Anti-cracking and anti-freezing fiber composite concrete and preparation method thereof

Abstract

The application discloses an anti-cracking and anti-freezing fiber composite concrete and a preparation method thereof, and relates to the field of concrete. In the application, biomimetic spider silk is immersed in a mineralization solution of microorganisms, light-responsive nanomaterials are added, and light is adjusted so that calcium carbonate crystals are arranged in a honeycomb shape on the surface of the spider silk, biomimetic spider silk fibers and the mineralization layer of microorganisms are alternately deposited, and a "fiber-mineralization layer-fiber" sandwich structure is constructed. The structure cooperates with the spiral shape of the spider silk and the honeycomb mineralization layer, greatly improves the interface strength of the concrete, effectively inhibits shrinkage cracks, and activates the microorganisms in the cracks to repair the cracks by mineralization, thereby endowing the concrete with strong crack resistance and self-repairing capability. Meanwhile, the self-prepared nanocomposite fiber takes polyvinyl alcohol and ethylene glycol copolymer as main materials, and has poly-lactic acid microchambers containing anhydrous calcium chloride connected at both ends, the hydrophilicity of the polyvinyl alcohol and the heat release of the anhydrous calcium chloride improve the frost resistance of the concrete. The anti-cracking and anti-freezing fiber composite concrete prepared by the application has the effects of high crack resistance and high frost resistance.

Description

Technical Field

[0001] This invention relates to the field of concrete technology, specifically to a crack-resistant and freeze-resistant fiber-reinforced composite concrete and its preparation method. Background Technology

[0002] In the field of construction engineering, concrete, as the most widely used basic material, directly affects the quality and safety of building structures. Especially in cold regions, concrete structures are subjected to severe freeze-thaw cycles year-round. Ordinary concrete contains a large number of pores. In low-temperature environments, the moisture in these pores freezes and expands. Repeated freeze-thaw cycles exert a periodic destructive force on the concrete, leading to cracking, spalling, and other defects, greatly weakening the structure's durability.

[0003] Meanwhile, due to its inherent properties, concrete is highly susceptible to cracking under the influence of temperature changes and drying shrinkage. These cracks not only reduce the load-bearing capacity of concrete structures but also impair their waterproofing properties, providing pathways for the intrusion of corrosive external media and accelerating structural deterioration. Against this backdrop, developing fiber-reinforced composite concrete with excellent freeze-thaw and crack-resistant properties has become an urgent priority for the industry. This material can effectively improve the performance of concrete in cold environments, significantly enhance the stability and service life of building structures, and meet the stringent requirements of construction projects in complex environments. Summary of the Invention

[0004] The purpose of this invention is to provide a crack-resistant and freeze-resistant fiber-reinforced composite concrete and its preparation method, so as to solve the problems existing in the prior art.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a crack-resistant and freeze-resistant fiber-reinforced composite concrete, wherein the preparation method of the crack-resistant and freeze-resistant fiber-reinforced composite concrete includes the following steps:

[0006] (1) After hydroxylating the biomimetic spider silk with a silane coupling agent, it was soaked in a mineralization solution containing 2% microorganisms at a mass ratio of 1:100-200. 0.01-0.03 times the mass of the biomimetic spider silk was added as photoresponsive nanomaterials. A mixed LED light source with a blue, green and red light ratio of 3:2:1, a light intensity of 1000 lux, and parallel illumination at 25-35℃ was used for 30 min. The mineralization cycle of "30 min illumination - 90 min standing" was carried out until a honeycomb mineralization layer was formed. Then, the biomimetic spider silk with a sandwich structure of "fiber-mineralization layer-fiber" was formed by "deposition-adsorption". The silk was dried at 30-40℃ to constant weight to obtain the self-made biomimetic spider silk solid.

[0007] (2) Polylactic acid containing microcavities, anhydrous calcium chloride, and organic solvent are uniformly mixed at a mass ratio of 10:1:100. After sonication at 30-35℃ and 40-50kHz for 30 minutes, the mixture is dried at 40℃ for 6 hours to obtain polylactic acid filled with anhydrous calcium chloride. Polyvinyl alcohol and ethylene glycol copolymer, polylactic acid filled with anhydrous calcium chloride, catalyst, and organic solvent are mixed at a mass ratio of 10:5:0.5:150. After stirring and reacting at 30-35℃ and 300-400rpm for 4-6 hours, the mixture is electrospun for 2-6 hours and dried at 40℃ for 6 hours to obtain self-made composite nanofibers.

[0008] (3) Mix 300-400 parts by weight of cement, 600-800 parts by weight of sand, 1100-1300 parts by weight of stone, 160-200 parts by weight of water, 5 parts by weight of admixture, 3-5 parts by weight of self-made biomimetic spider silk solid, 3-5 parts by weight of self-made composite fiber, and 60-100 parts by weight of admixture at 500 rpm to obtain crack-resistant and freeze-resistant fiber composite concrete.

[0009] Further, the preparation steps of the biomimetic spider silk in step (1) are as follows: Recombinant Escherichia coli wet cells expressing recombinant spider silk protein are dissolved in a heavy suspension containing 300 mM sodium chloride at a mass ratio of 1:10. After stirring at 300 rpm for 1 hour at 4°C, the mixture is homogenized using a high-pressure homogenizer to break down the cell walls. The mixture is then centrifuged at 8000–12000 rpm for 10 minutes. The supernatant is collected and purified by passing it through a nickel column affinity layer. Impurities are eluted with a pH 8.0 buffer solution containing 70 mM imidazole, and the target protein is eluted with a pH 8.0 buffer solution containing 250 mM imidazole to obtain the recombinant spider silk protein solution. The resulting solution is transferred to a dialysis bag with a molecular weight cutoff of 10 kDa and dialyzed in deionized water for 72 hours, with the deionized water being replaced every 8 hours. Next, the dialyzed spider silk protein solution was freeze-dried at -80℃ to obtain biomimetic spider silk freeze-dried powder. The biomimetic spider silk freeze-dried powder was dissolved in hexafluoroisopropanol at a mass ratio of 1:4, stirred at 100 rpm for 15 min, and then sonicated at 40 kHz for 15 min to obtain a spinning solution. The spinning solution was loaded into a syringe with a metal needle with an outer diameter of 0.9 mm and an inner diameter of 0.6 mm, and connected to an electrospinning device. The distance between the nozzle and the receiving plate was set to 15 cm, the voltage to 20 kV, and the solution flow rate to 0.5 mL / h. A rotating cylindrical collecting device was placed on the receiving plate at a rotation speed of 500 rpm, so that the fibers formed a spiral shape during collection. The collected spiral fibers were dried in a drying oven at 40℃ for 24 h to obtain spiral nanoscale biomimetic spider silk.

