Visual tracer agent for deep tip of 0.01 mm-grade concrete crack and use method of visual tracer agent

Abstract

The invention discloses a 0.01 mm grade concrete crack deep tip visual tracer agent and a use method thereof. The visual tracer agent is formed by mixing liquid nano glue and a graphene oxide aqueous solution; wherein the volume ratio of the liquid nano glue to the graphene oxide aqueous solution is (7.5-8.5): (2.5-1.5), and the mass volume concentration of the graphene oxide aqueous solution is 15-20 mg / ml. The visual tracer agent prepared by the invention has the characteristics of excellent dielectric property, low viscosity, strong flowability, high permeability and the like. Based on the visual tracer agent, the invention further provides a method for detecting the depth of the hidden crack of the 0.01 mm-level concrete by using the visual tracer agent, so that the industrial problem that the depth of the hidden crack of the concrete with the width smaller than 0.05 mm cannot be detected is solved; in addition, the visual tracer agent can also be used for depth detection of macroscopic and microscopic cracks with the width of 0.1 mm or above.

Description

Technical Field

[0001] This invention belongs to the field of technology for detecting the location of the deep tip of hidden cracks in concrete structures, and specifically relates to a 0.01mm-level visual tracer for the deep tip of concrete cracks and its application method. Background Technology

[0002] Cracks are a major driving force behind concrete structural accidents, and crack depth is a decisive indicator of potential engineering disasters. Hidden cracks of 0.01 mm (cracks with a width of 0.01–0.09 mm) represent the nascent stage of large-scale macroscopic cracks. Although the opening width of hidden cracks is small, the properties of concrete dictate that hidden cracks under load generally possess a certain depth. Cracks of a certain depth not only directly impair the structural bearing capacity but also act as pathways for environmental corrosion extending into water-contaminated concrete structures, accompanied by steel reinforcement corrosion. The deeper the crack, the faster the structural bearing capacity decreases, and the risk of structural disaster due to cracking cannot be ignored. Therefore, determining the location of the deep tip of the crack is crucial for structural safety.

[0003] For detecting the deep tips of macroscopic cracks wider than 0.2 mm, ultrasonic methods are commonly used. However, ultrasonic methods suffer from low accuracy when detecting the tips of macroscopic cracks narrower than 0.05 mm. In recent years, new detection methods have been reported, such as the tracer and its application method disclosed in Chinese Patent (Application No.: CN202410114867.3) for radar tracing detection of concrete crack depth. This method involves mixing nano-adhesive with metal powder, then injecting the mixture into the depth of the crack, and combining it with radar waves for detection. However, this method is limited by the availability of metal powder and can only detect cracks with a width between 0.1 and 0.2 mm, failing to detect deep hidden cracks narrower than 0.05 mm.

[0004] Research has revealed two key challenges for deep detection of hidden cracks less than 0.05 mm wide: first, the difficulty of filling the extremely narrow crack cavity, where current techniques using metal powder and nanogels to form a suspended liquid are insufficient; and second, the challenge of effectively reflecting subsequent incident radar waves after the tracer has been injected into the cavity, given the small tracer dosage. Therefore, the development of a liquid tracer with superior dielectric properties and fluidity is required to overcome these challenges.

[0005] Type I nanogels (hereinafter referred to as liquid nanogels) are specifically inorganic aqueous nano-permeable crystalline material solutions with a solid content of 10%–30% and a density of 1.05–3.05 g / cm³. 3 Viscosity ≤11mPa.s. Summary of the Invention

[0006] In view of the problems existing in the background technology, the purpose of this invention is to provide a 0.01mm-level concrete crack deep tip visualization tracer and its application method.

[0007] The first aspect of the present invention provides a 0.01 mm-level visualization tracer for the deep tip of concrete cracks, which is composed of a mixture of liquid nano-adhesive and graphene oxide aqueous solution; wherein the volume ratio of the liquid nano-adhesive to the graphene oxide aqueous solution is (7.5-8.5):(2.5-1.5), and the mass-volume concentration of the graphene oxide aqueous solution is 15-20 mg / ml.

[0008] Preferably, the degree of oxidation of the graphene oxide is 30% to 60%, and the thickness of a single layer of graphene oxide is 0.6 to 1 nm.

