JPH0551097B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a portable detection end for measuring the corrosion status of steel materials in existing concrete structures, and particularly to a detection end that can perform non-destructive continuous measurement. (Prior Art) Reinforcing bars used in concrete structures corrode under various conditions and lose their functionality. Therefore, when measuring and inspecting the corrosion status of reinforcing bars and determining the lifespan of a concrete structure according to the situation, a part of the concrete structure is usually destroyed,
The method used was to expose the reinforcing bars and visually inspect them, but this is not the preferred method for structures. Therefore, non-destructive measuring means have been proposed, as seen in Japanese Patent Application Laid-Open No. 59-217147.
In this method, a steel material (reinforcing bar) in concrete is used as a test electrode, and a test electrode terminal is connected to the exposed part, while a portable electrode part equipped with a reference electrode and a counter electrode is sequentially placed on the concrete surface along the steel material. The self-potential, polarization resistance, and liquid resistance are measured at various points on the concrete surface using the reference electrode, test electrode, and counter electrode. From these three electrochemical characteristic values, the corrosion status of the steel material can be determined. This is a means of investigating corrosion of steel in concrete to estimate corrosion. The device used for this purpose is to close the bottom of a bottomless container equipped with a liquid supply and air vent with a lower lid made of porous material, fill the container with an electrolyte aqueous solution, and immerse the reference electrode and counter electrode in this electrolyte aqueous solution. Then, using a portable electrode part formed so as to be able to adhere to the concrete surface and the steel material in the concrete as a test electrode, connect the test electrode terminal to this exposed part, and use the reference electrode and counter electrode to measure the natural potential,
A device comprising a three-electrode monitor that outputs measured values of polarization resistance and liquid resistance is disclosed. (Problems to be Solved by the Invention) The above-mentioned Japanese Patent Application Laid-Open No. 59-217147 is an excellent method in that it can non-destructively measure the corrosion status of reinforcing bars in concrete, but the specific device is as follows. There are some technical issues. That is, the measurement of reinforcing steel corrosion in normal concrete structures is not limited to the top surface, but often has to be carried out from the side surface or the bottom surface (bottom surface). When measuring from the top or bottom surface, the leakage of the aqueous electrolyte solution (hereinafter simply referred to as electrolyte) to the concrete surface tends to become unstable, so there is a risk that the measurement will be uncertain. This becomes a major technical problem, especially in field work where there are many places where footing is usually poor and measurements are difficult. In other words, the detection end of the invention causes unnecessary air to be mixed inside depending on the posture of use, and as a result,
This has the problem that it becomes impossible to maintain good electrical continuity between the detection end and the reinforcing bar. (Means for Solving the Problems) The present invention is intended to develop a detection end that is capable of reliable measurement in any measurement posture and has high accuracy. , a portable detection end that has an electrolyte-filled part inside and a reference electrode and a counter electrode protruding into the filled part and immersed in the electrolyte is brought into contact with the electrolyte leaking onto the concrete surface to be measured. characteristic values (e.g. natural potential, polarization resistance, liquid resistance, etc.)
A portable reinforcing steel corrosion detection end used in a device for measuring corrosion of reinforcing steel, and an exhaust pipe equipped with a liquid/air supply pipe and an on-off valve connected to a device capable of supplying liquid or air. A support plate on which a reference electrode and a counter electrode are attached, an inner cylinder insertion hole at the center of the shaft, a flange on the outer edge, a bottom plate having a communication hole with the inner cylinder, and a mounting part for the support plate on the top, An outer cylinder whose inside is an electrolyte filling part, and an inner cylinder having a liquid passage valve port with the communication hole and extending into the body of the outer cylinder to draw out the electrolyte are fixed to the center of the shaft. a rotary cap rotatably mounted on the flange of the outer cylinder when the inner cylinder is inserted through the inner cylinder insertion hole; and a rotary cap that is rotatably attached to the flange of the outer cylinder; It is characterized by comprising a liquid-permeable packing material disposed on the lower surface of the support plate and a liquid-permeable contact material sealing the surface of the rotary cap on the measurement target side, and a counter electrode surrounding the reference electrode as the center. It is arranged like this. Hereinafter, the structure of the present invention will be explained in detail together with its operation. FIG. 1 is a schematic longitudinal cross-sectional view of a detection end 1 according to the present invention, in which a disk-shaped support plate 2 is connected to a protective cap 3.
