Design and Construction of a New Asphalt Drainage Layer

Report No: 05-R11

Published in 2004

About the report:

Because of the importance of having a good drainage mechanism built into a pavement structure to prevent premature failure, the Virginia Department of Transportation (VDOT) has used drainage layers under both portland cement concrete and asphalt concrete since the early 1990s. Unfortunately, these mixes have been rather difficult to place and durability has been a possible issue of concern. The purpose of this study was to design an improved asphalt drainage layer for one of the VDOT districts that eliminated the deficiencies of previous drainage layers. A 50-50 blend of No. 68 and No. 8 aggregates was chosen based on laboratory testing, and the mix was installed in a newly constructed flexible pavement with good results. The mix was easy to place and contained thick asphalt films that should contribute to a long service life. Based upon this success, a specification was drafted, and the mix was used in an additional project in the fall of 2003.

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: November 28, 2023

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