Aging Characteristics of RAP Blend Binders: Rheological Properties

A study involving two rolling-thin-film-oven-aged asphalts and their blends with 15 and 50% of extracted reclaimed asphalt pavement (RAP) binders was conducted to investigate the effect of RAP content and properties on the long-term aging characteristics of asphalt binders. The results from rheological analyses of aged, blended binders indicate that the aging characteristics of blended binders are dependent on fresh asphalt binders. The results show that the crossover frequency decreases at an exponential form as RAP concentrations increase, and the rheological index increases as RAP concentration increases. The pattern for stiffness increase as a function of aging times for RAP-blended binders is similar to that of a typical chemical-aging kinetic model, in which the stiffness increases substantially initially and then levels off at longer aging times. The results demonstrate that there is a linear relationship between the logarithm of G* and the phase angle for RAP-blended binders at all aging times and RAP contents, regardless of asphalt and RAP sources.