Preparation method of self-healing negative-carbon cement-based grouting material based on gradient structure

Abstract

The present invention discloses a preparation method of a self-healing negative-carbon cement-based grouting material based on a gradient structure, comprising the steps of: (1) adding carbide slag to water, fully soaking it, separating the soaking solution, and then introducing excessive carbon dioxide into it to convert calcium hydroxide into calcium bicarbonate, and obtaining a mixing solution after completion. (2) Mixing the mixing solution, a silicate cement-based grouting material, and a microbial-sodium alginate repair material to obtain a composite grouting material. (3) After degassing the composite grouting material, performing ultrasonic treatment to enable a part of the microbial-sodium alginate repair material to diffuse to the outer layer of the cement-based grouting material, and another part to be embedded in the cement-based grouting material, thereby forming the characteristic that the concentration of the microbial-sodium alginate repair material in the cement-based grouting material gradually increases from the inside to the outside in a gradient distribution, that is, obtaining the self-healing negative-carbon cement-based grouting material. This grouting material can not only repair shrinkage cracks but also fill the void area of the grouting material.

Description

Technical Field

[0001] The present invention relates to the technical field of grouting materials, and particularly relates to a preparation method of a self-healing negative-carbon cement-based grouting material based on a gradient structure. Background Technique

[0002] Disclosing the information of this background technique section is only intended to increase the understanding of the overall background of the present invention, and it is not necessarily regarded as an admission or an implication in any form that this information constitutes the prior art already known to those of ordinary skill in the art.

[0003] With the acceleration of underground engineering construction, the construction and maintenance requirements of underground infrastructure have increased significantly. The application of grouting materials in civil engineering for repairing and strengthening structures has become increasingly important, and they are widely used in many fields such as construction, mining, and water conservancy. Grouting materials are mainly divided into cement-based grouting materials, polymer-based grouting materials, resin-based grouting materials, etc. Since cement-based grouting materials are mainly composed of cement, sand, and water, they have the advantages of convenient raw material acquisition, excellent durability, simple process, high cost performance, etc., and are suitable for projects with higher bearing requirements. Currently, they are widely used in reinforcement projects. However, cement-based grouting materials inevitably have shrinkage deformation during the hardening process, resulting in shrinkage cracks. At the same time, shrinkage will also cause voids between the grouting material matrix and the repaired structure body, and these factors greatly limit the grouting reinforcement effect of cement-based grouting materials.

[0004] In response to the above problems, engineers generally adopt the method of secondary grouting with organic grouting materials such as polyurethane or organic latex powder to control the voids between the grouting material and the repaired structure body. However, this method not only has a complex construction process, increasing the project cost, but also the durability of organic grouting materials is poor, and their application is limited. Summary of the Invention

[0005] In response to the above problems, the present invention provides a preparation method of a self-healing negative-carbon cement-based grouting material based on a gradient structure. This grouting material can not only repair shrinkage cracks but also fill the void area of the grouting material, improving the reinforcement effect. Specifically, the technical solution of the present invention is as follows.

[0006] A preparation method of a self-healing negative-carbon cement-based grouting material based on a gradient structure, comprising the following steps:

[0007] (1) Add carbide slag to water, fully soak it, and then separate the soaking solution. Then, pass excessive carbon dioxide into it to convert calcium hydroxide into calcium bicarbonate, and after completion, obtain a mixing solution.

[0008] (2) Mix the mixing solution, a silicate cement-based grouting material, and a microorganism-sodium alginate repair material to obtain a composite grouting material.

[0009] (3) After degassing the composite grouting material, ultrasonic treatment is carried out to allow a part of the microbial-sodium alginate repair material to diffuse to the outer layer of the cement-based grouting material, while another part is embedded in the cement-based grouting material, so as to form the characteristic that the concentration of the microbial-sodium alginate repair material in the cement-based grouting material gradually increases from the inside to the outside in a gradient distribution, thus obtaining the self-repairing negative-carbon cement-based grouting material.

[0010] Further, in step (1), the mass ratio of the carbide slag to water is 1:8 - 20.

