Reclaimed Asphalt Pavements and Contaminant LeachingA Literature Review Study
Additional Document Info
ASCE. Similar to global practices, reclaimed asphalt pavement (RAP) materials that are milled from dense-graded (DG) mixes are usually recycled into new DG mixes in New Zealand (NZ). However, RAP millings from porous asphalt (PA) are only used as fill, drainage materials, or as dust mitigation layers on unsealed roads. Due to the projected increase in road works on NZ (Auckland) motorways, more PA-derived millings will be stored on sites and be used in low value recycling applications until a way of recycling these PA millings into new asphalt mixes, especially high value PA, is found. Unlike DG mixes, PA has the ability to improve stormwater quality through pollutant filtration, including heavy metals, by its internal porous structure. In the case of DG mixes, pollutants are directly washed off from the pavement surface into the stormwater. Thus, PA-derived RAP may have a higher risk of pollutant leaching than DG-derived RAP. This paper summarizes a comparative literature review study on the assessment of pollutant leaching potential from RAP materials to determine what effect it can have on the current NZ practices with respect to RAP storage, use, and environmental issues.