Preparation method of debris flow protection engineering self-repairing concrete part using microorganisms and magnesium oxide

Abstract

The invention provides a preparation method of a debris flow protection engineering self-repairing concrete part by using microorganisms and magnesium oxide, which comprises the following steps: S1, dipping a porous aggregate base material with the particle size distribution of 1-5mm in a urease-producing microbial agent, and enabling urease-producing microorganisms in the urease-producing microbial agent to fully enter pores of the porous aggregate base material; s2, urea and magnesium oxide are added into the urease-producing microbial agent impregnated with the porous aggregate base material to obtain a mixed solution, the mixed solution is maintained for 2-5 days, the self-repairing aggregate with the particle size distribution ranging from 2 mm to 10 mm is obtained, urea, urease-producing microorganisms, magnesium oxide and water react with one another in the maintenance period, a hardened shell wrapping the outer surface of the porous aggregate base material is generated, and the self-repairing aggregate with the particle size distribution ranging from 2 mm to 10 mm is obtained. Urea and urease-producing microorganisms are retained in pores of the porous aggregate base material, and the hardened shell comprises brucite, basic magnesium carbonate and magnesium oxide which is not completely reacted; and S3, mixing the self-repairing aggregate with the debris flow protection material, and curing to obtain the debris flow protection engineering self-repairing concrete piece utilizing the microorganisms and the magnesium oxide.

Description

Technical Field

[0001] This invention relates to the field of concrete repair technology, specifically to a method for preparing self-healing concrete components for debris flow protection projects using microorganisms and magnesium oxide. Background Technology

[0002] Debris flow disasters have become major mountain geological disasters, seriously affecting engineering construction and safety, and causing significant casualties and property losses every year.

[0003] Existing debris flow protection projects (such as retaining dams, retaining walls, and sediment traps) are prone to cracking and structural deterioration under long-term exposure to water erosion, freeze-thaw cycles, and debris flow particle impact. If these cracks are not repaired promptly, they can lead to leakage, reduced strength, and even project failure. Traditional repair methods mainly rely on manual grouting and sprayed cement mortar, which suffer from long repair cycles, high secondary construction costs, and difficulty in responding promptly to hidden cracks. Therefore, a self-healing, green, and sustainable method is needed to maintain these protective projects.

[0004] To reduce the cost of manual maintenance, self-healing technologies based on microbially induced calcium carbonate precipitation (MICP) have been proposed in recent years. This technology uses urease-producing microorganisms to decompose urea to produce carbonate ions, which then combine with calcium ions to form calcium carbonate, which is deposited in the cracks to achieve automatic healing. However, existing MIP technologies still have the following shortcomings when applied to debris flow protection projects: (1) Limited repair efficiency: Existing microbially induced precipitation is mainly suitable for repairing micron-sized cracks, and its ability to repair millimeter-sized or even larger cracks is insufficient, making it difficult to meet the actual engineering needs; (2) The carrier introduces structural weak points: In order to maintain the activity of microorganisms, they usually need to be fixed in a porous carrier and mixed with materials. However, these carrier areas often become weak points in the structure, and are more prone to cracking under external forces, which reduces the overall durability.

[0005] Therefore, there is an urgent need for a self-healing technology that can effectively repair larger-scale cracks without weakening the overall strength of the protective structure, so as to improve the long-term service performance and safety of debris flow protection projects. Summary of the Invention

[0006] In order to overcome the shortcomings of the existing technology, the present invention provides a method for preparing self-healing concrete components for debris flow protection engineering using microorganisms and magnesium oxide.

[0007] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0008] A method for preparing self-healing concrete components for debris flow protection engineering using microorganisms and magnesium oxide includes the following steps:

[0009] S1. A porous aggregate substrate with a particle size distribution of 1~5mm is impregnated in a urease-producing microbial agent, so that the urease-producing microorganisms in the urease-producing microbial agent can fully enter the pores of the porous aggregate substrate.

