Reinforced concrete structure durability degradation dynamic defense system and method

Abstract

The invention relates to a dynamic defense system and method for durability degradation of a reinforced concrete structure. The system comprises a composite fabric network pre-buried in the reinforced concrete structure, a sensing unit for monitoring the health state of the structure and a response control unit, the composite fabric network comprises conductive row fiber bundles and conductive column fiber bundles which are intercrossed and woven into a two-dimensional matrix skeleton and can be addressed independently; arranging a plurality of repairing microcapsules which adopt a specific sensitive polymer wall material to package a chemical repairing agent at cross nodes, and additionally arranging function execution assemblies at corresponding nodes according to requirements; and the response control unit applies an excitation signal exceeding a preset threshold value to the target node, and generates or triggers the function execution component to form a corresponding external excitation energy field to act on the sensitive polymer wall material of the repairing microcapsule, so that the sensitive polymer wall material is broken or subjected to phase change to release the chemical repairing agent. According to the method, the threat position, the threat type and the threat level can be accurately positioned, and the repair range and strength are dynamically adjusted.

Description

Technical Field

[0001] This invention relates to technologies for preventing and repairing durability degradation of reinforced concrete structures, and particularly to a dynamic defense system and method for durability degradation of reinforced concrete structures. Background Technology

[0002] The degradation of the durability of reinforced concrete structures is a core challenge limiting their service life. Carbon dioxide, which causes concrete carbonation; chloride ions, which cause steel corrosion; and sulfate ions, which cause concrete cracking, are the main threats from the environment. Traditional methods for addressing this problem often employ electrochemical repair; however, this method is a remedial measure and cannot provide proactive protection throughout the entire lifecycle. Existing solutions, such as randomly incorporating self-healing microcapsules into concrete, have limitations including uncontrollable response, depletion of the repair agent, inability to precisely adjust the repair dosage according to the degree of damage, and difficulty in distinguishing and addressing various coupled corrosion environments. Summary of the Invention

[0003] Purpose of the invention: The present invention aims to provide a dynamic defense system and method for the durability deterioration of concrete structures that can accurately locate the location, type and level of threats, and dynamically adjust the scope and intensity of repairs, thereby extending the life of the structure and improving the utilization efficiency of repair resources.

[0004] Technical solution: The present invention provides a dynamic defense system for durability degradation of reinforced concrete structures, comprising a composite fabric network embedded in the reinforced concrete structure and containing a chemical repair agent, a sensing unit disposed on the composite fabric network for monitoring the internal health status of the reinforced concrete structure, and a response control unit for controlling the release of the chemical repair agent based on the monitoring results.

[0005] The composite fabric network includes a two-dimensional matrix skeleton woven from independently addressable conductive row fiber bundles and conductive column fiber bundles. At the intersection nodes of the two-dimensional matrix skeleton, several repair microcapsules containing chemical repair agents encapsulated in specific sensitive polymer wall materials are placed. Functional execution components are added as needed at the nodes where the repair microcapsules are located. Based on monitoring results, the response control unit applies excitation signals exceeding preset thresholds to the row and column fiber bundles of the target node, generating or triggering the functional execution components to form a corresponding external excitation energy field acting on the sensitive polymer wall material of the repair microcapsules. This causes the polymer wall material to crack or undergo a phase change, thereby releasing the chemical repair agent and achieving dynamic defense against the degradation of the durability of reinforced concrete structures.

[0006] Preferably, the repair microcapsule encapsulates the chemical repair agent using a polymer wall material that is sensitive to a preset threshold voltage, without adding functional execution components. The response control unit generates a high-voltage electric field by applying a pulse high-voltage signal exceeding the preset threshold to the row and column fiber bundles of the target node according to the monitoring results, and uses the dielectric breakdown effect or electron avalanche effect to cause the polymer wall material to break.

[0007] Preferably, the repair microcapsule uses a polymer wall material sensitive to mechanical impact to encapsulate a chemical repair agent. The added functional execution component is a piezoelectric actuator. The response control unit, based on the monitoring results, applies an alternating voltage signal exceeding a preset threshold to the row and column fiber bundles of the target node, triggering the piezoelectric actuator to generate an ultrasonic sound field or mechanical vibration field, thereby causing the polymer wall material to crack through acoustic fatigue or mechanical resonance.

[0008] Preferably, the repair microcapsule uses a polymer wall material sensitive to magnetocaloric effect to encapsulate a chemical repair agent. The added functional execution component is an induction coil or a resistance heating element. The response control unit, based on the monitoring results, applies an alternating current signal exceeding a preset threshold to the row and column fiber bundles of the target node, triggering the functional execution component to generate an alternating magnetic field or thermal field. The polymer wall material temperature is raised to the melting point and undergoes a phase change melting by using electromagnetic induction heating or resistance heating.

[0009] Preferably, the repair microcapsules include at least type B repair microcapsules for corrosion resistance and type C repair microcapsules for sulfate resistance; a plurality of type B repair microcapsules and a plurality of type C repair microcapsules are respectively disposed on different nodes of the composite fabric network. The nodes on the composite fabric network where type B repair microcapsules are disposed are called type B pixel nodes, and the nodes where type C repair microcapsules are disposed are called type C pixel nodes. The type B pixel nodes and type C pixel nodes are arranged adjacent to each other on the composite fabric network in a checkerboard pattern.

[0010] Preferably, the corrosion-resistant type B repair microcapsules are internally encapsulated with a chloride ion fixative; the sulfate-resistant type C repair microcapsules are internally encapsulated with a strontium hydroxide aqueous solution.

[0011] Preferably, the repair microcapsule further includes a carbonization-resistant type A repair microcapsule, and the insulating layer covering the composite fabric network has a coating layer, in which the type A repair microcapsule is disposed.

[0012] Preferably, the type A repair microcapsule comprises a pH-sensitive chitosan polymer wall material and an internally encapsulated calcium hydroxide concentrate slurry.

[0013] Preferably, the sensing unit adopts a distributed optical fiber sensing system, which is an integrated sensing optical fiber woven into a composite fabric network and passing through all nodes. It includes at least a pH value identification probe, a chloride ion identification probe, a sulfate ion identification probe, and a host, and is used to monitor the pH value, chloride ion concentration, and sulfate ion concentration corresponding to the node coordinates on the optical fiber path.

[0014] Preferably, the pH recognition probe is immobilized with a pH-sensitive indicator dye, used to identify pH changes by changes in absorption spectrum; the chloride ion recognition probe is a fluorescent probe, which is immobilized with fluorescent molecules, used to identify chloride ions by fluorescence quenching; the sulfate ion recognition probe is immobilized with barium ions and a fluorescent dye sensitive to the quenching effect of barium ions, used to identify sulfate ions by detecting changes in fluorescence intensity.

[0015] The dynamic defense method of the dynamic defense system for durability degradation of reinforced concrete structures according to the present invention includes the following steps: (1) An addressable composite fabric network with repair microcapsules is pre-embedded in a reinforced concrete structure; (2) Set up sensing units on the composite fabric network to monitor the health status of the reinforced concrete structure in real time and draw a health map based on the mapping relationship between the optical fiber path and the composite fabric network. (3) Identify threat types and locations based on monitoring results; determine the row and column addresses of repair microcapsules to be activated based on the location of the threat; and determine the intensity of the excitation signal and the number of repair microcapsules to be activated based on the type and level of the threat. (4) Apply an excitation signal exceeding a preset threshold to the node where the repair microcapsule is located to generate an external excitation energy field at the node, causing the wall material of the repair microcapsule to undergo physical rupture or phase change to release the chemical repair agent encapsulated inside, thereby performing dynamic repair and defense.

