WO2021098197A1

WO2021098197A1 - Apparatus for testing rebar in concrete, and method therefor

Info

Publication number: WO2021098197A1
Application number: PCT/CN2020/095587
Authority: WO
Inventors: 王鹏刚; 金祖权; 赵铁军; 侯东帅; 田砾; 范宏; 牟犇; 熊传胜; 张小影
Original assignee: 青岛理工大学
Priority date: 2019-11-22
Filing date: 2020-06-11
Publication date: 2021-05-27
Also published as: CN110836631A; CN110836631B

Abstract

Provided are an apparatus for testing a rebar in concrete, and a method therefor. The testing apparatus comprises an electrode plate (11), a direct-current power source, and a data acquisition processing apparatus (13), the data acquisition processing apparatus (13) comprising: a capacitance meter, wherein an angular frequency thereof is set as 10 KHz; a display module (1) for displaying a numerical value obtained after testing by a capacitance sensor; an operation module (4) for performing a manual actual operation and inputting special engineering information to set a parameter; a processing module for compiling data analysis statistics on the numerical value measured by the capacitance meter and other relevant numerical values; and a data connection line socket (2) for connecting to the electrode plate (11). A low-cost and high-precision lossless testing apparatus and method based on the principle of electrostatic field capacitance are provided. Various types of targeted testing are implemented on a rebar in concrete, so as to acquire an accurate and convenient testing result comprising rebar position, size and corrosion amount, and the working efficiency of construction engineering acceptance, and testing, reinforcement and identification of an existing reinforced concrete structure are improved.

Description

Device and method for detecting steel bars in concrete

Technical field

The invention relates to a device and a method for nondestructive detection of steel bars applied to concrete structures, and belongs to the field of building construction.

Background technique

At present, in the construction of commercial and civil buildings, railways and highways and other rail transit projects, reinforced concrete structures are used in concrete construction. In order to ensure the quality of construction and the safety of subsequent long-term use, it is necessary to carry out a number of special inspections of steel bars in concrete, which is the primary prerequisite for ensuring the safety of reinforced concrete structures.

According to the latest edition of my country's "Construction Quality Acceptance Standards for Construction Engineering", the inspection items of steel bars in concrete structures include whether the position, size and other parameters are consistent with the design drawings, and whether the corrosion degree and state are within the standard value range. In particular, the corrosion of steel bars usually occurs inside the concrete structure, and it is difficult to evaluate the service life and load-bearing capacity of the building. Moreover, the corrosion of steel bars will directly lead to the collapse of the building, which is extremely harmful. When repairing damaged buildings, it is also necessary to obtain corresponding accurate steel corrosion data. If the corrosion of steel bars can be found in time and early repair measures can be taken, it will greatly reduce costs and reduce economic losses.

The prior art mainly adopts technologies such as ultrasonic method, electromagnetic induction method, geological radar, and tomographic imaging for the detection of steel bars in concrete during the safety of infrastructure construction and the construction acceptance stage. The electromagnetic induction method is a relatively common detection method, which can measure the position and depth of the steel bar relatively accurately. However, due to the high environmental requirements and the susceptibility to the influence of the material composition, it is prone to errors. The geological radar method is mainly used for the layered detection of concrete, and can also detect the position of the steel bars in the concrete, but the geological radar is relatively complicated to operate and the equipment is more expensive. Tomography technology is also often used to evaluate concrete, but its application in practical engineering is limited due to expensive equipment, troublesome operation and data processing.

In view of this, this patent application is hereby filed.

Summary of the invention

The device and method for detecting steel bars in concrete of the present invention solve the above-mentioned problems in the prior art and provide a low-cost, high-precision non-destructive detection device and method based on the principle of electrostatic field capacitance. Targeted multiple inspections, in order to obtain accurate and convenient inspection results including the position, size and corrosion amount of steel bars, so as to improve the work efficiency of construction project acceptance and inspection, reinforcement and appraisal of existing reinforced concrete structures.

In order to achieve the above design objectives, the said device for detecting steel bars in concrete mainly includes an electrode plate, a DC power supply and a data acquisition and processing device. among them,

The electrode plate includes a copper electrode, polymethyl methacrylate and a moisture content test device, and the two copper electrodes are placed on the same level and on the same level;

The data acquisition and processing device includes a capacitance meter, the angular frequency of which is set to 10KHz; a display module to display the value obtained after detection by the capacitance sensor; an operation module to manually input specific project information to set parameters; The processing module is used to perform data analysis and statistics on the measured values of the capacitance meter and other related values; the data connection line socket is used to connect the electrode plate.

