Preparation method of coated microbial self-repairing capsule suitable for cement-based material
By using maifanite to prepare a three-layer microbial self-healing capsule, the problems of single carrier function and poor compatibility were solved, the reaction efficiency of MIP and the mechanical properties of concrete were improved, and an environmentally friendly self-healing effect was achieved.
Patent Information
- Application Number
- CN202511258878.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-04
- Publication Date
- 2025-12-12
AI Technical Summary
Existing microbial self-healing microcapsules have problems such as limited carrier function, poor compatibility with microorganisms and cement-based materials, and impact on the MIP reaction process and the mechanical properties of concrete.
Using maifanite as the core material, a three-layer microbial self-healing capsule was prepared, including a bacterial core material, a repair component coating layer, and a protective component coating layer. The self-healing capsule was formed through steps such as drying, sterilization, and coating, which improved the efficiency of the MIP reaction and mechanical properties.
This invention achieves multifunctionality, environmental friendliness, improved mechanical properties, and economic feasibility of microbial self-healing capsules, enhances the efficiency of the MIP reaction, and ensures the activity of microorganisms and the durability of cement-based materials.
Smart Images
Figure CN121107733A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of geotechnical engineering technology and relates to a method for preparing encapsulated microbial self-healing capsules suitable for cement-based materials. Specifically, it is a method for preparing microbial self-healing microcapsules using maifanite particles based on the MICP principle. Background Technology
[0002] Cement-based materials, as the most important building materials in construction projects, directly affect the safety and durability of building structures. However, during service, cement-based materials are susceptible to cracking due to external loads, temperature changes, acid rain, and other factors. The presence of cracks allows harmful ions to penetrate the cement-based material, reducing its durability and load-bearing capacity. If damaged areas are not repaired in time, structural failure can occur, seriously threatening people's lives and property. Therefore, repair and reinforcement work on cement-based materials is urgently needed.
[0003] Traditional methods for repairing cement-based materials primarily rely on external intervention, representing passive repair. Common techniques include surface treatment, injection grouting, and replacement. While these methods can restore performance, they are typically costly, complex to implement, require interruption of structural use, and struggle to completely repair internal microcracks, resulting in limited long-term effectiveness. To overcome the shortcomings of traditional methods, self-healing technologies have emerged. These methods achieve active crack healing by pre-installing repair mechanisms within the material, such as chemical repair, physical repair, and microbial repair. Among these, microbial self-healing technology utilizes the natural mineralization of microorganisms, creating self-healing microcapsules to "embed" repair capabilities within the carrier material. This approach boasts low energy consumption, low carbon emissions, and broad applicability, not only improving the durability and sustainability of cement-based structures but also reducing maintenance costs.
[0004] Recent years have seen some breakthroughs in the preparation of self-healing microcapsules, but several issues regarding carrier materials remain to be addressed. (Research Progress on Microbial Self-Healing Concrete Carrier Materials)
[0005] The article "[J]" (Hou Fuxing, Xi'an Jiaotong University, 2024) points out that current research on carrier materials focuses only on protecting microorganisms, and the overall performance is not ideal. Not only is the compatibility with microorganisms poor, but it may also affect the mineralization deposition ability of microorganisms and the mechanical properties of cement-based materials. The article "Research Progress on Repair Technology of Concrete Surface Defects and Cracks Based on Microbial Induced Mineralization" (Qian Chunxiang, Ren Lifu, Luo Mian, Journal of the Chinese Ceramic Society, 2015, 43(05): 619-631) points out that immobilizing bacterial spores and essential substances for bacterial survival and mineralization in ceramsite can extend the effective repair effect of bacteria to more than 6 months. However, this still cannot meet the requirements of actual concrete engineering applications. This shows that the interconnected pore structure of porous carriers cannot completely protect bacteria from the damage of the concrete environment. This puts forward higher requirements for microcapsule encapsulation technology, mechanical properties, compatibility with microorganisms, and matching degree with concrete structure. In addition, current organic microcapsules (such as polyurea formaldehyde and PMMA shells) are mainly prepared by in-situ polymerization. Although they are easy to prepare and have good flexibility, they have defects such as poor thermal stability, low mechanical strength and mismatch with the density of cement matrix. Encapsulated microcapsules not only have strong thermal stability and density matching with cement-based materials, but also form chemical bonds with cement hydration products through inorganic shells, which can effectively improve self-healing efficiency.
