JP6640664B2 - Steel potential measurement method - Google Patents

Description

  The present invention relates to a steel material potential measuring method for non-destructively measuring a 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 include, for example, flying salt near the coast and spraying of a deicing agent in cold regions. When the steel material in the concrete structure is corroded, cracking occurs in the cover concrete due to the expansion pressure of the steel material in the corroded portion, or rust juice leaks out, so that the corrosion state of the steel material is first revealed. However, repair and renovation work of concrete structures at the stage when the corrosion state of steel is exposed requires a large cost. Therefore, a technique for non-destructively measuring the state of steel corrosion at a stage where steel corrosion is not exposed has been attracting attention.

  One of the non-destructive methods for non-destructively measuring the corrosion state of steel in concrete structures is the self-potential measurement method. The spontaneous potential measurement method is a method of measuring a potential of a steel material surface that changes due to corrosion of a steel material in a concrete structure. Generally, the more the corrosion of the steel material proceeds, the more the potential of the steel material becomes lower (−). Side). In the self-potential measurement method, an electrode body called a reference electrode and a potentiometer are used. The positive terminal of the potentiometer is connected to a steel material, the lead terminal of the reference electrode is connected to the negative terminal, and the reference electrode is connected to a concrete surface. The measurement is carried out by abutting the concrete or embedding it in the concrete body. A reference electrode of the type in contact with a concrete surface is called a portable reference electrode, and a reference electrode of a type embedded in a concrete body is called an embedded reference electrode (for example, Patent Document 1).

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

  There is also known a technique of performing measurement by embedding a fine wire-shaped noble metal-coated titanium wire as a reference electrode in a concrete structure (for example, Patent Document 3).

JP-A-61-124863 JP 2013-224456 A JP 2001-013100 A

  Corrosion of steel materials in concrete structures is deeply affected by salt damage, especially near the coast, and by road spraying of deicing agents such as sodium chloride and calcium chloride in cold regions. In particular, salt damage near the coast appears as corrosion from the steel material on the lower side of the concrete structure, and salt damage caused by spraying the deicing agent on the road gradually progresses from the steel material on the upper side.

  In the measurement method using the portable reference electrode, since the measurement is performed by bringing the reference 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 in which the concrete surface on the upper surface side is covered by a pavement, etc., in order to measure corrosion of steel on the upper side (road surface side) of the concrete structure using a portable reference electrode, The concrete surface is exposed by cutting the road surface, and after the measurement, it is necessary to perform a road surface restoration work.

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

  However, when measuring multiple steel materials at different height positions, such as the upper and lower parts of a concrete structure, it is necessary to embed each reference electrode in accordance with the height position of each steel material. It takes time to cut the perforations for embedding the holes. 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 potential measuring method that can reduce the cost of 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 method of measuring a steel material potential according to one embodiment of the present invention is a method of measuring a potential of a plurality of steel materials disposed at different heights in a concrete structure. A reference electrode bundle in which a plurality of reference electrodes each having an insulating coating covering the line electrode is bundled, the insulating coating at a tip portion of each of the reference electrodes is removed to expose the line electrodes, and each of the reference electrodes is exposed. The height of the tip portion is embedded in the concrete structure in accordance with the height of the steel material, and the potential difference between each of the reference electrode and the reference electrode is measured.

  According to the present invention, a reference electrode bundle obtained by bundling a plurality of reference electrodes is exposed by removing the insulating coating of the tip portion of each reference electrode to expose the line electrode, and each tip portion has a height of a separate steel material. By embedding in a concrete structure according to the above, the embedding work of a plurality of reference electrodes can be performed efficiently.

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

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic cross-sectional view of a concrete structure viewed from a side direction for describing a method of measuring corrosion of reinforcing steel according to an embodiment of the present invention. It is AA 'sectional drawing of the concrete structure of FIG. It is a figure showing the example of the collation electrode bundle used in the rebar corrosion measurement method of this embodiment. It is a schematic sectional drawing which shows the embedding method of the reference electrode bundle in a concrete structure in the reinforcing-bar corrosion measurement method of this embodiment. It is a schematic sectional drawing similarly showing the embedding method of the reference electrode bundle in a concrete structure in the reinforcing-bar corrosion measurement method of this embodiment. It is a schematic sectional drawing for demonstrating the connection method of the potentiometer 20 when measuring the corrosion of the upper reinforcing bar 3.

