A pre-buried electrode for monitoring volume resistivity of conductive concrete and preparation method thereof

Abstract

The invention discloses an embedded electrode for monitoring the volume resistivity of conductive concrete and a preparation method thereof, which belongs to the field of development and application of conductive concrete, and comprises an embedded electrode sheet and a stabilizing panel. The four corners of the embedded electrode sheet are bent inwards, a square hole is arranged in the middle of the embedded electrode sheet, one side of the square hole is integrally extended outwards to form an access point, and the stabilizing panel is arranged in parallel with and connected to the reserved electrode sheet. The invention connects the integrally formed embedded electrode sheet with a polystyrene plate, and the polystyrene plate plays a role in stabilizing the position of the copper electrode, and at the same time protects the current access point to be clean and easy to use. The copper electrode and the polystyrene plate have low costs and good conductive transmission effects, and can effectively ensure the distance and relative position between electrodes in the conductive concrete, and at the same time improve the safety of the access current, and do not generate pollution during use and installation, which is green and environmentally friendly.

Description

Technical Field

[0001] The invention relates to a pre-buried electrode for monitoring the volume resistivity of conductive concrete and a preparation method thereof, and belongs to the field of development and application of conductive concrete. Background Art

[0002] Conductive concrete relies on the conductive path formed by the internal conductive admixture and the carriers to conduct electrical signals. When the conductive concrete is under the action of external load or when cracks appear inside, it will cause changes in the internal conductive network, resulting in regular changes in the volume resistivity of the conductive concrete. Therefore, as long as the changes in the volume resistivity of the conductive concrete are detected, the load condition and internal cracks of the concrete structure can be known, and long-term, non-destructive safety monitoring of the concrete structure can be achieved. During monitoring, the conductive concrete structure must be connected to the circuit, so the embedded electrodes used in the conductive concrete are crucial.

[0003] Traditional embedded electrodes are made of copper sheets or metal meshes, and there are many problems during use. First of all, the copper sheet electrodes currently used cannot guarantee that their position will not change after the concrete is poured. Once the position of the electrode changes, it will inevitably affect the accuracy of the test results. In addition, the copper sheet electrodes currently used lack a connection design with the concrete matrix. During long-term use, tiny gaps will form between the electrode and the matrix, resulting in increased contact resistance, which seriously affects the accuracy and stability of conductive concrete structure health monitoring. The use of metal mesh electrodes also has the problem of electrode displacement and deformation. In addition, ordinary metal electrodes have poor durability in special environments. It is difficult to function in the high-salinity environment of the coast, and there is a risk of rust and cracking that causes structural damage.

[0004] In addition, in the experimental monitoring of the volume resistivity of conductive concrete, embedded electrodes also play an important role. The traditional preparation method also cannot solve the problem of deformation and displacement of embedded electrodes after pouring, which seriously affects the application and development of conductive concrete.

[0005] Therefore, there is a need for a conductive concrete volume resistivity pre-embedded electrode and a preparation method thereof, in which the pre-embedded electrode will not be displaced or deformed during pre-embedding. Summary of the invention

[0006] In view of the problems existing in the prior art, the present invention provides a pre-buried electrode for monitoring the volume resistivity of conductive concrete and a preparation method thereof.

[0007] The objective of the present invention is achieved through the following technical scheme: a pre-buried electrode for monitoring the volume resistivity of conductive concrete, comprising a pre-buried electrode sheet, characterized in that: it also includes a stabilizing panel, the four corners of the pre-buried electrode sheet are bent inward, a square hole is opened in the middle of the pre-buried electrode sheet, one side of the square hole extends outward to form an integrated access point, and the stabilizing panel is arranged in parallel with and connected to the pre-buried electrode sheet.

[0008] The present invention uses a copper embedded electrode sheet, with an opening in the middle, and retains one side to form an access point to ensure one-piece molding. The electrode sheet is designed using an one-piece molding process to ensure good contact of the electrode sheet. The one-piece embedded electrode sheet reduces the influence of the electrode sheet itself on the test resistivity. Then, by using a stable panel, the electrode sheet is prevented from displacement and deformation inside the concrete.

