Abstract

Asphalt cement is supplied by multiple different refineries in Iraq. The wide variation in environmental condition all over the country had led the flexible pavement to practice a considerable variation in surface temperature, ranging from -15℃ to more than 65℃. Ageing potential of the asphalt binder is variable. An attempt has been made in the present investigation to assess the influence of short and long term ageing on temperature susceptibility of asphalt concrete prepared by using dense graded aggregate and three types of asphalt binder obtained from Daura, Erbil, and Nasiriyah refineries located at middle, north and south regions of the country. Asphalt cement samples were subjected to the classical physical properties’ determination, stiffness modulus, penetration index, and creep stiffness. Asphalt concrete specimens of 102 mm in diameter and 63.5 mm in height were prepared using the prementioned binders and subjected to temperature susceptibility determination. It was concluded that implementation of asphalt binder of the same penetration grade but from varied asphalt sources from (Erbil, Doura, and Nasiriya) have produced different behavior under ageing. Erbil binder exhibit the lowest temperature susceptibility of 50 kPa/°C after long term ageing and highest creep stiffness of 270 MPa after practicing 7 hours ageing among Daura and Nasiriya binders regardless of ageing periods. However, Erbil binder exhibit the lowest stiffness modulus of 140 kN/ m2 and penetration index of (-0.64) before ageing as compared to other refineries’ binder regardless of ageing period. It is recommended that the selection of a proper asphalt cement for paving must be based on evaluation of rheological properties such as temperature susceptibility and environmental conditions rather than the present practice of considering the physical properties only.