Reclaimed asphalt pavement (RAP) is the deteriorated pavement material, containing aged binder and aggregates. A rejuvenator is normally added to the mixture to reduce its stiffness, by blending with the aged binder and changing the properties of the mixture. Therefore, it is necessary to have an insight into the microstructure of the RAP and rejuvenated RAP. In this study, waste engine oil (WEO), waste vegetable oil (WVO) and waste grease (WG) are used as rejuvenators, at different dosages. The interaction between the rejuvenator and RAP is evaluated through microscopic analysis, Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) analysis. The microscopic analysis has provided the orientation and distribution of the aggregate, depicting the significant increase in coating of aged binder on the RAP with the increase in the rejuvenator dosage. The FTIR and XRD results have shown that rejuvenator has restored the asphaltenes and maltenes ratio and fluidity of the RAP. WG has comprehensively enhanced the asphaltenes and maltenes ratio, compared to the WEO and WVO. However, microscopic analysis suggests that the WG has high agglomeration. Overall, it is concluded that 6% WVO is a perfect dosage to enhance fluidity of the RAP. © 2020, © 2020 Informa UK Limited, trading as Taylor & Francis Group.