Based on the application of the above detection device, this application also realizes a new detection method. That is, the state of the steel bar is determined according to the fluctuation of the capacitance value and the capacitance value data, and the calculation formula is as follows:

Among them, C is the capacitance between the two plates of the capacitive sensor, in farads (F) as the unit; A is the (effective) area between the two plates, in square meters; ε _r is the relative medium between the plates. Permittivity; ε is the absolute permittivity in vacuum (8.854×10 ^-12 Fm ^-1 ); d is the separation distance between the electrode plates, in meters; the change trend of the capacitance between the electrode plates indicates The difference in the location, size and amount of corrosion of the steel bars in the concrete.

The method for detecting steel bars in concrete includes the following implementation steps:

1) Calibration

Calibration refers to the establishment of a characterization mapping with the state of the steel bar based on the capacitance value data. The calibration process includes the calibration of the capacitance value and the diameter of the steel bar, the calibration of the capacitance value and the thickness of the protection layer of the steel bar, and the calibration of the capacitance value and the corrosion state of the steel bar;

2) Obtain data from actual measurement

2.1 Connect the electrode plate to the data acquisition and processing device and turn it on;

2.2 Perform actual inspections on reinforced concrete structures;

Place the electrode plate on one side of the concrete, operate the operation module in the data acquisition and processing device, input necessary engineering information, and scan the electrode plate along the concrete side to the other side at a constant speed to obtain the capacitance values of different positions;

3) Data processing and analysis

3.1 Scale the test target along the moving direction of the electrode plate;

3.2 Establish a two-dimensional coordinate system, the X axis is the scale of the moving direction of the electrode plate, and the Y axis is the capacitance value measured by the capacitance meter;

To detect the position of the steel bar, the relationship between the capacitance value and the diameter of the steel bar is expressed as C=aB ² +bB+c (1);

The expression of the thickness relation of the protective layer of the steel bar is: C=eD ² +fD+g (2);

The relationship between the diameter of the steel bar and the capacitance value is: C=aB ² +bB+c;

The relationship between the amount of corrosion of steel bars and the capacitance value is C=K ₀ *△M (3).

Further, the calibration process includes the following steps:

1.1 Calibration of capacitance value and steel bar diameter

1.1.1 Put steel bars of different diameters into the same batch of concrete with the same protective layer thickness, and cure the concrete for 28 days;

1.1.2 After the concrete curing is completed, put the reinforced concrete to be tested into the oven to keep the reinforced concrete with a moisture content of 0;

1.1.3 Take out the reinforced concrete to be tested with a moisture content of 0, use the detection device to scan the electrode plate 11 along the concrete side to the other at a uniform speed, measure the capacitance value corresponding to different steel bar diameters, and establish the capacitance value and the steel bar diameter. One-to-one correspondence;

1.1.4 Using a data acquisition and processing device, bring the capacitance value obtained in the previous step into formula (1) to detect the diameter of the steel bar; the formula (1) that characterizes the relationship between the capacitance value and the diameter of the steel bar is: C=aB ² +bB+ c;

1.2 Calibration of capacitance value and thickness of steel protection layer

1.2.1 Put the steel bars of the same diameter into the same batch of concrete with different protective layer thickness, and cure the concrete for 28 days;

1.2.2 After the concrete is cured, put the reinforced concrete to be tested into the oven to keep the reinforced concrete with a moisture content of 0;

1.2.3 Take out the reinforced concrete to be tested, assemble the sensor, and scan the electrode plate along the side of the steel bar in the concrete at a constant speed to measure the capacitance value corresponding to the thickness of the steel bar protection layer, and establish the capacitance value and the thickness of the steel bar protection layer. One-to-one correspondence;

1.2.4 The capacitance value obtained by using the data acquisition and processing device is brought into formula (2) to detect the thickness of the steel protection layer; the formula (2) that characterizes the relationship between the capacitance value and the thickness of the steel protection layer is, C=eD ² +fD +g;

1.3 Calibration of capacitance value and steel corrosion status

1.3.1 Put the steel bars of the same diameter into the same batch of concrete with the same protective layer thickness, and cure the concrete for 28 days;

1.3.2 After the concrete has been cured, corrosion of the steel bars is carried out through electrochemical tests. By controlling the power-on time, the steel bars will produce different degrees of corrosion;

