Biomass valorization toward sustainable bio-oil obtained by pyrolysis of lignocellulosic raw materials for bitumen modification

The quality and durability of road surfaces have long been an area of interest for researchers all over the world, who are trying to prolong life of service of roads and cut the additional expenses. The quality of bitumen, one of the most important parts of road building materials, can be improved with various modifiers, lots of which have been introduced and used commercially for a long time. This paper studies bio-oil obtained in the process of slow pyrolysis of sawdust as a sustainable modifier for bitumen production. Adhesive properties of bitumen produced by different methods of bio-oil introduction into the material are studied, as well as some of the no-harm characteristics. It was found that introducing both bio-oil and its fraction boiling above 350 degrees & Scy; directly into bitumen leads to a rise in adhesion rate (up to 91.52 % for unfractionated bio-oil and 79.98 % for bio-oil >350 degrees & Scy; fraction vs. 62.88 % for base bitumen). However, adding >350 degrees & Scy; fraction of bio-oil proved to deteriorate the bitumen's rheological characteristics, such as ductility and penetration, while adding bio-oil made bitumen fail the ageing test (mass change). The addition of bio-oil in the amount of 1 wt% into vacuum, residue showed to have a limited effect on the adhesion properties of the resulting oxidized bitumen, while passing both no-harm and ageing tests. The results reported that the optimal concentration of bio-oil added to bitumen in the case of the current study was 2-3 wt%, since it is at this share of the modifier that the binder shows peak adhesion indicators of the adhesion with the mineral surface.