[0016] Compared with the prior art, the present invention has the following significant advantages: the repair functional unit is upgraded from the traditional randomly distributed capsules to precise pixels, and the independent activation of repair microcapsules at any node is realized through matrix addressing technology. This enables the system to dynamically adjust the scope and intensity of repair according to the precise location and severity of the damage, thereby maximizing the extension of the structure's lifespan and greatly improving the utilization efficiency of repair resources. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the composite fabric network structure of the present invention; Figure 2 This is a schematic diagram of the composite fabric network configuration of the present invention; wherein, Figure 2 (a) is a schematic diagram of the tiling setup. Figure 2(b) is the front view of the surround setting. Figure 2 (c) Top view of the surrounding layout; Figure 3 For the present invention Figure 1 Enlarged view of point a in the middle; Figure 4 This is a schematic diagram showing the arrangement of the distributed optical fiber sensing unit of the present invention; Figure 5 This is a flowchart of the method of the present invention. Detailed Implementation

[0018] The technical solution of the present invention will be further described below with reference to the accompanying drawings.

[0019] Example 1

[0020] The present invention discloses a dynamic defense system for durability degradation of reinforced concrete structures, comprising a composite fabric network 1 embedded in the reinforced concrete structure and containing a chemical repair agent, a sensing unit 2 disposed on the composite fabric network for monitoring the internal health status of the reinforced concrete structure, and a response control unit for controlling the release of the chemical repair agent based on the monitoring results.

[0021] This embodiment utilizes dielectric breakdown.

[0022] like Figure 1 As shown, the composite fabric network 1 includes a two-dimensional matrix skeleton woven from independently addressable conductive row fiber bundles 11 and conductive column fiber bundles 12. The surfaces of both the conductive row and column fiber bundles are covered with an insulating layer, and conductive contacts are only provided at the intersection nodes. Several repair microcapsules 13 are disposed at the intersection nodes of the two-dimensional matrix skeleton, such as... Figure 3 As shown. In order to construct a microenvironment capable of withstanding high electric field strength, the conductive contacts and the surface of the repair microcapsules are treated with a hydrophobic nano-coating, preferably an ultrathin modification layer of fluorosilane or polytetrafluoroethylene.

[0023] The repair microcapsules comprise a polymer wall material sensitive to a preset threshold voltage and an internally encapsulated chemical repair agent for repairing concrete. The microcapsules are designed so that when a pulse voltage exceeding the preset threshold is applied between the row and column fiber bundles containing them, the polymer wall material ruptures, releasing the internally encapsulated chemical repair agent. Several repair microcapsules form a tightly packed structure under weaving tension. This micron-scale tightly packed structure, combined with a hydrophobic coating on the surface, creates an airtight microscopic physical contact interface between the conductive contacts and the microcapsule wall material. The hydrophobic repulsion effectively displaces the conductive concrete pore liquid between the contact surfaces, forming a dry electrical contact channel. This ensures that the electric field energy is concentrated at both ends of the microcapsule wall material, preventing short-circuit leakage through the pore liquid. Even if a trace amount of residual liquid film exists at the contact interface, the local Joule heat generated at the contact point at the moment of preset voltage triggering vaporizes the liquid film, maintaining the electrical insulation of the breakdown channel.

[0024] The composite fabric network 1 is embedded in the reinforced concrete structure, for example, it can be laid flat inside the reinforced concrete wall near the reinforcing bars, or arranged around the inside of the bridge pier near the reinforcing bars, such as... Figure 2 As shown.

[0025] The repair microcapsules include type B repair microcapsules for corrosion resistance and type C repair microcapsules for sulfate resistance. The type B repair microcapsules for corrosion resistance include a polymer wall material sensitive to a preset threshold voltage and an internally encapsulated chloride ion fixative, preferably an aqueous solution of sodium aluminate. Sodium aluminate (NaAlO2) readily hydrolyzes in aqueous solution to generate aluminate ions, which react with calcium ions already present in the concrete and invading chloride ions to form Freund's salt. Since Freund's salt is a stable crystalline hydrate, chloride ions are incorporated into the crystal structure of Freund's salt, becoming part of the solid phase, thus losing their mobility and corrosive activity. The reaction process is as follows: (French salt) The C-type repair microcapsules for sulfate attack resistance comprise a polymer wall material sensitive to a preset threshold voltage and an internally encapsulated strontium hydroxide aqueous solution. The main hazard of sulfate attack in concrete is that invading sulfate ions react with calcium hydroxide and calcium aluminate hydrates in cement hydration products to form expansive gypsum and ettringite, leading to concrete cracking, spalling, and damage. Furthermore, the strontium hydroxide released after the microcapsule structure ruptures preferentially reacts with SO42-. 2-The ionic reaction generates SrSO4, an inert substance that is chemically stable and non-expanding. The byproduct, hydroxide ions, significantly increases the alkalinity of the local environment, providing a safer environmental immunity for the passivation film of the reinforcing steel. The polymer wall material sensitive to the preset threshold voltage is a polymer insulating wall material doped with high dielectric constant particles, preferably polyvinylidene fluoride (PVDF) doped with titanium dioxide.

[0026] Several type B repair microcapsules and several type C repair microcapsules are respectively attached to different nodes of the composite fabric network. Nodes on the composite fabric network with type B repair microcapsules are called type B pixel nodes 14, and nodes with type C repair microcapsules are called type C pixel nodes 15. Type B pixel nodes and type C pixel nodes are arranged adjacent to each other in a checkerboard pattern, alternating between them. Figure 4 As shown. By applying a first potential to the target row fiber bundle and a second potential to the target column fiber bundle, the potential difference at the target intersection node reaches a preset threshold, thereby breaking down the polymer wall material of the repair microcapsule at the target node location; while the potential difference borne by other nodes in the same row and column does not reach the preset threshold, which is insufficient to cause the repair microcapsule wall material at the node to rupture.

[0027] The composite fabric network has an insulating layer with a coating layer containing carbonization-resistant type A repair microcapsules. These microcapsules comprise a pH-sensitive chitosan polymer wall material and an internally encapsulated calcium hydroxide concentrate. The polymer wall material is preferably a polyelectrolyte composite gel formed from modified chitosan and sodium alginate. The sodium alginate molecular chains form a dense gel network through calcium ion crosslinking, with modified chitosan interspersed within to enhance the mechanical strength of the wall material. When carbonization occurs, externally invading carbon dioxide reacts with the pore fluid to generate carbonate ions, which competitively capture the calcium ion crosslinking agent maintaining the gel structure of the wall material, resulting in calcium carbonate precipitation. With the loss of calcium ions, the sodium alginate gel network disintegrates. Simultaneously, the decrease in pH associated with carbonization causes the modified chitosan component to protonate and swell, generating internal expansion stress. Under this dual action, the microcapsule wall material rapidly ruptures, releasing the internally encapsulated calcium hydroxide. After the calcium hydroxide is released internally, it neutralizes the carbonic acid and prevents the pH value of the concrete from continuing to drop. At the same time, the calcium carbonate precipitate crystals generated are deposited in the capillary pores of the concrete, which plays a role in filling and sealing, reducing the permeability of the concrete, thereby slowing down the subsequent invasion rate of CO2 and other harmful ions, and playing a dual repair role of chemical neutralization and physical sealing.

[0028] The sensing unit 2 employs a distributed optical fiber sensing system, comprising at least a pH value detection probe, a chloride ion detection probe, a sulfate ion detection probe, and a host unit, used to monitor the pH value, chloride ion concentration, and sulfate ion concentration corresponding to the node coordinates along the optical fiber path. To eliminate optical crosstalk between detection signals of different chemical parameters and improve detection accuracy, the distributed optical fiber sensing system is designed as a multi-channel parallel integrated sensing fiber bundle. The integrated sensing fiber bundle consists of at least three independently operating sensing fibers bundled or twisted together side-by-side, used for independent pH value monitoring, chloride ion monitoring, and sulfate ion monitoring, respectively. The outer layer of the fiber bundle is wrapped with a braided sheath or microporous loose tube that is permeable to liquid but impermeable to cement particles, providing mechanical protection and preventing shear damage during pouring. The fiber bundle is arranged in an arc or serpentine pattern along the conductive row and column fiber bundles on the composite fabric network, passing through all intersection nodes, such as... Figure 4 As shown, the host unit 21 of the distributed fiber optic sensing system is integrated in the response control unit and has multi-channel spectral analysis and fluorescence intensity demodulation functions.