[0010] Furthermore, the silane coupling agent in step (1) is: γ-glycidyl etheroxypropyltrimethoxysilane (KH560).

[0011] Further, the hydroxylation step in step (1) is as follows: KH560 is added to deionized water at a volume ratio of 1:3 and stirred at 250 rpm for 2 h at 35 °C for hydrolysis reaction; spiral nanoscale biomimetic spider silk is mixed with the hydrolysate of KH560 at a mass ratio of 1:5 at 60 °C and stirred at 300 rpm for 8 h; the biomimetic spider silk is taken out, washed with anhydrous ethanol 2 to 4 times, and dried at 40 °C to constant weight to obtain hydroxylated biomimetic spider silk.

[0012] Furthermore, the photoresponsive nanomaterial in step (1) is: molybdenum sulfide particles with a diameter of 20 nm.

[0013] Furthermore, the microorganism mentioned in step (1) is: Pasteurella multocida.

[0014] Furthermore, the mineralization solution in step (1) is a solution composed of 6g yeast extract, 5g sodium chloride, 6g urea, 2g wheat bran, 12g calcium chloride and 1000ml deionized water.

[0015] Further, the preparation process of polylactic acid containing microcavities in step (2) is as follows: lactic acid with a purity ≥98% is added to a reaction vessel, and p-toluenesulfonic acid is added at a mass ratio of lactic acid to p-toluenesulfonic acid of 100:3. A prepolymerization reaction is carried out at 100-120°C for 2 hours. After the prepolymerization reaction is completed, the reaction temperature is gradually increased to 180-220°C, and the reaction is carried out under a vacuum of 10... -3 Polycondensation reaction is carried out at kPa. As the reaction proceeds, low molecular weight polylactic acid continues to polycondense, and the molecular weight continuously increases, so that the molecular weight of polylactic acid reaches 100,000 to 150,000. The above-mentioned polylactic acid with a molecular weight of 100,000 to 150,000 is dissolved in dichloromethane at a volume ratio of 1:15 to obtain a polylactic acid solution. Using polyvinyl alcohol as a surfactant, polyvinyl alcohol is dissolved in deionized water to prepare a polyvinyl alcohol aqueous solution with a mass concentration of 1 to 3% as an aqueous phase solution. The polylactic acid solution and the aqueous phase solution are injected into the flow channel of the microfluidic chip at a flow rate ratio of 1:5 using an injection pump. At the junction of the flow channels or at specific structural points, the two fluids interact. The polylactic acid solution forms droplets under the action of the aqueous phase solution, and then shrinks under the action of surface tension to form microcavities with a particle size of 20 μm.

[0016] Further, the preparation process of the polyvinyl alcohol and ethylene glycol copolymer in step (2) is as follows: polyvinyl alcohol is added to a three-necked flask, deionized water is added, and the mixture is stirred at a stirring rate of 150-250 rpm at a water bath temperature of 80-90°C until completely dissolved to obtain a uniform polyvinyl alcohol aqueous solution; after the polyvinyl alcohol aqueous solution is cooled to 40-50°C, ethylene glycol is added, and stirring is continued for 15-20 minutes to ensure thorough mixing; potassium persulfate is then added, and the pH value of the reaction system is adjusted with sodium hydroxide solution (0.1 mol / L). The temperature was increased to 7-8℃, then raised to 65-75℃, and the polymerization reaction was carried out at a stirring rate of 200-300 rpm until the molecular weight of the target product reached 5000-10000. The reaction product was distilled to remove unreacted raw materials and water, and then the product was dried in a drying oven at 40-50℃ to constant weight to obtain a nano-sized polyvinyl alcohol-ethylene glycol copolymer with a molecular weight of 5000-10000. The mass ratio of polyvinyl alcohol:ethylene glycol:deionized water:potassium persulfate with a degree of polymerization of 1700 was 1:1:15:0.02.

[0017] Furthermore, the organic solvent in step (2) is a mixture of dichloromethane and N,N-dimethylformamide in a volume ratio of 3:1.

[0018] Furthermore, the electrospinning device in step (2) consists of a spinneret of 0.6 to 1.6 mm, a high-voltage power supply of 20 to 50 kV, and a roller of 500 rpm to 1500 rpm.

[0019] Furthermore, the admixture in step (3) is a polycarboxylate superplasticizer, and the admixture is fly ash admixture.

[0020] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0021] This invention combines biomimetic spider silk fiber with microbial mineralization technology and adds self-made composite nanofibers to achieve crack-resistant and freeze-resistant effects.

[0022] First, this invention involves hydroxylating pretreated biomimetic spider silk with a silane coupling agent, then immersing it in a mineralization solution containing microorganisms that secrete urease. Photoresponsive nanomaterials are added, and by adjusting the light parameters, calcium carbonate crystals are induced to form a honeycomb arrangement on the surface of the biomimetic spider silk. Then, by alternately depositing biomimetic spider silk fibers and a microbial mineralization layer, a "fiber-mineralization layer-fiber" sandwich structure is formed. This structure, combined with the helical structure of the biomimetic spider silk and the honeycomb mineralization layer deposited by microorganisms on the fiber surface, can significantly improve the interfacial strength of concrete, effectively inhibiting concrete shrinkage cracks. The mineralization layer can also improve the corrosion resistance and freeze-thaw resistance of the fibers. Furthermore, the microorganisms are activated in the cracks, filling them through a mineralization reaction, giving the concrete not only strong crack resistance but also self-healing properties.

