Development of an eastern shale oil residue as an asphalt additive: Subtask 2.5

An evaluation of eastern shale oil as an asphalt additive to reduce oxidative age hardening and moisture susceptibility is being conducted. An eastern shale oil residue having a viscosity of 1.30 Pa.s at 60° C (140°F) was blended with three different petroleum-derived asphalts that are known to be very susceptible to oxidative aging. In addition, blends of the eastern shale oil residue and the petroleum-derived asphalts are being coated onto three different aggregates that are known to be susceptible to water stripping. The oxidative age hardening portion of this study is not complete at this time. To date, information has been obtained on the imaged samples and two of the aged petroleum-derived asphalts (AAD-1 and AAK-1). When complete, this data will include rheological data on the unaged, RTFO-aged, and the RTFO/PAV-aged samples and infrared data on the unaged and RTFO/PAV-aged samples. With respect to the rheological data, asphalt AAD-1 meets the specifications of a PG 58 asphalt while asphalt AAK-1 does not. In the latter case this indicates that AAK-1 is more appropriately evaluated at a higher temperature range. The infrared spectroscopic data obtained for the eastern shale oil residue show that it contains appreciable amounts of carbonyl and sulfoxide compound types, 0.22 absorbance units and 0.27 moles/L, respectively. Thus, upon the addition of this residue to the three petroleum-derived asphalts the blends contain increased amounts of these functional groups relative to the petroleum-derived asphalts. This has been observed with other additives and is not considered detrimental. In addition, the data that has been collected to date indicate that the moisture susceptibility of blends of eastern shale oil residue and asphalt AAM-1 are somewhat improved when coated onto Lithonia granite. However, the addition of eastern shale oil residue to asphalts AAD-1 and AAK-1 did not improve the moisture susceptibility of these petroleum-derived asphalt blends when coated onto Lithonia granite. The results of the petroleum-derived asphalts and blends when coated onto low absorption limestone and silicious Gulf Coast gravel are not complete at this time.