Asphalt pavement crack propagation loading device, detection method and evaluation method

Abstract

The invention provides an asphalt pavement crack propagation loading device, a detection method and an evaluation method. The asphalt pavement crack propagation loading device comprises a reaction frame, an actuator connected with the reaction frame, a telescopic rod connected with the actuator and a contact plate placed below the telescopic rod. The reaction frame comprises a base and a stand column, the base comprises four cross beams with the same length, two first longitudinal beams with the same length and two second longitudinal beams, the four cross beams are arranged in parallel at equal intervals, the first longitudinal beams are connected with the two sides of the four cross beams arranged in parallel, the length of the first longitudinal beams is the same as the width of the four cross beams after arrangement, and the second longitudinal beams are connected with the stand column. The two ends of the second longitudinal beam are connected with the two cross beams in the middle respectively, the second longitudinal beam is located in the middle of the two cross beams in the middle, and the length of the second longitudinal beam is equal to the distance between the cross beams; one side of a stand column of the counter-force frame is connected with four corners of the base, and the other side is in contact with the ground. The pavement crack propagation loading device provided by the invention can accurately detect the propagation path of the crack.

Description

Technical Field

[0001] The invention relates to an asphalt pavement crack evaluation method, in particular to an asphalt pavement crack expansion loading device, a detection method and an evaluation method. Background Art

[0002] Under the repeated action of vehicle loads, various diseases will appear on the asphalt pavement. Coupled with the influence of natural environment such as wind, rain and snow, the structural layers of the asphalt pavement will suffer certain damage, such as breakage and breakage. The road surface will be damaged, and the strength and stiffness will be reduced. The road service level will become lower and lower, and the service life of the asphalt pavement will be seriously shortened.

[0003] At present, there is no specific method for calculating the expansion of cracks in asphalt pavements, no specific indicators for evaluation, and no specific test method. The numerical values ​​of the expansion of cracks in asphalt pavements are not quantified, the range of activity is large, and the error is also large, which brings a series of difficulties to actual projects. Summary of the invention

[0004] One of the purposes of the present invention is to provide an asphalt mixture specimen crack extension loading device to solve the problem of large numerical error of crack extension in existing crack extension devices.

[0005] The second purpose of the present invention is to provide a method for detecting crack extension in an asphalt pavement to solve the problem of large errors in existing crack extension calculations.

[0006] The third purpose of the present invention is to provide a method for evaluating crack expansion in an asphalt pavement to solve the problem of inaccurate evaluation of existing crack expansion.

[0007] One of the purposes of the present invention is achieved in that:

[0008] An asphalt pavement crack expansion loading device comprises a reaction frame, an actuator connected to the reaction frame, a telescopic rod connected to the actuator, and a contact plate placed under the telescopic rod;

[0009] The reaction frame includes a base and a column, the base includes four cross beams of the same length, two first longitudinal beams of the same length and two second longitudinal beams of the same length, the four cross beams are arranged in parallel with equal spacing, the first longitudinal beam is connected to both sides of the four cross beams arranged in parallel, the length of the first longitudinal beam is the same as the width of the four cross beams after arrangement, the two ends of the second longitudinal beam are respectively connected to the two cross beams in the middle, the second longitudinal beam is in the middle of the two cross beams in the middle, and the length of the second longitudinal beam is the spacing between the cross beams;

[0010] One side of the column of the reaction frame is connected to the four corners of the base, and the other side is in contact with the ground.

[0011] The second object of the present invention is achieved in this way:

[0012] A method for detecting crack expansion of an asphalt pavement comprises the following steps:

[0013] Sa1. Prepare at least 9 asphalt mixture specimens, the asphalt mixture specimens comprising asphalt, gravel and admixtures; the front surface of the asphalt mixture specimens is sprayed with matte paint, and grid lines are drawn, and the surface after the grid lines are drawn is sprayed with artificial speckles; a pre-crack is cut in the middle of the bottom of the asphalt mixture specimen, and the specification of the asphalt mixture specimen is 100mm×100mm×150mm;

[0014] Sa2. Setting the asphalt pavement crack extension loading device as one of the purposes of the invention, placing the asphalt mixture specimen under the contact plate, starting the non-contact measuring instrument, and recording the initial coordinates of the front of the asphalt mixture specimen at the initial time;

[0015] Sa3. Start the actuator and apply a load amplitude of 20N to each asphalt mixture specimen. The dynamic load cycle is sinusoidal and the load application time is 60s.

