Effect of Ageing on the Rheological and Chemical Characteristics of Bioasphalt

The supply of crude oil-derived asphalt binder is in constant decline, whereas its demand is increasing steeply. The finite nature of asphalt binder coupled with escalating prices of crude oil demands exploration of renewable alternatives. Bioasphalt is an environmentally friendly substitute for asphalt binder and is renewable and cost effective. The aim of this study was to investigate the effects of oxidative ageing (short- and long-term ageing) on the rheological and chemical properties of bioasphalt, produced by 30% replacement of asphalt binder with sugarcane molasses (SM). Dynamic shear rheometer and Fourier transform infrared spectroscopy (FTIR) were employed to assess the performance of bioasphalts. Complex shear modulus master curves showed that the addition of SM resulted in higher stiffness at lower frequencies. The increased complex shear modulus indicated enhanced permanent deformation characteristics of bioasphalt. Short- and long-term ageing index based on master curves of bioasphalts were 23% and 40% lower than the base binder. FTIR spectra of SM indicated the presence of phenols, amino acids, amines, alkanes, aromatics, carboxylic acids, alcohols, O─ H, and nitrogen compounds. The sulfoxide index and carbonyl index of bioasphalts were similar to marginally higher compared with the base binders. The ageing index patterns based on sulfoxide index and carbonyl index led to the conclusion that bioasphalts had similar ageing susceptibility as base binders.