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Enhanced Metakaolin Reactivity in Blended Cement with Additional Calcium Hydroxide

Weise, Kira ; Ukrainczyk, Neven ; Duncan, Aaron ; Koenders, Eduardus (2022):
Enhanced Metakaolin Reactivity in Blended Cement with Additional Calcium Hydroxide. (Publisher's Version)
In: Materials, 15 (1), MDPI, e-ISSN 1996-1944,
DOI: 10.26083/tuprints-00021224,

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Item Type: Article
Origin: Secondary publication via sponsored Golden Open Access
Status: Publisher's Version
Title: Enhanced Metakaolin Reactivity in Blended Cement with Additional Calcium Hydroxide
Language: English

This study aims to increase the pozzolanic reactivity of metakaolin (MK) in Portland cement (PC) blends by adding additional calcium hydroxide (CH_add) to the initial mixture. Cement paste samples were prepared with PC, MK and water with a water-to-binder ratio of 0.6. Cement replacement ratios were chosen from 5 to 40 wt.% MK. For higher replacement ratios, i.e., 20, 30 and 40 wt.% MK, CH_add was included in the mixture. CH_add-to-MK ratios of 0.1, 0.25 and 0.5 were investigated. Thermogravimetric analysis (TGA) was carried out to study the pozzolanic reactivity after 1, 7, 28 and 56 days of hydration. A modified mass balance approach was used to normalize thermogravimetric data and to calculate the calcium hydroxide (CH) consumption of samples with CH_add. Results showed that, without CH_add, a replacement ratio of 30 wt.% or higher results in the complete consumption of CH after 28 days at the latest. In these samples, the pozzolanic reaction of MK turned out to be restricted by the amount of CH available from the cement hydration. The increased amount of CH in the samples with CH_add resulted in an enhanced pozzolanic reaction of MK as confirmed by CH consumption measurements from TGA

Journal or Publication Title: Materials
Volume of the journal: 15
Issue Number: 1
Place of Publication: Darmstadt
Publisher: MDPI
Collation: 19 Seiten
Classification DDC: 600 Technik, Medizin, angewandte Wissenschaften > 600 Technik
Divisions: 13 Department of Civil and Environmental Engineering Sciences > Institute of Construction and Building Materials
Date Deposited: 03 May 2022 11:16
Last Modified: 23 Aug 2022 08:59
DOI: 10.26083/tuprints-00021224
Corresponding Links:
URN: urn:nbn:de:tuda-tuprints-212240
Additional Information:

Keywords: supplementary cementitiousmaterials (SCMs); pozzolanic reaction; calcined clay;metakaolin; thermogravimetric analysis (TGA); calcium hydroxide

URI: https://tuprints.ulb.tu-darmstadt.de/id/eprint/21224
PPN: 494559748
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