Method for self-repairing of concrete cracks by secondary biological materials

Abstract

The application discloses a concrete crack secondary biological material self-repairing method and belongs to the technical field of microbial self-repairing; the method comprises the following steps: firstly, wetting the surface of a concrete crack with deionized water; secondly, brushing a microbial self-repairing slurry on the surface of the concrete crack under a negative pressure condition and standing; thirdly, exposing the concrete to the sea for 30-300 days to enable the surface of the concrete to adsorb marine organisms to form a biological adhesion layer; and the microbial self-repairing slurry is prepared by mixing and preparing a bacillus pasteurii bacterial liquid and a cementing liquid. The method provided by the application is used for brushing the microbial self-repairing slurry first and then exposing the concrete to the sea, which is helpful to effectively filling the surface layer pores of the concrete, thereby optimizing the surface layer pore structure and improving the durability of the concrete.

Description

Technical Field

[0001] This invention relates to the field of microbial self-healing technology, specifically to a method for self-healing concrete cracks using secondary biomaterials. Background Technology

[0002] As a core material in modern construction engineering, concrete plays an irreplaceable role in marine infrastructure construction. However, the harsh marine environment poses a severe challenge to concrete structures due to chloride ion corrosion, significantly impacting their service life. Traditional protective methods such as epoxy resin coatings and corrosion inhibitors are not only costly but also inherently flawed, including difficult maintenance and poor environmental compatibility. Against this backdrop, green protection technologies based on microbial mineralization have attracted considerable attention due to their environmentally friendly and self-healing properties.

[0003] Studies have shown that microbial induced calcium carbonate deposition (MICP) technology can efficiently generate calcite-type calcium carbonate precipitates through the urease catalysis of microorganisms such as Bacillus pasteurellii. Domestic innovative research has used biocompatible carriers such as sodium alginate and agar to immobilize microorganisms, successfully constructing a dense mineralized layer that significantly reduces the chloride ion diffusion coefficient of concrete. More complexly, chloride ion erosion and carbonation processes in marine environments exhibit a significant synergistic effect. When the width of concrete cracks is within the critical range of 150-370 μm, the crack topology becomes a key factor controlling the erosion process. Field observations show that chloride ion penetration in concrete in tidal zones exhibits a clear gradient distribution, with the most severe corrosion occurring in the transition zone between the splash zone and the tidal zone. Therefore, developing a new method for self-healing concrete cracks using secondary biomaterials not only has significant theoretical value but also provides an innovative solution for ensuring the long-term durability of marine engineering concrete structures. Summary of the Invention

[0004] The purpose of this invention is to provide a self-healing method for concrete cracks using secondary biomaterials, which effectively improves the concrete's resistance to chloride ion erosion and water seepage, thereby enhancing the concrete's durability.

[0005] The technical solution adopted by the present invention to achieve the above objectives is as follows:

[0006] A method for self-healing concrete cracks using secondary biomaterials includes: first, wetting the surface of the concrete cracks with deionized water; then, applying a microbial self-healing slurry to the surface of the concrete cracks under negative pressure and allowing it to stand; next, exposing the concrete to the sea for 30-300 days to allow the concrete surface to absorb marine organisms and form a biofilm layer; the microbial self-healing slurry is a mixture of bacterial solution and cementitious liquid; the volume ratio of the bacterial solution to the cementitious liquid is 1:0.2-2.

[0007] This invention first applies a microbial self-healing slurry to the surface of concrete cracks for primary biomaterial repair, effectively filling internal cracks, altering the internal porosity of the concrete, and improving its durability. Then, the concrete is exposed to the sea. The surface of the concrete coated with the microbial self-healing slurry is enriched with calcium ions from the cement and trace elements from microbial nutrients, effectively attracting marine organisms to attach and form a biofilm layer for secondary biomaterial repair. The bio-adhesive secreted by the marine organisms forms a biological protective layer on the concrete surface. This bio-adhesive exhibits radial adhesion characteristics, effectively filling surface cracks and blocking chloride ion intrusion, thereby improving concrete durability.

[0008] Preferably, in the preparation of the cementing solution, calcium acetate and urea are mixed, and deionized water is added and stirred evenly to obtain the cementing solution.

[0009] More preferably, the mass ratio of calcium acetate to urea is 1:0.2-1.

[0010] More preferably, the ratio of calcium acetate to deionized water is 1g:2-10mL.

[0011] Preferably, a regulator is added and stirred evenly during the preparation of the cementitious liquid to obtain the cementitious liquid. This invention uses a regulator obtained by reacting 4-(dimethylamino)butyraldehyde dimethyl acetal and 4-(bromoethane)phenylacetic acid; the regulator is then used to prepare a microbial self-healing grout, which may promote microbial transport and enhance its dispersion in concrete cracks by regulating the surface characteristics of microorganisms, thereby resulting in better calcium carbonate deposition and distribution, delaying chloride ion corrosion of concrete; simultaneously, it effectively blocks the pore structure of concrete cracks and reduces the relative permeability coefficient of the repaired concrete.

[0012] More preferably, in the preparation of the regulator, 4-(dimethylamino)butanol dimethyl acetal and acetonitrile are first mixed, and then reacted with 4-(bromoethane)phenylacetic acid to obtain the regulator.

[0013] More preferably, the ratio of 4-(dimethylamino)butyraldehyde dimethyl acetal to acetonitrile is 1g:2-10mL.

