Marking agent and marking method

Abstract

To provide a marking agent that has a color distinct from concrete, does not give a negative impression, maintains marking effectiveness for a certain period, and does not adversely affect human health or the environment.SOLUTION: A marking agent comprises a humic substance and marks a concrete material, wherein: it is preferable that a solid content of the humic substance is 3 mass% or more; and it is preferable that the humic substance is one or more selected from the group consisting of fulvic acid, humic acid, and humin.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a marking agent and a marking method for concrete materials.

Background Art

[0002] In 2014, the Ministry of Land, Infrastructure, Transport and Tourism made it mandatory to conduct inspections of tunnels, bridges, etc. by close visual inspection once every five years. However, conducting inspections of a huge number of tunnels and bridges by human close visual inspection involves a great deal of labor and huge costs. Such a situation has become a major social issue in the construction industry where the shortage of manpower and financial difficulties are becoming serious. On the infrastructure aging countermeasure portal site of the Ministry of Land, Infrastructure, Transport and Tourism, statistical values are summarized as "the current situation and future of the aging of social capital". Based on the figures for 2023, it is calculated that approximately 40% of the 730,000 road bridges and approximately 30% of the 11,000 tunnels are aging.

[0003] In view of such a situation, it is urgent to develop an efficient inspection method to replace the close visual inspection that relies on manpower. A typical example is inspection by drone. Efforts are accelerating to use drones to photograph high places and places that are difficult to access, and to combine image analysis and AI to streamline the inspection work. The width of cracks, etc. can also be accurately grasped.

[0004] On the other hand, from the inspection results, it is necessary to repair the parts that are actually significantly deteriorated, and it is necessary to mark (mark) those parts so that they can be visually confirmed from a distance by a human. Even if the inspection can be carried out by drone, the repair work needs to be done by a person, and in that case, the installation of scaffolding is essential. Since the installation of scaffolding increases costs, it is desirable to install a reasonable scaffolding to the minimum necessary. Therefore, it is important to clearly recognize the repair locations.

[0005] In such cases, as a marking agent for marking concrete, (i) it should be a liquid with good workability, (ii) it should not have an adverse effect on the human body or the environment, (iii) it should be able to maintain the marking effect for a certain period even in an outdoor environment exposed to rain, snow, and wind, etc.

[0006] Conventionally, as agents for marking concrete, magic ink, ink, etc. have been used. However, if a large amount of magic ink is sprayed, there are concerns about adverse effects on people and the environment around. Also, since the main component of ink is carbon, there is no adverse effect on the environment, but due to its jet-black color, it is too conspicuous or gives a bad impression. Also, since the marked area is not always repaired, if it does not disappear, it will simply become a stain.

[0007] Patent Document 1 and Patent Document 2 exemplify methyl blue, methyl red, methyl orange, methyl yellow, methyl violet, etc. as marking agents for concrete.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0009] However, the marking agents in Patent Document 1 and Patent Document 2 are vulnerable to ultraviolet rays and are easily washed away by rain, so they cannot maintain the marking effect for a certain period. Also, there are concerns about their impact on the environment.

[0010] There is a need for a marking agent that has a color distinguishable from concrete, does not give a bad impression, has a marking effect that lasts for a certain period of time, and does not have an adverse effect on the human body or the environment. However, such a marking agent has not been developed at present.

[0011] Therefore, an object of the present invention is to provide a marking agent that has a color distinguishable from concrete, does not give a bad impression, has a marking effect that lasts for a certain period of time, and does not have an adverse effect on the human body or the environment.

Means for Solving the Problems

[0012] As a result of intensive research to achieve the above object, the present inventors have found that the above problems can be solved by a marking agent containing humic substances. The present invention is based on the above findings and has the following gist.

