A microbial repair agent particle for self-repairing cement-based materials and a preparation method thereof

Abstract

The present invention discloses a microbial repair agent particle for a crack self-repairing cement-based material and a preparation method thereof. The repair agent particle has a core-shell structure and comprises a microbial repair agent core and a repair agent shell. The repair agent core comprises the following components by mass percentage: microbial powder: 10-15 parts, calcium source: 0.75-1.25 parts, nutrient: 2-3 parts, filler: 8-10 parts; the repair agent shell comprises the following components by mass percentage: sulfoaluminate cement: 6-8 parts, density adjustment powder: 1-3 parts, fly ash: 0-1 part. The present invention changes the formula of the repair agent core and adopts an extrusion granulation method to prepare the core particles, achieving a high loading rate of the microbial component in the core and a small particle size distribution coefficient of the core. At the same time, the repair agent particle has good sphericity, concentrated size distribution, small deviation of particle strength, uniform wall thickness, high yield rate, good responsiveness to cracking and good self-repairing effect on cracks in cement-based materials such as mortar and concrete.

Description

Technical Field

[0001] This invention relates to a self-healing agent for cracks in cement-based materials such as mortar and concrete, and its preparation method, and more particularly to a microbial repair agent particle and its preparation method. Background Technology

[0002] During its service life, concrete inevitably develops cracks due to internal stress or external environmental factors, negatively impacting its mechanical properties and durability, causing serious economic losses and even safety accidents. Compared to traditional crack repair methods, microbial self-healing offers advantages such as timeliness and spontaneity, and its green and gentle repair process, along with its excellent repair results, has garnered widespread attention in the industry.

[0003] Microbial self-healing concrete is based on microbial-induced calcium carbonate precipitation technology. Microorganisms induce the mineralization and deposition of calcium carbonate to fill cracks that appear during construction or use. To address the negative impact of the strong alkalinity inside the concrete on microbial activity, solidification techniques are typically used to protect the microorganisms, such as core-shell structures. Patent CN201911408297.4 discloses a microbial repair agent particle with a low-alkali cementitious material as the shell and its preparation method. This patent uses coral reef calcareous sand as a carrier, loading microorganisms and nutrients to form a core, and uses a low-alkali cementitious material as the shell to prepare the repair agent particles. In the process of preparing the core, this patent uses coral reef calcareous sand as a carrier, reducing the loading of microbial components in the repair agent particles, thus limiting the repair effect of the particles on cracks. Summary of the Invention

[0004] The primary objective of this invention is to provide a microbial remediation agent particle with a core-shell structure and a high loading rate for self-healing cement-based materials;

[0005] The second objective of this invention is to provide a method for preparing microbial remediation agent particles for self-healing cement-based materials with high yield, low dimensional deviation, and high density.

[0006] Technical Solution: The microbial repair agent particles for self-healing cement-based materials of the present invention comprise a microbial repair agent core and a repair agent shell. The microbial repair agent core comprises the following components by mass percentage: microbial powder: 10-15 parts, calcium source: 0.75-1.25 parts, nutrients: 2-3 parts, and filler: 8-10 parts. The repair agent shell comprises the following components by mass percentage: sulfoaluminate cement: 6-8 parts, density adjusting powder: 1-3 parts, and fly ash: 0-1 parts.

[0007] Compared to patents CN201911408297.4 and CN201910500880.1, this invention employs an extrusion granulation method to prepare microbial remediation agent core particles. The core particles obtained by this method have a high apparent density and a high loading of microbial components per unit volume. To ensure the uniformity of particle size distribution, this invention also introduces shot blasting technology to regularize the microbial remediation agent core particles. Furthermore, this invention innovatively improves upon commonly available extrusion granulators by adding specially designed cutting blades at intervals along the circumference of the screen. During extrusion granulation, these blades remain stationary while cutting the raw material. This design simplifies the preparation process, thereby increasing the yield of remediation agent core particles and ensuring the stability of particle size and density during mass production.

[0008] Among them, the calcium source is a calcium-containing compound that will not have a negative impact on the durability of concrete. The calcium source can be one or more of calcium formate, calcium acetate, and calcium lactate. The nutrient is a powder that can provide nutrients for bacterial growth. The nutrient can be one or more of yeast extract, yeast peptone, and glucose.

