A method for evaluating the crack resistance of drainage asphalt mixtures
Patent Information
- Application Number
- CN202611029876.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-07-10
- Publication Date
- 2026-09-29
AI Technical Summary
[0003]现有抗裂性能评价方法（如小梁弯曲试验、半圆弯拉试验或圆盘形紧凑拉伸试验）通常需要对试件进行切割、开槽或粘接夹具等前处理，操作繁琐，且对于大空隙排水沥青混合料，测试结果的变异系数常超过20%，重复性较差，难以满足工程现场快速质量控制的需求
[0014]本发明的一种排水沥青混合料抗裂性能评价方法，采用以下步骤：制作试件，采用标准击实仪成型马歇尔试件，其中试件保持完整，无需切割、开槽和钻孔；对所述试件进行间接拉伸加载试验，记录加载过程中的荷载与位移数据，绘制荷载-位移曲线；确定曲线上的峰值荷载点，计算峰值前能量A，其中峰值前能量A为荷载-位移曲线从位移零点到峰值点之间与位移轴围成的面积；在峰值后的下降段上选取多个不同荷载比例对应的点，通过这些点拟合一条直线，将该直线延长至与位移轴相交，计算由所述直线、峰值点处的垂线以及位移轴所围成的三角形面积，作为峰值后能量B；利用断裂指数公式计算断裂指数，根据断裂指数的大小评价混合料的抗裂性能；通过上述过程，达到了在抗裂性能评价过程中具有操作简便、重复性好，能快速评价的效果。
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Abstract
Description
Technical Field
[0001] This invention relates to the field of road engineering material performance testing technology, and in particular to a method for evaluating the crack resistance of drainage asphalt mixtures. Background Technology
[0002] Drainage asphalt mixture, as a type of porous asphalt material with a porosity typically as high as 15% to 25%, is widely used in highway surface layers, urban expressways, and tunnel paving due to its excellent permeability, drainage, noise reduction, anti-skid, and anti-drift properties. It is one of the key materials for improving road driving safety and comfort.
[0003] Existing methods for evaluating crack resistance (such as beam bending test, semi-circular bending test or disc compact tensile test) usually require pretreatment of the specimens, such as cutting, grooving or bonding fixtures, which is cumbersome. Moreover, for large-void drainage asphalt mixtures, the coefficient of variation of the test results often exceeds 20%, and the repeatability is poor, making it difficult to meet the needs of rapid quality control on the engineering site.
[0004] In conclusion, it is essential to propose a simple, repeatable, and rapid evaluation method for assessing the crack resistance of drainage asphalt mixtures. Summary of the Invention
[0005] The purpose of this invention is to provide a method for evaluating the crack resistance performance of drainage asphalt mixtures, which achieves the objectives of being simple to operate, having good repeatability, and being able to conduct rapid evaluations during the crack resistance performance evaluation process.
[0006] To achieve the above objectives, the present invention provides a method for evaluating the crack resistance of drainage asphalt mixtures, comprising the following steps: Specimens were prepared using a standard compactor to form Marshall specimens, which remained intact without the need for cutting, grooving, or drilling. An indirect tensile loading test was performed on the specimen, and the load and displacement data during the loading process were recorded to plot the load-displacement curve. Determine the peak load point on the curve and calculate the energy A before the peak, where the energy A before the peak is the area enclosed by the load-displacement curve from the zero displacement point to the peak point and the displacement axis. On the descending segment after the peak, select multiple points corresponding to different load ratios, fit a straight line through these points, extend the straight line to intersect the displacement axis, and calculate the area of the triangle enclosed by the straight line, the perpendicular line at the peak point, and the displacement axis as the energy B after the peak. The fracture index is calculated using the fracture index formula, and the crack resistance of the mixture is evaluated based on the magnitude of the fracture index.
