Performance evaluation method of recycled asphalt mixture, computer equipment and storage medium
By constructing a two-dimensional discrete element model and using the microcrack density and aggregate breakage rate of the slip zone to evaluate the performance of recycled asphalt mixtures, the problem of evaluating the impact of aggregate breakage in existing technologies has been solved, and the performance of recycled asphalt mixtures can be precisely adjusted and the road performance improved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-04
- Publication Date
- 2026-03-31
AI Technical Summary
Existing technologies lack effective methods for evaluating the impact of aggregate crushing on the performance of recycled asphalt mixtures, which affects the gradation and road performance of the mixtures.
A two-dimensional discrete element model was constructed to simulate the microcrack and breakage information of recycled asphalt mixtures. The microcrack density of slip zone and aggregate breakage rate were used as evaluation indicators, and the bonding performance was simulated by combining a linear parallel bonding model.
It enables accurate evaluation of the performance of recycled asphalt mixtures, allowing for better adjustment of their mix proportions and improvement of road performance.
Smart Images
Figure CN121768536A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of recycled asphalt mixture technology, and in particular to a method for evaluating the performance of recycled asphalt mixtures, a computer device, and a storage medium. Background Technology
[0002] Reclaimed Asphalt Pavement (RAP) undergoes processing steps including milling, crushing, screening, heating, and mixing during its use. During the milling process, the aggregates of RAP develop microcracks under the mechanical force of the milling equipment. These microcracks further evolve during crushing, screening, heating, and mixing, forming a recycled asphalt mixture. After being laid on the road surface, these microcracks develop into macrocracks under traffic loads and external environmental conditions, leading to aggregate breakage. This aggregate breakage directly affects the mixture's gradation and further impacts its road performance.
[0003] However, current standards and testing or evaluation methods lack consideration of the impact of aggregate crushing on the performance of asphalt mixtures. Therefore, there is an urgent need to propose a performance evaluation method for recycled asphalt mixtures based on crushable aggregates, so as to provide technical support for the performance evaluation of recycled asphalt mixtures composed of crushable aggregates. Summary of the Invention
[0004] The technical problem to be solved by the present invention is to provide a method, computer equipment and storage medium for evaluating the performance of recycled asphalt mixtures, so as to accurately evaluate the performance of recycled asphalt mixtures and thus better adjust the mix proportions of recycled asphalt mixtures.
[0005] To address the aforementioned technical problems, this invention provides a method for evaluating the performance of recycled asphalt mixtures, comprising: constructing a two-dimensional discrete element model of the target recycled asphalt mixture, wherein the two-dimensional discrete element model is used to characterize coarse aggregate, RAP, old asphalt, new aggregate, and new asphalt; calibrating the microscopic parameters of the two-dimensional discrete element model; loading the two-dimensional discrete element model and detecting microcrack information and / or breakage information during the loading process; constructing slip zones based on the microcrack information and calculating the microcrack density of the slip zones, wherein the slip zones are band-shaped cracks located inside the RAP and at the interface between the RAP and the new asphalt; calculating the aggregate breakage rate based on the breakage information; and evaluating the performance of the target recycled asphalt mixture based on the microcrack density of the slip zones and / or the aggregate breakage rate.
[0006] As an improvement to the above scheme, the step of constructing a two-dimensional discrete element model of the target recycled asphalt mixture includes: constructing a two-dimensional wall model of the target recycled asphalt mixture; extracting two-dimensional coarse aggregate contour models from a preset two-dimensional coarse aggregate contour model set according to the gradation information of the target recycled asphalt mixture to construct a coarse aggregate particle model, and filling the coarse aggregate particle model into the two-dimensional wall model, wherein the coarse aggregate particle model is filled with indestructible particles; constructing a first particle model to represent new asphalt, and filling the first particle model into the two-dimensional wall model; deleting the indestructible particles in the coarse aggregate particle model; constructing breakable particles, and filling the coarse aggregate particle model with the breakable particles; bonding the breakable particles in the coarse aggregate particle model using a linear parallel bonding model; constructing a second particle model to represent old asphalt, and covering the second particle model on the RAP surface; and representing coarse aggregate, RAP, old asphalt, new aggregate, and new asphalt using different colors.
