Multi-element microorganism crack self-repairing cement-based material and preparation method thereof

Abstract

The invention provides a multi-element microorganism crack self-repairing cement-based material and a preparation method, and relates to the field of cement-based materials, the multi-element microorganism crack self-repairing cement-based material comprises the following components by mass: 2118-2243 parts of a cement base material, 32-163 parts of a multi-element microorganism mixed solution and 12-61 parts of a mineralizer; the cement base material comprises cement, sand, water and nutrient substances for metabolism and growth of multiple microorganisms; the multi-element microorganism mixed solution comprises a mixture of urease type bacteria, anaerobic bacteria and paenibacillus mucilaginosus which have the capability of inducing mineralization, and a liquid culture medium; the mineralizing agent comprises calcium acetate, urea and glucose. According to the method, urease type bacteria, anaerobic bacteria and paenibacillus mucilaginosus are utilized for synergistic mineralization, and the problems that the repair depth is not enough due to the fact that the oxygen concentration in the deep position of the crack is low, and the repair speed is low when a single strain is adopted can be solved. When the surface cracks are repaired, the crack repairing depth of the cracked cement-based material is greatly improved, and the repairing period of the micro-cracks of the cement-based material is remarkably shortened.

Description

Technical Field

[0001] The present invention relates to the technical field of cement-based materials, and in particular to a multi-microorganism crack self-repairing cement-based material and a preparation method thereof. Background Art

[0002] As a composite building material product with low cost, good durability and high compressive strength, cement-based materials are widely used in various civil engineering fields. However, due to the brittleness and low toughness of cement-based materials, cracks will appear in the early stage and cause cracking. Due to the influence of load and non-load factors, microcracks are formed, allowing harmful media to enter the concrete, resulting in serious damage to the performance of concrete. There are many traditional methods for treating cracks in cement-based materials, such as surface treatment, grouting and structural reinforcement, but these methods often consume a lot of manpower and material resources. And they are post-remediation and cannot quickly and autonomously repair cracks from the source. The economic, environmental protection and intelligent nature of microbial self-repairing cement-based materials are considered to be one of the most promising repair methods at present. In traditional microbial self-repairing cement-based materials, when the cement substrate is formed and cracked, water, oxygen and other chemicals penetrate into the cracks to promote the bacteria to induce the formation of mineralized substances, thereby achieving self-healing of cracks and improving the physical and mechanical properties of the material structure. At present, certain theoretical research and practical applications have been carried out on the repair of cracks in cement-based materials by microbial self-repairing materials. However, the self-healing cement-based materials using urease-type bacteria still have problems such as slow repair rate and insufficient repair depth due to the low oxygen content deep in the cracks and the low volume yield of calcium carbonate per unit time.

[0003] In the prior art, CN113121145 discloses a concrete crack self-repairing material and application based on microbial synergistic mineralization, wherein the concrete crack self-repairing material comprises a porous carrier and a substrate loaded with a microbial synergistic mineralizer. The microbial synergistic mineralizer comprises a mixture of spores of urealytic bacteria and denitrifying bacteria with the ability to induce mineralization and nutrients. When applied, the concrete crack self-repairing material is directly mixed with the various components of the concrete, and the substrate is first dissolved in the mixing water, and then mixed evenly with the other components of the concrete. This technology uses the synergistic mineralization of aerobic and anaerobic microorganisms to achieve synchronous and effective repair of the surface and deep cracks of the concrete. However, the porous carrier of the microbial synergistic mineralizer used has a more complicated preparation process. The prepared microbial synergistic mineralized concrete crack self-repairing material has a slow repair rate, and the cracks can only be basically repaired after 28 days of curing. CN116730685 discloses a self-repairing cement-based material for cracks based on mineralized deposition of Bacillus pasteurianus and a preparation method, comprising a cement substrate, a premix one and a premix two, wherein the premix one comprises urease-producing bacteria and a carrier that have adsorbed calcium ions, and the premix two comprises urease-producing bacteria and a carrier that have not adsorbed calcium ions. The diatomaceous earth loaded with microorganisms is divided into two parts, one part is diatomaceous earth loaded with microorganisms that have not adsorbed calcium ions in advance, and the other part is diatomaceous earth loaded with microorganisms that have adsorbed calcium ions in advance. The prepared self-repairing regenerated cement-based material for cracks based on mineralized deposition of Bacillus pasteurianus is a regenerated cement-based material that has both self-diagnosis and self-repair of cracks and is green and environmentally friendly. This technology uses a single urease-type strain and does not describe the repair effect deep in the cracks. At the same time, the cement-based material cannot be repaired in time after early cracking, and the repair cycle is long, and it still needs to be maintained for 28 days. CN106699026A discloses a crack self-repairing regenerated concrete based on the mineralization deposition of urease-producing microorganisms and a preparation method thereof, wherein the components are expanded perlite loaded with urease-producing microorganisms, cement, gravel, sand, silica fume, water, urea, calcium chloride, urease-producing microbial suspension and water reducer. By directly adding a portion of the crack repairing agent into the concrete, the cracks and holes on the recycled coarse aggregate itself, as well as the weak bonding area between the recycled aggregate and the new cement stone matrix, are self-repaired, thereby improving the mechanical properties of the recycled concrete. At the same time, the other portion of the crack repairing agent is first adsorbed into the expanded perlite carrier, and then added into the concrete, so as to improve the crack self-repairing ability of the recycled concrete during service, thereby improving the impermeability and durability of the recycled concrete. The technology uses urease-type bacteria and expanded perlite loaded with urease-type bacteria, and the crack repair is greatly affected by substances such as moisture and oxygen in the environment.