[0010] S2 adds urea and magnesium oxide to the urease-producing microbial agent impregnated with the porous aggregate substrate to obtain a mixture. The mixture is cured for 2-5 days to obtain self-healing aggregate with a particle size distribution of 2-10 mm. During the curing period, the urea, the urease-producing microorganisms, the magnesium oxide and water react with each other to generate a hardened shell covering the outer surface of the porous aggregate substrate. The urea and the urease-producing microorganisms are retained in the pores of the porous aggregate substrate. The hardened shell includes brucite, basic magnesium carbonate and unreacted magnesium oxide.

[0011] S3 After mixing the self-healing aggregate with debris flow protection material and curing it, a self-healing concrete component for debris flow protection engineering utilizing microorganisms and magnesium oxide is obtained.

[0012] In one embodiment, the urease-producing microorganism is Bacillus pasteurellii.

[0013] In one embodiment, the viable count of the urease-producing microorganisms in the urease-producing microbial agent is 1.0 ~ 1.5 × 10⁻⁶. 9 CFU / mL.

[0014] In one embodiment, the urease-producing microbial agent further includes 20 g / L of yeast extract.

[0015] In one embodiment, the porous aggregate substrate is porous volcanic rock.

[0016] In one embodiment, in step S1, the mass of the porous aggregate substrate added to each liter of the urease-producing microbial agent is 2000-4000g, and / or, in step S2, the mass of the urea added to each liter of the urease-producing microbial agent is 30-120g, and / or, in step S2, the mass of the magnesium oxide added to each liter of the urease-producing microbial agent is 300-500g.

[0017] In one embodiment, in step S2, the mass ratio of the self-healing aggregate with a particle size of 2-5 mm to the self-healing aggregate with a particle size of 5-10 mm is 1:0.5-1.

[0018] In one embodiment, in step S3, the maintenance time is 25 to 30 days.

[0019] In one embodiment, in step S3, the debris flow protection material includes sand, gravel, cement, and water, and / or, in step S3, the mass ratio of the self-healing aggregate to the conventional coarse aggregate in the debris flow protection material is 1:5~10.

[0020] In one embodiment, the self-healing concrete component for debris flow protection engineering utilizing microorganisms and magnesium oxide can be used in debris flow protection engineering.

[0021] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:

[0022] a. This invention utilizes the synergistic reaction of urease-producing microorganisms, urea, and magnesium oxide to generate a hardened shell that coats the outer surface of a porous aggregate substrate. The hardened shell is mainly composed of brucite, basic magnesium carbonate, and unreacted magnesium oxide. This porous aggregate substrate coated with the hardened shell has excellent strength and good compatibility with other matrix materials when mixed. It does not weaken the overall performance of the self-healing concrete component for debris flow protection engineering using microorganisms and magnesium oxide. At the same time, the hardened shell also isolates the urease-producing microorganisms to prevent further reactions after subsequent cracking.

[0023] b. The self-healing concrete component of the debris flow protection project utilizing microorganisms and magnesium oxide of the present invention, after cracking under external force, allows water to seep in, activating urease-producing microorganisms remaining in the pores of the porous aggregate substrate, decomposing urea to produce carbonate ions; carbonate ions promote the carbonation of the outer layer of brucite to form basic magnesium carbonate, while magnesium oxide reacts with water to form magnesium hydroxide, maintaining an alkaline environment and enhancing microbial activity and mineralization efficiency; the microbial mineralization products, magnesium oxide hydration products brucite, and magnesium oxide carbonation products basic magnesium carbonate are deposited together in the crack, forming a larger and more tightly bound repair product, thereby achieving self-repair of the crack;

[0024] c. In this invention, by setting the particle size distribution of the porous aggregate substrate to 1~5mm, a self-healing aggregate with a particle size distribution of 2~10mm is obtained. It can use self-healing aggregates of different particle sizes to repair micron to millimeter-level cracks, significantly improve the impermeability, erosion resistance and freeze-thaw resistance of debris flow protection projects, and achieve long-term durability of the structure. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of a self-healing aggregate provided in an embodiment of the present invention;

[0026] Figure 2 This is a schematic diagram of a self-healing concrete component for debris flow protection engineering utilizing microorganisms and magnesium oxide, provided in an embodiment of the present invention.

