Leaching Behavior of Coal Combustion Products and the Environmental Implication in Road Construction [February 2008]

2008Final reportPDFResearch PaperUTC-R17800013830DTRS98-G-0021Fly ashRoad constructionLeachingEnvironmental impactsMaterials testsMissouri University of Science and Technology. Center for Infrastructure Engineering StudiesUniversity Transportation Centers Program (U.S.)Wang, JianminMissouri University of Science and Technology. Center for Infrastructure Engineering StudiesUniversity Transportation Centers Program (U.S.)United States. Department of Transportation. Research and Special Programs AdministrationNTL-ENERGY AND ENVIRONMENT-Environment ImpactsNTL-HIGHWAY/ROAD TRANSPORTATION-Construction and MaintenanceNTL-HIGHWAY/ROAD TRANSPORTATION-MaterialsUS Transportation CollectionThe use of coal fly ash in road base and sub-base applications can provide better properties and performance, and is superior to it being otherwise disposed and becoming a possible environmental liability. Understanding the metal leaching behavior for various fly ashes can help the construction industry and the energy industry in selecting the environmentally benign fly ash for road construction and for other beneficial use applications, and determining the long term environmental impact of fly ash during road construction. Coal fly ash contains many regulated cationic and oxyanionic elements such as antimony, arsenic, barium, boron, cadmium, chromium, cupper, lead, mercury, molybdenum, nickel, and selenium. Due to the implantation of several new air emission control regulations, future fly ash may contain elevated concentrations of volatile trace elements especially oxyanionic elements. Since oxyanionic elements have greater mobility in the environment, being less studied previously, and are generally more toxic than cationic elements, understanding the leaching behavior of oxyanionic elements from fly ash is significant in determining the potential environmental impact of fly ash during disposal or beneficial use, selecting the appropriate fly ash for road construction, and developing methods to control the leaching of oxyanionic elements. This research becomes more urgent due to the implementation of more stringent arsenic standards in drinking water that will become effective in January 2006. This research will focus on the leaching behavior of 6 major oxyanionic elements, antimony, arsenic, boron, chromium, molybdenum, and selenium, for various fly ashes under different management scenarios, using both batch and column experiments. Mathematical models will be developed to quantify the leaching behavior of these elements. Speciation of these oxyanionic elements will be determined using the most advanced Perkin-Elmer HPLC-ICP-MS system available at MST. /Abstract from report summary page/92