[0014] More preferably, the ratio of 4-(bromoethane)phenylacetic acid to acetonitrile is 1 g: 2-10 mL.

[0015] More preferably, the reaction temperature is 40-60℃.

[0016] Preferably, the bacterial solution is a Bacillus pasteurellium bacterial solution, OD 600 The value is 2.3-2.7.

[0017] More preferably, the preparation of the bacterial solution specifically involves,

[0018] After activating Bacillus pasteurellii, it was inoculated onto a solid slant culture medium and incubated statically at 20-30℃ for 20-30 hours. Then, the strain was inoculated into a liquid culture medium and incubated at 20-30℃ with a shaking speed of 100-200 rpm for 20-30 hours to obtain the bacterial solution.

[0019] More preferably, the solid slant culture medium comprises peptone, meat extract, urea, agar, and deionized water, wherein the mass ratio of peptone to meat extract is 1:0.2-1, the mass ratio of peptone to urea is 1:2-8, the mass ratio of peptone to agar is 1:1-5, and the volume ratio of peptone to deionized water is 1g:0.1-0.5L.

[0020] More preferably, the liquid culture medium comprises peptone, meat extract, urea and deionized water, wherein the mass ratio of peptone to meat extract is 1:0.2-1, the mass ratio of peptone to urea is 1:2-8, and the volume ratio of peptone to deionized water is 1g:0.1-0.5L.

[0021] Preferably, the preparation of the cementing solution specifically involves,

[0022] Calcium acetate and urea are mixed, and deionized water is added and stirred until homogeneous to obtain a cementitious solution.

[0023] More preferably, the mass ratio of calcium acetate to urea is 1:0.2-1.

[0024] More preferably, the ratio of calcium acetate to deionized water is 1g:2-10mL.

[0025] Preferably, the preparation of the cementing solution also includes the addition of a regulator, specifically,

[0026] Calcium acetate and urea are mixed, and a regulator and deionized water are added and stirred until homogeneous to obtain a cementing solution.

[0027] More preferably, the mass ratio of calcium acetate to urea is 1:0.2-1.

[0028] More preferably, the mass ratio of calcium acetate to regulator is 1:0.05-0.1.

[0029] More preferably, the ratio of calcium acetate to deionized water is 1g:2-10mL.

[0030] More preferably, the preparation of the regulator specifically involves,

[0031] 4-(dimethylamino)butanol dimethyl acetal and acetonitrile were mixed and stirred, and 4-(bromoethane)phenylacetic acid was added at 40-60℃ and reacted for 8-24 h. After the reaction was completed, the mixture was cooled to room temperature, and anhydrous diethyl ether was added to precipitate the precipitate. The precipitate was dried under vacuum to obtain the regulator.

[0032] More preferably, the ratio of 4-(dimethylamino)butyraldehyde dimethyl acetal to acetonitrile is 1g:2-10mL.

[0033] More preferably, the ratio of 4-(bromoethane)phenylacetic acid to acetonitrile is 1 g: 2-10 mL.

[0034] More preferably, the volume ratio of acetonitrile to anhydrous diethyl ether is 1:1-4.

[0035] More preferably, the preparation of the regulator specifically involves,

[0036] 4-(dimethylamino)butanal dimethyl acetal and acetonitrile were mixed and stirred. 4-(bromoethane)phenylacetic acid was added at 40-60℃ and reacted for 8-24 h. After the reaction was completed, the mixture was cooled to room temperature, and anhydrous diethyl ether was added to precipitate the precipitate. The precipitate was filtered and retained. Tetrahydrofuran was added and stirred to dissolve the precipitate. Thionyl chloride was added at 0-5℃, and the mixture was refluxed at 50-70℃ for 2-6 h. After the reaction was completed, methyl 7-aminoheptanoate was added, followed by the slow addition of triethylamine and 4-dimethylaminopyridine. The mixture was reacted at 30-50℃ for 0.5-2 h. The mixture was extracted with dichloromethane, and the organic layer was retained and washed 3-6 times with pure water. Anhydrous sodium sulfate was added and the mixture was dried. The mixture was filtered, the solvent was removed by rotary evaporation, and the mixture was dried under vacuum to obtain the conditioning agent. In the preparation of the regulator, the present invention further introduces methyl 7-aminoheptaate to react, which may enhance the metabolic activity of microorganisms by regulating the microbial mineralization reaction environment, promoting the deposition of calcium carbonate minerals, effectively blocking chloride ion penetration channels, and significantly reducing water penetration, thereby further improving the chloride ion erosion resistance and impermeability of the repaired concrete.

[0037] More preferably, the ratio of 4-(dimethylamino)butyraldehyde dimethyl acetal to acetonitrile is 1g:2-10mL.

[0038] More preferably, the ratio of 4-(bromoethane)phenylacetic acid to acetonitrile is 1 g: 2-10 mL.

[0039] More preferably, the volume ratio of acetonitrile to anhydrous diethyl ether is 1:1-4.

[0040] More preferably, the volume ratio of acetonitrile to tetrahydrofuran is 1:1-2.

[0041] More preferably, the volume ratio of acetonitrile to thionyl chloride is 1:1-2.

[0042] More preferably, the ratio of methyl 7-aminoheptaanoate to acetonitrile is 1g:2-10mL.

