Toward a better understanding of the low-temperature reversible aging phenomenon in asphalt binder

Abstract

ABSTRACT Asphalt aging with time is one of the main causes that leads to the performance deterioration of asphalt pavement. Compared with non-reversible oxidation aging, reversible aging which resulted from molecular structuring gets little attention in asphalt materical specification, especialy at low-temperature. This paper aims to compare the effect of oxidation and isothermal conditioning on original asphalt binder’s low-temperature properties. Firstly, the mechanisms of asphalt reversible aging are systematically reviewed in this paper. Secondly, extended bending beam rheometer (Ex-BBR) test and modulated differential scanning calorimetry (MDSC) test are carried out on original asphalt and its oxidative residue. The results show that oxidation has apparently different influence on two physical hardening indicators used in this study. Only three days of non-accelerated physical hardening may produce a more brittle material than accelerated oxidative residue. There is an obvious peak around 25°C in non-reversing heat flow curve of asphalt binder after long-term isothermal conditioning, and it is caused by some imperfect crystals forming fully crystallized structure after long-term conditioning. Both long-term isothermal conditioning and oxidation will increase the amount of crystalline phase and rigid amorphous phase.