Effect of aging on morphology of organo-montmorillonite modified bitumen by atomic force microscopy

Abstract

SummaryThe morphology of unmodified and organo-montmorillonite modified bitumens was investigated by atomic force microscopy. The influence of thin film oven test and ultraviolet aging on the morphology of the binders was also analysed. The atomic force microscopy results showed that bitumen displayed a 'bee-like' structure and the dimension of the 'bee-like' structures was decreased to some extent with the introduction of organo-montmorillonite. Organo-montmorillonite showed a better interaction with the dispersed domains in comparison with the matrix in bitumen, which led to an obvious increase in the contrast between the dispersed domains and the matrix in bitumen. Compared with the unmodified bitumen, the single-phase trend in the organo-montmorillonite modified bitumen could be effectively prevented during thin film oven test and ultraviolet aging, indicating its good aging resistance which was in accordance with changes in physical properties of the organo-montmorillonite modified bitumen before and after aging.

Effect of Nano-zinc Oxide on the Morphology and Ultraviolet Aging Properties of Various Bitumens

“…As shown in Figure 1a, the dispersed domains (the dark-looking region) in bitumen B1 show a succession of pale and dark lines called bee-like structures. According to our previous research, the appearance of bee-like structures can be attributed to the existence of asphaltenes in bitumen (Zhang et al, 2011). After nano-ZnO modification, the dimension of bee-like structures is decreased obviously as well as the average size of particles in bee-like structures.…”

“…In recent decades, increasing researchers have paid attention to the aging of bitumen. Some additives have been used to improve the aging resistance of bitumen, such as antioxidant, montmorillonite, carbon black, and so on (Ouyang et al, 2006;Yu et al, 2009;Zhang et al, 2011;Cong et al, 2012;Feng et al, 2013). However, more attention of the researchers has been paid to the thermo-oxidative aging of bitumen and less to the UV aging as well as its control methods.…”

Effect of organo-montmorillonite on the morphology and aging properties of various bitumens

“…OMMT shows a better interaction with the dispersed phase. It implies that the dispersed phase becomes stiffer with the introduction of OMMT, as discussed in reference [12] . As a result, the difference of interaction leads to the two phases with sharp boundaries with the introduction of OMMT.…”

“…It indicates that the aging resistance of bitumen B1 is improved more remarkably than the other two bitumens after modification. According to AFM analysis, a great association of the dispersed domains in bitumen appears during the thermo-oxidative aging, which contributes to the single phase trend of the bitumen [12] .…”

“…Compared with bitumens B1 and B2, OMMT shows a better improvement on the UV aging properties of bitumen B3 which displays a relative lower softening point increment and viscosity aging index after UV aging. According to AFM analysis, after UV aging the contrast between the dispersed phase and the matrix phase is more obvious than that after thermo-oxidative aging [12] . It implies that there is a difference in sensitivity to UV radiation of the two phases, which leads to the increasing of the difference in composition, adhesion and stiffness among the two phases after UV aging.…”