Methods for detecting the degree of corrosion of sleeve joints in prefabricated concrete structures

Abstract

This invention provides a method for detecting the degree of corrosion of sleeve joints in prefabricated concrete structures, comprising the following steps: scanning the projected area of ​​the sleeve on the surface of the concrete component using a concrete resistivity tester; determining whether there is at least one test point within the projected area with a resistivity value less than a preset threshold; if so, the outer wall of the sleeve under test is corroded, and core sampling is performed on the sleeve at the test point with the lowest resistivity value to determine the corrosion rate of the outer wall or the total corrosion rate of the sleeve; otherwise, the outer wall of the sleeve under test is not corroded, and a hole is opened in the grout outlet of the sleeve under test, and an endoscope is inserted into the hole to detect whether the inner wall of the sleeve under test is corroded; if so, core sampling is performed within 20mm below the grout outlet of the sleeve under test to determine the corrosion rate of the inner wall of the sleeve. This invention can achieve a comprehensive understanding of the corrosion status and degree of the sleeve.

Description

Technical Field

[0001] This invention relates to the field of prefabricated buildings, and specifically to a method for detecting the degree of corrosion of sleeve joints in prefabricated concrete structures. Background Technology

[0002] In recent years, prefabricated concrete structures have been widely promoted in my country. Most of their vertical precast components utilize sleeve grouting connections, and the quality of these sleeve joints is crucial to ensuring the overall structural performance. After years of research, my country has systematically solved the problem of detecting and rectifying defects in sleeve grouting, achieving technology patenting, patent standardization, and standard industrialization. However, frontline building inspectors have discovered new problems when using these technologies for on-site inspections: both steel and cast iron sleeves suffer from corrosion, severely affecting the quality of sleeve joints and potentially endangering the overall structural safety. The key first step in addressing this problem is to detect the degree of corrosion of the sleeves. Sleeve joints are concealed works, and both the outer and inner walls of the sleeves are susceptible to corrosion. Corrosion of the outer wall reduces the bond strength between the sleeve and the concrete, while corrosion of the inner wall reduces the bond strength between the sleeve and the grout, both potentially leading to sleeve joint failure. Due to the complexity of the locations where corrosion occurs, there is currently no method that can systematically and simultaneously identify the corrosion occurrence and corresponding degree on the inner and outer walls of the sleeve, thus limiting the assessment of the impact of corrosion on the sleeve joint by technicians. Summary of the Invention

[0003] The purpose of this invention is to provide a method for detecting the degree of corrosion of sleeve joints in prefabricated concrete structures, so as to simultaneously detect the corrosion of the inner and outer walls of the sleeve.

[0004] To achieve the above objectives, the present invention provides a method for detecting the degree of corrosion of a sleeve joint in a prefabricated concrete structure, wherein the sleeve is cast inside the concrete, and the method includes the following steps:

[0005] Step S100: Determine the projection range of the sleeve under test on the surface of the concrete component, and use a concrete resistivity tester to continuously scan and detect from top to bottom or from bottom to top within the projection range to obtain the resistivity value of each detection point within the projection range;

[0006] Step S200: Determine whether there is at least one detection point within the projection range whose resistivity value is less than a preset resistivity threshold;

[0007] If yes, proceed to step S300; otherwise, proceed to step S400.

[0008] Step S300: Determine that the outer wall of the tested sleeve is corroded, and mark the detection point with the smallest resistivity value within the projection range as the target detection point, and then execute step S500;

[0009] Step S400: Determine that the outer wall of the tested sleeve is not corroded, and open a hole in the grout outlet of the tested sleeve. The depth of the hole is greater than the minimum distance between the inner wall of the tested sleeve and the surface of the concrete component. Use an endoscope to insert into the hole and use the endoscope to detect whether the inner wall of the tested sleeve is corroded.

[0010] If the test result shows that the inner wall of the tested sleeve is not corroded, the test on the tested sleeve ends; if the test result shows that the inner wall of the tested sleeve is corroded, step S600 is executed.

[0011] Step S500: Drill core samples on the tested sleeve according to the location of the target detection point to obtain core samples, and determine the outer wall corrosion rate or total corrosion rate of the tested sleeve based on the core samples;

[0012] Step S600: Take a core sample at any position within 20mm below the slurry outlet of the sleeve under inspection to obtain a core sample, and determine the corrosion rate of the inner wall of the sleeve under inspection based on the core sample.

[0013] Optionally, an impact drill may be used to create holes and / or core samples.