[0016] Sa4. Observe the front of the asphalt mixture specimen using a non-contact measuring instrument, and record the coordinate value of the asphalt mixture specimen and the time corresponding to the coordinate value every preset time period;

[0017] Sa5. Continuously change the load amplitude to 40N, 60N, 80N, 100N, 120N, 140N, 160N, 180N and 200N. Each load application time is 60s. Repeat step Sa4.

[0018] Sa6. Compare the coordinate values ​​of the asphalt mixture specimen at each time point with the initial coordinates at the initial time, determine the missing coordinates at each time point, and determine the crack propagation path that changes with time based on the missing coordinates at each time point.

[0019] The third object of the present invention is achieved in this way:

[0020] A method for evaluating crack growth in an asphalt pavement comprises the following steps:

[0021] Sb1. Prepare at least 9 asphalt mixture specimens, the asphalt mixture specimens include asphalt, gravel and admixtures; three vertical strain gauges are pasted on one side of the asphalt mixture specimen in the asphalt pavement crack extension loading device, and three transverse strain gauges are pasted on the other side; a pre-crack is cut in the middle of the bottom of the asphalt mixture specimen, and the specification of the asphalt mixture specimen is 100mm×100mm×150mm;

[0022] Sb2. Setting one of the purposes of the invention asphalt pavement crack expansion loading device;

[0023] Sb3. Start actuator 1, apply a load amplitude of 20N to the asphalt mixture specimen, the dynamic load cycle is sinusoidal, and the load application time is 60s;

[0024] Sb4. Turn on the strain collector, collect the values ​​of three vertical strain gauges 6 at preset time intervals, and calculate the average value ε 1 , collect the values ​​of the three transverse strain gauges 7 and calculate the average value ε 2 , according to the average value ε 1 and the mean value ε 2 , and get the γ value at each time point. The γ value is: γ=(ε 1 -ε 2 ) / ε 1 =1-ε 2 / ε 1 ;

[0025] Sb5. Continuously change the load amplitude to 40N, 60N, 80N, 100N, 120N, 140N, 160N, 180N and 200N respectively, each load application time is 60s, and repeat step Sb4;

[0026] Sb6. Determine the final γ value at each time point based on the γ value of all asphalt mixture specimens at each time point;

[0027] Sb7. According to the crack propagation path of the asphalt mixture specimen changing with time as described in the second object of the invention, the final crack width changing with time is determined, and the relationship curve between the final γ value and the final crack width is plotted according to the crack width changing with time and the final γ value at each time point;

[0028] Sb8. Determine the evaluation results corresponding to different widths based on the relationship curve between the final γ value and the final crack width.

[0029] Furthermore, the specific method of determining the final γ value at each time point in step Sb6 is:

[0030] Sb6-1. Group the asphalt mixture specimens, with the same number of specimens in each group;

[0031] Sb6-2. According to the γ value of each asphalt mixture specimen at each time point, determine the average γ value of each group of asphalt mixture specimens at each time point;

[0032] Sb6-3. Average the average γ value of each group of asphalt mixture specimens at each time point to determine the final γ value at each time point.

[0033] Furthermore, the specific method for determining the final crack width varying with time in step Sb7 is:

[0034] Sb7-1. Determine the crack width of each asphalt mixture specimen over time according to the crack propagation path of the asphalt mixture specimen over time;

[0035] Sb7-2. According to the crack width of each asphalt mixture specimen over time, determine the average crack width of each group of asphalt mixture specimens over time;

[0036] Sb7-3. Average the average crack width of each group of asphalt mixture specimens that changes with time to determine the final crack width that changes with time.

[0037] The asphalt pavement crack expansion loading device of the present invention applies a load to an asphalt mixture specimen and calculates the crack expansion path, thereby providing an effective device for calculating asphalt pavement crack expansion. The asphalt pavement crack expansion loading device is simple and can be reused, thereby reducing calculation costs.

[0038] The present invention evaluates the expansion depth, width and direction of cracks in asphalt pavement under the action of vehicle dynamic load, which is helpful to understand the crack law of asphalt pavement and provide a reference for calculating the life, quality and service level of asphalt pavement.

