A method for quantitatively analyzing asphalt-aggregate interface failure behavior based on image processing

Abstract

This invention discloses a quantitative analysis method for asphalt-aggregate interface failure behavior based on image processing, belonging to the field of road engineering. The method includes the following steps: conducting pull-out tests on the asphalt-aggregate interface using a universal testing machine to obtain stress-strain curves, extracting evaluation indicators based on the stress-strain curves, and calculating the cohesive failure behavior test results based on the evaluation indicators; acquiring images of the failure interface of the hybrid failure specimen using digital image processing methods, identifying and calculating the area ratio of the cohesive failure region to the adhesive failure region based on the acquired images; and calculating the evaluation indicator results of the adhesive failure region based on the cohesive failure behavior test results and the area ratio, thereby achieving a quantitative expression of the asphalt-aggregate interface bonding failure behavior.

Description

Technical Field

[0001] This invention belongs to the field of road engineering technology, and in particular relates to a quantitative analysis method for failure behavior of asphalt-aggregate interface based on image processing. Background Technology

[0002] Water damage to asphalt pavements refers to the phenomenon where, during service, surface moisture and melting snow are forced into the pores of the pavement mixture by vehicle wheels, creating repeated dynamic water pressure or vacuum suction. This affects the original asphalt-aggregate interface bonding, leading to the gradual replacement of asphalt by water and the formation of a water-aggregate bond. Water damage to asphalt pavements is one of the most common early-stage pavement defects in hot and humid regions and a key focus of pavement design and construction. As defined and explained above, the core of asphalt pavement's resistance to water damage lies in the strong bond between the asphalt and aggregate interfaces, which effectively resists rainwater intrusion. In other words, the bonding characteristics of the asphalt-aggregate interface are crucial in reflecting the water damage resistance of the asphalt mixture.

[0003] Road engineers have come to deeply understand the importance of the interfacial bonding characteristics between asphalt and aggregates, and have developed a series of test methods and evaluation indicators to reflect this. Currently, the standard test method is the boiling / immersion method. This method primarily observes the spalling of aggregates of a certain particle size at the asphalt interface in slightly boiling or 80°C water. This method requires a high level of experience from the operator, and the test results can only be used for qualitative analysis.

[0004] Based on the shortcomings of the current boiling method, Youtchef et al. introduced the Pneumatic Adhesion Tensile Testing Instrument (PATTI) from the polymer coatings industry, which has gradually become the mainstream method for studying the bonding characteristics of road asphalt and aggregates. The specific procedure involves immersing a pull-out bolt in hot asphalt and rapidly bonding it to the specific lithological aggregate being tested. After cooling, pneumatic pressure is used to pull it out, thus obtaining the bonding performance data. This testing method still has the following limitations: First, it cannot distinguish between cohesive failure and adhesive failure, resulting in a mismatch with the water damage failure modes of asphalt mixtures in real service environments; second, it considers all test results as valid, leading to the inclusion of some results with large errors in the analysis, resulting in poor stability and reproducibility of the test results; third, it cannot control test process parameters such as test temperature and tensile speed, and the obtained results are only numerical values, lacking a systematic approach to scientific research.

[0005] In recent years, tensile tests on the asphalt-aggregate interface have been conducted using universal testing machines (UTMs) and material test systems (MTSs). This allows for dynamic control and continuous recording of the test process. However, similar to the aforementioned test methods, neither can effectively distinguish between cohesive failure and adhesive failure at the asphalt-aggregate interface, nor can it provide criteria for determining the success or failure of the test.

[0006] As can be seen from the above review, although some research and improvements have been made to the test methods for the bonding characteristics of the asphalt-aggregate interface, it is still impossible to distinguish the types of bonding failures at the asphalt-aggregate interface, nor can a criterion for judging whether the test is successful be given, let alone a test method with stability and reproducibility. Summary of the Invention

[0007] To address the aforementioned technical problems, this invention proposes a quantitative analysis method for asphalt-aggregate interface failure behavior based on image processing, thereby resolving the issues present in the prior art.

[0008] To achieve the above objectives, this invention provides a quantitative analysis method for asphalt-aggregate interface failure behavior based on image processing, comprising:

[0009] Pull-out tests were conducted on the asphalt-aggregate interface using a universal testing machine to obtain stress-strain curves. Evaluation indices were then extracted based on the stress-strain curves, and the cohesive failure behavior test results were calculated based on the evaluation indices.

[0010] Digital image processing methods were used to acquire images of the failure interface of hybrid failure specimens. Based on the acquired images, the area ratio of cohesive failure region to adhesive failure region was identified and calculated.

[0011] Based on the test results of the cohesive failure behavior and the area ratio, the evaluation index results of the adhesive failure area are calculated, so as to realize the quantitative expression of the asphalt-aggregate interface bonding failure behavior.

[0012] Optionally, the process of extracting evaluation indicators based on stress-strain curves includes:

[0013] Curve fitting was performed on the continuous stress-strain data collected during the pull-out test to identify characteristic points on the curve;

[0014] When the specimen fails by fracture, the tensile modulus is calculated using the maximum tensile stress and strain corresponding to the peak point of the stress-strain curve, and the fracture energy is obtained by integrating the stress-strain curve.

