Nebraska Balanced Mix Design Phase I

Balanced mix design (BMD) is an alternative concept for designing asphalt mixtures that mainly focuses on performance of mixtures rather than only volumetric analysis. Using this concept, it would be possible to account for the incorporation of recycled asphalt mixtures, warm technology, polymers, rejuvenators, and other foreign additives, as well as external effective factors on the mix design such as environmental effects. This project sought to investigate performance-based methodologies for the asphalt mix design by taking a step to develop a preliminary Nebraska BMD framework. With that, selection of appropriate performance tests, finding a functional laboratory aging protocol, and defining performance test criteria were the main long-term goals developed in this phase of study. To this end, three main types of distresses were taken into consideration (rutting, fatigue cracking, and moisture susceptibility), and a set of performance tests including well-established tests (Hamburg Wheel Track (HWT), Illinois Flexibility Index Test (I-FIT), Tensile Strength Ration (TSR)) and surrogate tests (IDEAL-RT, HT-IDT, G-stability, IDEAL-CT) were selected to capture these distresses on two types of high-performance commonly used asphalt mixtures in Nebraska (SLX and SPR). For the fatigue cracking analysis, long-term aging conditioning was conducted using two common aging protocols (NCHRP 09-54 and NCAT). Three types of data were utilized in this study including laboratory performance test results for the lab-compacted and field core specimens, as well as field data based on pavement surface condition monitoring. The validity of the surrogate performance tests was accomplished not only by correlating the field core results with field condition data, but also with correlating every individual surrogate test result to that of a well-established test. Further, the sensitivity, practicality, cost-effectiveness, and variability of different tests were assessed using statistical