Smaller stone size surface dressings for high stone surface mixes

High stone asphalt surfacing mixes are widely used around the world. Although their high stone content has reduced problems with permanent deformation they pose a problem when they become polished and don’t meet minimum requirements for safety. It may be possible to overlay with another thin surfacing, remove and recycle or re-texture. Each process has differing merits in terms of sustainability. This paper considers chip seal as an alternative method. Traditionally, chip seal has been viewed as being noisy and has not been considered for use in urban areas where noise is an important factor in the selection of a new surface. Research at University of Ulster in noise prediction highlighted that small stone size chipseal surfacings can achieve significant noise reduction so offering an additional alternative for resurfacing. A laboratory study of chip embedment has investigated change in texture depth and skid resistance for a range of chip sizes and asphalt mix types. This has developed laboratory techniques that appear to rank the embedment of chip seal aggregates in relation to underlying road material. This study has shown less embedment for high stone mixes and confirms the findings of limited small stone size chip seal road trials where skid resistance and texture depth was monitored. This paper reports the findings to date.