There is a widely held perception that bitumen quality has reduced over the last thirty or so years. Bitumen suppliers certainly acknowledge that changes in the supply chain have occurred. However, they maintain that this is inconsequential to performance as the products remain within the requirements of the various paving-grade bitumen specifications. A review of existing information and literature pertaining to changes in Australian paving-grade bitumen supply and the performance of bituminous surfaces is presented. Changes in the crude oil sources and refineries for the manufacture of bitumen consumed in Australia is confirmed. There is also overwhelming evidence that the crude oil source and the refining impact on measurable bitumen properties, including the rheological composition, ageing profile and even the routinely measured specification parameters. Finally, there is significant evidence indicating changes in bitumen properties impact field performance of bituminous surfaces. Although not exhaustive, these examples form a science-based argument that, yes, variable field performance of bituminous surfaces has resulted from differences in bitumen properties, likely resulting from changes in oil sources and refining. The lack of confidence in field performance of different batches or supplies of the same grade of bitumen is concerning. This presents a challenge for the broader industry and must be addressed in a collaborative manner. A supplier-purchaser-client approach is essential and increased supply chain transparency would be beneficial for establishing a working level of trust across the industry.
27th Australian Road Research Board (ARRB) Annual Conference: Linking people, places and opportunities, Melbourne, Australia 16-18 November 2016