Evaluation of Superpave Mix Design for Low-Volume Roads in New Jersey

This research project explored the implementation of the Superpave® mixture design system for use on low-volume roads in New Jersey by comparing them with well-performing Marshall mixtures. The research used a reverse-engineering approach to examine mixture blend gradations, volumetric properties, performance, and durability of well-performing Marshall mixtures compared with Superpave mixtures for low-traffic-level applications. In addition, the research evaluated the number of gyrations needed to produce equivalent air voids to the well-performing Marshall mixtures in the Superpave gyratory compactor. The gradations of the fine-graded Marshall mixtures from four suppliers were used to develop corresponding Superpave mixtures in the lab. The comparison of the Superpave and Marshall mixtures showed that they had similar volumetric, rutting, fatigue, permeability, and average asphalt binder thickness characteristics. The research also established relationships between G_sb or G_mm and the number of gyrations needed to reach air void levels similar to the Marshall mixtures.