[0023] Secondly, the composite fiber used in this invention employs a copolymer of polyvinyl alcohol and ethylene glycol as the main material of the nanofiber. Polylactic acid (PLA) is linked to both ends of the copolymer molecular chain. Since PLA contains microcavities filled with anhydrous calcium chloride, the terminal carboxyl groups on the PLA chambers react with the hydroxyl groups of the PLA copolymer under the action of a catalyst to form ester bonds, thereby achieving chemical bonding between the PLA microcavities and the linear copolymer matrix. This is then processed using electrospinning technology to obtain a self-made nanofiber membrane, which is added to concrete. Polyvinyl alcohol itself has good hydrophilicity, and the hydroxyl groups on its molecular chain can form hydrogen bonds with water molecules, making it easy for the fiber surface to adsorb water molecules. As the fiber absorbs free water from the concrete and transports it to both ends, it reacts with the anhydrous calcium chloride in the microcavities to generate heat, improving the concrete's freeze-thaw resistance. Furthermore, calcium chloride is a commonly used substance for lowering the freezing point of water; its aqueous solution has a freezing point significantly lower than pure water, further enhancing the overall freezing point lowering effect of the nanofiber. This greatly improves the freeze-thaw resistance of concrete. The hydroxyl groups of ethylene glycol can complex with calcium ions in the concrete, further increasing the concrete's strength and crack resistance. Due to its high specific surface area, the nanostructure of the fiber membrane allows the nanofibers to mechanically interlock with the cement hydration products (CSH gel), reducing the interfacial transition zone and effectively inhibiting crack propagation. Detailed Implementation

[0024] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0025] To more clearly illustrate the method provided by the present invention, the following embodiments are provided in detail. The test methods for various indicators of the crack-resistant and freeze-thaw-resistant fiber-reinforced composite concrete prepared in the following embodiments are as follows:

[0026] Crack resistance: The concrete samples were made to the corresponding dimensions and cured for 28 days at 22°C and 95% relative humidity. The splitting tensile strength was then tested. The test method was consistent with that in GB / T 50081-2019, and the average value of the results was taken.

[0027] Freeze-thaw resistance: The method of “4 Freeze-thaw test” in GB / T50082—2009 Standard for Test Methods of Long-term Performance and Durability of Ordinary Concrete was adopted. The concrete samples were first made into corresponding sizes and cured for 28 days at a temperature of 22℃ and a relative humidity of 95% before the test was performed.

[0028] Durability: According to the stepwise pressure method in GB / T50082-2009 Standard for Test Methods of Long-term Performance and Durability of Ordinary Concrete, the concrete of the example was made into the corresponding size and cured for 28 days at a temperature of 22℃ and a relative humidity of 95%, and its impermeability grade was tested.

[0029] Example 1

[0030] (1) Recombinant Escherichia coli wet cells expressing recombinant spider silk protein were dissolved in a heavy suspension containing 300 mM sodium chloride at a mass ratio of 1:10. After stirring at 300 rpm for 1 h at 4 °C, the cells were homogenized using a high-pressure homogenizer and centrifuged at 8000 rpm for 10 min. The supernatant was collected and purified by nickel column affinity chromatography. Impurities were eluted with a buffer solution containing 70 mM imidazole at pH 8.0, and the target protein was eluted with a buffer solution containing 250 mM imidazole at pH 8.0 to obtain the recombinant spider silk protein solution. The obtained solution was transferred to a dialysis bag with a molecular weight cutoff of 10 kD and dialyzed in deionized water for 72 h, with the deionized water being changed every 8 h. The dialyzed spider silk protein solution was then... Bionic spider silk freeze-dried powder was obtained by freeze-drying at -80℃. The powder was dissolved in hexafluoroisopropanol at a mass ratio of 1:4, stirred at 100 rpm for 15 min, and then sonicated at 40 kHz for 15 min to obtain a spinning solution. The spinning solution was loaded into a syringe with a metal needle with an outer diameter of 0.9 mm and an inner diameter of 0.6 mm, and connected to an electrospinning device. The distance between the nozzle and the receiving plate was set to 15 cm, the voltage to 20 kV, and the solution flow rate to 0.5 mL / h. A rotating cylindrical collecting device was placed on the receiving plate at a rotation speed of 500 rpm, causing the fibers to form a spiral shape during collection. The collected spiral fibers were dried in a drying oven at 40℃ for 24 h to obtain spiral nanoscale bionic spider silk.

[0031] (2) KH560 was added to deionized water at a volume ratio of 1:3 and stirred at 250 rpm for 2 h at 35 °C for hydrolysis reaction; the spiral nanoscale biomimetic spider silk was mixed with the hydrolysate of KH560 at a mass ratio of 1:5 and stirred at 300 rpm for 8 h at 60 °C. The biomimetic spider silk was taken out, washed twice with anhydrous ethanol, and dried at 40 °C to constant weight to obtain hydroxylated biomimetic spider silk.

[0032] (3) The hydroxylated biomimetic spider silk was soaked in a mineralization solution of 2% pasteurella multocida at a mass ratio of 1:100. The mineralization solution consisted of 6g yeast extract, 5g sodium chloride, 6g urea, 2g wheat bran, 12g calcium chloride and 1000ml deionized water. 0.01 times the mass of biomimetic spider silk nano-sized molybdenum sulfide was added. A parallel light source with a mixed LED light source of blue, green and red light ratio of 3:2:1, light intensity of 1000 lux, and light temperature of 25℃ was used for 30 min. The "lighting for 30 min - standing for 90 min" cycle was repeated 4 times until a honeycomb mineralization layer was formed.

[0033] (4) After completing one round of light-induced mineralization, the bionic spider silk is taken out from the mineralization solution, the surface is rinsed with deionized water, and then it is soaked in the above-mentioned new spinning solution so that the fiber is adsorbed on the surface of the mineralization layer. The bionic spider silk with the adsorbed fiber is taken out, and the excess fiber dispersion liquid on the surface is removed with deionized water to form a "fiber-mineralization layer-fiber" sandwich structure of bionic spider silk. It is dried at 30°C to constant weight to obtain a self-made bionic spider silk solid with a particle size of 10nm spiral.

[0034] (5) Add lactic acid with a purity ≥98% to the reactor, and add p-toluenesulfonic acid at a mass ratio of lactic acid to p-toluenesulfonic acid of 100:3. Perform a prepolymerization reaction at 100°C for 2 hours. After the prepolymerization reaction is completed, gradually increase the reaction temperature to 180°C and maintain a vacuum of 10°C. -3 Polycondensation reaction was carried out at kPa. As the reaction proceeded, the low molecular weight polylactic acid continued to polycondense, and the molecular weight continued to increase until the molecular weight of polylactic acid reached 100,000. The polylactic acid with a molecular weight of 100,000 was dissolved in dichloromethane at a volume ratio of 1:15 to prepare a polylactic acid solution. Polyvinyl alcohol was used as a surfactant and dissolved in deionized water to prepare a 1% (w / w) polyvinyl alcohol aqueous solution as an aqueous phase solution. The polylactic acid solution and the aqueous phase solution were injected into the flow channel of the microfluidic chip at a flow rate ratio of 1:5 using an injection pump. At the junction of the flow channels or at specific structural points, the two fluids interacted. The polylactic acid solution formed droplets under the action of the aqueous phase solution, and then contracted under the action of surface tension to form microcavities with a particle size of 20 μm, thus obtaining polylactic acid containing microcavities.

