Concrete Specimen, Method for Manufacturing Concrete Specimen, and Method for Measuring Hydrogen Amount

Abstract

The present invention comprises concrete (11) that has a planar first surface, metal (12) that is embedded in the first surface, and a nickel film or a palladium film that is formed on the first surface that includes the metal (12).

Description

Technical Field

[0001] The present invention relates to a concrete specimen, a method for manufacturing the concrete specimen, and a method for measuring the amount of hydrogen.

Background Art

[0002] Reinforcing bars are embedded inside reinforced concrete structures such as infrastructure facilities. Since reinforced concrete structures are placed outdoors, hydrogen generated by the corrosion reaction penetrates into the metal inside the reinforcing bars. As the amount of hydrogen penetrating into the metal increases, the probability of the metal deteriorating and breaking increases. Therefore, the amount of hydrogen penetrating into the metal is measured to non-invasively inspect the deterioration of the reinforcing bars.

[0003] As a method for measuring the amount of hydrogen penetrating into the metal, for example, a test apparatus disclosed in Non-Patent Document 1 is known.

[0004] In the test apparatus disclosed in Non-Patent Document 1, one surface of a metal plate to be tested is set as a hydrogen penetration surface and placed in a corrosion environment. The other surface of the metal plate is set as a hydrogen detection surface and placed in a sodium hydroxide solution. When hydrogen that has penetrated into the metal plate from the hydrogen penetration surface diffuses inside the metal plate and reaches the hydrogen detection surface, the hydrogen is electrochemically forced to ionize in the sodium hydroxide solution. The current due to the electrons released when hydrogen ionizes is detected, and based on the detected current value, the amount of hydrogen that has penetrated into the inside of the metal plate can be calculated.

Prior Art Documents

Non-Patent Documents

[0005]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, in the test apparatus disclosed in Non-Patent Document 1, a metal foil or a metal plate is used as the test object for the hydrogen permeation test, and there is no mention of using concrete (hereinafter referred to as "concrete specimen") in which a metal plate is embedded as the test object.

[0007] In addition to its role as a test object, the metal plate also serves as a partition plate to prevent leakage of the sodium hydroxide solution in contact with the hydrogen detection surface. Since concrete permeates the sodium hydroxide solution, even if the concrete specimen could be installed in the test apparatus, the sodium hydroxide solution would leak. For this reason, there has been a problem that a hydrogen permeation test using a concrete specimen cannot be carried out.

[0008] The present invention has been made in view of the above circumstances, and an object thereof is to provide a concrete specimen capable of preventing permeation of a sodium hydroxide solution, a method for manufacturing the concrete specimen, and a method for measuring the amount of hydrogen that penetrates into the metal in the concrete specimen.

Means for Solving the Problems

[0009] A concrete specimen according to one aspect of the present invention includes concrete having a planar first surface, a metal embedded in the first surface, and a metal film formed on the first surface including the metal.

[0010] A method for manufacturing a concrete specimen according to one aspect of the present invention includes a step of cutting a concrete block in which a metal is embedded inside the concrete with a plane including the metal to generate a concrete piece, and a step of forming a metal film on the metal and the concrete on the cut surface of the concrete piece.

[0011] A method for measuring the amount of hydrogen in one aspect of the present invention is a measurement method for measuring the amount of hydrogen that penetrates into the metal of the above-described concrete specimen, comprising dipping the first surface of the concrete into a sodium hydroxide solution, disposing the second surface opposite to the first surface in an outdoor environment, detecting a current flowing in the sodium hydroxide solution, and calculating the amount of hydrogen that penetrates into the metal based on the detected current.

Advantages of the Invention

[0012] According to the present invention, it becomes possible to measure the amount of hydrogen that penetrates into the metal in the concrete specimen by preventing the permeation of the sodium hydroxide solution.

Brief Description of the Drawings

[0013]

Figure 1A

Figure 1B

Figure 1C

Figure 2A

Figure 2B

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0014] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The concrete specimen according to this embodiment is manufactured by cutting a concrete block with a metal embedded therein along a plane including the metal to generate a concrete piece, and forming a metal film such as nickel or palladium on the cut surface of the concrete piece. The surface of the concrete specimen on which the metal film is formed is defined as the hydrogen detection surface (the first surface described later), and the surface on the opposite side of the hydrogen detection surface is defined as the hydrogen intrusion surface (the second surface described later), and the specimen is installed in a test apparatus to measure the amount of hydrogen that penetrates into the metal. This will be described in detail below.

[0015] FIG. 1A is a cross-sectional view of a concrete block with a metal embedded therein, FIG. 1B is an explanatory view showing a cut surface L1 when cutting the concrete block to create a concrete specimen, and FIG. 1C is a cross-sectional view of the concrete piece obtained by cutting the concrete block along the cut surface L1. FIG. 2A is an explanatory view showing the process of forming a metal film on the cut surface of the concrete piece, and FIG. 2B is an explanatory view showing the concrete specimen formed by forming the metal film.

