Mini-arrayed concrete chloride ion sensor and measurement data correction method

Abstract

The application discloses a micro-array type concrete chloride ion sensor and a measurement data correction method. The micro-array type chloride ion sensing sensor is composed of Ag / AgCl selective electrodes, a micro-MnO2 reference electrode array, a shell, connecting wires and a packaging material. The Ag / AgCl selective electrode array and the long-acting micro-MnO2 reference electrode array are nested with each other, so that the same number of Ag / AgCl selective electrodes are distributed at equal intervals around each micro-MnO2 reference electrode. The measurement data correction method is that the array type chloride ion sensing sensor collects concrete chloride ion concentration data through the electrode pair composed of the Ag / AgCl selective electrode and the adjacent micro-MnO2 reference electrode, and calibrates the data by using the difference between the micro-MnO2 reference electrode and the rest of the micro-MnO2 reference electrode groups in the array. The micro-array type chloride ion sensing sensor can improve the repeatability and reliability of the monitoring results of the chloride ion concentration in the concrete and inverses the concentration gradient of the chloride ion in the concrete.

Description

Technical Field

[0001] This invention relates to corrosion and protection technology for reinforced concrete structures, and more particularly to a miniature array-type concrete chloride ion sensor and a method for correcting measurement data. Background Technology

[0002] Concrete durability refers to the ability of concrete to resist various destructive factors and maintain its strength and appearance integrity over a long period under working conditions. In marine concrete, chloride ions can adversely affect the concrete and reinforcing steel, reducing the durability of the concrete structure. Therefore, real-time monitoring of the chloride ion concentration distribution within the concrete cover provides data support for concrete structure durability assessment and remaining service life prediction, thereby enabling the development of scientific management and maintenance systems to ensure the durability and service safety of concrete structures. This is of great practical significance.

[0003] Currently, methods for determining chloride ion content are mainly divided into two categories: destructive testing and non-destructive monitoring. Destructive testing requires damaging the concrete structure, collecting samples, grinding them, and then measuring the chloride ion content using silver nitrate titration. This method has the disadvantage of damaging the original structure, and the measured results are generally higher or lower than the sample's chloride ion content, leading to inefficiency and inaccuracy. Non-destructive monitoring mainly involves embedding sensors in the concrete to directly monitor chloride ion content, offering advantages such as non-destructiveness and high accuracy. Non-destructive monitoring primarily utilizes electrochemical techniques, such as embedded electrode potential measurement, embedded electrode chronopotentiometry, and resistance and impedance measurement. This method is characterized by in-situ, non-destructive, and rapid operation. Therefore, developing electrochemical sensors for real-time detection of the depth distribution of chloride ion concentration in concrete, thereby comprehensively understanding the durability of concrete structures, is an inevitable trend in the development of durability monitoring technology.

[0004] However, most embedded durability monitoring sensors currently available cannot monitor the depth distribution of chloride ion concentration in concrete, thus failing to provide effective data support for durability assessment and concrete life prediction. Tang Yanbing et al. from CCCC Fourth Harbor Engineering Research Institute Co., Ltd. invented a sensor capable of monitoring the depth distribution of chloride ion concentration in the concrete cover. However, the measurement data from a chloride ion sensor composed of a single chloride ion probe and a single reference electrode at the same depth are scattered, resulting in low reliability. Furthermore, multi-probe composite sensors on the market are relatively bulky. Summary of the Invention

[0005] Purpose of the invention: In view of the problems existing in the prior art, the purpose of this invention is to provide a miniature array chloride ion sensor that can be embedded in concrete to monitor the distribution of chloride ions in the depth direction of concrete in real time; another purpose of this invention is to provide a method for calibrating the measurement data of the miniature array chloride ion sensor.

