Disruption factor of asphalt mixtures

Typically, aggregate gradation is selected to meet Superpave mix design specification; however, many Superpave mixtures have exhibited deficient field performance. The porosity of the dominant aggregate size range (DASR), which is the primary structural network of aggregates, has been extensively validated as a tool to evaluate coarse aggregate structure of laboratory and field asphalt mixtures. Mixtures identified by the system as having poor or marginal gradations resulted in poor rutting resistance. This study focused on how asphalt mixture performance is affected by changes in interstitial component (IC), which is the material between DASR particles. Laboratory testing clearly showed that IC characteristics may have a significant effect on rutting and cracking performance of mixtures. The disruption factor (DF) was developed to evaluate the potential of IC aggregates to disrupt the DASR structure. DF satisfactorily distinguished poor performing mixtures; therefore, it may eventually be used in combination with DASR porosity as a design parameter for rutting and cracking resistant asphalt mixtures.