Performance Improvements of Hot Mix Asphalt Concrete Using Carbon-Based Fillers

To further advance the state of the art on the performance improvements of hot mix asphalt concrete, this paper investigates the improvements to cracking damage of hot mix asphalt concrete by the addition of carbon-based fillers. There have been various studies dedicated to measuring the strength performance of asphalt mixtures modified with non-traditional fillers, but many of the current studies seem to have varying success with their results or have results that are not statistically significant. In this research, carbon black and F-516 graphite in various percentages were added into asphalt mixtures as a replacement of the traditionally used hydrated lime powder. Viscosity testing and indirect tension tests (IDT) were conducted on hot mix asphalt and asphalt mastic specimens, respectively. Results from the viscosity tests show that the addition of the carbon-based fillers increase the viscosity of the mastic. Indirect tensile tests with optimum binder contents showed mixed results. Carbon black specimens showed increases in the tensile strength, while graphite specimens showed decreases in the strength. Additional graphite specimens were then prepared with increased binder contents and results from IDT tests found increases in strength, although these improvements were lower than the specimens containing carbon black