[0004] Therefore, how to solve the problem that self-healing materials are restricted by the environment and cannot balance the repair rate and repair depth has become a technical problem that needs to be solved urgently. Summary of the invention

[0005] The present invention aims to solve at least one of the technical problems existing in the prior art or related art, and discloses a multi-microbial self-repairing cement-based material and a preparation method thereof, which uses anaerobic bacteria and jelly-like Bacillus for synergistic mineralization. It overcomes the problem that traditional microbial self-repairing materials are restricted by the environment, and solves the problem that the existing self-repairing materials cannot take into account both the repair rate and the repair depth when using Bacillus pasteurianus to mineralize and repair cracks.

[0006] The first aspect of the present invention discloses a multi-microorganism crack self-repairing cement-based material, comprising: 2118-2243 parts of cement base material, 32-163 parts of multi-microorganism mixed solution and 12-61 parts of mineralizer by mass; the cement base material comprises cement, sand, water and nutrients for the metabolism and growth of multi-microorganisms; the multi-microorganism mixed solution comprises a mixture of urease-type bacteria, anaerobic bacteria and jelly-like Bacillus with the ability to induce mineralization and a liquid culture medium; the mineralizer comprises calcium acetate, urea and glucose.

[0007] In this technical solution, the multi-microorganism crack self-repairing cement-based material provided by the present invention is used by mixing the multi-microorganism mixed liquid and the mineralizer with the components of the cement base material respectively, and the mineralizer is first mixed evenly with the components of the cement base material. The multi-microorganism mixed liquid is dissolved in the mixing water, and then mixed evenly with the other components of the cement base material mixed with the mineralizer. The total weight of the multi-microorganism mixed liquid is 10%-50% of the total water consumption.

[0008] According to the multi-microorganism crack self-repairing cement-based material disclosed in the present invention, preferably, the concentration of the multi-microorganism mixed solution is 1×10 9 cells / mL-8×10 9 cells / mL.

[0009] According to the multi-microbial crack self-repairing cement-based material disclosed in the present invention, preferably, the mixture specifically includes Bacillus pasteurianus, Saccharomyces cerevisiae and carbonic anhydrase bacteria, and Bacillus pasteurianus, Saccharomyces cerevisiae and carbonic anhydrase bacteria are mixed in a volume ratio of 7:1:2 to obtain the mixture.

[0010] According to the multi-microorganism crack self-repairing cement-based material disclosed in the present invention, preferably, the liquid culture medium contains 15g peptone, 3g beef extract, 10g glucose, 5.6g yeast extract powder, 5g disodium hydrogen phosphate, 0.28g potassium chloride, 2g calcium carbonate, 20g sucrose, 1g ammonium sulfate, 1g magnesium sulfate and an appropriate amount of deionized water per 1L.

