阅读说明：本技术 一种再生沥青混合料低温抗裂性能的评价方法 (Method for evaluating low-temperature cracking resistance of recycled asphalt mixture ) 是由 李强 陆杨 王家庆 刘嵩 赵曜 于 2021-07-26 设计创作，主要内容包括：本发明公开一种再生沥青混合料低温抗裂性能的评价方法,基于materials studio构建新、旧沥青无定形晶胞模型、再生剂分子模型以及集料中所含氧化物的超晶胞模型,对新、旧沥青无定形晶胞模型进行结构优化和退火处理得到体系能量最小模型,并对体系能量最小模型与氧化物超晶胞模型进行合理化验证,经build layer功能建立新沥青-再生剂-旧沥青的界面模型、再生沥青-再生沥青界面模型、再生沥青-氧化物界面模型,处理及计算得到再生沥青常温、低温时黏度、黏聚能以及与集料间的黏附能,经分析和加权计算得到评价再生沥青混合料低温抗裂的性能指标；本发明准确性高、操作简单,选用微观可量化的指标从分子尺度解释再生沥青混合料的性能。(The invention discloses an evaluation method of low-temperature crack resistance of a regenerated asphalt mixture, which comprises the steps of constructing a new and old asphalt amorphous unit cell model, a regenerant molecular model and a super unit cell model of oxides contained in aggregates based on materials studio, carrying out structural optimization and annealing treatment on the new and old asphalt amorphous unit cell models to obtain a minimum system energy model, carrying out rationalization verification on the minimum system energy model and the oxide super unit cell model, establishing a new asphalt-regenerant-old asphalt interface model, a regenerated asphalt-regenerated asphalt interface model and a regenerated asphalt-oxide interface model through build layer functions, processing and calculating to obtain a viscosity, cohesive energy and adhesive energy with the aggregates of the regenerated asphalt at normal temperature and low temperature, and obtaining a low-temperature crack resistance index of the regenerated asphalt mixture through analysis and weighted calculation; the invention has high accuracy and simple operation, and adopts microscopic quantifiable indexes to explain the performance of the regenerated asphalt mixture from the molecular scale.)

1. The method for evaluating the low-temperature cracking resistance of the recycled asphalt mixture is characterized by comprising the following steps of:

step 1, constructing a new asphalt amorphous unit cell model, an old asphalt amorphous unit cell model, a regenerant molecular model and a super unit cell model of oxides contained in aggregates based on materials studio software;

step 2, carrying out structural optimization and annealing treatment on the new and old asphalt amorphous unit cell models to obtain new and old asphalt amorphous unit cell models with the minimum system energy;

step 3, carrying out model rationalization verification on the new and old asphalt amorphous unit cell models with the minimum system energy and the super unit cell models of oxides contained in the aggregate;

step 4, establishing a new asphalt-regenerant-old asphalt interface model based on the build layer function, carrying out molecular dynamics simulation after mixing and dissolving to obtain a regenerated asphalt model, and then carrying out shear function simulated shearing to obtain the viscosity of the regenerated asphalt at normal temperature and low temperature;

step 5, establishing a regenerated asphalt-regenerated asphalt interface model and a regenerated asphalt-oxide interface model with equal interface areas based on the build layer function, and calculating to obtain the cohesive energy among the regenerated asphalt at normal temperature and low temperature and the adhesive energy of the regenerated asphalt-aggregate interface;

and 6, weighting and calculating the viscosity, the adhesion energy and the cohesion energy according to the comparison condition of the adhesion energy and the cohesion energy to obtain a low-temperature crack resistance index, and evaluating the low-temperature crack resistance of the regenerated asphalt mixture.

2. The method for evaluating the low-temperature crack resistance of the reclaimed asphalt mixture according to claim 1, which is characterized by comprising the following steps of: the new and old asphalt models in the step 1 comprise four-component and twelve-molecule structures, each molecular monomer is subjected to structure optimization, and the constraction function in the amophorus cell is utilized to obtain the asphalt model with the initial density of 0.1g/cm according to different molecular proportions³The new and old asphalt amorphous unit cell models are assembled in the 3D periodic cube box.

