Road trials of Stone Mastic Asphalt and other thin surfacings

This is the second report on a series of road trial sites with surface course materials that are innovative in the United Kingdom and have now been monitored for up to six years. This report describes the later sites, four with sections of stone mastic asphalt surface course and one with a multiple surface dressing thin surfacing system. These sites complement the previously reported sites with proprietary thin surfacing systems. The initial results from the new sites are reported, together with the results of the regular monitoring of all the trial sites. There are concerns about the reduction in texture depth with trafficking which was found with stone mastic asphalt on some, but not all, sites. Nevertheless, the overall performance of the various materials is encouraging, with several of the proprietary thin surfacings now having Departmental Type Approval for use on trunk roads and motorways in England. (A)