A method for determining the optimum amount and type of conductive medium in a health monitoring pavement

Abstract

The application discloses a method for determining the optimal content and type of conductive medium in a health monitoring pavement, and relates to the field of asphalt concrete, and comprises the following steps: preparing a plurality of health monitoring pavement test pieces with different conductive medium contents; cutting the health monitoring pavement test pieces into semi-cylindrical health monitoring pavement test pieces; extracting pixel points where the conductive medium is located in an image; calculating the dispersity of the conductive medium; calculating the agglomeration of the conductive medium; calculating the resistivity of the health monitoring pavement test piece; adopting a water immersion Marshall test and a freeze-thaw splitting test to evaluate the water stability of the health monitoring pavement test piece; uniformly processing the three indexes of the dispersity, the agglomeration and the resistivity; and determining the optimal content and type of the conductive medium in the health monitoring pavement. The application provides a comprehensive and comprehensive evaluation method for the closed loop degree determination of the conductive medium, and has important significance for determining the content and type of the conductive medium.

Description

Technical fields:

[0001] This invention relates to the field of asphalt concrete, and more particularly to a method for determining the optimal dosage and type of conductive medium in health monitoring pavements. Background technology:

[0002] Health monitoring pavement is a type of pavement constructed from asphalt concrete with incorporated conductive media (graphite, carbon fiber, steel fiber, etc.). These conductive media form conductive pathways due to a closed-loop effect, giving the pavement a certain level of conductivity. By utilizing the relationship between changes in the pavement's performance and its resistance, fatigue damage within the pavement can be assessed, making it possible to predict pavement defects and initiate self-repair. This is the principle behind health monitoring pavement. When subjected to external conditions, stress, strain, fatigue cracks, aging, and other structural damage cause changes in the microstructure of the asphalt pavement, resulting in changes in resistivity.

[0003] However, due to the influence of factors such as the type and dosage of the conductive medium, as well as the mixing method and mixing time, the distribution of the conductive medium in health monitoring pavements exhibits significant non-uniformity, resulting in large differences in whether conductive pathways can be formed and the length of those pathways. Therefore, there is an urgent need for a method to determine the optimal dosage and type of conductive medium in health monitoring pavements, so that the conductive medium within the health monitoring pavement can form the shortest conductive pathway. Summary of the Invention:

[0004] To address the aforementioned technical problems, this invention discloses a method for determining the optimal dosage and type of conductive medium in health monitoring pavements. This method is of great significance for improving the health monitoring performance of health monitoring pavements and determining the dosage of conductive medium. The method is implemented according to the following steps:

[0005] S1: Prepare multiple sets of health monitoring test specimens with different conductive dielectric doping amounts;

[0006] S2: Cut the health monitoring road test specimen longitudinally along the height direction to form a semi-cylindrical health monitoring road test specimen;

[0007] S3: Place the semi-cylindrical health monitoring road test specimen flat, use magnetoacoustic imaging technology to obtain the image of the cut surface of the health monitoring road test specimen, and extract the pixels where the conductive medium is located in the image.

[0008] S4: Calculate the dispersion of the conductive medium based on the pixel points where the conductive medium is located obtained from S3;

[0009] S5: Calculate the density of the conductive medium based on the pixel location obtained in S3;

[0010] S6: Calculate the resistivity of the health monitoring road test specimen;

[0011] S7: The water stability of health monitoring road test specimens was evaluated using the immersion Marshall test and freeze-thaw splitting test.

[0012] S8: The three indicators of dispersion, aggregation, and resistivity are homogenized.

[0013] S9: Summing OD based on normalized arithmetic and the normalized values ​​of each index. s For specimens with a maximum value, water immersion residual stability, and splitting tensile strength ratio after freeze-thaw all greater than 80%, the optimal dosage and type of conductive medium for health monitoring pavement were determined.

