A method and system for evaluating low-temperature crack resistance of asphalt mixture pavement

Abstract

The present application provides a kind of asphalt mixture pavement low temperature crack resistance performance evaluation method and system, it is related to road material technical field, including: using nuclear magnetic resonance method obtains the microstructure parameter of to-be-measured asphalt mixture;Based on the first functional relationship of the pore size distribution density function and cumulative pore volume fraction obtained by classification theory, the mapping relationship of cumulative pore volume fraction and transverse relaxation time is determined by conversion and derivation to the first functional relationship;And based on the mapping relationship, the fractal dimension of the pore structure porosity corresponding to different pore diameters is determined;The comprehensive change rate and complexity of the microstructure parameter are used to construct asphalt mixture performance damage index;The low temperature crack resistance performance of to-be-measured asphalt mixture is negatively correlated with the damage index;The comprehensive change rate is related to the peak pore diameter cumulative porosity, the maximum slope of the peak cumulative pore diameter, and the complexity is related to the peak pore diameter cumulative porosity and the fractal dimension.

Description

Technical Field

[0001] This invention relates to the field of image processing technology, and in particular to a method and system for evaluating the low-temperature crack resistance of asphalt mixture pavement. Background Technology

[0002] Asphalt pavement refers to various types of pavement constructed from asphalt mixtures. Due to its excellent water resistance, durability, and fatigue performance, it has become one of the most widely used high-grade pavements in road construction. Among them, warm-mix recycled asphalt mixtures not only increase the content of recycled pavement material (RAP) and lower the construction temperature, but also improve the road performance of recycled pavements, which is of great significance in reducing resource waste. However, in cold northern regions, low-temperature cracking of asphalt pavements has become one of the major defects affecting road service life and driving safety. Affected by the severe winter climate, pavement materials become more brittle under low-temperature conditions, making them unable to resist the shrinkage stress caused by temperature changes and the dynamic stress caused by vehicle loads, easily forming micro-cracks that gradually expand into macro-cracks. Therefore, to improve the low-temperature crack resistance of warm-mix recycled asphalt mixture pavements, fibers, with their high strength and good toughness, have been demonstrated by numerous indoor tests and engineering practices. Incorporating fibers into recycled asphalt mixtures can delay the initiation and expansion of cracks in warm-mix recycled asphalt concrete pavements, thus improving crack resistance. The incorporation of basalt fiber with high tensile strength into recycled asphalt mixtures will further enhance the crack resistance of asphalt mixtures, extend the service life of pavements, and improve pavement durability.

[0003] However, existing methods for determining the enhancing effect of basalt fiber on the low-temperature crack resistance of warm-mix recycled asphalt pavement mainly focus on the study of macroscopic properties, and cannot objectively quantify the effect of basalt fiber on improving the performance of asphalt mixtures. Summary of the Invention

[0004] In view of this, the present invention proposes a method and system for evaluating the low-temperature crack resistance of asphalt mixture pavement.

[0005] The technical solution of this invention is implemented as follows: The first aspect of this invention provides a method for evaluating the low-temperature crack resistance of asphalt mixture pavements, comprising:

[0006] The microstructural parameters of the asphalt mixture to be tested were obtained using nuclear magnetic resonance (NMR); the asphalt mixture to be tested was an asphalt mixture containing basalt fibers; the microstructural parameters included the cumulative porosity of the peak pore size and the maximum slope of the cumulative peak pore size.

[0007] Based on fractal theory, the first functional relationship between pore size distribution density function and cumulative pore volume fraction is obtained. The first functional relationship is converted and derived to determine the mapping relationship between cumulative pore volume fraction and transverse relaxation time. Based on the mapping relationship, the fractal dimension of porosity corresponding to different pore sizes is determined.

[0008] The performance damage index of asphalt mixture is constructed using the comprehensive change rate and complexity of the microstructural parameters; the damage index is negatively correlated with the low-temperature crack resistance of the asphalt mixture under test; the comprehensive change rate is related to the cumulative porosity of the peak pore size and the maximum slope of the cumulative peak pore size, and the complexity is related to the cumulative porosity of the peak pore size and the fractal dimension.

[0009] Based on the above technical solutions, preferably, before obtaining the first functional relationship between the pore size distribution density function and the cumulative pore volume fraction based on fractal theory, the following is also included:

[0010] A second functional relationship is created between the pore structure distribution density function, the maximum pore diameter, the proportionality constant, and the fractal dimension based on fractal theory.

[0011] The second functional relationship is converted and derived to determine the aperture distribution density function; the aperture distribution density function is related to the fractal dimension.

[0012] Based on the above technical solutions, preferably, the step of converting and deriving the mapping relationship between the cumulative pore volume fraction and the transverse relaxation time for the first functional relationship includes:

[0013] The first functional relationship between the established pore size distribution density function and the cumulative pore volume fraction function is converted and derived. Combined with the measurement data of transverse relaxation time in nuclear magnetic resonance, the mapping relationship between the cumulative pore volume fraction and the transverse relaxation time is determined.

[0014] Based on the above technical solutions, preferably, the step of determining the fractal dimension of the porosity of pore structures corresponding to different pore sizes based on the mapping relationship includes:

[0015] A coordinate system is created by taking the logarithm of the cumulative pore volume fraction as the vertical axis and the logarithm of the transverse relaxation time as the horizontal axis, to obtain the mapping relationship between the cumulative pore volume fraction and the transverse relaxation time, and the slope of the curve corresponding to the mapping relationship is determined as the fractal dimension of the corresponding pore size.