[0006] In summary, existing microbial self-healing microcapsules have the following problems:
[0007] 1. The carrier has a single function and its overall performance is not ideal;
[0008] 2. The use of organic materials as carriers not only results in poor compatibility with microorganisms and cement-based materials, affecting the MIP reaction process, but also releases a certain amount of free formaldehyde during the preparation of materials such as urea-formaldehyde resin, which is harmful to human health.
[0009] 3. When repairing concrete, excessive use of additives can affect the mechanical properties and durability of the concrete. Summary of the Invention
[0010] The technical problem to be solved by the present invention is to overcome the problems pointed out in the background art. That is, the purpose of the present invention is to provide a method for encapsulated microbial self-healing capsules suitable for cement-based materials, using maifanite as the core material, which not only realizes the multi-functionality of the carrier, but also improves the reaction efficiency of MIP and the strength of concrete.
[0011] The objective of this invention is achieved by providing a method for preparing a self-healing microbial capsule suitable for cement-based materials. This self-healing microbial capsule, from the inside out, consists of a bacterial core, a repair component encapsulation layer, and a protective component encapsulation layer. The preparation method includes the following steps:
[0012] Step 1, pretreatment of the core material, wherein the core material is spherical maifanite particles with a particle size of 1mm to 2mm. The pretreatment includes drying and high-temperature sterilization of the spherical maifanite particles, and then placing them in a sterile environment to cool to room temperature for later use.
[0013] Step 2, preparation of coating powder, including preparation of repair component powder and protective component powder;
[0014] Step 3, preparation of bacterial culture, including preparation of culture medium, preparation and measurement of bacterial culture, when...
[0015] OD 600 When the OD value is between 1.2 and 1.8, the bacterial culture preparation is complete. 600 The absorbance of the bacterial solution at a wavelength of 600 nm;
[0016] Step 4, preparation of the bacterial core material. Specifically, firstly, the spherical maifanite particles are soaked in the bacterial solution cultured in step 3 and allowed to stand for a period of time. Then, they are dried to a given degree of dryness C1 to obtain the bacterial core material, namely the bacterial spherical maifanite particles.
[0017] Step 5: Using a granulator, the bacteria-carrying spherical maifanite particles are sequentially coated with repair component powder and protective component powder to obtain a semi-finished self-repairing capsule containing two coating layers.
[0018] Step 6: Remove the semi-finished self-healing capsules from the granulator and dry them until the final dryness C2 is reached. At this point, the preparation of the encapsulated microbial self-healing capsules is complete.
[0019] Preferably, the implementation process of step 1 is as follows:
[0020] First, spherical maifanite particles with a particle size of 1mm to 2mm are screened out, and the sieved spherical maifanite particles are dried in an environment of 50℃ to 70℃. Second, the dried spherical maifanite particles are sterilized at 121℃ for 30 minutes. After sterilization, they are placed in a sterile environment and left to cool to room temperature before use.
[0021] Preferably, the implementation process of step 2 is as follows:
[0022] Step 2.1, Preparation of Repair Component Powder
[0023] Anhydrous calcium chloride and urea were mixed in a molar ratio of 1:1, then pulverized thoroughly in a pulverizer, and then passed through a 200-mesh sieve. After sieving, the mixture was stored in a sealed bag as a binder powder for later use.
[0024] Ammonium chloride, tris(hydroxymethyl)aminomethane, and yeast extract powder are mixed and stirred evenly in a mass ratio of 10:15.75:20. Then, they are mixed with the binder powder in a ratio of 1:10. After mixing, the mixture is placed in a pulverizer and pulverized thoroughly. The powder obtained after sieving is the repair component powder.
[0025] Step 2.2, Preparation of protective component powder
[0026] Low-alkalinity sulfoaluminate cement and fly ash are mixed in a mass ratio of 4:1 and stirred evenly to obtain the protective component powder.
[0027] The prepared repair component powder and protective component powder are placed in sealed bags for storage until use.
