R&D result detail

Original Title

Early hydration of C4AF with silica fume and its role on katoite composition

English Title

Early hydration of C4AF with silica fume and its role on katoite composition

Type

WoS Article

Original Abstract

C4AF is considered the least reactive main clinker phase, but its reactivity may be affected by adding supplementary cementitious materials (SCMs). Pure C4AF was synthesised in a laboratory furnace, and the role of silica fume without gypsum on its early hydration properties was monitored. Burning was carried out in four stages to achieve 99% purity of C4AF. Heat flow development was monitored by isothermal calorimetry over 7 days of hydration at 20°C and 40°C. The role of silica fume on hydrogarnet phase katoite (Ca3Al2(SiO4)3 – x(OH)4x x = 1.5–3) formation during early hydration was studied. Rapid dissolution of C4AF, formation of metastable C-(A,F)-H and its conversion to C3(A, F)H6 was evidenced by isothermal calorimetry as a large exotherm. Changes in microstructure during early hydration were documented by SE micrographs, EDS point analyses, X-ray mapping and line scans by SEM-EDS. The phase composition was characterised by DTA-TGA and QXRD after 7 days of hydration. The katoite diffraction pattern is similar for the reference sample and sample with silica fume, but substitution in its structure can be revealed by X-ray microanalyses. The composition of katoite is variable due to the various extent of substitution of 4OH− by SiO44− due to silica fume.

English abstract

C4AF is considered the least reactive main clinker phase, but its reactivity may be affected by adding supplementary cementitious materials (SCMs). Pure C4AF was synthesised in a laboratory furnace, and the role of silica fume without gypsum on its early hydration properties was monitored. Burning was carried out in four stages to achieve 99% purity of C4AF. Heat flow development was monitored by isothermal calorimetry over 7 days of hydration at 20°C and 40°C. The role of silica fume on hydrogarnet phase katoite (Ca3Al2(SiO4)3 – x(OH)4x x = 1.5–3) formation during early hydration was studied. Rapid dissolution of C4AF, formation of metastable C-(A,F)-H and its conversion to C3(A, F)H6 was evidenced by isothermal calorimetry as a large exotherm. Changes in microstructure during early hydration were documented by SE micrographs, EDS point analyses, X-ray mapping and line scans by SEM-EDS. The phase composition was characterised by DTA-TGA and QXRD after 7 days of hydration. The katoite diffraction pattern is similar for the reference sample and sample with silica fume, but substitution in its structure can be revealed by X-ray microanalyses. The composition of katoite is variable due to the various extent of substitution of 4OH− by SiO44− due to silica fume.

Keywords

C(4)AF; hydration; katoite; microstructure; silica fume

Key words in English

C(4)AF; hydration; katoite; microstructure; silica fume

Authors

BOHÁČ, M.; ZEZULOVÁ, A.; KREJČÍ KOTLÁNOVÁ, M.; KUBÁTOVÁ, D.; STANĚK, T.; KREJZA, Z.; VŠIANSKÝ, D.; NOVOTNÝ, R.; PALOVČÍK, J.; DVOŘÁK, K.

RIV year

2025

Released

29.02.2024

Publisher

WILEY

Location

HOBOKEN

ISBN

1365-2818

Periodical

JOURNAL OF MICROSCOPY

Volume

28.2.2024

Number

28.2.2024

State

United Kingdom of Great Britain and Northern Ireland

Pages from

168

Pages to

176

Pages count

9

URL

https://onlinelibrary.wiley.com/doi/full/10.1111/jmi.13280

Full text in the Digital Library

http://hdl.handle.net/

BibTex

@article{BUT188310,
  author="Martin {Boháč} and Anežka {Zezulová} and Michaela {Krejčí Kotlánová} and Dana {Kubátová} and Theodor {Staněk} and Zdeněk {Krejza} and Dalibor {Všianský} and Radoslav {Novotný} and Jakub {Palovčík} and Karel {Dvořák}",
  title="Early hydration of C4AF with silica fume and its role on katoite composition",
  journal="JOURNAL OF MICROSCOPY",
  year="2024",
  volume="28.2.2024",
  number="28.2.2024",
  pages="168--176",
  doi="10.1111/jmi.13280",
  issn="0022-2720",
  url="https://onlinelibrary.wiley.com/doi/full/10.1111/jmi.13280"
}