Correlation among Molecule Relaxations In Multicomponent Asphalt Models

Selection of asphalts for paving applications are guided by temperature dependence of changes in complex moduus. Multicompoent models of asphalt systems have been simulated using molecular dynamics in order to quantify the orientational and configurational relaxation of individual molecules and to relate changes in relaxation rate to changes in stress fluctuations, stress correlations, and free volume. The latter was quantified using the volume calculated to be accessible to a nanoscale hard sphere probe in configurations extracted from the simulations. Decreases in accessible volume showed good correlations with increases in relaxation time, consistent with trends predicted by free volume models of viscosity, such as the Doolittle equation.