Bitumen improvement with bio-oil and natural or organomodified montmorillonite: Structure, rheology, and adhesion of composite asphalt binders

The use of nanoscale particles and modifiers from renewable raw materials are modern approaches to improving the properties of existing materials. This paper examines the combined application of montmorillonite nano -particles (10-30%) and bio-oil (5-20%) to improve the properties of bitumen binder. A study of the rheological and wetting properties of bitumen has shown that the addition of 10% bio-oil alone maximizes the adhesion of bitumen to silicate surface without a noticeable deterioration in the fluidity of its melt. Due to bitumen's hy-drophobicity and bio-oil's hydrophilicity, montmorillonite was considered in two variants: hydrophilic (natural) and hydrophobic (organomodified). Hydrophilic particles form submillimeter aggregates in the bitumen me-dium, reduce its viscosity at low content and high temperatures, and shift the solid-liquid transition point to-wards lower temperatures. In addition, these particles increase the bitumen's stiffness upon cooling, its cohesion and adhesion, but slightly worsen the low-frequency elasticity. Hydrophobic clay affects the bitumen's properties more strongly, which is due to its exfoliation to nanoscale particles. This clay causes the gelling of bitumen binder at high concentrations over a wide temperature range, significantly improving its elasticity, stiffness, cohesion, and adhesion. Hydrophobic particles are better suited to produce a high-quality binder but make it highly viscous.