[0007] As an improvement to the above scheme, the construction steps of the two-dimensional coarse aggregate contour model set include: collecting the three-dimensional coarse aggregate morphology; and projecting the three-dimensional coarse aggregate morphology to generate a two-dimensional coarse aggregate contour model.
[0008] As an improvement to the above scheme, the calculation steps for the microcrack density of the slip band include: according to the formula Calculate the microcrack density of the slip band; where, The microcrack density of the slip zone. For the area of the slip zone, The area is the two-dimensional discrete element model.
[0009] As an improvement to the above scheme, the step of constructing a slip band based on the microcrack information includes: detecting the bonding fracture points generated by the linear parallel bonding model during the loading of the two-dimensional discrete element model; extracting the bonding fracture points inside the RAP and at the interface between the RAP and the new asphalt as reference fracture points; dividing the two-dimensional discrete element model into several mesh elements; calculating the microcrack sub-density of each mesh element based on the reference fracture points; using mesh elements with microcrack sub-density greater than a preset slip band threshold as reference cells, and using the reference fracture points in the reference cells as target fracture points; and constructing a slip band based on the target fracture points.
[0010] As an improvement to the above scheme, the step of constructing a slip band based on the target fracture point includes: S1, taking the target fracture point with the largest Y coordinate as the starting point; S2, taking a target fracture point adjacent to the starting point as the midpoint; S3, taking a target fracture point adjacent to the midpoint as the ending point; S4, connecting the starting point, midpoint, and ending point to form a slip segment; S5, determining whether the included angle of the slip segment is within a preset included angle range; S6, if the determination is yes, taking the midpoint as the new starting point, taking the ending point as the new midpoint, and returning to step S3, until there are no adjacent target fracture points to the midpoint; S7, if the determination is no, taking another target fracture point adjacent to the midpoint as the new ending point, deleting the slip segment, and returning to step S4, until there are no adjacent target fracture points to the midpoint; S8, combining the slip segments into a slip band and deleting the target fracture points corresponding to the slip band, returning to step S1, until all target fracture points have been constructed.
[0011] As an improvement to the above scheme, the aggregate crushing rate is the ratio of the area of the crushed coarse aggregate to the area of the two-dimensional discrete element model.
[0012] As an improvement to the above scheme, the method for calculating the area of the crushed coarse aggregate includes: detecting the bonding fracture points generated by the linear parallel bonding model during the loading of the two-dimensional discrete element model; and taking the area of the coarse aggregate particle model corresponding to the bonding fracture point as the area of the crushed coarse aggregate.
[0013] As an improvement to the above scheme, the step of evaluating the performance of the target recycled asphalt mixture based on the microcrack density of the slip zone and the aggregate breakage rate includes: evaluating the performance of the target recycled asphalt mixture based on the microcrack density of the slip zone to output a first evaluation level; evaluating the performance of the target recycled asphalt mixture based on the aggregate breakage rate to output a second evaluation level; and using the lower evaluation result between the first evaluation level and the second evaluation level as the final evaluation level.
[0014] Accordingly, the present invention also provides a computer device, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps of the above-described performance evaluation method for recycled asphalt mixtures based on crushable aggregates.
[0015] Accordingly, the present invention also provides a computer-readable storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, implements the steps of the above-described performance evaluation method for recycled asphalt mixtures based on crushable aggregates.
