Evaluation of bio-based and petroleum-based rejuvenator based on cracking susceptibility of hot mix asphalt with high RAP content

Abstract

Highly aged asphalt binder in RAP is a potential source of inferior performance, especially the cracking resistance of HMA. Use of rejuvenators is a suitable way to incorporate more RAP by offsetting the stiffness of the aged binder. In this study, bio-based and petroleum-based rejuvenators were evaluated based on cracking susceptibility of the hot mix asphalt prepared with low (15%) and high (30%) RAP content. Less amount of plant-based rejuvenator (15% by weight of RAP binder) was required to lower the RAP binder grade to a certain level in comparison to petroleum-based one (35%). Cracking susceptibility of the mix was determined by semi-circular bend test performed at intermediate and low temperature as well as by overlay test. It was observed that use of rejuvenator can successfully restore the cracking resistance of the mix with low RAP content from 93% to even 112% of the control mix. For mix with high RAP content the cracking potential cannot always be restored at the level similar to the control mix but can be improved from 56% to 144% of control mix properties. Petroleum-based rejuvenator is less susceptible to aging and performed significantly better to resist cracking for long-term aged mix in all the test performed in this study. However, use of maximum amount of rejuvenator should be limited because it can adversely affect the rutting as well as cracking resistance of the mix.