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Durability of cement pastes exposed to external sulfate attack and leaching: Physical and chemical aspects

Abstract : Keywords: External sulfate attack Structure durability Sulfate ingress Microstructure Leaching A B S T R A C T Sulfate ions in seawater or underground can attack the cement paste leading to expansion and strength loss. This expansion is usually related to ettringite and gypsum precipitation. This study aims to characterize the possible altered zone and to identify the mechanisms of degradation under such conditions. For this study, cement pastes manufactured using CEM I with two w/c ratios (0.45 and 0.60) were exposed to sodium sulfate solutions (semi-immersion at a controlled pH = 8.0 ± 0.1) after one year of curing in water. The analysis of the physical aspect of this phenomenon shows that two modes of transfer occur: transfer of sulfate ions to the cement matrix and leaching of calcium ions to the external solution. The analysis of the chemical composition of the affected material highlights the progressive consumption of portlandite at the surface, the decalcification of C-S-H and the formation of AFt from both Afm and aluminium incorporated in C-S-H.
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https://hal.archives-ouvertes.fr/hal-02362091
Contributor : Bruno Bresson <>
Submitted on : Sunday, November 17, 2019 - 9:42:46 AM
Last modification on : Sunday, April 25, 2021 - 2:08:01 PM

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Rim Ragoug, Othman Omikrine Metalssi, Fabien Barberon, Jean-Michel Torrenti, Nicolas Roussel, et al.. Durability of cement pastes exposed to external sulfate attack and leaching: Physical and chemical aspects. Cement and Concrete Research, Elsevier, 2019, 116, pp.134-145. ⟨10.1016/j.cemconres.2018.11.006⟩. ⟨hal-02362091⟩

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