Self-repairing civil engineering material and construction method

Abstract

The invention discloses a self-repairing civil engineering material and a construction method, the engineering material comprises a base material and a microbial self-repairing agent dispersed in the base material, the microbial self-repairing agent comprises a microbial agent and a nutrient source, the microbial agent is a urease-producing microorganism domesticated by tolerating low temperature and alkaline environment, and the nutrient source is a nutrient source. The microbial self-repairing agent is wrapped by a capsule of a core-shell structure, the shell of the capsule is a protective layer capable of being dissolved under the water seepage condition, the inner core of the capsule is a porous carrier, and the microbial agent and the nutrient source are loaded in pores of the porous carrier. The construction method comprises the following steps: a1, mixing a microbial self-repairing agent with a base material raw material to prepare a composite material; and a2, the composite material is applied to the surface of a hydraulic structure base body to be repaired or protected. The problems that a self-repairing anti-seepage material cannot keep stable activity in a harsh low-temperature and high-alkali environment of a hydraulic structure, and meanwhile, crack water seepage is difficult to accurately respond to trigger a self-repairing reaction are solved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of civil engineering materials, and particularly relates to a self-repairing civil engineering material and a construction method. BACKGROUND

[0002] In the construction and long-term operation of water conservancy and hydropower projects, the anti-seepage system of the structures is the core lifeline to ensure their safety and stability and prolong their service life. Whether it is the core wall and dam foundation of a high dam and large reservoir or the lining and slope of a water conveyance channel, it is subjected to the coupling effects of water scouring, dry-wet cycling, freezing-thawing and foundation settlement for a long time.

[0003] Traditionally, the engineering field widely relies on geosynthetic materials (such as geomembranes), cement-based waterproof mortar or bentonite waterproof blankets and other materials to build the anti-seepage layer. These materials can often provide good anti-seepage effect at the initial stage, but they are essentially “passive” protection, and the material performance will gradually deteriorate over time and under environmental action. A particularly prominent problem is that these materials lack flexibility or adaptability, and when there is a slight deformation of the base layer, cracks are easily generated. Once cracks occur, water will enter, not only directly leading to leakage failure, but also possibly causing more serious engineering hidden dangers such as internal erosion and corrosion, and the repair work often needs to interrupt operation, carry out large-area excavation and replacement, which is costly and difficult to construct.

[0004] With the progress of material science, the concept of self-repairing has been introduced into the field of civil engineering, aiming to endow materials with the ability to repair themselves after damage, thereby changing from passive to active. Among them, the microbially induced calcium carbonate precipitation technology has attracted widespread attention due to its environmental friendliness and stability of the repair product. The basic principle is to use the metabolic activity of specific microorganisms to convert the provided nutrient source into calcium carbonate precipitation to fill the microcracks in the material. This technology provides a promising direction for solving the pain points of passive protection. There have been many attempts to directly incorporate such microbial repair agents into cement-based materials or mix them into soil.

[0005] However, when this technology goes from the laboratory to practical engineering, especially in the complex and harsh working conditions of water conservancy and hydropower engineering, its limitations are exposed. First, the environment of hydraulic structures is not ideal, for example, the water temperature of the bottom of high-altitude reservoirs is low all year round, and the interior of newly poured concrete is a high alkaline environment. These conditions are fatal to most microorganisms used for repair, causing their activity to decline sharply or even die, thus causing the self-repair function to fail at a critical moment. Second, traditional methods of adding microorganisms, such as simply mixing the bacterial solution with the nutrient agent and then adding it, have many problems. On the one hand, in the early stages of material mixing and pouring, strong alkaline environment or mechanical shear force can cause irreversible damage to microorganisms; on the other hand, the nutrient source may be consumed too early and cannot provide sustained and effective repair when cracks occur. Even some solutions try to use porous carriers to adsorb microorganisms, but their protective effect is limited, and it is difficult to control the triggering time of the repair reaction, which may cause local rapid mineralization to affect the overall performance of the material.

[0006] In view of the above technical problems, there are many self-repairing engineering technologies in the prior art, such as reference file 1: Chinese patent with patent number CN2024109329291 discloses a method for preparing a low-temperature alkali-tolerant concrete microbial self-repairing agent and its application; reference file 2: Chinese patent with patent number CN2023107456527 discloses a self-repairing concrete suitable for underwater cracks in cold regions and a preparation method thereof; reference file 3: Chinese patent with patent number CN202410550092.4 discloses a high-impervious self-repairing concrete and a preparation method thereof.