It has protrusions 2a and 2b that are inserted into the outer cylinder 4, and is made of an electrically insulating material, and is equipped with a reference electrode 5, a counter electrode 6, a liquid/air supply pipe 7, and an exhaust pipe 8. . The lead wire 5a of the reference electrode 5 extends upward and is connected to a take-out portion, in this example, a connector 9. Similarly, the lead wire 6a of the counter electrode 6 is connected to the connector 9, and the lead wires 5a, 6a is the 3-electrode corrosion monitor 1 via the connector 9 and the cord 10.
Connected to 1. In addition, the top of the liquid/air supply pipe 7 (hereinafter simply referred to as the dual-purpose pipe) and the attachment part of the protective cap 3, which in this example is the connecting pipe 12, are connected by a flexible tube 13. Furthermore, the connecting pipe 12
and the liquid/air supply device 14 are connected by a hose 15. In addition, the liquid and air supply equipment includes an air/liquid switching valve,
Gas/liquid pumps, on-off valves, pressure regulating valves, etc. are provided, but their explanations are omitted. The top of the exhaust pipe 8 and the attachment part of the protective cap 3, in this example the connection pipe 16, are connected by a flexible tube 17, and the connection pipe 16 and the exhaust valve 18 are connected by a hose 19. There is. Next, the flange 3a of the protective cap 3 is configured to be in close contact with the upper surface of the flange 2c of the disk-shaped support plate 2, and similarly, the flange 4a of the outer cylinder 4 is
It is configured to be in close contact with the lower surface of the flange 2c. Furthermore, since a plurality of holes 20 are provided that pass through the flanges 3a, 2c, and 4a, the tightening bolts 21 are passed through the through holes 20, and then the nuts 22 are inserted.
When tightened, the protective cap 3, disc-shaped support plate 2, and outer cylinder 4 can be tightly connected, and if necessary, a packing material can be interposed as appropriate to improve airtightness. is also possible. Next, a flange 4c is attached to the bottom plate 4b of the outer cylinder 4.
is provided around the periphery, and an inner cylinder insertion hole 24 into which the inner cylinder 23 is inserted is provided at the center of the shaft. Further, the bottom plate 4b is provided with a hole 25 that communicates between the electrolyte filling lumen 4d provided in the body of the outer cylinder 4 and the inner cylinder insertion hole 24. Further, an inner cylinder 23 made of a straight pipe with both ends open is fixed to the rotary cap 27, which is rotatably mounted with the flange 4c fitted into the annular groove 26. The rotary cap 27 is a split-assembly type annular metal fitting 27a.
It is composed of the mounting bolt 28 of this annular hardware 27a and the inner cylinder support part 27b, and the bottom plate 4 of the outer cylinder 4.
After pressing the inner cylinder support portion 27b with the packing material 29 interposed in the inner cylinder support portion 27b, the inner cylinder support portion 27b is rotatably assembled to the bottom plate 4b using the annular hardware 27a and the mounting bolts 28. Further, the outer surface of the rotary cap 27 is sealed with a liquid-permeable contact plate 30, so that the inner cylinder 23
A predetermined amount of the electrolytic solution inside passes through within a predetermined time. Therefore, the liquid-permeable contact plate 30 is made of organic or inorganic fibers or a liquid-permeable porous material. The lower part of the inner cylinder 23 is connected to the rotary cap 27.
The upper part extends above the inner cavity 4d of the outer cylinder 4, and the upper edge 23a and the lower surface of the disc-shaped support plate 2, in this example, the lower surface _2b1 of the insertion protrusion 2b. A liquid-permeable packing material 31 is held in between. Further, a liquid passage valve port 32 is provided below the inner cylinder 23 and penetrates through the cylinder wall, and the rotation of the inner cylinder 23 in conjunction with the rotation of the rotary cap 27 allows the liquid to pass through the communication hole 23.