[0011] Further, in step (1), the soaking time is 1 - 2 hours.

[0012] Further, in step (1), the rate of carbon dioxide injection is 10 - 15 L / min. After injecting carbon dioxide, the soaking solution first becomes turbid, and then becomes clear again as carbon dioxide continues to be injected, thus obtaining the mixing solution.

[0013] Further, in step (2), the mass ratio of the mixing solution, the portland cement-based grouting material, and the microbial-sodium alginate repair material is 0.2 - 0.5:1.0:0.005 - 0.02.

[0014] Further, in step (2), the portland cement-based grouting material includes portland cement, silica fume, and organic latex powder. Optionally, the ratio of the portland cement, silica fume, and organic latex powder is 60 - 70 parts by weight:7 - 12 parts by weight:2 - 3 parts by weight.

[0015] Further, in step (2), the microbial-sodium alginate repair material is prepared by the following method: adding the microbial solution of Bacillus pasteurii to water and mixing evenly, then adding sodium alginate, urea, and calcium acetate, and mixing evenly to obtain the repair material.

[0016] Further, the ratio of the microbial solution of Bacillus pasteurii, water, sodium alginate, urea, and calcium acetate is 10 - 17 mL:100 - 110 ml:0.7 - 1.5 g:4 - 8 g:12 - 20 g. Optionally, the number of viable bacteria in the microbial solution of Bacillus pasteurii is 1×10 12 ~1×10 14 CFU.

[0017] Further, in step (3), the degassing treatment method is vibration degassing. Optionally, the vibration frequency is 3 - 5 Hz, and the vibration time is 10 - 30 min.

[0018] Further, in step (3), the ultrasonic treatment time is 10 - 30 min, and the power is 200 - 400 W.

[0019] Compared with the prior art, the technical solution of the present invention has at least the following beneficial effects:

[0020] The self-healing negative-carbon cement-based grouting material of the present invention effectively solves the problems of poor grouting density, gaps left, and self-shrinkage of traditional cement-based grouting materials, resulting in voids between the grouting material and the crack surface of the structure to be repaired and poor grouting reinforcement effect. The reasons are as follows:

[0021] (1) The present invention first uses excessive carbon dioxide to modify the leaching solution of carbide slag, which can not only consume carbon dioxide, offset part of the carbon emissions generated in cement production in the silicate cement-based grouting material, and reduce the carbon footprint of the cement-based grouting material. Moreover, the calcium bicarbonate contained in the obtained mixing solution reacts with the calcium hydroxide generated by cement hydration during the hardening stage after the grouting material is grouted to form calcium carbonate, filling the matrix of the grouting material and improving the density. At the same time, by consuming the calcium hydroxide generated by the hydration, the alkalinity of the grouting material is reduced, which is more conducive to the survival of microorganisms in the microorganism-sodium alginate repair material, enabling it to better play the role of repairing cracks generated in the matrix of the grouting material.

[0022] (2) The present invention uses ultrasonic treatment to make part of the microorganism-sodium alginate repair material diffuse to the outer layer of the cement-based grouting material, while the other part is embedded in the cement-based grouting material, thus forming a gradient distribution characteristic of the concentration of the microorganism-sodium alginate repair material in the cement-based grouting material gradually increasing from the inside to the outside. After injecting this grouting material into cracks, etc., the sodium alginate cross-links with the calcium ions released by cement hydration to form calcium alginate hydrogel, which absorbs moisture in the environment and swells to fix the microorganisms at the cracks and secrete calcium carbonate to repair the cracks. Due to the above-mentioned concentration gradient distribution characteristic, most of the hydrogel and calcium carbonate are enriched between the grouting material and the crack surface, which can not only increase the bonding strength between the grouting material and the crack surface, but also effectively solve the problem of voids generated between the grouting material and the crack surface caused by shrinkage of the grouting material and incomplete grouting of the joint, greatly improving the grouting reinforcement effect. At the same time, when cracks occur in the grouting material, the calcium alginate hydrogel can quickly repair itself, improving the grouting reinforcement effect.

