29Si NMR investigation of the effect of acetic and oxalic acids on Portland-limestone cement hydration

0563761 - ÚTAM 2023 RIV CH eng C - Konferenční příspěvek (zahraniční konf.)
Mazur, A. - Tolstoy, P. M. - Sotiriadis, Konstantinos
29Si NMR investigation of the effect of acetic and oxalic acids on Portland-limestone cement hydration.
Materials Science Forum. Vol. 1071. Baech: Trans Tech Publications, 2022 - (Meile, K.; Cabulis, U.; Kirpluks, M.; Han, Y.; Liang, F.; Dvořák, K.; Gazdič, D.), s. 247-252. ISBN 978-3-0364-0186-7. ISSN 1662-9752.
[International conference on silicate binders (ICBM 2021) /20./. Brno (CZ), 02.12.2021-02.12.2021]
Grant CEP: GA ČR(CZ) GC21-35772J
Institucionální podpora: RVO:68378297
Klíčová slova: Portland-limestone cement * organic additives * hydration * NMR spectroscopy
Obor OECD: Materials engineering
https://doi.org/10.4028/p-73l5m1

The use of carboxylic acids in mix design alters the hydration process of cement, the resulting pore structure of the obtained cement paste, and, consequently, the mechanical properties of concrete. All these changes are directly related to the structure of the calcium silicate hydrate phase. In the present study, the effect of acetic acid and oxalic acid on the hydration of Portlandlimestone cement was monitored using solid state 29Si NMR spectroscopy. The results showed that
acetic acid facilitated alite and belite hydration, however, the formation of polymerized silicate chains, incorporating Q2p species, begun later than in pure cement paste. Oxalic acid accelerated the polymerization, but slowed down alite and belite hydration. Such behaviors may correspond to decreased porosity (acetic acid addition) and increased strength (oxalic acid addition). Both acids accelerated belite hydration, compared to the pure paste, likely due to an increased acidity of the pore solution. The findings provide structural information about C─S─H phase, to be considered for thaumasite sulfate attack investigations on Portland-limestone cement pastes containing carboxylic acids.
Trvalý link: https://hdl.handle.net/11104/0335573