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Effect of sulfate on CO2 binding efficiency of recycled alkaline materials

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  • Maciej Zajac, Heidelberg Cement AG
  • ,
  • Jørgen Skibsted
  • Barbara Lothenbach, Swiss Federal Laboratories for Materials Science and Technology (Empa)
  • ,
  • Frank Bullerjahn, Heidelberg Cement AG
  • ,
  • Jan Skocek, Heidelberg Cement AG
  • ,
  • Mohsen Ben Haha, Heidelberg Cement AG

CO2 mineralization using alkaline waste materials and by-products is a promising technology to reduce CO2 emissions. This work investigates the impact of alkali sulfates on the carbonation process. Detailed investigations of the carbonation reaction show that the sulfates are important phases impacting the mineralization. Alkalis alone accelerate the kinetics and change the morphology of the precipitated phases. Sulfates additionally reduce the amount of CO2 mineralized since a part of calcium precipitates as calcium sulfate. The mutual interaction between alkalis and sulfate ions provides a tool to control the mineralization kinetics and especially the extent of carbonation by preventing calcium sulfate precipitation at surplus of alkalis. Furthermore, sulfate-containing materials, which so far have not been considered as suitable for CO2 mineralization (e.g. gypsum), can now be considered for CO2 sequestration. A modification of the Steinour formula, used for calculations of the carbonation potential, is proposed to account for the observed effects.

Original languageEnglish
Article number106804
JournalCement and Concrete Research
Number of pages18
Publication statusPublished - Jul 2022

    Research areas

  • Carbonation, CO2 sequestration, Kinetics, Mechanisms, Recycling

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