Repeated Loading and Unloading Tests of Asphalt Binders and Mixes

Repeated creep and repeated load permanent deformation tests were performed on asphalt binders and mixes. The repeated creep test method was proposed as a new method for the evaluation of the ability of modified asphalt binders to maintain their elastic response; and the suitability of this test method for evaluation of asphalt pavements was studied. Rheological modeling with linear and nonlinear viscoelastic models was applied to describe the material behavior. The second test method, known as the repeated load permanent deformation test, was proposed by the United States National Cooperative Highway Research Program (NCHRP) as one of the Simple Performance Test (SPT) candidates for asphalt mix testing. The effects of loading, material (conventional base asphalt and polymer modified asphalt) and the number of cycles were investigated. The capability of the Universal Testing Machine (UTM) to produce haversine pulse loading and the resulting responses were investigated. The ability of viscoelastic theory to describe the asphalt mix behavior under this testing was studied.