Cooperative construction method of cement concrete crack self-repairing microcapsule system

Abstract

The invention provides a collaborative construction method of a cement concrete crack self-repairing microcapsule system, which comprises the following steps of: pre-positioning a fragile area through finite element analysis or an engineering database, and constructing a static magnetic field source matrix in gradient distribution on the surface of a reinforcing steel bar; during pouring, an electromagnetic field system is activated, magnetic epoxy resin / curing agent microcapsules are synchronously fed in batches, and the magnetic powder gradient distribution design ensures that tracks of two components coincide; a high-shear-resistance microcrystalline capsule wall is formed through a perfluorotributylamine quenching process, and pumping vibration damage is resisted; the crack friction temperature rise triggers paraffin phase change to weaken the capsule wall, weak shear stress is superposed to directionally crack, and the two-component repairing agent is contacted and polymerized to form in-situ sealing; the embedded sensor and the optical fiber strain gauges form a monitoring network to capture crack signals in real time and trigger repair. Millisecond-level synchronization of crack expansion and repair is realized by adopting a heat-force double-trigger mechanism; the quenching reinforced capsule wall ensures zero damage, long-term stability in the construction period; the service life of the concrete structure is remarkably prolonged through the whole-process collaborative technology.

Description

Technical Field

[0001] This invention relates to the field of intelligent building materials and concrete structure repair technology, and in particular to a collaborative construction method for a self-healing microcapsule system for cement concrete cracks. Background Technology

[0002] Cement concrete is widely used in infrastructure, but its inherent properties and service environment make it prone to cracking. Construction defects, as well as the effects of temperature, humidity, load, and chemical corrosion, can cause cracks to initiate and propagate, allowing moisture and chloride ions to penetrate, accelerating steel corrosion and material deterioration, reducing structural load-bearing capacity and durability. Over 80% of concrete structures have cracks, resulting in high maintenance costs. Traditional repair methods can only treat surface cracks, and grouting methods are complex, costly, and passive, failing to meet current needs. Self-healing microcapsule systems are a research hotspot, but their poor compatibility with the matrix, the need for optimization of the repair agent mechanism, and the lack of supporting construction processes limit their application. Therefore, the development of related systems and processes is of great significance. Summary of the Invention

[0003] The purpose of this invention is to provide a synergistic construction method for a self-healing microcapsule system for cement concrete cracks, in order to solve the core problems of low microcapsule triggering reliability, weak targeting migration ability, failure of dual-component synergy, and easy damage during construction in the prior art.

[0004] To achieve the aforementioned technical features, the present invention aims to: simulate service load stress cloud maps using finite element software, or mark typical crack paths using an engineering database to accurately locate crack-prone areas; electrochemically deposit a nickel-based magnetic layer on the surface of the reinforcing steel in the located area, or bond neodymium iron boron permanent magnet sheets with gradient spacing matching the crack propagation mode to form a static magnetic field source matrix; before pouring, densely distribute piezoresistive sensors along the reinforcing steel in the stress concentration area, and after curing, attach fiber optic strain gauges to the surface to capture crack signals in real time and eliminate temperature drift; activate the electromagnetic field system, first lay a portion of the concrete mix, simultaneously add magnetic bicomponent microcapsules with walls strengthened by perfluorotributylamine quenching, and then cover with the remaining mix; during low-speed stirring, the magnetic powder gradient distribution capsules undergo controlled directional migration; when cracks occur, the frictional temperature rises to 50–65℃, and the paraffin phase transformation weakens the capsule walls; superimposed weak shear stress triggers directional fracture, and the bicomponent repair agent overflows and polymerizes in contact, forming a sealing barrier in situ.

[0005] A collaborative construction method for a self-healing microcapsule system for cement concrete cracks includes the following steps: Step 1: Pre-locate the concentrated and crack-prone areas of the concrete component through finite element analysis or engineering database. Step 2: Construct a gradient-distributed static magnetic field source matrix on the surface of the reinforcing steel; Step 3: During construction, before pouring concrete, pressure sensors are densely distributed along the axial direction of the reinforcing bars in the stress concentration area to collect real-time fluctuations in the compressive stress inside the concrete. Step 4: Immediately activate the electromagnetic field system during the concrete pouring stage to generate a dynamically controlled magnetic field that works in synergy with the static magnetic field source matrix; add magnetic epoxy resin / curing agent microcapsules in stages, and design the magnetic powder gradient distribution to ensure that the trajectories of the two components overlap. Step 5: After the concrete curing is completed, the microcapsules are tightly wrapped by the solidified concrete matrix and firmly fixed in their final positioning position. Step 6: The embedded sensor and fiber optic strain gauge form a monitoring network to capture crack signals in real time and trigger repair.

