Array permanent magnet and electrochemical impedance synchronous detection device and method for steel bar corrosion in concrete

Abstract

This invention discloses a synchronous detection device for arrayed permanent magnet and electrochemical impedance spectroscopy (EIS) of steel reinforcement corrosion in concrete, belonging to the field of electronic digital data processing technology. It is suitable for non-destructive testing of concrete structure corrosion in structural health assessment. The device includes at least one sub-detection mechanism. Each sub-detection mechanism comprises a unit frame and, from front to back, a permanent magnet probe, a main wheel, an electrical control box, and wheel-type electrodes arranged sequentially on the unit frame. The permanent magnet probe consists of a permanent magnet and a magnetic coil; the wheel-type electrodes consist of a transmitting electrode and a receiving electrode. The electrical control box is communicatively connected to both the permanent magnet probe and the wheel-type electrodes, and consists of an analog wireless acquisition module, an AC impedance analyzer, and electrode control valves. This device uses a permanent magnet perturbation method to identify the spatial distribution of corrosion state, and then combines this with the dynamic feature extraction of the AC polarization impedance method to quantitatively calculate the corrosion current and corrosion rate. The combination of these two methods allows for the synchronous acquisition and integrated assessment of the amount and rate of steel reinforcement corrosion without damaging the concrete structure. This invention also discloses a method for synchronous detection of arrayed permanent magnet and electrochemical impedance spectroscopy (EIS) of steel reinforcement corrosion in concrete.

Description

Technical Field

[0001] This invention belongs to the field of electronic digital data processing technology and is applicable to the detection of corrosion damage in concrete structures for structural health assessment, especially rapid non-destructive testing of bridge structures. Specifically, it relates to an array permanent magnet and electrochemical impedance synchronous detection device and method for detecting steel reinforcement corrosion in concrete. Background Technology

[0002] Reinforced concrete structures are inevitably subjected to environmental and load coupling effects during service. Once the internal reinforcing steel corrodes, it significantly weakens the structure's bending, shear, and seismic resistance. For example, steel corrosion causes a reduction in cross-sectional area and a decline in mechanical properties, thus affecting the load-bearing capacity of concrete members and seriously threatening overall safety and durability. Therefore, steel corrosion is one of the key factors leading to structural deterioration. Because early-stage corrosion is highly concealed, it is usually only discovered when cracks appear on the concrete surface or corrosion products seep out. Therefore, conventional methods relying on macroscopic phenomena such as surface cracks and rust seepage often miss the optimal intervention window. However, existing detection methods are mostly limited to qualitative judgment and cannot meet the needs of quantitative assessment of the degree and extent of corrosion in engineering practice. There is an urgent need to develop efficient and reliable non-destructive testing technologies and equipment. Therefore, developing efficient and accurate non-destructive testing methods is crucial for the maintenance of large concrete structures such as bridges.

[0003] Current methods for detecting steel reinforcement corrosion mainly rely on electrochemical and magnetic methods. Electrochemical methods (such as half-cell potential method, linear polarization resistance method, and AC impedance spectroscopy) can effectively reflect the electrochemical activity and rate of steel reinforcement corrosion. A common practice is to use the half-cell potential method for large-area rapid scanning to initially locate the active corrosion region, and then use the linear polarization method or electrochemical impedance spectroscopy for quantitative assessment in key areas. Patent CN219758135U, through the structural integration of device functions, enables a single device to perform measurements of multiple electrochemical indicators, improving operational convenience. However, in practical applications, the results of electrochemical methods are easily affected by factors such as environmental humidity, temperature, and electrode contact conditions. Except for the half-cell potential method, which can reflect the corrosion state, other methods are mostly used to determine the corrosion rate, making it difficult to achieve precise quantification of the corrosion amount. In other words, most methods cannot achieve continuous non-destructive testing and can only provide information on the "corrosion rate."

[0004] Magnetic methods, based on the principle of changes in magnetic resistance or distortion of the leakage magnetic field at defects in ferromagnetic steel bars, can identify cross-sectional damage to steel bars without contact and obtain information on cumulative corrosion. However, limited by the thickness of the protective layer and the lifting height, the detection results often suffer from insufficient resolution and limited quantitative capabilities. Patent CN119534613A, based on the principle that ferromagnetic materials generate leakage magnetic fields at defects, uses magnetized components and Hall elements to sense the magnetic field signal, which can accurately detect shallow damage to steel pipes and steel components. However, due to the significant attenuation of the magnetic field in non-ferromagnetic media, the leakage magnetic signal weakens exponentially away from the surface of the steel component. Therefore, due to the isolation of the concrete protective layer, this method has limited ability to detect and assess the corrosion state of steel bars within concrete. When the concrete protective layer is thick, the leakage magnetic signal is weak, making it difficult to meet the needs of accurate assessment of steel bar corrosion within concrete.

[0005] In other words, electrochemical methods can dynamically reflect the "velocity" of corrosion (i.e., corrosion rate), while magnetic methods statically reveal the "state" of corrosion (i.e., cumulative corrosion amount). A single method is insufficient to comprehensively characterize the corrosion process, potentially underestimating potential risks or leading to misjudgments. Simultaneous data collection and joint analysis of both methods, providing a comprehensive characterization of the corrosion process from both dynamic and static dimensions, not only complements each other in quantification but also reveals the development patterns of steel reinforcement corrosion from both "velocity" and "state" dimensions, thereby significantly improving the accuracy and reliability of detection.