[0006] Technical solution: The micro array type concrete chloride ion sensor of the present invention includes a shell, an Ag / AgCl selective electrode and a micro MnO2 reference electrode. The shell is a right-angled trapezoidal three-dimensional structure. The array of Ag / AgCl selective electrodes and the array of micro MnO2 reference electrodes are nested together. The same number of Ag / AgCl selective electrodes (3) are distributed at equal intervals around each micro MnO2 reference electrode. The chloride ion probe part of each Ag / AgCl selective electrode extends out of the inclined surface of the shell, and the exposed probe tip serves as the detection end. The electrode wire of each micro MnO2 reference electrode extends out of the inclined surface of the shell as the detection end. The ends of the Ag / AgCl selective electrode and the micro MnO2 reference electrode are connected by wires, and the wires are combined and extend out of the shell. The part of the shell containing the Ag / AgCl selective electrode and the micro MnO2 reference electrode is encapsulated by a colloidal encapsulation material, and the part containing the wires is encapsulated by a polymer encapsulation material.

[0007] Preferably, the number of Ag / AgCl selective electrodes is 9, and the number of micro MnO2 reference electrodes is 4, forming a 3×3 Ag / AgCl selective electrode array with an embedded 2×2 micro MnO2 reference electrode array.

[0008] The method for correcting the measurement data of the micro-array concrete chloride ion sensor includes the following steps:

[0009] (1) Each Ag / AgCl selective electrode is paired with an adjacent MnO2 reference electrode to collect and measure the potential difference V. SnRm The potential difference data matrix V0 is obtained as follows:

[0010]

[0011] Among them, V SnRm The matrix order is represented by S. n The order of the Ag / AgCl selective electrode and matrix is ​​R m The potential difference of the micro MnO2 reference electrode, n = 1, 2, ..., 9; m = 1, 2, 3, 4;

[0012] (2) Correcting data errors caused by potential differences between different reference electrodes: Collect multiple sets of data for Ag / AgCl selective electrodes in matrix order S2, S4, S5, S6, and S8, and correct them based on the data of the same micro MnO2 reference electrode for two different Ag / AgCl selective electrodes. The correction weight of Ag / AgCl selective electrode S5 is 1 / 4 of that of the other Ag / AgCl electrode involved in the correction.

[0013] (3) Adjust the data matrix; adjust the data matrix V0 according to the correction value of the micro MnO2 reference electrode. Next, take the average of each data point with the four data points above, below, to the left, and to the right. If there is a gap, replace it with the current center data. The resulting average value replaces the original center data, thus obtaining the transition data matrix V. * ;

[0014] (4) Transition data matrix V * The data are averaged and updated into a 3×3 data matrix V, resulting in 9 new potential differences as test data for each selective electrode. These data are then used for subsequent processing to reflect the chloride ion diffusion and concentration curve within the control area of ​​the array-type chloride ion sensor.

[0015] Furthermore, the formula in step (2) is modified as follows:

[0016] Correction value between R1 and R2 for:

[0017]

[0018] Correction value between R1 and R3 for:

[0019]

[0020] Correction value between R2 and R4 for:

[0021]

[0022] Correction value between R3 and R4 for:

[0023]

[0024] Therefore, the correction value for each reference electrode can be obtained:

[0025] R1 correction value

[0026] R2 correction value

[0027] R3 correction value

[0028] R4 correction value

[0029] This correction method considers the overall operational correlation among the four reference electrodes. When the center selection electrode S5 malfunctions, it has little impact on the entire system. However, when one of the edge selection electrodes malfunctions, it significantly affects the correction of the two adjacent reference electrodes, but does not affect the correction of the remaining reference electrodes.

[0030] Furthermore, step (2) also includes checking the correction value by fixing a reference electrode at the end.

