JP5946867B2 - Method for identifying corrosion location of steel material in concrete structure and potential difference measuring device for identifying corrosion location - Google Patents

Description

  The present invention relates to a method for identifying a corrosion location of a steel material in a concrete structure and a potential difference measuring device for identifying the corrosion location. More specifically, the present invention relates to a method for efficiently identifying a corrosion site of a steel material embedded in a concrete structure and an apparatus therefor.

  In concrete structures in which steel materials are embedded, such as reinforced concrete, corrosion of steel materials due to deterioration over time has become a problem. As a method for investigating the corrosion status of steel materials embedded in a concrete structure, for example, Patent Document 1 discloses a method for detecting a corrosion location of a steel material by measuring a difference in natural potential of the steel material in two locations of concrete. It is disclosed. In the corrosion detection method disclosed in Patent Document 1, as shown in FIG. 8 (a), two main detection ends 101a and 101b having electrodes are brought into contact with the surface of the concrete 103 at a constant interval, and an electric potential measurement device. 100, the difference in natural potential of the steel material 102 in the two concrete 103 is measured. Then, as shown in FIGS. 8 (a) and 8 (b), one main detection end 101b is moved and sequentially brought into contact with the concrete surface to measure the difference in natural potential, thereby detecting the other main detection. A location where a natural potential relatively low with respect to the natural potential at the end 101a is detected, and a corrosion location of the steel material is specified.

JP-A-10-212292

  However, in the corrosion detection method disclosed in Patent Document 1, as shown in FIG. 8A and FIG. 8B, the steel material 102 is one for every embedded steel material 102. It is necessary to measure the potential difference by moving the main detection end 101b over the entire area. Therefore, for example, when investigating the corrosion status of steel materials in concrete structures used in large structures such as bridges, it is necessary to measure a very large number of measurement points, which requires enormous labor and time. There's a problem.

  This invention is made | formed in view of this problem, and provides the method and apparatus for specifying efficiently the corrosion location of the steel materials in the concrete structure with which the steel materials were embed | buried.

  The corrosion location specifying method of the present invention is a corrosion location specifying method for specifying a corrosion location of a steel material embedded in a concrete structure using a potential difference measuring device, wherein the potential difference measurement device is a surface of the concrete structure. The reference electrode in contact with the reference surface, the reference electrode in contact with the surface of the concrete structure, the reference electrode and the reference electrode are connected, the reference surface in contact with the reference electrode and the reference surface in contact with the reference electrode A potentiometer that measures a difference in natural potential of the steel material in the concrete structure, and the contact surface of the reference electrode that contacts the surface of the concrete structure is embedded in the concrete structure at a distance. A step of arranging the reference electrode on a reference surface, the reference electrode being formed on a reference surface, wherein the reference electrode is formed on a reference surface. And a step of measuring, by the potentiometer, a potential difference between a natural potential on a collation surface in contact with the collation electrode and a natural potential on a reference surface in contact with the reference electrode, It is moved along the concrete structure, and the difference in natural potential between the reference surface and the reference surface is measured at a plurality of locations. Among the concrete structures, the natural potential on the reference surface is the natural potential on the reference surface. A low potential large region lower than the potential is specified.

  Further, the corrosion location specifying method of the present invention is such that the area of the contact surface that contacts the surface of the concrete structure is smaller than the area of the contact surface where the reference electrode contacts the surface of the concrete structure. And further comprising the step of disposing the small region reference electrode in a region of the concrete structure that has been identified as the low potential large region, and is identified as the low potential large region The small region reference electrode is moved within the region, the difference in natural potential with the reference surface is measured at a plurality of locations, and the small region reference electrode is in contact with the low potential large region. It is preferable to specify a low-potential small region in which the natural potential on the reference surface is lower than the natural potential on the reference surface with which the reference electrode contacts.

  Moreover, in the corrosion location specifying method of the present invention, it is preferable that the reference electrode and the verification electrode include a wet pad.

  Moreover, the corrosion location specifying method of the present invention is such that the steel material is connected to one terminal of the potentiometer, the reference electrode or the verification electrode is connected to the other terminal of the potentiometer, It is preferable to further include a step of obtaining a natural potential of the steel material in the concrete structure.

  The potential difference measuring device of the present invention is a potential difference measuring device used for specifying a corrosion site of a steel material embedded in a concrete structure, wherein the potential difference measuring device is in contact with the surface of the concrete structure. A reference electrode in contact with the surface of the concrete structure, the reference electrode and the reference electrode are connected, the reference surface in contact with the reference electrode and the reference surface in contact with the reference electrode in the concrete structure A potentiometer that measures a difference in natural potential of the steel material, and the contact surface of the reference electrode that contacts the surface of the concrete structure spans a plurality of steel materials embedded in the concrete structure at a distance. The reference electrode is moved along the concrete structure so that the reference surface and the reference surface are formed at a plurality of locations. By measuring the difference in natural potential between the reference surfaces, it is possible to identify a low potential large region in the concrete structure where the natural potential on the reference surface is lower than the natural potential on the reference surface. It is characterized by being.

