Characterisation of bitumen through multiple ageing-rejuvenation cycles

The multiple recycling of bitumen offers the possibility of reusing it for repeated lifecycles and achieve a higher degree of circularity of materials used in pavement construction. Aiming to identify the prospect, this study aged bitumen in a laboratory setting and then rejuvenated it using a bio-based rejuvenator for four ageing cycles. The low temperature and fatigue performance of the bitumen in each cycle was comprehensively characterised using dynamic shear rheometer (DSR) based rheological measurements. The results illustrated that although rejuvenation cannot recover all properties of the aged bitumen to the level of virgin bitumen, using rejuvenators can largely improve most properties negatively affected by ageing. The optimal dosage of rejuvenators should be determined based on the balance of the properties. The use of rejuvenation indexes, such as the one employed in this study, can assure that the low-temperature and intermediate temperature performance can be met through multiple ageing-rejuvenation cycles. In terms of chemical changes, although ageing reduces the chemical or colloidal stability of bitumen, rejuvenation can recover this property to its initial level. Overall, the results obtained in the study suggest that using appropriate rejuvenators, bitumen can potentially be recycled through multiple lifecycles.