Journal of Materials in Civil Engineering, vol.35, no.1, 2023 (SCI-Expanded)
© 2022 American Society of Civil Engineers.Given the importance of pavement surface, many transportation agencies have developed technical specifications to serve as a baseline for ensuring the quality of initial pavement roughness after paving works, monitoring it over time as an indicator of serviceability, and then referring to it as a threshold for strategic scheduling of pavement repair and maintenance works. Past studies have shown that various external factors are involved in determining pavement roughness; however, how principal asphaltic design parameters may affect initial pavement roughness has not been examined so far. To close this gap, this study investigated the contribution of the basic concepts of the Marshall mixture design method and individual constituent properties by analyzing the international roughness index (IRI) values of the asphalt wearing course of nine different roads with a total length of 435 km. The evidence from this study suggested that the strongest relationship at the mixture level was observed between Marshall stability and IRI, whereas optimum bitumen content had no influence on IRI. At the ingredient level, among various material properties, the specific gravity of fine aggregate was found to have the most pronounced effect on IRI. Consequently, particular attention should be devoted to these two factors to further improve IRI values at the mixture design stage.