[0028] Preferably, the implementation process of step 3 is as follows:
[0029] The culture medium was prepared using the formula ATCC1376NH4-YE recommended by the American Culture Collection Center. The culture medium was then placed in an autoclave for sterilization. The sterilization time was set to 30 minutes and the autoclave temperature was set to 121°C. The culture medium was then placed on a clean bench for UV sterilization and ventilation. It was used when the temperature of the culture medium dropped to room temperature.
[0030] After the culture medium has cooled to room temperature, take the culture medium into a container and add Bacillus buskieri into the culture medium using a sterile pipette to obtain a bacterial solution. The volume ratio of Bacillus buskieri to culture medium is 1:100. Place the bacterial solution in an incubator for incubation. Set the incubator temperature to 28℃~32℃, the oscillation frequency to 200 times / min~320 times / min, and the incubation time to 24h~72h.
[0031] Measure the absorbance of the bacterial solution obtained in step 1.2 at a wavelength of 600 nm, i.e., OD. 600 Value, in OD 600 Take it out when the value is between 1.2 and 1.8 and set aside for later use.
[0032] Preferably, the implementation process of step 4 is as follows:
[0033] First, place the sterilized and cooled spherical maifan stone particles into a clean, corrosion-resistant container, pour in the cultured bacterial solution, ensuring the bacterial solution covers the maifan stone particles by 2cm to 3cm, and let it stand in a clean and uncontaminated environment for 30min to 45min.
[0034] Next, the above-treated spherical maifanite particles are placed in a temperature-controlled drying device and dried to a given dryness degree C1 to obtain the bacterial core material, namely bacterial spherical maifanite particles.
[0035] The drying temperature of the temperature-controlled drying equipment is set to 35℃~40℃. After drying, the bacteria-laden maifanite granules are placed in a sealed bag for later use.
[0036] Preferably, the implementation process of step 5 is as follows:
[0037] Step 5.1: Place the bacteria-loaded spherical maifanite granules into the granulator, start the granulator, and adjust the rotation speed parameters to ensure that the bacteria-loaded maifanite granules maintain a uniform rolling state in the machine cavity without jumping or splashing.
[0038] Once the bacteria-carrying spherical maifanite particles are in a stable and uniform rolling state, the binder is sprayed in until the surface is wet. Repair component powder is added to coat the surface of the bacteria-carrying spherical maifanite particles. The rotation speed and the amount of binder sprayed are adjusted in real time according to the coating condition to ensure that the bacteria-carrying spherical maifanite particles maintain a uniform rolling state in the machine cavity, so as to ensure uniform coating.
[0039] When the repair component is coated to a given layer thickness A1, stop adding repair component powder and spraying binder, adjust the granulator speed to 72 r / min, and polish and round it to obtain a self-healing capsule containing only the repair coating layer;
[0040] Step 5.2: Remove the self-healing capsule containing only the repair coating layer and place it in a temperature-controlled drying device to dry it, so as to remove excess moisture from the coating process; the drying temperature is set to 35℃~40℃ and the drying time is set to 20min~40min.
[0041] Step 5.3: Place the dried self-healing capsule containing only the repair coating layer back into the granulator, start the granulator, and adjust the rotation speed parameters to ensure that the self-healing capsule containing only the repair coating layer maintains a uniform rolling state in the machine cavity without jumping or splashing.
[0042] Once the self-healing capsule containing only the repair coating layer is in a stable and uniform rolling state, the adhesive is sprayed in until the surface is wetted. Protective component powder is added to coat the surface of the self-healing capsule containing only the repair coating layer. The rotation speed and adhesive spraying are adjusted in real time according to the coating situation to ensure that the self-healing capsule containing only the repair coating layer maintains a uniform rolling state in the machine cavity, so as to ensure uniform coating.
[0043] When the protective component powder is coated to a given layer thickness A2, the addition of protective component powder is stopped, the granulator speed is adjusted to 72r / min, and polishing and rounding are performed to obtain a self-healing capsule containing two coating layers.
[0044] Step 5.4: Hot air is introduced into the granulator cavity to dry the self-healing capsule containing two encapsulation layers until there is no obvious moisture on its surface. Then, an appropriate amount of water is sprayed in to moisten the surface, and hot air is introduced again to perform the drying and water spraying cycle until the given number of cycles B is reached, and the semi-finished self-healing capsule is obtained.
