Testing device and method for evaluating rheological property of asphalt mixture

Abstract

The invention belongs to the technical field of pavement performance detection and evaluation, and relates to a testing device and method for evaluating the rheological property of an asphalt mixture, and the method comprises the following steps: S1, fixing a test sample formed by the asphalt mixture on a sample loading rotary table of the testing device; s2, setting the required load level, maximum deformation quantity and test temperature according to test requirements; s3, controlling the environment temperature to reach the test temperature through the test device, and keeping the temperature; s4, the weight of the load is adjusted, the test sample is driven to rotate, the test wheel rolls on the surface of the test sample according to the annular wheel trace to grind and rub the test sample, and multiple load cycles are carried out till the deformation result reaches the set maximum deformation quantity under the action of the nth load cycle; and S5, calculating the anti-load rheological index of the test sample. According to the method, the rheological property of the asphalt mixture can be accurately and quantitatively represented, the real deformation of a pavement structure is accurately reflected, and the scientificity and rationality of rheological property evaluation are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of road performance detection and evaluation, and relates to a testing device and method for evaluating the rheological properties of asphalt mixture. Background Art

[0002] Rheological properties refer to the quantitative relationship between the strain and stress of an object under the action of external forces. Asphalt mixture, as a typical viscoelastic material, has significant temperature sensitivity, and its rheological properties reflect its deformation characteristics under specific environment and load conditions. Under load, asphalt mixture first produces viscoelastic deformation, accompanied by a certain viscous rheological deformation. When the load is removed, the elastic deformation part can be instantly restored, while the viscoelastic deformation part recovers successively with the passage of time, but the viscous rheological deformation cannot be restored, thus forming "permanent deformation". The rheological properties of asphalt mixture depend on the properties of asphalt materials, the bonding strength between asphalt and mineral aggregates, the grading type, and the uniformity of asphalt mixture. Asphalt mixtures with high rheological properties are more prone to plastic deformation such as rutting, which affects the smoothness and driving safety of the road surface. Moreover, severe deformation can easily cause the loosening and shedding of the surface aggregate of the road surface, destroying the integrity of the road surface. Therefore, how to accurately evaluate the rheological properties of asphalt mixtures has important guiding significance for the long-term service performance of asphalt pavements.

[0003] At present, there are two methods to evaluate the rheological properties of asphalt mixtures: modulus and deformation.

[0004] The modulus method is mainly tested through static creep tests. The data of specimen deformation changing with time during the whole loading process is measured and recorded through static creep tests, and then the creep stiffness modulus of the material is calculated. The stress-strain relationship under specific temperature and time conditions is used to reflect the rheological properties of the material under unconfined stress. The larger the stiffness modulus value, the better the deformation capacity of the asphalt mixture and the more stable the structure. However, static creep tests mostly use beams or cylindrical specimens, which are in an unconfined state and have certain differences from the service environment of actual plate-type and confined pavement structures; moreover, static creep tests are mostly static loads in the form of monotonic loading, which is significantly different from the cyclic dynamic load form of reciprocating rolling of wheels in actual use, and the gap between loading and unloading is not considered in the static loading process, so that the pavement material is in a constant load state, so that the test process lacks a short elastic deformation recovery stage. Due to the large difference between the static creep test process and the actual use state of asphalt pavement, it is difficult for the test results to accurately reflect the true deformation characteristics of the pavement structure.

[0005] The evaluation method of deformation is currently mainly carried out through indoor rutting tests. By repeatedly rolling the test wheel on the test piece surface, the flow deformation accumulates and finally forms rutting-like plastic deformation. The number of test wheel rolling within a unit deformation is used as the evaluation index, that is, the dynamic stability is used to reflect the anti-wheel load rheological properties of asphalt mixture. In the rutting test, the test wheel is driven by a crank connecting rod to perform reciprocating linear motion. First, the test wheel is non-uniform in the straight line segment. It is always at a higher speed in the middle of the specimen, while the speed at the starting and ending positions is lower. There are also starting and braking phenomena, which makes it difficult to simulate the whole process of stable wheel load action; secondly, frequent stopping and starting also make it difficult to achieve high-speed and continuous loading, which reduces the test efficiency. Secondly, the reciprocating of the test wheel represents that the direction of the force applied by the test wheel on the surface of the specimen has changed within a test cycle. In the actual road environment, driving has directionality, which is inconsistent with the actual use of the road surface. Finally, the evaluation index is the deformation in the second half of loading (45-60 min) or the number of load actions required to reach the specified deformation (25 mm), and is expressed as the number of test wheel rollings required to achieve unit deformation. This evaluation index can only reflect the anti-rheological properties of the specimen through the final load-deformation result, but cannot reflect the occurrence process of load-deformation, nor can it accurately characterize the rheological behavior characteristics of each stage or period.

[0006] In summary, the existing indoor simulation test methods and result evaluation of rheological properties have technical deficiencies in that they cannot accurately characterize and accurately reflect the actual deformation of the pavement structure, and cannot meet the current technical needs of asphalt pavement material design and performance evaluation. Therefore, it is necessary to develop a new indoor simulation test device and method for the rheological properties of asphalt mixtures based on actual needs. Summary of the invention

[0007] In view of the technical problem that the existing rheological evaluation of asphalt mixture in the above-mentioned background technology has great deficiencies, the present invention provides a testing device and method for evaluating the rheological properties of asphalt mixture.