[0006] Preferably, the specific method of step 1 is as follows: a three-dimensional mechanical model of the concrete component is established using finite element analysis software to simulate the stress distribution cloud map under service load and accurately identify the area of ​​maximum principal stress concentration; or, by combining historical engineering databases and construction experience, typical crack paths are marked as crack-prone areas. The specific method of step 2 is as follows: When arranging steel bars in a concrete structure, a nickel-based magnetic layer is plated on the surface of the steel bars in the easily cracked areas, or neodymium iron boron permanent magnet sheets are bonded to the surface of the steel bars with high-temperature resistant epoxy adhesive. The spacing and arrangement are designed in a gradient according to the easily cracked areas and crack propagation patterns to form a static magnetic field source matrix with spatial magnetic field distribution.

[0007] Preferably, step 4 is specifically implemented as follows: First, a portion of the concrete mix is ​​laid out, and magnetic epoxy resin microcapsules and magnetic curing agent microcapsules are simultaneously added in stages. A synergistic magnetic field is used to apply directional magnetic force to the magnetic microcapsules, driving them to migrate and accumulate towards the pre-set static magnetic field source matrix on the surface of the reinforcing steel. Then, the remaining mix is ​​covered, and a regulating magnetic field is continuously applied before the concrete initially sets to ensure that the microcapsules are ultimately stably positioned near the target crack-prone area. The mixing process is kept at a low speed to prevent significant displacement of the positioned microcapsules. In step 5, fiber optic strain gauges are attached to the weak areas of the component surface, temperature drift is eliminated by statically determinate sensor decoupling algorithm, and data is wirelessly transmitted to the cloud platform analysis system. The specific method of step 6 is as follows: When a concrete crack occurs in a preset crack-prone area, the monitoring system captures the crack signal in real time and transmits it to the control terminal. The mechanical stress generated by the relative movement between the crack surfaces acts on the microcapsules located at this location. The friction of the crack surface heats up to the critical point of paraffin phase transformation, and at the same time, the paraffin capsule wall structure of the microcapsule weakens, triggering directional rupture. After the two-component repair agent overflows, it permeates and flows along the crack. Upon contact, it triggers a polymerization reaction. The repair body solidifies in situ within the crack to form a sealing barrier. The integrity of the repair body is evaluated through periodic non-destructive testing.

[0008] Preferably, a pre-embedded electrically controlled microcapsule delivery system is added, the steps of which include: a. During the concrete pouring stage, double-layer flexible insulated pipes are pre-embedded in key crack-prone areas, with modular electromagnets wrapped around their outer walls; b. The outer cavity is filled with a sodium chloride conductive solution and connected to the negative terminal of the power supply; the inner cavity stores magnetic repair microcapsules, and the inner wall is equipped with a porous conductive metal filter membrane and connected to the positive terminal of the power supply. c. When concrete cracks and squeezes the pipe, the conductive solution seeps through the porous conductive metal filter membrane to connect the circuit; the current activates the modular electromagnet to generate a directional magnetic field, driving the inner microcapsules to migrate to the crack; d. The current flowing through the solution generates Joule heat, melting the paraffin walls of the microcapsules and causing them to rupture under mechanical stress at their migration endpoint; the two-component repair agent penetrates deep into the crack, polymerizes and solidifies, forming a supplementary repair.

[0009] Preferably, the magnetic epoxy resin microcapsules are composed of paraffin wax, petroleum resin, magnetic powder, and waterborne epoxy resin, with each component in parts by weight as follows: 30-55 parts paraffin wax, 5-10 parts petroleum resin, 45-65 parts waterborne epoxy resin, and 20-55 parts magnetic powder. The curing agent microcapsules are composed of paraffin wax, petroleum resin, magnetic powder, and a curing agent, with each component in parts by weight as follows: 35-60 parts paraffin wax, 5-10 parts petroleum resin, 45-60 parts curing agent, and 20-55 parts magnetic powder. By adjusting the type, mass ratio, and particle size distribution of magnetic powder in the two-component microcapsules, their magnetic susceptibility and overall density are matched, ensuring that they are subjected to the same magnetic force and have overlapping motion trajectories in the crack gradient magnetic field, thus achieving synchronous migration to the crack tip.

[0010] Preferably, the paraffin capsule wall of the microcapsule is constructed by blending C9 petroleum resin with paraffin wax with a melting point of 50-65℃; By preferentially mixing magnetic powder with molten paraffin / petroleum resin, most of the magnetic powder is encapsulated in the outer layer of the capsule wall, forming a magnetic powder gradient distribution structure with "high on the outside and low on the inside".