[0045] Preferably, the given layer thickness A1 and the given layer thickness A2 are both 1.0 mm to 1.5 mm; the given number of cycles B is 4 to 7 times.
[0046] Preferably, the moisture content of both the given dryness C1 in step 2 and the final dryness C2 in step 7 is less than 5%.
[0047] Compared with the prior art, the beneficial effects of the present invention include:
[0048] 1. This invention achieves the multifunctionality of microbial self-healing microcapsules. In this invention, maifanite is used as the core material. Besides serving as a carrier for Bacillus pasteurellii attachment, it can efficiently enrich heavy metal ions, significantly improving the efficiency of the MIP reaction. Furthermore, due to its excellent bidirectional pH regulation, maifanite provides a favorable growth and metabolic environment for microorganisms, ensuring their activity.
[0049] 2. This invention achieves environmentally friendly microcapsule preparation. It abandons traditionally used organic carrier materials that may release free formaldehyde (such as urea-formaldehyde resin) or other harmful substances. The maifan stone used in this invention is a natural inorganic mineral, and its processing does not require the use of strong acids or alkalis, thus releasing no toxic or harmful substances.
[0050] 3. This invention improves the mechanical properties and environmental stability of microcapsules while reducing the negative impact on the properties of the matrix material. Compared with traditional organic microcapsules, maifanite itself has higher mineral strength, and its excellent compatibility with cement-based materials and moderate density allow it to be uniformly distributed in the cement matrix, thereby more effectively reducing the additional porosity introduced by the incorporation of microcapsules.
[0051] 4. This invention has certain economic feasibility. Maifan stone mineral resources are abundant, inexpensive, and the processing is relatively simple and environmentally friendly. Its excellent adsorption properties, bioactivity promoting ability, and environmental stability enable maifan stone-based microcapsules to not only efficiently remediate pollution but also possess long-lasting effects and reliability.
[0052] 5. The self-repairing capsule of this invention employs a three-layer structure to enhance the efficiency of the MIP reaction and ensure microbial activity, while also exhibiting environmental friendliness, superior mechanical properties, and environmental stability. In this three-layer structure, the core consists of bacteria-laden maifanite particles carrying Bacillus pasteurellii, which plays a primary role in the repair process; the middle layer contains repair components that provide conditions for the reactivation of Bacillus pasteurellii while also acting as a binding material in the MIP reaction; the outermost layer is a protective component used to reduce the impact of the external environment on the internal components of the encapsulated microbial self-repairing capsule. Attached Figure Description
[0053] Figure 1 This is a flowchart of the preparation method of the present invention.
[0054] Figure 2 This is a schematic diagram of the encapsulated microbial self-healing capsule structure described in this invention.
[0055] Figure 3 This is a test diagram of the integrated encapsulated microbial self-healing capsule and cement-based material of the present invention.
[0056] Figure 4 This is a graph showing the trend of urease activity changes in the encapsulated microbial self-repair capsule of the present invention. Detailed Implementation
[0057] The method of the present invention will be further described in detail below with reference to the embodiments.
[0058] Figure 2 The diagram shows the structure of the encapsulated microbial self-healing capsule of the present invention. As can be seen from the diagram, the encapsulated microbial self-healing capsule consists of a bacterial core material, a repair component encapsulation layer, and a protective component encapsulation layer from the inside out.
[0059] The core consists of bacteria-laden maifanite particles, which carry Bacillus pasteurellii and play a major role in repair. The middle layer is a repair component that provides conditions for the reactivation of Bacillus pasteurellii while also participating in the MICP reaction as a binding material. The outermost layer is a protective component used to reduce the impact of the external environment on the internal components of the encapsulated microbial self-repair capsule.
[0060] Figure 1 This is a flowchart of the present invention. As can be seen from the flowchart, the present invention includes the following steps:
[0061] Step 1, pretreatment of the core material, wherein the core material is spherical maifanite particles with a particle size of 1mm to 2mm. The pretreatment includes drying and high-temperature sterilization of the spherical maifanite particles, and then placing them in a sterile environment to cool to room temperature before use.
