development of non-petroleum binders derived from fast pyrolysis bio-oils for use in flexible pavement (2010)

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.\nThe 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.\nThe 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.