[0011] Preferably, the low specific heat capacity of perfluorotributylamine is used as the core control method for microcapsule solidification. When the high-temperature molten capsule wall mixture is injected with low-temperature perfluorotributylamine, its extremely low heat capacity causes the capsule wall material to be violently de-heated within milliseconds, triggering the non-equilibrium solidification of paraffin / petroleum resin. This transient phase change forces the molecules to arrange themselves in a disordered manner, forming a highly dense microcrystalline structure capsule wall.

[0012] Preferably, a static magnetic field source matrix is ​​constructed by pre-applying a nickel-based magnetic layer on the surface of the reinforcing steel in the crack-prone area. When the external electromagnetic field is activated, the pre-applied layer generates a strong magnetic coupling effect with the electromagnetic field, forming a local magnetic field intensity multiplication zone at the crack tip, which generates a super strong capture force for the migrating magnetic microcapsules, thereby achieving precise targeted enrichment of deep cracks.

[0013] Preferably, the preparation process of the magnetic epoxy resin microcapsules is as follows: a. Weigh out the paraffin wax, petroleum resin, magnetic powder, and water-based epoxy resin according to the required weight proportions for each component; b. Mix paraffin wax with perfluorotributylamine, and heat to melt and disperse the paraffin wax in the perfluorotributylamine solution to obtain a paraffin wax / perfluorotributylamine mixture; c. Heat the petroleum resin to 130-140°C and stir at 400-600 rpm for 20-30 minutes. Add the paraffin / perfluorotributylamine mixture prepared above, control the temperature at 80-90°C, and stir for 10-20 minutes to obtain a paraffin / perfluorotributylamine / petroleum resin mixture. Then add magnetic powder, control the temperature at 70-80°C, and stir for 30-60 minutes to obtain a paraffin / perfluorotributylamine / petroleum resin / magnetic powder mixture. Finally, add waterborne epoxy resin, control the temperature at 70-80°C, and stir for 1-2 hours. d. Stop heating; increase the stirring speed to 900~1200 rpm, add perfluorotributylamine solution, and rapidly reduce the temperature of the mixture to obtain a suspension of thermoplastic resin-coated magnetic epoxy resin microcapsules; e. The suspension is ultrasonically dispersed, then filtered to separate the microcapsules. After drying, the microcapsules are obtained as magnetic epoxy resin microcapsules.

[0014] Preferably, the preparation process of the magnetic curing agent microcapsules is as follows: a. Weigh out the paraffin wax, petroleum resin, magnetic powder, and curing agent according to the required weight proportions of each raw material; b. Mix paraffin wax and perfluorotributylamine, and heat to melt and disperse the paraffin wax in the perfluorotributylamine solution to obtain a paraffin / perfluorotributylamine mixture; c. Heat the petroleum resin to 130-140°C and stir at 400-600 rpm for 20-30 minutes. Add the paraffin / perfluorotributylamine mixture prepared above, control the temperature at 80-90°C, and stir for 10-20 minutes to obtain a petroleum resin / paraffin / perfluorotributylamine mixture. Then add magnetic powder, maintain the temperature at 70-80°C, and stir for 30-60 minutes to obtain a paraffin / perfluorotributylamine / petroleum resin / magnetic powder mixture. Finally, add the curing agent, control the temperature at 80-90°C, and stir for 1-2 hours. d. Stop heating, increase the stirring speed to 900~1200 rpm, add perfluorotributylamine solution, and rapidly reduce the temperature of the mixture to obtain a suspension of thermoplastic resin-coated curing agent microcapsules; e. The suspension is ultrasonically dispersed, then filtered to separate the microcapsules. The microcapsules are then dried in an oven to obtain magnetic curing agent microcapsules. Preferably, magnetic epoxy resin microcapsules and magnetic curing agent microcapsules are mixed at a mass ratio of 60~70:30~40 to obtain self-healing magnetic microcapsules for cement concrete cracks.

[0015] The present invention has the following beneficial effects: 1. By precisely identifying crack-prone areas through finite element simulation and engineering experience, a gradient-distributed static magnetic field source is constructed on the surface of the reinforcing steel. This process ensures that the subsequent migration path of the microcapsules closely matches the spatial distribution of potential cracks, significantly improving the targeting of repairs. It avoids the ineffective allocation of repair resources to non-risk areas from the outset, greatly optimizing material utilization efficiency.

[0016] 2. The magnetic powder gradient encapsulation technology is used to regulate the physical properties of the two-component microcapsules, so that they are driven by the same force in the magnetic field. This completely solves the contact failure problem caused by the separation of the epoxy resin and curing agent capsules due to migration trajectory, and ensures that the repair agent is fully mixed at the crack tip and triggers the polymerization reaction, so as to achieve reliable repair of deep cracks.

