A concrete structure durability monitoring device and monitoring method

Abstract

The present invention provides a durability monitoring device and a monitoring method for a concrete structure, wherein the device comprises a reference electrode, a working electrode, an auxiliary electrode, an insulating ring and a sealing layer, the working electrode and the auxiliary electrode are both ring-shaped, the auxiliary electrode, the insulating ring and the working electrode are sleeved on the outer wall of the reference electrode from top to bottom, the exposed parts of the auxiliary electrode, the insulating ring and the working electrode are coated with a water-permeable protective layer, the water-permeable protective layer is fixedly connected to the outer wall of the reference electrode to fix the auxiliary electrode, the insulating ring and the working electrode on the outer wall of the reference electrode, the sealing layer is coated on the top of the reference electrode and contacts the water-permeable protective layer, the reference electrode is connected with a first wire, the working electrode is connected with a second wire, the auxiliary electrode is connected with a third wire, and the first wire, the second wire and the third wire are collected, penetrate the sealing layer from bottom to top and extend outside the sealing layer. The present invention aims to solve the shortcomings of existing concrete structure corrosion monitoring sensors.

Description

Technical Field

[0001] The invention belongs to the technical field of corrosion and protection of reinforced concrete structures, and in particular relates to a concrete structure durability monitoring device and a monitoring method. Background Art

[0002] In reinforced concrete structures, since concrete is a porous and brittle material, it is corroded by external corrosive media for a long time during the service life of the project, causing corrosion of internal steel bars, resulting in poor structural bearing capacity, and in severe cases, structural failure and damage, bringing immeasurable economic losses. Therefore, it is very necessary to implement durability monitoring of reinforced concrete structures in harsh corrosive environments, and to predict the service life of existing concrete structures, so as to achieve "early treatment of diseases and early prevention of diseases".

[0003] At present, the most commonly used sensor at home and abroad is the anode ladder system produced by S+R Sensortec in Germany. This sensor can determine the corrosion time and corrosion depth of the steel bar by monitoring the corrosion potential and corrosion current of the anode at different depths. This anode ladder system is already very mature, but due to its large size, the on-site installation and debugging process is inconvenient, time-consuming and labor-intensive, and the large size makes it difficult to ensure that the sensor will not be damaged or malfunction due to accidental contact during construction site operations. In addition, the Corrowatch sensor and Corrorisk sensor produced by FORCE should also be widely used. Both are post-installed corrosion monitoring sensors. The principles of both are similar to the anode ladder. Anodes at different depths are buried to monitor their corrosion potential and corrosion current, thereby judging the corrosion depth of the concrete structure. These two sensors are relatively economical and widely applicable, but because external drilling is required, there is a risk of external ion longitudinal penetration interference after the sensor is buried in the encapsulation mortar. The ECI sensor developed by Virginia Company in the United States can measure corrosion parameters such as steel bar corrosion potential, corrosion current, pH, concrete resistivity, and chloride ion concentration. However, due to the small size of the working electrode, it is greatly affected by local factors in the concrete environment, so that the stability of the monitored data is poor, and the product relies on imports and is expensive.

[0004] Under the active call of the century-old quality engineering brand, the durability requirements of reinforced concrete structures are more stringent. In order to ensure the efficient operation and maintenance of the reinforced concrete structure of the project, the corrosion of the reinforced concrete structure can be discovered early and necessary remedial measures can be taken. Therefore, a concrete structure durability monitoring device and monitoring method are urgently needed in China to solve the shortcomings of the existing concrete structure corrosion monitoring sensors. Summary of the invention

[0005] The purpose of the present invention is to provide a concrete structure durability monitoring device and a monitoring method, aiming to solve the shortcomings of existing concrete structure corrosion monitoring sensors.

[0006] The present invention is achieved through the following technical solutions:

[0007] A concrete structure durability monitoring device comprises a reference electrode, a working electrode, an auxiliary electrode, an insulating ring and a sealing layer. The working electrode and the auxiliary electrode are both ring-shaped. The auxiliary electrode, the insulating ring and the working electrode are sleeved on the outer wall of the reference electrode from top to bottom. The exposed parts of the auxiliary electrode, the insulating ring and the working electrode are covered with a water-permeable protective layer. The water-permeable protective layer is fixedly connected to the outer wall of the reference electrode to fix the auxiliary electrode, the insulating ring and the working electrode on the outer wall of the reference electrode. The sealing layer is covered on the top of the reference electrode and contacts the water-permeable protective layer. The reference electrode is connected to a first wire, the working electrode is connected to a second wire, and the auxiliary electrode is connected to a third wire. After the first wire, the second wire and the third wire are collected, they pass through the sealing layer from bottom to top and extend outside the sealing layer.