[0009] A second aspect of the present invention provides a method for using the aforementioned 0.01mm grade concrete crack deep tip visualization tracer, comprising the following steps:

[0010] S1. Add the aqueous solution of graphene oxide to the liquid nanogel and stir to mix evenly to obtain a visual tracer;

[0011] S2. Inject a visual tracer into the deep part of the concrete crack. During the injection process, use radar electromagnetic waves to track the migration of the visual tracer in the concrete hidden crack cavity. After the visual tracer reaches the tip of the hidden crack for 2-5 minutes, use radar electromagnetic waves to detect it and obtain the depth of the concrete hidden crack in the range of 0.01 mm.

[0012] Preferably, in step S1, the stirring speed is 60-100 rpm and the stirring time is 1-2 min.

[0013] Preferably, in step S2, the frequency of the electromagnetic radar wave is 1.6 to 2.6 GHz.

[0014] The present invention has the following beneficial effects:

[0015] (1) The present invention prepares a (liquid) visual tracer by mixing liquid nanogel (Type I nanogel with a dielectric constant of about 110) with a certain concentration of graphene oxide aqueous solution. The visual tracer has the characteristics of excellent dielectric properties, low viscosity, strong fluidity and high permeability.

[0016] (2) The present invention also provides a method for detecting the depth of 0.01 mm-level hidden cracks in concrete using a visual tracer, which realizes the depth detection of concrete cracks with a width of 0.01 mm, especially 0.01 to 0.05 mm, and solves the industry problem that the existing technology cannot detect the depth of hidden cracks in concrete with a width of less than 0.05 mm. In addition, the method can also be used for the depth detection of macroscopic and microscopic cracks with a width of more than 0.1 mm. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 Images of the visualization tracer prepared in Example 1;

[0019] Figure 2 Images of the concrete structure to be tested;

[0020] Figure 3 This is a process diagram of using the visual tracer (prepared in Example 1) to detect concrete structures in Experiment Example 1;

[0021] Figure 4 For the depth detection of cracks after injection of the visualization tracer (prepared in Example 1) in Test Example 1;

[0022] Figure 5 This is an image of the concrete structure at an actual detection depth of 22.5 cm in Experiment Example 1;

[0023] Figure 6 This is a process diagram of using the visual tracer (prepared in Example 2) to detect concrete structures in Experiment Example 2;

[0024] Figure 7 The depth detection results of the crack after the injection of the visualization tracer (prepared in Example 2) in Test Example 2;

[0025] Figure 8 This is an image of the concrete structure at an actual detection depth of 52.5 cm in Experiment Example 2;

[0026] Figure 9 The results of crack depth detection after injecting tracer (prepared in Comparative Example 1) in Test Example 3 (a) and a photograph (b) after the tracer reaches the tip of the deep crack.

[0027] Figure 10 The depth detection results of the crack after injecting the tracer (prepared in Comparative Example 2) in Experiment Example 4;

[0028] Figure 11 This is an image showing the tracer reaching the tip of the deep hidden crack in Experiment Example 4;

[0029] Figure 12The images show the depth of the crack after the tracer (prepared in Comparative Example 3) was injected in Experimental Example 5 (a) and the image after the tracer reached the tip of the deep crack (b). Detailed Implementation

[0030] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of the invention. However, those skilled in the art will understand that the invention may be implemented in other embodiments without these specific details.

[0031] Example 1

[0032] Preparation of the visualization tracer: Liquid nanogel (commercially available) and a 15 mg / ml aqueous solution of graphene oxide (50% oxidation degree, 0.6–1 nm thickness of monolayer graphene oxide) were mixed at a volume ratio of 7.5:2.5 and stirred until homogeneous. The stirring speed was 80 rpm and the stirring time was 2 min to obtain the visualization tracer (see...). Figure 1 ), denoted as sample 1.

[0033] Example 2

[0034] Preparation of the visualization tracer: Liquid nanogel and graphene oxide aqueous solution with a mass-volume concentration of 20 mg / ml were mixed evenly at a volume ratio of 7.5:2.5. The stirring speed was 100 rpm and the stirring time was 1 min to obtain the visualization tracer, which was denoted as sample 2.

[0035] Example 3

[0036] Preparation of the visualization tracer: Liquid nanogel and graphene oxide aqueous solution with a mass-volume concentration of 15 mg / ml (the degree of oxidation of graphene oxide is 30%, and the thickness of monolayer graphene oxide is 0.6-1 nm) were mixed evenly at a volume ratio of 7.5:2.5. The stirring speed was 80 rpm and the stirring time was 2 min to obtain the visualization tracer, which was denoted as sample 3.

