A composite geometric characteristic evaluation method and system for recycled asphalt mixture

Abstract

The present invention discloses a composite geometric characteristic evaluation method and system for recycled asphalt mixture, the method comprising: recycling old asphalt mixture, extracting and screening the old asphalt mixture, and measuring the relative density and crushing value of each grade of new and old aggregates after screening; measuring the geometric characteristic parameters of the new and old aggregates to determine the geometric characteristics of the new and old aggregates; determining the blending ratio of each grade of new and old aggregates, and preparing based on the blending ratio to obtain recycled asphalt mixture; analyzing the geometric characteristics and particle size differences to obtain the geometric measurement and average particle size of the new and old aggregates in each grade of recycled asphalt mixture; constructing a geometric parameter calculation model based on relative density, crushing value, geometric measurement and average particle size, and using the geometric parameter calculation model to evaluate the geometric characteristics. The present invention is helpful to quantitatively evaluate the comprehensive contribution of the geometric characteristics and particle size of new and old aggregates to the contact friction characteristics of recycled asphalt mixture.

Description

Technical Field

[0001] The invention belongs to the technical field of road engineering, and in particular relates to a method and system for evaluating composite geometric characteristics of recycled asphalt mixture. Background Art

[0002] Hot recycled asphalt mixture refers to a composite material formed by adding a certain proportion of new aggregate, new asphalt and regeneration agent to the old asphalt pavement after milling, crushing, screening and other treatments. The old aggregate is obtained by extracting and recovering asphalt from waste asphalt mixture. Under the long-term action of traffic load and environmental factors, the morphological structure of the aggregate changes, which is mainly manifested in weakened edges and corners, worn surface texture and increased needle-like content. In order to measure the geometric characteristics of aggregates, domestic and foreign scholars have conducted extensive research on new aggregates and recycled old materials using aggregate image acquisition systems, CT scanning and other technologies. However, after the new and old aggregates are recombined, the geometric morphology and physical properties of the new and old aggregates are different, and the blending ratio and particle size distribution of each grade of aggregate are also different. There is no effective measurement method for how to characterize the composite geometric characteristics of recycled graded mineral materials. Summary of the invention

[0003] The present invention aims to address the deficiencies of the prior art and proposes a composite geometric characteristic evaluation method and system for recycled asphalt mixture, so as to quantitatively evaluate the comprehensive contribution of the geometric characteristics and particle size of new and old aggregates to the contact friction characteristics of recycled asphalt mixture.

[0004] To achieve the above object, the present invention provides the following solutions:

[0005] A method for evaluating composite geometric characteristics of recycled asphalt mixture comprises the following steps:

[0006] Recovering old asphalt mixture, extracting and screening the old asphalt mixture, and measuring the relative density and crushing value of each level of new and old aggregates after screening;

[0007] Measuring geometric characteristic parameters of the new and old aggregates to determine the geometric properties of the new and old aggregates;

[0008] Determining the blending ratio of each grade of new and old aggregates, and preparing the recycled asphalt mixture based on the blending ratio to obtain the recycled asphalt mixture;

[0009] Analyze the geometric characteristics and particle size differences to obtain geometric measurements and average particle sizes of new and old aggregates in each grade of the recycled asphalt mixture;

[0010] Based on the relative density, the crushing value, the geometric measurement and the average particle size, a geometric parameter calculation model is constructed, and the geometric feature evaluation is performed using the geometric parameter calculation model.

[0011] Preferably, the extraction and screening method comprises:

[0012] Using trichloroethylene to dissolve and recover the asphalt on the surface of the old asphalt mixture, and extracting to obtain clean aggregate;

[0013] The extracted aggregate is screened and stored in grades to obtain several grades of new and old aggregate.

[0014] Preferably, the geometric characteristic parameters include: sphericity, texture coefficient and angular gradient;

[0015] The geometric characteristics include: shape characteristics, texture characteristics and angularity.

