Research Article Changes in Nanoscaled Mechanical and Rheological Properties of Asphalt Binders Caused by Aging Ben Liu, Junan Shen, and Xuyan Song Road Engineering Research Center, Suzhou University of Science and Technology, Suzhou 215011, China Correspondence should be addressed to Junan Shen; shenjunan@hotmail.com Received 28 January 2015; Accepted 30 March 2015 Academic Editor: Changhong Ke Copyright © 2015 Ben Liu et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Aging of an asphalt binder causes the changes in the microstructure and, consequently, in the nanomechanical and rheological properties of the aged asphalt binder. Short-term aging on asphalt binders was simulated using rotating thin flm oven (RTFO). Tese changes in the microstructure and nanomechanical and rheological properties were measured using atomic force microscope (AFM) and dynamic shear rheometer (DSR). Te results indicated that (1) the adhesive force of the asphalt binder from AFM tests was increased afer RTFO aging; (2)  * of the asphalt binder from DSR tests increased afer RTFO aging; (3) the results from AFM were consistent with those from DSR, explaining the mechanism of the changes of rheological properties. 1. Introduction Asphalt binder plays an important role in the performance of asphalt mixture, which accounted for 29% of rut depth at high temperature, according to the strategic highway research program (SHRP) research. Rheology is a very powerful tool for characterizing and quantifying materials properties. Since the rheological properties of asphalt change during production and continue to change subsequently in service, there is necessity to study the phenomenon of aging [1]. As a result of the global climate, air temperature of most areas in China in the summer is higher and higher and lasts for a long time, making the rutting and water damage particularly more prominent than ever before. Te DSR is widely used for char- acterizing asphalt binders and is required for specifcations in many countries. DSR can accurately measure the rheological responses of asphalt flms adhesion to aggregate’s surfaces [2]. As a special material, asphalt binder has viscoelastic property and is more complicated than other pavement materials. Te testing involves using rotating thin flm oven (RTFO) aged binders to mimic the state of binder aging in the mixture beams [3]. Because of its complexity in compositions, the rheological properties of asphalt binder are dependent on the aging, the temperature tested, and the test methods. A number of studies have recognized that binders of nearly identical SHRP performance grades can show diferences in fracture properties that vary signifcantly [4–6]. In order to understand the changes in nanoscale caused by the aging of short and long terms, the frontier of atomic force microscope (AFM) was used to explore the nanomechanical forces. Te adhesion, nanoforce curve, and rheological properties were tested on an asphalt binder before and afer aging through rotating thin flm oven (RTFO) aging. 2. Materials and Methods 2.1. Materials. Tis research used Shell Pen 70# as asphalt. Te properties of Pen asphalt were shown in Table 1. It is indicated from Table 1 that the asphalt conformed to the requirements of the Chinese specifcations. In addition, the materials used for atomic force micro- scope test including acetone solution and carbon disulfde solution are all commercially available. 2.2. Methods. AFM analysis uses BRUKER company’s icon type atomic force microscope. Its principle is that there is a small tip which is very sensitive to the weak force at the other end of micro-cantilever. Tip gently contacted the sample surface, due to the extremely weak repelling force between needle tip atoms and the sample surface atoms, the force will Hindawi Publishing Corporation Journal of Nanomaterials Volume 2015, Article ID 961924, 6 pages http://dx.doi.org/10.1155/2015/961924