[0014] Optionally, the hole may be opened using the impact drill equipped with a solid drill bit, the outer diameter of which is less than 14 mm.

[0015] Optionally, the core sampling on the tested sleeve includes:

[0016] The impact drill with a solid drill bit is used to drill into the concrete until the outer wall surface of the sleeve under test is reached.

[0017] Using the impact drill equipped with a hollow drill bit, core sampling is performed starting from the outer wall surface of the tested sleeve until the entire sleeve wall is drilled through, wherein the outer diameter of the hollow drill bit is less than 12 mm.

[0018] Optionally, the endoscope's probe includes a front-viewing lens and a side-viewing lens.

[0019] Optionally, the step of core sampling on the tested sleeve according to the location of the target detection point to obtain a core sample, and determining the outer wall corrosion rate or total corrosion rate of the tested sleeve based on the core sample, includes:

[0020] If the target detection point is located within 20mm below the slurry outlet of the sleeve under test, core sampling is performed at the position corresponding to the target detection point on the sleeve under test to obtain a first core sample. Based on the first core sample, the outer wall corrosion rate or total corrosion rate of the sleeve under test is determined.

[0021] If the target detection point is located more than 20 mm below the slurry outlet of the sleeve under test, core samples are taken at either the location corresponding to the target detection point or at any location within 20 mm below the slurry outlet of the sleeve under test to obtain a first core sample and a second core sample. The first outer wall corrosion rate or the first total corrosion rate is calculated based on the first core sample, and the second outer wall corrosion rate or the second total corrosion rate is calculated based on the second core sample. The outer wall corrosion rate of the sleeve under test is determined based on the first outer wall corrosion rate and the second outer wall corrosion rate, or the total corrosion rate of the sleeve under test is determined based on the first total corrosion rate and the second total corrosion rate.

[0022] Optionally, determining the outer wall corrosion rate or total corrosion rate of the tested sleeve based on the first core sample includes:

[0023] If the inner wall of the first core sample is corroded, all the rust on the inner and outer walls of the first core sample is removed to obtain the remaining wall thickness of the first core sample, and the total corrosion rate of the tested sleeve is calculated according to the following formula:

[0024] x 总 = (a1-b1) / a1×100%

[0025] In the formula, x 总 The total corrosion rate is given by denoted as a1, where a1 is the original wall thickness of the first core sample and b1 is the remaining wall thickness of the first core sample.

[0026] If the inner wall of the first core sample is not corroded, then all the rust on the outer wall of the first core sample is removed to obtain the remaining wall thickness of the first core sample, and the corrosion rate of the outer wall of the tested sleeve is calculated according to the following formula:

[0027] x 外 = (a² - b²) / a² × 100%

[0028] In the formula, x 外 denoted as the outer wall corrosion rate, a2 as the original wall thickness of the first core sample, and b2 as the remaining wall thickness of the first core sample.

[0029] Optionally, determining the outer wall corrosion rate of the tested sleeve based on the first outer wall corrosion rate and the second outer wall corrosion rate includes:

[0030] If the inner wall of the second core sample is not corroded, then the corrosion rate of the outer wall of the first core sample is taken as the corrosion rate of the outer wall of the tested sleeve.

[0031] If the inner walls of both the first core sample and the second core sample are corroded, the larger of the first total corrosion rate and the second total corrosion rate shall be taken as the total corrosion rate of the tested sleeve.

[0032] Optionally, determining the corrosion rate of the inner wall of the tested sleeve based on the core sample includes:

[0033] All rust residue on the inner wall of the core sample was removed to obtain the remaining wall thickness of the core sample, and the corrosion rate of the inner wall of the tested sleeve was calculated according to the following formula:

[0034] x 内 = (a3-b3) / a3×100%

[0035] In the formula, x 内 a3 is the inner wall corrosion rate, a3 is the original wall thickness of the core sample, and b3 is the remaining wall thickness of the core sample.

[0036] Optionally, the endoscope probe has a diameter of less than 7 mm.

