Impact of Warm-Mix Additives on Viscosity Reduction in Virgin and Aged Bitumen with Polymer Modification

Abstract

Combining warm-mixing and recycling technologies in asphalt pavement is essential for reducing energy consumption, lowering greenhouse gas emissions, and decreasing material costs, providing both economic and environmental benefits. This study examines how warm-mix additive types and dosages, bitumen aging levels, and bio-oil addition impact the viscosity of virgin bitumen, polymer-modified bitumen (PMB), and their aged binders. The results indicate that wax-based and chemical-based warm-mix additives impact viscosity differently: Wax-based additive reduces viscosity in virgin bitumen more effectively, while chemical-based additive lower viscosity in PMB significantly. Polymer presence increases viscosity compared to virgin bitumen, but PMB demonstrates superior aging resistance, especially beyond 40h aging. Moreover, bio-oil consistently provides a greater viscosity reduction than Sasobit, which tends to be less effective in aged virgin bitumen but becomes more effective in aged PMB over time. Using a warm-mix additive with a bio-rejuvenator is an effective way to rejuvenate aged bitumen, though the effectiveness of each additive depends on the presence of polymer and the aging level of the bitumen.