[0043] More preferably, the volume ratio of acetonitrile to triethylamine is 1:0.1-1.

[0044] More preferably, the volume ratio of triethylamine to 4-dimethylaminopyridine is 1:0.2-1.

[0045] More preferably, the volume ratio of acetonitrile to dichloromethane is 1:1-3.

[0046] More preferably, the mass ratio of 4-(dimethylamino)butyraldehyde dimethyl acetal to anhydrous sodium sulfate is 1:1-2.

[0047] Preferably, the preparation of the microbial self-healing slurry specifically involves,

[0048] The microbial self-healing slurry is obtained by mixing the bacterial solution and the cementing solution.

[0049] More preferably, the volume ratio of bacterial solution to cementing solution is 1:0.2-2.

[0050] Preferably, the secondary biomaterial self-healing method for concrete cracks specifically includes:

[0051] S1, Level 1 Repair: Spray deionized water onto the concrete crack surface until it is wetted. Apply the microbial self-healing grout to the crack surface, then spread it evenly with a brush pre-soaked in the grout. Let it stand for 2-5 hours. Next, apply the bonding agent to the crack surface, then spread it evenly with a brush pre-soaked in the bonding agent. Let it stand for 6-24 hours. Repeat this process, applying the bonding agent 8 times. The ratio of microbial self-healing grout usage to the concrete crack surface area is 1 mL: 5-20 cm². 2 The ratio of binder usage to concrete crack surface area is 1 mL: 5-20 cm². 2 .

[0052] S2, Secondary Repair: Exposing concrete cracks to the open sea for 30-300 days allows marine organisms to attach to the surface of the cracks, forming a biofilm. Exposure conditions include: average air temperature of 20-30℃, salinity of 25-40‰, and average tidal range of 1-5m.

[0053] Preferably, the secondary biomaterial self-healing method for concrete cracks specifically includes:

[0054] S1, Level 1 Repair: Spray deionized water onto the concrete crack surface until it is wetted. Apply the microbial self-healing grout to the crack surface, then spread it evenly with a brush pre-soaked in the grout. After application, treat under vacuum (pressure below -0.1 MPa) for 5-20 minutes, then allow to stand for 2-5 hours under normal conditions. Next, apply the binder to the crack surface, spreading it evenly with a brush pre-soaked in the binder. Treat under vacuum (pressure below -0.1 MPa) for 5-20 minutes, then allow to stand for 6-24 hours under normal conditions. Repeat this process 8 times. The ratio of microbial self-healing grout usage to the concrete crack surface area is 1 mL: 5-20 cm². 2 The ratio of binder usage to concrete crack surface area is 1 mL: 5-20 cm². 2 .

[0055] S2, Secondary Repair: Exposing concrete cracks to the open sea for 30-300 days allows marine organisms to attach to the surface of the cracks, forming a biofilm. Exposure conditions include: average air temperature of 20-30℃, salinity of 25-40‰, and average tidal range of 1-5m.

[0056] This invention utilizes a binder to prepare a cementitious liquid, which is then compounded with a bacterial solution to obtain a microbial self-healing slurry. The microbial self-healing slurry is first applied to the surface of concrete cracks, followed by repeated application of the binder 1-10 times. This results in the following beneficial effects: The secondary biomaterial self-healing method for concrete cracks provided by this invention effectively improves concrete durability and the self-healing performance of concrete cracks. Concrete specimens treated with this method exhibit excellent resistance to chloride ion erosion, with a chloride ion erosion resistance rate of 11.4-24.3%. Simultaneously, the crack repair effect is significant, with the relative permeability coefficient of the repaired concrete crack specimens reduced to 2.8-28.7%. Therefore, this invention is a secondary biomaterial self-healing method for concrete cracks that enhances concrete durability and the self-healing performance of concrete cracks. Attached Figure Description

[0057] Figure 1 The infrared spectrum of the regulator.

[0058] Figure 2 The macroscopic morphology of complete barnacles attached to the surface of a concrete crack specimen.

[0059] Figure 3 SEM image of a cross-section of a concrete crack specimen with intact barnacle attachment.

[0060] Figure 4 SEM image of a cross-section of a concrete crack specimen with only barnacle bio-adhesive attached. Detailed Implementation

[0061] The present invention will now be described in further detail with reference to specific embodiments. The given embodiments are merely illustrative of the invention and not intended to limit its scope. The embodiments provided below can serve as a guide for further improvements by those skilled in the art and do not constitute a limitation on the invention in any way.

[0062] Unless otherwise specified, the experimental methods used in the following examples are conventional methods. Unless otherwise specified, the materials and reagents used in the following examples are commercially available.

[0063] Example 1:

[0064] Preparation of bacterial culture, including,

[0065] After activating *Bacillus pasteurellii*, it was inoculated onto a solid slant agar medium and incubated statically at 30°C for 24 hours. Then, the strain was inoculated into a liquid agar medium and incubated at 30°C with shaking at 150 rpm for 24 hours to obtain the bacterial suspension. The OD of the bacterial suspension was... 600 The value was 2.7. *Pasteurella multocida* was purchased from the Shanghai Microbial Culture Collection Center (SHBCC), catalog number ATCC-11859. Activation of *Pasteurella multocida* was performed according to the manufacturer's instructions. Solid slant culture medium consisted of peptone, meat extract, urea, agar, and deionized water. The mass ratio of peptone to meat extract was 1:0.6, the mass ratio of peptone to urea was 1:4, the mass ratio of peptone to agar was 1:3, and the volume ratio of peptone to deionized water was 1 g:0.2 L. Liquid culture medium consisted of peptone, meat extract, urea, and deionized water. The mass ratio of peptone to meat extract was 1:0.6, the mass ratio of peptone to urea was 1:4, and the volume ratio of peptone to deionized water was 1 g:0.2 L.