[0007] Reference file 1 uses Bacillus pasteurii for alkali-tolerant domestication (pH to 13), but does not involve low-temperature domestication or strain compounding, and the environmental adaptability is narrow; reference file 2 uses facultative aerobic bacteria domesticated from sludge, which is suitable for low-temperature and anoxic environment, but the source of the strain is unclear, and the compounding ratio or optimization strategy is not specified; reference file 3 uses aerobic microorganisms (such as Bacillus megaterium) and facultative anaerobic microorganisms (Bacillus pasteurii) in combination, but the strain ratio optimization or specific complementarity is not specified.

[0008] In addition, reference file 1 uses a coating material (such as metakaolin + sodium silicate), but the core-shell structure or intelligent triggering mechanism is not specified; and the repair agent is directly added, which is easy to consume early. Reference file 2 reduces water erosion by immobilizing on recycled aggregate and ceramsite, but has no shell dissolution triggering design, relies on physical carrier cracking to release, and is easy to cause inaccurate repair. Reference file 3 has a coating process (such as metakaolin geopolymer), but does not emphasize the water-triggered properties of the core-shell structure, and the protection effect is weak.

[0009] In addition, reference document 1 uses calcium lactate and urea, but does not specify the proportion, which may affect the mineralization stability; the nutrient source of reference document 2 is calcium lactate and sodium nitrate (non-urease pathway), which is suitable for anoxic environment but has a slower mineralization speed; reference document 3 clearly sets the proportion of the nutrient source to be 1:5, but does not demonstrate the advantages of the proportion range.

[0010] Therefore, although the microbial self-repairing technology is advanced in theory, in actual water conservancy engineering applications, the existing schemes often face challenges such as unreliable repair effect, poor environmental adaptability, and difficult precise control of the repair process. Engineering practice urgently needs a new type of material that can truly adapt to the particularity of the water conservancy environment, has stable and long-acting self-repairing ability, and not only can repair, but also can wait and accurately respond to damage under harsh conditions. This requires a deeper innovation of the activity maintenance, triggering mechanism of the repair agent and the synergistic working performance with the engineering matrix, rather than simply transplanting laboratory technology. SUMMARY

[0011] The purpose of the present application is to provide a self-repairing civil engineering material and a construction method to solve the problem that the self-repairing impermeable material in the prior art cannot maintain stable activity in the harsh low-temperature and high-alkali environment of the water conservancy structure, and is difficult to accurately respond to crack water triggering self-repairing reaction.

[0012] The technical scheme of the present application is as follows: A self-repairing civil engineering material, comprising a matrix material and a microbial self-repairing agent dispersed therein, the microbial self-repairing agent comprising a microbial agent and a nutrient source, the microbial agent being a urease-producing microorganism domesticated to resist low temperature and alkaline environment, the microbial self-repairing agent being encapsulated by a core-shell structure, the shell of the capsule being a protective layer that can dissolve under water infiltration conditions, the core of the capsule being a porous carrier, and the microbial agent and the nutrient source being loaded in the pores of the porous carrier.

[0013] The microbial agent is a compounded microbial population of B. mycoides and B. cereus, and the ratio of the viable bacterial count of B. mycoides to that of B. cereus in the compounded microbial population is 2-5:1.

[0014] The nutrient source is a compound of calcium lactate and urea, and the mass ratio of calcium lactate to urea in the compound is 1:3-7.

[0015] The porous carrier is at least one of expanded perlite, zeolite and diatomite.

[0016] The shell is a geopolymer layer or an organic-inorganic composite gel layer.

[0017] The microbial self-repairing agent accounts for 1.5%-10% of the total mass of the matrix material.

[0018] The base material is one of a cement-based material, a polymer coating, or a clay-based material.

[0019] The mass ratio of the microbial agent, the nutrient source, and the porous carrier in the microbial self-repairing agent is 1:3-5:6-10.

[0020] A construction method of a self-repairing civil engineering material, comprising the following steps: a1. Mixing the microbial self-repairing agent with the base material raw material to prepare a composite material; a2. Applying the composite material to the surface of the hydraulic structure base to be repaired or protected.

[0021] In step a2, after the composite material is applied to the surface of the hydraulic structure base, a curing step in a humid environment is further included.