[0016] Preferably, the method for obtaining the geometric measurement includes: spatially spreading and reorganizing the new and old aggregates based on the shape characteristics, the texture characteristics and the angularity, and analyzing the reorganized geometric structure to obtain the geometric measurement.

[0017] Preferably, the method for obtaining the average particle size comprises:

[0018] Comparative analysis of the geometrical properties and the weakening of the geometrical morphology of the new and old aggregates due to environmental factors and milling recovery;

[0019] Based on the weakening condition and the difference in particle sizes between the new and old aggregates in each batch, the average particle size of the new and old aggregates in each batch is calculated.

[0020] Preferably, the geometric parameter calculation model includes:

[0021] Composite Shape Index Model:

[0022]

[0023] Composite Texture Index Model:

[0024]

[0025] Composite angular index model:

[0026]

[0027] Where N represents new aggregate, R represents old aggregate, and RCI SP Represents the composite shape index, RCI TX Represents composite texture index, RCI GA represents the composite angularity index, a i represents the mass fraction of the i-th grade aggregate, g i Represents the relative density of the i-th grade aggregate, d i represents the average particle size of the i-th batch of aggregate, represents the crushing value of the i-th batch of aggregate, C wi represents the weighted perimeter of the i-th aggregate particle, SA wi represents the weighted surface area of ​​the i-th aggregate particle, V wi represents the weighted volume of aggregate particles in the i-th level, SP i Indicates the sphericity of the aggregate particles in the i-th batch, TX i represents the texture coefficient of the i-th aggregate particle, GA i Represents the angular gradient of the i-th grade aggregate particles.

[0028] The present invention also provides a composite geometric characteristic evaluation system for recycled asphalt mixture, the evaluation system applies any of the above evaluation methods, including: a waste material processing module, a geometric characteristic measurement module, a preparation module, a first analysis module and a second analysis module;

[0029] The old material processing module is used to recycle old asphalt mixture, extract and screen the old asphalt mixture, and measure the relative density and crushing value of each level of new and old aggregates after screening;

[0030] The geometric property measurement module is used to measure the geometric characteristic parameters of the new and old aggregates to determine the geometric properties of the new and old aggregates;

[0031] The preparation module is used to determine the blending ratio of each grade of new and old aggregates, and prepare the recycled asphalt mixture based on the blending ratio to obtain the recycled asphalt mixture;

[0032] The first analysis module is used to analyze the geometric characteristics and particle size differences to obtain the geometric measurements and average particle size of the new and old aggregates in each batch of the recycled asphalt mixture;

[0033] The second analysis module is used to construct a geometric parameter calculation model based on the relative density, the crushing value, the geometric measurement and the average particle size, and use the geometric parameter calculation model to perform geometric feature evaluation.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] The present invention not only measures the shape, texture and angular characteristics of new and old aggregates, but also measures the particle size and a series of physical indicators. These parameters are integrated to establish a calculation model for the composite geometric characteristic parameters of recycled asphalt mixture, which helps to quantitatively evaluate the comprehensive contribution of the geometric characteristics and particle size of new and old aggregates to the contact friction characteristics of recycled asphalt mixture. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solution of the present invention, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0037] Figure 1 A schematic diagram of a method flow of an embodiment of the present invention;

[0038] Figure 2 Schematic diagram of the system structure of an embodiment of the present invention. DETAILED DESCRIPTION

[0039] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0041] Embodiment 1

[0042] In this embodiment, if Figure 1 As shown, a method for evaluating composite geometric characteristics of recycled asphalt mixture comprises the following steps:

[0043] S1. Recycle the old asphalt mixture, extract and screen the old asphalt mixture, and measure the relative density and crushing value of each grade of new and old aggregates after screening.

[0044] The extraction and screening method includes: using trichloroethylene to dissolve and recover the asphalt on the surface of the old asphalt mixture, extracting to obtain clean aggregate; screening the extracted aggregate and storing it in grades to obtain several grades of old aggregate.

