This paper describes an investigation of the skid resistance of stone mastic asphalt (SMA), initiated in response to concern whether SMA poses a hazard to road users during the early stage of its life cycle. The surface friction of four different SMA mixes and dense graded asphalt (DGA) as a control was monitored early in its life and until after much or all of the binder had worn from the road surface. In addition the principle of applying grit to the asphalt surface was investigated to ascertain whether it improved surface friction and accelerated the rate of wear of bitumen from the surface. The investigation concluded that the surface friction of SMA is lower in its early life in comparison to DGA, however the investigation could not conclude whether the SMA posed a hazard to road users due to the reduced level of surface friction early in its life. It was shown that using surface gritting improved surface friction and may accelerate the rate of wear of binder from the surface. It is recommended that further investigation of the early life surface friction of SMA be undertaken as well as development work on the practice of using surface grit. (a) For the covering entry of this conference, please see ITRD abstract no. 0612AR242E.
Samenvatting