant roots, and the degradation products are non-toxic and harmless, increasing vegetation coverage within one year.

Description

Technical Field

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

[0002] In recent years, with the rapid development of infrastructure construction, the performance requirements for road cutting slope protection materials have been increasing. Not only must they have excellent mechanical strength and durability, but they must also take into account ecological restoration functions and environmental protection properties. Traditional protective materials such as cement concrete and shotcrete can provide high strength, but they have significant defects such as brittleness, poor permeability, and high carbon emissions, making it difficult to meet the needs of complex geological conditions and ecologically sensitive areas. For example, cement-based materials are prone to cracking 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 exacerbates resource consumption and greenhouse gas emissions, which violates the concept of green and sustainable development.

[0003] In the existing technology, some improvement schemes attempt to introduce ecological elements. For example, Chinese patent CN111662066A discloses an ecological concrete incorporating 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] To address the above issues, there is an urgent need 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

[0006] 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 cracking and inhibit plant growth after hardening.

[0007] (2) Technical solution

[0008] In a first aspect, the present invention provides a protective material for road cutting slopes, 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.

[0009] Optionally, the industrial waste slag is selected from at least one of fly ash and steel slag.

[0010] Optionally, the starch-modified polylactic acid is corn starch.

[0011] Optionally, according to the following proportions by mass, the protective materials for the road cutting slope include 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.

[0012] Optionally, the microcapsule self-repairing agent uses sodium silicate as the core material and polyurethane as the wall material;

[0013] The microcapsule self-repairing agent is evenly dispersed in the protective material. When the slope is subjected to load and cracks are generated, the stress at the crack tip exceeds the breaking strength of the polyurethane wall material, and the microcapsules rupture and release the sodium silicate solution.

[0014] Optionally, the preparation method of the modified bentonite comprises the steps of:

[0015] S1, soaking the calcium-based bentonite, removing impurities, and centrifugally dehydrating;

[0016] S2, mixing the bentonite obtained in S1 with a 4% sodium carbonate solution; stirring and reacting for 2 hours to obtain sodium bentonite;

[0017] S3, adding 5% hexadecyltrimethylammonium bromide to the sodium bentonite, stirring at 50-100° C. to react to form organic bentonite;

[0018] S4, washing, drying at 110℃ and grinding.

[0019] Optionally, the method for preparing starch-modified polylactic acid comprises the steps of:

[0020] S1, drying corn starch at 50-100°C for 4 hours;

[0021] S2, dissolving the polylactic acid particles in 10% dichloromethane to form a polylactic acid solution;

[0022] S3, mixing the dry starch with the polylactic acid solution and adding a catalyst of 0.5 wt% p-toluenesulfonic acid;

[0023] S4, under nitrogen protection, stirring and reacting at 50-100° C. for 4-8 hours to generate starch-polylactic acid copolymer.

[0024] Optionally, the preparation method of the microcapsule self-repairing agent comprises the steps of:

[0025] S1, mixing a 20% sodium silicate solution with a Span-80 emulsifier, and shearing and emulsifying at 8000-10000 rpm to form an emulsified core material emulsion;

[0026] S2, mixing toluene diisocyanate TDI and polyether polyol PPG2000, adding catalyst dibutyltin dilaurate, and reacting at 50-80°C to form a terminal isocyanate prepolymer;

[0027] S3, dissolving the prepolymer in 15% xylene, and adding the emulsified core material emulsion;

[0028] S4, stirring and reacting at 30-60°C, wherein the isocyanate group reacts with water to form a polyurethane wall material;

[0029] S5, centrifugation to separate microcapsules, washing with acetone, and vacuum drying.

[0030] Optionally, the preparation method of the modified polyhydroxybutyrate fiber comprises the following steps:

[0031] S1. The PHB fiber was immersed in a 5% sodium hydroxide solution to remove impurities; rinsed with deionized water until neutral and dried;

[0032] S2 prepared ethanol solution containing hydroxyethyl acrylate monomer and potassium persulfate initiator, the PHB fiber was immersed in the solution and ultrasonically treated for 25-35min;

[0033] S3. Under nitrogen protection, the reaction was carried out at 70°C for 3 hours. The modified polyhydroxybutyrate fiber was then washed with ethanol and dried in vacuum to obtain the modified polyhydroxybutyrate fiber.