[0045] S2. Measure the geometric characteristic parameters of the new and old aggregates to determine the geometric properties of the new and old aggregates.

[0046] In this embodiment, the aggregate image acquisition device AIMS is used to measure geometric characteristic parameters, including sphericity, texture coefficient and angular gradient; the geometric characteristics include shape characteristics, texture characteristics and angularity.

[0047] S3. Determine the blending ratio of each grade of new and old aggregates, and prepare the recycled asphalt mixture based on the blending ratio to obtain the recycled asphalt mixture.

[0048] S4. Analyze the geometric characteristics and particle size differences to obtain the geometric measurements and average particle size of the new and old aggregates in each grade of recycled asphalt mixture.

[0049] The method for obtaining the geometric measurement includes: spatially spreading and reorganizing the new and old aggregates based on shape characteristics, texture characteristics and angularity, and analyzing the reorganized geometric structure to obtain the geometric measurement.

[0050] In this embodiment, the method for obtaining the average particle size includes: comparing and analyzing the geometric characteristics of the new and old aggregates according to the sphericity, texture coefficient and angular gradient index measured by the AIMS device, and then analyzing the weakening of the geometric morphology of the new and old aggregates under vehicle load, environmental factors and milling recovery process; based on the weakening condition and the difference in particle size of each batch of new and old aggregates, calculating the average particle size of each batch of new and old aggregates.

[0051] Here is an example of old aggregate:

[0052]

[0053] Among them, P i+1 Indicates the mesh size of the i+1th level, Q i Indicates the average particle size adjustment factor.

[0054] S5. Based on the relative density, crushing value, geometric measurement and average particle size, a geometric parameter calculation model is constructed, and the geometric characteristics are evaluated using the geometric parameter calculation model.

[0055] The geometric parameter calculation model includes:

[0056] Composite Shape Index Model:

[0057]

[0058] Composite Texture Index Model:

[0059]

[0060] Composite angular index model:

[0061]

[0062] Where N represents new aggregate, R represents old aggregate, and RCI SP Represents the composite shape index, RCI TX Represents composite texture index, RCI GA represents the composite angularity index, a i represents the mass fraction of the i-th grade aggregate, g i Represents the relative density of the i-th grade aggregate, d i represents the average particle size of the i-th batch of aggregate, represents the crushing value of the i-th batch of aggregate, C wi represents the weighted perimeter of the i-th aggregate particle, SA wi represents the weighted surface area of ​​the i-th aggregate particle, V wi represents the weighted volume of aggregate particles in the i-th level, SP i Indicates the sphericity of the aggregate particles in the i-th batch, TX i represents the texture coefficient of the i-th aggregate particle, GA i Represents the angular gradient of the i-th grade aggregate particles.

[0063] Embodiment 2

[0064] In this embodiment, the AC-13 old asphalt pavement recycled from a certain expressway is taken as an example to introduce the method flow of the present invention.

[0065] After extraction and recovery with trichloroethylene, the relative density and crushing value of the old aggregate were measured, as shown in Table 1.

[0066] Table 1

[0067]

[0068] The aggregate image acquisition system AIMS was used to measure the sphericity of new and old coarse aggregates, as shown in Table 2.

[0069] Table 2

[0070]

[0071] The blending ratio of old aggregate is determined to be 30% and then prepared.

[0072] Compare and analyze the similarities and differences in the geometric properties and particle sizes of the new and old aggregates, and determine the geometric measurements and average particle size of the old aggregate.

[0073] According to Table 2, after vehicle load, environmental factors and milling recovery process, the sphericity value of the old aggregate is slightly larger than that of the new aggregate, which indicates that the old aggregate has undergone wear and tear, the surface structure has changed, and the edges and textures have been lost. The shapes of the new and old aggregates are spatially spread and reorganized, and the geometric measurement of the shapes of the new and old aggregates is a one-dimensional straight line.