[0007] In the process of preparing the specimens, a standard compactor is used to form Marshall specimens, in which the specimens remain intact without the need for cutting, grooving, or drilling: Weigh out aggregates, mineral powder and asphalt. Heat the aggregates to 190°C and the asphalt to 150°C. Control the temperature of the mixing pot to 185°C. Mix the aggregates and asphalt for 90 seconds, then add the mineral powder and mix for another 90 seconds to obtain an asphalt mixture. Preheat the mold to 165℃~175℃, put the mixed material into the mold, and use a standard compactor to compact both sides of the specimen 50 times each, with the compaction temperature controlled at 165℃~175℃. Demold the specimen and leave it at room temperature for 24 hours to maintain its original integrity without cutting, grooving, or drilling.
[0008] In the steps of conducting an indirect tensile loading test on the specimen, recording the load and displacement data during the loading process, and plotting the load-displacement curve: The specimen was placed in an environmental chamber at 25℃ for 2 hours. Place the specimen in the indirect tensile test fixture; An electronic universal testing machine was used, with a loading rate set to 50 mm / min, to conduct a one-time loading destructive test on the specimen; Record the load and vertical displacement data, and plot the collected data as a load-displacement curve.
[0009] Among the steps, in determining the peak load point on the curve, the energy A before the peak is calculated, where the energy A before the peak is the area enclosed by the load-displacement curve from the zero displacement point to the peak point and the displacement axis: Starting from the beginning of the curve, traverse the data points to the peak point, and use the trapezoidal rule to numerically integrate the area under the curve: For the interval of the i-th data point (between adjacent points i-1 and i), the area of the infinitesimal element is:
[0010] Where F is the load (N) and D is the displacement (mm). Then the energy A before the peak value is: .
[0011] In the step of selecting multiple points corresponding to different load ratios on the descending segment after the peak, fitting a straight line through these points, extending this line to intersect the displacement axis, and calculating the area of the triangle enclosed by the straight line, the perpendicular line at the peak point, and the displacement axis, which is used as the energy B after the peak: Select three load proportion points.
[0012] In the step of selecting multiple points corresponding to different load ratios on the descending segment after the peak, fitting a straight line through these points, extending this line to intersect the displacement axis, and calculating the area of the triangle enclosed by the straight line, the perpendicular line at the peak point, and the displacement axis, which is used as the energy B after the peak: The post-peak energy B is calculated as follows: Let the equation of the fitted line be... Intersection with the displacement axis The peak point displacement is ,but ,in The load value at the peak displacement is used to fit the straight line.
[0013] The fracture index formula is: fracture index = (B / A+B)×100%.
[0014] This invention discloses a method for evaluating the crack resistance of drainage asphalt mixtures, comprising the following steps: preparing specimens, molding Marshall specimens using a standard compactor, wherein the specimens are kept intact without cutting, grooving, or drilling; conducting indirect tensile loading tests on the specimens, recording load and displacement data during the loading process, and plotting a load-displacement curve; determining the peak load point on the curve, calculating the pre-peak energy A, where the pre-peak energy A is the area enclosed by the load-displacement curve from the zero displacement point to the peak point and the displacement axis; selecting multiple points corresponding to different load ratios on the descending segment after the peak, fitting a straight line through these points, extending the line to intersect the displacement axis, and calculating the area of the triangle enclosed by the straight line, the perpendicular line at the peak point, and the displacement axis as the post-peak energy B; calculating the fracture index using the fracture index formula, and evaluating the crack resistance of the mixture based on the magnitude of the fracture index; through the above process, achieving the effects of simple operation, good repeatability, and rapid evaluation in the crack resistance evaluation process. Attached Figure Description
[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0016] Figure 1 This is a flowchart of the steps in the method for evaluating the crack resistance of drainage asphalt mixtures according to the present invention.
[0017] Figure 2 This is a flowchart of steps S100 of the present invention.
[0018] Figure 3This is a flowchart of steps S200 of the present invention.
[0019] Figure 4 This is a schematic diagram of the cracking test fixture of the present invention.
[0020] Figure 5 This is a schematic diagram of the cracking test loading process of the present invention.
