Study On Temperature Sensitivity Of Road Asphalt Based On Molecular Simulation Technology

In the past 40 years of reforming and opening up,China's highway development has made great achievements.But the problem of temperature sensitivity of road asphalt has not been fundamentally solved.As the core index of asphalt performance,temperature sensitivity affects the macroscopic function of asphalt pavement in the high and low temperature sections.Asphalt contributes a lot to road ruts.If asphalt is sensitive to temperature in the high temperature section,the rutting of the asphalt will increase.The asphalt low temperature crack resistance is the main influencing factor of low temperature performance of asphalt pavement.Asphalt's sensitivity to temperature in the low temperature section will accelerate the brittle cracking of the asphalt and cause cracking of the pavement.Therefore,asphalt temperature sensitivity research is of great significance to improve pavement performance and service time.Through the combination of simulation,experiment and theory,this paper explores the relationship between the microscopic properties of asphalt temperature sensitivity and macroscopic performance,and attempts to obtain the microscopic influence mechanism of asphalt temperature sensitivity and the correlation between micro-macroscopic variables,to provide a certain direction and basis for the future research of asphalt temperature sensitivity.The paper select Panjin 90# asphalt,CNOOC 90# asphalt,Panjin 90#SBS modified asphalt,CNOOC 90#SBS modified asphalt,Panjin 90# asphalt after long-term aging and CNOOC 90# asphalt after long-term aging as the samples of study.Asphalt molecular model was constructed using a four-component assembly method.Molecular dynamics simulations of 200 ps were performed using Materials Studio software to observe the microscopic properties.The rationality and balance of the molecular model are judged by calculating the molecular density,solubility parameters and mean square displacement of the asphalt.The structural parameters of asphalt molecules were calculated using the E-d-m method.The performance of asphalt high temperature performance at the microscopic level was studied by calculation of cohesive energy density.The performance of asphalt low temperature performance at the microscopic level was studied by calculation of glass transition temperature.The rationality of estimating the glass transition temperature using the solubility parameter was verified.The overall radial distribution function map is used to study the structural state of asphalt molecules.The microscopic aggregation state of the representative atoms is explored using a radial distribution function of the atomic benzene ring carbon as the representing atom.Basic performance tests on six asphalt samples were conducted to capture their overall performance.Dynamic shear rheological tests and low-temperature bending beam creep tests were carried out on six kinds of asphalt samples to determine their complex modulus,phase angle,rutting factor,bending creep modulus and creep rate m to evaluate the high and low temperature performance.The slope of the complex modulus and temperature double logarithmic regression line is used as an index to evaluate the temperature sensitivity of asphalt.The slope of the bending creep modulus and temperature double logarithmic regression line were used as indicators to evaluate the temperature sensitivity of asphalt at low temperature.The correlation between the microstructure parameters of asphalt and the temperature sensitivity of high and low temperature asphalt was analyzed by grey correlation.The regression equation of asphalt structural parameters and high and low temperature sensitivity of asphalt was obtained by multiple linear regression analysis.The influence mechanism of microscopic parameters affecting asphalt temperature sensitivity was deduced.