Comparative evaluation of pyrolysis oils derived from lignocellulosic biomass and municipal solid waste as potential bitumen modifiers

Abstract The transition toward sustainable road construction has led to increased research on replacing conventional asphalt binders with bio-based and waste-derived alternatives. Bio-bitumen derived from lignocellulosic biomass and binders modified using domestic and industrial waste have shown significant potential in reducing greenhouse gas (GHG) emissions by up to 80%. Life cycle assessments have reported net-negative emissions for certain biomass-based binders. However, these alternative binders may alter the chemical and molecular compositions of the base bitumen, thereby affecting its physical characteristics and overall performance. Pyrolysis of biomass and non-recyclable waste is emerging as a promising alternative due to its chemical similarity to fossil fuel–based oils. Despite its potential, the performance of pyrolyzed oils is highly dependent on feedstock type and process parameters. This study investigates the chemical, thermal, and rheological properties of binders produced from lignocellulosic sources (pine needles, sawdust, and rice straw) and a waste source (municipal solid waste). Five percent pyrolyzed oil from each source was added to the base bitumen (VG 40 in this study) for laboratory investigation. Results show that pyrolysis oils are chemically compatible with bitumen, but the variations in molecular composition and their quantitative presence affect the binder characteristics. Among all the samples, pine needle (PN) feedstock and PN bio-oil exhibited a balanced chemical profile with lower polarity, contributing to improved compatibility with petroleum binders. PN bio-bitumen demonstrated the closest similarity to the base bitumen in terms of molecular structure, thermal stability, rheological and aging response. The study concludes that the performance of bio-bitumen is strongly influenced by the source of pyrolysis oil, with PN bio-bitumen showing comparatively promising results for further development.