[0074] The three-dimensional mid-long sides of the new and old aggregates were measured, as shown in Table 3.

[0075] Table 3

[0076]

[0077] It can be seen that the particle size of the same grade of old aggregate is smaller than that of the new aggregate, which means that the gradation of the old aggregate has not only changed, but also tends to become finer. Therefore, the average particle size of the old aggregate is expressed as:

[0078]

[0079] The calculation model of composite geometric parameters of recycled asphalt mixture is established as follows:

[0080] Composite Shape Index Model:

[0081]

[0082] Composite Texture Index Model:

[0083]

[0084] Composite angular index model:

[0085]

[0086] The above formula is used to calculate the composite shape index RCI of AC-13 recycled asphalt mixture SP , which is 0.001573.

[0087] Embodiment 3

[0088] In this embodiment, a composite geometric characteristic evaluation system for recycled asphalt mixture includes: a waste material processing module, a geometric characteristic measurement module, a preparation module, a first analysis module and a second analysis module.

[0089] The old material processing module is used to recycle old asphalt mixture, extract and screen the old asphalt mixture, and measure the relative density and crushing value of each level of new and old aggregates after screening.

[0090] The workflow of the old material processing module includes: using trichloroethylene to dissolve and recover the asphalt on the surface of the old asphalt mixture, and extracting clean aggregates; screening the extracted aggregates and storing them in grades to obtain several grades of new and old aggregates; measuring the relative density and crushing value of each grade of new and old aggregates after screening.

[0091] The geometric property measurement module is used to measure the geometric characteristic parameters of new and old aggregates and determine the geometric properties of new and old aggregates.

[0092] In this embodiment, the aggregate image acquisition device AIMS is used to measure geometric characteristic parameters, including sphericity, texture coefficient and angular gradient; the geometric characteristics include shape characteristics, texture characteristics and angularity.

[0093] The preparation module is used to determine the blending ratio of each grade of new and old aggregates, and prepare them based on the blending ratio to obtain recycled asphalt mixture.

[0094] The first analysis module is used to analyze the geometric characteristics and particle size differences to obtain the geometric measurements and average particle size of the new and old aggregates in each grade of recycled asphalt mixture.

[0095] The workflow of the first analysis module includes: spatially spreading and reorganizing the new and old aggregates based on shape characteristics, texture characteristics and angularity, and analyzing the reorganized geometric structure to obtain geometric measurements; comparing and analyzing the geometric characteristics of the new and old aggregates according to the sphericity, texture coefficient and angular gradient index measured by the AIMS device, and then analyzing the weakening of the geometric morphology of the new and old aggregates under vehicle load, environmental factors and milling and recycling processes; calculating the average particle size of each batch of new and old aggregates based on the weakening situation and the difference in particle size between each batch of new and old aggregates.

[0096] The second analysis module is used to construct a geometric parameter calculation model based on relative density, crushing value, geometric measurement and average particle size, and use the geometric parameter calculation model to evaluate geometric characteristics.

[0097] The geometric parameter calculation model includes:

[0098] Composite Shape Index Model:

[0099]

[0100] Composite Texture Index Model:

[0101]

[0102] Composite angular index model:

[0103]

[0104] Where N represents new aggregate, R represents old aggregate, and RCI SP Represents the composite shape index, RCI TX Represents composite texture index, RCI GA represents the composite angularity index, a i represents the mass fraction of the i-th grade aggregate, g i Represents the relative density of the i-th grade aggregate, d i represents the average particle size of the i-th batch of aggregate, represents the crushing value of the i-th batch of aggregate, C wi represents the weighted perimeter of the i-th aggregate particle, SA wi represents the weighted surface area of ​​the i-th aggregate particle, V wi represents the weighted volume of aggregate particles in the i-th level, SP i Indicates the sphericity of the aggregate particles in the i-th batch, TX i represents the texture coefficient of the i-th aggregate particle, GA i Represents the angular gradient of the i-th grade aggregate particles.

