Cementitious material crack self-healing particles and methods of making and using same

Abstract

The application discloses a cement-based material crack self-repairing particle and a preparation and use method thereof, which comprises functional microorganisms, a carrier and an outer protective layer; the functional microorganisms are loaded in the carrier; and the outer protective layer is wrapped on the outer surface of the carrier; the preparation method comprises the following steps: modifying the carrier first, then loading the functional microorganisms in the carrier, and then wrapping the outer protective layer on the outside of the carrier. In use, the self-repairing particle is directly mixed into the cement-based material, and a nutrient agent can be further added, so that the cracks in the cement-based material can be automatically repaired. The self-repairing particle of the application not only does not reduce the mechanical properties of the cement-based material like the existing self-repairing particle, but also can even improve the mechanical properties of the cement-based material, improve the durability of the cement-based material, has a good effect on repairing cracks, and can purify the contacted sewage to a certain extent.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of concrete crack repair, and particularly relates to a cement-based material crack self-repairing particle and a preparation and use method thereof. BACKGROUND

[0002] The statements in this section merely provide background information related to the present disclosure and can not constitute the prior art.

[0003] Concrete belongs to brittle material, and the tensile strength is far lower than the compressive strength. When the tensile stress exceeds the instant tensile strength, cracks will appear in the concrete. Once the concrete structure or component in the water environment cracks, water carrying various pollutants, corrosive media, microorganisms and the like can enter the interior of the concrete, and physical and chemical actions will occur between the water and the interior organization of the concrete material, thereby gradually destroying the cementing ability of the concrete material, affecting the engineering durability, and threatening the safe operation of the engineering. Therefore, it is necessary to effectively protect the concrete building or component with potential damage risk and repair the concrete structure subjected to the physical and chemical actions of the corrosive media.

[0004] Regarding the repair of the concrete cracks, the self-repairing technology can solve the problems that cannot be solved by the traditional methods. Compared with the traditional crack repair technology, the crack self-repairing has the unique property of prolonging the service life of the concrete, and is helpful to ensure the safety performance and durability of the major civil infrastructure such as high-rise buildings, bridges, nuclear power plants and water conservancy projects.

[0005] The concrete crack self-repairing refers to that the concrete releases or generates new substances to self-seal and heal the cracks under the action of external or internal conditions.

[0006] The self-repairing technology can be traced back to 1925 when Abram found that the concrete test piece cracked in the tensile strength test was placed outdoors for 8 years, the cracks were healed, and the strength was increased by two times than before. The concrete crack self-repairing technology mainly includes four kinds: crystallization precipitation, permeation crystallization, polymer solidification and electrolytic deposition technology.

[0007] There are many kinds of concrete crack self-repairing materials, and the repair effects are quite different. The main problems are that the self-repairing material may have a negative effect on the performance of the concrete body, and the effect after the repair cannot reach the expectation.

[0008] The use of the biological mineralization principle to repair the concrete cracks is a new technology developed in recent years. The biological mineralization is the process in which the living body manufactures organic-inorganic composite materials by regulating the nucleation, orientation, growth and assembly of inorganic minerals. The biological mineralization is a very common phenomenon in nature, such as corals, shells and the like. The alkali-resistant bacteria group is usually loaded in the porous material, and then mixed into the cement mortar or cement concrete.

[0009] Due to high porosity, the porous material is usually low in strength. During the construction operation such as mixing, transporting, pouring and vibrating, the porous material is easily broken under the impact and friction of sand and stone and external force. When the cement-based material appears cracks, the microorganism has already died and cannot play a role in repairing the cracks. The broken porous material is a weak phase in the cement-based material, which not only affects the strength of the cement-based material, but also affects the durability of the cement-based material, and further endangers the safety of the structure.

[0010] The microorganism load of the porous material depends on the pore structure and surface structure of the porous material. The porous material with large particle size, high porosity, large specific surface area or large dosage has high total microorganism load and good crack repair effect. However, the porous material with large particle size, high porosity, large specific surface area and large dosage has a negative impact on the workability, strength and durability of the cement mortar and cement concrete.

[0011] The porous material is also widely used in sewage treatment due to its high ion exchange capacity. In order to improve the ammonia nitrogen removal rate of the porous material, modification of the porous material is also a common technical means. However, the modification of the porous material for sewage treatment does not need to consider the strength of the material. The larger the specific surface area of the modified porous material, the higher the proportion of small diameter ion exchange, and the better the sewage treatment effect.

[0012] In order to obtain satisfactory crack repair effect, the porous material for self-repairing of cracks in the cement-based material needs to have large specific surface area, sufficient strength and high microorganism load, and the radius of the ion used for modification and the number thereof should not have a negative impact on the hydration process of the cement-based material and the strength and durability of the hardened cement-based material.

[0013] Some existing technologies use fly ash as an outer protective layer of the porous material. However, due to the high strength of the Al-O bond and Si-O bond in the fly ash, a high alkali concentration is needed to destroy the Al-O bond and Si-O bond and release the internal microorganism. However, high alkali content leads to large shrinkage of the wall material and easy cracking. Once the wall material cracks, it cannot play its protective role. Moreover, under the action of alkali, the fly ash generates a three-dimensional network structure of alumino-silicate with flocculent and zeolite-like structure, and the polymerization degree is as high as hundreds or thousands, and Si-O-Si, Si-O-Al and Al-O-Al are connected together. After being mixed into the cement-based material, there is an obvious interface transition zone between the outer surface of the wall material and the cement-based material, which becomes a weak phase in the cement-based material. SUMMARY

[0014] The cement-based material crack self-repairing particle provided by the present application can not only efficiently repair the cracks of the cement-based material, but also improve the mechanical properties and durability of the cement-based material.

[0015] The technical scheme of the present application is as follows:

[0016] A cement-based material crack self-repairing particle comprises functional microorganisms, a carrier and an outer protective layer.

[0017] The functional microorganisms are loaded in the carrier.

[0018] The outer protective layer is wrapped on the outer surface of the carrier.

[0019] The carrier is modified zeolite, which is modified by microwave heating treatment in a salt solution.

[0020] The outer protective layer is an alkali earth system geopolymer cementing material mixed with limestone powder, and the thickness of the outer protective layer is 0.1-0.5 mm.

[0021] The geopolymer cementing material has high strength and fast strength development, and is suitable for being used as the outer protective layer of the modified zeolite. However, the geopolymer cementing material has large early shrinkage and is easy to crack; the higher the alkali content, the faster the strength development of the geopolymer cementing material, the higher the shrinkage growth rate, and the easier the cracking. The outer protective layer is the alkali earth system geopolymer cementing material mixed with limestone powder, which can effectively ensure the strength of the outer protective layer and the protection of the carrier loaded with the functional microorganisms.