[0027] Numbering on the map:

[0028] 1-Porous aggregate substrate; 2-Hardened shell; 3-Urease-producing microorganisms; 4-Self-healing aggregate; 5-Conventional coarse aggregate; 6-Repair product. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Unless specifically stated, they can be replaced by other equivalent or similar alternative features. Unless specifically stated, each feature is only one example of a series of equivalent or similar features. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Therefore, the detailed description of the embodiments of the present invention provided below is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the invention.

[0030] Unless otherwise specified, the terminology used in this invention generally has the meanings commonly understood by those skilled in the art. The implementation conditions used in the embodiments can be further adjusted according to different specific requirements; implementation conditions not specified are conventional conditions in the industry. The technical features involved in the various embodiments of this invention can be combined with each other as long as they do not conflict with each other.

[0031] In this invention, operations without specific instructions are performed at room temperature. The raw materials used in this application are commercially available or can be prepared using conventional methods in the prior art.

[0032] This invention discloses a method for preparing self-healing concrete components for debris flow protection engineering using microorganisms and magnesium oxide. This method can be applied to debris flow protection projects, such as debris flow retaining walls or dam structures. During service, when these structures crack under external forces, water seeps in, activating urease-producing microorganisms in the pores of the porous aggregate substrate. These microorganisms decompose urea to produce carbonate ions. The carbonate ions promote the carbonation of the outer layer of brucite to form basic magnesium carbonate. Simultaneously, magnesium oxide reacts with water to form magnesium hydroxide, maintaining an alkaline environment and enhancing microbial activity and mineralization efficiency. The microbial mineralization product calcium carbonate, the magnesium oxide hydration product brucite, and the magnesium oxide carbonation product basic magnesium carbonate are deposited together in the cracks, forming larger and more tightly bonded repair products, thus achieving self-healing of the cracks. Compared with traditional MICP technology, this invention can effectively repair large cracks, and the self-healing aggregate has high strength and good compatibility with the matrix, preventing it from becoming a weak point, significantly improving the durability and safety of debris flow protection engineering.

[0033] like Figures 1-2As shown, this invention provides a method for preparing self-healing concrete components for debris flow protection engineering using microorganisms and magnesium oxide, mainly including the following steps:

[0034] S1. The porous aggregate substrate 1 with a particle size distribution of 1~5mm is impregnated in a urease-producing microbial agent, so that the urease-producing microorganisms 3 in the urease-producing microbial agent can fully enter the pores of the porous aggregate substrate 1.

[0035] In some embodiments, the porous aggregate substrate 1 is impregnated with a urease-producing microbial agent for 4-8 hours.

[0036] In some embodiments, the porous aggregate substrate 1 is specifically porous volcanic rock, which is a volcanic rock mainly composed of vesicular basalt and perlite, and is a common building material;

[0037] In some embodiments, the porous volcanic rock needs to be cleaned and dried before being added in step S1 to prevent it from affecting the experimental results.

[0038] In some embodiments, the urease-producing microorganism 3 is Bacillus pasteurii, specifically Bacillus pasteurii strain numbered ATCC11859, and the viable count of Bacillus pasteurii in the urease-producing microbial agent is 1.0 ~ 1.5 × 10⁻⁶. 9 In some embodiments, the culture medium for the urease-producing microorganism 3 can be a sterile culture medium, including but not limited to yeast extract, ammonium sulfate, and tris-(hydroxymethyl)aminomethane (Tris Base). After sterilization, the culture medium is inoculated with Bacillus pasteurellii at an inoculum of 1-10% and cultured with shaking for 24 hours to form a urease-producing microbial inoculum. The yeast extract is used to enhance the activity of the urease-producing microorganism, and the tris-(hydroxymethyl)aminomethane and ammonium sulfate are used to regulate the growth of the urease-producing microorganism.