[0008] Furthermore, the reference electrode includes a polytetrafluoroethylene tube with an opening at the lower end, the polytetrafluoroethylene tube is filled with a KCl gel electrolyte layer and a porous diatomaceous earth sealing layer, an Ag / AgCl probe is provided at the central axis of the polytetrafluoroethylene tube, the top of the Ag / AgCl probe is connected to the first wire, a waterproof interface is provided at the center of the top of the polytetrafluoroethylene tube, the top of the waterproof interface penetrates the sealing layer and extends outside the sealing layer, the second wire and the third wire pass through the side wall of the polytetrafluoroethylene tube and merge with the first wire, and then pass through the waterproof interface to the outside of the polytetrafluoroethylene tube.

[0009] Furthermore, the polytetrafluoroethylene tube includes a tube wall, a accommodating cavity is provided in the tube wall, and an opening connected to the accommodating cavity is provided at the lower end of the tube wall, a tube cap for sealing is detachably connected to the lower end of the tube wall, two wire holes connected to the accommodating cavity are provided on the outer side of the tube wall, and a wire hole connected to the accommodating cavity is also provided on the inner side of the tube wall, the second wire and the third wire respectively pass through the two wire holes on the outer side of the tube wall and then extend into the accommodating cavity, and pass through the wire holes on the inner side of the tube wall and then merge with the first wire, and the accommodating cavity is filled with epoxy resin.

[0010] Furthermore, the auxiliary electrode is a chemically inert MMO titanium-based mixed metal oxide anode mesh.

[0011] Furthermore, the thickness of the water-permeable protective layer is 1 to 2 cm, and / or the water-permeable protective layer is a high-permeability concrete layer.

[0012] Furthermore, the lower end surface of the water-permeable protective layer is flush with the lower end surface of the reference electrode, and the sum of the heights of the water-permeable protective layer and the sealing layer is less than or equal to 120 mm.

[0013] Furthermore, the cross-sectional diameter of the water-permeable protective layer is equal to the cross-sectional diameter of the sealing layer, and the cross-sectional diameter of the water-permeable protective layer is less than or equal to 50 mm.

[0014] Furthermore, the sealing layer is an epoxy resin layer.

[0015] Furthermore, the insulating ring is a rubber insulating ring.

[0016] The present invention also provides a method for monitoring the durability of a concrete structure, using any of the above-mentioned devices for monitoring the durability of a concrete structure, the method comprising the following steps:

[0017] Assembling any one of the above-mentioned concrete structure durability monitoring devices, and burying the concrete structure durability monitoring device in the concrete protective layer of the concrete structure to be tested;

[0018] A constant current pulse is applied between the auxiliary electrode and the working electrode, and the polarization potential data between the working electrode and the reference electrode are acquired by real-time monitoring to obtain a curve of the polarization potential changing with time;

[0019] Based on the curve of polarization potential changing with time, the annualized corrosion rate of the steel bar at the working electrode location is calculated according to the following formula:

[0020]

[0021]

[0022]

[0023] Corrosion=11.6*I corr / A (4)

[0024] Among them, U t is the polarization potential, I app is the applied constant current pulse, R p is the polarization resistance, C dl is the double layer capacitance, R Ω is the ohmic resistance, t is the time, the zero point is when the constant current pulse is applied, U max is the steady-state point reached by the working electrode after long-term polarization, B is an empirical constant, for activated corroded steel bars, B is 25mV, for passivated steel bars, B is 50mV, I corr is the corrosion current density, Corrosion is the annualized corrosion rate, and A is the ratio of the surface area of ​​the working electrode to that of the auxiliary electrode;

[0025] Based on the calculated annualized steel corrosion rate, the durability of the tested concrete structure is determined.

