Improved skid resistance through small chip seal design

Transit New Zealand requires higher polished stone value (PSV) aggregate, limiting sources being used for sealing chip. Research to date has suggested that skid resistance increases linearly with percentage crushing. The use of a smaller chip ensures more crushed faces, with sharper aggregate tips thereby increasing tyre hysteresis. It has been suggested the use of 100 per cent crushed chip has an effect of increasing PSV by 4 to 5 which, if accepted, could result in marginal PSV sources becoming more acceptable. The use of crushed multi grade, small chip will prolong the time to rehabilitate a pavement, for layer instability. Recent research suggests surface amalgams which contain higher percentages of sub 4.75mm stone have greater stability. This paper presents the initial findings of initial field trials based on the theories suggested above. Further we suggest this approach is safer, more environmentally friendly and better for the overall performance of the road asset.