Leachate risks of fine solid wastes in porous asphalt pavement and runoff purification effects of diatomite filler

Abstract

Solid wastes have been widely applied in porous asphalt pavement, but some of them may contain pollutants. Whether their leachate during rainfall events poses a threat to nearby watersheds has not received enough attention. Based on the laboratory rainfall and infiltrate test, this study evaluated the leachate risks of fine solid wastes in porous asphalt mixture (PA). Based on the runoff pollution characteristics in Shanghai, China, the purification performance of PA with diatomite filler was explored. The results showed that a small amount of Al and Fe in solid waste fillers might infiltrate during intensive rainfall. The diatomite filler could improve pollutants removal rates via physical filtration and selective chemical adsorption effects. The correlations between rainfall characteristics and the removal rates were further developed, which indicated the increase of rainfall time and intensity adversely affected the removal rates. The composition of PA for different runoff pollution characteristics was proposed as well.