Rutting Prediction of Asphalt Pavement Layer Using C-ϕ Model

Past research has shown that the concept of C-ϕ (cohesion and angle of friction) can be applied for asphalt paving mix design. It has also been established that the C-ϕ model is able to analyze the behavior of asphalt pavement under load, thereby permitting the incorporation of mechanistic or semimechanistic distress models into asphalt mix design as well as pavement thickness design. Therefore the C-ϕ concept offers a useful basis for an integrated procedure for asphalt paving mix design and asphalt pavement design. This paper further illustrates the usefulness of the C-ϕ based approach by developing a rutting prediction model based on the C-ϕ model. The proposed rutting prediction model employs the widely adopted expression of power relationship as the basic equation for prediction of cumulative damage. The basic expression is modified by incorporating the following effects: (1) the effect of load through a stress ratio computed using the C-ϕ concept, (2) the effect of temperature, and (3) the effect of loading speed. The applicability of the model is demonstrated using laboratory wheel tracking tests on three different mix types. A proposed procedure of applying the rut depth prediction model for estimation of rut depths in in-service pavements is also outlined.