[0006] In summary, the core problem of existing technologies lies in how to develop an integrated non-destructive testing method that can simultaneously acquire the rate and state of steel reinforcement corrosion, and to provide a high-efficiency and stable mechanical scanning system, so as to achieve rapid and reliable assessment of steel reinforcement corrosion inside bridges in complex service environments, and provide key technical support for accurate determination of bearing capacity and maintenance decisions. Summary of the Invention

[0007] In view of this, the purpose of this invention is to provide an array permanent magnet and electrochemical impedance synchronous detection device and method for steel reinforcement corrosion in concrete. The aim is to effectively solve the problems of mechanized non-destructive corrosion detection and accurate quantification of damage in concrete structures, to address the applicability of the permanent magnet perturbation method at large lifting heights, to avoid signal distortion caused by vibrations in the lifting height of the detection end during the detection process, and to non-destructively and continuously measure the electrochemical impedance of the steel reinforcement, thereby quantifying the total amount of steel reinforcement corrosion within the cross-section of concrete components and providing a basis for assessing the cross-sectional bearing capacity and lifespan of concrete components.

[0008] This invention proposes a combined magneto-electric assessment approach: it overcomes the limitations of traditional magnetic flux leakage detection in terms of lifting height and deep rebar location by using permanent magnet perturbation, enabling spatial distribution identification of corrosion states; and then combines this with dynamic feature extraction using AC polarization impedance spectroscopy to quantitatively calculate corrosion current and corrosion rate. This combined approach allows for the simultaneous acquisition and integrated assessment of rebar corrosion amount and rate without damaging the concrete structure. This device and method not only enhance the scientific rigor of the detection results but also provide solid data support for subsequent structural performance evaluation and life prediction.

[0009] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a synchronous detection device for arrayed permanent magnet and electrochemical impedance spectroscopy (EIS) for detecting steel reinforcement corrosion within concrete. The device includes at least one sub-detection mechanism. Each sub-detection mechanism comprises a unit frame and, from front to back, a permanent magnet probe, a main wheel, an electrical control box, and wheeled electrodes arranged sequentially on the unit frame. The unit frame provides support and is designed for easy movement on the concrete surface. The permanent magnet probe identifies the depth and width of steel reinforcement corrosion within the concrete based on voltage signals and consists of a permanent magnet and a magnetic coil wound around the permanent magnet. The wheeled electrodes are used to conform to the concrete surface and conduct current paths between the concrete surface and the steel reinforcement within the concrete. They consist of several sets of transmitting and receiving electrodes arranged side-by-side, each set having a front-to-back spacing, forming a conductive path that allows detection of corrosion between the concrete and the internal steel reinforcement. The device energizes the reinforcing bars to acquire current signals for assessing corrosion. The electrical control box, connected to the permanent magnet probe and wheeled electrodes for communication and data transmission, comprises an analog wireless acquisition module, an AC impedance analyzer, and electrode control valves. The analog wireless acquisition module acquires and transmits voltage signals from the permanent magnet probe. The electrode control valves control the switching of any single set of transmitting and receiving electrodes in the wheeled electrodes, ensuring flexibility and selectivity. The AC impedance analyzer transmits a composite high-frequency and low-frequency current signal, which passes sequentially through the transmitting electrode, the reinforcing bar, and the receiving electrode to measure the voltage signal between the two electrodes, thus measuring the AC impedance to assess corrosion. The main wheel, supported by a unit frame, moves longitudinally along the reinforcing bars on the concrete surface, ensuring smooth operation of all detection components. During testing, the main wheel, supported by the unit frame, moves longitudinally along the reinforcing bars on the concrete surface. The entire device acquires corrosion-related data of the reinforcing bars within the concrete during this process, and obtains voltage signals for corrosion depth and width through the permanent magnet probe. The wheeled electrodes monitor current changes between themselves and the reinforcing bars, while the electrical control box coordinates the data and processes the current signals. By adopting the above scheme, this device, through the combination of permanent magnet and electrochemical impedance detection methods, can achieve simultaneous assessment of the amount and rate of steel corrosion without damaging the concrete structure.

[0010] Optionally, the permanent magnet probe also includes a first shielding cover to protect the sensitive elements inside the permanent magnet probe and prevent external electromagnetic waves from interfering with the probe signal, thereby improving the accuracy and stability of the measurement; while the electrical control box also includes a second shielding cover to prevent external electromagnetic interference and also to prevent electromagnetic radiation inside the control box from affecting other equipment, ensuring the reliability of the overall system.

[0011] Optionally, the permanent magnet probe also includes a magnetizer positioned on top of the permanent magnet to stabilize the voltage signal of the magnetic coil. This magnetizer helps stabilize the magnetic field generated by the permanent magnet, preventing external factors from interfering with the magnetic field strength and direction, thus ensuring the accuracy of the voltage signal measured by the magnetic coil. Simultaneously, the magnetizer effectively enhances signal strength, improves the signal-to-noise ratio, and makes the voltage signal clearer, facilitating subsequent data processing and analysis.

[0012] Optionally, the wheeled electrode also includes a wheel frame, wheel frame linkages, and shock absorbers. Two parallel wheel frames are arranged at intervals on the unit frame via shock absorbers to improve overall stability and space utilization. The shock absorbers are designed to reduce the impact of vibration on the electrodes during operation, ensuring measurement accuracy under different terrains and conditions. They effectively absorb shocks and vibrations, enhancing the system's durability. The two wheel frames are connected by multiple wheel frame linkages, providing structural integrity and strength, while allowing adjustment of the distance between the two wheel frames to meet different operational needs. One wheel frame houses multiple transmitting electrodes arranged in a linear interval, while the other wheel frame houses multiple receiving electrodes arranged in a linear interval, corresponding one-to-one with the transmitting electrodes. The wheel frame supports the transmitting and receiving electrodes, ensuring they are stably held in the correct position. Each individual transmitting and receiving electrode has its hub mounted on its corresponding wheel frame via its own independent axle, allowing each electrode to move relatively independently during operation. Tires are fitted onto the hubs to provide appropriate grip and shock absorption, enabling smooth system movement.