5 and the liquid passage valve port 32 are in a state where liquid can be passed or not. Furthermore, a tip 6b of a counter electrode 6 is formed in a spiral shape and is opposed to the tip 5b of the reference electrode 5 extending below the inner cavity 23b of the inner tube 23 at a set distance. Such a configuration of the counter electrode 6 can make the current distribution uniform and also make the shape of the counter electrode 6 compact, so that the volume of the detection end can be made smaller and transportation and measurement can be made convenient. Next, a test electrode terminal 35 is attached to the exposed part 34a of the reinforcing bar 34 buried in the concrete 33, and a lead wire 36 is connected to the three-electrode monitor. 1 is a partially cutaway schematic perspective view of the detection end 1 according to FIG. 1, and parts having the same symbols as those in FIG. The details of the rotary cap 27 will be explained in FIG. As mentioned above, the rotary cap 27 is connected to the annular metal fitting 2.
7a, an inner cylinder support part 27b, and a mounting bolt 28 that connects them. As described above, it is assembled after being pressed against the bottom plate 4b, and as a result, the annular groove 26 is formed, and the rotary cap 27 is rotatably mounted on the flange 4c. Now, the detection end of the present invention has the above-mentioned configuration, and its operation and functions are shown in FIGS.
The operation procedure will be explained with reference to FIG. 5, which is an explanatory diagram of the operation procedure. FIG. 3 is a diagram showing a state in which the detection end 1 is pressed against a concrete floor surface and the state of corrosion of the reinforcing bars 34 is being measured. First, prior to measurement, the rotary cap 27 is rotated in advance together with the inner cylinder 23, so that the liquid passage valve port 32 and the communication hole 25 are communicated with each other so that liquid can pass therethrough. After that, after opening the exhaust valve 18,
From the liquid/air supply device 14 via the hose 15,
The electrolytic solution is fed into the outer cylinder 4 through the dual-purpose pipe 7. The electrolytic solution 50 passes from the dual-purpose pipe 7 through the communication hole 25 and the liquid passage valve port 32, and is filled into the inner cylinder 23, and simultaneously filled into the outer cylinder 4. When the exhaust valve 18 is closed when the appropriate amount is filled, an amount mainly determined by the liquid permeability of the liquid permeable contact plate 30 leaks from the liquid permeable contact plate 30 to the surface 33a of the concrete 33. . Therefore, as mentioned above, the three-electrode monitor 1 is electrically connected to the reference electrode 5, the counter electrode 6, and the test electrode 35.
1, electrochemical characteristic values (eg, spontaneous potential polarization resistance, liquid resistance, etc.) can be appropriately measured. For convenience in supplying the electrolytic solution, if the outer cylinder 4, inner cylinder 23, etc. are made of transparent corrosion-resistant material, the measurement work can be performed more quickly. The counter electrode 6 in the embodiment of the present invention has a helical tip as described above, and the shape can be made extremely small, so it can be provided sufficiently close to the reference electrode 5. This configuration is effective in making the overall configuration of the detection end 1 compact, and can also improve measurement accuracy. Next, FIG. 4 is an explanatory diagram of the measurement situation on the vertical concrete wall surface 33b. In this case, prior to supplying the electrolytic solution, the inner cylinder 23 is rotated to cut off communication between the liquid flow valve port 32 and the communication port 25. Leave it as the state.
As described above, the liquid passage system is opened and closed by the rotation of the inner cylinder 23, so although it is in the form of a through hole, it is referred to as a liquid passage valve port in the present invention. Now, when the exhaust valve 18 is opened and the electrolytic solution is supplied into the inner cavity 4d and closed at an appropriate time, the electrolytic solution 50 fills the space between the inner cylinder 23 and the inner wall 4e of the outer cylinder 4. Thereafter, the liquid passes through the liquid-permeable packing material 31 to fill the inner cavity 23b of the inner cylinder 23, and then leaks from the liquid-permeable contact plate 30 to the wall surface 33b. Therefore, if the electrolytic solution is continuously supplied from the liquid/air supply device 14, the electrolytic solution will be smoothly distributed to the wall surface 33b in the required amount.
