Recycling of petroleum bitumen used in road and roofing shingle is widespread, and in many cases the recycled content includes bitumen that has already endured multiple consecutive cycles of service life, and their aging level varies significantly. Therefore, there is a need to accurately determine aging level for each recovered bitumen based on fundamental measures established to track physio-chemical changes that occur during progressive aging. This study examines effects of progressive aging in bitumen and introduces aging indicators based on absorption spectroscopy. Bitumen samples were exposed to accelerated aging in a pressure aging vessel (PAV) and were examined by UV-vis absorption and Fourier transform infrared spectroscopy. Absorption spectroscopy results not only showed carbonyl content consistently increased with aging time, but also revealed other distinct chemical changes such as loss of saturated hydrocarbons, followed by carbonation and then degradation of the poly-aromatic cores of asphaltenes and resins with extended aging. As such absorption spectroscopy deemed to be useful to determine extent of aging resembling multiple periods of service life for bitumen.