A four phase micro-mechanical model for asphalt mastic modulus

B. Shane Underwood, Y. Richard Kim

Research output: Contribution to journalArticlepeer-review

61 Scopus citations


In this paper, existing formulations for predicting the stiffening effects of graded aggregate particles at moderate and high concentrations in a viscoelastic matrix (asphalt) are evaluated. These functions encompass dilute, micro-mechanical, and phenomenological solutions, but each is found to produce qualitatively and quantitatively unsatisfactory results at all particle concentrations. These shortcomings are hypothesized result from the inability of these models to consider a third phase of the composite, a physico-chemically influenced layer at the aggregate surface. A model to account for this layer is developed and applied to predict the stiffening of asphalt mastics across a range of volumetric concentrations. The model is found to predict the stiffening responses at moderate concentrations well, but under predicts the responses at the highest concentrations. At these concentrations, particulate contact and internal structure development occurs and provides an additional stiffening mechanism that the four phase model does not account for. The under predictions at these higher concentrations are thus expected and rational.

Original languageEnglish (US)
Pages (from-to)13-33
Number of pages21
JournalMechanics of Materials
StatePublished - Aug 2014


  • Analytical modeling
  • Asphalt mastic
  • Micro-mechanics
  • Physico-chemical interaction
  • Rheological properties

ASJC Scopus subject areas

  • Instrumentation
  • General Materials Science
  • Mechanics of Materials


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