Utilization of dry-method styrene-butadiene-styrene and epoxy polymer to enhance the aged asphalt binder: Properties evaluation and cost discussion

To reduce the cost of epoxy asphalt mixture (EAM) pavement and increase the performance of mixture with high reclaimed asphalt pavement (RAP) content, three different dry-method styrene-butadiene-styrene (SBS) modifiers and an epoxy polymer (EP) were employed in this study to enhance the properties of aged asphalt binder and prepare SBS-modified epoxy reclaimed asphalt (SERA) binders. The chemical interaction between the dry-method SBS and EP was analyzed, and the microscopic structure and mechanical properties of the SERA binder were evaluated. Additionally, a discussion on the initial material cost of the newly proposed SERA mixture (SERAM) was conducted. Results indicated that the degraded products generated by the oxidization of dry-method SBS undergo interactive reactions with the epoxy rings present on the epoxy resin molecules. Phase separation occurred both between EP and SBS-containing aged asphalt binder, and between SBS and aged asphalt binder. The addition of dry-method SBS to epoxy reclaimed asphalt (ERA) increased the size of the asphalt binder phase in the fluorescence images. At EP contents ranging from 30% to 50%, the incorporation of dry-method SBS led to notable improvements in the elongation at peak, low-temperature properties, and fatigue resistance of ERA binder. The SERA binder exhibited comparable or even superior properties in terms of tensile strength, low-temperature behavior, and fatigue properties when compared to virgin epoxy asphalt (EA) binder. However, dry-method SBS may have a negative impact on the high-temperature properties and curing time of the binder. Dry-method SBS with rejuvenation capacity exhibited the greatest improvement in elongation at peak, low-temperature properties, and fatigue properties of ERA. Compared to EAM, the utilization of SERAM results in material cost-savings of approximately 46 USD (9%) per ton of mixture.