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

Journal Article · Mon Nov 15 04:00:00 EST 2021 · Cement and Concrete Research

DOI:https://doi.org/10.1016/J.CEMCONRES.2021.106566· OSTI ID:23206202

Sotiriadis, Konstantinos; Hlobil, Michal; Viani, Alberto; Mácová, Petra; Vopálenský, Michal ^[1]

---

1. Institute of Theoretical and Applied Mechanics of the Czech Academy of Sciences, Prosecká 809/76, Prague, CZ-19000 (Czech Republic)

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)SH), impairing the overall mechanical performance. CSH 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 CSH phase. Results were validated by thermodynamic simulations, indicating that the real systems did not reach equilibrium.

• OSTI ID: 23206202
• Journal Information: Cement and Concrete Research, Journal Name: Cement and Concrete Research Vol. 149; ISSN 0008-8846; ISSN CCNRAI
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CALCIUM SILICATES
COMPUTERIZED TOMOGRAPHY
CRACKS
CROSS-LINKING
GYPSUM
HYDRATES
LAYERS
LEACHING
LIMESTONE
MAGNESIUM SULFATES
MECHANICAL PROPERTIES
MICROSTRUCTURE
NUCLEAR MAGNETIC RESONANCE
PORTLAND CEMENT
SIMULATION
SOLIDS
SPECTROSCOPY
THERMODYNAMICS
X RADIATION