Short term ageing of asphalt binder in thin asphalt layers.

The effects of ageing on pavement performance are significant, particularly in terms of fatigue cracking. South Africa has the 10th longest road network in the world, requiring innovative approaches to road construction due to severe budget constraints. Innovative solutions such as thin asphalt concrete layers for surfacing, result in unique ageing rates of the layers, which, in general, have a higher incidence of fatigue cracking than, for example, thicker asphalt concrete layers used in other parts of the world. The objective of this paper is to evaluate how ageing mechanisms affect various asphalt binder properties, and whether they affect them to the same extent or not. Furthermore, the objective of the paper is also to determine the accuracy of the Rolling Thin Film Oven Test (RTFOT) in simulating short-term ageing in the field. The RTFOT provides a relatively good indication of short-term ageing, according to this multi-decade ageing study, and the effect on the asphalt binder properties used as ageing indices depends on the specific property chosen for comparison before and after ageing. • From 2001 to 2012, the prevalent surfacing in South Africa was a dense-graded asphalt mix with 50/70-grade asphalt binder. • Asphalt binders were consistent over 2001 to 2012, originating from four South African refineries. • A short-term ageing method in the laboratory cannot emulate the reaction kinetics during manufacturing and placement. • Binder properties such as penetration and softening are affected to different extents in an oxidation / ageing environment. • The rolling thin film oven provides a good indication of ageing under typical conditions of manufacturing and laying. [ABSTRACT FROM AUTHOR]