[0022] The beneficial effects of the present application are: The present application uses specially domesticated composite microbial agents, which are introduced into the self-repairing civil engineering material, to improve the reliability of the material in harsh environments such as low temperature and high alkalinity in water conservancy projects, and to ensure the activity basis of the self-repairing function.

[0023] Through the design of the core-shell structure capsule, a reliable physical barrier is provided for the microbial agent and the nutrient source. This barrier can effectively isolate the internal microorganisms and nutrients from the external environment that may cause damage to them during the mixing, pouring, and early hardening stages of the material. At the same time, through the synergistic effect of the water-triggered dissolving shell and the porous carrier core, precise controlled release of the repair agent is achieved, effectively preventing pre-consumption during construction, and concentrating the repair capacity on dealing with actual damage.

[0024] The material system of the present application has good compatibility with the engineering base, is convenient to construct, and gives the hydraulic structure a long-term self-healing ability without changing the traditional process of the engineering base, thereby greatly reducing the maintenance cost and prolonging the service life of the hydraulic structure. DETAILED DESCRIPTION

[0025] A self-repairing civil engineering material, comprising a base material and a microbial self-repairing agent dispersed therein, the microbial self-repairing agent comprising a microbial agent and a nutrient source, the microbial agent being a urease-producing microorganism domesticated to resist low temperature and alkaline environment, the microbial self-repairing agent being wrapped by a core-shell structure capsule, the shell of the capsule being a protective layer that can dissolve under water infiltration conditions, the core of the capsule being a porous carrier, and the microbial agent and the nutrient source being loaded in the pores of the porous carrier.

[0026] The microorganism agent used in the present application is urease-producing microorganism domesticated to resist low temperature and alkaline environment. By gradually adapting urease-producing microorganism to low temperature and alkaline environment, it is equivalent to professional "pre-job training" for the microorganism, which makes its internal physiological characteristics change beneficially, so that it can maintain the willingness and ability to work under the harsh conditions of hydraulic structure. This step is the fundamental prerequisite to ensure that the whole repair system can start and continue to be effective, and it solves the problem of whether the microorganism can "survive" and "maintain combat effectiveness".

[0027] The microbial self-repairing agent is wrapped by a core-shell structure capsule, which can provide a miniature protective cabin with intelligent response characteristics for the microorganism agent and nutrient source. The existence of the shell first provides a reliable physical barrier, which can effectively isolate the internal microorganism and nutrient source from the external environment that may cause damage to them (such as strong alkaline pore solution, mechanical shear force) during the mixing, pouring and early hardening stages of the material, and avoids the unnecessary loss of valuable repair resources before the crack occurs.

[0028] Moreover, the dissolution characteristics of this shell mean that the protective layer will only be removed and the repair reaction will only be precisely started when the crack actually occurs and water intrusion appears as a specific signal. This "signal response" mechanism ensures the high targeting of the repair action, concentrates the repair ability on the real damage site, and effectively overcomes the drawbacks of blind consumption of repair agents in traditional methods. Thus, through the close combination of "directional domestication" and "intelligent triggering", a complete logical closed loop is formed: domestication ensures the survival ability of microorganisms in harsh environments, making repair possible; the core-shell capsule ensures that this repair ability can be preserved and precisely delivered to the time and place where it is needed.

[0029] Compared with the prior art, the self-repairing civil engineering material in the present application most directly shows that the reliability and long-term effectiveness of the material self-repairing function have been greatly improved. Due to the enhanced environmental adaptability of microorganisms, the probability of their remaining active during the engineering life cycle is significantly improved, so that the material not only can repair cracks in the short term, but also has the potential to maintain this repair ability in the long term. At the same time, the precise triggering characteristics brought by the core-shell structure greatly improve the utilization efficiency of repair resources, so that limited repair agents can be more effectively used to handle actual damage, thereby prolonging the maintenance-free period of the material. From the perspective of engineering application, this material exhibits better overall performance coordination. It not only maintains the original mechanical and impermeable properties of the base material, but also integrates the intelligent self-repairing function without sacrificing the performance of one side. This synergy makes the final material not a laboratory conceptual model, but a truly innovative engineering material that can adapt to complex engineering realities and has practical value.