[0009] The filler is one or more of microcrystalline cellulose, starch, sodium carboxymethyl starch, and mannitol. The density-adjusting powder is one or more of iron powder, alumina, silicon carbide, and barite.

[0010] The above-mentioned method for preparing microbial remediation agent particles for self-healing cement-based materials includes the following steps:

[0011] (A1) Mix microbial powder, calcium source, nutrients and filler, add water and stir to form wet material;

[0012] (A2) The wet material is placed in an extrusion granulator for extrusion granulation to obtain small-segment repair agent core particles;

[0013] (A3) Place the loose material of the repair agent core particles in a shot blasting machine to obtain the repair agent core particles, and then air dry them;

[0014] (A4) The dried repair agent core particles are sieved, and the sieved repair agent core particles are poured into a granulator for powder coating and granulation. After sieving and curing, microbial repair agent particles are obtained.

[0015] The powder used for coating and granulation is a mixture of sulfoaluminate cement, density-regulating powder, and fly ash.

[0016] In step (A1), the addition of water and stirring includes the following steps:

[0017] (B1) Stir the powder for 5-10 minutes;

[0018] (B2) Spray water mist into the mixer, the amount of which is 20-25% of the powder mass;

[0019] (B3) Continue stirring for 1-3 minutes after the water mist spraying is finished;

[0020] (B4) Add water to the mixer, the amount of water being 15-20% of the powder mass;

[0021] (B5) Stir the wet material for 2 to 5 minutes.

[0022] In step (A2), the length of the small segments is 1mm to 4mm; the extrusion granulator uses a screen with an aperture of 0.5mm to 2mm and a rotation speed of 60r / min to 120r / min. The method for obtaining the small segments of the repair agent core granules is as follows: cutting blades are spaced along the circumference of the screen on the outer ring of the extrusion granulator; the screen rotates with the extrusion granulator while the blades remain stationary, cutting the extruded repair agent core granules into small segments. The number of blades is 6 to 12.

[0023] In step (A3), the shot blasting speed is 500 r / min to 600 r / min, and the shot blasting time is 40 s to 120 s. The shot blasting speed and shot blasting time are adjusted according to the appearance morphology of the core particles of the obtained repair agent.

[0024] In step (A3), the drying time of the core particles of the repair agent is 18h to 30h.

[0025] In step (A4), the granulator is an aggregate granulator.

[0026] In step (A4), mixed cement powder and water mist are sprayed into the aggregate granulator in batches for powder coating and granulation; the mixed cement powder includes sulfoaluminate cement, density adjusting powder and fly ash, and the mass ratio of sulfoaluminate cement, density adjusting powder and fly ash is (6-8):(1-3):(0-1); the mass ratio of mixed cement powder and water mist is (3-5):1.

[0027] In step (A4), the particle size range of the core particles of the repair agent after sieving is 0.5mm to 2.5mm. The reason for controlling the particle size of the core particles is to ensure that the content of microbial powder inside the repair agent is sufficient so that the repair effect of the repair agent meets the relevant indicators. The particle size range of the repair agent particles after sieving is 1.0mm to 4.75mm. The reason is that the single particle strength of the repair agent particles meets the requirements, and the internal stress that occurs when cracks appear in the concrete structure can break the repair agent particles and release the effective components inside.

[0028] In step (A4), the curing process is as follows: The repair agent granules are placed in a constant temperature and ventilation environment of 20℃~30℃ and left to stand for 7 days to 10 days. Before day 2, water mist is sprayed onto the surface of the repair agent every 4 to 6 hours to keep it moist. After day 2, water mist is sprayed onto the surface of the repair agent every 8 to 12 hours until the repair agent granules are completely soaked. The purpose of this curing is to increase the hardness of the cement shell and reduce the premature cracking of the repair agent granules during concrete mixing, which would lead to a decrease in microbial activity.

[0029] The core of the repair agent particles of this invention is prepared by extrusion granulation. The core particle size ranges from 0.5 mm to 2.5 mm, and the overall particle size ranges from 1.0 mm to 4.75 mm. The single particle strength of this repair agent particle ranges from 70 N to 80 N, and it is suitable for concrete with strengths of C40 to C70 and mortar with strengths of M10 to M50.

[0030] Beneficial effects: Compared with the prior art, the present invention achieves the following significant effects:

[0031] (1) The present invention prepares the core particles of the repair agent by extrusion granulation; the method improves the apparent density of the core particles of the repair agent, thereby increasing the loading of microbial components in the core particles of the repair agent per unit volume, and the repair efficacy of the repair agent particles is significantly enhanced.

