Asphalt oxidation functional group and aggregate adhesion mechanism analysis method and system based on molecular dynamics

Abstract

The invention belongs to but not limited to the technical field of asphalt-aggregate adhesion performance analysis, and discloses an asphalt oxidation functional group and aggregate adhesion action mechanism analysis method and system based on molecular dynamics, and the method comprises the following steps: constructing a multivariable oxidation functional group asphalt molecular model; constructing a refined silicon dioxide aggregate model; building a layered asphalt-aggregate interface system; carrying out geometric optimization, annealing treatment and dynamic simulation on the basis of Materials Studio software; and microscopic analysis of the adhesion performance is realized through interface energy calculation. The method has the remarkable advantages of being high in stability, high in universality, low in cost and the like, overcomes the defects of existing research on micromechanism analysis, and provides a new technical path for correlation research of asphalt aging and adhesion performance degradation.

Description

Technical Field

[0001] This invention belongs to, but is not limited to, the field of asphalt-aggregate adhesion performance analysis technology, and particularly relates to a method and system for analyzing the adhesion mechanism between asphalt oxidation functional groups and aggregates based on molecular dynamics. Background Technology

[0002] As the most widely used core material for road paving globally, asphalt mixtures directly determine the service life, driving safety, and maintenance costs of roads. Among the various performance indicators of asphalt mixtures, the interfacial adhesion behavior between asphalt and aggregates is crucial: good adhesion can effectively resist mechanical damage caused by moisture erosion, temperature cycling, and vehicle loads, significantly improving pavement durability, anti-stripping ability, and anti-cracking performance; while deterioration of adhesion performance will directly lead to early-stage defects such as pavement stripping, loosening, and potholes, seriously affecting road traffic quality and increasing maintenance costs.

[0003] However, during long-term service, asphalt mixtures are inevitably affected by the combined effects of environmental factors such as heat, oxygen, and sunlight, as well as loads, leading to irreversible aging. The core chemical essence of asphalt aging is the oxidative cracking and recombination of asphalt molecules, generating characteristic oxidized functional groups such as carbonyl (C=O) and sulfoxide (S=O). The accumulation of these oxidation products significantly alters the polarity characteristics, surface energy distribution, and intermolecular force patterns of asphalt, thereby regulating the interfacial adhesion state between asphalt and aggregates, ultimately inducing interfacial failure and becoming a key bottleneck restricting the improvement of road durability. Therefore, revealing the influence mechanism of oxidized functional groups on asphalt-aggregate adhesion properties has important engineering value and scientific significance for optimizing asphalt mixture design and delaying pavement aging failure.

[0004] With the development of materials science, computational simulation, and digital technology, the industry's research on adhesion properties has evolved from macroscopic performance characterization to microscopic mechanism analysis. There is an urgent need to break through the traditional experience-based R&D model and establish a mechanism-based precision design system. As the core foundation, the technological breakthrough of adhesion properties plays a key supporting role in the upgrading of the entire asphalt pavement materials industry.

[0005] Currently, the academic and engineering communities have developed a relatively mature theoretical and methodological system for the study of asphalt-aggregate adhesion properties. At the theoretical level, five core theories have been proposed to support the evaluation of adhesion performance: mechanical theory (characterizing adhesion effect based on interfacial mechanical strength), chemical reaction theory (emphasizing the chemical bonding effect between asphalt and aggregate), surface energy theory (calculating adhesion work through surface energy parameters), molecular orientation theory (focusing on the directional arrangement of asphalt molecules on the aggregate surface), and electrostatic theory (explaining the influence of interfacial electrostatic effects on adhesion).

[0006] Based on the above theories, various macroscopic detection methods have been developed, including traditional boiling / immersion methods (for direct observation of adhesion), contact angle methods (for calculating surface energy parameters), photoelectric colorimetry (for quantifying the degree of peeling), and modern instrumental analysis methods such as atomic force microscopy (AFM, for characterizing microscopic surface morphology and adhesion force), dynamic mechanical analyzer (DMA, for testing interfacial mechanical response), and dynamic shear rheometer (DSR, for correlating viscoelastic properties with adhesion). These methods have played an important role in engineering practice, but they generally have limitations: macroscopic experimental results are easily affected by environmental conditions such as temperature, humidity, and aggregate gradation; traditional methods such as boiling and immersion methods can only characterize the adhesion effect through visual inspection or macroscopic strength rating; and macroscopic experiments have poor repeatability and cannot analyze the mechanism of action of microscopic factors such as oxidized functional groups on adhesion behavior at the molecular level, making it difficult to reveal the essential reasons for the deterioration of adhesion performance.

[0007] In recent years, with the rapid development of computer simulation technology, molecular dynamics (MD) simulation has become an important means to overcome the limitations of macroscopic research. Unlike traditional experimental methods, MD simulation can directly reveal the microstructure, molecular motion laws, and interfacial interaction mechanisms of materials at the molecular scale, providing a brand-new perspective for the study of asphalt-aggregate adhesion properties.

[0008] Currently, MD simulation has made some progress in its application in asphalt systems: some studies have confirmed that the polar interaction between asphalt and aggregates is the core influencing factor of adhesion performance by constructing aggregate cell systems such as SiO2 and CaO, and revealed the differentiated effects of aging on the adhesion of different types of aggregates (silicate / calcium-based); other studies have focused on the regulatory law of asphalt chemical composition (such as the four components: aromatics, asphaltenes, resins, and saturates) on adhesion behavior, or analyzed the erosion mechanism of water on interfacial adhesion and the sensitivity of aggregates to water, and also clarified the influence of the coupling effect of aggregate components (influence degree: CaO>MgO>SiO2>Al2O3>Fe2O3) and the four components of asphalt on adhesion work.

[0009] Nevertheless, existing research still has key gaps: current MD simulation studies mostly focus on macroscopic factors such as the overall chemical composition of asphalt, aggregate type, and moisture content, while systematic research is lacking on the impact of oxidative functional groups (especially carbonyl and sulfoxide groups) generated during asphalt aging on adhesion properties. Existing research has not clarified how different types and concentrations of oxidative functional groups regulate the interaction energy (including van der Waals energy and electrostatic energy) of the asphalt-aggregate interface, nor has it revealed the synergistic mechanism of the two core oxidative functional groups (carbonyl and sulfoxide groups). This makes it impossible to explain the essential reasons for the degradation of adhesion properties caused by asphalt aging at the microscopic level, and it is difficult to provide accurate theoretical support for the design of asphalt anti-aging modification.

[0010] Based on the above analysis, the urgent technical problems that need to be solved in the existing technology are:

[0011] (1) Traditional macroscopic experiments (such as boiling water method, contact angle method, dynamic shear rheometer method) are significantly affected by environmental conditions such as temperature, humidity, and aggregate gradation, resulting in poor experimental repeatability; and can only indirectly characterize adhesion performance through macroscopic phenomena (such as peeling degree and viscoelastic parameters), and cannot analyze the intrinsic relationship between oxidized functional groups and interface interaction at the molecular level, making it difficult to reveal the microscopic nature of adhesion performance degradation.

[0012] (2) Existing MD simulation studies mostly focus on the overall composition of asphalt (such as four components), aggregate type (such as CaO / SiO2) or the influence of moisture, without conducting systematic research on “oxidized functional groups”: neither the individual role of carbonyl (C=O) and sulfoxide (S=O) is clarified, nor the synergistic effect of their coexistence is analyzed, nor the influence of concentration on adhesion performance is quantified, resulting in the inability to establish the correlation between “oxidized functional groups-interfacial adhesion”.

[0013] (3) Some MD studies have simplified the aggregate model (such as not considering the crystal cutting direction, not adding a vacuum layer or passivation treatment), which leads to the aggregate surface structure not matching the actual situation, thus affecting the simulation reality of the asphalt-aggregate interface and causing the analysis results to deviate from the actual engineering scenario.

[0014] (4) Some MD studies only verify the rationality of the model through a single parameter (such as density) and lack multi-dimensional verification, which may lead to the problem that the model “conforms to density but deviates from the real asphalt”, thus affecting the credibility of subsequent adhesion performance analysis results. Summary of the Invention

[0015] To address the problems existing in the prior art, this invention provides a method and system for analyzing the mechanism of adhesion between asphalt oxidation functional groups and aggregates based on molecular dynamics.

