Thermodynamic modeling of sulfate interaction

Author(s): B. Lothenbach, W. Kunther, A.E. Idiart
Paper category: Conference
Book title: Concrete Repair, Rehabilitation and Retrofitting III (ICCRRR)
Editor(s): M.G. Alexander, H.-D. Beushausen, F. Dehn, P. Moyo
Print ISBN: 978-0-415-89952-9
Publisher: Taylor & Francis Group
Pages: 519- 520
Total Pages: 2
Language: English

Abstract: 
The expansion of mortars caused by external sulfate attack is significantly reduced by the presence of bicarbonate in the interacting solution. CaCO₃ is formed near the surface. Thermodynamic modeling confirms that CaCO₃ binds most of the available CaO and thus reduces the formation of ettringite. Thermodynamic modeling is a versatile tool to predict the changes in the phase assemblage associated with cement-sulfate interaction. Direct linking of the amount of ettringite and/or other solids formed with the macroscopically observed expansion, however, is not possible. Although sulfate attack generally leads to macroscopic expansion, the amount of newly formed solid is typically too small to fill all the available pores. Previous modeling efforts following crystallization pressure theory indicated that the consideration of an oversaturated solution and the subsequent development of crystallization pressure in small pores is not sufficient to adequately model the experimentally observed expansions. An improved understanding of the microstructural features responsible for expansion is thus needed.

Online publication: 2014
Publication Type: abstract_only
Public price (Euros): 0.00