[0030] This application employs a porous carrier as the capsule core to load microbial agents and nutrient sources. This design significantly improves the effective loading rate and activity retention of the remediation agent. The porous structure, with its large specific surface area, provides a large number of microenvironments for microorganisms to attach to. This not only achieves high-concentration encapsulation of the agents and nutrient sources, but more importantly, these pores act as a physical barrier, providing a buffer for fragile microbial cells during the initial stages of mixing and material hardening, reducing direct damage from mechanical stress and chemical impact. This feature, combined with the protective functions of the core and shell, forms a synergistic defense system: the shell resists macroscopic environmental erosion, while the porous structure of the core optimizes the microscopic survival environment, jointly ensuring that the remediation unit remains dormant and stable before triggering.

[0031] The porous carrier is at least one of expanded perlite, zeolite, and diatomite.

[0032] The microbial agent is a composite microbial community of Bacillus mycosis fungoides and Bacillus cereus. Bacillus mycosis fungoides exhibits significant metabolic stability in alkaline environments, while Bacillus cereus has a strong ability to maintain its activity at low temperatures. The actual working conditions of water conservancy projects precisely involve the complex challenges of both high alkalinity and low temperatures, making it difficult for any single microbial species to work effectively under such dual pressures. The core function of this composite strategy is to construct a more environmentally adaptable and robust microbial remediation system through functional complementarity, thereby ensuring that the self-healing function can be reliably activated and complete the repair task in different scenarios, such as the high alkalinity environment of concrete pores or the low-temperature waters deep within reservoirs.

[0033] The ratio of viable Bacillus mycosis fungoides to Bacillus cereus in the compound microbial community is 2-5:1. At this ratio, the numerically dominant Bacillus mycosis fungoides effectively dominates and maintains metabolic activity in an alkaline environment, while an appropriate proportion of Bacillus cereus serves as a crucial functional supplement, ensuring that the repair function is not interrupted when the temperature drops sharply. Neither one will inhibit the efficacy of the other due to excessive proliferation, nor will an imbalance in the ratio lead to functional failure under specific environmental stresses. Thus, together they constitute a more robust microbial remediation system under changing operating conditions.

[0034] The nutrient source is a complex of calcium lactate and urea, wherein the mass ratio of calcium lactate to urea in the complex is 1:3~7.

[0035] Urea is the core substrate for urease-driven mineralization reactions, while the introduction of calcium lactate plays a dual role: its decomposition product, lactate, serves as an auxiliary carbon source for microorganisms, promoting cell proliferation to maintain long-term repair potential; simultaneously, calcium ions directly serve as an essential raw material for the formation of calcium carbonate precipitate. Therefore, this composite nutrient source constructs a synergistic system that simultaneously supports microbial survival and mineralization product formation.

[0036] If the urea ratio is too low, the esterification reaction will be insufficient in power, and the repair process will be slow. If the urea ratio is too high, the local pH may rise too quickly or ammonia accumulation may inhibit microbial activity. The specific mass ratio range of 1:3~7 is an ideal balance point, which ensures that the microorganisms can quickly obtain balanced "energy" and "building materials" after the capsule shell dissolves, thereby starting rapid and continuous mineralization deposition and effectively filling cracks.

[0037] The shell is a geopolymer layer or an organic-inorganic composite gel layer.

[0038] The application selects a geopolymer layer or an organic-inorganic composite gel layer as the capsule shell, which is a key material guarantee for realizing the core function of intelligent triggering and long-term protection. Both of these materials can form a stable solid barrier in a dry state, effectively isolating the high-alkali environment generated by cement hydration during construction from the internal microorganisms, and ensuring the survival rate of the repair unit. More importantly, their dissolution characteristics are closely related to the water environment. When cracks occur in underground engineering and are accompanied by water intrusion, the shell can undergo controllable dissolution under certain water pressure or ion exchange, thereby accurately releasing the repair agent and realizing the intelligent response of "starting only when damaged, and waiting when not damaged".

[0039] The microbial self-repairing agent accounts for 1.5%~10% of the total mass of the base material.

[0040] The base material is one of a cement-based material, a polymer coating, or a clay-based material.

[0041] In actual application, the cement-based material includes C30 grade cement concrete, C40 grade sprayed concrete, C35 / P8 grade waterproof concrete; When the base material is C30 grade cement concrete, the microbial self-repairing agent accounts for 1.5% of the mass of the base material; When the base material is C40 grade sprayed concrete, the microbial self-repairing agent accounts for 2.0% of the mass of the base material; When the base material is C35 / P8 grade waterproof concrete, the microbial self-repairing agent accounts for 1.8% of the mass of the cement; The polymer coating includes a water-based polyurethane coating and an epoxy resin modified cement-based grouting material; When the base material is a water-based polyurethane coating, the microbial self-repairing agent accounts for 10% of the total mass of the base material; When the base material is an epoxy resin modified cement-based grouting material, the microbial self-repairing agent accounts for 10% of the dry powder mass of the grouting material; The clay-based material includes clay; When the base material is clay, the mass ratio of the microbial self-repairing agent to the base material is 1:20.

