Comparison of Several Asphalt Design Methods

Report No: 98-R15

Published in 1998

About the report:

This laboratory study compared several methods of selecting the optimum asphalt content of surface mixes. Six surface mixes were tested using the 50-blow Marshall design, the 75-blow Marshall design, two brands of SHRP gyratory compactors, and the U.S. Army Corps of Engineers' gyratory testing machine (GTM) with the oil-filled and the air-filled rollers. The Georgia loaded wheel tester (GLWT) was also used in an attempt to define the maximum allowable asphalt content. The GTM with the air-filled roller and the 75-blow Marshall design produced the largest differences in optimum asphalt content. The two SHRP gyratory compactors gave comparable contents. The lack of rutting with the GLWT at a high asphalt content prevented determining the maximum allowable asphalt content and fulfilling the primary purpose of the study. However, other findings were of interest.

Disclaimer Statement:The contents of this report reflect the views of the author(s), who is responsible for the facts and the accuracy of the data presented herein. The contents do not necessarily reflect the official views or policies of the Virginia Department of Transportation, the Commonwealth Transportation Board, or the Federal Highway Administration. This report does not constitute a standard, specification, or regulation. Any inclusion of manufacturer names, trade names, or trademarks is for identification purposes only and is not to be considered an endorsement.


  • G. W. Maupin, Jr., P.E.

Last updated: December 15, 2023

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