JP2018004348A - Steel material potential measuring method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce cost for measurement of spontaneous potentials of a plurality of steel materials located at different heights in a concrete structure.SOLUTION: For measurement of electric potentials of a plurality of steel materials provided at different heights in a concrete structure 1, a reference electrode bundle 10 bundling a plurality of reference electrodes 10A, 10B which respectively have wire-shaped line electrodes 11A, 11B and insulation coatings 12A, 12B to coat the line electrodes 11A, 11B is prepared. The line electrodes 11A, 11B are exposed by removing the respective insulation coatings 12A, 12B of the tip parts of the reference electrodes 10A, 10B and the height of each of the tip parts is caused to match the height of a different steel material so as to be buried in the concrete structure 1. Then, each potential difference between each of the reference electrodes 10A, 10B and a standard electrode is measured.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a steel material potential measuring method for nondestructively measuring the corrosion state of a steel material in a concrete structure.

  For example, corrosion of steel in concrete structures such as reinforced concrete has become a social problem. Causes of corrosion of steel materials include, for example, incoming salt near the coast and spraying of antifreezing agents in cold regions. When the steel material in the concrete structure is corroded, the corrosion condition of the steel material is revealed only when the cover concrete cracks due to the expansion pressure of the steel material in the corroded part or the rust juice leaks out. However, repair and renovation work of concrete structures at the stage where the corrosion state of steel materials is exposed requires a large cost. Therefore, a technique for nondestructively measuring a steel material corrosion state at a stage where the steel material corrosion is not exposed is attracting attention.

  One of the methods for nondestructively measuring the corrosion state of steel in concrete structures is a self-potential measurement method. The self-potential measurement method is a method of measuring the potential of the steel surface that changes due to corrosion of the steel material in the concrete structure. Generally, the potential of the steel material is in a base direction (− Side). In the natural potential measurement method, an electrode body called a reference electrode and a potentiometer are used, and the positive terminal of the potentiometer is connected to steel, the lead wire of the reference electrode is connected to the negative terminal, and this reference electrode is connected to the concrete surface. The measurement is performed by abutting on or embedded in a concrete frame. A type of verification electrode that is in contact with the concrete surface is called a portable verification electrode, and a type of verification electrode that is embedded in a concrete frame is called an embedded verification electrode (for example, Patent Document 1).

  The natural potential measurement method is used not only for the purpose of measuring the corrosion state of the steel material of an existing concrete structure, but also for confirming the effect of the cathodic protection method (for example, Patent Document 2).

  A technique is also known in which measurement is performed by embedding a thin noble metal-coated titanium wire in a concrete structure as a reference electrode (for example, Patent Document 3).

JP-A 61-124863 JP2013-224456A JP 2001-013100 A

  Corrosion of steel materials in concrete structures is particularly concerned with salt damage near the coast and salt damage caused by spraying anti-freezing agents such as sodium chloride and calcium chloride in cold regions. Particularly, salt damage near the coast appears as corrosion from the lower steel of the concrete structure, and salt damage caused by spraying the antifreeze on the road surface gradually proceeds from the upper steel.

  In the measurement method using the portable verification electrode, since the measurement is performed by bringing the verification electrode into contact with the concrete surface, there is a restriction that only steel materials near the concrete surface can be subjected to corrosion measurement. For this reason, in the case of a concrete structure where the upper surface concrete surface is covered by road work, etc., in order to measure the corrosion of the steel material on the upper side (road surface side) of the concrete structure using a portable verification electrode, In practice, it is difficult to expose the concrete surface by road surface cutting and to perform road surface restoration work after measurement.

  On the other hand, in the measurement method using the embedded collating electrode, it is possible to embed the collating electrode in accordance with the position of the reinforcing bar to be measured in the concrete structure. It can also be used to measure the corrosion of steel on the upper side (road surface side) of concrete structures.

  However, when multiple steel materials at different height positions such as the upper and lower parts of a concrete structure are to be measured, it is necessary to embed each reference electrode according to the height position of each steel material. It takes time to cut a hole for embedding. Furthermore, there is a concern that the strength may decrease due to an increase in the number of perforations provided in the concrete structure.

  An object of the present invention is to provide a steel material potential measuring method capable of reducing the cost when measuring the natural potential of a plurality of steel materials located at different heights in a concrete structure.

