Strategies to improve performance of reclaimed asphalt pavement-recycled asphalt shingle mixtures

Abstract

ABSTRACT Recycling highway construction materials and minimising the use of virgin materials can reduce the pavement life cycle costs, improve highway network condition, conserve natural resources, and protect the environment. However, aged binder in reclaimed asphalt pavement (RAP) and recycled asphalt shingle (RAS) makes asphalt pavements more brittle and creates long-term durability problems. In this study, the performance benefits of using softer virgin binder grade and increased virgin binder content strategies in RAP and RAS mixture production in Oregon were quantified. Semi-circular bend and flow number tests were conducted on prepared samples in laboratory to assess their cracking and rutting performance with low or no RAP (0% and 15%), high RAP (30% and 40%), and RAP&RAS, three binder contents (total binder contents with RAP/RAS and virgin binder – 6%, 6.4%, and 6.8%), and three binder grades (PG 58-34, PG 64-22, and PG 76-22). Moreover, possible combinations of RAP/RAS content, binder content, and binder grade to produce asphalt mixtures with high cracking and rutting performances were suggested using regression modelling and sensitivity analysis. The results of this study show that increasing binder content does not create any significant impact on the cracking performance of RAP&RAS mixtures but it is an effective strategy to improve the fatigue cracking resistance of 30% and 40% RAP mixtures.