The measurement will continue accurately. The liquid-permeable packing material 31 is suitably made of organic or inorganic cloth or fiber. With this configuration, the electrolytic solution in the inner cylinder 23 maintains an appropriate internal pressure, so that the wall surface 3
There is no fear that leakage of the electrolytic solution to 3b will be interrupted, making it possible to perform measurements accurately. That is, the liquid-permeable packing material 31 has a function of allowing the electrolyte to pass through under a moderate pressure loss, and even when the outer cylinder 4 is placed sideways, that is, in a horizontal position, the electrolyte is not removed from the inner cylinder 23 inside the outer cylinder 4. It is possible to prevent the liquid from rapidly flowing away in the opposite direction. Next, FIG. 5 is a schematic diagram illustrating a situation in which the detection end 1 is pressed from below against a concrete lower surface 33c of a building ceiling or a bridge to perform measurement. In this example as well, first, prior to supplying the electrolytic solution, the inner cylinder 23 is rotated to cut off communication between the liquid passage valve port 32 and the communication port 25, and then the exhaust opening/closing valve 18 is opened to supply the electrolytic solution. The electrolytic solution is supplied from the liquid/air supply device 14 to the inner cavity 4d, and the inner cavity 4d filled with the electrolytic solution is pressed against the inner cavity 4d, and the exhaust opening/closing valve 18 is closed. In this case, the electrolyte will fall due to gravity, so unless some pressure is applied,
The electrolytic solution does not leak to the outside from the liquid-permeable plate 30. Therefore, using the liquid/air supply device 14, the electrolytic solution 50 is fed from the dual-purpose pipe 7 to the inner cavity 4d. Then, the electrolyte passes through the liquid-permeable packing material 31,
The inner cylinder 23 is filled with the liquid, and the liquid leaks from the liquid-permeable contact plate 30 to the lower surface 33c, and the leakage continues. In this way, the detection end 1 of the present invention can be used in any measurement posture, has sufficient measurement functions, and maintains the best electrical continuity at all times due to the continuous supply of electrolyte. Therefore, highly reliable measurement results can be obtained. In the above example, the method of supplying the electrolyte using the liquid/air supply device 14 has been explained, but as another method, when the outer cylinder 4 is sufficiently filled with electrolyte, It is also effective to supply compressed air using the liquid/air supply device 14. In this case, as long as the electrolyte 50 exists in the outer cylinder 4, the electrolyte passes through the electrolyte-permeable packing material 31, fills the inner cylinder 23, and leaks from the liquid-permeable contact plate 30 to the lower surface 33c. However, leakage will continue. In this case as well, since the best electrical conduction state can be maintained at all times, highly reliable measurement results can be obtained. (Example) A silver/silver chloride electrode was used as the reference electrode 5, a platinum wire was used as the counter electrode 6, and a detection end with a Na ₂ SO ₄ saturated solution as the electrolyte was used. The results of measuring the slab) will be explained below. A plastic sponge was used as the liquid-permeable contact plate 30, synthetic gauze was used as the liquid-permeable packing material 31, and data were obtained using a three-electrode monitor. The reinforcing bars in the concrete slab to be measured are nominally
4.1mm diameter welded wire mesh with 150mm spacing between reinforcing bars.
The average fog was 20.1 mm, the water/cement ratio of the concrete slab was 51.2%, the average salt content was 0.081% (NaCl equivalent), and the neutralization depth at the time of measurement was 19.7 mm. It was presumed to be in the early stages of corrosion. Next, the correlation between the corrosion rate (mm/year) based on the diameter measurement of the sampled reinforcing bars, the self-potential (mV), the reciprocal of the polarization resistance (Kohm), and the liquid resistance (Kohm) is shown in Figure 6. This will be explained with reference to the graphs in FIGS. 7 and 8. As shown in Figure 6, the natural potential is -200mV
It was found that the lower the resistance, the higher the corrosion tendency, and the reciprocal value of polarization resistance has a very clear correlation with the corrosion rate, and furthermore, the smaller the liquid resistance, the lower the corrosion performance of concrete. I understand that. In other words, in the past, a qualitative understanding of the corrosion situation was carried out by comparing the order of natural potential, polarization resistance, and liquid resistance, but with the detection end of the present invention,
It becomes possible to quantitatively understand the corrosion situation. (Effects of the Invention) As described above, the detection end of the present invention can be used continuously in any posture, so it is possible to quickly and reliably perform measurements on an actual structure, and it has a high practical effect.