3. The method for evaluating the low-temperature crack resistance of the reclaimed asphalt mixture according to claim 1, which is characterized by comprising the following steps of: the process of constructing a super cell model of the oxides contained in the aggregate in step 1 is as follows,

firstly, establishing a crystal cell of oxide crystals in the contained aggregate, and carrying out structural optimization through geometry optimization in a cast; calculating the most stable and common cracking surface of each crystal by using the BFDH task in morphology calculation; using a clean surface function, intercepting a crystal face according to the cracking surface to establish an oxide unit cell surface model in the aggregate, wherein the thickness is set to be larger than a truncation radius; then using geometry optimization in the castep to carry out structural optimization on the surface model of the oxide unit cell in the aggregate; and adding a vacuum layer on the surface of the aggregate, and constructing a super cell model of the oxide contained in the aggregate by using build supercell function.

4. The method for evaluating the low-temperature crack resistance of the reclaimed asphalt mixture according to claim 1, which is characterized by comprising the following steps of: and 2, annealing the new and old asphalt amorphous unit cell models after the structure optimization is completed by using the aneal in the recipe module, wherein the circulating temperature is 300k-800k, the circulating times are 15-20 times, the step length is 1fs, the ensemble is set as NVT, the initial speed is set as random, the thermostat is set as Anderson, and the model with the minimum system energy in the circulating process is output.

5. The method for evaluating the low-temperature crack resistance of the reclaimed asphalt mixture according to claim 1, which is characterized by comprising the following steps of: the model rationalization verification process in step 3 is as follows,

calculating the solubility and the molecular order of the new and old asphalt amorphous unit cell models with the minimum system energy; the solubility is the square root of cohesive energy density output by the covalent energy density function, and is 15.3-23(J/cm3)^0.5The molecular ordering degree is obtained by analyzing an image output by the radial distribution function, the short-range ordering is shown, and the long-range disorder is reasonable; calculating a supercell model of oxides contained in the aggregate by using mechanical properties in a Forcite module, wherein the calculation method is constant strain, and the bulk modulus is obtainedYoung modulus, Poisson's ratio parameter, compare with actual parameter, verify the rationality of the super cell model of oxide.

6. The method for evaluating the low-temperature crack resistance of the reclaimed asphalt mixture according to claim 1, which is characterized by comprising the following steps of: the construction process of the regenerated asphalt model in the step 4 is as follows,

the method comprises the steps of firstly establishing an interface model of the new asphalt, the regenerant and the old asphalt by using a build layer function, calculating the number of molecules of the regenerant according to the doping amount, adopting a periodic boundary condition for the interface model, then carrying out dynamic kinetic simulation in a Forcite module, heating to 433k under an NVT (noise, vibration and harshness) ensemble, running the interface model with a step length of 200ps, running the interface model under an NPT ensemble after the heating is finished, fully mixing and dissolving, setting the initial speed to random, setting a thermostat to Anderson, setting a barostat to Berendsen, and obtaining the regenerated asphalt model after the kinetic simulation is finished.

7. The method for evaluating the low-temperature crack resistance of the reclaimed asphalt mixture according to claim 1, which is characterized by comprising the following steps of: the first layer of the regenerated asphalt-oxide interface model is the aggregate medium oxide super cell model, the second layer is the regenerated asphalt model, and the third layer is set through build vacuum slabThe vacuum layer of (1).

8. The method for evaluating the low-temperature crack resistance of the reclaimed asphalt mixture according to claim 1, which is characterized by comprising the following steps of: the calculation method of the cohesion energy between the reclaimed asphalts described in step 5 is as follows,

dynamically balancing in a fortite module on a regenerated asphalt-regenerated asphalt interface model, firstly cooling to 263k under an NVT (noise vibration and harshness) ensemble, then dynamically balancing under an NPT ensemble, and outputting total energy after the operation is finished, namely total system energy E of the regenerated asphalt-regenerated asphalt interface model_A1A2；

Are respectively and independentlyCalculating the system energy of the upper and lower regenerated asphalt layers and recording as E_A1、E_A2Cohesive energy at low temperature between reclaimed asphalts E_adhesion-lowObtained from equation (1):

E_adhesion-low＝E_A1A2-E_A1-E_A2 (1)；

changing the temperature to 300k, and repeating the above operation to obtain the cohesion energy E at normal temperature between the reclaimed asphalt_adhesion-mid。