[0011] According to the multi-microorganism crack self-repairing cement-based material disclosed in the present invention, preferably, the cement base material specifically includes 650 parts of cement, 1300 parts of sand, 162-292 parts of water, and 1-7 parts of nutrients in parts by mass; the nutrients specifically include 50-250 parts of peptone, 10-50 parts of beef extract, 18-90 parts of yeast extract powder, 16-80 parts of disodium hydrogen phosphate, 1-5 parts of potassium chloride, 6-33 parts of calcium carbonate, 20-100 parts of sucrose, 3-16 parts of ammonium sulfate, and 3-16 parts of magnesium sulfate in parts by mass.

[0012] According to the multi-microorganism crack self-repairing cement-based material disclosed in the present invention, preferably, the weight ratio of the multi-microorganism mixed solution to the mineralizer is 1:0.37.

[0013] According to the multi-microorganism crack self-repairing cement-based material disclosed in the present invention, preferably, the weight ratio of calcium acetate, urea and glucose is 1:0.55:0.14.

[0014] The second aspect of the present invention also discloses a method for preparing a multi-microorganism crack self-repairing cement-based material, comprising: preparing a multi-microorganism mixed solution: using deionized water to prepare a multi-microorganism liquid culture solution, sterilizing the culture solution, and then adding a urea solution with a mass fraction of 4% to obtain a liquid culture medium; mixing the cultured Bacillus pasteurianus, Saccharomyces cerevisiae and carbonic anhydrase bacteria in a volume ratio of 7:1:2, and inoculating the mixture into the liquid culture medium; placing the inoculated liquid culture medium in a shaker and continuing to culture for 23-25 ​​hours, so that the concentration of the multi-microorganism mixed solution is 1×10 9 cells / ml-8×10 9 cells / ml; prepare the mineralizer: mix calcium acetate, urea and glucose in a mass ratio of 1:0.55:0.14; fully stir the cement base material, the multi-microorganism mixed solution and the mineralizer according to the ratio to obtain the multi-microorganism crack self-repairing cement-based material.

[0015] According to the preparation method of the multi-microorganism crack self-repairing cement-based material disclosed in the present invention, preferably, in the step of preparing the multi-microorganism mixed solution, the sterilization treatment refers to sterilization treatment for 25min-35min under the conditions of temperature 120°C and pressure 0.1MPa; the temperature of the shaker is 35°C and the rotation speed is 170rpm / min; the concentration of the urea solution is 4mol / L; and inoculation is performed at 10% of the volume of the liquid culture medium.

[0016] According to the preparation method of the multi-microorganism crack self-repairing cement-based material disclosed in the present invention, preferably, the preparation method of the cement substrate comprises: 50-250 parts by weight of peptone, 10-50 parts by weight of beef extract, 18-90 parts by weight of yeast extract powder, 16-80 parts by weight of disodium hydrogen phosphate, 1-5 parts by weight of potassium chloride, 6-33 parts by weight of calcium carbonate, 20-100 parts by weight of sucrose, 3-16 parts by weight of ammonium sulfate, and 3-16 parts by weight of magnesium sulfate are fully mixed to obtain nutrients; and the cement substrate is prepared by mixing 650 parts by weight of cement, 1300 parts by weight of sand, 162-292 parts by weight of water, and 1-7 parts by weight of nutrients.

[0017] The beneficial effects of the present invention include at least:

[0018] 1. The present invention is based on the principle of urease-type bacteria mineralization deposition, and the multi-microorganism mixed solution prepared by the present invention adopts the method of combining Bacillus pasteurianus with Saccharomyces cerevisiae and carbonic anhydrase bacteria. While repairing surface cracks, it greatly improves the crack repair depth of cement-based materials after cracking, and significantly shortens the repair cycle of micro-cracks in cement-based materials.

[0019] 2. The present invention is to prepare a multi-microorganism crack self-repairing cement-based material by mixing a cement base material, a multi-microorganism mixed liquid and a mineralizing liquid, and to use the synergistic mineralization of urease bacteria, anaerobic bacteria and jelly-like Bacillus to repair cracks in cement-based materials. It can solve the problem of insufficient repair depth caused by low oxygen concentration in the deep cracks and slow repair rate using a single strain of bacteria. While repairing surface cracks, it greatly improves the crack repair depth of cement-based materials after cracking, and significantly shortens the repair cycle of micro-cracks in cement-based materials.