[0021] Figure 6 This is the load-displacement curve diagram of the present invention.
[0022] Figure 7 This is the original load-displacement curve origin correction diagram of the present invention.
[0023] Figure 8 The present invention adds a new right-side slope line graph to the new load-displacement curve based on 70%, 75%, and 80% of the load peak value. Detailed Implementation
[0024] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application.
[0025] The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The singular forms “a,” “the,” and “the” used in this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any or all possible combinations of one or more of the associated listed items.
[0026] It should be understood that although the terms first, second, third, etc., may be used in this application to describe various information, such information should not be limited to these terms. These terms are only used to distinguish information of the same type from one another. For example, without departing from the scope of this application, first information may also be referred to as second information, and similarly, second information may also be referred to as first information. Depending on the context, the word "if" as used herein may be interpreted as "when," "when," or "in response to determination."
[0027] Please see Figures 1-8 This invention provides a method for evaluating the crack resistance of drainage asphalt mixtures, comprising the following steps: S100: Prepare specimens by forming Marshall specimens using a standard compactor, ensuring the specimens remain intact without cutting, grooving, or drilling. S200: Conduct an indirect tensile loading test on the specimen, record the load and displacement data during the loading process, and plot the load-displacement curve; S300: Determine the peak load point on the curve and calculate the energy A before the peak, where the energy A before the peak is the area enclosed by the load-displacement curve from the zero displacement point to the peak point and the displacement axis. S400: Select multiple points corresponding to different load ratios on the descending segment after the peak, fit a straight line through these points, extend the straight line to intersect the displacement axis, and calculate the area of the triangle enclosed by the straight line, the perpendicular line at the peak point, and the displacement axis as the energy B after the peak. S500: The fracture index is calculated using the fracture index formula, and the crack resistance of the mixture is evaluated based on the magnitude of the fracture index.
[0028] In this embodiment, firstly, specimens are prepared using a standard compactor to form Marshall specimens, which are kept intact without cutting, grooving, or drilling. Then, an indirect tensile loading test is performed on the specimens, and the load and displacement data during the loading process are recorded to plot a load-displacement curve. Next, the peak load point on the curve is determined, and the pre-peak energy A is calculated, where pre-peak energy A is the area enclosed by the load-displacement curve from the zero displacement point to the peak point and the displacement axis. Then, multiple points corresponding to different load ratios are selected on the descending segment after the peak, and a straight line is fitted through these points. This line is extended to intersect the displacement axis, and the area of the triangle enclosed by the straight line, the perpendicular line at the peak point, and the displacement axis is calculated as the post-peak energy B. Subsequently, the fracture index is calculated using the fracture index formula, and the crack resistance of the mixture is evaluated based on the magnitude of the fracture index. Through the above process, the crack resistance evaluation process is characterized by its simplicity, good repeatability, and rapid evaluation capabilities.
[0029] Furthermore, in the process of preparing the specimens, Marshall specimens are formed using a standard compactor, wherein the specimens remain intact without the need for cutting, grooving, or drilling: S101: Weigh the aggregate, mineral powder and asphalt, heat the aggregate to 190℃, heat the asphalt to 150℃, control the temperature of the mixing pot to 185℃, mix the aggregate and asphalt for 90s, then add the mineral powder and mix for 90s to obtain the asphalt mixture. S102: Preheat the mold to 165℃~175℃, put the mixed material into the mold, and use a standard compactor to compact both sides of the specimen 50 times each, with the compaction temperature controlled at 165℃~175℃. S103: Demold the specimen and leave it at room temperature for 24 hours to maintain its original integrity without cutting, grooving or drilling.