[0013] [1] A marking agent containing humic substances for marking a concrete material. [2] The marking agent according to [1], wherein the solid content concentration of the humic substances is 3% by mass or more. [3] The marking agent for concrete according to [1] or [2], wherein the humic substances are one or more selected from the group consisting of fulvic acid, humic acid, and humin. [4] The marking agent according to any one of [1] to [3], having a pH of 2 to 8. [5] The marking agent according to any one of [1] to [4], wherein the weight average molecular weight of the humic substances is 500 or more. [6] The marking agent according to any one of [1] to [5], wherein the melanic index of the humic substances is 4 or less. [7] A marking method of attaching the marking agent according to any one of [1] to [6] to a concrete material to make a mark. [8] The marking method according to [7], wherein the marking agent is enclosed in a package capable of enclosing a predetermined amount. [9] A marking method according to [7] or [8], which changes the pH of the marking agent to change the visible period of the mark.

Advantages of the Invention

[0014] According to the present invention, it is possible to provide a marking agent that has a color distinguishable from concrete, does not give a bad impression, has a marking effect that lasts for a certain period, and does not have an adverse effect on the human body or the environment.

Embodiments for Carrying Out the Invention

[0015] Hereinafter, a marking agent and a marking method for a concrete material according to an embodiment (this embodiment) of the present invention will be described.

[0016] [Marking Agent] The marking agent according to this embodiment contains humus and is a marking agent for marking a concrete material.

[0017] The concrete of the above-mentioned concrete material refers to cement concrete (cement hardened body, mortar hardened body, concrete hardened body, etc.), asphalt concrete, etc. Also, a mark refers to a symbol, sign, mark, logo, design, etc. made by a human and used to indicate a certain meaning or concept.

[0018] As a marking agent for marking concrete, as described above, magic ink, ink, etc. have been used, but these may have an adverse effect on the surrounding people and the environment, or may be too conspicuous due to their jet-black color, resulting in a bad impression. To address such problems, in this embodiment, by including humus in the marking agent, it is possible to have a color distinguishable from concrete, not give a bad impression, have a marking effect that lasts for a certain period, and not have an adverse effect on the human body or the environment.

[0019] The humic substances referred to in this embodiment are a general term for "organic substances with undefined chemical structures (non-living organic substances)" that are generated when organic substances in organisms decay under microbial and chemical actions after the death of organisms. Humic substances are generally classified into three types: "humic acid", "fulvic acid", and "humin" based on their solubility in alkalis and acids. Humic acid is defined as a component that is soluble in alkalis but insoluble in acids, fulvic acid is a component that is soluble in both alkalis and acids, and humin is a component that is insoluble in both alkalis and acids.

[0020] Humic substances exist in nature and also in soil. The fact that soil appears black to brown is due to the presence of humic substances. Also, humic substances are included in skin care products and health foods and are known to have no adverse effects on the human body. Furthermore, they are also known as the main components of fertilizer products and biostimulant products and have no adverse effects on the environment or plants.

[0021] Although products industrialized as solids or liquids are sold as humic substances, in the present invention, for the purpose of being used as a concrete marking agent, it is desirable to apply a liquid product from the viewpoint of being able to be painted or sprayed.

[0022] The concentration of humic substances in the marking agent is not particularly limited, but it is preferably 3% by mass or more in terms of the solid content concentration of humic substances, and more preferably 5 to 20% by mass. By having a solid content concentration of 3% by mass or more, the marking effect (any one of color tone, residual property, and visibility) can be sufficiently exhibited. Note that among commercially available humic substances, there are those with a high solid content concentration, but they can also be diluted and used within the range where the solid content concentration is 3% by mass or more.

[0023] In this embodiment, the humic substances are not particularly limited, and it is preferable that they are one or more selected from the group consisting of fulvic acid, humic acid, and humin. Generally, fulvic acid has a small molecular weight. When it is the main component, the color when applied to concrete is yellowish brown, and the marking effect lasts for about one week. Humic acid has a larger molecular weight than fulvic acid. When a marking agent mainly composed of this is applied to concrete, the color becomes dark brown, and the marking effect lasts for more than one month. Thus, humic substances can be selected according to the purpose.

[0024] The pH of the marking agent is preferably 2 to 8, and more preferably 3 to 7. When the pH is 2 to 8, it does not have an adverse effect on the concrete, and a marking effect can be obtained. The pH can be adjusted to a desired range by adding an acid or an alkali, etc. The pH can be measured by the method described in the examples.

