The mechanical response of dry-process polymer wastes modified asphalt under ageing and moisture damage

The use of waste polymers for modifying asphalt has remarkable environmental and economic advantages. However, limitation still exists in the resistance of these mixtures against moisture damage and ageing. This paper aims to explore the impact of ageing and moisture damage on the mechanical properties of modified asphalt mixtures with polymer wastes (plastic waste and crumb rubber). Asphalt mixtures designated asphalt concrete (AC14) were prepared using granite aggregate, 60/70 PEN asphalt, and filler (hydrated lime). The properties of indirect tensile strength, resilient modulus, dynamic creep, and rutting were calculated to examine the effect of short-, long-term ageing and moisture damage. The results of the mechanical tests for the modified mixtures were compared to the conventional dense-graded asphalt mixture. The findings showed that asphalt mixtures containing both polymers presented superior properties after short-term ageing. In contrast, long-term ageing has enhanced the control and plastic waste mixtures’ bonding properties while negatively impacting the rubberised asphalt. Long-term ageing has reduced the resistance of rubberised mixture against permanent deformation by about 33%. The moisture conditioning has significantly deteriorated the mixture’s resistance to cracking and permanent deformation, particularly for the control and rubberised mixtures. The modulus and rutting resistance of the asphalt mixtures modified by crumb rubber and waste plastic has decreased by up to 9% and 17% after moisture conditioning.