JP7369659B2 - Reinforcement corrosion property evaluation method - Google Patents

Description

The present invention relates to a reinforcing steel corrosion property evaluation method.

Structures with reinforcing bars, such as reinforced concrete and reinforced steel concrete, are used for bridges, buildings, and the like. The reinforcing bars and steel frames (hereinafter simply referred to as reinforcing bars) contained inside are used for the purpose of reinforcing the strength of the structure.

Structures with reinforcing bars may suffer damage such as cracks due to the reinforcing bars inside the structure corroding and expanding. Therefore, in order to prevent damage to structures having reinforcing bars due to corrosion of reinforcing bars, it is necessary to diagnose the presence or absence of corrosion of reinforcing bars and the degree of corrosion at an early stage.

Therefore, various inspection techniques for structures having reinforcing bars have been proposed.

Patent Document 1 describes a heating step in which reinforced concrete is heated by electromagnetic induction heating for a predetermined period of time, and a temperature on the surface of the concrete is measured to obtain temperature information on the surface of the concrete that changes over time. The effect of the cavity thickness calculation step, in which the cavity thickness in the concrete is calculated from the difference between the temperature measurement step and the time taken to reach the maximum temperature on the surface of the concrete, and the amount of temperature rise, which decreases depending on the cavity thickness, are removed. The corrected temperature rise calculation step calculates the corrected temperature rise, the maximum temperature of the concrete surface when the reinforcing bars are not corroded, and the maximum temperature rise correction value obtained in the corrected temperature rise calculation step. ``A method for evaluating the corrosion properties of reinforcing steel in reinforced concrete, which consists of a corrosion rate calculation step of calculating the corrosion rate of reinforcing steel using temperature.'' has been proposed.

Patent Document 2 describes, ``a striking part that strikes the surface to be inspected of a structure, a pressing part that adjustably sets a pressing force for pressing the striking surface of the striking part against the surface to be inspected, and a striking part of the striking part. "A hammering sound inspection device for a structure, comprising: a detection section that detects a striking sound generated by the structure; and a processing section that determines the state inside the structure based on a detection signal from the detection section." ing.

Japanese Patent Application Publication No. 2016-191696 JP2019-39787A

As described above, methods for diagnosing the presence or absence of corrosion of reinforcing bars and the degree of corrosion are being considered.
Therefore, the object of the present invention is to create a new reinforcing steel corrosion property evaluation method for diagnosing the presence or absence of corrosion of reinforcing bars and the degree of corrosion. An object of the present invention is to provide a reinforcing steel corrosion property evaluation method for diagnosing the presence or absence of corrosion and the degree of corrosion.

The above problem is solved by the following means. That is <1>
A step (P-1) of hitting the surface of a structure having reinforcing bars;
a step (P-2) of sampling the air around the striking part after the step (P-1);
a step (P-3) of bringing the air into contact with a sebum component and a salt component to obtain a gas containing an odor component;
analyzing the gas containing the odor component and detecting the odor component (P-4);
A step (P-5) of evaluating the presence or absence of corrosion of the reinforcing steel based on the detected amount of the odor component;
A method for evaluating reinforcing steel corrosion properties of a structure having reinforcing bars.
<2>
The method for evaluating reinforcing steel corrosion properties of a structure having reinforcing bars according to <1> above, wherein the sebum component is artificial scale and the salt component is artificial sweat.
<3>
The method for evaluating reinforcing steel corrosion properties of a structure having reinforcing bars according to <1> or <2> above, wherein the step (P-1) is a hammering test.
<4>
A structure having reinforcing bars according to any one of <1> to <3> above, wherein the odor component is at least one compound selected from the group consisting of aldehydes and alkenyl ketones having 7 or more and 10 or less carbon atoms. Evaluation method for reinforcing steel corrosion properties.

According to the present invention, there is a new method for diagnosing the presence or absence of corrosion of reinforcing bars and the degree of corrosion, that is, by analyzing the components in the air after hitting the surface of a structure having reinforcing bars. A method for diagnosing the degree of corrosion is provided.

FIG. 3 is a diagram showing the gas chromatography analysis results of Test Example 1. 3 is a diagram showing the gas chromatography analysis results of Test Example 2. FIG. 3 is a diagram showing the gas chromatography analysis results of Test Example 3. FIG.

Hereinafter, an embodiment that is an example of the present invention will be described. These descriptions and test examples are illustrative of embodiments and do not limit the scope of the invention.
In the numerical ranges described step by step in this specification, the upper limit value or lower limit value described in one numerical range may be replaced with the upper limit value or lower limit value of another numerical range described step by step. good. Further, in the numerical ranges described in this specification, the upper limit or lower limit of the numerical range may be replaced with the value shown in the test example.