[0039] The present invention is based on the theories of material mechanics, theoretical mechanics, elasticity mechanics and fracture mechanics, and is combined with experiments. The calculation method is accurate, which effectively makes up for the deficiencies in previous asphalt mixture crack expansion assessment, saves materials and time, and improves the accuracy of asphalt mixture crack expansion data and assessment results. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 Schematic diagram of the crack extension loading device for asphalt mixture specimens.

[0041] Figure 2 This is the relationship curve between crack width and γ value.

[0042] Figure 3 Schematic diagram of crack propagation path.

[0043] Among them, 1. actuator; 2. telescopic rod; 3. reaction frame; 4. contact plate; 5. asphalt mixture specimen; 6. vertical strain gauge for measurement; 7. transverse strain gauge for measurement; 8. artificial speckle; 9. grid line; 10. pre-crack. DETAILED DESCRIPTION

[0044] The present invention is further described below.

[0045] like Figure 1As shown, an embodiment of the present invention provides an asphalt pavement crack expansion loading device including: a reaction frame 3, an actuator 1 connected to the reaction frame 3, a telescopic rod 2 connected to the actuator, and a contact plate 4 placed under the telescopic rod 2.

[0046] A contact plate 4 is placed below the telescopic rod 2 so that when the actuator 1 applies a load downward to the asphalt mixture specimen 5, the force is more uniform.

[0047] The reaction frame 3 includes a base and columns. The base includes four cross beams of the same length, two first longitudinal beams of the same length and two second longitudinal beams of the same length. The four cross beams are arranged in parallel with equal spacing. The two first longitudinal beams are respectively connected to the two sides of the four cross beams arranged in parallel. The four cross beams and the first longitudinal beams are perpendicular to each other. The length of the first longitudinal beam is the same as the width of the four cross beams after arrangement. The two ends of the second longitudinal beam are respectively connected to the two middle cross beams. The second longitudinal beam is in the middle position of the two middle cross beams. The length of the second longitudinal beam is the spacing between the cross beams. One side of the four columns of the reaction frame 3 is respectively connected to the four corners of the base, and the other sides are in contact with the ground.

[0048] The actuator 1 and the reaction frame 3 can be connected by screws, and the actuator 1 and the telescopic rod 2 can be connected and fixed by welding.

[0049] The embodiment of the present invention also provides a method for detecting crack propagation of an asphalt pavement, comprising the following steps:

[0050] Sa1. Prepare at least 9 asphalt mixture specimens 5, the asphalt mixture specimens 5 include asphalt, gravel and admixtures; the front surface of the asphalt mixture specimen 5 is sprayed with matte paint, and grid lines 9 are drawn, and the surface after the grid lines 9 are drawn is sprayed with artificial speckles 8; a pre-crack 10 is cut in the middle of the bottom of the asphalt mixture specimen 5, and the specifications of the asphalt mixture specimen are 100mm×100mm×150mm.

[0051] Asphalt mixture specimen 5 includes asphalt, gravel and admixtures, and the distances between adjacent grid lines are equal.

[0052] Matt paint and artificial speckles are sprayed on the surface of the asphalt mixture specimen 5, which makes it easier to detect changes in coordinates, and for a measurement method with higher precision, the result is more accurate.

[0053] Sa2. Set up an asphalt pavement crack expansion loading device, place the asphalt mixture specimen under the contact plate, start the non-contact measuring instrument, and record the initial coordinates of the front side of the asphalt mixture specimen 5 at the initial time.

[0054] The non-contact measuring instrument can capture and identify the grid lines on the front of the asphalt mixture specimen. When determining the coordinates, since the vertical coordinate spacing has been determined, the horizontal coordinate spacing can be determined according to the measurement accuracy. For example, if a higher measurement accuracy is required, the spacing between adjacent horizontal coordinates is 0.01mm, and if a lower measurement accuracy is required, the horizontal coordinate spacing is 1mm. When there are no cracks in the asphalt mixture specimen, the coordinates of the grid lines on the front of the asphalt mixture specimen can be captured by the non-contact measuring instrument.

[0055] Sa3. Start the actuator 1 and apply a downward load with an amplitude of 20N to each asphalt mixture specimen 5. The dynamic load cycle is sinusoidal and the load application time is 60s.

[0056] The actuator 1 applies a force with an amplitude of 20N to the reaction frame 3. The reaction frame 3 makes the direction of the force applied by the actuator 1 downward. The reaction frame 3 determines the magnitude and direction of the force by keeping the asphalt mixture specimen 5 balanced. The actuator 1 determines the extension direction of the crack by applying a load to the asphalt mixture specimen.