[0014] Preferably, in step S4, the dispersion of the conductive medium is calculated using the following method:

[0015] S4.1: Cover the image with a square grid of side length r×r, and count the number of non-empty grids N(r) that cover the aluminum particles;

[0016] S4.2: Calculate the probability p that a point in the fractal falls on the i-th grid. i ;

[0017] S4.3: Based on the above data, calculate the fractal dimension D. i

[0018]

[0019]

[0020] Preferably, in step S5, the method for calculating the aggregation degree of the conductive medium is as follows:

[0021] S5.1: Cover the image with a square grid of side length R×R (each small square has a side length r′), and use equally spaced straight lines to cut out the image;

[0022] S5.2: Determine the position of the conductive medium intercepted by a certain straight line, and count the number n of conductive media in the square grid with a side length of 2r′ (which is uniformly defined as the grid containing the lower left corner of the conductive medium);

[0023] S5.3: Calculate the average nearest neighbor distance between other conductive media and the intercepted conductive media within a square grid with side length 2r′.

[0024]

[0025] Where, d i The distance between any conductive medium within the range (excluding the intercepted conductive medium) and the intercepted conductive medium;

[0026] S5.4: Calculate the aggregation degree k

[0027]

[0028] Preferably, in step S6, the resistivity of the health monitoring road surface specimen is calculated, and the specific steps are as follows:

[0029] S6.1: Clean and polish the electrode contact areas on the top and bottom surfaces of the health monitoring road test specimen;

[0030] S6.2: Graphite powder is filled on the surface of the health monitoring road test specimen. The graphite powder is sandwiched between the electrode and the specimen. The weight of the electrode is used to press the surface of the health monitoring road test specimen to make it in close contact.

[0031] S6.3: Calculate the resistivity of the health monitoring road test specimen.

[0032]

[0033] Where ρ is the resistivity of the health monitoring road test specimen, R is the resistance of the health monitoring road test specimen, S is the cross-sectional area of ​​the health monitoring road test specimen, and H is the height of the health monitoring road test specimen.

[0034] Preferably, in step S8, the method for determining the uniformity of the conductive dielectric dispersion is as follows:

[0035] S8.1: Each index is standardized to a normalized value between 0 and 1. For the two indices, dispersion and resistivity, where larger values ​​are considered better, normalized values ​​d are calculated separately. max The normalized value d is calculated using the aggregation degree index, where smaller values ​​are generally better. min ;

[0036]

[0037]

[0038] Among them, Y i It is the calculated index value of the specimen, Y. max It is the maximum value of the index among all specimens, Y min It is the minimum value of the index among all specimens;

[0039] S8.2: Calculate the arithmetic sum of the normalized values ​​and ODS.

[0040]

[0041] Compared with existing technologies, the present invention provides a method for determining the optimal dosage and type of conductive medium in road surface health monitoring, which can achieve the following technical effects:

[0042] (1) This invention provides a method for determining the optimal dosage and type of conductive medium in health monitoring pavement. Based on three indicators, fractal dimension, aggregation degree and resistivity, it accurately and quantitatively characterizes the dispersion degree of conductive medium and the shortest conductive path that can be formed, providing a comprehensive evaluation method for determining the closed-loop nature of conductive medium.

[0043] (2) This invention provides a method for determining the optimal dosage and type of conductive medium in health monitoring pavement, which is of great significance for improving the health monitoring performance of health monitoring pavement and determining the dosage and type of conductive medium. Attached Figure Description

[0044] Figure 1 The flowchart illustrates the method for determining the optimal dosage and type of conductive medium in road surface health monitoring according to this invention. Detailed Implementation

[0045] The following will describe the implementation of the present invention in detail with reference to the embodiments, so that the process of how the present invention uses technical means to solve technical problems and achieve technical effects can be fully understood and implemented accordingly.

[0046] Example:

[0047] In the laboratory, Marshall specimens for health monitoring of road surfaces were prepared using the Marshall compaction method. The specimens were cylinders with a diameter of 101 mm and a height of 60 mm. The asphalt mixture used was AC-20 type, with a maximum nominal aggregate size of 26.5 mm.

[0048] The conductive medium of the Marshall specimen for health monitoring of the road surface to be tested was set to be graphite.

[0049] The graphite used is flake graphite with a fineness of 400 mesh.

