Investigating the Aging Susceptibility of Bio-Modified Asphalts

Asphalt binder supplies are shrinking, while the demand for it is increasing rapidly; this in turn has led to an increase in the price of asphalt. As the price of asphalt binder increases, the demand for alternative and renewable binder resources increases. Therefore, this paper investigates the effects of introduction of four different bio-binders (made from Corn Stover, Miscanthus Pellet, Swine Manure, and Wood Pellet) on the aging susceptibility of asphalt as measured by the change in rheological and chemical properties of a selected asphalt binder (PG64-22) as a result of oxidative aging. The results of Rotational Viscometer (RV) and Dynamic Shear Rheometer (DSR) were used to evaluate the rheological behavior of the various bio-modified asphalt binders. Overall, the rheological characterization showed that bio-binder from Wood Pellets had the most desirable properties in unaged status among all bio-modified specimens. However, this trend was reversed after aging, indicating Pellets bio-binder has thehighest susceptibility to oxidative aging. In order to quantitatively measure and compare the extent of aging, the chemical composition of each sample was obtained using the FTIR spectra. Oxidative aging was demonstrated through tracking the formation of carbonyl and sulfoxide groups due to aging. The results showed that aging susceptibilities varied significantly depending on the source of the biomass. The experimental results indicates that bio-binder from Swine Manure was least susceptible to aging, followed by bio-binder made from Corn Stover, Miscanthus Pellets, and Wood Pellets.