[0035] (6) Add polyvinyl alcohol to a three-necked flask, add deionized water, and stir at 150 rpm in a water bath at 80°C until completely dissolved to obtain a homogeneous polyvinyl alcohol aqueous solution; after the polyvinyl alcohol aqueous solution is cooled to 40°C, add ethylene glycol, continue stirring for 15 min to mix thoroughly, add potassium persulfate, adjust the pH of the reaction system to 7 with sodium hydroxide solution (0.1 mol / L), then raise the temperature to 65°C and carry out the polymerization reaction at a stirring rate of 200 rpm until the molecular weight of the target product reaches 5000; distill the reaction product to remove unreacted raw materials and water, and then dry the product in a drying oven at 40°C to constant weight to obtain a nano-sized polyvinyl alcohol-ethylene glycol copolymer with a molecular weight of 5000; wherein the mass ratio of polyvinyl alcohol: ethylene glycol: deionized water: potassium persulfate with a degree of polymerization of 1700 is 1:1:15:0.02;

[0036] (7) Polylactic acid containing microcavities, anhydrous calcium chloride, and a mixed solvent of dichloromethane and N,N-dimethylformamide in a volume ratio of 3:1 were mixed at a mass ratio of 10:1:100. After sonication at 30°C and 40kHz for 30 min, the mixture was dried at 40°C for 6 h to obtain polylactic acid filled with anhydrous calcium chloride. Polyvinyl alcohol and ethylene glycol copolymer, polylactic acid filled with anhydrous calcium chloride, p-toluenesulfonic acid, and a mixed solvent of dichloromethane and N,N-dimethylformamide in a volume ratio of 3:1 were mixed at a mass ratio of 10:5:0.5:150. After stirring at 30°C and 300rpm for 4 h, the mixture was continuously spun by electrospinning for 2 h. The equipment parameters of the spinning device were: 30kV high voltage power supply, 0.6mm needle and 1000rpm roller. The obtained nanofiber membrane was dried at 40°C for 6 h to obtain self-made composite nanofibers with a particle size of 50nm.

[0037] (8) Mix 300 parts by weight of cement, 600 parts by weight of sand, 1100 parts by weight of stone, 160 parts by weight of water, 5 parts by weight of polycarboxylate superplasticizer, 3 parts by weight of self-made biomimetic spider silk solid, 3 parts by weight of self-made composite fiber, and 60 parts by weight of fly ash admixture at 500 rpm to obtain crack-resistant and freeze-resistant fiber composite concrete.

[0038] Example 2

[0039] (1) Recombinant Escherichia coli wet cells expressing recombinant spider silk protein were dissolved in a heavy suspension containing 300 mM sodium chloride at a mass ratio of 1:10. After stirring at 300 rpm for 1 h at 4 °C, the cells were homogenized using a high-pressure homogenizer and centrifuged at 10000 rpm for 10 min. The supernatant was collected and purified by nickel column affinity chromatography. Impurities were eluted with a buffer solution containing 70 mM imidazole at pH 8.0, and the target protein was eluted with a buffer solution containing 250 mM imidazole at pH 8.0 to obtain the recombinant spider silk protein solution. The obtained solution was transferred to a dialysis bag with a molecular weight cutoff of 10 kD and dialyzed in deionized water for 72 h, with the deionized water being changed every 8 h. The dialyzed spider silk protein solution was then purified. Bionic spider silk freeze-dried powder was obtained by freeze-drying at -80℃. The bionic spider silk freeze-dried powder was dissolved in hexafluoroisopropanol at a mass ratio of 1:4, stirred at 100 rpm for 15 min, and then sonicated at 40 kHz for 15 min to obtain a spinning solution. The spinning solution was loaded into a syringe with a metal needle with an outer diameter of 0.9 mm and an inner diameter of 0.6 mm, and connected to an electrospinning device. The distance between the nozzle and the receiving plate was set to 15 cm, the voltage to 20 kV, and the solution flow rate to 0.5 mL / h. A rotating cylindrical collecting device was placed on the receiving plate at a rotation speed of 500 rpm, so that the fibers formed a spiral shape during collection. The collected spiral fibers were dried in a drying oven at 40℃ for 24 h to obtain spiral nanoscale bionic spider silk.

[0040] (2) KH560 was added to deionized water at a volume ratio of 1:3 and stirred at 250 rpm for 2 h at 35 °C for hydrolysis reaction; the spiral nanoscale biomimetic spider silk was mixed with the hydrolysate of KH560 at a mass ratio of 1:5 and stirred at 300 rpm for 8 h at 60 °C. The biomimetic spider silk was taken out, washed 3 times with anhydrous ethanol, and dried at 40 °C to constant weight to obtain hydroxylated biomimetic spider silk.

[0041] (3) The hydroxylated biomimetic spider silk was soaked in a mineralization solution of 2% Pasteurella multocida at a mass ratio of 1:150. The mineralization solution consisted of 6g yeast extract, 5g sodium chloride, 6g urea, 2g wheat bran, 12g calcium chloride and 1000ml deionized water. 0.02 times the mass of the biomimetic spider silk was added to nano-sized molybdenum sulfide. A parallel light source was used with a mixed LED light source of blue, green and red light in a ratio of 3:2:1, a light intensity of 1000 lux, and a light temperature of 30℃ for 30 min. The "lighting for 30 min - standing for 90 min" cycle was repeated 5 times until a honeycomb mineralization layer was formed.

[0042] (4) After completing one round of light-induced mineralization, the bionic spider silk is taken out from the mineralization solution, the surface is rinsed with deionized water, and then it is soaked in the above-mentioned new spinning solution so that the fiber is adsorbed on the surface of the mineralization layer. The bionic spider silk with the adsorbed fiber is taken out, and the excess fiber dispersion liquid on the surface is removed with deionized water to form a "fiber-mineralization layer-fiber" sandwich structure of bionic spider silk. It is dried at 35°C to constant weight to obtain a self-made bionic spider silk solid with a particle size of 10nm spiral.

