title: pH-dependent leaching of constituents of potential concern from concrete materials containing coal combustion fly ash.
abstract: Current concerns about the environmental safety of coal combustion fly ash have motivated this evaluation of the impact of fly ash use as a cement replacement in concrete materials on the leaching of constituents of potential concern. The chemical effects of fly ash on leaching were determined through characterization of liquid-solid partitioning using EPA Method 1313 for four fly ash materials as well as concrete and microconcrete materials containing 0% (control materials), 25% and 45% replacement of portland cement with the fly ash source. All source materials, concrete formulations and replacement levels are representative of US concrete industry practices. Eluate concentrations as a function of pH were compared to a broader range of available testing results for international concretes and mortars for which the leaching characteristics of the component fly ashes were unknown. The chemistry of the hydrated cement fraction was found to dominate the liquid-solid partitioning resulting in reduced leaching concentrations of most trace metals compared to concentrations from fly ash materials alone. Compared to controls, eluate concentrations of Sb, As, B, Cr, Mo, Se, Tl and V from concrete products containing fly ash were essentially the same as the eluate concentrations from control materials produced without fly ash replacement indicating little to no significant impact on aqueous partitioning.
authors.affiliation: Department of Civil and Environmental Engineering, Vanderbilt University, VU Station B351831, Nashville, TN 37215, United States. Electronic address: david.kosson@vanderbilt.edu.
authors.forename: David S
authors.initials: DS
authors.lastname: Kosson
authors.affiliation: Department of Civil and Environmental Engineering, Vanderbilt University, VU Station B351831, Nashville, TN 37215, United States.
authors.forename: Andrew C
authors.initials: AC
authors.lastname: Garrabrants
authors.affiliation: Department of Civil and Environmental Engineering, Vanderbilt University, VU Station B351831, Nashville, TN 37215, United States.
authors.forename: Rossane
authors.initials: R
authors.lastname: DeLapp
authors.affiliation: Hans van der Sloot Consultancy, Dorpsstraat 216, 1721 BV Langedijk, The Netherlands.
authors.forename: Hans A
authors.initials: HA
authors.lastname: van der Sloot
mesh_terms: D060729:Coal Ash; D003252:Construction Materials; D006863:Hydrogen-Ion Concentration; D014481:United States; D014484:United States Environmental Protection Agency
chemical_list: D060729:Coal Ash
keywords: Coal combustion fly ash; Concrete; Equilibrium-based leaching; Leaching environmental assessment framework; Microconcrete