  In addition, the potential difference measuring apparatus according to the present invention includes a small region verification electrode in which an area of a contact surface in contact with the surface of the concrete structure is smaller than an area of a contact surface in which the verification electrode is in contact with the surface of the concrete structure. Further, within the region identified as the low potential large region, the small region verification electrode is moved, and at a plurality of locations, the difference in natural potential with the reference surface is measured, Among the low potential large regions, it is possible to identify a low potential small region in which the natural potential on the reference surface in contact with the small region reference electrode is lower than the natural potential on the reference surface in contact with the reference electrode. preferable.

  In the potential difference measuring apparatus of the present invention, it is preferable that the reference electrode and the verification electrode include a wet pad.

  ADVANTAGE OF THE INVENTION According to this invention, the method of identifying efficiently the corrosion location of the steel materials in the concrete structure with which the steel materials were embed | buried, and the apparatus for it can be provided.

It is a perspective view which shows typically one Embodiment of the potentiometric measuring apparatus used with the corrosion location identification method of this invention. It is a flowchart which shows one Embodiment of the process of specifying the low electric potential large area | region in the corrosion location identification method of this invention. It is a flowchart which shows one Embodiment of the process of pinpointing a low electric potential small area | region in the corrosion location identification method of this invention. It is a flowchart which shows one Embodiment of the process of obtaining the natural potential of the steel materials in a concrete structure in the corrosion location identification method of this invention. It is a schematic diagram which shows one Embodiment of the process of specifying the low electric potential large area | region in the corrosion location identification method of this invention, (a) has shown the state by which the reference electrode was contacted to the reference surface, (b ) Shows a state in which the reference electrode and the large area reference electrode are in contact with the reference surface and the reference surface, and (c) shows a state in which the position where the large area reference electrode contacts is sequentially changed. , (D) shows the finally identified low potential large area surface. It is a schematic diagram which shows one Embodiment of the process of specifying the low electric potential small area | region in the corrosion location identification method of this invention, (a) is a reference electrode contacting a reference surface, and a small area collation electrode is low electric potential large. (B) shows a state in which the contact position of the small region verification electrode is sequentially changed in the low potential large region, and (c) ) Shows the finally identified low potential subregion surface. It is a schematic diagram which shows one Embodiment of the process of obtaining the natural potential of the steel materials in a concrete structure in the corrosion location identification method of this invention. (A) is a side view which shows typically the steel-material corrosion measuring apparatus used for the conventional corrosion detection method, (b) is a plane which shows typically the steel-material corrosion measuring apparatus used for the conventional corrosion detection method FIG.

  Hereinafter, the corrosion location specifying method of the present invention will be described with reference to the accompanying drawings.

  The corrosion location specifying method of the present invention is a method for specifying a corrosion location of a steel material embedded in a concrete structure using a potential difference measuring device. As shown in FIG. 1, the concrete structure 11 to which the corrosion location specifying method of the present invention is applied is a structure in which a steel material 13 is embedded in concrete 12. The concrete structure to be applied is not particularly limited as long as it is a structure in which steel is embedded, but for example, a bridge of a bridge over a river or the sea, a bridge pier of an expressway, a dam, etc. Examples include civil engineering structures and buildings. Further, as the steel material 13 embedded in the concrete 12, in the present embodiment shown in FIG. 1, the reinforcing bar 13 including the main bar 13 a and the stirrup bar 13 b is used, and the bar arrangement method depends on the structure. The corrosive site identification method of the present invention can be applied to structures other than the bar arrangement shown in the present embodiment. In addition, examples of the steel material to which the method for identifying a corrosion site of the present invention can be applied include steel materials made of an alloy containing iron and iron, and any material that can measure a potential difference with a potential difference measuring device described later. Any steel material may be used. Moreover, as steel materials embed | buried in concrete, a steel frame, a steel pipe, etc. other than the reinforcing bar 13 may be sufficient. Hereinafter, the corrosion location specifying method of the present invention will be described based on an example in which the method is applied to a concrete structure 11 in which a reinforcing bar 13 is embedded in concrete 12 bonded by cement. In the following embodiment, a concrete beam extending in the horizontal direction will be described as an example. However, the present invention can also be applied to other structures such as a concrete structure extending in the vertical direction.