[0023] (3) The present invention utilizes the density difference between the portland cement-based grouting material and the microorganism-sodium alginate repair material to make the repair material exhibit an asymmetric concentration distribution characteristic in the grouting material, significantly improving the utilization efficiency of the repair material and avoiding the problem that the grouting material is prone to failure due to reasons such as the alkaline environment in the cement-based material for a long time. The Bacillus pasteurii microorganisms can secrete calcium carbonate to seal the cracks at the cracks for a long time and stably under the anchoring action of calcium alginate hydrogel, avoiding the problem of microorganism loss caused by traditional methods such as brushing or soaking. At the same time, the Bacillus pasteurii microorganisms are protected by the calcium alginate hydrogel and do not directly contact the cement alkaline environment, which is beneficial to their long-term survival. The present invention distributes most of the microorganism-sodium alginate repair material on the periphery of the grouting material, effectively avoiding the alkaline environment of the cement. Coupled with the role of calcium bicarbonate in reducing the alkalinity of the grouting material in the above-mentioned mixing liquid, it can effectively improve the survival conditions of microorganisms. It not only ensures the long-term effectiveness of microorganisms but also is consistent with the cracking law of the grouting material. The cracks gradually develop from the outside to the inside, so that the cracks can be repaired at the beginning and play a role, reducing the problem that the reinforcement effect of the grouting material is reduced due to cracks. Description of the Drawings

[0024] It should be noted that the accompanying drawings in the specification, which form a part of the present invention, are used to provide a further understanding of the present invention and do not constitute an improper limitation to the present invention.

[0025] Figure 1 Diagram of the self-healing negative-carbon cement-based grouting material sample with a gradient structure prepared for Example 1 below;

[0026] Figure 2 Scanning electron microscope image of the self-healing negative-carbon cement-based grouting material with a gradient structure prepared for Example 1 below;

[0027] Figure 3 Diagram of the strength recovery rate performance test for Example 1 below. Detailed Embodiments

[0028] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. Unless otherwise defined, all professional and scientific terms used in the present invention have the same meaning as those familiar to those skilled in the art. The preferred implementation methods and materials described in the present invention are only for demonstration purposes. The reagents or raw materials used in the invention can be obtained through conventional channels. Unless otherwise specified, the reagents or raw materials used in the present invention are used in the conventional manner in the art or in accordance with the product instructions. The technical solutions of the present invention will be further described below in conjunction with the specific embodiments.

[0029] Example 1

[0030] A preparation method of a self-healing negative-carbon cement-based grouting material based on a gradient structure, comprising the following steps:

[0031] (1) Mix carbide slag and water in a mass ratio of 1:10, stir evenly, and then let it stand for 2 hours. After completion, filter out the soaking solution, then place the soaking solution in a transparent container, and continuously introduce carbon dioxide into the soaking solution at a rate of 12 L / min through an air delivery pipe. The discharged carbon dioxide gas is collected and reused. Wait until the soaking solution first becomes turbid, and then becomes clear again as carbon dioxide continues to be introduced, then the mixing solution is obtained and reserved for use.

[0032] (2) Mix 42.5 ordinary Portland cement, silica fume, and VAE latex powder in a ratio of 63 parts by weight: 8 parts by weight: 2.5 parts by weight, stir evenly, and obtain a Portland cement-based grouting material for standby.

[0033] (3) Weigh each raw material according to the following ratio: DSM 33 Bacillus pasteurii microbial liquid (the number of live bacteria is 1.7×10 13 CFU), water, sodium alginate, urea, and calcium acetate = 15 mL: 100 ml: 1 g: 5 g: 15 g. Then add the Bacillus pasteurii microbial liquid to water, stir evenly, first add the sodium alginate, stir evenly, then add the urea and calcium acetate, and stir evenly to obtain a microbial-sodium alginate repair material for standby.

[0034] (4) Mix the mixing solution, Portland cement-based grouting material, and microbial-sodium alginate repair material of this example in a mass ratio of 0.35:1.0:0.015, stir evenly, and obtain a composite grouting material for standby.

