Effect of Flat and Elongated Aggregate on Stone Matrix Asphalt Performance

The importance of this study is driven by asphalt mixture economics since the in‐place cost of stone matrix asphalt (SMA) mixtures is up to 80% higher than conventional dense‐graded mixes. The production of SMA aggregate alone is believed to cost approximately twice that of conventional aggregate production. Therefore, it is essential to determine whether the need for such high quality aggregate products is necessary for satisfactory SMA performance. European specifications were adopted in AASHTO M325 and typically require SMA aggregates to have no more than 30 percent Los Angeles abrasion loss and no more than 20 percent flat and elongated (F&E) particles when measured at a 3:1 ratio of length to maximum thickness. However, these strict aggregate requirements were developed for use in Europe, where studded tires are used for winter travel, and may not be necessary for other countries. The objective of this study was to evaluate the performance of SMA mixes designed with different percentages of F&E aggregate to determine how critical this aggregate property is. Quarries that produce both SMA and non‐SMA stone and two quarries that do not produce SMA stone (due to high F&E values) were evaluated. The study concludes that there is generally no significant adverse effect on performance from using high F&E aggregate if that aggregate has low abrasion loss values. A recommendation is made to use the same F&E requirements for SMA mixes as is used for Superpave mixes.


  • English

Media Info

  • Media Type: Digital/other
  • Features: Figures; References; Tables;
  • Pagination: 19p

Subject/Index Terms

Filing Info

  • Accession Number: 01635101
  • Record Type: Publication
  • Report/Paper Numbers: NCAT Report 17-03
  • Files: TRIS
  • Created Date: May 22 2017 5:06PM