[0030] In this embodiment, aggregates, mineral powder, and asphalt are weighed first. The aggregates are heated to 190°C, and the asphalt is heated to 150°C. The temperature of the mixing pot is controlled at 185°C. The aggregates and asphalt are mixed for 90 seconds, and then the mineral powder is added and mixed for another 90 seconds to obtain an asphalt mixture. The mold is then preheated to 165°C to 175°C. The mixed mixture is placed into the mold, and the specimen is compacted 50 times on each side using a standard compactor. The compaction temperature is controlled at 165°C to 175°C. The specimen is then demolded and placed at room temperature for 24 hours to maintain its original integrity without the need for cutting, grooving, or drilling.
[0031] Furthermore, in the steps of conducting an indirect tensile loading test on the specimen, recording the load and displacement data during the loading process, and plotting the load-displacement curve: S201: Place the specimen in a 25℃ ambient chamber for 2 hours; S202: Place the specimen in the indirect tensile test fixture; S203: Using an electronic universal testing machine, with a loading rate set to 50 mm / min, a one-time loading failure test is performed on the specimen; S204: Record load and vertical displacement data, and plot the collected data as a load-displacement curve.
[0032] In this embodiment, the specimen is placed in an environmental chamber at 25°C for 2 hours; then the specimen is placed in an indirect tensile testing fixture; then an electronic universal testing machine is used to perform a one-time loading failure test on the specimen with a loading rate of 50 mm / min; then the load and vertical displacement data are recorded, and the collected data are plotted as a load-displacement curve.
[0033] Furthermore, in the step of determining the peak load point on the curve and calculating the energy A before the peak, where the energy A before the peak is the area enclosed by the load-displacement curve from the zero displacement point to the peak point and the displacement axis: Starting from the beginning of the curve, traverse the data points to the peak point, and use the trapezoidal rule to numerically integrate the area under the curve: For the interval of the i-th data point (between adjacent points i-1 and i), the area of the infinitesimal element is:
[0034] Where F is the load (N) and D is the displacement (mm). Then the energy A before the peak value is: .
[0035] Furthermore, on the descending segment after the peak, multiple points corresponding to different load ratios are selected. A straight line is fitted through these points, and this line is extended to intersect the displacement axis. The area of the triangle enclosed by the straight line, the perpendicular line at the peak point, and the displacement axis is calculated as the energy B after the peak. Select three load proportion points.
[0036] Furthermore, on the descending segment after the peak, multiple points corresponding to different load ratios are selected. A straight line is fitted through these points, and this line is extended to intersect the displacement axis. The area of the triangle enclosed by the straight line, the perpendicular line at the peak point, and the displacement axis is calculated as the energy B after the peak. The post-peak energy B is calculated as follows: Let the equation of the fitted line be... Intersection with the displacement axis The peak point displacement is ,but ,in The load value at the peak displacement is used to fit the straight line.
[0037] Furthermore, in the step of calculating the fracture index using the fracture index formula and evaluating the crack resistance of the mixture based on the magnitude of the fracture index: The fracture index formula is: fracture index = (B / A+B)×100%.
[0038] Example 1: 1. Specimen Preparation: Marshall specimens were prepared using a standard compaction apparatus according to the specifications in T0702-2025 of the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTGE3410-2025). The specific steps are as follows: Weigh the aggregate, mineral powder, and asphalt according to the design gradation (the amount of asphalt is determined according to the target void ratio; in this embodiment, high-viscosity modified asphalt is used, and the asphalt-aggregate ratio is 5.0%). The aggregate is heated to 190°C, the asphalt is heated to 150°C, the mixing pot temperature is controlled at 185°C, the aggregate and asphalt are mixed for 90 seconds, and then mineral powder is added and mixed for 90 seconds to obtain asphalt mixture. A standard compactor was used, and the mold was preheated to 165℃~175℃. The mixed material was poured into the mold, and each side was compacted 50 times, with the compaction temperature controlled at 165℃~175℃. After demolding, the specimens are left at room temperature for 24 hours to maintain their original, intact state, without the need for cutting, grooving, or drilling.