[0017] 3. By utilizing the extremely low heat capacity of perfluorotributylamine to trigger transient non-equilibrium solidification of the capsule wall, a highly dense microcrystalline structure is formed, resulting in a qualitative leap in the microcapsule's resistance to mechanical damage. This completely resists the strong shearing action during the concrete pumping and vibration process, ensuring zero leakage of the repair agent during construction and long-term storage stability.

[0018] 4. The capsule wall of the specific melting point paraffin-resin blend undergoes a phase transformation and weakening under the frictional temperature rise of the crack, allowing even weak shear stresses that would normally not trigger cracking to induce directional fracture. This mechanism simultaneously avoids the risk of environmental temperature interference, achieving a precise synchronous response between crack propagation and repair agent release, significantly improving self-healing reliability.

[0019] 5. An embedded sensor network captures crack signals in real time, and the cloud platform automatically triggers a repair response. This process replaces the lag and subjectivity of traditional manual inspection, enabling immediate diagnosis and autonomous repair of hidden cracks, significantly reducing structural maintenance costs and extending service life. Attached Figure Description

[0020] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0021] Figure 1 This is a layout diagram of a dual-sensor monitoring system for concrete cracks.

[0022] Figure 2 This is a schematic diagram of the gradient magnetic powder and quenched microcrystalline capsule structure.

[0023] Figure 3 This is a targeted enrichment map of deep fractures in a static magnetic matrix and electromagnetic synergy.

[0024] Figure 4This is a schematic diagram of the structure and operation of a pre-embedded electrically controlled capsule delivery system.

[0025] In the diagram: 1. Concrete component; 2. Reinforcing bar; 3. Magnetic layer; 4. Permanent magnet sheet; 5. Pressure sensor; 6. Magnetic epoxy resin microcapsule; 7. Magnetic curing agent microcapsule; 8. Strain gauge; 9. Static determinate sensor; 10. Cloud platform analysis system; 11. Capsule wall; 12. Magnetic powder; 13. Deep crack; 14. Waterborne epoxy resin; 15. Curing agent. Detailed Implementation

[0026] The present invention will be further described in detail below through specific embodiments. These embodiments are intended to enable those skilled in the art to gain a more comprehensive understanding of the present invention, but do not limit the invention in any way.

[0027] Example 1: like Figures 1 to 4 As shown, a collaborative construction method for a self-healing microcapsule system for cement concrete cracks includes the following steps: Step 1: Use finite element analysis software to establish a three-dimensional mechanical model of the concrete component 1, simulate the stress distribution cloud map under service load, and accurately identify the area of ​​maximum principal stress concentration; or combine historical engineering databases and construction experience to mark typical crack paths.

[0028] Step 2: When arranging steel bars 2 in the concrete structure, a nickel-based magnetic layer 3 is plated on the surface of the steel bars in the easily cracked areas, or neodymium iron boron permanent magnet sheets 4 are bonded to the surface of the steel bars 2 with high-temperature resistant epoxy adhesive. The spacing and arrangement are designed in a gradient according to the easily cracked areas and crack propagation mode to form a static magnetic field source matrix with spatial magnetic field distribution. Step 3: During construction, before pouring concrete, pressure sensors 5 are densely distributed along the reinforcing bar axis in the stress concentration area to collect real-time fluctuations in compressive stress inside the concrete. Step 4: Immediately activate the electromagnetic field system during the concrete pouring stage to generate a dynamically controlled magnetic field that synergizes with the static magnetic field source matrix. First, lay a portion of the concrete mix. Then, simultaneously add magnetic epoxy resin microcapsules 6 and magnetic curing agent microcapsules 7 using a phased feeding method. Utilize the synergistic magnetic field to apply directional magnetic force to the magnetic microcapsules, driving them to migrate and accumulate towards the pre-designated static magnetic field source matrix on the steel reinforcement surface. Cover with the remaining mix, and continue applying the controlled magnetic field before the concrete initially sets to ensure the microcapsules are ultimately stably positioned near the target crack-prone area. Maintain a low mixing speed during the mixing process to prevent significant displacement of the positioned microcapsules.

[0029] Step 5: After concrete curing, the microcapsules are tightly encapsulated by the solidified concrete matrix and firmly fixed in their final positioning position, i.e., the preset crack-prone area. Fiber optic strain gauges 8 are attached to the weak areas of the component surface, and temperature drift is eliminated by a decoupling algorithm using statically determinate sensors 9. The data is wirelessly transmitted to the cloud platform analysis system 10.