[0037] The method for detecting the degree of corrosion of sleeve joints in prefabricated concrete structures provided by this invention has the following beneficial effects:

[0038] This invention provides a method for detecting the degree of corrosion of sleeve joints in prefabricated concrete structures, comprising: firstly, determining the projection range of the sleeve under test on the surface of the concrete component, and using a concrete resistivity tester to continuously scan and detect from top to bottom or from bottom to top within the projection range to obtain the resistivity value of each detection point within the projection range; then determining whether there is at least one detection point within the projection range with a resistivity value less than a preset resistivity threshold; if so, determining that the outer wall of the sleeve under test is corroded, and marking the detection point with the lowest resistivity value within the projection range as the target detection point, and performing core drilling on the sleeve under test according to the location of the target detection point to obtain a core sample, and determining the... The corrosion rate of the outer wall or the total corrosion rate of the sleeve under inspection is determined. If not, it is determined that the outer wall of the sleeve under inspection is not corroded. A hole is made in the grout outlet of the sleeve under inspection, and the depth of the hole is greater than the minimum distance between the inner wall of the sleeve under inspection and the surface of the concrete component. An endoscope is inserted into the hole to check whether the inner wall of the sleeve under inspection is corroded. If the test result is that the inner wall of the sleeve under inspection is not corroded, the inspection of the sleeve under inspection ends. If the test result is that the inner wall of the sleeve under inspection is corroded, a core sample is taken at any position within 20 mm below the grout outlet of the sleeve under inspection to obtain a core sample. The corrosion rate of the inner wall of the sleeve under inspection is determined based on the core sample. This invention first uses a concrete resistivity tester, taking advantage of the fact that both the structural sleeve and the reinforcing steel are corroded steels, to determine whether the outer wall of the sleeve is corroded by setting a resistivity threshold that corresponds to the condition of the outer wall corrosion. Based on the experience that the grout outlet area is most susceptible to corrosion, an opening is made in the grout outlet, and an endoscope is used to observe whether the inner wall is corroded. Then, to calculate the corrosion rate, a core sampling method is introduced. By drilling core samples from the outer wall of the sleeve, the corrosion rate is determined by comparing the different states before and after corrosion. Through this process, this invention can obtain the corrosion status and corrosion rate of the outer wall of the sleeve, the corrosion status and corrosion rate of the inner wall of the sleeve, and the corrosion status and total corrosion rate of both the outer and inner walls of the sleeve. This allows for the effective identification of severely corroded areas of the sleeve and the precise determination of the degree of corrosion at corresponding locations, making it highly practical. Furthermore, the test results can provide data support for subsequent assessments of the impact of corrosion on the performance of the sleeve joint, indicating a very broad application prospect. Attached Figure Description

[0039] Figure 1 This is a flowchart illustrating a method for detecting the degree of corrosion of sleeve joints in prefabricated concrete structures, provided in an embodiment of the present invention. Detailed Implementation

[0040] To make the objectives, advantages, and features of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that the drawings are all in a very simplified form and are not drawn to scale, and are only used to facilitate and clarify the explanation of the embodiments of this invention. Furthermore, the structures shown in the drawings are often part of the actual structures. In particular, different figures may emphasize different aspects and may sometimes use different scales.

[0041] It should be understood that when an element or layer is referred to as "on" or "connected to" other elements or layers, it may be directly on or connected to other elements or layers, or there may be intervening elements or layers. Conversely, when an element is referred to as "directly on" or "directly connected to" other elements or layers, there are no intervening elements or layers. Although the terms first, second, third, etc., may be used to describe various elements, components, areas, layers, and / or portions, these elements, components, areas, layers, and / or portions should not be limited by these terms. These terms are only used to distinguish one element, component, area, layer, or portion from another element, component, area, layer, or portion. Therefore, without departing from the teachings of this invention, the first element, component, area, layer, or portion discussed below may be referred to as a second element, component, area, layer, or portion. Spatial relation terms such as "below," "under," "below," "above," "on top," "above," etc., may be used herein for convenience of description to describe the relationship between one element or feature shown in the figures and other elements or features. It should be understood that, in addition to the orientations shown in the figures, spatial relational terms are intended to also include different orientations of the devices in use and operation. For example, if the devices in the figures are flipped, then elements or features described as “below,” “under,” or “below” will be oriented “on” other elements or features. Devices may be oriented additionally (rotated 90 degrees or otherwise) and the spatial descriptive terms used herein will be interpreted accordingly. The terminology used herein is intended only to describe particular embodiments and is not intended to limit the invention. When used herein, the singular forms “a,” “an,” and “the” are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “comprising” is used to identify the presence of features, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups. When used herein, the terms “and / or” include any and all combinations of the associated listed items.

[0042] The purpose of this invention is to provide a method for detecting the degree of corrosion of sleeve joints in prefabricated concrete structures, so as to simultaneously detect the corrosion of the inner and outer walls of the sleeve.