1.3.3 After the electrochemical test is completed, put the reinforced concrete to be tested into the oven to keep the reinforced concrete with a moisture content of 0;

1.3.4 Take out the reinforced concrete to be tested, assemble the sensor, and scan the electrode plate at a constant speed from one side of the steel bar in the concrete to the other side, and measure the capacitance values corresponding to different corrosion states of the steel bars;

1.3.5 Take out the corroded steel bars from the concrete, spray an acid rust removal solution on the surface of the corroded steel bars to remove the rust;

1.3.6 Weigh the steel bar after rust removal, compare it with the initial steel bar quality, obtain the steel bar corrosion amount, and establish a one-to-one correspondence between the capacitance value and the steel bar corrosion amount;

1.3.7 Bring the capacitance value and the steel corrosion amount obtained by the data acquisition and processing device into formula (3) for quantitative detection of the steel corrosion amount; the formula (3) that characterizes the relationship between the capacitance value and the corrosion state of the steel bar is, C=K ₀ *△M.

As mentioned above, the advantages of the device and method for detecting steel bars in concrete of the present application are:

1. Using the principle of electrostatic field capacitance, it can quickly and accurately detect multiple data such as the position, size and rust amount of steel bars in concrete, and realize a non-destructive testing method, which can greatly improve the efficiency and efficiency of project acceptance and inspection and appraisal. accuracy.

2. The detection and data correction are carried out by the capacitance sensor, the result is more accurate and convenient, and the capacitance sensor is not affected by the difference of materials, effectively avoiding errors.

Description of the drawings

This application will now be further explained in conjunction with the following drawings.

Figure 1 is a schematic diagram of the detection device described in this application;

Figure 2 is a schematic diagram of a data acquisition and processing device;

Fig. 3 is a schematic side sectional view of the electrode plate;

Fig. 4 is a schematic diagram of a front cross-section of the electrode plate;

Figure 5 is an analysis diagram of detection data;

Figure 6 is a schematic diagram of detecting the position of steel bars;

Figure 7 is a schematic diagram of detecting the diameter of steel bars;

Figure 8 shows the relationship between the amount of steel corrosion and the capacitance value.

In the above figure, there are: 1-display module; 2-pole plate connection line socket; 3-sliding trolley connection line; 4-operation module; 5-indicator light; 6-hook; 7-computer connection line socket; 8-power supply Charging line socket; 9-switch button; 10-steel bar; 11-electrode plate; 12-connection line between electrode plate and data acquisition and processing device; 13-data acquisition and processing device; 14-concrete; 15-copper electrode; 16-polya Methyl acrylate; 17-plastic shell; 18-plastic filler.

Detailed ways

Embodiment 1. The following describes the embodiments of the present application in detail with reference to the accompanying drawings.

As shown in Figures 1 to 4, this application is based on the principle of electrostatic field capacitance. The said device for detecting steel bars in concrete mainly includes electrode plate 11, DC power supply, data acquisition and processing device 13, electrode plate and data acquisition and processing device的连接线12。 The connection line 12.

Wherein, the electrode plate 11 includes a copper electrode 15, a polymethyl methacrylate 16 and a moisture content test device.

Copper electrodes 15 (as shown in Figure 4) are used to generate excitation voltage and induced voltage. The distance between the copper electrodes can be 0.5 cm. Two copper electrodes 15 are placed at the same level and the same level. The size of the electrode plate 11 It is 7.5cm×4cm×0.1mm.

The encapsulated copper electrode 15 can be polymethyl methacrylate 16 to ensure that the electrode plate 11 is in an insulated state.

The plastic casing 17 further encapsulates the encapsulated polymethyl methacrylate 16 so as to effectively protect the copper electrode 15. The size of the polymethyl methacrylate 16 is 8.5 cm×8.7 cm×2 mm.

The plastic casing 17 has a cubic structure, and the copper electrode 15 is closely attached to the inner wall of one side of the casing 17 to facilitate detection.

The detection principle is to determine the state of the steel bars according to the fluctuation of the capacitance value and the size of the capacitance value.

The capacitance value of the parallel capacitance sensor can be calculated by the following formula:

Among them, C is the capacitance between the two plates of the capacitive sensor, in farads (F) as the unit;

A is the (effective) area between the two plates, in square meters;

ε _r is the relative permittivity of the material between the plates;

ε is the absolute dielectric constant in vacuum (8.854×10 ^-12 Fm ^-1 );

d is the separation distance between the plates, in meters.

