Laboratory Investigation of the Ageing of Dense Graded and Stone Mastic Asphalt Mixtures for Runway Surfacing

Ungrooved stone mastic asphalt (SMA) is an attractive alternate to grooved dense graded asphalt (DGA) for runway surfacing. Laboratory and field trials have demonstrated the comparable mechanical properties of SMA, but no comparison of the age-related weathering, which often triggers runway resurfacing, has been performed. This research compared the ageing of SMA to otherwise identical DGA, over 98 days of accelerated ageing in the laboratory. The surface texture and modulus of the mixture samples were compared, as well as extracted binder rheology, composition, and chemistry. It was concluded that binder properties were unable to reflect the benefit of the greater binder volume associated with different mixture types. Similarly, the ageing profile of the mixture samples complicates comparison of the modulus of the samples. Overall, it was concluded that SMA is expected to last approximately 4 years longer as a runway surface, compared to equivalent DGA.