How char from waste pyrolysis can improve bitumen characteristics and induce anti-aging effects

Modifying bitumens to improve their characteristics is one of the ways to increase road pavement durability reducing maintenance costs and environmental issues. In this study the structural and mechanical characteristics of a 50/70 bitumen modified by two different char samples are presented. The choice of char as bitumen modifier fulfils the recent needs for environmental protection. The two char samples come from the pyrolysis of Refuse Derived Fuel (RDF) and waste tyres (WT), respectively. They differ in composition and morphology and their production took place with different yields. Char-modified bitumens revealed increased shear modulus and resistance to mechanical stress as found by rheometry. Artificial aging of these char-modified bitumens unveiled that the bitumen modified by char from WT (WT-char) possessed a certain resilience against aging, with a reduced increase in rigidity upon aging. The anti-aging effect showed by WT-char was attributed to its higher carbon content, which confers higher compatibility with the bitumen chemical nature and presumably a more uniform dispersion within the bituminous structure thanks to the establishment of more effective interactions.