A hydrophilic self-healing waterproofing admixture, a preparation method and application thereof

Abstract

The application relates to the technical field of building waterproof materials, and particularly discloses a hydrophilic self-healing waterproof additive, a preparation method and application thereof. The additive is composed of a microcapsule core-shell structure unit and an external compatibility regulator in a physical mixing mode. The core component comprises chromobacterium violaceum, a compound culture medium, slow-release nutrients, a compound calcium source, slow-release urea and an aluminate-gypsum composite expansion body; the shell is composed of a swelling resin which is obtained by blending polyvinyl alcohol and epoxy resin at a mass ratio of 2:1; and the external compatibility regulator is obtained by mixing nano-silicon dioxide and fly ash beads at a mass ratio of 1:3, and is distributed between the microcapsule particles in a free particle state and does not enter the microcapsule. The application realizes rapid primary plugging and long-acting secondary repair of cracks through the dual-effect synergy of an inorganic expansion repair system and a biological mineralization repair system, and solves the industry pain point that the existing additive reduces the mechanical properties of concrete.

Description

Technical Field

[0001] This invention relates to the field of building waterproofing materials technology, specifically to a hydrophilic self-healing waterproofing admixture, its preparation method, and its application. Background Technology

[0002] In the field of civil engineering, concrete is the most widely used structural material, but it has inherent defects such as low flexural and tensile strength and susceptibility to cracking. Cracks in concrete can lead to a significant decrease in its impermeability, resulting in structural leakage, steel corrosion, and other problems, which seriously affect the durability and safety of building structures.

[0003] Currently, waterproofing repair technologies for concrete cracks can be mainly divided into the following categories: 1. Cement-based penetrating crystalline materials: These materials generate crystals through chemical reactions to block pores, but their repair depth is limited, their repair effect on existing cracks is generally poor, and they cannot achieve multiple self-healing processes.

[0004] 2. External waterproof coating: This is a passive protection method. The coating will fail once it ages or is damaged. Moreover, the construction is complicated and it is difficult to repair internal cracks.

[0005] 3. Microbial-induced calcium carbonate precipitation (MICP) technology: This technology utilizes microbial mineralization to generate calcium carbonate for crack repair, offering advantages such as environmental friendliness and good compatibility between the repair product and the matrix. However, it also has significant drawbacks, specifically: (1) It is difficult to maintain the activity of microorganisms and the activation time is difficult to control precisely: the high alkalinity of concrete and changes in external temperature and humidity can easily lead to the inactivation of microorganisms. Furthermore, the activation time of microorganisms is difficult to control precisely, which can easily lead to premature mineralization or delayed activation, resulting in unreliable repair response.

[0006] (2) Single repair mechanism and poor long-term waterproof reliability: Most existing self-healing materials adopt a single repair mechanism (such as pure microbial mineralization or pure inorganic expansion). Pure microbial repair has a slow response and cannot stop water quickly; pure inorganic expansion materials (such as sulfoaluminates) generate crystals with low strength and weak bonding with the matrix, which are prone to cracking again under stress. Moreover, they are mostly one-time repairs, and the repair layer cannot self-heal again after cracking, resulting in insufficient long-term waterproof reliability.

[0007] (3) Poor compatibility with concrete matrix, which easily reduces mechanical properties: Many admixtures or repair products are not compatible with the physical and chemical properties of concrete matrix, resulting in weak bonding between the repair layer and the matrix, and easy peeling. More seriously, the introduction of some admixtures will interfere with cement hydration and reduce the compressive and flexural mechanical properties of concrete, forming the contradiction of "repair is weakening".

[0008] (4) High production costs and complex processes: Some technologies rely on complex microcapsule encapsulation processes (such as those requiring high temperature and high pressure) or expensive bioactive materials, resulting in high production costs and hindering large-scale engineering applications.

[0009] In summary, there is an urgent need for a self-healing waterproofing admixture that can simultaneously solve the aforementioned technical problems. Summary of the Invention

[0010] To address the shortcomings of existing technologies, this invention provides a hydrophilic self-healing waterproof admixture, its preparation method, and its application. This admixture not only uses readily available raw materials, has a simple process, and controllable costs, making it suitable for large-scale production without altering existing construction techniques, but also possesses multiple self-healing capabilities. It can achieve rapid initial sealing of cracks and long-term secondary repair, solving industry pain points in existing technologies such as uncontrollable microbial activation timing, slow response speed, poor compatibility between admixtures and concrete, and easy reduction of mechanical properties.