[0020] 3. The present invention is different from traditional microbial self-repairing cement-based materials. The multi-microbial self-repairing cement-based materials do not require external moisture and oxygen to penetrate into the cracks to activate the bacteria. They can be repaired through the capillary water provided by the cement-based materials and the coordinated mineralization of anaerobic bacteria and jelly-like Bacillus. The problem of traditional microbial self-repairing materials being restricted by the environment is overcome, and the cement-based materials have excellent self-repairing ability, thereby improving the durability.

[0021] 4. The preparation method of the present invention is to mix multiple microorganisms in a certain proportion and inoculate them into a liquid culture medium for cultivation to obtain a multiple microorganism mixed solution. The obtained multiple microorganism mixed solution, cement substrate and mineralizer are mixed in a certain proportion to obtain a self-repairing material. The multiple microorganism crack self-repairing material in the present application can significantly increase the yield of calcium carbonate in the cracks and the crack area repair rate, improve the repair rate, and increase the repair depth in the repair of cracks in cement-based materials. It solves the problem that the current microbial self-repairing cement-based materials are restricted by the environment. It has good engineering application value and provides an efficient and green and environmentally friendly biorepair method for self-repair of concrete cracks. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A schematic diagram of a maintenance method for a multi-microorganism crack self-repairing cement-based material according to an embodiment of the present invention is shown.

[0023] Figure 2 Comparative photos of the crack surface of the specimen before and after repair according to an embodiment of the present invention are shown.

[0024] Figure 3 The SEM images of the cross-section material at different depths at the crack of the specimen according to the embodiment of the present invention are shown.

[0025] Figure 4 The XRD diagram of the precipitates at the cracks of the test piece according to the embodiment of the present invention is shown.

[0026] Figure 5 A SEM image of precipitates at cracks of a specimen according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0027] In order to more clearly understand the above-mentioned purpose, features and advantages of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention can also be implemented in other ways different from those described herein, and therefore, the present invention is not limited to the limitations of the specific embodiments disclosed below.

[0028] According to one embodiment of the present invention, a multi-microorganism crack self-repairing cement-based material is disclosed, comprising: 2118-2243 parts of cement base material, 32-163 parts of multi-microorganism mixed solution and 12-61 parts of mineralizer in parts by mass; the cement base material comprises cement, sand, water and nutrients for the metabolism and growth of multi-microorganisms; the multi-microorganism mixed solution comprises a mixture of urease-type bacteria, anaerobic bacteria and jelly-like Bacillus with the ability to induce mineralization, and a liquid culture medium; the mineralizer comprises calcium acetate, urea and glucose.

[0029] According to the above embodiment, preferably, the concentration of the multi-microorganism mixture is 1×10 9 cells / mL-8×10 9 cells / mL, the total weight of the multi-microbial mixture is 10%-50% of the total water consumption.

[0030] According to the above embodiment, preferably, the mixture specifically includes Bacillus pasteurianus, Saccharomyces cerevisiae and carbonic anhydrase bacteria, and the Bacillus pasteurianus, Saccharomyces cerevisiae and carbonic anhydrase bacteria are mixed in a volume ratio of 7:1:2 to obtain the mixture.

[0031] According to the above embodiment, preferably, the liquid culture medium contains 15g peptone, 3g beef extract, 10g glucose, 5.6g yeast extract powder, 5g disodium hydrogen phosphate, 0.28g potassium chloride, 2g calcium carbonate, 20g sucrose, 1g ammonium sulfate, 1g magnesium sulfate and appropriate amount of deionized water per 1L.

[0032] According to the above embodiment, preferably, the cement base material specifically includes 650 parts of cement, 1300 parts of sand, 162-292 parts of water, and 1-7 parts of nutrients in parts by mass; the nutrients specifically include 50-250 parts of peptone, 10-50 parts of beef extract, 18-90 parts of yeast extract powder, 16-80 parts of disodium hydrogen phosphate, 1-5 parts of potassium chloride, 6-33 parts of calcium carbonate, 20-100 parts of sucrose, 3-16 parts of ammonium sulfate, and 3-16 parts of magnesium sulfate in parts by mass.

[0033] According to the above embodiment, preferably, the weight ratio of the multi-microorganism mixture to the mineralizer is 1:0.37.

[0034] According to the above embodiment, preferably, the weight ratio of calcium acetate, urea and glucose is 1:0.55:0.14.

