Experimental Study on the Use of Waste Glass and Fly Ash in the Design of Open-Graded Asphalt Mixtures

Abstract

To support sustainable road infrastructure development and mitigate the environmental impact of industrial and municipal waste, this study explores the use of waste glass, Type C fly ash, and municipal solid waste (MSW) fly ash as partial replacements for conventional aggregates and fillers in open-graded asphalt mixtures. Laboratory experiments were conducted to evaluate the performance of mixtures incorporating varying proportions of waste glass (10, 20, and 30 % by mass of fine aggregates) as a replacement for fine granite aggregate, along with Type C fly ash and MSW fly ash as mineral fillers. These were compared against control mixtures using 100% virgin granite aggregates and stone dust as the filler. The performance of open-graded asphalt mixtures was assessed based on key parameters influencing field performance, including air-void content, permeability, indirect tensile strength (ITS), moisture susceptibility, Marshall stability, resistance to raveling (Cantabro loss), surface macrotexture, and acoustic performance. The results showed that incorporating up to 30% waste glass and using fly ash fillers in open-graded asphalt mixtures had minimal effect on air-void contents. Permeability decreased as waste glass content increased, likely due to reduced void connectivity, contributing to better moisture resistance. MSW fly ash and increasing waste glass content consistently enhanced moisture resistance across both unmodified (PG 67-22) and modified (PG 76-22) binders, while Type C fly ash was more effective in PG 67-22 mixtures. Mechanical strength remained stable or improved slightly, particularly with MSW fly ash. Raveling resistance varied by combination: Type C fly ash reduced it in PG 67-22 mixtures but improved it in PG 76-22 mixtures; MSW fly ash generally improved resistance. Macrotexture depth decreased with more glass, suggesting a potential compromise in surface friction. Furthermore, the incorporation of waste glass and MSW fly ash improved the sound absorption of open-graded asphalt mixtures, indicating potential advantages for noise reduction in pavement surfaces. These findings generally demonstrate the potential of using waste glass and MSW fly ash in open-graded asphalt mixture, offering a sustainable alternative for pavement construction.