[0043] (5) Add lactic acid with a purity ≥98% to the reactor, and add p-toluenesulfonic acid at a mass ratio of lactic acid to p-toluenesulfonic acid of 100:3. Perform a prepolymerization reaction at 110°C for 2 hours. After the prepolymerization reaction is completed, gradually increase the reaction temperature to 200°C and maintain a vacuum of 10°C. -3 Polycondensation reaction was carried out at kPa. As the reaction proceeded, the low molecular weight polylactic acid continued to polycondense, and the molecular weight continued to increase until the molecular weight of polylactic acid reached 125,000. The polylactic acid with a molecular weight of 125,000 was dissolved in dichloromethane at a volume ratio of 1:15 to prepare a polylactic acid solution. Polyvinyl alcohol was used as a surfactant and dissolved in deionized water to prepare a 2% (w / w) polyvinyl alcohol aqueous solution as an aqueous phase solution. The polylactic acid solution and the aqueous phase solution were injected into the flow channel of the microfluidic chip at a flow rate ratio of 1:5 using an injection pump. At the junction of the flow channels or at specific structural points, the two fluids interacted. The polylactic acid solution formed droplets under the action of the aqueous phase solution, and then contracted under the action of surface tension to form microcavities with a particle size of 20 μm, thus obtaining polylactic acid containing microcavities.

[0044] (6) Add polyvinyl alcohol to a three-necked flask, add deionized water, and stir at 200 rpm in a water bath at 85°C until completely dissolved to obtain a homogeneous polyvinyl alcohol aqueous solution; after the polyvinyl alcohol aqueous solution is cooled to 45°C, add ethylene glycol, continue stirring for 18 min to mix thoroughly, add potassium persulfate, adjust the pH of the reaction system to 7.5 with sodium hydroxide solution (0.1 mol / L), then heat to 70°C and carry out the polymerization reaction at a stirring rate of 250 rpm until the molecular weight of the target product reaches 7500; distill the reaction product to remove unreacted raw materials and water, and then dry the product in a drying oven at 45°C to constant weight to obtain a nano-sized polyvinyl alcohol-ethylene glycol copolymer with a molecular weight of 7500; wherein the mass ratio of polyvinyl alcohol: ethylene glycol: deionized water: potassium persulfate with a degree of polymerization of 1700 is 1:1:15:0.02;

[0045] (7) Polylactic acid containing microcavities, anhydrous calcium chloride, and a mixed solvent of dichloromethane and N,N-dimethylformamide in a volume ratio of 3:1 were uniformly mixed at a mass ratio of 10:1:100. After sonication at 33°C and 45kHz for 30 min, the mixture was dried at 40°C for 6 h to obtain polylactic acid filled with anhydrous calcium chloride. Polyvinyl alcohol and ethylene glycol copolymer, polylactic acid filled with anhydrous calcium chloride, p-toluenesulfonic acid, and a mixed solvent of dichloromethane and N,N-dimethylformamide in a volume ratio of 3:1 were mixed at a mass ratio of 10:5:0.5:150. After stirring and reacting at 33°C and 350rpm for 5 h, the mixture was continuously spun by electrospinning for 4 h. The equipment parameters of the spinning device were: 30kV high voltage power supply, 0.6mm needle and 1000rpm roller. The obtained nanofiber membrane was dried at 40°C for 6 h to obtain self-made composite nanofibers with a particle size of 50nm.

[0046] (8) Mix 350 parts by weight of cement, 700 parts by weight of sand, 1200 parts by weight of stone, 180 parts by weight of water, 5 parts by weight of polycarboxylate superplasticizer, 4 parts by weight of self-made biomimetic spider silk solid, 4 parts by weight of self-made composite fiber, and 80 parts by weight of fly ash admixture at 500 rpm to obtain crack-resistant and freeze-resistant fiber composite concrete.

[0047] Example 3

[0048] (1) Recombinant Escherichia coli cells expressing recombinant spider silk protein were dissolved in a heavy suspension containing 300 mM sodium chloride at a mass ratio of 1:10. After stirring at 300 rpm for 1 h at 4 °C, the cells were homogenized using a high-pressure homogenizer and centrifuged at 12000 rpm for 10 min. The supernatant was collected and purified by nickel column affinity chromatography. Impurities were eluted with a buffer solution containing 70 mM imidazole at pH 8.0, and the target protein was eluted with a buffer solution containing 250 mM imidazole at pH 8.0 to obtain the recombinant spider silk protein solution. The obtained solution was transferred to a dialysis bag with a molecular weight cutoff of 10 kD and dialyzed in deionized water for 72 h, with the deionized water being changed every 8 h. The dialyzed spider silk protein solution was then purified. Bionic spider silk freeze-dried powder was obtained by freeze-drying at -80℃. The bionic spider silk freeze-dried powder was dissolved in hexafluoroisopropanol at a mass ratio of 1:4, stirred at 100 rpm for 15 min, and then sonicated at 40 kHz for 15 min to obtain a spinning solution. The spinning solution was loaded into a syringe with a metal needle with an outer diameter of 0.9 mm and an inner diameter of 0.6 mm, and connected to an electrospinning device. The distance between the nozzle and the receiving plate was set to 15 cm, the voltage to 20 kV, and the solution flow rate to 0.5 mL / h. A rotating cylindrical collecting device was placed on the receiving plate at a rotation speed of 500 rpm, so that the fibers formed a spiral shape during collection. The collected spiral fibers were dried in a drying oven at 40℃ for 24 h to obtain spiral nanoscale bionic spider silk.

[0049] (2) KH560 was added to deionized water at a volume ratio of 1:3 and hydrolyzed at 35°C and 250 rpm for 30 min. Spiral nanoscale biomimetic spider silk was mixed with the hydrolysate of KH560 at a mass ratio of 1:5 and stirred at 60°C and 300 rpm for 8 h. The biomimetic spider silk was taken out, washed 4 times with anhydrous ethanol, and dried at 40°C to constant weight to obtain hydroxylated biomimetic spider silk.

[0050] (3) The hydroxylated biomimetic spider silk was soaked in a mineralization solution of 2% Pasteurella multocida at a mass ratio of 1:200. The mineralization solution consisted of 6g yeast extract, 5g sodium chloride, 6g urea, 2g wheat bran, 12g calcium chloride and 1000ml deionized water. 0.03 times the mass of the biomimetic spider silk was added to nano-sized molybdenum sulfide. A parallel light source was used with a mixed LED light source of blue, green and red light in a ratio of 3:2:1, a light intensity of 1000 lux, and a light temperature of 35℃ for 30 min. The "lighting for 30 min - standing for 90 min" cycle was repeated 6 times until a honeycomb mineralization layer was formed.