[0039] In some embodiments, the mass of porous aggregate substrate added to each liter of urease-producing microbial agent is 2000~4000g.

[0040] In some embodiments, the mass ratio of porous aggregate substrate with a particle size of 2-5 mm to porous aggregate substrate 1 with a particle size of 5-10 mm is 1:0.5-1. By limiting the mass ratio of the two particle sizes in porous aggregate substrate 1, the proportion of self-healing aggregates with different particle sizes obtained subsequently is controlled, thereby achieving the repair of cracks of different sizes.

[0041] S2 adds urea and magnesium oxide to a urease-producing microbial agent impregnated with porous aggregate substrate 1 to obtain a mixture. The mixture is cured for 2 to 5 days to obtain self-healing aggregate 4 with a particle size distribution of 2 to 10 mm. During the curing period, urea, urease-producing microorganisms 3, magnesium oxide and water react with each other to generate a hardened shell 2 that coats the outer surface of the porous aggregate substrate 1. Urea and urease-producing microorganisms 3 remain in the pores of the porous aggregate substrate 1. The hardened shell 2 includes brucite, basic magnesium carbonate and unreacted magnesium oxide.

[0042] In some embodiments, the mass of urea added to each liter of urease-producing microbial agent is 30-120g, and the mass of magnesium oxide added to each liter of urease-producing microbial agent is 300-500g.

[0043] In some embodiments, the magnesium oxide is specifically active magnesium oxide powder with a particle size of 75 μm.

[0044] In some embodiments, the curing time can be 2 to 5 days to allow the substances to react fully and generate a hardened shell 2 that coats the outer surface of the porous aggregate substrate 1 until the moisture in the pores of the porous aggregate substrate 1 is completely consumed. The curing conditions are a temperature of 10 to 30°C and a humidity of 75 ± 5%.

[0045] In some embodiments, the mass ratio of self-healing aggregate with a particle size of 2-5 mm to self-healing aggregate with a particle size of 5-10 mm is 1:0.5-1. By controlling the particle size of the self-healing aggregate, it is possible to ensure that cracks of different widths can be repaired. Specifically, the self-healing aggregate with a particle size of 2-5 mm can repair cracks with a width of 0.5-0.75 mm, and the self-healing aggregate with a particle size of 5-10 mm can repair cracks with a width of 0.75-1 mm.

[0046] S3 involves mixing self-healing aggregate with debris flow protection materials and then curing them to obtain self-healing concrete components for debris flow protection projects that utilize microorganisms and magnesium oxide.

[0047] In some embodiments, debris flow protection materials may be concrete, masonry, or other cement-based composite materials.

[0048] In some embodiments, the debris flow protection material includes sand, gravel, cement and water, and the mass ratio of the self-healing aggregate 4 to the conventional coarse aggregate 5 (such as sand and gravel) in the debris flow protection material can be 1:5 to 10.

[0049] In some embodiments, the curing time can be 25 to 30 days, and the curing conditions are a temperature of 10 to 30°C and a humidity of 75 ± 5%.

[0050] The main chemical reactions that occur in step S2 and when the self-healing concrete components for debris flow protection obtained in step S3, which utilize microorganisms and magnesium oxide, are applied to debris flow protection projects are as follows:

[0051] Urease-producing microorganisms hydrolyze urea to form carbonate ions: ;

[0052] Magnesium oxide hydrates to form magnesium hydroxide (brucite): ;

[0053] Magnesium hydroxide carbonizes to form basic magnesium carbonate (HMCs): .