[0039] 2. Load-displacement curve test: The specimen was placed in an environmental chamber at 25℃ for 2 hours. Referencing the indirect tensile test fixture (12.7 mm wide pressure strip, 50.8 mm inner radius of curvature, and rounded ends) in JTG3410-2025 T0742, place the specimen in the fixture; An electronic universal testing machine was used, with a loading rate set to 50 mm / min, to conduct a one-time loading destructive test on the specimen; The testing machine automatically records load and vertical displacement data, with a sampling frequency of no less than 100Hz, and plots the collected data into load-displacement curves, such as... Figure 4 and Figure 5 As shown.
[0040] 3. Fracture index calculation: (1) Correction of the origin of the original load-displacement curve, see Figure 7 .
[0041] Read raw load-displacement data from an Excel file; Find the maximum load value (peak force); In the rising section of the curve, take three points corresponding to the peak forces of 5%, 10%, and 15%, and perform linear fitting on these three points to obtain the slope line on the left: y=kx+b. Determine two key intersection points: ① Left intersection point: the intersection of the left slope line and the X-axis, i.e., x = -b / k (displacement offset); ② Curve intersection point: the first intersection point of the left slope line and the original curve. Generate new load-displacement data, perform "translation correction" on the original data so that the curve starts from the origin (0, 0), and the new displacement = original displacement - ① the x-value of the left intersection point. At the same time, replace the "bending segment" before the curve intersection point with the straight line segment y=kx passing through the origin. The splicing method is as follows:
[0042] (2) Calculation of the energy A before the peak: Starting from the beginning of the curve, iterate through the data points until the peak point. Use the trapezoidal rule to numerically integrate the area under the curve: For the interval of the i-th data point (between adjacent points i-1 and i), the area of the infinitesimal element is:
[0043] Where F is the load (N) and D is the displacement (mm). Then the energy A before the peak value is:
[0044] In this embodiment, the measured peak load Fpeak = 14387.8164 N, the peak displacement Dpeak = 2.5824 mm (after origin correction), and the calculated value A = 23497.8497 N.mm.
[0045] (3) Calculation of post-peak energy B: Three characteristic load points are determined: 80%, 75%, and 70% of the peak load, respectively. , , ,See Figure 8 .
[0046] Starting from the data points after the peak point, search backwards to find the point where the load first equals or is very close to the aforementioned characteristic value, and its corresponding displacement. , , .
[0047] Place the three points ( ), ( ), ( Performing linear regression (least squares method) to fit a straight line equation:
[0048] Calculate the intersection point of the line and the displacement axis (let...) ):
[0049] Calculate the straight line at the peak displacement Load value at .
[0050]
[0051] perpendicular line from the peak point ( ), displacement axis ( The area of the right triangle formed by the fitted line and the peak value is taken as the peak energy B. .
[0052] In this embodiment, the slope of the fitted line is k = -2472.5622, the intercept is b = 20901.8387, and the calculated values are D0 = 8.4535 mm and Fpeak,line = 14516.6941 N. The length of the base of the triangle is 8.4535 - 2.5824 = 5.8711 mm, and the height is 14516.6941 N. Therefore, B = 0.5 × 5.8711 × 14516.6941 = 42615.4814 N·mm.
[0053] Fracture index calculation: .
[0054] Example 2: To verify repeatability, four parallel specimens with the same gradation were molded under the conditions of Example 1, and the fracture index was tested and calculated for each. The results were 64.4577%, 62.0379%, 75.6559%, and 65.7515%, respectively. The average value was 66.9758%, the standard deviation was 5.9880%, and the coefficient of variation was only 8.94%, which is much lower than the 23% coefficient of variation of the traditional small beam three-point bending test, indicating that the method has excellent repeatability.
[0055] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the disclosure herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein.
[0056] It should be understood that this application is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope.
