Abstract
This study evaluated the performance of reclaimed asphalt pavement (RAP) mixtures for (a) RAP percentage, (b) asphalt content, and (c) various base binders. All RAP mixtures were produced in the laboratory for better control of the plant production variables. A simplified viscoelastic continuum damage model was used to evaluate the fatigue properties of the mixtures, and the triaxial stress sweep (TSS) test was used to evaluate rutting. In addition, layered viscoelastic critical distresses (LVECD) pavement analysis was used to predict the fatigue resistance of the mixtures. To explain the observed fatigue and rutting behavior, binder testing was performed on binders extracted and recovered from the mixtures. The test parameters included performance grade, low-temperature critical cracking temperature, and multiple stress creep and recovery parameters tested at a high temperature. Incorporating soft binder was found to be a promising strategy because the binder test data and LVECD predictions indicated a noticeable improvement in the fatigue resistance of the mixes. The TSS test data did not show a significant reduction in rutting resistance. The predictions clearly showed that increasing the asphalt layer thickness could lead to improved pavement performance. Mixtures with low asphalt binder content (0.5% below the optimum binder content) turned out to be susceptible to fatigue. The best strategy for incorporating high percentages of RAP seemed to be the use of a soft base binder while maintaining the optimum asphalt binder content or increasing the asphalt layer thickness.