[0054] In step S2, urease-producing microorganisms 3 decompose urea and water to produce carbonate ions. Magnesium oxide reacts with water to generate magnesium hydroxide. Carbonate and magnesium hydroxide react with water to carbonize and generate basic magnesium carbonate. The final product includes 60-70% magnesium hydroxide (brucite), 10-20% basic magnesium carbonate, and 10-20% unhydrated magnesium oxide. Magnesium hydroxide (brucite), basic magnesium carbonate, and magnesium oxide together constitute the hardened shell 2 encapsulating the outer surface of the porous aggregate substrate. Including magnesia trihydrate (MgCO3·3H2O), magnesia hydrous (MgCO3·Mg(OH)2·4H2O), and spheroidal magnesia (MgCO3·Mg(OH)2·5H2O), this porous aggregate substrate 1 coated with a hardened shell 2 has excellent strength and good compatibility with other matrix materials when mixed. It will not weaken the overall performance of the self-healing concrete component of the debris flow protection project using microorganisms and magnesium oxide. At the same time, the hardened shell 2 also plays the role of isolating urease-producing microorganisms 3 to prepare for further reactions after subsequent cracking.

[0055] When the self-healing concrete component for debris flow protection obtained in step S3, utilizing microorganisms and magnesium oxide, is applied to debris flow protection projects, water seeps into the component after it cracks under external force. This activates the urease-producing microorganisms 3 remaining in the pores of the porous aggregate substrate 1, which decompose urea to produce carbonate ions. The carbonate ions promote the carbonation of the outer layer of brucite to form basic magnesium carbonate. At the same time, magnesium oxide reacts with water to form magnesium hydroxide, maintaining an alkaline environment and enhancing microbial activity and mineralization efficiency. The microbial mineralization product calcium carbonate, the magnesium oxide hydration product brucite, and the magnesium oxide carbonation product basic magnesium carbonate are deposited together in the crack, forming a larger and more tightly bonded repair product 6, thereby achieving self-repair of the crack.

[0056] Example 1

[0057] The method for preparing self-healing concrete components for debris flow protection engineering using microorganisms and magnesium oxide in this embodiment mainly includes the following steps:

[0058] S1. The porous aggregate substrate with a particle size distribution of 1~5mm is impregnated in a urease-producing microbial agent for 6h, so that the urease-producing microorganisms in the urease-producing microbial agent can fully enter the pores of the porous aggregate substrate.

[0059] The porous aggregate substrate is specifically porous volcanic rock. Before adding the porous volcanic rock in this step, it needs to be cleaned and dried for later use. The urease-producing microorganism in this embodiment is *Bacillus pasteurii*, specifically strain number ATCC11859. The viable count of *Bacillus pasteurii* in the urease-producing microbial agent is 1 × 10⁻⁶. 9 The CFU / mL urease-producing microbial agent also includes 20 g / L yeast extract, 15.73 g / L tris(hydroxymethyl)aminomethane (Tris Base), and 10 g / L ammonium sulfate.

[0060] In this step, the mass of porous aggregate substrate added to each liter of urease-producing microbial agent is 3000g, and the mass ratio of porous aggregate substrate with a particle size of 1.25~2.5mm to porous aggregate substrate with a particle size of 2.5~5mm is 1:1.

[0061] S2 adds urea and magnesium oxide to a urease-producing microbial agent impregnated with a porous aggregate substrate to obtain a mixture. The mixture is cured for 3 days to obtain self-healing aggregate with a particle size distribution of 2-10 mm. The mass of urea added per liter of urease-producing microbial agent is 60 g, and the mass of magnesium oxide added per liter of urease-producing microbial agent is 500 g. The magnesium oxide is specifically active magnesium oxide powder with a particle size of 75 μm. The curing conditions are a temperature of 25°C and a humidity of 75%. In this embodiment, the mass ratio of self-healing aggregate with a particle size of 2-5 mm to self-healing aggregate with a particle size of 5-10 mm is 1:1.