Each component may contain multiple types of applicable substances.
When referring to the amount of each component in a composition, if there are multiple types of substances corresponding to each component in the composition, unless otherwise specified, the total amount of the multiple types of substances present in the composition means quantity.

In this specification, the term "process" is used not only to refer to an independent process but also to include any process that is not clearly distinguishable from other processes as long as the intended purpose of the process is achieved. It will be done.

<Reinforcement corrosion property evaluation method>
The reinforcing steel corrosion property evaluation method according to this embodiment is as follows:
A step (P-1) of hitting the surface of a structure having reinforcing bars;
a step (P-2) of sampling the air around the striking part after the step (P-1);
a step (P-3) of bringing the air into contact with a sebum component and a salt component to obtain a gas containing an odor component;
analyzing the gas containing the odor component and detecting the odor component (P-4);
A step (P-5) of evaluating the presence or absence of corrosion of the reinforcing steel based on the detected amount of the odor component;
has.

The reinforcing steel corrosion property evaluation method according to the present embodiment can diagnose the presence or absence of corrosion of reinforcing bars and the degree of corrosion due to the above configuration. The reason is as follows.

The reinforcing steel corrosion property evaluation method according to the present embodiment includes a step (P-1) of hitting the surface of a structure having reinforcing bars (hereinafter sometimes simply referred to as a structure). Through this process, iron oxide in the structure floats in the air via the voids and cracks in the structure.
Furthermore, the reinforcing steel corrosion property evaluation method according to the present embodiment includes a step (P-2) of sampling the air around the striking part after the step (P-1). Through this step, air containing suspended iron oxide is collected.
Next, the reinforcing steel corrosion property evaluation method according to the present embodiment includes a step (P-3) of bringing the air into contact with a sebum component and a salt component to obtain a gas containing an odor component. In this step, the collected iron oxide comes into contact with sebum components and salt components, thereby generating odor components.
Then, a step (P-4) of analyzing the gas containing the odor component and detecting the odor component (P-4), and a step (P-4) of evaluating the presence or absence of corrosion of the reinforcing steel and the degree of corrosion based on the detected amount of the odor component (P-4). 5). Thereby, the presence or absence of corrosion of reinforcing bars and the degree of corrosion can be evaluated.

Therefore, the reinforcing steel corrosion property evaluation method according to the present embodiment can diagnose the presence or absence of corrosion of reinforcing bars and the degree of corrosion.

<Process (P-1)>
The reinforcing steel corrosion property evaluation method according to the present embodiment includes a step (P-1) of hitting the surface of a structure having reinforcing bars.
Through this process, if the reinforcing bars in the structure are corroded, iron oxide will float in the air via the voids and cracks in the structure.

Specifically, step (P-1) includes, for example, a step of hitting the surface of the structure with a hammer.
This process can employ a known process of performing a hammering test on a structure.

<Process (P-2)>
The reinforcing steel corrosion property evaluation method according to the present embodiment includes a step (P-2) of sampling the air around the striking part after the step (P-1).
Through this process, air containing suspended iron oxide is collected.

The process of collecting air is not particularly limited; for example, it may be a process of manually collecting air using a plastic bag, etc., or a process of automatically sucking and collecting air using a pump, etc. .

Here, the area around the striking part refers to an area within a radius of about 1.0 m with the striking part as the center point.

<Process (P-3)>
The reinforcing steel corrosion property evaluation method according to the present embodiment includes a step (P-3) of bringing the air obtained in step (P-2) into contact with a sebum component and a salt component to obtain a gas containing an odor component.
In this step, the collected iron oxide is brought into contact with the salt component together with the sebum component, thereby generating an odor component.

Step (P-3) is not particularly limited, and examples include a method of sealing the air, sebum component, and salt component obtained in step (P-2) in a container.
Further, as the step (P-3), a method may be mentioned in which the air obtained in the step (P-2) is passed through a filter containing sebum components and salt components.

The sebum component herein refers to at least one compound selected from the group consisting of triglycerides such as triolein; squalene; esters such as myristyl octadecylate; and fatty acids such as oleic acid, or a mixture thereof.

The sebum component is preferably a mixture of triglyceride; squalene; esters such as myristyl octadecylate; and fatty acids such as oleic acid.

The above mixture is preferably a mixture of 5 to 50% by mass of triglyceride, 5 to 20% by mass of squalene, 5 to 50% by mass of ester, and 5 to 35% by mass of fatty acid.

Specifically, as the above-mentioned mixture, artificial plaque having the following composition is particularly preferable.

Artificial scale: 45% by mass of oleic acid, 25% by mass of triolein, 20% by mass of cholesterol oleate, 4% by mass of liquid paraffin, 4% by mass of squalene, 2% by mass of cholesterol.

The sebum component may be used after being dissolved in a solvent such as water, alcohol, an alkane having 6 to 12 carbon atoms, and acetone.