[0043] To achieve the above objectives, this invention provides a method for detecting the degree of corrosion of sleeve joints in prefabricated concrete structures, wherein the sleeve is cast inside the concrete. (Please refer to...) Figure 1 This is a flowchart illustrating a method for detecting the degree of corrosion of sleeve joints in prefabricated concrete structures, provided in an embodiment of the present invention. Figure 1 As shown, the method for detecting the degree of corrosion of sleeve joints in prefabricated concrete structures provided by the present invention includes the following steps:

[0044] Step S100: Determine the projection range of the sleeve under test on the surface of the concrete component, and use a concrete resistivity tester to continuously scan and detect from top to bottom or from bottom to top within the projection range to obtain the resistivity value of each detection point within the projection range;

[0045] Step S200: Determine whether there is at least one detection point within the projection range whose resistivity value is less than a preset resistivity threshold;

[0046] If yes, proceed to step S300; otherwise, proceed to step S400.

[0047] Step S300: Determine that the outer wall of the tested sleeve is corroded, and mark the detection point with the smallest resistivity value within the projection range as the target detection point, and then execute step S500;

[0048] Step S400: Determine that the outer wall of the tested sleeve is not corroded, and open a hole in the grout outlet of the tested sleeve. The depth of the hole is greater than the minimum distance between the inner wall of the tested sleeve and the surface of the concrete component. Use an endoscope to insert into the hole and use the endoscope to detect whether the inner wall of the tested sleeve is corroded.

[0049] If the test result shows that the inner wall of the tested sleeve is not corroded, the test on the tested sleeve ends; if the test result shows that the inner wall of the tested sleeve is corroded, step S600 is executed.

[0050] Step S500: Drill core samples on the tested sleeve according to the location of the target detection point to obtain core samples, and determine the outer wall corrosion rate or total corrosion rate of the tested sleeve based on the core samples;

[0051] Step S600: Core sampling is performed at any location within a 20mm range below the grout outlet of the tested sleeve to obtain a core sample. Based on the core sample, the corrosion rate of the inner wall of the tested sleeve is determined. This invention first uses a concrete resistivity tester, utilizing the principle that structural sleeves and reinforcing bars are both corroded steels, to determine whether the outer wall of the sleeve is corroded by pre-setting a resistivity threshold that matches the corrosion condition of the sleeve's outer wall. Then, based on the experience that the grout outlet area is most prone to corrosion, an opening is made in the grout outlet, and an endoscope is used to observe whether the inner wall is corroded. Next, to calculate the corrosion rate, a core sampling method is introduced. By drilling core samples from the outer wall of the sleeve, the corrosion rate is determined by comparing the different states before and after corrosion. Through this operation, this invention... This invention enables efficient and accurate assessment of the overall corrosion of the inner and outer walls of the sleeve without causing large-scale structural damage. It can obtain the corrosion status and rate of the outer wall, the corrosion status and rate of the inner wall, and the corrosion status and total corrosion rate of both the outer and inner walls. This allows for the effective identification of severely corroded areas and precise determination of the degree of corrosion at each location, demonstrating strong practicality. Furthermore, the test results can provide data support for subsequent evaluation of the impact of corrosion on the performance of the sleeve joint, indicating a very broad application prospect.

[0052] It should be understood that using an impact drill as a tool allows for efficient operation when drilling the aforementioned holes or core sampling. It should be noted that when drilling the aforementioned holes, the impact drill must be paired with a solid drill bit with an outer diameter not exceeding 14mm. This is because the inner diameter of the grout outlet hole in common grouting sleeves is generally 16mm, and the outer diameter of the solid drill bit not exceeding 14mm effectively avoids damage to the inner wall of the grout outlet hole when drilling the opening in the sleeve.

[0053] Furthermore, the core sampling on the inspected sleeve includes:

[0054] The impact drill with a solid drill bit is used to drill into the concrete until the outer wall surface of the sleeve under test is reached.

[0055] Using the impact drill equipped with a hollow drill bit, core sampling is performed starting from the outer wall surface of the tested sleeve until the entire sleeve wall is drilled through, wherein the outer diameter of the hollow drill bit is less than 12 mm.