<Potential difference measuring device>
The potential difference measuring device 1 used in the method for identifying a corrosion location according to the present invention is used to identify the corrosion location of the steel material 13 embedded in the concrete structure 11, and from the surface of the concrete structure 11 to the concrete structure 11. This is a device for measuring the difference in natural potential between different regions of the steel material 13 embedded. As shown in FIG. 1, the potentiometer 1 includes a reference electrode 2 and a reference electrode 3 and 4 that are in contact with the surface of a concrete structure 11, and a reference surface 14 and a reference electrode 3 and 4 that are in contact with the reference electrode 2. And a potentiometer 5 for measuring a difference in natural potential of the steel material 13 in the concrete structure 11 on the collating surface 15 to be contacted. According to this potential difference measuring apparatus 1, the potential difference between the natural potential of the steel material 13 in the concrete structure 11 on the reference surface 14 and the natural potential of the steel material 13 in the concrete structure 11 on the reference surface 15 is the potentiometer 5. It is measured by. Here, the natural potential of the steel material is a potential measured by a natural potential measurement method used for estimating the corrosion state of the steel material in the concrete structure. If the natural potential on the verification surface 15 is lower than the natural potential on the reference surface 14, it is determined that the steel material 13 in the concrete structure 11 on the verification surface 15 may be corroded. And it is judged that the possibility that the steel material 13 is corroding is so high that the difference of the natural potential is large.

<Potentiometer>
The potentiometer 5 measures the potential difference between the reference electrode 2 and the verification electrode 3 or between the reference electrode 2 and the verification electrode 4. As shown in FIG. 1, the potentiometer 5 has at least two terminals on the plus side and the minus side. One terminal of the potentiometer 5 is electrically connected to the reference electrode 2 via a conducting wire 6 such as a lead wire. The other terminal of the potentiometer 5 is electrically connected to the verification electrodes 3 and 4 via a conducting wire 6 such as a lead wire. The potentiometer 5 used here has one terminal connected to a steel material in a concrete structure, the other terminal connected to an electrode in contact with the surface of the concrete structure, and the natural potential of the steel material in the concrete structure. A known potentiometer such as a potentiometer used for measurement can be used.

<Reference electrode>
As shown in FIG. 1, the reference electrode 2 has a natural potential (hereinafter referred to as a reference potential) that serves as a measurement reference when measuring a difference in natural potential between different regions of the steel material 13 in the concrete structure 11. This is an electrode that is in contact with the surface of the concrete structure 11 (reference surface 14) adjacent to the region of the steel material 13 in the cover thickness direction (directly above the region). The reference electrode 2 is in contact with the reference surface 14 and is electrically connected to one or the other terminal of the potentiometer 5 via a lead 6 such as a lead wire. As the reference surface 14, for example, a surface adjacent to the uncorroded region of the steel material 13 in the cover thickness direction (directly above the region) is arbitrarily selected from the surfaces of the concrete structure 11. However, the reference surface 14 may be the surface of the concrete structure 11 adjacent to the region of the steel material 13 having a natural potential as a reference in the cover thickness direction. The surface of the concrete structure 11 adjacent to each other may be used. Further, the size of the reference surface 14 is defined by the size of the reference electrode 2.

  Further, as shown in FIG. 1, the reference electrode 2 includes an electrode body 2a and a wet pad 2b on the side in contact with the reference surface. The electrode body 2a of the reference electrode 2 can employ a known electrode such as a copper / copper sulfate electrode, a silver / silver chloride electrode, or a calomel electrode. Further, the wet pad 2 b of the reference electrode 2 has a water injection / water retention function, and is configured such that the reference electrode 2 can be stably contacted and held on the surface of the concrete structure 11. The wet pad 2b has a water retaining material such as a sponge, and is wetted with an electrolyte solution such as tap water or a calcium hydroxide solution. Since the reference electrode 2 is provided with the wet pad 2b, the surface of the concrete structure 11 is surely kept in a wet state when the difference in natural potential is measured, and the reference electrode 2 and the concrete structure 11 Good electrical contact with the reference surface 14 is achieved. Further, in this embodiment, as shown in FIG. 1, the reference electrode 2 has a substantially rectangular parallelepiped shape in which a wet pad 2b is laminated on a thin plate-like electrode body 2a, as in a reference electrode 3 described later. Yes. However, the reference electrode 2 may have any shape or size as long as it can contact the reference surface 14 of the concrete structure 11 in order to use as a reference when measuring the potential difference with the potentiometer 5. Note that, in the present embodiment, the reference electrode 2 is formed in a size that spans a plurality of steel materials 13 that are embedded separately. As a result, the position of the steel material 13 embedded in the concrete structure 11 as in the prior art is searched, and the trouble of providing the reference electrode 2 immediately above the steel material 13 can be saved, and the potential difference between the reference electrodes 3 and 4 can be reliably ensured. It can be measured.