[0029] The pH identification probe is immobilized with a pH-sensitive indicator dye, used to identify pH changes through variations in the absorption spectrum. The principle is as follows: based on the total internal reflection phenomenon of optical fiber, when the pH value of the external environment changes due to carbonization, the chemical structure of the indicator dye changes accordingly, causing a change in the color of the absorbed light, i.e., the absorption spectrum. Because the evanescent wave has a sensing range at the nanometer level, it can instantly detect the change in dye color and reflect it as spectral attenuation in the optical signal transmitted inside the optical fiber. Finally, the response control unit can accurately determine whether the location has been acidified by analyzing the spectral characteristics of the returned signal.

[0030] The chloride ion recognition probe is a fluorescent probe, which carries fluorescent molecules to recognize chloride ions via fluorescence quenching. The principle is as follows: the fluorescent molecules on the probe emit bright fluorescence continuously under specific excitation light. When chloride ions diffuse to the vicinity of the probe, they undergo high-frequency physical collisions with the excited fluorescent molecules, reducing their energy and fluorescence intensity through non-radiative means. The higher the chloride ion concentration, the greater the probability of collisional quenching, and the lower the total observable fluorescence intensity. Therefore, the response control unit can quantitatively determine the chloride ion concentration at a given location by precisely measuring the decay of the fluorescence signal from bright to dark.

[0031] The sulfate recognition probe is immobilized with barium ions and a fluorescent dye that enhances the fluorescence of barium ions through coordination, and is used to recognize sulfate ions by competitive coordination fluorescence quenching. The principle is as follows: First, a fluorescent dye molecule forms a complex with barium ions, utilizing the coordination effect of the metal ions to put the dye molecule in a highly fluorescent state as an initial probe. When the number of sulfate ions increases, because the binding ability of sulfate ions to barium ions is much stronger than that of the fluorescent dye molecule to barium ions, the sulfate ions will competitively capture barium ions, causing the fluorescent dye molecule to lose the enhancing effect of the coordinating ions and dissociate. The fluorescence quantum yield of the dissociated free-state fluorescent dye molecule decreases significantly, leading to fluorescence quenching or significant attenuation. The response control unit can determine the intrusion of sulfate ions by monitoring the attenuation process of the fluorescence signal from bright to dark. In this embodiment, a soluble barium salt and a fluorescent dye sensitive to the quenching effect of barium ions are preferably immobilized on the surface of an optical fiber using a sol-gel method.

[0032] The host of the distributed optical fiber sensing system calculates the pH value, chloride ion concentration, and sulfate ion concentration corresponding to the coordinate points on the optical fiber path by measuring spectral absorption and fluorescence intensity changes. Based on the mapping relationship between the optical fiber path and the composite fabric network, it converts and draws a visualized concrete chemical health map in real time.

[0033] The response control unit compares real-time data obtained from the distributed fiber optic sensing system with a preset threat threshold to determine the threat type, location, and level. Based on the determination result, it selects the repair microcapsule type, calculates the dynamic dose, and identifies the pixel nodes requiring repair defense. A preset voltage is applied to both ends of the target repair microcapsule node to activate the repair microcapsule and release chemical repair agents for repair defense.

[0034] like Figure 5 As shown, the present invention provides a dynamic defense method for durability degradation of reinforced concrete structures, comprising the following steps: (1) An addressable composite fabric network with chemical repair agent is pre-embedded in a reinforced concrete structure; (2) Set up sensing units on the composite fabric network to identify the pH value, chloride ion concentration and sulfate ion concentration inside the reinforced concrete structure, monitor the health status of the reinforced concrete structure in real time, and draw a health map based on the mapping relationship between the optical fiber path and the composite fabric network. (3) Identify threat types and locations based on monitoring results; determine the row and column addresses of repair microcapsules to be activated based on the location of the threat; determine the applied voltage level and the number of repair microcapsules to be activated based on the type and level of the threat; apply the corresponding voltage to the node where the identified repair microcapsules are located to activate the repair microcapsules to release the chemical repair agent encapsulated inside them for dynamic repair and defense.

[0035] The technical solution of the present invention is further illustrated below with a specific embodiment. This embodiment describes a dynamic defense system for the durability degradation of reinforced concrete structures applied to a certain marine engineering building.

[0036] This invention discloses a dynamic defense system for durability degradation of reinforced concrete structures, comprising a prefabricated, flexible composite fabric network fixed between the reinforcing cage and the formwork during reinforced concrete pouring. The composite fabric network is composed of independently addressable conductive row and column fiber bundles interwoven together. Preferably, the distance between the warp and weft threads of the composite fabric network is 2 cm. Different types of repair microcapsules are placed at the intersection nodes.

[0037] The anti-carbonization type A repair microcapsules have a particle size of 50-150 μm and an average particle size of 100 μm. The preferred polymer wall material is a polyelectrolyte composite gel formed from modified chitosan and sodium alginate, wherein sodium alginate serves as the framework, and its chemical formula is [chemical formula missing]. Chitosan is a natural polysaccharide with numerous carboxyl functional groups on its molecular chain. Modified chitosan is a derivative introduced by chemical grafting of amino protecting groups. Its molecular chain contains a large number of amino functional groups sensitive to weakly alkaline environments, acting as a pH sensor and self-destruct switch. Its polymer wall material rupture and release mechanism is based on the synergistic effect of competitive calcium ion replacement and pH-responsive swelling. When concrete carbonates, externally infiltrated carbon dioxide reacts with the pore fluid to generate carbonate ions. Because the solubility product constant of calcium carbonate is much lower than that of calcium alginate, carbonate ions competitively capture the calcium ion crosslinking agent that maintains the gel structure of the wall material, reacting to form calcium carbonate precipitate. With the loss of calcium ions, the sodium alginate gel network disintegrates. Simultaneously, the decrease in pH associated with carbonation causes the modified chitosan component to undergo protonation swelling, generating internal expansion stress. Under the dual effects of skeletal disintegration and internal expansion, the microcapsule wall material rapidly ruptures, releasing the encapsulated calcium hydroxide.

[0038] The corrosion-resistant type B microcapsules have a particle size of 50-150 μm, with an average particle size of 80 μm. The polymer wall material is preferably a polyvinylidene fluoride (PVDF) composite polymer doped with titanium dioxide nanoparticles, with a thickness of 1 μm. The internal core material is a chloride ion fixative, preferably sodium aluminate in this embodiment. TiO2 is a semiconductor material with a high dielectric constant, and PVDF is a high-performance insulating dielectric with excellent resistance to strong alkalis, ensuring that the core material will not hydrolyze and corrode the shell during the encapsulation period. When a threshold voltage is applied, the microcapsules release the encapsulated sodium aluminate through controlled dielectric breakdown of the wall material, solidifying the harmful free chloride ions into harmless, stable minerals.

[0039] The dielectric breakdown principle of its polymer wall material (TiO2-doped PVDF) is as follows: A transient high-voltage pulse is applied through potential modulation. When a potential difference is applied to both ends of the microcapsule shell, which is only 1 μm thick, an electric field is formed. Because the dielectric constant of TiO2 nanoparticles is much higher than that of the PVDF matrix, the electric field lines are twisted and concentrated around the TiO2 nanoparticles, leading to an increase in the local electric field strength near them. When the local field strength exceeds the breakdown threshold of the PVDF composite material, valence band electrons are released, forming initial free electrons. These free electrons are accelerated in the electric field and bombard the atoms on the PVDF molecular chains at high frequency, generating secondary electrons. This results in an exponential increase in the number of electrons, forming an electron avalanche. The electron avalanche forms one or more plasma-conducting channels in the insulating PVDF matrix. The internal energy of these channels is released instantaneously, triggering high-temperature decomposition or melt perforation of the polymer surrounding the channel. This single, pulsed breakdown is designed to create one or more stable, micron-sized release pores on the wall material, allowing the internally encapsulated sodium aluminate aqueous solution of chemical repair agent to slowly and continuously leak into the external crack space, achieving low-energy, controllable, on-demand release.