[0016] Hereinafter, with reference to FIGS. 1A, 1B, 1C, 2A, and 2B, the procedure of the manufacturing method of the concrete specimen according to the embodiment will be described.

[0017] First, as shown in FIG. 1A, a concrete block 41 with a metal 12 embedded inside the concrete 11 is prepared. The metal 12 is, for example, iron (Fe). Note that FIG. 1A shows an example using a concrete block 41 in which the entire periphery of the metal 12 is covered with the concrete 11, but the concrete block 41 only needs to have at least a part of the metal 12 covered with the concrete 11. Also, in FIG. 1A, the metal 12 and the concrete 11 have a rectangular parallelepiped shape, but other shapes may be used instead of the rectangular parallelepiped.

[0018] Next, as shown in FIG. 1B, a planar cut surface L1 including the metal 12 is set on the concrete block 41, and the concrete block 41 is cut along this cut surface L1. As a result, as shown in FIG. 1C, a concrete piece 41a obtained by dividing the concrete block 41 into two is generated. That is, the concrete piece 41a has a shape in which the metal 12 is exposed at the center and the periphery thereof is covered with the concrete 11.

[0019] As shown in FIG. 2A, the concrete piece 41a shown in FIG. 1C is inserted into the vacuum chamber 31, and a metal film is formed on the surfaces of the metal 12 and the concrete 11 by a vacuum evaporation method. For the metal film, for example, nickel (Ni) and palladium (Pd) may be used.

[0020] Specifically, a metal such as nickel (Ni) or palladium (Pd) is placed on the evaporation source 32, and the metal is heated to evaporate in the vacuum chamber 31, thereby forming a metal film on the surfaces of the metal 12 and the concrete 11. Note that the method for forming the metal film is not limited to the vacuum evaporation method, and other film formation methods such as sputtering and CVD method may be used.

[0021] As a result, as shown in FIG. 2B, a concrete specimen 10 (hereinafter abbreviated as "specimen 10") in which the metal 12 is embedded in the surface of the concrete 11 and a metal film 13 is formed on the surfaces of the concrete 11 and the metal 12 is generated. Hereinafter, the surface of the specimen 10 on which the metal film 13 is formed (the lower surface of the specimen 10 shown in FIG. 2B) is referred to as the first surface, and the surface opposite to the first surface (the upper surface of the specimen 10 shown in FIG. 2B) is referred to as the second surface.

[0022] That is, the concrete specimen 10 according to the present embodiment is composed of the concrete 11 having a planar first surface, the metal 12 embedded in the first surface, and the metal film 13 formed on the first surface including the metal 12.

[0023] Further, the concrete specimen 10 according to the present embodiment is manufactured by a step of cutting a concrete block 41 in which a metal 12 is embedded inside the concrete 11 with a plane including the metal 12 to generate a concrete piece 41a, and a step of forming a metal film 13 on the metal 12 and the concrete 11 on the cut surface of the concrete piece 41a.

[0024] In the present embodiment, the amount of hydrogen that penetrates into the metal 12 is measured using the specimen 10 manufactured by the above procedure. Hereinafter, the method for measuring the amount of hydrogen will be described.

[0025] FIG. 3 is an explanatory diagram schematically showing a measuring device used for measuring the amount of hydrogen. As shown in FIG. 3, the measuring device 100 includes a first cell 23, a second cell 24, a first current detector 21, a second current detector 22, and a fixture 28.

[0026] The inside of the first cell 23 is an environment where hydrogen penetrates. The inside of the first cell 23 is, for example, an outdoor environment. The outdoor environment is an environment of outside air having arbitrary temperature and humidity.

[0027] The inside of the second cell 24 is filled with a sodium hydroxide solution 14.

[0028] The specimen 10 is installed at the connection part between the first cell 23 and the second cell 24 and is hermetically fixed by the fixture 28. The specimen 10 is arranged such that the first surface is exposed to the second cell 24 side and the second surface is exposed to the first cell 23 side. That is, the first surface of the specimen 10 is immersed in the sodium hydroxide solution 14.

[0029] The first current detector 21 is connected to a reference electrode RE1, a counter electrode CE1 provided in the first cell 23, and a sample electrode WE connected to the specimen 10. The first current detector 21 measures the current flowing in the first cell based on the voltages generated in each of the electrodes RE1, CE1, and WE.

[0030] The second current detector 22 is connected to a reference electrode RE2, a counter electrode CE2 provided in the second cell 24, and a sample electrode WE connected to the specimen 10. The second current detector 22 measures the current flowing through the sodium hydroxide solution 14 filled in the second cell based on the voltages generated at each of the electrodes RE2, CE2, and WE.