[0056] Using traditional methods with hollow drill bits for sampling is inefficient, and the hollow drill bits required for successful sampling are often too long, hindering stable drilling operations. Therefore, a solution is to first use a solid drill bit to drill to the outer surface of the sleeve, then switch to a hollow drill bit to perform core sampling from the outer surface until the entire sleeve wall is penetrated. This method achieves efficient and stable core sampling. However, setting the core sample diameter too high can excessively damage the sleeve, negatively impacting its load-bearing capacity. Based on the inventors' experience, when the outer diameter of the hollow drill bit and the obtained core sample diameter both do not exceed 12mm, effective testing can be achieved without excessive damage to the sleeve. Furthermore, a solid drill bit outer diameter of no more than 14mm allows the hollow drill bit to easily enter the hole for core sampling.

[0057] Preferably, the outer diameter of the endoscope probe does not exceed 7mm. When the inner diameter of the opening is 14mm, extensive experiments have shown that controlling the outer diameter of the endoscope probe to within 7mm can achieve a suitable distance between it and the inner wall of the opening, thereby obtaining a better observation effect.

[0058] Furthermore, the endoscope's probe includes a front-viewing lens and a side-viewing lens, allowing observation of the interior of the opening through the front-viewing lens and / or the side-viewing lens. In an exemplary embodiment, the endoscope is communicatively connected to a display device for displaying images captured by the endoscope's front-viewing lens and / or test lens, facilitating observation by technicians. Furthermore, a controller can be connected to control the endoscope to automatically switch between displaying images captured by different lenses, further facilitating observation by technicians. It should be understood that even without the display device or the controller, observation can still be performed through the endoscope using optical imaging principles or other methods, which will not be elaborated upon here.

[0059] Specifically, the threshold value is 20 kΩ·cm. According to the principles of concrete resistivity testing and relevant standards, a better testing effect can be obtained at a threshold value of 20 kΩ·cm. It should be understood that different threshold values ​​can be set according to the different needs of technical personnel, which will not be elaborated further here.

[0060] Further, optionally, the step of core sampling on the tested sleeve according to the location of the target detection point to obtain a core sample, and determining the outer wall corrosion rate or total corrosion rate of the tested sleeve based on the core sample, includes:

[0061] If the target detection point is located within 20mm below the slurry outlet of the sleeve under test, core sampling is performed at the position corresponding to the target detection point on the sleeve under test to obtain a first core sample. Based on the first core sample, the outer wall corrosion rate or total corrosion rate of the sleeve under test is determined.

[0062] If the target detection point is located more than 20mm below the grout outlet of the sleeve under inspection, core samples are taken at either the location corresponding to the target detection point or at any location within 20mm below the grout outlet of the sleeve under inspection to obtain a first core sample and a second core sample. A first outer wall corrosion rate or a first total corrosion rate is calculated based on the first core sample, and a second outer wall corrosion rate or a second total corrosion rate is calculated based on the second core sample. The outer wall corrosion rate of the sleeve under inspection is determined based on the first and second outer wall corrosion rates, or the total corrosion rate of the sleeve under inspection is determined based on the first and second total corrosion rates. According to industry experience, the grout outlet of the grouting sleeve and its vicinity are the most susceptible to corrosion. Therefore, when the detection location is far from the grout outlet of the sleeve, to ensure the accuracy of the detection, a second detection is performed near the grout outlet, and the corrosion rate is calculated. Extensive testing revealed that when the set detection position extends more than 20mm beyond the periphery of the slurry outlet, performing core sampling again within a 20mm radius of the slurry outlet yields more accurate detection results. It should be noted that determining the outer wall corrosion rate of the tested sleeve based on the first and second outer wall corrosion rates includes:

[0063] If the inner wall of the second core sample is not corroded, then the corrosion rate of the outer wall of the first core sample is taken as the corrosion rate of the outer wall of the tested sleeve.

[0064] If the inner walls of both the first core sample and the second core sample are corroded, the larger of the first total corrosion rate and the second total corrosion rate shall be taken as the total corrosion rate of the tested sleeve.

[0065] It should be understood that, according to the needs of technical personnel, the operating steps of this invention can also be used to perform supplementary testing at different positions on the sleeve, which will not be elaborated here.

[0066] Optionally, determining the outer wall corrosion rate or total corrosion rate of the tested sleeve based on the first core sample includes:

[0067] If the inner wall of the first core sample is corroded, all the rust on the inner and outer walls of the first core sample is removed to obtain the remaining wall thickness of the first core sample, and the total corrosion rate of the tested sleeve is calculated according to the following formula:

[0068] x 总= (a1-b1) / a1×100%

[0069] In the formula, x 总 The total corrosion rate is given by denoted as a1, where a1 is the original wall thickness of the first core sample and b1 is the remaining wall thickness of the first core sample.

