Successful Utilization of High Amount of Reclaimed Asphalt Pavement Material in Bituminous Pavements: Indian Case Study

Reclaimed Asphalt Pavement (RAP) Material can be recycled into a fresh bituminous mixture by heating and mixing with fresh aggregates and binder. Since the RAP bitumen undergoes aging during the service life, it cannot be used directly without modification with softer virgin bitumen and/or rejuvenators to avoid premature cracking in pavements. The amount of RAP that can be included in bituminous mixtures is limited because the mixtures with high RAP content will have increased susceptibility to cracking due to aged RAP bitumen. Therefore, the rejuvenators can be used to soften the RAP bitumen. A case study demonstrates an increase in the percentage of RAP material (around 80%) in a bituminous mixture treated with a rejuvenator and characterizes the mixture's quality. The main objective of this study is to provide a RAP mix design using hot in-place recycling technology for renewal treatment/preventive maintenance work of existing pavement of the Ranchi ring road project in the state of Jharkhand. In the laboratory, two rejuvenators (Tall oils and Paraffinic Oils) were evaluated to check its efficacy when blended with the RAP binder. In addition, the influence of rejuvenators was evaluated on extracted binders and mixtures conducted in various tests, such as softening point, penetration, and rheological properties at various dosages of rejuvenators. The Marshall method of mix design was adopted in this study for the mix design of HMA with 80% RAP content. In the field (Ranchi outer ring road), around 80% RAP material was successfully used in the surface layer (50 mm Bituminous Concrete layer) using a hot in-place recycling method. Required quantities of fresh aggregate, virgin binder, and rejuvenators are added to the RAP material milled from the pavement. Then, RAP, fresh aggregate, virgin binder, and rejuvenator are mixed well and compacted to the required thickness. Results showed that bituminous mix containing 80% RAP with tall oil rejuvenator fulfilled desired properties of surface layer mix.