Ageing effects of Modified Asphalt Binder with Sustainable Additives using RTFO and PAV methods

The ageing process leads to pavement distress, including fatigue and thermal cracking. Various laboratory ageing methods are employed to evaluate the durability of modified bitumen. These methods, which include a rotational thin film oven (RTFO) with pressure ageing vessels (PAV), play a crucial role in assessing the resilience of asphalt materials. In this study, binder ageing (RTFO + PAV) was conducted using one conventional, two activated carbon-modified, and two warm mix asphalt binders. Chemical analysis of the binders was performed using Fourier transform infrared spectroscopy (FTIR) tests. At the same time, the rheological response was assessed through dynamic viscosity, high-temperature performance grade, Superpave rutting factor, and multiple stress creep and recovery (MSCR) tests over a temperature range of 40 to 70°C at five distinct stress levels. The fatigue performance of the aged binders was evaluated using linear amplitude sweep (LAS) tests and a binder yield energy test (BYET). MSCR data indicated degradation at higher temperatures due to short-term ageing, thereby influencing the rutting characteristics of the modified binders. FTIR results suggested that the stiffness of PAV-aged binders is primarily attributed to the formation of carbonyl and sulfoxide compounds during ageing. Activated carbon modification significantly improved the permanent deformation characteristics of the asphalt binders. Additionally, incorporating warm mix additives positively influenced the creep and recovery responses. BYET and LAS results show that 24 hours of PAV ageing might overestimate fatigue performance in modified bitumen. Hence, ageing the asphalt mix may offer a more practical approach for accurate assessment.

Keywords: Aging, Linear amplitude sweep (LAS), Binder yield energy test (BYET), Multiple stress creep and recovery (MSCR)