[0016] Based on the above technical solutions, preferably, the construction of the asphalt mixture performance damage index using the comprehensive change rate and complexity of the microstructural parameters includes:

[0017] The first pore size, the second pore size, and the third pore size are determined based on the curve peaks in the transverse relaxation time spectrum and the cumulative porosity distribution curve of the asphalt mixture to be tested; the first pore size is smaller than the second pore size, and the second pore size is smaller than the third pore size.

[0018] The maximum slope of the transverse relaxation time spectrum and the cumulative porosity distribution curve corresponding to the first pore size, the second pore size and the third pore size, respectively, as well as the cumulative porosity corresponding to the first pore size, the second pore size and the third pore size are obtained respectively;

[0019] The rate of change of the microstructure parameters is determined based on the maximum slope and the cumulative porosity, and the sum of the rates of change of the first pore diameter, the second pore diameter, and the third pore diameter is determined as the comprehensive rate of change.

[0020] Based on the above technical solutions, preferably, the construction of the asphalt mixture performance damage index using the comprehensive change rate and complexity of the microstructural parameters includes:

[0021] The cumulative porosity and fractal dimension corresponding to the first pore size, the second pore size, and the third pore size are obtained respectively;

[0022] The structural performance index of each pore size is determined based on the cumulative porosity and the fractal dimension, and the sum of the structural performance indices of the first pore size, the second pore size, and the third pore size is determined as the complexity of the microstructure parameter.

[0023] Based on the above technical solutions, preferably, the method of constructing the asphalt mixture performance damage index using the comprehensive change rate and complexity of the microstructural parameters further includes:

[0024] The product of the comprehensive rate of change of the microstructural parameters and the complexity is determined as the damage index of the asphalt mixture to be tested.

[0025] Furthermore, in a second aspect, the present invention provides a system for evaluating the low-temperature crack resistance performance of asphalt mixture pavements, comprising: a parameter acquisition module, a function mapping module, and an index determination module; wherein,

[0026] The parameter acquisition module is configured to acquire the microstructure parameters of the asphalt mixture to be tested using nuclear magnetic resonance; the asphalt mixture to be tested is an asphalt mixture mixed with basalt fibers; the microstructure parameters include the cumulative porosity of the peak pore size and the maximum slope of the cumulative peak pore size.

[0027] The function mapping module is configured to obtain a first functional relationship between the pore size distribution density function and the cumulative pore volume fraction based on fractal theory, convert and derive the first functional relationship to determine the mapping relationship between the cumulative pore volume fraction and the transverse relaxation time, and determine the fractal dimension of the porosity of the pore structure corresponding to different pore sizes based on the mapping relationship.

[0028] The index determination module is configured to construct an asphalt mixture performance damage index using the comprehensive change rate and complexity of the microstructure parameters; the damage index is negatively correlated with the low-temperature crack resistance of the asphalt mixture under test; the comprehensive change rate is related to the cumulative porosity of the peak aperture and the maximum slope of the cumulative peak aperture, and the complexity is related to the cumulative porosity of the peak aperture and the fractal dimension.

[0029] More preferably, a third aspect of the present invention provides an electronic device, including a processor and a memory; the memory stores a computer program, wherein the computer program, when executed by the processor, implements the low-temperature crack resistance evaluation method for asphalt mixture pavement described in the first aspect.

[0030] More preferably, in a fourth aspect of the present invention, a computer storage medium is provided, on which a computer program is stored, wherein the computer program, when executed by a processor, implements the method for evaluating the low-temperature crack resistance performance of asphalt mixture pavement as described in the first aspect.

[0031] The low-temperature crack resistance evaluation method and system for asphalt mixture pavement of the present invention has the following advantages over the prior art:

[0032] 1. Microstructural parameters of asphalt mixtures were collected by nuclear magnetic resonance. The complexity of the pore structure of asphalt mixtures was quantitatively analyzed by pore fractal dimension. Based on the calculation results of fractal dimension and the rate of change of microstructural parameters, the influence of microstructural parameters on the crack resistance of basalt fiber asphalt mixtures was evaluated by fractal dimension quantification. The effect of basalt fiber asphalt mixture performance improvement was determined, which greatly improved the accuracy and reliability of the evaluation results.

[0033] 2. By constructing a mapping relationship between pore structure and transverse relaxation time using fractal theory, the fractal dimension of different pore sizes is quantified, directly linking the internal structure and macroscopic properties of the material, providing an objective basis at the microscopic level for the reinforcing effect of basalt fibers. By constructing a damage index based on the comprehensive rate of change and complexity, the optimization effect of basalt fibers on the pore structure is fully captured, directly quantifying the reinforcing effect and achieving an objective quantitative evaluation of the low-temperature crack resistance of basalt fibers in warm-mix recycled asphalt mixtures. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 A flowchart illustrating a method for evaluating the low-temperature crack resistance of asphalt mixture pavement according to an embodiment of the present invention;

[0036] Figure 2 A schematic diagram of the microstructure parameters of the blank group asphalt mixture provided in an embodiment of the present invention;

[0037] Figure 3 A schematic diagram of the microstructure parameters of the short-cut basalt fiber asphalt mixture provided in an embodiment of the present invention;

[0038] Figure 4 A schematic diagram of the microstructure parameters of the flocculent basalt fiber asphalt mixture provided in an embodiment of the present invention;

[0039] Figure 5 The nuclear magnetic resonance fractal dimension model provided in the embodiments of the present invention and Line graph;

[0040] Figure 6 The fracture energy density diagrams of three groups of asphalt mixtures under different freeze-thaw cycles are provided in the embodiments of the present invention.