[0037] Example 4

[0038] Preparation of the visualization tracer: Liquid nanogel and graphene oxide aqueous solution with a mass-volume concentration of 15 mg / m³ (the degree of oxidation of graphene oxide is 60%, and the thickness of monolayer graphene oxide is 0.6-1 nm) were mixed evenly at a volume ratio of 7.5:2.5. The stirring speed was 80 rpm and the stirring time was 2 min to obtain the visualization tracer, which was denoted as sample 4.

[0039] Comparative Example 1

[0040] Preparation of tracer: The liquid nanogel and the graphene oxide aqueous solution with a mass-volume concentration of 20 mg / ml were mixed evenly at a volume ratio of 6:4. The stirring speed was 100 rpm and the stirring time was 2 min to obtain the tracer, which was recorded as sample 5.

[0041] Comparative Example 2

[0042] Preparation of tracer: The liquid nanogel and the graphene oxide aqueous solution with a mass-volume concentration of 15 mg / ml were mixed evenly at a volume ratio of 9:1. The stirring speed was 80 rpm and the stirring time was 2 min to obtain the tracer, which was recorded as sample 6.

[0043] Comparative Example 3

[0044] Preparation of tracer: Weigh 5g of ferric oxide with a particle size of 5nm to 20nm and add it to 95g of liquid nanogel. Stir and mix evenly at a stirring speed of 300 rpm for 5 minutes to obtain the tracer, which is recorded as sample 7.

[0045] Experimental Example 1

[0046] In concrete structures (see) Figure 2 Cracks with a width of 0.02 to 0.04 mm and a depth of 25 cm were prefabricated in the concrete pier structure to simulate cracking.

[0047] Reference Figure 3 The method for using a 0.1mm-grade visual tracer for the deep tip of concrete cracks is as follows: 15ml of the visual tracer prepared in Example 1 is injected into the deep part of the hidden cracks in the concrete structure. The injection is performed in stages, one-time injections, following the procedure described in Chinese Patent (Application No.: CN202311730568.4), with controlled injection duration. During the injection process, the real-time radar pseudo-color image is observed, tracking the movement of the visual tracer's indicator signal along the concrete crack cavity. When the indicator signal disappears in the radar pseudo-color image, the next stage of indicator injection is performed until the visual tracer reaches the deep tip of the concrete crack. Two to five minutes after the visual tracer reaches the deep tip of the hidden crack, ground-penetrating radar (frequency 2.6GHz) is used for detection. The radar detection results are shown in […]. Figure 4 .

[0048] Depend on Figure 4 The results show that at the actual detection depth of 22.5cm (see...) Figure 5 The presence of a clear reflection signal indicates that this location is the liquid surface of the visualization tracer at the bottom of the crack. This demonstrates that the visualization tracer prepared in Example 1 possesses excellent dielectric properties, low viscosity, strong fluidity, and high permeability. After splitting the crack along the cavity, the final depth of the prefabricated crack in this experimental example was determined to be 24.5 cm, with a detection error of 1.7 cm.

[0049] Experimental Example 2

[0050] In concrete structures (see) Figure 2 Cracks 0.1 mm wide and ~55 cm deep were prefabricated in the concrete pier structure to simulate cracking.

[0051] Reference Figure 6 The method for using a 0.1mm-grade visual tracer for the deep tip of concrete cracks is as follows: Inject 30ml of the visual tracer prepared in Example 2 into the deep part of the hidden crack in the concrete structure, performing a single injection in stages (method as in Example 1), and controlling the injection time. During the injection process, observe the real-time radar pseudo-color image, tracking the movement trajectory of the visual tracer's indicator signal along the concrete crack cavity. After determining that the visual tracer has reached the deep tip of the hidden crack for 2-5 minutes, use ground-penetrating radar (frequency 1.6GHz) for detection. The radar detection results are shown in […]. Figure 7 .

[0052] Depend on Figure 7 The results show that the actual detection depth was 52.5cm at the bottom of the concrete structure (see...). Figure 8 The presence of a clear reflection signal indicates that this location is the surface at the bottom of the crack where the tracer is present. After splitting the crack along the cavity, the depth of the precast crack in this test case was finally determined to be 54 cm, with a detection error of 1.5 cm.

[0053] Experimental Example 3

[0054] In concrete structures (see) Figure 2 Cracks with a width of 0.02 to 0.04 mm and a depth of 55 cm were prefabricated in the pier to simulate cracking of the pier structure.