[0013] Optionally, the electrical control box also includes an amplifier and a filter. The amplifier's main function is to amplify the weak voltage signal generated by the magnetic coil. When receiving signals, the magnetic coil often produces a very small voltage, which may be difficult to detect effectively in subsequent signal processing or data analysis. The filter removes noise and unwanted frequency components from the magnetic coil voltage signal, retaining the useful signal. In this way, the amplifier and filter in the electrical control box work together to significantly improve signal quality, making subsequent data acquisition, processing, and display more accurate. This is a crucial step in ensuring measurement accuracy and signal clarity.

[0014] Optionally, the unit frame also includes nozzles and a water tank. The electrical control box further includes an electrolyte controller. The nozzles are connected to the water tank via the electrolyte controller. The nozzles' function is to spray water or electrolyte at a certain pressure and with a spraying or atomizing effect to meet specific technical requirements. The water tank stores the water or electrolyte medium, ensuring a sufficient supply for normal system operation. The electrolyte controller manages the liquid flow in the water tank. Thus, by combining the nozzles, water tank, and electrolyte controller into a single system, automated control is achieved.

[0015] Optionally, a connecting lug is provided at each of the four top corners of the unit frame; multiple bolting parts are provided on both sides of the unit frame; multiple sub-detection mechanisms are arranged in a linear array, which can ensure that the detection system covers a wider area and improve detection efficiency. Multiple connecting lugs on the same axis are connected in series by a crossbeam, which can reduce mutual interference between sub-detection mechanisms, ensuring that they work in the same axis. Furthermore, the bolting parts of adjacent sub-detection mechanisms on their corresponding facing sides are connected by a bridging rod, enhancing structural stability and preventing deformation or loosening during operation. Thus, this structural design aims to improve the modularity and scalability of the system, making assembly, maintenance, and upgrades more convenient and efficient.

[0016] This invention also provides a method for simultaneous detection of steel reinforcement corrosion in concrete using arrayed permanent magnet and electrochemical impedance spectroscopy. The method employs the aforementioned device for simultaneous detection of steel reinforcement corrosion in concrete using arrayed permanent magnet and electrochemical impedance spectroscopy, and includes the following steps: S1) Defect calibration of the detection device; a series of reinforced concrete specimens with equidistant step lengths and different corrosion depths are made, and a single sub-detection mechanism is used to scan along the longitudinal direction of the steel bars in each reinforced concrete specimen one by one at the same scanning speed to record the voltage signal amplitude output by the magnetic coil of the permanent magnet probe under different corrosion depth conditions, so as to establish the calibration relationship of "voltage amplitude-corrosion depth"; while the corrosion width is confirmed by the width of the defect voltage signal in the magnetic coil. S2) According to the detection requirements, multiple sub-detection mechanisms are assembled into a linear array and, with the assistance of a sliding rail mechanism set on the concrete surface to be tested, move at a constant speed to carry out permanent magnet disturbance scanning, and electrolyte is sprayed evenly on the concrete surface; during this process, the permanent magnet probes of multiple sub-detection mechanisms work synchronously, and the collected voltage signals are amplified, filtered and processed by wireless analog signal acquisition in sequence before being transmitted to the computer for storage. S3) The voltage signals collected by the permanent magnet probes of multiple sub-detection mechanisms arranged in a line are time-domain aligned and superimposed by the computer to determine the location of the rust cross section, and the amount of rust is jointly judged by combining the "voltage amplitude-corrosion depth" calibration relationship and the identification of the width of missing voltage signals. S4) Then, the wheel electrodes of multiple sub-detection mechanisms are controlled by the sliding rail mechanism to stop at the defect starting position of the permanent magnet disturbance judgment, and AC polarization impedance measurement is performed at that position; under the control of computer instructions, the AC impedance analyzer is started to emit high-frequency and low-frequency composite current signals in sequence, and the voltage signal fed back by the wheel electrodes is collected simultaneously and transmitted to the computer for storage. S5) When the transmitting electrode outputs signal v(n), the receiving electrode synchronously receives signal i(n), and then uses Fourier transform to convert the time domain signals of current and voltage into frequency domain signals to draw Nyquist plot. (1) (2) By comparing the values ​​of two sets of signals recorded at the same time at different frequencies, the complex impedance is: (3) in, For voltage signal phase, The phase of the current signal; The Nyquist plot coordinates (Z', -Z'') represent the real and imaginary parts of Z, respectively; the polarization resistance R is then extracted from the Nyquist plot. p The Srern-Geary constant B was determined by combining the corrosion stages obtained from permanent magnet perturbation, and then the corrosion current density i was calculated using the Stern-Geary equation. corr ; (4) Where B is an empirical constant; According to Faraday's law, the mass of dissolved Fe per unit area per unit time is converted into the rate of steel bar section reduction, i.e., the corrosion rate, and then calculated using the following formula: (5) Among them, v loss The corrosion rate is given by M (mm / year); M is the molar mass of the steel bar; n is the number of electrons reacted; F ≈ 96485 C / mol. Reinforcing steel density; S6) Input the amount and rate of corrosion at different cross-sectional locations into a classifier that has been trained in advance based on electrochemical and magnetic measurement methods under different corrosion levels, so as to achieve a joint determination of the overall corrosion state.