[0066] Preparation of the cementing solution includes,

[0067] Calcium acetate and urea were mixed, and deionized water was added and stirred until homogeneous to obtain a cementitious solution. The mass ratio of calcium acetate to urea was 1:0.4, and the volume ratio of calcium acetate to deionized water was 1 g:6 mL.

[0068] Preparation of microbial self-healing slurry, including,

[0069] The microbial self-healing slurry was obtained by mixing the bacterial solution and the cementing solution. The volume ratio of the bacterial solution to the cementing solution was 1:1.

[0070] A secondary biomaterial self-healing method for concrete cracks includes,

[0071] S1, Level 1 Repair: Spray deionized water onto the concrete crack surface until it is wetted. Apply the microbial self-healing grout to the crack surface, then spread it evenly with a brush pre-soaked in the grout. Let it stand for 3 hours. Next, apply the bonding agent to the crack surface, then spread it evenly with a brush pre-soaked in the bonding agent. Let it stand for 12 hours. Repeat this process, applying the bonding agent 8 times. The ratio of microbial self-healing grout usage to the concrete crack surface area is 1 mL: 10 cm². 2 The ratio of binder usage to concrete crack surface area is 1 mL: 10 cm². 2 .

[0072] S2, Secondary Repair: The concrete cracks are exposed to the open sea for 180 days, allowing marine organisms to attach to the surface of the cracks and form a biofilm. The exposure conditions are: average air temperature of 22.1℃, salinity of 32.0‰, and average tidal range of 2.95m.

[0073] Example 2:

[0074] The preparation of the bacterial solution is the same as in Example 1.

[0075] The preparation of the cementing solution is the same as in Example 1.

[0076] The preparation of the microbial self-healing slurry is the same as in Example 1.

[0077] A secondary biomaterial self-healing method for concrete cracks includes,

[0078] S1, Level 1 Repair: Deionized water is sprayed onto the concrete crack surface until it is wetted. Microbial self-healing grout is then dripped onto the crack surface and spread evenly using a brush pre-soaked in the grout. After application, the surface is treated under vacuum at a pressure of -0.1 MPa for 15 minutes, followed by standing for 3 hours under normal conditions. Then, a binder is dripped onto the crack surface and spread evenly using a brush pre-soaked in the binder. This process is repeated under vacuum at a pressure of -0.1 MPa for 15 minutes, followed by standing for 12 hours under normal conditions. This process is repeated 8 times. The ratio of microbial self-healing grout usage to the concrete crack surface area is 1 mL: 10 cm². 2 The ratio of binder usage to concrete crack surface area is 1 mL: 10 cm². 2 .

[0079] S2, Secondary Repair: The concrete cracks are exposed to the open sea for 180 days, allowing marine organisms to attach to the surface of the cracks and form a biofilm. The exposure conditions are: average air temperature of 22.1℃, salinity of 32.0‰, and average tidal range of 2.95m.

[0080] Example 3:

[0081] The preparation of the bacterial solution is the same as in Example 1.

[0082] The preparation of regulators includes,

[0083] 4-(dimethylamino)butyraldehyde diacetate and acetonitrile were mixed and stirred. 4-(bromoethane)phenylacetic acid was added at 50°C and reacted for 12 hours. After the reaction was completed, the mixture was cooled to room temperature, and anhydrous diethyl ether was added to precipitate the precipitate. The precipitate was then dried under vacuum to obtain the regulator. The molar ratio of 4-(dimethylamino)butyraldehyde diacetate to acetonitrile was 1 g: 5 mL; the molar ratio of 4-(bromoethane)phenylacetic acid to acetonitrile was 1 g: 5 mL; and the volume ratio of acetonitrile to anhydrous diethyl ether was 1:2.

[0084] Preparation of the cementing solution includes,

[0085] Calcium acetate and urea were mixed, and a regulator and deionized water were added and stirred until homogeneous to obtain a cementitious solution. The mass ratio of calcium acetate to urea was 1:0.4, the mass ratio of calcium acetate to regulator was 1:0.1, and the volume ratio of calcium acetate to deionized water was 1 g:6 mL.

[0086] The preparation of the microbial self-healing slurry was the same as in Example 1, except that the cementing liquid was replaced with the cementing liquid prepared in this example.

[0087] The method for self-healing of concrete cracks using secondary biomaterials is the same as in Example 2, except that the microbial self-healing slurry in step S1 is replaced with the microbial self-healing slurry prepared in this example, and the cementing liquid in step S2 is replaced with the cementing liquid prepared in this example.

[0088] Example 4:

[0089] The preparation of the bacterial solution is the same as in Example 1.

[0090] The preparation of the regulator is the same as in Example 3.

[0091] The preparation of the cementing solution was the same as in Example 3, except that the mass ratio of calcium acetate to regulator was changed to 1:0.05.

