Influence of thermal and moisture ageing on the mechanical behaviour of conventional and polymer-modified asphalt mixtures

This study aims to improve our understanding of how ageing affects the performance of asphalt mixtures used in pavements, focusing on two commonly applied binders: conventional Petroleum Asphalt Cement (PAC 50/70) and Polymer Modified Asphalt (PMA 55/75). Considering the tropical climate in Brazil, where temperature and moisture both play a crucial role in pavement durability, four ageing conditions were simulated: no ageing, short-term thermal ageing, long-term thermal ageing, and long-term thermal ageing combined with moisture exposure. The results indicate that ageing increases binder stiffness and improves resistance to permanent deformation, especially in polymer-modified mixtures. However, exposure to moisture reduces this resistance, primarily affecting mixtures with conventional binders as a result of adhesive failure. Statistical analysis confirms that there are significant differences in susceptibility to ageing between the two binder types. Overall, the polymer modification enhances the mixture is resilience against combined thermal and moisture ageing. These findings highlight the importance of incorporating realistic ageing scenarios and including moisture effects in laboratory evaluations to better predict the performance of pavements in tropical regions.