[0015] When the specimen yields but does not fracture, the yield modulus is calculated by the stress corresponding to the yield plateau on the stress-strain curve and the strain corresponding to the stress, and the yield energy is obtained by calculating the integral area under the stress-strain curve from the beginning of the test to the end of the yielding stage.

[0016] Strength indices are constructed based on the tensile modulus and yield modulus, and energy indices are constructed based on the fracture energy and yield energy.

[0017] Based on the characteristics of the selected asphalt material, at least one strength index and at least one energy index are selected as evaluation indicators for the asphalt-aggregate interfacial bonding performance.

[0018] Optionally, the process of identifying and calculating the area ratio of cohesive failure regions to adhesive failure regions based on the acquired images includes:

[0019] After the test specimen completes the test, the two failure interfaces are arranged in an axisymmetric order corresponding to the damage areas and images are collected.

[0020] The acquired image is enhanced and binarized to obtain a grayscale image;

[0021] Based on the grayscale image, an adaptive threshold segmentation algorithm is used to perform image binarization processing to separate the asphalt area from the aggregate area;

[0022] In the binarized image, the asphalt-asphalt contact area is identified as the cohesive failure area, and the asphalt-aggregate contact area is identified as the adhesive failure area.

[0023] The number of pixels in the cohesive failure region and the adhesive failure region are counted separately, and the area ratio of the cohesive failure region to the adhesive failure region is calculated.

[0024] Optionally, the process of using an adaptive threshold segmentation algorithm for image binarization to separate the asphalt region from the aggregate region and obtain the area ratio of the cohesive failure region to the adhesion failure region includes:

[0025] The two binarized images are arranged in an axisymmetric order that corresponds one-to-one with the damaged areas;

[0026] A planar coordinate system is established based on two images placed symmetrically, and the planar coordinate positions of each part are obtained;

[0027] Compare the failure results of plane coordinate positions that are symmetrical. When both symmetrical positions are asphalt, it is recorded as cohesive failure. When one of the symmetrical positions is an aggregate part, it is recorded as adhesive failure.

[0028] The number of pixels in the cohesive failure region and the adhesive failure region are counted separately, and the area ratio of the cohesive failure region to the adhesive failure region is calculated.

[0029] Optionally, the acquired images are enhanced and binarized using the Matlab image processing platform. The process of processing images using the Matlab image processing platform includes:

[0030] The original color image was enhanced for contrast and filtered for noise using Matlab image processing functions. The enhanced color image was then converted to a grayscale image using the rgb2gray function.

[0031] Optionally, the process of calculating the evaluation index results of the adhesion failure region based on the test results of the cohesive failure behavior and the area ratio includes:

[0032] Based on the test results of the cohesive failure behavior and the area of ​​the test area, the strength index and energy index results were calculated.

[0033] Establish the mathematical relationship between the overall evaluation index of hybrid failure and the evaluation indices of cohesive failure and adhesive failure;

[0034] The contribution weights of cohesive failure mode and adhesive failure mode in hybrid failure are determined based on the area ratio obtained from digital image processing.

[0035] By substituting the test results of cohesive failure behavior and the contribution weights of the two failure modes in mixed failure into the mathematical relationship of mixed failure, and combining the test results of mixed failure, the evaluation index results of the adhesive failure region are obtained.

[0036] Optionally, after achieving a quantitative expression of the asphalt-aggregate interface bond failure behavior, the evaluation method feasibility verification is also included;

[0037] Among them, the stability and reproducibility of the quantitative expression results of the asphalt-aggregate interface bonding failure behavior were analyzed using the analysis of variance method and the two-sample t-test method.

[0038] The present invention also provides a computer, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the method described thereon.

[0039] The present invention also provides a storage medium having a computer program stored thereon, which, when executed by a processor, implements the method described thereon.

[0040] Compared with the prior art, the present invention has the following advantages and technical effects:

[0041] This invention successfully achieves precise quantitative analysis of asphalt-aggregate interface failure behavior by combining mechanical testing and image processing techniques. This method can effectively distinguish the contribution ratios of cohesive and adhesive failures, overcoming the shortcomings of traditional methods that can only qualitatively evaluate or cannot distinguish failure modes. By establishing a scientific quantitative evaluation system, reliable data support is provided for the study of water damage resistance of asphalt mixtures, significantly improving the accuracy, stability, and engineering guidance value of the test results. Attached Figure Description

[0042] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0043] Figure 1 This is a diagram illustrating the experimental technology roadmap for an embodiment of the present invention.

[0044] Figure 2 The test steps for the hybrid failure test are as follows, according to an embodiment of the present invention;

[0045] Figure 3 The following are some test cases in the cohesive failure test of the present invention; (a) is a tensile process diagram, (b) the failure interface is not in the test area due to excessive tensile speed, (c) the failure interface appears between asphalt and aggregate due to excessively low tensile temperature, and (d) the cohesive force test fails due to excessively large test area.