[0092] The preparation of the microbial self-healing slurry was the same as in Example 1, except that the cementing liquid was replaced with the cementing liquid prepared in this example.

[0093] The method for self-healing of concrete cracks using secondary biomaterials is the same as in Example 2, except that the microbial self-healing slurry in step S1 is replaced with the microbial self-healing slurry prepared in this example, and the cementing liquid in step S2 is replaced with the cementing liquid prepared in this example.

[0094] Example 5:

[0095] The preparation of the bacterial solution is the same as in Example 1.

[0096] The preparation of regulators includes,

[0097] 4-(dimethylamino)butanal dimethyl acetal and acetonitrile were mixed and stirred. 4-(bromoethane)phenylacetic acid was added at 50°C and reacted for 12 h. After the reaction was completed, the mixture was cooled to room temperature, and anhydrous diethyl ether was added to precipitate the precipitate. The precipitate was filtered and retained. Tetrahydrofuran was added and stirred to dissolve the precipitate. Thionyl chloride was added at 4°C, and the mixture was refluxed at 60°C for 3 h. After the reaction was completed, methyl 7-aminoheptanoate was added, followed by the slow addition of triethylamine and 4-dimethylaminopyridine. The mixture was reacted at 40°C for 1 h. The mixture was extracted with dichloromethane, and the organic layer was retained and washed five times with pure water. Anhydrous sodium sulfate was added and the mixture was dried. The mixture was filtered, the solvent was removed by rotary evaporation, and the mixture was dried under vacuum to obtain the conditioning agent. The volume ratio of 4-(dimethylamino)butyraldehyde diacetate to acetonitrile is 1 g: 5 mL; the volume ratio of 4-(bromoethane)phenylacetic acid to acetonitrile is 1 g: 5 mL; the volume ratio of acetonitrile to anhydrous diethyl ether is 1:2; the volume ratio of acetonitrile to tetrahydrofuran is 1:1; the volume ratio of acetonitrile to thionyl chloride is 1:1; the volume ratio of methyl 7-aminoheptanoate to acetonitrile is 1 g: 5 mL; the volume ratio of acetonitrile to triethylamine is 1:0.5; the volume ratio of triethylamine to 4-dimethylaminopyridine is 1:0.5; the volume ratio of acetonitrile to dichloromethane is 1:2; and the mass ratio of 4-(dimethylamino)butyraldehyde diacetate to anhydrous sodium sulfate is 1:1.5.

[0098] The preparation of the cementing liquid is the same as in Example 3, except that the regulator is replaced with the regulator prepared in this example.

[0099] The preparation of the microbial self-healing slurry was the same as in Example 1, except that the cementing liquid was replaced with the cementing liquid prepared in this example.

[0100] The method for self-healing of concrete cracks using secondary biomaterials is the same as in Example 2, except that the microbial self-healing slurry in step S1 is replaced with the microbial self-healing slurry prepared in this example, and the cementing liquid in step S2 is replaced with the cementing liquid prepared in this example.

[0101] Example 6:

[0102] The preparation of the bacterial solution is the same as in Example 1.

[0103] The preparation of the regulator is the same as in Example 5.

[0104] The preparation of the cementing solution is the same as in Example 3, except that the regulator is replaced with the regulator prepared in this example and the mass ratio of calcium acetate to regulator is changed to 1:0.05.

[0105] The preparation of the microbial self-healing slurry was the same as in Example 1, except that the cementing liquid was replaced with the cementing liquid prepared in this example.

[0106] The method for self-healing of concrete cracks using secondary biomaterials is the same as in Example 2, except that the microbial self-healing slurry in step S1 is replaced with the microbial self-healing slurry prepared in this example, and the cementing liquid in step S2 is replaced with the cementing liquid prepared in this example.

[0107] Comparative Example 1:

[0108] The preparation of the bacterial solution is the same as in Example 1.

[0109] The preparation of the regulator was the same as in Example 3, except that 4-(bromoethane)phenylacetic acid was not added.

[0110] The preparation of the cementing liquid is the same as in Example 3, except that the regulator is replaced with the regulator prepared in this example.

[0111] The preparation of the microbial self-healing slurry was the same as in Example 1, except that the cementing liquid was replaced with the cementing liquid prepared in this example.

[0112] The method for self-healing of concrete cracks using secondary biomaterials is the same as in Example 2, except that the microbial self-healing slurry in step S1 is replaced with the microbial self-healing slurry prepared in this example, and the cementing liquid in step S2 is replaced with the cementing liquid prepared in this example.

[0113] Comparative Example 2:

[0114] The preparation of the bacterial solution is the same as in Example 1.

[0115] The preparation of the regulator was the same as in Example 3, except that 4-(dimethylamino)butyraldehyde dimethyl acetal was not added.

[0116] The preparation of the cementing liquid is the same as in Example 3, except that the regulator is replaced with the regulator prepared in this example.

[0117] The preparation of the microbial self-healing slurry was the same as in Example 1, except that the cementing liquid was replaced with the cementing liquid prepared in this example.

[0118] The method for self-healing of concrete cracks using secondary biomaterials is the same as in Example 2, except that the microbial self-healing slurry in step S1 is replaced with the microbial self-healing slurry prepared in this example, and the cementing liquid in step S2 is replaced with the cementing liquid prepared in this example.

[0119] Comparative Example 3:

[0120] The preparation of the bacterial solution is the same as in Example 1.