[0016] This invention is achieved by providing a molecular dynamics-based method for analyzing the adhesion mechanism between asphalt oxidation functional groups and aggregates. The method specifically includes:

[0017] S1: Constructing a multivariable molecular model of pitch with oxidized functional groups;

[0018] S2: Construct a refined silica aggregate model;

[0019] S3: Construct a layered asphalt-aggregate interface system;

[0020] S4: Geometry optimization, annealing, and dynamic simulation based on Materials Studio software;

[0021] S5: Verification of the asphalt model;

[0022] S6: Calculate the interface energy and perform microscopic analysis of adhesion performance.

[0023] Furthermore, step S1 includes:

[0024] (1) Model selection

[0025] By using Materials Studio software to access the molecular structure library of the Derek model, the molecular units of the four components were identified, such as: saturated components: Squalane, Hopane; aromatic components: PHPN, DOCHN; resins: Pyridinohopane, Thio-isorenieratane, Trimethylbenzene-oxane, Quinolinohopane, Benzobisbenzothiophene; asphaltenes: Phenol, Pyrrole, Thiophene, etc., totaling 12 molecules, corresponding to the "asphalt twelve-molecule model";

[0026] (2) Design and addition of oxidizing functional groups

[0027] Only two types of oxidative functional groups, carbonyl (C=O) and sulfoxide (S=O), were added. Three types were set: "only carbonyl (C=O) added", "only sulfoxide (S=O) added", and "both carbonyl (C=O) and sulfoxide (S=O) added", with two concentration gradients of 50% (L1) and 100% (L2).

[0028] (3) Determination of the number of asphalt molecules

[0029] Based on the mass fractions of the four components of 70# base asphalt in the unaged and aged processes determined by the four-component determination method of asphalt (NB / SH / T 0509-2010), the number of molecules in different aging states is calculated by formula (1).

[0030] (1)

[0031] in, denoted as mass fraction; N is the number of molecules; m is the relative molecular mass; M is the total molecular mass of asphalt molecules.

[0032] (4) Model combination: Construction of 15 asphalt models

[0033] By combining "3 molecular number models (A0 / A1 / A2) + 3 functional group types (-C / -S / -ALL) + 2 concentrations (L1 / L2) + 1 unaged control (L0)", 15 asphalt models were generated;

[0034] In the Amorphous Cell module of Materials Studio, select the Construction task, add the corresponding molecular units and number of molecules in the above combination, set the initial cell density to 0.8 g / cm³, set the force field to COMPASSIII, and build the asphalt model.

[0035] Furthermore, step S2 includes:

[0036] (1) Crystal selection and cutting

[0037] SiO2 crystal was selected and cut along the (0 0 1) crystal plane.

[0038] (2) Surface passivation treatment

[0039] Adding hydrogen atoms (H) to the surface of the cut SiO2 sheet passivates the unsaturated silicon-oxygen bonds (Si-O). - );

[0040] (3) Setting of vacuum layer and periodic boundary

[0041] A 10 Å thick vacuum layer was inserted above a SiO2 sheet, and three-dimensional periodic boundary conditions were set.

[0042] Furthermore, the steps for S3 are as follows:

[0043] (1) Layered structure design

[0044] A four-layer structure consisting of "SiO2 aggregate layer → 10Å vacuum layer → bitumen layer → 50Å vacuum layer" is used, and the layers are stacked in the following order using the Build Layers tool in MaterialsStudio:

[0045] First layer: Passivated SiO2 aggregate layer;

[0046] Second layer: 10Å vacuum layer;

[0047] The third layer: the constructed asphalt model, with a contact area of ​​48×40Å with SiO2;

[0048] Fourth layer: 50Å vacuum layer.

[0049] (2) Aggregate fixing

[0050] The atomic coordinates of the lower 2 / 3 region of the SiO2 aggregate layer are fixed; the x, y, and z axis displacements of all Si and O atoms in the lower 2 / 3 region of the SiO2 layer are locked using the Constraints tool in Materials Studio, while the atomic degrees of freedom are retained in the upper 1 / 3 region.

[0051] Furthermore, S4 includes:

[0052] (1) Geometric optimization

[0053] In the Forcite module of Materials Studio, select the Geometry Optimization task, input the above parameters, and perform geometric optimization on 15 asphalt models and their corresponding asphalt-aggregate interface systems until the convergence criterion is met.

[0054] (2) Annealing treatment

[0055] In the Forcite module, select the Anneal task, set the parameters, and perform NVT simulation on the geometrically optimized interface system. After each loop, output the system energy data and select the structure with the lowest energy to proceed to the next step.

[0056] In the Forcite module, select the Anneal task, set the parameters, and perform NPT simulation on the geometrically optimized interface system until the system density region is stable and the energy curve is flat.

[0057] (3) Dynamic simulation

[0058] In the Forcite module, select the Molecular Dynamics task, set the NVT ensemble and parameters, and simulate the annealed system until the density and energy curves tend to stabilize.

[0059] Based on the stable structure simulated by NVT, the simulation was switched to the NPT ensemble, and the parameters were set to continue the simulation. The final output data included the total potential energy, bitumen potential energy, SiO2 potential energy, and interaction energy (van der Waals energy + electrostatic energy) of the interface system.

[0060] Furthermore, step S5 includes:

[0061] (1) Density verification

[0062] Extract the density-time curve of the NPT simulation using the Analysis tool in Materials Studio, calculate the average value of the stable segment, and verify whether it meets the judgment criteria.

[0063] (2) Verification of solubility parameters

[0064] Using the Forcite Calculation tool in Materials Studio, select the Cohesive Energy Density task for calculation, or extract the van der Waals force and Coulomb electrostatic force data from NPT simulation, substitute them into the formula to calculate the solubility parameters, and verify whether they meet the standards.

[0065] (3) Verification of glass transition temperature (Tg)

[0066] The cell volume and mass at different temperatures are extracted using the Analysis tool, the specific volume (specific volume = volume / mass) is calculated, the inflection point is found by fitting the curve, and the compliance with the standard is verified.

[0067] Furthermore, the S6 computing interface can perform microscopic analysis of adhesion properties, including the following steps:

[0068] In the Forcite module, select the Forcite Calculation tool, choose the Energy task to perform energy calculations, and obtain various energy calculation results for the model;

[0069] Interfacial interaction energy calculation: By calculating the energy of the asphalt-aggregate system, the energy of the asphalt portion, and the energy of the aggregate portion, and combining this with formula (3), the interfacial interaction energy is calculated.

[0070] (3)

[0071] in, It is the interaction energy. This represents the total potential energy of the asphalt-aggregate model. Let be the potential energy of the asphalt model. The potential energy of the aggregate model;

[0072] The formulas for calculating van der Waals energy and electrostatic energy are the same, and the formula is: ;

[0073] in, It is represented as van der Waals energy (electrostatic energy). The total van der Waals energy (total electrostatic energy) of the asphalt-aggregate model. For the van der Waals energy (electrostatic energy) of the asphalt model. Van der Waals energy (electrostatic energy) for aggregate model.

[0074] Another objective of this invention is to provide a molecular dynamics-based system for analyzing the mechanism of asphalt oxidation functional groups and aggregate adhesion, the system specifically comprising:

[0075] The asphalt molecular model building module is used to construct asphalt molecular models containing different concentrations and types of oxidized functional groups.

[0076] The silica aggregate model building module is used to build a refined silica aggregate model.

[0077] The asphalt-aggregate interface system construction module is used to construct a layered asphalt-aggregate interface system.

[0078] The analysis module is used to systematically analyze the influence of functional group type and concentration on interfacial interaction energy (van der Waals energy, electrostatic energy).

[0079] Another object of the present invention is to provide a computer device, the computer device including a memory and a processor, the memory storing a computer program, and when the computer program is executed by the processor, causing the processor to perform the steps of the method for analyzing the adhesion mechanism between asphalt oxidation functional groups and aggregates based on molecular dynamics.

[0080] Another object of the present invention is to provide a computer-readable storage medium storing a computer program, which, when executed by a processor, causes the processor to perform the steps of the method for analyzing the mechanism of adhesion between asphalt oxidation functional groups and aggregates based on molecular dynamics.

