Bio-Oil Impact on Water Diffusion and Durability of Bitumen: Influence of Aging and Salinity

Abstract

Enhancing the performance and sustainability of asphalt materials is crucial for developing durable and environmentally friendly infrastructure. This study explores the impact of bio-oils derived from biomass waste on the water diffusion behavior of biomodified bitumen, highlighting the significance of surface interactions in optimizing material properties. Through dewetting contact angle measurements and differential Fourier transform infrared (FTIR) spectroscopy, we examine the interactions between water and biomodified bitumen. While bio-oils improve bitumen adhesion, they also increase water absorption, potentially weakening bitumen cohesion due to altered surface properties. Salty water interactions showed distinct behavior, with FTIR analysis revealing changes in bitumen surface composition from salt complex formation with bio-oil components. In the presence of a monovalent salt (NaCl), some biomodified binders performed significantly worse than others, highlighting the variability in salt-induced degradation among different formulations. Conversely, when exposed to a divalent salt solution (CaCl₂), all biomodified bitumen blends exhibited great resistance to dewetting. These findings emphasize the role of surface chemistry in influencing water diffusion and material degradation under varied environmental conditions. Additionally, short-term thermal aging was shown to increase water diffusion, affecting both the physical and chemical properties of bitumen. Density functional theory (DFT) analysis further elucidated how aging alters water–oil interactions, exacerbating water diffusion. Our study underscores the need for carefully refining bio-oil formulations to mitigate water-induced degradation and support sustainable, long-lasting asphalt solutions, especially in environments prone to salt exposure and corrosive conditions.