Evaluation of Superpave Repeated Shear at Constant Height Test To Predict Rutting Potential of Mixes: Performance of Three Pavement Sections in North Carolina

Abstract

The repeated shear at constant height (RSCH) test to predict the rutting potential of asphalt aggregate mixes based on field performance of pavement sections in North Carolina has been evaluated. Three pavement sections in Buncombe, McDowell, and Montgomery counties were selected based on the degree of rutting severity experienced after several years in service. The pavement section in Buncombe County showed no rutting, whereas those in McDowell and Montgomery counties showed light and severe rutting distress, respectively. Results of this study indicated that the RSCH test can clearly identify the well-performing versus poorly performing mixes (i.e., Buncombe versus Montgomery counties). Although previous studies in which the French pavement rutting tester and the Georgia loaded-wheel tester were used indicated early rutting of the pavement in Buncombe County, the RSCH test indicated that the mix was not susceptible to excessive rutting—in line with field experience of no significant pavement distress observed in this pavement. For Montgomery County, the RSCH test clearly showed that the mix was susceptible to excessive rutting with the wheelpath cores distinctly showing potential for tertiary flow—in agreement with experience of significant rutting distress observed in this pavement.