Abstract
Most bituminous binders used for pavement materials are derived from fossil fuels, specifically crude petroleum. Nowadays, technical and economic prospects exist in using biorenewable resources to produce biobinders. Biobinders can be used in three ways to decrease the demand for crude petroleum–derived bituminous binders: direct alternative binder (100% replacement), bitumen extender (25% to 75% bitumen replacement), and bitumen modifier (<10% bitumen replacement). Applicability of developing biobinders from oakwood-based bio-oils to be used as a direct alternative has been investigated through studying the rheological properties. Temperature and shear rate (rate of loading) of biobinders and modified biobinders play major roles in changing the viscosity of bio-oils. The rheological properties of oakwood bio-oils have been investigated and compared with those of bitumen binders, to study the applicability of producing biobinders. Temperature and shear susceptibilities have been studied through measuring the viscosity of the bio-oils. Results reveal that the relationship between the viscosity of bio-oils and temperature and shear rates are log linear–like bitumen binders. In addition, temperature is the main contributor to the viscosity of the bio-oils in comparison with shear rate. Important is that the viscosity temperature susceptibility values for the bio-oils in comparison with bitumen blends indicate that bio-oils are more susceptible to temperature. Moreover, the addition of polymer modifiers leads to a change in temperature ranges of the bio-oils. In conclusion, the rheological properties of oakwood bio-oils are similar to and comparable with bitumen binders, and they represent a viable renewable alternative to petroleum-derived asphalt binders.
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