A method for detecting recycled asphalt thin layer overlay material based on three-dimensional fitting

Abstract

This invention discloses a testing method for recycled asphalt thin-layer overlay materials based on three-dimensional fitting, belonging to the field of road engineering material performance testing technology. The method includes: S1, preparing standard rutting slab specimens; S2, conducting accelerated loading tests, determining the initial friction coefficient, recording the number of loading cycles and rutting depth, and measuring the friction coefficient at preset nodes to construct a dataset (,,,). S3, establishing a three-dimensional prediction model through nonlinear regression; S4, obtaining the on-site rutting depth and cumulative load, substituting them into the model to obtain the predicted friction coefficient value, and evaluating the skid resistance and durability performance accordingly. This invention achieves dynamic prediction of skid resistance and durability through three-dimensional fitting of the number of loading cycles, rutting depth, and friction coefficient, overcoming the static limitations of single-point testing.

Description

Technical Field

[0001] This invention relates to the field of road engineering material performance testing technology, specifically a testing method for recycled asphalt thin-layer overlay materials based on three-dimensional fitting. Background Technology

[0002] During the service of thin-layer overlay, skid resistance is the core indicator for evaluating its driving safety. Existing testing methods usually use on-site pendulum friction testers or sand-spreading methods for single-point measurement, which has the following shortcomings: (1) It cannot reflect the dynamic decay law of skid resistance with the accumulation of traffic load and the development of rutting deformation; (2) It lacks the ability to predict the long-term service performance of materials and can only obtain isolated data at the current moment; (3) For recycled asphalt thin-layer overlay, a new type of material, there is no dedicated testing method and evaluation system. Therefore, it is urgent to develop a testing method that can be based on indoor accelerated loading test and integrate load-deformation-skid resistance three-dimensional parameters to achieve accurate evaluation of the skid resistance and durability performance of on-site overlay materials and prediction of remaining life.

[0003] The existing testing methods for recycled asphalt thin-layer overlay materials have the following drawbacks: 1. Patent document CN121164613A discloses a method and system for testing recycled asphalt. "This application discloses a method and system for testing recycled asphalt. The method includes: multi-stage crushing, sieving, grading, and impurity removal of asphalt aggregate to obtain asphalt aggregate; using near-infrared spectroscopy to detect the uniformity of asphalt content distribution in the asphalt aggregate; using microfluidics coupled with other techniques to perform aging tests on the asphalt aggregate that meets the uniformity requirements, obtaining aging degree values ​​and aging anomaly values ​​of the asphalt aggregate; based on the aging degree values ​​and aging anomaly values, generating target formulation data for recycled asphalt mixtures, the target formulation..." The data includes the proportion of asphalt aggregate, the PG grade of virgin asphalt, the type and proportion of recycling agent, and the aggregate gradation. Using a pre-set durability prediction model, the long-term durability data of the recycled asphalt mixture is predicted based on the formulation data. This effectively solves the problems of material inhomogeneity, difficulty in evaluating the performance of old asphalt, and uncertainty in long-term performance prediction in recycled asphalt. However, the aforementioned document focuses on chemical and material components, emphasizing durability prediction during the recycled asphalt formulation design stage, and does not address the dynamic evaluation of skid resistance after thin-layer overlay construction. This presents a technical problem: it cannot reflect the attenuation of skid resistance with rut depth under traffic loads. Summary of the Invention

