Partial replacement of asphalt binder with heavy fraction of hydrothermal liquefaction bio-crude oil

Abstract Growing interest in the use of bio-derived materials in asphalt pavements is driven by their potential cost benefits and environmental sustainability. Among emerging technologies, hydrothermal liquefaction (HTL) has shown significant potential for converting wet biomass to bio-oil. This study evaluates the potential of bio-asphalt from HTL to partially replace conventional asphalt binder. Two biobinders, referred to as Bio1 and Bio2, were employed. Two biobinder blends were prepared by partially replacing PG 64-22 with 50% Bio1 and 25% Bio2. The binders were evaluated using the Multiple Stress Creep Recovery (MSCR) and poker chip tests. Bio-mixtures prepared with both blends were evaluated using the Illinois Flexibility Index Test (I-FIT). Bio-mixtures containing 25% Bio2 were also evaluated using the Hamburg Wheel Tracking Test (HWTT). The inclusion of biobinder improved rutting resistance, as indicated by MSCR results. Replacing 50% of the asphalt binder with Bio1 reduced creep compliance by 47% and 41%, and increased percent recovery by 82% and 85% at stress levels of 0.1 and 3.2 kPa, respectively. However, reductions in strength and ductility were observed with aging in the poker chip test. I-FIT revealed that all short-term aged bio-mixtures met the cracking resistance threshold of Flexibility Index 8, while long-term aged bio-mixtures containing Bio-blend 1 met the threshold of 4, and those with Bio-blend 2 closely approached it. Hamburg Wheel Tracking results showed 21% less rutting for mixtures containing biobinder. This research underscores the potential of biobinders to replace 25–50% of asphalt binders and provides insights into their benefits and limitations.