[0051] (4) After completing one round of light-induced mineralization, the bionic spider silk is taken out from the mineralization solution, the surface is rinsed with deionized water, and then it is soaked in the above-mentioned new spinning solution so that the fiber is adsorbed on the surface of the mineralization layer. The bionic spider silk with the adsorbed fiber is taken out, and the excess fiber dispersion liquid on the surface is removed with deionized water to form a "fiber-mineralization layer-fiber" sandwich structure of bionic spider silk. It is dried at 40°C to constant weight to obtain a self-made bionic spider silk solid with a particle size of 10nm spiral.

[0052] (5) Add lactic acid with a purity ≥98% to the reactor, and add p-toluenesulfonic acid at a mass ratio of lactic acid to p-toluenesulfonic acid of 100:3. Perform a prepolymerization reaction at 120°C for 2 hours. After the prepolymerization reaction is completed, gradually increase the reaction temperature to 220°C and maintain a vacuum of 10. -3 Polycondensation reaction was carried out at kPa. As the reaction proceeded, the low molecular weight polylactic acid continued to polycondense, and the molecular weight continued to increase until the molecular weight of polylactic acid reached 150,000. The polylactic acid with a molecular weight of 150,000 was dissolved in dichloromethane at a volume ratio of 1:15 to prepare a polylactic acid solution. Polyvinyl alcohol was used as a surfactant and dissolved in deionized water to prepare a 3% (w / w) polyvinyl alcohol aqueous solution as an aqueous phase solution. The polylactic acid solution and the aqueous phase solution were injected into the flow channel of the microfluidic chip at a flow rate ratio of 1:5 using an injection pump. At the junction of the flow channels or at specific structural points, the two fluids interacted. The polylactic acid solution formed droplets under the action of the aqueous phase solution, and then contracted under the action of surface tension to form microcavities with a particle size of 20 μm, thus obtaining polylactic acid containing microcavities.

[0053] (6) Add polyvinyl alcohol to a three-necked flask, add deionized water, and stir at 250 rpm in a water bath at 90°C until completely dissolved to obtain a homogeneous polyvinyl alcohol aqueous solution; after the polyvinyl alcohol aqueous solution is cooled to 50°C, add ethylene glycol, continue stirring for 20 min to mix thoroughly, add potassium persulfate, adjust the pH of the reaction system to 8 with sodium hydroxide solution (0.1 mol / L), then heat to 75°C and carry out the polymerization reaction at 300 rpm until the molecular weight of the target product reaches 10,000; distill the reaction product to remove unreacted raw materials and water, and then dry the product in a drying oven at 50°C to constant weight to obtain a nano-sized polyvinyl alcohol-ethylene glycol copolymer with a molecular weight of 10,000; wherein the mass ratio of polyvinyl alcohol: ethylene glycol: deionized water: potassium persulfate with a degree of polymerization of 1700 is 1:1:15:0.02;

[0054] (7) Polylactic acid containing microcavities, anhydrous calcium chloride, and a mixed solvent of dichloromethane and N,N-dimethylformamide in a volume ratio of 3:1 were uniformly mixed at a mass ratio of 10:1:100. After sonication at 35°C and 50kHz for 30 minutes, the mixture was dried at 40°C for 6 hours to obtain polylactic acid filled with anhydrous calcium chloride. Polyvinyl alcohol and ethylene glycol copolymer, polylactic acid filled with anhydrous calcium chloride, p-toluenesulfonic acid, and a mixed solvent of dichloromethane and N,N-dimethylformamide in a volume ratio of 3:1 were mixed at a mass ratio of 10:5:0.5:150. After stirring and reacting at 35°C and 400rpm for 6 hours, the mixture was continuously spun by electrospinning for 6 hours. The equipment parameters of the spinning device were: 30kV high voltage power supply, 0.6mm needle and 1000rpm roller. The obtained nanofiber membrane was dried at 40°C for 6 hours to obtain self-made composite nanofibers with a particle size of 50nm.

[0055] (8) Mix 400 parts by weight of cement, 800 parts by weight of sand, 1300 parts by weight of stone, 200 parts by weight of water, 5 parts by weight of polycarboxylate superplasticizer, 5 parts by weight of self-made biomimetic spider silk solid, 5 parts by weight of self-made composite nanofiber, and 100 parts by weight of fly ash admixture at 500 rpm to obtain crack-resistant and freeze-resistant fiber composite concrete.

[0056] Comparative Example 1

[0057] The difference between Comparative Example 1 and Example 2 lies in step (1), where the bionic spider silk is not spiraled during collection. The remaining steps are the same as in Example 2.

[0058] Comparative Example 2

[0059] The difference between Comparative Example 2 and Example 2 lies in step (2), in that the biomimetic spider silk is not hydroxylated, while the other steps are the same as in Example 2.

[0060] Comparative Example 3

[0061] The difference between Comparative Example 3 and Example 2 lies in step (3), in that the mineralization layer of the biomimetic spider silk is not induced into a honeycomb structure, while the other steps are the same as in Example 2.

[0062] Comparative Example 4

[0063] The difference between Comparative Example 4 and Example 2 lies in step (3). Step (3) is changed to adding hydroxylated biomimetic spider silk to a mixture of 0.1 mol / L calcium chloride solution and 0.1 mol / L sodium carbonate solution at a mass ratio of 1:21. The pH value is adjusted to 7 with tris(hydroxymethyl)aminomethane hydrochloride buffer solution (0.1 mol / L). The reaction is carried out in a constant temperature incubator at 37°C for 48 h. During the reaction, the solution is gently stirred every 12 h. After the reaction is completed, the mineralized biomimetic spider silk is taken out, rinsed with deionized water 3 times, and then the sample is placed in a 60°C oven to dry for 24 h. The remaining steps are the same as in Example 2.

[0064] Comparative Example 5

[0065] The difference between Comparative Example 5 and Example 2 lies in step (4), in that a sandwich structure of "fiber-mineralized layer-fiber" is not formed, while the other steps are the same as in Example 2.

