High-strength self-repairing concrete and method for preparing the same
By embedding self-healing microorganisms and nanocomposite coatings in recycled concrete and combining them with biomimetic gradient curing, the self-healing ability of recycled concrete was realized, its mechanical properties and durability were improved, and the structural defects of recycled aggregates were solved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- WUXI DACHENG CONSTRUCT CO LTD
- Filing Date
- 2025-03-27
- Publication Date
- 2026-06-02
AI Technical Summary
The recycled coarse aggregate in existing recycled concrete has high porosity, high water absorption, and high crushing index due to the hardened cement mortar adhering to its surface and internal microcracks, which limits its mechanical properties and application range.
Self-healing microorganisms such as Bacillus subtilis, Bacillus megaterium, or Bacillus pasteurellium are used to generate calcium carbonate crystals that fill cracks through a microbial induced carbonate precipitation (MICP) mechanism. The interfacial bonding between aggregates and cementitious matrix is enhanced by a composite coating of nano-magnesium sulfate fibers and silica sol. Combined with a biomimetic gradient curing strategy, concrete performance is optimized.
It significantly extends the mechanical structure and mechanical properties of concrete structures, solves the problems of high water absorption and low strength of recycled aggregates, and provides a stable porous microenvironment for microorganisms, ensuring the long-term survival and effective repair of the repair agent.
Smart Images
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Abstract
Description
Technical Field
[0001] This application relates to the field of self-healing concrete, and in particular to a high-strength self-healing concrete and its preparation method. Background Technology
[0002] The use of recycled concrete in construction engineering can solve a series of resource and environmental problems caused by construction waste, thereby promoting the green and sustainable development of construction projects. However, recycled aggregates have an additional layer of mortar adhering to the original aggregates after crushing, resulting in a complex structure, low density, high water absorption, high crushing index, and poor strength. In actual engineering, concrete structures will develop a certain amount of porosity and cracks due to their material composition and processing technology, external loads, and environmental factors. Simultaneously, under the combined action of various loads and environmental factors, actual engineering structures often suffer varying degrees of damage or cracking in the concrete. These damages or cracks can interconnect, accelerating the transport of media within the concrete and significantly impacting the durability of the concrete structure.
[0003] In response to the aforementioned existing technologies, the inventors discovered that current recycled concrete is made from construction solid waste processed through crushing, cleaning, and screening to obtain aggregates with a particle size >5mm. Compared to natural coarse aggregate, recycled coarse aggregate has more protruding edges and a rougher surface, and its surface is coated with hardened cement mortar. Furthermore, the internal structure contains numerous micro-cracks formed during the crushing process, resulting in higher porosity and water absorption rates compared to natural coarse aggregate. Compared to natural coarse aggregate, recycled coarse aggregate exhibits lower bulk density and higher crushing index due to the hardened cement mortar coating. This significantly reduces the mechanical properties of the prepared concrete material, limiting its applicability. Summary of the Invention
[0004] To address the aforementioned technical problems, this application provides a high-strength self-healing concrete and a method for preparing the same.
[0005] In the first aspect, this application provides a high-strength self-healing concrete, which adopts the following technical solution:
[0006] A high-strength self-healing concrete comprises the following substances in parts by weight:
[0007]
[0008] The recycled coarse aggregate is recycled coarse aggregate loaded with self-healing microorganisms, and the self-healing microorganisms include at least one of Bacillus subtilis, Bacillus megaterium, and Bacillus pasteurellii.
[0009] Through the above technical solution, this application endows concrete cracks with self-healing capabilities by immobilizing self-healing microorganisms (such as Bacillus subtilis, Bacillus megaterium, or Bacillus pasteurellii). These microorganisms form dormant spores inside the concrete. When cracks form and moisture seeps in, the microorganisms are activated and metabolize calcium sources (such as calcium chloride or calcium sulfate) and urea in the surrounding environment. Calcium carbonate crystals are generated through a microbial-induced carbonate precipitation (MICP) mechanism, filling the cracks and restoring structural integrity. This process requires no external intervention and can significantly extend the mechanical structure and mechanical properties of concrete structures.
[0010] Furthermore, the recycled coarse aggregate is a surface-treated recycled coarse aggregate, and the surface treatment adopts the following technical solution:
[0011] Take recycled coarse aggregate and soak it in hydrochloric acid and ultrasonically clean it. After cleaning, wash and dry it to obtain pretreated recycled coarse aggregate.
[0012] Take nano-magnesium sulfate fibers and mix them with silica sol, then disperse them by ultrasonication and collect the dispersion.
