Modeling and Correlating Rut Depth Observed in Different Asphalt Mixture Performance Tests

The purpose of research is to model and correlate the laboratory rutting behavior of indigenous asphalt mixtures, prior to placing in the field. Extensive laboratory testing was carried out on thirty representative wearing course mixtures using two types of rutting performance tests i.e. CWTT (Cooper Wheel Tracking Tests), and APA (Asphalt Pavement Analyzer) tests. The mixture ranking is consistent for both laboratory performance tests at the tested temperature conditions of 40 and 50oC. Laboratory rutting prediction models have been developed by non-linear regression analysis technique. Significant independent variables involved in the model are temperature, number of passes in case of CWTT or number of cycles in case of APA tests, bitumen penetration value, and Flakiness index of coarse aggregates fraction. A strong relationship has been observed between measured and predicted values of rut depth in terms of R2 value of 0.92 and 0.95 for CWTT and APA tests, respectively. A reasonable empirical quadratic function correlation (R^2 = 0.69) has been developed between rut depth of CWTT and rut depth in APA test.