Photocatalytic asphalt mixtures: Mechanical performance and impacts of traffic and weathering abrasion on photocatalytic efficiency

Abstract

The photocatalytic asphalt mixture provides safer roads and mitigates the air quality problems, trapping and degrading organic compounds and also harmful gases. In this research, an asphalt mixture was functionalized with nano-TiO2 by bulk incorporation, using the contents 3 and 6%, and by spraying coating using an aqueous solution over its surface at different temperatures and rates. For bulk incorporation, the mechanical performance was assessed. The factors ? application procedure, influence of temperature, spraying rate, incorporation percentage and TiO2 immobilization (from traffic and rain removal) ? were evaluated based on Rhodamine B (RhB) degradation. For bulk incorporation, the best content nano-TiO2 was 3%. The temperature of the substrate has no influence on the photocatalytic results. The most effective spraying rates were 8 and 16?mL/cm2. Before simulating the traffic effect, the spraying coating technique was more effective than the bulk incorporation one. After this process, the opposite behavior was detected. The rain simulation did not cause removal of the nanoparticles. Additionally, the exposed aggregates affected the photocatalytic efficiency, being important their contribution combined to the effect of nano-TiO2. To have the maximum benefit of the techniques studied, the ideal solution would be the combination of both, with negligible impact on mechanical performance.