[0035] (5) After filling the composite grouting material into a container, place it on a vibration platform with a frequency of 5 Hz and vibrate for 20 min to remove the air in the slurry. Then seal the container with a sealing cover and place it in the water of an ultrasonic cleaner, and process it for 15 min with an ultrasonic power of 400 W to obtain a self-healing negative-carbon cement-based grouting material, and its sample Figure 1 is shown.

[0036] Figure 2 is the scanning electron microscope image of the inside of the hardened self-healing negative-carbon cement-based grouting material of this example. It can be seen that the surface of the grouting material is covered with a layer of hairpin-shaped gels, which expand evenly outward. These gels can effectively block the void area of the grouting material and can also repair cracks, improving the reinforcement effect of the grouting material.

[0037] Performance test: Set the pressure corresponding to 80% of the 28-day compressive strength of the concrete specimen as the load damage pressure value. Then apply the above pressure load to the concrete specimen and maintain it for 30 s to obtain a pressure load damaged and cracked concrete specimen. Inject the grouting material prepared in this embodiment into the cracks of the cracked concrete specimen until it is full, place it under standard curing conditions for 7 days, and at the same time set the cracked but ungrouted and repaired concrete specimen as the control group. Then, according to the "Standard for Test Methods of Physical and Mechanical Properties of Concrete" (GBT 50081-2019), test the compressive strength of the above specimens, and the results are as Figure 3 shown. It can be seen that when the concrete specimen is cracked and untreated, its compressive strength is only 12.07 MPa. After being repaired with the grouting material prepared in this embodiment, the strength of the concrete specimen (repair group) is 25.11 MPa, which is 13.05 MPa higher than that of the control group, and the strength recovery rate reaches 108.12%, showing a good effect of grouting reinforcement.

[0038] Example 2

[0039] A preparation method of a self-healing negative-carbon cement-based grouting material based on a gradient structure includes the following steps:

[0040] (1) Mix carbide slag and water at a mass ratio of 1:8, stir evenly, and then let it stand for 1.5 hours. After completion, filter out the soaking solution, then place the soaking solution in a transparent container, and continuously pass carbon dioxide into the soaking solution at a rate of 10 L / min through an air delivery pipe. The discharged carbon dioxide gas is collected and reused. Wait until the soaking solution first becomes turbid and then becomes clear again as carbon dioxide continues to be passed in to obtain a mixing solution for standby.

[0041] (2) Mix 42.5 ordinary Portland cement, silica fume, and VAE latex powder in a ratio of 70 parts by weight: 12 parts by weight: 3 parts by weight, and stir evenly to obtain a Portland cement-based grouting material for standby.

[0042] (3) Weigh each raw material according to the following ratio: DSM 33 Bacillus pasteurii microbial liquid (the number of live bacteria is 1×10 14 CFU), water, sodium alginate, urea, and calcium acetate = 10 mL: 105 ml: 0.7 g: 4 g: 12 g. Then add the Bacillus pasteurii microbial liquid to water, stir evenly, first add the sodium alginate, stir evenly, then add the urea and calcium acetate, and stir evenly to obtain a microbial-sodium alginate repair material for standby.

[0043] (4) Mix the mixing solution, silicate cement-based grouting material, and microorganism-sodium alginate repair material of this embodiment according to a mass ratio of 0.5:1.0:0.02, and stir evenly to obtain a composite grouting material for standby.

[0044] (5) After filling the composite grouting material into a container, place it on a vibration platform with a frequency of 3 Hz and vibrate for 30 min to remove the air in the slurry. Then, seal the container with a sealing cover and place it in the water of an ultrasonic cleaner, and process it for 30 min with an ultrasonic power of 200 W to obtain a self-repairing negative carbon cement-based grouting material.

[0045] Use the same method as in Example 1 above to test the strength recovery rate of the grouting material prepared in this embodiment for cracked concrete specimens. The result is 113.76%, showing a good effect of grouting reinforcement.