[0040] The process expression is: V br =E bd ×d in, V br Indicates the breakdown voltage. E bd This indicates the dielectric breakdown field strength of the composite material, which can be precisely tuned by controlling the doping concentration of TiO2 nanoparticles. d This indicates the casing thickness. (To indicate the breakdown voltage) V br The voltage is adjusted to around 50V, which meets engineering safety standards. In this embodiment, the doping concentration of TiO2 is set to 10 wt% to 25 wt%, preferably 15 wt% to 20 wt%.

[0041] The C-type repair microcapsules resistant to sulfate attack have a particle size of 50-150 μm and an average particle size of 80 μm. The polymer wall material is preferably PVDF doped with titanium dioxide nanoparticles, with a thickness of 1 μm, and the internal core material is strontium hydroxide.

[0042] The dielectric breakdown mechanism of the polymer wall material in the C-type repair microcapsule is the same as that of the B-type microcapsule. Furthermore, the strontium hydroxide released after the microcapsule structure ruptures preferentially reacts with SO4. 2-The ionic reaction produces SrSO4, an inert substance that is chemically stable and non-swellable. The byproduct of this reaction, hydroxide ions, significantly increases the alkalinity of the local environment, providing a safer environmental immunity for the passivation film on the reinforcing steel.

[0043] In this composite fabric network, B-type pixel nodes with several B-type repair microcapsules and C-type pixel nodes with several C-type repair microcapsules are arranged adjacent to each other in a checkerboard pattern at the intersections, ensuring that both active repair capabilities exist simultaneously in any local area. To ensure the effectiveness of electric field application in underwater or humid environments, both the conductive contacts and the microcapsule surfaces are coated with a superhydrophobic nano-coating. At the intersections, the repair microcapsules form a tightly packed structure under the action of weaving tension. This micron-scale tightly packed structure, combined with the hydrophobic coating, creates an airtight physical contact interface between the conductive contacts and the microcapsule wall material. The hydrophobic repulsion effectively dissipates the conductive concrete pore liquid between the contact surfaces, forming a dry, direct electrical contact channel, thereby preventing current short-circuiting through external liquids and ensuring that electric field energy can be applied to the microcapsule insulating wall material without damage. The insulating layer is coated with a porous, electrically insulating adhesive, preferably a breathable hydrogel, in which carbonization-resistant A-type repair microcapsules are uniformly distributed.

[0044] The present invention discloses a dynamic defense system for durability degradation of reinforced concrete structures, which further includes a distributed optical fiber sensing system for monitoring the internal health status of the concrete and mapping its health. The distributed optical fiber sensing system is a multimodal optical fiber sensor bundle woven into a composite fabric network, including a pH value detection probe, a chloride ion detection probe, a sulfate ion detection probe, and a host computer. The host computer is a distributed optoelectronic integrated demodulation host, integrating an OFDR module and a fluorescence demodulation module.

[0045] The pH identification probe uses a pH indicator dye, preferably thymolphthalein, thymol blue or its modified derivatives, to identify a decrease in the pH value of concrete pore fluid through the evanescent wave absorption principle.

[0046] The fabrication process is as follows: Standard single-mode optical fiber is selected, and a precision side polishing process is used to remove part of the cladding on one side, forming a D-shaped optical fiber structure with an asymmetric cross-section. A nanoporous silica film is coated on the polished surface using a sol-gel method. During the gel preparation process, a pH indicator dye is covalently bonded to the silica network framework using a silane coupling agent to prevent the dye from leaching out in the highly alkaline environment of concrete.

[0047] Its working process is as follows: a) The OFDR module in the distributed optoelectronic demodulation host emits a linearly swept continuous laser signal into the optical fiber; b) When the laser propagates within the fiber core, its electromagnetic field penetrates the fiber core / gel interface in the form of an evanescent wave and enters the gel coating containing the indicator. c) The pH indicator molecules in the gel coating change their molecular structure (such as the opening and closing of the lactone ring) according to the pH value of the surrounding microenvironment, thereby changing their absorption coefficient for specific wavelengths of light. d) The distributed optoelectronic integrated demodulation host analyzes the Rayleigh backscattered signal along the optical fiber and demodulates the spectral loss characteristics of the signal at a specific location; e) By comparing the signal attenuation intensity of the characteristic absorption band (corresponding to the absorption peak of the indicator) with a pre-calibrated pH-light loss database, the pH value at that location can be accurately demodulated. When the pH value is detected to drop from the alkaline frequency domain to the neutral or weakly alkaline frequency domain, i.e., from pH > 12.0 to pH < 9.5, carbonization is determined to have occurred at that location.

[0048] The chloride ion recognition probe is a fluorescent fiber optic probe used to identify free chloride ions that have penetrated into the concrete through a fluorescence quenching mechanism.

[0049] The preparation process is as follows: A D-type optical fiber structure is constructed, and using the sol-gel method, fluorescent probe molecules sensitive to chloride ions are covalently bonded to a porous silica network on the fiber core surface via a silane coupling agent. The selection of the fluorescent probe molecules must match the low-loss transmission window of the optical fiber. To ensure specific recognition and eliminate interference from other ions in the concrete pore fluid, quinoline derivatives with high specific quenching response to chloride ions are preferred, especially N-(ethoxycarbonylmethyl)-6-methoxyquinoline bromide; alternatively, in long-distance monitoring scenarios, to reduce optical fiber transmission loss, chloride ion-sensitive fluorescent dyes with near-infrared excitation characteristics are preferred.

[0050] Its working process is as follows: a) The fluorescence demodulation module in the distributed optoelectronic integrated demodulation host emits optical signals with specific excitation wavelengths into the optical fiber based on fluorescence OTDR or frequency domain fluorescence technology; b) Evanescent wave energy excites the fluorescent probe molecules in the gel coating, causing them to transition to an excited state. In a chloride-free environment, the excited probe molecules produce high-intensity characteristic fluorescence, at which point the fluorescence intensity is... I 0 ; c) When chloride ions diffuse into the gel film through the pores of concrete, the chloride ions act as quenchers and collide dynamically with fluorescent molecules in the excited state, causing the fluorescent molecules to return to the ground state through non-radiative transitions, thereby significantly reducing the fluorescence emission intensity. d) The host measures the attenuation of local fluorescence intensity by receiving and analyzing the back fluorescence signal or the light intensity distribution after Stokes shift along the optical fiber path.

[0051] Among them, fluorescence intensity I is related to chloride ion concentration [Cl]. − The relationship between them follows the Stern-Wolmer equation:

[0052] in, I 0 The initial fluorescence intensity in the absence of chloride ions. K SV This is the quenching constant. The response control unit can accurately determine the chloride ion concentration at a given location by calculating the percentage decrease in fluorescence intensity.

[0053] The sulfate recognition probe is loaded with barium ions and calcein fluorescent dye that is sensitive to the quenching effect of barium ions. Its core is to use a fluorescent complex that specifically responds to barium ions as a sensitive unit and adopt a "competitive precipitation-fluorescence release" mechanism to recognize invading sulfate ions by competitively binding fluorescence recovery method.

[0054] The preparation process of the sulfate recognition probe is as follows: A D-shaped optical fiber structure is constructed, and a functionalized silica hydrogel matrix is ​​coated onto the side-polished fiber core surface. To isolate the interference of calcium ions in concrete throughout its entire lifespan, a "tiered defense" strategy is adopted. First, the gel matrix undergoes high-density quaternization modification, grafting positively charged quaternary ammonium salt functional groups to construct a "cationic electrostatic shielding layer," utilizing the principle of like charges repulsion to block the entry of high-concentration background calcium ions. A trace amount of calcium ion-specific masking agent, preferably ethylene glycol bis(2-aminoethyl ether)tetraacetic acid (EGTA), is doped inside the gel to capture and complex a small amount of residual calcium ions that penetrate the electrostatic shielding layer. Simultaneously, due to the interaction between EGTA and Ba... 2+ The weak binding force prevents damage to the calcein-barium sensing probe, ensuring that changes in the fluorescence signal are triggered solely by the precipitation competition of sulfate ions for barium ions, thus enabling independent and precise monitoring of sulfate erosion. During preparation, the molar amount of the quaternary ammonium salt component needs to be controlled to be much higher than that of EGTA to ensure that the gel layer maintains a strong positive charge throughout.