[0034] Optionally, the method for preparing the protective material for the cutting slope comprises the steps of:

[0035] Putting cement, modified bentonite and industrial waste into a mixer and dry mixing to obtain a dry mix;

[0036] Dissolving a bio-based binder in water, spraying the mixture into the dry mix, and stirring until wet granules are formed;

[0037] Add basalt fiber, modified PHB fiber, and recycled rubber particles in sequence and shake to mix;

[0038] Sprinkle the microcapsule self-repairing agent into the mixture and stir at a low speed to obtain a mixture;

[0039] The mixed material is vacuum degassed and extruded into a honeycomb plate or slope protection brick body; the formed body is cured at a constant temperature and then naturally cured until the moisture content is less than 5%.

[0040] (3) Beneficial effects

[0041] Modified bentonite and bio-based binder form a dense matrix, which improves the compressive strength; basalt fiber and modified PHB fiber work synergistically to increase the tensile strength to 18-20MPa, adapting to the slope deformation requirement of ±5%.

[0042] Bio-based binders (starch-PLA) and modified PHB fibers (degradation cycle 9-12 months) provide initial support for plant roots. The degradation products are non-toxic and harmless, and the vegetation coverage rate increases within one year.

[0043] The water absorption and swelling properties and water-locking capacity of organically modified bentonite promote plant germination and reduce soil erosion.

[0044] The expansion of the crack triggers the rupture of the polyurethane wall material of the microcapsule self-healing agent, and the sodium silicate solution generates SiO2 gel, which seals the 0.3-0.5mm crack within 24 hours and improves the repair efficiency. DETAILED DESCRIPTION

[0045] In order to better explain the present invention and facilitate understanding, the present invention is described in detail below through specific implementation methods.

[0046] Starch is a natural polymer composed of glucose units and contains a large number of hydroxyl (-OH) groups, making it highly hydrophilic. However, this also results in poor mechanical properties and easy swelling due to water absorption, making it unsuitable for use as a structural material alone. PLA, on the other hand, is a synthetic biodegradable material derived from the polymerization of lactic acid. While it possesses good mechanical strength and hydrophobicity, it is brittle, lacks toughness, and is prone to breakage.

[0047] When starch and PLA are mixed, the incompatibility between the hydrophilic starch and the hydrophobic PLA leads to weak interfacial bonding, resulting in poor overall material performance. Therefore, chemical modification is necessary to enhance their compatibility. The core of esterification grafting modification is to form a covalent bond between starch and PLA through a chemical reaction. Specifically, under appropriate conditions, the hydroxyl groups (-OH) on the starch molecular chain and the carboxyl groups (-COOH) on the PLA molecular chain undergo an esterification reaction to form an ester bond (-COO-). This eliminates the need for a simple physical mixture of starch and PLA, but rather connects them through a chemical bond, significantly improving their compatibility and bonding strength.

[0048] Organically modified sodium bentonite significantly improves the engineering performance of bentonite in slope protection materials through a two-step modification process of sodium modification and organic intercalation. The mechanism of action is as follows:

[0049] First, sodium modification improves expansion and cation exchange capacity

[0050] The original calcium-based bentonite interlayer mainly adsorbs Ca 2+ , its interlayer spacing is small (about 1.2nm), and its water absorption and expansion capacity is limited (expansion capacity 8-10mL / g). 2+ Be Na + Replacement, sodium bentonite interlayer due to Na +Hydration forms a thicker hydration film, with interlayer spacing increasing to 1.5-2.0nm. After sodiumization, the expansion capacity increases to 15-20mL / g. Upon contact with water, the bentonite rapidly expands, filling micro-cracks in the material (expansion rate ≥150%) and inhibiting crack propagation.