9. The method for evaluating the low-temperature crack resistance of the reclaimed asphalt mixture according to claim 1, which is characterized by comprising the following steps of: the adhesion energy of the reclaimed asphalt-aggregate interface in step 5 is calculated as follows,

dynamic kinetic simulation in a fortite module is carried out on all regenerated asphalt-oxide interface models, the ensemble is set to be NVT, the cooling temperature is set to be 263k, the model is cooled by running for 200ps, and then the model is run for 1000ps under the NPT ensemble, so that the total energy E of the interface model is obtained_totalAnd the energy E of the aggregate oxide layer in the equilibrium state is obtained after the regenerated asphalt layer is removed_SRecovering the regenerated asphalt layer, removing the aggregate oxide layer and calculating to obtain the energy E when the regenerated asphalt layer is balanced_ASAdhesion energy of recycled asphalt-oxide interface E_ADFrom equation (2):

E_AD＝E_total-E_s-E_AS (2)；

the adhesion energy of the regenerated asphalt-aggregate interface at low temperature is the sum of the adhesion energy of all oxides in the aggregate and the regenerated asphalt multiplied by the content P of each oxide in the aggregate, and the sum is obtained by the formula (3)

E_AT-low＝E_AD1×P₁+E_AD2×P₂+……+E_ADn×P_n (3)；

Changing the temperature to 300k, and repeating the operation to obtain the adhesion energy E of the regenerated asphalt-aggregate interface at normal temperature_AT-mid。

10. The method for evaluating the low-temperature crack resistance of the reclaimed asphalt mixture according to claim 1, which is characterized by comprising the following steps of: the specific method for evaluating the low-temperature crack resistance of the recycled asphalt mixture in the step 6 is as follows,

selecting the viscosity V of the recycled asphalt in the recycled asphalt mixture at low temperature_LViscosity V of recycled asphalt at normal temperature_MCohesive energy at low temperature between reclaimed asphalts E_adhesion-lowAnd cohesive energy at normal temperature between reclaimed asphalts E_adhesion-midAdhesion energy at low temperature of recycled asphalt-aggregate interface E_AT-lowAdhesion energy at room temperature of recycled asphalt-aggregate interface E_AT-mid；

Comparison E_adhesion-lowAnd E_AT-lowWhen E is large or small_adhesion-lowGreater than E_AT-lowWhen the asphalt mixture is used, the adhesion of the regenerated asphalt mixture is prone to be damaged, and the low-temperature crack resistance index L is obtained by the formula (4)

When E is_adhesion-lowLess than E_AT-lowWhen the asphalt mixture is used, cohesive failure tends to occur in the recycled asphalt mixture, and the low-temperature crack resistance index L is obtained by the formula (5)

Technical Field

The invention relates to an evaluation method for low-temperature crack resistance of a regenerated asphalt mixture, in particular to a test technology for quantitatively evaluating the performance of the regenerated asphalt mixture based on a molecular dynamics method, and belongs to the technical field of highway pavement engineering and computer experiments.

Background

At present, the main pavement type of roads in China is an asphalt concrete pavement, which accounts for about 80% of the total mileage of the road pavement in China, wherein about 12% of the asphalt pavements need to be maintained and maintained on a large scale every year, and the generated waste asphalt mixture can reach two million tons.

The regeneration technology of the old asphalt pavement is one of the important means for maintaining the asphalt pavement, can fully utilize waste materials, save asphalt and stone materials, achieve the purposes of saving resource and manufacturing cost and protecting ecological environment by recycling the waste materials, is a green engineering technology, and is widely researched and applied in the world.

In the asphalt pavement regeneration technology, the low-temperature crack resistance of the regenerated asphalt mixture is the hot content of the current international research. The method based on molecular dynamics can establish a bitumen-aggregate interface model from the microcosmic aspect, and is considered as a third scientific means except theoretical analysis and experimental observation in the century, which is called as a 'computer experiment' means. The method is characterized in that classical molecular dynamics theory is used as guidance, molecular dynamics simulation software is used as a platform, the cause of the disease occurrence of the asphalt mixture is microscopically explored, various performances of the asphalt mixture are predicted, and scientific basis can be provided for material selection and development of the asphalt pavement.

By a molecular dynamics method, the micro modeling can be carried out on the recycled asphalt mixture from a molecular angle, a model is endowed with a proper force field by utilizing the classic Newtonian motion mechanics, the micro index which can represent the performance of the recycled asphalt mixture is selected, the low-temperature crack resistance of the recycled asphalt mixture is comprehensively evaluated, and guidance is provided for the further development of the recycled asphalt pavement.

