Optimizing Nickel Slag in Stone Matrix Asphalt: A Sustainable Alternative to Natural Coarse Aggregate

This study investigated the potential of utilizing water-cooled Nickel Slag (NS) as a replacement for Crushed Stone (CS) in Stone Matrix Asphalt (SMA) mixtures, where structural strength relied on aggregate interlocking. Key empirical parameters from the Marshall test, including stability, flow, Void in Mix (VIM), Void in Mineral Aggregate (VMA), and asphalt drainage, were assessed across asphalt content levels of 6%, 6.25%, 6.5%, 6.75%, and 7%. The results indicated that the optimum Marshall characteristics for SMA mixtures using 100% NS as coarse aggregate occurred at an asphalt content of 6.25%, corresponding to those of conventional CS mixtures. Additionally, they exhibited high stability and low flow, enhancing resistance to rutting and permanent deformation, while their low asphalt absorption reduced binder demand. These finding suggests that NS is a viable, cost-effective alternative to natural aggregates.