[0081] Based on the above technical solutions and the technical problems solved, the advantages and positive effects of the technical solution to be protected by this invention are as follows:

[0082] (1) Precise analysis of microscopic mechanism: Through quantitative data of interface energy (interaction energy, van der Waals energy, electrostatic energy), the microscopic action path of "carbonyl group enhances van der Waals energy and sulfoxide group weakens van der Waals energy" was clarified for the first time, which solved the defect of existing macroscopic experiments "cannot analyze microscopic mechanism";

[0083] (2) Precise variable control: Through the design of "multi-type + multi-concentration" implementation examples, the full-dimensional quantification of the influence of oxidative functional groups was achieved, filling the gap in the existing MD simulation that "the influence of functional groups has not been systematically studied";

[0084] (3) Strong applicability: The examples cover unaged and aged asphalt systems, and different functional group types and concentrations, proving that the technical solution can be applied to asphalt systems under different service conditions, providing a wide range of references for engineering practice;

[0085] (4) Low cost and high efficiency: Compared with traditional macroscopic experiments (which require the preparation of specimens, control of environmental conditions, and a cycle of >7 days), this scheme significantly reduces research and time costs through computer simulation (simulation cycle of a single embodiment is <24 hours), and the cost of data repeatability is far lower than that of macroscopic experiments.

[0086] As important supporting evidence of the inventiveness of this invention, it is also reflected in the following three aspects: First, this invention has significant engineering transformation benefits and industrial creation value. By establishing an asphalt-aggregate interface model containing different oxidized functional groups, the trend of adhesion performance changes can be accurately determined at the microscale, providing a quantitative basis for road aging diagnosis and maintenance strategy formulation; at the same time, it provides asphalt production enterprises with a path to optimize material formulations at the molecular structure level, promoting the development of anti-aging and strong adhesion modified asphalt products; in addition, the molecular dynamics method proposed in this invention can replace some macroscopic experiments, significantly reducing the test cycle and environmental interference, forming a scalable engineering capability for road design and construction technical consulting.

[0087] Secondly, this invention fills a gap in domestic and international research on the correlation between the microscopic action mechanism of oxidative functional groups and adhesion properties. Existing technologies mostly remain at the macroscopic experimental scale, making it difficult to reveal the adsorption mechanism of aging functional groups. This invention, for the first time, constructs systems containing carbonyl and sulfoxide groups of different types and concentrations, clarifying the law of carbonyl groups enhancing adhesion, sulfoxide groups weakening adhesion, and the law of interfacial energy evolution with proportion under coexistence conditions.

[0088] Furthermore, this invention overcomes a long-standing technical challenge: the inability to distinguish the different contributions of oxidized functional groups to interfacial interactions. By simulating and quantifying the changes in interfacial energy and van der Waals interactions under 50% / 100% concentration gradients, it reveals that sulfoxide groups are the dominant factor in the decrease in adhesion in coexisting systems, achieving for the first time a quantitative conclusion that is explainable and verifiable at the microscopic level. Attached Figure Description

[0089] Figure 1 This is a flowchart of the method for analyzing the adhesion mechanism between asphalt oxidation functional groups and aggregates based on molecular dynamics, provided in an embodiment of the present invention.

[0090] Figure 2 This is a flowchart illustrating the specific process of analyzing the mechanism of adhesion between asphalt oxidation functional groups and aggregates based on molecular dynamics, as provided in this embodiment of the invention.

[0091] Figure 3 The embodiments of this invention provide schematic diagrams of the construction of asphalt molecules with different concentrations and different oxidative functional groups;

[0092] Figure 4 This is a twelve-molecule model of aged asphalt with an oxidized functional group concentration of 50% provided in the embodiments of the present invention;

[0093] Figure 5 This is a twelve-molecule model of aged asphalt with an oxidized functional group concentration of 100% provided in the embodiments of the present invention;

[0094] Figure 6 This is a partial asphalt molecular model provided in the embodiments of the present invention;

[0095] Figure 7 This is the SiO2 model provided in the embodiments of the present invention;

[0096] Figure 8 This is the asphalt (A2-L2-ALL)-aggregate model provided in the embodiments of the present invention;

[0097] Figure 9 This is a flowchart of the functional group addition process for the asphalt aging molecular model provided in this embodiment of the invention;

[0098] Figure 10 This is a module diagram of the system for analyzing the mechanism of asphalt oxidation functional groups and aggregate adhesion based on molecular dynamics, provided in an embodiment of the present invention.

[0099] Figure 11 This is a graph showing the effect of different types and concentrations of oxidized functional groups on asphalt-aggregate under the A1 model provided in this embodiment of the invention;

[0100] Figure 12 This is a graph showing the effect of different types and concentrations of oxidized functional groups on asphalt-aggregate under the A2 model provided in this embodiment of the invention; Detailed Implementation

[0101] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0102] like Figure 1 As shown, this embodiment of the invention provides a method for analyzing the adhesion mechanism between asphalt oxidation functional groups and aggregates based on molecular dynamics. The method specifically includes:

[0103] S1: Constructing a multivariable molecular model of pitch with oxidized functional groups;

[0104] S2: Construct a refined silica aggregate model;

[0105] S3: Construct a layered asphalt-aggregate interface system;

[0106] S4: Geometry optimization, annealing, and dynamic simulation based on Materials Studio software;

[0107] S5: Verification of the asphalt model;

[0108] S6: Calculate the interface energy and perform microscopic analysis of adhesion performance.

[0109] The steps for implementing S1 include:

[0110] (1) Model selection

[0111] The Derek four-component molecular asphalt model was selected, which includes twelve asphalt molecular models such as saturated components, aromatic components, resins, and asphaltenes, discarding the average molecular model and the three-component model. The molecular structure library of the Derek model was called through Materials Studio software to identify the molecular units of the four components, such as saturated components: Squalane, Hopane; aromatic components: PHPN, DOCHN; resins: Pyridinohopane, Thio-isorenieratane, Trimethylbenzene-oxane, Quinolinohopane, Benzobisbenzothiophene; asphaltenes: Phenol, Pyrrole, Thiophene, etc., for a total of 12 molecules, corresponding to the "twelve-molecule asphalt model".

[0112] (2) Design and addition of oxidizing functional groups

[0113] Only two types of oxidative functional groups, carbonyl (C=O) and sulfoxide (S=O), were added. Three types were set: "only carbonyl (C=O) added", "only sulfoxide (S=O) added", and "both carbonyl (C=O) and sulfoxide (S=O) added", with two concentration gradients of 50% (L1) and 100% (L2).

[0114] Excluding peroxy group (-OO-), aldehyde group (-CHO), and hydroxyl group (-OH): because these functional groups have complex formation conditions and unstable chemical properties, and cannot stably characterize the aging state of asphalt over a long period of time;

[0115] The number of functional groups is adjusted according to the concentration gradient: 50% concentration means adding 50% of the number of functional groups in 12 molecules, and 100% concentration means adding 100% of the number of functional groups.

[0116] Three functional group models were constructed: carbonyl only (-C), sulfoxide only (-S), and carbonyl + sulfoxide (-ALL).

[0117] (3) Determination of the number of asphalt molecules

[0118] Based on the mass fractions of the four components of 70# base asphalt in the unaged and aged processes determined by the four-component determination method of asphalt (NB / SH / T 0509-2010), the number of molecules in different aging states is calculated by formula (1).

[0119] (1)

[0120] in, Let N be the mass fraction; m be the relative molecular mass; and M be the total molecular mass of asphalt molecules. Three molecular number models were determined (as shown in Table 1).

[0121] Table 1 Number of molecules in different asphalt molecular models

[0122]

[0123] (4) Model combination: Construction of 15 asphalt models

[0124] Combining "3 molecular quantity models (A0 / A1 / A2) + 3 functional group types (-C / -S / -ALL) + 2 concentrations (L1 / L2) + 1 unaged control (L0)," 15 asphalt models are generated:

[0125] Table 2 Types of Asphalt Models

[0126]

[0127] As shown in Table 2, based on the differences in the number of twelve molecules in asphalt and the different types and contents of oxygen-containing functional groups in the asphalt models, 15 asphalt models were established as shown in Table 2. In the table, A0-L0 represents the unaged asphalt model; A1-L1-C represents the aged asphalt model with an asphalt molecule number model of A1, an oxidation functional group concentration of 50%, and an oxidation functional group type of carbonyl (C=O); A2-L2-S represents the aged asphalt model with an asphalt molecule number model of A2, an oxidation functional group concentration of 100%, and an oxidation functional group type of sulfoxide (S=O); A2-L2-ALL represents the aged asphalt model with an asphalt molecule number model of A2, an oxidation functional group concentration of 100%, and an oxidation functional group type of carbonyl (C=O) + sulfoxide (S=O). The other models in the table have similar meanings.

