Progress on environmental risk assessment on solid wastes utilized in asphalt pavement

There are broad development prospects for solid waste utilization in the construction of asphalt pavement. As solid wastes may contain heavy metals and other contaminants, the environmental safety is the primary premise of their applications in asphalt pavement. The main utilization modes and current situations of solid wastes in asphalt pavement construction were reviewed. Meanwhile, the research methods of environmental risk assessment of the contaminants in the solid wastes in road use on the groundwater and atmosphere were summarized, and the common leaching methods of heavy metals in solid wastes and cement and concrete introduced. Based on a summary of the mechanism of asphalt-aggregate adhesion and the current heavy metal leaching methods in the use of solid wastes in pavement, the suitability of the quantitative characterization method (leaching method) of pollutants release in the environmental risk assessment of solid wastes utilization in asphalt pavement was discussed. It is concluded that the environmental risk assessment of solid waste pavement can be carried out only by laboratory simulation and in foreign models due to the lack of research on the leaching methods of pollutants in specific scenes. Therefore, the pollutant leaching methods for solid waste use in asphalt pavement should restore actual application scenarios, taking into account the wheel load, ultraviolet radiation and other factors. Finally, it is pointed out that the development of environmental risk assessment standards for solid waste recycling should be the future research trend.