Claims
1. A method for evaluating the crack resistance of drainage asphalt mixtures, characterized in that, Includes the following steps: Specimens were prepared using a standard compactor to form Marshall specimens, which remained intact without the need for cutting, grooving, or drilling. An indirect tensile loading test was performed on the specimen, and the load and displacement data during the loading process were recorded to plot the load-displacement curve. Determine the peak load point on the curve and calculate the energy A before the peak, where the energy A before the peak is the area enclosed by the load-displacement curve from the zero displacement point to the peak point and the displacement axis. On the descending segment after the peak, select multiple points corresponding to different load ratios, fit a straight line through these points, extend the straight line to intersect the displacement axis, and calculate the area of the triangle enclosed by the straight line, the perpendicular line at the peak point, and the displacement axis as the energy B after the peak. The fracture index is calculated using the fracture index formula, and the crack resistance of the mixture is evaluated based on the magnitude of the fracture index.
2. The method for evaluating the crack resistance of drainage asphalt mixtures as described in claim 1, characterized in that, In the process of preparing specimens, Marshall specimens are formed using a standard compactor, where the specimens remain intact without the need for cutting, grooving, or drilling: Weigh out aggregates, mineral powder and asphalt. Heat the aggregates to 190°C and the asphalt to 150°C. Control the temperature of the mixing pot to 185°C. Mix the aggregates and asphalt for 90 seconds, then add the mineral powder and mix for another 90 seconds to obtain an asphalt mixture. Preheat the mold to 165℃~175℃, put the mixed material into the mold, and use a standard compactor to compact both sides of the specimen 50 times each, with the compaction temperature controlled at 165℃~175℃. Demold the specimen and leave it at room temperature for 24 hours to maintain its original integrity without cutting, grooving, or drilling.
3. The method for evaluating the crack resistance of drainage asphalt mixtures as described in claim 1, characterized in that, In the steps of conducting an indirect tensile loading test on the specimen, recording the load and displacement data during the loading process, and plotting the load-displacement curve: The specimen was placed in an environmental chamber at 25℃ for 2 hours. Place the specimen in the indirect tensile test fixture; An electronic universal testing machine was used, with a loading rate set to 50 mm / min, to conduct a one-time loading destructive test on the specimen; Record the load and vertical displacement data, and plot the collected data as a load-displacement curve.
4. The method for evaluating the crack resistance of drainage asphalt mixtures as described in claim 1, characterized in that, In the step of determining the peak load point on the curve and calculating the energy A before the peak, where the energy A before the peak is the area enclosed by the load-displacement curve from the zero displacement point to the peak point and the displacement axis: Starting from the beginning of the curve, traverse the data points to the peak point, and use the trapezoidal rule to numerically integrate the area under the curve: For the interval of the i-th data point (between adjacent points i-1 and i), the area of the infinitesimal element is: Where F is the load (N) and D is the displacement (mm). Then the energy A before the peak value is: 。 5. The method for evaluating the crack resistance of drainage asphalt mixtures as described in claim 1, characterized in that, In the step of selecting multiple points corresponding to different load ratios on the descending segment after the peak, a straight line is fitted through these points. This straight line is extended until it intersects the displacement axis. The area of the triangle enclosed by the straight line, the perpendicular line at the peak point, and the displacement axis is calculated as the energy B after the peak. Select three load proportion points.
6. The method for evaluating the crack resistance of drainage asphalt mixtures as described in claim 5, characterized in that, In the step of selecting multiple points corresponding to different load ratios on the descending segment after the peak, a straight line is fitted through these points. This straight line is extended until it intersects the displacement axis. The area of the triangle enclosed by the straight line, the perpendicular line at the peak point, and the displacement axis is calculated as the energy B after the peak. The post-peak energy B is calculated as follows: Let the equation of the fitted line be... Intersection with the displacement axis The peak point displacement is ,but ,in The load value at the peak displacement is used to fit the straight line.
7. The method for evaluating the crack resistance of drainage asphalt mixtures as described in claim 1, characterized in that, In the step of calculating the fracture index using the fracture index formula and evaluating the crack resistance of the mixture based on the magnitude of the fracture index: The fracture index formula is: fracture index = (B / A+B)×100%.