[0050] Monitoring showed that when the graphite content was greater than 15%, the specimen was able to begin to form a conductive network. Therefore, the experimental groups were set up with the graphite content as shown in Table 1 below:

[0051] Table 1

[0052]

[0053] The performance of different graphite contents in Table 1 was monitored using the following method:

[0054] S1: Prepare multiple sets of health monitoring road test specimens with different conductive dielectric doping amounts, and the conductive dielectric in the health monitoring road test specimens can be captured by magnetoacoustic imaging technology.

[0055] S2: Cut the health monitoring road test specimen longitudinally along the height direction to form a semi-cylindrical health monitoring road test specimen;

[0056] S3: Place the semi-cylindrical health monitoring road test specimen flat, select the imaging technology according to the properties of the conductive medium, and extract the pixels where the conductive medium is located in the image after imaging.

[0057] S4: Based on the pixel location of the conductive medium obtained in S3, calculate the dispersion of the conductive medium:

[0058] S4.1: Cover the image with a square grid of side length r×r, and count the number of non-empty grids N(r) that cover the aluminum particles;

[0059] S4.2: Calculate the probability p that a point in the fractal falls on the i-th grid. i ;

[0060] S4.3: Based on the above data, calculate the fractal dimension D. i

[0061]

[0062]

[0063] S5: Calculate the density of the conductive medium based on the pixel location obtained in S3.

[0064] S5.1: Cover the image with a square grid of side length R×R (each small square has a side length r′), and use equally spaced straight lines to cut out the image;

[0065] S5.2: Determine the position of the conductive medium intercepted by a certain straight line, and count the number n of conductive media in the square grid with a side length of 2r′ (which is uniformly defined as the grid containing the lower left corner of the conductive medium);

[0066] S5.3: Calculate the average nearest neighbor distance between other conductive media and the intercepted conductive media within a square grid with side length 2r′.

[0067]

[0068] Where, d i The distance between any conductive medium within the range (excluding the intercepted conductive medium) and the intercepted conductive medium;

[0069] S5.4: Calculate the aggregation degree k

[0070]

[0071] S6: Calculate the resistivity of the health monitoring road test specimen;

[0072] S6.1: Clean and polish the electrode contact areas on the top and bottom surfaces of the health monitoring road test specimen;

[0073] S6.2: Graphite powder is filled on the surface of the health monitoring road test specimen. The graphite powder is sandwiched between the electrode and the specimen. The weight of the electrode is used to press the surface of the health monitoring road test specimen to make it in close contact.

[0074] S6.3: Calculate the resistivity of the health monitoring road test specimen.

[0075]

[0076] Where ρ is the resistivity of the health monitoring road test specimen, R is the resistance of the health monitoring road test specimen, S is the cross-sectional area of ​​the health monitoring road test specimen, and H is the height of the health monitoring road test specimen.

[0077] S7: The water stability of health monitoring road test specimens was evaluated using the immersion Marshall test and freeze-thaw splitting test.

[0078] S8: The three indicators of dispersion, aggregation, and resistivity are homogenized.

[0079] S8.1: Each index is standardized to a normalized value between 0 and 1. For the two indices, dispersion and resistivity, where larger values ​​are considered better, normalized values ​​d are calculated separately. max The normalized value d is calculated using the aggregation degree index, where smaller values ​​are generally better. min ;

[0080]

[0081]

[0082] Among them, Y i It is the calculated index value of the specimen, Y. max It is the maximum value of the index among all specimens, Y min It is the minimum value of the index among all specimens;

[0083] S8.2: Calculate the arithmetic sum of the normalized values ​​and OD. s :

[0084]

[0085] S9: Determine the optimal dosage of conductive medium for health monitoring road surfaces.

[0086] The measurement and calculation results of various parameters for experimental groups 1-6 above are shown in Table 2 below:

[0087] Table 2

[0088]

[0089]

[0090] As shown in Table 2 above, the normalized arithmetic value and OD of experimental group 5 (Marshall specimens for health monitoring pavement with a dosage of 20%) are... s The optimal dosage of graphite for health monitoring pavement is 20%, which meets the requirements of 80% for residual stability after immersion and splitting tensile strength after freeze-thaw cycles.