[0025] Also, the weight average molecular weight of the humic substance is preferably 500 or more, and more preferably 500 to 5,000. When the weight average molecular weight is 500 or more, the visibility is improved, and the persistence can be ensured for 3 days or more. The weight average molecular weight can be measured by the method described in the examples.

[0026] From the viewpoint of improving visibility and also from the viewpoint of ensuring persistence for 3 days or more, the melanic index (MI) of the humic substance is preferably 4 or less, and more preferably 1.4 to 4.0.

[0027] Here, MI is an index used for the classification of soil humic acid, and is the ratio of absorbances (A450 / A520) at wavelengths 450 nm and 520 nm of the absorption spectrum of the sodium hydroxide extract (written by Koichi Kumada, Chemistry of Soil Organic Matter, 2nd Edition, The Chemical Society of Japan Press (1981), Japanese Journal of Soil Science and Plant Nutrition, Vol. 71, No. 1, pp. 82 - 85 (2000)). Specifically, it can be measured by the method described in the examples.

[0028] MI can be prepared by increasing or decreasing the amount of nitric acid during the production of the crude humic acid product. Increasing the amount of nitric acid added increases MI. Also, it has been found that when MI is 2.4 or more, the low molecular weight and solubility of the humic substances are improved. Therefore, by considering MI, it is possible to evaluate the physical properties without performing complicated analysis operations such as measuring the weight average molecular weight of the humic substances, and a humic acid extract suitable for this embodiment can be obtained.

[0029] [Marking Method] The marking method according to this embodiment is a method of attaching a marking agent to a concrete material to make a mark. It is preferable that the marking agent is enclosed in a package capable of enclosing a predetermined amount.

[0030] When attaching the marking agent of this embodiment to concrete, the method is not particularly limited. For example, it can be sprayed with a spray, painted with a brush or a pen. Also, it can be used in the form of a capsule or a gel ball that breaks when thrown, or enclosed in a package such as a portion container known by the product name "Pakitte". A spray, injection, throwing of a capsule or a gel ball, and a portion container known by the product name "Pakitte" can also be used by mounting them on a drone.

[0031] The concrete marking agent of the present invention, after being applied to the concrete surface, gradually becomes thinner as it is washed away by rain, wind, and snow, but can be visually recognized for a certain period of time. This is because, in view of the interval from the inspection (marking) of the concrete structure until the actual repair work is carried out, it is desirable that the marking effect lasts for several months to about one year and then gradually disappears.

[0032] The concrete surface after marking with humus shows a brown color. A color that can be distinguished from gray concrete and yet has no sense of incongruity is desirable, and brown is a desirable color from this perspective. Rust juice derived from steel bars often adheres to concrete structures, and this is because brown is familiar from daily experience.

[0033] In this embodiment, it is preferable to change the pH of the marking agent to change the visual recognition period of the above mark. For example, when the pH is about 2, the remaining period can be set short. Also, when the pH is further increased to about 8, the visibility is enhanced and the remaining period can be set long.

Example

[0034] Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to these examples.

[0035] Each of the marking agents A to F shown in Table 1 below was applied to a concrete plate of 300×300×50 mm using a pen to mark a circle with a diameter of about 20 cm and a width of about 3 cm. For each marking agent, the following measurements were made: humic acid solid content concentration, pH, weight average molecular weight, and melanic index (MI), and these are also shown in Table 1. Note that marking agents A to D are commercially available products. Marking agent E is commercially available ink and the active ingredient is carbon. Also, marking agent F is a reagent methylene blue indicator.