Disclosure of Invention

Aiming at the problems and the defects in the prior art, the invention provides a method for evaluating the low-temperature cracking resistance of a recycled asphalt mixture, which aims to solve the problems in the background technology.

In order to achieve the purpose, the invention provides the following technical scheme, which comprises the following steps:

step 1, constructing a new asphalt amorphous unit cell model, an old asphalt amorphous unit cell model, a regenerant molecular model and a super unit cell model of oxides contained in aggregates based on materials studio software;

step 2, carrying out structural optimization and annealing treatment on the new and old asphalt amorphous unit cell models to obtain new and old asphalt amorphous unit cell models with the minimum system energy;

step 3, carrying out model rationalization verification on the new and old asphalt amorphous unit cell models with the minimum system energy and the super unit cell models of oxides contained in the aggregate;

step 4, establishing a new asphalt-regenerant-old asphalt interface model based on the build layer function, carrying out molecular dynamics simulation after mixing and dissolving to obtain a regenerated asphalt model, and then carrying out shear function simulated shearing to obtain the viscosity of the regenerated asphalt at normal temperature and low temperature;

step 5, establishing a regenerated asphalt-regenerated asphalt interface model and a regenerated asphalt-oxide interface model with equal interface areas based on the build layer function, and calculating to obtain the cohesive energy among the regenerated asphalt at normal temperature and low temperature and the adhesive energy of the regenerated asphalt-aggregate interface;

and 6, weighting and calculating the viscosity, the adhesion energy and the cohesion energy according to the comparison condition of the adhesion energy and the cohesion energy to obtain a low-temperature crack resistance index, and evaluating the low-temperature crack resistance of the regenerated asphalt mixture.

Preferably, the new asphalt model and the old asphalt model in the step 1 comprise four-component and twelve-molecule structures, each molecular monomer is subjected to structure optimization, and the structure is controlled by using the structure function in the amophorus cell according to different molecular proportions, wherein the initial density is 0.1g/cm³The new and old asphalt amorphous unit cell models are assembled in the 3D periodic cube box.

Preferably, the process for constructing the supercell model of the oxide contained in the aggregate in step 1 is as follows, firstly, cells of oxide crystals contained in the aggregate are established, and structural optimization is carried out through geometry optimization in a cast; calculating the most stable and common cracking surface of each crystal by using the BFDH task in morphology calculation; using a clean surface function, carrying out crystal face interception according to the cracking surface, and establishing an oxide unit cell surface model in the aggregate, wherein the thickness is set to be larger than a truncation radius; then using geometry optimization in the castep to carry out structural optimization on the surface model of the oxide unit cell in the aggregate; and adding a vacuum layer on the surface of the aggregate, and constructing a super cell model of the oxide contained in the aggregate by using build supercell function.

Preferably, in the step 2, annealing the new and old asphalt amorphous unit cell models after the structure optimization is completed by using an aneal in a fortite module, wherein the cycle temperature is 300k-800k, the cycle times are 15-20 times, the step length is 1fs, the ensemble is set as NVT, the initial speed is set as random, the thermostat is set as Anderson, and the model with the minimum system energy in the cycle process is output.

Preferably, the model rationalization verification process in the step 3 is as follows, and the solubility and the molecular order degree of the new and old asphalt amorphous unit cell model with the minimum system energy are calculated; the solubility is the square root of cohesive energy density output by the covalent energy density function, and is 15.3-23 (J/cm)³)^0.5The molecular ordering degree is obtained by analyzing an image output by the radial distribution function, the short-range ordering is shown, and the long-range disorder is reasonable; and (3) calculating the supercell model of the oxides contained in the aggregate by using mechanical properties in a fortite module, wherein the calculation method is constant strain, obtaining parameters of the bulk modulus, the Young modulus and the Poisson ratio, comparing the parameters with actual parameters, and verifying the rationality of the oxide supercell model.

Preferably, the construction process of the regenerated asphalt model in the step 4 is as follows, firstly, building an interface model of the new asphalt, the regenerant and the old asphalt by using a build layer function, calculating the number of molecules of the regenerant according to the doping amount, adopting a periodic boundary condition for the interface model, then carrying out dynamic kinetic simulation in a Forcite module, heating to 433k under an NVT (noise, vibration and harshness) ensemble, running for 1000ps under an NPT ensemble after the heating is finished, fully mixing and dissolving, setting the initial speed to random, setting the thermostat to Anderson, setting the barostat to Berendsen, and obtaining the regenerated asphalt model after the kinetic simulation is finished.