[0042] The mass ratio of the microbial agent, the nutrient source, and the porous carrier in the microbial self-repairing agent is 1:3-5:6-10.

[0043] The application also provides a construction method of the self-repairing civil engineering material, comprising the following steps: a1. mixing the microbial self-repairing agent with the raw material of the matrix material to prepare a composite material; a2. applying the composite material to the matrix surface of the hydraulic structure to be repaired or protected.

[0044] In step a2, after the composite material is applied to the matrix surface of the hydraulic structure, a step of curing in a humid environment is further included.

[0045] In the application, the microbial self-repairing agent comprises a microbial agent and a nutrient source, and the microbial agent is a urease-producing microorganism domesticated in a low-temperature and alkaline environment.

[0046] The method for domesticating the microbial agent in a low-temperature and alkaline environment is as follows: 1. First stage: single-factor gradient domestication (adapting to alkalinity and low temperature respectively) Alkaline resistance domestication: Start: inoculate the original strain (a mixture of Bacillus mycoides and Bacillus cereus) into a triangular flask containing a nutrient broth medium, and set the initial pH value to 9.0 (slightly higher than the ordinary environment); Process: shake culture at a suitable temperature (such as 30°C in this embodiment). When the bacterial population grows into the stable phase (usually 24-48h of culture, 36h in this embodiment), perform transfer and subculture. Transfer the bacterial solution to a new culture medium with a slightly increased pH value (such as an increase of 0.2-0.3 pH units each time) at a certain ratio (1% in this embodiment); Cycle: repeat the above subculture process to gradually increase the pH value of the culture environment from 9.0 to 11.0. In this process, bacteria that are not resistant to alkalinity are gradually eliminated, and the surviving bacteria are dominant strains with increasing alkaline resistance.

[0047] Low-temperature domestication: Start: also start from the original strain, and culture at a suitable pH (such as 7.0 in this embodiment) but a lower temperature (such as 20°C in this embodiment); Process: after the bacterial population adapts to growth, gradually reduce the culture temperature at each subculture (such as a decrease of 2-3°C in this embodiment); Cycle: repeat the subculture to gradually reduce the culture temperature from 20°C to 10°C or even lower. This process selects cold-resistant strains with high metabolic activity at low temperatures.

[0048] 2. Second stage: dual-factor complex domestication (simultaneously adapting to low temperature and high alkalinity) Starting: mix the alkali-resistant bacterial population and cold-resistant bacterial population obtained through the above single-factor domestication; Process: cultivate and subculture in a combined environment of lower temperature (e.g. 15°C in this example) and higher pH (e.g. pH=10.0 in this example); Cycle: gradually and alternately increase the pH value and decrease the temperature to approach the final target environmental conditions (e.g. pH=10.5, temperature=10°C in this example). This process is crucial, as it forces the microorganisms to evolve mechanisms to cope with both stresses simultaneously, thereby obtaining a complex engineered bacterial population that can tolerate the dual stress of "low temperature" and "high alkalinity".

[0049] 3. Domestication endpoint and preparation of microbial agent When the microbial population can stably grow in the target harsh environment (e.g. 10°C, pH=10.5 in this example) and its urease activity reaches a satisfactory level, the domestication is complete. At this time, the final domesticated bacterial population is expanded to prepare a high-concentration bacterial solution (e.g. 10 9 CFU / mL) for subsequent loading onto a porous carrier to prepare a microbial self-repairing agent.

[0050] The following examples illustrate the present application: Example 1 This example provides a self-repairing material for preventing seepage of dam concrete surface, which specifically comprises the following components: Matrix material: C30 grade cement concrete; Microbial self-repairing agent: Microbial agent: a complex bacterial population of Bacillus paramycoides and Bacillus cereus domesticated in low-temperature (10°C) and alkaline (pH=11) environments, with a live bacterial count ratio of 2:1; Nutrient source: a complex of calcium lactate and urea with a mass ratio of 1:5.