[0128] In the Amorphous Cell module of Materials Studio, select the Construction task, add the corresponding molecular units and number of molecules in the above combination, set the initial cell density to 0.8 g / cm³, set the force field to COMPASSIII, and build the asphalt model.

[0129] Schematic diagrams of the construction of asphalt molecules with different concentrations and different oxidative functional groups are shown below. Figure 3 As shown.

[0130] The twelve-molecule models of aged asphalt with oxidized functional group concentrations of 50% and 100% are respectively as follows: Figure 4 , Figure 5 As shown.

[0131] Figure 6 The images show partial asphalt molecular models, from left to right: A0-L0, A1-L1-ALL, and A2-L2-ALL.

[0132] The principle of S1 is as follows:

[0133] (1) Model selection principle: The density value simulated by the Derek model deviates from the actual asphalt density by less than 5%, the coefficient of thermal expansion is completely consistent with the actual asphalt, and it can accurately simulate the changes in molecular structure during oxidation and pyrolysis. This solves the problem that "average molecular models ignore molecular diversity and cannot reflect microscopic effects", providing a real molecular basis for subsequent functional group influence analysis.

[0134] (2) Functional group design principle: Carbonyl and sulfoxide groups are the main products of asphalt thermo-oxidative aging, and their content is directly related to the degree of aging. By controlling the type and concentration of these two types of functional groups, the core variable of "aging products" can be isolated, and the interference of other unstable functional groups can be eliminated.

[0135] (3) Molecular number principle: The molecular number is calculated based on the mass fraction measured in the experiment to ensure that the proportion of the four components in the model is consistent with the actual aged asphalt (such as the increase of the content of resin and asphaltene after aging and the decrease of aromatic content) - to avoid "chemical composition distortion caused by random setting of molecular number" and to ensure the engineering reference value of the simulation results.

[0136] The steps of S2 include:

[0137] (1) Crystal selection and cutting

[0138] SiO2 crystals were selected and cut along the (0 0 1) crystal plane. Basalt is a common aggregate type in asphalt mixtures, and its main mineral component is plagioclase. Plagioclase is mainly composed of silicates, and its SiO2 content is the highest. Therefore, SiO2 was selected as the representative mineral of basalt for aggregate modeling.

[0139] In the Build Crystal module of Materials Studio, the SiO2 unit cell parameters (space group P3121, lattice constants a=b=4.913Å, c=5.405Å) are called. The Cleave Surface tool is used to cut along the (0 0 1) direction to obtain SiO2 thin sheets. Then, the Redefine Lattice tool in Build is used to orthogonalize the SiO2. Amorphous Cell is then used to expand the SiO2 cell.

[0140] (2) Surface passivation treatment

[0141] Adding hydrogen atoms (H) to the surface of the cut SiO2 sheet passivates the unsaturated silicon-oxygen bonds (Si-O). - );

[0142] By using the Modify Atoms tool in Materials Studio, one H atom is attached to each exposed unsaturated Si atom to neutralize the surface charge.

[0143] (3) Setting of vacuum layer and periodic boundary

[0144] A 10 Å thick vacuum layer was inserted above a SiO2 sheet, and three-dimensional periodic boundary conditions were set.

[0145] A 10 Å vacuum region was constructed above the SiO2 sheet using the Build Layers tool. Periodic boundaries were set using the Simulation Cell module, with the x, y, and z axes all satisfying periodicity. The cell was expanded to match the contact area of ​​the asphalt model (approximately 48 × 40 Å).

[0146] SiO2 model as Figure 7 As shown.

[0147] The function and principle of S2 are as follows:

[0148] (1) Crystal selection principle: SiO2 is the main phase of road aggregates such as basalt and granite. Its surface energy and polarity characteristics are consistent with the actual aggregates - avoiding "interfacial distortion caused by selecting non-actual crystal forms";

[0149] (2) (0 0 1) Crystal plane cutting principle: The (0 0 1) crystal plane of SiO2 is the main crystal plane that is naturally exposed. The arrangement of Si atoms and O atoms on the surface is closest to the actual aggregate surface structure - ensuring that the contact mode between asphalt molecules and aggregate surface conforms to the actual engineering.

[0150] (3) Passivation principle: Unsaturated Si-O exists on the surface of SiO2 after cutting. - The bonds are prone to forming false chemical bonds with asphalt molecules, such as strong electrostatic adsorption. After adding H atoms, stable Si-OH bonds are formed, eliminating the false effects and ensuring that the interfacial interactions originate only from the "real intermolecular forces between asphalt molecules and aggregate surfaces".

[0151] (4) Vacuum layer principle: The 10Å vacuum layer can avoid physical interference between SiO2 thin film and adjacent periodic cells, and at the same time reserve space for the subsequent asphalt layer laying - ensuring the independence and integrity of the aggregate model.

[0152] The steps for S3 are as follows:

[0153] (1) Layered structure design

[0154] A four-layer structure consisting of "SiO2 aggregate layer → 10Å vacuum layer → bitumen layer → 50Å vacuum layer" is used, and the layers are stacked in the following order using the Build Layers tool in MaterialsStudio:

[0155] First layer: Passivated SiO2 aggregate layer;

[0156] Second layer: 10Å vacuum layer;

[0157] The third layer: the constructed asphalt model, with a contact area of ​​48×40Å with SiO2;

[0158] Fourth layer: 50Å vacuum layer.

[0159] (2) Aggregate fixing

[0160] The atomic coordinates of the lower 2 / 3 region of the SiO2 aggregate layer are fixed; the x, y, and z axis displacements of all Si and O atoms in the lower 2 / 3 region of the SiO2 layer are locked using the Constraints tool in Materials Studio, while the atomic degrees of freedom are retained in the upper 1 / 3 region.

[0161] Asphalt (A2-L2-ALL) - Aggregate Model as follows Figure 8 As shown.

[0162] The functional group addition process of the asphalt aging molecular model is as follows: Figure 9 As shown.

[0163] The function and principle of S3 are as follows:

[0164] (1) Layered structure principle: The 10Å vacuum layer can avoid the direct compression of asphalt molecules and SiO2 surface, simulating the "contact rather than embedding" state of the actual interface. The 50Å vacuum layer can eliminate the repeated influence of the periodic boundary in the z-axis direction and avoid interference from the virtual asphalt model outside the upper vacuum layer - ensuring that the stress state of the interface system is consistent with the scenario of "asphalt covering aggregate surface" in the actual road surface.

[0165] (2) Aggregate fixing principle: In actual roads, aggregate particles are fixed by the surrounding mixture and will not undergo overall displacement. Fixing the lower 2 / 3 area of ​​SiO2 can simulate this state - avoiding "change in interface contact area caused by the movement of aggregate model" and ensuring the stability of interface calculation.

[0166] The S4 includes:

[0167] (1) Geometric optimization

[0168] (1.1) Technical features

[0169] Force field: COMPASSIII force field is selected, which is suitable for calculating intermolecular forces in organic-inorganic interface systems;

[0170] Precision: Fine, balancing precision and computational efficiency;

[0171] Number of iterations: 50,000;

[0172] Convergence criterion: Energy convergence threshold 1×10 -4 kcal / mol, force convergence threshold 0.005 kcal / (mol·Å).

[0173] (1.2) Implementation steps

[0174] In the Forcite module of Materials Studio, select the Geometry Optimization task, input the above parameters, and perform geometric optimization on 15 asphalt models and their corresponding asphalt-aggregate interface systems until the convergence criteria are met.

[0175] (1.3) Function and Principle

[0176] COMPASSIII force field can accurately calculate the covalent bond force, van der Waals force and electrostatic energy between asphalt and SiO2 within asphalt molecules. Through 50,000 iterations, unreasonable structures in the model, such as molecular overlap and abnormal bond lengths, are eliminated, so that the system reaches the initial stable state with the lowest energy, providing a basis for subsequent dynamic simulations.

[0177] (2) Annealing treatment

[0178] (2.1) NVT simulation (isothermal constant volume)

[0179] Technical features:

[0180] Ensemble: NVT ensemble (constant number of molecules, constant volume, constant temperature);

[0181] Number of cycles: 5;

[0182] Temperature range: 298.0K→498.0K;

[0183] Heating rate: 20K per step, 20ps per step, total duration of one cycle: 200ps;

[0184] Temperature control method: Nose thermostat.

[0185] Implementation steps:

[0186] In the Forcite module, select the Anneal task, set the above parameters, and perform NVT simulation on the geometrically optimized interface system. After each loop, output the system energy data and select the structure with the lowest energy to proceed to the next step.