[0051] Secondly, organic intercalation modification enhances hydrophobicity and interfacial compatibility

[0052] The sodium bentonite further reacts with hexadecyltrimethylammonium bromide, where the cationic end is embedded in the bentonite interlayers through electrostatic interaction, and the long-chain alkyl group extends outward, forming an organic-inorganic hybrid structure. This process triggers the following key changes:

[0053] The alkyl chains cover the surface of bentonite, and the contact angle increases from <10° (hydrophilic) to >90° (hydrophobic), which greatly reduces the water absorption rate (from 80% to 30%) and prevents the softening of the material during the rainy season; after organic intercalation modification, the interlayer spacing increases to 2.5-3.0nm, forming a "molecular channel" that is easier to adsorb long-chain molecules of organic binders (such as starch-PLA), thereby improving the interfacial bonding strength; the alkyl chains on the surface of bentonite are combined 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 18-20MPa.

[0054] The working principle of the microcapsule self-repairing agent is as follows:

[0055] The microcapsule self-healing agent is evenly dispersed in the protective material matrix (addition level: 2-3%). When the slope cracks under load, the stress at the crack tip exceeds the fracture strength of the polyurethane wall material, causing the microcapsules to rupture and release the sodium silicate solution. Furthermore, high humidity (RH > 80%) accelerates the swelling of the wall material and promotes the release of the core material. In acid rain (pH < 5), the hydrolysis rate of the polyurethane wall material is accelerated, aiding the release of the repair agent.

[0056] The repair process can be divided into the first and second stages. In the first stage (0-24 hours), the sodium silicate solution penetrates along the cracks, reacts with CO2 or water in the environment to form SiO2 gel, and initially seals the cracks. In the second stage (24-72 hours), the gel further dehydrates and hardens, forming a chemical bond (Si-O-Si bond) with the matrix to restore the integrity of the material.

[0057] The functions of the cement, modified bentonite, industrial waste residue, binder, basalt fiber, modified polyhydroxybutyrate fiber (PHB), recycled rubber particles, and microcapsule self-repairing agent in the protective material for cutting slopes of the present invention are as follows:

[0058] Cement, as a cementitious material, provides basic compressive strength (15-18 MPa), forms a rigid skeleton, and stabilizes the slope structure.

[0059] Industrial waste residue (fly ash / steel slag) partially replaces cement, reducing carbon emissions. The SiO2 in fly ash reacts with cement hydration products to improve later-stage strength, while the Fe2O3 in steel slag enhances wear resistance. The waste residue utilization rate reaches 90%, reducing solid waste accumulation. Synergistic effect: Cement reacts with the active components in industrial waste residue (such as SiO2 and Al2O3 in fly ash) to form calcium silicate hydrate (CSH) gel, improving long-term strength.

[0060] The starch-modified polylactic acid binder forms covalent bonds between the starch hydroxyl groups and the PLA carboxyl groups through an esterification grafting reaction, achieving a bond strength of 3.5 MPa. It is a 100% bio-based material with a degradation cycle of 2-3 years, synchronizing with plant root growth. Its advantage is improved water resistance (water absorption rate <15%), which avoids the water-induced failure of traditional starch binders.

[0061] The tensile strength of basalt fiber is greater than 2000MPa, which inhibits crack expansion; disperses stress waves and improves stability under dynamic loads (such as vehicle vibration); it is acid and alkali resistant, UV resistant, and has a service life of more than 50 years.

[0062] Recycled rubber particles have the function of buffering and absorbing energy. They have a low elastic modulus (1-3MPa), which absorbs impact energy and reduces fatigue damage. They can also fill material gaps and reduce fluctuations in water permeability (stable at 5×10 -3 cm / s). This allows for recycling tire rubber and reducing “black pollution”.

