Application of Waste Cooking Oil as a Rejuvenator for Aged Bitumen

Abstract

Abstract Bitumen/asphalt is used as a binder in flexible pavements. It is obtained from petroleum which is a non-renewable source of energy. Therefore, use of recycled asphalt pavement (RAP) is sustainable and economical as it replaces the fresh bitumen in the mix design. Stiffness of bitumen increases after aging due to environmental effects. Therefore, use of aged bitumen in construction of RAP causes increase in thermal crackling. To overcome this stiffening effect and to increase the self-healing properties of bitumen, certain materials in the form of rejuvenators can be added. Organic oils such as waste cooking oil (WCO) can be added to recycled bitumen to soften it by replacing lost maltenes and saturates. In this study, varying percentages of WCO are added to the RAP mix and its physical and rheological properties are evaluated by various tests. The results of the study indicate that properties of naturally aged bitumen and artificially aged bitumen improvise when waste cooking oil is added to them in a limited quantity. The addition of waste cooking oil as a rejuvenator improves properties of aged bitumen such as viscosity, softening point, penetration and ductility, but can decrease the Marshall stability of the mixture if too much WCO is added. The optimum range for adding WCO was found to be around 4% for thin film oven aged bitumen and around 6% for naturally aged bitumen. The rejuvenated material can be used in the construction of low-cost roads. Treatment of waste oils can also be done to remove the Free Fatty Acids (FFAs) from the waste oil. One such process applied in this study is the process of Transesterification. After testing, it was found that the properties didn’t vary substantially upon treatment of waste cooking oil. So, it is not recommended as it also increases the cost of the project.