[0041] Figure 7 The microstructural performance damage index C and macroscopic fracture energy density provided in the embodiments of the present invention Correlation analysis plot of values;

[0042] Figure 8 This is a schematic diagram of the structure of an asphalt mixture pavement low-temperature crack resistance evaluation system provided in an embodiment of the present invention;

[0043] Figure 9 This is a schematic diagram of the structure of an electronic device provided in an embodiment of the present invention. Detailed Implementation

[0044] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0045] In some embodiments, such as Figure 1 As shown, Figure 1 This is a flowchart illustrating a method for evaluating the low-temperature crack resistance of asphalt mixture pavement according to an embodiment of the present invention; the method for evaluating the low-temperature crack resistance of asphalt mixture pavement according to the present invention includes:

[0046] S110, the microstructure parameters of the asphalt mixture to be tested were obtained by nuclear magnetic resonance method; the asphalt mixture to be tested was an asphalt mixture mixed with basalt fiber; the microstructure parameters included the cumulative porosity of the crest pores and the maximum slope of the cumulative pores of the crests.

[0047] In this embodiment, the asphalt mixture to be tested can be a warm-mix recycled asphalt mixture with added chopped and flocculent basalt fibers; the microstructural parameters of each group of asphalt mixtures to be tested are obtained by nuclear magnetic resonance (NMR). The spectrum can effectively reflect the evolution of the internal pore structure of the specimen under freeze-thaw cycles, that is, the characteristic of the transverse component of nuclear magnetization decaying exponentially with time.

[0048] S120: Based on fractal theory, the first functional relationship between the pore size distribution density function and the cumulative pore volume fraction is obtained. The first functional relationship is converted and derived to determine the mapping relationship between the cumulative pore volume fraction and the transverse relaxation time. Based on the mapping relationship, the fractal dimension of the porosity of the pore structure corresponding to different pore sizes is determined.

[0049] Fractal theory quantifies the self-similarity and geometric complexity of pore structures through fractal dimensions. The pore size distribution density function describes the proportion of pore volume per unit pore size, while the cumulative pore volume fraction represents the percentage of pore volume with a pore size smaller than d in the total pore volume. The transverse relaxation time reflects the relaxation characteristics of the fluid within the pores and is directly proportional to the pore size.

[0050] In some embodiments, before obtaining the first functional relationship between the pore size distribution density function and the cumulative pore volume fraction based on fractal theory, the method further includes:

[0051] A second functional relationship is created between the pore structure distribution density function, the maximum pore diameter, the proportionality constant, and the fractal dimension based on fractal theory.

[0052] The second functional relationship is converted and derived to determine the aperture distribution density function; the aperture distribution density function is related to the fractal dimension.

[0053] In this embodiment, according to fractal theory, the diameter is greater than Number of pores It satisfies the power function relationship, as shown in equation (1):

[0054] (1)

[0055] In the formula: Characterizes the maximum pore size (μm). Characterizing the pore structure distribution density function, It is a proportionality constant. F represents the fractal dimension of the pore structure.

[0056] Taking the derivative of both sides of equation (1) simultaneously yields the aperture distribution density function, as shown in equation (2).

[0057] (2)

[0058] In the formula: M′ is a proportionality constant, .

[0059] In some embodiments, the mapping relationship between the cumulative pore volume fraction and the transverse relaxation time is determined by converting and deriving the first functional relationship, including:

[0060] The first functional relationship between the established pore size distribution density function and the cumulative pore volume fraction function is converted and derived. Combined with the measurement data of transverse relaxation time in nuclear magnetic resonance, the mapping relationship between the cumulative pore volume fraction and the transverse relaxation time is determined.

[0061] In asphalt mixtures, the pore volume with a pore size smaller than d can be represented by equation (3).

[0062] (3)

[0063] In the formula: Characterizes the minimum pore size (μm);

[0064] Combining equations (2) and (3), equation (4) can be derived:

[0065] (4)

[0066] Therefore, the cumulative pore volume fraction can be derived. As shown in equation (5).

[0067] (5)

[0068] In the formula: Characterizing total pore volume (μm3)

[0069] Due to dmax dmin, equation (5) can be simplified to equation (6):

[0070] (6)

[0071] Equation (7) is further derived from equations (1) and (6).

[0072] (7)

[0073] In the formula: It is represented as the maximum lateral relaxation time (ms).

[0074] Taking the logarithm of both sides of equation (7) yields equation (8).

[0075] (8)

[0076] get .

[0077] In some embodiments, determining the fractal dimension of the porosity of pore structures corresponding to different pore sizes based on the mapping relationship includes:

[0078] A coordinate system is created by taking the logarithm of the cumulative pore volume fraction as the vertical axis and the logarithm of the transverse relaxation time as the horizontal axis. The mapping relationship between the cumulative pore volume fraction and the transverse relaxation time is obtained, and the slope of the curve corresponding to the mapping relationship is determined as the fractal dimension of the corresponding pore size.

[0079] Here, outliers can be removed from the scattered data beforehand, and then the least squares method can be used to fit the scattered data to obtain the slope of the curve corresponding to the mapping relationship.

