This paper reports the results of a chip seal research project in Texas where the researchers are using quantitative, qualitative and economic means to compare hot asphalt cement and emulsion chip seal binder performance on rural roads. The Transit New Zealand T/3 “sand circle” test was used to measure the change in average texture depth over time for the two bindertypes and these measurements were then correlated with a qualitative windshield survey and Texas Department of Transportation’s Pavement ManagementInformation System ratings. The results demonstrate the value of quantitatively characterizing the preseal surface condition as a benchmark againstwhich to compare new chip seal performance. They also show that relying on purely qualitative pavement ratings can introduce errors into the pavement management system. The project found that those roads, regardless of the binder type used, that had poor preseal conditions and low macrotexture showed early loss of macrotexture and premature flushing after a reseal. It also found that the emulsion chip seals lost their macrotexture over time more slowly than the hot asphalt cement chip seals. Finally, an economic analysis of the two sample sets showed the emulsion chip seals to be themore cost effective alternative for maintaining satisfactory macrotextureover time.
Abstract