[0030] Step 6: When a concrete crack occurs in a pre-defined crack-prone area, the monitoring system captures the crack signal in real time and transmits it to the control terminal. The mechanical stress generated by the relative movement between the crack surfaces acts on the microcapsules located at this location. The friction of the crack surface heats up to the critical point of paraffin phase transformation, while the structure of the capsule wall 11 weakens, triggering directional rupture. After the two-component repair agent overflows, it permeates and flows along the crack, initiating a polymerization reaction upon contact. The repair material solidifies in situ within the crack, forming a sealing barrier. The integrity of the repair material is assessed through periodic non-destructive testing.

[0031] Furthermore, to compensate for the loss of migration ability of microcapsules in concrete cracks after solidification, and to address the issue of deep or static magnetic field-covered blind spots in cracks, a pre-embedded electrically controlled capsule delivery system is added. The steps include: a. During the concrete pouring stage, double-layer flexible insulating pipes 16 are pre-embedded in key crack-prone areas, with modular electromagnets 17 wrapped around their outer walls. b. The outer cavity is filled with sodium chloride conductive solution 18 and connected to the negative terminal of the power supply 19; the inner cavity stores magnetic repair microcapsules and the inner wall is provided with a porous conductive metal filter membrane 20 and connected to the positive terminal of the power supply 21. c. When concrete cracks and squeezes the pipe, the conductive solution seeps through the porous metal filter membrane 20 to connect the circuit; the current activates the modular electromagnet 17 to generate a directional magnetic field, driving the inner microcapsules to migrate to the crack. d. The current flowing through the solution generates Joule heat, melting the paraffin capsule wall 11 of the microcapsule, causing it to rupture under mechanical stress at the migration endpoint; the two-component repair agent penetrates deep into the crack, polymerizes and solidifies, forming a supplementary repair.

[0032] Furthermore, the magnetic epoxy resin microcapsules 6 are composed of paraffin wax, petroleum resin, magnetic powder, and water-based epoxy resin, with each component in parts by weight as follows: 30-55 parts paraffin wax, 5-10 parts petroleum resin, 45-65 parts water-based epoxy resin, and 20-55 parts magnetic powder. The curing agent microcapsules 7 are composed of paraffin wax, petroleum resin, magnetic powder, and curing agent, with each component in parts by weight as follows: 35-60 parts paraffin wax, 5-10 parts petroleum resin, 45-60 parts curing agent, and 20-55 parts magnetic powder. Furthermore, the pressure sensor 5 is attached to the reinforcing steel in the concrete, and the strain gauge 8 is connected to the statically determinate sensor 9 system, which is connected to the cloud platform analysis system 10. The strain gauge 8 is attached to the weakest part of the concrete.

[0033] Furthermore, the type, mass ratio, and particle size distribution of the magnetic powder 12 in the two-component microcapsules are matched with their magnetic susceptibility and overall capsule density to ensure that they are subjected to the same magnetic force and have overlapping motion trajectories in the crack gradient magnetic field, thus achieving synchronous migration to the crack tip.

[0034] Furthermore, the C9 petroleum resin is blended with paraffin wax of a specific melting point (50-65°C) to construct the capsule wall 11. At the service temperature of concrete, the solid paraffin wax reinforces the glassy resin, ensuring the stability of the microcapsules during storage. Once a crack occurs, the local stress concentration area reaches a critical temperature due to frictional heat / temperature rise. The paraffin wax undergoes a solid-liquid phase transition, disrupting the homogeneity of the capsule wall 11 and causing a sharp increase in resin brittleness. At this time, the superimposed crack shear stress, which is much lower than the conventional strength, can trigger the instantaneous rupture of the capsule wall 11, enabling sensitive and controllable release of the repair agent and precise response to damage.

[0035] Furthermore, the magnetic powder 12 is preferentially mixed with molten paraffin / petroleum resin, so that most of the magnetic powder 12 is encapsulated in the outer layer of the capsule wall, forming a magnetic powder gradient distribution structure with a "high outer layer and low inner layer". This allows the microcapsule to generate a larger magnetic torque in the magnetic field, improving migration efficiency; at the same time, the high magnetic powder content in the outer layer causes the capsule wall 11 to preferentially bear stress concentration at the cracks, triggering directional rupture.

[0036] Furthermore, the low specific heat capacity of the perfluorotributylamine serves as a core control mechanism for microcapsule curing. When the high-temperature molten capsule wall mixture is injected with low-temperature perfluorotributylamine, its extremely low heat capacity causes the capsule wall material to undergo intense heat loss within milliseconds, triggering non-equilibrium solidification of paraffin / petroleum resin. This transient phase transition forces disordered molecular arrangement, forming a highly dense microcrystalline structure capsule wall 11, significantly improving shear resistance during construction, avoiding premature rupture caused by pumping and vibration, and ensuring the long-term stability of the microcapsules in concrete.

