The effect of gel-type contributions in lime-sand bricks, alkali-activated slags and CEMI/CEMIII pastes: Implications for next generation concretes

Research output: Contribution to journalArticleResearchpeer review

Authors

  • Claus Henning Rüscher
  • Ludger Lohaus
  • Fongjan Jirasit
  • Hervé Kouamo Tchakouté

External Research Organisations

  • Rajamangala University of Technology Lanna (RMUTL)
  • University of Yaounde I
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Details

Original languageEnglish
Article number9
JournalGels
Volume8
Issue number1
Early online date23 Dec 2021
Publication statusPublished - Jan 2022

Abstract

Lime-sand bricks of different ages were investigated using IR-spectroscopy, thermogravimetry, and X-ray diffraction/scattering. After subtraction of the dominant quartz contribution (80%), the IR spectra show the absorption peaks of the hydrothermally formed binder phases. The spectra also show the alteration of the binder during ageing under atmospheric conditions by the influence of CO2 forming carbonate and a condensed SiO2-gel (secondary gel). The alteration could also be proven in X-ray pattern, obtaining a separation between crystalline CSH and amorphous contributions in the freshly produced lime-sand brick, too. Here, the formation of CSHamorph could be understood as a precursor state (primary gel) to the crystallization of CSH phases. X-ray patterns of aged bodies of alkali-silicate solution activated slags (AAS), CEM-I/CEM-III pastes, and CEM-I concrete indicate that in all cases a similar amorphous CSH-type phase (CSHamorph) was formed, which is responsible for the hardening properties as the glue. The main X-ray peak of CSHamorph obtained using CuKα-radiation with a usual diffractometer is observed between 24 and 35 2 Theta with maximum at about 29 2 Theta, whereas it appears much more broadly distributed between 15 and 35 2 Theta with maximum between 26 and 28 2 Theta for a geopolymer body prepared using the reaction of alkali-silicate solution and metakaolin (AAMK). This is due to the network formed by siloxo and sialate units in the case of AAMK, given that any crystallization can be ruled out. The origin of increasing mechanical strength during the ageing of AAS mortars must be due to further crosslinking of the preformed siloxo chains. Thermal treatment up to 800C leads to a complete loss of any mechanical strength of the CEM pastes due to the destruction of crystalline CSH-phases, whereas geopolymer bodies maintain their strength. Implications for next generation concrete include that cement clinker could be completely replaced by using a using alkali silcate solution technology for gel formation.

Keywords

    Alkali-activated materials, Concretes, Geopolymer-gel, Lime-sand-brick

ASJC Scopus subject areas

Cite this

The effect of gel-type contributions in lime-sand bricks, alkali-activated slags and CEMI/CEMIII pastes: Implications for next generation concretes. / Rüscher, Claus Henning; Lohaus, Ludger; Jirasit, Fongjan et al.
In: Gels, Vol. 8, No. 1, 9, 01.2022.

Research output: Contribution to journalArticleResearchpeer review

Rüscher CH, Lohaus L, Jirasit F, Tchakouté HK. The effect of gel-type contributions in lime-sand bricks, alkali-activated slags and CEMI/CEMIII pastes: Implications for next generation concretes. Gels. 2022 Jan;8(1):9. Epub 2021 Dec 23. doi: 10.3390/gels8010009
Rüscher, Claus Henning ; Lohaus, Ludger ; Jirasit, Fongjan et al. / The effect of gel-type contributions in lime-sand bricks, alkali-activated slags and CEMI/CEMIII pastes : Implications for next generation concretes. In: Gels. 2022 ; Vol. 8, No. 1.
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abstract = "Lime-sand bricks of different ages were investigated using IR-spectroscopy, thermogravimetry, and X-ray diffraction/scattering. After subtraction of the dominant quartz contribution (80%), the IR spectra show the absorption peaks of the hydrothermally formed binder phases. The spectra also show the alteration of the binder during ageing under atmospheric conditions by the influence of CO2 forming carbonate and a condensed SiO2-gel (secondary gel). The alteration could also be proven in X-ray pattern, obtaining a separation between crystalline CSH and amorphous contributions in the freshly produced lime-sand brick, too. Here, the formation of CSHamorph could be understood as a precursor state (primary gel) to the crystallization of CSH phases. X-ray patterns of aged bodies of alkali-silicate solution activated slags (AAS), CEM-I/CEM-III pastes, and CEM-I concrete indicate that in all cases a similar amorphous CSH-type phase (CSHamorph) was formed, which is responsible for the hardening properties as the glue. The main X-ray peak of CSHamorph obtained using CuKα-radiation with a usual diffractometer is observed between 24◦ and 35◦ 2 Theta with maximum at about 29◦ 2 Theta, whereas it appears much more broadly distributed between 15◦ and 35◦ 2 Theta with maximum between 26◦ and 28◦ 2 Theta for a geopolymer body prepared using the reaction of alkali-silicate solution and metakaolin (AAMK). This is due to the network formed by siloxo and sialate units in the case of AAMK, given that any crystallization can be ruled out. The origin of increasing mechanical strength during the ageing of AAS mortars must be due to further crosslinking of the preformed siloxo chains. Thermal treatment up to 800◦C leads to a complete loss of any mechanical strength of the CEM pastes due to the destruction of crystalline CSH-phases, whereas geopolymer bodies maintain their strength. Implications for next generation concrete include that cement clinker could be completely replaced by using a using alkali silcate solution technology for gel formation.",
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T1 - The effect of gel-type contributions in lime-sand bricks, alkali-activated slags and CEMI/CEMIII pastes