[0011] This invention is achieved through the following technical solution: A hydrophilic self-healing waterproof admixture is provided, comprising two parts: a microcapsule core-wall structural unit and an externally incorporated compatibility adjustment unit, which coexist in a physically mixed manner. (a) The microcapsule core-wall structural unit includes: Core components: Composed of 20-50 parts by weight of Aureobacterium praecox, 5-8 parts by weight of compound culture medium, 25-35 parts by weight of slow-release nutrients, 3-8 parts by weight of compound calcium source, 20-40 parts by weight of slow-release urea, and 20-50 parts by weight of aluminate-gypsum composite expander. The compound calcium source is composed of calcium lactate and calcium acetate in a mass ratio of 1:1 to 2; The mass ratio of aluminate to gypsum in the aluminate-gypsum composite expander is 1:1.5 to 2.5. The sustained-release nutrients use dextran gel as the sustained-release carrier, with beef extract-peptone mixture accounting for 7% to 9% of the total mass of the sustained-release nutrients; Capsule wall component: 4-5 parts by weight of a swelling resin modified by blending polyvinyl alcohol and epoxy resin at a mass ratio of 2:1. The capsule wall maintains structural integrity in a dry state and swells and cracks to release the capsule core component when exposed to water. (b) External compatibility modifier: It is made by mixing nano-silica and fly ash microspheres at a mass ratio of 1:3, and the dosage is 1 to 3 parts by weight. The modifier is distributed in the microcapsule particles in a free particulate state and does not enter the interior of the microcapsule. Among them, slow-release nutrients, compound calcium source, slow-release urea and Aureobacterium tumefaciens together constitute the biomineralization repair system, and aluminate-gypsum composite expander constitutes the inorganic expansion repair system. The biomineralization repair system and the inorganic expansion repair system are encapsulated in the capsule wall to form a water-activated dual-effect synergistic self-healing microcapsule.

[0012] Furthermore, the modified swelling resin is prepared by mixing polyvinyl alcohol aqueous solution and epoxy resin at a mass ratio of 2:1 to prepare a resin solution with a solid content of 4% to 5%. The resin solution is then sprayed onto the surface of the core component by rotation and dried to form the core wall.

[0013] Furthermore, the composite culture medium is prepared by beef extract, peptone and water in a mass ratio of 1:1:17; in the slow-release nutrients, the beef extract-peptone mixture is pre-adsorbed and loaded into the pores of the dextran gel carrier.

[0014] Furthermore, the aluminate is any one or a combination of two of calcium sulfoaluminate aluminates or calcium aluminate cement clinker; the gypsum is selected from one or more of dihydrate gypsum, α-hemihydrate gypsum or anhydrous gypsum.

[0015] Furthermore, the average particle size of the nano-silica is 20–80 nm, and the specific surface area is ≥150 m². 2 / g; fly ash microspheres have a true density of 2.2–2.6 g / cm³. 3 Hollow microspheres with an average particle size of 0.5–10 μm.

[0016] Furthermore, *Pseudomonas aeruginosa* can be replaced with *Bacillus*, which has equivalent mineralization capabilities.

[0017] This invention also provides a method for preparing a hydrophilic self-healing waterproof additive, comprising the following steps: S1. Preparation of Aristolochic Acid Culture: Aristolochic Acid is inoculated into a composite culture medium, and the slow-release nutrients, composite calcium source and slow-release urea are added. The culture is then incubated at 34-36℃ for 20-28 hours to obtain a bacterial culture. S2. Preparation of inorganic-biological mixture: Add the aluminate-gypsum composite expansion body to the bacterial culture obtained in step S1, stir and mix evenly to obtain the mixture; S3. Preparation of capsule wall fluid: Dissolve the modified swelling resin in deionized water and stir to prepare a resin solution with a solid content of 4% to 5%. S4. Rotary coating molding: Place the mixture from step S2 in a rotary pot and rotate it at 30-40 r / min. Spray the resin solution from step S3 evenly onto the surface of the material. After spraying, continue rotating for 6-10 minutes to allow the resin solution to form a continuous coating layer on the surface of the material. S5. Drying and external blending: Dry the material coated in step S4 at 85-95℃ for 7-8 hours, then add the external compatibility regulator and mix for 2-4 minutes to obtain the hydrophilic self-healing waterproof additive. The compatibility modifier is never contained within the microcapsule wall, but is physically mixed with the microcapsule particles through external doping.