[0017] Preferably, in step S1), for the unprepared intermediate corrosion depth value, the corresponding calibration result is obtained by linear interpolation.

[0018] Preferably, in step S6), the classifier is a support vector machine (SVM).

[0019] The present invention has the following beneficial effects: The present invention provides a synchronous detection device for arrayed permanent magnet and electrochemical impedance spectroscopy for detecting steel corrosion in concrete. This device solves the problems of the lifting height limitation of magnetic measurement method for reinforced concrete, signal distortion caused by jitter of the lifting height of the detection end during the detection process, and how to continuously measure the steel impedance without damage.

[0020] The present invention provides a synchronous detection device for array permanent magnet and electrochemical impedance spectroscopy for steel reinforcement corrosion in concrete. This device eliminates the need for detecting leakage magnetic fields and senses the presence of steel reinforcement corrosion in concrete by detecting changes in magnetic circuit reluctance. It can effectively overcome the lift height limitation simply by establishing an effective magnetic circuit between the permanent magnet and the steel reinforcement.

[0021] The present invention provides a synchronous detection device for arrayed permanent magnet and electrochemical impedance spectroscopy for steel reinforcement corrosion in concrete. It uses electrochemical and magnetic methods to simultaneously collect and jointly evaluate the corrosion status of steel reinforcement in concrete, realizing full-section acquisition of steel reinforcement corrosion status data in concrete beams and comprehensively evaluating the corrosion status of steel reinforcement in the section, thus avoiding signal interference from surrounding steel reinforcement when detecting and evaluating the corrosion status of a single steel reinforcement.

[0022] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0023] To make the objectives, technical solutions, and advantages of the present invention clearer, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein: Figure 1 This is a three-dimensional assembly structure diagram of the concrete steel corrosion detection device for synchronous detection of array permanent magnet and electrochemical impedance according to the present invention. Figure 2 for Figure 1 A side view of a single permanent magnet probe in a diagram; Figure 3 for Figure 2 A top-down view; Figure 4 for Figure 2 AA diagram in the image; Figure 5 for Figure 2 BB diagram in the middle; Figure 6 for Figure 1 A schematic diagram of the electrical control box in the diagram; Figure 7Let h be the probability of each durability stage under varying h conditions (considering only h); Figure 8 The probabilities of each durability stage under varying h conditions (considering all factors) ); Figure 9 I Probabilities of each durability stage under changing conditions (considering only) ); Figure 10 for Probabilities of each durability stage under changing conditions (considering all factors) ).

[0024] Reference numerals: 1. Permanent magnet probe; 2. Electrical control box; 3. Wheel electrode; 4. Nozzle; 5. Water tank; 6. Main wheel; 7. Unit frame; 8. Bridging link; 101. First shield; 102. Permanent magnet; 103. Magnetic coil; 104. Magnetizer; 201. Second shield; 202. Amplifier; 203. Filter; 204. Analog wireless acquisition module; 205. Electrolyte controller; 206. AC impedance analyzer; 207. Electrode control valve; 301. Axle; 302. Hub; 303. Tire; 304. Wheel frame; 305. Wheel frame link; 306. Wheel frame shock absorber; 307. Transmitting electrode; 308. Receiving electrode; 701. Connecting lug; 702. Detailed Implementation

[0025] The present invention will be further described below with reference to specific embodiments. The accompanying drawings are for illustrative purposes only, representing schematic diagrams rather than actual physical objects, and should not be construed as limiting the scope of this patent. To better illustrate the embodiments of the present invention, some components in the drawings may be omitted, enlarged, or reduced, and do not represent the actual dimensions of the product. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0026] Please see Figure 1-6 As shown in this embodiment, the array permanent magnet and electrochemical impedance synchronous detection device for steel corrosion in concrete is based on the principle of permanent magnet disturbance detection technology using an equivalent magnetic circuit model. It uses magnetic field disturbance to quantitatively detect defects in ferromagnetic materials (such as steel bars) and achieves quantitative evaluation by establishing a physical and mathematical model between defect size and induced voltage.

[0027] Specifically, during the service life of a concrete beam, the mid-span pure bending section is generally the first location where corrosion begins to develop due to the coupling effect of environmental loads. Furthermore, due to the structural characteristics of concrete beams, the mid-span reinforcing bars (steel strands) need to be neatly arranged at the maximum distance from the lower edge of the beam to maximize the utilization of material properties. When a magnetic circuit is established between the permanent magnet and the reinforcing bar, because magnetic energy tends towards the bottom potential and the magnetic field lines are closed, if the bottom magnetic pole of the permanent magnet 102 of this device remains on the same plane as the surface of the reinforcing bar and moves at a constant speed along the longitudinal direction of the reinforcing bar, the magnetic field lines will start from the bottom of the permanent magnet 102, pass through the air, concrete, reinforcing bar, concrete again, air, and then return to the top magnetic pole. If the permanent magnet 102 moves in a non-corroded beam segment, the magnetic field lines will remain stable due to the equivalence of the magnetic circuits between the various components, and the magnetic coil 103 will not generate an induced voltage in this case. If steel reinforcement corrosion occurs during the scanning process, the air domain and corrosion products between the permanent magnet 102 and the steel reinforcement in the magnetic circuit will increase. This will increase the magnetic reluctance of the magnetic circuit, resulting in magnetic circuit reconstruction (mainly near the steel reinforcement). It should be noted that because the air domain below the permanent magnet 102 becomes thicker, the permeability of air is much lower than that of steel reinforcement, and the damage caused by corrosion in the concrete beam is relatively wide. Therefore, passing through the thickened air to reach the steel reinforcement interface is still the shortest path for the magnetic field lines. However, in the subsequent path, the distribution of the magnetic circuit in the air domain is mainly controlled by the magnetic field range of the permanent magnet 102. Therefore, the overall change in the magnetic circuit during the entire process is mainly concentrated on the change in magnetic reluctance caused by the increase in air gap. By adding a magnetizer 104 to the upper part of the permanent magnet 102, the magnetic field lines at the tail of the magnetic circuit can be restricted to maintain a more stable route, thereby enhancing the stability of the induced voltage. Furthermore, by using a stainless steel first shield 101 outside the permanent magnet probe 1 and its magnet coil 103, the interference of the external magnetic field on the induced signal can be reduced.

