Simulation of field aging of bituminous concrete with and without warm mix additive using modified oven

of bitumen is a major concern which affects the durability of pavements on a long run. Numerous methods are being proposed by researchers for simulating the field aging in the laboratory to predict the long term field performance of the bituminous concrete. AASHTO R30 guidelines are very popular and are being used by many researchers and hence, these guidelines with necessary modifications have been followed. A laboratory oven was modified with additional facility of oxygen supply. Bituminous concrete specimens were prepared with and without warm mix additive (Sasobit) and filler (hydrated lime). Care has been taken to ensure that the grade of bitumen and gradation of aggregates of the laboratory samples are similar to the field core samples. These samples were subjected to aging from one to fifteen days in the modified oven after initial short-term aging of the un-compacted bituminous concrete mix. The aged bituminous concrete samples were then tested to find Marshall’s stability, flow value and tensile strength ratio (TSR). The field core samples were collected from selected locations on national highways 16 and 65.The aged bitumen from the field cores and the laboratory aged samples was extracted using the Soxhlet apparatus. Fundamental properties like penetration, softening point, ductility and viscosity were found for the extracted bitumen. It was observed that the laboratory aged bituminous concrete mixtures, aged in accordance with modified AASHTO R30 and the field core samples had a significant difference in the binder properties. It is concluded that the laboratory aging exposure for bituminous concrete mixture should be increased from 5 days (suggested by AASHTO R30) to 15 days to simulate the field aging.