Kinetics of enforced carbonation of cement paste

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  • Maciej Zajac, Global R&D HeidelbergCement AG
  • ,
  • Jørgen Skibsted
  • Pawel Durdzinski, Global R&D HeidelbergCement AG
  • ,
  • Frank Bullerjahn, Global R&D HeidelbergCement AG
  • ,
  • Jan Skocek, Global R&D HeidelbergCement AG
  • ,
  • Mohsen Ben Haha, Global R&D HeidelbergCement AG

The carbonation mechanisms of ground, hydrated cement pastes that mimic recycled concrete fines are investigated under direct wet carbonation. The carbonation is a sequential processes including dissolution of the hydrates, transport of the dissolved material to the precipitation sites and precipitation of the reaction products. During the first stages of carbonation, when portlandite reacts, the reaction is limited by the amount of dissolved CO2 and potentially by the calcite precipitation rate. When portlandite is depleted, the kinetics is dominated by the dissolution of other hydrates and diffusion of calcium into the solution. The main carbonation products are calcite and an alumina-silica (hydrate) gel. The hydrotalcite-like phase appears to be stable towards carbonation under the experimental conditions employed in this work. The CO2 concentration and the paste composition have a limited influence on the reaction mechanisms as well as on products formed.

Original languageEnglish
Article number106013
JournalCement and Concrete Research
Volume131
ISSN0008-8846
DOIs
Publication statusPublished - May 2020

    Research areas

  • Alumina-silica gel, Calcite, CO, Concrete recycling, Reaction kinetics

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