  In order to solve the above problems, a steel material potential measuring method according to one aspect of the present invention is a wire-like line electrode for measuring the potentials of a plurality of steel materials arranged at different heights in a concrete structure. And a collation electrode bundle in which a plurality of collation electrodes each having an insulation coating covering the line electrode are bundled, the insulation coating at the tip portion of each collation electrode is removed to expose the line electrode, and each The height of the tip portion is embedded in the concrete structure in accordance with the height of the different steel materials, and the potential difference between each of the reference electrode and the reference electrode is measured.

  According to the present invention, a collation electrode bundle in which a plurality of collation electrodes are bundled, the line electrode is exposed by removing the insulation coating from the tip portion of each collation electrode, and each tip portion is provided with a height of a separate steel material. By embedding in the concrete structure according to the above, it is possible to efficiently embed a plurality of reference electrodes.

  Further, in the steel material potential measuring method according to one aspect of the present invention, when the perforation for embedding the reference electrode bundle is provided in the concrete structure, the number of the perforations can be minimized, so that the perforation cutting is performed. The cost can be greatly reduced, and the strength reduction of the concrete structure can be suppressed.

  As described above, according to the present invention, it is possible to reduce the cost when measuring the natural potential of a plurality of steel materials located at different heights in a concrete structure.

It is the schematic sectional drawing which looked at the concrete structure from the side direction, in order to explain the reinforcing bar corrosion measuring method which is one embodiment concerning the present invention. It is AA 'sectional drawing of the concrete structure of FIG. It is a figure which shows the example of the collation electrode bundle used in the reinforcing bar corrosion measuring method of this embodiment. It is a schematic sectional drawing which shows the embedding method of the collation electrode bundle | flux in a concrete structure in the reinforcing bar corrosion measuring method of this embodiment. It is a schematic sectional drawing which similarly shows the embedding method of the collation electrode bundle | flux in a concrete structure in the reinforcing bar corrosion measuring method of this embodiment. It is a schematic sectional drawing for demonstrating the connection method of the potentiometer 20 in the case of measuring the corrosion of the upper rebar 3.

Hereinafter, embodiments according to the present invention will be described with reference to the drawings.
FIG. 1 is a schematic cross-sectional view of a concrete structure 1 viewed from the side in order to explain one embodiment of a steel bar corrosion measurement method employing the steel material potential measurement method of the present invention, and FIG. 2 is a concrete structure 1 of FIG. It is AA 'sectional drawing.

[Outline of Rebar Corrosion Measurement Method of this Embodiment]
First, the outline of the reinforcing bar corrosion measuring method of this embodiment will be described. This reinforcing bar corrosion measuring method is a self-potential measurement of the corrosion state of a plurality of reinforcing bars 2 and 3 arranged at different heights in a concrete structure 1. In the measurement by the method, the reference electrode bundle 10 in which a plurality of reference electrodes 10A and 10B having wire-like line electrodes 11A and 11B and insulating coatings 12A and 12B covering the line electrodes 11A and 11B are bundled is used as each reference electrode. The insulating coatings 12A and 12B of the tip portions 13A and 13B of 10A and 10B are removed to expose the line electrodes 11A and 11B, and the heights of the tip portions 13A and 13B are adjusted to the heights of the separate reinforcing bars 2 and 3, respectively. And embedded in the concrete structure 1 to measure the potential difference between each reference electrode 10A, 10B and the reference electrode.

  Note that the potential of the reference electrode is the potential of any of the reinforcing bars in the concrete structure 1. In FIG. 1 and FIG. 2, for example, the potential of the lower reinforcing bar 2 is used as the potential of the reference electrode. Alternatively, the potential of another reinforcing bar in the concrete structure 1 such as the reinforcing bar 3 may be used as the potential of the reference electrode.

Hereinafter, the above-mentioned method for measuring corrosion of reinforcing bars will be described in more detail.
[Configuration of Verification Electrode Bundle 10]
FIG. 3 is a side view showing the configuration of the verification electrode bundle 10 used in the reinforcing bar corrosion measurement method of the present embodiment.

  As shown in the figure, the collating electrode bundle 10 used in the reinforcing bar corrosion measuring method of the present embodiment has two thin collating electrodes 10A, 10B bundled together by, for example, one or more binding bands 21. Configured. The two verification electrodes 10A and 10B may be bundled together with an adhesive, or may be twisted together and bundled together.

