Journal Published Online: 10 November 2008
Volume 37, Issue 1

Determination of Volumetric Properties for Permeable Friction Course Mixtures



Current hot mix asphalt (HMA) mix design procedures used to determine the optimum asphalt content (OAC) for permeable or porous friction course (PFC) mixtures are based on volumetric properties, primarily total air void (AV) content. This calculated volumetric parameter depends on the bulk specific gravity (Gmb) and the theoretical maximum specific gravity (Gmm) of the mixture, which are generally difficult to measure in a laboratory due to the high asphalt contents, high total AV contents, and the use of modified asphalts for PFC mixtures. This study evaluated two methodologies for determining Gmb (vacuum and dimensional analysis) and two methodologies for determining Gmm (measured and calculated) for use in calculations of total AV content. For the mixtures assessed in this study, originally designed with a total AV content of 20 %, the alternative methodologies studied led to total AV content values outside the design range (18 to 22 %), which implies the necessity of gradation modifications or changes in the fiber content to meet AV requirements and define an OAC. Dimensional analysis and a calculation procedure, based on values of Gmm measured in the laboratory at low asphalt contents, are recommended for determining Gmb and Gmm values, respectively. In addition, dimensional analysis is preliminarily recommended to compute the water-accessible AV content of PFC mixtures based on the assessment of two methods (vacuum and a methodology proposed for dimensional analysis) to compute this parameter. Water-accessible AV content is considered as an alternative parameter for mix design and evaluation.

Author Information

Alvarez, Allex
University of Magdalena
Martin, Amy
Zachry Department of Civil Engineering, Texas A&M University
Estakhri, Cindy
Texas Transportation Institute
Izzo, Richard
Texas Department of Transportation
Pages: 10
Price: $25.00
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Stock #: JTE101696
ISSN: 0090-3973
DOI: 10.1520/JTE101696