[0022] Firstly, the technical problem of large shrinkage and easy cracking of the geopolymer cementing material is solved. The limestone powder can be used as micro aggregate to inhibit the shrinkage of the geopolymer cementing material; since the alkali earth system geopolymer cementing material is used, the Ca-O bond in the ground granulated blast furnace slag powder can be broken at a low alkalinity, so that low modulus and low alkalinity sodium silicate is used, thereby reducing the alkali content in the cementing material and helping to reduce the shrinkage of the cementing material; the zeolite has a particle size of 1.1-2.4 mm, and compared with large particle size particles, the zeolite has small surface area and small wrapping area of the outer protective layer, and the thickness of the outer protective layer is 0.1-0.5 mm, so that the small particle size and the thin thickness of the outer protective layer help to reduce the shrinkage of the cementing material.

[0023] Secondly, the technical problem of low strength of the carrier of the functional microorganism is solved. The zeolite belongs to a porous material and has low strength. Although the modification of the zeolite by using the salt solution + microwave heating technology avoids the significant reduction of the strength, the internal structure of the modified zeolite is still damaged, and thus the strength of the modified zeolite is still reduced. The carrier of the functional microorganism is wrapped by the alkali earth geopolymer cementitious material doped with limestone powder. The alkali earth geopolymer cementitious material uses low-alkalinity sodium water glass, does not damage the Al-O bond and the Si-O bond of the zeolite, and does not further damage the structure of the modified zeolite. In addition, the hydration product of the alkali earth geopolymer cementitious material can penetrate into the macropores of the zeolite, so that the hydration product and the zeolite form an interpenetrating structure at the interface between the outer protective layer and the zeolite, and the technical problem of the reduction of the strength of the self-healing particle caused by the interface defect is eliminated. The alkali earth geopolymer cementitious material doped with limestone powder has high strength, and the strength of the self-healing particle obtained by wrapping the carrier of the functional microorganism is significantly improved and is higher than the strength of the unmodified zeolite, which indicates that the modified zeolite is well protected. At the same time, the water absorption of the self-healing particle is significantly reduced, which indicates that the outer protective layer is dense and well protects the functional microorganism.

[0024] According to a preferred embodiment, the modified zeolite is prepared by the following specific method:

[0025] 1-5 parts of natural zeolite particles with a particle size of 1.1-2.4 mm are added to 20-30 parts of a sodium chloride solution with a concentration of 1.0-2.5 mol / L, the temperature is set to 50-80℃, and the microwave treatment is performed for 20-40 min;

[0026] The solid-liquid mixture of the zeolite after the microwave treatment is subjected to solid-liquid separation at a centrifugal speed of 4000-5000 rpm, the solid phase is washed with water meeting the water requirement of the cement-based material for not less than 4 times, and is dried at 50-60℃ until the water content is not more than 2%, to obtain the modified zeolite, i.e. the carrier.

[0027] The zeolite modification technology does not significantly damage the structure of the zeolite and does not significantly reduce the strength of the zeolite. The carrier uses the zeolite which is rich in material sources, and the modification uses the microwave heating technology of the natural zeolite in the salt solution, i.e. the salt solution + microwave heating technology. If the microwave heating technology is directly used, the thermal effect and the non-thermal effect of the microwave act on the zeolite, so that the defects in the zeolite crystal increase, the pore volume increases, the specific surface area increases, and the ammonia nitrogen adsorption capacity in the sewage increases. However, for the self-healing particle of the cement-based material, the increase of the pore volume in the zeolite reduces the strength of the zeolite, and thus the strength of the self-healing particle is reduced. Under the action of mechanical stirring, collision, friction and extrusion between the component materials, the self-healing particle is broken, which not only does not achieve the repair effect, but also damages the workability, mechanical properties and durability of the cement-based material;

[0028] Compared with the modification of zeolite by directly using the microwave heating technology, the modification of zeolite by using the salt solution + microwave heating technology, the zeolite is in the NaCl solution, the temperature field is uniform in the microwave heating process, and the optimization of the pore structure is more reasonable, and whether the small pore ratio, the total pore volume or the average pore diameter is lower than the former, and the problem of significant reduction of the strength of the zeolite caused by the modification of the zeolite by using the microwave heating technology is overcome. The way of first salt solution treatment and then microwave treatment, the early salt solution treatment: the alkali earth metal ions with large atomic radius such as Ca 2+ , Mg 2+ in the zeolite pore are replaced by Na + ions with small atomic radius, but the surface state of the pores changes in the subsequent microwave treatment process, the Na + ions in the zeolite pores migrate, which is not conducive to the loading of microorganisms on the modified zeolite.

[0029] According to a preferred embodiment, the cylinder pressure strength of the carrier is not less than 85% of that before modification.

[0030] According to a preferred embodiment, the outer protective layer comprises 1 part of finely ground blast furnace slag powder with a specific surface area not less than 350 m 2 / g, 0.2-0.5 parts of 300-600 mesh limestone powder, 0.8-1.4 parts of sodium water glass with a modulus of 1.2-1.5, and 0.6-1.0 parts of water meeting the mixing water requirements of cement-based materials.

[0031] According to a preferred embodiment, the functional microorganism is the first generation of bacteria liquid of microbial freeze-dried powder in a liquid medium, which is cultured to the exponential growth phase at a suitable temperature; the culture temperature and time are determined according to the type of microbial freeze-dried powder and the composition of the liquid medium; and the microbial freeze-dried powder is a non-pathogenic microbial freeze-dried powder capable of producing urease.

[0032] Preferably, the microbial freeze-dried powder is any one or a mixture of the two of Bacillus cohnii and Bacillus pasteurii.

[0033] Another aspect of the present application provides a preparation method of cement-based material crack self-repairing particles, which specifically comprises the following steps:

[0034] S1: preparing functional microorganisms and carriers;

[0035] S1.1: preparing functional microorganisms:

[0036] The microbial freeze-dried powder is selected from any one or a mixture of the two of Bacillus cohnii and Bacillus pasteurii;

[0037] Firstly, 3 g of beef extract, 5 g of peptone, and 20 g of urea are added to distilled water to obtain 1 L of liquid medium. Then, 200 μL of microbial freeze-dried powder is selected and activated in the liquid medium at 30°C for 24 hours to obtain a functional microbial solution.