Since the distance between the electrode plates 11 and the effective area of the electrode plates 11 remain unchanged, the detection substance between the copper electrodes 15 changes, that is, the dielectric constant (ε _r ) between the copper plates 15 changes, causing the electrodes The capacitance (C) between the plates changes.

The difference in the position and size of the steel bars in the concrete between the electrode plates 11 and the amount of steel corrosion will cause the dielectric constant (ε _r ) between the electrode plates to change. This principle is used to detect the state of the steel bars in the concrete.

The DC power supply supplies a stable 1.0V constant voltage to the electrode plate 11 so that the electrode plate 11 generates an excitation voltage.

The data acquisition and processing device 13 includes, as shown in Fig. 2:

Capacitance meter, used to detect the capacitance value between the electrode plates 11, and its angular frequency is set to 10KHz;

The display module 1 is used for man-machine interactive operation after the completion. The display module 1 is connected with the capacitance meter to display the value obtained after the capacitance sensor is detected. The value can be displayed by digital display, curve display and bar display;

Operation module 4, used to manually input some specific engineering information, so as to be able to set parameters, switch the display mode and set the brightness, etc.;

Processing module, used for data analysis and statistics of the measured value of the capacitance meter and other related values;

The data connection line socket 2 is connected to the data acquisition and processing device 13 and the electrode plate 11;

Indicator light 5, always on means that the equipment is normal and ensure the equipment is working normally

Hook 6 for easy carrying during testing;

The computer connection line jack 7 is used to connect with the computer to facilitate the import of the data into the computer for storage and further analysis and processing of the data;

The power charging line socket 10 is used for charging the data acquisition and processing device to ensure normal operation and provide voltage for the electrodes.

Based on the application of the above detection device, this application also implements the following method for detecting steel bars in concrete.

The detection method is based on the principle of electrostatic field capacitance and includes the following implementation steps:

1) Calibration

Calibration refers to the establishment of a characterization mapping with the state of the steel bar based on the capacitance value data. Said calibration includes calibration of capacitance value and steel bar diameter, calibration of capacitance value and steel protection layer thickness, calibration of capacitance value and steel corrosion state, etc. specifically,

1.1 Calibration of capacitance value and steel bar diameter

1.1.4 Use the data acquisition and processing device to bring the capacitance value obtained in the previous step into formula (1) to detect the diameter of the steel bar;

The formula (1) that characterizes the relationship between the capacitance value and the diameter of the steel bar is: C=aB ² +bB+c.

1.2 Calibration of capacitance value and thickness of steel protection layer

1.2.3 Take out the reinforced concrete to be tested, assemble the sensor, and scan the electrode plate along the side of the steel bar in the concrete at a constant speed to measure the capacitance values corresponding to the thickness of the steel bar protection layer. One-to-one correspondence;

1.2.4 The capacitance value obtained by using the data acquisition and processing device is brought into formula (2) to detect the thickness of the steel protection layer; the formula (2) that characterizes the relationship between the capacitance value and the thickness of the steel protection layer is: C=eD ² +fD +g.

1.3 Calibration of capacitance value and steel corrosion status

1.3.1 Put the steel bars with the same diameter into the same batch of concrete with the same protective layer thickness, and cure the concrete for 28 days;

1.3.3 After the electrochemical test is completed, put the reinforced concrete to be tested into the oven to keep the reinforced concrete with a moisture content of 0.

1.3.7 Bring the capacitance value and the steel corrosion amount obtained by the data acquisition and processing device into the formula (3) for quantitative detection of the steel corrosion amount;

The formula (3) that characterizes the relationship between the capacitance value and the corrosion state of the steel bar is: C=K ₀ *△M.

2) Obtain data from actual measurement

2.1 Connect the electrode plate to the data acquisition and processing device and turn it on. The indicator light in the data acquisition and processing device is always on, indicating that the equipment is normal;

2.2 Actual inspection of reinforced concrete structures

Place the electrode plate on one side of the concrete, operate the operation module in the data acquisition and processing device, input the necessary engineering information, scan the electrode plate along the concrete side to the other side at a constant speed to obtain the capacitance values of different positions. The capacity of the room can be expressed as:

In the formula, C is the capacitance between the electrode plates, a is the length of the electrode plates, b is the width of the electrode plates, d is the distance between the electrode plates, K ₀ is the coefficient of different types of reinforced concrete, and ε _x is The relative dielectric constant between the electrode plates; when other parameters are unchanged, the change of the relative dielectric constant between the electrode plates will directly affect the change of the capacitance.