[0035] Example 1

[0036] According to another embodiment of the present invention, a method for preparing a multi-microorganism self-repairing cement-based material is also disclosed, comprising:

[0037] Preparation of liquid culture medium: Use deionized water to prepare a multi-microorganism liquid culture solution, sterilize the culture solution, and then add a 4% by mass urea solution to obtain a liquid culture medium.

[0038] Inoculation: Mix the cultured Bacillus pasteurianus, Saccharomyces cerevisiae and carbonic anhydrase bacteria in a volume ratio of 7:1:2 and inoculate into the liquid culture medium.

[0039] Cultivate polymicroorganisms: Place the inoculated liquid culture medium in a shaker and continue culturing for 23-25 ​​hours to obtain a concentration of 10 9cells / ml of a multi-microbial mixture.

[0040] Preparation of mineralizer: Mix calcium acetate, urea and glucose in a mass ratio of 1:0.55:0.14.

[0041] Preparation of nutrients: Thoroughly mix 0.5 g of peptone, 0.1 g of beef extract, 0.18 g of yeast extract powder, 0.16 g of disodium hydrogen phosphate, 0.01 g of potassium chloride, 0.065 g of calcium carbonate, 0.2 g of sucrose, 0.03 g of ammonium sulfate, and 0.03 g of magnesium sulfate to obtain a total of 1.28 g of nutrients.

[0042] Mixing and stirring: pour 650g of cement, 1300g of sand, 292.5g of water, 1.28g of nutrients, 32.5g of multi-microorganism mixed solution and 12.0g of mineralizer into a mixer and stir evenly to obtain a multi-microorganism crack self-repairing cement-based material.

[0043] Example 2

[0044] According to another embodiment of the present invention, a method for preparing a multi-microorganism self-repairing cement-based material is also disclosed, comprising:

[0045] Preparation of liquid culture medium: Use deionized water to prepare a multi-microorganism liquid culture solution, sterilize the culture solution, and then add a 4% by mass urea solution to obtain a liquid culture medium.

[0046] Inoculation: Mix the cultured Bacillus pasteurianus, Saccharomyces cerevisiae and carbonic anhydrase bacteria in a volume ratio of 7:1:2 and inoculate into the liquid culture medium.

[0047] Cultivate polymicroorganisms: Place the inoculated liquid culture medium in a shaker and continue culturing for 23-25 ​​hours to obtain a concentration of 10 9 cells / ml of a multi-microbial mixture.

[0048] Preparation of mineralizer: Mix calcium acetate, urea and glucose in a mass ratio of 1:0.55:0.14.

[0049] Preparation of nutrients: 1 g of peptone, 0.2 g of beef extract, 0.36 g of yeast extract powder, 0.32 g of disodium hydrogen phosphate, 0.02 g of potassium chloride, 0.13 g of calcium carbonate, 0.4 g of sucrose, 0.06 g of ammonium sulfate, and 0.06 g of magnesium sulfate were fully mixed to obtain a total of 2.56 g of nutrients.

[0050] Mixing and stirring: pour 650g of cement, 1300g of sand, 260g of water, 2.56g of nutrients, 65g of multi-microorganism mixed solution and 24.0g of mineralizer into a mixer and stir evenly to obtain a multi-microorganism crack self-repairing cement-based material.

[0051] Example 3

[0052] According to another embodiment of the present invention, a method for preparing a multi-microorganism self-repairing cement-based material is also disclosed, comprising:

[0053] Preparation of liquid culture medium: Use deionized water to prepare a multi-microorganism liquid culture solution, sterilize the culture solution, and then add a 4% by mass urea solution to obtain a liquid culture medium.

[0054] Inoculation: Mix the cultured Bacillus pasteurianus, Saccharomyces cerevisiae and carbonic anhydrase bacteria in a volume ratio of 7:1:2 and inoculate into the liquid culture medium.

[0055] Cultivate polymicroorganisms: Place the inoculated liquid culture medium in a shaker and continue culturing for 23-25 ​​hours to obtain a concentration of 10 9 cells / ml of a multi-microbial mixture.

[0056] Preparation of mineralizer: Mix calcium acetate, urea and glucose in a mass ratio of 1:0.55:0.14.

