Assessing the Role of Extender Oil in the Enhancement of the Rheological Properties of Bio Modified Asphalt Cement

Abstract

In Iraq, the asphalt cement is produced as a byproduct during the crude oil refining process. The produced asphalt cement does not practice any further processing which is required to control its chemical composition and physical behavior. It was felt that incorporation of bio-modifiers can enhance its sustainability and reserve the required rheological properties. In the present work, the modification was conducted by implementation of extender oil (used oil) and scrap tire rubber in the wet process to improve the quality of the asphalt cement and provide a sustainable and proper quality of the binder for paving work. It was observed that a combination of various percentages of scrap tire rubber and extender oil had provided a suitable control on the temperature susceptibility in terms of penetration index and penetration viscosity number, temperature of equivalent stiffness, and the stiffness of the binder. The stiffness of asphalt cement was digested at cold, moderate, and hot environment. It was concluded that the addition of extender oil was able to reduce the PI by (27.2, 54.5, and 36.3) % when (5, 10, and 15) % of extender oil were added respectively. Addition of scrap tire rubber exhibit further control of the temperature susceptibility and was able to reduce the PI up to 10 % of rubber. The scrap tire rubber can improve the PVN of the binder, while the extender oil increases the negative values of VPN. When the 15 % of extender oil is implemented, the stiffness of the binder declines by (75, 90, and 50) % when the testing temperature decline from (60 to 25, and 4) ℃ respectively. Implication of 15 % of extender oil and 15 % of scrap tire rubber into the asphalt cement from Qayarah is recommended to control the temperature susceptibility and provide a sustainable binder for pavement.