[0038] S1.2: Preparation of carrier: modified zeolite;

[0039] 1-5 parts of natural zeolite particles with a particle size of 1.1-2.4 mm are added to 20-30 parts of a solution of sodium chloride with a concentration of 1.0-2.5 mol / L, and microwave treatment is performed for 20-40 min at a temperature of 50-80°C. The zeolite-sodium chloride solid-liquid mixture after microwave treatment is subjected to solid-liquid separation at a centrifugal speed of 4000-5000 rpm, and the solid phase is washed with water that meets the requirements of cement-based material mixing water for not less than 4 times. Drying is performed at 50-60°C until the water content is not more than 2%, to obtain the modified zeolite, i.e., the carrier.

[0040] S2: Carrier loading functional microorganisms: vacuum impregnation method is adopted;

[0041] S2.1: The carrier after step S1.2 is weighed and placed in a vacuum pot, and the volume of the carrier does not exceed the maximum volume of solid materials that the vacuum pot can accommodate;

[0042] S2.2: The vacuum pot is set to a negative pressure of 0.06 MPa-0.1 MPa;

[0043] S2.3: The functional microbial solution is added to the vacuum pot at a solid-liquid ratio (g / mL) of 1-2:40, and the pressure in the vacuum pot is maintained at the set negative pressure during the process, so that the functional microorganisms are fully attached to the carrier, and all valves are closed;

[0044] S2.4: The vacuum pot after step S2.3 is placed in a shaking box and shaken at 150 rpm for 40-60 min to increase the contact area between the functional microorganisms and the carrier;

[0045] S2.5: The carrier is taken out from the vacuum pot after step S2.4, filtered with a screen, and the excess microbial solution on the surface of the carrier is filtered out. Then, the carrier is dried at a temperature of 30-50°C until the water content is not more than 10%, to obtain the carrier loaded with functional microorganisms.

[0046] S3: Wrapping of outer protective layer;

[0047] S3.1: Preparation of outer protective layer slurry:

[0048] The components of the outer protective layer are weighed, water is first added to the sodium water glass and stirred uniformly, then the finely ground blast furnace slag powder and limestone powder are added and stirred until uniform to obtain the outer protective layer slurry;

[0049] S3.2: feeding and coating: the functional microorganism-loaded carrier obtained in step S2 is first uniformly added into a granulator, and then the outer protective layer slurry is added into the granulator for coating in three or more times with an interval of 30 s each time, and the process is repeated until the outer protective layer is completely added into the granulator; the rotation speed of the granulator is 50-80 rpm / min; the mass ratio of the functional microorganism-loaded carrier to the outer protective layer slurry is 5:1-2:1;

[0050] S3.3: curing: after the coating is completed, the particles coated with the outer protective layer slurry are placed in an environment with a temperature of 20±1℃ and a relative humidity (RH) of greater than 90% for curing for 7 days, and then naturally cured for 14-21 days;

[0051] S3.4: drying and sizing: the particles are dried to a constant weight at a temperature of 40±2℃, with a requirement that the water content is not higher than 2%; and then sieved and sized, to obtain the cement-based material crack self-repairing particles.

[0052] Another aspect of the present application provides a method for using the cement-based material crack self-repairing particles, which specifically comprises the following steps:

[0053] Step S1: the self-repairing particles are added into the cement-based material, and the addition amount is 25-50% of the mass of the cementitious material in the cement-based material, and at the same time, the mass of the fine aggregate in the cement-based material is correspondingly reduced by 1-2%;

[0054] Step S2: the nutrient agent is also added into the cement-based material, and the addition amount of the nutrient agent is 0.5-2.5% wt of the mass of the cementitious material in the cement-based material.

[0055] According to a preferred embodiment, the nutrient agent is a soluble calcium source, and the soluble calcium source is calcium lactate or calcium chloride.

[0056] The principle of repairing cracks in the cement-based material according to the present application is as follows:

[0057] (1) The outer protective layer of the self-repairing particles can protect the microorganisms from the influence of the high-alkali and high-stress environment. When cracks appear in the cement-based material, air and water will enter the cracks; the outer protective layer of the self-repairing particles at the cracks is broken along with the appearance of the cracks in the cement-based material.

[0058] (2) The functional microorganisms begin to recover after contacting with the air and water, and the urease microorganisms produce urease in the growth and reproduction process, and the urease decomposes urea in the sewage into ammonia (NH3) and carbon dioxide (CO2), and the CO2 is further dissolved to form carbonate ions; the nutrient agent, the sewage, and the limestone powder in the outer protective layer provide Ca 2+The negatively charged cell wall can not only chelate calcium ions, promote the generation of calcium carbonate (CaCO3), but also provide nucleation sites for calcium carbonate deposition. Through a series of chemical reactions, calcium carbonate gradually deposits at the crack site, thereby repairing the crack.

[0059] (3) In sewage, the phosphate (PO4 3- ) and sulfate (SO4 2- ) in the sewage generate slightly soluble calcium phosphate (Ca3(PO4)2) and calcium sulfate (CaSO4), which cooperate with calcium carbonate to repair the cracks in cement-based materials.

[0060] The above chemical reaction equations are shown in equations (1) to (5): (1):

[0062]

[0063] (2) H2CO3→CO3 2- +2H + ;

[0064] (3) Cell-Ca3 2- +CO3 2- →Cell+CaCO3;

[0065] (4) Cell-Ca3 2- +SO4 2- →Cell+CaSO4;

[0066] (5) Cell-Ca3 2- +PO4 2- →Cell+Ca3(PO4)2.

[0067] Like the principle of zeolite water purification for water treatment, the modified zeolite used in the present application has high porosity and high ion exchange capacity. Under the action of electrostatic adsorption and ion exchange, the self-repairing particles can purify sewage in contact with cement-based materials to a certain extent.

[0068] Compared with the existing technology, the present application has the following beneficial effects:

[0069] 1. A cement-based material crack self-repairing particle, wherein the carrier - modified zeolite provides a load capacity for microorganisms, has good mechanical strength, does not affect the strength and durability of cement-based materials, i.e. avoids negative effects on cement-based materials while providing crack repair function.

