Most bituminous adhesives or binders that are used for pavement materials are derived primarily from fossil fuels. Nevertheless, with petroleum oil reserves becoming depleted and the subsequent promotion to establish a bio-based economy, there is a drive to develop and produce binders from alternative sources, particularly from biorenewable resources. Recently, through the application of scientific research and development, a range of different vegetable oils have been investigated to determine their physical and chemical properties to study their applicability to be used as bio-binders in the pavement industry. Bio-binders can be utilized in three different ways to decrease the demand for fossil fuel based bituminous binders summarized as follows: (1) as a bitumen modifier (<10% bitumen replacement), (2) as a bitumen extender (25% to 75% bitumen replacement), and (3) as a direct alternative binder (100% replacement). On the other hand, there has been no research conducted until now that studies the applicability of the utilization of bio-oils as a bitumen replacement (100% replacement) to be used in the pavement industry.

The main objectives of this dissertation can be summarized as follows. First, the rheological properties of fast pyrolysis liquid co-products (bio-oils) were investigated to determine the heat pre-treatment/upgrading procedure required for developing bio-binders from bio-oils. The second objective included the modification of Superpave test procedure to comply with the properties of the developed bio-binders. Third, the chemical characterization of the developed bio-binders was studied in addition to the physical characterization. Fourth, the utilization of bio-oils as bio-binders in the pavement industry was explored through determining the temperature and shear susceptibilities of the developed bio-binders and comparing them with commonly used bitumen binders. Fifth, the temperature performance grades for the developed bio-binders were measured in addition to the determination of the mixing and the compaction temperatures. Sixth, the master curves for the developed bio-binders were studied and compared to commonly used bitumen binders.

The overall conclusions about the applicability of using bio-oils as bio-binders in the pavement industry can be summarized as follows. First, the bio-oils cannot be used as bio-binders/pavement materials without any heat pre-treatment/upgrading procedure due to the presence of water and volatile contents in considerable amounts. The heat treatment/upgrading procedure for deriving bio-binders from bio-oils should be determined for each type of bio-oil separately due to the significant difference between the different types of bio-oils, e.g. the chemical composition, the process by which the bio-oils were derived, and the type of the biorenewable resource from which the bio-oils were derived. Second, the current testing standards and specifications, especially Superpave procedures, should be modified to comply with the properties of the bio-binders derived from bio-oils because of difference in temperature susceptibility and aging. Third, the temperature range of the viscous behavior for bio-oils may be lower than that of bitumen binders by about 30-40yC. Fourth, the rheological properties, i.e. temperature and shear susceptibilities, of the unmodified bio-binders derived from bio-oils vary in comparison to bitumen binders, but upon adding polymer modifiers, the rheological properties of these modified bio-binders change significantly. Fifth, the high temperature performance grade for the developed bio-binders may not vary significantly from the bitumen binders; however, the low temperature performance grade may vary significantly due to the high oxygen content in the bio-binders and subsequent aging compared to the bitumen binders.