[0008] The present invention improves the wheel load action mode and uses the load resistance rheological index as an evaluation index, thereby being able to accurately and quantitatively characterize the rheological properties of asphalt mixtures, accurately reflecting the actual deformation of the pavement structure, and improving the scientificity and rationality of the rheological performance evaluation.

[0009] In order to achieve the above object, the technical solution adopted by the present invention is:

[0010] A method for evaluating the rheological properties of asphalt mixture comprises the following steps:

[0011] S1. Fixation of test sample

[0012] Fixing a test sample formed of an asphalt mixture on a sample-carrying rotating table of a testing device;

[0013] S2. Parameter setting

[0014] According to the test requirements, set the required load level P, maximum deformation L and test temperature T;

[0015] S3. Constant temperature treatment of test samples

[0016] The temperature control device of the test device controls the ambient temperature to reach the test temperature T, and maintains it at this temperature for 3 to 6 hours;

[0017] S4. Performance test

[0018] Start the test device, apply a load level P to the test sample, and drive the test sample to rotate at the same time. The test wheel on the test device rolls on the surface of the test sample according to the circular wheel track to crush and rub the test sample, and performs multiple load cycles along the circular wheel track; record the load deformation amount corresponding to the test sample at each time point, and finally obtain the deformation result l of the test sample under the action of the nth load cycle n Reach the set maximum deformation L;

[0019] S5. Performance evaluation

[0020] Calculate the load rheological index LRI of the test sample at the test temperature T T , the calculation formula is as follows:

[0021]

[0022] Where, LRI T is the load resistance rheological index, J / mm;

[0023] N is the total number of cycles of rolling and kneading applied during the test, times;

[0024] l n is the deformation result under the nth load cycle, mm;

[0025] L is the set maximum deformation, i.e. the deformation result under the Nth load cycle, mm;

[0026] P is the set load level, kN;

[0027] T is the set test temperature, ℃.

[0028] It is further defined that in step S2, the maximum deformation L is 30 mm to 40 mm, and the load level P is 50 kN.

[0029] It is further defined that the specific process of step S4 is:

[0030] Start the test device, adjust the weight of the load in the loading device to P, drive the test sample to rotate with the sample rotating table, and use the test wheel at the bottom of the loading device to roll and rub the test sample. Record the expansion and contraction of the loading device at each time point during one rotation of the sample rotating table, that is, the load deformation amount corresponding to the test sample, and calculate the deformation result l of the test sample under the load during one rotation. n ;

[0031] One rotation of the sample rotating table is considered as one load cycle, until the deformation result of the test sample under the action of the nth load cycle is l n Reach the set maximum deformation L.

[0032] It is further defined that in step S4, the deformation result l of the test sample under the load during one rotation is n , is the mean of the deformation values ​​at each time point.

[0033] It is further defined that the step S5 further includes calculating the load rheological rate LRR and the load rheological energy LRE;

[0034] The calculation method of the load rheological rate LRR and the load rheological energy LRE is:

[0035] The number of load cycles is taken as the horizontal axis, and the deformation result l of the test sample under each load cycle is n The deformation-load number change curve is drawn with as the vertical coordinate. The load rheological rate LRR is the slope at each point on the deformation-load number change curve; the load rheological energy LRE is the total area under the deformation-load number change curve.

[0036] It is further defined that the smaller the load rheological rate LRR is, the larger the load rheological energy LRE is, indicating that the load rheological ability of the asphalt mixture of the test sample is stronger.

[0037] A testing device for implementing the method for evaluating the rheological properties of asphalt mixture, the testing device comprising a constant temperature testing box and a sample loading rotating table, a loading device, a driving mechanism and a computer processor respectively placed in the constant temperature testing box;

[0038] The constant temperature test box is equipped with a temperature control device for controlling the ambient temperature in the constant temperature test box to reach the test temperature T, and transmitting the test temperature data to the computer processor;

[0039] The sample loading rotating table is used to place the test sample;

[0040] A load is set on the top of the loading device, and a test wheel is set at the bottom of the loading device; the loading device is placed above the sample rotating table, and a constant load is applied to the test sample through the load, and the test wheel is in contact with the surface of the test sample to roll and rub the test sample;

[0041] A displacement sensor is also provided beside the loading device, and the displacement sensor is located between the test wheel and the load, and is used to obtain the expansion and contraction amount of the loading device in the vertical direction, and transmit the expansion and contraction amount to the computer processor;

[0042] The driving mechanism is connected to the sample rotating table and is used to drive the sample rotating table to drive the test sample to rotate;

[0043] The driving mechanism is provided with a revolution counter for recording the number of load cycles and transmitting the recorded data to a computer processor;

[0044] The computer processor is connected to the temperature control device, the revolution counter and the displacement sensor respectively, and is used to receive various data during the test and calculate the load rheological index LRI. T , load rheological rate LRR and load resistance rheological energy LRE.