[0013] Take the dispersion and mix it with the pretreated recycled coarse aggregate in a reactor. Heat the mixture and introduce carbon dioxide to a supercritical state. After stirring and mixing, depressurize gradually and solidify in situ to obtain surface-treated recycled coarse aggregate.
[0014] Through the above technical solution, this application first removes old cement paste, organic matter and metal impurities from the surface of aggregates by soaking in hydrochloric acid and ultrasonic-assisted cleaning, exposing the original pore structure of the aggregates and providing a clean interface for subsequent coating.
[0015] Subsequently, the mixed dispersion of nano-magnesium sulfate fibers and silica sol reacts with the aggregate under supercritical carbon dioxide conditions to form a nano- to micro-scale composite coating. Supercritical carbon dioxide, with its high diffusivity and low surface tension, can penetrate into the pores of the aggregate, carrying the nanofibers and silica sol to deposit uniformly, forming a carrier structure that combines toughness and porosity.
[0016] The high specific surface area of nano-magnesium sulfate fibers and the inorganic bonding effect of silica sol significantly enhance the interfacial bonding force between aggregates and cementitious matrix, reduce weak points in the interfacial transition zone, and inhibit crack propagation. The innovation of this process lies in the synergistic physical-chemical modification, which retains the environmental advantages of recycled aggregates while solving their defects of high water absorption and low strength. At the same time, it creates a stable porous microenvironment for microbial loading, ensuring the long-term survival of the repair agent.
[0017] Furthermore, the gradient depressurization includes the following steps:
[0018] First, reduce the pressure to 15MPa at 5MPa / s and hold the pressure for 5 minutes; after the pressure holding is completed, reduce the pressure to atmospheric pressure at 10MPa / s.
[0019] Through the above technical solution, this application optimizes the internal structure of aggregates by staged depressurization. First, the pressure is reduced to 15 MPa at a rate of 5 MPa / s and held for 5 minutes. The slow release of supercritical carbon dioxide balances the internal stress of the aggregates, preventing pore collapse or microcrack propagation caused by a sudden pressure drop. During the pressure holding stage, the nanofibers and silica sol further cross-link, forming an interlocking network structure. Subsequently, the pressure is rapidly reduced to atmospheric pressure at 10 MPa / s. The pressure difference drives the supercritical carbon dioxide to escape rapidly from the aggregates, forming interconnected pores. This provides a habitat for microorganisms and ensures unobstructed channels for subsequent coating liquid penetration.
[0020] The physical principle of this process lies in achieving "directional design" of the aggregate pore structure through the dynamic control of pressure changes: the slow-descent stage ensures structural stability, while the rapid-descent stage creates high porosity. Compared with traditional hot-pressing or chemical foaming methods, gradient depressurization avoids damage to the aggregate from high temperatures or corrosive agents, while significantly increasing the specific surface area and mechanical strength of the aggregate, laying the foundation for efficient microbial loading and long-term survival.
[0021] Furthermore, the diameter of the nano-magnesium sulfate fiber is 20-50 nm, and the aspect ratio is 55-90.
[0022] Through the above technical solution, this application selects nano-magnesium sulfate fibers with a diameter of 20-50 nm and an aspect ratio of 55-90, which are uniformly dispersed in silica sol and anchored on the aggregate surface to form a "nanobrush"-like structure, enhancing the mechanical bonding between the aggregate and the cement matrix. The nano-magnesium sulfate fibers exhibit directional alignment during supercritical carbon dioxide permeation, forming a three-dimensional network by bridging aggregate pores. This not only improves the compressive strength of the aggregate but also retains sufficient interconnected pores for microbial habitation.
[0023] Furthermore, the recycled coarse aggregate immobilized with self-healing microorganisms is prepared using the following technical solution:
[0024] The lyophilized microbial powder was mixed with calcium chloride solution, the mixture was collected and added dropwise to sodium alginate solution, filtered and vacuum dried, pulverized and sieved to obtain microbial microcapsule particles;
[0025] Microbial microcapsule particles, tetraethyl orthosilicate, and dopamine were mixed and collected to obtain a mixed coating solution.
[0026] Surface-treated recycled coarse aggregate is immersed in a mixed coating solution. After immersion, ozone is introduced and polymerized in situ. The coated recycled coarse aggregate is collected and heated to densify, thus preparing the recycled coarse aggregate loaded with self-healing microorganisms.
[0027] Through the above technical solution, this application employs a microbial immobilization process to achieve efficient protection and controlled release of microorganisms via microencapsulation and double coating technology. First, freeze-dried microbial powder is mixed with calcium chloride solution and then dripped into sodium alginate solution. This process forms hydrogel microcapsules through ionic cross-linking, encapsulating the microorganisms within the core. The size design of the microcapsules ensures they are not destroyed during concrete mixing, while allowing the capsules to dissolve and release the microorganisms when water seeps into cracks.