[0026] Compared with the prior art, the present invention has the following beneficial effects: the wrapped sleeve structure is adopted, so that the overall size is small, the installation is convenient, and the impact on the concrete structure is small, and it is particularly suitable for durability monitoring of concrete structures in seaport projects; based on the current step technology in corrosion detection, a three-electrode system is introduced, which can eliminate the interference of current loss and unstable monitoring data caused by the uncertainty of the steel bar area in corrosion detection, and realize accurate measurement of polarization resistance, with good measurement stability, and can evaluate the corrosion condition of concrete structures; the outermost layer is a water-permeable protective layer and a sealing layer, and the sealing layer located on the upper part can eliminate the interference caused by the concrete components being tested. Drilling causes longitudinal interference in the penetration of ions and water. The water-permeable protective layer located at the bottom can ensure the lateral transmission of ions and water between the concrete structure durability monitoring device of the present invention and the old concrete, thereby ensuring the accuracy of the monitoring data, so as to improve the monitoring accuracy of the present invention as a post-installed corrosion monitoring device. At the same time, when the present invention is used as a pre-embedded corrosion monitoring device, the water-permeable protective layer and the sealing layer are both insulating layers, and the present invention can be directly fixed on the steel bars of the concrete component, and the installation is relatively simple and quick. Therefore, the present invention can meet the use requirements as a pre-embedded corrosion monitoring device and a post-installed corrosion monitoring device, and has a wide range of uses. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a cross-sectional view of a concrete structure durability monitoring device of the present invention;

[0028] Figure 2 It is a top view of the concrete structure durability monitoring device of the present invention;

[0029] Figure 3 In order to bury the concrete structure durability monitoring device in a concrete component to be tested, a constant current pulse response polarization potential change curve over time is applied.

[0030] In the figure, 1-reference electrode, 11-polytetrafluoroethylene tube, 111-tube wall, 112-tube cap, 13-epoxy resin, 12-KCl gel electrolyte layer, 13-porous diatomaceous earth sealing layer, 14-Ag / AgCl probe, 15-waterproof interface, 2-working electrode, 3-auxiliary electrode, 4-insulating ring, 5-sealing layer, 6-water-permeable protective layer, 7-second wire, 8-third wire. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0032] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings. At the same time, in the description of the present invention, the terms "first", "second", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0034] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0035] In the description of the present invention, it should be noted that the terms "upper", "lower", "inside", "outside", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, or are directions or positional relationships in which the product of the invention is usually placed when in use. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.

[0036] See also Figure 1 , Figure 1 is a cross-sectional view of a concrete structure durability monitoring device according to the present invention, Figure 2 The top view of the durability monitoring device of a concrete structure of the present invention is shown in FIG. A durability monitoring device for a concrete structure, which contains a three-electrode system composed of a reference electrode 1, a working electrode 2, and an auxiliary electrode 3, can accurately measure the corrosion rate of steel bars and can meet the detection of the corrosion potential of concrete components, that is, the corrosion current. The outer part is composed of an upper sealing layer 5 and a lower water-permeable protective layer 6, which can eliminate longitudinal ion interference and ensure the accuracy of monitoring data.

[0037] Specifically, the working electrode 2 and the auxiliary electrode 3 are both ring-shaped, and the working electrode 2 is made of the same steel material as the steel bars in the concrete member to be measured. The auxiliary electrode 3 is a chemically inert MMO titanium-based mixed metal oxide anode mesh. The auxiliary electrode 3, the insulating ring 5 and the working electrode 2 are sleeved on the outer wall of the reference electrode 1 from top to bottom, and the working electrode 2 and the auxiliary electrode 3 are separated by the insulating ring 5, and the inner walls of the working electrode 2, the auxiliary electrode 3 and the insulating ring 5 are all in contact with the outer wall of the reference electrode 1. In one embodiment, the insulating ring 5 is a rubber insulating ring.