[0045] It is further defined that the loading device includes a pressure rod, a force transmission column and a gantry loading frame which are respectively placed in a constant temperature test box and connected in sequence from top to bottom; the pressure rod is placed horizontally, the force transmission column is placed vertically, the test wheel is placed at the bottom of the gantry loading frame, one end of the pressure rod is movably connected to the bottom surface of the constant temperature test box, the load is placed on the other end of the pressure rod, and the displacement sensor is placed on the force transmission column.

[0046] It is further defined that the gantry loading frame is a gantry-shaped structure formed by connecting a cross bar and two support bars, a steering bearing is arranged at the bottom end of each of the two support bars, there are two test wheels, a test wheel is arranged at the bottom of each steering bearing and the test wheel is connected to the steering bearing; the force transmission column is connected to the cross bar.

[0047] It is further defined that the test device also includes a support device placed in the constant temperature test box, the support device includes a first support frame, a second support frame and a crossbeam respectively located below the pressure rod; the displacement sensor is placed on the crossbeam and is located beside the force transmission column;

[0048] The first support frame and the second support frame are both placed vertically, the sample rotating table is located between the first support frame and the second support frame, one end of the pressure rod is connected to the bottom surface of the constant temperature test box through the first support frame; the bottom end of the second support frame is connected to the bottom surface of the constant temperature test box, and the top end of the second support frame is connected to the first support frame through a horizontally placed crossbeam; a force transmission hole is arranged on the crossbeam, and the force transmission column passes through the force transmission hole and is connected to the gantry loading frame.

[0049] Compared with the prior art, the present invention has the following beneficial effects:

[0050] 1. The present invention discloses a testing device and method for evaluating the rheological properties of asphalt mixtures, which can accurately simulate the rolling and kneading state of vehicle loads under indoor conditions, and realize quantitative and accurate evaluation of the rheological properties of asphalt pavement materials.

[0051] 2. The present invention realizes the continuous and unidirectional rolling and kneading effect of the test wheel on the test sample by driving the test sample to rotate through the sample rotating table, which can simulate the real load environment of the asphalt mixture pavement material during the driving process of the car, and ensure the scientific and reasonable effect of the rolling and kneading effect; at the same time, the design of the sample rotating table and the loading device can meet the requirements of high-speed operation of the equipment, ensure the continuity of the rolling and kneading load, and greatly improve the efficiency of the rheological effect on the test sample.

[0052] 3. The present invention is based on the proposed load rheological index LRI T Evaluation indicators can realize the scientific characterization and evaluation of the load-resistant rheological properties of asphalt mixture materials and structures, making the rheological performance evaluation results of pavement materials and structures more accurate and reliable, and can better serve the design and performance evaluation of asphalt pavement materials.

[0053] 4. The testing device provided by the present invention is simple in structure, scientific and reasonable, easy to implement, and can be used in standardized production. It has extremely important practical engineering significance for studying the load-resistant rheological properties of asphalt pavement materials and structures. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 It is a plan view of the testing device of the present invention;

[0055] Figure 2 It is a schematic diagram of the structure of the loading device of the present invention;

[0056] Figure 3 It is a schematic diagram of the structure of the support device of the present invention;

[0057] Figure 4 It is a schematic diagram of the support frame structure of the present invention;

[0058] Figure 5 It is a schematic diagram of the wheel track position of the present invention;

[0059] Figures 1 to 5In: 1. Constant temperature test box, 11. Base, 111. Raised platform, 12. Temperature control device, 13. Sample rack, 2. Sample rotating table, 21. Thrust bearing, 3. Support device, 31. First support frame, 311. Support column, 312. Fixed pin, 32. Second support frame, 33. Crossbeam, 331. Positioning end plate, 332. Square force transmission hole, 4. Loading device, 41. Pressure rod, 411. Load, 412. Rubber pad, 42. Gantry loading frame, 421. Force transmission column, 422. Steering bearing, 423. Fork frame, 43. Test wheel, 431. Rolling friction device, 5. Test sample, 51. Wheel track, 6. Computer processor, 61. Motor, 611. Rotating shaft, 612. Revolution counter, 62. Speed ​​controller, 63. Displacement sensor. DETAILED DESCRIPTION

[0060] The technical solution of the present invention is further described below through the accompanying drawings and embodiments.

[0061] Unless otherwise defined, technical or scientific terms used in the present invention shall have the common meanings understood by one having ordinary skills in the field to which the present invention belongs.

[0062] Technologies, methods, and equipment known to ordinary technicians in the relevant field may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered as part of the specification.

[0063] In addition, it should be understood that although this specification is described according to the implementation modes, not every implementation mode includes only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation modes that can be understood by those skilled in the art. These other implementation modes are also covered within the protection scope of the present invention.

[0064] Example 1

[0065] See also Figure 1 This embodiment provides a testing device for evaluating the rheological properties of asphalt mixture, the testing device includes a constant temperature test box 1 and a sample rotating table 2, a loading device 4, a driving mechanism and a computer processor 6 respectively placed in the constant temperature test box 1.

[0066] In this embodiment, a temperature control device 12 is installed in the constant temperature test box 1 for controlling the ambient temperature in the constant temperature test box 1 to reach the test temperature T and transmitting the test temperature data to the computer processor 6 .

[0067] In this embodiment, the sample rotating table 2 is used to place the test sample 5 .