[0070] 2. A method for using cement-based material crack self-repairing particles, the cement-based material crack self-repairing particles and nutrients are mixed in an appropriate amount, which will not have a negative impact on the workability, mechanical properties and durability of the cement-based material, and can even improve and enhance the aforementioned properties of the cement-based material. The outer protective layer of the cement-based material crack self-repairing particles is an alkali earth-based geopolymer cementing material mixed with limestone powder, and the hydration product thereof is C-S-H gel with low polymerization degree, which is the same as the main hydration product of the cement-based material. When the self-repairing particles are mixed into the cement-based material, the cement hydration product preferentially nucleates and grows on the outer surface of the self-repairing particles. The interface between the outer protective layer of the self-repairing particles and the cement-based material is tightly combined, and there is no obvious interface transition zone, which eliminates the technical problem of strength reduction of the cement-based material caused by interface defects between the cement-based material and the self-repairing particles. The interface between the cement-based material and the self-repairing particles is stronger than the interface between the cement-based material and quartz sand, and the interface is further enhanced by the morphology effect. Therefore, the self-repairing particles can improve the workability of the cement-based material and enhance the mechanical properties and durability of the cement-based material.

[0071] 3. A cement-based material crack self-repairing particle, which has high crack repair efficiency and good repair effect. The pore structure of the modified zeolite is optimized, and the alkali earth metal ions such as Ca 2+ , Mg 2+ with large atomic radii in the pores are replaced by Na + ions with small atomic radii. Microorganisms are usually negatively charged, so the modified zeolite is more likely to load microorganisms, and the amount of microorganisms that can be loaded is increased, which helps to efficiently repair cracks. The self-repairing particles utilize the components in sewage and the synergistic effect of microbial mineralization deposition to purify water and generate more compact and stronger sediment to plug the cracks of the cement-based material, further improving the repair effect. The permeability resistance of the repaired mortar and concrete is significantly improved, and the micro-morphology of the repair sediment is good.

[0072] 4. A cement-based material crack self-repairing particle, which still has good cement-based material crack repair effect in sewage. It is suitable for crack repair of mortar, concrete buildings or components in contact with water, especially mortar, concrete and the like in contact with contaminated and eutrophic water bodies, and can purify sewage in contact with it to a certain extent. BRIEF DESCRIPTION OF DRAWINGS

[0073] Figure 1 A schematic diagram of pre-prepared cracks in cement-based materials;

[0074] Figure 2 A schematic diagram of pre-prepared cracks in Example 3 under a magnifying glass. In (a), the state of the cracks before repair; in (b), the state of the cracks after repair;

[0075] Figure 3 A schematic diagram of the test method for the permeability resistance of cement-based materials. DETAILED DESCRIPTION

[0076] It should be noted that the test methods in the following examples are all conventional methods unless otherwise specified. The test materials used in the following examples are all commercially available. In the quantitative tests in the following examples, three repeated tests were set up, and the results were averaged.

[0077] The features and properties of the present application are further described in detail below in conjunction with examples.

[0078] Example 1

[0079] The cement-based material crack self-repairing particle according to the present application is prepared by the following method comprising the following steps:

[0080] S1: preparing functional microorganisms and carriers

[0081] S1.1: preparing functional microorganisms

[0082] First, 3 g of beef extract, 5 g of peptone, and 20 g of urea were added to 1 L of distilled water to obtain 1 L of liquid culture medium. Then, 220 μL of Bacillus pasteurii freeze-dried powder was selected and activated, and cultured in the liquid culture medium at a temperature of 30°C for 24 h to obtain a first-generation functional microorganism bacterial solution.

[0083] S1.2: preparing carriers

[0084] 1 part by mass of natural zeolite particles with a particle size of 1.1-2.4 mm was added to 20 parts by mass of a sodium chloride solution with a concentration of 2.0 mol / L, and the temperature was set to 80°C for microwave treatment for 20 min. The zeolite-sodium chloride solid-liquid mixture after microwave treatment was subjected to solid-liquid separation at a centrifugal speed of 5000 rpm, and the solid phase was washed with tap water for 4 times. Drying was performed at 55°C until the water content was 2%, to obtain the modified zeolite, i.e., the carrier.

[0085] S2: preparing carriers loaded with functional microorganisms

[0086] S2.1: the carrier was weighed and placed in a vacuum pot, and the volume of the carrier was not more than two-thirds of the volume of the vacuum pot;

[0087] S2.2: the vacuum pot cover was tightly screwed, the air inlet was closed, the air outlet was opened, and the vacuum pump was started to draw the air pressure in the pot to the set negative pressure; the set negative pressure in the vacuum pot was 0.06 MPa;

[0088] S2.3: the air inlet sterilization tube was immersed in the functional microorganisms, and the solid-liquid ratio (g / mL) of the carrier and the functional microorganisms (bacterial solution) was 1:40; and the air inlet valve was slowly opened, the functional microorganisms were drawn into the vacuum pot, and the pressure in the pot was maintained at the set negative pressure during the process, so that the functional microorganisms were fully attached to the carrier, and all the valves were closed;

[0089] S2.4: Put the vacuum pot of step S2.3 into the shaking box, keep for a preset shaking time at a preset shaking speed to increase the contact area of the functional microorganism and the carrier; the preset shaking speed is 150 rpm, and the preset shaking time is 40 min;

[0090] S2.5: Take out the carrier from the vacuum pot after shaking in step S2.4, filter with a screen to remove the excess bacterial solution on the surface of the carrier; then dry the carrier at a temperature of 30°C to a water content of 10%, to obtain a carrier loaded with functional microorganisms.

[0091] S3: Wrap the outer protective layer

[0092] S3.1: Prepare the outer protective layer slurry: the outer protective layer is an alkali earth-based geopolymer cementitious material doped with limestone powder, which comprises the following mass fractions of each substance:

[0093] 1 part of 350 m 2 / g of finely ground blast furnace slag powder, 0.2 parts of 300 mesh limestone powder, 1.4 parts of sodium silicate with a modulus of 1.5, and 0.6 parts of tap water.

[0094] Weigh the components of the outer protective layer, first add water to the sodium silicate and stir until uniform, then add the weighed finely ground blast furnace slag powder and limestone powder, continue to stir until uniform to obtain the outer protective layer slurry;

[0095] S3.2: Feeding and wrapping: first uniformly add the carrier loaded with functional microorganisms obtained in step S2 into the granulator, then add the outer protective layer slurry into the granulator in four times with an interval of 30 s, and repeat this process until all the outer protective layer is added into the granulator; the rotation speed of the granulator is 80 rpm / min; the mass ratio of the carrier (solid particles) loaded with functional microorganisms to the outer protective layer slurry is 5:1; the thickness of the outer protective layer is 0.1-0.5 mm.

[0096] S3.3: Curing: after wrapping is completed, place the particles wrapped with the outer protective slurry in an environment with a temperature of 20±1°C and a relative humidity RH greater than 90% for curing for 7 days, and then naturally cure for 14 days;

[0097] S3.4: Drying and granulating: dry at a temperature of 40±2°C to a constant weight until the water content is 2%; then sieve and granulate, to obtain the cement-based material crack self-repairing particles.