[0121] The preparation of the regulator was the same as in Example 5, except that 4-(dimethylamino)butyraldehyde dimethyl acetal and 4-(bromoethane)phenylacetic acid were not added.

[0122] The preparation of the cementing liquid is the same as in Example 3, except that the regulator is replaced with the regulator prepared in this example.

[0123] The preparation of the microbial self-healing slurry was the same as in Example 1, except that the cementing liquid was replaced with the cementing liquid prepared in this example.

[0124] The method for self-healing of concrete cracks using secondary biomaterials is the same as in Example 2, except that the microbial self-healing slurry in step S1 is replaced with the microbial self-healing slurry prepared in this example, and the cementing liquid in step S2 is replaced with the cementing liquid prepared in this example.

[0125] Experimental example:

[0126] 1. Material Characterization

[0127] The modifier prepared in Example 5 of this invention was collected and detected using a Fourier transform infrared spectrometer.

[0128] Figure 1 The infrared spectrum of the modifier is shown at 3400 cm⁻¹. -1 An absorption peak for NH appears nearby, at 2920 cm⁻¹. -1 An absorption peak for -CH3 appears nearby, at 2830 cm⁻¹. -1 An absorption peak for -CH2 appears nearby, at 1730 cm⁻¹. -1 An absorption peak of C=O appears nearby, at 1580 cm⁻¹. -1 An absorption peak of C=C appears nearby, at 1120 cm⁻¹. -1 An absorption peak for CO appears nearby.

[0129] 2. Concrete performance testing

[0130] Preparation of concrete simulation specimens:

[0131] S1. Concrete Mixing: Mix fly ash, mineral powder, sand, and gravel for 30 seconds, add cement and mix for 60 seconds, then add water and polycarboxylate superplasticizer and mix for 120 seconds to obtain concrete. The mass ratio of cement to fly ash is 1:0.5; the mass ratio of fly ash to mineral powder is 1:1; the mass ratio of fly ash to sand is 1:7; the mass ratio of fly ash to gravel is 1:10; the ratio of fly ash to water is 1 kg:1 L; and the mass ratio of fly ash to polycarboxylate superplasticizer is 1:0.04.

[0132] S2. Vibration: Place the concrete into a mold pre-coated with release agent and vibrate it on a vibrating table until slurry appears on the surface of the specimen. During vibration, use a shovel to lightly tap along the mold wall to ensure full compaction and prevent over-vibration that could lead to segregation and bleeding.

[0133] S3. Smoothing: Remove excess concrete overflowing from the edges of the mold and smooth the surface with a scraper.

[0134] S4. Curing: After smoothing, the specimens are covered with plastic film and left to stand at 22°C for 24 hours. After curing in a standard concrete curing room for 28 days, concrete simulation specimens are obtained.

[0135] 2.1 Resistance to chloride ion corrosion

[0136] Concrete simulated specimens were cut into cylindrical specimens with a diameter of 100 mm and a height of 50 mm, and divided into three groups: a control group and two experimental groups. The control group received no treatment. In the two experimental groups, the secondary biomaterial self-healing method for concrete cracks described in Examples 1 and 2 was used, respectively, to apply microbial self-healing slurry to the surface of the cylindrical specimens. After treatment, the resistance to chloride ion erosion of the concrete specimens in the control group and the two experimental groups was determined according to the "Standard for Test Methods of Long-Term Performance and Durability of Ordinary Concrete" (GB / T50082-2024).

[0137] The electrical flux of the blank group was 1230C. The electrical flux of the cylindrical specimen coated with the microbial self-healing slurry using the secondary biomaterial self-healing method for concrete cracks in Example 1 was 1165C. The electrical flux of the cylindrical specimen coated with the microbial self-healing slurry using the secondary biomaterial self-healing method for concrete cracks in Example 2 was 1090C. This indicates that applying the microbial self-healing slurry under vacuum negative pressure can promote the deeper deposition of calcium carbonate generated by microbial-induced mineralization into the pore structure of concrete, effectively filling the surface pores of concrete, thereby optimizing the surface pore structure and improving the concrete's resistance to chloride ion penetration, specifically manifested as a significant decrease in electrical flux.

[0138] Concrete simulated specimens were cut into cylindrical specimens with a diameter of 100 mm and a height of 50 mm, and divided into three groups: a control group and eight experimental groups. The control group was left untreated. In the eight experimental groups, the secondary biomaterial self-healing method for concrete cracks, as described in Examples 2-6 and the comparative example, was applied sequentially, with microbial self-healing slurry applied to the surface of the cylindrical specimens. After treatment, the chloride ion erosion resistance of the concrete specimens in the control group and the eight experimental groups was determined according to the "Standard for Test Methods of Long-Term Performance and Durability of Ordinary Concrete" (GB / T50082-2024). The chloride ion erosion resistance rate (%) was calculated as: (Electric flux of control group - Electric flux of experimental group) / Electric flux of control group × 100%.

