Balancing the Aromatic and Ketone Content of Bio-oils as Rejuvenators to Enhance Their Efficacy in Restoring Properties of Aged Bitumen

The potential of the bio-oil from the co-pyrolysis of poplar wood and waste tire rubber to revitalize severely aged bitumen was examined by shifting the balance of aromatics and ketones in the bio-oil. Laboratory experiments were performed to compare the revitalization efficiency of bio-oils from the pyrolysis of poplar wood and co-pyrolysis of wood and waste tire rubber. Furthermore, the chemical compositions of the bio-oils from both processes were studied using gas chromatography-mass spectrometry to distinguish how each bio-oil revitalized severely aged bitumen. The results showed that the wood pyrolysis bio-oil had high phenol and ketone relative contents but very low aromatic and alkane relative contents. In contrast, significant relative amounts (19.18%) of aromatics and alkanes and a lower ketone relative content (0.95%) were found in the co-pyrolysis bio-oil. The rheological characterization of aged bitumen rejuvenated with both bio-oils showed that the co-pyrolysis bio-oil was much more effective than the wood pyrolysis bio-oil, which was evidenced by a higher crossover modulus and frequency as well as lower shear thinning in the aged bitumen rejuvenated by the co-pyrolysis bio-oil. These results prove that the co-pyrolysis bio-oil is a potential asphalt rejuvenator.