Organically treating montmorillonite with dual surfactants to modify bitumen

Abstract

The contradiction between complex compositions of bitumen and the mono organic treatment on the montmorillonite (Mt) has not been fully considered during preparing bitumen-montmorillonite nanocomposite. In this study, dual surfactants, benzyl dimethyl stearyl ammonium chloride (S1) and octadearyl dimethyl ammonium chloride (S2), were adopted to treat the Mt together to increase its compatibility with bitumen. The structure of dual organically-treated Mt was characterized and its relation to the improvement of bitumen’s properties was studied. The results indicated that S1 surfactant containing the benzene ring with a larger volume increased the interlayer space of Mt more. After mixing with bitumen, the mono and dual organically-treated Mts had almost the same basal spacing. Based on the principle of the dissolution in a similar material structure, more oil components of bitumen entered the interlayer space of Mt when it contained more S2 surfactant, and more aromatic components of bitumen did this when more S1 surfactant. The bitumen modified by mono S2 treated Mt had better PAV ageing resistance due to the protection of the oily components of bitumen from volatilization. However, the bitumen modified by dual organically-treated Mt had better resistance to the UV ageing due to the reduction of oxidation, as well as of volatilization. Therefore, it was more useful to adopt the dual organically-treated Mt to modify bitumen, and consequently to improve the durability of asphalt pavement.