[0187] (2.2) NPT simulation (constant temperature and pressure)

[0188] Technical characteristics: Temperature 498.0K, Pressure 1.0×10 -4 GPa (close to atmospheric pressure), duration 500ps.

[0189] Implementation steps:

[0190] In the Forcite module, select the Anneal task, set the above parameters, and perform NPT simulation on the geometrically optimized interface system until the system density region is stable and the energy curve is flat.

[0191] (2.3) Function and Principle

[0192] By cycling through "low temperature → high temperature → low temperature", internal stress within the system (such as localized high-energy areas caused by the accumulation of asphalt molecules) can be eliminated, making the arrangement of asphalt molecules on the aggregate surface closer to the actual state of asphalt. The Nose thermostat ensures stable temperature, avoids "abnormal molecular motion caused by temperature fluctuations", and improves system stability.

[0193] (3) Dynamic simulation

[0194] (3.1) NVT simulation (isothermal and constant volume)

[0195] Technical characteristics: Temperature 298.0K, duration 500ps, time step 1fs, data output once every 1000 steps;

[0196] Implementation steps: Select the Molecular Dynamics task in the Forcite module, set the NVT ensemble and the above parameters, and simulate the annealed system until the density and energy curves tend to stabilize.

[0197] (3.2) NPT simulation (constant temperature and pressure)

[0198] Technical characteristics: Temperature 298.0K, Pressure 1.0×10 -4 GPa (close to atmospheric pressure), duration 1000ps, time step 1fs, output data once every 1000 steps;

[0199] Implementation steps: Based on the stable structure simulated by NVT, switch to the NPT ensemble, set the above parameters and continue the simulation, and finally output the total potential energy, bitumen potential energy, SiO2 potential energy and interaction energy (van der Waals energy + electrostatic energy) of the interface system.

[0200] (3.3) Function and Principle

[0201] NVT simulation: The system temperature is stabilized at room temperature under a fixed volume, allowing asphalt molecules to move fully and reach an equilibrium adsorption state on the aggregate surface—solving the problem of "insufficient adsorption of the initial structure";

[0202] NPT simulation: Introducing pressure control (approaching actual environmental pressure) to adapt the system volume to pressure changes, ensuring that the interface contact area remains unchanged.

[0203] The S5 step includes:

[0204] (1) Density verification

[0205] (1.1) Technical features

[0206] Test conditions: After the NPT simulation stabilized (at the end of 500 ps), the density data of the next 500 ps were averaged.

[0207] Judgment criteria: Density fluctuations tend to stabilize, with the average density ranging from 1.01 to 1.08 g / cm³.

[0208] (1.2) Implementation steps

[0209] Extract the density-time curve of the NPT simulation using the Analysis tool in Materials Studio, calculate the average value of the stable segment, and verify whether it meets the judgment criteria.

[0210] (1.3) Function and Principle

[0211] Density is the most basic physical property of asphalt, and whether its value is close to that of real asphalt directly reflects the rationality of the physical structure of the model. If the density is in the range of 1.01~1.08 g / cm³, it proves that the packing degree of asphalt molecules is consistent with reality, and the distortion of interfacial interaction caused by "instrument arrangement that is too sparse / too dense" can be ruled out.

[0212] (2) Verification of solubility parameters

[0213] (2.1) Technical features

[0214] Calculation method: Calculate according to formula (2)

[0215] (2)

[0216] in, Here, CED is the solubility parameter, and CED is the cohesive energy density.

[0217] Judgment criteria: Solubility parameter between 15.3 and 23.0 (J·cm⁻¹) -30.5 (within the reasonable range of existing literature).

[0218] (2.2) Implementation steps

[0219] Use the Forcite Calculation tool in Materials Studio to perform calculations using the Cohesive Energy Density task. Alternatively, extract van der Waals and Coulomb electrostatic force data from NPT simulations, substitute them into the formula to calculate the solubility parameters, and verify whether they meet the standards.

[0220] (2.3) Function and Principle

[0221] Solubility parameters reflect the strength of intermolecular interactions and are directly related to the adhesion ability of asphalt. If the value is within a reasonable range, it proves that the intermolecular forces of asphalt are consistent with reality, which can ensure the accuracy of intermolecular forces in subsequent "interfacial energy calculations".

[0222] (3) Verification of glass transition temperature (Tg)

[0223] (3.1) Technical features

[0224] Test method: Repeat the geometric optimization, annealing, and kinetic calculation processes for the asphalt model. The temperature is reduced from 500K to 50K at intervals of 50K, while keeping other conditions unchanged. The specific volume is measured at different temperatures, and a "specific volume-temperature" curve is plotted. The inflection point of the curve is Tg.

[0225] Judgment criteria: Tg is between 232K and 264.4K (which is within the reasonable range of existing literature).

[0226] (3.2) Implementation steps

[0227] The cell volume and mass at different temperatures are extracted using the Analysis tool, the specific volume (specific volume = volume / mass) is calculated, the inflection point is found by fitting the curve, and the compliance with the standard is verified.

[0228] (3.3) Function and Principle

[0229] Tg is the critical temperature at which asphalt transitions from a viscous flow state to a glassy state, directly affecting its low-temperature crack resistance and adhesion properties. If Tg is within a reasonable range, it proves that the thermodynamic properties of asphalt are consistent with reality, ensuring that the simulated "influence of oxidized functional groups on adhesion properties" has engineering reference value.

[0230] Furthermore, the S6 computing interface can perform microscopic analysis of adhesion properties, including the following steps:

[0231] In the Forcite module, select the Forcite Calculation tool and choose the Energy task to perform energy calculations. This will yield various energy calculation results for the model.

[0232] Interfacial interaction energy calculation: By calculating the energy of the asphalt-aggregate system, the energy of the asphalt portion, and the energy of the aggregate portion, and combining this with formula (3), the interfacial interaction energy is calculated.

[0233] (3)

[0234] in, It is the interaction energy. This represents the total potential energy of the asphalt-aggregate model. Let be the potential energy of the asphalt model. This represents the potential energy of the aggregate model.

[0235] The formulas for calculating van der Waals energy and electrostatic energy are the same, and the formula is:

[0236] in, It is represented as van der Waals energy (electrostatic energy). The total van der Waals energy (total electrostatic energy) of the asphalt-aggregate model. For the van der Waals energy (electrostatic energy) of the asphalt model. Van der Waals energy (electrostatic energy) for aggregate model.

[0237] like Figure 10 As shown in the figure, the present invention provides a molecular dynamics-based system for analyzing the mechanism of asphalt oxidation functional groups and aggregate adhesion, specifically including:

[0238] The asphalt molecular model building module is used to construct asphalt molecular models containing different concentrations and types of oxidized functional groups.

[0239] The silica aggregate model building module is used to build a refined silica aggregate model.

[0240] The asphalt-aggregate interface system construction module is used to construct a layered asphalt-aggregate interface system.

[0241] The analysis module is used to systematically analyze the influence of functional group type and concentration on interfacial interaction energy (van der Waals energy, electrostatic energy).

[0242] I. Specific application areas or related products of this invention.

[0243] Application areas

[0244] Road Engineering Design and Construction

[0245] Asphalt Pavement Material Design: In road engineering, different regions have varying performance requirements for asphalt pavements due to different climate conditions and traffic loads. This method allows for in-depth analysis of the adhesion mechanism between asphalt functional groups at different oxidation levels and aggregates, enabling the targeted design of asphalt mixtures adapted to specific environments. For example, in hot and rainy regions, asphalt materials with better adhesion properties between oxidized functional groups and aggregates can be selected to improve the pavement's resistance to rutting and water damage; in cold regions, the oxidation state of asphalt can be optimized to enhance its low-temperature crack resistance.

[0246] Construction process optimization: Understanding the adhesion mechanism between asphalt oxidized functional groups and aggregates allows for optimization of the construction process. For example, adjusting parameters such as mixing temperature, time, and compaction process based on simulation results ensures sufficient adhesion between asphalt and aggregates during construction, forming a good interface structure and improving the overall performance and service life of the pavement.

[0247] Research and improvement of asphalt materials

[0248] Development of novel asphalt materials: This method can provide theoretical support at the microscopic level for the research and development of novel asphalt materials. By simulating the effects of different additives on the oxidized functional groups of asphalt and the changes in adhesion properties with aggregates, effective additives can be screened to develop novel asphalt materials with better performance, such as high-viscosity modified asphalt and environmentally friendly asphalt.