[0055] Its working process is as follows: a) Initial highlight state: Ba is pre-selected 2+ It forms a calcein-barium ion complex with the immobilized calcein molecules. Due to the chelation-enhanced fluorescence effect, the system is in a high-fluorescence state; b) Dual anti-interference filtration: When the pore liquid comes into contact with the sensor, the positively charged gel layer first repels most of the Ca. 2+ A very small amount of Ca seeps into the gel due to osmotic pressure. 2+Because EGTA's binding affinity for Ca is much higher than its affinity for Ba, it is immediately and preferentially captured by the internal EGTA. This dual synergistic mechanism ensures that the barium ion probe in the core sensing region is not affected by any calcium ion replacement. c) Competitive quenching and signal reversal: Negatively charged SO4 2- Attracted and enriched by positively charged gel, it then interacts with Ba in the complex. 2+ The reaction produces a precipitate. Calcein, having lost its metal ions, is released, leading to a sharp drop in fluorescence quantum yield and a drastic decrease in local fluorescence intensity. d) Signal Acquisition and Judgment: The distributed optoelectronic demodulation host monitors the attenuation rate of fluorescence intensity. The response control unit converts the decrease in fluorescence intensity into sulfate ion concentration based on a pre-calibrated concentration curve. To ensure signal uniqueness, the system employs a dual-wavelength ratio measurement method or optical time-domain reflectometry (OTDR) loss analysis to distinguish between chemical quenching and physical loss.

[0056] The distributed optical fiber sensing system of this invention, through a distributed optoelectronic demodulation host integrated within the response control unit, sends a series of composite light pulses at a preset frequency to each identification probe woven alongside the composite fabric network. The host collects and demodulates backscattered light signals and fluorescence signals returned from various points along the optical fiber at high speed. By analyzing the changes in spectral absorption and fluorescence intensity, it calculates the pH value, chloride ion concentration, and sulfate ion concentration corresponding to the node coordinates on the optical fiber path. Furthermore, based on the mapping relationship between the optical fiber path and the composite fabric network, it converts and draws a visualized concrete chemical health map in real time.

[0057] The present invention discloses a dynamic defense system for durability degradation of reinforced concrete structures, which further includes a response control unit, i.e., a central controller. The central controller compares real-time data obtained from distributed sensors with a preset threat threshold database (as shown in Table 1) to determine the threat location, threat type, and level. Based on the determination results, it selects target repair microcapsules and calculates dynamic dosage. A preset voltage is applied to both ends of the target repair microcapsules to trigger the release of chemical repair agents for repair and defense.

[0058] Table 1 Threat Threshold Database and Corresponding Remediation Decision Schemes

[0059] The present invention discloses a dynamic defense method for durability degradation of reinforced concrete structures, comprising the following steps: (1) An addressable composite fabric network with chemical repair agent is pre-embedded in a reinforced concrete structure; (2) A distributed optical fiber sensing system is set up on the composite fabric network to monitor the health status of the reinforced concrete structure in real time and draw a health map based on the mapping relationship between the optical fiber path and the composite fabric network. (3) Identify the threat type and location based on the monitoring results; determine the row and column addresses of the repair microcapsules that need to be activated based on the location of the threat; determine the applied voltage level and the type and number of repair microcapsules that need to be activated based on the type and level of the threat; apply the corresponding voltage to the identified repair microcapsules to activate them, causing them to rupture and release the encapsulated chemical repair agent inside, so as to carry out dynamic repair and defense.

[0060] Step (3) includes: (3.1) Based on the real-time data obtained by the distributed optical fiber sensing system, compare it with the preset threat threshold database to determine the threat location, threat type and level.

[0061] (3.2) Based on the location of the threat, determine the row and column addresses of the repair microcapsules to be activated, such as (row R, column C). Based on the type and level of the threat, determine the applied voltage level and the number of repair microcapsules to be activated. For example, if chloride ion level 1 is identified, activate the 1×1 matrix centered on the threat point, i.e., 1 type B pixel node; if chloride ion level 2 is identified, activate the 3×3 matrix centered on the threat point, i.e., 5 type B pixel nodes; if sulfate level is identified, activate all type C pixel nodes in the 2×2 matrix centered on the threat point. Based on the calculation results, generate a target address list containing all repair microcapsules to be activated, such as [B(R15, C22), C(R16, C23), ...].

[0062] (3.3) Based on the threat type and target address list, the central controller employs a time-division multiplexing or point-by-point scanning strategy to sequentially apply preset voltages corresponding to the threat type to the conductive row and column fiber bundles, activating the corresponding repair microcapsules to release chemical repair agents, thus avoiding cross-interference caused by simultaneous triggering at multiple points. For example, when the system activates address B (R15, C22), the central controller applies a +25V voltage to the 15th row conductive fiber bundle and a -25V voltage to the 22nd column conductive fiber bundle, creating a 50V potential difference across the B-type repair pixel at the cross node (R15, C22), exceeding its dielectric breakdown threshold, causing the B-type repair microcapsule to rupture and release sodium aluminate. Repair microcapsules at other non-target addresses in row 15 or column 22 only withstand a 25V potential difference, insufficient to trigger rupture. After activating this point, the system switches to the next target address to perform the operation.

[0063] (3.4) After one or more activations, the central controller focuses on changes in the chemical parameters of the repair area. If the threat is eliminated, the current repair cycle ends. If the threat persists or worsens, the central controller decides to execute a new round of repair, increase the number of activated repair microcapsules, or reassess the threat type. If the threat remains uncontrolled after the repair agent is consumed, an alarm is issued.

[0064] To further verify the effectiveness of the method in this embodiment, a TiO2-doped PVDF solution, consistent with the formulation of the B-type microcapsule wall material, was used to prepare a homogeneous polymer film with a thickness of 1.0 μm ± 0.1 μm on an indium tin oxide (ITO) conductive glass substrate via spin coating, simulating the shell of the microcapsule. A 1 mm diameter copper probe was used as the upper electrode to lightly touch the surface of the film, and the ITO glass was used as the lower electrode. A high-precision source meter was connected to apply voltage and monitor the current flowing through the film.

[0065] When a single-amplitude voltage (25V) is applied, a semi-selective node is simulated, meaning that voltage is applied only to the target row or column fiber bundle. Monitoring data shows that the leakage current flowing through the film is only in the nA range, and the film exhibits extremely high insulation resistance. After continuous energization for 60 minutes, the probe contact point is observed under a microscope; the film surface is smooth and intact, without any signs of ablation or breakdown. This demonstrates that at 25V, the electric field strength is lower than the dielectric strength of the material, and electron avalanche is not triggered, verifying the safety of the non-target node.

[0066] When a double-amplitude voltage (50V) was applied, all nodes were simulated, i.e., voltage was applied to the target cross-nodes. At the instant of voltage application (<10 ms), the monitored current experienced a sudden step increase, jumping from the nA level to the mA level, indicating insulation failure. Subsequent microscopic observation revealed physical perforations of approximately 2-5 μm in diameter in the polymer film at the probe contact location. This confirmed that under double voltage, the electric field strength exceeded the withstand limit of the PVDF composite material, successfully inducing irreversible dielectric breakdown and forming a release channel.

[0067] Example 2

[0068] The present invention discloses a dynamic defense system for durability degradation of reinforced concrete structures, comprising a composite fabric network embedded in the reinforced concrete structure and containing a chemical repair agent, a sensing unit disposed on the composite fabric network for monitoring the internal health status of the reinforced concrete structure, and a response control unit for controlling the release of the chemical repair agent based on the monitoring results.