[0004] The purpose of this invention is to provide a three-dimensional fitting-based testing method for recycled asphalt thin-layer overlay materials to solve the technical problem that existing technologies cannot dynamically predict skid resistance and durability. Through indoor Hamburg rut accelerated loading tests, a three-dimensional nonlinear prediction model is established between the number of loading cycles (reflecting traffic load accumulation), rut depth (reflecting pavement deformation), and friction coefficient (reflecting skid resistance). Then, by using the field-measured rut depth and the cumulative number of traffic load cycles, the skid resistance of the current overlay material can be quickly and accurately evaluated to determine whether it meets safety requirements, and an early warning can be issued.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a method for detecting recycled asphalt thin-layer overlay materials based on three-dimensional fitting, comprising the following steps: S1. Specimen Preparation: Standard rutting slab specimens of the recycled asphalt thin-layer overlay material to be tested were prepared. According to the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG E20-2011) and the Hamburg Rutting Test Standard Method (AASHTO T324-23), the standard rutting slab specimens were formed to dimensions of 300mm × 400mm × 50mm (length × width × height) using a roller mill. After static curing for 48 hours, these 50mm thick specimens were used for indoor accelerated loading tests. The material mix proportions were completely consistent with those of a 2.5cm thick thin-layer overlay on actual road surfaces, and the specimen thickness met the sample loading requirements of the Hamburg rutting tester. The mix proportion of the recycled asphalt thin-layer overlay material is as follows: 40% 7-13mm RAP material, 26% 11-16mm hot aggregate, 20% 6-11mm hot aggregate, 12% 0-4mm hot aggregate, and 2% mineral powder. PG82-28 composite modified asphalt is used as the binder, with an optimal asphalt-aggregate ratio of 5.5% and a new asphalt-aggregate ratio of 3.93%. The designed porosity range of the material is 10%-15%. After S1 and before S2, the standard rutted slab specimens may be subjected to accelerated aging treatment: the standard rutted slab specimens are placed in an 85°C oven for continuous aging for 120 hours, or aged in an ultraviolet aging chamber according to ASTM G154 standard for 72 hours. Then, subsequent steps are performed on the aged specimens to evaluate the degradation law of the anti-skid durability performance of the recycled asphalt thin-layer overlay material after long-term service aging. S2. Accelerated loading test and data acquisition: The standard rutted plate specimen was subjected to accelerated loading test using a Hamburg rut tester (referring to AASHTO T 324-23 standard). The loading wheel was a rubber wheel, the test temperature was set to 40℃±2℃, the tire pressure was 0.7MPa±0.05MPa, and the loading speed was set to 52±2 times / min. Initial friction coefficient determination: Before the test, the rutted plate specimen was placed in a constant temperature chamber at 20℃ for 2 hours to equilibrate. Using a pendulum friction meter, three measuring points were selected in the preset wear area (corresponding to the loaded wheel track). Each measuring point was measured five times, and the average value was taken as the friction coefficient at that point. The average value of the three points was then taken as the initial friction coefficient. During the measurement, a small film with a width of 31.75 mm was used, and the pendulum friction instrument was calibrated before the measurement to ensure that the friction coefficient error between the long film and the small film was within 5%-10%. Loading process data recording: During the test, the number of loading cycles is automatically recorded by the rutting tester. And measure the rut depth corresponding to the number of loading cycles in real time. ; Intermittent testing method: Each 20,000 loading cycles is considered a node. At each node, the test is paused, the standard rutted slab specimen is removed from the testing instrument, and transferred to a 20℃ constant temperature environment. The surface temperature of the specimen is monitored using an infrared thermometer. After the temperature stabilizes to 20℃±1℃ (approximately 30 minutes), the friction coefficient of the wear area (at a different location than the original measuring point to avoid interference from repeated rolling) is measured using a pendulum friction meter. For each specimen, measurements were taken at three points, and the average value was recorded. The corresponding cumulative number of loading cycles was also recorded. and rut depth ; Test termination conditions: According to the Technical Specification for Urban Road Maintenance (CJJ 36-2016), the loading test shall be terminated when the measured value of the friction coefficient decreases to below 42 or the rut depth reaches 5 mm. This is thus constructed based on the number of loads. rut depth coefficient of friction and initial friction coefficient The original experimental dataset of dimensions; S3. Establish a three-dimensional nonlinear prediction model: Based on the original experimental dataset, a nonlinear regression analysis method (least squares method) is used to establish a model representing the number of loading cycles. rut depth With coefficient of friction The three factors are interconnected and include the initial coefficient of friction. Three-dimensional nonlinear prediction model as parameters: ; in This is the predicted value of the friction coefficient. For a nonlinear function determined by regression from experimental data, the model's coefficient of determination is required. ≥0.95; Optionally, after S2 and before S3, a step of normalizing the original experimental data is also included: using a linear normalization method to map the original friction coefficient data of different specimens in the same batch to the [0, 1] interval, so as to eliminate the influence of individual specimen differences on the model accuracy. The normalization calculation formula is: ; in, This is the original friction coefficient data. and These are the maximum and minimum values ​​among all node data of the specimen, respectively. This is the normalized friction coefficient value; S4. On-site skid resistance and durability performance evaluation: Obtain the current rut depth of the target recycled asphalt overlay under its current service condition. Cumulative number of traffic load actions and the known initial coefficient of friction of the material. ; Current rut depth The measurements were taken on-site using the sand-spreading method (refer to JTG 3450-2019) or a laser profiler. The cumulative number of traffic load actions Based on on-site traffic volume survey data, the actual standard axle load BZZ-100 load application times were equivalent to the standard loading times of the indoor Hamburg rutting test using the axle load conversion factor (adopting the equivalent axle load conversion principle, based on the pavement structure layer thickness and material modulus). Will , and Substituting the values ​​into the three-dimensional nonlinear prediction model, the current predicted value of the friction coefficient is calculated. ; Will With respect to the preset safety friction coefficient threshold =42 (based on CJJ 36-2016 standard) for comparison: like If the value is ≥42, the anti-slip performance is deemed to meet the safety requirements. like If the value is less than 42, the anti-slip performance is deemed insufficient, and a warning will be issued.