[0028] Subsequently, tetraethyl orthosilicate hydrolyzes under alkaline conditions to form a silica gel layer, which, together with the polydopamine membrane formed by the oxidative polymerization of dopamine, constitutes a dual coating barrier: the silica layer provides rigid protection against the highly alkaline environment inside the concrete; the polydopamine membrane layer has adhesive and antioxidant properties, preventing reactive oxygen species from damaging microbial DNA. The introduction of ozone can accelerate dopamine polymerization, forming a denser coating layer.
[0029] Furthermore, the amount of the lyophilized microbial powder added to the calcium chloride solution is not less than 109 CFU / g.
[0030] Furthermore, the temperature for the heating and densification treatment is 85-120℃.
[0031] Through the above technical solution, this application employs a temperature-induced densification treatment to strengthen the coating layer structure. Within this temperature range, the silanol groups (Si-OH) generated by TEOS hydrolysis condense to form a Si-O-Si network, while the catechol groups of polydopamine undergo oxidative crosslinking. The two work synergistically to form a dense inorganic-organic hybrid layer, thereby achieving a good coating effect on recycled aggregates.
[0032] Secondly, this application provides a method for preparing high-strength self-healing concrete, employing the following technical solution:
[0033] A method for preparing high-strength self-healing concrete includes the following preparation steps:
[0034] Take cement, recycled coarse aggregate and fine aggregate, mix them and put them in a mixing device, stir and collect the mixture;
[0035] The water-reducing agent and water are injected into the mixture in three separate batches, stirred and mixed, and the resulting slurry is collected.
[0036] After the slurry is collected and poured, a biomimetic gradient curing treatment is applied to prepare high-strength self-healing concrete.
[0037] Furthermore, the biomimetic gradient maintenance treatment includes the following steps:
[0038] After sealing and curing in an environment with 90-95% humidity and 15-20℃ for 3 days, urea and calcium sulfate solution are injected for activation curing for 4-7 days. After activation curing is completed, dry and wet cycle curing is carried out for 8-28 days to complete the preparation method of the high-strength self-healing concrete.
[0039] Furthermore, the wet-dry cycle curing involves immersing the plant in water for 12 hours followed by drying for another 12 hours.
[0040] Through the above technical solution, this application optimizes concrete performance through a phased process and a biomimetic curing strategy. Injecting the water-reducing agent and water in three stages avoids slurry segregation caused by a single addition, ensuring uniform aggregate dispersion and full cement hydration. The biomimetic gradient curing simulates the self-repair process of a living organism: initial sealed curing (90-95% humidity, 15-20℃, 3 days) promotes the formation of CSH gel in the cement, establishing initial strength, while the low temperature inhibits premature microbial activation; after injecting urea and calcium sulfate solution, urea hydrolyzes to generate CO3 in an alkaline environment. 2- and NH4 + , with Ca 2+ It combines to form calcium carbonate, activating microbial mineralization activity; wet-dry cycle curing (12h immersion / 12h drying, 8-28 days) simulates the natural environment through periodic humidity changes, inducing a cycle of microcrack generation and repair, thus enhancing concrete density. The innovation of this curing strategy lies in the temporal coupling of material hydration and biorepair: in the early stage, cement strength is the primary factor, while in the later stage, microbial repair of micro-damage is relied upon, ultimately achieving a synergistic improvement in strength and durability.
[0041] In summary, this application has the following beneficial effects:
[0042] First, this application endows concrete cracks with self-healing capabilities through immobilized self-healing microorganisms (such as Bacillus subtilis, Bacillus megaterium, or Bacillus pasteurellii). These microorganisms form dormant spores inside the concrete. When cracks form and moisture seeps in, the microorganisms are activated and metabolize calcium sources (such as calcium chloride or calcium sulfate) and urea in the surrounding environment. Through the microbial-induced carbonate precipitation (MICP) mechanism, they generate calcium carbonate crystals, filling the cracks and restoring structural integrity. This process requires no external intervention and can significantly extend the mechanical structure and mechanical properties of concrete structures.
[0043] Secondly, this application first removes old cement paste, organic matter and metal impurities from the surface of the aggregate by soaking in hydrochloric acid and ultrasonic-assisted cleaning, exposing the original pore structure of the aggregate and providing a clean interface for subsequent coating.