[0066] Comparative Example 6

[0067] The difference between Comparative Example 6 and Example 2 lies in the difference between steps (5) and (7). Step (5) is removed, and step (7) is replaced by mixing polyvinyl alcohol and ethylene glycol copolymer, dichloromethane and N,N-dimethylformamide in a volume ratio of 3:1 at a mass ratio of 10:150, and continuously spinning for 4 hours in an electrospinning device consisting of a 30kV high voltage power supply, a 0.6nm needle and a roller rotating at 1000rpm. The resulting nanofiber membrane is dried at 40°C for 6 hours to obtain self-made nanofibers with a particle size of 50nm. The remaining steps are the same as in Example 2.

[0068] Comparative Example 7

[0069] The difference between Comparative Example 7 and Example 2 lies in the difference between steps (6) and (7). Step (6) is removed, and step (7) is changed to uniformly mixing polylactic acid containing microcavities, anhydrous calcium chloride, dichloromethane in a volume ratio of 3:1 and N,N-dimethylformamide in a mass ratio of 10:1:100, sonicating at 35°C and 50kHz for 30 min, and then drying at 40°C for 6 h to obtain polylactic acid filled with anhydrous calcium chloride; the polylactic acid filled with anhydrous calcium chloride, and the... Toluenesulfonic acid, dichloromethane (volume ratio 3:1), and N,N-dimethylformamide were mixed in a mass ratio of 5:0.5:150 and reacted at 35°C with stirring at 400 rpm for 6 hours. Then, the mixture was continuously spun by electrospinning for 6 hours. The spinning equipment parameters were: 30 kV high voltage power supply, 0.6 nm needle, and 1000 rpm roller. The resulting nanofiber membrane was dried at 40°C for 6 hours to obtain self-made nanofibers with a particle size of 50 nm. The remaining steps were the same as in Example 2.

[0070] Comparative Example 8

[0071] The difference between Comparative Example 8 and Example 2 lies in step (8). Step (8) is changed to mixing 350 parts by weight of cement, 700 parts by weight of sand, 1200 parts by weight of stone, 180 parts by weight of water, 5 parts by weight of polycarboxylate superplasticizer, 4 parts by weight of self-made composite fiber, and 80 parts by weight of fly ash admixture at 500 rpm to obtain crack-resistant and freeze-resistant fiber composite concrete. The remaining steps are the same as in Example 2.

[0072] Comparative Example 9

[0073] The difference between Comparative Example 9 and Example 2 lies in step (8). Step (8) is changed to mixing 350 parts by weight of cement, 600 parts by weight of sand, 1200 parts by weight of stone, 180 parts by weight of water, 5 parts by weight of polycarboxylate superplasticizer, 4 parts by weight of self-made biomimetic spider silk solid, and 80 parts by weight of fly ash admixture at 500 rpm to obtain crack-resistant and freeze-resistant fiber composite concrete. The remaining steps are the same as in Example 2.

[0074] Comparative Example 10

[0075] The difference between Comparative Example 10 and Example 2 lies in the difference between steps (1) to (8). The difference is that steps (1) to (7) are removed, and step (8) is changed to mixing 350 parts by weight of cement, 700 parts by weight of sand, 1200 parts by weight of stone, 180 parts by weight of water, 5 parts by weight of polycarboxylate superplasticizer, and 80 parts by weight of fly ash admixture at 500 rpm to obtain crack-resistant and freeze-resistant fiber composite concrete.

[0076] Example of effect

[0077] Table 1 below presents the performance analysis results of crack-resistant and freeze-resistant fiber-reinforced composite concretes using Examples 1 to 3 and Comparative Examples 1 to 10 of the present invention.

[0078] Table 1

[0079]

[0080]

[0081] A comparison of the experimental data on splitting tensile strength between the examples and comparative examples reveals that this product, after pretreatment of biomimetic spider silk with hydroxylation via a silane coupling agent, is immersed in a mineralization solution containing microorganisms capable of secreting urease. Photoresponsive nanomaterials are added, and by adjusting the light parameters, calcium carbonate crystals are induced to form a honeycomb arrangement on the surface of the biomimetic spider silk. Then, through alternating deposition of biomimetic spider silk fibers and microbial mineralization layers, a "fiber-mineralization layer-fiber" sandwich structure is formed. This structure, combined with the helical structure of the biomimetic spider silk and the honeycomb mineralization layer deposited by microorganisms on the fiber surface, can significantly improve the interfacial strength of concrete and effectively inhibit concrete shrinkage cracks. The mineralization layer can also improve the corrosion resistance and frost resistance of the fibers. A comparison of the experimental data on mass loss rate between the examples and comparative examples reveals that the self-made nanocomposite fibers used in this product use a copolymer of polyvinyl alcohol and ethylene glycol as the main material of the nanofibers. The ends of the copolymer molecular chains are linked to polylactic acid containing microcavities, and the cavities are filled with anhydrous calcium chloride. Polyvinyl alcohol (PVA) has excellent hydrophilicity, and the hydroxyl groups on its molecular chain readily form hydrogen bonds with water molecules, allowing water to be adsorbed onto the fiber surface. The fibers absorb free water from the concrete and transport it to both ends, where it reacts exothermically with anhydrous calcium chloride within the microcavities. Furthermore, the calcium chloride lowers the freezing point of water, improving the concrete's frost resistance. The hydroxyl groups of ethylene glycol complex with calcium ions, enhancing the concrete's strength and crack resistance. The fiber membrane's nanostructure has a large specific surface area, mechanically interlocking with the CSH gel, reducing the interfacial transition zone and inhibiting crack propagation. Comparison of experimental data from the examples and comparative examples regarding impermeability levels reveals that microorganisms on the biomimetic spider silk surface are activated within the cracks, filling them through a mineralization reaction. This results in concrete possessing not only strong crack resistance but also self-healing properties.

[0082] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No markings in the claims should be construed as limiting the scope of the claims.