[0068] In this embodiment, a load 411 is set on the top of the loading device 4, and a test wheel 43 is set at the bottom of the loading device 4; the loading device 4 is placed above the sample rotating table 2, and a constant load is applied to the test sample 5 through the load 411. The test wheel 43 contacts the surface of the test sample 5 and is used to roll and rub the test sample 5.

[0069] In this embodiment, a displacement sensor 63 is also provided on the loading device 4 . The displacement sensor 63 is located between the test wheel 43 and the load 411 , and is used to obtain the expansion and contraction amount of the loading device 4 in the vertical direction and transmit the expansion and contraction amount to the computer processor 6 .

[0070] In this embodiment, the driving mechanism is connected to the sample rotating platform 2 and is used to drive the sample rotating platform 2 to drive the test sample 5 to rotate.

[0071] In this embodiment, a revolution counter 612 is provided on the driving mechanism for recording the number of load cycles and transmitting the recorded data to the computer processor 6 .

[0072] In this embodiment, the computer processor 6 is connected to the temperature control device 12, the revolution counter 612 and the displacement sensor 63 respectively, and is used to receive various data during the test process and calculate the load rheological index LRI T , load rheological rate LRR and load resistance rheological energy LRE.

[0073] See also Figure 1 In this embodiment, the constant temperature test box 1 is a rectangular box, and a temperature control device 12 is installed in the constant temperature test box 1. The temperature control device 12 is connected to the computer processor 6, and can realize automatic control of the temperature in the constant temperature test box 1. In particular, the temperature control device 12 is a conventional temperature control device in the industry, preferably a blast type (blast type), to ensure the uniformity of temperature distribution in the constant temperature test box 1.

[0074] In this embodiment, a base 11 is provided at the bottom of the constant temperature test box 1, and a raised platform 111 is provided on the base 11. The sample rotating table 2 is placed on the raised platform 111 through a thrust bearing 21. The thrust bearing 21 serves to support the sample rotating table 2 and ensure the free rotation of the sample rotating table 2.

[0075] In this embodiment, a sample rack 13 is further provided in the constant temperature test box 1, and the sample rack 13 is used to store the test pieces.

[0076] See also Figure 1, the sample-carrying rotating platform 2 is arranged on the base 11 of the constant temperature test box 1, and the supporting devices 3 are arranged on both sides of the base 11. The test sample 5 is placed above the sample-carrying rotating platform 2, and the loading device 4 passes through the supporting device 3 and contacts the upper surface of the test sample 5. Two test wheels 43 are arranged at the bottom of the loading device 4, and the test wheels 43 apply a constant load to the test sample 5 through the loading device 4. A driving mechanism is arranged on the side of the sample-carrying rotating platform 2. Preferably, the driving mechanism is a motor 61, and the motor 61 can drive the sample-carrying rotating platform 2 to drive the test sample 5 to rotate, thereby realizing the continuous rolling effect of the test wheel 43 on the upper surface of the test sample 5. A rolling friction device 431 is arranged on the test wheel 43, which can realize the rolling and kneading effect of the test wheel 43 on the test sample 5 when rolling on the surface of the test sample 5. A displacement sensor 63 is arranged on the supporting device 3, which can monitor the displacement change of the loading device 4 with the test time, and a revolution counter 612 is arranged on the motor 61. The deformation data and the revolution data are transmitted to the computer processor 6 through the connecting line for storage. During implementation, the test sample 5 is driven to rotate by the sample rotating table 2 to realize the continuous and unidirectional rolling and kneading effect of the test wheel 43 on the test sample 5, which can simulate the actual load environment of the asphalt mixture pavement material during the driving process of the car, and ensure the scientific and reasonable effect of the rolling and kneading effect; at the same time, the design of the sample rotating table 2 and the loading device 4 can meet the requirements of high-speed operation of the equipment, ensure the continuity of the rolling and kneading load, and greatly improve the efficiency of the rheological effect on the test sample 5.

[0077] In this embodiment, the sample loading rotating platform 2 is a disc structure, and a square groove is provided inside, and the size of the groove matches the size of the test sample 5. The bottom edge of the sample loading rotating platform 2 is connected to the rotating shaft 611 of the motor 61.

[0078] The computer processor 6 controls the rotation speed of the motor 61 through the rotation speed controller 62 , and the rotating shaft 611 of the motor 61 drives the sample-carrying rotating platform 2 to rotate through the gear teeth.

[0079] In this embodiment, a rotation counter 612 is also provided on the rotating shaft 611 of the motor 61, and the rotation counter 612 is connected to the computer processor 6. The computer processor 6 calculates the number of rotations of the sample rotating table 2 by connecting the number of gear teeth between the rotating shaft 611 and the sample rotating table 2, and feeds back the number of rotations of the sample rotating table 2 to the computer processor 6 for storage.

[0080] See Figure 1In this embodiment, the loading device 4 includes a pressure rod 41, a force transmission column 421 and a gantry loading frame 42 which are respectively placed in the constant temperature test box 1 and connected in sequence from top to bottom; the pressure rod 41 is placed horizontally, the force transmission column 421 is placed vertically, the test wheel 43 is placed at the bottom of the gantry loading frame 42, one end of the pressure rod 41 is movably connected to the bottom surface of the constant temperature test box 1, the load 411 is placed on the other end of the pressure rod 41, and the displacement sensor 63 is placed on the force transmission column 421.