[0028] Based on the above principle, when the permanent magnet probe 1 passes over the defect, the induced voltage signal generated by its magnetic coil 103 will be amplified by the amplifier 202 of the electrical control box 2, and then filtered out by the filter 203 to remove low-frequency components caused by subtle changes in the position of the rebar and similar reasons, as well as high-frequency white noise components introduced by signal acquisition. The signal is then transmitted to the computer (PC) for storage via the analog wireless acquisition module 204. Note that to prevent mutual interference between the current of the electrical control box 2 and the current of the permanent magnet probe 1, the electrical control box 2 is placed at least 50mm away from the permanent magnet probe 1 and is equipped with a second shielding cover 201.

[0029] Simultaneously, the computer wirelessly controls the electrolyte controller 205 to spray water or electrolyte medium through the wired nozzle 4, creating a reliable environment for polarization resistance detection. During polarization resistance detection, the wheeled electrode 3 is positioned at the center of the suspected corrosion location. The computer issues a command to control the electrode control valve 207 to connect a set of wheeled electrodes 3 (transmitting electrode 307 and receiving electrode 308). Subsequently, the computer issues a command to cause the AC impedance analyzer 206 to emit a current signal that travels through the electrode control valve 207 to the reinforcing bar. The feedback voltage signal is received by the AC impedance analyzer 206 and wirelessly transmitted back to the computer.

[0030] In this example, the main wheel 6 is positioned close to the permanent magnet probe 1, the wheel electrode 3 is positioned away from the permanent magnet probe 1, and the electrical control box 2 is positioned close to the wheel electrode 3; the water tank 5 is arranged on the opposite side of the electrical control box 2 and the permanent magnet probe 1, and is located above the wheel electrode 3.

[0031] The reason why the permanent magnet disturbance method can detect corrosion even at a relatively large lifting height is that the voltage sensing signal is highly sensitive to the spatial relative position between the permanent magnet 102 and the reinforcing bar. Therefore, it is necessary to avoid vertical bumps caused during measurement. To solve this problem, this device uses bridging rods 8 to combine and connect multiple unit frames 7, and arranges them in a straight array on a slide rail mechanism (such as a linear guide or sliding guide, not shown), and operates stably through the slide rail mechanism. Among them, the connecting ear 701 set on each unit frame 7 requires an integrated crossbeam to increase the overall rigidity of the combined device and prevent vibration. It is the main force-bearing component connecting multiple unit frames 7, and the connecting ear 701 can also be conveniently used for handling or hoisting. The bolted part 702 is an auxiliary force-bearing connection component of the bridging rod 8. At the same time, the bridging rod 8 has a telescopic structure to adapt to the spacing between two adjacent sub-detection mechanisms. In this way, the induced voltage signal of the same section of the concrete of the beam is collected by a linear array, so as to eliminate the random error caused by friction between the measuring instrument and the beam through statistical averaging.

[0032] The non-contact AC polarized impedance method applies high-frequency and low-frequency signals to concrete simultaneously through transmitting electrodes. The high-frequency signal establishes a bridge, allowing the low-frequency signal to penetrate the concrete more easily, thus achieving true non-destructive testing. To ensure the stability of the permanent magnet scanning method while maintaining electrode contact with the beam surface, this device utilizes wheeled electrodes 3 with front and rear rows of transmitting electrodes 307 and receiving electrodes 308, and incorporates wheel frame shock absorbers 306. These absorbents and buffer the movement of the unit frame 7, and, in conjunction with the weight of the sub-detection mechanism, better contact the concrete surface and assist the movement of the main wheel 6. Copper is preferably used as the electrode material, i.e., copper is used for the wheel hub 302. To ensure good contact between the electrodes and concrete, the tires 303 are made of water-absorbing and wear-resistant material. It is worth noting that the wheel hub 302 and tires 303 need to be widened, but not exceeding the transverse spacing of the reinforcing bars in the mid-span. Specifically, the front and rear rows of transmitting electrodes 307 and receiving electrodes 308 along the longitudinal direction of the reinforcing bars only cover one reinforcing bar, in order to improve signal strength. To enhance signal stability and prevent crosstalk between multiple electrodes or circuit disruption caused by the formation of pathways between other electrodes after signal transmission, an insulated wheel frame 304 and an independent axle 301 are required. An electrode control valve 207 ensures that each electrode is isolated from the others. It is important to note that the main wheel 6 is an insulated tire. To ensure proper pathway formation, the two types of electrodes (transmitting electrode 307 and receiving electrode 308) should be spaced 50 mm apart. To adapt to different operating conditions, an adjustable wheel frame connecting rod 305 is used, meaning this connecting rod 305 has a telescopic structure. Finally, pre-wetting the concrete can improve the signal-to-noise ratio; therefore, this device is equipped with a water tank 5 and a nozzle 4 to spray the electrolyte medium.

