||Optimized Mix Design Procedure for Superpave Surface Mixes
Michael M. Sprinkel
Associate Director for Structures
Since the adoption of Superpave, asphalt surface mixes may be deficient in asphalt cement, according to observations throughout both Virginia and the nation. Several studies have also revealed that additional asphalt may increase the endurance, or service life, of surface mixes. A VCTIR research advisory committee has requested a study to investigate how to improve the state’s current design of asphalt surface mixes.
This project will investigate VDOT’s surface-mix design methods to improve durability, primarily by increasing binder content, thus adding surface life. It will be primarily a laboratory study, focusing on the widely used 9.5 mm surface mix. Rut tests and conventional gyratory volumetric properties will determine the maximum amount of asphalt cement that can be safely added to the current mixes. It is estimated that increasing the service life by only 10 percent could yield an annual savings to VDOT of $25 million.