[0018] Further, in step S1, the slow-release nutrients are carried by granular or bead-shaped dextran gel, which is pre-adsorbed and loaded with beef extract-peptone mixed nutrients before being mixed with bacterial culture; in step S4, the spraying rate of the resin solution is matched with the rotation speed of the rotating pot so that the thickness of the capsule wall is controlled at 20-50 μm.

[0019] The present invention also provides a self-healing waterproof concrete, the raw material composition of which, by weight, includes: 150-270 parts of ordinary Portland cement; Fine aggregate sand 480-620 parts; 500-600 parts of coarse aggregate crushed stone; 75-135 parts water; 2-5 parts of polycarboxylate superplasticizer; 20-30 parts of hydrophilic self-healing waterproofing additive; The hydrophilic self-healing waterproof admixture is added as a dry powder during concrete mixing. After the concrete is formed and cured, when water seeps into the cracks, the modified swelling resin in the microcapsule wall swells and cracks upon contact with water, sequentially initiating: the initial sealing and repair by hydration of the aluminate-gypsum composite expansion body in the core to generate ettringite crystals, and the secondary repair by in-situ mineralization of calcite-type calcium carbonate by the Bacillus cereus-composite calcium source-slow-release urea system at the cracks. In addition, the nano silica and fly ash microspheres in the compatibility modifier are distributed in the cement stone matrix to improve the density of the interface transition zone.

[0020] Preferably, the fine aggregate is river sand, manufactured sand, or a mixture of both; the coarse aggregate is continuously graded crushed stone with a maximum particle size of ≤25mm.

[0021] The beneficial effects of this invention are: I. This invention encapsulates an aluminate-gypsum composite expandable body (inorganic expansion repair system) and an *Bacillus cereus*-composite calcium source-slow-release urea system (biomineralization repair system) within a capsule wall, forming a water-activated, dual-effect synergistic microcapsule. When water enters the crack: Initial repair: The inorganic expansion system rapidly hydrates upon contact with water to form ettringite crystals, achieving rapid sealing of cracks (response time is reduced by more than 30% compared to commercially available products), effectively preventing further water seepage; Secondary repair: If the initial repair layer cracks again due to external force, moisture and oxygen enter and awaken the white bacteria, slowly releasing nutrients for its proliferation. Through urea hydrolysis and combination with calcium ions, calcite-type calcium carbonate is generated at the crack, achieving secondary or even multiple repairs.

[0022] This dual-effect synergistic structure enables a 7-day crack area repair rate of ≥96% and a 7-day impermeability rate of ≥95%. It can effectively repair micro-cracks with a width of ≤0.3mm, and the microbial activity is maintained for more than 10 years. It has the ability to self-heal multiple times, which completely solves the industry pain points of existing single repair mechanisms being prone to failure and unable to repair multiple times.

[0023] II. This invention uses a swellable resin modified by blending polyvinyl alcohol and epoxy resin at a mass ratio of 2:1 as the capsule wall material. This capsule wall maintains structural integrity in a dry state and remains stable during concrete preparation and curing, preventing premature release of the core material. It precisely swells and cracks only when water enters the cracks, releasing the core components. The response time is significantly shorter than that of commercially available swellable resin capsule walls, truly achieving "waterless stability and immediate repair with water."

[0024] III. This invention optimizes the nutrient system of a composite calcium source (a mixture of calcium lactate and calcium acetate in a 1:1-2 ratio) and slow-release urea, and, in conjunction with the alkaline environment of concrete, guides the directional deposition of calcium carbonate, metabolized by *Bacillus cereus*, in the form of calcite at cracks. Calcite-type calcium carbonate exhibits excellent chemical compatibility with concrete hydration products (CSH gel, calcium hydroxide, etc.), enabling chemical bonding and integrated fusion between the repair layer and the substrate. The repair layer is less prone to peeling, and its mineralization strength is increased by more than 20% compared to commercially available products.