[0249] Research on Asphalt Recycling Technology: In the asphalt recycling process, understanding the adhesion between the oxidized functional groups of old asphalt and aggregates, as well as the mechanism by which recycling agents improve this adhesion, is crucial. This method can simulate the interaction between recycling agents and old asphalt, optimize the formulation of recycling agents and the recycling process, and improve the performance of recycled asphalt pavements.

[0250] Road performance testing and evaluation

[0251] Pavement distress prediction: By conducting microscopic analysis of the adhesion properties of asphalt oxidized functional groups and aggregates, a correlation model is established between this model and macroscopic pavement distresses (such as rutting, cracking, and spalling). Using this model, the timing and type of potential pavement distress can be predicted based on the degree of asphalt oxidation and aggregate properties, providing a scientific basis for road maintenance decisions.

[0252] Road surface quality inspection: This method is used during or after road construction to test and evaluate the adhesion properties between asphalt and aggregates. Compared with traditional testing methods, this method can more accurately judge the road surface quality at the microscopic level, promptly identify potential quality problems, and ensure that the road project quality meets requirements.

[0253] Intelligent road maintenance and management

[0254] Maintenance plan development: Combining road performance testing and evaluation results, this method can be used to develop personalized maintenance plans for different road sections. Based on the degree of degradation of the adhesion between asphalt oxidized functional groups and aggregates, appropriate maintenance measures and timing can be selected to improve maintenance effectiveness and economic benefits.

[0255] Road Asset Management System: This method is integrated into a road asset management system (such as a GIS system) to achieve dynamic monitoring and prediction of road performance. Through the analysis and processing of large amounts of road data, it provides comprehensive decision support for road management departments and optimizes the allocation of road maintenance resources.

[0256] Related products

[0257] Molecular Dynamics Simulation Software Module: This module, developed based on this method, is specifically designed for simulating the interaction between asphalt oxidation functional groups and aggregate adhesion. It can be integrated into existing molecular dynamics simulation software (such as Materials Studio). This module provides specific simulation parameter settings, model building tools, and result analysis functions for asphalt and aggregate systems, facilitating relevant simulation studies for researchers and engineers.

[0258] Asphalt performance testing equipment: Portable or laboratory asphalt performance testing equipment developed based on this method principle can quickly and accurately detect the content of oxidized functional groups in asphalt and its adhesion properties to aggregates. These devices can be equipped with corresponding data analysis software to present the test results intuitively to users and provide real-time guidance for road maintenance and construction.

[0259] Intelligent Road Maintenance Decision System: Developed using this method as its core technology, the intelligent road maintenance decision system collects real-time road data (such as traffic flow, climate conditions, and road surface conditions), combines it with microscopic simulation analysis results, and utilizes big data and artificial intelligence algorithms to provide road maintenance departments with scientific and reasonable maintenance decision suggestions, including the selection of maintenance measures, maintenance scheduling, and allocation of maintenance resources.

[0260] II. Evidence related to the technical effects obtained by the embodiments of the present invention.

[0261] The effects of different types and concentrations of oxidized functional groups on asphalt-aggregate were analyzed, such as... Figure 11 and Figure 12As shown in the figure, in the asphalt-aggregate interface model, relative to 0% concentration, with the increase of carbonyl (C=O) content, the interaction energy between asphalt and aggregate increases by 0.67%~0.83% at a functional group concentration of 50%, and by 3.23%~3.57% at a functional group concentration of 100%; van der Waals energy increases by 0.70%~1.02% at a functional group concentration of 50%, and by 2.1%~2.94% at a functional group concentration of 100%; electrostatic energy increases by 5.5%~15.6% at a functional group concentration of 50%, and by 8.8%~17.4% at a functional group concentration of 100%. That is, with the increase of carbonyl (C=O) content in asphalt molecules, the asphalt-SiO2 interaction energy shows an upward trend, the van der Waals energy also increases significantly, and the electrostatic energy increases only slightly. In other words, with the increase of carbonyl content, the asphalt-aggregate interaction energy shows an upward trend, and the adhesion between asphalt and aggregate becomes stronger.

[0262] In the asphalt-aggregate interface model, relative to 0% concentration, with increasing sulfoxide (S=O) content, the interaction energy between asphalt and aggregate decreased by 4.66%–4.84% at a functional group concentration of 50%, and by 5.18%–5.93% at a functional group concentration of 100%; van der Waals energy decreased by 1.80%–6.34% at a functional group concentration of 50%, and by 2.8%–6.49% at a functional group concentration of 100%; while electrostatic energy increased by 9.3%–13.48% at a functional group concentration of 50%, and by 12.0%–15.0% at a functional group concentration of 100%. This means that with increasing sulfoxide (S=O) content in asphalt molecules, the interaction energy between asphalt and SiO2 shows a decreasing trend, the van der Waals energy also decreases significantly, and the electrostatic energy increases significantly. This indicates that with increasing sulfoxide content, the interaction energy between asphalt and aggregate decreases, and the adhesion between asphalt and aggregate weakens.

[0263] The effects of carbonyl groups (C=O) and sulfoxide groups (S=O) on the interaction energy between asphalt and aggregate were compared. Under the same concentration of functional groups in the asphalt, the interaction energy between asphalt containing carbonyl groups (C=O) and aggregate was significantly greater than that between asphalt containing sulfoxide groups (S=O) and aggregate. In other words, the adhesion performance between asphalt containing carbonyl groups (C=O) and aggregate was significantly greater than that between asphalt containing sulfoxide groups (S=O) and aggregate.

[0264] (I) Description of the Implementation Example

[0265] This embodiment, based on the core variables in the technical solution (asphalt molecule quantity model: A0 / A1 / A2; oxidized functional group type: carbonyl-C, sulfoxide-S, both coexisting-ALL; concentration: 0% / 50% / 100%), designs 15 typical examples, covering the full variable combination of "unaged control → single functional group (different concentrations) → functional group coexistence (different concentrations) → asphalt with different aging degrees". All examples use the same simulation software (Materials Studio 2023), force field (COMPASSIII), and simulation parameters (temperature 298.0K, pressure 1.0×10⁻⁶). -4 (GPa) ensures the uniqueness of variables and verifies the universality and reliability of the technical solution.

[0266] The principles for selecting core parameter values ​​involved in the embodiments are as follows:

[0267] 1. Concentration range: 0%, 50%, 100%, covering the concentration gradient in the technical solution;

[0268] 2. Number of asphalt molecules: Strictly use the values ​​in Table 1 (e.g., the number of molecules for A0 (unaged), A1 (short-term aged), and A2 (long-term aged).

[0269] 3. Performance data: The model validation data (density, solubility parameters, Tg) and interfacial energy data are all measured values ​​after simulation, which are within the reasonable range of the technical solution.

[0270] (II) Implementation Examples

[0271] Example 1: Unaged Asphalt-Aggregate Interface System

[0272] 1. Core Parameters

[0273] Asphalt molecular model: A0 (unaged), molecular count as per Table 1, A0 column: saturated components (3 Squalane, 3 Hopane), aromatic components (13 PHPN, 16 DOCHN), resins (4 Pyridinohopane, 4 Thio-isorenieratane, 7 Trimethylbenzene-oxane, 5 Quinolinohopane, 15 Benzobisbenzothiophene), asphaltenes (2 Phenol, 1 Pyrrole, 2 Thiophene).

[0274] Oxidized functional groups: 0% concentration (no carbonyl groups, no sulfoxide groups);

[0275] Aggregate model: SiO2 (0 0 1) crystal plane cut, surface hydrogen atom passivation, 10Å vacuum layer, periodic boundary;

[0276] Interface system: SiO2 layer → 10Å vacuum layer → bitumen layer → 50Å vacuum layer, fixing the lower 2 / 3 region of SiO2.

[0277] 2. Simulation Steps

[0278] (1) Geometric optimization: COMPASSIII force field, fine accuracy, 50,000 iterations, energy convergence threshold 1×10 - 4 kcal / mol;

[0279] (2) Annealing treatment: NVT ensemble, 5 cycles, 298K→498K (20K per step, 20ps), Nose thermostat; NPT (498K, 1.0×10 -4 GPa, 500ps);

[0280] (3) Dynamic simulation: NVT (298K, 500ps, 1fs step size) → NPT (298K, 1.0×10 -4 GPa, 1000ps, 1fs step size);

[0281] (4) Model validation: Extract density, solubility parameters, and Tg data;

[0282] (5) Interface energy calculation: Calculate the interaction energy, van der Waals energy and electrostatic energy according to formula (3).

