Influence of fumed silica nanoparticles on the rheological and anti-aging properties of bitumen

Abstract

Inorganic nanofillers such as nano silica (nano-SiO2) modifiers can enhance the rheological and anti-aging performance of bitumen. However, nanoparticles are susceptible to aggregation and are considered costly for modifying a bituminous pavement. In this study, fumed silica nanoparticles (FSNs) are proposed as a novel bitumen modifier, which is only 1/10 the price of conventional nano-SiO2. The properties of FSNs are compared with those of organically modified nano-SiO2 (MNS) and ordinary SiO2 (OS) particles. Firstly, the surface morphology of OS, MNS, and FSNs is examined through field emission scanning electron microscopy (FESEM). The rheological, chemical, and thermal properties of base and silica-modified bitumen are investigated before and after different aging methods. The results reveal that FSNs readily form a network structure in the bitumen matrix, which effectively enhances the bitumen's elasticity and deformation resistance at high temperatures. Furthermore, regardless of the aging method used, FSNs dramatically reduce the complex modulus aging index of bitumen, demonstrating their resistance to thermo-oxidative degradation and ultraviolet radiation aging. The Fourier transform infrared (FTIR) spectra indicate that FSNs effectively reduce the carbonyl index of bitumen due to their chemical stability and barrier properties. The differential scanning calorimetry (DSC) results show that the glass transition temperature (Tg) of FSN-modified bitumen does not change much after aging, which is due to the inhibition of the conversion of light components into asphaltene during the aging process. Therefore, the FSNs can be considered as a cost-effective and promising modifier for increasing the durability of bitumen.