[0098] Preparation of mortar test piece, raw materials used: P·O42.5 cement 450g, medium sand with fineness modulus of 2.8 1237.5g, self-repairing particles 112.5g (25%), mixing water 225ml, soluble calcium source selected as calcium lactate, dosage 2.25g (0.5%). Form 40mm×40mm×160mm prism test piece according to cement mortar forming method, standard curing to specified age, test its performance.

[0099] Example 2

[0100] The self-repairing particle of cement-based material according to the present application comprises the following steps:

[0101] S1: Preparation of functional microorganism and carrier

[0102] S1.1: Preparation of functional microorganism

[0103] First, 3g of beef extract, 5g of proteose peptone and 20g of urea are added to 1L of distilled water to obtain 1L of liquid culture medium, then 220μL of Bacillus cohnii freeze-dried powder is selected and activated, and the functional microorganism bacterial solution is obtained by culturing at 30℃ for 24h in the liquid culture medium.

[0104] S1.2: Preparation of carrier: modified zeolite

[0105] 1 part by mass of natural zeolite particles with a particle size of 1.1-2.4mm is added to 30 parts by mass of a solution of sodium chloride with a concentration of 1.0mol / L, the temperature is set to 50℃, and the microwave treatment is performed for 40min; the solid-liquid mixture of zeolite-sodium chloride after microwave treatment is subjected to solid-liquid separation at a centrifugal speed of 5000rpm, and the solid phase is washed with tap water for 4 times; drying is performed at 60℃ until the water content is 1.8%, to obtain the modified zeolite, i.e. the carrier.

[0106] S2: Preparation of carrier loaded with functional microorganism

[0107] S2.1: The carrier is weighed and placed in a vacuum pot, and the volume of the carrier does not exceed two-thirds of the volume of the vacuum pot

[0108] S2.2: The vacuum pot cover is tightly screwed, the air inlet is closed, the air outlet is opened, and the vacuum pump is started to draw the air pressure in the pot to the set negative pressure; the set negative pressure in the vacuum pot is 0.1MPa

[0109] S2.3: The air inlet sterilization tube is immersed in the functional microorganism, and the solid-liquid ratio (g / mL) of the carrier and the functional microorganism (bacterial solution) is 2:40 (i.e. 1:20); and the air inlet valve is slowly opened, the functional microorganism is drawn into the vacuum pot, and the pressure in the pot is maintained at the set negative pressure during the process, so that the functional microorganism is fully attached to the carrier, and all valves are closed

[0110] S2.4: Put the vacuum pot of step S2.3 into the shaking box, keep the preset shaking speed for the preset shaking time, so as to increase the contact area of the functional microorganism and the carrier; the preset shaking speed is 150 rpm, and the preset shaking time is 60 min;

[0111] S2.5: Take out the carrier from the vacuum pot after shaking in step S2.4, filter through a screen, and filter off the excess bacterial liquid on the surface of the carrier; then dry the carrier at a temperature of 50°C until the water content is 5%, to obtain the carrier loaded with the functional microorganism.

[0112] S3: Wrapping an outer protective layer

[0113] S3.1: Preparation of an outer protective layer slurry: the outer protective layer is an alkali earth-based geopolymer cementitious material doped with limestone powder, and includes the following components by mass fraction:

[0114] 1 part of finely ground blast furnace slag powder with a specific surface area of 380 m 2 / kg, 0.5 parts of 600-mesh limestone powder, 0.8 parts of sodium silicate with a modulus of 1.2, and 1.0 parts of tap water.

[0115] Weigh the components of the outer protective layer, first add water to the sodium silicate and stir until uniform, then add the weighed finely ground blast furnace slag powder and limestone powder, and continue to stir until uniform to obtain the outer protective layer slurry;

[0116] S3.2: Feeding and wrapping: first uniformly add the carrier loaded with the functional microorganism obtained in step S2 into the granulator, then add the outer protective layer slurry into the granulator in three times with an interval of 30 s each time, and repeat the process until all the outer protective layer slurry is added into the granulator; the rotation speed of the granulator is 50 rpm / min; the mass ratio of the carrier (solid particles) loaded with the functional microorganism to the outer protective layer slurry is 2:1; and the thickness of the outer protective layer is 0.1-0.5 mm.

[0117] S3.3: Curing: after the wrapping is completed, place the particles wrapped with the outer protective slurry in an environment with a temperature of 20±1°C and a relative humidity RH greater than 90% for curing for 7 days, and then naturally cure for 21 days;

[0118] S3.4: Drying and granulating: dry at a temperature of 40±2°C until the water content is 1.8%; then sieve and granulate, to obtain the cement-based material crack self-repairing particles.

[0119] The mortar test piece is prepared, and the mortar mixing ratio is: P·O42.5 cement 450 g, medium sand with a fineness modulus of 2.8 1125 g, self-repairing particles 225 g (50%), mixing water 225 ml, and the soluble calcium source is calcium chloride, and the dosage is 11.25 g (2.5%). The prism test piece with a size of 40 mm*40 mm*160 mm is formed according to the cement mortar forming method, and the performance is tested after standard curing to the specified age.

[0120] Example 3

[0121] The technical scheme of the embodiment is different from that of example 1.

[0122] When the test piece is formed, a steel bar is added in the test piece, and then the test piece is formed and demolded. After standard curing for 28 days, the crack precasting of the mortar test piece is carried out by using a bending test machine. During the loading process, the test piece is first loaded at a speed of 200 N / s until the test piece is about to appear a crack, and then the loading speed is adjusted to 20 N / s until the crack reaches a target width, and the load is maintained for 5 min, and then the load is unloaded. After the test piece is placed in a dry state for 1 day, the crack precasting is completed.

[0123] The test piece with a crack is respectively placed in a tap water tank and a simulated sewage tank, and the tank opening is sealed by using a PVC film. The environmental temperature is kept at 20±1 ℃, and the crack repair effect is evaluated after the specified age.

[0124] The remaining steps are the same as those in example 1.

[0125] Example 4

[0126] The technical scheme of the embodiment is different from that of example 2.

[0127] When the test piece is formed, a steel bar is added in the test piece, and then the test piece is formed and demolded. After standard curing for 28 days, the crack precasting of the mortar test piece is carried out by using a bending test machine. During the loading process, the test piece is first loaded at a speed of 200 N / s until the test piece is about to appear a crack, and then the loading speed is adjusted to 20 N / s until the crack reaches a target width, and the load is maintained for 5 min, and then the load is unloaded. After the test piece is placed in a dry state for 1 day, the crack precasting is completed.

