Influence of Polymer Type and Dosage on Binder Mix Design Considerations

This study investigated the influence of polymer types and dosages on binder mix designconsiderations utilising High-Density Polyethylene (HDPE) and Butonal (aqueous SBS polymer)as modifiers. The initial characterisation of unmodified asphalt binder involved establishingfundamental properties, namely softening point, penetration index, flash and fire pointtemperatures, and specific gravity, which constituted baseline parameters for subsequent analysis.Subsequently, the asphalt binders were modified through the incorporation of HDPE and Butonalat concentrations of 2%, 3%, 4%, and 5% by weight. These modified binders were subjected to acomplete evaluation, examining softening point, penetration, and specific gravity to assessperformance variations. Results showed that HDPE modification generally increased binderstiffness, with higher softening points and lower penetration values, enhancing high-temperaturerutting resistance but risking reduced low-temperature flexibility at excessive dosages. In contrast,butonal modification resulted in improved elasticity while maintaining penetration values withinmoderate ranges, indicating better resistance to thermal cracking. Specific gravity was found tovary non-linearly with both polymer types and dosages, influencing binder volume and mixvolumetric parameters such as Voids in Mineral Aggregate (VMA) and Voids Filled with Asphalt(VFA). The findings highlight the need for polymer- and dosage-specific calibration of mix designto balance stiffness, elasticity, and thermal stability while adjusting binder content to account fordensity changes.”