[0046] Figure 4 The evaluation index for the bonding failure process of the asphalt-aggregate interface in this embodiment of the invention is as follows: (a) is the evaluation index when the specimen fails due to fracture, and (b) is the evaluation index when the specimen fails due to yielding in the cohesion test.

[0047] Figure 5 The diagram illustrates the effectiveness judgment based on the failure results of the test specimen in the cohesiveness test of this invention, wherein (a) is the normal tensile elongation of asphalt in the test area, (b) is the asphalt fracture located inside the test area, and (c) is the asphalt fracture located at the root of the test area.

[0048] Figure 6 This is a quantitative expression process for the asphalt-aggregate interface bonding failure behavior according to an embodiment of the present invention.

[0049] Figure 7 This is a flowchart of binary image failure type comparison and analysis based on ImageJ software according to an embodiment of the present invention;

[0050] Figure 8 This is a design drawing of the cohesive failure tensile device in the BTTD tensile device according to an embodiment of the present invention;

[0051] Figure 9 This is a design drawing of the fixture used for cohesive testing in the BTTD tensile apparatus of this invention.

[0052] Figure 10 Design drawing of the hybrid failure tensile device in the BTTD tensile device of this invention;

[0053] Figure 11 This is a design drawing of a fixture for mixed-type testing in the BTTD tensile apparatus of this invention. Detailed Implementation

[0054] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0055] It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although a logical order is shown in the flowchart, in some cases the steps shown or described may be executed in a different order than that shown here.

[0056] Example 1

[0057] To address the aforementioned bottlenecks, this invention, based on current research, provides experimental procedures for assessing the failure behavior of the asphalt-aggregate interface bonding characteristics. Combining the experimental result analysis and digital image processing methods mentioned in the patent, the proportions of cohesive and adhesive failures in any mixed-type failure outcome can be distinguished. Simultaneously, based on the experimental evaluation index results, the tensile modulus and energy contribution results for cohesive and adhesive failures are calculated separately, enabling quantitative analysis of the asphalt-aggregate interface bonding characteristics. Furthermore, this patent verifies the stability and reproducibility of the experimental results, demonstrating the accuracy of the testing method. The experimental method mentioned in this patent can effectively evaluate the bonding characteristics of asphalt mixture interfaces, providing a quantitative analytical tool for in-depth research on the water damage performance of asphalt mixtures.

[0058] To quantitatively analyze the bonding failure behavior of the asphalt-aggregate interface, this invention combines digital image processing technology to establish a method for analyzing the contribution of cohesive and adhesive failures in mixed failure types, thus forming a quantitative testing method for expressing the bonding failure behavior of the asphalt-aggregate interface. Simultaneously, the stability and reproducibility of the proposed testing method are analyzed to verify its reliability.

[0059] like Figure 1 As shown, this embodiment provides a quantitative analysis method for asphalt-aggregate interface failure behavior based on image processing, including the following steps:

[0060] First, pull-out tests of asphalt mixtures are mainly conducted using a universal testing machine (UTM). Based on the test results, evaluation indicators that can distinguish the test results of different test objects are given. At the same time, based on the occurrence of asphalt-aggregate interface bonding failure behavior during the test process, the criteria for judging the success and failure of the test process are clarified.

[0061] Secondly, after obtaining the test results of asphalt-aggregate interface bonding failure, it is necessary to construct an analysis method for the contribution of cohesive failure and adhesive failure in the mixed failure. By analyzing the cohesive failure based on the BTTD test method, test results under specific evaluation indicators can be obtained. The detailed steps are as follows: (1) Take pictures of the failure results of the mixed test specimen based on the BTTD test method. With the help of digital image processing methods, the proportion of cohesive failure and adhesive failure can be given; (2) Combine the evaluation index results of the mixed test failure, and substitute the cohesive evaluation index results calculated in the first step into the results to solve the evaluation index results of the adhesive failure results, thereby realizing the quantitative expression of the asphalt-aggregate interface bonding failure behavior.

[0062] Furthermore, the BTTD testing apparatus of this embodiment is as follows: Figures 8-11 As shown in the diagram, the device consists of upper and lower tie rods, upper and lower parallel plates, upper and lower bases, and two sets of shaping fixtures. The upper and lower tie rods are accessories included with the universal tensile testing machine and are used for connecting the entire testing device and for tensile testing. The upper and lower parallel plates are self-made stainless steel parallel plates, providing a platform for placing the bases. The upper and lower bases are for the selected test aggregates (basalt and limestone), with dimensions of 70mm × 50mm × 15mm. The bases and parallel plates are bonded together with stone adhesive. Of the two sets of shaping fixtures, the 50mm × 50mm × 15mm fixture (the initial dimensions of the test area are planned to be 10mm × 10mm × 7mm) is a cohesive failure test fixture, and the other 50mm × 50mm × 1mm fixture is a hybrid failure test fixture.