[0016] Implementing this invention has the following beneficial effects: This invention innovatively introduces the microcrack density of the slip zone and the aggregate breakage rate as evaluation indicators in the performance evaluation method of recycled asphalt mixture based on crushable aggregates. It provides an accurate evaluation of the performance of recycled asphalt mixtures from a completely new perspective, thereby enabling better adjustment of the mix proportions of recycled asphalt mixtures. This invention introduces a novel two-dimensional discrete element model construction method for performance evaluation of recycled asphalt mixtures based on crushable aggregates. By specifically treating the indestructible particles inside the two-dimensional coarse aggregate contour model, crushable particles are filled inside the two-dimensional coarse aggregate contour model. Then, the crushable particles inside the coarse aggregate particle model are bonded by a linear parallel bonding model, thereby effectively simulating the bonding performance of recycled asphalt mixtures and making the two-dimensional discrete element model have crushable characteristics. Attached Figure Description
[0017] Figure 1 This is a flowchart of the first embodiment of the performance evaluation method for recycled asphalt mixtures based on crushable aggregates of the present invention; Figure 2 This is a schematic diagram of the three-dimensional coarse aggregate morphology in this invention; Figure 3 This is a schematic diagram of the two-dimensional coarse aggregate outline model in this invention; Figure 4 This is a schematic diagram illustrating the construction of the coarse aggregate particle model in this invention; Figure 5 This is a schematic diagram of the two-dimensional discrete element model for constructing the target recycled asphalt mixture in this invention; Figure 6 This is a schematic diagram of the distribution of the slip zone in this invention; Figure 7 This is a flowchart of the second embodiment of the performance evaluation method for recycled asphalt mixtures based on crushable aggregates of the present invention; Figure 8 This is a schematic diagram of the aggregate crushing type in this invention; Figure 9 This is a flowchart of the third embodiment of the performance evaluation method for recycled asphalt mixtures based on crushable aggregates of the present invention. Detailed Implementation
[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings. It is hereby declared that the directional terms such as up, down, left, right, front, back, inside, and outside used in this text are based solely on the accompanying drawings and are not intended to specifically limit the invention.
[0019] See Figure 1 , Figure 1The flowchart of a first embodiment of the performance evaluation method for recycled asphalt mixtures based on crushable aggregates of the present invention is shown, which includes: S101, Construct a two-dimensional discrete element model of the target recycled asphalt mixture; The raw materials for recycled asphalt mixtures include RAP, virgin aggregate, and asphalt. Virgin aggregate is divided into six grades: 22-28 mm, 10-20 mm, 10-15 mm, 5-10 mm, 3-5 mm, and 0-3 mm. RAP is divided into three grades: 19-25 mm, 13-19 mm, and 0-8 mm. Coarse aggregate refers to aggregate with a particle size ≥ 2.36 mm (including RAP and virgin aggregate), while fine aggregate refers to aggregate with a particle size < 2.36 mm.
[0020] It should be noted that different recycled asphalt mixtures have different raw material screening rates, aggregate blending ratios, gradation relationships, and properties.
[0021] For example, the screening pass rates of raw materials for four types of recycled asphalt mixtures with RAP content of 15%, 30%, 45% and 60% are shown in Table 1 below, the blending ratio of aggregates for each grade is shown in Table 2 below, and the gradation of the four types of recycled asphalt mixtures is shown in Table 3 below.
[0022] Table 1
[0023] Table 2
[0024] Table 3
[0025] Since different recycled asphalt mixtures have different properties, different two-dimensional discrete element models need to be constructed for recycled asphalt mixtures with different RAP content to characterize coarse aggregate, RAP, old asphalt, new aggregate and new asphalt.
[0026] It should be noted that before constructing the two-dimensional discrete element model of the target recycled asphalt mixture, a two-dimensional coarse aggregate profile model set must first be constructed. The specific construction steps include: (1) Collect the three-dimensional morphology of coarse aggregates; like Figure 2 As shown, a 3D scanner is used to scan coarse aggregates of different particle sizes and profiles to obtain the real 3D morphology of coarse aggregates and generate STL format files.
[0027] (2) Project the three-dimensional coarse aggregate morphology to generate a two-dimensional coarse aggregate outline model.
[0028] like Figure 3As shown, the two-dimensional coarse aggregate contour is obtained by projection to construct a two-dimensional coarse aggregate contour database template file to characterize the two-dimensional coarse aggregate contour model, and the two-dimensional coarse aggregate contour database template files of different particle sizes are combined to form a two-dimensional coarse aggregate contour model set (i.e., template).
[0029] For example, taking recycled asphalt mixture AC-25 as an example, the new aggregate is divided into six grades: 22-28mm, 10-20mm, 10-15mm, 5-10mm, 3-5mm, and 0-3mm, while the RAP is divided into three grades: 19-25mm, 13-19mm, and 0-8mm. The STL format files of the 3D scanned coarse aggregate (greater than 2.36mm) are as follows: Figure 2 As shown, the two-dimensional coarse aggregate profile model set is as follows: Figure 3 As shown.