[0031] FIG. 4 is an explanatory diagram showing how the first surface of the specimen 10 is in contact with the sodium hydroxide solution 14.

[0032] As shown in FIG. 4, a metal film 13 is formed on the surfaces of the metal 12 and the concrete 11 that constitute the specimen 10. That is, a metal film 13 such as a nickel film or a palladium film is formed on the first surface of the specimen 10. The nickel film and the palladium film do not permeate the sodium hydroxide solution 14. Therefore, the sodium hydroxide solution 14 filled in the second cell 24 does not permeate the concrete 11. Accordingly, leakage of the sodium hydroxide solution 14 to the first cell 23 side can be prevented.

[0033] Next, the principle of measuring the hydrogen amount by the above-described measuring device 100 will be described. As shown in FIG. 3, the second surface of the specimen 10 (the left surface in FIG. 4) is exposed to the outdoor environment in the first cell 23.

[0034] A part of the hydrogen present in the first cell 23 penetrates into the concrete 11 from the second surface of the specimen 10 and reaches the surface of the metal 12 (the left surface in FIG. 4). Further, a part of the hydrogen that has reached the surface of the metal 12 penetrates into the metal 12 and diffuses, reaching the first surface of the metal 12 (the right surface in FIG. 4).

[0035] The hydrogen that has reached the first surface is ionized in the sodium hydroxide solution 14, and electrons are released by the ionization reaction. The second current detector 22 measures the current flowing through the sodium hydroxide solution 14.

[0036] Based on the current measured by the second current detector 22, the amount of hydrogen that has penetrated into the metal 12 of the specimen 10 can be calculated.

[0037] In this way, using the concrete specimen 10 that simulates a reinforced concrete structure, the amount of hydrogen that penetrates into the metal (reinforcing bar) embedded in the concrete can be measured.

[0038] As described above, the concrete specimen 10 according to this embodiment includes concrete 11 having a planar first surface, a metal 12 embedded in the first surface, and a metal film 13 formed on the first surface including the metal 12.

[0039] In the concrete specimen 10 according to this embodiment, since the metal film 13 is formed on the first surface which is the hydrogen detection side surface, when measuring the amount of hydrogen using the measuring device 100, it is possible to prevent the sodium hydroxide solution 14 filled in the second cell 24 from permeating through the concrete 11 and leaking to the first cell 23 side.

[0040] Therefore, it is possible to easily measure the amount of hydrogen in the metal embedded in concrete, such as a reinforced concrete structure. According to this embodiment, it becomes possible to non-invasively measure the corrosion state of the reinforcing bars embedded in the concrete.

[0041] Also, in the concrete specimen 10 according to this embodiment, since nickel (Ni) or palladium (Pd) is used as the metal film formed on the surface of the concrete 11, it is possible to more reliably prevent the leakage of the sodium hydroxide solution 14. Furthermore, by forming a nickel or palladium film as the metal film, it becomes possible to improve the detection sensitivity of hydrogen.

[0042] Also, in this embodiment, a method of forming the metal film 13 on the surfaces of the concrete 11 and the metal 12 by a vacuum evaporation method or the like is adopted. Therefore, since a method of forming a metal film such as nickel or palladium by plating is not adopted, the problem of the plating solution penetrating into the concrete can be avoided.

[0043] Note that the present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the gist thereof.

Explanation of Reference Numerals

[0044] 10 Concrete Specimen 11 Concrete 12 Metal 13 Metal Film 14 Sodium Hydroxide Solution 21 First Current Detector 22 Second Current Detector 23 First Cell 24 Second Cell 28 Fixture 31 Vacuum Chamber 32 Evaporation Source 41 Concrete Block 41a Concrete Piece 100 Measuring Device

Claims

1. Concrete having a planar first surface, metal embedded in the first surface, a metal film formed on the first surface including the metal, and a concrete specimen provided with the same.

2. The metal film contains nickel or palladium. The concrete specimen according to Claim 1.

3. A step of cutting a concrete block having metal embedded therein with a plane including the metal to generate a concrete piece, and a step of forming a metal film on the metal and the concrete on the cut surface of the concrete piece. A method for manufacturing a concrete specimen provided with the same.

4. The step of forming the metal film forms the metal film by a vacuum evaporation method. The method for manufacturing a concrete specimen according to Claim 3.

5. The metal film contains nickel or palladium. The method for manufacturing a concrete specimen according to Claim 3 or 4.

6. A measurement method for measuring the amount of hydrogen that penetrates into the metal of the concrete specimen according to Claim 1 or 2, wherein a step of immersing the first surface of the concrete in a sodium hydroxide solution, disposing a second surface opposite to the first surface in an outdoor environment, and detecting a current flowing in the sodium hydroxide solution, and a step of calculating the amount of hydrogen that penetrates into the metal based on the detected current. A measurement method for the amount of hydrogen provided with the same.

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