[0046] Example 3

[0047] A preparation method of a self-repairing negative carbon cement-based grouting material based on a gradient structure includes the following steps:

[0048] (1) Mix carbide slag and water according to a mass ratio of 1:20, stir evenly, and then let it stand for 1 hour. After completion, filter out the soaking solution, place the soaking solution in a transparent container, and continuously introduce carbon dioxide into the soaking solution at a rate of 15 L / min through an air pipe. The discharged carbon dioxide gas is collected and reused. Wait until the soaking solution first becomes turbid and then becomes clear again as carbon dioxide continues to be introduced to obtain a mixing solution for standby.

[0049] (2) Mix 42.5 ordinary Portland cement, silica fume, and VAE latex powder according to a ratio of 60 parts by weight: 7 parts by weight: 2 parts by weight, and stir evenly to obtain a silicate cement-based grouting material for standby.

[0050] (3) Weigh each raw material according to the following ratio: DSM 33 Bacillus pasteurii microbial liquid (the number of live bacteria is 1×10 12 CFU), water, sodium alginate, urea, and calcium acetate = 17 mL: 110 ml: 1.5 g: 8 g: 20 g. Then add the Bacillus pasteurii microbial liquid to water, stir evenly, first add the sodium alginate, stir evenly, then add the urea and calcium acetate, and stir evenly to obtain a microorganism-sodium alginate repair material for standby.

[0051] (4) Mix the mixing solution, silicate cement-based grouting material, and microorganism-sodium alginate repair material of this embodiment according to a mass ratio of 0.2:1.0:0.005, and stir evenly to obtain a composite grouting material for standby.

[0052] (5) After filling the composite grouting material into a container, place it on a vibrating platform with a frequency of 5 Hz and vibrate for 10 minutes to remove the air in the slurry. Then, seal the container with a sealing cover and place it in the water of an ultrasonic cleaner, and process it for 10 minutes with an ultrasonic power of 300 W to obtain the self-healing negative carbon cement-based grouting material.

[0053] Use the same method as in Example 1 above to test the strength recovery rate of the grouting material prepared in this example for the cracked concrete specimen. The result is 119.43%, showing a good effect of grouting reinforcement.

[0054] Example 4

[0055] A preparation method of a self-healing negative carbon cement-based grouting material based on a gradient structure includes the following steps:

[0056] (1) Mix carbide slag and water in a mass ratio of 1:10, stir evenly, and then let it stand for 2 hours. After completion, filter out the soaking solution, then place the soaking solution in a transparent container, and continuously introduce carbon dioxide into the soaking solution at a rate of 12 L / min through an air delivery pipe. The discharged carbon dioxide gas is collected and reused. Wait until the soaking solution first becomes turbid and then becomes clear again as carbon dioxide continues to be introduced to obtain the mixing solution, which is reserved for use.

[0057] (2) Mix 42.5 ordinary Portland cement, silica fume, and VAE latex powder in a ratio of 63 parts by weight: 8 parts by weight: 2.5 parts by weight, stir evenly to obtain the Portland cement-based grouting material, which is reserved for use.

[0058] (3) Weigh each raw material according to the following ratio: DSM 33 Bacillus pasteurii microbial liquid (the number of viable bacteria is 1.7×10 13 CFU), water, sodium alginate, urea, and calcium acetate = 15 mL: 100 ml: 1 g: 5 g: 15 g. Then add the Bacillus pasteurii microbial liquid to the water, stir evenly, first add the sodium alginate, stir evenly, then add the urea and calcium acetate, and stir evenly to obtain the microbial-sodium alginate repair material, which is reserved for use.

[0059] (4) Mix the mixing solution, Portland cement-based grouting material, and microbial-sodium alginate repair material of this example in a mass ratio of 0.35:1.0:0.015, stir evenly to obtain the composite grouting material, which is reserved for use.

[0060] (5) After filling the composite grouting material into a container, place it on a vibrating platform with a frequency of 5 Hz and vibrate for 20 minutes to remove the air in the slurry, and obtain the self-healing negative carbon cement-based grouting material.

[0061] The strength recovery rate of the grouting material prepared in this example for cracked concrete specimens was tested using the same method as in Example 1 above, and the result was 86.27%.