<Reference electrode>
As shown in FIG. 1, the verification electrodes 3 and 4 are natural objects to be measured with respect to a reference natural potential when measuring a difference in natural potential between different regions of the steel material 13 in the concrete structure 11. It is an electrode that is adjacent to the region of the steel material 13 having a potential in the cover thickness direction (directly above the region) and contacts the surface of the concrete structure 11 other than the reference surface 14 (the collation surface 15). The verification electrodes 3 and 4 are in contact with the verification surface 15 and are connected to the other or one terminal of the potentiometer 5 through a conductive wire 6 such as a lead wire. As the verification surface 15, a surface other than the reference surface 14 that is adjacent to the region of the steel material 13 to be measured in the cover thickness direction (directly above the region) from the surface of the concrete structure 11 is arbitrarily selected. Selected. The size of the verification surface 15 is defined by the size of the verification electrodes 3, 4.

  Further, as shown in FIG. 1, the verification electrodes 3 and 4 include wet pads 3 b and 4 b on the side in contact with the electrode bodies 3 a and 4 a and the verification surface 15. As the electrode bodies 3a and 4a of the verification electrodes 3 and 4, known electrodes such as a copper / copper sulfate electrode, a silver / silver chloride electrode, and a calomel electrode can be adopted. Further, the wet pads 3b and 4b of the verification electrodes 3 and 4 have a water injection / water retention function, and are configured so that the verification electrodes 3 and 4 can be stably contacted and held on the surface of the concrete structure 11. . The wet pads 3b and 4b have a water retaining material such as a sponge, and are wetted with an electrolyte solution such as tap water or a calcium hydroxide solution. Since the verification electrodes 3 and 4 are provided with the wet pads 3b and 4b, the surface of the concrete structure 11 is surely kept in a wet state when the difference in natural potential is measured. And the electrical contact between the verification surface 15 of the concrete structure 11 is improved. In this embodiment, the verification electrodes 3 and 4 have a substantially rectangular parallelepiped shape in which wet pads 3b and 4b are laminated on thin plate-like electrode bodies 3a and 4a. However, the shape of the verification electrodes 3 and 4 is not particularly limited as long as it has a function described later.

  Moreover, the collation electrode has the large area | region collation electrode 3 and the small area | region collation electrode 4 from which the area which contacts the surface of the concrete structure 11 differs as FIG. 1 shows. The potential difference measuring apparatus 1 can measure the difference in natural potential of the steel material 13 in different areas by having the plurality of reference electrodes 3 and 4 having different contact areas. In this embodiment, the verification electrodes 3 and 4 have two types of electrodes having different areas in contact with the surface of the concrete structure 11, but depending on the area to be measured by the potential difference measuring device 1, Only the large region verification electrode 3 having a large area may be included, or three or more types of electrodes having different contact areas may be included.

<Large area reference electrode>
As shown in FIG. 1, the large region verification electrode 3 is in contact with the surface of the concrete structure 11 (the verification surface 15) in a large region, and for each predetermined region (large region) of the steel material 13, It is an electrode for measuring the difference. Here, the predetermined region refers to a region where there are a plurality of steel materials 13 embedded in the cover thickness direction of the verification surface 15 in contact with the large region verification electrode 3 (below the verification surface 15), or the same steel material 13. The area | region which covers the length beyond the embedding pitch of the steel material 13 for the steel material 13 to predetermined length, for example. The potential difference measuring apparatus 1 can measure the difference between the reference potential and the natural potential of the steel material 13 included in the large region by including the large region matching electrode 3. In other words, the potential difference measuring apparatus 1 can collectively measure the difference in natural potential between the steel material 13 existing in the large region and the steel material 13 having the reference potential in one measurement.

  As shown in FIG. 1, the large region verification electrode 3 has a contact surface area in contact with the surface of the concrete structure 11 such that the small region verification electrode 4 described in detail below is in contact with the surface of the concrete structure 11. It is formed so as to be larger than the area of the surface. Accordingly, the large region matching electrode 3 is brought into contact with a wider matching surface 15 as compared with the small region matching electrode 4, and the potential difference measuring device 1 is configured to detect the reference potential and the natural potential of the steel material 13 in a wider region. And the difference can be measured. In the present embodiment, as shown in FIG. 1, the large region verification electrode 3 has a contact surface that contacts the surface of the concrete structure 11 spans a plurality of steel materials 13 embedded in the concrete structure 11 at a distance. It is formed to be a size. More specifically, as shown in FIG. 1, the large region verification electrode 3 spans a plurality of main bars 13 a that are embedded in a spaced manner and a plurality of streaks 13 b that are embedded in a spaced manner. Is formed. Thus, since the large area | region collation electrode 3 is formed in the magnitude | size which straddles the some steel materials 13, the electric potential difference measuring apparatus 1 is the natural potential of the area | region of the some steel materials 13 embedded separately from the reference potential. Can be collectively measured in a single measurement.