[0080] S130 uses the comprehensive change rate and complexity of microstructural parameters to construct the performance damage index of asphalt mixtures; the damage index is negatively correlated with the low-temperature crack resistance of the asphalt mixture under test; the comprehensive change rate is related to the cumulative porosity of the peak pore size and the maximum slope of the cumulative peak pore size, and the complexity is related to the cumulative porosity of the peak pore size and the fractal dimension.

[0081] In some embodiments, an asphalt mixture performance damage index is constructed using the combined rate of change and complexity of microstructural parameters, including:

[0082] The first pore size, second pore size, and third pore size are determined based on the curve peaks in the transverse relaxation time spectrum and cumulative porosity distribution curve of the asphalt mixture to be tested; the first pore size is smaller than the second pore size, and the second pore size is smaller than the third pore size.

[0083] The maximum slope of the transverse relaxation time spectrum and the cumulative porosity distribution curve corresponding to the first pore size, the second pore size and the third pore size, respectively, as well as the cumulative porosity corresponding to the first pore size, the second pore size and the third pore size are obtained respectively.

[0084] The rate of change of microstructural parameters is determined based on the maximum slope and cumulative porosity, and the sum of the rates of change of the first pore diameter, the second pore diameter, and the third pore diameter is determined as the comprehensive rate of change.

[0085] In this embodiment, the overall rate of change of the microstructural parameters, The spectral density and cumulative porosity distribution curves will exhibit a three-peak distribution, which can be defined as the first pore size, the second pore size, and the third pore size, respectively. The comprehensive rate of change of the microstructural parameters of the asphalt mixture under test can be expressed as:

[0086]

[0087] In the formula: The comprehensive rate of change of the microstructural parameters of the asphalt mixture under test; Characterizes the cumulative porosity corresponding to the first pore size portion; Characterizing the first aperture portion The maximum slope of the spectrum and cumulative porosity distribution curve; Characterizes the cumulative porosity corresponding to the second pore size portion; Characterizing the second aperture portion The maximum slope of the spectrum and cumulative porosity distribution curve; Characterizes the cumulative porosity corresponding to the third pore size portion; Characterizing the third aperture portion The maximum slope of the spectrum and the cumulative porosity distribution curve.

[0088] In some embodiments, an asphalt mixture performance damage index is constructed using the combined rate of change and complexity of microstructural parameters, including:

[0089] The cumulative porosity and fractal dimension corresponding to the first pore size, the second pore size, and the third pore size are obtained respectively;

[0090] The structural performance index of each pore size is determined based on the cumulative porosity and fractal dimension, and the sum of the structural performance indices of the first, second, and third pore sizes is determined as the complexity of the mesoscopic structural parameters.

[0091] The complexity of the detailed structural parameters can be expressed as:

[0092]

[0093] In the formula: Characterize the complexity of the microstructure parameters of the asphalt mixture under test; These are the cumulative porosities corresponding to the first, second, and third pore diameter portions, respectively. These are the fractal dimensions of the porosity of the pore structures in the first, second, and third pore diameters, respectively.

[0094] In some embodiments, constructing an asphalt mixture performance damage index using the combined rate of change and complexity of microstructural parameters further includes:

[0095] The product of the overall rate of change and complexity of the microstructural parameters is determined as the damage index of the asphalt mixture to be tested.

[0096] The performance impairment index C of the mixture under test can be expressed as:

[0097] .

[0098] In an optional embodiment, the selected freeze-thaw cycles are 0, 10, and 20, respectively, to obtain... The cumulative porosity distribution curves were obtained from the spectrum and calculated the microstructural parameters of each pore, including the cumulative porosity of the peak pore size and the maximum slope of the cumulative pore size of the peak. The values ​​of the first, second, and third pore sizes for each microstructural parameter were statistically analyzed under 0, 10, and 20 freeze-thaw cycles. Then, the fractal dimension model of the nuclear magnetic resonance was plotted. The curves were used to obtain the fractal dimension of the porosity corresponding to the first, second, and third pore sizes. Then, for each control group, a performance damage index for warm-mix recycled asphalt mixtures was constructed based on the microstructural parameters and fractal dimension, yielding the comprehensive change rate of the microstructural parameters for each group of asphalt mixtures under test. and the complexity of detailed structural parameters ;according to and The performance damage index C of the warm-mix recycled fiber asphalt mixture for each group was calculated, and the effect of the low-temperature crack resistance of the asphalt mixture under test in each group was determined according to the magnitude of the performance damage index C.

[0099] In one alternative embodiment, a specific example is provided. The new asphalt is SBS-modified asphalt, and the polymer modifier SBS is thermoplastic styrene-butadiene rubber. 4% by mass of the polymer modifier SBS is incorporated into the base asphalt, and its basic technical performance indicators are shown in Table 1.

[0100] Table 1 Technical Specifications of SBS Modified Asphalt

[0101]

[0102] The waste asphalt pavement material (RAP) used in the experiment was obtained from the pavement material produced by milling during the maintenance and repair of Class I highways in Wuchuan County, Hohhot City, Inner Mongolia. The RAP content was 50%, and the relevant technical indicators are shown in Table 2.

[0103] Table 2 Technical Specifications of Old Asphalt

[0104]

[0105] The experiment used Styreneic Methyl Copolymers (SMC) produced by Beijing Xierma Company. Its main components include hydrocarbons and resin materials, and the dosage is 15% of the old asphalt. Its technical indicators are shown in Table 3.