[0062] The implementation process of step 1 is as follows:
[0063] First, spherical maifanite particles with a particle size of 1mm to 2mm are screened out, and the sieved spherical maifanite particles are dried in an environment of 50℃ to 70℃. Second, the dried spherical maifanite particles are sterilized at 121℃ for 30 minutes. After sterilization, they are placed in a sterile environment and left to cool to room temperature before use.
[0064] In this embodiment, the particle size is selected as 1.5 mm, the drying temperature is 60°C, the sterilization temperature is 121°C, and the sterilization time is 30 min.
[0065] Step 2, preparation of coating powder, including preparation of repair component powder and protective component powder.
[0066] The implementation process of step 2 is as follows:
[0067] Step 2.1, Preparation of Repair Component Powder
[0068] Anhydrous calcium chloride and urea were mixed in a molar ratio of 1:1, then pulverized thoroughly in a pulverizer, and then passed through a 200-mesh sieve. After sieving, the mixture was stored in a sealed bag as a binder powder for later use.
[0069] Ammonium chloride, tris(hydroxymethyl)aminomethane, and yeast extract powder are mixed and stirred evenly in a mass ratio of 10:15.75:20. Then, they are mixed with the binder powder in a ratio of 1:10. After mixing, the mixture is placed in a pulverizer and pulverized thoroughly. The powder obtained after sieving is the repair component powder.
[0070] Step 2.2, Preparation of protective component powder
[0071] Low-alkalinity sulfoaluminate cement and fly ash are mixed in a mass ratio of 4:1 and stirred evenly to obtain the protective component powder.
[0072] The prepared repair component powder and protective component powder are placed in sealed bags for storage until use.
[0073] Step 3, preparation of bacterial culture, including preparation of culture medium, preparation and measurement of bacterial culture, when OD 600 When the OD value is between 1.2 and 1.8, the bacterial culture preparation is complete. 600 The absorbance of the bacterial solution is measured at a wavelength of 600 nm.
[0074] The implementation process of step 3 is as follows:
[0075] The culture medium was prepared using the formula ATCC1376NH4-YE recommended by the American Culture Collection Center. The culture medium was then placed in an autoclave for sterilization. The sterilization time was set to 30 minutes and the autoclave temperature was set to 121°C. The culture medium was then placed on a clean bench for UV sterilization and ventilation. It was used when the temperature of the culture medium dropped to room temperature.
[0076] After the culture medium has cooled to room temperature, take the culture medium into a container and add Bacillus buskieri into the culture medium using a sterile pipette to obtain a bacterial solution. The volume ratio of Bacillus buskieri to culture medium is 1:100. Place the bacterial solution in an incubator for incubation. Set the incubator temperature to 28℃~32℃, the oscillation frequency to 200 times / min~320 times / min, and the incubation time to 24h~72h.
[0077] Measure the absorbance of the bacterial solution obtained in step 1.2 at a wavelength of 600 nm, i.e., OD. 600 Value, in OD 600 Take it out when the value is between 1.2 and 1.8 and set aside for later use.
[0078] In this embodiment, the incubator temperature is set to 30°C, the oscillation frequency is set to 280 times / min, and the incubation time is set to 48 hours.
[0079] Step 4, preparation of the bacterial core material. Specifically, firstly, the spherical maifanite particles are soaked in the bacterial solution cultured in step 3 and allowed to stand for a period of time. Then, they are dried to a given dryness degree C1 to obtain the bacterial core material, namely the bacterial spherical maifanite particles.
[0080] The implementation process of step 4 is as follows:
[0081] First, place the sterilized and cooled spherical maifan stone particles into a clean, corrosion-resistant container, pour in the cultured bacterial solution, ensuring the bacterial solution covers the maifan stone particles by 2cm to 3cm, and let it stand in a clean and uncontaminated environment for 30min to 45min.
[0082] Next, the above-treated spherical maifanite particles are placed in a temperature-controlled drying device and dried to a given dryness degree C1 to obtain the bacterial core material, namely bacterial spherical maifanite particles.
[0083] The drying temperature of the temperature-controlled drying equipment is set to 35℃~40℃. After drying, the bacteria-laden maifanite granules are placed in a sealed bag for later use.