[0009] First, connect the stabilizing panel to the concrete formwork. The stabilizing panel ensures that the embedded electrode sheet remains in position during the concrete pouring process. At the same time, the stabilizing panel fixes the embedded electrode sheet inside the concrete. After the concrete solidifies, the stabilizing panel can be removed to expose the access point of the embedded electrode sheet for connecting to the circuit, forming a current access point, which is convenient for testing and using conductive concrete.

[0010] Preferably, the embedded electrode sheet is a copper sheet. Copper is a material with outstanding conductivity. Compared with other electrode sheets, copper has a small resistivity and a small resistance. The resistivity measured as the electrode of the test piece is more stable.

[0011] Preferably, the embedded electrode sheet has a thickness of 0.2 mm and a side length of 35 mm. The area of ​​the embedded electrode sheet also affects the resistivity of the material. To reduce the influence of the embedded electrode sheet on the test, a copper sheet with a thickness of 0.2 mm and a side length of 35 mm is selected.

[0012] Preferably, the stabilizing panel is a polystyrene board.

[0013] The polystyrene board stabilizes the position of the embedded electrode sheet, while protecting the current access point from being clean and easy to use; the copper electrode and the polystyrene board have low cost and good electrical conduction effect, and can effectively ensure the distance and relative position between the electrodes in the conductive concrete, while improving the safety of the access current, and do not generate pollution during use and installation, which is green and environmentally friendly.

[0014] Preferably, the stabilizing panel has a thickness of 5 mm and a side length of 40 mm.

[0015] Preferably, the stabilizing panel is provided with a notch, and slide grooves are provided on both sides of the notch, and the side walls of the access point cooperate with the slide grooves to form a plug-in connection between the access point and the stabilizing panel. The access point and the stabilizing panel form a plug-in connection, which facilitates the removal of the stabilizing panel after the concrete is solidified.

[0016] Preferably, the embedded electrode sheet is connected to the stable panel by silicone glue. Using silicone glue to connect between the embedded electrode sheet and the stable panel ensures convenient overall installation of the electrode and facilitates the removal of the stable panel after the concrete structure is completely cured.

[0017] Preferably, the side length of the square hole is 10 mm, and the length of the access point is 10 mm. When pouring concrete, 5 mm of the access point is buried in the concrete, and the other 5 mm is exposed outside the body. The total thickness of the embedded electrode is about 10 mm, which does not affect the concrete structure.

[0018] Preferably, the bending dimensions of the four corners of the embedded electrode sheet are 3 mm × 3 mm. The four corners of the embedded electrode sheet are bent inward to improve the connection with the matrix, and it is more firmly connected to the concrete during concrete pouring, ensuring a tight connection between the embedded electrode sheet and the concrete substrate, and having the characteristics of stable conduction and good durability.

[0019] A preparation method of an embedded electrode for monitoring the volume resistivity of conductive concrete, characterized by comprising the following steps:

[0020] Step 1: Prepare a copper embedded electrode sheet with a thickness of 0.2 mm and a side length of 35 mm;

[0021] Step 2: Prepare a polystyrene board with a thickness of 5 mm and a side length of 40 mm;

[0022] Step 3: Bend the four corners of the copper embedded electrode sheet inward, and the bending dimensions of the four corners are 3 mm × 3 mm;

[0023] Step 4: Open a square hole with a specification of 10 mm × 10 mm in the middle of the copper embedded electrode sheet. One side of the square hole is reserved and connected to the copper embedded electrode sheet, and it is bent in the opposite direction to form an access point;

[0024] Step 5: Insert the first 5 mm of the access point into the polystyrene board and connect it to the polystyrene board through silicone glue.

[0025] The present invention has the following beneficial effects: 1. The present invention uses a copper sheet as the material for making the embedded electrode, which has the characteristics of stable conduction and good durability. One side of the square hole extends outward integrally to form an access point, and the electrode sheet is designed using an integral molding process to ensure good contact of the electrode sheet. The influence of the factors of the integrally formed embedded electrode sheet itself on the measured resistivity eliminates the contact resistance and can measure a more accurate resistivity; the specially designed copper electrode is tightly connected to the concrete substrate, ensuring accurate and stable test results of the volume resistivity. During the concrete pouring process, the internal electrode is stable in position and does not deform. After the concrete structure hardens, the exposed access point is safe and reliable, reducing the risk of electric leakage during the test process and improving the safety of monitoring.

