IR‐Spectroscopic Investigation of Geopolymer and Csh‐Phase Stability on Heating Temperature in Post‐Fired Building Materials

Rüscher, Claus H.; Rigo, Ellen; Unterderweide, K.; Krauss, Hans-W.; Jirasit, F.

doi:10.1002/9781119321811.ch11

Cited by 1 publication

(4 citation statements)

References 8 publications

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“…[ 2 ] and further in Refs. [ 12 , 14 ] and could be taken from our archive. The preparation of CEM I and CEM III pastes are described in Ref.…”

Section: Methods and Samplesmentioning

confidence: 99%

“…The preparation of CEM I and CEM III pastes are described in Ref. [ 12 ] and could be taken from that reservoir.…”

Section: Methods and Samplesmentioning

confidence: 99%

“…A distinction between the amorphous contribution and the crystalline CSH-phases in cement stones is obtained using a thermal treatment of samples. A thermal treatment up to 800 °C did not weaken the compressive strength of the AAMK sample, 35–31 MPa [ 12 ]. The XRD diagram remains the same as shown in Figure 7 .…”

Section: Distinction Between Crystalline and Amorphous Csh By Thermal Treatmentmentioning

confidence: 99%

“…Conclusively, heating at 600 °C reveals the destruction of the CSH* contribution as exemplified in Figure 10 for another AAH sample before and after thermal treatment at 600 °C. This sample revealed compressive strength of about 100 and 55 MPa before and after thermal treatment at 800 °C, respectively [ 12 ].…”

Section: Distinction Between Crystalline and Amorphous Csh By Thermal Treatmentmentioning

confidence: 99%

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The Effect of Gel-Type Contributions in Lime-Sand Bricks, Alkali-Activated Slags and CEMI/CEMIII Pastes: Implications for Next Generation Concretes

Rüscher

Lohaus

Jirasit

et al. 2021

Gels

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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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“…[ 2 ] and further in Refs. [ 12 , 14 ] and could be taken from our archive. The preparation of CEM I and CEM III pastes are described in Ref.…”

Section: Methods and Samplesmentioning

confidence: 99%

“…The preparation of CEM I and CEM III pastes are described in Ref. [ 12 ] and could be taken from that reservoir.…”

Section: Methods and Samplesmentioning

confidence: 99%

Section: Distinction Between Crystalline and Amorphous Csh By Thermal Treatmentmentioning

confidence: 99%

Section: Distinction Between Crystalline and Amorphous Csh By Thermal Treatmentmentioning

confidence: 99%

See 2 more Smart Citations

The Effect of Gel-Type Contributions in Lime-Sand Bricks, Alkali-Activated Slags and CEMI/CEMIII Pastes: Implications for Next Generation Concretes

Rüscher

Lohaus

Jirasit

et al. 2021

Gels

View full text Add to dashboard Cite

show abstract

IR‐Spectroscopic Investigation of Geopolymer and Csh‐Phase Stability on Heating Temperature in Post‐Fired Building Materials

Cited by 1 publication

References 8 publications

The Effect of Gel-Type Contributions in Lime-Sand Bricks, Alkali-Activated Slags and CEMI/CEMIII Pastes: Implications for Next Generation Concretes

The Effect of Gel-Type Contributions in Lime-Sand Bricks, Alkali-Activated Slags and CEMI/CEMIII Pastes: Implications for Next Generation Concretes

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