Nano-scale moisture damage evaluation of carbon nanotube-modified asphalt

© 2018 Elsevier Ltd In addition to polymer modification, the use of nanomaterials to improve different asphalt properties has recently been found to be beneficial. However, the potential of nanomaterials in pavement engineering still requires extensive evaluation of several unexplored properties. One of the vital properties is resistance to moisture damage, which is a very complex phenomenon. The present nano-scale evaluation addresses moisture damage intensively. In this study, the moisture damage of two different polymers: styrene-butadiene (SB) and styrene-butadiene-styrene (SBS), along with carbon nanotube (CNT)-modified asphalt is evaluated at a nano-level. The modification of the asphalt includes two distinct levels of each polymer (4% and 5%, respectively) with three different levels of CNT (0.5%, 1.0%, and 1.5%). The evaluation at the nano-scale was carried out in terms of changes in adhesion using atomic force microscopy (AFM). The tip in AFM was simulated in such a way that it represented different existing functional groups of the asphalt. Finally, the moisture damage of CNT-polymer modified asphalt was compared with that of the corresponding polymer-modified asphalt. The results revealed that the addition of a certain level of CNT to SB and SBS increases resistance to moisture damage. Based on the evaluation, it is concluded that 1.0% and 1.5% of CNT with 4.0% and 5.0% of either polymer (SB or SBS) respectively, outperformed all the other combinations of the corresponding polymer modified asphalt