[0057] Preparation of nutrients: 1.5 g of peptone, 0.3 g of beef extract, 0.54 g of yeast extract powder, 0.48 g of disodium hydrogen phosphate, 0.03 g of potassium chloride, 0.2 g of calcium carbonate, 0.6 g of sucrose, 0.09 g of ammonium sulfate, and 0.09 g of magnesium sulfate were fully mixed to obtain a total of 3.83 g of nutrients.

[0058] Mixing and stirring: pour 650g of cement, 1300g of sand, 227.5g of water, 3.83g of nutrients, 97.5g of multi-microorganism mixed solution and 36g of mineralizer into a mixer and stir evenly to obtain a multi-microorganism crack self-repairing cement-based material.

[0059] like Figures 1 to 5 As shown, according to another embodiment of the present invention, a specific process of conducting a self-repairing effect verification experiment on the multi-microorganism crack self-repairing cement-based material provided in the above-mentioned embodiments 1, 2 and 3 is also disclosed, including:

[0060] like Figure 1As shown, a self-repairing cement-based material specimen was prepared using the multi-microorganism crack self-repairing cement-based material provided by the present invention, and the specimen was a 40mm×40mm×160mm rectangular mortar specimen. After the prepared specimen was placed in water for curing for 28 days, the specimen was broken into two halves using a flexural testing machine, and then the broken specimens were tied together using rubber bands, and then insect pins of different diameters were inserted into the cracks to control the crack width of the specimen. The width of the crack was measured by a crack width tester to ensure that the crack width of the specimen was 0.2-0.4 mm. After the crack was made, the specimens were separated and placed in the corresponding curing box, and water was added for immersion and curing (the water temperature was controlled at 25-35°C), and the water level was kept about 10mm higher than the surface of the specimen. The specimen repair cycle was set to 28 days.

[0061] The characterization indicators of self-repair performance include: area repair rate, compressive strength recovery rate and crack repair depth.

[0062] The evaluation methods for area repair rate include:

[0063] like Figure 2 As shown in the figure, the image of the specimen that has been cracked but not repaired is collected. The crack surface photos are processed using image processing software (ImageJ), the threshold is adjusted to distinguish the crack area and non-crack area of ​​the concrete specimen, and then the pixel points in the crack area are calculated to obtain the area of ​​the crack area.

[0064] Calculate the crack area repair rate:

[0065] Area repair rate =

[0066] In the formula, Indicates the initial area of ​​the crack before repair (mm 2 ); Indicates the area of ​​the crack after repair (mm 2 ).

[0067] Figure 2 (a) is a schematic diagram showing the crack repair of the specimen made of the material of Example 1, Figure 2 (b) is a schematic diagram showing the crack repair of the specimen made of the material of Example 2, Figure 2 (c) is a schematic diagram showing the crack repair of the specimen made of the material of Example 3. The area repair rates of the cracks of the cement mortar specimens of different example groups at 3d, 7d, and 28d are shown in the following table:

[0068] Group 3d crack area repair rate (%) 14d Crack Area Repair Rate (%) 28d crack area repair rate (%) Example 1 18.5 23.4 35.2 Example 2 43.7 62.8 70.6 Example 3 67.4 92.5 100

[0069] The evaluation methods for compressive strength recovery rate include:

[0070] When cracks occur in cement-based materials, the cracks are repaired to a certain extent due to the secondary healing formed by cement hydration, but the recovery effect in this case is limited. However, due to the ability of microorganisms to mineralize and produce calcium, the cracks of the microbial self-repairing specimens are filled with CaCO3 precipitates, and the originally loose mortar matrix is ​​consolidated, thereby obtaining a higher strength recovery rate. Calculate the compressive strength recovery rate:

[0071] R=

[0072] Where R represents the strength recovery rate of the mortar specimen, C1 represents the compressive strength of the mortar specimen after repair (MPa), and C0 represents the compressive strength of the mortar specimen before repair (MPa).

[0073] The compressive strength and calculated strength recovery rate of the cement mortar specimens of different embodiment groups before and after 28 days of crack repair are shown in the following table:

[0074] Group <![CDATA[C0(MPa)]]> <![CDATA[C1(MPa)]]> R（%） Example 1 24 10.4 43.3 Example 2 28.7 14.1 49 Example 3 24.6 13 52.8

[0075] Evaluation methods for crack repair depth include:

[0076] The multi-microbial self-healing cement-based material utilizes the characteristics of anaerobic bacteria (yeast) in an anaerobic environment, combines it with urease bacteria (Bacillus pasteurianus), and makes the self-healing material achieve better results in crack depth. The specimens repaired for 28 days were disconnected along the cracks, and the amount of calcium carbonate precipitation in the depth of the cracks was observed and photographed. The layered sampling method was used to divide the specimen section into multiple gradients along the vertical (depth) direction. Every 5 mm in the vertical direction was taken as a gradient, and the precipitates were taken separately. The scraping method was used. The taken precipitates were placed in a 50℃ oven for drying for 48 hours, and then the microscopic morphology was observed using SEM (scanning electron microscope).