[0031] Furthermore, in step (3), the matrix for:

[0032]

[0033] Furthermore, in step (3), the transition data matrix V * for:

[0034]

[0035] in,

[0036]

[0037]

[0038] Furthermore, in step (4), the data matrix V is:

[0039]

[0040] in,

[0041] V1 = V 1-1 ;

[0042]

[0043]

[0044] Beneficial effects: Compared with the prior art, the present invention has the following significant advancements: 1. The present invention solves the problem of unreliable results in measuring chloride ion concentration in concrete using traditional single-electrode pairs. Based on the miniaturization of chloride ion probes and reference electrodes, a self-correcting chloride ion sensor for concrete is constructed by using multiple electrode pairs arranged in a gradient array. This calibrates the sensor's detection data, improves the repeatability and reliability of chloride ion concentration monitoring results in concrete, and inversely retrieves the chloride ion concentration gradient in concrete, achieving high-precision measurement of chloride ions in concrete at different depths; 2. The present invention can realize real-time monitoring of chloride ion distribution in the depth direction of concrete, providing data support for the durability assessment of concrete structures and the prediction of the remaining service life of concrete. Attached Figure Description

[0045] Figure 1 Front view of a miniature array-type concrete chloride ion sensor;

[0046] Figure 2 Right view of a miniature array-type concrete chloride ion sensor. Detailed Implementation

[0047] The technical solution of the present invention will be explained and described in detail below with reference to the accompanying drawings and specific embodiments.

[0048] The miniature array-type concrete chloride ion sensor of the present invention includes a stainless steel housing 1, nine Ag / AgCl selective electrodes 3 and four long-lasting miniature MnO2 reference electrodes 4. The housing 1 has a right-angled trapezoidal three-dimensional structure. The array of Ag / AgCl selective electrodes 3 and the array of miniature MnO2 reference electrodes 4 are nested together, and the same number of Ag / AgCl selective electrodes 3 are evenly distributed around each miniature MnO2 reference electrode 4. The chloride ion probe portion of each Ag / AgCl selective electrode 3 extends out of the inclined surface of the housing 1, and the exposed probe tip serves as the detection end. The electrode wire of each miniature MnO2 reference electrode 4 extends out of the inclined surface of the housing 1 as the detection end. The ends of the Ag / AgCl selective electrodes 3 and the miniature MnO2 reference electrodes 4 are connected by wires 6, and the wires 6 are combined and extend out of the housing 1. The portion of the housing 1 containing the Ag / AgCl selective electrodes 3 and the miniature MnO2 reference electrodes 4 is encapsulated by a colloidal encapsulation material 2, and the portion containing the wires 6 is encapsulated by a polymer encapsulation material 5.

[0049] The housing measures 15mm × 15mm, with the bottom of the trapezoidal base not exceeding 40mm. The Ag / AgCl selective electrodes at the edge are 2mm from the frame of the housing, adjacent Ag / AgCl selective electrodes are 3.8mm apart, and adjacent diagonally opposite Ag / AgCl selective electrodes are approximately 5.4mm apart. Four miniature MnO2 reference electrodes are placed at the center of each of the four small square spaces formed by the nine Ag / AgCl selective electrodes, forming a 3×3 Ag / AgCl selective electrode array with an embedded 2×2 miniature MnO2 reference electrode array. The Ag / AgCl selective electrode tubes have a diameter of approximately 1mm, and the miniature MnO2 reference electrodes have a diameter of approximately 3-4mm. A chloride ion probe is fixed to the front of the chloride ion sensor and partially exposed on the front end face as the detection end. The other end extends inward to connect to a copper cable, which extends beyond the cylindrical package and the housing. The solid reference electrode shell is a transparent plastic tube, partially exposed on the front end face for easy fixation. A solid reference electrode is fixed at the center of the chloride ion electrode pair, forming an array of chloride ion probes and solid reference electrodes. The cylindrical encapsulation shell is a prism with a trapezoidal bottom, and its inner front surface has grooves for fixing the chloride ion probes and solid reference electrodes. This miniature array-type concrete chloride ion sensor is arranged in the concrete with the reinforcing steel bars at the bottom and the concrete surface at the top, thus enabling the measurement of chloride ion concentrations at different depths of concrete.

