Innovative evaluation of recycled asphalt pavement (rap) use in slurry seal applications

Slurry seal is a surface treatment method that is used to extend the life of asphalt pavements. By sealing the surface from environmental effects (e.g., water penetration and ultraviolet light etc.), slurry seal retards aging (embrittlement) and prevents raveling. Slurry seal is a mixture of Aggregate/Reclaimed Asphalt Pavement (RAP), Asphalt Emulsion and Mineral fillers. To evaluate the potential performance of a slurry seal mixture, multiple traditional tests are conducted, such as Mix Time Test, Cohesion Test, Consistency Test, Wet Stripping Test, Wet Track Abrasion Test (WTAT), Sand Adhesion Test and Classification Compatibility Test. These tests are typically run to determine a slurry seal mixture formula (mixture design). In this study, a comprehensive experimental program was undertaken to compare the performances of slurry seal mixtures made with 100% RAP (Recycled Asphalt Pavement) and virgin (VG) aggregates. The tests included traditional tests such as residual binder content, mix time, cohesion, consistency, wet-abrasion, wet-stripping, integrity/compatibility tests. In addition, two new testing protocols were introduced to assess the abrasion, raveling and rutting resistance of the slurry seal mixtures using the Hamburg Wheel Tracking (HWT) device. It was observed that the slurry seals made with 100% RAP generally performed as good as or better than the slurry seals made with virgin aggregates.