[0069] This embodiment utilizes cavitation effect and mechanical resonance effect for breakdown.

[0070] The composite fabric network includes: a two-dimensional matrix skeleton woven from independently addressable conductive row fiber bundles and conductive column fiber bundles; a plurality of repair microcapsules are disposed at the intersection nodes of the two-dimensional matrix skeleton, the repair microcapsules containing a brittle inorganic wall material sensitive to high-frequency mechanical impact and an internally encapsulated chemical repair agent for repairing concrete; wherein, the repair microcapsules are designed such that when a preset alternating voltage is applied between the row fiber bundle and the column fiber bundle in which they are located, their polymer wall material ruptures and releases the internally encapsulated chemical repair agent.

[0071] The repair microcapsules include type B repair microcapsules that resist corrosion and type C repair microcapsules that resist sulfate attack.

[0072] The core materials of the type B and type C repair microcapsules remain unchanged, consistent with Example 1. The core material of the corrosion-resistant type B microcapsules is an aqueous solution of sodium aluminate, while the core material of the sulfate-resistant type C repair microcapsules is an aqueous solution of strontium hydroxide. Both use brittle inorganic materials sensitive to mechanical impact as their wall material. In this embodiment, thin-walled hollow microspheres made of alkali-resistant glass or zirconium-doped borosilicate glass are preferred. Compared to ordinary glass, alkali-resistant glass contains a high proportion of zirconium oxide, effectively resisting long-term erosion by the strongly alkaline core material and ensuring that the wall material does not undergo natural thinning or perforation during the decades-long pre-embedding period. The microsphere wall thickness is preferably 0.5-1.0 μm. These microspheres have sufficient strength to withstand low-frequency mechanical stress during construction and pouring, but exhibit significant brittleness under high-frequency ultrasonic impacts above 20 kHz. The glass microcapsules can be prepared by encapsulating liquid core materials using existing sol-gel dual emulsion template methods or microfluidic technology; the specific preparation process will not be described in detail in this embodiment.

[0073] Except for conductive contact areas at intersections, the conductive fiber bundles in the composite fabric network are all coated with an insulating layer. The conductive fiber insulating layer of the composite fabric network has a coating layer on which the type A repair microcapsules are immobilized. The coating layer is an ion-permeable adhesive coating, preferably a highly absorbent and breathable hydrogel. The type A repair microcapsules comprise a pH-sensitive modified chitosan-sodium alginate polymer wall material and an internally encapsulated concentrated calcium hydroxide slurry. Its rupture mechanism is consistent with that of Example 1.

[0074] The distributed fiber optic sensing system adopts the same multimode fiber optic sensing bundle architecture as in Embodiment 1, for high-precision positioning and identification of Cl. - SO4 2- Changes in concentration and pH value.

[0075] The response control unit includes piezoelectric actuators located at the cross nodes of the two-dimensional matrix skeleton of the composite fabric network. These piezoelectric actuators are preferably PZT piezoelectric ceramic microsheets or PZT piezoelectric fiber bundles encapsulated in a protective shell, which is made of a rigid, acoustically transmissive polymer such as epoxy resin. To ensure reliable electrical connections and efficient acoustic energy transmission in a concrete environment, the electrodes at both ends of the PZT piezoelectric actuator are respectively bonded to the conductive row and column fiber bundles (with the insulation layer removed) at the cross nodes using high-strength conductive silver paste or conductive epoxy resin. Thus, the conductive row and column fiber bundles constitute the driving electrodes for differential excitation of the PZT piezoelectric actuator.

[0076] Upon determining the threat type and location, the response control unit locks onto the location of the repair microcapsule to be activated and applies alternating voltage to both sides of the microcapsule. The PZT piezoelectric actuator generates expansion and contraction vibrations, forming a miniature ultrasonic source. This high-frequency vibration triggers repair through a synergistic mechanism of acoustic cavitation and mechanical resonance: on one hand, the vibration penetrates the thin wall of the microcapsule, generating strong acoustic pressure waves within the encapsulated liquid core. During the negative pressure half-cycle of the sound wave, microcavitation bubbles form inside the liquid; during the positive pressure half-cycle, the cavitation bubbles violently collapse, generating micro-jet shock waves that create enormous circumferential tensile stress on the inner wall of the capsule, forcing the capsule to rupture explosively from the inside out. On the other hand, the high-frequency acoustic wave matches or approaches the natural frequency of the glass microcapsule, inducing strong mechanical resonance. Under the dual action of micro-jet impact and resonant stress, the glass shell rapidly exceeds its fatigue limit, cracking and ultimately shattering. This releases the internal repair agent core material for dynamic repair and defense.

[0077] To address the challenge of independent selection and precise activation of repair microcapsules at pixel nodes, this embodiment employs a phase-inversion differential driving strategy to apply acoustic excitation. Its core principle is based on the linear superposition characteristic of sine waves. The specific driving signal expression is as follows: ,in: V(t) for t The instantaneous voltage applied to the row or column fiber bundle at any given time; V p This refers to the voltage amplitude, i.e., the maximum excitation intensity. f The ultrasonic driving frequency is preferably 20~100 kHz, used to match the mechanical resonant frequency of the glass microcapsules; t This is a time variable. During activation, the central controller applies a positive-phase signal to the target row. Simultaneously, an inverted signal is applied to the target column. That is, the phase difference is 180°. At this time, the potential difference across the target PZT actuator at the intersection is... Its amplitude reaches V p 2 times.

[0078] Based on the square-proportional relationship between electric power and voltage amplitude The voltage amplitude that the target node withstands is Its corresponding driving power is Non-target PZT actuators located in the same row or column only experience unilateral potential changes, with a voltage amplitude of [value missing]. V p Its power is proportional to Therefore, the potential difference amplitude corresponding to the target node is twice that of other nodes in the target row or column, and the vibration energy is four times that of other nodes in the target row or column. The corresponding control unit sets the mechanical fracture threshold of the glass microcapsule to be between... V p The generated vibration stress and 2 V p The generated vibration stresses ensure that only the microcapsules at the target node are broken, while other non-target nodes remain within the safe fatigue limit, effectively eliminating crosstalk malfunctions in matrix addressing.

[0079] To verify the effectiveness of the phase reversal differential driving strategy and the cavitation threshold characteristics of the defense system, this embodiment constructs a macroscopic equivalent physical model for verification.

[0080] To strictly adhere to the physical equivalence principle of "consistent materials and geometric similarity" and ensure the reproducibility of the microscopic mechanism at the macroscopic level, this experiment used a 2 mL standard medical borosilicate glass ampoule as the macroscopic equivalent of the microcapsule. The ampoule's material is consistent with the microcapsules described in the examples (both are brittle borosilicate glass), with a wall thickness of 0.25 mm ± 0.02 mm, accurately simulating the acoustic impedance characteristics and mechanical brittleness of the microcapsule. A 1.0 mol / L sodium hydroxide solution was encapsulated inside the ampoule to simulate an alkaline repair agent. The driving source was a PZT-5 piezoelectric ceramic disc (10 mm in diameter, 1 mm thick), which was bonded to the bottom of the ampoule using conductive silver paste to simulate microscopic curing connections and mechanical coupling. To facilitate observation of the breakdown effect, the entire assembly was completely immersed in an observation tank containing an aqueous solution of transparent phenolphthalein indicator. If the ampoule remains intact, the alkali solution is sealed, and the external water tank remains colorless. In the event of physical breakdown, the released alkali solution comes into contact with phenolphthalein, enabling visual colorimetric determination. To prevent short circuits in the drive circuit due to the underwater conductive environment, electronic-grade insulating epoxy resin is used to locally seal the PZT electrode solder joints and exposed wires after the wire connections are completed. This sealing layer is strictly limited to the thickened area at the bottom of the ampoule, avoiding coverage of the thin side walls to ensure that the mechanical vibration modes and acoustic damping characteristics of the glass sidewalls are not altered.