[Detailed description of the invention]

FIG. 1 is a schematic vertical sectional view of the detection end of the present invention, FIG. 2 is a partially cutaway schematic perspective view, FIG. 3, and FIG.
Figure 5 is an explanatory diagram of the operating procedure of the detection end of the present invention, Figure 6 is the corrosion rate and self-potential, Figure 7 is the corrosion rate and the reciprocal of polarization resistance, and Figure 8 is the correlation between the corrosion rate and liquid resistance. These are graphs shown respectively. 1: Detection end, 2: Disk-shaped support plate, 2a: Insertion protrusion, 2b: Insertion protrusion, 2b ₁ : Bottom surface, 2
c: flange, 3: protective cap, 3a: flange, 4: outer cylinder, 4a: flange, 4b: bottom plate, 4
c: flange, 4d: lumen, 4e: inner wall, 5: reference electrode, 5a: lead wire, 5b: tip, 6: counter electrode, 6a: lead wire, 6b: tip, 7: liquid supply/air supply pipe, 8: Exhaust pipe, 9: Connector, 10:
Cord, 11:3 electrode corrosion monitor, 12:connecting tube, 13:flexible tube, 14:liquid supply/
Air supply device, 15: Hose, 16: Connection pipe, 17:
Flexible tube, 18: Exhaust on/off valve, 1
9: Hose, 20: Through hole, 21: Tightening bolt, 22: Nut, 23: Inner cylinder, 23a: Upper edge,
23b: Inner cavity, 24: Inner cylinder insertion hole insertion hole, 25:
Communication hole, 26: Annular groove, 27: Rotating cap, 2
7a: Annular hardware, 27b: Inner cylinder support part, 28: Mounting bolt, 29: Packing material, 30: Liquid permeable contact plate, 31: Liquid permeable packing material, 32: Liquid passage valve port, 33: Concrete, 33a :Surface, 33
b: wall surface, 33c: bottom surface, 34: reinforcing bar, 34a:
Exposed part, 35: Test electrode terminal, 36: Lead wire, 3
7: Installation screw, 50: Electrolyte.

Claims (1)

[Scope of Claims] 1 Conductivity is established through the exposed part of the reinforcing bars in concrete, and a portable detection end is provided which has an electrolyte-filled part inside, a reference electrode protruding from the filled part and immersed in the electrolyte, and a counter electrode. , a portable reinforcing steel corrosion detection end of a device that measures the corrosion state of reinforcing bars in concrete by making electrochemical measurements in contact with the concrete surface to be measured, and is a device that can supply liquid or air. A combined liquid and air supply pipe is connected, an exhaust pipe equipped with an on-off valve, and a support plate equipped with a reference electrode and a counter electrode. an outer cylinder having a bottom plate having a communication hole with the cylinder, and an attachment part for the support plate on the top, and an electrolyte filling part in the body; having a liquid passage valve port with the communication hole; An inner cylinder that extends into the outer cylinder body and draws out the electrolyte is fixed to the center of the shaft, and when the inner cylinder is inserted through the inner cylinder insertion hole, it is rotatably attached to the flange of the outer cylinder. a rotary cap that is attached to the rotary cap; a liquid-permeable packing material disposed on the upper edge of the inner cylinder and the lower surface of the support plate when the rotary cap is attached; a surface of the rotary cap on the measurement target side that is sealed; A portable reinforcing steel corrosion detection end characterized by being made of a liquid-permeable contact material. 2. The portable reinforcing steel corrosion detection end according to claim 1, wherein the counter electrode is arranged so as to surround the reference electrode.