[0044] Subsequently, the mixed dispersion of nano-magnesium sulfate fibers and silica sol reacts with the aggregate under supercritical carbon dioxide conditions to form a nano- to micro-scale composite coating. Supercritical carbon dioxide, with its high diffusivity and low surface tension, can penetrate into the pores of the aggregate, carrying the nanofibers and silica sol to deposit uniformly, forming a carrier structure that combines toughness and porosity.
[0045] The high specific surface area of nano-magnesium sulfate fibers and the inorganic bonding effect of silica sol significantly enhance the interfacial bonding force between aggregates and cementitious matrix, reduce weak points in the interfacial transition zone, and inhibit crack propagation. The innovation of this process lies in the synergistic physical-chemical modification, which retains the environmental advantages of recycled aggregates while solving their defects of high water absorption and low strength. At the same time, it creates a stable porous microenvironment for microbial loading, ensuring the long-term survival of the repair agent.
[0046] Third, this application employs a microbial immobilization process that utilizes microencapsulation and double coating technology to achieve efficient protection and controlled release of microorganisms. First, the freeze-dried microbial powder is mixed with a calcium chloride solution and then dropped into a sodium alginate solution. This process forms hydrogel microcapsules through ionic cross-linking, encapsulating the microorganisms within the core. The size design of the microcapsules ensures they are not destroyed during concrete mixing, while allowing the capsules to dissolve and release the microorganisms when water seeps into cracks.
[0047] Subsequently, tetraethyl orthosilicate hydrolyzes under alkaline conditions to form a silica gel layer, which, together with the polydopamine membrane formed by the oxidative polymerization of dopamine, constitutes a dual coating barrier: the silica layer provides rigid protection against the highly alkaline environment inside the concrete; the polydopamine membrane layer has adhesive and antioxidant properties, preventing reactive oxygen species from damaging microbial DNA. The introduction of ozone can accelerate dopamine polymerization, forming a denser coating layer. Detailed Implementation
[0048] The present application will be further described in detail below with reference to the embodiments.
[0049] Preparation Example 1
[0050] Surface-treated recycled coarse aggregate 1
[0051] Take recycled coarse aggregate and soak it in 0.5 mol / L hydrochloric acid and ultrasonically clean it for 10 min at 200 W. After cleaning, rinse it with deionized water until neutral, and then dry it at 50℃ for 12 h to collect the pretreated recycled coarse aggregate.
[0052] Take 20g of magnesium sulfate fiber with a diameter of 20nm and an aspect ratio of 55nm and mix it with 1000g of silica sol with a solid content of 10%. Disperse the mixture by ultrasonication at 200W and collect the dispersion.
[0053] The dispersion was mixed with the pretreated recycled coarse aggregate at a mass ratio of 2:1 and placed in a reactor. The mixture was heated and carbon dioxide was introduced to a supercritical state of 25 MPa. After stirring and mixing, the pressure was first reduced to 15 MPa at 5 MPa / s and then maintained for 5 min. After the pressure was maintained, the pressure was reduced to atmospheric pressure at 10 MPa / s and then circulated with hot air at 80℃ for 30 min for in-situ solidification treatment. The surface-treated recycled coarse aggregate 1 was collected.
[0054] Preparation Example 2
[0055] Surface-treated recycled coarse aggregate 2
[0056] Take recycled coarse aggregate and soak it in 0.5 mol / L hydrochloric acid and ultrasonically clean it for 10 min at 200 W. After cleaning, rinse it with deionized water until neutral, and then dry it at 50℃ for 12 h to collect the pretreated recycled coarse aggregate.
[0057] Take 35g of magnesium sulfate fiber with a diameter of 35nm and an aspect ratio of 70nm and mix it with 1250g of silica sol with a solid content of 10%. Disperse the mixture under ultrasonication at 200W and collect the dispersion.
[0058] At a mass ratio of 2:1, the dispersion was mixed with the pretreated recycled coarse aggregate and placed in a reactor. The mixture was heated and carbon dioxide was introduced to a supercritical state of 25 MPa. After stirring and mixing, the pressure was first reduced to 15 MPa at 5 MPa / s and then maintained for 5 minutes. After the pressure was maintained, the pressure was reduced to atmospheric pressure at 10 MPa / s and then instantly released. The mixture was then circulated with hot air at 80°C for 30 minutes for in-situ solidification treatment. The surface-treated recycled coarse aggregate 2 was collected.
[0059] Preparation Example 3
[0060] Surface-treated recycled coarse aggregate 3
[0061] Take recycled coarse aggregate and soak it in 0.5 mol / L hydrochloric acid and ultrasonically clean it for 10 min at 200 W. After cleaning, rinse it with deionized water until neutral, and then dry it at 50℃ for 12 h to collect the pretreated recycled coarse aggregate.