3) Data processing and analysis

3.1 Scale the test target along the moving direction of the electrode plate;

The position of the steel bar is detected, and the position of the steel bar in the concrete can be determined by the fluctuation of the capacitance value. The relationship between the capacitance value and the diameter of the steel bar is expressed as: C=aB ² +bB+c (1);

Place the electrode plate on the surface of the reinforced concrete, scan the electrode plate from one side of the reinforced concrete surface to the other at a constant speed, and measure the moisture content of the reinforced concrete and the capacitance value of each position with a step length of 2.5mm;

The data acquisition and processing device obtains the corrected capacitance value of each position through the relationship between the moisture content and the capacitance value. As shown in Fig. 6, it shows that the capacitance sensor can detect the positional relationship of the steel bars.

To detect the thickness of the protective layer of the steel bar, the relational expression is: C=eD ² +fD+g (2);

In the above two formulas, C is the corrected capacitance value, B is the diameter of the steel bar, D is the thickness of the protective layer of the steel bar, and a, b, c, e, f, and g are the values obtained after fitting;

Detect the diameter of the rebar

Place the electrode plate on the surface of the reinforced concrete, scan the electrode plate 11 along the surface of the reinforced concrete with the same steel protection layer thickness and different steel diameters at a constant speed to the other side, and correct the maximum capacitance and moisture content of each measurement. Compare the relationship between the capacitance value of the same steel protection layer thickness under different steel diameters;

The relationship between the diameter of the steel bar and the capacitance value is: C=aB ² +bB+c, where C is the corrected capacitance value, B is the diameter of the steel bar, and a, b, and c are the values obtained after fitting, as shown in the figure Figure 7 shows that capacitive sensing can detect the relationship between the diameter of the steel bar.

Detect the relationship between the amount of steel corrosion and the capacitance value

Scan the electrode plate along the reinforced concrete surface of the same steel protection layer thickness and the same steel diameter at a constant speed from one side to the other side. The capacitance value and moisture content measured each time are corrected, and the corrosion amount of the steel bar is compared with the capacitance value. The relationship is shown in Figure 8.

The expression of the relationship between the capacitance value and the corrosion state of the steel bar is: C=K ₀ *△M (3);

Among them, C is the corrected capacitance value, K ₀ is the coefficient under different reinforced concrete states, and △M is the corrosion amount of the steel bars in the reinforced concrete to be tested.

As mentioned above, in conjunction with the content of the solution given in the drawings and description, similar technical solutions can be derived. However, all the content of the solution that does not deviate from the structure of the present invention still belongs to the right scope of the technical solution of the present application.

Claims

A device for detecting steel bars in concrete, which is characterized in that it includes an electrode plate, a DC power supply, and a data acquisition and processing device;

The electrode plate includes a copper electrode, polymethyl methacrylate and a moisture content test device, and the two copper electrodes are placed on the same level and on the same level;

The data acquisition and processing device includes a capacitance meter, the angular frequency of which is set to 10KHz;

Display module to display the value obtained after the capacitance sensor detects;

Operation module, used for manual actual operation to input specific project information to set parameters;

Processing module, used for data analysis and statistics of the measured value of the capacitance meter and other related values;

The data connection line socket is used to connect the electrode plate.
The method for detecting steel bars in concrete according to claim 1, wherein the state of the steel bars is determined according to the fluctuation of the capacitance value and the capacitance value data, and the calculation formula is as follows:

Among them, C is the capacitance between the two plates of the capacitive sensor, in farads (F);

A is the (effective) area between the two plates, in square meters;

ε r is the relative permittivity of the material between the plates;

ε is the absolute dielectric constant in vacuum (8.854×10 -12 Fm -1 );

d is the separation distance between the plates, in meters;

The change trend of the capacitance between the electrode plates characterizes the difference in the position, size and amount of corrosion of the steel bars in the concrete.
The method for detecting steel bars in concrete according to claim 2, characterized in that: based on the principle of electrostatic field capacitance, the method includes the following implementation steps:

1) Calibration

Calibration refers to the establishment of a characterization mapping with the state of the steel bar based on the capacitance value data. The calibration process includes the calibration of the capacitance value and the diameter of the steel bar, the calibration of the capacitance value and the thickness of the protection layer of the steel bar, and the calibration of the capacitance value and the corrosion state of the steel bar;