[0128] The test piece with a crack is respectively placed in a tap water tank and a simulated sewage tank, and the tank opening is sealed by using a PVC film. The environmental temperature is kept at 20±1 ℃, and the crack repair effect is evaluated after the specified age.

[0129] The remaining steps are the same as those in example 2.

[0130] Comparative example 1

[0131] The cement-based material crack self-repairing particle prepared in this comparative example is compared with Example 2, and only the outer protective layer outside the carrier loaded with functional microorganisms is not provided, and the remaining steps are the same as those of Example 2.

[0132] Comparative Example 2

[0133] The cement-based material crack self-repairing particle prepared in this comparative example is compared with Example 3, and only the outer protective layer outside the carrier loaded with functional microorganisms is not provided, and the remaining steps are the same as those of Example 3.

[0134] Comparative Example 3

[0135] Compared with Example 1, the preparation of the carrier in step S1.2 is first microwave treatment, and then salt solution treatment, that is, 1 part by mass of natural zeolite particles with a particle size of 1.1-2.4 mm is first microwave treated for 20 min, and the temperature is set to 80°C; the microwave treated zeolite is added to a solution of 20 parts by mass of sodium chloride with a concentration of 2.0 mol / L for 20 min, and the temperature is set to 80°C, and then the zeolite-sodium chloride solid-liquid mixture is subjected to solid-liquid separation at a centrifugal speed of 5000 rpm, and the solid phase is washed with tap water for 4 times; dried at 55°C to a water content of 2%, to obtain the modified zeolite, that is, the carrier.

[0136] The remaining steps are the same as those of Example 1.

[0137] Comparative Example 4

[0138] The mortar test piece is prepared, and the mortar mixing ratio is: P·O42.5 cement 450 g, medium sand with a fineness modulus of 2.8 1350 g, and mixing water 225 ml. No nutrient agent and self-repairing particle is added. According to the cement mortar molding method, a 40 mm×40 mm×160 mm prism test piece is molded, and the performance is tested after standard curing for 3d and 28d.

[0139] Comparative Example 5

[0140] The mortar test piece is prepared according to Comparative Example 4, and the test piece is made, the crack is pre-prepared, and the curing is carried out in the same manner as in Example 3, and is placed in tap water and sewage for treatment.

[0141] Comparative Example 6

[0142] The difference between this comparative example and Example 1 is that:

[0143] The mass ratio of the outer protective layer slurry of the carrier (solid particles) loaded with functional microorganisms in step S3.2 is 5:1, and all the outer protective layer slurry is added at one time.

[0144] The obtained self-repairing particle has an outer protective layer thickness of less than 0.1 mm. The self-repairing particle has a cylinder compressive strength of only 10.1 MPa, which is lower than that of natural zeolite. Therefore, the mortar test piece is no longer continued.

[0145] Comparative Example 7

[0146] The difference between the present comparative example and Example 1 is that:

[0147] The mass ratio of the carrier (solid particles) of the load functional microorganism to the slurry of the outer protective layer of the self-healing particles in Step S3.2 is 5:3, and the slurry is added in 9 times.

[0148] The obtained self-healing particles have an outer protective layer thickness of 80% higher than 0.5 mm, and a cylinder compressive strength of 20.5 MPa. The specimen forming is performed in the same manner as in Example 3.

[0149] The test results of the performance of the self-healing particles prepared in Examples 1-4 and Comparative Examples 1-7 are as follows:

[0150] (I) Cylinder compressive strength, water absorption rate, and integrity of the self-healing particles and natural zeolite

[0151] Cylinder compressive strength: It is an important indicator for evaluating the strength of porous materials. The determination method refers to "Lightweight Aggregate and Its Test Methods Part 2: Test Methods for Lightweight Aggregate" (GB / T 17431.2-2010) for cylinder compressive strength test. The arithmetic mean of 3 test results is taken as the determination value, and the calculation is accurate to 0.1 MPa.

[0152] Mass water absorption rate: It can represent the ability of the carrier to adsorb bacterial solution and the degree of influence by the external environment to a certain extent. The mass water absorption rate test refers to "Determination of Moisture by Zeolite Drying Method" (GB / T 23956-2009).

[0153] Integrity: The integrity of the self-healing particles is one of the factors that determine whether the particles can heal cracks in the later stage when the particles are added to the mortar. The particles are added to the mortar at a certain amount, and mixed with cement, sand and water in a cement mortar mixer. The mixing process follows the national standard (GB / T 17671). After mixing, the cement mortar is taken out and placed in a container, and the slurry is washed away with running water. The surface of the particles is observed, and the integrity rate is calculated. The integrity rate is calculated by formula (1).

[0154]

[0155] Wherein: I—integrity rate; m—total mass of particles; m0—mass of particles with damaged coating.

[0156] The test results of the cylinder compressive strength, water absorption rate, and integrity of the self-healing particles in Example 1, Example 2, and Comparative Example 3 are shown in Table 1.

[0157] Table 1 Test results of cylinder compressive strength, water absorption rate, and integrity

[0158] Test index Example 1 Example 2 Comparative Example 3 Natural zeolite Cylinder compression strength (MPa) 16.8 16.2 12.4 10.6 Mass water absorption rate (%) 19.28 19.51 19.98 74.55 Integrity (%) 93.4 93.0 74.5 61.1

[0159] The self-repairing particles obtained in Embodiment 1 and Embodiment 2 have a cylinder compressive strength increased by 58.5% and 52.8% respectively, a water absorption rate of 25.6% and 26.2% respectively, and a completeness in mortar increased by 52.9% and 52.2% respectively compared with natural zeolite.

[0160] Comparative Example 3 uses a conventional modification method of zeolite by microwave treatment and then soaking in a salt solution. Since the same outer protective layer as in Embodiment 1 is used, the outer protective layer is dense, the water absorption rate of the self-repairing particles is similar to that of Embodiment 1, but the cylinder compressive strength and completeness are significantly lower than those of Embodiment 1 and Embodiment 2.

[0161] The self-repairing particles obtained in Embodiment 1 and Embodiment 2 can effectively resist mechanical stress, collision and friction between mortar components during the mixing process, and play a high-efficiency protection role on the whole load.

[0162] The cylinder compressive strength of the carriers in Embodiment 1, Embodiment 2 and Comparative Example 3 is compared with that of natural zeolite in Table 2. Compared with natural zeolite, the strength of the carriers obtained by the present application is not significantly reduced, while the strength of the carriers in Comparative Example 3 is significantly reduced.

