⁠Effect of filler on thermodynamic and mechanical behaviour of asphalt mastic: a MD simulation study

To fully understand the filler reinforcement mechanism in asphalt mastic, molecular dynamic (MD) simulation was adopted to explore the effect of mineral filler on the structural, thermodynamic and mechanical properties of asphalt mastic. An asphalt/silica nanoparticle composite system that consisted of silica nanoparticles and a 12-components combined asphalt model was generated to represent asphalt mastic. The asphalt molecular model was validated in terms of thermodynamic properties such as density, glass transition temperature (T_g) and cohesive energy density (CED). The structural properties, in the form of free volume and radial distribution function (RDF) of asphalt mastic were calculated. Thermodynamic properties including density, T_g and CED of asphalt mastic were further investigated. Mechanical properties such as Young’s, bulk and shear moduli were also estimated. Results show that the addition of silica particles to neat asphalt binder decreased the interaction between asphalt molecules and increased free volumes in the configuration. T_g decreased as the increasing concentration of the silica particle. Furthermore, the effects of the filler particle size and concentration on the thermodynamic and mechanical properties of asphalt mastic were discussed. This fundamental level simulation results reported here provide a platform for potentially accounting for the effect of fillers on the properties of asphalt mastic.