Physical properties of sepiolite clay nanofibers modified bitumen

Bitumen is a material especially used in flexible pavements, runaway in airfields as binder. Several types of modifiers are employed in order to enhance properties of bitumen against permanent deformation and to avoid cracking and deteriorations of pavement. Recently, nanomaterials gain traction in many fields including engineering materials by presenting entirely new properties of materials such as nanoscale particle size, very high surface area, and good suspension ability. This paper describes the physical effects of nanofibers on bitumen as modifier. Sepiolite clay nanofibers having of particle diameter of less than 100 nm was employed in bitumen with amounts of 2%, 3%, and 4% by total weight of mixture. The physical effects of the sepiolite clay on bitumen were investigated by conventional tests such as penetration, softening point and ductility. Storage stability test was performed on modified bitumen to observe the settling condition of modified bitumen during storage. Rolling Thin Film Oven Test (RTFOT) was applied to modified bitumen to investigate effect of the nano modifier on short term aging properties of bitumen. Rotational Ciscometer (RV) and Dynamic Shear Rheometer (DSR) was done to investigate fundamental rheological properties such as viscosity, complex shear modulus and phase angle of sepiolite clay modified bitumen. Nanoclay modification leads to a decrease in penetration, an increase in softening point, and which indicate an increasing stiffness of bitumen. RTFOT results shows that Sepiolite clay nanofibers has a positive effect on short term aging of bitumen while good storage ability of modified bitumen was determined by storage stability test. Increased rutting parameter after modification obtained by DSR test is a clear indication of better rheological properties of bitumen which means permanent deformation occurred in flexible pavement can be restrained by sepiolite clay nanofibers modification. © 2017 Taylor & Francis Group, London.