[0081] Construct a 2×2 analog matrix drive circuit, using a dual-channel function signal generator as the controller, and mapping the two output channels to the rows and columns of the matrix respectively. Drive frequency ( f The reference voltage amplitude was set to 28 kHz, and frequency sweep testing showed that this frequency is close to the natural resonant frequency of the ampoule in its liquid-filled state. V p The voltage is set to 40V. The signal mode is: Channel A analog line drive signal output. Channel B analog column drive signal output phase adjustable signal .

[0082] Set the phase difference of channel B to Simulates the state of a non-target node. At this time, the magnitude of the potential difference across the PZT is... After 60 seconds of continuous power-on, weak ripples were observed in the water surrounding the ampoule in the tank, indicating that the PZT was in a vibrating state. However, the ampoule wall remained intact, and the external phenolphthalein solution showed no color change. Under a single voltage drive of 40V, the mechanical vibration power generated by the PZT was approximately 1.6W, and the alternating stress induced in the glass wall material was lower than the fatigue limit of high borosilicate glass, verifying the safety of the non-target node during long-term monitoring.

[0083] Set the phase difference of channel B to At this point, it is in reverse driving state, simulating the target node state. The sum of the potential difference amplitudes across the PZT is... (i.e. 2) V p At the instant the voltage was applied, numerous fine, grayish-white bubbles were clearly observed inside the ampoule, accompanied by high-frequency noise, confirming the occurrence of endogenous acoustic cavitation. As the internal cavitation bubbles violently collapsed, generating a shock wave, coupled with the mechanical resonance of the casing, the ampoule shattered instantly. The clear phenolphthalein solution outside the ampoule instantly turned red, centered on the ampoule, indicating that the internally encapsulated NaOH solution had been successfully released. This demonstrates that under double voltage, the PZT output power jumped to approximately 6.4W. The enormous circumferential tensile stress generated by this energy difference effectively exceeded the glass's strength threshold, achieving precise, targeted shattering.

[0084] Based on the same inventive concept, the present invention provides a dynamic defense method for durability degradation of reinforced concrete structures, comprising the following steps: (1) An addressable composite fabric network with chemical repair agent and piezoelectric actuator is pre-embedded in a reinforced concrete structure; (2) Set up sensing units on the composite fabric network to identify the pH value, chloride ion concentration and sulfate ion concentration inside the reinforced concrete structure, monitor the health status of the reinforced concrete structure in real time, and draw a health map based on the mapping relationship between the optical fiber path and the composite fabric network. (3) Identify threat types and locations based on monitoring results; determine the row and column addresses of repair microcapsules to be activated based on the location of the threat; and determine the applied voltage level and the number of repair microcapsules to be activated based on the type and level of the threat. (4) Apply an alternating voltage signal exceeding the preset threshold to the node where the repair microcapsule is located to trigger the piezoelectric actuator to generate an ultrasonic sound field or mechanical vibration field. Use acoustic fatigue or mechanical resonance to cause the polymer wall material to break and release the chemical repair agent encapsulated inside, so as to carry out dynamic repair and defense.

[0085] Example 3

[0086] The present invention discloses a dynamic defense system for durability degradation of reinforced concrete structures, comprising a composite fabric network embedded in the reinforced concrete structure and containing a chemical repair agent, a sensing unit disposed on the composite fabric network for monitoring the internal health status of the reinforced concrete structure, and a response control unit for controlling the release of the chemical repair agent based on the monitoring results.

[0087] This embodiment uses a magnetic induction thermal melting triggering mechanism.

[0088] The composite fabric network comprises: a two-dimensional matrix skeleton woven from independently addressable conductive row fiber bundles and conductive column fiber bundles; and a plurality of repair microcapsules disposed at the intersection nodes of the two-dimensional matrix skeleton. Each repair microcapsule contains a thermoplastic wall material sensitive to magnetocaloric effects and an internally encapsulated chemical repair agent for repairing concrete. The repair microcapsules are designed to melt the wall material and release the repair agent by localized magnetic induction when a preset alternating current is applied to the intersection node where they are located.

[0089] The repair microcapsules include type B repair microcapsules that resist corrosion and type C repair microcapsules that resist sulfate attack.

[0090] The core materials of the type B and type C repair microcapsules remain unchanged, consistent with Example 1. The core material of the corrosion-resistant type B microcapsules is an aqueous solution of sodium aluminate, while the core material of the type C repair microcapsules resistant to sulfate attack is an aqueous solution of strontium hydroxide. Both the corrosion-resistant type B and sulfate-resistant type C repair microcapsules use temperature-sensitive low-melting-point materials for their wall materials. In this example, the wall material of the type B and type C repair microcapsules is preferably a modified paraffin composite shell doped with magnetic nanoparticles, and its melting point is set to 80°C to avoid the influence of the heat of hydration of concrete. To improve heating efficiency, superparamagnetic iron(III) oxide (Fe3O4) nanoparticles are uniformly incorporated into the thermoplastic wall material matrix, or high-concentration iron(III) oxide (Fe3O4) nanoparticles are fixed on the outer surface of the wall material. The conductive fiber bundles and column fiber bundles in the composite fabric network are provided with insulating layers; the insulating layers are removed at the intersections to ensure close contact between the conductive core of the fiber bundle and the repair microcapsule wall material. The conductive fiber insulating layer of the composite fabric network is coated with a layer, and the type A repair microcapsules are immobilized on the coating layer. The coating layer uses a porous electrically insulating adhesive, preferably epoxy resin or hydrogel. The type A repair microcapsules include a pH-sensitive modified chitosan-sodium alginate polymer wall material and an internally encapsulated calcium hydroxide concentrated slurry.

[0091] The distributed optical fiber sensing system employs a multimode optical fiber sensing bundle with the same structure as described in Embodiment 1, for high-precision positioning and identification of Cl. - SO4 2- Changes in concentration and pH value.

[0092] The response control unit includes miniature planar spiral induction coils or resistive heating elements disposed at the intersection nodes of the two-dimensional matrix skeleton of the composite fabric network. In this embodiment, an induction coil is preferred. To construct a low-impedance and durable electrical connection, the input and output terminals of the coil are respectively bonded to the conductive cores of the stripped insulating row and column fiber bundles using conductive silver paste or laser micro-welding processes. When the threat type and location are determined, the response control unit locks the location of the repair microcapsule to be activated, and when a preset alternating current is applied to the selected row / column, the current flows through the coil, making it act as a local electromagnetic field emitter.

[0093] Specifically, since the B-type and C-type repair microcapsules are distributed in a known checkerboard pattern on the composite fabric network, the central controller indexes the row and column addresses of the target nodes (e.g., row i, column j) from the database according to the threat type. The central controller connects the conductive fiber bundle in row i to the signal terminal of a preset AC power supply and the conductive fiber bundle in column j to the ground terminal, while placing all non-target rows and columns in a high-impedance floating state. At this time, a preset AC current flows in from row i, passes through the miniature induction coil located at the intersection node (i, j), and finally flows out from column j, forming a closed heating circuit. According to Ampere's law, a highly concentrated, alternating localized magnetic field is generated. This alternating magnetic field causes the Fe3O4 magnetic nanoparticles doped around the microcapsules to rapidly heat up through hysteresis and eddy current losses. The heat generated by the nanoparticles is transferred to the thermoplastic microcapsule wall material they encapsulate via thermal conduction. When the wall material reaches its melting point, it rapidly melts, losing its structural integrity and releasing the internal repair agent core material for dynamic repair and defense. Meanwhile, adjacent nodes, lacking a main circuit current (or with only a weak leakage current), maintain their temperature below the melting point, preserving their structural integrity. Thus, the system achieves independent and precise thermal activation of type B and type C microcapsules. In this embodiment, the frequency of the preset alternating current is preferably between 100 kHz and 1 MHz to ensure that the magnetic nanoparticles can generate sufficient magnetocaloric effect.