[0063] Acrylate-grafted PHB fiber enhances toughness and crack resistance, boasting a 25% elongation at break. It absorbs deformation energy and reduces brittle failure. It degrades by 30% over 9-12 months, gradually replaced by plant roots, creating a "material-ecology" reinforcement system. After acrylate grafting, the interfacial bond strength with the adhesive is increased by 60%.

[0064] Synergistic effect between the various substances of the present invention:

[0065] As a rigid reinforcing material, basalt fiber has a tensile strength of up to 2000MPa, which can quickly bear external loads and prevent the structural damage of the slope under instantaneous impact (such as falling rocks or vehicle vibration). After the PHB fiber is modified by acrylic ester grafting, the elongation at break is increased to 25%, which significantly absorbs deformation energy, inhibits crack expansion, and avoids brittle fracture of the material. Recycled rubber particles (elastic modulus 1-3MPa) fill the pores of the material to effectively buffer the stress fluctuations caused by cyclic 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 18-20MPa and extends the dynamic fatigue life by more than 3 times (after 10 6 No macro cracks in the 2-cycle test).

[0066] The bio-based binder (starch-modified polylactic acid) releases lactic acid and other small organic molecules during degradation, providing initial nutrients for plant roots. Its porous structure also promotes water and air circulation, accelerating seed germination. The modified PHB fiber is gradually replaced by plant roots over a degradation cycle of 9-12 months, forming a dynamic reinforcement mechanism of "fiber degradation-root anchoring."

[0067] The microcapsule self-healing agent exploits the mechanical response of the polyurethane wall material, rupturing when cracks reach 0.1-0.3mm in width. It releases a sodium silicate solution to form a SiO2 gel, sealing the crack within 24 hours with a repair efficiency exceeding 85%. The water-absorbing swelling properties of the bentonite (expansion rate ≥150%) further compress the crack edges, assisting the gel in filling and compacting the repaired area. These two elements work together to form a dual mechanism of "active repair (chemical gel) + passive filling (physical expansion)."

[0068] Preparation Example 1

[0069] The preparation method of the modified bentonite comprises the steps of:

[0070] Select calcium-based bentonite with a montmorillonite content of ≥80%, crush it and pass it through a 200-mesh sieve; soak it in a ratio of calcium-based bentonite: water = 1:5 for 24 hours, remove impurities and then centrifuge for dehydration (water content reduced to 30%).

[0071] The pretreated bentonite was mixed with 4% sodium carbonate solution in a mass ratio of 1:3 and reacted with mechanical stirring at 60°C for 2 hours.

[0072] 5% hexadecyltrimethylammonium bromide was added to the sodium bentonite and stirred at 80°C for 1 hour to form organobentonite (the interlayer spacing expanded from 1.2 nm to 2.8 nm).

[0073] Wash with deionized water until Br-free - The residue (no precipitation detected by silver nitrate) was dried at 110°C, ground to 300 mesh, and stored in a sealed container.

[0074] Preparation Example 2

[0075] The preparation method of starch-modified polylactic acid comprises the following steps:

[0076] The corn starch was dried in an oven at 80 °C for 4 h to remove moisture.

[0077] The polylactic acid (PLA) particles were dissolved in 10% dichloromethane to form a homogeneous solution.

[0078] Dry starch and PLA solution were mixed in a mass ratio of 1:3, 0.5 wt% of p-toluenesulfonic acid as a catalyst was added, and the mixture was stirred at 70°C for 6 hours under nitrogen protection to generate a starch-PLA graft copolymer.

[0079] The reaction solution was poured into cold ethanol for precipitation, filtered, vacuum dried for 24 hours, crushed and sieved (200 mesh) to obtain a white powdery binder.

[0080] Preparation Example 3

[0081] The preparation method of the microcapsule self-repairing agent comprises the steps of:

[0082] A 20% sodium silicate solution was mixed with a Span-80 emulsifier at a mass ratio of 5:1, and high-speed shear emulsification was performed at 10,000 rpm for 10 minutes to form aqueous phase droplets.