[0026] 2. The present invention uses copper sheets as the material for making the embedded electrodes. Copper is a material with outstanding conductivity. Compared with other electrode sheets, copper has a small resistivity and resistance. The resistivity measured as the electrode of the test piece is more stable.

[0027] 3. In the present invention, the stabilizing panel is made of polystyrene material, which is low in cost and easy to operate. The polystyrene board has strong processability, good durability, stable connection with the copper sheet electrode, and convenient demoulding in the later stage.

[0028] 4. In the present invention, silicone adhesive is used as a material for connecting the embedded electrode and the stable panel, which can protect the access point while connecting, ensuring that the electrode access point is waterproof, moisture-proof, corrosion-resistant, and durable.

[0029] 5. In the present invention, the total thickness of the embedded electrode is about 10 mm, which does not affect the concrete structure.

[0030] 6. The present invention is easy to install, and the electrode layout is flexible, and can be arranged at will according to specific use requirements. After pouring concrete, the electrode sheet is completely wrapped by concrete, leaving only the contact point outside, which is safe and reliable. It solves the problem of poor stability of traditional embedded electrodes, inability to ensure that their position in concrete does not change before and after pouring, and difficulty in electrode layout; at the same time, it solves the problem of lack of connection design between traditional electrodes and substrates. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 The present invention is a schematic structural diagram of a pre-buried electrode for monitoring the volume resistivity of conductive concrete.

[0032] Figure 2 It is a schematic diagram of the structure of the embedded electrode sheet in the present invention.

[0033] Figure 3 It is a side view of the silicone adhesive connection in the present invention.

[0034] Figure 4 It is a cross-sectional view of the plug connection in the present invention.

[0035] Figure 5 It is a schematic diagram of the access point after the embedded electrode sheet is installed.

[0036] Figure 6 It is a comparison chart of the test results of the embedded electrode sheet in the present invention and the traditional embedded electrode.

[0037] In the figure: 1 embedded electrode sheet, 2 stabilizing panel, 3 square hole, 4 access point, 5 silicone glue, 6 slide groove. DETAILED DESCRIPTION

[0038] The present invention will be further described below in conjunction with the accompanying drawings and the accompanying descriptions.

[0039] like Figure 1 , 2 As shown in Figures 3, 4 and 5, a pre-embedded electrode for monitoring the volume resistivity of conductive concrete comprises a pre-embedded electrode sheet 1 and a stabilizing panel 2, wherein the pre-embedded electrode sheet 1 is a copper sheet with a thickness of 0.2 mm and a side length of 35 mm; the stabilizing panel 2 is a polystyrene board with a thickness of 5 mm and a side length of 40 mm; the four corners of the pre-embedded electrode sheet 1 are bent inward, and the bending dimensions of the four corners of the pre-embedded electrode sheet 1 are 3 mm × 3 mm; a square hole 3 is provided in the middle of the pre-embedded electrode sheet 1, and the side length of the square hole 3 is 10 mm. An access point 4 is provided on one side of the square hole 3, and the access point 4 is integrally formed with the pre-embedded electrode sheet and is bent in the opposite direction of the bending of the four corners. The stabilizing panel 2 is arranged parallel to the pre-embedded electrode sheet 1, and the access point 4 is connected to the stabilizing panel 2.

[0040] Furthermore, the stabilizing panel 2 is provided with a notch, and slide grooves 6 are respectively provided on both sides of the notch, and the side walls of the access point 4 cooperate with the slide grooves 6 to form a plug-in connection between the access point 4 and the stabilizing panel 2 .

[0041] Furthermore, a silicone adhesive 5 is provided between the access point 4 and the stabilizing panel 2 , and the access point 4 and the stabilizing panel 2 are fixedly connected via the silicone adhesive 5 .