[0105] The embodiments described above are only descriptions of the preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for evaluating composite geometric characteristics of recycled asphalt mixture, characterized in that: The following steps are involved: Recovering old asphalt mixture, extracting and screening the old asphalt mixture, and measuring the relative density and crushing value of each level of new and old aggregates after screening; Measuring geometric characteristic parameters of the new and old aggregates to determine the geometric properties of the new and old aggregates; Determining the blending ratio of each grade of new and old aggregates, and preparing the recycled asphalt mixture based on the blending ratio to obtain the recycled asphalt mixture; Analyze the geometric characteristics and particle size differences to obtain geometric measurements and average particle sizes of new and old aggregates in each grade of the recycled asphalt mixture; constructing a geometric parameter calculation model based on the relative density, the crushing value, the geometric measurement and the average particle size, and performing geometric feature evaluation using the geometric parameter calculation model; The geometric characteristic parameters include: sphericity, texture coefficient and angular gradient; The geometric characteristics include: shape characteristics, texture characteristics and angularity; The method for obtaining the geometric measure includes: spatially spreading and reorganizing the new and old aggregates based on the shape characteristics, the texture characteristics and the angularity, and analyzing the reorganized geometric structure to obtain the geometric measure; The method for obtaining the average particle size includes: Comparative analysis of the geometrical properties and the weakening of the geometrical morphology of the new and old aggregates due to environmental factors and milling recovery; Based on the weakening condition and the difference in particle sizes between the new and old aggregates at each level, calculating the average particle size of the new and old aggregates at each level; The geometric parameter calculation model includes: Composite Shape Index Model: Composite Texture Index Model: Composite angular index model: Where N represents new aggregate, R represents old aggregate, and RCI SP Represents the composite shape index, RCI TX Represents composite texture index, RCI GA represents the composite angularity index, a i represents the mass fraction of the i-th grade aggregate, g i Represents the relative density of the i-th grade aggregate, d i represents the average particle size of the i-th batch of aggregate, represents the crushing value of the i-th batch of aggregate, C wi represents the weighted perimeter of the i-th aggregate particle, SA wi represents the weighted surface area of ​​the i-th aggregate particle, V wi represents the weighted volume of aggregate particles in the i-th level, SP i Indicates the sphericity of the aggregate particles in the i-th batch, TX i represents the texture coefficient of the i-th aggregate particle, GA i Represents the angular gradient of the i-th grade aggregate particles.

2. According to claim 1, a method for evaluating composite geometric characteristics of recycled asphalt mixture is characterized in that: The extraction and screening method comprises: Using trichloroethylene to dissolve and recover the asphalt on the surface of the old asphalt mixture, and extracting to obtain clean aggregate; The extracted aggregate is screened and stored in grades to obtain several grades of new and old aggregate.

3. A composite geometric feature evaluation system for recycled asphalt mixture, the evaluation system applying the evaluation method according to any one of claims 1-2, characterized in that: include: A waste material processing module, a geometric property measurement module, a preparation module, a first analysis module and a second analysis module; The old material processing module is used to recycle old asphalt mixture, extract and screen the old asphalt mixture, and measure the relative density and crushing value of each level of new and old aggregates after screening; The geometric property measurement module is used to measure the geometric characteristic parameters of the new and old aggregates to determine the geometric properties of the new and old aggregates; The preparation module is used to determine the blending ratio of each grade of new and old aggregates, and prepare the recycled asphalt mixture based on the blending ratio to obtain the recycled asphalt mixture; The first analysis module is used to analyze the geometric characteristics and particle size differences to obtain the geometric measurements and average particle size of the new and old aggregates in each batch of the recycled asphalt mixture; The second analysis module is used to construct a geometric parameter calculation model based on the relative density, the crushing value, the geometric measurement and the average particle size, and use the geometric parameter calculation model to perform geometric feature evaluation.

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