[0050] The method for correcting the measurement data of the micro-array concrete chloride ion sensor includes the following steps:

[0051] (1) Each Ag / AgCl selective electrode was paired with an adjacent MnO2 reference electrode, and the measured potential difference was recorded. S2, S4, S6, and S8 had two sets of data due to their two adjacent reference electrodes (matrix edge), while S5 had four sets of data due to its four adjacent reference electrodes (matrix center). The data were expressed in terms of V. S(n)R(n) The original data is recorded in the following format and obtained as a 4×4 matrix:

[0052]

[0053] (2) Correcting data errors caused by potential differences between different reference electrodes. Ideally, the voltage difference measured by the selective electrode and the two adjacent reference electrodes is stable and the same. However, in actual measurements, there will be some deviation. This is due to the potential difference between the reference electrodes themselves. In order to make the data true, reliable and valuable for analysis, the error between different reference electrodes should be determined first and the data should be corrected.

[0054] Multiple sets of data measured using electrodes S2, S4, S5, S6, and S8 were used for correction. Data from the same reference electrode of the two selective electrodes were also used in the correction. The correction value is expressed as V. * ;

[0055] Since electrode S5 participates in the correction of the four reference electrodes, if the potential difference measured by it and the four reference electrodes is too large, it is determined that the sensor is malfunctioning; if the difference is not large, the correction continues to avoid the impact of poor data caused by its abnormality on the entire system. Its correction weight should be 1 / 4 of that of the other selective electrode participating in the correction. The specific correction formula is as follows:

[0056] Correction value between R1 and R2

[0057] Correction value between R1 and R3

[0058] Correction value between R2 and R4

[0059] Correction value between R3 and R4

[0060] From these four equations, the correction value for each reference electrode can be obtained:

[0061] R1 correction value

[0062] R2 correction value

[0063] R3 correction value

[0064] R4 correction value

[0065] This correction method considers the overall operational correlation among the four reference electrodes. When the center selection electrode S5 malfunctions, it has little impact on the entire system. However, when one of the edge selection electrodes malfunctions, it significantly affects the correction of the two adjacent reference electrodes without affecting the correction of the other reference electrodes. Alternatively, the correction value can be rechecked by fixing one of the reference electrodes.

[0066] (3) Adjust the data matrix. Based on the potential differences measured by each selective electrode, a new 4×4 data matrix is ​​obtained, as shown below:

[0067]

[0068] The data was transformed into a smoothed 3×3 matrix. First, the average value of each data point and the four data points above, below, left, and right was taken. If there was a gap, the current center data was used to replace it. The average value of the result replaced the original center data, resulting in a new transitional data matrix. This matrix better reflects the diffusion trend of chloride ions in the entire sensor system.

[0069]

[0070]

[0071]

[0072] (4) Take the average value of the data measured and corrected by the nine selective electrodes to obtain nine new potential differences, i.e., the corrected 3×3 data matrix, as the test data of each selective electrode, and use it for subsequent processing to reflect the chloride ion diffusion and concentration curve in the control area of ​​the array-type chloride ion sensor.

[0073] For example: V1 = V 1-1

[0074]

[0075]

[0076] Corrected Ag / AgCl selective electrode 3×3 data matrix:

[0077]

[0078] Furthermore, based on specific needs and further methods, a curve showing the change of chloride ion concentration in concrete with depth can be fitted, thereby allowing the concentration of chloride ions in concrete at different depths to be observed, providing data support for durability assessment and prediction of the remaining service life of concrete.