[0055] The method for using a 0.1mm-grade concrete crack tip visualization tracer is as follows: Inject 30ml of the tracer prepared in Comparative Example 1 into the deep part of the hidden crack in the concrete structure, under the same injection conditions as in Experimental Example 1. Detection is performed using ground-penetrating radar (frequency 1.6GHz). The radar detection results are shown in [Figure 1]. Figure 9 .

[0056] Depend on Figure 9 The results showed that no reflection signal appeared in the obtained radar pseudocolor image. After splitting the crack along the cavity, it was found that the injected tracer accumulated in the upper half of the crack cavity and did not reach the depth of the crack. This may be attributed to the high concentration of graphene oxide, which caused the graphene in the tracer to have a large consistency and accumulate along the surface of the crack cavity during injection, making it difficult to inject to the deep tip of the crack.

[0057] Test Example 4

[0058] In concrete structures (see) Figure 2Cracks with a width of 0.02 to 0.04 mm and a depth of 25 cm were prefabricated in the concrete pier structure to simulate cracking.

[0059] The method for using a 0.1mm-grade concrete crack tip visualization tracer is as follows: Inject 30ml of the tracer prepared in Comparative Example 2 into the deep part of the hidden crack in the concrete structure, under the same injection conditions as in Experimental Example 1. Detection is performed using ground-penetrating radar (frequency 1.6GHz). The radar detection results are shown in [Figure 1]. Figure 10 .

[0060] Depend on Figure 10 The results showed that no reflection signal appeared in the obtained radar pseudo-color image. After splitting the crack along the cavity, it was found that the injected tracer had reached the deep tip of the crack (see...). Figure 11 The analysis suggests that this phenomenon may be due to a low content of graphene oxide in the tracer, resulting in insufficient dielectric properties of the tracer to effectively reflect radar waves at the tracer.

[0061] Experimental Example 5

[0062] In concrete structures (see) Figure 2 Cracks 0.1 mm wide and ~55 cm deep were prefabricated in the concrete pier structure to simulate cracking.

[0063] 30 ml of the tracer prepared in Comparative Example 3 was injected deep into the hidden cracks in the concrete structure under the same injection conditions as in Experimental Example 1. The precast cracks were then re-measured using ground-penetrating radar (1.6 GHz). The radar detection results are shown in [Figure 1]. Figure 12 .

[0064] Depend on Figure 12 The results showed that no reflection signal appeared in the obtained radar pseudocolor image. After splitting the crack along the cavity, it was found that the injected tracer accumulated in the upper half of the crack cavity and did not reach the depth of the crack. This may be attributed to the large particle size of the trimer tetroxide powder, which, during the injection of the 0.1 mm wide crack, accumulated along the crack sidewall and was difficult to inject to the deep tip of the crack.

[0065] This invention is not limited to the specific embodiments described above. Any modifications made by those skilled in the art based on the above concept without creative effort are within the scope of protection of this invention.

Claims

A 1.001mm grade concrete crack deep tip visualization tracer, characterized in that, It is composed of a mixture of liquid nanogel and graphene oxide aqueous solution; wherein the volume ratio of the liquid nanogel to the graphene oxide aqueous solution is (7.5-8.5):(2.5-1.5), and the mass-volume concentration of the graphene oxide aqueous solution is 15-20 mg / ml.

2. The 0.01mm grade concrete crack deep tip visualization tracer according to claim 1, characterized in that, The degree of oxidation of the graphene oxide is 30% to 60%, and the thickness of a single layer of graphene oxide is 0.6 to 1 nm.

3. The method of using the 0.01mm grade concrete crack deep tip visualization tracer as described in claim 1 or 2, characterized in that, Includes the following steps: S1. Add the aqueous solution of graphene oxide to the liquid nanogel and stir to mix evenly to obtain a visual tracer; S2. Inject a visual tracer into the deep part of the concrete crack. During the injection process, use radar electromagnetic waves to track the migration of the visual tracer in the concrete hidden crack cavity. After the visual tracer reaches the tip of the hidden crack for 2-5 minutes, use radar electromagnetic waves to detect it and obtain the depth of the concrete hidden crack in the range of 0.01 mm.

4. The method of using the 0.01mm grade concrete crack deep tip visualization tracer according to claim 3, characterized in that, In step S1, the stirring speed is 60-100 rpm and the stirring time is 1-2 min.

5. The method of using the 0.01mm grade concrete crack deep tip visualization tracer according to claim 3, characterized in that, In step S2, the frequency of the electromagnetic radar wave is 1.6 to 2.6 GHz.

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