Interstitial component characteristics and its effect on mixture properties

Although aggregate gradation is known to have a dominant effect on asphalt mixture cracking performance, existing design criteria and guidelines provide very general restrictions. The Dominant Aggregate Size Range and Interstitial Component DASR-IC model is able to effectively introduce the effects of gradation on mixture properties. A set of performance related parameters and associated criteria have been developed based on analysis of the aggregates in the DASR-IC. These parameters include DASR porosity, disruption factor (DF), effective film thickness (EFT), and fine aggregate ratio (FAR). The DASR which relates to rutting performance and its associated parameters, DASR porosity and DF have been sufficiently characterized. There was need to fully characterize the effect of IC on mixture cracking properties and performance. This study focused on evaluating the effects of void structure and binder distribution on mixture properties as well as changes in mixture properties due to oxidation and moisture. In addition the study determined how SBS polymer modification affects mixture sensitivity to changes in IC as well as its effect on mixture properties and performance.;It was found that changes in void structure and binder distribution resulting from changes in IC gradation have an effect on mixture properties as well as changes in properties due to oxidation and moisture. The study concluded that the effective film thickness, EFT is a valid parameter to be used as a guideline and its implementation would help to ensure consistently enhanced cracking performance. The existing criteria of EFT (12.5 to 25 microns) is strongly recommended. Additionally, the study concluded that to ensure improved cracking performance for granite mixtures, the use of an SBS polymer modified binder or an antistripping agent is highly recommended.