Preferably, the first layer of the regenerated asphalt-oxide interface model is the aggregate medium-oxide super cell model, the second layer is the regenerated asphalt model, and the third layer is set by build vacuum slabThe vacuum layer of (1).

Preferably, the calculation method of the cohesion energy between the recycled asphalt in the step 5 includes performing dynamic dynamics simulation in a form module on a recycled asphalt-recycled asphalt interface model, cooling to 263k under an NVT (noise, vibration and harshness) ensemble, performing dynamic balance under an NPT ensemble, and outputting total energy after the calculation is finished, namely total energy E of the system of the recycled asphalt-recycled asphalt interface model_A1A2(ii) a Respectively and independently calculating system energy of the upper and lower regenerated asphalt layers and recording the system energy as E_A1、E_A2And the cohesive energy E between the reclaimed asphalts_adhesion-lowObtained from equation (1):

E_adhesion-low＝E_A1A2-E_A1-E_A2 (1)；

changing the temperature to 300k, and repeating the above operation to obtain the cohesion energy E at normal temperature between the reclaimed asphalt_adhesion-mid。

Preferably, the calculation method of the adhesion energy of the regenerated asphalt-aggregate interface in the step 5 is that dynamic kinetic simulation in a formite module is carried out on all regenerated asphalt-oxide interface models, the ensemble is set to be NVT, the cooling temperature is set to be 263k, the model is cooled after running for 200ps, and then the model is run for 1000ps under the NPT ensemble, so that the total energy E of the interface model is obtained_totalAnd the energy E of the aggregate oxide layer in the equilibrium state is obtained after the regenerated asphalt layer is removed_SRecovering the regenerated asphalt layer, removing the aggregate oxide layer and calculating to obtain the energy E when the regenerated asphalt layer is balanced_ASAdhesion energy of recycled asphalt-oxide interface E_ADFrom equation (2):

E_AD＝E_total-E_S-E_AS (2)；

the adhesion energy of the regenerated asphalt-aggregate interface at low temperature is the sum of the adhesion energy of all oxides in the aggregate and the regenerated asphalt multiplied by the content P of each oxide in the aggregate, and the sum is obtained by the formula (3)

E_AT-low＝E_AD1×P₁+E_AD2×P₂+……+E_ADn×P_n (3)；

Changing the temperature to 300k, and repeating the operation to obtain the adhesion energy E of the regenerated asphalt-aggregate interface at normal temperature_AT-mid。

Preferably, the specific method for evaluating the low-temperature crack resistance of the recycled asphalt mixture in the step 6 is as follows, namely selecting the viscosity V of the recycled asphalt in the recycled asphalt mixture at low temperature_LViscosity V of recycled asphalt at normal temperature_MCohesive energy at low temperature between reclaimed asphalts E_adhesion-lowAnd cohesive energy at normal temperature between reclaimed asphalts E_adhesion-midAdhesion energy at low temperature of recycled asphalt-aggregate interface E_AT-lowAdhesion energy at room temperature of recycled asphalt-aggregate interface E_AT-mid(ii) a Comparison E_adhesion-lowAnd E_AT-lowWhen E is large or small_adhesion-lowGreater than E_AT-lowWhen the asphalt mixture is used, the adhesion of the regenerated asphalt mixture is prone to be damaged, cracks are developed between the regenerated asphalt and aggregate interfaces, and the low-temperature crack resistance index L is obtained by the formula (4)

When E is_adhesion-lowLess than E_AT-lowWhen the asphalt mixture is used, cohesive damage tends to occur to the recycled asphalt mixture, cracks develop among the recycled asphalt, and the low-temperature crack resistance index L is obtained by the formula (5)

Compared with the prior art, the invention has the beneficial effects that:

1. the low-temperature crack resistance of the recycled asphalt mixture is quantitatively evaluated through molecular dynamics simulation based on materials studio software, the accuracy is high, the operation steps are simple, the subjectivity of the traditional experimental method is effectively avoided, and the engineering practice is guided;

