Advanced Testing and Characterization of Asphalt Concrete Materials in Tension

The modeling of asphalt concrete materials is currently handled using linear viscoelasticity (VE) and viscoplasticity (VP) with damage. Exploratory frequency sweep and creep and recovery test results indicate that the linear VE with damage theory cannot represent the material response unless damage–healing is also included in the formulation. Therefore, the concept of effective stress, used for modeling damage, is extended to include additional nonlinear effects. A new theory of nonlinear VE with damage and VP is presented for uniaxial loading conditions in tension. A special load transfer device is described. It allows very fast unloading and very long recovery periods with complete unloading. It permits better separation between VE and VP components. Using this device, a uniaxial tension creep and recovery test is conducted and analyzed. The nonlinear material response is illustrated and a calibration of the damage function is presented. The formulation is being extended to three-dimensional conditions.