[0042] A method for preparing a pre-buried electrode for monitoring the volume resistivity of conductive concrete comprises the following steps:

[0043] Step 1: Prepare a copper embedded electrode sheet with a thickness of 0.2 mm and a side length of 35 mm;

[0044] Step 2: Prepare a polystyrene board with a thickness of 5 mm and a side length of 40 mm;

[0045] Step 3: Bend the four corners of the copper embedded electrode sheet inward, and the bending size of the four corners is 3mm×3mm;

[0046] Step 4: Open a square hole with a size of 10 mm × 10 mm in the middle of the copper pre-embedded electrode sheet, keep one side of the square hole connected to the copper pre-embedded electrode sheet, and bend it in the opposite direction to form an access point;

[0047] Step 5: Insert the first 5mm of the access point into the polystyrene board and connect it to the polystyrene board with silicone glue.

[0048] When in use, first make the embedded electrode sheet according to special requirements, connect the polystyrene board to the concrete formwork, use the polystyrene board to ensure that the copper embedded electrode sheet remains in position during the concrete pouring process, and fix the copper embedded electrode sheet inside the concrete through the polystyrene board. After the concrete solidifies, the polystyrene board can be removed to expose the access point of the embedded electrode sheet for connecting to the circuit, forming a current access point, which is convenient for testing and using conductive concrete.

[0049] The resistivity test method of conductive concrete can be done by the volt-ampere method, that is, using an ammeter to measure the current passing through an unknown resistor under this voltage, and then calculating the resistance value of the unknown resistor. Resistivity is a physical quantity used to represent the resistance characteristics of various materials. The ratio of the resistance of the test piece to the product of the cross-sectional area and the length is called the resistivity of the material.

[0050] In the conductivity test of conductive concrete, one of the indicators of the electrothermal performance test is the resistivity of the test block, and the electrode has a great influence on the resistivity of the test block. Copper is a material with outstanding conductivity. Compared with other electrode sheets, copper has a small resistivity and resistance. The resistivity measured by the electrode of the test piece is more stable. In the present invention, copper material is selected. The following studies the influence of different structures of pre-buried electrodes on the test results under the same laying method.

[0051] The specific test groups are shown in Table 1

[0052]

[0053] Table 1

[0054] 1. The impact of the modified embedded electrode sheet and the traditional embedded electrode sheet on the test stability

[0055] For each group of three specimens, the average value is taken according to the allowable error, and a line graph is compiled. By adopting the secondary method - laying the same electrode on the left and right sides, the current between the electrodes at both ends is tested, and the changes in current of the modified pre-buried electrode sheet and the traditional inserted pre-buried electrode are tested respectively as the test time increases, so as to observe the influence of the modified pre-buried electrode sheet and the traditional inserted pre-buried electrode on the resistivity test of conductive concrete.

[0056] like Figure 6As shown in the figure, for the conductive concrete specimen, during the 120-day test (input voltage is 50V AC), one is the test result of the modified composite structure embedded electrode sheet, and the other is the test result of using the traditional embedded electrode. The current of the modified embedded electrode sheet and the traditional inserted electrode both show an increasing trend with the increase of test time. As the test time increases, the test results of the specimen using the modified electrode are stable. When the traditional inserted embedded electrode is tested for about 500s, the current becomes unstable. A part of the test sample using the traditional inserted embedded electrode is damaged during the test, and the electrode is exposed. The electrode is easy to fall off during the test, resulting in unstable test current. This shows that the traditional inserted embedded electrode will affect the monitoring of the specimen resistivity.

[0057] During the test, as the test time increases, heat will be generated. The traditional pre-buried electrodes have more access points than those exposed outside the body after the modification. The heat generated will cause the electrode sheets to crack, thus affecting the monitoring of the resistivity of the test piece.

[0058] The access point of the modified pre-embedded electrode sheet is just the right size to fit the conductive electrode clip, and the access point should not be too long, otherwise it will cause the electrode sheet to break; the pre-embedded electrode sheet is integrally formed to reduce contact resistance, and the four corners are bent inward, which not only improves the close connection between the electrode sheet and the substrate, but also ensures that there will be no gap between the electrode sheet and the substrate as the test time increases during the test. Therefore, the test results of the modified pre-embedded electrode sheet are more stable than those of the traditional inserted pre-embedded electrode.