[0033] The calculation method for corrosion rate measurement using the non-contact AC impedance method is the same as that of the general impedance method. When the transmitting electrode outputs a signal v(n), the receiving electrode simultaneously receives a signal i(n). Then, V(f) can be obtained through Fourier transform. k ) and I(f k ): (1) (2) By comparing the values ​​of two sets of signals recorded at the same time at different frequencies, the complex impedance is: (3) in, For voltage signal phase, This represents the phase of the current signal.

[0034] The Nyquist plot coordinates (Z', -Z'') represent the real and imaginary parts of Z, respectively. Furthermore, the polarization resistance R of the reinforcing steel can be obtained from the Nyquist plot. pAnd from the Srern-Geary relationship, the corrosion current density can be obtained as: (4) Where B is an empirical constant, typically taken as 52mV for the passivation stage and 26mV for the active corrosion stage.

[0035] According to Faraday's law, the amount of charge passing per unit area per unit time can be converted into the mass of dissolved Fe, and then into the rate of steel bar section reduction. Therefore, the corrosion rate can be calculated using the following formula: (5) Among them, v loss The corrosion rate is M (mm / year); M is the molar mass of the steel bar; n is the number of electrons in the reaction, usually taken as 2; F≈96485C / mol; This refers to the density of the reinforcing steel.

[0036] The specific working principle of this array permanent magnet and electrochemical impedance synchronous detection device for detecting steel corrosion in concrete is as follows: First, the detection device was calibrated in the laboratory. A series of steel reinforcement specimens with corrosion depths ranging from 0.5 to 5.0 mm and step sizes of 0.5 mm were prepared. Based on the thickness of the protective layer of the steel reinforcement in the beam to be tested, each calibration specimen was placed at the same height as the thickness of the protective layer. Then, a single sub-detection mechanism was used to scan along the steel reinforcement direction one by one at the same and appropriate scanning speed to record the voltage signal amplitude output by the magnetic coil 103 of the permanent magnet probe 1 under different corrosion depth conditions, and a calibration relationship of "voltage amplitude - corrosion depth" was established. For intermediate corrosion depth values ​​that were not prepared, the corresponding calibration results were obtained through linear interpolation. Furthermore, the corrosion width was determined by the width of the defect voltage signal in the magnetic coil 103.

[0037] Secondly, according to the detection requirements, multiple sub-detection mechanisms are assembled into a linear array, and the slide rail mechanism is fixed at the position of the beam segment to be tested, ensuring that the main wheel 6 is in close contact with the surface of the beam bottom plate to ensure the stability of the detection path. Next, the entire bottom surface of the beam is scanned. That is, the device moves at a constant speed with the assistance of the slide rail mechanism, while electrolyte is evenly sprayed on the bottom surface of the beam to improve the electrical contact conditions. During this process, the permanent magnet probes 1 of multiple sub-detection mechanisms start working synchronously. The collected voltage signals are amplified by the amplifier 202 of the electrical control box 2, filtered by the filter 203, and processed by the analog wireless acquisition module 204 before being transmitted to the computer for storage.

[0038] Furthermore, the computer performs time-domain alignment and superposition on the voltage signals collected by the permanent magnet probes 1 of the multiple sub-detection mechanisms arranged in a linear array to eliminate noise introduced by the vibration of the device, and amplifies the signals. Subsequently, the location of the rust cross-section is determined, and the amount of rust (the spatial distribution of the depth and width of the rust degree) is jointly judged by combining the "voltage amplitude-corrosion depth" comparison table and the identification of the width of missing voltage signals.

[0039] Then, the device is controlled by a sliding rail mechanism to stop at the defect starting position determined by the permanent magnet perturbation method, and AC polarization impedance measurement is initiated at that position. Under the control of computer instructions, the AC impedance analyzer 206 in the electrical control box 2, the electrode control valve 207, the transmitting electrode 307 and the receiving electrode 308 of the wheel electrode 3 are driven to generate a high-frequency and low-frequency composite current signal. At the same time, the voltage signal of the receiving electrode 308 is acquired by the wireless acquisition module and transmitted to the computer for storage, ensuring that the current and voltage signals are completely synchronized in time. Next, the time-domain signals of the current and voltage are converted into frequency-domain signals using Fourier transform, a Nyquist plot is plotted, and the polarization resistance R is extracted. p The Srern-Geary constant B is determined by combining the corrosion stage obtained from the permanent magnet perturbation method. Then, the corrosion current is calculated by the Stern-Geary equation, and the steel corrosion rate v is calculated by formula (5). loss .

[0040] Finally, the amount and rate of corrosion at different cross-sections of the bridge are input into a classifier that has been trained in advance based on electrochemical and magnetic measurement methods under different corrosion levels, thereby achieving a joint determination of the overall corrosion status.

[0041] Therefore, the array permanent magnet and electrochemical impedance synchronous detection device and method for detecting steel corrosion in concrete captures the magnetic reluctance changes of each magnetic field line path, converging them inside the permanent magnet and generating an induced voltage in the external coil to detect corrosion in concrete. Compared to capturing the presence of leakage magnetic fields, this permanent magnet perturbation method does not need to consider the small-range limitations of leakage magnetic fields, thus greatly improving the detection distance.

[0042] This array permanent magnet and electrochemical impedance synchronous detection device for steel reinforcement corrosion in concrete combines the mechanism of beam corrosion and the location distribution characteristics of the main reinforcement in the beam. By arranging permanent magnet probes in an array and detecting the corrosion status of concrete across the entire cross section, the noise of the aggregated signal can be reduced and the defect signal amplified by leveraging the noise independence of each permanent magnet probe.