2) Obtain data from actual measurement

2.1 Connect the electrode plate to the data acquisition and processing device and turn it on;

2.2 Perform actual inspections on reinforced concrete structures;

Place the electrode plate on one side of the concrete, operate the operation module in the data acquisition and processing device, input necessary engineering information, and scan the electrode plate along the concrete side to the other side at a constant speed to obtain the capacitance values of different positions;

3) Data processing and analysis

3.1 Scale the test target along the moving direction of the electrode plate;

3.2 Establish a two-dimensional coordinate system, the X axis is the scale of the moving direction of the electrode plate, and the Y axis is the capacitance value measured by the capacitance meter;

To detect the position of the steel bar, the relationship between the capacitance value and the diameter of the steel bar is expressed as C=aB 2 +bB+c (1);

The expression of the thickness relation of the protective layer of the steel bar is: C=eD 2 +fD+g (2);

The relationship between the diameter of the steel bar and the capacitance value is: C=aB 2 +bB+c;

The relationship between the amount of corrosion of steel bars and the capacitance value is C=K 0 *△M (3).
The method for detecting steel bars in concrete according to claim 3, wherein the calibration process includes the following steps:

1.1 Calibration of capacitance value and steel bar diameter

1.1.1 Put steel bars of different diameters into the same batch of concrete with the same protective layer thickness, and cure the concrete for 28 days;

1.1.2 After the concrete curing is completed, put the reinforced concrete to be tested into the oven to keep the reinforced concrete with a moisture content of 0;

1.1.3 Take out the reinforced concrete to be tested with a moisture content of 0, use the detection device to scan the electrode plate 11 along the concrete side to the other at a uniform speed, measure the capacitance value corresponding to different steel bar diameters, and establish the capacitance value and the steel bar diameter. One-to-one correspondence;

1.1.4 Using a data acquisition and processing device, bring the capacitance value obtained in the previous step into formula (1) to detect the diameter of the steel bar; the formula (1) that characterizes the relationship between the capacitance value and the diameter of the steel bar is: C=aB 2 +bB+ c;

1.2 Calibration of capacitance value and thickness of steel protection layer

1.2.1 Put the steel bars of the same diameter into the same batch of concrete with different protective layer thickness, and cure the concrete for 28 days;

1.2.2 After the concrete is cured, put the reinforced concrete to be tested into the oven to keep the reinforced concrete with a moisture content of 0;

1.2.3 Take out the reinforced concrete to be tested, assemble the sensor, and scan the electrode plate along the side of the steel bar in the concrete at a constant speed to measure the capacitance value corresponding to the thickness of the steel bar protection layer, and establish the capacitance value and the thickness of the steel bar protection layer. One-to-one correspondence;

1.2.4 The capacitance value obtained by using the data acquisition and processing device is brought into formula (2) to detect the thickness of the steel protection layer; the formula (2) that characterizes the relationship between the capacitance value and the thickness of the steel protection layer is, C=eD 2 +fD +g;

1.3 Calibration of capacitance value and steel corrosion status

1.3.1 Put the steel bars with the same diameter into the same batch of concrete with the same protective layer thickness, and cure the concrete for 28 days;

1.3.2 After the concrete has been cured, corrosion of the steel bars is carried out through electrochemical tests. By controlling the power-on time, the steel bars will produce different degrees of corrosion;

1.3.3 After the electrochemical test is completed, put the reinforced concrete to be tested into the oven to keep the reinforced concrete with a moisture content of 0;

1.3.4 Take out the reinforced concrete to be tested, assemble the sensor, and scan the electrode plate at a constant speed from one side of the steel bar in the concrete to the other side, and measure the capacitance values corresponding to different corrosion states of the steel bars;

1.3.5 Take out the corroded steel bars from the concrete, spray an acid rust removal solution on the surface of the corroded steel bars to remove the rust;

1.3.6 Weigh the steel bar after rust removal, compare it with the initial steel bar quality, obtain the steel bar corrosion amount, and establish a one-to-one correspondence between the capacitance value and the steel bar corrosion amount;

1.3.7 Bring the capacitance value and the steel corrosion amount obtained by the data acquisition and processing device into formula (3) for quantitative detection of the steel corrosion amount; the formula (3) that characterizes the relationship between the capacitance value and the corrosion state of the steel bar is, C=K 0 *△M.