Effectiveness of Pongamia pinnata oil as rejuvenator for higher utilization of reclaimed asphalt (RAP) material

An increasing trend in utilization of the reclaimed asphalt pavement (RAP) for pavement recycling is being noticed due to its cost-effectiveness and environmental sustainability. Most of the studies recommend to add RAP only up to 30% except a few which recommends up to 50% based on the convenience in field application. However, there is a scope for higher RAP utilization through the addition of rejuvenators or recycling agents. In this study, a non-edible oil (i.e. Pongamia oil) obtained from Pongamia pinnata was used as a rejuvenator for design of recycled hot mix asphalt (HMA) with higher RAP content. Rheological tests revealed that about 5% dosage of the rejuvenator is adequate to meet the performance in terms of rutting and fatigue cracking. The rejuvenated binder was found to be thermostatically stable when exposed to temperature up to 230 °C as observed from thermogravimetric analysis (TGA). The performance of the HMA containing a varying percentage of RAP (30% to 70%) with the addition of a softer binder and with the addition of rejuvenator was studied or compared in terms of volumetric properties, indirect tensile strength (ITS), moisture sensitivity, resilient modulus, rutting and intermediate temperature cracking. Results indicate that by adding the Pongamia oil as a rejuvenator, RAP up to 60% may be used in the production of HMA without affecting the performance significantly.