[0070] If the inner wall of the first core sample is not corroded, then all the rust on the outer wall of the first core sample is removed to obtain the remaining wall thickness of the first core sample, and the corrosion rate of the outer wall of the tested sleeve is calculated according to the following formula:

[0071] x 外 = (a² - b²) / a² × 100%

[0072] In the formula, x 外 denoted as the outer wall corrosion rate, a2 as the original wall thickness of the first core sample, and b2 as the remaining wall thickness of the first core sample.

[0073] Similarly, determining the corrosion rate of the inner wall of the tested sleeve based on the core sample includes:

[0074] All rust residue on the inner wall of the core sample was removed to obtain the remaining wall thickness of the core sample, and the corrosion rate of the inner wall of the tested sleeve was calculated according to the following formula:

[0075] x 内 = (a3-b3) / a3×100%

[0076] In the formula, x 内 Let a3 be the original wall thickness of the core sample and b3 be the remaining wall thickness of the core sample. The corrosion rate is obtained by dividing the range of corroded wall thickness of the sleeve by the total wall thickness. This step, along with the calculation using the aforementioned formula, provides a direct and quantitative representation of the degree of corrosion of the sleeve. It should be understood that other parameters related to the mass before and after corrosion can also be used to determine the degree of corrosion, which will not be elaborated upon here.

[0077] The following two specific embodiments illustrate the method for detecting the degree of corrosion of prefabricated concrete structure sleeve joints provided by the present invention.

[0078] Example 1

[0079] For a prefabricated concrete building, a sleeve with a wall thickness of 6.0 mm is selected in the exterior wall of the first floor near the junction box of the electromechanical pipeline. Now, according to... Figure 1 The flowchart shows how to detect the corrosion of the sleeve.

[0080] Specifically, the following steps are included:

[0081] (1) Mark the projection range of the sleeve on the concrete surface.

[0082] (2) Along the projection range of the sleeve on the concrete surface, use a concrete resistivity tester to continuously scan from top to bottom. Assuming the concrete resistivity threshold is 20kΩcm, if there are cases where the detected value is less than 20kΩcm, it indicates that the outer wall of the sleeve is corroded.

[0083] (3) Mark the position with the smallest detection value within the projection range of the sleeve on the concrete surface, which is located 50mm below the grout outlet of the sleeve.

[0084] (4) Determine the degree of corrosion within the sleeve wall thickness range:

[0085] At a point 50mm below the grout outlet of the sleeve, first use an impact drill with a solid drill bit to drill into the concrete until the outer wall surface of the sleeve is reached. Then, use an impact drill with a hollow drill bit to drill core samples from the outer wall surface of the sleeve within the sleeve wall thickness until the entire sleeve wall is drilled through. After drilling core samples from the sleeve wall, it was observed that the inner wall of the core sample was corroded. The rust on both the outer and inner walls of the sleeve was removed. The remaining wall thickness was then measured to be 4.8mm. Therefore, the total corrosion rate is (6.0-4.8) / 6.0×100%=20%.

[0086] Select another location 10mm below the slurry outlet of the sleeve to drill a core sample. The outer and inner walls of the core sample at this location are corroded. Remove the rust from the outer and inner walls of the sleeve, and then measure the remaining wall thickness as 5.0mm. The total corrosion rate is (6.0-5.0) / 6.0×100%=16.7%.

[0087] It can be seen that both the outer and inner walls of the sleeve in Example 1 are corroded, with a total corrosion rate of 20%.

[0088] Example 2

[0089] For a certain prefabricated concrete building, a sleeve with a wall thickness of 6.0 mm is selected in the exterior wall of a certain middle prefabricated layer near the termination point of the electromechanical pipeline. Now, according to... Figure 1 The flowchart describes the process of inspecting the corrosion of the sleeve. Specifically, it includes the following steps:

[0090] (1) Mark the projection range of the sleeve on the concrete surface.

[0091] (2) Along the projection range of the sleeve on the concrete surface, use a concrete resistivity tester to continuously scan from top to bottom. If the concrete resistivity threshold is set to 20kΩcm, the test values ​​are all greater than 20kΩcm, indicating that there is no corrosion on the outer wall of the sleeve.