[0030] Accordingly, the steps for constructing a two-dimensional discrete element model of the target recycled asphalt mixture include: (1) Construct a two-dimensional wall model of the target recycled asphalt mixture; A two-dimensional wall model of the target recycled asphalt mixture was established using discrete element method software (PFC5.0 2D). The size of the two-dimensional wall model was 300mm × 50mm, but this was not a limitation.
[0031] (2) Based on the gradation information of the target recycled asphalt mixture, extract the two-dimensional coarse aggregate contour model from the preset two-dimensional coarse aggregate contour model to construct the coarse aggregate particle model, and fill the two-dimensional wall model with the coarse aggregate particle model, which is filled with indestructible particles. Clump distribute (block generation) is used to sequentially read coarse aggregate particles of different sizes from the two-dimensional coarse aggregate profile model set. The volume of each coarse aggregate particle is determined according to the gradation information of the target recycled asphalt mixture. Based on the volume of a single coarse aggregate particle, the number of coarse aggregate particles required to be generated for each coarse aggregate is calculated. The generation order is to generate coarse aggregate particle models in descending order of particle size.
[0032] (3) Construct the first particle model to characterize the new asphalt, and fill the first particle model into the two-dimensional wall model; Ball generate sequentially to produce spherical particles with a diameter of 0.2mm to 0.3mm to fill the voids in the coarse aggregate until the porosity meets the design requirements.
[0033] (4) Delete the unbreakable particles in the coarse aggregate particle model; Remove the unbreakable particles from the coarse aggregate particle model, and only retain the outline of the coarse aggregate particle model.
[0034] (5) Construct crushable particles and fill the coarse aggregate particle model with crushable particles; The outline of the coarse aggregate particle model is filled with round particles with a particle size of 0.2mm to 0.3mm.
[0035] (6) The crushable particles in the coarse aggregate particle model are bonded by a linear parallel bonding model; like Figure 4 As shown, after generating a coarse aggregate particle model with contour features in step (2), the present invention deletes the unbreakable particles in the coarse aggregate particle model in step (4), then generates circular particles with a radius of 0.2mm to 0.3mm to fill the coarse aggregate particle model in step (5), and finally binds the circular particles into a whole by using a linear parallel bonding model in step (6).
[0036] In practical applications, you can first generate circular particles with a radius of 0.2mm to 0.3mm to fill the coarse aggregate particle model through step (5), and then delete the unbreakable particles in the coarse aggregate particle model through step (4).
[0037] It should be noted that in the process of establishing the crushable coarse aggregate particle model, Clump only serves as an intermediary for transmitting the shape and grouping information of the coarse aggregate. The Ball within the coarse aggregate outline inherits the grouping and mesoscopic parameter information of Clump.
[0038] Therefore, the two-dimensional discrete element model established in this invention has the characteristic of being breakable. The balls within the coarse aggregate contour are bonded together as a whole through parallel bonding to effectively simulate the bonding performance of recycled asphalt mixtures.
[0039] (7) Construct a second particle model to characterize the old asphalt and cover the RAP surface with the second particle model; To accurately distinguish between new and old aggregates, this invention covers the surface of RAP with an old asphalt film, while the surface of new aggregates is free of the old asphalt film; wherein, the old asphalt is represented by round particles with a radius of 0.2mm to 0.3mm.
[0040] (8) Different colors are used to represent coarse aggregate, RAP, old asphalt, new aggregate and new asphalt.
[0041] like Figure 5 As shown, the components of the target recycled asphalt mixture are grouped and distinguished by different colors for coarse aggregate, RAP, old asphalt, new aggregate, and new asphalt.
[0042] Therefore, the present invention can construct a complete two-dimensional discrete element model based on the gradation information of the target recycled asphalt mixture to accurately characterize the microstructural features of coarse aggregate, RAP, old asphalt, new aggregate and new asphalt.