[0037] Furthermore, a magnetic layer 3 (such as nickel plating) is pre-placed on the surface of the reinforcing steel in the crack-prone area to construct a static magnetic field source substrate. When an external electromagnetic field is activated, the pre-placed layer generates a strong magnetic coupling effect with the electromagnetic field, forming a local magnetic field strength multiplication zone at the crack tip, which generates a super-strong trapping force for the migrating magnetic microcapsules, achieving precise targeted enrichment of deep cracks 13.

[0038] Further, the preparation of the magnetic epoxy resin microcapsules 6: a. Weigh out the required weight proportions of paraffin wax, petroleum resin, magnetic powder 12, and water-based epoxy resin 14; b. Mix paraffin wax with perfluorotributylamine, and heat to melt and disperse the paraffin wax in the perfluorotributylamine solution to obtain a paraffin wax / perfluorotributylamine mixture; c. Heat the petroleum resin to 130-140°C and stir at 400-600 rpm for 20-30 minutes. Add the paraffin / perfluorotributylamine mixture prepared above, control the temperature at 80-90°C, and stir for 10-20 minutes to obtain a paraffin / perfluorotributylamine / petroleum resin mixture. Then add magnetic powder 12, control the temperature at 70-80°C, and stir for 30-60 minutes to obtain a paraffin / perfluorotributylamine / petroleum resin / magnetic powder mixture. Finally, add waterborne epoxy resin, control the temperature at 70-80°C, and stir for 1-2 hours. d. Stop heating; increase the stirring speed to 900~1200 rpm, add perfluorotributylamine solution, and rapidly reduce the temperature of the mixture to obtain a suspension of thermoplastic resin-coated magnetic epoxy resin microcapsules; e. The suspension is subjected to ultrasonic dispersion treatment, and then the microcapsules are separated by filtration. After drying, the microcapsules are obtained as magnetic epoxy resin microcapsules 6.

[0039] Further, the preparation of magnetic curing agent microcapsules 7: a. Weigh out the paraffin wax, petroleum resin, magnetic powder 12 and curing agent 15 according to the required weight proportions of each raw material; b. Mix paraffin wax and perfluorotributylamine, and heat to melt and disperse the paraffin wax in the perfluorotributylamine solution to obtain a paraffin / perfluorotributylamine mixture; c. Heat the petroleum resin to 130-140°C and stir at 400-600 rpm for 20-30 minutes. Add the paraffin / perfluorotributylamine mixture prepared above, control the temperature at 80-90°C, and stir for 10-20 minutes to obtain a petroleum resin / paraffin / perfluorotributylamine mixture. Then add magnetic powder, maintain the temperature at 70-80°C, and stir for 30-60 minutes to obtain a paraffin / perfluorotributylamine / petroleum resin / magnetic powder mixture. Finally, add the curing agent, control the temperature at 80-90°C, and stir for 1-2 hours. d. Stop heating, increase the stirring speed to 900~1200 rpm, add perfluorotributylamine solution, and rapidly reduce the temperature of the mixture to obtain a suspension of thermoplastic resin-coated curing agent microcapsules; e. The suspension is ultrasonically dispersed, then filtered to separate the microcapsules. The microcapsules are then dried in an oven to obtain the magnetic curing agent microcapsules. Furthermore, the self-healing magnetic microcapsules for cement concrete cracks are made by mixing magnetic epoxy resin microcapsules and magnetic curing agent microcapsules at a mass ratio of 60~70:30~40.

[0040] Although the preferred embodiments of the present invention have been described above in conjunction with the accompanying drawings, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many specific modifications under the guidance of the present invention without departing from the spirit of the invention and the scope of protection of the claims, and these modifications all fall within the scope of protection of the present invention.

Claims

1. A synergistic construction method of a cement concrete crack self-repairing microcapsule system, characterized in that, Includes the following steps: Step 1: Pre-locate the concentrated and crack-prone areas of the concrete component (1) through finite element analysis or engineering database. Step 2: Construct a gradient-distributed static magnetic field source matrix on the surface of the reinforcing bar (2); Step 3: During construction, before pouring concrete, pressure sensors (5) are densely distributed along the reinforcing bar axis in the stress concentration area to collect the internal compressive stress fluctuations of the concrete in real time. Step 4: Immediately activate the electromagnetic field system during the concrete pouring stage to generate a dynamically controlled magnetic field that works in synergy with the static magnetic field source matrix; add magnetic epoxy resin / curing agent microcapsules in stages, and design the magnetic powder gradient distribution to ensure that the trajectories of the two components overlap. Step 5: After the concrete curing is completed, the microcapsules are tightly wrapped by the solidified concrete matrix and firmly fixed in their final positioning position. Step 6: The embedded sensor and fiber optic strain gauge form a monitoring network to capture crack signals in real time and trigger repair.