[0106] Table 3 Technical Specifications of SMC Warm Mix Recycling Agent

[0107]

[0108] The new aggregate used in the experiment was taken from basalt in Zhuozishan County, Inner Mongolia Autonomous Region. The density test results of the basalt aggregate are shown in Table 4, and the gradation design is shown in Table 5.

[0109] Table 4. Results of aggregate density test

[0110]

[0111] Table 5 Gradation Composition Design

[0112]

[0113] The experiment used chopped basalt fibers and flocculent basalt fibers. The chopped basalt fibers were golden-brown needle-like flakes with a regular cylindrical shape and a relatively smooth surface, although some small granular deposits and slightly rough areas were present. The flocculent basalt fibers were grayish-white and cotton-like, with a randomly distributed microstructure and partially interlocked fibers forming a complex spatial network structure. The technical specifications of the two types of basalt fibers are shown in Table 6.

[0114] Table 6. Results of Basalt Fiber Performance Tests

[0115]

[0116] To improve the mechanical properties of warm-mix recycled asphalt mixtures, 0.4% short-cut basalt fiber and flocculent basalt fiber were incorporated, respectively. According to the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG E20-2011), the Marshall design method was used to determine the optimal asphalt-aggregate ratio for hot-mix asphalt mixtures and warm-mix recycled asphalt mixtures with different fiber contents, as shown in Table 7.

[0117] Table 7 Optimal Oil-Stone Ratio

[0118]

[0119] Nuclear magnetic resonance (NMR) technology was used to test warm-mix recycled asphalt mixtures (WRAM) subjected to freeze-thaw cycles, WRAM-C with 0.4% chopped basalt fiber, and WRAM-F with 0.4% flocculent basalt fiber. Results were obtained. Spectrum and cumulative porosity distribution curve, such as Figures 2 to 4 As shown, the three mixtures The spectral curves all exhibit a distinct three-peak distribution characteristic, according to The relaxation time range divides the pore size into: the first pore diameter ( <10ms), second aperture (10ms < <100ms) and the third aperture ( >100ms). The microstructural parameters of each pore were calculated, including the cumulative porosity of the peak pore size and the maximum slope of the cumulative peak pore size. The microstructural parameters of the blank group (warm-mix recycled asphalt mixture without basalt fiber), the chopped basalt fiber group (warm-mix recycled asphalt mixture with 0.4% chopped basalt fiber), and the flocculent basalt fiber group (warm-mix recycled asphalt mixture with 0.4% flocculent basalt fiber) are shown in Tables 8 to 10, respectively.

[0120] Table 8: Microstructural parameters of the blank group

[0121]

[0122] Table 9: Microstructural parameters of short-cut basalt fiber set

[0123]

[0124] Table 10: Microstructural parameters of the fibrous set in flocculent basalt

[0125]

[0126] After normalizing Tables 8-10 above, we obtain Table 11:

[0127] Table 11: Comprehensive variation rate of microstructural parameters of warm-mix recycled asphalt mixtures

[0128]

[0129] As can be seen from Tables 8 to 11, compared with the blank group of asphalt mixtures, the incorporation of short-cut basalt fibers and flocculent basalt fibers can delay the destruction of the microstructure of asphalt mixtures under freeze-thaw action, which is beneficial to improving the low-temperature crack resistance of asphalt mixtures.

[0130] Taking a warm-mix recycled asphalt mixture (WRAM-F-20) specimen with 0.4% flocculent basalt fiber incorporated after 20 freeze-thaw cycles as an example, the nuclear magnetic resonance fractal dimension model was plotted according to equation (8). and Curves, such as Figure 5As shown in the figure, the curve reveals a significant difference on both sides of 10. Therefore, linear regression analysis was performed on the two parts separately. The fractal dimensions less than 10 and greater than 10 are expressed as follows: and The calculation results are shown in Table 12. From the table, we can see that... and The correlation coefficient R of the fitted curve 2 All values ​​were above 0.8, indicating that the pore structure of the asphalt mixture exhibited good fractal characteristics. The fractal dimensions of the second and third pore diameters were also shown. Fractal dimension greater than the first aperture This indicates that the second and third apertures are more complex than the first aperture.

[0131] Table 12 Fractal dimensions of three asphalt mixtures under different freeze-thaw cycles

[0132]

[0133] The larger the fractal dimension, the more complex and inhomogeneous the pore structure, and the better the material properties. This is in line with the overall variation rate of the microstructural parameters of the mixture. The trends are consistent. After applying reverse normalization (1-F) to the fractal dimension, we obtain Table 13:

[0134] Table 13 Complexity of Microstructural Parameters of Warm-Mix Recycled Asphalt Mixtures

[0135]

[0136] As can be seen from Tables 12 and 13, and The correlation coefficient R of the fitted curve 2 All values ​​were above 0.8, indicating that the pore structure of the asphalt mixture exhibited good fractal characteristics. The fractal dimensions of the second and third pore diameters were also shown. Fractal dimension greater than the first aperture This indicates that the complexity of the second and third pore sizes is higher than that of the first pore size. With increasing freeze-thaw cycles, the complexity of the three asphalt mixtures... and All showed a decreasing trend, indicating that after freeze-thaw cycles, the complexity of the mixture's pore structure decreased and its uniformity increased. Under the same freeze-thaw conditions, the fractal dimension of the incorporated fibers... and The results were all higher than the control group, indicating that the incorporation of fibers increases the complexity of the pore structure of asphalt mixtures. This is because the incorporation of fibers fills pores, especially large pores, and forms a network structure, increasing the complexity of the pore structure. This complex pore structure restricts water flow, especially during freeze-thaw cycles, slowing down the rate of water penetration and reducing the damage caused by freeze-thaw cycles to asphalt mixtures. Due to their multidimensional connectivity, flocculent fibers can construct a denser and more interwoven structural system in the mixture. This system not only fills large pores but also provides some separation and constraint to micropores, thus forming a multi-level pore system and significantly increasing the complexity of the pore structure. In contrast, chopped fibers are mainly linearly distributed, with a relatively simple network structure, and have a weaker impact on pore complexity.