[0043] This array-based permanent magnet and electrochemical impedance spectroscopy (EIS) synchronous detection device for steel reinforcement corrosion in concrete can not only obtain the total corrosion amount using the permanent magnet perturbation method, but also simultaneously obtain the corrosion rate near the corrosion location using the AC polarization resistance method. When both corrosion depth (h), reflecting the total corrosion amount, and steel reinforcement impedance, reflecting the corrosion rate, are simultaneously collected... Then, the results are input into a pre-trained classifier (such as a Support Vector Machine, SVM) to obtain a more accurate rust stage. The performance of each classifier can be evaluated using metrics such as accuracy (Ac), precision (Pr), recall (Re), and F1 score, based on the confusion matrix. Table 1 compares the performance of each classifier using only h... And simultaneously considering h, The prediction results of the classifier are shown. It can be clearly seen that the support vector machine classifier with joint data outperforms the classifier with individual data in all performance metrics.

[0044] Table 1 Evaluation index results of classification results under different data types / % Using a trained support vector machine model, the probabilistic characteristics of steel reinforcement corrosion state as a function of h can be intuitively understood. Specifically, based on SVM, by iterating through the complete value range of each data point using the input attributes, the probability of the steel reinforcement being in each corrosion stage when the data changes can be obtained. The specific results are as follows: Figure 7-10 As shown, it is evident that the distribution of each corrosion state is more robust when using joint data for evaluation, demonstrating the advantages of the joint evaluation method.

[0045] The main technical points of this application are summarized as follows: 1. Simultaneous "Magnetic-Electro" Dual-Mode Detection: This method integrates permanent magnet perturbation (magnetism) and alternating current impedance (AC) methods (electrochemistry) into a single detection unit, enabling the simultaneous acquisition of both "state" and "velocity" quantities of corrosion. The two physical quantities are measured in a single scan using the same device, improving detection efficiency and data fusion.

[0046] 2. Arrayed and modular structural design: Multiple sub-detection mechanisms are arranged in a linear array to cover the entire cross-section, improving detection coverage and signal stability. Modular assembly is achieved through connecting lugs, bolted joints, and bridging rods to adapt to the detection needs of beams of different widths.

[0047] 3. Application of the permanent magnet perturbation method: This method uses "magnetic circuit reluctance change" instead of the traditional "leakage magnetic field" detection, breaking through the limitations of lift height and making it suitable for thick protective concrete layers. Furthermore, a magnetizer and shielding cover are added to improve signal stability and anti-interference capabilities.

[0048] 4. Wheeled Electrode and Vibration Damping Design: The wheeled electrodes are attached to the concrete surface and maintain stable contact through vibration dampers, ensuring the reliability of electrochemical measurements. Simultaneously, the electrodes are individually controlled in groups to avoid signal crosstalk and adapt to situations with multiple reinforcing bars.

[0049] 5. Data fusion and intelligent assessment: Input magnetic and electrochemical data into a trained classifier (such as SVM) to achieve joint intelligent determination of corrosion status, thereby improving the accuracy and robustness of assessment.

[0050] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A synchronous detection device for arrayed permanent magnet and electrochemical impedance spectroscopy for detecting steel corrosion in concrete, characterized in that, It includes at least one sub-detection mechanism. Each sub-detection mechanism includes a unit frame (7) and a permanent magnet probe (1), a main wheel (6), an electrical control box (2) and a wheel electrode (3) arranged sequentially from front to back on the unit frame (7). The permanent magnet probe (1) identifies the depth and width of steel reinforcement corrosion in concrete based on voltage signals. It is composed of a permanent magnet (102) and a magnetic coil (103) wound on the permanent magnet (102). The wheel electrode (3) is used to adhere to the concrete surface and conduct the current path formed between the concrete surface and the steel reinforcement in the concrete. It consists of several sets of transmitting electrodes (307) and receiving electrodes (308) arranged side by side, with each set having a front-to-back spacing. The electrical control box (2) is used to communicate with the permanent magnet probe (1) and the wheel electrode (3) respectively. It consists of an analog wireless acquisition module (204), an AC impedance analyzer (206), and an electrode control valve (207). The analog wireless acquisition module (204) is used to acquire and transmit the voltage signal of the permanent magnet probe (1). The electrode control valve (207) is used to switch on and off any single group of transmitting electrodes (307) and receiving electrodes (308) in the wheel electrode (3). The AC impedance analyzer (206) is used to transmit high-frequency and low-frequency composite current signals and measure the voltage signal between the two electrodes after passing through the transmitting electrode (307), the reinforcing bar, and the receiving electrode (308) in sequence. The main wheel (6) is supplemented by a unit frame (7) and moves longitudinally on the concrete surface and along the steel reinforcement inside the concrete.

2. The array permanent magnet and electrochemical impedance synchronous detection device for steel reinforcement corrosion in concrete according to claim 1, characterized in that, The permanent magnet probe (1) also includes a first shield (101); the electrical control box (2) also includes a second shield (201).

3. The array permanent magnet and electrochemical impedance synchronous detection device for steel reinforcement corrosion in concrete according to claim 1, characterized in that, The permanent magnet probe (1) also includes a magnetizer (104) disposed on top of the permanent magnet (102) and used to stabilize the voltage signal of the magnetic coil (103).

4. The array permanent magnet and electrochemical impedance synchronous detection device for steel reinforcement corrosion in concrete according to claim 1, characterized in that, The wheel electrode (3) also includes a wheel frame (304), a wheel frame connecting rod (305), and a shock absorber (306). Two wheel frames (304) are arranged in parallel and spaced apart on the unit frame (7) through the shock absorber (306), and the two wheel frames (304) are connected to each other through multiple wheel frame connecting rods (305). One wheel frame (304) is provided with multiple transmitting electrodes (307) arranged in a linear interval, and the other wheel frame (304) is provided with multiple receiving electrodes (308) arranged in a linear interval and corresponding one-to-one with the multiple transmitting electrodes (307). Each transmitting electrode (307) and each receiving electrode (308) has its hub (302) set on the corresponding wheel frame (304) through its own independent wheel axle (301), and a tire (303) is fitted on the hub (302).