[0057] Sa4. Observe the front side of the asphalt mixture specimen 5 using a non-contact measuring instrument, and record the coordinate value of the asphalt mixture specimen 5 and the time corresponding to the coordinate value every preset time period.

[0058] In order to determine the coordinate value of the asphalt mixture specimen 5 more accurately, the coordinate value of the asphalt mixture specimen 5 and the time corresponding to the coordinate value are detected every preset time period.

[0059] Sa5. Continuously change the amplitude of the load to 40N, 60N, 80N, 100N, 120N, 140N, 160N, 180N and 200N respectively. Each load application time is 60s. Repeat step Sa4.

[0060] When no load is applied to the asphalt mixture specimens and when the load amplitude is changed afterwards, the horizontal axis spacing is the same.

[0061] The time corresponding to the coordinate value is relative. For example, the initial time is 0. If the preset time period is 2s, the time of the 2nd second is 2, and the final time recorded for each asphalt mixture time is 600s.

[0062] Sa6. Compare the coordinate values ​​of the asphalt mixture specimen at each time point with the initial coordinates at the initial time, determine the missing coordinates at each time point, and determine the crack propagation path that changes with time based on the missing coordinates at each time point.

[0063] like Figure 2As shown, at a certain moment, the coordinate values ​​of each time point recorded at that moment and before that moment are compared with the initial coordinates. When a load is applied to the asphalt mixture specimen 5, many cracks will be generated in the asphalt mixture specimen 5. When cracks are determined based on the missing coordinates, cracks with more missing coordinates are taken as main cracks, that is, crack extension paths.

[0064] The embodiment of the present invention also provides a method for evaluating crack expansion of an asphalt pavement, comprising the following steps:

[0065] Sb1. Make at least 9 asphalt mixture specimens, which include asphalt, gravel and admixtures; three vertical strain gauges are pasted on one side of the asphalt mixture specimen in the asphalt pavement crack extension loading device, and three transverse strain gauges are pasted on the other side; a pre-crack is cut in the middle of the bottom of the asphalt mixture specimen, and the specification of the asphalt mixture specimen is 100mm×100mm×150mm;

[0066] Sb2. Set up the above-mentioned asphalt pavement crack expansion loading device.

[0067] Sb3. Start the actuator 1 and apply a downward load with an amplitude of 20N to the asphalt mixture specimen 5. The dynamic load cycle is sinusoidal and the load application time is 60s.

[0068] Asphalt mixture is composed of asphalt, gravel and various admixtures. Under the action of vertical external force, the asphalt mixture is continuously compressed, the lateral deformation is relatively small, and the γ value is relatively large; as the load increases, the lateral deformation is relatively large, and the γ value gradually decreases. Due to the supporting effect of gravel aggregate, the γ value has a stable period; as the load increases again, the lateral deformation becomes larger and larger, and the γ value becomes smaller and smaller. At this time, the damage of the asphalt mixture is more serious.

[0069] Sb4. Turn on the strain collector, collect the values ​​of three vertical strain gauges 6 at preset time intervals, and calculate the average value ε 1 , collect the values ​​of the three transverse strain gauges 7 and calculate the average value ε 2 , according to the average value ε 1 and the mean value ε 2 , and obtain the γ value at each time point.

[0070] The value of γ is: γ=(ε 1 -ε 2 ) / ε 1 =1-ε 2 / ε 1 .

[0071] The collection time of the values ​​of the vertical strain gauge and the transverse strain gauge is the same, and the preset time period for collecting the values ​​of the strain gauge is the same as the preset time period for recording the coordinate values ​​in the above embodiment.

[0072] Sb5. The load amplitude is continuously changed to 40N, 60N, 80N, 100N, 120N, 140N, 160N, 180N and 200N, respectively. Each load application time is 60s, and step Sb4 is repeated;

[0073] F(t)=P×│sin(2×π×f×t+α 0 )│

[0074] F is the dynamic amplitude that changes with the applied time; P is the applied load amplitude; f is the frequency; α 0 is the initial phase; t is the application time (0-60s).

[0075] Sb6. Determine the final γ value at each time point based on the γ value of all asphalt mixture specimens at each time point.