2. the method selects viscosity, adhesion energy and cohesion energy to carry out analysis and weighted calculation, considers weak points and cracking positions of the regenerated asphalt mixture at low temperature, provides a new index for evaluating the low-temperature performance of the regenerated mixture, and can evaluate the low-temperature crack resistance of the regenerated asphalt mixture containing different regenerants, aggregates and asphalt by adjusting a model and parameters;

3. in the aspect of selecting the asphalt molecule model, the diversity of asphalt molecules is fully considered, the asphalt molecule model is the asphalt molecule model with the highest precision at present, the calculation result is reliable and accurate, and the anisotropy of crystals is fully considered when the model of oxides in the aggregate is intercepted on a crystal face; on the aspect of the operation sequence and parameter setting of the dynamics simulation, the defects of large system energy, instability, insufficient relaxation and the like of the conventional model are overcome, and the method has better simulation and prediction capabilities.

Drawings

FIG. 1 is a AAA-1 model diagram of the new and old asphalts of the present invention;

FIG. 2 is a schematic representation of a new and old pitch amorphous unit cell of the present invention;

FIG. 3 is a molecular model diagram of a regenerant in example 1 of the present invention;

FIG. 4 shows SiO 2 in example 1 of the present invention₂A schematic diagram of a super cell;

FIG. 5 is a graph of the molecular order of the novel pitch amorphous unit cell of the present invention;

FIG. 6 is a schematic representation of a new asphalt-regenerant-old asphalt interface of the present invention;

FIG. 7 is a simulated view of the shear of reclaimed asphalt shear of the present invention;

FIG. 8 shows a regenerated pitch-silica SiO of the present invention₂And (5) an interface model diagram.

Detailed Description

In order to make the objects and technical solutions of the present invention clearer and easier to understand, the present invention will be described in further detail below with reference to the accompanying drawings and examples. It should be noted that the specific embodiments described herein are only for explaining the present invention and are not used for limiting the present invention. The technical parameters in the specific implementation case are only set reasonably in the case, and any modification of the technical parameters only belongs to the protection scope of the invention.

Example 1

The invention provides a method for evaluating the low-temperature crack resistance of a recycled asphalt mixture, which mainly comprises the following steps:

step 1, establishing a new asphalt amorphous unit cell model, an old asphalt amorphous unit cell model, a regenerant molecular model and a super unit cell model of oxides contained in aggregates based on materials studio software;

step 2, carrying out structural optimization and annealing treatment on the new and old asphalt amorphous unit cell models to obtain new and old asphalt amorphous unit cell models with the minimum system energy;

step 3, carrying out model rationalization verification on the new and old asphalt amorphous unit cell models with the minimum system energy and the super unit cell models of oxides contained in the aggregate;

step 4, establishing a new asphalt-regenerant-old asphalt interface model based on the build layer function, carrying out molecular dynamics simulation after mixing and dissolving to obtain a regenerated asphalt model, and then carrying out shear function simulated shearing to obtain the viscosity of the regenerated asphalt at normal temperature and low temperature;

step 5, establishing a regenerated asphalt-regenerated asphalt interface model and a regenerated asphalt-oxide interface model with equal interface areas based on the build layer function, and calculating to obtain the cohesive energy among the regenerated asphalt at normal temperature and low temperature and the adhesive energy of the regenerated asphalt-aggregate interface;

and 6, weighting and calculating the viscosity, the adhesion energy and the cohesion energy according to the comparison condition of the adhesion energy and the cohesion energy to obtain a low-temperature crack resistance index, and evaluating the low-temperature crack resistance of the regenerated asphalt mixture.

The formula referred to in the examples is as follows:

equation 1: e_adhesion-low＝E_A1A2-E_A1-E_A2；

Equation 2: e_AD＝E_total-E_S-E_AS；

Equation 3: e_AT-low＝E_AD1×P₁+E_AD2×P₂+……+E_ADn×P_n；

Equation 4:

equation 5:

the specific implementation steps are as follows:

the new and old asphalt models are AAA-1 models proposed by SHRP (American Highway strategic research plan), which comprise four-component and twelve-molecular structures, and adopt the content of each component of domestic common No. 70 asphalt as a prototype to establish an asphalt binder unit cell model, and adopt the content of the main mineral component of common basalt to establish an aggregate unit cell model.

The first step is as follows: new and old asphalt amorphous unit cell models are constructed by using amorporus cell function in materials studio software.