[0062] Example 5

[0063] A preparation method of a self-healing negative-carbon cement-based grouting material based on a gradient structure includes the following steps:

[0064] (1) Weigh each raw material according to the following ratio: DSM 33 Bacillus pasteurii microbial liquid (the number of live bacteria is 1×10 12 CFU), water, urea, and calcium acetate = 17 mL: 110 mL: 8 g: 20 g. Then add the Bacillus pasteurii microbial liquid to water, stir evenly, and then add the urea and calcium acetate, and stir evenly to obtain a microbial repair material for standby.

[0065] (2) Mix the mixing liquid (the same as in Example 3 above), the silicate cement-based grouting material, and the microbial repair material of this example in a mass ratio of 0.2:1.0:0.005, and stir evenly to obtain a composite grouting material for standby.

[0066] (3) After filling the composite grouting material into a container, place it on a vibration platform with a frequency of 5 Hz and vibrate for 10 min to remove the air in the slurry. Then seal the container with a sealing cover and place it in the water of an ultrasonic cleaner, and process it at an ultrasonic power of 300 W for 10 min to obtain the self-healing negative-carbon cement-based grouting material.

[0067] The strength recovery rate of the grouting material prepared in this example for cracked concrete specimens was tested using the same method as in Example 1 above, and the result was 98.31%.

[0068] Example 6

[0069] A preparation method of a self-healing negative-carbon cement-based grouting material based on a gradient structure includes the following steps:

[0070] (1) Mix 42.5 ordinary Portland cement, silica fume, and VAE latex powder in a ratio of 70 parts by weight: 12 parts by weight: 3 parts by weight, and stir evenly to obtain a silicate cement-based grouting material for standby.

[0071] (2) Mix clean water, the silicate cement-based grouting material, and the microbial-sodium alginate repair material (the same as in Example 2 above) in a mass ratio of 0.5:1.0:0.02, and stir evenly to obtain a composite grouting material for standby.

[0072] (3) After filling the composite grouting material into a container, place it on a vibrating platform with a frequency of 3 Hz and vibrate for 30 min to remove the air in the slurry. Then, seal the container with a sealing cover and place it in the water of an ultrasonic cleaner, and process it for 30 min with an ultrasonic power of 200 W to obtain the self-healing negative carbon cement-based grouting material.

[0073] Use the same method as in Example 1 above to test the strength recovery rate of the grouting material prepared in this example for the cracked concrete specimen, and the result is 94.05%.

[0074] Example 7

[0075] A preparation method of a self-healing negative carbon cement-based grouting material based on a gradient structure includes the following steps:

[0076] (1) Mix carbide slag and water in a mass ratio of 1:10, stir evenly, and then let it stand for 2 hours. After completion, filter out the soaking solution, and then place the soaking solution in a transparent container to obtain the mixing solution for standby.

[0077] (2) Mix 42.5 ordinary Portland cement, silica fume, and VAE latex powder in a ratio of 63 parts by weight: 8 parts by weight: 2.5 parts by weight, stir evenly to obtain the Portland cement-based grouting material for standby.

[0078] (3) Weigh each raw material according to the following ratio: DSM 33 Bacillus pasteurii microbial liquid (the number of live bacteria is 1.7×10 13 CFU), water, sodium alginate, urea, and calcium acetate = 15 mL: 100 ml: 1 g: 5 g: 15 g. Then add the Bacillus pasteurii microbial liquid to the water, stir evenly, first add the sodium alginate, stir evenly, then add the urea and calcium acetate, and stir evenly to obtain the microbial-sodium alginate repair material for standby.

[0079] (4) Mix the mixing solution, Portland cement-based grouting material, and microbial-sodium alginate repair material of this example in a mass ratio of 0.35:1.0:0.015, stir evenly to obtain the composite grouting material for standby.

[0080] (5) After filling the composite grouting material into a container, place it on a vibrating platform with a frequency of 5 Hz and vibrate for 20 min to remove the air in the slurry. Then, seal the container with a sealing cover and place it in the water of an ultrasonic cleaner, and process it for 15 min with an ultrasonic power of 400 W to obtain the self-healing negative carbon cement-based grouting material.