[0063] The BTTD testing device has the following advantages:

[0064] (1) It can distinguish between cohesive failure and mixed failure. This BTTD test device includes two sets of fixtures, one for cohesive failure and one for mixed failure. Using this device, cohesive failure and mixed failure can be successfully distinguished. Furthermore, by determining the proportion of the two failure modes (cohesive and adhesive failure) in the mixed failure, the contributions of cohesive failure and adhesive failure to the mixed failure behavior can be obtained.

[0065] (2) It can accurately control test parameters such as test temperature and tensile rate. This set of equipment, through the combination of specific fixtures and UTM testing equipment, can accurately control process parameters such as temperature and tensile rate during the test, realize dynamic control and continuous recording of the entire test process, and make up for the current difficulty in controlling the test environment and parameters in the test of asphalt-aggregate bonding performance.

[0066] (3) It can effectively determine whether the test results are valid. Current test methods (such as PATTI) are almost all unable to determine the validity of test results, but instead include them all in the test results. In this test device, the validity of the test results can be determined by combining the failure location of the asphalt-aggregate (e.g., in cohesive failure, failure in the middle area of ​​the pull-out object is valid, while failure at the root is invalid) and the asphalt-base detachment situation, which significantly improves the scientific nature of the test results.

[0067] Finally, the stability and reproducibility of the proposed testing method are analyzed. By performing multiple parallel operations on the same test object at different testing times and with different operators, experimental results of different tests are obtained. Analysis of variance and t-test methods are used to analyze the significant differences in the experimental results to determine the reliability of the testing method.

[0068] Since the specific test objects and test environment must be determined in advance for the test, considering the research purpose of this embodiment, the test objects selected in this part include asphalt and aggregates. The asphalt is further divided into No. 70 base asphalt and SBS modified asphalt, and the aggregates are further divided into basalt and limestone. The test environment is -10℃ and 10℃.

[0069] Furthermore, quantitative testing methods for expressing asphalt-aggregate interfacial bond failure include:

[0070] During the experiment, the cohesiveness test of the asphalt-aggregate interface is highly similar to the procedure for the mixture test. This section will only use the mixture test as an example to elaborate on its operational process. Specifically, the mixture test includes the following key steps, such as... Figure 2 As shown:

[0071] (1) Preparations before the test include: heating the asphalt to be tested to a suitable pouring temperature to ensure that its fluidity meets the test requirements; applying release agent evenly to the base plate holding the test device and the two sets of shaping fixtures to prevent the material from sticking to the device during the test; combining the upper and lower parallel plates with the shaping fixtures to form a test area with a suitable space to provide a stable operating environment for subsequent tests.

[0072] (2) Molding the specimen. Slowly pour an appropriate amount of asphalt heated to a suitable temperature into the space enclosed by the parallel plates and the clamps, and then quickly squeeze the two parallel plates until they are in close contact with the shaping clamps.

[0073] (3) Scraping. After the poured asphalt has cooled sufficiently, use a scraper to remove excess binder from the surface to ensure that the specimen surface is flat.

[0074] (4) Heat preservation. Place the scraped specimen in a UTM heat preservation box and perform constant temperature treatment for 3 to 5 hours to ensure that the internal temperature of the specimen is uniform and stable.

[0075] (5) Test. After the heat preservation time is over, the specimen is quickly installed into the test device and kept for an additional hour before the test procedure is officially started.

[0076] It is worth noting that once the test procedure for testing the asphalt-aggregate interfacial bonding characteristics based on the BTTD tensile testing device is determined, the key parameters affecting the test results need to be identified to ensure the test's measurability and the accuracy of the results. In this section, after repeated experiments, it is considered that the test temperature, tensile rate, and area of ​​the cohesive failure behavior test region are the key test parameters in this procedure, such as... Figure 3 As shown, the details are as follows:

[0077] (1) The tensile rate is to meet the requirements of the asphalt-aggregate interface bonding failure test in accordance with the test temperature. If the tensile rate is too fast, the failure interface in the cohesive failure test may appear between the asphalt and aggregate, which will also fail to achieve the purpose of asphalt-asphalt fracture in the cohesive failure test. Figure 3 As shown in (b), if the stretching rate is too slow, the tensile strain will be large and the test process will be long, which is not conducive to test control or exceeds the UTM test range.

[0078] (2) The test temperature should not be too low or too high. If the temperature is too low, the tensile modulus of asphalt will be too high. In the cohesive failure behavior test, the failure interface is very likely to appear between the asphalt and aggregate, which will not achieve the purpose of testing the cohesive failure behavior. Figure 3 As shown in (c), excessively high temperatures result in excessive tensile strain in the asphalt and a low tensile modulus, which is not conducive to experimental operation and may cause experimental errors.

[0079] (3) The area of ​​the cohesive failure behavior test zone is designed to ensure that, under the selected test temperature and tensile rate, the failure interface appears in the middle of the test zone, rather than in the aggregate between the asphalt and the base or at the root of the test zone. Figure 3 As shown in (d).

