WP2: Impact of RA Quality and Characteristics on Mix Design and Performance of Asphalt Containing RA

The objective of WP 2 is to analyse the potential use of RA in new asphalt surface layer mixes in consideration of the usage of modified binders. Therefore the chemical compatibility of new binders with old bitumens in RA and the physical performance of the resulting binder and asphalt mixes are examined to develop mix-design guidelines to ensure a long service life of asphalt mixes with reclaimed asphalt.

In new bituminous bound courses – especially in base asphalt layers – the use of up to 40 % of RA is state of the art in most of the European countries. In surface layers, RA is currently used only in a percentage up to about 10 to 20%, because the demands on the surface properties of wearing courses are very high, as they build the contact partner to the tyres. Additional to these requirements related to the traffic safety, surface layers are subject to a wide range of weather impacts. Wearing courses need a good resistance against rutting at high temperatures as well as a high resistance against top-down cracks, which are prohibited by good low-temperature and fatigue performance. To reach these requirements, in wearing courses the components with the highest quality are used (e.g. high quality aggregates, modified binders).

The benefits of the results of WP 2 lie in the rise of the percentage of RA especially in new surface asphalt courses. Thereby, the resources for virgin high quality aggregates and high performance binders can be preserved for future generations. The impact on the environment by the exploitation of new quarries is reduced. Further, the use of higher amounts of recycled materials will reduce the costs for new road infrastructure, which will release the public budgets for traffic infrastructure. As many European Countries doesn’t have natural resources of high quality aggregates, the transport demand of crushed chippings will be decreased witch results in a reduction of CO2–emissions.

WP2 Tasks:

• 2.1: RA compatibility with the new binder (conventional and modified)
• 2.2: Impact of RA on asphalt mix design and laboratory performance
• 2.3: Field validation

WP2 published reports:

• Chemical and physical compatibility of new and aged binders from RA
• Mix design and performance of asphalt mixes with RA
• Main report on results of comparative site monitoring