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The process of reclaimed asphalt pavement (RAP) recycling may occur multiple times during the life of the pavement. This study investigates the effect of multiple recycling on binder properties by employing a virgin 3045 PEN grade binder that was aged in the laboratory intended to simulate aging of binders in RAP. The aged binder was rejuvenated using two bio-oils and one softer binder. The doses of the bio-oils and softer binder were determined by matching the continuous high-temperature performance grade (PGH) of the rejuvenated RAP binder to that of the virgin binder. This aging and rejuvenation cycle was repeated three times. Finally, fatigue and rutting performance of the binder was evaluated for the three reuse levels. Results indicate that the material can be reused up to three cycles keeping good performance on fatigue or rutting. However, care should be taken regarding the cumulative effect of bio-oils causing an over-softening effect on the of the RAP. [ABSTRACT FROM AUTHOR]

• Previously used methods for determining DoA, DoAv and DoB are shown. • Investigation methods for determining DoA, DoAv and DoB are classified. • Advantages and disadvantages of the investigation methods and techniques are shown. • The literature review which may help in quantifying DoA, DoAv and DoB is given. The lack of understanding the mechanisms governing the interaction between reclaimed asphalt binder (RAb) 1 1 RAb – Reclaimed Asphalt binder. and recycling agents is one of the technical issues that still need to be resolved when high amount of reclaimed asphalt (RA) 2 2 RA – Reclaimed Asphalt. is used in a new recycled asphalt mixture (RAM). Due to important role of RAb in that interaction and increased used of RA, it becomes necessary to have a way to classify RA, as any other material used in asphalt mixture production. It is very important to determine how much RAb is active by itself (DoA) 3 3 DoA – Degree of binder Activity. , but also to determine how much RAb can be considered available for a mix design of RAM (DoAv) 4 4 DoAv – Degree of binder Availability. when a recycling agent is used. Finally, since that RAM's properties are strongly dependent on the degree of blending between RAb and recycling agent (DoB) 5 5 DoB – Degree of Blending. , it should evaluate to what extent RAb contributes to the final properties of RAM. These blending parameters (DoA, DoAv and DoB) are so crucial that identifying suitable methodologies for their assessment would be extremely important in performing a proper mix design due to dangerous of having a lack of active bitumen in RAM. This paper presents a literature review of methods which have been used for the evaluation and assessment of mentioned parameters, grouped in four macro-areas: mechanical, chemical, visualization and mechanistic approaches. Furthermore, summarized review of used methods was prepared together with their critical review, all with aim to find appropriate methods for determining these parameters. [ABSTRACT FROM AUTHOR]