[0032] (2) The present invention adds shot blasting treatment to regulate the sphericity of the core particles of the repair agent, improve the uniformity of the particle size distribution of the core particles, obtain core particles with small size deviation and high yield, thereby improving the stability of the shell thickness, particle size and strength of the final core-shell structure repair agent particles; optimizes the responsiveness of the repair agent when mortar or concrete cracks, and can release effective components such as microorganisms in a timely manner;

[0033] (3) Based on the commercially available extrusion granulator, the present invention adds blades around the screen, which can cut the raw material while it is being extruded and granulated, thus simplifying the operation steps. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the preparation process of the microbial remediation agent particles of the present invention;

[0035] Figure 2 Comparative photographs of the core and overall structure of the repair agent particles obtained in Example 1;

[0036] Figure 3 The particle size distribution coefficient is the core particle size distribution coefficient of the repair agent in each embodiment and comparative example;

[0037] Figure 4The yield of the repair agent core particles in each embodiment and comparative example;

[0038] Figure 5 The volumetric loading of the repair agent core particles in each embodiment and comparative example;

[0039] Figure 6 The individual particle strength and standard deviation of the repair agent particles in each embodiment and comparative example;

[0040] Figure 7 The changes in ultrasonic propagation velocity across cracks in microbial self-healing concrete specimens of Example 1 and Comparative Example 1 over time. Detailed Implementation

[0041] The present invention will now be described in further detail.

[0042] Example 1

[0043] like Figure 1 As shown, the process of preparing repair agent core particles using raw materials is as follows:

[0044] (a1) Mix carbonic anhydrase microbial spore powder, yeast powder, calcium lactate, yeast extract and microcrystalline cellulose in a ratio of 20:20:3:8:40, add to a material mixer and stir for 5 minutes to mix the materials;

[0045] (a2) Add water to the mixer. The ratio of water to material is 4:11. Add water to the mixer in batches. Spray the first 50% of the water evenly onto the material using a spray bottle. After mixing for 2 minutes, pour the remaining water into the mixer and continue mixing for 5 minutes to obtain wet material.

[0046] (a3) The wet material is poured into an extrusion granulator for granulation. The speed of the extrusion granulator is 100 r / min, the screen aperture is set to 1.5 mm, and there are 8 blades on the side to prepare small segments of repair agent core granules with a length of 2 mm to 3 mm. Under the action of the baffle, the granulated particles flow out from the discharge port for easy collection. The process of preparing small segments of repair agent core granules is as follows: Based on a commercially available extrusion granulator, blades for cutting are set at intervals along the circumference of the screen on the outer ring of the screen. The screen rotates with the extrusion granulator while the blades remain stationary. The rotor of the extrusion granulator is equipped with a base plate. A baffle is set around the outer ring of the screen to collect the granulated particles. The baffle is equipped with a discharge port. When the machine is started, the blades are fixed, and the screen and the base plate rotate together with the rotor. The blades move relative to the screen to cut the repair agent core granules extruded from the screen, shortening the length of the granules. Under the action of the baffle, the small segments of repair agent core granules flow out from the discharge port.

[0047] (a4) The loose core particles are shot blasted. The shot blasting amount is 1kg, the shot blasting machine speed is 500r / min, and the shot blasting time is 60s. After shot blasting, the repair agent core particles are obtained.

[0048] (a5) Dry the repair agent core particles in a cool place for 24 hours. Sift the dried repair agent core particles; particles with a diameter of 1.6mm to 1.43mm are considered finished repair agent core particles. The ratio of finished repair agent core particles to raw material mass is called the yield. (The text abruptly ends here, so the translation also ends here.) Figure 2 As shown in (a), particles that do not meet the particle size specifications are considered waste and used for subsequent repeated granulation.

[0049] Waste materials obtained during the preparation of core particles are recycled for secondary preparation of repair agent core particles. The preparation process is as follows:

[0050] (b1) Process the waste obtained in step (a5) to obtain waste fluff material;

[0051] (b2) Place the fluffed waste material in a mixer and mix it. During the mixing process, add water to the mixer. The ratio of water to material is 1:7. After all the water has been added to the mixer, continue mixing for 5 minutes to obtain wet material.