Hereinafter, embodiments of 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 a side direction for explaining an embodiment of a method for measuring corrosion of steel bars employing a method for measuring a steel material potential according to the present invention, and FIG. 3 is a sectional view taken along line AA ′ of FIG.

[Summary of Rebar Corrosion Measurement Method of Present Embodiment]
First, the outline of the method of measuring corrosion of reinforcing steel according to the present embodiment will be described. This method of measuring corrosion of reinforcing steel measures the state of corrosion of a plurality of reinforcing bars 2 and 3 disposed at different heights in the concrete structure 1 by measuring the natural potential. When measuring by the method, the reference electrode bundle 10 in which a plurality of reference electrodes 10A and 10B having wire-shaped line electrodes 11A and 11B and insulating coatings 12A and 12B covering the line electrodes 11A and 11B are bundled with each reference electrode The insulating coatings 12A and 12B of the tips 13A and 13B of 10A and 10B are removed to expose the line electrodes 11A and 11B, and the height of each tip 13A and 13B is adjusted to the height of the separate reinforcing bars 2 and 3. And embedded in the concrete structure 1 to measure the potential difference between each of the reference electrodes 10A and 10B and the reference electrode.

  Note that the potential of the reference electrode is the potential of any reinforcing bar in the concrete structure 1. 1 and 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-described method of measuring corrosion of reinforcing steel will be described in more detail.
[Configuration of the reference electrode bundle 10]
FIG. 3 is a side view showing the configuration of the reference electrode bundle 10 used in the method of measuring reinforcing steel corrosion of the present embodiment.

  As shown in the figure, the reference electrode bundle 10 used in the method for measuring reinforcing steel corrosion according to the present embodiment is such that two thin line-shaped reference electrodes 10A and 10B are bundled together by, for example, one or more binding bands 21 or the like. It is composed. The two reference electrodes 10A and 10B may be bound together by an adhesive, or may be bound together by twisting each other.

  The configuration of each of the reference electrodes 10A and 10B in the reference electrode bundle 10 is basically the same. One reference electrode 10A has a wire-shaped line electrode 11A, an insulating coating 12A that covers the line electrode 11A, a lead wire 14A, and a connection portion 15A. Similarly, the other reference electrode 10B also has a wire-shaped line electrode 11B, an insulating coating 12B covering the line electrode 11B, a lead wire 14B, and a connection portion 15B. The connection portions 15A and 15B are portions for electrically connecting the line electrodes 11A and 11B and the ends of the lead wires 14A and 14B. The main difference between each of the reference electrodes 10A and 10B is its length, in other words, only at 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. is there.

  The line electrodes 11A and 11B are composed of a wire made of titanium (Ti) and a noble metal coating made of any one of iridium (Ir), ruthenium (Ru), hafnium (Hf) or rhodium (Rh) covering the titanium wire. Is done. Titanium is a metal having a high potential and a high strength with respect to iron, and has a high durability, is easily drawn, and is suitable as a thin-line reference electrode material. However, since titanium is easily oxidized, it is desirable to coat it with the above-mentioned noble metal that is resistant to acids and alkalis to prevent this. The diameter of the line electrodes 11A and 11B is about 1.0 to 3.0 mm.

[Method of Embedding Reference Electrode Bundle 10]
4 and 5 are schematic sectional views showing a method of embedding the reference electrode bundle 10 in the concrete structure 1.
For embedding the reference electrode bundle 10 in the concrete structure 1, for example, as shown in FIG. 4, a perforation 6 is provided by cutting or the like from the lower surface 1A of the concrete structure 1, and as shown in FIG. Is carried out by inserting a collating electrode bundle 10 into the hole and filling a gap in the perforation 6 with a repair material 7 such as mortar. The perforations 6 are formed from the lower surface 1A 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 to be measured. 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 therebetween.

