Decomposition temperature of calcium carbonate in lime binders aged at elevated carbon dioxide concentration monitored by TGA/MS analysis

0561613 - ÚTAM 2023 RIV SI eng C - Conference Paper (international conference)
Frankeová, Dita - Válek, Jan - Slížková, Zuzana
Decomposition temperature of calcium carbonate in lime binders aged at elevated carbon dioxide concentration monitored by TGA/MS analysis.
Proceedings of the 6th Historic Mortars Conference - HMC 2022. Ljubljana: University of Ljubljana, 2022 - (Bokan Bosiljkov, V.; Padovnik, A.; Turk, T.; Štukovnik, P.), s. 31-39. ISBN 978-961-6884-77-8.
[Historic mortars conference HMC 2022 /6./. Lublaň (SI), 21.09.2022-23.09.2022]
R&D Projects: GA MK(CZ) DG20P02OVV028
Keywords : TGA/MS * mortars * lime binders
OECD category: Materials engineering

Calcium carbonate is the main component of lime binders, and the determination of its content is the basis of the chemical-mineralogical analysis of historical mortars. The study is focused on monitoring the decomposition temperature of calcium carbonate of various lime binders exposed to accelerated ageing. The samples were exposed to 1% CO2 and periodically saturated with water for 540 days. After 30, 180 and 540 days, thermal analysis (TGA/MS) was performed to monitor changes in the mineralogical composition of the binders. The content of calcium carbonate decomposing in the temperature ranges 450-650°C (CO2 I) and 650-850°C (CO2 II) and the content of chemically bound water (100-450°C) was determined. The obtained results show that four of the six binders had not significantly changed by the accelerated ageing. This indicates the resistance of the binders to both the elevated concentration of carbon dioxide and water, probably because all present phases carbonated before the start of the experiment. The study suggests that the chemically bound water most probably does not come from the dehydration of the CSH phases but is released from the silica gel, which is a product of their carbonation. However, the accelerated ageing significantly changed the thermal analysis curves of the two binders. These were experimentally burned binders – a natural hydraulic lime and a Roman cement. The different response of these two binders to the ageing is likely caused by the presence of larger particles associated with the technological processes of their production.
Permanent Link: https://hdl.handle.net/11104/0334293