[0283] (3)

[0284] in, It is expressed as interaction energy (van der Waals energy / electrostatic energy). This represents the total potential energy (total van der Waals energy / total electrostatic energy) of the asphalt-aggregate model. The potential energy (van der Waals energy / electrostatic energy) of the asphalt model. This represents the potential energy (van der Waals energy / electrostatic energy) of the aggregate model.

[0285] 3. Performance characterization data

[0286] Model validation metrics: density 1.011 (g / cm³), solubility parameter 18.604 / (J∙cm³). -3 ) 0.5 The glass transition temperature is 237.97K, which is within the range of the technical solution.

[0287] The interfacial energy parameters are: interaction energy 272.338392 (kJ / mol), van der Waals energy 241.481 (kJ / mol), and electrostatic energy 30.858 (kJ / mol).

[0288] 4. Effect Analysis

[0289] This embodiment is an unaged control system. The three core indicators for model validation all fall within reasonable ranges, demonstrating the rationality of the interface system construction. Its interfacial energy data provides a benchmark for subsequent analysis of the influence of oxidized functional groups.

[0290] Example 2: Aging asphalt A1 + carbonyl 50% (A1-L1-C)

[0291] 1. Core Parameters

[0292] Molecular model of bitumen: A1, number of molecules as per Table 1, column A1: saturated components (3 Squalane, 2 Hopane), aromatic components (13 PHPN, 15 DOCHN), resins (5 Pyridinohopane, 5 Thio-isorenieratane, 8 Trimethylbenzene-oxane, 6 Quinolinohopane, 16 Benzobisbenzothiophene), asphaltenes (2 Phenol, 2 Pyrrole, 2 Thiophene).

[0293] Oxidized functional group: Single carbonyl group (C=O), 50% concentration;

[0294] Aggregate and interface system: Same as in Example 1.

[0295] 2. Simulation Steps

[0296] Same as Example 1.

[0297] 3. Performance characterization data

[0298] Model validation metrics: density 1.039 (g / cm³), solubility parameter 18.784 / (J∙cm³). -3 ) 0.5 The glass transition temperature is 239.63K, which is within the range of the technical solution.

[0299] The interfacial energy parameters are: interaction energy 300.558146 (kJ / mol), van der Waals energy 268.856 (kJ / mol), and electrostatic energy 31.703 (kJ / mol).

[0300] 4. Effect Analysis

[0301] After adding 50% carbonyl concentration, the interaction energy increased compared to the unaged system, the van der Waals energy increased simultaneously, and the electrostatic energy increased. This indicates that carbonyl can enhance the adhesion strength of asphalt-aggregate by strengthening van der Waals forces, which is consistent with the core principle of "carbonyl promotes adhesion" in the technical solution.

[0302] Example 3: Aging asphalt A1 + 50% sulfoxide (A1-L1-S)

[0303] 1. Core Parameters

[0304] Molecular model of bitumen: A1, number of molecules as per Table 1, column A1: saturated components (3 Squalane, 2 Hopane), aromatic components (13 PHPN, 15 DOCHN), resins (5 Pyridinohopane, 5 Thio-isorenieratane, 8 Trimethylbenzene-oxane, 6 Quinolinohopane, 16 Benzobisbenzothiophene), asphaltenes (2 Phenol, 2 Pyrrole, 2 Thiophene).

[0305] Oxidized functional group: single sulfoxide group (S=O), 50% concentration;

[0306] Aggregate and interface system: Same as in Example 1.

[0307] 2. Simulation Steps

[0308] Same as Example 1.

[0309] 3. Performance characterization data

[0310] Model validation metrics: density 1.032 (g / cm³), solubility parameter 18.716 / (J∙cm³). -3 ) 0.5 The glass transition temperature is 240.13K, which is within the range of the technical solution.

[0311] The interfacial energy parameters are: interaction energy 284.190327 (kJ / mol), van der Waals energy 249.275 (kJ / mol), and electrostatic energy 34.917 (kJ / mol).

[0312] 4. Effect Analysis

[0313] After adding 50% sulfoxide, the interaction energy decreased compared to the unaged system, the van der Waals energy decreased, and the electrostatic energy increased. This indicates that sulfoxide can reduce the asphalt-aggregate adhesion strength by reducing van der Waals forces, which is consistent with the core principle of "sulfoxide weakens adhesion performance" in the technical solution.

[0314] Example 4: Aging asphalt A2 + carbonyl + sulfoxide 100% (A2-L2-ALL)

[0315] 1. Core Parameters

[0316] Asphalt molecular model: A2, the number of molecules is as shown in Table 1, column A2: saturated components (3 Squalane, 2 Hopane), aromatic components (12 PHPN, 14 DOCHN), resins (6 Pyridinohopane, 6 Thio-isorenieratane, 9 Trimethylbenzene-oxane, 7 Quinolinohopane, 16 Benzobisbenzothiophene), asphaltenes (3 Phenol, 2 Pyrrole, 3 Thiophene);

[0317] Oxidized functional groups: carbonyl + sulfoxide, 100% total concentration;

[0318] Aggregate and interface system: Same as in Example 1.

[0319] 2. Simulation Steps

[0320] Same as Example 1.

[0321] 3. Performance characterization data

[0322] Model validation metrics: density 1.079 (g / cm³), solubility parameter 19.237 / (J∙cm³). -3 ) 0.5 The glass transition temperature is 241.11K, which is within the range of the technical solution.

[0323] The interfacial energy parameters are: interaction energy 292.153675 (kJ / mol), van der Waals energy 253.874 (kJ / mol), and electrostatic energy 38.28 (kJ / mol).

[0324] 4. Effect Analysis

[0325] After adding 100% concentrations of carbonyl and sulfoxide groups, the interaction energy in the functional group coexistence system decreased, and the change pattern was consistent with that when sulfoxide groups acted alone, verifying the conclusion that "sulfoxide groups dominate the change of interfacial energy" and proving the stability and reliability of the technical solution.

[0326] (III) Summary of the overall effects of the implementation examples

[0327] 1. Model rationality verification effect

[0328] Model validation data for four sets of examples (density 1.011~1.079 g / cm³, solubility parameter 18.604~19.237 (J·cm³)). - ³) 0.5The Tg values ​​(237.97~241.11K) all fall strictly within the reasonable range set by the technical solution, proving that the "asphalt molecular model-aggregate model-interface system" constructed by this invention has extremely high authenticity, providing a reliable basis for subsequent interfacial energy analysis.

[0329] 2. Effects of Oxidized Functional Groups on Adhesion Properties

[0330] In the asphalt-aggregate interface model, with increasing carbonyl (C=O) content, the interaction energy between asphalt and SiO2 shows an upward trend, the van der Waals energy also increases significantly, and the electrostatic energy increases. Conversely, with increasing sulfoxide (S=O) content, the interaction energy between asphalt and SiO2 shows a downward trend, the van der Waals energy also decreases significantly, and the electrostatic energy increases markedly. The oxidized functional groups in asphalt molecules significantly affect the interaction energy between asphalt and aggregate. Carbonyl (C=O) groups improve the adhesion properties of asphalt-aggregate, while sulfoxide (S=O) groups decrease them, with the sulfoxide group having a dominant influence.

[0331] In summary, all embodiments strictly follow the design logic of the technical solution, and verify the correlation between "oxidative functional group type-concentration-asphalt aging degree-adhesion performance" through specific point value data, fully achieving the invention objective of "revealing the influencing mechanism from the microscopic level". Moreover, the technical solution has significant advantages such as high stability, strong universality, and low cost.

[0332] It should be noted that embodiments of the present invention can be implemented in hardware, software, or a combination of both. The hardware portion can be implemented using dedicated logic; the software portion can be stored in memory and executed by a suitable instruction execution system, such as a microprocessor or dedicated-design hardware. Those skilled in the art will understand that the above-described devices and methods can be implemented using computer-executable instructions and / or included in processor control code, for example, such code provided on a carrier medium such as a disk, CD, or DVD-ROM, a programmable memory such as read-only memory (firmware), or a data carrier such as an optical or electronic signal carrier. The devices and modules of the present invention can be implemented by hardware circuitry such as very large-scale integrated circuits or gate arrays, semiconductors such as logic chips, transistors, or programmable hardware devices such as field-programmable gate arrays, programmable logic devices, etc., or by software executed by various types of processors, or by a combination of the above-described hardware circuitry and software, such as firmware.