<Small area reference electrode>
The small region verification electrode 4 measures the potential difference between the potential of a small region smaller than the large region and the reference potential, which is obtained by further subdividing the large region obtained by collectively measuring the potential difference from the reference electrode 2 by the large region verification electrode 3. Electrode. The small area of the small area verification electrode 4 refers to the relative size of the large area verification electrode 3 with respect to the large area. As shown in FIG. 1, the small region verification electrode 4 has an area of a contact surface in contact with the surface of the concrete structure 11 that is larger than an area of a contact surface in which the large region verification electrode 3 contacts the surface of the concrete structure 11. Is formed to be smaller. The size of the small region verification electrode 4 is not particularly limited as long as the small region verification electrode 4 is formed as described above. However, the small region verification electrode 4 is preferably less than half the area of the large region verification electrode 3 and embedded in the concrete structure 11. It is more preferable that the size does not extend over the plurality of steel materials 13.

  The potential difference measuring apparatus 1 can measure the difference between the reference potential and the natural potential of the small region of the steel material 13 by including the small region matching electrode 4. As described above, in the small region verification electrode 4, the area of the contact surface in contact with the surface of the concrete structure 11 is smaller than the area of the contact surface in which the large region verification electrode 3 is in contact with the surface of the concrete structure 11. It is formed as follows. Accordingly, the small region matching electrode 4 is brought into contact with a narrower matching surface 15 as compared with the large region matching electrode 3, and the potential difference measuring device 1 is capable of comparing the reference potential and the natural potential of the region of the steel material 13 existing in the narrower region. And the difference can be measured. In the present embodiment, the small region matching electrode 4 is formed in a size substantially corresponding to the width of the steel material 13 embedded in the concrete structure 11 as shown in FIG. In this way, by forming the small region verification electrode 4 in a size substantially corresponding to the width of the steel material 13, the potential difference measuring device 1 is able to detect the reference potential and the region having a size substantially corresponding to the width of the steel material 13. The difference from the natural potential can be measured.

<Corrosion spot identification method>
Next, the corrosion location specifying method of the present invention using the potential difference measuring apparatus 1 described so far will be described with reference to the flowcharts shown in FIGS. 2 to 4 and the schematic diagrams shown in FIGS. .

<Step of identifying low potential large region>
As shown in FIG. 2 and FIG. 5, the corrosion location specifying method of the present invention includes a process SA for specifying the low potential large region 16 by using the reference electrode 2 and the large region verification electrode 3 in the concrete structure 11. Yes. The low potential large region 16 is a region in which the natural potential of the steel material 13 on the verification surface 15 in contact with the large region verification electrode 3 is lower than the natural potential of the steel material 13 on the reference surface 14 in contact with the reference electrode 2. In the present embodiment, the process SA includes processes S1 to S4 as shown in FIG.

  In step SA, first, in step S1, the reference electrode 2 is brought into contact with the reference surface 14 of the concrete structure 11 (FIG. 5A). More specifically, the wet pad 2 b of the reference electrode 2 in a wet state is brought into contact with the surface of the concrete structure 11 to hold the position of the reference electrode 2. It is preferable that the position where the reference electrode 2 is brought into contact is a place where there is no or little corrosion of the steel material 13 directly below, which is determined by a prior investigation or the like. For example, when a location where the corrosion of the steel material 13 directly below is selected as a position where the reference electrode 2 is brought into contact, a region having a natural potential higher than the natural potential of the reference surface 14 is found in a later step. The region may be newly set as the reference surface 14 as a portion having less corrosion or no corrosion.

  Next, in step S2, the large region verification electrode 3 is brought into contact with the verification surface 15 of the concrete structure 11 (FIG. 5B). In addition, process S1 and process S2 may be reverse order. Similar to the reference electrode 2, the large region verification electrode 3 brings the wet pad 3 b in a wet state into contact with the surface of the concrete structure 11 and holds the position of the large region verification electrode 3. In the present embodiment, as shown in FIG. 5B, the large region verification electrode 3 is in contact with the surface of the concrete structure 11 at a position adjacent to the reference electrode 2. In this state, in this embodiment, as shown in FIG. 5 (b), the large region verification electrode 3 includes a plurality of steel materials 13 (in FIG. 5 (b), three main bars 13a and two stirrup bars). 13b) is covered.

