Investigation the permanence under different effects of red asphalt pavements produced using waste and pigment both containing iron oxide (Fe₂O₃)

This doctoral dissertation aims to provide functional, aesthetic, and environmentally sustainable improvements to conventional asphalt pavements through a comprehensive performance evaluation of colored asphalt mixtures produced by incorporating hybrid combinations of industrial waste from Mazıdağı and iron oxide pigments. The primary motivation of the study is to develop an economical and sustainable bulk-coloring solution that reduces the reliance on expensive synthetic pigments while enhancing road visibility and traffic safety. In addition, the research seeks to promote the valorization of large-volume industrial waste materials within an environmentally responsible framework. The experimental program comparatively examined asphalt mixtures containing iron oxide pigment, Mazıdağı waste, optimal hybrid combinations, and surface-painted systems against a control specimen. The mixture design was performed according to the Marshall method, followed by a detailed evaluation under four main categories: color durability, mechanical performance, thermal behavior, and environmental impact. A novel image-processing-based method was developed for the quantitative assessment of color performance. Mechanical tests (Marshall stability, indirect tensile strength, and tensile strength ratio) evaluated the structural integrity of the mixtures, while accelerated UV aging and wheel tracking tests assessed color retention. Surface temperature measurements were used to examine the potential contribution of colored mixtures to Urban Heat Island (UHI) mitigation. Based on the Multi-Criteria Decision-Making (MCDM) analysis, the hybrid mixture containing 2% waste + 4% pigment was identified as the optimal formulation, providing the best balance among color saturation, cost efficiency, and engineering performance. The hybrid mixture exhibited the highest Marshall stability (2494 kg), indicating superior structural integrity. Color retention analyses revealed that bulk-colored systems demonstrated significantly higher resistance to environmental degradation compared to surface-painted mixtures. The environmental impact assessment, conducted through leaching (ICP) analyses, confirmed that the chemical parameters in the leachate remained well below the international drinking-water quality limits, verifying the environmental safety of Mazıdağı waste utilization. In conclusion, this study scientifically verifies the potential use of an industrial by-product as a functional construction material. The developed optimal hybrid mixture successfully integrates high mechanical performance, color durability, and cost-effectiveness, providing a sustainable and innovative foundation for the future development of colored asphalt pavement technologies.