  Alternatively, the reference electrode bundle 10 may be embedded at the time of placing the concrete structure 1 in concrete. Alternatively, a punch for forming the perforations 6 may be embedded at the time of casting concrete, and the perforations 6 may be obtained by removing the punches together with the mold when the mold is dismantled.

  As shown in FIGS. 1, 2 and 5, in the reference electrode bundle 10 embedded in the concrete structure 1, one of the reference electrodes 10 </ b> A sets the lower reinforcing bar 2 in the concrete structure 1 as a corrosion measurement target. In order to do so, the distal end portion 13A of the line electrode 11A, which has been 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 connects the tip portion 13B of the line electrode 11B, which has been exposed after the insulating coating 12B has been removed, to the upper reinforcing bar 3 in the concrete structure 1 in order to measure the upper reinforcing bar 3 in the concrete structure 1. It is 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 reinforcing bar 2, and the height of the center of the tip portion 13B of the line electrode 11B matches the height of the upper reinforcing bar 3. It is desirable to match the height.

  In addition, since each of the reference electrodes 10A and 10B is entirely covered with the insulating coatings 12A and 12B except for the tip portions 13A and 13B, the space between the line electrodes 11A and 11B is provided. They are electrically insulated.

  Further, as shown in FIGS. 1, 2 and 5, the reference electrode bundle 10 is provided in a state where the lead wires 14A and 14B of the respective reference electrodes 10A and 10B are drawn out from the lower surface 1A of the concrete structure 1. It is embedded in the structure 1. In addition, it is preferable that the surface of each of the lead wires 14A and 14B is covered with an insulating coating, similarly to the line electrodes 11A and 11B, in order to avoid continuity during measurement.

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

  When performing the 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 pulled out from the lower surface of the concrete structure 1. The connected lead wire 14A is connected to the negative terminal of the potentiometer 20. Thereby, the potential difference between the reference 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 measurement of the reinforcing bar 3 is performed, 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 pulled out from the lower surface of the concrete structure 1. Connected to the negative terminal of the potentiometer 20. Thereby, the potential difference between the reference 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 rebar corrosion measuring method of the present embodiment, the reference electrode bundle 10 including the plurality of reference electrodes 10A and 10B is provided with the insulating coating 12A of the tip portions 13A and 13B of the respective reference electrodes 10A and 10B. , 12B are removed to expose the line electrodes 11A, 11B, and the height of each tip portion 13A, 13B is embedded in the concrete structure 1 in accordance with the height of the separate reinforcing bars 2, 3. The embedding operation of the reference electrodes can be performed more efficiently than a typical method of separately embedding the reference electrodes having different lengths into the reinforcing bars 2 and 3 having different heights in the object 1.

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

  In addition, the method of measuring corrosion of a reinforcing bar according to the present embodiment can be employed for measuring corrosion of reinforcing bars in an existing concrete structure as well as in a new concrete structure.

  The number of the reference electrodes constituting the reference electrode bundle 10 is determined according to the number of reinforcing bars having different heights to be measured in the concrete structure 1. In the example of FIG. 1, two reference electrodes 10 </ b> A and 10 </ b> B are used because the upper rebar 2 and the lower rebar 3 are to be measured, but the upper rebar 2 and the lower rebar 2 are used. In the case where a reinforcing bar (not shown) having a height between 3 and 3 is also to be measured, the number of reference electrodes is 3 or more. As described above, the reinforcing bar corrosion measuring method of the present embodiment can cope 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. It is possible to

  As described above, the method for measuring corrosion of reinforcing steel of a newly-installed or existing concrete structure has been described. However, 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 its effect in the cathodic protection method. It is possible to

DESCRIPTION OF SYMBOLS 1 ... Concrete structure 2, 3 ... Reinforcing bar 6 ... Perforation 7 ... Repair material 10 ... Reference electrode bundle 10A, 10B ... Reference 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 reference electrode bundle obtained by bundling a plurality of reference electrodes each having a wire-shaped line electrode and an insulating coating covering the line electrode, exposing the line electrode by removing the insulating coating at the tip of each of the reference electrodes A method for measuring a potential of a steel material, wherein the height of each of the tip portions is adjusted to the height of a different one of the steel materials and embedded in the concrete structure, and the potential difference between each of the reference electrode and the reference electrode is measured.

Images