[0051] Loading and encapsulation: dissolve the above microbial agent and nutrient source in deionized water, and load them into the pores of expanded perlite (porous carrier) with a particle size of 0.5-1.0 mm using vacuum impregnation method. Subsequently, use a sodium silicate solution with a modulus of 1.8 as an activator to mix with metakaolin to form a geopolymer slurry, and form a geopolymer layer shell with a thickness of about 50 μm on the surface of the loaded perlite particles through spray coating process, to prepare core-shell structure capsules.

[0052] Mass ratio: in the microbial self-repairing agent, the mass ratio of the microbial agent, the nutrient source and the porous carrier is 1:3:6.

[0053] Construction method: the prepared microbial self-repairing agent is directly mixed into the base material at a mixing amount of 1.5% of the mass of the base material, and after being fully stirred, water is added for pouring and vibrating, and finally standard wet curing is performed. The material is applied to the impervious layer of the dam water-facing surface. When microcracks are generated in the concrete due to temperature stress and water seeps in, the capsule shell dissolves, and the released microbial agent generates calcium carbonate precipitation using the nutrient source to achieve self-repairing.

[0054] Example 2 The present embodiment provides a self-repairing polymer coating for the surface of a water delivery channel, which specifically comprises the following components: Base material: waterborne polyurethane (PU) coating; Microbial self-repairing agent: Microbial agent: a compounded microbial group of domesticated Bacillus mycoides and Bacillus cereus, with a live bacterial number ratio of 5:1; Nutrient source: a compound of calcium lactate and urea, with a mass ratio of 1:3.

[0055] Loading and packaging: the microbial agent and the nutrient source are loaded in zeolite molecular sieves (porous carrier) with a pore size of 2-5 nm. The shell is formed by an organic-inorganic composite gel layer composed of sodium alginate and silica sol, which is solidified by ion crosslinking (calcium chloride solution).

[0056] Mass ratio: in the microbial self-repairing agent, the mass ratio of the microbial agent, the nutrient source and the porous carrier is 1.5:4.5:10.

[0057] Construction method: the prepared microbial self-repairing agent is dispersed in the resin at an addition amount of 10% of the total mass of the base material (waterborne polyurethane resin), and is uniformly sprayed on the channel concrete base surface using a high-pressure airless spraying device to form a coating layer with a thickness of about 2 mm. If the coating layer is worn and cracked due to erosion during operation, the infiltrated water will activate the capsules to achieve self-repairing.

[0058] Example 3 The present embodiment provides a self-repairing material for toughening and imperviousness of the clay core of an earth-rock dam, which specifically comprises the following components: Base material: compacted clay; Microbial self-repairing agent: Microbial agent: a compounded microbial group of domesticated Bacillus mycoides and Bacillus cereus, with a live bacterial number ratio of 3.5:1 (intermediate value); Nutrient source: a compound of calcium lactate and urea, with a mass ratio of 1:7. Loading and encapsulation: The microbial agent and nutrient source are loaded in 200-mesh diatomite (porous carrier) powder. The same process as Example 1 is used to coat the geopolymer shell.

[0059] Mass ratio: In the microbial self-repairing agent, the mass ratio of the microbial agent, nutrient source, and porous carrier is 1:4:8.

[0060] Construction method: The prepared microbial self-repairing agent is uniformly mixed with the base material at a mass ratio of 1:20, layered and filled in the core wall part, and compacted. After the operation of the dam body, if cracks are generated in the core wall due to uneven settlement, seepage water will trigger the repair function of the capsule.

[0061] Example 4 This example provides a self-repairing material for tunnel lining concrete, which specifically includes the following components: Base material: C40 grade sprayed concrete; Microbial self-repairing agent: Microbial agent: a compound microbial population of domesticated Bacillus mycoides and Bacillus cereus, with a live bacterial count ratio of 4:1; Nutrient source: a compound of calcium lactate and urea, with a mass ratio of 1:5.

[0062] Loading and encapsulation: The microbial self-repairing agent and nutrient source are loaded in expanded perlite particles. The shell is an organic-inorganic composite gel layer formed by gelatin and nanoclay.

[0063] Mass ratio: In the microbial self-repairing agent, the mass ratio of the microbial agent, nutrient source, and porous carrier is 1.2:3.6:9.

