Low-temperature performance of recycled asphalt mixtures under static and oscillatory loading

In this paper the effect of reclaimed asphalt pavement (RAP) on the low-temperature properties of asphalt mixture is experimentally investigated and modelled. Two test methods are used: bending beam rheometer (BBR) mixture creep test, which is based on static loading, and dynamic shear rheometer (DSR) mixture complex modulus test, which uses oscillatory loading. First, creep stiffness, m-value, thermal stress, critical cracking temperature and complex modulus are derived, and then, statistically and graphically compared. Then, the rheological Huet model is used to evaluate the experimental BBR measurements and to derive a simple relationship associating the characteristic time of mixtures to the RAP content. The statistical results indicate that most of the mixtures prepared with RAP have relatively poorer performance compared to virgin mixtures up to a RAP content of 25%. Based on rheological modelling, it appears that RAP and characteristic time are linked through an exponential relationship.