Ozone treatment of asphalt exhaust

Abstract

Asphalt is a semi-solid to liquid hydrocarbon material with a brownish-black color, widely used in road construction and maintenance. When heated to high temperatures during paving operations, asphalt generates volatile organic compound (VOC) fumes containing polycyclic aromatic hydrocarbons (PAHs), posing significant occupational health hazards. This study investigated the physical characteristics of asphalt cement AC 60/70, measured total volatile organic compound (TVOC) fume concentrations generated at heating temperatures of 100°C, 200°C, and 300°C for asphalt masses of 5, 10, and 15 g, and evaluated the efficiency of ozone (O₃) treatment for fume removal using batch and continuous flow processes at 5 ppm ozone concentration. The average density of asphalt was 1.046 g/cm³. At 100°C and 200°C, equilibrium TVOC concentrations remained generally below the occupational exposure limit (OEL) of 0.5 mg/m³ established by NIOSH and ACGIH. At 300°C, concentrations reached 10 mg/m³, exceeding the OEL 20-fold, with an average fume release rate in the range of 1.192×10^-3 - 4.966×10^-3 mg/min. Ozone treatment achieved 100% fume removal efficiency: the batch process required 10–20 minutes and the continuous flow process required 16–30 minutes, depending on asphalt mass. These results demonstrate that ozone treatment is a highly effective approach for controlling asphalt exhaust emissions in occupational environments.