[0038] The exposed parts of the auxiliary electrode 3, the insulating ring 5 and the working electrode 2 are coated with a water-permeable protective layer 6, and the water-permeable protective layer 6 is fixedly connected to the outer wall of the reference electrode 1 to fix the auxiliary electrode 3, the insulating ring 5 and the working electrode 2 on the outer wall of the reference electrode 1, so that the bottom of the reference electrode 1 is exposed. During the monitoring process, it is convenient for the reference electrode 1 to contact the concrete of the measured concrete structure to obtain monitoring data. The water-permeable protective layer 6 has high permeability, which can ensure the free lateral penetration and diffusion of ions and water, and ensure the accuracy of the monitoring data. In one embodiment, the thickness of the water-permeable protective layer 6 is 1 to 2 cm, and / or the water-permeable protective layer 6 is a high-permeability concrete layer. The sealing layer 5 is coated on the top of the reference electrode 1 and contacts the water-permeable protective layer 6. The sealing layer 5 can eliminate the longitudinal interference of ion and water penetration caused by drilling holes in the measured concrete component, and further ensure the accuracy of the monitoring data. In one embodiment, the sealing layer 5 is an epoxy resin layer. The reference electrode 1 is connected to a first wire, the working electrode 2 is connected to a second wire 7, and the auxiliary electrode 3 is connected to a third wire 8. After the first wire, the second wire 7 and the third wire 8 are gathered, they penetrate the sealing layer 5 from bottom to top and extend outside the sealing layer 5 for connection with external instruments. The durability monitoring device of the concrete structure of the present invention adopts a wrapped sleeve structure, which makes the overall size small, easy to install, and has little impact on the concrete structure. In one embodiment, the lower end face of the water-permeable protective layer 6 is flush with the lower end face of the reference electrode 1, and the sum of the heights of the water-permeable protective layer 6 and the sealing layer 5 is less than or equal to 120 mm. The cross-sectional diameter of the water-permeable protective layer 6 is equal to the cross-sectional diameter of the sealing layer 5, and the cross-sectional diameter of the water-permeable protective layer 6 is less than or equal to 50 mm.

[0039] In one embodiment, the reference electrode 1 comprises a polytetrafluoroethylene tube 11 with an opening at the lower end, the polytetrafluoroethylene tube 11 is made of polytetrafluoroethylene, the polytetrafluoroethylene tube 11 is filled with a KCl gel electrolyte layer 12 and a porous diatomite plugging layer 13, the KCl gel electrolyte layer 12 is composed of a KCl gel electrolyte, the porous diatomite plugging layer 13 is made of porous diatomite, the porous diatomite is an existing product, and the gap between the porous diatomite plugging layer 13 and the polytetrafluoroethylene tube 11 is sealed with epoxy resin. An Ag / AgCl probe 14 is provided at the central axis of the polytetrafluoroethylene tube 11, the top of the Ag / AgCl probe 14 is connected to the first wire, a waterproof interface 15 is provided at the center of the top of the polytetrafluoroethylene tube 11, the top of the waterproof interface 15 penetrates the sealing layer 5 and extends outside the sealing layer 5, the second wire 7 and the third wire 8 pass through the side wall of the polytetrafluoroethylene tube 11 and converge with the first wire, and then pass through the waterproof interface 15 to the outside of the polytetrafluoroethylene tube 11. The reference electrode 1 is an Ag / AgCl electrode containing a KCl gel electrolyte, which has long-lasting effect and high stability. The water-permeable protective layer 6 fixes the auxiliary electrode 3, the insulating ring 5 and the working electrode 2 on the polytetrafluoroethylene tube 11. In one embodiment, the polytetrafluoroethylene tube 11 includes a tube wall 111, a receiving cavity is provided in the tube wall 111, and an opening communicating with the receiving cavity is provided at the lower end thereof, and a tube cap 112 for sealing is detachably connected to the lower end of the tube wall 111. Preferably, the tube wall 111 is threadedly connected to the tube cap 112, and the connection between the tube wall 111 and the tube cap 112 makes the receiving cavity sealed. Two wire holes communicating with the receiving cavity are provided on the outer side of the tube wall 111, and a wire hole communicating with the receiving cavity is also provided on the inner side thereof. The second wire and the third wire respectively pass through the two wire holes on the outer side of the tube wall 111 and extend into the receiving cavity, and pass through the wire holes on the inner side of the tube wall 111 and then converge with the first wire, and the receiving cavity is filled with epoxy resin 13. An accommodating cavity is provided in the tube wall 111 to facilitate the placement of the second wire 7 and the third wire 8 , and the accommodating cavity is filled with epoxy resin 13 to ensure sealing.

