EXPLORING THE BINDER BLENDING AND MOBILIZATION ON THE PERFORMANCE OF RECYCLED ASPHALT MIXTURES INCORPORATING RAP AND LIGNIN

Despite the increasing use of Reclaimed Asphalt Pavement (RAP) in asphalt mixtures, a significant gap still exists in the literature regarding the mobilisation of the aged RAP binder. Although the total RAP binder content is commonly considered during the mix design process, the extent to which this binder is effectively activated, interacts with the virgin binder, and contributes to the mechanical performance of the mixture is not yet fully understood. This uncertainty may lead to inaccurate estimations of the effective binder content and, consequently, affect the mechanical behaviour and durability of recycled asphalt mixtures. Moreover, lignin, a by-product of the paper and biodiesel industries, has potential as an asphalt binder additive to improve workability at lower temperatures. To contribute to this discussion, this study evaluated four AC14 asphalt mixtures. Two mixtures were produced with 20% RAP, whilst the other two incorporated 20% RAP and 20% lignin by binder mass. For each composition, two hypotheses regarding the mobilisation of the aged RAP binder were considered: full mobilisation (100%) and partial mobilisation (85%). Furthermore, the interaction between the virgin binder, the aged RAP binder, and lignin was investigated. Characterisation tests were performed on the virgin binder, the binder recovered from RAP, and the produced asphalt mixtures in order to evaluate the influence of aged RAP binder mobilisation on the final properties of the material. The results indicate that the mobilisation of the aged RAP binder influences the performance of recycled asphalt mixtures, highlighting the importance of properly accounting for its contribution during the mix design process. These findings provide further insight into binder availability in RAP mixtures and support the development of more reliable and sustainable recycled asphalt technologies.