Journal of the Korean Asphalt Institute ISSN:2234-0785(Print) 2635-9553(Online) 한국아스팔트학회지

This study was designed to analyse the short-coming of conventional instant mixing (IM) method for recycling reclaimed asphalt pavement (RAP) in recycled mix. During this IM process, RAP and new materials are instantly mixed in a mixer for a short time period without knowing the aged binder in the RAP is not properly rejuvenated by virgin binder. To overcome this problem, a new mixing method, that is called a stage mixing (SM) by which the RAP and virgin binder are mixed first and then new aggregates are mixed together, was developed. The objective of this study is to show aging difference between binders on new and RAP in a recycled mix which was produced by IM, and to present how the aging difference is turned out in performance. To evaluate whether or not the RAP binder is rejuvenated well, gel-permeation chromatography (GPC) was used to examine the binder located new and RAP coarse aggregate particles separately in a recycled mix. Indirect tensile strength (ITS), deformation strength (SD), wheel tracking and tensile strength ratio (TSR) tests were conducted to evaluate to performance for both mixtures. Results showed that there were significant aging level differences between the mixes produced by IM and SM. The mixes by IM were turned out to show higher stiffness and poorer serviceability performances than the mixes by SM in all four testing evaluated in this study. Therefore, it was concluded that the recycled mix should be produced by stage mixing technique for better performing recycled mixes.