Predicting the development of asphalt surfacing properties in Ireland

This paper gives an over-view of research into predicting the development of asphalt surfacing properties for mixes used in Ireland. Accelerated trafficking was simulated using the Road Test Machine. The asphalt materials included asphalt concrete, hot rolled asphalt, stone mastic asphalt; and proprietary high friction surfacing and thin surfacing systems. The properties assessed include wet skid resistance, aggregate exposure, 2D and 3D areal texture. The findings highlight the role of aggregate and bitumen type; nominal particle size and bitumen properties. The results show that properties such as skid resistance can be optimised for a given aggregate depending on how it’s used. It suggests that lower skid resistant aggregate can be used as a smaller nominal size and still provide adequate levels of in-service performance. The data suggests that current specifications could be modified to allow better optimisation / more sustainable use of local aggregates than previously allowed.