Evaluation Of Rutting Potential In Asphalt Mixes Using Finite Element Modeling

Quality of asphalt mix (HMA) is one of the main factors that affects the flexible pavement performance. Use of poor quality mix and finding their consequences through pavement performance evaluation is often too costly. Therefore, the remedy is to evaluate the quality of the mix at the design stage of a project. In recent years, performance-based testing has gained popularity so that problematic mixes can be identified and eliminated. Asphalt Pavement Analyzer (APA) has been successfully used in recent years for evaluation of permanent deformation or rutting in both hot mix and cold mix asphalt specimens. However, testing of asphalt mixes in the APA is often expensive and time consuming. Also, a small-scale model with only one layer of asphalt is usually tested in APA while a typical pavement cross section is made up of several layers. In view of layered pavement systems encountered in practice, three-dimensional finite element models (FEM) can be used to relate the APA test results with the in-service performance of the pavement. The primary objectives of this study are to develop a finite element model to simulate the laboratory testing of asphalt mixes in APA for rutting and to relate the test results to basic material properties. The APA tests results have been used to obtain the associated material parameters through simulation of the rut vs loading cycle response. These material parameters can be used to simulate rutting in an actual pavement using a three-dimensional finite element model. A visco-elasto-plastic model (creep model) has been used to represent the time-dependent characteristics of the asphalt mixture. Factors having significant effects on rutting potential of asphalt mixes have been identified. A commercially available finite element program, ABAQUS, is used in this study. FEM results show that the ABAQUS-based model can adequately account for cyclic loading and other factors and, as such, it can be used effectively to evaluate the rutting potential of in-service pavement.