[0084] In this embodiment, the bacterial solution was submerged 2 cm above the maifanite particles and left to stand for 35 minutes in a clean and uncontaminated environment.
[0085] Step 5: Using a granulator, the bacteria-laden spherical maifanite particles are sequentially coated with repair component powder and protective component powder to obtain a semi-finished self-healing capsule containing two coating layers.
[0086] The implementation process of step 5 is as follows:
[0087] Step 5.1: Place the bacteria-loaded spherical maifanite granules into the granulator, start the granulator, and adjust the rotation speed parameters to ensure that the bacteria-loaded maifanite granules maintain a uniform rolling state in the machine cavity without jumping or splashing.
[0088] Once the bacteria-carrying spherical maifanite particles are in a stable and uniform rolling state, the binder is sprayed in until the surface is wet. Repair component powder is added to coat the surface of the bacteria-carrying spherical maifanite particles. The rotation speed and the amount of binder sprayed are adjusted in real time according to the coating condition to ensure that the bacteria-carrying spherical maifanite particles maintain a uniform rolling state in the machine cavity, so as to ensure uniform coating.
[0089] When the repair component is coated to a given layer thickness A1, stop adding repair component powder and spraying binder, adjust the granulator speed to 72 r / min, and polish and round it to obtain a self-healing capsule containing only the repair coating layer;
[0090] Step 5.2: Remove the self-healing capsule containing only the repair coating layer and place it in a temperature-controlled drying device to dry it, so as to remove excess moisture from the coating process; the drying temperature is set to 35℃~40℃ and the drying time is set to 20min~40min.
[0091] Step 5.3: Place the dried self-healing capsule containing only the repair coating layer back into the granulator, start the granulator, and adjust the rotation speed parameters to ensure that the self-healing capsule containing only the repair coating layer maintains a uniform rolling state in the machine cavity without jumping or splashing.
[0092] Once the self-healing capsule containing only the repair coating layer is in a stable and uniform rolling state, the adhesive is sprayed in until the surface is wetted. Protective component powder is added to coat the surface of the self-healing capsule containing only the repair coating layer. The rotation speed and adhesive spraying are adjusted in real time according to the coating situation to ensure that the self-healing capsule containing only the repair coating layer maintains a uniform rolling state in the machine cavity, so as to ensure uniform coating.
[0093] When the protective component powder is coated to a given layer thickness A2, the addition of protective component powder is stopped, the granulator speed is adjusted to 72r / min, and polishing and rounding are performed to obtain a self-healing capsule containing two coating layers.
[0094] Step 5.4: Hot air is introduced into the granulator cavity to dry the self-healing capsule containing two encapsulation layers until there is no obvious moisture on its surface. Then, an appropriate amount of water is sprayed in to moisten the surface, and hot air is introduced again to perform the drying and water spraying cycle until the given number of cycles B is reached, and the semi-finished self-healing capsule is obtained.
[0095] In this embodiment, the given layer thickness A1 and the given layer thickness A2 are both 1.0 mm to 1.5 mm; the given number of cycles B is 4 to 7 times. The drying temperature in step 5.2 is set to 35°C, and the drying time is set to 30 min.
[0096] Step 6: Remove the semi-finished self-healing capsules from the granulator and dry them until the final dryness C2 is reached. At this point, the preparation of the encapsulated microbial self-healing capsules is complete.
[0097] In this embodiment, the moisture content of both the given dryness degree C1 in step 2 and the final dryness degree C2 in step 7 is less than 5%.
[0098] Figure 3 This invention relates to a test combining a self-healing microbial capsule with a cement-based material. Figure 3 During the study, the morphological changes of encapsulated microbial self-healing capsules in cement-based materials were observed. The protective components and cement-based materials were well integrated, and no obvious boundary was observed within 22.5 hours.
[0099] Figure 4 This is a curve showing the change in urease activity over time during the fabrication of the encapsulated microbial self-repair capsules of this invention and after 7 days of storage. The vertical axis represents urease activity, and the horizontal axis represents time. The mass ratio of the encapsulated microbial self-repair capsules to the culture medium was 1:100, totaling 100 ml, which was then cultured in a constant temperature shaking incubator at 30°C and a shaking frequency of 300 rpm. The experimental results show that the Bacillus pasteurellii in the encapsulated microbial self-repair capsules were not completely dead and still possessed certain biological activity, capable of secreting urease to complete the biomineralization reaction.
