Cracking Performance of asphalt binders and mixtures with Rejuvenator: the Kielsbroek case study

Due to considerable economic and environmental benefits, the incorporation reclaimed asphalt pavement (RAP) in new asphalt mixtures is one of the most sustainable practices in the construction sector. However, high RAP contents stiffen asphalt and comprise cracking resistance. The application of rejuvenators is often regarded as a promising practice because of their softening effect. Due to this effect, questions are also raised about the possibility of lowering production temperatures. The combination of high RAP contents, warm-mix asphalt (WMA) technology and rejuvenators is rather undiscovered because of the several variables involved. This study evaluates their joint effect on cracking behavior. Both asphalt binders and mixtures were tested with a specific focus on the cracking performance in both levels. Six high-RAP asphalt mixtures were produced, covering both surface (40% RAP) and base (70% RAP) layers, each prepared in a reference, a rejuvenated, and a rejuvenated-WMA variant. Air voids, indirect tensile strength (ITS) and semi-circular bending (SCB) fracture tests evaluated mixtures’ mechanical performance. Nine binder blends, including virgin, RAP, and rejuvenated virgin/RAP mixtures, were characterized by penetration and dynamic shear rheometer (DSR) frequency sweeps. The binder blend design and materials were based on the asphalt mixtures in order to compare across the different levels. Across binders, rejuvenation reversed ageing, restoring flexibility and lowering cracking indices. At mixture level, rejuvenated and WMA variants showed higher fracture energy, flexibility and improved cracking-resistance indicators, while modest reductions in tensile strength and some uncertainty due to variability remained. Overall, the bio-based rejuvenator effectively reversed binder ageing and enhanced cracking resistance in high-RAP mixtures. Integrating WMA delivered additional environmental benefits without forfeiting these mechanical advantages in most cases. However, the findings underscore the need to incorporate further mechanical performance evaluations, such as rutting resistance and moisture-sensitivity tests, to support the reliable long-term performance and broader implementation of high-RAP asphalt pavements.