Preliminary study on using lignin as aging inhibitor in bitumen

During oxidative aging, oxygen reacts with active molecules present in bitumen producing polar compounds, principally ketones and sulfoxides, and increasing in the portion of asphaltenes. In general, oxidation reactions in bitumen yields to change its generic chemical composition and finally its colloidal structure deteriorating the physico-mechanical properties. Lignin is a natural polymer, which has been used in this study as an aging inhibitor to bitumen. Particularly, the effect of aging on the microstructure morphology, surface properties, chemical composition and rheological changes of lignin and the impact of latter as anti-oxidant in bitumen were evaluated. For the purposes of this study, Environmental Scanning Electron Microscope, Helium Pycnometer, Dynamic Vapor Sorption devices and were used to analyze the microstructure, density and specific surface area, respectively. Moreover, Fourier Transform Infrared spectroscopy was used to track the compositional changes in lignin-modified bitumen after PAV aging. Dynamic Shear Rheometer was used to analyze the rheological properties. Overall, decreasing in the carbonyl and sulfoxide compounds were tracked in lignin-modified binders confirm that lignin act as an aging inhibitor in bitumen.