Asphalt and binder evaluation of asphalt mix with 70% reclaimed asphalt

With modern recycling technologies, reclaimed asphalt (RA) has been successfully used in new hot mix asphalt (HMA). However, even if the conventional technical specifications on binders and asphalt mixtures are met, HMA produced with high amount of RA, 50% and higher, may show poor performance behaviour. This is particularly true for cracking susceptibility due to the different chemical and physical properties of aged bituminous binder. The benefit of a purposely designed rejuvenating agent can help in using a high amount of RA in new HMA. This paper presents an evaluation of asphalt mixtures comparing a virgin asphalt mix with 0% RA and mix with 70% of RA with and without a bio-based rejuvenating agent. The different asphalt mixtures were characterised with complex modulus measurement at different temperatures and frequencies, and low-temperature cracking susceptibility through the thermal stress restrained specimen test. The binder was extracted and recovered from the different mixes to be also investigated through complex shear modulus and low-temperature behaviour using the bending beam rheometer. The outcomes of the tests showed positive effects of the bio-based rejuvenating agent especially at low temperature to restore flexibility. These effects were consistent on both the binder and the asphalt mix scale.