[0052] (b3) Pour the wet material into an extrusion granulator for granulation. The speed of the extrusion granulator is 100 r / min, the screen aperture is set to 1.5 mm, and there are 8 blades on the side to prepare small segments of repair agent core particles with a length of 2 mm to 3 mm.

[0053] (b4) The loose core particles are shot blasted. The shot blasting amount is 1kg, the shot blasting machine speed is 500r / min, and the shot blasting time is 60s. After shot blasting, the repair agent core particles are obtained.

[0054] (b5) Place the core particles of the repair agent in a cool place to dry for 24 hours, and sieve the dried core particles of the repair agent. Particles with a particle size of 1.6 mm to 1.43 mm are the finished product of the core particles of the repair agent.

[0055] The repair agent particles are prepared using the repair agent core particles. The preparation process is as follows:

[0056] (c1) Repair agent particles are prepared using an agglomeration granulator. The rotor speed of the agglomeration granulator is set to 50 r / min and the turntable speed is set to 20 r / min. The repair agent core particles prepared above are placed in a mixing pot and stirred.

[0057] (c2) Sulfoaluminate cement, iron powder and fly ash are mixed in a mass ratio of 7:2:1 to form a mixed powder. The mixed powder and water mist are sprayed into the aggregated granulator in batches for powder coating and granulation. The ratio of mixed powder to water mist is 4:1.

[0058] (c3) After granulation, the repair agent particles are screened, and particles with a particle size of 2.8mm to 3.2mm are the finished repair agent particles;

[0059] (c4) The repair agent granules were cured in a constant temperature and ventilation environment at 20℃ for 7 days. For the first 48 hours, water mist was sprayed onto the granule surface every 6 hours. After 48 hours, water mist was sprayed onto the carrier surface every 12 hours to keep the granule surface moist. The resulting repair agent granules were then obtained. The repair agent granules are shown below. Figure 2 As shown in (b).

[0060] The performance of the repair agent's core particles was evaluated.

[0061] Particle size distribution coefficient, yield, and unit volume loading are used as evaluation indicators for the performance of the core particles of the repair agent. The particle size distribution coefficient is a parameter used to describe the proportion of particles of different sizes in the total mass of the particles, reflecting the distribution of particles of different sizes. A smaller particle size distribution coefficient indicates that the particle size distribution is concentrated. The particle size distribution coefficient is calculated as shown in equation (1):

[0062] S pan =(d 90 -d 10 ) / d 50 (1)

[0063] In the formula:

[0064] S pan Particle size distribution coefficient;

[0065] d 90 : Particle size at 90% volume percentage, meaning that particles smaller than this size account for 90% of the total volume of all particles, mm;

[0066] d 50 Particle size at 50% volume fraction, in mm;

[0067] d 10 : Particle size at 10% volume percentage, in mm.

[0068] The yield rate represents the ratio between the mass of the finished particles and the mass of the raw materials during the particle preparation process. The yield rate is calculated as shown in equation (2).

[0069]

[0070] In the formula:

[0071] P: Yield, %;

[0072] m p : Mass of the finished repair agent core particles, kg;

[0073] m0: Mass of raw material, kg.

[0074] The unit volume load refers to the mass of microbial powder contained in a unit volume of core particles. The calculation of the unit volume load is shown in equation (3).

[0075]

[0076] In the formula:

[0077] L: Load capacity per unit volume, g / cm³ 3 ;

[0078] m m : The mass of microbial inoculum powder, in grams;

[0079] ρ p Apparent density of the repair agent core particles, g / cm³ 3 ;

[0080] m p Mass of the repair agent core particles, in grams.

[0081] Figure 2 Image (a) in the image is a photograph of the core of the repair agent particles obtained in Example 1. Figure 2 Image (b) is a photograph of the overall structure of the repair agent particles obtained in Example 1. Figure 2 It can be seen that the core of the repair agent particles and the particle size distribution of the repair agent particles are concentrated, and the particles have good uniformity.

[0082] Fifty repair agent particles were randomly selected, and the strength of each individual particle was tested. The mean and standard deviation of the individual particle strength were calculated. Figure 3 As shown.

[0083] Example 2

[0084] Based on Example 1, the difference from Example 1 is that step (a1) is adjusted to mix carbonic anhydrase microbial spore powder, yeast powder, calcium lactate, yeast extract and starch in a ratio of 20:20:3:8:32, and the ratio of water to materials in step (a2) is adjusted to 1:3; step (c2) is adjusted to mix sulfoaluminate cement, alumina and fly ash in a ratio of 7:3:1.