[0062] Take 50g of magnesium sulfate fiber with a diameter of 50nm and an aspect ratio of 90nm and mix it with 1500g of silica sol with a solid content of 10%. Disperse the mixture by ultrasonication at 200W and collect the dispersion.
[0063] At a mass ratio of 2:1, the dispersion was mixed with the pretreated recycled coarse aggregate and placed in a reactor. The mixture was heated and carbon dioxide was introduced to a supercritical state of 25 MPa. After stirring and mixing, the pressure was first reduced to 15 MPa at 5 MPa / s and then maintained for 5 minutes. After the pressure was maintained, the pressure was reduced to atmospheric pressure at 10 MPa / s and then instantly released. The mixture was then circulated with hot air at 80°C for 30 minutes for in-situ solidification treatment. The surface-treated recycled coarse aggregate 3 was collected.
[0064] Preparation Example 4
[0065] Regenerated coarse aggregate immobilized with self-healing microorganisms 1
[0066] The dosage of Bacillus subtilis added was 2.5 × 10⁻⁶. 9 CFU / g, take Bacillus subtilis lyophilized powder and stir and mix with 0.1mol / L calcium chloride solution, collect the mixture and add it dropwise to 3% sodium alginate solution, filter and place it in vacuum drying at 50℃, pulverize and sieve to collect microbial microcapsule particles;
[0067] Take 200g of microbial microcapsule particles, 200mL of tetraethyl orthosilicate and 400mg of dopamine, stir and mix them, and collect the mixed coating solution;
[0068] The surface-treated recycled coarse aggregate 1 is immersed in a mixed coating solution. After immersion, 5 ppm ozone is introduced and polymerized in situ. The coated recycled coarse aggregate is collected and heated to 85°C for densification treatment to obtain the recycled coarse aggregate 1 with self-healing microorganisms.
[0069] Preparation Example 5
[0070] Regenerated coarse aggregate 2 loaded with self-healing microorganisms
[0071] The dosage of Bacillus megater is 3×10. 9 CFU / g, take Bacillus megaterium lyophilized powder and stir and mix with 0.1 mol / L calcium chloride solution, collect the mixture and add it dropwise to 3% sodium alginate solution, filter and place it in vacuum dry at 50℃, pulverize and sieve to collect microbial microcapsule particles;
[0072] Take 200g of microbial microcapsule particles, 200mL of tetraethyl orthosilicate and 400mg of dopamine, stir and mix them, and collect the mixed coating solution;
[0073] The surface-treated recycled coarse aggregate 2 is immersed in a mixed coating solution. After immersion, 5 ppm ozone is introduced and polymerized in situ. The coated recycled coarse aggregate is collected and heated to 100°C for densification treatment to obtain the recycled coarse aggregate 2 loaded with self-healing microorganisms.
[0074] Preparation Example 6
[0075] Regenerated coarse aggregate 3 loaded with self-healing microorganisms
[0076] The dosage of Bacillus pasteurellium was 5 × 10⁻⁶. 9 CFU / g, take the freeze-dried powder of Bacillus pasteurellii and stir and mix it with 0.1mol / L calcium chloride solution, collect the mixture and add it dropwise to 3% sodium alginate solution, filter and place it in vacuum drying at 50℃, pulverize and sieve to collect microbial microcapsule particles;
[0077] Take 200g of microbial microcapsule particles, 200mL of tetraethyl orthosilicate and 400mg of dopamine, stir and mix them, and collect the mixed coating solution;
[0078] The surface-treated recycled coarse aggregate 3 is immersed in a mixed coating solution. After immersion, 5 ppm ozone is introduced and polymerized in situ. The coated recycled coarse aggregate is collected and heated to 120°C for densification treatment to obtain the recycled coarse aggregate 3 loaded with self-healing microorganisms.
[0079] Preparation Example 7
[0080] Regenerated coarse aggregate loaded with self-healing microorganisms 4
[0081] The amount of Bacillus subtilis added was 2.5×10⁹ CFU / g. Bacillus subtilis lyophilized powder was mixed with 0.1 mol / L calcium chloride solution. The mixture was collected and added dropwise to 3% sodium alginate solution. The mixture was filtered and vacuum dried at 50℃. The powder was then pulverized and sieved to obtain microbial microcapsule particles.