[0043] S102, calibrate the mesoscopic parameters of the two-dimensional discrete element model; The specific values of the detailed parameters are shown in Table 4 below: Table 4
[0044] S103, load the two-dimensional discrete element model and detect microcrack information during the loading process of the two-dimensional discrete element model; As the loading process progresses, the deformation of the two-dimensional discrete element model accumulates continuously. The crack monitoring program can monitor in real time the initiation, development and continuous expansion of microcracks in various regions inside the two-dimensional discrete element model until the loading ends.
[0045] S104, Construct slip bands based on microcrack information and calculate the microcrack density of slip bands; The slip zone is a band-shaped crack located inside the RAP and at the interface between the RAP and the new asphalt.
[0046] It should be noted that the characteristics of the slip zone formation in recycled asphalt mixtures are: microcracks in the concentrated RAP area develop along the old asphalt on the RAP surface, gradually forming through cracks that lead to cracking of the recycled asphalt mixture. The slip zone is a weak area of the recycled asphalt mixture and also the area with the highest risk of cracking failure in the specimen. From a microscopic perspective, micropores are distributed between the old asphalt and aggregate on the RAP surface. Under load, microcracks in the concentrated RAP area initiate and rapidly expand, forming a slip zone that leads to cracking of the recycled asphalt mixture. In this invention, microcracks within the slip zone range are referred to as effective microcracks, while microcracks in other areas are referred to as ineffective microcracks. Among them, effective microcracks are mainly distributed within the slip zone range and will cause cracking failure of the mixture, resulting in the loss of the load-bearing capacity of the recycled asphalt mixture and its inability to serve normally; ineffective microcracks, although causing internal damage to the mixture, do not expand into macroscopic cracks, and the recycled asphalt mixture still maintains basic road performance; effective microcracks account for about 60-70%, and ineffective microcracks account for about 30-40%. Figure 6 As shown, the slip bands are unevenly distributed in the recycled asphalt mixture, and their main characteristics include: (1) There are multiple slip zones, and their lengths and inclination angles are all different; (2) The inclination angle of the slip zone refers to the inclination angle between the slip zone and the direction of load application; (3) Partially penetrating slip zones cause cracking of recycled asphalt mixtures, while partially non-penetrating slip zones only damage the recycled asphalt mixtures and do not cause cracking of the mixtures.
[0047] Accordingly, the steps for constructing slip bands based on microcrack information include: (1) Detect the bonding fracture points generated by the linear parallel bonding model during the loading process of the two-dimensional discrete element model; In each load step or time step, the bond fracture information of all bond fracture points is recorded; the bond fracture information includes the spatial coordinates (x, y) of the bond fracture point and the type of bond fracture point (including RAP inside, RAP and new asphalt interface, new asphalt inside, and new asphalt and aggregate interface). (2) Extract the bonding fracture points inside RAP and at the interface between RAP and new asphalt as reference fracture points; (3) Divide the two-dimensional discrete element model into several grid units; Generally, the side length of each grid cell is taken as 10 times the diameter of the round particles (0.2~0.3mm).
[0048] (4) Calculate the microcrack density of each mesh element based on the reference fracture point; Corresponding microcrack density The calculation formula is:
[0049] in, For grid cells The number of reference fracture points within, For grid cells The area.
[0050] (5) Use the grid cells with microcrack density greater than the preset slip band threshold as the reference cells, and use the reference fracture point in the reference cells as the target fracture point; Generally, the preset slip band threshold is the average value of the microcrack sub-densities of all grid cells plus 1 to 2 times the standard deviation.
[0051] (6) Construct a slip zone based on the target fracture point.
[0052] Furthermore, the steps for constructing a slip zone based on the target fracture point include: (6.1) Take the target fracture point with the largest Y-coordinate as the starting point; (6.2) Take the target fracture point adjacent to the starting point as the midpoint; (6.3) Take the target break point adjacent to the midpoint as the endpoint; (6.4) Connect the starting point, midpoint, and ending point to form a sliding segment; (6.5) Determine whether the included angle of the sliding segment is within the preset included angle range; This invention requires that the angle between the line connecting the starting point and the midpoint and the line connecting the midpoint and the ending point be less than 30°.
