Viscoelastic and aging performance of waste engine oil rejuvenated recycled bitumen with and without nanoclay

Abstract

This study investigates the effects of the waste engine oil (WEO) on the viscoelastic properties of unmodified and organo-modified nanoclay (OMNC) modified bitumen blends containing simulated recycled asphalt pavement (sRAP) and virgin bitumen. The effect of OMNC on the long-term aging performance of the bitumen is also studied. A predetermined percentage of WEO was added to the bitumen blends, which contain 50 % virgin and 50 % sRAP bitumen. Engineering and viscoelastic properties of the prepared blends were tested. Penetration test and high-temperature performance grade retention rate (PGRR) results show that aging rate decreases as OMNC percentage increases. It was observed that mixing WEO to blends reduces their viscosity, which approaches the level of virgin bitumen. High-temperature performance grade (PG) tests results show that addition of 6.6 % of WEO to unmodified sRAP blend decrease its high PG from 94 to 76 °C while adding 4.9 % WEO to the OMNC-modified sRAP blend decreases its high PG from 88 to 76 °C. The results of multiple stress creep recovery (MSCR) tests show that the addition of WEO to sRAP blends can lead to an enhancement in recovery percentage (%R) and a decrease in non-recoverable compliance (J_nr) values. Further, WEO also reduces the complex modulus (G*) and increases the phase angle (δ) at a wide range of frequencies. Overall, adding 6.6 % and 4.9 % WEO to unmodified and OMNC-modified sRAP blends, respectively, offsets the effect of aged binders, suggesting it can act as a rejuvenator while providing elasticity and flexibility to long-term aged binders.