[0006] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention establishes a three-dimensional nonlinear prediction model among loading times, rut depth, and friction coefficient, thereby realizing dynamic prediction of the skid resistance and durability of recycled asphalt thin-layer overlay materials. This overcomes the limitation of traditional single-point detection, which can only obtain static data at the current moment, and can predict the skid resistance at any service stage. 2. This invention, by using the Hamburg rutting tester and setting standardized test parameters (temperature 40℃±2℃, pressure 0.7MPa, rubber wheel loading, and intermittent testing every 20,000 cycles), achieves an equivalent simulation of the long-term field service process through indoor accelerated loading tests, significantly shortening the testing cycle (200,000 rolling cycles only require about 6.5 hours) and significantly reducing testing costs. 3. This invention achieves high-precision fitting with a model determination coefficient of over 0.98 by normalizing the preprocessing of the original experimental data and establishing a three-dimensional nonlinear prediction model using the least squares method (specifically, the goodness of fit of the power function of rut depth-loading number is 96.2%, the goodness of fit of the exponential function of friction coefficient-loading number is 98.4%, the goodness of fit of friction coefficient-rut depth is 97.6%, and the three-dimensional comprehensive goodness of fit is 98.1%), thus ensuring the accuracy of the prediction results; 4. This invention compares the model's predicted value with a preset safety friction coefficient threshold of 42 and issues an early warning, thereby enabling rapid evaluation and safety warning of the anti-slip durability performance of on-site overlay materials. This facilitates maintenance decisions and is applicable to preventive maintenance and functional improvement projects for rural roads, county and township roads, and scenic roads with low traffic volume. 5. By adding an accelerated aging treatment step (thermal-oxidative aging or ultraviolet aging) to the standard rut slab specimens before the accelerated loading test, this invention can evaluate the degradation law of the anti-skid durability of recycled asphalt thin-layer overlay materials after long-term service aging, and provides a standardized testing method for evaluating the aging resistance performance of materials. Attached Figure Description

[0007] Figure 1 This is a schematic diagram of the overall process of the present invention; Figure 2 This is a schematic diagram illustrating the key technical principles of the present invention; Figure 3 This is a schematic diagram of the rut test measurement points of the present invention; Figure 4 This is a schematic diagram of the three-dimensional fitting surface of the present invention. Detailed Implementation

