ABSTRACT
In the United Kingdom there has been a dramatic change in the types of asphalt surfacing laid. The traditional use of hot rolled asphalt with its reliance on high PSV 20 mm chippings and texture depth to ensure wet skid resistance has been replaced by a variety of thinner surfacing materials. These typically use smaller sized aggregate; have a smoother surface, negative texture with their aggregate coated with bitumen that may contain fibres or some sort of polymer modification. Observation of these new surfacings has shown that the bitumen used may be retained longer on the surface of aggregate than on an HRA. This prompted the question whether it is possible to predict the early life skid resistance of these types of surfacing. As a result a laboratory method has been developed that measures the change in skid resistance for different aggregate and bitumen combinations. This has shown how differences in the type of aggregate affect the rate at which binder loss increases wet skid resistance. The research has improved the understanding of the role of the materials used and the processes involved in the provision of early life wet skid resistance for new asphalt surfacings.
