Modeling Shear Viscosity of Asphalt through Nonequilibrium Molecular Dynamics Simulation

Abstract

This paper investigates a quantifiable relationship between the chemical composition and the shear viscosity of the asphalt binder through the nonequilibrium molecular dynamics (NEMD) simulation. The fix Deform and fix NVT/SLLOD ensembles were used to perform a shear effect on the model. The relationship between the shear viscosity and the microstructure characteristics of the asphalt model was studied. The results indicated that the asphalt model exhibited shear thinning as the strain rate increases. The effects of energy and chemical structure (molecular weight, aromatic carbon and heteroatom percentage) on shear viscosity were studied from the perspective of microstructure. The results showed that the larger fused aromatic ring core caused a nonlinear relationship between viscosity and strain rate. The viscosity of the asphalt model increased with the molecular weight, the percentage of aromatic carbon and heteroatoms. The molecular weight had a greater effect on viscosity than aromatic carbon and heteroatom percentage. Considering energy variations with strain rate and chemical structure, the NEMD method can be used to predict the behavior of the asphalt molecules under shear strain at a certain level.