[0064] Construction method: The microbial self-repairing agent is 2.0% of the mass of the base material (sprayed concrete). During the construction of sprayed concrete, the capsule is directly added to the sprayed stream through the addition device, so that it is uniformly distributed in the lining layer. This material can effectively repair concrete cracks caused by deformation or shrinkage of surrounding rock.

[0065] Example 5 This example provides a self-repairing material for waterproof concrete in the basement of a building, which specifically includes the following components: Base material: C35 / P8 grade waterproof concrete; Microbial self-repairing agent: Microbial agent: a compound microbial population of domesticated Bacillus mycoides and Bacillus cereus, with a live bacterial count ratio of 2:1; Nutrient source: a compound of calcium lactate and urea, with a mass ratio of 1:7; Loading and encapsulation: the microbial agent and the nutrient source were loaded into the zeolite carrier and encapsulated with a geopolymer layer on the outer layer according to the method in Example 1.

[0066] Mass ratio: in the microbial self-repairing agent, the mass ratio of the microbial agent, the nutrient source and the porous carrier was 1:5:10.

[0067] Construction method: the dosage of the microbial self-repairing agent accounted for 1.8% of the mass of cement in the base material (waterproof concrete). The agent was added when the materials were fed in the concrete mixing station to ensure uniform distribution. After pouring and forming, the agent was cured according to the conventional process. When the basement concrete structure appeared to have water seepage cracks, the agent could automatically trigger the repair process.

[0068] Example 6 This example provides a self-repairing composite material for crack grouting repair of existing hydraulic structures, which specifically comprises the following components: Base material: epoxy resin modified cement-based grouting material; Microbial self-repairing agent: Microbial agent: a compound microbial population of domesticated Bacillus mycoides and Bacillus cereus, with a live bacterial count ratio of 5:1; Nutrient source: a compound of calcium lactate and urea, with a mass ratio of 1:3.

[0069] Loading and encapsulation: the microbial agent and the nutrient source were loaded into the zeolite carrier and encapsulated with a geopolymer layer on the outer layer according to the method in Example 1.

[0070] Mass ratio: in the microbial self-repairing agent, the mass ratio of the microbial agent, the nutrient source and the porous carrier was 1.5:4.5:12.

[0071] Construction method: the microbial self-repairing agent was mixed with dry grouting material at a ratio of 10% of the mass of the base material (dry grouting material powder). During repair construction, the mixture was mixed with water and then injected into the concrete cracks through a pressure grouting machine. The cured grouting body not only fills the cracks but also has the ability to continuously repair new micro-cracks.

[0072] Comparative Example 1 The core-shell capsule structure was removed, and the domesticated microbial agent and the nutrient source used in Example 1 were directly mixed with the dry concrete material in powder form (i.e., the microbial agent, the nutrient source and the porous carrier were simply physically mixed without a geopolymer shell). The dosage was consistent with Example 1.

[0073] Comparative Example 2 The microbial agent used only a single strain, i.e., only domesticated Bacillus mycoides (corresponding to the high alkaline environment of Example 2). The other conditions were the same as those in Example 2.

[0074] Comparative Example 3 The nutrient source was changed to single urea. The rest of the conditions were the same as in Example 3.

[0075] The self-repairing composites prepared in Examples 1-6 and Comparative Examples 1-3 were tested, and the testing methods were as follows: 1. Preparation of test pieces and pre-damage: The materials of each example and comparative example were formed into test pieces of standard size (such as concrete test pieces of 100 mm x 100 mm x 100 mm cubes, and coating materials coated on a cement mortar base), and after standard curing for 28 days, a through crack with a width of 0.3 mm was induced in the middle of the test piece using the splitting method, and the initial crack width was measured and recorded using a vernier caliper or a microscope.

[0076] 2. Self-repairing performance test: Repairing environment: the pre-damaged test piece was soaked in a saturated calcium hydroxide solution (simulating concrete pore alkali solution, pH ≈ 12.5) at 10°C for wet curing.

[0077] Evaluation of repair effect (curing for 7 days and 28 days): Surface crack width: the change in crack width was observed and recorded using a crack microscope.

[0078] Repair rate calculation: repair rate (%) = (initial crack width - crack width at a certain time) / initial crack width x 100%. When the crack is completely closed and cannot be seen, it is recorded as 100% repair.

[0079] Permeability recovery: the permeability performance of the repaired test piece was tested (referring to GB / T 50082-2009), and the permeability coefficient or impermeability grade was determined. The permeability performance of the uncracked test piece was taken as the benchmark (permeability coefficient about 10 -11 m / s), and the recovery degree was calculated.