[0092] (3) Use an impact drill with a solid drill bit to drill a hole in the grout outlet of the sleeve until the steel bar inside the sleeve is reached. Then, insert the endoscope probe into the sleeve through the drilling channel and observe the inner wall near the grout outlet of the sleeve by using the front and side view lenses. If the inner wall near the grout outlet of the sleeve is corroded, it is determined that the outer wall of the sleeve is not corroded and the inner wall is corroded.

[0093] (4) Determine the degree of corrosion within the sleeve wall thickness range:

[0094] At a point 10mm below the grout outlet of the sleeve, first use an impact drill with a solid drill bit to drill through the concrete until the outer wall surface of the sleeve is reached. Then, use an impact drill with a hollow drill bit to drill core samples from the outer wall surface of the sleeve within the sleeve wall thickness range until the entire sleeve wall is drilled through. After core sampling of the sleeve wall, first remove the rust from the inner wall of the sleeve, then measure the remaining wall thickness as 5.2mm, and finally calculate the inner wall corrosion rate as (6.0-5.2) / 6.0×100%=13.3%.

[0095] It can be seen that only the inner wall of the sleeve in Example 2 is corroded, and the corrosion rate of the inner wall is 13.3%.

[0096] It should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the systems disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple, and relevant parts can be referred to the method section.

[0097] It should also be noted that although the present invention has been disclosed above with reference to preferred embodiments, these embodiments are not intended to limit the present invention. For any person skilled in the art, many possible variations and modifications can be made to the technical solutions of the present invention based on the disclosed technical content, or equivalent embodiments can be modified accordingly, without departing from the scope of the present invention. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the present invention shall still fall within the scope of protection of the present invention.

[0098] It should also be understood that, unless otherwise specified or indicated, the terms “first,” “second,” “third,” etc., in the specification are used only to distinguish the various components, elements, and steps in the specification, and not to indicate the logical or sequential relationships between the various components, elements, and steps.

[0099] Furthermore, it should be recognized that the terminology described herein is used only to describe particular embodiments and not to limit the scope of the invention. It must be noted that the singular forms “a” and “an” used herein and in the appended claims include plural bases unless the context clearly indicates otherwise. For example, a reference to “a step” or “an apparatus” means a reference to one or more steps or apparatuses, and may include secondary steps and secondary apparatuses. All conjunctions used should be understood in the broadest sense. And the word “or” should be understood to have the definition of logical “or” rather than logical “exclusive OR”, unless the context clearly indicates otherwise. Furthermore, implementation of embodiments of the invention may include performing selected tasks manually, automatically, or in combination.

Claims

1. A method for detecting the degree of corrosion of a sleeve joint in a prefabricated concrete structure, wherein the sleeve is cast inside the concrete, characterized in that... The method includes the following steps: Step S100: Determine the projection range of the sleeve under test on the surface of the concrete component, and use a concrete resistivity tester to continuously scan and detect from top to bottom or from bottom to top within the projection range to obtain the resistivity value of each detection point within the projection range; Step S200: Determine whether there is at least one detection point within the projection range whose resistivity value is less than a preset resistivity threshold; If yes, proceed to step S300; otherwise, proceed to step S400. Step S300: Determine that the outer wall of the tested sleeve is corroded, and mark the detection point with the smallest resistivity value within the projection range as the target detection point, and then execute step S500; Step S400: Determine that the outer wall of the tested sleeve is not corroded, and open a hole in the grout outlet of the tested sleeve. The depth of the hole is greater than the minimum distance between the inner wall of the tested sleeve and the surface of the concrete component. Use an endoscope to insert into the hole and use the endoscope to detect whether the inner wall of the tested sleeve is corroded. If the test result shows that the inner wall of the tested sleeve is not corroded, the test on the tested sleeve ends; if the test result shows that the inner wall of the tested sleeve is corroded, step S600 is executed. Step S500: Drill core samples on the tested sleeve according to the location of the target detection point to obtain core samples, and determine the outer wall corrosion rate or total corrosion rate of the tested sleeve based on the core samples; Step S600: Drill a core sample at any position within a 20mm range below the slurry outlet of the sleeve under inspection to obtain a core sample, and determine the corrosion rate of the inner wall of the sleeve under inspection based on the core sample.

2. The method for detecting the degree of corrosion of sleeve joints in prefabricated concrete structures as described in claim 1, characterized in that, Use an impact drill to create holes and / or take core samples.

3. The method for detecting the degree of corrosion of sleeve joints in prefabricated concrete structures as described in claim 2, characterized in that, The hole is opened using the impact drill equipped with a solid drill bit, the outer diameter of which is less than 14 mm.