5. The array permanent magnet and electrochemical impedance synchronous detection device for steel reinforcement corrosion in concrete according to claim 1, characterized in that, The electrical control box (2) also includes an amplifier (202) and a filter (203). The amplifier (202) is used to amplify the voltage signal of the magnetic coil (103), and the filter (203) is used to filter the voltage signal of the magnetic coil (103).

6. The array permanent magnet and electrochemical impedance synchronous detection device for steel reinforcement corrosion in concrete according to claim 1, characterized in that, The unit frame (7) is also provided with a nozzle (4) and a water tank (5). The electrical control box (2) also includes an electrolyte controller (205). The nozzle (4) is connected to the water tank (5) through the electrolyte controller (205). The water tank (5) is used to store water or electrolyte medium.

7. The array permanent magnet and electrochemical impedance synchronous detection device for steel reinforcement corrosion in concrete according to any one of claims 1-6, characterized in that, A connecting ear (701) is provided at each of the four top corners of the unit frame (7); multiple bolting parts (702) are provided on both sides of the unit frame (7); multiple sub-detection mechanisms are arranged in a straight line array and connected in series with multiple connecting ears (701) on the same axis through a crossbeam, and adjacent two sub-detection mechanisms are connected to each other at the bolting parts (702) on the corresponding sides facing each other through a bridging rod (8).

8. A method for simultaneous detection of steel reinforcement corrosion in concrete using arrayed permanent magnets and electrochemical impedance spectroscopy, characterized in that, The method using the array permanent magnet and electrochemical impedance synchronous detection device for steel corrosion in concrete as described in claim 7 includes the following steps: S1) Defect calibration of the detection device; a series of reinforced concrete specimens with equidistant step lengths and different corrosion depths are made, and a single sub-detection mechanism is used to scan along the longitudinal direction of the steel bars in each reinforced concrete specimen one by one at the same scanning speed to record the voltage signal amplitude output by the magnetic coil of the permanent magnet probe under different corrosion depth conditions, so as to establish the calibration relationship of "voltage amplitude-corrosion depth"; while the corrosion width is confirmed by the width of the defect voltage signal in the magnetic coil. S2) According to the detection requirements, multiple sub-detection mechanisms are assembled into a linear array arrangement structure, and with the assistance of a sliding rail mechanism set on the concrete surface to be tested, they move at a constant speed to carry out permanent magnet disturbance scanning, and electrolyte is sprayed evenly on the concrete surface. During this process, the permanent magnet probes of multiple sub-detection mechanisms work synchronously, and the collected voltage signals are successively amplified, filtered, and processed by wireless analog signal acquisition before being transmitted to the computer for storage. S3) The voltage signals collected by the permanent magnet probes of multiple sub-detection mechanisms arranged in a line are time-domain aligned and superimposed by the computer to determine the location of the rust cross section, and the amount of rust is jointly judged by combining the "voltage amplitude-corrosion depth" calibration relationship and the identification of the width of missing voltage signals. S4) Then, the wheel electrodes of multiple sub-detection mechanisms are controlled by the sliding rail mechanism to stop at the defect starting position of the permanent magnet disturbance judgment, and AC polarization impedance measurement is performed at that position; under the control of computer instructions, the AC impedance analyzer is started to emit high-frequency and low-frequency composite current signals in sequence, and the voltage signal fed back by the wheel electrodes is collected simultaneously and transmitted to the computer for storage. S5) When the transmitting electrode outputs a signal v ( n If the receiving electrode receives the signal synchronously, then the receiving electrode will receive the signal. i ( n Then, Fourier transform is used to convert the time-domain signals of current and voltage into frequency-domain signals in order to plot the Nyquist plot; (1) (2) By comparing the values ​​of two sets of signals recorded at the same time at different frequencies, the complex impedance is: (3) Where, φ V For the voltage signal phase, φ I The phase of the current signal; The Nyquist plot coordinates (Z', -Z'') represent the real and imaginary parts of Z, respectively; the polarization resistance is then extracted from the Nyquist plot. R p The Srern-Geary constant was determined by combining the corrosion stages obtained from permanent magnet perturbation. B The corrosion current density was then calculated using the Stern-Geary equation. i corr ; (4) in, B These are empirical constants; According to Faraday's law, the mass of dissolved Fe per unit area per unit time is converted into the rate of steel bar section reduction, i.e., the corrosion rate, and then calculated using the following formula: (5) in, v loss Corrosion rate (mm / year); M The molar mass of the reinforcing steel; n The number of electrons in the reaction; F ≈96485C / mol; ρ Reinforcing steel density; S6) Input the amount and rate of corrosion at different cross-sectional locations into a classifier that has been trained in advance based on electrochemical and magnetic measurement methods under different corrosion levels, so as to achieve a joint determination of the overall corrosion state.

9. The method for simultaneous detection of array permanent magnet and electrochemical impedance spectroscopy for steel reinforcement corrosion in concrete according to claim 8, characterized in that, In step S1), for the unprepared intermediate corrosion depth values, the corresponding calibration results are obtained by linear interpolation.

10. The method for simultaneous detection of array permanent magnet and electrochemical impedance spectroscopy for steel reinforcement corrosion in concrete according to claim 8, characterized in that, In step S6), the classifier is a support vector machine (SVM).

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