The investigation of rheological properties of rejuvenated asphalt binder with waste cooking oil as rejuvenator

Asphalt binder plays a significant role in the performance of asphalt pavement. However, due to the limited availability of crude oil and the increasing cost of asphalt, alternatives are being investigated. Reclaimed asphalt pavement (RAP) provides a sustainable solution for the increasing demand of asphalt. However, the amount of RAP which can be utilized in asphalt mixtures is limited due to production and performance issues. Incorporation of high RAP content calls for rejuvenators, which rejuvenate the aged binder and increases the degree of blending. Among various rejuvenators, waste cooking oil (WCO) is gaining increased attention due to its availability and concern towards environmental pollution. When combined in proper proportions with RAP, WCO is a potential rejuvenator, which restores the properties of aged binder to that of unaged asphalt binder. This addresses two problems simultaneously and can greatly benefit the economy and environment. This study focuses on the viscoelastic and rheological properties of the rejuvenated binder with WCO and RAP. The rheological properties are evaluated using frequency sweep test by assessing the complex shear modulus and rutting parameter of different binders. The viscoelastic properties are studied using multiple stress creep recovery (MSCR) test. The data of the MSCR test are analyzed with the Burger model to understand the viscoelastic properties of the rejuvenated RAP binder. For each of 75%, 60%, and 45% RAP, three different oil proportions are selected, and the optimum WCO content is identified. The study concludes that higher RAP content results in lower viscous strain and higher elastic strain, whereas after mixing higher WCO, the viscous strain increases, and the elastic strain decreases. Hence, it is crucial to mix WCO and RAP in the optimum ratio to obtain the desired rheological and viscoelastic properties.