[0025] IV. In this invention, an external compatibility modifier, prepared by mixing nano-silica and fly ash microspheres at a mass ratio of 1:3, is distributed as free particles between the microcapsule particles and does not enter the interior of the microcapsules. This external doping structure brings the following unexpected technical effects: Ensuring microbial activity: The regulator does not come into direct contact with the core components, avoiding the potential inhibitory effect of the high specific surface area of ​​nano-silica and the alkaline environment on microorganisms, thus extending the microbial activity retention time to more than 10 years; Improving the density of the interface transition zone: The synergistic effect of the pozzolanic effect of nano-silica and the ball-filling effect of fly ash microspheres optimizes the microstructure of the cement stone interface transition zone and reduces the porosity. Mechanical performance enhancement: The above synergistic effect increases the compressive strength of concrete with this admixture by 5% to 8% and the flexural strength by 6% to 8% compared with blank concrete of the same mix proportion. This completely overturns the traditional perception that self-healing admixtures "repair is weakening" and achieves the reverse technical effect of "repair and enhancement".

[0026] V. The preparation method of this invention does not require harsh conditions such as high temperature and high pressure. The raw materials are all commonly used industrial raw materials, and the mass production cost is reduced by more than 15% compared with similar products on the market. It can be directly mixed into concrete without changing the existing construction process, and is suitable for various concrete mix proportions and engineering scenarios. It contains no toxic or harmful substances, and the mineralization product is environmentally friendly calcium carbonate. The repaired concrete has excellent impermeability, freeze-thaw resistance, acid and alkali resistance, and corrosion resistance. Its aging resistance is the same as the lifespan of the building, which meets the needs of green and low-carbon building development.

[0027] In summary, this invention, through its two-part architecture of "microcapsule core-capsule wall structural unit + external compatibility modifier", significantly surpasses existing technologies in multiple dimensions, including repair efficiency, response speed, repair layer bonding force, matrix mechanical properties, microbial activity retention period, production cost, and engineering applicability. Detailed Implementation

[0028] To clearly illustrate the technical features of this solution, the following detailed implementation method will be used to explain the solution.

[0029] In the following embodiments, the "external compatibility modifier" is always physically mixed with the microcapsules in a free particulate state outside the capsule and does not enter the core or wall of the microcapsule. This ensures that the modifier's modification effect on the cement stone interface transition zone and its isolation and protection of the microbial activity inside the capsule are achieved simultaneously. Unless otherwise specified, all raw materials used in the following embodiments are commercially available products.

[0030] Example 1:

[0031] (1) Preparation of hydrophilic self-healing waterproof admixture: Take 20 parts by weight of *Bacillus anguishii*, 5 parts of compound culture medium, 25 parts of slow-release nutrients, 3 parts of compound calcium source (calcium lactate: calcium acetate = 1:2), 20 parts of slow-release urea, 20 parts of aluminate-gypsum composite expander (aluminate: gypsum = 1:1.5), and 4 parts of modified swelling resin, wherein the ratio of polyvinyl alcohol (PVA): epoxy resin (EP) is 2:1, and 1 part of external compatibility modifier (nano silica: fly ash microspheres = 1:3). Prepare according to the aforementioned method.

[0032] (2) Preparation of waterproof concrete: By weight, the mixture consists of 150 parts ordinary silicate cement, 480 parts river sand, 500 parts crushed stone, 20 parts of the above-mentioned hydrophilic self-healing waterproof admixture, 2 parts polycarboxylate superplasticizer, and 75 parts water. It is then mixed, molded, and cured according to conventional processes.

[0033] (3) Performance testing: The microcracks were prefabricated using the three-point bending method. After water injection, the following tests were conducted: 75% crack area repair rate and 78% impermeability rate after 3 days; 96% crack area repair rate and 95% impermeability rate after 7 days; the compressive strength of the concrete was increased by 5% and the flexural strength by 6% compared to ordinary concrete; the repair layer was tightly bonded to the concrete substrate without peeling; the performance requirements of the economical solution in this embodiment are met, and it can satisfy the waterproofing needs of ordinary civil buildings.

