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

The reclaimed asphalt pavement (RAP) should be properly rejuvenated when it is used in a recycled asphalt mixture. In this study, a RAP was used for recycled mix with recycle ratios of 30, 40 and 50 wt. % without rejuvenator. A 19 mm virgin aggregate for binder-course mixes, and a PG58-22 asphalt were used for recycled mixes, and a PG64-22 was used for a normal (control) mix. The asphalt binders were recovered from the RAP, normal mix and recycled mixes by Abson method. Absolute viscosity at 60°C, kinematic viscosity at 135°C, PG grading, G*/sin δ and pass/fail (P/F) temperatures were measured from the recovered binders by a dynamic shear rheometer (DSR). Gel-permeation chromatography (GPC) was used to measure large molecular size (LMS) of binder from the dissolution of mixture particle without binder recovery for estimation of physical properties of asphalt. The recovered binder properties including absolute viscosity (AV), G*/sin δ and P/F temperature were found to be increased by the recycling ratio increases. The regression analyses between AV and LMS, and P/F temp. and LMS showed high correlations with R² > 0.99, respectively. Therefore, it was possible to estimate AV and P/F temp. reliably by LMS. According to Korean guide-line, recycled mixes failed to pass the limit of AV ≤ 5,000 p except for 30% recycled mix. However, all recycled mixes should be prepared using a rejuvenator when evaluated by P/F temp. method of the Asphalt Institute method, because the P/F temp. of recovered binders were 6°C on average higher than expected values.