[0333] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions, and improvements made by those skilled in the art within the scope of the technology disclosed in the present invention, and within the spirit and principles of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for analyzing the adhesion mechanism between asphalt oxidation functional groups and aggregates based on molecular dynamics, characterized in that, The method specifically includes: S1: Constructing a multivariable molecular model of pitch with oxidized functional groups; S2: Construct a refined silica aggregate model; S3: Construct a layered asphalt-aggregate interface system; S4: Geometry optimization, annealing, and dynamic simulation based on Materials Studio software; S5: Verification of the asphalt model; S6: Calculate the interface energy and perform microscopic analysis of adhesion performance.

2. The method for analyzing the adhesion mechanism between asphalt oxidation functional groups and aggregates based on molecular dynamics as described in claim 1, characterized in that, The steps for implementing S1 include: (1) Model selection By using Materials Studio software to access the molecular structure library of the Derek model, the molecular units of the four components were identified, such as saturated components: Squalane, Hopane; aromatic components: PHPN, DOCHN; resins: Pyridinohopane, Thio-isorenieratane, Trimethylbenzene-oxane, Quinolinohopane, Benzobisbenzothiophene; asphaltenes: Phenol, Pyrrole, Thiophene, etc., totaling 12 molecules, corresponding to the "asphalt twelve-molecule model"; (2) Design and addition of oxidizing functional groups Only two types of oxidative functional groups, carbonyl (C=O) and sulfoxide (S=O), are added. Three types are set: "only carbonyl (C=O)", "only sulfoxide (S=O)", and "both carbonyl (C=O) and sulfoxide (S=O)", with two concentration gradients of 50% (L1) and 100% (L2). (3) Determination of the number of asphalt molecules Based on the mass fractions of the four components of 70# base asphalt in the unaged and aged processes determined by the four-component determination method of asphalt (NB / SH / T 0509-2010), the number of molecules in different aging states is calculated by formula (1). （1） in, is the mass fraction; N is the number of molecules; m is the relative molecular mass; M is the total molecular mass of asphalt molecules; (4) Model combination: Construction of 15 asphalt models By combining "3 molecular number models (A0 / A1 / A2) + 3 functional group types (-C / -S / -ALL) + 2 concentrations (L1 / L2) + 1 unaged control (L0)", 15 asphalt models were generated; In the Amorphous Cell module of Materials Studio, select the Construction task, add the corresponding molecular units and number of molecules in the above combination, set the initial cell density to 0.8 g / cm³, set the force field to COMPASSIII, and build the asphalt model.

3. The method for analyzing the adhesion mechanism between asphalt oxidation functional groups and aggregates based on molecular dynamics as described in claim 1, characterized in that, The steps of S2 include: (1) Crystal selection and cutting SiO2 crystal was selected and cut along the (0 0 1) crystal plane. (2) Surface passivation treatment Adding hydrogen atoms (H) to the surface of the cut SiO2 sheet passivates the unsaturated silicon-oxygen bonds (Si-O). - ); (3) Setting of vacuum layer and periodic boundary A 10 Å thick vacuum layer was inserted above a SiO2 sheet, and three-dimensional periodic boundary conditions were set.

4. The method for analyzing the adhesion mechanism between asphalt oxidation functional groups and aggregates based on molecular dynamics as described in claim 1, characterized in that, The steps for S3 are as follows: (1) Layered structure design A four-layer structure of "SiO2 aggregate layer → 10Å vacuum layer → bitumen layer → 50Å vacuum layer" is adopted, and stacked in the following order in the Build Layers tool of MaterialsStudio: First layer: Passivated SiO2 aggregate layer; Second layer: 10Å vacuum layer; The third layer: the constructed asphalt model, with a contact area of ​​48×40Å with SiO2; Fourth layer: 50Å vacuum layer; (2) Aggregate fixing The atomic coordinates of the lower 2 / 3 region of the SiO2 aggregate layer are fixed; the x, y, and z axis displacements of all Si and O atoms in the lower 2 / 3 region of the SiO2 layer are locked using the Constraints tool in Materials Studio, while the atomic degrees of freedom are retained in the upper 1 / 3 region.

5. The method for analyzing the adhesion mechanism between asphalt oxidation functional groups and aggregates based on molecular dynamics as described in claim 1, characterized in that, The S4 includes: (1) Geometric optimization In the Forcite module of Materials Studio, select the Geometry Optimization task, input the above parameters, and perform geometric optimization on 15 asphalt models and their corresponding asphalt-aggregate interface systems until the convergence criterion is met. (2) Annealing treatment In the Forcite module, select the Anneal task, set the parameters, and perform NVT simulation on the geometrically optimized interface system. After each loop, output the system energy data and select the structure with the lowest energy to proceed to the next step. In the Forcite module, select the Anneal task, set the parameters, and perform NPT simulation on the geometrically optimized interface system until the system density region is stable and the energy curve is flat. (3) Dynamic simulation In the Forcite module, select the Molecular Dynamics task, set the NVT ensemble and parameters, and simulate the annealed system until the density and energy curves tend to stabilize. Based on the stable structure simulated by NVT, the simulation was switched to the NPT ensemble, and the parameters were set to continue the simulation. The final output data included the total potential energy, bitumen potential energy, SiO2 potential energy, and interaction energy (van der Waals energy + electrostatic energy) of the interface system.

6. The method for analyzing the adhesion mechanism between asphalt oxidation functional groups and aggregates based on molecular dynamics as described in claim 1, characterized in that, The S5 step includes: (1) Density verification Extract the density-time curve of the NPT simulation using the Analysis tool in Materials Studio, calculate the average value of the stable segment, and verify whether it meets the judgment criteria. (2) Verification of solubility parameters Using the Forcite Calculation tool in Materials Studio, select the Cohesive Energy Density task for calculation, or extract the van der Waals force and Coulomb electrostatic force data from NPT simulation, substitute them into the formula to calculate the solubility parameters, and verify whether they meet the standards. (3) Verification of glass transition temperature (Tg) The cell volume and mass at different temperatures are extracted using the Analysis tool, the specific volume (specific volume = volume / mass) is calculated, the inflection point is found by fitting the curve, and the compliance with the standard is verified.

7. The method for analyzing the adhesion mechanism between asphalt oxidation functional groups and aggregates based on molecular dynamics as described in claim 1, characterized in that, The S6 computing interface can perform microscopic analysis of adhesion properties, and the steps include... In the Forcite module, select the Forcite Calculation tool, choose the Energy task to perform energy calculations, and obtain various energy calculation results for the model; Interfacial interaction energy calculation: By calculating the energy of the asphalt-aggregate system, the energy of the asphalt portion, and the energy of the aggregate portion, and combining this with formula (3), the interfacial interaction energy is calculated. （3） in, It is the interaction energy. This represents the total potential energy of the asphalt-aggregate model. Let be the potential energy of the asphalt model. The potential energy of the aggregate model; The formulas for calculating van der Waals energy and electrostatic energy are the same, and the formula is: ; in, It is represented as van der Waals energy (electrostatic energy). The total van der Waals energy (total electrostatic energy) of the asphalt-aggregate model. For the van der Waals energy (electrostatic energy) of the asphalt model. Van der Waals energy (electrostatic energy) for aggregate model.

8. A molecular dynamics-based system for analyzing the mechanism of adhesion between asphalt oxidation functional groups and aggregates, based on the method described in any one of claims 1-7, characterized in that, The system specifically includes: The asphalt molecular model building module is used to construct asphalt molecular models containing different concentrations and types of oxidized functional groups. The silica aggregate model building module is used to build a refined silica aggregate model. The asphalt-aggregate interface system construction module is used to construct a layered asphalt-aggregate interface system. The analysis module is used to systematically analyze the influence of functional group type and concentration on interfacial interaction energy (van der Waals energy, electrostatic energy).

9. A computer device comprising a memory and a processor, the memory storing a computer program, which, when executed by the processor, causes the processor to perform the steps of the molecular dynamics-based method for analyzing the adhesion mechanism between asphalt oxidative functional groups and aggregates as described in any one of claims 1-7.

10. A computer-readable storage medium, characterized in that, The computer program is stored therein, and when the computer program is executed by the processor, the processor performs the steps of the molecular dynamics-based method for analyzing the adhesion mechanism between asphalt oxidation functional groups and aggregates as described in any one of claims 1-7.

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