[0081] See also Figure 2 In this embodiment, the gantry loading frame 42 is a gantry structure formed by connecting a cross bar and two support bars. A steering bearing 422 is provided at the bottom end of each of the two support bars. There are two test wheels 43. A test wheel 43 is arranged at the bottom of each steering bearing 422 and the test wheel 43 is connected to the steering bearing 422; the force transmission column 421 is connected to the cross bar.

[0082] In this embodiment, the pressure rod 41 is located above the loading device 4, and one end of the pressure rod 41 is hinged to the support column 311 through the fixing pin 312, so that the pressure rod 41 can rotate around the support column 311; the other end of the pressure rod 41 is connected to the load 411. In particular, the load 411 is a number of counterweight blocks.

[0083] In this embodiment, a rubber pad 412 is provided in the middle of the pressure rod 41, and the rubber pad 412 contacts the force transmission column 421. It is particularly noted that the rubber pad 412 is made of hard rubber material to reduce the vibration of the loading device 4 during the test and ensure the stability of the test system.

[0084] Preferably, the pressure rod 41 is a lever system, the fixed pin 312 is a fulcrum, the load 411 end is a force application point, and the rubber pad 412 is a resistance point, so as to increase the load force applied by the loading device 4 according to the lever principle.

[0085] In this embodiment, a force transmission column 421 is provided on the upper part of the gantry loading frame 42, and a steering bearing 422 is provided at the ends of the two support rods at the lower part, and a test wheel 43 is installed on the steering bearing 422. The test wheel 43 is connected to the steering bearing 422 through a fork frame 423, the support rod at the lower part of the gantry loading frame 42 is connected to the inner ring of the steering bearing 422, and the fork frame 423 is connected to the outer ring of the steering bearing 422.

[0086] Preferably, the steering bearing 422 is preferably a thrust roller bearing, which can withstand an axial load mainly as an axial load and a combined radial load, so as to realize horizontal free rotation of the test wheel 43 .

[0087] Preferably, in this embodiment, a rolling friction device 431 is provided on the fork frame 423 that fixes the test wheel 43 to reduce the degree of free rotation of the test wheel 43 during the test process, so as to achieve the rolling and kneading effect of the test wheel 43 on the test sample 5 when rolling on the surface of the test sample 5.

[0088] Preferably, in this embodiment, the test wheel 43 is preferably a rubber pneumatic tire, and the rubber hardness is preferably 70-80 IRHD.

[0089] See also Figure 5 In this embodiment, the wheel track 51 of the test wheel 43 when rolling on the surface of the test sample 5 is in a circular shape.

[0090] See also Figure 1 The test device provided in this embodiment also includes a support device 3 placed in the constant temperature test box 1, and the support device 3 includes a first support frame 31, a second support frame 32 and a beam 33 respectively located below the pressure rod 41; the displacement sensor 63 is placed on the beam 33 and is located next to the force transmission column 421.

[0091] In this embodiment, the first support frame 31 and the second support frame 32 are both placed vertically, the sample rotating table 2 is located between the first support frame 31 and the second support frame 32, one end of the pressure rod 41 is connected to the inner bottom surface of the constant temperature test box 1 through the first support frame 31; the bottom end of the second support frame 32 is connected to the inner bottom surface of the constant temperature test box 1, and the top end of the second support frame 32 is connected to the first support frame 31 through a horizontally placed beam 33; a force transmission hole 332 is set on the beam 33, and the force transmission column 421 passes through the force transmission hole 332 and is connected to the gantry loading frame 42.

[0092] See also Figure 3 The cross beam 33 is two parallel beam bodies, and the beam bodies are connected by a positioning end plate 331. The middle part of the positioning end plate 331 is a square force transmission hole 332. The square force transmission hole 332 can be used for the force transmission column 421 of the loading device 4 to pass through. The size of the square force transmission hole 332 matches the cross section of the force transmission column 421, and ensures that the force transmission column 421 can be lifted vertically but cannot rotate in the horizontal plane, so as to realize the positioning function of the support device 3 for the loading device 4 during the test.

[0093] See also Figure 4 Specifically, the first support frame 31 and the second support frame 32 are both door-shaped supports. The first support frame 31 and the second support frame 32 are respectively located on both sides of the base 11, and the sample rotating table 2 is placed in the space between the first support frame 31 and the second support frame 32. A support column 311 is provided at the center of the top of the first support frame 31, and a fixing pin 312 is provided at the end of the support column 311.

[0094] In this embodiment, the displacement sensor 63 measures the load deformation of the test sample 5 by monitoring the expansion and contraction amount of the force transmission column 421 .

[0095] In this embodiment, the computer processor 6 stores the data information of the revolution counter 612 and the data information of the displacement sensor 63 monitored at each time point during the test process, so as to draw a deformation-load frequency variation curve.

[0096] Preferably, the test wheel 43 completes one rotation around the test sample 5, and each point on the wheel track 51 is subjected to two rolling and kneading actions of the test wheel 43. During this period, the deformation result of the test sample 5 is represented by the average of the deformation values ​​at each time point monitored in this cycle.