[0083] Toluene diisocyanate (TDI) and polyether polyol (PPG2000) were mixed in a molar ratio of 1:2, and a catalyst of dibutyltin dilaurate was added at a concentration of 0.1%. The mixture was reacted at 60°C for 2 hours to generate an isocyanate-terminated prepolymer.

[0084] The prepolymer was dissolved in 15% xylene and the emulsified core material emulsion was slowly added; the reaction was stirred at 40°C for 4 hours, and the isocyanate group reacted with water to form a polyurethane wall material.

[0085] The microcapsules were separated by centrifugation, washed with acetone three times, dried under vacuum at 40°C, and microcapsules with a particle size of 200-400 μm were screened.

[0086] Preparation Example 4

[0087] The preparation method of the modified polyhydroxybutyrate fiber comprises the following steps:

[0088] The PHB fiber was immersed in 5% sodium hydroxide solution and treated at 60℃ for 20 minutes to remove surface impurities; rinsed with deionized water until neutral, and dried at 60℃;

[0089] Prepare an ethanol solution containing 10% hydroxyethyl acrylate monomer and 0.5% potassium persulfate initiator, immerse the fiber in the solution, and ultrasonicate for 30 minutes;

[0090] Under nitrogen protection, the reaction was carried out at 70°C for 3 hours to graft the acrylate onto the fiber surface; after washing with ethanol, the modified PHB fiber was obtained by vacuum drying.

[0091] Example 1

[0092] The protective materials for the road cutting slope include 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-healing agent.

[0093] Put cement, modified bentonite and steel slag into the mixer and dry mix for 15 minutes;

[0094] Dissolve the bio-based binder (starch-PLA) in warm water, spray evenly into the dry mix, and stir until wet granules are formed;

[0095] Add basalt fiber, modified PHB fiber, and recycled rubber particles in sequence, and shake and mix for 20 minutes to ensure that the fibers are evenly dispersed;

[0096] Sprinkle the microcapsule self-healing agent evenly and stir at low speed to avoid capsule rupture;

[0097] The mixed material is fed into a twin-screw extruder, degassed at a vacuum degree of -0.08MPa, and extruded into a honeycomb plate or slope protection brick body; the formed body is placed in a constant temperature box at 60℃ for curing for 24 hours, and then naturally cured for 7 days until the moisture content is less than 5%.

[0098] Example 2

[0099] The protective materials for the road cutting slope include 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.

[0100] The preparation method of this embodiment is the same as that of Example 1

[0101] Example 3

[0102] The protective materials for the road cutting slope include 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.

[0103] The preparation method of this embodiment is the same as that of Example 1

[0104] Comparative Example 1 (lacking modified polyhydroxybutyrate fiber)

[0105] The protective materials for the road cutting slope include 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.

[0106] The preparation method of this comparative example is the same as that of Example 1

[0107] Comparative Example 2 (lack of microcapsule self-repairing agent)

[0108] The protective material for the road 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.

[0109] The preparation method of this comparative example is the same as that of Example 1

[0110] In order to further illustrate the technical effects of the road cutting slope protective materials of various embodiments and comparative examples of the present invention, relevant performance tests were conducted on the protective materials obtained in the embodiments and comparative examples. The test standard for compressive strength was the "Standard for Test Methods for Mechanical Properties of Ordinary Concrete" (GB / T 50081), and the test standard for anti-seepage pressure was the "Standard for Test Methods for Long-term Performance and Durability of Ordinary Concrete" (GB / T 50082). The test results are shown in Table 1. All embodiments were carried out under the same experimental environment.

[0111] Table 1: Test results of relevant properties of protective materials obtained in Examples and Comparative Examples

[0112]

[0113] It can be seen from the table that the protective material of the embodiment of the present invention has better load-bearing capacity and anti-permeability performance than the comparative example, and basalt fiber, modified polyhydroxybutyrate fiber and microcapsule self-healing agent are more beneficial to improving the performance of the protective material.