Claims

1. A crack-resistant and freeze-thaw-resistant fiber-reinforced composite concrete, characterized in that, The preparation method of the crack-resistant and freeze-thaw-resistant fiber-reinforced composite concrete includes the following steps: (1) Recombinant Escherichia coli wet cells expressing recombinant spider silk protein were dissolved in a heavy suspension containing 300 mM sodium chloride at a mass ratio of 1:

10. After stirring at 300 rpm for 1 h at 4 °C, the cells were homogenized using a high-pressure homogenizer and centrifuged at 8000-12000 rpm for 10 min. The supernatant was collected and purified by passing it through a nickel column affinity layer. Impurities were eluted with a buffer solution containing 70 mM imidazole at pH 8.0, and the target protein was eluted with a buffer solution containing 250 mM imidazole at pH 8.0 to obtain the recombinant spider silk protein solution. The obtained solution was transferred to a dialysis bag with a molecular weight cutoff of 10 kD and dialyzed in deionized water for 72 h, with the deionized water being changed every 8 h. The dialyzed spider silk was then collected. The protein solution was freeze-dried at -80℃ to obtain biomimetic spider silk freeze-dried powder. The biomimetic spider silk freeze-dried powder was dissolved in hexafluoroisopropanol at a mass ratio of 1:4, stirred at 100 rpm for 15 min, and then sonicated at 40 kHz for 15 min to obtain a spinning solution. The spinning solution was loaded into a syringe with a metal needle with an outer diameter of 0.9 mm and an inner diameter of 0.6 mm, and connected to an electrospinning device. The distance between the nozzle and the receiving plate was set to 15 cm, the voltage to 20 kV, and the solution flow rate to 0.5 mL / h. A rotating cylindrical collecting device was placed on the receiving plate at a rotation speed of 500 rpm, so that the fibers formed a spiral shape during collection. The collected spiral fibers were dried in a drying oven at 40℃ for 24 h to obtain spiral biomimetic spider silk. After hydroxylating the spiral-shaped biomimetic spider silk with a silane coupling agent, it was soaked in a mineralization solution containing 2% microorganisms at a mass ratio of 1:100-200. 0.01-0.03 times the mass of the biomimetic spider silk was added as photoresponsive nanomaterials. A mixed LED light source with a blue, green, and red light ratio of 3:2:1, a light intensity of 1000 lux, and parallel illumination at 25-35℃ was used for 30 minutes. The mineralization cycle of "30 minutes of illumination - 90 minutes of rest" was carried out until a honeycomb-shaped mineralization layer was formed. Then, the biomimetic spider silk with a sandwich structure of "fiber-mineralization layer-fiber" was formed through "deposition-adsorption". It was dried at 30-40℃ to constant weight to obtain the self-made biomimetic spider silk solid. (2) Add lactic acid with a purity ≥98% to the reactor, and add p-toluenesulfonic acid at a mass ratio of lactic acid to p-toluenesulfonic acid of 100:

3. Perform a prepolymerization reaction at 100-120℃ for 2 hours. After the prepolymerization reaction is completed, gradually increase the reaction temperature to 180-220℃ and maintain a vacuum of 10 -3 Polycondensation reaction was carried out at kPa; the polylactic acid obtained by the above polycondensation reaction was dissolved in dichloromethane at a volume ratio of 1:15 to obtain a polylactic acid solution; polyvinyl alcohol was used as a surfactant and dissolved in deionized water to prepare a polyvinyl alcohol aqueous solution with a mass concentration of 1-3% as an aqueous phase solution; the polylactic acid solution and the aqueous phase solution were injected into the flow channel of the microfluidic chip at a flow rate ratio of 1:5 by an injection pump. At the junction of the flow channels, the two fluids interacted. The polylactic acid solution formed droplets under the action of the aqueous phase solution, and then contracted under the action of surface tension to form microcavities, thus obtaining polylactic acid containing microcavities. Polylactic acid containing microcavities, anhydrous calcium chloride, and an organic solvent were uniformly mixed at a mass ratio of 10:1:

100. After sonication at 30–35°C and 40–50 kHz for 30 min, the mixture was dried at 40°C for 6 h to obtain polylactic acid filled with anhydrous calcium chloride. Polyvinyl alcohol and ethylene glycol copolymer, polylactic acid filled with anhydrous calcium chloride, catalyst, and organic solvent were then mixed at a mass ratio of 10:5:0.5:

150. After stirring at 30–35°C and 300–400 rpm for 4–6 h, the mixture was electrospun for 2–6 h and dried at 40°C for 6 h to obtain self-made composite nanofibers. (3) Mix 300-400 parts by weight of cement, 600-800 parts by weight of sand, 1100-1300 parts by weight of stone, 160-200 parts by weight of water, 5 parts by weight of admixture, 3-5 parts by weight of self-made biomimetic spider silk solid, 3-5 parts by weight of self-made composite fiber, and 60-100 parts by weight of admixture at 500 rpm to obtain crack-resistant and freeze-resistant fiber composite concrete. The photoresponsive nanomaterial in step (1) is a molybdenum sulfide particle with a diameter of 20 nm; The mineralization cycle and deposition-adsorption method described in step (1) are as follows: under the above-mentioned light parameters, the mineralization solution is irradiated for 30 minutes to induce the mineralization direction, and then left to stand for 90 minutes to allow the mineralization to grow. This cycle is repeated 4 to 6 times until a honeycomb mineralization layer is formed. The biomimetic spider silk with a mineralization layer deposited is placed in a new spinning solution to adsorb a new biomimetic spider silk layer, forming a "fiber-mineralization layer-fiber" sandwich structure of biomimetic spider silk.

2. The crack-resistant and freeze-thaw-resistant fiber-reinforced composite concrete according to claim 1, characterized in that, The diameter of the biomimetic spider silk in step (1) is 10 nm.

3. The crack-resistant and freeze-thaw-resistant fiber-reinforced composite concrete according to claim 1, characterized in that, The microorganism mentioned in step (1) is Pasteurella multocida.

4. The crack-resistant and freeze-thaw-resistant fiber-reinforced composite concrete according to claim 1, characterized in that, The polylactic acid containing microchambers in step (2) has a molecular weight of 100,000 to 150,000 and a microchamber particle size of 20 µm.

5. The crack-resistant and freeze-thaw-resistant fiber-reinforced composite concrete according to claim 1, characterized in that, The organic solvent in step (2) is a mixture of dichloromethane and N,N-dimethylformamide in a volume ratio of 3:

1.

6. The crack-resistant and freeze-thaw-resistant fiber-reinforced composite concrete according to claim 1, characterized in that, The molecular weight of the polyvinyl alcohol-ethylene glycol copolymer in step (2) is 5000-10000, and it is nanoscale.

7. The crack-resistant and freeze-thaw-resistant fiber-reinforced composite concrete according to claim 1, characterized in that, The catalyst in step (2) is p-toluenesulfonic acid.

8. The crack-resistant and freeze-thaw-resistant fiber-reinforced composite concrete according to claim 1, characterized in that, The particle size of the self-made composite nanofibers in step (2) is 50 nm.

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