[0082] Take 200g of microbial microcapsule particles, 200mL of tetraethyl orthosilicate and 400mg of dopamine, stir and mix them, and collect the mixed coating solution;
[0083] Untreated recycled coarse aggregate is immersed in a mixed coating solution. After immersion, 5 ppm ozone is introduced and polymerized in situ. The coated recycled coarse aggregate is collected and heated to 100°C for densification treatment to obtain the recycled coarse aggregate 4 containing self-healing microorganisms.
[0084] Example
[0085] Example 1
[0086] A high-strength self-healing concrete comprises the following substances by weight: 45 kg cement, 100 kg recycled coarse aggregate loaded with self-healing microorganisms, 65 kg fine aggregate, 10 kg water, and 0.1 kg water-reducing agent.
[0087] A method for preparing high-strength self-healing concrete includes the following steps:
[0088] Take cement, recycled coarse aggregate and fine aggregate, mix them and put them in a mixing device, stir and collect the mixture;
[0089] The water-reducing agent and water are injected into the mixture in three separate batches, stirred and mixed, and the resulting slurry is collected.
[0090] After the slurry is taken and poured, it is sealed and cured for 3 days in an environment with 90% humidity and 15℃. Then, urea and calcium sulfate solution are injected for 7 days of activation curing. After activation curing is completed, dry and wet cycle curing is carried out for 28 days. The dry and wet cycle curing is carried out by immersion in water for 12 hours and then drying for 12 hours each time. After the dry and wet cycle curing is completed, high-strength self-healing concrete can be prepared.
[0091] Example 2
[0092] A high-strength self-healing concrete comprises the following substances by weight: 52 kg cement, 100-120 kg recycled coarse aggregate loaded with self-healing microorganisms, 70 kg fine aggregate, 15 kg water, and 0.2 kg water-reducing agent.
[0093] A method for preparing high-strength self-healing concrete includes the following steps:
[0094] Take cement, recycled coarse aggregate and fine aggregate, mix them and put them in a mixing device, stir and collect the mixture;
[0095] The water-reducing agent and water are injected into the mixture in three separate batches, stirred and mixed, and the resulting slurry is collected.
[0096] After the slurry is taken and poured, it is sealed and cured for 3 days in an environment with 92% humidity and 17℃. Then, urea and calcium sulfate solution are injected for 7 days of activation curing. After activation curing is completed, dry and wet cycle curing is carried out for 28 days. The dry and wet cycle curing is carried out by immersion in water for 12 hours and then drying for 12 hours each time. After the dry and wet cycle curing is completed, high-strength self-healing concrete can be prepared.
[0097] Example 3
[0098] A high-strength self-healing concrete comprises the following substances by weight: 60 kg cement, 120 kg recycled coarse aggregate loaded with self-healing microorganisms, 80 kg fine aggregate, 20 kg water, and 0.3 kg water-reducing agent.
[0099] A method for preparing high-strength self-healing concrete includes the following steps:
[0100] Take cement, recycled coarse aggregate and fine aggregate, mix them and put them in a mixing device, stir and collect the mixture;
[0101] The water-reducing agent and water are injected into the mixture in three separate batches, stirred and mixed, and the resulting slurry is collected.
[0102] After the slurry is taken and poured, it is sealed and cured for 3 days in an environment with 95% humidity and 20℃. Then, urea and calcium sulfate solution are injected for 7 days of activation curing. After activation curing is completed, dry and wet cycle curing is carried out for 28 days. The dry and wet cycle curing is carried out by immersion in water for 12 hours and then drying for 12 hours each time. After the dry and wet cycle curing is completed, high-strength self-healing concrete can be prepared.
[0103] Example 4
[0104] A high-strength self-healing concrete comprises the following substances by weight: 60 kg cement, 120 kg recycled coarse aggregate loaded with self-healing microorganisms, 80 kg fine aggregate, 20 kg water, and 0.3 kg water-reducing agent.
[0105] A method for preparing high-strength self-healing concrete includes the following steps:
[0106] Take cement, recycled coarse aggregate and fine aggregate, mix them and put them in a mixing device, stir and collect the mixture;
[0107] The water-reducing agent and water are injected into the mixture in three separate batches, stirred and mixed, and the resulting slurry is collected.
[0108] After the slurry is taken and poured, it is sealed and cured for 3 days in an environment with 95% humidity and 20℃. Then, urea and calcium sulfate solution are injected for 7 days of activation curing. After activation curing is completed, dry and wet cycle curing is carried out for 28 days. The dry and wet cycle curing is carried out by immersion in water for 12 hours and then drying for 12 hours each time. After the dry and wet cycle curing is completed, high-strength self-healing concrete can be prepared.
