Development of Mix Design Approach for Mixtures with Reclaimed Asphalt Pavement, RAP, Materials

The high demand for using recycled materials in roadways for sustainability has generated the need to develop new approaches to mix design in order to address and incorporate performance measures. In this regard, the mix design approach should identify methods to assess mixture performance, incorporating, for example, permanent deformation and fatigue cracking, to otherwise limiting volumetric analysis, as identified by the current Superpave approach used by many states. The objectives of this study were to develop such a methodology and identify threshold values for permanent deformation and fatigue cracking for the most common mixtures used in the state of Maryland. The performance testing results for fatigue cracking and permanent deformation are presented herein. Based on these results, initial threshold values were adopted. Furthermore, the experimentation included three distinct populations: plant mixtures; modified plant mixtures; and field mixtures (i.e., behind the paver). The results are presented herein along with relevant considerations about their potential use within quality assurance. The asphalt mixtures included in this study represent common or similar materials and mixtures often used in the northeast region. Thus, the suggested approach and overall testing results may be transferable elsewhere where similar materials and asphalt mixtures are used.