[0163] Table 2 Comparison of cylinder compressive strength of carriers and natural zeolite

[0164] Test index Example 1 Example 2 Comparative Example 3 Natural zeolite Cylinder compression strength (MPa) 9.5 9.3 7.2 10.6

[0165] (B) Effect of self-repairing particles on mechanical properties of cement mortar

[0166] Embodiment 1, Embodiment 2 and Comparative Example 3 are cement mortar test pieces with self-repairing particles, Comparative Example 1 is self-repairing particles without an outer protective layer, and the carrier in Comparative Example 3 is treated by microwave and then a salt solution. Comparative Example 4 is a cement mortar test piece without self-repairing particles and soluble calcium source. The test results of 3d and 28d flexural strength and compressive strength are shown in Table 3.

[0167] Table 3 Effect of self-repairing particles on mechanical properties of cement mortar

[0168]

[0169] Compared with Comparative Example 4, the self-repairing particles obtained by the application in Example 1 and Example 2 are added to the cement mortar, and the 3d and 28d flexural strength and compressive strength are obviously improved. However, compared with Example 2, the 3d and 28d flexural strength and compressive strength of Comparative Example 1 and Comparative Example 3 are significantly reduced. Compared with Comparative Example 4, the strength of Comparative Example 1 and Comparative Example 3 is also obviously reduced; it can be seen that the setting of the outer protective layer and the modification method of the carrier have a great influence on the performance of the cement mortar test piece.

[0170] (III) Repair effect of self-repairing particles on cracks in cement mortar

[0171] Preparation of cracks: in order to ensure that the crack position and width meet the requirements of the test, a Φ8 steel bar is arranged along the long axis direction of the mortar during the molding of the cement mortar test piece containing the crack self-repairing material prepared by each embodiment of the application. After standard curing for 28d, the test piece is loaded at a speed of 50N / S to determine the flexural strength; after the test piece appears a crack of 0.5±0.3mm, the load is maintained for 1min and then unloaded. The crack preparation schematic diagram is shown in Figure 1 . The pre-prepared crack under the magnifying glass is shown in Figure 2 .

[0172] Preparation of simulated sewage: 1L tap water is added with the following mass of each component substance, stirred and dissolved to prepare a uniform aqueous solution, as shown in Table 4.

[0173] Table 4: Each component in the simulated liquid sewage (mg·L -1 )

[0174]

[0175]

[0176] Crack repair process: the test piece with cracks is respectively placed in the tap water tank and the simulated sewage tank, and the tank opening is sealed with a PVC film. The environmental temperature is maintained at 20±1℃, and the crack repair effect is evaluated after the specified age.

[0177] Evaluation of repair effect:

[0178] ①Observation of crack morphology: after the designed repair age, the test piece is taken out, and the crack morphology is observed under a magnifying glass.

[0179] ②Test of impermeability: the test schematic diagram of the impermeability of the cement mortar test piece after crack repair is shown in Figure 3 . A glass triangular long neck funnel is inverted and placed on the repaired crack surface, the funnel edge is sealed with the test piece surface, and the permeability coefficient is calculated according to formula (2) by measuring the height difference of the water column in the glass tube after 24h:

[0180]

[0181] k - permeability coefficient, unit: cm / s

[0182] a - cross-sectional area of the glass tube, unit: cm 2 ;

[0183] H - height difference between t0 and t1, unit: cm

[0184] A - surface area of the test area of the test piece (i.e. the area covered by the funnel mouth), unit: cm 2 ;

[0185] h0 - height value of the liquid surface at t0, unit: cm

[0186] h1 - height value of the liquid surface at t1, unit: cm

[0187] t0 - initial time, recorded as 0

[0188] t1 - 24 x 3600, unit: s

[0189] After 14 days of repair, the test piece was taken out, the crack repair effect was observed, and the crack repair of Example 3 in the simulated sewage was observed under a magnifying glass, as shown in (b). As can be seen from (b), the crack has been completely closed, and the repair effect is remarkable. Figure 2 Figure 2 Based on the fact that the Bacillus pasteurii can produce high-activity urease, it can efficiently decompose urea. The carbonate generated by decomposition reacts with calcium ions in the sewage solution to form a precipitate, thereby repairing the cracks of the test piece.

[0190] After 28 days of repair, the permeability coefficients of Example 3, Example 4, and Comparative Example 2 were measured, as shown in Table 5. Comparative Example 5 did not add self-repairing particles, so the test piece had no ability to resist water pressure, and the water added to the pipe flowed out within a few seconds, so the permeability coefficient was too large to be calculated. Compared with Example 3, the carrier loaded with functional microorganisms in Comparative Example 2 had no external protective layer, the integrity of the carrier loaded with functional microorganisms was low, and the functional microorganisms were activated too early, resulting in poor crack repair effect. Whether immersed in tap water or sewage, the permeability coefficient was two orders of magnitude higher than that of Example 3 after 28 days of repair. Comparative Example 7 was the same as Comparative Example 5, although self-repairing particles were added, but the protective layer of the self-repairing particles was too thick, and the functional microorganisms were still in the carrier and were not revived, so they did not play a repair role.

[0191] Table 5 Permeability coefficient of cement mortar piece after 28 days of repair -7 (cm / s)

[0192]

[0193] ​(iv) Evaluation of the water purification function of the present application

[0194] The ammonia nitrogen concentration in the sewage was determined by the Nessler reagent spectrophotometry, the total phosphorus concentration was determined by the ammonium molybdate spectrophotometry, and the chemical oxygen demand COD was determined by the dichromate method. The test results are shown in Table 6. After the sewage was soaked in the cement mortar test piece for 7 days, the COD value, ammonia nitrogen concentration and total phosphorus concentration of the sewage soaked in Example 3 and Example 4 were significantly reduced, indicating that the sewage purification effect of the present application was very obvious. Comparative Example 5 had no self-repairing particles, and had almost no sewage purification effect. Compared with Example 3, the carrier loaded with functional microorganisms in Comparative Example 2 had no outer protective layer, and the water purification effect was better than that of Example 3. In Comparative Example 2, the carrier loaded with functional microorganisms had a reduced integrity, but had a high porosity, a high specific surface area and a high ion exchange capacity. Under the action of electrostatic adsorption and ion exchange, the carrier loaded with functional microorganisms could purify the sewage in contact with the cement mortar test piece.