[0097] In this embodiment, the computer processor 6 is equipped with data receiving and data processing software, which can automatically complete the calculation of the deformation value under a single cycle load, and is used for the evaluation and analysis of the load-resistant rheological properties of the test sample 5. Specifically, the computer processor 6 can receive the collected cycle number, test temperature, and expansion and contraction data of the displacement sensor 63, calculate the deformation value under a single cycle load, and calculate the load-resistant rheological index through the calculation model, draw the deformation-load number change curve, and calculate the load rheological rate LRR and the load-resistant rheological energy LRE.

[0098] Preferably, in this embodiment, the test sample 5 can be prepared by indoor molding, or can be cut and processed by sampling on-site on a newly built or existing road. The test surface of the test sample 5 should be the upper surface of the molded or sampled sample, and the upper surface should be clean and flat.

[0099] Preferably, during the test, the weight of the load 411 can be adjusted according to the required load grade level.

[0100] Preferably, the termination condition of the test operation in this embodiment is reaching a specified maximum deformation amount.

[0101] Example 2

[0102] The present embodiment provides a method for evaluating the rheological properties of asphalt mixture, comprising the following steps:

[0103] S1. Fixation of test sample 5

[0104] A test sample 5 formed of an asphalt mixture is fixed on a sample-carrying rotating table 2 of a testing device;

[0105] S2. Parameter setting

[0106] According to the test requirements, the required load level P, maximum deformation L and test temperature T are set; in step S2, the maximum deformation L is 30mm-40mm, and the standard value of the load level P is preferably 50kN.

[0107] S3, constant temperature treatment of test sample 5

[0108] The temperature control device 12 of the test device controls the ambient temperature to reach the test temperature T, and maintains this temperature for 3 to 6 hours;

[0109] S4. Performance test

[0110] The test device is started, and a load level P is applied to the test sample 5. At the same time, the test sample 5 is driven to rotate. The test wheel 43 on the test device rolls on the surface of the test sample 5 according to the circular wheel track to crush and rub the test sample 5, and multiple load cycles are performed along the circular wheel track; the load deformation amount corresponding to the test sample 5 at each time point is recorded, and finally the deformation result l of the test sample 5 under the action of the nth load cycle is obtained. n Reach the set maximum deformation L. In this embodiment, during the test, the test wheel 43 is static, the test sample 5 is dynamic, and the test wheel 43 contacts the upper surface of the test sample 5, so that the static test wheel 43 performs a circular trajectory motion on the rotating test sample 5, realizing an accurate simulation of the rolling and kneading state of the vehicle load, thereby ensuring the accuracy of the evaluation results.

[0111] Specifically, the test device is started, the weight of the load 411 in the loading device 4 is adjusted to P, the sample rotating table 2 drives the test sample 5 to rotate, and the test wheel 43 at the bottom of the loading device 4 is used to roll and rub the test sample 5, and the expansion and contraction amount of the loading device 4 at each time point during one rotation of the sample rotating table 2, that is, the load deformation amount corresponding to the test sample 5, is recorded, and the deformation result l of the test sample 5 under the load during one rotation is calculated. n ; One rotation of the sample rotating table 2 is regarded as one load cycle, until the deformation result of the test sample 5 under the action of the nth load cycle is l n Reach the set maximum deformation L.

[0112] In this embodiment, the deformation result of the test sample 5 under the load during one rotation is l n , is the average value of the deformation value at each time point. The wheel track 51 when the test wheel 43 rolls on the surface of the test sample 5 is annular. In this embodiment, the placement, fixation and rotation of the test sample 5 on the sample rotating table 2, the connection between the loading device 4 and the supporting device 3, and the operation of the loading device 4 are all referred to in Example 1.

[0113] S5. Performance evaluation

[0114] Calculate the load rheological index LRI of test sample 5 at test temperature T T , the calculation formula is as follows:

[0115]

[0116] Where, LRI T is the load resistance rheological index, J / mm;

[0117] N is the total number of cycles of rolling and kneading applied during the test, times;

[0118] l n is the deformation result under the nth load cycle, mm;

[0119] L is the set maximum deformation, i.e. the deformation result under the Nth load cycle, mm;

[0120] P is the set load level, kN;

[0121] T is the set test temperature, ℃.

[0122] It is further defined that step S5 further includes calculating the load rheological rate LRR and the load rheological energy LRE; the calculation method of the load rheological rate LRR and the load rheological energy LRE is:

[0123] With the number of load cycles as the horizontal axis, the deformation result l of test sample 5 under each load cycle n The deformation-load number change curve is drawn with as the vertical coordinate. The load rheological rate LRR is the slope at each point on the deformation-load number change curve; the load rheological energy LRE is the total area under the deformation-load number change curve.

[0124] Specifically, in this embodiment, the method for evaluating the rheological properties of asphalt mixture includes the following steps:

[0125] 1) The test sample 5 is formed. According to the size of the square groove of the sample rotating table 2, a square plate specimen is prepared indoors; or the road surface is cut on site, and then the sample is cut according to the size of the square groove of the sample rotating table 2. The surface of the test sample 5 is guaranteed to be flat and free of floating sand.

