Laboratory Study for Comparing Rutting Performance of Limestone and Basalt Superpave Asphalt Mixtures

Abstract

The primary objective of this research effort was to conduct a rutting performance–based comparison between limestone and basalt Superpave asphalt mixtures using dynamic creep rutting tests. Two sets of mixtures were prepared using limestone and basalt aggregate, mixed with one asphalt binder having a Superpave performance grade of PG 64-10. To overcome the stripping potential of the Superpave basalt asphalt mixtures, 1% by total weight of the basalt aggregate was replaced by hydrated lime for the filler portion of the aggregate. Rutting was evaluated at four different temperatures (40, 50, 60, and 65°C) and one loading frequency of 8 Hz. Rutting test results indicated that the basalt Superpave asphalt mixtures exhibited superior performance relative to the limestone Superpave asphalt mixtures. The difference in the rut depth at 19,200 loading cycles between the limestone and basalt asphalt mixtures was statistically significant at levels of $\alpha =1$, 5, 1, and 0.5% for the temperatures 40, 50, 60, and 65°C, respectively. The difference in the rut depth at 200,000 loading cycles between the two asphalt mixtures was statistically significant at levels of $\alpha =1$, 5, 0.1, and 0.1% for the temperatures 40, 50, 60, and 65°C, respectively. In addition, the difference in the number of loading cycles to rutting failure between limestone and basalt asphalt mixtures was also statistically significant at a level of $\alpha =0.1\%$ for all temperatures.