[0080] Multiple tests were conducted to assess the three key parameters mentioned above: test temperature, tensile rate, and area of ​​the cohesive failure test region. Ultimately, it was determined that the optimal test temperatures for four groups of factors—70 base asphalt, SBS modified asphalt, basalt slab, and limestone slab—were -10℃ and 10℃. The tensile rate should be matched to the test temperature. Therefore, multiple tests were conducted, ultimately determining that the optimal tensile rate at -10℃ was 2 mm / min, and at 10℃, it was 5 mm / min. Regarding the selection of the test region size, its cross-sectional area directly affects the location of asphalt cohesive failure under low-temperature conditions; an excessively large cross-sectional area may lead to failure between the asphalt and the substrate. Therefore, a reasonable test region size needs to be determined based on experience or additional experiments. In this experiment, the size of the cohesive test region was determined to be 10mm × 10mm × 7mm under the most unfavorable conditions.

[0081] Furthermore, the process of selecting quantitative evaluation indicators for asphalt-aggregate interface bond failure includes:

[0082] After determining the test equipment and procedures, it is necessary to further select appropriate evaluation indicators to reflect the test results of the asphalt-aggregate interface bonding failure behavior.

[0083] Regarding the selection of evaluation indicators, given that this experiment relies on a UTM device for testing, which allows for real-time monitoring of stress and strain changes, a complete stress-strain curve can be obtained first. Based on this curve, the maximum tensile stress and its corresponding tensile strain can be directly extracted, and the maximum tensile modulus can be further calculated. Furthermore, for most asphalt samples that ultimately fail by fracture, the fracture energy consumed at fracture can be calculated by integrating the stress-strain curve. It is worth noting that due to the excellent properties of SBS modified asphalt, at a tensile speed of 5 mm / min and 10℃, the tested asphalt may not reach the fracture state within the range of the cohesiveness test, and will mostly exhibit a yield point. Therefore, for the cohesiveness test at 10℃, the stress and strain at the yield point are used as the evaluation criteria. The asphalt-aggregate interface bonding performance under four asphalt / aggregate combinations is evaluated through the yield stress, yield strain, and the calculated yield modulus and yield energy. In summary, the test objects, test conditions, and evaluation indicators determined in this study are shown in Table 1, where the schematic diagram of each evaluation indicator is shown below. Figure 4 As shown.

[0084] Table 1

[0085]

[0086] Furthermore, the process for determining the validity of test results includes:

[0087] After conducting tensile tests on the asphalt-aggregate interfacial bond failure behavior, the validity of the test results needs to be determined to decide whether the results can be used as a valid group for bond performance analysis. In previous asphalt-aggregate bond performance tests, the inability to effectively distinguish between cohesive and mixed-type failure modes led to a lack of clear criteria for determining test success, making it difficult to verify the validity of the test results. In this test, thanks to the introduction of the BTTD device, the two failure modes of asphalt—cohesive failure and mixed-type failure—were successfully distinguished, thus enabling the establishment of clear criteria for determining the success or failure of the test.

[0088] For cohesive testing, when asphalt failure or yielding occurs within the test area, such as... Figure 5 If the test fails, the test is considered successful; if the failure occurs at the root of the test area, the test is considered a failure.

[0089] For mixed-type tests, since both cohesive failure and adhesive failure occur, they are generally mixed-type failures (in extreme cases, asphalt-aggregate failure, which is adhesive failure). Therefore, there is generally no case of test failure. It is only necessary to use digital image processing technology to identify and calculate the ratio of cohesive failure and adhesive failure in the mixed-type failure behavior.

[0090] Furthermore, such as Figure 6 As shown, the process of quantitatively expressing the asphalt-aggregate interface bond failure behavior based on digital image processing technology includes:

[0091] After obtaining the results of the asphalt-aggregate interface cohesiveness and hybridization tests based on the BTTD device, the next step is to analyze the state of cohesiveness and adhesion failure evaluation indicators (tensile / yield modulus, fracture / yield energy) in the hybridization test, as well as their contribution (proportion) to the evaluation indicator values, so as to further quantitatively express the asphalt-aggregate interface bonding failure behavior.

[0092] In this embodiment, digital image processing is used to analyze the ratio of cohesive and adhesive failures at the hybrid failure interface, and the adhesive failure state is calculated based on the cohesive failure results. The detailed processing steps are as follows:

[0093] (1) For the test results of cohesive failure behavior, the results can be calculated directly based on the determined evaluation index.

[0094] (2) For the test results of mixed failure behavior, firstly, the two failure interfaces of the test specimen were placed in the order of one-to-one correspondence of the failure areas and photographed and stored; secondly, the two photographs were converted into grayscale images by image enhancement and image binarization; thirdly, the aggregate part and the asphalt part on each picture were marked by threshold segmentation to determine the corresponding position; fourthly, the asphalt / aggregate situation at the corresponding position was compared from the perspective of one-to-one correspondence of the two grayscale images, and the point corresponding to the asphalt-aggregate was marked as adhesive failure, and the point corresponding to the asphalt-asphalt was marked as cohesive failure; finally, the cohesive and adhesive failure areas in a single grayscale image were counted to obtain the ratio of the two failure modes.