[0053] (6.6) If the judgment is yes, take the midpoint as the new starting point, take the end point as the new midpoint, and return to step (6.3) until there are no adjacent target break points at the midpoint; (6.7) If the judgment is negative, take the other target break point adjacent to the midpoint as the new endpoint, delete the slip segment and return to step (6.4) until there are no adjacent target break points at the midpoint; (6.8) Combine the slip segments into slip bands and delete the target fracture points corresponding to the slip bands. Return to step (6.1) until all target fracture points have been constructed.
[0054] It should be noted that the target break point on the slip zone cannot be calculated repeatedly. After the search of one slip zone is completed, start the search of the second slip zone according to the above steps, until all slip zones have been searched.
[0055] Since ineffective microcracks do not directly cause material failure, this invention only counts effective microcracks within the slip band; ineffective microcracks are not included in the statistics. Accordingly, the microcrack density of the slip band can be calculated using the following formula:
[0056] in: The microcrack density of the slip zone is expressed in % (%). The area of the slip zone is in mm. 2 ; The area of the two-dimensional discrete element model is expressed in mm. 2 .
[0057] Further, calculate the area of the slip zone. In general, the length of the slip zone is taken as the side length, and the width is n times the diameter of the round particle (n can be 3, but is not limited to this value); therefore, the product of the side length and the width is the area of the slip zone.
[0058] S105, evaluate the performance of the target recycled asphalt mixture based on the microcrack density of the slip zone.
[0059] The specific performance classifications are shown in Table 5 below: Table 5
[0060] As can be seen from the above, the present invention uses the microcrack density of slip zone to quantitatively characterize the performance of recycled asphalt mixture, and the specific performance grades are excellent, good, medium and poor.
[0061] See Figure 7 , Figure 7The flowchart of a second embodiment of the performance evaluation method for recycled asphalt mixtures based on crushable aggregates of the present invention is shown, which includes: S201, Construct a two-dimensional discrete element model of the target recycled asphalt mixture; S202, calibrating the mesoscopic parameters of the two-dimensional discrete element model; S203, loads the two-dimensional discrete element model and detects the breakage information during the loading process of the two-dimensional discrete element model; like Figure 8 As shown, based on the differences in the direction of stress concentration and the failure mechanism, aggregate crushing is categorized into four typical failure modes: compressive crushing, compressive fracture, shear crushing, and shear fracture. The arrows in the figure indicate the direction of load application, and the stress concentration effect at the contact interface is the direct cause of aggregate failure.
[0062] Under load, the aggregate and asphalt are displaced, and the asphalt mixture specimen undergoes permanent deformation. In some areas, the coarse aggregate breaks due to stress concentration, while from a microscopic perspective, it manifests as ball-ball parallel bond fracture.
[0063] S204, Calculate the aggregate crushing rate based on crushing information; It should be noted that the aggregate crushing rate is the ratio of the area of the crushed coarse aggregate to the area of the two-dimensional discrete element model.
[0064] Accordingly, the calculation methods for the area of crushed coarse aggregate include: (1) Detect the bonding fracture points generated by the linear parallel bonding model during the loading process of the two-dimensional discrete element model; (2) The area of the coarse aggregate particle model corresponding to the bonding fracture point is taken as the area of the crushed coarse aggregate.
[0065] S205 evaluates the performance of target recycled asphalt mixtures based on aggregate crushing ratio.
[0066] and Figure 1 Unlike the first embodiment shown, this embodiment uses aggregate crushing rate as the evaluation index, and the specific performance classification is shown in Table 6 below: Table 6
[0067] As can be seen from the above, the present invention uses aggregate crushing rate to quantitatively characterize the performance of recycled asphalt mixture, and the specific performance grades are excellent, good, medium and poor.
[0068] See Figure 9 , Figure 9 The flowchart of a third embodiment of the performance evaluation method for recycled asphalt mixtures based on crushable aggregates of the present invention is shown, which includes: S301, Construct a two-dimensional discrete element model of the target recycled asphalt mixture; S302, calibrating the mesoscopic parameters of the two-dimensional discrete element model; S303 loads a two-dimensional discrete element model and detects microcrack and fracture information during the loading process. S304, construct slip bands based on microcrack information and calculate the microcrack density of slip bands; S305, calculate the aggregate crushing rate based on crushing information; S306 evaluates the performance of target recycled asphalt mixtures based on the microcrack density of the slip zone and the aggregate breakage rate.