[0137] Both types of basalt fibers inhibited internal structural damage in warm-mix recycled asphalt mixtures. The internal structural damage index was used as the basis for comparison. A higher index indicates a better improvement in the low-temperature crack resistance of the warm-mix recycled asphalt mixture, while a lower index indicates a worse improvement. The pore damage evaluation indices for the two types of basalt fiber-based warm-mix recycled asphalt mixtures are shown in Table 14.

[0138] Table 14 Performance Damage Index of Two Basalt Fiber Warm Mix Recycled Asphalt Mixtures

[0139]

[0140] fracture energy density (F E This method can comprehensively and accurately assess the low-temperature crack resistance of asphalt mixtures, taking into account both material deformation and load-bearing capacity. Under low-temperature conditions, the failure process of asphalt mixtures is essentially an energy dissipation process. E A larger value indicates that more energy is consumed during material failure, and better crack resistance. Calculate F. E The formula is shown in Equation 12:

[0141] (12)

[0142] In the formula: Characterizing the stress at the bottom of the beam, Characterizing the bending strain at the bottom of the beam, Characterizing the strain value corresponding to the maximum stress, Characterizing the strain integral, The stress-strain curve characterizes the asphalt mixture. Based on Equation 12, the fracture energy density (F0) of warm-mix recycled asphalt mixtures under different freeze-thaw cycles for the blank group, the short-cut basalt fiber group, and the flocculent basalt fiber group can be calculated. E ),like Figure 6 As shown.

[0143] Under freeze-thaw cycle conditions, the microstructural property damage index C and macroscopic fracture energy density F of three asphalt mixtures were compared. E The values ​​exhibit a strong negative correlation and a deterioration pattern. Constructing C and F... E A scatter plot can be used to analyze the relationship between two indicators, such as... Figure 7 As shown in the figure. From the figure, we can see that C and F... E The value of R 2 The correlation coefficient is 0.869, indicating a high correlation. The microstructural performance damage index C evaluation method can effectively reflect the low-temperature crack resistance of asphalt mixtures and has high reliability.

[0144] In some embodiments, please refer to Figure 8 , Figure 8 This is a schematic diagram of a low-temperature crack resistance evaluation system for asphalt mixture pavement provided in an embodiment of the present invention. The present invention provides an asphalt mixture pavement low-temperature crack resistance evaluation system 800, comprising: a parameter acquisition module 810, a function mapping module 820, and an index determination module 830; wherein,

[0145] The parameter acquisition module 810 is configured to acquire the microstructure parameters of the asphalt mixture to be tested using nuclear magnetic resonance; the asphalt mixture to be tested is an asphalt mixture mixed with basalt fiber; the microstructure parameters include the cumulative porosity of the peak pore size and the maximum slope of the cumulative peak pore size.

[0146] The function mapping module 820 is configured to obtain the first functional relationship between the pore size distribution density function and the cumulative pore volume fraction based on fractal theory, convert and derive the first functional relationship to determine the mapping relationship between the cumulative pore volume fraction and the transverse relaxation time, and determine the fractal dimension of the porosity of the pore structure corresponding to different pore sizes based on the mapping relationship.

[0147] The index determination module 830 is configured to construct the performance damage index of asphalt mixture using the comprehensive change rate and complexity of the microstructure parameters; the damage index is negatively correlated with the low-temperature crack resistance of the asphalt mixture under test; the comprehensive change rate is related to the cumulative porosity of the peak aperture and the maximum slope of the cumulative peak aperture, and the complexity is related to the cumulative porosity of the peak aperture and the fractal dimension.

[0148] In some embodiments, the function mapping module 820 is specifically configured as follows:

[0149] A second functional relationship is created between the pore structure distribution density function, the maximum pore diameter, the proportionality constant, and the fractal dimension based on fractal theory.

[0150] The second functional relationship is converted and derived to determine the aperture distribution density function; the aperture distribution density function is related to the fractal dimension.

[0151] In some embodiments, the function mapping module 820 is specifically configured as follows:

[0152] The first functional relationship between the established pore size distribution density function and the cumulative pore volume fraction function is converted and derived. Combined with the measurement data of transverse relaxation time in nuclear magnetic resonance, the mapping relationship between the cumulative pore volume fraction and the transverse relaxation time is determined.

[0153] In some embodiments, the function mapping module 820 is specifically configured as follows:

[0154] A coordinate system is created by taking the logarithm of the cumulative pore volume fraction as the vertical axis and the logarithm of the transverse relaxation time as the horizontal axis. The mapping relationship between the cumulative pore volume fraction and the transverse relaxation time is obtained, and the slope of the curve corresponding to the mapping relationship is determined as the fractal dimension of the corresponding pore size.

[0155] In some embodiments, the index determination module 830 is specifically configured as follows:

[0156] The first pore size, second pore size, and third pore size are determined based on the curve peaks in the transverse relaxation time spectrum and cumulative porosity distribution curve of the asphalt mixture to be tested; the first pore size is smaller than the second pore size, and the second pore size is smaller than the third pore size.

