Evaluation of Open-Graded Friction Course (OGFC) Mix Design: Summary Version

This study evaluates the open-graded friction course (OGFC) mix design proposed by the National Center for Asphalt Technology (NCAT) in order to suggest revisions to California Test 368, Standard Method for Determining Optimum Binder Content (OBC) for Open-Graded Asphalt Concrete. Three asphalt types, three aggregate types, and three gradations were used. The NCAT approach includes selection of optimum gradation, selection of optimum asphalt binder content, and evaluation of moisture susceptibility using a modified Lottman method in accordance with AASHTO T 283 with one freeze-thaw cycle. It was found that, regardless of binder and aggregate types, the optimum gradation selected per the NCAT approach did not guarantee the success of an OGFC mix design. None of the mixes with coarse gradation simultaneously met the criteria for percent air-void content, draindown, and Cantabro loss. Binder type is the most significant factor affecting both draindown performance and Cantabro performance. This study proposes a volumetric-based OGFC mix design (1) to provide a better way to determine the initial binder content rather than basing it on the bulk specific gravity of the aggregate blend as suggested by NCAT; (2) to account for asphalt absorption; and (3) to allow direct selection of trial binder contents to prepare specimens for performance testing.


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  • Accession Number: 01533074
  • Record Type: Publication
  • Source Agency: UC Berkeley Transportation Library
  • Report/Paper Numbers: UCPRC-SR-2013-02, CA13-1874A
  • Contract Numbers: CA141874A
  • Created Date: Jul 17 2014 7:18PM