[0034] Example 2:

[0035] Preparation of hydrophilic self-healing waterproof admixture: The following ingredients were prepared by weight: 35 parts of *Bacillus anthracis*, 6.5 parts of compound culture medium, 30 parts of slow-release nutrients, 5.5 parts of compound calcium source (calcium lactate: calcium acetate = 1:2), 30 parts of slow-release urea, 35 parts of aluminate-gypsum composite expander (aluminate: gypsum = 1:1.5), 4.5 parts of modified swelling resin (PVA: EP = 2:1), and 2 parts of external compatibility regulator (nano-silica: fly ash microspheres = 1:3). The preparation method was the same as in Example 1.

[0036] (2) Preparation of waterproof concrete: By weight, there are 210 parts of ordinary silicate cement, 550 parts of manufactured sand, 550 parts of crushed stone, 25 parts of hydrophilic self-healing waterproof admixture, 3.5 parts of polycarboxylate superplasticizer, and 105 parts of water. Mix, mold, and cure.

[0037] (3) Performance testing: 3-day crack repair rate of 78%, impermeability rate of 82%; 7-day crack repair rate of 98%, impermeability rate of 97%; concrete compressive strength is increased by 7% and flexural strength by 8% compared to blank concrete; it can effectively repair cracks smaller than 0.3 mm; the repair layer is completely integrated with the substrate, and the microbial activity is maintained for more than 10 years; it has the standard performance of a hydrophilic self-healing waterproof admixture and is suitable for most industrial and civil building waterproofing projects.

[0038] Example 3:

[0039] Preparation of hydrophilic self-healing waterproof admixture: Take 50 parts by weight of *Bacillus anguishii*, 8 parts of compound culture medium, 35 parts of slow-release nutrients, 8 parts of compound calcium source (calcium lactate: calcium acetate = 1:2), 40 parts of slow-release urea, 50 parts of aluminate-gypsum composite expander (aluminate: gypsum = 1:1.5), 5 parts of modified swelling resin (PVA: EP = 2:1), and 3 parts of external compatibility regulator (nano silica: fly ash microspheres = 1:3).

[0040] Waterproof concrete preparation: By weight, the composition is: 270 parts ordinary silicate cement, 620 parts mixed sand, 600 parts crushed stone, 30 parts hydrophilic self-healing waterproof admixture, 5 parts water-reducing agent, and 135 parts water.

[0041] Performance testing: 3-day crack repair rate of 80%, impermeability rate of 85%; 7-day crack repair rate of 97%, impermeability rate of 96%; concrete compressive strength is increased by 8% and flexural strength is increased by 7% compared with blank concrete; excellent freeze-thaw resistance, acid and alkali resistance, aging resistance with the same lifespan as the building, and can be repaired multiple times; suitable for high-standard waterproofing projects (such as tunnels, bridges, underground pipe corridors, etc.).

[0042] Comparative example: Using the same concrete mix proportions as in Example 2, the hydrophilic self-healing waterproofing admixture was replaced with an equal amount of commercially available conventional microbial self-healing waterproofing admixture (Jiangsu A Company microbial self-repairing agent, whose main active ingredients are Bacillus spores and supporting nutrient components). The test results are as follows: The 3-day crack repair rate is 50%, and the impermeability rate is 55%; the 7-day crack repair rate is 75%, and the impermeability rate is 78%; the compressive strength of the concrete is 3% lower than that of the blank concrete, and the flexural strength is 2% lower; the repair layer is easy to peel off, the microbial activity is maintained for less than 3 years, and it has no ability to be repaired multiple times.

[0043] Control group: The following control experimental group was set up to demonstrate the synergistic effect of external compatibility modifiers and the necessity of optimizing the capsule wall ratio.

[0044] Control A0 (without external compatibility modifier): Except for the absence of external compatibility modifier (the amount of nano-silica and fly ash microspheres is 0), the composition of other raw materials and the preparation method are exactly the same as in Example 2.

[0045] Test results: 92% crack repair rate and 90% impermeability rate after 7 days; the compressive strength of the concrete decreased by 2% and the flexural strength decreased by 1% compared with the blank concrete; the microbial activity was maintained for about 8 years.

[0046] The results showed that the mechanical properties of concrete decreased and the repair efficiency also decreased after the removal of the external compatibility modifier, indicating that the external compatibility modifier plays an irreplaceable role in maintaining microbial activity and improving the mechanical properties of the matrix.