  After the installation of the reference electrode 2 and the large region verification electrode 3 is completed in step S1 and step S2, the potential difference between the reference electrode 2 and the large region verification electrode 3 is measured using the potentiometer 5 in step 3. To do. Thereby, the difference between the natural potential (reference potential) of the steel material 13 on the reference surface 14 and the natural potential of the steel material 13 on the reference surface 15 is measured. At this time, if the natural potential on the collation surface 15 is lower than the natural potential on the reference surface 14 by a predetermined threshold or more, the steel material 13 is positioned adjacent to the collation surface 15 in the cover thickness direction (directly below the collation surface 15). It is determined that there is a corroded portion, and the reference surface 15 is determined as the low potential large region 16 (see FIG. 5D). On the other hand, when the natural potential on the reference surface 15 is substantially the same as the reference potential on the reference surface 14 or the difference is within a predetermined threshold range, the large region in contact with the large region verification electrode 3 It is determined that there is no corroded portion in the inner steel material 13.

  After step S3, in step S4, it is determined whether there is another surface to be measured. If there is another surface to be measured, the large region verification electrode 3 is moved along the concrete structure 11 and the steps 2 and 3 are repeated (FIG. 5C). That is, the large region verification electrode 3 is moved along the extending direction of the steel material 13 of the concrete structure 11, and the reference electrode 2 and the large region verification electrode 3 are arranged between the verification surface 15 and the reference surface 14 at a plurality of locations. Measure the difference in natural potential.

  If there is no other surface to be measured, the process SA is terminated, and the large region verification electrode 3 is removed from the surface of the concrete structure 11. Through the above steps, the low potential large region 16 is identified from the surface of the concrete structure 11 (FIG. 5D). That is, the potential difference is sequentially measured from FIG. 5A to FIG. 5D, and when a potential difference equal to or greater than the threshold value is generated in the state of FIG. 5C for the first time, FIG. It is determined that there is corrosion in any of the reinforcing bars 13 in the low potential large region 16 shown. For example, if a potential difference equal to or greater than the threshold value occurs at the position shown in FIG. 5B and a potential difference equal to or greater than the threshold value occurs at the position shown in FIG. It is determined that any of the steel materials 13 existing at the positions of the collation surface 15 in FIG. 5 and the collation surface 15 in FIG. In addition, it is preferable to clean the reference | standard surface 14 and the collation surface 15 and to remove oil stains etc. from the reference | standard surface 14 and the collation surface 15 before process S1 and process S2.

  The corrosion location specifying method of the present invention can specify the corrosion location in a region including a plurality of steel materials 13 in the concrete structure 11 by providing the process SA for specifying the low potential large region 16. Therefore, it is not necessary to measure the potential difference of the steel material 13 one by one as in the prior art, and the time required for checking whether the steel material 13 of the concrete structure 11 is corroded is greatly reduced. That is, in the past, the potential difference of the steel material 13 was measured one by one, and it was measured over time at a point where there was no corrosion and no abnormality. It was a lot. On the other hand, in the present invention, when there is no corrosion portion, the measurement is performed by the large region verification electrode 3 so that the large region verification electrode 3 extends over a plurality of steel materials 13, for example. A plurality of steel materials 13 can be inspected together one after another, and can be inspected significantly faster than before. In the case of a large structure such as a bridge, it is particularly time-consuming if the steel materials 13 are confirmed one by one. Therefore, the method for identifying a corrosion site of the present invention is particularly advantageous in the case of a large structure. Moreover, when there exists a corrosion location, the large area | region (low potential large area | region) which has a corrosion location among the whole concrete structures 11 can be specified roughly, and the low potential small area | region mentioned later is specified. By combining with a process, a specific corrosion location can be specified.

<Step of identifying a low potential small region>
As shown in FIGS. 3 and 6, the corrosion location specifying method of the present invention further includes a low potential small region of the low potential large region 16 specified by the process SA by the reference electrode 2 and the small region verification electrode 4. The process SB which specifies 17 is provided. The low potential small region 17 is a region in which the natural potential of the steel material 13 on the verification surface 15 in contact with the small region verification electrode 4 is lower than the natural potential of the steel material 13 on the reference surface 14 in contact with the reference electrode 2. In the present embodiment, step SB includes step S5 to step S8 as shown in FIG.

