Coupled Mechanical and Chemo-Transport Model for the Simulation of Cementitious Materials Subjected to External Sulfate Attack
We propose in this study to develop a chemo-transport-mechanical model for the simulation of external sulfate attack (ESA) in cementitious materials. This degradation mainly consists in the hydrate decalcification/dissolution due to leaching and in the reaction between the sulfate ions migrating within the material and monosulfate initially present to precipitate into ettringite. It may generate macroscopic expansions leading to severe microcracking. The key point in this study is the use of the integration numerical platform ALLIANCES which couples a code solving the chemical equations, the diffusion of ionic species into the porosity, and the mechanical problem. The crystallization pressures resulting from the interaction between growing monosulfate crystals and the surrounding C-S-H matrix are assumed to cause the observed macroscopic swelling. A macroscopic bulk strain tensor calculated from the volume of formed ettringite is introduced for directly reproducing these expansions. Explicit upscaling techniques applied on a simplified representation of the materials allow estimating both mechanical and diffusive properties of the evolving microstructure. Finally, simulations of laboratory tests investigating the effects of ESA on mortar specimens are performed and analyzed. Comparison of the numerical results with experimental ones is performed and discussed.
KeywordsPorosity Crystallization SiO2 Hydrated Gypsum
AREVA NC is gratefully acknowledged for financial support.
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