Evaluating the ageing degrees of bitumen by rheological and chemical indices

Abstract

The ageing of bitumen is an inevitable phenomenon which is still challenging to be characterised. This paper aims at evaluating the ageing degrees of bitumen comprehensively. There were six types of bitumen being aged to five levels for comparing purposes and multiple rheological tests by a DSR as well as chemical test for the SARA (saturates, aromatics, resins and asphaltenes) properties of bitumen were carried out. The critical temperatures, G-R parameter and nonrecoverable-compliance-based ageing indices were proposed to evaluate the ageing degrees of bitumen in terms of low-, intermediate- and high-temperature performance of bitumen, respectively. Also, a novel ageing evaluation index based on the integration of modulus of master curves was employed and modified, which can evaluate the ageing degrees of bitumen accurately in terms of the whole range of temperature. Finally, the chemical ageing index were analysed and was confirmed to have strong linear relationship with rheological indices of bitumen.