Binder availability and blending efficiency of reclaimed asphalt: A state-of-the-art review

Use of reclaimed asphalt pavement (RAP) and reclaimed asphalt shingles (RAS) into asphalt mixtures has become more popular from economic and environmental perspective. However, a significant concern arises us to how much of the aged binder in RAP/RAS can be mobilized into virgin binder during mixing and construction. Variation in reclaimed binder availability leads to the variation of effective binder content, as well as the quality of the blended effective binder, hence the engineering properties of asphalt mixtures. Currently, different ap-proaches were proposed to quantify the blending efficiency of reclaimed asphalt. However, the mechanism and application of each method may not be well understood and clarified. This study presented a comprehensive literature review of binder availability and blending efficiency of reclaimed asphalt. Firstly, the concepts of reclaimed binder availability and blending efficiency were introduced. Secondly, different quantification methods were summarized with the understanding of their mechanisms and application. Thirdly, effects of different factors on blending efficiency of reclaimed asphalt were investigated. Lastly, practical applications of blending efficiency were reviewed.