[0008] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0009] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," "outer," "front end," "rear end," "both ends," "one end," and "the other end," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0010] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installed," "equipped with," "connected," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0011] Example 1: Please refer to Figure 1 , Figure 2 , Figure 3 and Figure 4 This invention provides a method for testing recycled asphalt thin-layer overlay materials based on three-dimensional fitting. This embodiment uses a composite modified recycled thin-layer overlay applied in the 2024 "Four Good Rural Roads" construction project in Pingyuan County, Meizhou City, Guangdong Province as the testing object. The specific implementation is as follows: I. Specimen Preparation According to the production mix ratio: 40% 7-13mm RAP material, 26% 11-16mm hot aggregate, 20% 6-11mm hot aggregate, 12% 0-4mm hot aggregate, and 2% mineral powder, PG82-28 composite modified asphalt was used, with an optimal asphalt-aggregate ratio of 5.5% (3.93% for new asphalt). A 300mm×400mm×50mm rutting slab specimen was formed using a roller mill (model 20-4035) manufactured by Infra Test GmbH, Germany. After forming, the specimen was allowed to cure at room temperature for 48 hours. The material mix ratio of this 50mm thick specimen was completely consistent with the actual 2.5cm thick overlay of the road surface. The specimen thickness met the sample loading requirements of the Hamburg rutting tester (according to AASHTO T 324-23 standard). A total of 3 parallel specimens were prepared. II. Accelerated Loading Experiment and Data Acquisition The German Infra Test 40-2000 Hamburg rutting tester was used, with rubber tires as the loading wheel. The test temperature was set to 40℃, the tire pressure to 0.7MPa, and the loading speed to 52 cycles / min. Initial friction coefficient determination: Before the test, the rutted plate specimen was placed in a constant temperature room at 20℃ for 2 hours to equilibrate. Using a pendulum friction tester (small film, width 31.75mm), three measuring points (measuring points 1-3) were selected in the preset wear area. Each measuring point was measured 5 times, and the average value was taken as the friction coefficient of that point. The average value of the three points was then taken as the initial friction coefficient. Before the measurement, the pendulum friction tester was calibrated. On the ceramic standard plate, the friction coefficient error between the long film and the small film was within 5-10%, confirming that the small film was usable. In this embodiment, the average initial friction coefficient of the three specimens was... =58.3, this data comes from the measured results of the Hamburg rutting test using SRA composite modified asphalt; Intermittent loading and data acquisition: The Hamburg rutting tester is started, and the loading wheel rolls back and forth on a 230×50mm road surface area. Every 20,000 loads, the test is automatically paused, the rutting plate specimen is removed from the tester, and transferred to a 20℃ constant temperature environment. The surface temperature of the specimen is monitored using an infrared thermometer. After the temperature stabilizes at 20℃±1℃ (approximately 30 minutes), the friction coefficient of the wear area (measuring points 4-6, located within the wheel track but different from the initial measuring point position) is measured using a pendulum friction meter. The average value of the three points is taken as the friction coefficient for this stage. Simultaneously record the current cumulative number of loading times displayed by the rutting instrument. and rut depth ; Repeat the above process to record the data at 20,000, 40,000, 60,000, 80,000, 100,000, 120,000, 140,000, 160,000, 180,000, and 200,000 loading times in sequence; After 200,000 loading cycles, the friction coefficient was measured to drop to 38.7 and the rut depth to be 3.08 mm. This data comes from the results of the SRA-Ⅰ-40℃ Hamburg rut test. Test termination condition check: According to the "Technical Specification for Urban Road Maintenance" (CJJ 36-2016), the friction coefficient of all nodes in this embodiment is higher than 42 and the rut depth does not reach 5mm, therefore 200,000 loading cycles are completed; The collected data is shown in Table 1 below: Table 1. Data collected

[0012] III. Establishing a Three-Dimensional Nonlinear Prediction Model Based on the above data, nonlinear regression analysis was performed using the least squares method. The following fitting relationships were first established: (1) Rut depth With load count Power function fitting: The fitting yields the equation Coefficient of determination (i.e., a goodness of fit of 96.2%) (2) Coefficient of friction With load count Exponential fitting: The fitting yields the equation Coefficient of determination (i.e., a goodness of fit of 98.4%) (3) Coefficient of friction with rut depth Exponential fitting: The fitting yields the equation Coefficient of determination (i.e., a goodness of fit of 97.6%).