[0077] The SEM morphology analysis results are as follows Figure 3 As shown, through Figure 3 (a) It can be found that in the SEM image of the sample obtained above 5 mm on the specimen section, there are a large number of dense and large calcites, and the calcium carbonate precipitation structure here is stable; Figure 3 (b) Calcite in the 5-10 mm range is loosely distributed and its quantity is significantly reduced compared to (a). Some needle-like substances appear, which may be the decomposition of calcite. Figure 3 (c) There is almost no calcite or vaterite above 10 mm. In summary, the repair effect of the composite microbial self-healing material on the mortar depth can reach about 10 mm.

[0078] Microscopic analysis of mineralized products in fractures:

[0079] After 28 days of repair, it can be observed that the cracks are filled with sedimentary minerals. The repair products are analyzed using microscopic testing techniques such as XRD (X-ray diffraction), SEM, and EDS (energy dispersive X-ray spectrometer).

[0080] The XRD analysis results are as follows Figure 4 As shown in the figure, from the dotted box mark, we can see that the highest peak of each group of sediments occurs at about 29°, which is calcium carbonate crystal. After comparative analysis, it is divided into vaterite and calcite.

[0081] The results of SEM microstructure analysis are as follows: Figure 5 As shown, Figure 5 (a) is the microscopic morphology of the precipitate at the crack of the specimen made of the material of Example 1. Figure 5 (b) is the microscopic morphology of the precipitate at the crack of the specimen made of the material of Example 2. Figure 5 (c) is the microscopic morphology of the precipitate at the crack of the specimen made of the material of Example 3. It can be found that the microscopic morphology of each group of precipitates is vaterite-type calcium carbonate crystals or calcite-type calcium carbonate crystals. In addition, EDS microscopic energy spectrum analysis was performed on the precipitates of the self-healing specimens. The results showed that the main substances of the precipitates at the cracks are composed of C, O, and Ca atoms, which is consistent with the analysis results of XRD, further indicating that the white substance filling the cracks is calcium carbonate.

[0082] In summary, the multi-microorganism self-repairing cement-based material disclosed in the present invention is different from the traditional microbial self-repairing cement-based material. The multi-microorganism self-repairing cement-based material disclosed in the present invention does not require external moisture and oxygen and other substances to penetrate into the cracks to activate the bacteria. It can be repaired through the capillary water provided by the cement-based material, and the synergistic mineralization of anaerobic bacteria and jelly-like Bacillus. Through the synergistic mineralization of multi-microorganisms, the problem of insufficient repair depth caused by low oxygen concentration in the deep cracks and slow repair rate using a single strain can be solved. At the same time, it solves the current major problem of microbial crack cement-based materials, which require external moisture and oxygen to penetrate into the cracks to activate the bacteria before subsequent mineralization repair reactions can be carried out. While repairing surface cracks, it greatly improves the crack repair depth of cement-based materials after cracking, and significantly shortens the repair cycle of microcracks in cement-based materials. It overcomes the problem of environmental restrictions on traditional microbial self-repairing materials, so that cement-based materials have excellent self-repairing ability, thereby improving durability and extending the service life of the structure.

[0083] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A multi-microorganism crack self-repairing cement-based material, characterized in that: include: The invention relates to a method for preparing a composite material comprising 2118-2243 parts of a cement base material, 32-163 parts of a multi-microorganism mixed solution and 12-61 parts of a mineralizer in proportion by mass; the cement base material comprises cement, sand, water and nutrients for the metabolism and growth of the multi-microorganisms; the multi-microorganism mixed solution comprises a mixture of urease-type bacteria, anaerobic bacteria and jelly-like Bacillus with the ability to induce mineralization and a liquid culture medium; and the mineralizer comprises calcium acetate, urea and glucose.