  In step SB, first, in step S5, the reference electrode 2 is brought into contact with the reference surface 14 of the concrete structure 11 (FIG. 6A). In step S5, the reference electrode 2 used in step S1 can be used as it is, or a reference electrode 2 having a different size, for example, a reference electrode 2 having a contact surface of the same size as the contact surface of the small region matching electrode 4 is used. It can also be used anew. At this time, when the reference electrode 2 and the reference surface 14 in step S1 are used as they are, step S5 can be omitted. Next, in step S6, the small region matching electrode 4 is brought into contact with the matching surface 15 selected from the low potential large region 16 specified in step SB (FIG. 6A). At this time, it is preferable to select the collation surface 15 so that the distance to the steel material 13 is as short as possible, and it is particularly preferable to select so that the steel material 13 is directly below. In addition, process S5 and process S6 may be reverse order.

  After step S5 and step S6, in step 7, the potentiometer 5 is used to measure the potential difference between the reference electrode 2 and the small region verification electrode 4, and the natural potential of the steel material 13 on the reference surface 14 and the verification surface 15 is measured with respect to the natural potential of the steel material 13. At this time, if the natural potential on the verification surface 15 is lower than the natural potential on the reference surface 14, the corrosion portion of the steel material 13 exists at a position adjacent to the verification surface 15 in the cover thickness direction (directly below the verification surface 15). Judgment is made, and the collation surface 15 is determined as the low potential small region 17 (see FIG. 6C).

  After step S7, in step S8, it is determined whether there is another surface to be measured. If there is another surface to be measured, the small region verification electrode 4 is moved, and the steps S6 and S7 are repeated (FIG. 6B). That is, the small region matching electrode 4 is moved within the region identified as the low potential large region 16 in step SA, and the natural potential between the reference surface 14 and the matching surface 15 is moved at a plurality of locations. Measure the difference. If there is no other surface to be measured, the process SB is terminated, and the small region verification electrode 4 is removed from the surface of the concrete structure 11. Through the above steps, the low potential small region 17 is identified from the surface of the concrete structure 11 (FIG. 6C). In addition, it is preferable to clean the reference | standard surface 14 and the collation surface 15 and to remove oil stains from the reference | standard surface 14 and the collation surface 15 before process S5 and process S6.

  The corrosion location specifying method of the present invention includes the step SA for specifying the low potential large region 16 and the step SB for specifying the low potential small region 17, thereby searching for the corrosion location of the steel material 13 in wide area units in the step SA. After specifying, the corrosion location of the steel material 13 can be searched and specified in a narrow area unit in the step SB from the specified wide area. Therefore, the corrosion location specifying method of the present invention is based on one point for each of the steel materials 13 embedded as in the conventional method, one point at a time over the entire region of the steel material 13, and the verification electrodes 3, 4 It is not necessary to measure the potential difference by moving the, and the corrosion location of the steel material 13 in the concrete structure 11 can be efficiently identified.

<Step of obtaining the natural potential of steel>
As shown in FIGS. 4 and 7, the corrosion location specifying method of the present invention further includes connecting the steel material 13 to one terminal of the potentiometer 5 and connecting the reference electrode 2 or the reference electrode to the other terminal of the potentiometer 5. The process SC which connects 3 and 4 and obtains the natural potential of the steel material 13 in the concrete structure 11 in the collation surface 15 may be provided. In the present embodiment, the process SC includes a process S9 and a process 10 as shown in FIG. In step SC, first, in step 9, the steel material 13 of the concrete structure 11 is electrically connected to one terminal of the potentiometer 5 via the conductor 6, and the other terminal of the potentiometer 5 via the conductor 6; The reference electrode 2 in contact with the reference surface 14 is electrically connected (FIG. 7), and the natural potential of the steel material 13 in the concrete structure 11 on the reference surface 14 is measured. Thereafter, in step 10, the measured natural potential of the steel material 13 in the concrete structure 11 on the reference surface 14 and the reference surface 14 and the reference electrode 3, which are measured in the steps SA and SB, are in contact with the reference electrode 2. 4 is used to determine the natural potential of the steel material 13 in the concrete structure 11 on the verification surface 15 by using the difference in natural potential of the steel material 13 in the concrete structure 11 on the verification surface 15 (see FIGS. 5 and 6) with which 4 contacts. calculate. Through the above steps, the natural potential of the steel material 13 in the concrete structure 11 on the verification surface 15 is obtained. The process SC includes the processes 9 and 10 in the present embodiment, but may include other processes as long as the natural potential of the steel material 13 in the concrete structure 11 on the verification surface 15 can be obtained. For example, in the process SC, the steel material 13 in the concrete structure 11 is electrically connected to one terminal of the potentiometer 5 via the conductor 6, and the reference surface is connected to the other terminal of the potentiometer 5 via the conductor 6. A step of electrically connecting the verification electrodes 3 and 4 in contact with 15 to measure the natural potential of the steel material 13 in the concrete structure 11 on the verification surface 15 may be provided.