[0109] Example 5
[0110] A high-strength self-healing concrete comprises the following substances by weight: 60 kg cement, 120 kg recycled coarse aggregate loaded with self-healing microorganisms, 80 kg fine aggregate, 20 kg water, and 0.3 kg water-reducing agent.
[0111] A method for preparing high-strength self-healing concrete includes the following steps:
[0112] Take cement, recycled coarse aggregate and fine aggregate, mix them and put them in a mixing device, stir and collect the mixture;
[0113] The water-reducing agent and water are injected into the mixture in three separate batches, stirred and mixed, and the resulting slurry is collected.
[0114] After the slurry is taken and poured, it is sealed and cured for 3 days in an environment with 95% humidity and 20℃. Then, urea and calcium sulfate solution are injected for 7 days of activation curing. After activation curing is completed, dry and wet cycle curing is carried out for 28 days. The dry and wet cycle curing is carried out by immersion in water for 12 hours and then drying for 12 hours each time. After the dry and wet cycle curing is completed, high-strength self-healing concrete can be prepared.
[0115] Example 6
[0116] A high-strength self-healing concrete comprises the following substances by weight: 60 kg cement, 120 kg recycled coarse aggregate loaded with self-healing microorganisms, 80 kg fine aggregate, 20 kg water, and 0.3 kg water-reducing agent.
[0117] A method for preparing high-strength self-healing concrete includes the following steps:
[0118] Take cement, recycled coarse aggregate and fine aggregate, mix them and put them in a mixing device, stir and collect the mixture;
[0119] The water-reducing agent and water are injected into the mixture in three separate batches, stirred and mixed, and the resulting slurry is collected.
[0120] After the slurry is taken and poured, it is sealed and cured for 3 days in an environment with 95% humidity and 20℃. Then, urea and calcium sulfate solution are injected for 7 days of activation curing. After activation curing is completed, dry and wet cycle curing is carried out for 28 days. The dry and wet cycle curing is carried out by immersion in water for 12 hours and then drying for 12 hours each time. After the dry and wet cycle curing is completed, high-strength self-healing concrete can be prepared.
[0121] Comparative Example 1
[0122] A high-strength self-healing concrete, compared with Example 1, in which the recycled coarse aggregate is not immobilized with self-healing microorganisms, and the remaining components and steps are the same as in Example 1.
[0123] Comparative Example 2
[0124] A high-strength self-healing concrete, compared with Example 1, does not employ the biomimetic gradient curing treatment step, but all other components and steps are the same as in Example 1.
[0125] Performance testing
[0126] The compressive strength shall be tested in accordance with the relevant provisions of the "Standard for Test Methods of Long-term Performance and Durability of Ordinary Concrete" (GB / T50082-2009).
[0127] The initial crack width of the concrete materials prepared using the technical solutions of Examples 1-6 and Comparative Examples 1-2 was measured using the surface observation method. The initial crack depth of the self-healing recycled concrete with dimensions of 100mm × 100mm × 400mm after prefabrication was measured using an ultrasonic detector. The test results are shown in Tables 1 and 2 below:
[0128] Table 1 Performance Test Table
[0129]
[0130]
[0131] Table 2 Mechanical Performance Test Table
[0132]
[0133] A comparison of Examples 1-3 and Comparative Example 1 reveals that the technical solution of this application endows concrete cracks with self-healing capabilities through the immobilization of self-healing microorganisms (such as Bacillus subtilis, Bacillus megaterium, or Bacillus pasteurellii). These microorganisms form dormant spores inside the concrete. When cracks form and moisture seeps in, the microorganisms are activated and metabolize calcium sources (such as calcium chloride or calcium sulfate) and urea in the surrounding environment. Calcium carbonate crystals are generated through a microbial-induced carbonate precipitation (MICP) mechanism, filling the cracks and restoring structural integrity. This process requires no external intervention and can significantly extend the mechanical structure and mechanical properties of concrete structures.
[0134] Further comparison with Examples 1-3 and 4-6 illustrates that the technical solution of this application employs a microbial immobilization process to achieve efficient protection and controllable release of microorganisms through microencapsulation and double coating technology. First, lyophilized microbial powder is mixed with calcium chloride solution and then dripped into sodium alginate solution. This process forms hydrogel microcapsules through ionic cross-linking, encapsulating the microorganisms within the core. The size design of the microcapsules ensures they are not destroyed during concrete mixing, while allowing them to dissolve and release the microorganisms when water seeps into cracks. Subsequently, tetraethyl orthosilicate hydrolyzes under alkaline conditions to generate a silica gel layer, which, together with the polydopamine membrane formed by the oxidative polymerization of dopamine, constitutes a double coating barrier: the silica layer provides rigid protection against the high-alkaline environment inside the concrete; the polydopamine membrane layer has adhesive and antioxidant properties, preventing reactive oxygen species from damaging the microbial DNA. The introduction of ozone accelerates dopamine polymerization, forming a denser coating layer.
