IMPACT OF AGEING PROCESSES AND BINDER ORIGIN ON THE VOLUMETRIC PROPERTIES OF ASPHALT CONCRETE

Oil refineries in Iraq supply various types of asphalt cement. The environmental conditions across the country exhibit a significant temperature range of -15℃ to over 65℃ between winter and summer as well as an hourly variation in temperature between day and night of ± 20℃. The potential properties of asphalt concrete due to such harsh environment which accelerate the ageing process of the binder can vary. The influence of short- and long-term ageing on the physical properties of asphalt concrete prepared with asphalt binders of the same penetration grade obtained from Dourah, Erbil, and Nasiriyah refineries was assessed. The variation in the physical properties of asphalt concrete samples were tested for temperature susceptibility and volumetric properties such as bulk density, voids content %, voids filled with binder Vfb %, and voids in mineral aggregates VMA %. Asphalt concrete mixtures were prepared with optimum binder requirements and subjected to short and long-term ageing processes respectively. It was concluded that implementation of asphalt binder of the same penetration grade but from varied asphalt sources shows different behavior after practicing the ageing process. Erbil binder exhibits the lowest susceptibility to temperature variation of 35.42 kPa/°C among other asphalt binders. After the ageing process, the voids content increases by (38.8, 52.9 and 60) % for Nasiriyah, Erbil and Dourah binders respectively. The mathematical models obtained fit into the experimental observation with high accuracy. Hence, the models are practical to be used to predict the changes in volumetric properties of asphalt concrete throughout the ageing process.