[0139] Table 1. Resistance to chloride ion attack (%)

[0140]

[0141] Table 1 shows the chloride ion erosion resistance rate (%). As shown in Table 1, the chloride ion erosion resistance rate of Examples 3-4 is higher than that of Example 1 because a regulator was introduced into the cementing solution in Examples 3-4 during the preparation of the microbial self-healing slurry, while no regulator was used in Example 1. The chloride ion erosion resistance rate of Example 3 is higher than that of Example 4 because the amount of regulator used in the preparation of the microbial self-healing slurry is different. The chloride ion erosion resistance rate of Examples 3-4 is higher than that of Comparative Examples 1-2 because the regulator was prepared by synergistic use of 4-(dimethylamino)butyraldehyde dimethyl acetate and 4-(bromoethane)phenylacetic acid in Examples 3-4, while 4-(bromoethane)phenylacetic acid was not used in Comparative Example 1, and 4-(dimethylamino)butyraldehyde dimethyl acetate was not used in Comparative Example 2. This indicates that using appropriate amounts of 4-(dimethylamino)butanol dimethyl acetate and 4-(bromoethane)phenylacetic acid to prepare a regulator, and then using the regulator to prepare a cementing solution, which is then compounded with bacterial solution to obtain a microbial self-healing slurry, helps to improve the resistance to chloride ion erosion.

[0142] The higher chloride ion erosion resistance rates of Examples 5-6 compared to Example 3 are due to the further introduction of methyl 7-aminoheptanoate for modification during the preparation of the regulator. The higher chloride ion erosion resistance rates of Examples 5-6 compared to Comparative Example 3 are because Comparative Example 3 used only methyl 7-aminoheptanoate in the preparation of the regulator, without using 4-(dimethylamino)butyraldehyde dimethyl acetal and 4-(bromoethane)phenylacetic acid. The higher chloride ion erosion resistance rate of Example 5 compared to Example 6 is due to the different amounts of regulator used in the preparation of the microbial self-healing slurry. This indicates that the further introduction of methyl 7-aminoheptanoate in the preparation of the regulator in this invention helps to further improve the chloride ion erosion resistance rate.

[0143] 2.2 Permeability Test

[0144] When concrete has cracks, water can quickly pass through the cracks. If the cracks are repaired, it takes longer for a unit volume of water to penetrate the concrete. Therefore, the permeability coefficient can be used to characterize the water resistance of concrete after crack repair.

[0145] Concrete simulated specimens were cut into cylindrical specimens with a diameter of 100 mm and a height of 50 mm. Adhesive tape was then wrapped around the specimens, and pressure was applied using a pressure testing machine. Concrete crack specimens were obtained when microcracks appeared on the surface of the specimens. These specimens were randomly divided into 9 groups, with one group serving as a blank control group and receiving no treatment. The remaining 8 groups were treated sequentially using the secondary biomaterial self-healing methods for concrete cracks described in Examples 2-6 and Comparative Examples 1-3, respectively. After all specimens were treated, they were tightly connected to PVC plastic pipes, and the connection between the concrete crack specimens and the PVC pipes was sealed with epoxy resin to ensure no leakage. The volume of water permeating through the PVC pipes into the concrete crack specimens under constant pressure was measured. The permeability coefficient for each group was first calculated using Darcy's law, and then the relative permeability coefficient was calculated based on the permeability coefficient. The formula for calculating the relative permeability coefficient is: Relative permeability coefficient (%) = Permeability coefficient of experimental group / Permeability coefficient of blank group × 100%.

[0146] Table 2 Relative permeability coefficient (%)

[0147]

[0148] Table 2 shows the relative permeability coefficients (%). As can be seen from Table 2, the relative permeability coefficients of Examples 3-4 are lower than that of Example 1 because, in the preparation of the microbial self-healing slurry, Examples 3-4 introduced a regulator into the cementing solution, while Example 1 did not use a regulator. The relative permeability coefficient of Example 3 is lower than that of Example 4 because the amount of regulator used in the preparation of the microbial self-healing slurry is different. The relative permeability coefficients of Examples 3-4 are lower than those of Comparative Examples 1-2 because, in the preparation of the regulator, Examples 3-4 used 4-(dimethylamino)butyraldehyde dimethyl acetal and 4-(bromoethane)phenylacetic acid in combination to prepare the regulator, while Comparative Example 1 did not use 4-(bromoethane)phenylacetic acid, and Comparative Example 2 did not use 4-(dimethylamino)butyraldehyde dimethyl acetal. This indicates that using appropriate amounts of 4-(dimethylamino)butyraldehyde dimethyl acetate and 4-(bromoethane)phenylacetic acid to prepare a regulator, and then using the regulator to prepare a cementitious liquid, and then compounding it with bacterial solution to obtain a microbial self-healing grout, helps to improve the repair effect of the microbial self-healing grout, resulting in better impermeability of the repaired concrete crack specimens.

[0149] The relative permeability coefficients of Examples 5-6 of this invention are lower than those of Example 3 because methyl 7-aminoheptanoate was further introduced for modification during the preparation of the regulator. The relative permeability coefficients of Examples 5-6 are lower than those of Comparative Example 3 because Comparative Example 3 used only methyl 7-aminoheptanoate in the preparation of the regulator, without using 4-(dimethylamino)butyraldehyde dimethyl acetal and 4-(bromoethane)phenylacetic acid. The relative permeability coefficient of Example 5 is lower than that of Example 6 because the amount of regulator used differed in the preparation of the microbial self-healing grout. This indicates that the further introduction of methyl 7-aminoheptanoate into the preparation of the regulator in this invention helps to further improve the impermeability of the repaired concrete crack specimens.

