Strength Generation Mechanism And Road Performance Optimization Of Cold-mixed Asphalt Based On Molecular Simulation

Technology of cold-mixed asphalt mixture enable us to pave asphalt pavement at normal temperature and low temperature.Compared with hot-mixed asphalt mixture,it can reduce construction costs,reduce harmful substance emissions and improve operating efficiency,and this is an important way to achieve “green-road”construction.However,at present,there is not much research on cold-mixed asphalt mixtures,especially very little research on solvent-based cold-mixed asphalt on the micro level,which leads to weak links in design,mixing and paving.Therefore,it is of great significance to understand the strength formation mechanism of solvent-based cold-mixed asphalt from a molecular perspective.First,the empirical method was used to complete the mix ratio design of the solventbased cold-mixed asphalt mixture.Through the age experiments at different curing times and different curing temperatures,it was found that the strength formation of the solventbased cold-mixed asphalt mixture is directly related to the curing time and curing temperature.Then,the macroscopic properties of cold-mixed asphalt with different diesel diluent contents,such as nano-hardness,nano-modulus,phase transition temperature are also calculated from a micro-angle,so the effect of diluent residue on the properties of asphalt was explored;then the asphalt-aggregate interface model was established to study the effect of diesel diluent on the interface binding energy and water loss resistance.The diffusion coefficient of the diesel diluent at different temperatures is also calculated.Combining previous conclusions,the strength formation mechanism of solvent-based cold-mixed asphalt and the factors that influence strength is explained.At the same time,the viscosity-reducing effect was explained by using microscopic features such as radial distribution function,diffusion coefficient,and angular distribution of orientation within the asphaltene molecules.In order to solve the strength and performance defects of cold-mixed asphalt in experiments and simulations,the resin modification method was used to optimize the materials.First,based on the first principles of quantum mechanics,different resins and hardener materials were screened.Then,a molecular dynamics method was used to establish a modified model of the material,which was compared with the unmodified material model.Calculations show that resin modification can increase the density of cold-mixed asphalt,greatly improve the surface binding energy of cold-mixed asphalt and aggregate,reduce the water sensitivity of the interface,and restore the hardness and modulus to the state when no diesel diluent was added.Finally,by performing molecular dynamics simulation of stretching on the modified system,its strength generation mechanism was discussed.