Pavement

This report presents the findings from the first year of a three year Austroads study which aims to maximise the re-use of reclaimed asphalt pavement (RAP) in new asphalt product. The objective of this first year of study is to improve the methodology for the characterisation of RAP binders and the design of the binder blend in asphalt mixes containing RAP.

The study included a literature survey of the current international state of practice in terms of RAP binder characterisation. It further included experiments to develop a more practical and cost-effective approach to characterising the properties of binder blends containing RAP. The experimental work showed that the Dynamic Shear Rheometer (DSR) can be used to obtain viscosity parameters similar to the Shell sliding plate viscosity at 45 °C and the capillary viscosity at 60 °C. The DSR results are also more repeatable than the results of the Shell sliding plate test, which has conventionally been a more common test used in Australia for the characterisation of RAP binder.

The results show that for the RAP sources under study, a blend of C170 with 10% to 20% RAP does result in a viscosity equivalent to that of a C320, as generally accepted in current practice.

The DSR based methodology used in this study provides a practical, consistent and cost-effective method to characterise RAP binder blends. As successfully demonstrated in this study, the viscosity results from the DSR tests can be used to design RAP binder blends to a desired viscosity. The methodology will be further validated during the next year of this study, when it will be used to design binder blends for asphalt mixes containing various percentages of RAP.