Balanced Mix Design Relation With Predicted Pavement Performance: An Illustrative Example

Abstract: Conducting volumetric-based designs of asphalt mixtures (e.g., Hveem, Marshall, Superpave) coupled with performance testing is gaining popularity among State and local agencies. This type of mix design is commonly referred to as Balanced Mix Design [BMD]. Due to the laboratory testing, more performance-related information on asphalt mixtures can be collected aiming at designing an asphalt mixture for balanced performance among different critical distresses. Therefore, it is believed that adopting BMD will enhance pavement field performance. To investigate the impact of BMD on pavement performance, six asphalt mixtures were designed following the BMD method to have similar laboratory performance. Various asphalt mixture components (e.g., binder content, reclaimed asphalt pavement [RAP], recycling agents [RA], gradation) were used. FlexPAVE TM was adopted for conducting pavement design and evaluating the predicted pavement performance of each mixture. FlexPAVE TM nationally calibrated models were verified using the AASHTOWare TM Pavement ME locally calibrated models. Pavement performance was analyzed in terms of rutting and fatigue cracking. Different pavement performance trends were observed among the different asphalt mixtures. Additionally, to pass a set of rutting and cracking criteria, different asphalt mixtures required different pavement structures. This suggests that an inconsistent relationship exists between BMD and predicted pavement performance.
Moreover, this outcome highlighted that asphalt mixtures with similar laboratory performance may not be substituted in the same pavement structure. An illustration is provided of how to improve index parameters from laboratory tests to provide better estimates of pavement performance.