Morphological Identification of Latex Modified Asphalt Binder Prepared with Surfactants

Abstract

The microscopic spreadability and storage stability of conventional asphalt binder (PEN 60/70) and 6% natural rubber latex (NRL) modified asphalt binder (with and without the incorporation of surfactant) were investigated in this study. The prepared samples were assessed under both unaged and short-term ageing (RTFO-aged) conditions. Subsequently, the storage stability was conducted on all asphalt binder samples under conditioning condition designated at 180 °C for 72 h. Optical and polarising microscopes were used to observe the surface morphology of asphalt binders. The results revealed that for 6% NRL modified asphalt binder under unaged condition, the formation of globular agglomerated microstructures can be detected. However, the NRL modified asphalt binder that is subjected to RTFO-ageing with the incorporation of different additives yielded homogeneous and interconnected structures with lamellar orientation. This is due to the evaporation and absorption effects, which could have improved the rutting and fatigue resistance of asphalt binders. The storage stability results exhibited similar microstructures with little or no observable morphological differences. Overall, the incorporation of surfactants improved the miscibility, homogeneity, and stability of latex modified asphalt binder.