Environmental controls and reaction pathways of coupled de-dolomitization and thaumasite formation

Florian Mittermayr*, Andre Baldermann, Claudia Baldermann, G.H. Grathoff, Dietmar Klammer, Stephan Jürgen Köhler, Albrecht Leis, Laurence Warr, Martin Dietzel

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Deteriorated concrete and interstitial solutions (IS) were collected from Austrian tunnels to elucidate potential connections between de-dolomitization caused by coupled alkali carbonate reactions (ACR) and thaumasite form of sulfate attack (TSA). A conceptual reaction model for the portlandite–CSH phases–dolomite–calcium sulfate–calcite–brucite–thaumasite system was developed based on experimental data, hydrochemical modelling, IS chemistry and apparent concrete compositions. During the initial stage of sulfate attack, ettringite and gypsum formation weakened the concrete's microstructure and initiated ACR. Leaching of hydrated cement phases resulted in IS with a pH ~ 12-13, which promoted incongruent dolomite dissolution. Infiltration of Ca–SO4–type ground water into the de-dolomitization zone facilitated calcite and brucite neo-formations at 13 > pH > 10.5 during advanced states of concrete deterioration and subsequently resulted in thaumasite precipitation at pH ~ 8.7. In this contribution, the reaction mechanisms and environmental controls of de-dolomitization are discussed in relation to the durability of concrete under sulfate attack.
Original languageEnglish
Pages (from-to)282-293
JournalCement and Concrete Research
Publication statusPublished - 2017

ASJC Scopus subject areas

  • Environmental Science(all)

Fields of Expertise

  • Advanced Materials Science

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