Claims

1. A method for correcting measurement data of a microarray-type concrete chloride ion sensor, characterized by, The micro-array concrete chloride ion sensor is realized, and the micro-array concrete chloride ion sensor comprises a shell (1), Ag / AgCl selective electrodes (3) and micro-MnO2 reference electrodes (4), the shell (1) is a right trapezoidal solid structure, the array of the Ag / AgCl selective electrodes (3) and the array of the micro-MnO2 reference electrodes (4) are nested with each other, and the same number of Ag / AgCl selective electrodes (3) are distributed at equal intervals around each micro-MnO2 reference electrode (4); the chloride ion probe part of each Ag / AgCl selective electrode (3) extends out of the slope of the shell (1), and the exposed probe front end serves as a detection end; the electrode lead of each micro-MnO2 reference electrode (4) extends out of the slope of the shell (1) as a detection end; the ends of the Ag / AgCl selective electrodes (3) and the micro-MnO2 reference electrodes (4) are connected through wires (6), the wires (6) are gathered and then extend out of the shell (1); the Ag / AgCl selective electrodes (3) and the micro-MnO2 reference electrodes (4) in the shell (1) are packaged by a colloidal packaging material (2), and the wire (6) is packaged by a high polymer packaging material (5); The measurement data correction method comprises the following steps: (1) Each Ag / AgCl selective electrode is paired with an adjacent Mn02 reference electrode to collect the measured potential difference V SnRm The data matrix V0 of the potential difference is obtained as follows: ； where V SnRm represents the potential difference between the Ag / AgCl selective electrode with matrix order S n and the micro-MnO2 reference electrode with matrix order R m , n = 1, 2, …, 9; m = 1, 2, 3, 4. (2) Correct the data error caused by the potential difference of different reference electrodes. Collect multiple sets of data of Ag / AgCl selective electrodes with the sequence of S2, S4, S5, S6, and S8, and correct the data according to the same micro-MnO2 reference electrode data of two different Ag / AgCl selective electrodes. The correction weight of the S5 Ag / AgCl selective electrode is ​ (3) Adjust the data matrix; according to the correction value of micro-MnO2 reference electrode, the data matrix V0 is corrected to matrix V1 , and the average value of each data and its upper, lower, left and right four data is obtained, if there is a vacancy, the current center data is replaced, and the average value is used instead of the original center data, and the transition data matrix is obtained ; (4) The data of transition data matrix are averaged respectively, and updated to a 3x3 data matrix V, to obtain 9 new potential differences as the test data of each selective electrode, for subsequent processing to reflect the diffusion and concentration curve of chloride ions in the control area of the arrayed chloride ion sensor.

2. The method of claim 1, wherein the measurement data of the microarray-type concrete chloride sensor is corrected. The correction formula in step (2) is as follows: between the values of the first and second signals correction value is: ； between the values of the first and second signals correction value between the values of the first and second signals is: ； between the values of the parameters of the first and second sets of parameters correction value between the values of the parameters of the first and second sets of parameters is: ； between the values of the first and second signals correction value is: ； Thus, the correction value of each reference electrode can be obtained: correction value ; correction value ; correction value ; correction value .

3. The method of claim 1, wherein the measurement data of the microarray-type concrete chloride sensor is corrected. In step (2), the way of finally fixing a reference electrode is further included to verify the correction value.

4. The method of claim 1, wherein the measurement data of the microarray-type concrete chloride sensor is corrected. In step (3), the matrix is: 。 5. The method of claim 1, wherein the measurement data of the microarray-type concrete chloride sensor is corrected. In step (3), the transition data matrix is: ； Wherein, ； 。 6. The method of claim 1, wherein the measurement data of the microarray-type concrete chloride sensor is corrected. In step (4), the data matrix V is: ； wherein ; ； 。 7. The method of claim 1, wherein the measurement data of the microarray-type concrete chloride sensor is corrected. The number of the Ag / AgCl selective electrodes (3) is 9, the number of the micro-MnO2 reference electrodes (4) is 4, and a 3*3 Ag / AgCl selective electrode array is inlaid in a 2*2 micro-MnO2 reference electrode array.

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