Respectively optimizing each molecular structure according to the four-component content of the 70# asphalt and the four-component content of the 70# asphalt after being aged for 5 years, and then utilizing the construction function of the amophorus cell in materials studio software according to different molecular proportions and the initial density of the amophorus cell is 0.1g/cm³Assembling in a cubic box to obtain new and old asphalt amorphous unit cell models. The contents of the components are shown in the following table 1, the molecular models of the new asphalt and the old asphalt are shown in figure 1, and the amorphous unit cells of the new asphalt and the old asphalt are shown in figure 2. Meanwhile, a regenerant molecular model is established, the regenerant molecular model is selected to be a single-component model with representative properties, the calculation of mixture mixing and dynamics can be simulated, the regenerant rich in aromatic is adopted in the embodiment, the single structure is adopted to represent the properties of the regenerant, and the chemical formula is C shown in figure 3₁₂H₁₆The molecular weight is 12, and the mixing amount is 4% of the mass of the old asphalt.

TABLE 1 asphalt model

The second step is that: the build crystal and build supercell functions were used in materials studio software to build supercell models of common oxides in aggregate.

Taking basalt aggregate as an example, firstly establishing crystal cells of oxides contained in the basalt aggregate, namely SiO₂(silica) and Al₂O₃(alumina), CaO (calcium oxide), Fe₂O₃(iron oxide), structural optimization by means of geometry optimization in castep; the most stable and common cracking surface of each crystal is calculated by using BFDH task in morphology calculation, meanwhile, the Miller coefficient when the crystal surface is intercepted by different oxides is obtained, and SiO is used₂Calculating to obtain the most stable cracking surface as { 10-1 } for example; using a clean surface function, intercepting a crystal face according to a cracked surface to establish an oxide unit cell surface model in the aggregate, wherein the thickness is set to be larger than a truncation radius, and the thickness is set to be larger than a truncation radiusAnd the cutoff radius is generallyThen using geometry optimization in the castep to carry out structure optimization on the surface model of the oxide unit cell in the aggregate; then, a vacuum layer is added on the surface of the material, and a built supercell function is used for constructing a supercell model of oxides contained in the aggregate, taking silicon dioxide as an example, as shown in figure 4.

The third step: the geometry optimization and the annual function are used in materials studio software to carry out the structure optimization and annealing treatment on the new and old asphalt amorphous unit cell model.

Performing structure optimization on new and old asphalt amorphous unit cells by means of geometry optimization in a fortite module, wherein smart is adopted as an algorithm, and a force field is COMPASS II; and (3) annealing the asphalt amorphous unit cell after the structure optimization is finished by using the aneal in the fortite module, wherein the circulating temperature is 300k-800k, the circulating times are 15-20 times, the step length is 1fs, the ensemble is set as NVT, the initial speed is set as random, the thermostat is set as Anderson, and the model with the minimum system energy in the circulating process is output.

The fourth step: and (4) carrying out model rationalization verification on the model obtained in the second step and the third step by using a Forcite function and an analysis function in a cast.

Calculating the solubility and the molecular order of the new and old asphalt amorphous unit cell models with the minimum system energy, wherein the solubility is the square root of cohesive energy density output by a covalent energy density function, and the solubility is 15.3-23 (J/cm)³)^0.5(ii) a The molecular order is obtained by analyzing the image output by the radial distribution function, and the short-range order is shown, and the long-range disorder is reasonable, as shown in fig. 5; and (3) calculating the supercell model of the oxides contained in the aggregate by using mechanical properties in a fortite module, wherein the calculation method is constant strain, obtaining parameters of the bulk modulus, the Young modulus and the Poisson ratio, comparing with actual parameters, and verifying the rationality of the oxide supercell model.

The fifth step: and (3) constructing a regenerated asphalt model by using dynamic kinetic simulation in a fortite module.

As shown in fig. 6, firstly, building an interface model of new asphalt, a regenerant and old asphalt by using a build layer function, wherein the number of molecules of the regenerant is 12 according to the doping amount, the ensemble is set to be NPT at first during dynamic kinetic simulation, the temperature is set at 433k according to the practical experience of thermal regeneration engineering, the running time is 1200ps, the step length is 1fs, the initial speed is set to random, the thermostat is set to Anderson, the barostat is set to be berendan, and then the dynamic kinetic simulation in a fortite module is finished to obtain a regenerated asphalt model; and then shearing is simulated through the shear function to obtain the viscosity of the recycled asphalt at low temperature and normal temperature, as shown in figure 7.