[0047] Control B1 (regulator incorporated into the core): In step S2, an externally added compatibility regulator (a mixture of nano-silica and fly ash microspheres at a ratio of 1:3) was added to the bacterial culture along with the aluminate-gypsum composite expander. The core was then coated using the same method, and no further external regulator was added. The rest was the same as in Example 2.

[0048] Test results: 70% crack repair rate and 68% impermeability rate after 7 days; the compressive strength of the concrete increased by 1% and the flexural strength increased by 0.5% compared with the blank concrete; the microbial activity was maintained for about 2 years.

[0049] The results showed that after the regulator was incorporated into the core, the high specific surface area of ​​the nano-silica and the alkaline environment had a significant inhibitory effect on microorganisms, resulting in a significant decrease in repair efficiency and activity retention time, and the mechanical property improvement effect was not obvious.

[0050] Control B2 (modifier incorporated into the capsule wall): The externally added compatibility modifier (a mixture of nano-silica and fly ash microspheres at a ratio of 1:3) was dispersed in the modified swelling resin solution in step S3, followed by coating, and finally no external modifier was added. The rest is the same as in Example 2.

[0051] Test results: 7-day crack repair rate 65%, impermeability rate 62%; concrete compressive strength increased by 0.5% compared to blank concrete, flexural strength decreased by 0.5%; microbial activity was maintained for approximately 1.5 years.

[0052] The results showed that after the regulator was incorporated into the capsule wall, it not only inhibited microbial activity, but also disrupted the continuity and swelling and cracking properties of the capsule wall, leading to a deterioration in the repair effect.

[0053] Control C1 (inorganic expansion repair system only, no live bacteria): All of the following were replaced with equal amounts of inert quartz powder: Bacillus cereus, compound culture medium, slow-release nutrients, compound calcium source, and slow-release urea. The remaining raw materials and preparation methods were exactly the same as in Example 2.

[0054] Test results: 7-day crack repair rate was 60%, and impermeability rate was 55%; the concrete compressive strength was 3% higher than that of blank concrete; the first crack sealing was relatively fast (about 2 hours), but it could not be repaired again after secondary cracking.

[0055] The results show that, although the inorganic expansion system alone can quickly seal the blockage, it cannot achieve multiple self-healing processes.

[0056] Control C2 (Biomineralization remediation system only, without aluminate-gypsum composite expander): The aluminate-gypsum composite expander was replaced with an equal amount of inert quartz powder, and the remaining raw materials and preparation methods were exactly the same as in Example 2.

[0057] Test results: 7-day crack repair rate of 80%, impermeability rate of 78%; concrete compressive strength increased by 6% compared with blank concrete; initial crack sealing was slow (about 12 hours), and secondary cracking could be repaired, but the repair efficiency was lower than that of Example 2.

[0058] The results show that although multiple repairs can be achieved with only the biomineralization system, the initial sealing speed is significantly insufficient and cannot meet the requirements for rapid water stoppage in engineering projects.

[0059] Capsule wall ratio optimization experiment To verify the superiority of a polyvinyl alcohol to epoxy resin mass ratio of 2:1, the following three control groups were set up (all using the ratio of Example 2, only the resin ratio of the capsule wall was changed): Compare with D1 1:0 (Pure PVA) 28 3 72 -1 Example 2 2：1 5 8 98 +7 Compare with D2 1：1 2 25 88 +5 Compare with D3 0.5：1 1 >60 (Do not start) 45 +3 The results show that although the pure PVA capsule wall starts up quickly, it has a high leakage rate and is prone to premature release of the capsule core during concrete mixing. When PVA:EP=1:1, the leakage rate is low but the start-up is too slow, resulting in delayed repair. When PVA:EP=2:1, the optimal balance between leakage rate and start-up speed is achieved, and it has both good alkali stability and water responsiveness, which is the key technical feature of this invention.

[0060] Multiple self-healing cycle tests Concrete specimens from Example 2 were selected, and cracks approximately 0.2 mm wide were prefabricated using the three-point bending method. After immersion in water for 7 days, the crack repair rate (first repair) was measured. The specimens were then reloaded until the cracks reopened (approximately 0.2 mm wide), and after another 7 days of immersion in water for curing, the second repair rate was measured. This process was repeated three times. The results are as follows: 1st time 98 97 2nd time 93 91 3rd 87 85 The results show that the hydrophilic self-healing waterproof additive of the present invention has at least three self-healing capabilities, and can maintain a high repair rate and impermeability recovery rate after multiple repairs, which is significantly better than commercially available products (the comparative example lost its ability to repair again after the first repair).

