Examination of an Implemented Asphalt Permeability Specification

About the report:

Much research had been conducted and reported regarding the permeability of asphalt mixtures in Virginia. Because of the susceptibility of many mixtures to the entrance of water, a new permeability specification for approval of asphalt job mixtures was implemented by the Virginia Department of Transportation (VDOT) in 2005 in an attempt to eliminate permeable mixtures. A testing program was conducted during the year of implementation to examine the effectiveness of the new specification, and those results are reported herein.

The purpose of the study was to determine if the contractors had to change the mixture designs so that the mixture would comply with the new permeability requirement and whether the specification produced pavements with acceptable permeability. Contractors were asked to indicate voluntarily whether mixture designs had to be redesigned because of permeability issues. In addition, each district materials engineer in the nine VDOT districts was asked to sample and test at least two surface mixtures to determine the level of permeability being achieved in the pavement.

Some mixtures had to be redesigned in 2005 to comply with the new specification. Generally, pavements that had been designed in accordance with the new specification and complied with density specifications had satisfactory permeability. The new specification appears to be performing as intended, and no changes are needed. As a consequence, the results of this research were implemented.

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