This paper assesses the significance and contribution of particle orientation in dense-graded mixtures. Measurements were made graphically from photographs made of thin strips cut from a block taken from a pavement during an investigation of traffic compaction in dense-graded mixtures. Coordinate measurements of the end points of each particle were recorded. Orientation was the direction of the longest dimension on the projection. The data were subjected to the Tukey chi-square statistical analysis in groups by particle length, depth, and region and in toto for each sample. The measurements showed that approximately 30 percent of the particles were oriented at angles within 10 deg of the preferred orientation and that the preferred orientation was generally in the range 4 to 8 deg above the horizontal in the direction of trafficking. Small changes were apparent under the compacting effect of simulated traffic but these were barely significant statistically. Low viscosity and high binder content appeared to promote preferential orientation but, again, the differences were not statistically significant. Particle size had negligible influence. The structural properties of a mix are very sensitive to orientation characteristics. Reorientation appears to be a function primarily of viscous resistance in the binder; changes in packing density are more a function of aggregate characteristics.

Media Info

  • Media Type: Print
  • Features: Figures; References;
  • Pagination: pp 151-156
  • Monograph Title: Characteristics of and factors influencing bituminous materials and mixtures
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00095577
  • Record Type: Publication
  • ISBN: 0309023599
  • Report/Paper Numbers: #517
  • Files: TRIS, TRB
  • Created Date: Jul 2 1975 12:00AM