Effects of copolymers on rheological and performance of binders and stone matrix asphalt mixtures

This research examines the effect of Nano-high density polyethylene (NHDPE) and SBR (Styrene–Butadiene Rubber) additives on the binders and stone matrix asphalt (SMA) mixtures’ performance behaviours. AC-60/70 binder, NHDPE (0%, 2%, and 4% by weight of binder), and styrene butadiene rubber (SBR) (0%, 2%, and 4%, by weight of bitumen) are utilised. Besides, the impact of the combination of SBR (1% and 3%) with NHDPE (1% and 3%) on the rheological behaviour of bitumen and the mechanical properties of the mixture was assessed. The results of the experimental tests were statistically evaluated using a two-factor analysis of variance (ANOVA). According to the rheological behaviour test, using both SBR and NHDPE additives not only enhance binders’ rutting and fatigue resistance as well as phase separation but also decrease binders’ low-temperature resistance. Besides, adding SBR, NHDPE, and NHDPE/SBR enhances the fatigue and rutting resistance of binders. The utilisation of both SBR and NHDPE increases the permanent deformation resistance, MR, ITS, fracture energy, and fatigue properties of a specimen. It was also found that NHDPE in comparison with SBR has a better impact in enhancing the performance of the mixture.