[0061] Repairable crack width test Using the concrete specimens from Example 2 as the research object, cracks with widths of 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, and 0.5 mm were prefabricated. The repair effect was tested after immersion in water for 7 days. The results are as follows: 0.1 99 1.2 0.2 98 1.1 0.3 96 0.9 0.4 82 0.5 0.5 65 0.3 The results show that the hydrophilic self-healing waterproof admixture of the present invention can effectively repair cracks with a width ≤0.3mm, with a repair rate ≥96% and a post-repair impermeability pressure ≥0.9MPa; for cracks of 0.4 mm and above, the repair effect is significantly reduced, so the effective repair range of the present invention is ≤0.3mm.

[0062] Performance Comparison Summary 3D crack area repair rate 50% 78% Increased by 56% 7d crack area repair rate 75% 98% An increase of 30.7% 3d impermeability 55% 82% An increase of 49.1% 7d permeability 78% 97% An increase of 24.4% Repairable crack width ≥0.5 mm ≤0.3 mm It can repair even finer cracks Changes in concrete compressive strength down 3% Increase by 5%~8% No impairment, but rather increased efficiency Changes in flexural strength of concrete Down 2% Increase by 6%~8% Improve mechanical properties Microbial activity retention period <3 years ≥10 years Service life extended by ≥233% Multiple self-healing abilities None (expires after 1 use) ≥3 times (the repair rate is still ≥87% on the 3rd time) Long-lasting waterproof, no need for repeated repairs Of course, the above description is not limited to the examples above. Technical features not described in this invention can be implemented by or using existing technology, and will not be repeated here. The above embodiments are only used to illustrate the technical solutions of this invention and are not intended to limit this invention. This invention has been described in detail with reference to preferred embodiments. Those skilled in the art should understand that any changes, modifications, additions or substitutions made by those skilled in the art within the scope of this invention do not depart from the spirit of this invention and should also fall within the scope of protection of the claims of this invention.

Claims

1. A hydrophilic self-healing waterproof additive, characterized in that: It consists of two parts: a microcapsule core-wall structural unit and an externally doped compatibility adjustment unit, which coexist in a physically mixed manner. (a) The microcapsule core-wall structural unit includes: Core components: Composed of 20-50 parts by weight of Aureobacterium praecox, 5-8 parts by weight of compound culture medium, 25-35 parts by weight of slow-release nutrients, 3-8 parts by weight of compound calcium source, 20-40 parts by weight of slow-release urea, and 20-50 parts by weight of aluminate-gypsum composite expander. The compound calcium source is composed of calcium lactate and calcium acetate in a mass ratio of 1:1 to 2; The mass ratio of aluminate to gypsum in the aluminate-gypsum composite expander is 1:1.5 to 2.

5. The sustained-release nutrients use dextran gel as the sustained-release carrier, with beef extract-peptone mixture accounting for 7% to 9% of the total mass of the sustained-release nutrients; Capsule wall component: 4-5 parts by weight of a swelling resin modified by blending polyvinyl alcohol and epoxy resin at a mass ratio of 2:

1. The capsule wall maintains structural integrity in a dry state and swells and cracks to release the capsule core component when exposed to water. (b) External compatibility modifier: It is made by mixing nano-silica and fly ash microspheres at a mass ratio of 1:3, and the dosage is 1 to 3 parts by weight. The modifier is distributed in the microcapsule particles in a free particulate state and does not enter the interior of the microcapsule. Among them, slow-release nutrients, compound calcium source, slow-release urea and Aureobacterium tumefaciens together constitute the biomineralization repair system, and aluminate-gypsum composite expander constitutes the inorganic expansion repair system. The biomineralization repair system and the inorganic expansion repair system are encapsulated in the capsule wall to form a water-activated dual-effect synergistic self-healing microcapsule.