Claims
1. A method for preparing encapsulated microbial self-healing capsules suitable for cement-based materials, characterized in that, This encapsulated microbial self-healing capsule consists of a bacterial core, a repair component encapsulation layer, and a protective component encapsulation layer from the inside out. The preparation method includes the following steps: Step 1, pretreatment of the core material, wherein the core material is spherical maifanite particles with a particle size of 1mm to 2mm. The pretreatment includes drying and high-temperature sterilization of the spherical maifanite particles, and then placing them in a sterile environment to cool to room temperature for later use. Step 2, preparation of coating powder, including preparation of repair component powder and protective component powder; Step 3, preparation of bacterial culture, including preparation of culture medium, preparation and measurement of bacterial culture, when OD 600 When the OD value is between 1.2 and 1.8, the bacterial culture preparation is complete. 600 The absorbance of the bacterial solution at a wavelength of 600 nm; Step 4, preparation of the bacterial core material. Specifically, firstly, the spherical maifanite particles are soaked in the bacterial solution cultured in step 3 and allowed to stand for a period of time. Then, they are dried to a given degree of dryness C1 to obtain the bacterial core material, namely the bacterial spherical maifanite particles. Step 5: Using a granulator, the bacteria-carrying spherical maifanite particles are sequentially coated with repair component powder and protective component powder to obtain a semi-finished self-repairing capsule containing two coating layers. Step 6: Remove the semi-finished self-healing capsules from the granulator and dry them until the final dryness C2 is reached. At this point, the preparation of the encapsulated microbial self-healing capsules is complete.
2. The method for preparing encapsulated microbial self-healing capsules suitable for cement-based materials according to claim 1, characterized in that, The implementation process of step 1 is as follows: First, spherical maifanite particles with a particle size of 1mm to 2mm are screened out, and the sieved spherical maifanite particles are dried in an environment of 50℃ to 70℃. Second, the dried spherical maifanite particles are sterilized at 121℃ for 30 minutes. After sterilization, they are placed in a sterile environment and left to cool to room temperature before use.
3. The method for preparing encapsulated microbial self-healing capsules suitable for cement-based materials according to claim 1, characterized in that, The implementation process of step 2 is as follows: Step 2.1, Preparation of Repair Component Powder Anhydrous calcium chloride and urea were mixed in a molar ratio of 1:1, then pulverized thoroughly in a pulverizer, and then passed through a 200-mesh sieve. After sieving, the mixture was stored in a sealed bag as a binder powder for later use. Ammonium chloride, tris(hydroxymethyl)aminomethane, and yeast extract powder were mixed and stirred evenly in a mass ratio of 10:15.75:
20. Then, they were mixed with the binder powder in a ratio of 1:
10. After mixing, the mixture was placed in a pulverizer and pulverized thoroughly. The powder obtained after sieving was the repair component powder. Step 2.2, Preparation of protective component powder Low-alkalinity sulfoaluminate cement and fly ash are mixed in a mass ratio of 4:1 and stirred evenly to obtain the protective component powder. The prepared repair component powder and protective component powder are placed in sealed bags for storage until use.
4. The method for preparing encapsulated microbial self-healing capsules suitable for cement-based materials according to claim 1, characterized in that, The implementation process of step 3 is as follows: The culture medium was prepared using the formula ATCC1376NH4-YE recommended by the American Culture Collection Center. The culture medium was then placed in an autoclave for sterilization. The sterilization time was set to 30 minutes and the autoclave temperature was set to 121°C. The culture medium was then placed on a clean bench for UV sterilization and ventilation. It was used when the temperature of the culture medium dropped to room temperature. After the culture medium has cooled to room temperature, take the culture medium into a container and add Bacillus buskieri into the culture medium using a sterile pipette to obtain a bacterial solution. The volume ratio of Bacillus buskieri to culture medium is 1:
100. Place the bacterial solution in an incubator for incubation. Set the incubator temperature to 28℃~32℃, the oscillation frequency to 200 times / min~320 times / min, and the incubation time to 24h~72h. Measure the absorbance of the bacterial solution obtained in step 1.2 at a wavelength of 600 nm, i.e., OD. 600 Value, in 0D 600 Take it out when the value is between 1.2 and 1.8 and set aside for later use.
