Microstructures and thermal aging mechanism of expanded vermiculite modified bitumen: Fid-Bau Portal

Microstructures and thermal aging mechanism of expanded vermiculite modified bitumen

Zhang, Henglong / Xu, Hongbin / Wang, Xiaoliang / Yu, Jianying

Highlights • This work evaluates a novel bitumen modification through the use of expanded vermiculite. • A new approach to determine the microstructures of OEVMt modified bitumen is reported. • Thermal aging properties of OEVMt modified bitumen are evaluated. • Aging mechanism of the binders is revealed by using atomic force microscopy.

Abstract This work evaluates a novel bitumen modification through the use of expanded vermiculite (EVMt) which has been traditionally used as thermal insulation material. In order to improve the compatibility between EVMt and bitumen, EVMt was modified by octadecyl dimethyl benzyl ammonium chloride and marked as organo-expanded vermiculite (OEVMt). A new approach to determine the microstructures of OEVMt modified bitumen was reported by combining the results from X-ray diffraction analysis of OEVMt modified bitumen and the dissolving–filtrating procedure. Aging mechanism of the binders was revealed by using atomic force microscopy (AFM). The results show that OEVMt modified bitumen forms a semi-exfoliated nanostructure. As a result of thin film oven test (TFOT) and situ thermal aging, mass change rate and viscosity aging index are increased, while retained penetration and ductility are decreased of binders. However, these physical changes can be effectively prevented by OEVMt. Aging influences bitumen morphology significantly. TFOT leads to the association of the dispersed domains and the single phase trend of bitumen. These changes are accelerated by situ thermal aging. However, these morphology changes of bitumen are inhibited obviously with the introduction of OEVMt, indicating the good thermal aging resistance of OEVMt modified bitumen with semi-exfoliated nanostructure.