[0081] Use the same method as in Example 1 above to test the strength recovery rate of the grouting material prepared in this example for the cracked concrete specimen, and the result is 83.64%.

[0082] The foregoing is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. should be included within the protection scope of the present invention.

Claims

1. A preparation method of a self-healing negative-carbon cement-based grouting material based on a gradient structure, characterized in that, The steps include: (1) adding carbide slag into water to fully soak it, separating the soaking liquid, and then introducing excess carbon dioxide into the soaking liquid to convert calcium hydroxide into calcium bicarbonate, and obtaining a mixing liquid after completion; (2) mixing the mixing liquid, silicate cement-based grouting material and microorganism-sodium alginate repair material to obtain a composite grouting material; (3) The composite grouting material is placed in a container for degassing treatment and then placed in water in an ultrasonic cleaning machine for ultrasonic treatment for 10 to 30 minutes. The power of the ultrasonic treatment is 200 to 400 W, so that a part of the microorganism-sodium alginate repair material diffuses into the outer layer of the cement-based grouting material, while the other part is embedded in the cement-based grouting material, thereby forming a gradient distribution characteristic in which the concentration of the microorganism-sodium alginate repair material in the cement-based grouting material gradually increases from the inside to the outside, that is, a self-repairing negative carbon cement-based grouting material is obtained; In step (2), the microorganism-sodium alginate repair material is prepared by the following method: adding Bacillus pasteurianus microbial liquid to water and mixing, and then adding sodium alginate, urea and calcium acetate, and mixing to obtain the repair material.

2. The preparation method of the self-healing negative carbon cement-based grouting material based on a gradient structure according to claim 1, characterized in that, In step (1), the mass ratio of the carbide slag to water is 1:8-20.

3. The preparation method of the self-healing negative-carbon cement-based grouting material based on a gradient structure according to claim 1, characterized in that, In step (1), the soaking time is 1 to 2 hours.

4. The preparation method of the self-healing negative carbon cement-based grouting material based on the gradient structure according to claim 1, characterized in that, In step (1), the rate of introducing carbon dioxide is 10-15 L / min; after the introduction of carbon dioxide, the soaking liquid first becomes turbid, and then becomes clear again as the carbon dioxide continues to be introduced, thereby obtaining the mixing liquid.

5. The preparation method of the self-healing negative-carbon cement-based grouting material based on the gradient structure according to claim 1, characterized in that, In step (2), the mass ratio of the mixing liquid, silicate cement-based grouting material, and microorganism-sodium alginate repair material is 0.2~0.5:1.0:0.005~0.

02.

6. The preparation method of the self-healing negative-carbon cement-based grouting material based on the gradient structure according to claim 1, characterized in that, In step (2), the silicate cement-based grouting material includes silicate cement, silica fume and organic latex powder.

7. The preparation method of the self-healing negative-carbon cement-based grouting material based on the gradient structure according to claim 6, characterized in that, The ratio of the silicate cement, silica fume and organic latex powder is 60-70 parts by weight: 7-12 parts by weight: 2-3 parts by weight.

8. The preparation method of the self-healing negative-carbon cement-based grouting material based on the gradient structure according to claim 7, characterized in that, The ratio of the Bacillus pasteurianus microbial liquid, water, sodium alginate, urea and calcium acetate is 10-17 mL: 100 mL: 0.7-1.5 g: 4-8 g: 12-20 g.

9. The preparation method of the self-healing negative-carbon cement-based grouting material based on the gradient structure according to claim 8, characterized in that, The viable count in the Bacillus pasteurii microbial liquid is 1×10 12 ~1×10 14 CFU.

10. The preparation method of the self-healing negative-carbon cement-based grouting material based on the gradient structure according to any one of claims 1-9, characterized in that, In step (3), the degassing method is vibration degassing.

11. The preparation method of the self-healing negative-carbon cement-based grouting material based on a gradient structure according to claim 10, characterized in that, The vibration frequency is 3-5 Hz, and the vibration time is 10-30 min.

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