[0195] Table 6 Chemical oxygen demand, ammonia nitrogen concentration and total phosphorus concentration in the simulated sewage after the cement mortar test piece was placed in the simulated sewage for 7 days

[0196] Detection item Simulated sewage before purification Example 3 Example 4 Comparative Example 2 Comparative Example 5 COD (mg / L) 27 16 18 13 26 Ammonia nitrogen concentration (mg / L) 46 23 26 19 46 Total phosphorus concentration (mg / L) 2.95 0.73 0.84 0.65 2.90

[0197] The above-described examples only express the specific embodiments of the present application, and the description is more specific and detailed, but it should not be understood as a limitation on the protection scope of the present application. It should be noted that for ordinary skilled persons in the art, without departing from the technical concept of the present application, a number of modifications and improvements can be made, which are all within the protection scope of the present application.

Claims

1. A self-healing crack particle for cement-based materials, characterized in that, Includes functional microorganisms, carriers, and an outer protective layer; The functional microorganisms are loaded onto a carrier; The outer protective layer is wrapped around the outer surface of the carrier; The carrier is modified zeolite, and the natural zeolite is modified by microwave heating in a salt solution. The outer protective layer is an alkaline earth-based geopolymer cementitious material mixed with limestone powder, and the thickness of the outer protective layer is 0.1-0.5 mm; The modified zeolite is prepared using the following specific method: Add 1-5 parts of natural zeolite particles with a particle size of 1.1-2.4 mm to 20-30 parts of sodium chloride solution with a concentration of 1.0-2.5 mol / L, set the temperature to 50-80℃, and microwave for 20-40 min. The microwave-treated zeolite-sodium chloride solid-liquid mixture was centrifuged at 4000-5000 rpm for solid-liquid separation. The solid phase was washed at least four times with water that meets the requirements for mixing water in cement-based materials. The mixture was then dried at 50-60°C until the moisture content did not exceed 2%, thus obtaining the modified zeolite.

2. The self-healing crack particle of cement-based material according to claim 1, characterized in that, The compressive strength of the carrier is not less than 85% of that before modification.

3. The self-healing crack particle of cement-based material according to claim 1, characterized in that, The outer protective layer comprises a component with a specific surface area of ​​not less than 350m². 2 / kg of finely ground blast furnace slag powder, 0.2~0.5 parts of 300-600 mesh limestone powder, 0.8~1.4 parts of sodium silicate with a modulus of 1.2~1.5 and 0.6~1.0 parts of water that meets the mixing requirements of cement-based materials.

4. The self-healing crack particle of cement-based material according to claim 1, characterized in that, The functional microorganisms are first-generation bacterial cultures of lyophilized microbial powder cultured in liquid culture medium at a suitable temperature until the exponential growth phase.

5. The self-healing crack particle of cement-based material according to claim 4, characterized in that, The microbial freeze-dried powder is any one or a mixture of two of Bacillus coli and Bacillus pasteurellii.

6. A method for preparing self-healing crack particles in cement-based materials according to any one of claims 1-5, characterized in that, Specifically, the steps include the following: S1: Preparation of functional microorganisms and carriers; S1.1: Preparation of functional microorganisms: Cultivate the lyophilized microbial powder to the exponential growth phase; S1.2: Preparation carrier: Modified zeolite: Natural zeolite was modified by microwave heating in a salt solution; S2: Carrier loaded with functional microorganisms: Functional microorganisms were loaded into the modified zeolite prepared in step S1.2 using a vacuum impregnation method to obtain a carrier loaded with functional microorganisms; S3: Wrap the outer protective layer; prepare the outer protective layer slurry, and put the carrier loaded with functional microorganisms prepared in step S2 into the outer protective layer slurry for wrapping. The mass ratio of the carrier loaded with functional microorganisms to the outer protective layer slurry is 5:1~2:1; then cure, dry and granulate to obtain cement-based material crack self-healing particles.

7. The method for preparing self-healing particles for cracks in cement-based materials according to claim 6, characterized in that, Step S2 specifically includes the following sub-steps: S2.1: Weigh the carrier processed in step S1.2 and place it into the vacuum pot. The volume of the carrier shall not exceed the maximum volume of solid material that the vacuum pot is designed to hold. S2.2: Set the negative pressure inside the vacuum cooker to 0.06MPa~0.1MPa; S2.3: Add functional microbial culture to the vacuum pot at a solid-liquid ratio of 1~2g:40mL, and maintain the pressure inside the vacuum pot at the set negative pressure to ensure that the functional microorganisms are fully attached to the carrier. Close all valves. S2.4: Place the vacuum pot from step S2.3 into a shaking box and shake at 150 rpm for 40-60 minutes to increase the contact area between the functional microorganisms and the carrier; S2.5: Remove the carrier from the vacuum pot after shaking in step S2.4, filter it with a sieve to remove excess bacterial liquid from the surface of the carrier; then dry the carrier at a temperature of 30~50℃ until the moisture content does not exceed 10% to obtain a carrier loaded with functional microorganisms.

8. The method for preparing self-healing crack particles in cement-based materials according to claim 6, characterized in that, Step S3 specifically includes the following sub-steps: S3.1: Preparation of the outer protective layer slurry: Weigh each component of the outer protective layer. First, add water to sodium silicate and stir evenly. Then, add the weighed finely ground blast furnace slag powder and limestone powder and continue stirring until uniform to obtain the outer protective layer slurry. S3.2: Feeding and Coating: First, uniformly add the carrier loaded with functional microorganisms obtained in step S2 into the granulator. Then, add the outer protective layer slurry into the granulator at least three times for coating, with an interval of 30 seconds between each addition. Repeat this process until all the outer protective layer slurry is added into the granulator. The rotation speed of the granulator is 50~80 rpm / min. S3.3: Curing: After the coating is completed, the particles coated with the outer protective layer of slurry are placed in an environment with a temperature of 20±1℃ and a relative humidity of more than 90% for 7 days, followed by natural curing for 14~21 days; S3.4: Drying and granulation: Dry the particles to constant weight at 40±2℃, requiring the moisture content to be no higher than 2%; then sieve and granulate to obtain cement-based material crack self-healing particles.

9. The method of using a self-healing cement-based material crack-repairing particle according to any one of claims 1-5, characterized in that, Specifically, the steps include the following: Step S1: The self-healing particles are incorporated into the cement-based material at a dosage of 25-50% of the mass of the cementitious material, while the mass of the fine aggregate in the cement-based material is reduced by 1-2% accordingly. Step S2: Nutrients are also incorporated into cement-based materials, with the amount of nutrient added being 0.5~2.5%wt of the mass of the cementitious materials in the cement-based materials; The nutrient is a soluble calcium source.

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