An Australian airport was to be resurfaced by asphalt overlay. The airport had experienced variable performance from similarly designed asphalt overlays in the past. Previous investigations had established that changes in the asphalt mastic had likely led to a lack of asphalt shear stress resistance. Various sources of fine aggregate and binder had been used in previous resurfacing works. Mastic combinations containing two specific fine aggregates sources and two specific binder sources resulted in variable asphalt performance. The two fine aggregates were similar except that one contained predominantly Hisingerite clay minerals, which had potentially detrimental properties. The two binder sources were the same grade of acid-modified bitumen manufactured from dif erent crude oil source blends with significantly dif erent properties. A combination of repeated shear stress testing of mastic and bitumen determined that both the fine aggregate and binder sources significantly af ected the mastic response to shear stress, and therefore expected asphalt shear resistance. No adverse impact associated with the Hisingerite-rich fine aggregate was found. The two sources of bitumen showed significantly dif erent properties. It was concluded that apparently similar fine aggregate and binder sources could have significant impact on mastic, and therefore asphalt, performance in high shear stress states during hot temperatures. It is recommended that the current Australian specifications for airport asphalt should be reviewed to prevent significantly dif erent surface performance from nominally identical and compliant mastic constituents.
6th Eurasphalt and Eurobitume (E&E) Congress: Investing in our greatest asset: roads, Prague, Czech Republic 1-3 June 2016
Proceedings of the 6th Eurasphalt and Eurobitume Congress / pp.1-14