Physical and Rheological Properties of Aged Bitumen Rejuvenated with Waste Engine Oil

Abstract

Age hardening of bitumen is one of the factors affecting the durability of asphaltic concrete pavements. As the bitumen ages, its viscosity increases and it becomes more stiff and brittle. Recycling agents have been used to restore or soften the aged bitumen properties to a consistency level appropriate for use in the recycling process of deteriorated pavements. This paper details a study on the use of Waste Engine Oil (WEO) from vehicles as a recycling agent for aged bitumen. The study focused on the rheological properties evaluation of virgin bitumen, aged bitumen and blended bitumen (50% of fresh bitumen + 50% of aged bitumen) mixed with waste engine oil as additive (with 0%, 3%, 6% and 9%). The aged bitumen was prepared through the process of Rolled Thin Oven Test (RTFOT) and Pressure Aging Vessel (PAV) test to simulate the aging process. The virgin bitumen, the aged bitumen, and the blended bitumen mixed with various proportions of WEO were then tested to determine their physical characteristics. Penetration, softening point, viscosity and dynamic shear rheometer (DSR) tests were conducted in order to determine rheological properties of the bitumen samples prepared. The penetration value of blended bitumen added with WEO increased with the addition of WEO. The softening point decrease with the percentage increased in WEO of the blended bitumen. The viscosity for the blended bitumen added with WEO decreases with the increase in the percentage of WEO added. The DSR results showed that the increase in the amount of WEO in blended bitumen decrease the G*/sin δ parameter. For the particular bitumen and WEO used, the optimum percentage of WEO is 6% by the total weight of bitumen as it complies with the Public Works Department of Malaysia’s specification requirements. This study suggests that WEO has ability to counteract the stiffening of aged bitumen and restore the aged bitumen to that of virgin bitumen. As the composition and performance of bitumen and WEO may be different from those used in this study, it is recommended that a detailed evaluation is carried out for the bitumen and WEO to be used in asphalt recycling.