2. The synergistic construction method of a cement concrete crack self-repairing microcapsule system according to claim 1, characterized in that, The specific method of step 1 is as follows: use finite element analysis software to establish a three-dimensional mechanical model of concrete component (1), simulate the stress distribution cloud map under service load, and accurately identify the area of ​​maximum principal stress concentration; or combine historical engineering database and construction experience to mark typical crack paths as crack-prone areas. The specific method of step 2 is as follows: When arranging steel bars (2) in concrete structure, a nickel-based magnetic layer (3) is plated on the surface of the steel bars in the easily cracked area, or neodymium iron boron permanent magnet sheet (4) is bonded to the surface of the steel bar (2) with high temperature resistant epoxy adhesive. The spacing and arrangement are designed in a gradient according to the easily cracked area and crack propagation mode to form a static magnetic field source matrix with spatial magnetic field distribution.

3. The synergistic construction method of the self-healing microcapsule system for cement concrete cracks according to claim 2, characterized in that, The specific method of step 4 is as follows: First, a portion of the concrete mix is ​​laid, and magnetic epoxy resin microcapsules (6) and magnetic curing agent microcapsules (7) are simultaneously added in a phased feeding manner. The magnetic microcapsules are then subjected to directional magnetic force by a synergistic magnetic field, driving them to migrate and accumulate towards the preset static magnetic field source matrix on the surface of the steel reinforcement. The remaining mix is ​​then covered, and a control magnetic field is continuously applied before the concrete initially sets to ensure that the microcapsules are finally stably positioned near the target crack-prone area. The mixing process is kept at a low speed to prevent significant displacement of the positioned microcapsules. In step 5, fiber optic strain gauges (8) are attached to the weak areas on the surface of the component, temperature drift is eliminated by decoupling algorithm of statically determinate sensor (9), and data is wirelessly transmitted to cloud platform analysis system (10). The specific method of step 6 is as follows: when concrete cracks occur in the preset crack-prone area, the monitoring system captures the crack signal in real time and transmits it to the control terminal. The mechanical stress generated by the relative movement between the crack surfaces acts on the microcapsules located at this location. The friction of the crack surface heats up to the critical point of paraffin phase transformation, and at the same time, the structure of the paraffin capsule wall (11) of the microcapsule weakens, triggering directional cracking. After the two-component repair agent overflows, it permeates and flows along the crack. Upon contact, it triggers a polymerization reaction. The repair body solidifies in situ within the crack to form a sealing barrier. The integrity of the repair body is evaluated through periodic non-destructive testing.

4. The synergistic construction method of the self-healing microcapsule system for cement concrete cracks according to claim 3, characterized in that, The steps for adding a pre-embedded electrically controlled microcapsule delivery system include: a. During the concrete pouring stage, double-layer flexible insulated pipes (16) are pre-embedded in key crack-prone areas, and their outer walls are wrapped with modular electromagnets (17). b. The outer cavity is filled with sodium chloride conductive solution (18) and connected to the negative terminal of the power supply (19); the inner cavity stores magnetic repair microcapsules, and the inner wall is provided with a porous conductive metal filter membrane (20) and connected to the positive terminal of the power supply (21). c. When concrete cracks and squeezes the pipe, the conductive solution seeps through the porous conductive metal filter membrane (20) to connect the circuit; the current activates the modular electromagnet (17) to generate a directional magnetic field, driving the inner microcapsules to migrate to the crack; d. The current flowing through the solution generates Joule heat, which melts the paraffin capsule wall of the microcapsule (11), causing it to break under mechanical stress at the migration endpoint; the two-component repair agent penetrates into the deep part of the crack, polymerizes and solidifies, and forms a supplementary repair body.

5. The synergistic construction method of the self-healing microcapsule system for cement concrete cracks according to claim 3, characterized in that, The magnetic epoxy resin microcapsules (6) are composed of paraffin wax, petroleum resin, magnetic powder and waterborne epoxy resin. The components are in the following weight parts: 30-55 parts paraffin wax, 5-10 parts petroleum resin, 45-65 parts waterborne epoxy resin and 20-55 parts magnetic powder. The curing agent microcapsules (7) are composed of paraffin wax, petroleum resin, magnetic powder and curing agent. The components are in the following weight parts: 35-60 parts paraffin wax, 5-10 parts petroleum resin, 45-60 parts curing agent and 20-55 parts magnetic powder. By adjusting the type, mass ratio and particle size distribution of magnetic powder (12) in the two-component microcapsules, their magnetic susceptibility and overall density of the microcapsules are matched, ensuring that they are subjected to the same magnetic force and have the same trajectory in the crack gradient magnetic field, thus achieving synchronous migration to the crack tip.