When using a sebum component dissolved in a solvent, the content of the sebum component is preferably 50% by mass or more and 99% by mass or less, and 75% by mass or more and 99% by mass or less based on the total mass of the sebum component and the solvent. It is more preferable that it is, and it is even more preferable that it is 90 mass% or more and 99 mass% or less.

The salt component includes at least one compound selected from the group consisting of sodium salt, potassium salt, magnesium salt, hydrochloride, etc., or a mixture thereof.

By bringing the air obtained in step (P-2) into contact with the salt component together with the sebum component, the reaction between the iron oxide and the sebum component can be carried out smoothly, and the odor component can be generated more efficiently.

As the salt component, a mixture of sodium salt and hydrochloride is preferred.

Further, it is preferable that the salt component is dissolved in water and used as an aqueous solution.
When using the salt component dissolved in water, the content of the salt component is preferably 0.1% by mass or more and 5.0% by mass or less based on the total mass of the salt component and water, and 0.3% by mass. % or more and 2.5% by mass or less, and even more preferably 0.5% by mass or more and 1.0% by mass or less.

Specifically, as the aqueous solution, artificial sweat having the following composition is particularly preferable.
Artificial sweat: 99.22% by mass of water, 0.05% by mass of L-histidine hydrochloride (monohydrate), 0.50% by mass of sodium chloride, 0.22% by mass of sodium dihydrogen phosphate (dihydrate) %, sodium hydroxide 0.01% by mass

The odor component is a compound produced by bringing the air obtained in step (P-2) into contact with the sebum component and the salt component.
Examples of the odor component include at least one compound selected from the group consisting of aldehydes and alkenyl ketones (ketones having an alkenyl group).

The number of carbon atoms in the aldehyde and the alkenyl ketone is preferably 7 or more and 12 or less, more preferably 8 or more and 11 or less, and 8 or more and 10 or less, from the viewpoint of improving the accuracy of reinforcing steel corrosion evaluation. It is even more preferable that there be.

The structure of the aldehyde and the alkenyl ketone may be a linear structure, a branched structure, or a cyclic structure.

Specific examples of the aldehyde include n-heptanal, n-octanal, n-nonanal, n-decanal, and the like.
Specific examples of the alkenyl ketone include 1-octen-3-one and 6-methyl-5-hepten-2-one.

<Process (P-4)>
The reinforcing steel corrosion property evaluation method according to the present embodiment includes a step (P-4) of analyzing a gas containing an odor component and detecting the odor component.
In this step, the detected amount of odor components is measured, which serves as a basis for evaluating the presence or absence of corrosion and the degree of corrosion in the next step (P-5).

Step (P-4) is not particularly limited, and includes, for example, a method of detecting odor components using gas chromatography.
Specifically, for example, there is a method in which an arbitrary amount of gas containing odor components obtained in step (P-3) is collected with a syringe, and the gas is injected into a gas chromatography device to detect the odor components. Can be mentioned.
The content of the odor component can be calculated from the peak area when a calibration curve of the odor component is created in advance and measured under the same conditions.

Methods other than gas chromatography may be used to analyze odor components.
Examples include infrared (IR) spectroscopy.

<Process (P-5)>
The reinforcing steel corrosion property evaluation method according to the present embodiment includes a step (P-5) of evaluating the presence or absence of corrosion of reinforcing bars and the degree of corrosion based on the detected amount of odor components.
In this step, the presence or absence of corrosion of the reinforcing bars and the degree of corrosion are evaluated from the detected amount of odor components measured in step (P-4).

Examples of methods for evaluating the presence or absence of corrosion of reinforcing bars include the following method.
Using a structure that is determined in advance to have corroded reinforcing bars, the detected amount of odor components is measured in steps (P-1) to (P-4), and the obtained measured value is used as a reference value. Next, using a structure to evaluate the presence or absence of corrosion of reinforcing bars, the detected amount of odor components is measured using the same procedure. If the detected amount is above the standard value, it is determined that there is corrosion; In such cases, methods to eliminate corrosion may be mentioned.

On the other hand, examples of methods for evaluating the degree of corrosion of reinforcing bars include the following method.
A plurality of structures with different degrees of corrosion of reinforcing bars are prepared, and the detected amount of odor components is measured for each structure in steps (P-1) to (P-4). Then, the measurement results are plotted on a graph with one axis representing the numerical corrosion degree and the other axis representing the detected amount of odor components, to create a calibration curve. Furthermore, the numerically quantified corrosion degree is divided into three or more numerical ranges, from the minimum corrosion degree to the maximum corrosion degree, and is used as an index representing the corrosion degree.
Subsequently, the detected amount of odor components is measured for the structure in which the degree of corrosion of reinforcing bars is to be evaluated through steps (P-1) to (P-4). By substituting the obtained measured values into the calibration curve, a numerical value representing the degree of corrosion is calculated. Then, there is a method of determining the degree of corrosion of the reinforcing bars by determining to which numerical range among the indicators representing the degree of corrosion the numerical value representing the degree of corrosion obtained by measurement corresponds.