[0126] 2) Installation of the test sample 5 . The test sample 5 is placed in the square groove of the sample rotating platform 2 , and elastic fillers are filled around the four sides of the test sample 5 to ensure the stability of the test sample 5 .

[0127] 3) Equipment debugging. According to the required load level, adjust the weight P of the load 411; turn on the computer processor 6 and set the speed of the motor 61; reset the displacement sensor 63 reading to zero; set the test termination condition: the maximum deformation L.

[0128] 4) Constant temperature treatment of test sample 5. Turn on the temperature control device 12, set the test temperature T, and keep the test sample 5 at the set ambient temperature for 3 to 6 hours.

[0129] 5) Rheological properties test.

[0130] The automatic working procedures of the displacement sensor 63 and the revolution counter 612 are turned on, and the equipment is started to perform rheological property test operations and real-time information collection. The computer processor 6 records the number of cycles n of the rolling and kneading action of the test wheel 43, as well as the load deformation amount of the test sample 5 at each time point. Furthermore, the computer processor 6 calculates the deformation result l of the test sample 5 under the load of this cycle. n The load cycle is repeated until the set maximum deformation L is reached. The computer processor 6 records and stores the deformation result l under each load cycle. n , and draw the deformation-load number change curve.

[0131] 6) Result processing: calculate the load rheological index LRI of test sample 5 at ambient temperature T T , as an evaluation index to characterize the load-resistant rheological properties of asphalt mixture materials.

[0132] In this embodiment, it is particularly noted that the maximum deformation parameter L is preferably 30 to 40 mm.

[0133] In this embodiment, it is particularly noted that the standard value of the load level P is preferably 50 kN.

[0134] In this embodiment, it is particularly noted that the load resistance rheological index LRI T Characterizes the ability of the test sample 5 to resist load deformation at a specified ambient temperature T, expressed as the work required to produce a unit deformation. T The larger the value, the stronger the pavement material's ability to resist load deformation. Under the action of rolling and kneading, the pavement material is less likely to undergo load rheological deformation.

[0135] In this embodiment, it is particularly noted that for the same material, the load resistance rheological index LRI T It should be a certain value, which can facilitate the comparative analysis of the load-resistant rheological properties of various materials.

[0136] In this embodiment, in the deformation-load number variation curve, the slope at each point is the load rheological rate LRR of the test sample 5, which represents its rheological property under the rolling and kneading load, expressed as the flow deformation variable under the single rolling and kneading load, J / mm. The larger the load rheological rate LRR, the worse the load rheological ability of the material. The load rheological rate LRR can be used to analyze the load rheological properties of the material at different load stages.

[0137] In this embodiment, in the deformation-load times variation curve, the deformation value l nIt increases with the increase of the number of load cycles n. The total area under the deformation-load number change curve represents the load rheological energy LRE of the material reaching the set maximum deformation L. The larger the load rheological energy LRE, the stronger the load rheological ability of the material.

[0138] It is especially noted that the measurement of the load resistance rheological index is automatically completed through the programming control software of the central computer, which reduces the operating errors of personnel.

[0139] It is particularly noted that, based on the device of the present invention, the ambient temperature can be adjusted in real time according to actual needs to simulate the load-resistant rheological level of the asphalt mixture material under real conditions.

[0140] It should be noted that the above are only preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to make equivalent substitutions for some of the technical features therein. However, any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for evaluating the rheological properties of asphalt mixture, characterized in that: The following steps are involved: S1. Fixing of test sample (5) Fixing a test sample (5) formed of an asphalt mixture on a sample-carrying rotating table (2) of a test device; S2. Parameter setting According to the test requirements, set the required load level P, maximum deformation L and test temperature T; S3. Test sample (5) constant temperature treatment The temperature of the environment is controlled to reach the test temperature T by the temperature control device (12) of the test device, and maintained at this temperature for 3 to 6 hours; S4. Performance test The test device is started, a load level P is applied to the test sample (5), and the test sample (5) is driven to rotate at the same time. The test wheel (43) on the test device rolls on the surface of the test sample (5) according to the circular wheel track to crush and rub the test sample (5), and multiple load cycles are performed along the circular wheel track; the load deformation amount corresponding to the test sample (5) at each time point is recorded, and finally the deformation result l of the test sample (5) under the action of the nth load cycle is obtained. n Reach the set maximum deformation L; S5. Performance evaluation Calculate the load resistance rheological index LRI of the test sample (5) at the test temperature T T , the calculation formula is as follows: Where, LRI T is the load resistance rheological index, J / mm; N is the total number of cycles of rolling and kneading applied during the test, times; l n is the deformation result under the nth load cycle, mm; L is the set maximum deformation, i.e. the deformation result under the Nth load cycle, mm; P is the set load level, kN; T is the set test temperature, ℃.

2. The method for evaluating the rheological properties of asphalt mixture according to claim 1, characterized in that: In step S2, the maximum deformation L is 30 mm to 40 mm, and the load level P is 50 kN.