[0062] S3 After mixing and curing the self-healing aggregate with the debris flow protection material, a self-healing concrete component for debris flow protection engineering utilizing microorganisms and magnesium oxide is obtained. In this embodiment, the debris flow protection material includes sand, gravel, cement, and water. The mass fraction of the self-healing aggregate is 197 parts, the mass fraction of sand is 718 parts, the mass fraction of gravel is 988 parts, the mass fraction of cement is 346 parts, and the mass fraction of water is 180 parts. That is, the mass ratio of the self-healing aggregate to conventional coarse aggregate (such as sand and gravel) is approximately 1:8.5. In this embodiment, the particle size of sand is 0.35~0.5mm, the particle size of gravel is 10~20mm, and the cement is specifically ordinary Portland cement (P·O 42.5). In this embodiment, the curing time is 28 days, and the curing conditions are a temperature of 25℃ and a humidity of 75%.

[0063] In this embodiment, the final gap filling rate of the self-healing concrete component for debris flow protection using microorganisms and magnesium oxide can reach over 90%. After 10 freeze-thaw cycles, the strength decreases by only 7% and the permeability coefficient increases by only 12%. The freeze-thaw cycle refers to the saturated concrete component being frozen at -20℃ for 12 hours and then thawed by immersion in water at 25℃ for 12 hours. The permeability coefficient refers to the flow rate of water that can permeate the concrete component under a unit hydraulic gradient.

[0064] Comparative Example 1

[0065] The main difference between this comparative example and Example 1 is:

[0066] In step S2, urea, calcium chloride, and nutrient powder are added to the urease-producing microbial agent impregnated with porous aggregate substrate. After drying, porous particles immobilized with urease-producing microorganisms, urea, calcium chloride, and nutrients are obtained. Metakaolin and sodium silicate are mixed at a mass ratio of 1:1, and then an equal mass of water is added. After stirring evenly to form a slurry, the porous particles immobilized with microorganisms, urea, calcium chloride, and nutrients are placed in the slurry for complete adsorption. After natural curing, they are dried to constant weight to obtain MICP self-healing aggregate with a particle size distribution of 2-10 mm. Each liter of urease-producing microbial agent contains 60 g of urea, 50 g of calcium chloride, and 5 g of nutrients, specifically beef peptone. The mass of porous particles added per liter of slurry is 3000 g.

[0067] In step S3, the MICP self-healing aggregate obtained in step 2 is mixed with debris flow protection material and cured to obtain a MICP self-healing concrete specimen with self-healing function. The specific composition and mass ratio of the debris flow protection material are the same as in Example 1, and the curing conditions are also the same as in Example 1.

[0068] In this comparative example, the main repair mechanism of the MICP self-healing aggregate is the microbial decomposition of urea to produce carbonate ions. These carbonate ions combine with calcium ions to form calcium carbonate, which fills the cracks. When cracks appear in the concrete specimen, the microorganisms are activated after moisture seeps in, inducing the formation of calcium carbonate deposits. For microcracks smaller than 200 μm, calcium carbonate deposition can essentially seal them, with a crack filling rate exceeding 90%. For cracks wider than 0.5 mm, calcium carbonate deposition is insufficient to completely fill them, resulting in poor repair performance and a crack filling rate of only 48%. Due to the low strength of the MICP porous carrier itself, under freeze-thaw cycles, the specimens are more prone to developing new cracks and damage at the carrier, leading to a decrease in overall durability. After 10 freeze-thaw cycles, the concrete specimen strength decreased by 37%, and the permeability coefficient increased by 234%.

[0069] Comparative Example 2

[0070] The main difference between this comparative example and Example 1 is that the porous aggregate substrate was not treated in this comparative example, and only volcanic rock with a size of 2-10 mm was used as aggregate. Because self-healing materials such as microorganisms and magnesium oxide were not used, the concrete specimens in this comparative example failed to heal after cracks appeared, with a crack filling rate of 0%. After 10 freeze-thaw cycles, the strength of the concrete specimens decreased by 54%, and the permeability increased by 373%.

