Use of Distortion Energy as Fundamental Design Parameter for Predicting Asphalt Fatigue Damage

The elastic distortion energy (ED) is one of the magnitudes that provide information on any continuum mechanical state. It consists in the part of the total deformation energy that produces a change in shape for constant volume, and depends on the relative differences between principal stresses. This paper explores the use of this variable as a fundamental parameter for asphalt fatigue. In the first place, bending fatigue tests are compared to indirect-tension tests from the mechanical point of view, and the laboratory results for a particular asphalt concrete mix are presented. A significant part of the experimentally contrasted differences between the results from the two fatigue tests can be explained by ED. ED also provides an explanation for the asphalt performance that can be observed in thick pavements and, in particular, for top-down cracking. Modeling shows that a critical situation exists for the asphalt mix at the top (up to 100 mm in depth) of a thick (350 mm) pavement, since the level of elastic distortion energy is considerably higher than at the bottom. Several issues are presented in this paper that support the possibility of asphalt fatigue being governed by actual differences between principal stresses (or strains), rather than the principal stresses (or strains) themselves, thus introducing a new approach to asphalt fatigue, which has been traditionally assumed to be caused only by tensile strains. Finally, the asphalt mechanical state is evaluated at several depths into a thick (350 mm) asphalt pavement and the results are presented by Mohr’s circles. Conclusions are extracted from the comparison of such mechanical states with those induced during bending and indirect-tension fatigue tests.

Language

  • English

Media Info

  • Media Type: DVD
  • Features: Figures; References; Tables;
  • Pagination: 18p
  • Monograph Title: TRB 89th Annual Meeting Compendium of Papers DVD

Subject/Index Terms

Filing Info

  • Accession Number: 01154905
  • Record Type: Publication
  • Report/Paper Numbers: 10-0695
  • Files: TRIS, TRB
  • Created Date: Jan 25 2010 10:20AM