3. The method for evaluating the rheological properties of asphalt mixture according to claim 1, characterized in that: The specific process of step S4 is: The test device is started, and the weight of the load (411) in the loading device (4) is adjusted to P. The sample rotating platform (2) drives the test sample (5) to rotate, and the test wheel (43) at the bottom of the loading device (4) is used to roll and rub the test sample (5). The expansion and contraction amount of the loading device (4) at each time point during one rotation of the sample rotating platform (2), that is, the load deformation amount of the test sample (5) corresponding to the load, is recorded, and the deformation result l of the test sample (5) under the load during one rotation is calculated. n One rotation of the sample rotating table (2) is regarded as one load cycle, until the deformation result of the test sample (5) under the action of the nth load cycle is l n Reach the set maximum deformation L.

4. The method for evaluating the rheological properties of asphalt mixture according to claim 3, characterized in that: In the step S4, the deformation result l of the test sample (5) under the load after one rotation is n , is the mean of the deformation values ​​at each time point.

5. The method for evaluating the rheological properties of asphalt mixture according to claim 1, characterized in that: The step S5 also includes calculating the load rheological rate LRR and the load rheological energy LRE; The calculation method of the load rheological rate LRR and the load rheological energy LRE is: The number of load cycles is taken as the horizontal axis, and the deformation result l of the test sample (5) under each load cycle is n The deformation-load number change curve is drawn with as the vertical coordinate. The load rheological rate LRR is the slope at each point on the deformation-load number change curve; the load rheological energy LRE is the total area under the deformation-load number change curve.

6. The method for evaluating the rheological properties of asphalt mixture according to claim 5, characterized in that: The smaller the load rheological rate LRR, the larger the load rheological energy LRE, indicating that the load rheological ability of the asphalt mixture of the test sample (5) is stronger.

7. A testing device for implementing the method for evaluating the rheological properties of asphalt mixture according to claim 5, characterized in that: The testing device comprises a constant temperature testing box 1 and a sample loading rotating table (2), a loading device (4), a driving mechanism and a computer processor (6) respectively placed in the constant temperature testing box (1); The constant temperature test box (1) is equipped with a temperature control device (12) for controlling the ambient temperature in the constant temperature test box (1) to reach a test temperature T, and transmitting the test temperature data to the computer processor (6); The sample-carrying rotating platform (2) is used to place the test sample (5); A load (411) is arranged on the top of the loading device (4), and a test wheel (43) is arranged on the bottom of the loading device (4); the loading device (4) is placed above the sample rotating platform (2), and a constant load is applied to the test sample (5) through the load (411); the test wheel (43) is in contact with the surface of the test sample (5) and is used to roll and rub the test sample (5); A displacement sensor (63) is also arranged beside the loading device (4) for obtaining the expansion and contraction amount of the loading device (4) in the vertical direction and transmitting the expansion and contraction amount to the computer processor (6); The driving mechanism is connected to the sample-carrying rotating platform (2) and is used to drive the sample-carrying rotating platform (2) to drive the test sample (5) to rotate; The driving mechanism is provided with a revolution counter (612) for recording the number of load cycles and transmitting the recorded data to the computer processor (6); The computer processor (6) is respectively connected to the temperature control device (12), the revolution counter (612) and the displacement sensor (63) to receive various data during the test and calculate the load rheological index LRI. T , load rheological rate LRR and load resistance rheological energy LRE.

8. The testing device according to claim 7, characterized in that: The loading device (4) comprises a pressure rod (41), a force transmission column (421) and a gantry loading frame (42) which are respectively placed in a constant temperature test box (1) and connected in sequence from top to bottom; the pressure rod (41) is placed horizontally, the force transmission column (421) is placed vertically, the test wheel (43) is placed at the bottom of the gantry loading frame (42), one end of the pressure rod (41) is movably connected to the bottom surface of the constant temperature test box (1), the load (411) is placed on the other end of the pressure rod (41), and the displacement sensor (63) is placed on the force transmission column (421).

9. The testing device according to claim 8, characterized in that: The gantry loading frame (42) is a gantry-shaped structure formed by connecting a crossbar and two support bars into an integral whole. A steering bearing (422) is arranged at the bottom end of each of the two support bars. There are two test wheels (43), and a test wheel (43) is arranged at the bottom of each steering bearing (422) and the test wheel (43) is connected to the steering bearing (422); the force transmission column (421) is connected to the crossbar.

10. The testing device according to claim 7, characterized in that: The testing device further comprises a supporting device (3) placed in the constant temperature testing box (1), the supporting device (3) comprising a first supporting frame (31), a second supporting frame (32) and a crossbeam (33) respectively located below the pressure rod (41); the displacement sensor (63) is placed on the crossbeam (33) and is located beside the force transmission column (421); The first support frame (31) and the second support frame (32) are both placed vertically, the sample rotating table (2) is located between the first support frame (31) and the second support frame (32), one end of the pressure rod (41) is connected to the inner bottom surface of the constant temperature test box (1) through the first support frame (31); the bottom end of the second support frame (32) is connected to the inner bottom surface of the constant temperature test box (1), and the top end of the second support frame (32) is connected to the first support frame (31) through a horizontally placed crossbeam (33); a force transmission hole (332) is arranged on the crossbeam (33), and the force transmission column (421) passes through the force transmission hole (332) and is connected to the gantry loading frame (42).

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