T2 - Implications for next generation concretes

AU - Rüscher, Claus Henning

AU - Lohaus, Ludger

AU - Jirasit, Fongjan

AU - Tchakouté, Hervé Kouamo

N1 - Funding Information: C.H.R. and L.L. use LUH-internal support, F.J. by local support and H.K.T. by AvH.

PY - 2022/1

Y1 - 2022/1

N2 - Lime-sand bricks of different ages were investigated using IR-spectroscopy, thermogravimetry, and X-ray diffraction/scattering. After subtraction of the dominant quartz contribution (80%), the IR spectra show the absorption peaks of the hydrothermally formed binder phases. The spectra also show the alteration of the binder during ageing under atmospheric conditions by the influence of CO2 forming carbonate and a condensed SiO2-gel (secondary gel). The alteration could also be proven in X-ray pattern, obtaining a separation between crystalline CSH and amorphous contributions in the freshly produced lime-sand brick, too. Here, the formation of CSHamorph could be understood as a precursor state (primary gel) to the crystallization of CSH phases. X-ray patterns of aged bodies of alkali-silicate solution activated slags (AAS), CEM-I/CEM-III pastes, and CEM-I concrete indicate that in all cases a similar amorphous CSH-type phase (CSHamorph) was formed, which is responsible for the hardening properties as the glue. The main X-ray peak of CSHamorph obtained using CuKα-radiation with a usual diffractometer is observed between 24◦ and 35◦ 2 Theta with maximum at about 29◦ 2 Theta, whereas it appears much more broadly distributed between 15◦ and 35◦ 2 Theta with maximum between 26◦ and 28◦ 2 Theta for a geopolymer body prepared using the reaction of alkali-silicate solution and metakaolin (AAMK). This is due to the network formed by siloxo and sialate units in the case of AAMK, given that any crystallization can be ruled out. The origin of increasing mechanical strength during the ageing of AAS mortars must be due to further crosslinking of the preformed siloxo chains. Thermal treatment up to 800◦C leads to a complete loss of any mechanical strength of the CEM pastes due to the destruction of crystalline CSH-phases, whereas geopolymer bodies maintain their strength. Implications for next generation concrete include that cement clinker could be completely replaced by using a using alkali silcate solution technology for gel formation.

AB - Lime-sand bricks of different ages were investigated using IR-spectroscopy, thermogravimetry, and X-ray diffraction/scattering. After subtraction of the dominant quartz contribution (80%), the IR spectra show the absorption peaks of the hydrothermally formed binder phases. The spectra also show the alteration of the binder during ageing under atmospheric conditions by the influence of CO2 forming carbonate and a condensed SiO2-gel (secondary gel). The alteration could also be proven in X-ray pattern, obtaining a separation between crystalline CSH and amorphous contributions in the freshly produced lime-sand brick, too. Here, the formation of CSHamorph could be understood as a precursor state (primary gel) to the crystallization of CSH phases. X-ray patterns of aged bodies of alkali-silicate solution activated slags (AAS), CEM-I/CEM-III pastes, and CEM-I concrete indicate that in all cases a similar amorphous CSH-type phase (CSHamorph) was formed, which is responsible for the hardening properties as the glue. The main X-ray peak of CSHamorph obtained using CuKα-radiation with a usual diffractometer is observed between 24◦ and 35◦ 2 Theta with maximum at about 29◦ 2 Theta, whereas it appears much more broadly distributed between 15◦ and 35◦ 2 Theta with maximum between 26◦ and 28◦ 2 Theta for a geopolymer body prepared using the reaction of alkali-silicate solution and metakaolin (AAMK). This is due to the network formed by siloxo and sialate units in the case of AAMK, given that any crystallization can be ruled out. The origin of increasing mechanical strength during the ageing of AAS mortars must be due to further crosslinking of the preformed siloxo chains. Thermal treatment up to 800◦C leads to a complete loss of any mechanical strength of the CEM pastes due to the destruction of crystalline CSH-phases, whereas geopolymer bodies maintain their strength. Implications for next generation concrete include that cement clinker could be completely replaced by using a using alkali silcate solution technology for gel formation.

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