[0013] Further construct a three-dimensional fitting model, the model form of which is: ; Where a, b, c, and d are model parameters determined through regression analysis, a is the attenuation coefficient of the friction coefficient due to the number of loading cycles, b is the attenuation rate coefficient due to the number of loading cycles, c is the attenuation coefficient of the friction coefficient due to the rut depth, and d is the attenuation exponent due to the rut depth. The model parameters are determined through regression, and the model determination coefficient is... (i.e., goodness of fit 98.1%), and it has been verified that the model can accurately describe the nonlinear relationship between the number of loading cycles, rut depth and friction coefficient; IV. On-site anti-slip durability performance evaluation Taking a rural road test section as an example, the current rut depth was obtained through on-site testing. (Measured using the sand-spreading method or laser profilometer), and the cumulative number of traffic load actions is calculated based on traffic volume survey data. (Using the equivalent axle load conversion principle), , and the known initial friction coefficient Substituting the values ​​into the three-dimensional prediction model, the predicted value of the current friction coefficient is calculated. ,Will Safety threshold 42 comparison: If If the anti-slip performance is ≥42, then the anti-slip performance is deemed to meet the safety requirements. If the value is less than 42, the anti-slip performance is deemed insufficient, and a warning will be issued. Field measurements verified that the relative error between the predicted and measured friction coefficient values ​​was less than 1%. In addition, this testing method can also serve as a standardized process for the engineering acceptance and post-evaluation services of roads supporting biomass energy projects, providing quantitative basis for project due diligence and risk assessment services; V. Example of Early Warning Output If the predicted friction coefficient of a certain road section is lower than 42, an early warning will be issued stating "Insufficient anti-skid performance, preventive maintenance or milling and repaving is recommended".

[0014] Example 2: Please refer to Figure 1 and Figure 4 The present invention provides a method for detecting recycled asphalt thin-layer overlay materials based on three-dimensional fitting: This embodiment is basically the same as Embodiment 1, except that a normalization preprocessing step is added after S2 and before S3. Specifically: For three parallel specimens formed in the same batch, the original friction coefficient data of each specimen at each loading node were linearly normalized. Taking one specimen as an example, the maximum friction coefficient of all nodes (including the initial value) was taken. and minimum value According to the formula Calculate the normalized value, and then perform three-dimensional fitting after merging the normalized data of the three specimens; After normalization, the model's coefficient of determination was further improved, indicating that the method effectively eliminated individual differences in the specimens and improved the model's generalization ability.

[0015] Example 3: Please refer to Figure 3 This invention provides a method for testing recycled asphalt thin-layer overlay materials based on three-dimensional fitting. This embodiment is basically the same as Embodiment 1, except that a domestic HYCA-5C automatic rutting tester is used for comparative testing. However, the comparative results show that steel wheel loading will cause surface particle peeling and abnormal increase in friction coefficient of the thin overlay at around 80,000 cycles (due to exposed aggregate), which cannot truly reflect the anti-skid attenuation law. Therefore, this invention explicitly limits the preferred use of the Hamburg rutting tester and rubber wheel combination. If other equipment is used, a comparison test of the equipment and the establishment of correction coefficients must be carried out in advance.

[0016] Example 4: Please refer to Figure 1 This invention provides a method for testing recycled asphalt thin-layer overlay materials based on three-dimensional fitting. This embodiment is basically the same as Embodiment 1, except that, after S1 and before S2, the standard rutted slab specimen is subjected to accelerated aging treatment. The specific operation is as follows: The standard rutted plate specimens formed according to the method of Example 1 were divided into two groups: the first group was the unaged group (directly subjected to S2-S4), and the second group was the aged group. The specimens of the aged group were placed in an 85°C oven for continuous aging for 120 hours (simulating thermo-oxidative aging), or aged in an ultraviolet aging chamber according to ASTM G154 standard for 72 hours (simulating ultraviolet aging). After aging, the specimens were taken out and restored to room temperature, and then accelerated loading tests and data collection were carried out according to S2 to S4 of Example 1. By comparing the initial friction coefficients of the aged group and the unaged group The friction coefficient decay curves at each loading node can be used to quantitatively evaluate the degradation law of the anti-skid durability of recycled asphalt thin-layer overlay material after long-term service aging. The test results show that the initial friction coefficient of the aged group specimens is reduced by about 8%-12% compared with the unaged group, and the friction coefficient decay rate is accelerated throughout the loading process. The decay coefficients a and c in the three-dimensional prediction model increase by 15%-20% respectively. This method provides a standardized testing method for evaluating the aging resistance performance of materials.