[0069] and Figure 1 Unlike the first embodiment shown, this embodiment uses both the microcrack density of the slip zone and the aggregate breakage rate as evaluation indicators.
[0070] Accordingly, the steps for evaluating the performance of the target recycled asphalt mixture based on the microcrack density and aggregate breakage rate of the slip zone include: (1) Evaluate the performance of the target recycled asphalt mixture based on the microcrack density of the slip zone to output the first evaluation level; (2) Evaluate the performance of the target recycled asphalt mixture based on the aggregate crushing rate to output the second evaluation level; (3) The lower of the first and second evaluation levels shall be used as the final evaluation level.
[0071] For example, when the microcrack density of the slip zone of the target recycled asphalt mixture is 6% and the aggregate crushing rate is 5%, the first evaluation level can be output as "good" based on Table 5 of the first embodiment, and the second evaluation level can be output as "medium" based on Table 6 of the second embodiment. Combining the first evaluation level and the second evaluation level, the final evaluation level can be obtained as "medium".
[0072] In summary, this invention introduces a novel two-dimensional discrete element model (DEM) construction method for evaluating the performance of recycled asphalt mixtures based on crushable aggregates. By specifically treating the indestructible particles within the two-dimensional coarse aggregate contour model, crushable particles are introduced to fill the model. A linear parallel bonding model is then used to bond these crushable particles within the coarse aggregate particle model, effectively simulating the bonding performance of recycled asphalt mixtures and giving the two-dimensional DEM model a crushable characteristic. Furthermore, this invention innovatively introduces the microcrack density of the slip zone and the aggregate breakage rate as evaluation indicators, providing a completely new perspective for accurately evaluating the performance of recycled asphalt mixtures and thus enabling better adjustment of the mix proportions.
[0073] Accordingly, the present invention also provides a computer device, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps of the above-described performance evaluation method for recycled asphalt mixtures based on crushable aggregates.
[0074] In addition, the present invention also provides a computer-readable storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, implements the steps of the above-described performance evaluation method for recycled asphalt mixtures based on crushable aggregates.
[0075] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.
Claims
1. A method for performance evaluation of a recycled asphalt mixture based on breakable aggregates, characterized by, The method comprises the following steps: constructing a two-dimensional discrete element model of a target recycled asphalt mixture, the two-dimensional discrete element model being used to represent coarse aggregate, RAP, old asphalt, new aggregate and new asphalt; calibrating the mesoscopic parameters of the two-dimensional discrete element model; loading the two-dimensional discrete element model and detecting micro-crack information and / or breakage information of the two-dimensional discrete element model during the loading process; constructing a slip band according to the micro-crack information and calculating the micro-crack density of the slip band, the slip band being a band-shaped crack located inside the RAP and at the interface between the RAP and the new asphalt; calculating the aggregate breakage rate according to the breakage information; evaluating the performance of the target recycled asphalt mixture according to the micro-crack density of the slip band and / or the aggregate breakage rate.
2. The method for performance evaluation of the regenerative asphalt mixture based on the breakable aggregate according to claim 1, characterized in that, The step of constructing the two-dimensional discrete element model of the target recycled asphalt mixture comprises: constructing a two-dimensional wall model of the target recycled asphalt mixture; extracting a two-dimensional coarse aggregate profile model from a preset two-dimensional coarse aggregate profile model set according to the gradation information of the target recycled asphalt mixture to construct a coarse aggregate particle model, and filling the coarse aggregate particle model with non-breakable particles in the two-dimensional wall model; constructing a first particle model to represent new asphalt, and filling the first particle model in the two-dimensional wall model; deleting the non-breakable particles in the coarse aggregate particle model; constructing breakable particles and filling the breakable particles in the coarse aggregate particle model; bonding the breakable particles in the coarse aggregate particle model through a linear parallel bonding model; constructing a second particle model to represent old asphalt, and covering the second particle model on the surface of the RAP; representing coarse aggregate, RAP, old asphalt, new aggregate and new asphalt by different colors.