[0135] Finally, by comparing Example 1 and Comparative Example 2, it is explained that the technical solution of this application simulates the self-repair process of a living organism through biomimetic gradient curing: initial sealed curing (humidity 90-95%, 15-20℃, 3 days) promotes the formation of CSH gel in cement, forming initial strength, while low temperature inhibits premature activation of microorganisms; after the injection of urea and calcium sulfate solution, urea hydrolyzes to generate CO3 in an alkaline environment. 2- and NH4 + , with Ca 2+ It combines to form calcium carbonate, activating microbial mineralization activity; wet-dry cycle curing (immersion in water for 12 hours / drying for 12 hours, 8-28 days) simulates the natural environment through periodic humidity changes, inducing a cycle of microcrack generation and repair, and strengthening the density of concrete.
[0136] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.
Claims
1. A high-strength self-healing concrete, characterized in that, Includes the following substances by weight: 45-60 parts cement; 100-120 parts recycled coarse aggregate; 65-80 parts fine aggregate; 10-20 parts water; Water-reducing agent: 0.1-0.3 parts; The recycled coarse aggregate is recycled coarse aggregate loaded with self-healing microorganisms, including at least one of Bacillus subtilis, Bacillus megaterium, and Bacillus pasteurellii; the recycled coarse aggregate is surface-treated recycled coarse aggregate, and the surface treatment adopts the following technical solution: Take recycled coarse aggregate and soak it in hydrochloric acid and ultrasonically clean it. After cleaning, wash and dry it to obtain pretreated recycled coarse aggregate. Take nano-magnesium sulfate fibers and mix them with silica sol, then disperse them by ultrasonication and collect the dispersion. Take the dispersion and mix it with the pretreated recycled coarse aggregate in a reactor. Heat the mixture and introduce carbon dioxide to the supercritical state. After stirring and mixing, depressurize gradually and solidify in situ to obtain surface-treated recycled coarse aggregate. The recycled coarse aggregate loaded with self-healing microorganisms is made using the following technical solution: The lyophilized microbial powder was mixed with calcium chloride solution, the mixture was collected and added dropwise to sodium alginate solution, filtered and vacuum dried, pulverized and sieved to obtain microbial microcapsule particles; Microbial microcapsule particles, tetraethyl orthosilicate, and dopamine were mixed and collected to obtain a mixed coating solution. Surface-treated recycled coarse aggregate is immersed in a mixed coating solution. After immersion, ozone is introduced and polymerized in situ. The coated recycled coarse aggregate is collected and heated to densify, thus preparing the recycled coarse aggregate with self-healing microorganisms. The gradient decompression includes the following steps: First, reduce the pressure to 15MPa at 5MPa / s and hold the pressure for 5 minutes; after holding the pressure, reduce the pressure to atmospheric pressure at 10MPa / s. The high-strength self-healing concrete requires biomimetic gradient curing treatment, which includes the following steps: After sealing and curing in an environment with humidity of 90-95% and temperature of 15-20°C for 3 days, urea and calcium sulfate solution are injected for activation curing for 4-7 days. After activation curing is completed, dry and wet cycle curing is carried out for 8-28 days to complete the preparation method of the high-strength self-healing concrete.
2. The high-strength self-healing concrete according to claim 1, characterized in that, The nano-magnesium sulfate fibers have a diameter of 20-50 nm and an aspect ratio of 55-90.
3. The high-strength self-healing concrete according to claim 1, characterized in that, The amount of the lyophilized microbial powder added to the calcium chloride solution is not less than 10%. 9 CFU / g.
4. The high-strength self-healing concrete according to claim 1, characterized in that, The temperature for the heating and densification treatment is 85-120℃.
5. A method for preparing high-strength self-healing concrete according to any one of claims 1-3, characterized in that, The preparation steps include the following: Take cement, recycled coarse aggregate and fine aggregate, mix them and put them in a mixing device, stir and collect the mixture; The water-reducing agent and water are injected into the mixture in three separate batches, stirred and mixed, and the resulting slurry is collected. After the slurry is collected and poured, a biomimetic gradient curing treatment is applied to prepare high-strength self-healing concrete.
6. The method for preparing high-strength self-healing concrete according to claim 4, characterized in that, The dry-wet cycle curing process involves immersing the plant in water for 12 hours followed by drying for another 12 hours.