[0080] Strength recovery rate: the compressive strength of the repaired test piece was tested, and compared with the strength of the uncracked test piece, and the strength recovery rate was calculated.

[0081] 3. Durability test Freeze-thaw cycle resistance: the repaired test piece was subjected to a rapid freeze-thaw cycle test (referring to GB / T 50082-2009), and the mass loss rate and relative dynamic elastic modulus after 100 freeze-thaw cycles were recorded.

[0082] Erosion resistance: for coating type test pieces, a water flow erosion instrument was used to erode for a certain time under a flow rate of 5 m / s, and the mass loss or thickness reduction was measured.

[0083] The specific test results are shown in Table 1 below: Table 1

[0084] From the data in Table 1 above, it can be seen that the self-repairing material technical solution of the present application exhibits comprehensive and significant performance advantages. After 28 days of maintenance, the surface crack repair rate of all examples is as high as 94% or more, and the permeability coefficient after repair is as low as 10 -12 m / s order of magnitude, completely restoring the anti-permeation barrier function of the structure, while the strength recovery rate is more than 90%, and excellent freeze-thaw durability is also exhibited.

[0085] Through a series of comparative examples, the necessity and synergistic value of each technical innovation of the present application are verified one by one. The repair function of Comparative Example 1 (without core-shell protection) is almost invalid, proving that the core-shell capsule structure is the cornerstone of the entire system to work. The effect of Comparative Example 2 (single strain) is halved, indicating that the complex bacterial population ratio is crucial for coping with complex environments. Comparative Example 3 (poor nutrition source ratio) is not completely repaired, indicating that the optimized nutrition system is the guarantee for efficient repair. The above results prove that the overall scheme of the present application, which organically integrates each technical point, produces a "1+1>2" synergistic effect, and solves the long-standing problem in the industry.

[0086] The specific embodiments described herein are merely illustrative of the spirit of the present application. Those skilled in the art to which the present application belongs can make various modifications or supplements to the described specific embodiments or replace them with similar ways, without departing from the spirit of the present application or exceeding the scope defined by the appended claims.

Claims

1. A self-healing civil engineering material, characterized in that: It includes a matrix material and a microbial self-healing agent dispersed therein. The microbial self-healing agent contains microbial agents and a nutrient source. The microbial agents are urease-producing microorganisms that have been domesticated to tolerate low temperature and alkaline environment. The microbial self-healing agent is encapsulated by a core-shell structure capsule. The outer shell of the capsule is a protective layer that can dissolve under water seepage conditions. The core of the capsule is a porous carrier. The microbial agents and nutrient source are loaded in the pores of the porous carrier.

2. The self-healing civil engineering material according to claim 1, characterized in that: The microbial agent is a compound bacterial group of Bacillus mycosis fungoides and Bacillus cereus, with a live bacteria ratio of 2 to 5:1 in the compound bacterial group.

3. The self-healing civil engineering material according to claim 1, characterized in that: The nutrient source is a complex of calcium lactate and urea, wherein the mass ratio of calcium lactate to urea in the complex is 1:3~7.

4. The self-healing civil engineering material according to claim 1, characterized in that: The porous carrier is at least one of expanded perlite, zeolite, and diatomite.

5. The self-healing civil engineering material according to claim 1, characterized in that: The outer shell is a geopolymer layer or an organic-inorganic composite gel layer.

6. The self-healing civil engineering material according to claim 1, characterized in that: The microbial self-healing agent accounts for 1.5% to 10% of the total mass of the matrix material.

7. The self-healing civil engineering material according to claim 6, characterized in that: The matrix material is one of cement-based materials, polymer coatings, or clay-based materials.

8. The self-healing civil engineering material according to claim 1, characterized in that: The mass ratio of microbial inoculant, nutrient source and porous carrier in the microbial self-healing agent is 1:3~5:6~10.

9. A construction method for a self-healing civil engineering material according to any one of claims 1 to 8, characterized in that: Includes the following steps: a1. Mix the microbial self-healing agent with the raw materials of the matrix material to prepare a composite material; a2. Applying composite materials to the surface of the hydraulic structure substrate to be repaired or protected.

10. The construction method according to claim 9, characterized in that: Step a2, after applying the composite material to the surface of the hydraulic structure substrate, also includes a step of curing in a humid environment.

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