Physical-chemical-mechanical quantitative assessment of the microstructural evolution in Portland-limestone cement pastes exposed to magnesium sulfate attack at low temperature

0545256 - ÚTAM 2022 RIV GB eng J - Journal Article
Sotiriadis, Konstantinos - Hlobil, Michal - Viani, Alberto - Mácová, Petra - Vopálenský, Michal
Physical-chemical-mechanical quantitative assessment of the microstructural evolution in Portland-limestone cement pastes exposed to magnesium sulfate attack at low temperature.
Cement and Concrete Research. Roč. 149, November (2021), č. článku 106566. ISSN 0008-8846. E-ISSN 1873-3948
R&D Projects: GA ČR(CZ) GJ18-26056Y
Institutional support: RVO:68378297
Keywords : thaumasite sulfate attack * X-ray micro-computed tomography * solid state NMR spectroscopy * nanoindentation * thermodynamic modelling
OECD category: Materials engineering
Impact factor: 11.958, year: 2021
Method of publishing: Limited access
https://doi.org/10.1016/j.cemconres.2021.106566

The changes in structural integrity and microstructure of Portland-limestone cement pastes were investigated in the course of magnesium sulfate attack at low temperature. A deterioration front, consisting of three distinct layers (brucite, gypsum, leached cement matrix), swelled in time due to the expansive nature of the deterioration products, generating cracks and subsequently detaching from the sound cement matrix, continuously promoting the process. Gypsum and thaumasite characterized the leached matrix, which experienced extensive cross-linking of the aluminosilicate structures, as a result of decalcification and dealumination of the calcium silicate hydrates (C–(A–)S–H), impairing the overall mechanical performance. C–S–H of low packing density was most severely affected by the process, as confirmed by the significant drop in nano-mechanical properties. The increased rate of deterioration with limestone content was tentatively attributed to the prevalent morphology of the C–S–H phase. Results were validated by thermodynamic simulations, indicating that the real systems did not reach equilibrium.
Permanent Link: http://hdl.handle.net/11104/0321994