Environmental impacts of reclaimed asphalt pavement on leaching of metals into groundwater. (August 2020)

• Record Type: Journal Article
• Authors: Yang, Qiang; Yin, Huiming; He, Xin; Chen, Fangliang; Ali, Ayman; Mehta, Yusuf; Yan, Beizhan
• Is Part Of: Transportation research. Volume 85(2020)
• Publication Date: 2020-08
• Subjects: Reclaimed asphalt pavement -- Trace element -- Metal -- Column experiment -- Batch extraction -- Soil attenuation; Transportation -- Research -- Periodicals; Transportation -- Environmental aspects -- Periodicals; 354.76
• DOI: 10.1016/j.trd.2020.102415
• Languages: English
• ISSNs: 1361-9209

Abstract

Graphical abstract: Highlights: Fresh hot mix asphalts (HMA) and reclaimed asphalt pavements (RAP) were assessed. Water extractable element concentrations were below MCLs except lead (Pb). Few potential pollutants released from RAPs were largely attenuated by soils. RAPs can be used as unbound materials in non-acidic environments (pH ≥ 5). Abstract: To investigate the environmental impacts of reclaimed asphalt pavement (RAP) while it was freshly processed (i.e. hot mixed asphalt or HMA) and after being subjected to weathering, three RAP materials, namely north-RAP, central-RAP, south-RAP, from three plants and one fresh HMA loose mix sample (Fresh-HMA) throughout New Jersey, USA underwent four different weathering processes including: Ultraviolet (UV) and precipitation weathering on unbounded RAP, UV and precipitation weathering on compacted RAP, weathering by heat and moisture cycles, and groundwater flow-through leaching. Batch experiments were conducted to mimic releasing of trace elements in weak acidic leachate from landfills. North-RAP and central-RAP released levels of Pb greater than the United States Environmental Protection Agency (USEPA) primary drinking water maximum contaminant level (MCL) of 15 µg/L. Novel two-column experiments (a RAP column followed by a soil column) were conducted to investigate the release of trace elements from RAP and the attenuation effect of soil on potential pollutants. The results of these experiments showed that pollutants released from RAPs such as Mn and Ni were largely attenuated in the soil. The results suggest that RAP can be used as an unbound material in environments except those acidic (i.e., pH < 5 as in mines with sulfur-containing minerals and landfills with acidic environment).