The impact of waste iron powder on the mechanical properties of microsurfacing asphalt mixtures

This study presents a method to investigate the impact of using a Waste Iron Powder Filler (WIPF) as a partial replacement for a Natural Siliceous Aggregate Filler (NSAF) to enhance the performance and mechanical properties of the microsurfacing mixture. Initially, WIPF’s chemical and physical properties were examined using X-ray fluorescence (XRF), Fourier Transform Infrared Spectrometer (FTIR), and Scanning Electron Microscope (SEM) analyses. Subsequently, the mixtures were prepared in four combinations comprising 0%, 1%, 2%, and 3% WIPF relative to the total volume of dry aggregates. The impact of WIPF on Microsurfacing was assessed by formulating mixtures following the guidelines of the International Slurry Surfacing Association (ISSA) A143. To this end, mixing time test, wet cohesion test, wet track abrasion test, Load Wheel Test-Sand adhesion, and Load Wheel Test -Displacement were performed. Furthermore, the resistance to cracking was examined by conducting the three-point bending test on Edge Notched Disk Bend (ENDB) specimens. The mixture design in all combinations complied with the specifications outlined in the ISSA A143 guideline. The mixture incorporating 2% WIPF demonstrated the most desirable performance. This mixture showed a 19% increase in cohesion based on the Wet Cohesion Test at 60 min, a 44% increment in resistance to aggregate loss according to the Wet Track Abrasion Test at 60 min, a 22% reduction in bleeding as per the Load Wheel Test-Sand adhesion, and 35% increase in resistance to rutting according to the Load Wheel Test -Displacement compared to the control mixture. According to the results obtained from the three-point bending test performed on ENDB specimens, the increase in WIPF consumption enhanced the fracture energy and fracture toughness at break temperatures of 0℃ and -18℃. Overall, this study revealed the appropriate performance of microsurfacing asphalt containing WIPF for practical applications.