Leaching of Chromium Metal from High Carbon Fly Ash Stabilized Highway Base Layers
Publication: Geo-Frontiers 2011: Advances in Geotechnical Engineering
Abstract
Fly ash produced by power plants in the United States occasionally contains significant amounts of unburned carbon due to the use of low nitrogen-oxide and sulphur-oxide burners in recent years. This ash cannot be reused in concrete production due to its reactivity with air entrainment admixtures and is largely placed in landfills. Roadways have high potential for large volume use of high carbon fly ash (HCFA). HCFA can be activated with lime kiln dust (a disposed residue of lime production plants) and used as the base layer for newly paved roads. However, in such applications, the leaching of heavy metals from fly ash-stabilized base layers can cause significant environmental concerns. A series of column leach tests (CLTs) were conducted to investigate the leaching potential of chromium (Cr) from the fly ash-stabilized soils. The results indicate that an increase in LKD amount, pH, and fly ash content have significant effects on leaching behavior of heavy metals from soil-fly ash mixtures. The leaching of Cr in CLTs exhibited a first flush pattern, and the concentrations quickly decreased to below EPA maximum concentration limits (MCLs) for drinking waters. In addition, a groundwater contamination modeling computer program (WiscLEACH) was used to estimate the Cr concentrations at different depths and distances from the center alignment of the center of the HCFA stabilized base layer.
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Copyright
© 2011 American Society of Civil Engineers.
History
Published online: Apr 26, 2012
ASCE Technical Topics:
- Ashes
- Base course
- Carbon fibers
- Chemical compounds
- Chemical elements
- Chemical processes
- Chemicals
- Chemistry
- Chromium
- Energy infrastructure
- Engineering materials (by type)
- Environmental engineering
- Fibers
- Fly ash
- Infrastructure
- Leaching
- Lifeline systems
- Materials engineering
- Pavements
- Power plants
- Recycling
- Traffic engineering
- Traffic management
- Traffic signs
- Transportation engineering
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