Fourier Transform Infrared Spectroscopy characterization of aging-related properties of original and nano-modiﬁed asphalt binders Hui Yao, Qingli Dai, Zhanping You ⇑ Department of Civil and Environmental Engineering, Michigan Technological University, 1400 Townsend Drive, Houghton, MI 49931, USA highlights  Six functional groups containing the carbonyl group were analyzed.  The carboxylic acids, amide and ketones are the primary components.  The mild aging of asphalt enhances the resistance to rutting and moisture damage. article info Article history: Received 20 March 2015 Received in revised form 28 August 2015 Accepted 15 October 2015 Keywords: Asphalt Fourier Transform Infrared Spectroscopy (FTIR) Aging Carbonyl groups abstract The objective of this study is to analyze the effect of aging on asphalt binders under the conditions of dry and sufﬁcient oxygen, and to identify the functional groups related to the fatigue and rutting of asphalt mixtures. During the asphalt aging process, the six functional groups (carboxylic acids, aldehydes, amides, anhydrides, esters and ketones) containing the carbonyl group can be found in the asphalt bin- ders based on the Fourier Transform Infrared Spectroscopy (FTIR) test results and references. The func- tional groups containing the carbonyl group in the asphalt binders can be also used to correlate to the oxidation extent of asphalt binders. Three nanomaterials were added into the control asphalt binder to study the effect of aging. The three materials included polymer modiﬁed nanoclay (PMN), non- modiﬁed nanoclay (NMN) and nanosilica (NS). The rolling thin ﬁlm oven (RTFO) and pressure aging vessel (PAV) aging effects of the asphalt binders were analyzed to understand the functional polar groups in the asphalt system under short- and long-term aging conditions, respectively. The different asphalt binders were tested by FTIR to obtain the spectra of chemical groups. The FTIR characterization results indicate that the carboxylic acids and ketones are the main aging components in the asphalt when exposed to air and oxygen. The esters and aldehydes in the asphalt are kept to a limited amount. Furthermore, these functional groups, along with the carbonyl group are closely related to the susceptibility of rutting and the fatiguing of asphalt mixtures. Ó 2015 Elsevier Ltd. All rights reserved. 1. Introduction Nowadays, asphalt material is widely applied in pavement engi- neering. The properties of asphalt binders determine the perfor- mance of the asphalt pavement. The viscosity of asphalt binders relates to the mixing and compaction temperatures. The modulus of asphalt binders has a connection with the high- and low- temperature performance of asphalt mixtures. In order to improve the performance of pavement, different modiﬁers are mixed with asphalt binders. The modiﬁers include various polymers, different ﬁbers, some waste materials and many kinds of nanomaterials [1,2]. Currently, aging is the main problem with asphalt and anti- aging research in different ﬁelds is still a hot topic. The quality and life of the pavement also relate to the speed of aging of the materials used in asphalt mixtures and cement concretes [3–5]. Oxidation causes the degradation of pavement and decreases the bonding strength between the asphalt and the aggregates. This will lead to pavement embrittlement and pavement distress, par- ticularly pavement cracking [6]. The aging of asphalt is caused by the processes of volatilization, oxidation, and steric hardening. Volatilization and oxidation of asphalt are produced by chemical reactions or the changing of the asphalt structure. Steric hardening http://dx.doi.org/10.1016/j.conbuildmat.2015.10.085 0950-0618/Ó 2015 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. E-mail addresses: huiyao@mtu.edu (H. Yao), qingdai@mtu.edu (Q. Dai), zyou@mtu.edu (Z. You). Construction and Building Materials 101 (2015) 1078–1087 Contents lists available at ScienceDirect Construction and Building Materials journal homepage: www.elsevier.com/locate/conbuildmat