Variation in the Rheological Behavior of Asphalt Cement Obtained from Different Origins through the Ageing Process

Abstract

Paving asphalt binder is supplied by many refineries in Iraq as a by-product through the distillation process of crude oil. The present work assesses the variation in rheological behavior of the asphalt binders after practicing the ageing process. Asphalt cement binders were obtained from Daura, Erbil, and Nasiriya refineries and aged by practicing the accelerated short-term ageing process with the aid of thin film oven test apparatus. The samples were tested for rheological and physical properties before and after practicing the ageing process. The rheological indices (ductility ageing index, penetration ageing index, softening point, and creep stiffness) were evaluated and compared. It was observed that the asphalt binders of Nasiriyah, Dourah, and Erbil exhibit ductility ageing index values of 0.63, 0.62, and 0.56, respectively. The creep stiffness increased by a rate of 84.4%, 81.8%, and 74.2% after ageing, while the softening point increased by 10.4%, 6.1%, and 7.4% for Nasiriyah, Dourah, and Erbil binders, respectively. Evaluating the rheological indices of asphalt cement binders is recommended when implementing the same penetration grade asphalt binder for paving work if supplied from different crude oil refinery sources.