Experimental Investigation On The Effects Of Ageing And Recycling Agents On The Multiscale Properties Of Binders With High Rap Contents

Abstract

Reclaimed Asphalt Pavement is very valuable materials commonly reused in asphalt mixtures due to their economic and environmental benefits in the road construction and now has become a common practice in the asphalt industry. One limit in the RAP contents in asphalt mixture is the fact that the aged binder that is present in RAP can cause a premature cracking. Rejuvenators are frequently added to high RAP mixtures to enhance the properties of the binder. Since RAP is an aged material recycling agents are used to reduce the stiffness of recycled asphalt mixtures and reducing chances of crack at high RAP contents. The aged binder may also negatively affect the low temperature performance of asphalt mixtures. In this study, a waste cooking oil based Rejuvenator was used to restore the properties of short and long term aged asphalt binder with different percentage of reclaimed asphalt pavement (25% to 50%). The Rheological, physical and Chemical properties were then analyzed at PG 60-80 and PG 80-100 and an SBS Modified asphalt were used in this study as a virgin materials. A pressure aging vessels test was conducted to perform long term aging process of the asphalt samples. The binder blends were prepared at four different ageing conditions (Unaged, RTFO, 20-h PAV and 40-h PAV). As RAP binder (Waste Cooking oil) increases from 1% to 5% value of Penetration, Ductility, Softening Point and M-value Decreases while Viscosity, G*/Sinδ and Creep Stiffness Increases. This indicates Properties of the binder are very sensitive to the RAP content. As a result of Rejuvenation to the aged bitumen with 1%-5% of WCO by the total weight of the bitumen for aged bitumen due to gradual aging, bitumen losses its properties. the amount of RAP increases from 25% to 50% before rejuvenating shows the fracture energy of the mixture reduces and potential susceptibility to thermal cracking resistance, and after rejuvenating with 1% to 5% WCO Rejuvenator ad 0.22 RBR it leads to the decline of cracking resistance at low temperature and it needs to be seriously considered in the design of mixtures with High RAP contents. The result showed that the addition of Recycling agent and the use of softer base binder grade reduced stiffness and improved the low temperature properties of the binder blends while ageing adversely affected these properties.