Performance evaluation of petroleum bitumen binders and mixtures modified by natural rock asphalt from Xinjiang China

- A comprehensive performance of bitumen binders and mixtures containing rock asphalt was evaluated.
- Rock asphalt improved the high temperature performance for both bitumen binder and mixtures.
- RA showed slight adverse influence on the low temperature performance.
- The PG grade of bitumen can be broadened by as high as two grades with rock asphalt.
- The tensile strength, moisture damage resistance and fatigue performance were also improved by rock asphalt.

Previous studies have showed that the property and modification outcomes of rock asphalt (RA) is dependent on RA sources and their chemical components. The RA from Xinjiang China was used to modify the petroleum bitumen. RA with five different dosages were added into petroleum bitumen: 0%, 5%, 10%, 15% and 20% by weight. A comprehensive performance of the RA modified bitumen binders and mixtures were evaluated in this study, including the high temperature performance, low temperature performance, moisture susceptibility, tensile strength, and fatigue performance. The tests conducted included dynamic shear rheometer (DSR) test, bending beam rheometer (BBR) test, wheel track test, three-point bean bending fracture test, and three-point bean bending fatigue test. It was found that the results for the bitumen binders agreed well with that for the bitumen mixtures. The addition of RA improves the high temperature performance of petroleum bitumen binders and mixtures. The moisture damage resistance, tensile strength and fatigue performance of petroleum mixture were enhanced as well with the addition of RA. The low temperature performance was slightly sacrificed after the addition of RA. However, the final PG grade width of the RA modified bitumen binders were broadened by one or two grades. Overall, the RA from Xinjiang China is a very good modifier for petroleum bitumen for performance improvement.