2. The multi-microorganism crack self-repairing cement-based material according to claim 1, characterized in that: The concentration of the multi-microorganism mixture is 1×10 9 cells / mL-8×10 9 cells / mL, and the total weight of the multi-microorganism mixture is 10%-50% of the total water consumption.

3. The multi-microorganism crack self-repairing cement-based material according to claim 1, characterized in that: The mixture specifically includes Bacillus pasteurianus, Saccharomyces cerevisiae and carbonic anhydrase bacteria, and the Bacillus pasteurianus, Saccharomyces cerevisiae and carbonic anhydrase bacteria are mixed in a volume ratio of 7:1:2 to obtain the mixture.

4. The multi-microorganism crack self-repairing cement-based material according to claim 1, characterized in that: The liquid culture medium contains 15 g of peptone, 3 g of beef extract, 10 g of glucose, 5.6 g of yeast extract powder, 5 g of disodium hydrogen phosphate, 0.28 g of potassium chloride, 2 g of calcium carbonate, 20 g of sucrose, 1 g of ammonium sulfate, 1 g of magnesium sulfate and an appropriate amount of deionized water per 1 L.

5. The multi-microorganism crack self-repairing cement-based material according to claim 1, characterized in that: The cement base material specifically includes, by weight, 650 parts of cement, 1,300 parts of sand, 162-292 parts of water, and 1-7 parts of nutrients; the nutrients specifically include, by weight, 50-250 parts of peptone, 10-50 parts of beef extract, 18-90 parts of yeast extract powder, 16-80 parts of disodium hydrogen phosphate, 1-5 parts of potassium chloride, 6-33 parts of calcium carbonate, 20-100 parts of sucrose, 3-16 parts of ammonium sulfate, and 3-16 parts of magnesium sulfate.

6. The multi-microorganism crack self-repairing cement-based material according to any one of claims 1 to 5, characterized in that: The weight ratio of the multi-microorganism mixed solution to the mineralizer is 1:0.

37.

7. The multi-microorganism crack self-repairing cement-based material according to any one of claims 1 to 5, characterized in that: The weight ratio of the calcium acetate, the urea and the glucose is 1:0.55:0.

14.

8. A method for preparing a multi-microorganism self-repairing cement-based material, characterized in that: include: Preparation of multi-microorganism mixed solution: Use deionized water to prepare multi-microorganism liquid culture solution, sterilize the culture solution, and then add 4% urea solution by mass to obtain liquid culture medium; mix the cultured Bacillus pasteurianus, Saccharomyces cerevisiae and carbonic anhydrase bacteria in a volume ratio of 7:1:2, and inoculate them into the liquid culture medium; place the inoculated liquid culture medium in a shaker and continue to culture for 23-25 ​​hours to make the concentration of the multi-microorganism mixed solution 1×10 9 cells / ml-8×10 9 cells / ml; Preparation of mineralizer: Mix calcium acetate, urea and glucose in a mass ratio of 1:0.55:0.14; The cement base material, multi-microorganism mixed solution and mineralizer are fully mixed according to the proportion to obtain the multi-microorganism crack self-repairing cement-based material.

9. The method for preparing a multi-microorganism self-repairing cement-based material according to claim 7, characterized in that: In the step of preparing the multi-microorganism mixture, sterilization treatment refers to sterilization treatment for 25min-35min under the conditions of temperature 120°C and pressure 0.1MPa; the temperature of the shaker is 35°C and the rotation speed is 170rpm / min; the concentration of the urea solution is 4mol / L; and inoculation is performed at 10% of the volume of the liquid culture medium.

10. The method for preparing a multi-microorganism self-repairing cement-based material according to claim 7, characterized in that: The preparation method of the cement substrate comprises: Fully mixing 50-250 parts by weight of peptone, 10-50 parts by weight of beef extract, 18-90 parts by weight of yeast extract powder, 16-80 parts by weight of disodium hydrogen phosphate, 1-5 parts by weight of potassium chloride, 6-33 parts by weight of calcium carbonate, 20-100 parts by weight of sucrose, 3-16 parts by weight of ammonium sulfate, and 3-16 parts by weight of magnesium sulfate to obtain a nutrient; The cement base material is prepared by mixing 650 parts by weight of cement, 1300 parts by weight of sand, 162-292 parts by weight of water, and 1-7 parts by weight of nutrients.

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