2. The hydrophilic self-healing waterproof additive according to claim 1, characterized in that: The modified swelling resin is prepared by mixing polyvinyl alcohol aqueous solution and epoxy resin at a mass ratio of 2:1 to prepare a resin solution with a solid content of 4% to 5%. The resin solution is then sprayed onto the surface of the core component by rotation and dried to form the core wall.

3. The hydrophilic self-healing waterproof additive according to claim 1, characterized in that: The composite culture medium was prepared by mixing beef extract, peptone, and water in a mass ratio of 1:1:17; in the slow-release nutrients, the beef extract-peptone mixture was pre-adsorbed and loaded into the pores of the dextran gel carrier.

4. The hydrophilic self-healing waterproof additive according to claim 1, characterized in that: Aluminates are any one or a combination of two of calcium sulfoaluminate aluminates or calcium aluminate cement clinker; gypsum is selected from one or more of dihydrate gypsum, α-hemihydrate gypsum or anhydrous gypsum.

5. The hydrophilic self-healing waterproofing additive according to claim 1, characterized in that: The average particle size of nano-silica is 20–80 nm, and the specific surface area is ≥150 m². 2 / g; fly ash microspheres have a true density of 2.2–2.6 g / cm³. 3 Hollow microspheres with an average particle size of 0.5–10 μm.

6. The hydrophilic self-healing waterproof additive according to claim 1, characterized in that: Paleobacterium can be replaced with Bacillus, which has the same mineralization capacity.

7. A method for preparing a hydrophilic self-healing waterproof admixture according to any one of claims 1 to 6, characterized in that: Includes the following steps: S1. Preparation of Aristolochic Acid Culture: Aristolochic Acid is inoculated into a composite culture medium, and the slow-release nutrients, composite calcium source and slow-release urea are added. The culture is then incubated at 34-36℃ for 20-28 hours to obtain a bacterial culture. S2. Preparation of inorganic-biological mixture: Add the aluminate-gypsum composite expansion body to the bacterial culture obtained in step S1, stir and mix evenly to obtain the mixture; S3. Preparation of capsule wall fluid: Dissolve the modified swelling resin in deionized water and stir to prepare a resin solution with a solid content of 4% to 5%. S4. Rotary coating molding: Place the mixture from step S2 in a rotary pot and rotate it at 30-40 r / min. Spray the resin solution from step S3 evenly onto the surface of the material. After spraying, continue to rotate for 6-10 minutes to form a continuous coating layer on the surface of the material with the resin solution. S5. Drying and external blending: Dry the material coated in step S4 at 85-95℃ for 7-8 hours, then add the external compatibility regulator and mix for 2-4 minutes to obtain the hydrophilic self-healing waterproof additive. The compatibility modifier is never contained within the microcapsule wall, but is physically mixed with the microcapsule particles through external doping.

8. The preparation method according to claim 7, characterized in that, In step S1, the slow-release nutrients are carried by granular or bead-shaped dextran gel, which is pre-adsorbed and loaded with beef extract-peptone mixed nutrients before being mixed with bacterial culture. In step S4, the spraying rate of the resin solution is matched with the rotation speed of the rotating pot to control the thickness of the capsule wall at 20-50 μm.

9. A self-healing waterproof concrete, characterized in that, The raw material composition, by weight, includes: 150-270 parts of ordinary Portland cement; Fine aggregate sand 480-620 parts; 500-600 parts of coarse aggregate crushed stone; 75-135 parts water; 2-5 parts of polycarboxylate superplasticizer; 20-30 parts of hydrophilic self-healing waterproofing additive; The hydrophilic self-healing waterproof admixture is added as a dry powder during concrete mixing. After the concrete is formed and cured, when water seeps into the cracks, the modified swelling resin in the microcapsule wall swells and cracks upon contact with water, sequentially initiating: the initial sealing and repair by hydration of the aluminate-gypsum composite expansion body in the core to generate ettringite crystals, and the secondary repair by in-situ mineralization of calcite-type calcium carbonate by the Bacillus cereus-composite calcium source-slow-release urea system at the cracks. In addition, the nano silica and fly ash microspheres in the compatibility modifier are distributed in the cement stone matrix to improve the density of the interface transition zone.

10. The self-healing waterproof concrete according to claim 9, characterized in that: Fine aggregate is river sand, manufactured sand, or a mixture of both; coarse aggregate is continuously graded crushed stone with a maximum particle size ≤25mm.