Hydration study of Portland-limestone cements containing aluminum-containing admixtures with a combination of isothermal calorimetry and FTIR spectroscopy

0577569 - ÚTAM 2024 GR eng A - Abstract
Sotiriadis, Konstantinos - Zárybnická, Lucie - Mácová, Petra - Mazur, A. S. - Tolstoy, P. M.
Hydration study of Portland-limestone cements containing aluminum-containing admixtures with a combination of isothermal calorimetry and FTIR spectroscopy.
2023. s. 195-195.
[International Conference on Instrumental Methods of Analysis. IMA-2023 /13./. 17.09.2023-20.09.2023, Chania]
R&D Projects: GA ČR(CZ) GC21-35772J
Institutional support: RVO:68378297
Keywords : cement pastes * hydratation * isothermal calorimetry * FTIR spectroscopy
OECD category: Materials engineering

The building industry is an increasingly developing sector. The significant environmental footprint of the production processes of cementitious materials calls for urgent solutions to optimise concrete composition and extend its service life. Portland-limestone cements serve this goal as their clinker content is reduced - however, they are known for their susceptibility to cold and humid sulfate-containing environments. The use of calcined clays as minertal admixtures in the binder improves the durability of Portland-limestone cement concrete against chemical attack. This is because of the silicon- and alumina-rich composition of these reactive materials that modifies the structure of cement hydrates. This paper aims to highlight the effect of such composition of the hydration of Portland-limestone cement by comparing two cement pastes prepared from type CEM II/A-LL (LA) and CEM II/B-LL (LB) cements that were admixed with either metakaolin (MK) or aluminium hydoxide (AH). The hydration study was performed with isothermal calorimetry and FTIR spectroscopy. The water-to-binder ratio of the paste was set to 0.45 - a 10% substitution level of cement with the admixtures (by binder mass) was selected. The pozzolanic reaction between MK and the portlandite produced during cement hydration leads to the formation of Si-rich C(a-)S-H, which is more resistant to sulfate attack. Due to the aluminium-rich composition of MK, additional calcium aluminate hydrates form during hydration, while aluminium is incorporated in the silicate chains of cement hydrates. AH was used for comparison with MK, i.e., to 'exclude' the effect of silicon. Silicon-rich nature will differentiate the FTIR signal of Si-O-Si/Si-O-Al bond in the C-(A-)S-H. The hydration id affected because of the use of MK/AH. The understanding of the hydration process of the used binders is a key to assess the final durability properties.
Permanent Link: https://hdl.handle.net/11104/0346687