  The configuration of each verification electrode 10A, 10B in the verification electrode bundle 10 is basically the same. One verification electrode 10A includes a wire-shaped line electrode 11A, an insulating coating 12A covering the line electrode 11A, a lead wire 14A, and a connecting portion 15A. Similarly, the other verification electrode 10B includes a wire-shaped line electrode 11B, an insulating coating 12B that covers the line electrode 11B, a lead wire 14B, and a connection portion 15B. The connecting portions 15A and 15B are portions that electrically connect the end portions of the line electrodes 11A and 11B and the lead wires 14A and 14B. The main difference between the respective verification electrodes 10A and 10B is the length thereof. In other words, only the positions of the tip portions 13A and 13B where the insulating coatings 12A and 12B are removed and the line electrodes 11A and 11B are exposed are provided. is there.

  The line electrodes 11A and 11B are composed of a wire made of titanium (Ti) and a noble metal coating made of iridium (Ir), ruthenium (Ru), hafnium (Hf) or rhodium (Rh) covering the titanium wire. Is done. Titanium is a stable and strong metal with a high potential relative to iron, has high durability, is easy to draw, and is suitable as a thin wire-like reference electrode material. However, since titanium is easily oxidized, in order to prevent this, it is desirable to coat with the above-mentioned noble metal resistant to both acid and alkali. The diameters of the line electrodes 11A and 11B are about 1.0 to 3.0 mm.

[Method of Embedding Verification Electrode Bundle 10]
4 and 5 are schematic cross-sectional views showing a method for embedding the reference electrode bundle 10 in the concrete structure 1. FIG.
For example, as shown in FIG. 4, the reference electrode bundle 10 is embedded in the concrete structure 1 by providing a perforation 6 by cutting or the like from the lower surface 1 </ b> A of the concrete structure 1, and as shown in FIG. 5, The reference electrode bundle 10 is inserted into the hole 6 and the gap in the perforation 6 is filled with a repair material 7 such as mortar. The perforations 6 are formed from the lower surface 1 </ b> A of the concrete structure 1 along a vertical direction or a substantially vertical direction orthogonal to the direction of the reinforcing bars 2 and 3 as a measurement target. As shown in FIG. 2, the perforation 6 is formed so as to pass through a position close to the reinforcing bars 2 and 3 to be measured with a predetermined concrete thickness interposed therebetween.

  Alternatively, the reference electrode bundle 10 may be embedded when the concrete structure 1 is placed in the concrete. Alternatively, a punching die for forming the perforations 6 may be embedded at the time of concrete placement, and the perforations 6 may be obtained by removing the punching die together with the mold at the time of disassembling the mold.

  As shown in FIGS. 1, 2, and 5, in the verification electrode bundle 10 embedded in the concrete structure 1, one verification electrode 10 </ b> A has the lower rebar 2 in the concrete structure 1 as a corrosion measurement target. In order to do this, the tip portion 13A of the line electrode 11A exposed by removing the insulating coating 12A is arranged in accordance with the height of the lower reinforcing bar 2. Similarly, the other line electrode 11B has the tip portion 13B of the line electrode 11B exposed after the insulation coating 12B is removed so that the upper rebar 3 in the concrete structure 1 is subject to corrosion measurement. Arranged according to the height. More specifically, for example, the height of the center of the tip portion 13A of the line electrode 11A matches the height of the lower rebar 2 and the height of the center of the tip portion 13B of the line electrode 11B is the height of the upper rebar 3. It is desirable to match the height.

  Further, each of the verification electrodes 10A and 10B is entirely covered with the line electrodes 11A and 11B by the insulating coatings 12A and 12B except for the tip portions 13A and 13B. Electrically isolated.

  Further, as shown in FIGS. 1, 2, and 5, the verification electrode bundle 10 is made of concrete in a state where the lead wires 14 </ b> A and 14 </ b> B of the respective verification electrodes 10 </ b> A and 10 </ b> B are drawn from the lower surface 1 </ b> A of the concrete structure 1. Embedded in the structure 1. Each lead wire 14A, 14B is preferably one whose surface is covered with an insulating film in the same manner as the line electrodes 11A, 11B in order to avoid mutual conduction during measurement.