[0091] It should be noted that, in this document, the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0092] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for determining the optimal dosage and type of conductive medium in a health monitoring pavement, characterized in that: Includes the following steps: S1: Prepare multiple sets of health monitoring test specimens with different conductive dielectric doping amounts; S2: Cut the health monitoring road test specimen longitudinally along the height direction to form a semi-cylindrical health monitoring road test specimen; S3: Place the semi-cylindrical health monitoring road test specimen flat, select the imaging technology according to the properties of the conductive medium, and extract the pixels where the conductive medium is located in the image after imaging. S4: Calculate the dispersion of the conductive medium based on the pixel points where the conductive medium is located obtained from S3; S5: Calculate the density of the conductive medium based on the pixel location obtained in S3; S6: Calculate the resistivity of the health monitoring road test specimen; S7: The water stability of health monitoring road test specimens was evaluated using the immersion Marshall test and freeze-thaw splitting test. S8: The three indicators of dispersion, aggregation, and resistivity are homogenized. S9: Based on specimens with the maximum normalized arithmetic sum, water immersion residual stability, and splitting tensile strength ratio after freeze-thaw cycles all greater than 80%, determine the optimal dosage and type of conductive medium for health monitoring pavements.

2. The method for determining the optimal dosage and type of conductive medium in a health monitoring pavement according to claim 1, characterized in that, In step S4, the dispersion of the conductive medium is calculated, and the specific steps are as follows: S4.1: Cover the image with a square grid of side length r×r, and count the number of non-empty grids N(r) that cover the aluminum particles; S4.2: Calculate the probability p that a point in the fractal falls on the i-th grid. i ; S4.3: Based on the above data, calculate the fractal dimension D. i 3. The method for determining the optimal dosage and type of conductive medium in a health monitoring pavement according to claim 1, characterized in that, In step S5, the degree of aggregation of the conductive medium is calculated, and the specific steps are as follows: S5.1: Cover the image with a square grid of side length R×R, and set the side length of each small square to r', and use equally spaced straight lines to cut out the image; S5.2: Determine the position of the conductive medium intercepted by a certain straight line, and count the number n of conductive media within a square grid with a side length of 2r' for each conductive medium; S5.3: Calculate the average nearest neighbor distance between other conductive media and the intercepted conductive media within a square grid with side length 2r'. Where, d i The distance between any conductive medium within the range and the intercepted conductive medium; S5.4: Calculate the aggregation degree k 4. The method for determining the optimal dosage and type of conductive medium in a health monitoring pavement according to claim 1, characterized in that, In step S6, the resistivity of the health monitoring road test specimen is calculated, and the specific steps are as follows: S6.1: Clean and polish the electrode contact areas on the top and bottom surfaces of the health monitoring road test specimen; S6.2: Graphite powder is filled on the surface of the health monitoring road test specimen. The graphite powder is sandwiched between the electrode and the specimen. The weight of the electrode is used to press the surface of the health monitoring road test specimen to make it in close contact. S6.3: Calculate the resistivity of the health monitoring road test specimen. Where ρ is the resistivity of the health monitoring road test specimen, R is the resistance of the health monitoring road test specimen, S is the cross-sectional area of ​​the health monitoring road test specimen, and H is the height of the health monitoring road test specimen.

5. The method for determining the optimal dosage and type of conductive medium in a health monitoring pavement according to claim 1, characterized in that, In step S8, the method for determining the uniformity of the conductive medium dispersion is as follows: S8.1: Each index is standardized to a normalized value between 0 and 1. For the two indices, dispersion and resistivity, where larger values ​​are considered better, normalized values ​​d are calculated separately. max The normalized value d is calculated using the aggregation degree index, where smaller values ​​are preferred. min ; Among them, Y i It is the calculated index value of the specimen, Y. max It is the maximum value of the index among all specimens, Y min It is the minimum value of the index among all specimens; S8.2: Calculate the arithmetic sum of the normalized values ​​and OD. s :

Images