[0040] The present invention also provides a method for monitoring the durability of a concrete structure, using any of the above-mentioned devices for monitoring the durability of a concrete structure, the method comprising the following steps:

[0041] S1. Assembling any one of the above-mentioned concrete structure durability monitoring devices, and burying the concrete structure durability monitoring device in the concrete protective layer of the concrete structure to be tested;

[0042] S2, applying a constant current pulse between the auxiliary electrode 3 and the working electrode 2, and acquiring polarization potential data between the working electrode 2 and the reference electrode 1 in real time to obtain a curve of polarization potential changing with time;

[0043] S3. Based on the curve of polarization potential changing with time, the annualized steel bar corrosion rate at the location of the working electrode 2 is calculated according to the following formula:

[0044]

[0045]

[0046]

[0047] Corrosion=11.6*I corr / A (4)

[0048] Among them, U t is the polarization potential, I app is the applied constant current pulse, R p is the polarization resistance, C dl is the double layer capacitance, R Ω is the ohmic resistance, U max is the steady-state point reached by the working electrode 2 after long-term polarization, B is an empirical constant, for activated corroded steel bars, B is 25 mV, for passivated steel bars, B is 50 mV, Corrosion is the annualized corrosion rate, A is the ratio of the surface area of ​​the working electrode 2 to that of the auxiliary electrode 3;

[0049] S4. Determine the durability of the concrete structure under test based on the calculated annualized steel corrosion rate.

[0050] In the above step S1, the assembly process of the concrete structure durability monitoring device of the present invention is as follows: after the working electrode 2, the insulating ring 5 and the auxiliary electrode 3 are sequentially installed on the polytetrafluoroethylene tube 11, the second wire 7 and the third wire 8 respectively pass through the two wire holes on the outer side of the tube wall 111 and extend into the accommodating cavity, and then pass through the wire holes on the inner side of the tube wall 111 and merge with the first wire to form a wire lead-out end, and the wire lead-out end is led out from the waterproof interface 15 at the top of the polytetrafluoroethylene tube 11 to the polytetrafluoroethylene On the outside of the tube 11, a KCl gel electrolyte layer 12 and a porous diatomite plugging layer 13 are filled into the polytetrafluoroethylene tube 11, so that the Ag / AgCl probe 14 is located at the central axis of the polytetrafluoroethylene tube 11, and then epoxy resin 13 is filled into the accommodating cavity of the tube wall 111, so that the gaps between the second wire 7 and the third wire 8 and the corresponding wire holes are sealed with epoxy resin, and a tube cap 112 is installed on the tube wall 111, and the tube cap 112 and the porous diatomite plugging layer 13 are sealed with epoxy resin. Then, a water-permeable protective layer 6 is cast on the outside formed by the working electrode 2, the insulating ring 5 and the reference electrode 1, and the top of the reference electrode 1 is sealed with a sealing layer 5. After the assembly is completed, if it is used for an in-service reinforced concrete structure, a hole is drilled on the surface of the concrete structure to be tested, the diameter of the drilled hole is matched with the cross-sectional diameter of the concrete structure durability monitoring device of the present invention, and then the concrete structure durability monitoring device of the present invention is inserted into the drilled hole to expose the lead-out end of the wire, and the hole left on the surface of the concrete structure to be tested is sealed with an appropriate amount of mortar; if it is used for a pre-buried reinforced concrete structure, it is only necessary to install and fix the concrete structure durability monitoring device of the present invention on the concrete protective layer of the concrete structure to be tested, perpendicular to the steel bar surface, and lead out the lead-out end of the wire.

[0051] Please refer to Figure 3 , Figure 3 In order to bury the durability monitoring device of concrete structure in a concrete member to be tested, a curve of polarization potential variation over time in response to a constant current pulse is obtained. In the above step S2, a constant current pulse is applied between the auxiliary electrode 3 and the working electrode 2 through an externally connected instrument terminal to monitor the polarization potential data between the working electrode 2 and the reference electrode 1 inside the reinforced concrete structure, and the obtained polarization potential data is analyzed. According to the relationship between the polarization potential data and time, a curve of polarization potential variation over time in response to a constant current pulse is obtained, such as Figure 3 shown.

[0052] In the above step S3, based on the obtained curve of polarization potential changing with time, the steel bar polarization potential U t The relationship with time t can be expressed by formula (1):

[0053]

[0054] Then, formula (1) can be expressed as a linear relationship and converted into:

[0055]

[0056] When t = 0, the least squares linear regression analysis can be used to obtain the corresponding slope and the intercept value ln(I app *R p ), the polarization resistance R p The value of .

