Evaluation of ageing behaviors of asphalt binders using FTIR tests
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International Journal of Pavement Research and Technology Journal homepage: www.springer.com/42947
Evaluation of ageing behaviors of asphalt binders using FTIR tests Yihua Niea,b*, Wenjing Gaob, Chenyang Zhoub, Peihan Yub, Xiaojin Songc a
Key Laboratory of Road Structure and Material of Ministry of Transport (Changsha), Changsha University of Science & Technology, Changsha 410114, China b School of Civil Engineering, Hunan University of Science and Technology, Xiangtan 411201, China c Hunan Zhongda Construction Engineering Testing Technology Co., Ltd., Changsha 410205, China Received 6 July 2020; received in revised form 2 November2020; accepted 8 November 2020
Abstract
The main objective of this study was to evaluate ageing behaviors of matrix and modified asphalt binders using different Four ier transform infrared (FTIR) spectral indices, based on FTIR tests. These FTIR indices include normalized carbonyl (C=O) absorption peak area (A1700), normalized sulfoxide (S=O) absorption peak area (A1030), carbonyl index (CI) and sulfoxide index (SI) based on five different reference groups. Th e rolling thin film oven test (RTFOT) was applied to simulate thermal oxidation ageing. Then, physical properties tests (softening point, penetration, duct ility, and viscosity) and FTIR tests were conducted on the studied asphalt binders (AH-50, AH-70, AH-90 matrix asphalt, and SBS-70 modified asphalt) with different ageing states. Meanwhile, ageing behaviors and their relationship characterized by the physical parameters and FTIR indices were studied and discussed. The results show that the changes with ageing time of FTIR indices and physical parameters are in accordance with ageing kinetics law, and normalized A1700, CI can interpret the ageing behavior as well as physical parameters. Normalized A1700 is easier to obtain and recommended as the opt imal ageing evaluation index among FTIR indices. The evaluation results of asphalt anti-ageing ability by selected FTIR indices are consistent, and SBS-70 modified asphalt exhibits the best ageing resistance among all tested technical parameters. Keywords: Asphalt binder; Thermal oxidation ageing; FTIR indices; Ageing kinetics; Ageing rate
Introduction The asphalt binder is primarily composed of a mixture of hydrocarbons combined with O, N, S and traces of metals and is of large molecule number with different chemical structures [1-4]. As the binding material of the asphalt mixes for pavement construction, asphalt ageing is a common phenomenon and very complex process [5-8]. Different environments induce different ageing behaviors including thermal oxygen ageing, ultraviolet ageing, and moisture ageing [9-14]. The oxidative ageing reaction causes the asphalt binder to become stiffer and more brittle under sufficient supply of reactive oxygen species, mostly because of association of polar components in the asphalt binder [15].The thermal oxygen ageing of asphalt binder mostly occurs in shortterm during mix production and pavement construction and longterm throughout the pavement s
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