[0114] 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 it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, 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 road cutting slope, characterized by: The protective material comprises, by mass, 40-50 parts of cement, 30-40 parts of modified bentonite, 30-40 parts of industrial waste residue, 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 a microcapsule self-repairing agent; the modified bentonite is organically modified sodium bentonite, and the modified polyhydroxybutyrate fiber is polyhydroxybutyrate fiber grafted with acrylate; The microcapsule self-repairing agent uses sodium silicate solution as the core material and polyurethane as the wall material; The microcapsule self-repairing agent is evenly dispersed in the protective material. When the slope is loaded and cracks are generated, the stress at the crack tip exceeds the breaking strength of the polyurethane wall material, and the wall material of the self-repairing agent microcapsule breaks, releasing the sodium silicate solution.

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

3. The protective material according to claim 1, wherein: The starch-modified polylactic acid is corn starch-modified polylactic acid.

4. The protective material according to claim 1, wherein: The preparation method of the modified bentonite comprises the steps of: S1, soaking the calcium-based bentonite, removing impurities, and centrifugally dehydrating; S2, mixing the bentonite obtained in S1 with a 4% sodium carbonate solution; stirring and reacting for 2 hours to obtain sodium bentonite; S3, adding 5% hexadecyltrimethylammonium bromide to the sodium bentonite, stirring at 50-100° C. to react to form organic bentonite; S4, washing, drying at 110℃ and grinding.

5. The protective material according to claim 1, wherein: The preparation method of starch-modified polylactic acid comprises the following steps: S1, drying corn starch at 50-100°C for 4 hours; S2, dissolving the polylactic acid particles in 10% dichloromethane to form a polylactic acid solution; S3, mixing the dry starch with the polylactic acid solution and adding a catalyst of 0.5 wt% p-toluenesulfonic acid; S4, under nitrogen protection, stirring and reacting at 50-100° C. for 4-8 hours to generate starch-polylactic acid copolymer.

6. The protective material according to claim 1, wherein: The preparation method of the microcapsule self-repairing agent comprises the steps of: S1, mixing a 20% sodium silicate solution with a Span-80 emulsifier, and shearing and emulsifying at 8000-10000 rpm to form an emulsified core material emulsion; S2, mixing toluene diisocyanate TDI and polyether polyol PPG2000, adding catalyst dibutyltin dilaurate, and reacting at 50-80°C to form a terminal isocyanate prepolymer; S3, dissolving the prepolymer in 15% xylene, and adding the emulsified core material emulsion; S4, stirring and reacting at 30-60°C, wherein the isocyanate group reacts with water to form a polyurethane wall material; S5, centrifugation to separate microcapsules, washing with acetone, and vacuum drying.

7. The protective material according to claim 1, wherein: The preparation method of the modified polyhydroxybutyrate fiber comprises the following steps: S1. The modified polyhydroxybutyrate fiber was immersed in a 5% sodium hydroxide solution to remove impurities; rinsed with deionized water until neutral and dried; S2. An ethanol solution containing hydroxyethyl acrylate monomer and potassium persulfate initiator was prepared, and the modified polyhydroxybutyrate fiber was immersed in the solution and ultrasonically treated for 25-35min; S3. Under nitrogen protection, the reaction was carried out at 70°C for 3 hours. The modified polyhydroxybutyrate fiber was then washed with ethanol and dried in vacuum to obtain the modified polyhydroxybutyrate fiber.

8. The protective material according to claim 1, wherein: The method for preparing the protective material for the cutting slope comprises the following steps: Putting cement, modified bentonite and industrial waste into a mixer and dry mixing to obtain a dry mix; Dissolving a bio-based binder in water, spraying the mixture into the dry mix, and stirring until wet granules are formed; Add basalt fiber, modified polyhydroxybutyrate fiber, and recycled rubber particles in sequence and shake to mix; Sprinkle the microcapsule self-repairing agent into the mixture and stir at a low speed to obtain a mixture; The mixed material is vacuum degassed and extruded into a honeycomb plate or slope protection brick body; the formed body is cured at a constant temperature and then naturally cured until the moisture content is less than 5%.

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