[0057] The corrosion current density I is calculated according to the Stern Geary formula. corr :

[0058]

[0059] For the judgment of activated corroded steel bars and passivated steel bars, the response curve under the current step can be used to determine whether the initial potential is less than the corrosion potential of the steel bars to determine whether the steel bars are corroded.

[0060] According to Faraday's law, the corrosion current density I corr Converted to corrosion rate Corrosion, based on the known 1μA / cm 2 The cross-sectional area loss of carbon steel is about 11.6 μm / a. Therefore, the corrosion rate at the current position of the working electrode 2 is calculated according to the following formula (4):

[0061] Corrosion=11.6*I corr / A (4)

[0062] In the above step S4, if the annualized corrosion rate increases sharply at a certain moment, it means that the steel bar at the position of the working electrode 2 is corroded. When the annualized corrosion rate increases and reaches a certain level, it means that the service life of the concrete component under test has expired and can no longer be used. Therefore, the durability of the concrete component under test can be determined based on the size of the annualized corrosion rate. Specifically, a critical threshold is pre-set, and then during the monitoring process, it is determined whether the annualized corrosion rate is greater than the preset critical threshold. If so, it means that the service life of the concrete component under test has expired and can no longer be used, thereby determining the durability of the concrete component under test. The current step technology is used to measure and analyze the relationship between the polarization potential of the steel bar and time, monitor the corrosion status of the steel bar, and introduce the surface area ratio A of the working electrode 2 and the auxiliary electrode 3 into the annualized corrosion rate calculation formula. There is no need to externally determine the steel bar area within the unit monitoring area, which avoids the influence of the current applied to the steel bar easily flowing along the steel bar during the polarization process, resulting in inaccurate monitoring data. Therefore, the calculated annualized corrosion rate is more scientific and accurate. Therefore, it is more scientific and accurate to confirm the durability of the concrete structure under test.

[0063] Compared with the prior art, the beneficial effects of the present invention are as follows: the use of a wrapped sleeve structure makes the overall size small, easy to install, and has little impact on the concrete structure, and is particularly suitable for durability monitoring of concrete structures in seaport projects; based on the current step technology in corrosion detection, a three-electrode system is introduced to eliminate the interference of current loss and unstable monitoring data caused by the uncertainty of the steel bar area in corrosion detection, and to achieve accurate measurement of polarization resistance with good measurement stability, which can evaluate the corrosion condition of concrete structures; the outermost layer is a water-permeable protective layer 6 and a sealing layer 5, and the sealing layer 5 located on the upper part can eliminate the interference caused by the concrete component being tested. Drilling causes longitudinal interference in the penetration of ions and water. The water-permeable protective layer 6 located at the bottom can ensure the lateral transmission of ions and water between the concrete structure durability monitoring device of the present invention and the old concrete, thereby ensuring the accuracy of the monitoring data, so as to improve the monitoring accuracy of the present invention as a post-installed corrosion monitoring device. At the same time, when the present invention is used as a pre-embedded corrosion monitoring device, the water-permeable protective layer 6 and the sealing layer 5 are both insulating layers, and the present invention can be directly fixed on the steel bars of the concrete component, and the installation is relatively simple and quick. Therefore, the present invention can meet the use requirements as a pre-embedded corrosion monitoring device and a post-installed corrosion monitoring device, and has a wide range of uses.

[0064] The present invention is not limited to the above-mentioned embodiments. If various changes or modifications to the present invention do not depart from the spirit and scope of the present invention, and if these changes and modifications fall within the scope of the claims and equivalent technologies of the present invention, the present invention is also intended to include these changes and modifications.