[0085] Example 3

[0086] Based on Example 1, the difference from Example 1 is that step (a1) is adjusted to mix carbonic anhydrase microbial spore powder, yeast powder, calcium lactate, yeast extract, microcrystalline cellulose, and mannitol in a ratio of 20:20:5:12:20:12, and the ratio of water to materials in step (a2) is adjusted to 4:11; step (c2) is adjusted to mix sulfoaluminate cement, iron powder, silicon carbide, and fly ash in a ratio of 8:1:1:1.

[0087] Example 4

[0088] Based on Example 1, the difference from Example 1 is that the number of side blades of the extrusion granulator in step (a3) ​​is adjusted to 12.

[0089] Example 5

[0090] Based on Example 1, the difference is that the speed of the shot blasting machine in step (a4) is adjusted to 600 r / min.

[0091] Comparative Example 1

[0092] Based on Example 1, the process for preparing the repair agent core particles is adjusted as follows:

[0093] (a1) Mix carbonic anhydrase microbial spore powder, yeast powder, calcium lactate and yeast extract in a ratio of 20:20:3:8, add to a material mixer and stir for 5 minutes to mix the materials.

[0094] (a2) Using sucrose as the nucleation site, sucrose granules are spread out, water mist is sprayed on the surface of the granules and then poured into an aggregate granulator. The material and water mist are sprayed into the aggregate granulator in batches for coating and granulation. The ratio of material to water mist is 3:1.

[0095] (a3) The core particles of the repair agent are screened, and particles with a diameter of 1.43 mm to 1.6 mm are selected as the finished product of the core particles of the repair agent.

[0096] Comparative Example 2

[0097] Based on Example 1, the difference from Example 1 is that microcrystalline cellulose is not added in step (a1).

[0098] Comparative Example 3

[0099] Based on Example 1, the difference from Example 1 is that the ratio of carbonic anhydrase microbial spore powder, yeast powder, calcium lactate, yeast extract and microcrystalline cellulose in step (a1) is adjusted to 20:20:3:8:60.

[0100] Comparative Example 4

[0101] Based on Example 1, the difference is that the ratio of water to material in step (a2) is adjusted to 1:2.

[0102] Comparative Example 5

[0103] Based on Example 1, the difference is that the ratio of water to material in step (a2) is adjusted to 1:4.

[0104] Performance data of the repair agent core particles in each embodiment and comparative example are as follows: Figure 3 , 4 As shown in Figures 5 and 6. From Figure 3 It can be seen that the particle size distribution coefficient S of the core particles of the repair agent prepared in the examples is... pan The particle size distribution of the core particles prepared in the example is smaller than that of the core particles prepared in the comparative example, indicating that the particle size distribution of the core particles prepared in this example is more concentrated. Figure 4 It can be seen that the yield of the repair agent core particles prepared in the examples is significantly higher than that of the core particles prepared in the comparative example; from Figure 5 It can be seen that the core particles of the repair agent prepared in the examples have a loading capacity of 0.8 g / cm³ for microbial powder per unit volume. 3 Its loading rate of microbial components is higher than that of the core particles prepared in the comparative example; from Figure 6 It can be seen that the single-particle strength of the repair agent particles prepared in the examples meets the standard of 70N to 80N, which is higher than that of the repair agent particles prepared in the comparative example. Furthermore, the standard deviation of the single-particle strength of the repair agent particles prepared in the examples is lower than that of the repair agent particles prepared in the comparative example. This indicates that the single-particle strength of the repair agent particles prepared in the examples is more concentrated in the core compared to the repair agent particles prepared in the comparative example.

[0105] To verify the repair effect of the repair agent particles on cracks, the repair agent core particles obtained in Example 4 and Comparative Example 6 were subjected to the following experiments:

[0106] (1) Weigh 347g / L of P·O 42.5 ordinary Portland cement, 23g / L of repair agent, 764g / L of river sand, 1187g / L of basalt gravel, and 170g / L of water, mix them into concrete specimens, and design concrete specimens without the addition of repair agent as a control group. After curing the specimens under standard conditions for 3 days, create cracks with a width between 400μm and 450μm.