4. The method for detecting the degree of corrosion of sleeve joints in prefabricated concrete structures as described in claim 2, characterized in that, The process of taking core samples from the tested sleeve includes: The impact drill with a solid drill bit is used to drill into the concrete until the outer wall surface of the sleeve under test is reached. Using the impact drill equipped with a hollow drill bit, core sampling is performed starting from the outer wall surface of the tested sleeve until the entire sleeve wall is drilled through, wherein the outer diameter of the hollow drill bit is less than 12 mm.

5. The method for detecting the degree of corrosion of sleeve joints in prefabricated concrete structures as described in claim 1, characterized in that, The endoscope's probe includes a front-viewing lens and a side-viewing lens.

6. The method for detecting the degree of corrosion of sleeve joints in prefabricated concrete structures as described in claim 1, characterized in that, The step of drilling core samples on the tested sleeve according to the location of the target detection point to obtain core samples, and determining the outer wall corrosion rate or total corrosion rate of the tested sleeve based on the core samples, includes: If the target detection point is located within 20mm below the slurry outlet of the sleeve under test, core sampling is performed at the position corresponding to the target detection point on the sleeve under test to obtain a first core sample. Based on the first core sample, the outer wall corrosion rate or total corrosion rate of the sleeve under test is determined. If the target detection point is located more than 20 mm below the slurry outlet of the sleeve under test, core samples are taken at either the location corresponding to the target detection point or at any location within 20 mm below the slurry outlet of the sleeve under test to obtain a first core sample and a second core sample. The first outer wall corrosion rate or the first total corrosion rate is calculated based on the first core sample, and the second outer wall corrosion rate or the second total corrosion rate is calculated based on the second core sample. The outer wall corrosion rate of the sleeve under test is determined based on the first outer wall corrosion rate and the second outer wall corrosion rate, or the total corrosion rate of the sleeve under test is determined based on the first total corrosion rate and the second total corrosion rate.

7. The method for detecting the degree of corrosion of sleeve joints in prefabricated concrete structures as described in claim 6, characterized in that, The step of determining the outer wall corrosion rate or total corrosion rate of the tested sleeve based on the first core sample includes: If the inner wall of the first core sample is corroded, all the rust on the inner and outer walls of the first core sample is removed to obtain the remaining wall thickness of the first core sample, and the total corrosion rate of the tested sleeve is calculated according to the following formula: x 总 =(a1-b1) / a1×100% In the formula, x 总 The total corrosion rate is given by denoted as a1, where a1 is the original wall thickness of the first core sample and b1 is the remaining wall thickness of the first core sample. If the inner wall of the first core sample is not corroded, then all the rust on the outer wall of the first core sample is removed to obtain the remaining wall thickness of the first core sample, and the corrosion rate of the outer wall of the tested sleeve is calculated according to the following formula: x 外 =(a2-b2) / a2×100% In the formula, x 外 denoted as the outer wall corrosion rate, a2 as the original wall thickness of the first core sample, and b2 as the remaining wall thickness of the first core sample.

8. The method for detecting the degree of corrosion of sleeve joints in prefabricated concrete structures as described in claim 6, characterized in that, The step of determining the outer wall corrosion rate of the tested sleeve based on the first outer wall corrosion rate and the second outer wall corrosion rate includes: If the inner wall of the second core sample is not corroded, then the corrosion rate of the outer wall of the first core sample is taken as the corrosion rate of the outer wall of the sleeve under test. If the inner walls of both the first core sample and the second core sample are corroded, the larger of the first total corrosion rate and the second total corrosion rate shall be taken as the total corrosion rate of the tested sleeve.

9. The method for detecting the degree of corrosion of sleeve joints in prefabricated concrete structures as described in claim 1, characterized in that, The step of determining the corrosion rate of the inner wall of the tested sleeve based on the core sample includes: All rust residue on the inner wall of the core sample was removed to obtain the remaining wall thickness of the core sample, and the corrosion rate of the inner wall of the tested sleeve was calculated according to the following formula: x 内 (a3-b3) / a3×100% In the formula, x 内 a3 is the inner wall corrosion rate, a3 is the original wall thickness of the core sample, and b3 is the remaining wall thickness of the core sample.

10. The method for detecting the degree of corrosion of sleeve joints in prefabricated concrete structures as described in any one of claims 1 to 9, characterized in that, The endoscope probe has a diameter of less than 7 mm.

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