Durability of epoxy-bonded TiO2-modified aggregate as a photocatalytic coating layer for asphalt pavement under vehicle tire polishing

A new approach to construct photocatalytic air-purifying asphalt pavements coated with TiO2 modified aggregate was developed and its feasibility and performance were evaluated. Two methods, namely the surface coating and pore filling methods, were adopted to produce the TiO2 modified aggregate. Their photocatalytic efficiency and mechanical performance under vehicle tire polishing, applied by an Aachen Polishing Machine (APM), were investigated and compared. Results indicated that it is feasible to build durable photocatalytic pavement using the new approach and material spreading process reported in this study. Both TiO2 modification methods provided the spreading aggregate with excellent and comparable NO degradation rates before polishing; however, the pore filling method provided better long-term NO degradation efficiency. The spreading aggregate modified by either method showed excellent long-term skid resistance and surface texture properties after vehicle tire polishing.