Chemical composition of leakage water from asphalt

摘要

This study aims to determine the environmental effects of both asphalt covering the ground and used road asphalt stored for later recycling. As cities grow and new roads are built, an increasing proportion of land in urbanized areas is covered with asphalt. Although asphalt is already being recycled to some extent, a sustainable environment requires a greater degree of recycling. From May 1996 to June 1997, a field experiment was carried out at Chalmers University of Technology in Gdteborg, Sweden. Three 0.22 cubic meter lysimeters were filled with different kinds of asphalt. The material had different environmental and storage histories. Both the outlet water and the precipitation were analysed with regard to pH, alkalinity, conductivity and the presence of different compounds, such as chloride, iron, sulphate, nitrate, copper, zinc and manganese. Physical properties, such as grain size distribution, were also evaluated. The study shows that the three types of asphalt have high buffering capacity, with pH-values around 7.5. The conductivity and concentrations of the different compounds are sometimes higher than the Swedish drinking water standards; however it is most significant that they decline and reach an almost stable value after three to six months.