Effect of pre-crack on the degradation of cement pastes exposed to a low concentration external sulfate attack
Résumé
Pre-cracked cement pastes were exposed to a 30 mmol/L Na 2 SO 4 solution to assess the influence of pre-existing cracks on degradation caused by a low concentration external sulfate attack. A global chemo-mechanical investigation was performed through SEM-EDS and microindentation analyses in the pre-cracked zone. These results were compared to analyses conducted in a distant zone from the pre-existing cracks to evaluate the effects of the pre-crack on the microstructure evolution. The chemical attack propagated in a characteristic V-shaped pattern around the pre-crack, indicating accelerated ion diffusion and localized degradation. Microtomography acquisitions were performed to monitor crack evolution during degradation. New cracks develop at the boundary between the decalcified and sound zones, with a higher density of cracks occurring near the initial pre-crack. The results suggest that the microcracks are caused by differential strain between the degraded and sound zones of the cement matrix, coalescing with the pre-crack and leading to its widening, promoting further decalcification, mineral precipitation and expansion.
Domaines
| Origine | Publication financée par une institution |
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