[0095] (3) Substitute the evaluation index results of cohesive failure behavior in step (1) into step (2) to directly solve the evaluation index results of adhesive failure, and finally realize the quantitative expression of any mixed failure behavior.

[0096] Meanwhile, in order to improve the quality of experimental result processing, this embodiment uses Matlab software for programming to obtain a binary image, and imports it into ImageJ software to compare the failure categories (cohesive / adhesive failure) at different locations of the image, and then calculates the ratio of the two failure modes, thus realizing the efficient processing of the digital image processing in step (2) above.

[0097] The Matlab programming content is shown below:

[0098] `clc; clear all;`: Clears all content in the command window and clears all variables in the workspace.

[0099] `I1 = imread('D:\Desktop\matlab\1.png'); whos I1;`: Reads the image file and displays its information.

[0100] %I1=rgb2gray(I1);: This is commented-out code, originally used to convert a color image to a grayscale image.

[0101] I1 = im2uint8(I1); whos I1;: Converts the image data type to an 8-bit unsigned integer.

[0102] figure,imshow(uint8(I1)),title('Original Image','fontsize',16);: Displays image I1 and adds the title "Original Image".

[0103] [m,n]=size(I1); I1=double(I1);: Get the size of image I1 and convert the data type to double precision.

[0104] Th=160;%: Set the threshold Th to 160.

[0105] count=zeros(256,1); pcount=zeros(256,1);: Initializes two 256x1 zero matrices to store the number and proportion of each grayscale value.

[0106] for i=1:m ... end: A nested loop iterates through each pixel of the image and counts the number of each grayscale value.

[0107] count1=zeros(256,1); pcount1=zeros(256,1);: Initializes two 256x1 zero matrices to store the number and proportion of each grayscale value.

[0108] for i=1:m ... end: A nested loop iterates through each pixel of the image and counts the number of each grayscale value.

[0109] dw=0; x=0; for i=1:m ... end: Calculate the number of pixels greater than the threshold Th.

[0110] for i=Th:255 ... end: Calculate the proportion of each gray value in the total matrix and calculate the overall gray mean of the image.

[0111] Th2=Th; Thbest=0; dfc=0; dfcmax=0;: Initialize the threshold and related variables for inter-class variance.

[0112] while(Th2>=Th&&Th2<=255) ... end: Loop to find the optimal threshold.

[0113] T2=Thbest; J2=im2bw(J1,T2 / 255);: Binarization is performed using the optimal threshold.

[0114] figure,imshow(J2),title('Collections','fontsize',16);: Displays the binarized image and adds the title "Collections".

[0115] Importing the Matlab output into ImageJ, we obtain the process of comparing and analyzing binary image failure types based on ImageJ software, as follows: Figure 7 As shown.

[0116] exist Figure 7In the image, the failure areas of the original image and the binarized image correspond one-to-one. After binarization, the black and white contrast test areas are obtained. The white areas represent asphalt, and the black areas represent aggregate. In the image processed by Image J, the red areas represent aggregate, and the white areas represent asphalt. The red areas belong to the adhesive failure zone, accounting for 65.45% in d), while the white areas in this image account for 34.55%, belonging to the cohesive failure zone. This allows us to determine the proportion of adhesive and cohesive failures in the mixed-type test.

[0117] Furthermore, the process of verifying the feasibility of the quantitative expression test evaluation method for asphalt-aggregate interface bond failure behavior includes:

[0118] The ability of an experimental testing method to effectively distinguish the test object is a prerequisite for its acceptance, while its stability and reproducibility are key to its widespread application. This section will test the stability and reproducibility of the quantitative expression test method for asphalt-aggregate interfacial bond failure proposed in this embodiment.

[0119] To ensure the reliability of the test results, this section adopts the most unfavorable conditions for testing, namely, testing the asphalt-aggregate interface bond failure of the limestone + base asphalt combination at 10℃. Based on the principles of stability and reproducibility testing, this experiment is divided into two groups: one group consists of two testers conducting five sets of tests sequentially under the same test time and testing machine; the second group consists of one tester conducting five identical sets of tests at a different time on a different UTM machine. The differences in the results of these groups are compared to verify the stability and reproducibility of the test method. The experiment will obtain 15 sets of bond performance results. These 15 sets of test results are processed using digital image processing techniques, and the percentage of the bond failure zone is statistically summarized in Table 2. The reliability of the test results cannot be determined solely based on the bond failure results and the coefficient of variation.

[0120] Therefore, this embodiment combines analysis of variance (ANOVA) and a two-sample t-test to analyze the stability and reproducibility of these 15 sets of experimental results. Analysis of variance (ANOVA) is a statistical method used to test whether there is a significant overall difference between the means of three or more independent samples. Its core principle is to decompose the total data variation into between-group variation (caused by grouping factors) and within-group variation (caused by random error), and to determine whether the difference in means is statistically significant by comparing the magnitudes of these two components. The two-sample t-test is a statistical method used to compare whether there is a significant difference between the means of two independent or paired samples. Its core principle is to determine whether this difference is caused by random error by calculating the ratio of the difference in means between the two sets of data to the standard error, i.e., the t-statistic. Simultaneously, analysis of variance and variability analysis were performed on these 15 sets of data, and multi-sample t-tests and analysis of variance (ANOVA) were conducted using SPSS software, as shown in Table 2.