[0036] (Humus solid content concentration) The humic acid solid content concentrations in marking agents A to D were calculated by the following method. First, the total organic carbon concentration (hereinafter referred to as TOC) was measured by the combustion catalytic oxidation method using a total organic carbon analyzer (TOC-L manufactured by Shimadzu Corporation). In addition, hydrochloric acid was added to the marking agent to adjust the pH of the marking agent to 1.0, and then centrifuged at 5,000×g for 10 minutes to precipitate humic acid from the marking agent. Fulvic acid was quantified by measuring the TOC of the supernatant excluding the precipitate of humic acid. For humic acid, the TOC of humic acid was calculated by subtracting the TOC measurement value of fulvic acid from the TOC measurement value of the marking agent. The humic substance solid content concentration was calculated by multiplying these TOCs by a coefficient. Generally, there is a strong correlation between TOC and the amount of humic substances, which varies depending on the type of lignite used as the raw material, etc., but the amount of humic substances can be estimated to be 1.4 to 2.0 times the amount of TOC. The humic acid solid content concentration was calculated by multiplying the TOC of humic acid by a coefficient of 1.7. Also, the fulvic acid solid content concentration was calculated by multiplying the TOC of fulvic acid by a coefficient of 2.0.

[0037] (Measurement of pH) The pH measurement was carried out by the glass electrode method. Each marking agent was measured at 20°C while stirring with a magnetic stirrer.

[0038] (Weight-average molecular weight) The weight-average molecular weight of the humic substances was measured by the HPSEC method (GPC method) using an ACQUITY APC Syetem manufactured by Waters. As the columns, an ACQUITY UPLC Protein BEH SEC Column, 2.5μm, 4.6mm×150mm and an ACQUITY UPLC Protein BEH SEC Column, 1.7μm, 4.6mm×150mm were connected and used. Sodium polystyrene sulfonate was used as the standard sample, and the detection wavelength was set to 260nm. The mobile phase was a 100mmol / L sodium phosphate buffer containing 20% by mass of acetonitrile, the flow rate was 0.3ml / min, and the column temperature was set to 40°C (the set value of the column oven).

[0039] [Melanic Index (MI)] Marking agents A to D were diluted with pure water and 0.5 mol / L sodium hydroxide aqueous solution to pH 12, and the absorbance at 450 nm and the absorbance at 520 nm were measured with pure water as a blank. At this time, if the absorbance at 450 nm showed 1.0 or more, 0.1 mol / L sodium hydroxide aqueous solution was added to adjust the absorbance to 0.8 or more and less than 1.0, and then the absorbance at 520 nm was measured. The ratio of "absorbance at 450 nm / absorbance at 520 nm" was calculated and designated as MI.

[0040] The color of the concrete surface immediately after marking was observed, and the surface having the mark on the outdoor square was exposed so as to be exposed, and the durability of the marking effect was confirmed. The results are also shown in Table 1.

[0041]

Table 1

[0042] As the observation results of the colors in Table 1 above, A is dark brown with good visibility and very good without any discomfort when marking on concrete, B is slightly light brown with some discomfort but good, and C is jet black and shows discomfort when marking on concrete and is not good. Since the concrete is a so-called earth color, it is considered that the marking agent is also compatible with the earth color. Note that the earth color is a general term for colors from brown to green that image natural objects such as the earth and plants on the earth.

[0043] The marking agent of this example is brown with no discomfort in color, and it can be seen that the marking effect is maintained for a certain period while gradually becoming thinner after exposure. On the other hand, when ink is used as the marking agent, a jet black color with discomfort adheres for a long time. In addition, with methylene blue, the color is also a fluorescent blue with a color that causes discomfort, and it disappears after exposure, and it can be seen that not only the marking effect is not maintained, but it also affects the environment.

Claims

1. A marking agent containing humus and used for marking a concrete material.

2. The marking agent according to Claim 1, wherein the solid content concentration of the humus is 3% by mass or more.

3. The concrete marking agent according to Claim 1 or 2, wherein the humus is one or more selected from the group consisting of fulvic acid, humic acid, and humin.

4. The marking agent according to Claim 1 or 2, having a pH of 2 to 8.

5. The marking agent according to Claim 1 or 2, wherein the weight average molecular weight of the humus is 500 or more.

6. The marking agent according to Claim 1 or 2, wherein the melanic index of the humus is 4 or less.

7. A marking method of attaching the marking agent according to Claim 1 or 2 to a concrete material to make a mark.

8. The marking method according to Claim 7, wherein the marking agent is enclosed in a package capable of enclosing a predetermined amount.

9. The marking method according to Claim 7, wherein the pH of the marking agent is changed to change the visible period of the mark.

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