Claims

1. A method for monitoring the durability of a concrete structure, using a device for monitoring the durability of a concrete structure, It is characterized in that The concrete structure durability monitoring device comprises a reference electrode, a working electrode, an auxiliary electrode, an insulating ring and a sealing layer, wherein the working electrode and the auxiliary electrode are both ring-shaped, and the auxiliary electrode, the insulating ring and the working electrode are sleeved on the outer wall of the reference electrode from top to bottom, and the exposed parts of the auxiliary electrode, the insulating ring and the working electrode are covered with a water-permeable protective layer, and the water-permeable protective layer is fixedly connected to the outer wall of the reference electrode to fix the auxiliary electrode, the insulating ring and the working electrode on the outer wall of the reference electrode, and the sealing layer is covered on the top of the reference electrode and contacts the water-permeable protective layer, and the reference electrode is connected to a first wire, and the working electrode is connected to a second wire, and the auxiliary electrode is connected to a third wire, and after the first wire, the second wire and the third wire are collected, they penetrate the sealing layer from bottom to top and extend out of the sealing layer; The method comprises the following steps: Assembling the concrete structure durability monitoring device, and burying the concrete structure durability monitoring device in the concrete protective layer of the concrete structure to be tested; Applying a constant current pulse between the auxiliary electrode and the working electrode, monitoring and acquiring polarization potential data between the working electrode and the reference electrode in real time, and obtaining a curve of polarization potential changing with time; Based on the curve of polarization potential changing with time, the annualized corrosion rate of the steel bar at the working electrode location is calculated according to the following formula: Corrosion=11.6*I corr / A (4) Among them, U t is the polarization potential, I app is the applied constant current pulse, R p is the polarization resistance, C dl is the double layer capacitance, R Ω is the ohmic resistance, t is the time, the zero point is when the constant current pulse is applied, U max is the steady-state point reached by the working electrode after long-term polarization, B is an empirical constant, for activated corroded steel bars, B is 25 mV, for passivated steel bars, B is 50 mV, I corr is the corrosion current density, Corrosion is the annualized corrosion rate, and A is the ratio of the surface area of ​​the working electrode to the auxiliary electrode; Based on the calculated annualized corrosion rate, the durability of the tested concrete structure is determined.

2. The method for monitoring the durability of a concrete structure according to claim 1, It is characterized in that The reference electrode comprises a polytetrafluoroethylene tube with an opening at the lower end, the polytetrafluoroethylene tube is filled with a KCl gel electrolyte layer and a porous diatomaceous earth plugging layer, an Ag / AgCl probe is arranged at the central axis of the polytetrafluoroethylene tube, the top end of the Ag / AgCl probe is connected to the first wire, a waterproof interface is arranged at the center of the top of the polytetrafluoroethylene tube, the top end of the waterproof interface penetrates the sealing layer and extends outside the sealing layer, the second wire and the third wire pass through the side wall of the polytetrafluoroethylene tube and merge with the first wire, and then pass through the waterproof interface to the outside of the polytetrafluoroethylene tube.

3. The method for monitoring the durability of a concrete structure according to claim 2, It is characterized in that The polytetrafluoroethylene tube includes a tube wall, a containing cavity is provided in the tube wall, and an opening connected to the containing cavity is provided at the lower end of the tube wall, a tube cap for sealing is detachably connected to the lower end of the tube wall, two wire holes connected to the containing cavity are provided on the outer side of the tube wall, and a wire hole connected to the containing cavity is also provided on the inner side of the tube wall, the second wire and the third wire respectively pass through the two wire holes on the outer side of the tube wall and then extend into the containing cavity, and pass through the wire holes on the inner side of the tube wall and then merge with the first wire, and the containing cavity is filled with epoxy resin.

4. The method for monitoring the durability of a concrete structure according to claim 1, It is characterized in that The auxiliary electrode is a chemically inert MMO titanium-based mixed metal oxide anode mesh.

5. The method for monitoring the durability of a concrete structure according to claim 1, It is characterized in that The thickness of the water-permeable protective layer is 1 to 2 cm, and / or the water-permeable protective layer is a high-permeability concrete layer.

6. The method for monitoring the durability of a concrete structure according to claim 1, It is characterized in that The lower end surface of the water-permeable protective layer is flush with the lower end surface of the reference electrode, and the sum of the heights of the water-permeable protective layer and the sealing layer is less than or equal to 120 mm.

7. The method for monitoring the durability of a concrete structure according to claim 1, It is characterized in that The cross-sectional diameter of the water-permeable protective layer is equal to the cross-sectional diameter of the sealing layer, and the cross-sectional diameter of the water-permeable protective layer is less than or equal to 50 mm.

8. The method for monitoring the durability of a concrete structure according to claim 1, It is characterized in that The sealing layer is an epoxy resin layer.

9. The method for monitoring the durability of a concrete structure according to claim 1, It is characterized in that The insulating ring is a rubber insulating ring.

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