[0157] The maximum slope of the transverse relaxation time spectrum and the cumulative porosity distribution curve corresponding to the first pore size, the second pore size and the third pore size, respectively, as well as the cumulative porosity corresponding to the first pore size, the second pore size and the third pore size are obtained respectively.

[0158] The rate of change of microstructural parameters is determined based on the maximum slope and cumulative porosity, and the sum of the rates of change of the first pore diameter, the second pore diameter, and the third pore diameter is determined as the comprehensive rate of change.

[0159] In some embodiments, the index determination module 830 is specifically configured as follows:

[0160] The cumulative porosity and fractal dimension corresponding to the first pore size, the second pore size, and the third pore size are obtained respectively;

[0161] The structural performance index of each pore size is determined based on the cumulative porosity and fractal dimension, and the sum of the structural performance indices of the first, second, and third pore sizes is determined as the complexity of the mesoscopic structural parameters.

[0162] In some embodiments, the index determination module 830 is further configured as follows:

[0163] The product of the overall rate of change and complexity of the microstructural parameters is determined as the damage index of the asphalt mixture to be tested.

[0164] It should be noted that the low-temperature crack resistance evaluation system for asphalt mixture pavement provided in this application embodiment and the low-temperature crack resistance evaluation method for asphalt mixture pavement provided in this application embodiment are based on the same application concept. Therefore, the specific implementation of this embodiment can refer to the implementation of the aforementioned low-temperature crack resistance evaluation method for asphalt mixture pavement, and the repeated parts will not be described again.

[0165] In some embodiments, please refer to Figure 9 , Figure 9 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this application. The electronic device 900 provided in this embodiment includes a processor 910 and a memory 920; the memory 920 stores a computer program, wherein the computer program, when executed by the processor, implements the aforementioned method for evaluating the low-temperature crack resistance performance of asphalt mixture pavement.

[0166] Specifically, processor 910 may include, for example, a general-purpose microprocessor, an instruction set processor and / or an associated chipset and / or a special-purpose microprocessor (e.g., an application-specific integrated circuit (ASIC)), etc. Processor 910 may also include onboard memory for caching purposes. Processor 910 may be a single processing unit or multiple processing units for performing different actions of the method flow according to embodiments of this application.

[0167] The memory 920 can be any medium capable of containing, storing, transmitting, propagating, or transmitting instructions. For example, the memory 920 can be, but is not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, device, apparatus, or propagation medium. Specific examples of the memory 920 include: magnetic storage devices such as magnetic tape or hard disk drives (HDDs); optical storage devices such as optical discs (CD-ROMs); and also random access memory (RAM) or flash memory; and / or wired / wireless communication links.

[0168] This application also provides a computer-readable medium storing a computer program that, when executed by a processor, implements the aforementioned method for evaluating the low-temperature crack resistance of asphalt mixture pavement. This computer-readable medium may be included in the device / apparatus / system described in the above embodiments; or it may exist independently and not assembled into that device / apparatus / system. The aforementioned computer-readable medium carries one or more programs, which, when executed, implement the method according to the embodiments of this application.

[0169] According to embodiments of this application, a computer-readable medium may be a computer-readable signal medium or a computer-readable storage medium, or any combination thereof. A computer-readable storage medium may be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples of a computer-readable storage medium may include, but are not limited to: an electrical connection having one or more wires, a portable computer disk, a hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage device, magnetic storage device, or any suitable combination thereof. In this application, a computer-readable storage medium may be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, apparatus, or device. In this application, a computer-readable signal medium may include a data signal propagated in baseband or as part of a carrier wave, carrying computer-readable program code. Such propagated data signals may take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination thereof. Computer-readable signal media can also be any computer-readable medium other than computer-readable storage media, which can send, propagate, or transmit a program for use by or in connection with an instruction execution system, apparatus, or device. The program code contained on the computer-readable medium can be transmitted using any suitable medium, including but not limited to: wireless, wired, optical fiber, radio frequency signals, etc., or any suitable combination thereof.

[0170] Those skilled in the art will understand that the features described in the various embodiments and / or claims of this application can be combined and / or combined in various ways, even if such combinations or combinations are not explicitly described in this application. In particular, the features described in the various embodiments and / or claims of this application can be combined and / or combined in various ways without departing from the spirit and teachings of this application. All such combinations and / or combinations fall within the scope of this application. Therefore, the scope of this application should not be limited to the above embodiments, but should be defined not only by the appended claims, but also by their equivalents. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this invention should be included within the protection scope of this invention.

Claims

1. A method for evaluating the low-temperature crack resistance of asphalt mixture pavement, characterized in that, include: The microstructural parameters of the asphalt mixture to be tested were obtained using nuclear magnetic resonance (NMR); the asphalt mixture to be tested was an asphalt mixture containing basalt fibers. The microstructural parameters include the cumulative porosity of the peak aperture and the maximum slope of the cumulative peak aperture. Based on fractal theory, the first functional relationship between pore size distribution density function and cumulative pore volume fraction is obtained. The first functional relationship is converted and derived to determine the mapping relationship between cumulative pore volume fraction and transverse relaxation time. Based on the mapping relationship, the fractal dimension of porosity corresponding to different pore sizes is determined. The performance damage index of asphalt mixture is constructed using the comprehensive change rate and complexity of the microstructure parameters. The damage index is negatively correlated with the low-temperature crack resistance of the asphalt mixture under test; the comprehensive change rate is related to the cumulative porosity of the peak aperture and the maximum slope of the cumulative peak aperture; and the complexity is related to the cumulative porosity of the peak aperture and the fractal dimension.

