Feasibility and Implementation of Balanced Mix Design in Nebraska

Balanced mix design (BMD) is an alternative mix design concept that is getting a lot of attention from the pavement community. It incorporates two or more mechanical performance tests, such as a rutting test and a cracking test, to assess how well the mixture resists common forms of distress. The BMD is considered as overcoming several issues in the current Superpave volumetric mix design, where proportioning of the aggregates and the asphalt binder relies primarily on empirical aggregate quality characteristics and mixture volumetric properties. Calculation of the volumetric properties is highly dependent on an accurate determination of the specific gravity of the mix components, which is not easy nor accurate with current test methods. Furthermore, the complexity and inaccuracy increase with the incorporation of reclaimed asphalt pavements (RAP) and foreign additives such as warm-mix additives, polymers, rejuvenators, and fibers. Therefore, performance tests need to be included as part of the mix design procedure to help ensure desirable pavement performance in the field. The overall goal of this research effort is to examine the feasibility of the BMD approach for Nebraska pavements and to develop a potential implementation plan of the method if it appears feasible.