Influence of RAP addition on linear viscoelastic behaviour and low temperature performance of Hot Mix Asphalt

Quebec Ministry of transportation currently limits the use of reclaimed asphalt pavement materials (RAP) to 10% in surface courses, due to the potential risks associated with cold weather. This restriction hinders the adoption of high RAP content mixes (>10%), which are nevertheless beneficial for reducing the carbon footprints of the asphalt materials sector and designing more environmentally and sustainable pavements. A study was therefore carried out to optimize the formulation and performance of high-RAP asphalt mixes in cold climates. The study evaluates the linear viscoelastic behaviour (LVE) using the complex modulus test and low-temperature performance (TSRST) of an Enrobé Semi-Grenu 10 mm (ESG10) mix with RAP contents ranging from 0 to 100%, using a PG 52S-34 binder. Complex modulus tests were fitted to the 2S2P1D model. TSRST tests measured cold performance. The results show that above 20%, stiffness increases and modifies the E2/E1 (viscous modulus (E2) and elastic modulus (E1)) ratio. Up to 30%, the addition of RAP does not significantly affect thermal performance or LVE behaviour