[0121] Table 2

[0122]

[0123] The first and second groups refer to five sets of experiments conducted by two researchers under the same experimental time and equipment. These five sets of data can be considered as five samples, each containing two replicates, making them suitable for one-way ANOVA. First, we test whether there is an overall difference in the means of the five groups. If the ANOVA is significant, then we perform pairwise comparisons. The results calculated using SPSS software are shown in Table 3 below.

[0124] Table 3

[0125]

[0126] Table 3 shows that the between-group mean square (SSB) is 519.30, the within-group mean square (SSW) is 241.42, the between-group mean square (MSB) is 129.83, and the within-group mean square (MSW) is 48.28. Therefore, the F-value is the ratio of MSB to MSW, i.e., F = MSB / MSW = 2.69. Referring to the F-distribution table, where n1 = 4 and n2 = 5, the critical value F0.05(4.5) = 5.19 (α = 0.05) is obtained. The actual F = 2.69 < 5.19, and the P-value > 0.05. The ANOVA results show that the means of the five groups are not significantly different at the α = 0.05 level. Therefore, no further post-hoc pairwise T-tests are needed, indicating that the experiment has good reproducibility and stability, and the data are highly reliable.

[0127] The second and third groups refer to five identical experiments conducted by the same experimenter at different times on different UTM machines. A two-sample t-test can be used for them, and the calculated t-value is 0.37 with 8 degrees of freedom. Referring to the t-distribution table, the critical value for the two-tailed test at the α=0.05 level is 2.306. Since the calculated t-value (0.37) is less than the critical value, the corresponding p-value is greater than 0.05. Therefore, at the significance level of α=0.05, there is no significant difference in the means of the two groups, indicating that the experiment has good stability and reproducibility under these conditions.

[0128] The key technologies of this invention are: (1) Establishing a quantitative evaluation system for failure behavior. Based on the characteristics of stress-strain curves, a multi-dimensional evaluation index system was constructed: the failure intensity was characterized by parameters such as fracture modulus and fracture energy, and the viscoelastic response was evaluated by yield modulus and yield energy. Furthermore, by combining Matlab threshold segmentation + ImageJ area statistics digital image processing technology, the calculation method of cohesive and adhesive contribution in mixed failures was analyzed, realizing a refined quantitative analysis of interface failure behavior. (2) Establishing a test validity criterion driven by failure location: for cohesive tests, it is clearly stipulated that the failure occurs inside the test area as a valid result; for mixed tests, the failure contribution ratio is directly quantified through image analysis. This solves the defect of traditional methods that accept invalid data in whole because they cannot distinguish the failure type. At the same time, the reproducibility of the test was verified. In the analysis of variance (ANOVA) and t-test, the data results were all p>0.05, showing no significant difference, and the coefficient of variation was controlled within the engineering acceptable range of 4.69%~15.31%. This empirically proves that the method has good stability and reproducibility.

[0129] The positive effects of this invention are as follows: Based on UTM testing, this invention clarifies the selection criteria for raw materials (base asphalt, SBS modified asphalt, basalt, and limestone), and establishes a key parameter system including temperature field (-10℃ to 10℃), tensile rate (2-5 mm / min), and test area. By constructing multi-dimensional evaluation indicators such as stress-strain curves, tensile modulus, and fracture energy, and combining digital image processing technology, a standardized testing and analysis method is proposed that can distinguish between mixed failure modes and determine the proportion of cohesive and adhesive failures in mixed failures, laying the foundation for accurate evaluation of interfacial bonding performance. The main conclusions are as follows:

[0130] (1) Establish a quantitative evaluation system for failure behavior. Based on the characteristics of stress-strain curves, a multi-dimensional evaluation index system was constructed: the failure intensity was characterized by parameters such as fracture modulus and fracture energy, and the viscoelastic response was evaluated by yield modulus and yield energy. Furthermore, by combining Matlab threshold segmentation and ImageJ area statistics digital image processing technology, the calculation method of the contribution of cohesion and adhesion in hybrid failures was analyzed, realizing a refined quantitative analysis of interface failure behavior.

[0131] (2) A failure location-driven test validity criterion was established: for cohesive tests, it was clearly stipulated that a failure occurring within the test area was a valid result; for mixed-type tests, the contribution ratio of failure was directly quantified through image analysis. This solves the problem of traditional methods accepting invalid data because they cannot distinguish between failure types. Simultaneously, the reproducibility of the tests was verified. In both ANOVA and t-tests, the data results showed p>0.05, indicating no significant difference, and the coefficient of variation was controlled within the acceptable engineering range of 4.69%~15.31%. This empirically demonstrates that the proposed method possesses good stability and reproducibility.

[0132] The present invention also provides a computer, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the method described thereon.

[0133] The present invention also provides a storage medium having a computer program stored thereon, which, when executed by a processor, implements the method described thereon.