5. The method for preparing encapsulated microbial self-healing capsules suitable for cement-based materials according to claim 1, characterized in that, The implementation process of step 4 is as follows: First, place the sterilized and cooled spherical maifan stone particles into a clean, corrosion-resistant container, pour in the cultured bacterial solution, ensuring the bacterial solution covers the maifan stone particles by 2cm to 3cm, and let it stand in a clean and uncontaminated environment for 30min to 45min. Next, the above-treated spherical maifanite particles are placed in a temperature-controlled drying device and dried to a given dryness degree C1 to obtain the bacterial core material, namely the bacterial-loaded spherical maifanite particles. The drying temperature of the temperature-controlled drying equipment is set to 35℃~40℃. After drying, the bacteria-laden maifanite granules are placed in a sealed bag for later use.
6. The method for preparing encapsulated microbial self-healing capsules suitable for cement-based materials according to claim 1, characterized in that, The implementation process of step 5 is as follows: Step 5.1: Place the bacteria-loaded spherical maifanite granules into the granulator, start the granulator, and adjust the rotation speed parameters to ensure that the bacteria-loaded maifanite granules maintain a uniform rolling state in the machine cavity without jumping or splashing. Once the bacteria-carrying spherical maifanite particles are in a stable and uniform rolling state, the binder is sprayed in until the surface is wet. Repair component powder is added to coat the surface of the bacteria-carrying spherical maifanite particles. The rotation speed and the amount of binder sprayed are adjusted in real time according to the coating condition to ensure that the bacteria-carrying spherical maifanite particles maintain a uniform rolling state in the machine cavity, so as to ensure uniform coating. When the repair component is coated to a given layer thickness A1, stop adding repair component powder and spraying binder, adjust the granulator speed to 72 r / min, and polish and round it to obtain a self-healing capsule containing only the repair coating layer; Step 5.2: Remove the self-healing capsule containing only the repair coating layer and place it in a temperature-controlled drying device to dry it, so as to remove excess moisture from the coating process; the drying temperature is set to 35℃~40℃ and the drying time is set to 20min~40min. Step 5.3: Place the dried self-healing capsule containing only the repair coating layer back into the granulator, start the granulator, and adjust the rotation speed parameters to ensure that the self-healing capsule containing only the repair coating layer maintains a uniform rolling state in the machine cavity without jumping or splashing. Once the self-healing capsule containing only the repair coating layer is in a stable and uniform rolling state, the adhesive is sprayed in until the surface is wetted. Protective component powder is added to coat the surface of the self-healing capsule containing only the repair coating layer. The rotation speed and adhesive spraying are adjusted in real time according to the coating situation to ensure that the self-healing capsule containing only the repair coating layer maintains a uniform rolling state in the machine cavity, so as to ensure uniform coating. When the protective component powder is coated to a given layer thickness A2, the addition of protective component powder is stopped, the granulator speed is adjusted to 72r / min, and polishing and rounding are performed to obtain a self-healing capsule containing two coating layers. Step 5.4: Hot air is introduced into the granulator cavity to dry the self-healing capsule containing two encapsulation layers until there is no obvious moisture on its surface. Then, an appropriate amount of water is sprayed in to moisten the surface, and hot air is introduced again to perform the drying and water spraying cycle until the given number of cycles B is reached, and the semi-finished self-healing capsule is obtained.
7. The method for preparing encapsulated microbial self-healing capsules suitable for cement-based materials according to claim 6, characterized in that, The given layer thickness A1 and the given layer thickness A2 are both 1.0 mm to 1.5 mm; the given number of cycles B is 4 to 7 times.
8. The method for preparing encapsulated microbial self-healing capsules suitable for cement-based materials according to claim 1, characterized in that, The moisture content of both the given dryness degree C1 in step 2 and the final dryness degree C2 in step 7 is less than 5%.