Geochemical modeling of leaching of Ca, Mg, Al, and Pb from cementitious waste forms

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Abstract

Results from extraction tests on cement–waste samples were simulated with a thermodynamic equilibrium model using a consistent database, to which lead data were added. Subsequent diffusion tests were modeled by means of a 3D diffusive transport model combined with the geochemical model derived from the extraction tests. Modeling results of the leached major element concentrations for both uncarbonated and (partially) carbonated samples agreed well with the extraction test using the set of pure minerals and solid solutions present in the database. The observed decrease in Ca leaching with increasing carbonation level was qualitatively predicted. Simulations also revealed that Pb leaching is not controlled by dissolution/precipitation only. The addition of the calcite–cerrusite solid solution and adsorption reactions on amorphous Fe- and Al-oxides improved the predictions and are considered to control the Pb leaching during the extractions tests. The dynamic diffusive leaching tests were appropriately modeled for Na, K, Ca and Pb.

Details

Original languageEnglish
Pages (from-to)1298-1305
JournalCement and Concrete Research
Volume40
Issue number8
DOIs
Publication statusPublished - Aug 2010

Keywords

  • thermodynamic modelling, lead, ordinary portland cement, waste management

ID: 272302