Investigating the rheological properties and microstructural analysis of Nano-expanded Perlite modified asphalt binder

The utilization of additives to improve the properties of asphalt binders has attracted considerable attention in recent years. This study aims to improve asphalt binder performance and damage resistance in asphalt pavements by incorporating Nano-Expanded Perlite (NEP) as a modifier. Asphalt binders were modified with varying percentages of NEP (0%, 2%, 4%, and 6%) and characterized using conventional and performance tests [i.e., rotational viscosity (RV), dynamic shear rheometer (DSR), bending beam rheometer (BBR)] to evaluate their rheological properties. Microstructural analyses, including X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDS), and Fourier-transform infrared spectroscopy (FTIR), were also conducted. The findings revealed adding up to 6% NEP increased the softening point, complex modulus (G⁎), and viscosity while decreasing penetration grade, phase angle (δ), and ductility of the modified asphalt binder. NEP improved the high-temperature performance grade by one grade and enhanced rutting resistance without adversely affecting the low-temperature cracking resistance. Furthermore, NEP-modified binder demonstrated good performance at intermediate and low temperatures despite increased binder stiffness. The microstructural analyses indicated uniform dispersion of NEP elements on the modified binder surface, and the Si element from the Perlite nanoparticles exhibited the highest proportion in the modified asphalt binder, acting as fillers within the binder matrix. Overall, these characteristics of Perlite enabled it to enhance the rheological properties and performance of the asphalt binder, acting as an effective modifier when incorporated into the binder and displaying favorable performance at various temperature conditions.