[0059] 2. The influence of the four corners of the pre-embedded electrode sheet on the test stability after modification under the same laying method

[0060] As shown in Table 2, under the same laying method, at 610s, the current of the traditional inserted pre-buried electrode became unstable and the current value was the lowest. After the modification, the current values ​​of the pre-buried electrode sheets with four corners and the pre-buried electrode sheets without four corners increased steadily with the increase of test time. However, at 610s and 1000s, the current value of the pre-buried electrode sheets with four corners was greater than that of the pre-buried electrode sheets without four corners.

[0061]

[0062] Table 2

[0063] The modified pre-buried electrode has less influence on the stability of the test specimen results. At the same time, the current of the modified pre-buried electrode sheet with four corners is larger than that of the pre-buried electrode sheet without four corners, because the four corners of the modified pre-buried electrode sheet are bent inward to increase the closeness with the substrate. As the test process progresses, no gap will be generated between the electrode sheet and the substrate, and the area of ​​the connected electrode sheet is small, and the corresponding resistance of the electrode itself is also small, which reduces the total resistance of the measurement circuit, thereby increasing the current of the circuit, and ultimately having little influence on the measured resistivity.

[0064] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modification, equivalent replacement, improvement, etc. made to the above embodiment based on the technical essence of the present invention should be included in the protection scope of the present invention.

Claims

1. A pre-buried electrode for monitoring the volume resistivity of conductive concrete, comprising a pre-buried electrode sheet (1), Features: It also includes a stabilizing panel (2), wherein the four corners of the embedded electrode sheet (1) are bent inwards, a square hole (3) is opened in the middle of the embedded electrode sheet (1), one side of the square hole (3) extends outwards to form an access point (4), the stabilizing panel (2) is arranged in parallel with and connected to the embedded electrode sheet (1), the stabilizing panel (2) is provided with a notch, and slide grooves (6) are respectively provided on both sides of the notch, and the side walls of the access point (4) cooperate with the slide grooves (6) to form a plug-in connection between the access point (4) and the stabilizing panel (2), and the stabilizing panel is connected to the concrete formwork, and the position of the embedded electrode sheet during the concrete pouring process is ensured to remain unchanged by the stabilizing panel, and the embedded electrode sheet is fixed inside the concrete by the stabilizing panel.

2. According to claim 1, a pre-buried electrode for monitoring the volume resistivity of conductive concrete, Features: The pre-buried electrode sheet (1) is a copper sheet.

3. The embedded electrode for monitoring the volume resistivity of conductive concrete according to claim 2, Features: The embedded electrode sheet (1) has a thickness of 0.2 mm and a side length of 35 mm.

4. The embedded electrode for monitoring the volume resistivity of conductive concrete according to claim 1, Features: The stabilizing panel (2) is a polystyrene board.

5. The embedded electrode for monitoring volume resistivity of conductive concrete according to claim 4, Features: The stabilizing panel (2) has a thickness of 5 mm and a side length of 40 mm.

6. The embedded electrode for monitoring volume resistivity of conductive concrete according to claim 1, Its characteristics are: The embedded electrode sheet (1) is connected to the stabilizing panel (2) via silicone glue (5).

7. The embedded electrode for monitoring volume resistivity of conductive concrete according to claim 1, Features: The side length of the square hole (3) is 10 mm, and the length of the access point (4) is 10 mm. When pouring concrete, 5 mm of the access point (4) is buried in the concrete, and the other 5 mm is exposed outside the body.

8. The embedded electrode for monitoring volume resistivity of conductive concrete according to claim 1, Features: The bending dimensions of the four corners of the embedded electrode sheet (1) are 3 mm×3 mm.

9. A method for preparing the embedded electrode for monitoring the volume resistivity of conductive concrete according to any one of claims 1 to 8, Features: The following steps are involved: Step 1: Prepare a copper embedded electrode sheet with a thickness of 0.2 mm and a side length of 35 mm; Step 2: Prepare a polystyrene board with a thickness of 5 mm and a side length of 40 mm; Step 3: Bend the four corners of the copper embedded electrode sheet inward, and the bending size of the four corners is 3mm×3mm; Step 4: Open a square hole with a size of 10 mm × 10 mm in the middle of the copper pre-embedded electrode sheet, keep one side of the square hole connected to the copper pre-embedded electrode sheet, and bend it in the opposite direction to form an access point; Step 5: Insert the first 5mm of the access point into the polystyrene board and connect it to the polystyrene board with silicone glue.

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