[0071] In summary, the MICP technology in Comparative Example 1 can only repair micron-level cracks and cannot effectively repair millimeter-level cracks. In Comparative Example 2, the cracks failed to heal, and the porous carrier became a weak point in the structure. Compared to the self-healing concrete component of the debris flow protection project utilizing microorganisms and magnesium oxide in Example 1, this technology is significantly inferior in terms of repair efficiency, crack repair range, and structural strength maintenance.

[0072] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method for producing a self-repairing concrete member for debris flow protection works using microorganisms and magnesium oxide, characterized by, The method comprises the following steps: S1: immersing a porous aggregate base material with a particle size distribution of 1-5 mm in a urease-producing microbial agent, so that the urease-producing microorganisms in the urease-producing microbial agent enter the pores of the porous aggregate base material; S2: adding urea and magnesium oxide to the urease-producing microbial agent in which the porous aggregate base material is immersed to obtain a mixed solution, curing the mixed solution for 2-5 days to obtain self-repairing aggregate with a particle size distribution of 2-10 mm, and during the curing, the urea, the urease-producing microorganisms, the magnesium oxide and water react with each other to form a hardened shell wrapped on the outer surface of the porous aggregate base material, and the pores of the porous aggregate base material remain the urea and the urease-producing microorganisms, and the hardened shell comprises brucite, basic magnesium carbonate and unreacted magnesium oxide; S3: mixing the self-repairing aggregate with a debris flow protection material and curing to obtain a debris flow protection engineering self-repairing concrete piece using microorganisms and magnesium oxide.

2. Process for the preparation of a self-repairing concrete element for debris flow protection works with microorganisms and magnesia according to claim 1, characterized in that: The urease-producing microorganisms are Bacillus pasteurii.

3. Process for the preparation of a self-repairing concrete element for debris flow protection works with microorganisms and magnesia according to claim 2, characterized in that: The viable cell number of the urease-producing microorganism in the urease-producing microbial agent is 1.0 ~ 1.5 x 10 9 CFU / mL.

4. The method for preparing a debris flow protection engineering self-repairing concrete member using microorganisms and magnesia according to claim 2, characterized in that: The urease-producing microbial agent further comprises 20 g / L of yeast extract.

5. The method for preparing a debris flow protection engineering self-repairing concrete member using microorganisms and magnesia according to claim 1, characterized by: The porous aggregate base material is porous volcanic rock.

6. The method for preparing a debris flow protection engineering self-repairing concrete member using microorganisms and magnesia according to claim 1, characterized in that: In step S1, the mass of the porous aggregate base material added in the urease-producing microbial agent per liter is 2000-4000 g, and / or in step S2, the mass of the urea added in the urease-producing microbial agent per liter is 30-120 g, and / or in step S2, the mass of the magnesium oxide added in the urease-producing microbial agent per liter is 300-500 g.

7. The method for preparing a debris flow protection engineering self-repairing concrete member using microorganisms and magnesia according to claim 1, characterized by: In step S2, the mass ratio of the self-repairing aggregate with a particle size of 2-5 mm to the self-repairing aggregate with a particle size of 5-10 mm is 1:0.5-1.

8. The method for preparing a debris flow protection engineering self-repairing concrete member using microorganisms and magnesia according to claim 1, characterized by: In step S3, the curing time is 25-30 days.

9. The method for preparing a debris flow protection engineering self-repairing concrete member using microorganisms and magnesia according to claim 1, characterized by: In step S3, the debris flow protection material comprises sand, gravel, cement and water, and / or in step S3, the mass ratio of the self-repairing aggregate to the conventional coarse aggregate in the debris flow protection material is 1:5-10.

10. Process for the preparation of a self-healing concrete element for rockfall protection works with microorganisms and magnesia according to any one of claims 1 to 9, characterized in that: The debris flow protection engineering self-repairing concrete piece using microorganisms and magnesium oxide can be used in debris flow protection engineering.

Images