[0134] The above are merely preferred embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for quantitatively analyzing asphalt-aggregate interface failure behavior based on image processing, characterized by, Includes the following steps: Pull-out tests were conducted on the asphalt-aggregate interface using a universal testing machine to obtain stress-strain curves. Evaluation indicators were then extracted based on the stress-strain curves, and the test results of cohesive failure behavior were calculated based on the evaluation indicators. Digital image processing methods were used to acquire images of the failure interface of hybrid failure specimens. Based on the acquired images, the area ratio of cohesive failure region to adhesive failure region was identified and calculated. Based on the test results of cohesive failure behavior and the area ratio, the evaluation index results of the adhesive failure region are calculated to achieve a quantitative expression of the bonding failure behavior of the asphalt-aggregate interface. The process of calculating the evaluation index results of the adhesive failure region includes: calculating the strength index results and energy index results based on the test results of cohesive failure behavior and the set test area; establishing a mathematical relationship between the overall evaluation index of mixed failure and the evaluation indices of cohesive failure and adhesive failure; determining the contribution weights of cohesive failure mode and adhesive failure mode in mixed failure based on the area ratio obtained from digital image processing; substituting the test results of cohesive failure behavior and the contribution weights of the two failure modes in mixed failure into the mathematical relationship of mixed failure, and combining the test results of mixed failure, to solve for the evaluation index results of the adhesive failure region.

2. The method for quantitatively analyzing asphalt-aggregate interface failure behavior based on image processing according to claim 1, characterized in that, The process of extracting evaluation indicators based on stress-strain curves includes: The continuous stress-strain data collected during the pull-out test were recorded as curves, and the characteristic points on the curves were identified. When the specimen fails by fracture, the tensile modulus is calculated using the maximum tensile stress and strain corresponding to the peak point of the stress-strain curve, and the fracture energy is obtained by integrating the stress-strain curve. When the specimen yields but does not fracture, the yield modulus is calculated by the stress corresponding to the yield plateau on the stress-strain curve and the strain corresponding to the stress, and the yield energy is obtained by calculating the integral area under the stress-strain curve from the beginning of the test to the end of the yielding stage. Strength indices are constructed based on the tensile modulus and yield modulus, and energy indices are constructed based on the fracture energy and yield energy. Based on the characteristics of the selected asphalt material, at least one strength index and at least one energy index are selected as evaluation indicators for the asphalt-aggregate interfacial bonding performance.

3. The method for quantitatively analyzing asphalt-aggregate interface failure behavior based on image processing according to claim 1, characterized in that, The process of identifying and calculating the area ratio of cohesive failure regions to adhesive failure regions based on the acquired images includes: After the test specimen completes the test, the two failure interfaces are arranged in an axisymmetric order corresponding to the damage areas and images are collected. The acquired image is enhanced and binarized to obtain a grayscale image; Based on the grayscale image, an adaptive threshold segmentation algorithm is used to perform image binarization processing to separate the asphalt area from the aggregate area; In the binarized image, the asphalt-asphalt contact area is identified as the cohesive failure area, and the asphalt-aggregate contact area is identified as the adhesive failure area. The number of pixels in the cohesive failure region and the adhesive failure region are counted separately, and the area ratio of the cohesive failure region to the adhesive failure region is calculated.

4. The method for quantitatively analyzing asphalt-aggregate interface failure behavior based on image processing according to claim 3, characterized in that, The process of using an adaptive threshold segmentation algorithm for image binarization to separate the asphalt region from the aggregate region and obtain the area ratio of the cohesive failure region to the adhesion failure region includes: The two binarized images are arranged in an axisymmetric order that corresponds one-to-one with the damaged areas; A planar coordinate system is established based on two images placed symmetrically, and the planar coordinate positions of each part are obtained; Compare the failure results of plane coordinate positions that are symmetrical. When both symmetrical positions are asphalt, it is recorded as cohesive failure. When one of the symmetrical positions is an aggregate part, it is recorded as adhesive failure. The number of pixels in the cohesive failure region and the adhesive failure region are counted separately, and the area ratio of the cohesive failure region to the adhesive failure region is calculated.

5. The method for quantitative analysis of asphalt-aggregate interface failure behavior based on image processing according to claim 3, characterized in that, The acquired images were enhanced and binarized using the Matlab image processing platform. The process of processing images using the Matlab image processing platform includes: The original color image was enhanced for contrast and filtered for noise using Matlab image processing functions. The enhanced color image was then converted to a grayscale image using the rgb2gray function.

6. The method for quantitative analysis of asphalt-aggregate interface failure behavior based on image processing according to claim 1, characterized in that, After achieving a quantitative expression of the asphalt-aggregate interface bond failure behavior, the evaluation method feasibility verification is also included. Among them, the stability and reproducibility of the quantitative expression results of the asphalt-aggregate interface bonding failure behavior were analyzed using the analysis of variance method and the two-sample t-test method.

7. A computer comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the method as described in claim 1.

8. A storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, it implements the method as described in claim 1.

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