[0017] The working principle involves establishing a three-dimensional nonlinear prediction model relating loading cycles, rut depth, and friction coefficient. This model enables dynamic prediction of the skid resistance and durability of recycled asphalt thin-layer overlay materials, overcoming the limitations of traditional single-point testing which only provides static data at the current moment. It can predict skid resistance at any service stage. By employing a Hamburg rut testing apparatus and setting standardized test parameters (temperature 40℃±2℃, pressure 0.7MPa, rubber wheel loading, and intermittent testing every 20,000 cycles), it achieves an equivalent simulation of long-term field service through indoor accelerated loading tests, significantly shortening the testing cycle (approximately 6.5 hours for 200,000 compactions) and reducing testing costs. The model achieves its intended effect by normalizing the preprocessing of raw test data and establishing a three-dimensional nonlinear prediction model using the least squares method. The high-precision fitting with a determination coefficient of over 0.98 (specifically, the goodness of fit of the power function of rut depth-loading number is 96.2%, the goodness of fit of the exponential function of friction coefficient-loading number is 98.4%, the goodness of fit of friction coefficient-rut depth is 97.6%, and the three-dimensional comprehensive goodness of fit is 98.1%) ensures the accuracy of the prediction results. By comparing the model's predicted values ​​with the preset safe friction coefficient threshold of 42 and issuing early warnings, the model enables rapid evaluation and safety warning of the anti-skid durability performance of the on-site overlay material, facilitating maintenance decisions. It is suitable for preventive maintenance and functional improvement projects on rural roads, county and township roads, and scenic roads with low traffic volume. By adding an accelerated aging treatment step, it is also possible to evaluate the decline law of the anti-skid performance of the material after long-term aging, providing more comprehensive data support for road maintenance decisions.

[0018] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A method for detecting recycled asphalt thin-layer overlay materials based on three-dimensional fitting, characterized in that: Includes the following steps: S1. Prepare standard rutted slab specimens of the recycled asphalt thin-layer overlay material to be tested; S2. An accelerated loading test is performed on the standard rutting plate specimen using a rutting tester. Before the test, the initial friction coefficient of the wear area of ​​the standard rutting plate specimen is determined. During the experiment, the number of loading times was recorded. Real-time measurement of the number of loading cycles Corresponding rut depth The friction coefficient of the wear area of ​​the standard rutted plate specimen was determined using an intermittent testing method at preset loading cycles. Thus, a system is built based on the number of loads. rut depth coefficient of friction and initial friction coefficient The original experimental dataset is of dimension 1; S3. Based on the original experimental dataset, a nonlinear regression analysis method is used to establish a characterization of the number of loading cycles. rut depth With coefficient of friction The three factors are interconnected and include the initial coefficient of friction. Three-dimensional nonlinear prediction model as parameters; S4. Obtain the current rutting depth of the target recycled asphalt overlay under its current service condition. and cumulative number of traffic load actions , will the and Substituting the values ​​into the three-dimensional nonlinear prediction model, the current predicted value of the friction coefficient is calculated. According to the above The skid resistance and durability of the target recycled asphalt overlay were evaluated.

2. The method for detecting recycled asphalt thin-layer overlay materials based on three-dimensional fitting according to claim 1, characterized in that: The rutting tester used in S2 is a Hamburg rutting tester, the loading wheel is a rubber wheel, the test temperature is set to 40℃±2℃, the tire pressure is 0.7MPa±0.05MPa, and the loading speed is set to 52 times / min±2 times / min.

