Aging Characteristics of RAP Modified Binders--Rheological Properties

A study involving two RTFO-aged asphalts and their blends with 15 and 50 percent 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. This paper presents the influence of RAP binders on the rheological properties of fresh binders in terms of their aging characteristics. 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 the crossover frequency decreases 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 typical chemical aging kinetic model, where 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 phase angle for RAP blended binders at all aging times and RAP contents, regardless of asphalt and RAP sources.