Analyzing Properties of Model Asphalts Using Molecular Simulation

Molecular simulations have been used to estimate the properties of three-component mixtures whose constituents were chosen to represent the chemical families found in paving asphalts. Naphthene aromatics and saturates were represented by 1,7-dimethylnaphthalene and n-C22, respectively. Two different asphaltene model structures were considered. The first has a large aromatic core with a few short side chains; the second contains a moderate size aromatic core with larger branches. Both types have been proposed in the recent literature based on experimental characterizations of asphaltene fractions. Properties calculated from atomistic molecular simulations of the mixtures include density, isothermal compressibility (inverse of bulk modulus), and zero shear viscosity. The thermodynamic properties suggest a high frequency glass transition above 25ºC for both model mixtures. The mixture based on the more aromatic asphaltene shows a more pronounced transition and has a higher bulk modulus. The calculated viscosity at elevated temperatures is somewhat smaller than that of real asphalts. For a polymer-modified model asphalt, the calculations are consistent with increases in viscosity and bulk modulus.

Language

  • English

Media Info

  • Media Type: CD-ROM
  • Features: Figures; References; Tables;
  • Pagination: 15p
  • Monograph Title: TRB 86th Annual Meeting Compendium of Papers CD-ROM

Subject/Index Terms

Filing Info

  • Accession Number: 01044208
  • Record Type: Publication
  • Report/Paper Numbers: 07-2841
  • Files: TRIS, TRB
  • Created Date: Feb 8 2007 7:32PM