(Test example)
It will be shown below that by analyzing odor components generated from iron oxide, it is possible to diagnose the presence or absence of corrosion of reinforcing bars in structures and the degree of corrosion.
Note that the present invention is not limited to these test examples. In the following description, all "parts" and "%" are based on mass unless otherwise specified.

<Test Example 1>
0.4 g of rust pieces of a corroded deformed steel bar, 3 g of artificial plaque (manufactured by Isekyu Co., Ltd.), and 20 mL of artificial sweat solution method A acidic (manufactured by Isekyu Co., Ltd.) were added to a petri dish, and the mixture was allowed to stand for 1 hour. After that, the petri dish containing the rust pieces of the corroded deformed steel bar, artificial plaque, and artificial sweat liquid was placed in a sampling bag with a capacity of 5 L (manufactured by GL Sciences, Inc., Smart Bag PA-A-A-5). After degassing the inside of the bag with a vacuum pump, 1 L of high-purity nitrogen gas was injected into the bag through an integrating flowmeter (FCM4000-3100, manufactured by Cofloc Co., Ltd.). The sampling bag was sealed and left at 20°C for 1 hour. Using a cartridge containing 2,6-DiPhenyl-p-phenylene Oxide (Tenax-TA) (manufactured by GL Sciences, Packed Liner with Tenax60/80), volatile organic compounds contained in 0.5 L of gas in the sampling bag were measured. After collecting it. The cartridge was attached to a gas chromatography device equipped with a multifunctional inlet (OPTIC-4 Multimode GC Inlet, manufactured by ATAS GL International BV), and odor components were measured. The results are shown in Figure 1. As shown in FIG. 1, octanal and 6-methyl-5-hepten-2-one were detected.
Note that 1-octen-3-one is known as one of the odor components generated by the reaction between rust pieces of corroded deformed steel bars, sebum components, and salt components. In this test example, 6-methyl-5-hepten-2-one, which has the same molecular weight as 1-octen-3-one and has a ketone structure with an alkenyl group, was detected. It is thought that 3-one is contained as an odor component.

<Test Example 2>
Odor components were measured in the same manner as in Test Example 1, except that 0.8 g of rust pieces of a corroded deformed steel bar were added.
The results are shown in FIG. As shown in Figure 2, octanal and 6-methyl-5-hepten-2-one were detected.

<Test Example 3>
Odor components were measured in the same manner as in Test Example 1 except that rust pieces of the corroded deformed steel bar were not added.
The results are shown in FIG. As shown in FIG. 3, octanal and 6-methyl-5-hepten-2-one were not detected.

The gas chromatography measurement conditions used in Test Examples 1 to 3 are shown below.
・Gas chromatography measurement conditions Equipment: Shimadzu Corporation, GCMS QP-2010Ultra
Inlet heating desorption temperature, time: 280°C, 3 minutes Cryofocus temperature: -90°C
Capillary column: manufactured by GL Sciences, Inc., Inert Cap Pure WAX (length: 30 m, inner diameter: 0.25 mm, film thickness: 0.25 μm)
Column tank temperature: Hold at 40°C for 1 minute → Increase temperature to 240°C at 12.5°C/min Carrier gas: Ultra-high purity helium, 4mL/min
Interface temperature: 230℃
Ion source temperature: 240℃
Scan range: m/z 30-350

The above results show that by analyzing the odor components generated from the rust pieces of the corroded deformed steel bar, it is possible to diagnose the presence or absence of corrosion and the degree of corrosion in the reinforcing bars of a structure.

Claims (4)

A step (P-1) of hitting the surface of a structure having reinforcing bars;
a step (P-2) of sampling the air around the striking part after the step (P-1);
a step (P-3) of bringing the air into contact with a sebum component and a salt component to obtain a gas containing an odor component;
analyzing the gas containing the odor component and detecting the odor component (P-4);
A step (P-5) of evaluating the presence or absence of corrosion of the reinforcing steel based on the detected amount of the odor component;
A method for evaluating reinforcing steel corrosion properties of a structure having reinforcing bars. 2. The method for evaluating corrosion properties of reinforcing bars of a structure having reinforcing bars according to claim 1, wherein the sebum component is artificial grime and the salt component is artificial sweat. The method for evaluating corrosion properties of reinforcing bars of a structure having reinforcing bars according to claim 1 or 2, wherein the step (P-1) is a hammering test. The structure having reinforcing bars according to any one of claims 1 to 3, wherein the odor component is at least one compound selected from the group consisting of aldehydes and alkenyl ketones having 7 to 10 carbon atoms. Reinforcement corrosion property evaluation method.