[0076] Each asphalt mixture specimen is grouped, and the number of specimens in each group is the same. For example, the number of asphalt mixture specimens is 9, which are divided into 3 groups, and the number of asphalt mixture specimens in each group is 3. According to the γ value of each asphalt mixture specimen at each time point, the average γ value of each group of asphalt mixture specimens at each time point is determined, and the average of the average γ values ​​of each group of asphalt mixture specimens at each time point is calculated to determine the final γ value at each time point.

[0077] like Figure 3 As shown, Sb7. According to the crack extension path of the asphalt mixture specimen 5 in the above embodiment, the final crack width that changes with time is determined, and according to the crack width that changes with time and the final γ value at each time point, a relationship curve between the final γ value and the final crack width is drawn. The width of the same crack at the tail and the tip is different, and the widest width of the crack is taken as the width of the crack. Figure 3 The horizontal axis is the final crack width, and the vertical axis is the final γ value.

[0078] The crack extension paths corresponding to different asphalt mixture specimens at the same time may be different, so the crack widths are different. The final crack width is calculated by calculating the average of the crack widths of different asphalt mixture specimens 5 at the same time. In order to ensure the consistency of the calculation results of the present invention, the asphalt mixture specimens are grouped in the same way as the grouping method for calculating the final γ value at each time point.

[0079] According to the crack propagation path of asphalt mixture specimen 5 changing with time, the crack width of each asphalt mixture specimen changing with time is determined. According to the crack width of each asphalt mixture specimen changing with time, the average crack width of each group of asphalt mixture specimens changing with time is determined. The average of the average crack widths of each group of asphalt mixture specimens changing with time is calculated to determine the final crack width changing with time.

[0080] Sb8. Determine the evaluation results corresponding to different widths based on the relationship curve between the final γ value and the final crack width.

[0081] Depend on Figure 2 It can be seen that: Point A is the beginning compression stage of asphalt mixture, and the gaps between aggregates are the largest; Point B is in the stage of minimum compression of pores between aggregates. This time is in the initial skeleton structure, that is, the γ value is in the stable stage in the BC stage, and the skeleton is subjected to external loads; the skeleton is gradually damaged in the CD stage, and the stability between the skeletons is destroyed; it is completely damaged in the DE stage.

[0082] According to the damage rule of material mechanics, the asphalt mixture in the AC section is in a good stage (the γ value at point C decreases by 33.3%), and the asphalt mixture structure in the CE stage is damaged (the γ value at point D decreases by 39.3%; the γ value at point E decreases by 46.7%). After a large number of experiments, the maximum width of the crack in the asphalt mixture at point B is 0.78mm; the maximum width of the crack in the asphalt mixture at point C is 2mm; the maximum width of the crack in the asphalt mixture at point D is 2.5mm; and the maximum width of the crack in the asphalt mixture at point E is 2.8mm.

[0083] As shown in Table 1, the final evaluation index of asphalt pavement crack expansion is as follows:

[0084] Table 1. Evaluation indexes of crack expansion in asphalt pavement

[0085]

[0086] As shown in Table 2, the laboratory conducted multiple groups of asphalt pavement crack expansion assessment index tests (the same asphalt mixture), with at least 3 parallel specimens in each group.

[0087] Table 2. Crack expansion evaluation index of asphalt pavement

[0088]

[0089] As shown in Table 3, in order to verify the reliability of this method, test specimens were also cut from the actual road surface for testing. The test method was the same as that of the present invention to obtain indicators.

[0090] Table 3. Crack expansion evaluation index of asphalt pavement

[0091]

[0092]

[0093] It can be seen from Table 3 that the asphalt pavement crack expansion evaluation index changes very little, so the evaluation result obtained by applying the evaluation method of the present invention is stable and reliable.

Claims

1. An asphalt pavement crack expansion loading device, characterized in that: It includes a reaction frame, an actuator connected to the reaction frame, a telescopic rod connected to the actuator, and a contact plate placed under the telescopic rod; The reaction frame includes a base and a column, the base includes four cross beams of the same length, two first longitudinal beams of the same length and two second longitudinal beams of the same length, the four cross beams are arranged in parallel with equal spacing, the first longitudinal beam is connected to both sides of the four cross beams arranged in parallel, the length of the first longitudinal beam is the same as the width of the four cross beams after arrangement, the two ends of the second longitudinal beam are respectively connected to the two cross beams in the middle, the second longitudinal beam is in the middle of the two cross beams in the middle, and the length of the second longitudinal beam is the spacing between the cross beams; One side of the column of the reaction frame is connected to the four corners of the base, and the other side is in contact with the ground.