3. The method for detecting recycled asphalt thin-layer overlay materials based on three-dimensional fitting according to claim 1, characterized in that: The intermittent testing method in S2 specifically involves: taking every 20,000 loading cycles as a node, pausing the test at each node, cooling the standard rutted plate specimen to 20℃±1℃, and then using a pendulum friction meter to determine the friction coefficient of the wear area. And record the corresponding rut depth. and cumulative load count ; The pendulum friction tester uses a small film with a width of 31.75 mm. Before measurement, the pendulum friction tester is calibrated to ensure that the friction coefficient error between the long film and the small film is within 5%-10%.

4. The method for detecting recycled asphalt thin-layer overlay materials based on three-dimensional fitting according to claim 1, characterized in that: The three-dimensional nonlinear prediction model in S3 uses the least squares method for parameter estimation, resulting in a model with a certain coefficient of determination. ≥0.95, model based on loading count and rut depth As the independent variable, the coefficient of friction As the dependent variable, and with the initial friction coefficient as the dependent variable. These are the baseline parameters.

5. The method for detecting recycled asphalt thin-layer overlay materials based on three-dimensional fitting according to claim 1, characterized in that: In step S4, the predicted value of the current friction coefficient is used. The evaluation of the anti-skid durability of the target recycled asphalt thin-layer overlay specifically includes, [the following is unclear and likely incomplete: "will be used for evaluation"]. With respect to the preset safety friction coefficient threshold If a comparison is made, If the anti-slip performance meets the safety requirements, then the anti-slip performance is deemed to be satisfactory. If the anti-slip performance is insufficient, a warning will be issued, and the safe friction coefficient threshold will be used. The value is 42.

6. The method for detecting recycled asphalt thin-layer overlay materials based on three-dimensional fitting according to claim 1, characterized in that: The step between S2 and S3 includes a normalization preprocessing step for the original experimental data. A linear normalization method is used to map the original friction coefficient data of different specimens from the same batch to the [0, 1] interval to eliminate the influence of individual specimen differences on model accuracy. The normalization calculation formula is as follows: ; in, This is the original friction coefficient data. and These are the maximum and minimum values ​​among all node data of the specimen, respectively. This is the normalized friction coefficient value.

7. The method for detecting recycled asphalt thin-layer overlay materials based on three-dimensional fitting according to claim 1, characterized in that: The test termination condition in S2 is that the loading test is terminated when the measured value of the friction coefficient decreases to below 42 or the rut depth reaches 5 mm.

8. The method for detecting recycled asphalt thin-layer overlay materials based on three-dimensional fitting according to claim 1, characterized in that: The recycled asphalt thin-layer overlay material contains 40% by mass of RAP recycled material and uses PG82-28 composite modified asphalt as binder. The standard rutted slab specimen has a molding thickness of 5cm to simulate the performance of a 2.5cm thick thin-layer overlay material on an actual road surface. The porosity of the material is designed to be within the range of 10%-15%.

9. The method for detecting recycled asphalt thin-layer overlay materials based on three-dimensional fitting according to claim 1, characterized in that: In S4, the cumulative number of traffic load actions The method for obtaining the data is as follows: based on on-site traffic volume survey data, the actual standard axle load BZZ-100 application times are equivalent to the standard loading times of the indoor Hamburg rut test using the axle load conversion factor, and the current rut depth is... Measured by sand spreading method or laser cross-section instrument.

10. The method for detecting recycled asphalt thin-layer overlay materials based on three-dimensional fitting according to claim 1, characterized in that: After S1 and before S2, the standard rutted slab specimen is subjected to accelerated aging treatment. The accelerated aging treatment includes placing the standard rutted slab specimen in an 85°C oven for 120 hours of continuous aging, or aging it in an ultraviolet aging chamber according to ASTM G154 standard for 72 hours. Then, S2 to S4 are performed on the aged specimen to evaluate the degradation law of the anti-skid durability performance of the recycled asphalt thin-layer overlay material after long-term service aging.

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