, Professor, Civil, Environmental and Geo-Engineering
Jialiang Le, Professor, Civil, Environmental and Geo-Engineering
High field density is desired for improving the durability of asphalt pavements. This project aimed to develop Superpave 5 mixtures (more compactable than traditional Superpave mixtures) by using locally available materials to improve the field density in Minnesota. First, researchers investigated previous projects in Minnesota. The mean and standard deviation of field density in Minnesota were about 93.5 percent Gmm (maximum specific gravity) and 1.5 percent Gmm, respectively. The research team identified significant correlations between field density and mix design indices, i.e., Ndesign, NMAS (normal maximum aggregate size), and fine aggregate angularity (FAA). Researchers then selected and modified four traditional Superpave mixtures to Superpave 5 mixtures by adjusting their aggregate gradations while maintaining the asphalt binder content. The research team performed laboratory performance tests to check the mechanical properties of the modified mixtures. The results showed it was feasible to design Superpave 5 mixtures (more compactable mixtures) by adjusting aggregate gradations, and the improved compactability of the mixtures did not adversely affect the performance of the mixtures for rutting, stiffness, and cracking resistance. Therefore, if implemented, Superpave 5 mixtures can increase field density as well as other performances of asphalt pavements.