And a sixth step: and calculating the adhesion energy between the regenerated asphalt and the adhesion energy between the regenerated asphalt and the aggregate interface.

Firstly, building a regenerated asphalt-regenerated asphalt interface model and a regenerated asphalt-oxide interface model by using build layer functionThe first layer is an aggregate medium oxide super-cell model, the second layer is a regenerated asphalt model, and the third layer is arranged by build vacuum slabThe interface areas of all the interface models are equal, and the influence of periodicity is eliminated; taking the regenerated pitch-silica interface model as an example, it is shown in fig. 8.

Dynamically balancing the regenerated asphalt-regenerated asphalt interface model under NPT ensemble at 263k and 300k respectively, and outputting total energy after operation, namely total energy E of the system of the regenerated asphalt-regenerated asphalt interface model_A1A2Respectively and independently calculating the system energy of the upper and lower regenerated asphalt layers and recording the system energy as E_A1、E_A2Calculating the cohesive energy E at low temperature by using the formula (1)_adhesion-lowAnd cohesive energy at ordinary temperature E_adhesion-mid。

Performing dynamic kinetic simulation in a Forcite module on all regenerated asphalt-oxide interface models, setting the ensemble to be NVT, setting the cooling temperature to be 263k, running for 200ps, cooling the models, and running for 1000ps under the NPT ensemble to obtain the total energy E of the interface models_totalAnd removing the regenerated asphalt layer to calculate the energy E of the aggregate oxide in the equilibrium state_SRecovering the regenerated asphalt layer, removing the aggregate oxide layer to obtain the energy EAs when the regenerated asphalt layer is balanced, and calculating the adhesion energy E of the regenerated asphalt-oxide interface by using the formula (2)_ADThen, the adhesion energy E of the regenerated asphalt-aggregate interface at low temperature is obtained from the formula (3)_AT-low. Changing the temperature to 300k, and repeating the above operation to obtain the adhesion energy E of the regenerated asphalt-aggregate interface at normal temperature_AT-mid。

The seventh step: and calculating a low-temperature crack resistance index L and evaluating the low-temperature crack resistance of the regenerated asphalt mixture.

Selecting related parameters, specifically viscosity V of recycled asphalt in recycled asphalt mixture at low temperature_LViscosity V of recycled asphalt at normal temperature_MCohesion at low temperature between reclaimed asphaltsEnergy E_adhesion-lowAnd cohesive energy at normal temperature between reclaimed asphalts E_adhesion-midAdhesion energy at low temperature of recycled asphalt-aggregate interface E_AT-lowAdhesion energy at room temperature of recycled asphalt-aggregate interface E_AT-mid。

If the viscosity V of the recycled asphalt at low temperature_LWhen the glass transition temperature becomes large, the deformability becomes poor, and the glass transition temperature becomes hard and brittle.

Comparison E_adhesion-lowAnd E_AT-lowWhen E is large or small_adhesion-lowGreater than E_AT-lowIn the process, the regenerated asphalt mixture tends to generate adhesive damage, namely the adhesion degree of an asphalt-aggregate interface is weak under a low-temperature condition, cracks are mostly developed on the asphalt-aggregate interface, no asphalt residue is left on the aggregate surface after cracking, and the low-temperature crack resistance index L is calculated according to a formula (4).

When E is_adhesion-lowLess than E_AT-lowIn the process, the recycled asphalt mixture tends to generate cohesive failure, the cohesiveness among asphalts is poor under the low-temperature condition, more cracks are developed among the asphalts, asphalt residues are left on the aggregate surface after cracking, and the low-temperature crack resistance index L is calculated according to the formula (5).

Evaluation standard of low-temperature crack resistance index L: the low-temperature crack resistance is good when L is more than or equal to 0.7 and less than 1, the low-temperature crack resistance is medium when L is more than or equal to 0.4 and less than 0.7, and the low-temperature crack resistance is poor when L is less than 0.4.

The technical principles of the present invention have been described above in connection with specific embodiments, which are intended to explain the principles of the present invention and should not be construed as limiting the scope of the present invention in any way. Based on the explanation here, those skilled in the art can conceive of other embodiments of the present invention without any creative effort, such as changing the model types of the recycling agent and the aggregate, adjusting the ratio of the four components of the asphalt model, or adding a modifier, etc., and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.