6. The synergistic construction method of the self-healing microcapsule system for cement concrete cracks according to claim 3, characterized in that, The wall of the microcapsule paraffin capsule (11) is constructed by blending C9 petroleum resin with paraffin that has a melting point of 50-65℃; By preferentially mixing magnetic powder (12) with molten paraffin / petroleum resin, most of the magnetic powder (12) is encapsulated in the outer layer of the capsule wall, forming a magnetic powder gradient distribution structure with "high outside and low inside".

7. The synergistic construction method of the self-healing microcapsule system for cement concrete cracks according to claim 5, characterized in that, Using the low specific heat capacity of perfluorotributylamine as the core control method for microcapsule solidification, when the high-temperature molten capsule wall mixture is injected with low-temperature perfluorotributylamine, its extremely low heat capacity causes the capsule wall material to be violently de-heated within milliseconds, triggering non-equilibrium solidification of paraffin / petroleum resin. This transient phase change forces the molecules to arrange themselves in a disordered manner, forming a highly dense microcrystalline structure capsule wall (11).

8. The synergistic construction method of the self-healing microcapsule system for cement concrete cracks according to claim 3, characterized in that, By pre-installing a nickel-based magnetic layer (3) on the surface of the steel bars in the crack-prone area, a static magnetic field source matrix is ​​constructed. When the external electromagnetic field is activated, the pre-installed layer generates a strong magnetic coupling effect with the electromagnetic field, forming a local magnetic field intensity multiplication zone at the crack tip, generating a super strong capture force on the migrating magnetic microcapsules, and achieving precise targeted enrichment of deep cracks (13).

9. The synergistic construction method of the self-healing microcapsule system for cement concrete cracks according to claim 7, characterized in that, The preparation process of magnetic epoxy resin microcapsules (6) is as follows: a. Weigh out the paraffin wax, petroleum resin, magnetic powder (12), and waterborne epoxy resin (14) according to the required weight proportions of each component. b. Mix paraffin wax with perfluorotributylamine, and heat to melt and disperse the paraffin wax in the perfluorotributylamine solution to obtain a paraffin wax / perfluorotributylamine mixture; c. Heat the petroleum resin to 130~140℃ and stir at 400~600rpm for 20~30min. Add the paraffin / perfluorotributylamine mixture prepared above, control the temperature at 80~90°C, and stir for 10~20min to obtain a paraffin / perfluorotributylamine / petroleum resin mixture. Then add magnetic powder (12), control the temperature at 70~80℃, and stir for 30~60min to obtain a paraffin / perfluorotributylamine / petroleum resin / magnetic powder mixture. Finally, add waterborne epoxy resin, control the temperature at 70~80℃, and stir for 1h~2h. d. Stop heating; increase the stirring speed to 900~1200 rpm, add perfluorotributylamine solution, and rapidly reduce the temperature of the mixture to obtain a suspension of thermoplastic resin-coated magnetic epoxy resin microcapsules; e. The suspension is subjected to ultrasonic dispersion treatment, and then the microcapsules are separated by filtration. After drying, the microcapsules are obtained as magnetic epoxy resin microcapsules (6).

10. The synergistic construction method of the self-healing microcapsule system for cement concrete cracks according to claim 9, characterized in that, The preparation process of the magnetic curing agent microcapsules (7) is as follows: a. Weigh out the paraffin wax, petroleum resin, magnetic powder (12), and curing agent (15) according to the required weight proportions of each raw material; b. Mix paraffin wax and perfluorotributylamine, and heat to melt and disperse the paraffin wax in the perfluorotributylamine solution to obtain a paraffin / perfluorotributylamine mixture; c. Heat the petroleum resin to 130-140°C and stir at 400-600 rpm for 20-30 minutes. Add the paraffin / perfluorotributylamine mixture prepared above, control the temperature at 80-90°C, and stir for 10-20 minutes to obtain a petroleum resin / paraffin / perfluorotributylamine mixture. Then add magnetic powder, maintain the temperature at 70-80°C, and stir for 30-60 minutes to obtain a paraffin / perfluorotributylamine / petroleum resin / magnetic powder mixture. Finally, add the curing agent, control the temperature at 80-90°C, and stir for 1-2 hours. d. Stop heating, increase the stirring speed to 900~1200 rpm, add perfluorotributylamine solution, and rapidly reduce the temperature of the mixture to obtain a suspension of thermoplastic resin-coated curing agent microcapsules; e. The suspension is ultrasonically dispersed, then filtered to separate the microcapsules. The microcapsules are then dried in an oven to obtain magnetic curing agent microcapsules. Magnetic epoxy resin microcapsules (6) and magnetic curing agent microcapsules (7) are mixed at a mass ratio of 60~70:30~40 to obtain self-healing magnetic microcapsules for cement concrete cracks.

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