Influence of limestone as main constituent in Portland cement on the chloride ingress in pastes exposed to sulfate-chloride solution assessed by Raman and NMR spectroscopy

0577568 - ÚTAM 2024 RIV GR eng A - Abstract
Mácová, Petra - Sotiriadis, Konstantinos - Mazur, A. S. - Tolstoy, P. M.
Influence of limestone as main constituent in Portland cement on the chloride ingress in pastes exposed to sulfate-chloride solution assessed by Raman and NMR spectroscopy.
2023. s. 196-196.
[International Conference on Instrumental Methods of Analysis. IMA-2023 /13./. 17.09.2023-20.09.2023, Chania]
Institutional support: RVO:68378297
Keywords : micro-Raman spectroscopy * cementitious materials * NMR spectroscopy * X-ray powder diffraction XRPD
OECD category: Materials engineering

The durability of cementitious materials in aggressive environments is significant concern in civil engineering practice. This study aims to investigate the microstructural changes occurring in two different cement pastes made from type CEM I ordinary Portland cement (PC) and type CEM II/B-LL Portland limestone cement (PLC), during exposure to sulfate-chloride solution and, therefore, assess the chloride ingress in relation to the presence of limestone in the cement. The cylindrical specimens were exposed to a sulfate-chloride solution and a solution containing only chlorides for 5 months at low temperature (5°C). Subsequently, the changes in microstructure at different depths were analyse using micro-Raman spectroscopy, 29Si solid-state nuclear magnetic resonance (ss NMR) spectroscopy, and X-ray powder diffraction (XRPD). The results revealed notable variations among the different combinations of cements and corrosive environments. The distribution of phases within the hydrated pastes shows significant influence of the presence of limestone in cement and sulfates in the corrosive solutiuon closer thew specimen's surface, indicating degradatin of main binding phase (C-S-H) and the formation of crystalline products (gypsum, ettringite, thaumasite, Friedel's ssalt). The findings highlight the influence of Ca/Si ratio of the cement used, and the presence of sulfates in the solution on the resistence against chloride ingress.
Permanent Link: https://hdl.handle.net/11104/0346686