[Measurement using potentiometer 20]
Next, a method for measuring corrosion of the reinforcing bars 2 and 3 in the concrete structure 1 using the potentiometer 20 will be described.

  When performing corrosion measurement of the reinforcing bar 2, as shown in FIG. 1, for example, the reinforcing bar 2 serving as a reference electrode is electrically connected to the + terminal of the potentiometer 20, and is pulled out from the lower surface of the concrete structure 1. Connect the lead wire 14 </ b> A to the negative terminal of the potentiometer 20. Thereby, the potential difference between the verification electrode 10A and the reference electrode is measured as the natural potential of the measurement target portion of the lower reinforcing bar 2.

  When the corrosion of the reinforcing bar 3 is measured, as shown in FIG. 6, for example, the reinforcing bar 2 serving as a reference electrode is electrically connected to the + terminal of the potentiometer 20 and is pulled out from the lower surface of the concrete structure 1. Lead wire 14 </ b> B is connected to the minus terminal of potentiometer 20. Thereby, the potential difference between the verification electrode 10B and the reference electrode is measured as the natural potential of the measurement target portion of the upper rebar 3.

  As described above, according to the reinforcing bar corrosion measurement method of the present embodiment, the verification electrode bundle 10 composed of a plurality of verification electrodes 10A and 10B is connected to the insulating coating 12A of the tip portions 13A and 13B of the verification electrodes 10A and 10B. , 12B are exposed to expose the line electrodes 11A, 11B, and the height of each of the tip portions 13A, 13B is embedded in the concrete structure 1 in accordance with the height of the separate reinforcing bars 2, 3, thereby providing a concrete structure. Compared to a typical method of separately embedding the verification electrodes having different lengths in the reinforcing bars 2 and 3 having different heights in the object 1, the operation of embedding the verification electrodes can be performed efficiently.

  Moreover, according to the reinforcing bar corrosion measurement method of the present embodiment, the number of perforations 6 for embedding the verification electrodes 10A and 10B can be minimized. In particular, since the number of perforations 6 required when measuring the corrosion state of the rebars 2 and 3 of the concrete structure 1 can be greatly reduced, the cutting cost of the perforations 6 can be greatly reduced. At the same time, a decrease in strength of the concrete structure 1 can be suppressed.

  Moreover, the reinforcing bar corrosion measuring method of this embodiment can be employed for the corrosion measurement of reinforcing bars in existing concrete structures as well as reinforcing bars in newly installed concrete structures.

  Note that the number of verification electrodes constituting the verification electrode bundle 10 is determined according to the number of reinforcing bars having different heights, which are measurement targets in the concrete structure 1. In the example of FIG. 1, since the upper rebar 2 and the lower rebar 3 are the measurement objects, the two verification electrodes 10 </ b> A and 10 </ b> B are used, but the upper rebar 2 and the lower rebar are used. When a reinforcing bar (not shown) with a height between 3 is also a measurement object, the number of verification electrodes is 3 or more. As described above, the reinforcing bar corrosion measuring method of the present embodiment copes with an increase in the number of reinforcing bars having different heights to be measured in the concrete structure 1 without changing the number of perforations 6 to be provided. Is possible.

  As mentioned above, the method for measuring the rebar corrosion of a newly installed or existing concrete structure has been described. The steel potential measuring apparatus of the present invention is also used as a means for measuring the potential of a steel material and confirming the effect in the cathodic protection method. Is possible.

DESCRIPTION OF SYMBOLS 1 ... Concrete structure 2, 3 ... Rebar 6 ... Perforation 7 ... Repair material 10 ... Collation electrode bundle 10A, 10B ... Collation electrode 11A, 11B ... Line electrode 12A, 12B ... Insulation coating 13A, 13B ... Tip part

Claims (1)

In measuring the potential of multiple steel materials arranged at different heights in a concrete structure,
A collating electrode bundle formed by bundling a plurality of collating electrodes each having a wire-shaped line electrode and an insulating coating covering the line electrode is removed, and the line electrode is exposed by removing the insulating coating from the tip portion of each collating electrode. And the height of each of the tip portions is embedded in the concrete structure in accordance with the height of the separate steel material, and the potential difference between each of the reference electrode and the reference electrode is measured.

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