2. A method for detecting crack expansion in an asphalt pavement, characterized in that: The following steps are involved: Sa1. Prepare at least 9 asphalt mixture specimens, the asphalt mixture specimens comprising asphalt, gravel and admixtures; the front surface of the asphalt mixture specimens is sprayed with matte paint, and grid lines are drawn, and the surface after the grid lines are drawn is sprayed with artificial speckles; a pre-crack is cut in the middle of the bottom of the asphalt mixture specimen, and the specification of the asphalt mixture specimen is 100mm×100mm×150mm; Sa2. Set the asphalt pavement crack extension loading device according to claim 1, place the asphalt mixture specimen under the contact plate, start the non-contact measuring instrument, and record the initial coordinates of the front side of the asphalt mixture specimen at the initial time; Sa3. Start the actuator and apply a load amplitude of 20N to each asphalt mixture specimen. The dynamic load cycle is sinusoidal and the load application time is 60s. Sa4. Use a non-contact measuring instrument to observe the front of the asphalt mixture specimen, and record the coordinate value of the asphalt mixture specimen and the time corresponding to the coordinate value every preset time period; Sa5. Continuously change the load amplitude to 40N, 60N, 80N, 100N, 120N, 140N, 160N, 180N and 200N. Each load application time is 60s. Repeat step Sa4. Sa6. Compare the coordinate values ​​of the asphalt mixture specimen at each time point with the initial coordinates at the initial time, determine the missing coordinates at each time point, and determine the crack propagation path that changes with time based on the missing coordinates at each time point.

3. A method for evaluating crack expansion in asphalt pavement, characterized in that: The following steps are involved: Sb1. Prepare at least 9 asphalt mixture specimens, the asphalt mixture specimens include asphalt, gravel and admixtures; three vertical strain gauges are pasted on one side of the asphalt mixture specimen in the asphalt pavement crack extension loading device, and three transverse strain gauges are pasted on the other side; a pre-crack is cut in the middle of the bottom of the asphalt mixture specimen, and the specification of the asphalt mixture specimen is 100mm×100mm×150mm; Sb2. Set the asphalt pavement crack expansion loading device according to claim 1; Sb3. Start actuator 1, apply a load amplitude of 20N to the asphalt mixture specimen, the dynamic load cycle is sinusoidal, and the load application time is 60s; Sb4. Turn on the strain collector, collect the values ​​of the three vertical strain gauges 6 at every preset time period, and calculate the average value ε1, collect the values ​​of the three transverse strain gauges 7, and calculate the average value ε2, and obtain the γ value at each time point according to the average values ​​ε1 and ε2, and the γ value is: γ=(ε1-ε2) / ε1=1-ε2 / ε1; Sb5. Continuously change the load amplitude to 40N, 60N, 80N, 100N, 120N, 140N, 160N, 180N and 200N respectively, each load application time is 60s, and repeat step Sb4; Sb6. Determine the final γ value at each time point based on the γ value of all asphalt mixture specimens at each time point; Sb7. According to the crack propagation path of the asphalt mixture specimen changing with time in claim 2, determine the final crack width changing with time, and draw a relationship curve between the final γ value and the final crack width according to the crack width changing with time and the final γ value at each time point; Sb8. Determine the evaluation results corresponding to different widths based on the relationship curve between the final γ value and the final crack width.

4. The asphalt pavement crack expansion evaluation method according to claim 3 is characterized in that: The specific method of determining the final γ value at each time point in step Sb6 is: Sb6-1. Group the asphalt mixture specimens, with the same number of specimens in each group; Sb6-2. According to the γ value of each asphalt mixture specimen at each time point, determine the average γ value of each group of asphalt mixture specimens at each time point; Sb6-3. Average the average γ value of each group of asphalt mixture specimens at each time point to determine the final γ value at each time point.

5. The asphalt pavement crack expansion evaluation method according to claim 4 is characterized in that: The specific method of determining the final crack width varying with time in step Sb7 is: Sb7-1. Determine the crack width of each asphalt mixture specimen over time according to the crack propagation path of the asphalt mixture specimen over time; Sb7-2. According to the crack width of each asphalt mixture specimen over time, determine the average crack width of each group of asphalt mixture specimens over time; Sb7-3. Average the average crack width of each group of asphalt mixture specimens that changes with time to determine the final crack width that changes with time.

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