3. The method for performance evaluation of the regenerative asphalt mixture based on the breakable aggregate according to claim 2, characterized in that, The step of constructing the two-dimensional coarse aggregate profile model set comprises: collecting three-dimensional coarse aggregate morphology of coarse aggregate; projecting the three-dimensional coarse aggregate morphology to generate a two-dimensional coarse aggregate profile model.
4. The method for evaluating the performance of a regenerative asphalt mixture based on breakable aggregates according to claim 1, characterized in that, The step of calculating the micro-crack density of the slip band comprises: The microcrack density of the slip band is calculated according to the formula ; wherein, is the microcrack density of the slip band, is the slip band area, is the two-dimensional discrete element model area.
5. The method for evaluating the performance of a regenerative asphalt mixture based on breakable aggregates according to claim 1, characterized in that, The step of constructing the slip band according to the micro-crack information comprises: detecting bonding breakage points generated by the linear parallel bonding model during the loading process of the two-dimensional discrete element model; extracting the bonding breakage points inside the RAP and at the interface between the RAP and the new asphalt as reference breakage points; dividing the two-dimensional discrete element model into a plurality of grid cells; calculating the micro-crack sub-density of each grid cell according to the reference breakage points; taking the grid cells with micro-crack sub-density greater than a preset slip band threshold as reference cells, and taking the reference breakage points in the reference cells as target breakage points; constructing a slip band according to the target breakage points.
6. The method for performance evaluation of the regenerative asphalt mixture based on the breakable aggregate according to claim 5, characterized in that, The step of constructing the slip band according to the target breakage points comprises: S1, taking the target breakage point with the maximum Y coordinate as a starting point; S2, taking a target breakage point adjacent to the starting point as a midpoint; S3, taking a target breakage point adjacent to the midpoint as an ending point; S4, connecting the starting point, the midpoint and the ending point to form a slip segment; S5, judging whether the included angle of the slip segment is within a preset included angle range; S6, if yes, taking the midpoint as a new starting point and the endpoint as a new midpoint, and returning to step S3 until the midpoint has no adjacent target fracture point; S7, if no, taking another target fracture point adjacent to the midpoint as a new endpoint, deleting the slip segment and returning to step S4 until the midpoint has no adjacent target fracture point; S8, combining the slip segments into a slip band and deleting the target fracture point corresponding to the slip band, and returning to step S1 until all target fracture points are completed.
7. The method for evaluating the performance of a regenerative asphalt mixture based on breakable aggregates according to claim 2, characterized in that, The aggregate crushing rate is a ratio of a broken coarse aggregate area to a two-dimensional discrete element model area.
8. The method for performance evaluation of a regenerative asphalt mixture based on breakable aggregates according to claim 7, characterized in that, The method for calculating the broken coarse aggregate area comprises: detecting a bond fracture point generated by a linear parallel bond model in a loading process of the two-dimensional discrete element model; taking an area of a coarse aggregate particle model corresponding to the bond fracture point as the broken coarse aggregate area.
9. The method for evaluating the performance of a regenerative asphalt mixture based on breakable aggregates according to claim 1, characterized in that, The step of evaluating the performance of the target recycled asphalt mixture according to the microcrack density of the slip band and the aggregate crushing rate comprises: evaluating the performance of the target recycled asphalt mixture according to the microcrack density of the slip band to output a first evaluation level; evaluating the performance of the target recycled asphalt mixture according to the aggregate crushing rate to output a second evaluation level; taking an evaluation result of a lower level between the first evaluation level and the second evaluation level as a final evaluation level. 10.A computer device, comprising a memory and a processor, wherein the memory stores a computer program, and the computer device is configured to perform the method according to any one of claims 1-9. The processor executes the computer program to implement the steps of the performance evaluation method of the recyclable aggregate-based recycled asphalt mixture according to any one of claims 1 to 9.
11. A computer readable storage medium having stored thereon a computer program, characterized in that, The computer program is executed by the processor to implement the steps of the performance evaluation method of the recyclable aggregate-based recycled asphalt mixture according to any one of claims 1 to 9.