[0107] (2) The cracked concrete specimens were placed in water for curing at 20℃. The ultrasonic wave propagation velocity across the cracks was measured at curing times of 7, 14, 21, and 28 days. The change in ultrasonic wave propagation velocity with repair time is shown below. Figure 7As shown, it can be seen that, under the same dosage, the repair agent particles prepared by extrusion granulation have a better repair effect on concrete cracks than those prepared by ball milling.

Claims

1. A microbial remediation agent granule for self-healing cement-based materials, characterized in that, It comprises a microbial repair agent core and a repair agent shell. The microbial repair agent core includes the following components by mass ratio: microbial powder: 10-15 parts, calcium source: 0.75-1.25 parts, nutrients: 2-3 parts, and filler: 8-10 parts. The outer shell of the repair agent comprises the following components by mass ratio: sulfoaluminate cement: 6-8 parts, density adjusting powder: 1-3 parts, fly ash: 0-1 parts; The filler is one or more of microcrystalline cellulose, starch, sodium carboxymethyl starch, and mannitol; the density adjusting powder is one or more of iron powder, alumina, silicon carbide, and barite. The method for preparing the microbial remediation agent particles for self-healing cement-based materials includes the following steps: (A1) Mix microbial powder, calcium source, nutrients and filler, add water and stir to form wet material; (A2) The wet material is placed in an extrusion granulator for extrusion granulation to obtain small-segment repair agent core particles loose material; (A3) Place the loose material of the small repair agent core particles in a shot blasting machine to obtain repair agent core particles, and then air dry them; (A4) The dried repair agent core particles are sieved, and the sieved repair agent core particles are poured into a granulator for powder coating and granulation. After sieving and curing, core-shell structured microbial repair agent particles for self-healing cement-based materials are obtained. The powder used for coating and granulation is a mixture of sulfoaluminate cement, density adjusting powder, and fly ash.

2. A method for preparing microbial remediation agent particles for self-healing cement-based materials as described in claim 1, characterized in that, Includes the following steps: (A1) Mix microbial powder, calcium source, nutrients and filler, add water and stir to form wet material; (A2) The wet material is placed in an extrusion granulator for extrusion granulation to obtain small-segment repair agent core particles loose material; (A3) Place the loose material of the small repair agent core particles in a shot blasting machine to obtain repair agent core particles, and then air dry them; (A4) The dried repair agent core particles are sieved, and the sieved repair agent core particles are poured into a granulator for powder coating and granulation. After sieving and curing, core-shell structured microbial repair agent particles for self-healing cement-based materials are obtained. The powder used for coating and granulation is a mixture of sulfoaluminate cement, density adjusting powder, and fly ash.

3. The method for preparing microbial remediation agent particles for self-healing cement-based materials according to claim 2, characterized in that, In step (A1), the mass of the water is 8 to 11 parts.

4. The method for preparing microbial remediation agent particles for self-healing cement-based materials according to claim 2, characterized in that, In step (A2), the length of the loose material of the core particles of the small repair agent is 1 mm to 4 mm; the extrusion granulator uses a screen with a pore size of 0.5 mm to 2 mm and a rotation speed of 60 r / min to 120 r / min.

5. The method for preparing microbial remediation agent particles for self-healing cement-based materials according to claim 2, characterized in that, In step (A2), the method for obtaining small-segment repair agent core particle loose material is as follows: cutter blades are set at intervals along the circumference of the screen on the outer ring of the extrusion granulator. The screen rotates with the extrusion granulator while the blades remain stationary, and the repair agent core particle loose material obtained after extrusion is cut into small-segment repair agent core particle loose material.

6. The method for preparing microbial remediation agent particles for self-healing cement-based materials according to claim 5, characterized in that, The number of blades is 6 to 12.

7. The method for preparing microbial remediation agent particles for self-healing cement-based materials according to claim 2, characterized in that, In step (A3), the shot blasting speed is 500 r / min ~ 600 r / min, and the shot blasting time is 40 s ~ 120 s; the air drying time of the core particles of the repair agent is 18 h ~ 30 h.

8. The method for preparing microbial remediation agent particles for self-healing cement-based materials according to claim 2, characterized in that, In step (A4), the particle size range of the core particles of the repair agent after sieving is 0.5 mm ~ 2.5 mm; the particle size range of the repair agent particles after sieving is 1.0 mm ~ 4.75 mm.

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