[0150] 3. Microscopic morphology test

[0151] In the preparation of concrete simulation specimens, an oiled aluminum foil sheet, 60 mm long and 50 mm wide, was vertically inserted during concrete pouring, resulting in a crack width of 0.2 mm. After the concrete simulation specimens had set for 16 hours, the foil sheet was slowly removed, and the specimens were then cured for 28 days to obtain concrete crack specimens. The concrete crack specimens were repaired using the secondary biomaterial self-healing method for concrete cracks described in Example 2. After the repair was completed, barnacles were observed to be attached to the surface of the concrete crack specimens.

[0152] Biomaterial samples were extracted from cracked concrete specimens using a small hammer and thin sections were prepared. The dried biomaterial samples were then fixed onto conductive adhesive and sputter-plated with gold under vacuum. The morphology of the barnacle bio-adhesive-concrete interface was observed using a scanning electron microscope at an accelerating voltage of 20V-30kV, and elemental analysis was performed using an EDS probe integrated with the SEM.

[0153] Figure 2 The macroscopic morphology of complete barnacles attached to the surface of a concrete crack specimen; Figure 3 SEM image of a cross-section of a concrete crack specimen with intact barnacles attached; the blue rectangles indicate the areas where barnacle bio-adhesive has penetrated the concrete substrate. Figure 4 This is a SEM image of a cross-section of a concrete crack specimen with only barnacle bio-adhesive adhering to it. The blue rectangles indicate the areas where the barnacle bio-adhesive has penetrated the concrete substrate. Figures 2 to 4It was found that in samples where barnacles were intact, the bio-adhesive secreted by the barnacles formed a protective layer of approximately 15 μm on the concrete surface. No sodium chloride or magnesium chloride crystals were observed in this bio-adhesive layer, and its microstructure differed significantly from that of the concrete. From the side, the barnacle adhesive appeared layered and dense with no obvious pores, and the interface morphology showed that the bio-adhesive secreted by the barnacles could penetrate and fill the micropores on the concrete surface. Furthermore, in samples where the barnacle shells had detached, the barnacle bio-adhesive layer was thinner and the interface was looser, but it was still observed that the bio-adhesive had penetrated and filled the pores on the concrete surface. This indicates that the barnacle bio-adhesive has good wettability and interfacial adhesion, enabling it to bond tightly to the concrete substrate.

[0154] The conventional operations in the operation steps of this invention are well known to those skilled in the art and will not be described in detail here.

[0155] The embodiments described above provide a detailed explanation of the technical solutions of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any changes and modifications made within the scope of the principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A secondary biomaterial self-healing method for concrete cracks, including: First, the surface of the concrete cracks is moistened with deionized water. Under negative pressure, the microbial self-healing slurry is applied to the surface of the concrete cracks and left to stand. Then, the concrete is exposed to the sea for 30-300 days to allow marine organisms to adsorb onto the concrete surface and form a biofilm. The microbial self-healing slurry is a mixture of bacterial solution and cementing solution. The volume ratio of bacterial solution to cementing solution is 1:0.2-2. In the preparation of cementing solution, calcium acetate and urea are mixed, and a regulator and deionized water are added and stirred evenly to obtain cementing solution. In the preparation of regulator, 4-(dimethylamino)butanal dimethyl acetonitrile and acetonitrile are mixed and stirred. 4-(bromoethane)phenylacetic acid is added at 40-60℃ and reacted for 8-24 hours. After the reaction is completed, the mixture is cooled to room temperature, anhydrous diethyl ether is added to precipitate the precipitate, and the precipitate is dried under vacuum to obtain regulator. The ratio of 4-(dimethylamino)butyral dimethyl acetal to acetonitrile is 1g:2-10mL; The ratio of 4-(bromoethane)phenylacetic acid to acetonitrile is 1g:2-10mL.

2. The method for self-healing concrete cracks using secondary biomaterials according to claim 1, characterized in that, The mass ratio of calcium acetate to urea is 1:0.2-1.

3. The method for self-healing concrete cracks using secondary biomaterials according to claim 1, characterized in that, The ratio of calcium acetate to deionized water is 1g:2-10mL.

4. The method for self-healing concrete cracks using secondary biomaterials according to claim 1, characterized in that, The regulator is prepared by the following steps: 4-(dimethylamino)butyral dimethyl acetal and acetonitrile are mixed and stirred, and 4-(bromoethane)phenylacetic acid is added at 40-60℃ and reacted for 8-24 h. After the reaction is completed, the mixture is cooled to room temperature, and anhydrous diethyl ether is added to precipitate the precipitate. The precipitate is filtered and retained, and tetrahydrofuran is added and stirred to dissolve it. Thionyl chloride is added at 0-5℃, and the mixture is refluxed at 50-70℃ for 2-6 h. After the reaction is completed, methyl 7-aminoheptanoate is added, and triethylamine and 4-dimethylaminopyridine are slowly added. The mixture is reacted at 30-50℃ for 0.5-2 h, extracted with dichloromethane, and the organic layer is retained and washed 3-6 times with pure water. Anhydrous sodium sulfate is added and the mixture is dried, filtered, the solvent is removed by rotary evaporation, and the mixture is dried under vacuum to obtain the regulator.

5. The method for self-healing concrete cracks using secondary biomaterials according to claim 1, characterized in that, The bacterial solution is a Bacillus pasteurellium bacterial solution, OD 600 The value is 2.3-2.7.

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