2. The method for evaluating the low-temperature crack resistance of asphalt mixture pavement as described in claim 1, characterized in that, Before obtaining the first functional relationship between the pore size distribution density function and the cumulative pore volume fraction based on fractal theory, the following is also included: A second functional relationship is established between the pore structure distribution density function, the maximum pore diameter, the proportionality constant, and the fractal dimension based on fractal theory. The second functional relationship is converted and derived to determine the aperture distribution density function; the aperture distribution density function is related to the fractal dimension.

3. The method for evaluating the low-temperature crack resistance of asphalt mixture pavement as described in claim 1, characterized in that, The step of converting and deriving the mapping relationship between the cumulative pore volume fraction and the transverse relaxation time based on the first functional relationship includes: The first functional relationship between the established pore size distribution density function and the cumulative pore volume fraction function is converted and derived. Combined with the measurement data of transverse relaxation time in nuclear magnetic resonance, the mapping relationship between the cumulative pore volume fraction and the transverse relaxation time is determined.

4. The method for evaluating the low-temperature crack resistance of asphalt mixture pavement as described in claim 3, characterized in that, The determination of the fractal dimension of the porosity of pore structures corresponding to different pore sizes based on the mapping relationship includes: A coordinate system is created by taking the logarithm of the cumulative pore volume fraction as the vertical axis and the logarithm of the transverse relaxation time as the horizontal axis, to obtain the mapping relationship between the cumulative pore volume fraction and the transverse relaxation time, and the slope of the curve corresponding to the mapping relationship is determined as the fractal dimension of the corresponding pore size.

5. The method for evaluating the low-temperature crack resistance of asphalt mixture pavement as described in claim 1, characterized in that, The method of constructing an asphalt mixture performance damage index using the comprehensive change rate and complexity of the microstructure parameters includes: The first pore size, the second pore size, and the third pore size are determined based on the curve peaks in the transverse relaxation time spectrum and the cumulative porosity distribution curve of the asphalt mixture to be tested; the first pore size is smaller than the second pore size, and the second pore size is smaller than the third pore size. The maximum slope of the transverse relaxation time spectrum and the cumulative porosity distribution curve corresponding to the first pore size, the second pore size and the third pore size, respectively, as well as the cumulative porosity corresponding to the first pore size, the second pore size and the third pore size are obtained respectively; The rate of change of the microstructure parameters is determined based on the maximum slope and the cumulative porosity, and the sum of the rates of change of the first pore diameter, the second pore diameter, and the third pore diameter is determined as the comprehensive rate of change.

6. The method for evaluating the low-temperature crack resistance of asphalt mixture pavement as described in claim 5, characterized in that, The method of constructing an asphalt mixture performance damage index using the comprehensive change rate and complexity of the microstructure parameters includes: The cumulative porosity and fractal dimension corresponding to the first pore size, the second pore size, and the third pore size are obtained respectively; The structural performance index of each pore size is determined based on the cumulative porosity and the fractal dimension, and the sum of the structural performance indices of the first pore size, the second pore size, and the third pore size is determined as the complexity of the microstructure parameter.

7. The method for evaluating the low-temperature crack resistance of asphalt mixture pavement as described in claim 6, characterized in that, The method of constructing the asphalt mixture performance damage index using the comprehensive change rate and complexity of the microstructure parameters also includes: The product of the comprehensive rate of change of the microstructural parameters and the complexity is determined as the damage index of the asphalt mixture to be tested.

8. A system for evaluating the low-temperature crack resistance of asphalt mixture pavement, characterized in that, include: The module consists of a parameter acquisition module, a function mapping module, and an exponent determination module; among them, The parameter acquisition module is configured to acquire the microstructure parameters of the asphalt mixture to be tested using nuclear magnetic resonance; the asphalt mixture to be tested is an asphalt mixture mixed with basalt fibers; the microstructure parameters include the cumulative porosity of the peak pore size and the maximum slope of the cumulative peak pore size. The function mapping module is configured to obtain a first functional relationship between the pore size distribution density function and the cumulative pore volume fraction based on fractal theory, convert and derive the first functional relationship to determine the mapping relationship between the cumulative pore volume fraction and the transverse relaxation time, and determine the fractal dimension of the porosity of the pore structure corresponding to different pore sizes based on the mapping relationship. The index determination module is configured to construct an asphalt mixture performance damage index using the comprehensive change rate and complexity of the microstructure parameters; the damage index is negatively correlated with the low-temperature crack resistance of the asphalt mixture under test; the comprehensive change rate is related to the cumulative porosity of the peak aperture and the maximum slope of the cumulative peak aperture, and the complexity is related to the cumulative porosity of the peak aperture and the fractal dimension.

9. An electronic device comprising a processor and a memory; said memory having a storage for a computer program, wherein, When the computer program is executed by the processor, it implements the method for evaluating the low-temperature crack resistance of asphalt mixture pavement as described in any one of claims 1 to 7.

10. A computer storage medium, characterized in that, It stores a computer program, wherein when the computer program is executed by a processor, it implements the method for evaluating the low-temperature crack resistance of asphalt mixture pavement as described in any one of claims 1 to 7.

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