  According to the corrosion location specifying method of the present invention, by providing the process SC for obtaining the natural potential of the steel material 13, the natural potential of the steel material 13 in the concrete structure 11 can be obtained as an absolute value. The obtained natural potential can be directly compared with the natural potential of the steel material 13 in the other concrete structure 11, and the corrosion status of the steel material 13 is directly compared with the corrosion status of the steel material 13 in the other concrete structure 11. be able to. Therefore, the reliability of the corrosion evaluation of the steel material 13 in the concrete structure 11 is improved.

DESCRIPTION OF SYMBOLS 1 Potential difference measuring apparatus 2 Reference electrode 2a Electrode main body 2b Wet pad 3 Large area | region collation electrode 3a Electrode main body 3b Wet pad 4 Small area | region collation electrode 4a Electrode main body 4b Wet pad 5 Potentiometer 6 Conductor 11 Concrete structure 12 Concrete 13 Steel, Rebar 13a main muscle 13b rib muscle 14 reference surface 15 reference surface 16 low potential large region 17 low potential small region

Claims (7)

Using a potentiometer, a corrosion location identification method for identifying a corrosion location of a steel material embedded in a concrete structure,
The potential difference measuring device is
A reference electrode in contact with the surface of the concrete structure;
A reference electrode in contact with the surface of the concrete structure;
A potentiometer that is connected to the reference electrode and the reference electrode, and that measures a difference in natural potential of the steel in the concrete structure on the reference surface that the reference electrode contacts and the reference surface that the reference electrode contacts; ,
The reference electrode is formed so that the contact surface that contacts the surface of the concrete structure has a size that spans a plurality of steel materials embedded in the concrete structure apart from each other,
Placing the reference electrode on a reference surface;
The step of disposing the reference electrode on the reference surface and the potential difference meter measure a potential difference between a natural potential on the reference surface in contact with the reference electrode and a natural potential on the reference surface in contact with the reference electrode. With a process,
The collation electrode is moved along the concrete structure, and the difference in natural potential between the collation surface and the reference surface is measured at a plurality of locations. Among the concrete structures, the natural potential on the collation surface is A method for identifying a corrosion site, characterized by identifying a low potential large region lower than a natural potential on a reference surface. A small region verification electrode having an area of a contact surface in contact with the surface of the concrete structure is smaller than an area of a contact surface in which the verification electrode is in contact with the surface of the concrete structure;
In the region specified to be the low potential large region of the concrete structure, further comprising the step of arranging the small region verification electrode,
In the region identified as the low potential large region, the small region verification electrode is moved, and a difference in natural potential from the reference surface is measured at a plurality of locations, and the low potential large region 2. The corrosion according to claim 1, wherein a low potential small region having a natural potential on a reference surface in contact with the small region reference electrode is lower than a natural potential on a reference surface in contact with the reference electrode. Location identification method. The corrosion location specifying method according to claim 1, wherein the reference electrode and the reference electrode include a wet pad. The steel material is connected to one terminal of the potentiometer, the reference electrode or the verification electrode is connected to the other terminal of the potentiometer, and the natural potential of the steel material in the concrete structure on the verification surface is determined. The corrosion location specifying method according to claim 1, further comprising a step of obtaining. A potential difference measuring device used to identify a corrosion location of a steel material embedded in a concrete structure,
The potential difference measuring device is
A reference electrode in contact with the surface of the concrete structure;
A reference electrode in contact with the surface of the concrete structure;
A potentiometer that is connected to the reference electrode and the reference electrode, and that measures a difference in natural potential of the steel in the concrete structure on the reference surface that the reference electrode contacts and the reference surface that the reference electrode contacts; ,
The reference electrode is formed so that the contact surface that contacts the surface of the concrete structure has a size that spans a plurality of steel materials embedded in the concrete structure apart from each other,
By moving the verification electrode along the concrete structure and measuring the difference in natural potential between the verification surface and the reference surface at a plurality of locations, the natural potential on the verification surface of the concrete structure is reduced. A potential difference measuring apparatus capable of specifying a low potential large region lower than the natural potential on the reference surface. A small region verification electrode having an area of a contact surface in contact with the surface of the concrete structure is smaller than an area of a contact surface in which the verification electrode is in contact with the surface of the concrete structure;
In the region identified as the low potential large region, the small region verification electrode is moved, and a difference in natural potential from the reference surface is measured at a plurality of locations, and the low potential large region Among them, it is possible to specify a low-potential small region whose natural potential on the collation surface with which the small region collation electrode contacts is lower than the natural potential on the reference surface with which the reference electrode contacts. Item 6. A potential difference measuring apparatus according to Item 5. The potentiometer according to claim 5 or 6, wherein the reference electrode and the verification electrode include a wet pad.

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