[0094] The response control unit controls the heating dosage by adjusting the power or duration of the input alternating current. Instead of relying on physical temperature sensors, the response control unit uses the aforementioned sensing units to monitor the decreasing trend of harmful ion concentration in the target area within a predetermined time window, serving as a functional closed-loop verification signal to determine whether the remedial agent has been successfully released and is functioning.

[0095] To verify the effectiveness and thermal response speed of the magnetic induction thermal melting addressing strategy, this embodiment uses modified microcrystalline wax with a melting point controlled to 80℃ and 15wt% Fe3O4 nanoparticles to prepare a 0.5 mm thick magnetic paraffin composite sheet to simulate the repair of microcapsule wall materials. This sheet is then placed over a 5 mm diameter planar spiral coil on a printed circuit board. The coil is connected to a signal generator and a power amplifier. When the coil is not energized or a low-frequency current (50 Hz, 1 A) is applied, the surface temperature of the sheet remains at room temperature, and its morphology does not change, verifying the stability of the system under non-operating conditions or power frequency interference. When a preset AC current (200 kHz, 1 A) is applied to the coil, an infrared thermal imager shows that the temperature in the central region of the coil rises from 25℃ to 85℃ within 3 minutes. Subsequently, the center of the magnetic paraffin sheet begins to soften, becomes transparent, and eventually melts into droplets, forming a physical channel.

[0096] Based on the same inventive concept, the present invention provides a dynamic defense method for durability degradation of reinforced concrete structures, comprising the following steps: (1) An addressable composite fabric network containing chemical repair agents and induction coils or resistive heating elements is pre-embedded in a reinforced concrete structure; (2) Set up sensing units on the composite fabric network to identify the pH value, chloride ion concentration and sulfate ion concentration inside the reinforced concrete structure, monitor the health status of the reinforced concrete structure in real time, and draw a health map based on the mapping relationship between the optical fiber path and the composite fabric network. (3) Identify threat types and locations based on monitoring results; determine the row and column addresses of repair microcapsules to be activated based on the location of the threat; and determine the applied voltage level and the number of repair microcapsules to be activated based on the type and level of the threat. (4) Apply an alternating current signal exceeding the preset threshold to the node where the repair microcapsule is located, triggering the induction coil or resistive heating element to generate an alternating magnetic field or thermal field. Use electromagnetic induction heating or resistive heating to raise the temperature of the polymer wall material to the melting point, causing a phase change and melting to release the chemical repair agent encapsulated inside, thus performing dynamic repair and defense.

Claims

1. A dynamic defense system for durability degradation of reinforced concrete structures, characterized in that, It includes a composite fabric network embedded in a reinforced concrete structure with chemical repair agent, a sensing unit on the composite fabric network for monitoring the internal health status of the reinforced concrete structure, and a response control unit for controlling the release of chemical repair agent based on the monitoring results. The composite fabric network includes a two-dimensional matrix skeleton woven from independently addressable conductive row fiber bundles and conductive column fiber bundles. At the intersection nodes of the two-dimensional matrix skeleton, several repair microcapsules containing chemical repair agents encapsulated in specific sensitive polymer wall materials are placed. Functional execution components are added as needed at the nodes where the repair microcapsules are located. Based on monitoring results, the response control unit applies excitation signals exceeding preset thresholds to the row and column fiber bundles of the target node, generating or triggering the functional execution components to form a corresponding external excitation energy field acting on the sensitive polymer wall material of the repair microcapsules. This causes the polymer wall material to crack or undergo a phase change, thereby releasing the chemical repair agent and achieving dynamic defense against the degradation of the durability of reinforced concrete structures.

2. The dynamic defense system for durability degradation of reinforced concrete structures according to claim 1, characterized in that, The repair microcapsule encapsulates a chemical repair agent in a polymer wall material that is sensitive to a preset threshold voltage. Without adding functional execution components, the response control unit generates a high-voltage electric field by applying a pulse high-voltage signal exceeding the preset threshold to the row and column fiber bundles of the target node based on the monitoring results. The polymer wall material is then broken by utilizing the dielectric breakdown effect or the electron avalanche effect.

3. The dynamic defense system for durability degradation of reinforced concrete structures according to claim 1, characterized in that, The repair microcapsule encapsulates a chemical repair agent in a polymer wall material that is sensitive to mechanical impact. The added functional execution component is a piezoelectric actuator. The response control unit, based on the monitoring results, applies an alternating voltage signal exceeding a preset threshold to the row and column fiber bundles of the target node, triggering the piezoelectric actuator to generate an ultrasonic sound field or mechanical vibration field, thereby causing the polymer wall material to crack through acoustic fatigue or mechanical resonance.

4. The dynamic defense system for durability degradation of reinforced concrete structures according to claim 1, characterized in that, The repair microcapsule encapsulates a chemical repair agent using a polymer wall material sensitive to the magnetocaloric effect. The added functional execution component is an induction coil or a resistance heating element. The response control unit, based on the monitoring results, applies an alternating current signal exceeding a preset threshold to the row and column fiber bundles of the target node, triggering the functional execution component to generate an alternating magnetic field or thermal field. The polymer wall material temperature is raised to the melting point and undergoes a phase change melting by using electromagnetic induction heating or resistance heating.

5. The dynamic defense system for durability degradation of reinforced concrete structures according to claim 1, characterized in that, The repair microcapsules include at least type B repair microcapsules that resist corrosion and type C repair microcapsules that resist sulfate attack. Several type B repair microcapsules and several type C repair microcapsules are respectively disposed on different nodes of the composite fabric network. The nodes on the composite fabric network where type B repair microcapsules are disposed are called type B pixel nodes, and the nodes where type C repair microcapsules are disposed are called type C pixel nodes. The type B pixel nodes and type C pixel nodes are arranged adjacent to each other on the composite fabric network in a checkerboard pattern.

6. The dynamic defense system for durability degradation of reinforced concrete structures according to claim 5, characterized in that, The corrosion-resistant type B repair microcapsules are internally encapsulated with a chloride ion fixative; the sulfate-resistant type C repair microcapsules are internally encapsulated with a strontium hydroxide aqueous solution.

7. The dynamic defense system for durability degradation of reinforced concrete structures according to claim 1, characterized in that, The repair microcapsule also includes a carbonization-resistant type A repair microcapsule, and a coating layer is provided on the insulating layer covering the composite fabric network, with the type A repair microcapsule disposed in the coating layer.

8. The dynamic defense system for durability degradation of reinforced concrete structures according to claim 7, characterized in that, The type A repair microcapsule comprises a pH-sensitive chitosan polymer wall material and internally encapsulated calcium hydroxide.

9. The dynamic defense system for durability degradation of reinforced concrete structures according to claim 1, characterized in that, The sensing unit employs a distributed optical fiber sensing system, which is an integrated sensing fiber bundle woven into a composite fabric network and passing through all nodes. It includes at least a pH value identification probe, a chloride ion identification probe, a sulfate ion identification probe, and a host, and is used to monitor the pH value, chloride ion concentration, and sulfate ion concentration corresponding to the node coordinates on the optical fiber path.

10. A dynamic defense method for a dynamic defense system for durability degradation of reinforced concrete structures according to any one of claims 1-9, characterized in that, Includes the following steps: (1) An addressable composite fabric network with repair microcapsules is pre-embedded in a reinforced concrete structure; (2) Set up sensing units on the composite fabric network to monitor the health status of the reinforced concrete structure in real time and draw a health map based on the mapping relationship between the optical fiber path and the composite fabric network. (3) Identify threat types and locations based on monitoring results; determine the row and column addresses of repair microcapsules to be activated based on the location of the threat; and determine the intensity of the excitation signal and the number of repair microcapsules to be activated based on the type and level of the threat. (4) Apply an excitation signal exceeding a preset threshold to the node where the repair microcapsule is located to generate an external excitation energy field at the node, causing the wall material of the repair microcapsule to undergo physical rupture or phase change to release the chemical repair agent encapsulated inside, thereby performing dynamic repair and defense.

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