Rheological and chemical properties of bitumen during hot in-place recycling

Hot in-place recycling (HIR) is a viable on-site rehabilitation technique that regenerates 100% reclaimed asphalt pavement (RAP) with less new used material and less traffic delay. The objective of this study was to investigate the chemical and rheological properties of bitumen at various HIR construction phases. The results indicated that the complex shear modulus, Glover-Rowe parameter, recovery percentage as well as ageing-related functional groups increased after pre-heating process regardless of sample type. In addition, the high temperature increment after pre-heating process resulted in remarkable differences in Glover-Rowe parameter and non-recoverable compliance between the original binder and pre-heated binder. Furthermore, the bituminous materials after long-term service still had the risk of further ageing during pre-heating process, and this risk also had negative influences on rejuvenation, because most rheological parameters such as complex shear modulus, Glover-Rowe parameter, and non-recoverable compliance of rejuvenated bitumen were still larger than those of original bitumen.