Review of Geopolymer Behaviour in Thermal Environment

Zulkifly, Khairunnisa; Cheng-Yong, Heah; Yun-Ming, Liew; Panias, D.; Sakkas, Konstantinos

doi:10.1088/1757-899x/209/1/012085

Cited by 28 publications

(11 citation statements)

References 33 publications

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“…Therefore, the effects on sample characteristics are low. At over 700 • C, a mass gain can be observed, which appears to be due to the oxidation of oxygen-poor iron species or pure iron [64].…”

Section: ≡M-oh + Ho-m≡ → ≡M-o-m≡ + H2o (6)mentioning

confidence: 99%

XRD and TG-DTA Study of New Alkali Activated Materials Based on Fly Ash with Sand and Glass Powder

et al. 2020

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In this paper, the effect on thermal behavior and compounds mineralogy of replacing different percentages of fly ash with compact particles was studied. A total of 30% of fly ash was replaced with mass powder glass (PG), 70% with mass natural aggregates (S), and 85% with mass PG and S. According to this study, the obtained fly ash based geopolymer exhibits a 20% mass loss in the 25–300 °C temperature range due to the free or physically bound water removal. However, the mass loss is closely related to the particle percentage. Multiple endothermic peaks exhibit the dihydroxylation of β-FeOOH (goethite) at close to 320 °C, the Ca(OH)2 (Portlandite) transformation to CaCO3 (calcite) occurs at close to 490 °C, and Al(OH)3 decomposition occurs at close to 570 °C. Moreover, above 600 °C, the curves show only very small peaks which may correspond to Ti or Mg hydroxides decomposition. Also, the X-ray diffraction (XRD) pattern confirms the presence of sodalite after fly ash alkaline activation, whose content highly depends on the compact particles percentage. These results highlight the thermal stability of geopolymers in the 25–1000 °C temperature range through the use of thermogravimetric analysis, differential thermal analysis, and XRD.

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Section: ≡M-oh + Ho-m≡ → ≡M-o-m≡ + H2o (6)mentioning

confidence: 99%

XRD and TG-DTA Study of New Alkali Activated Materials Based on Fly Ash with Sand and Glass Powder

et al. 2020

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“…The high stresses in the void wall developed the movement of non-combined water, thus the greater degradation occurred with rising temperature due to fine pores and shrinkage [26]. This was also due to breakage of the bonding and phase changing from an amorphous to a crystalline phase.…”

Section: Microstructure Analysismentioning

confidence: 99%

Strength Development and Elemental Distribution of Dolomite/Fly Ash Geopolymer Composite under Elevated Temperature

et al. 2020

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A geopolymer has been reckoned as a rising technology with huge potential for application across the globe. Dolomite refers to a material that can be used raw in producing geopolymers. Nevertheless, dolomite has slow strength development due to its low reactivity as a geopolymer. In this study, dolomite/fly ash (DFA) geopolymer composites were produced with dolomite, fly ash, sodium hydroxide, and liquid sodium silicate. A compression test was carried out on DFA geopolymers to determine the strength of the composite, while a synchrotron Micro-Xray Fluorescence (Micro-XRF) test was performed to assess the elemental distribution in the geopolymer composite. The temperature applied in this study generated promising properties of DFA geopolymers, especially in strength, which displayed increments up to 74.48 MPa as the optimum value. Heat seemed to enhance the strength development of DFA geopolymer composites. The elemental distribution analysis revealed exceptional outcomes for the composites, particularly exposure up to 400 °C, which signified the homogeneity of the DFA composites. Temperatures exceeding 400 °C accelerated the strength development, thus increasing the strength of the DFA composites. This appears to be unique because the strength of ordinary Portland Cement (OPC) and other geopolymers composed of other raw materials is typically either maintained or decreases due to increased heat.

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“…4 (2021) Tchakouté et al [18].On the other hand, the strength increased slightly in MD20 specimen after exposure to 800°C due to the viscous sintering process which occurred in the geopolymer mix at a temperature beyond 600°C which induced the healing of microcracks that led to a strength gain after exposure to 800°C [54] . According to the previous works [66,67], the sintering effect leads to the formation of a very compact structure with a high mechanical strength by inducing crack healing and thus the specimens are well conserved from failure at elevated temperature. Therefore, the MD20 specimen experienced the higher residual strength than control mix as well as other specimens containing CKD at 800°C.…”

Section: Compressive Strengthmentioning

confidence: 98%

Effect of Elevated Temperatures on The Performance of Metakaolin Geopolymer Pastes Incorporated by Cement kiln dust

2021

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The aim of the present work was to study the influence of elevated temperatures on the thermal behavior of geopolymer cements based on the incorporation of metakaolin with cement kiln dust. Geopolymer composites were synthesized by partially substituted metakaolin (MK) with 0, 20, 30 and 40 wt% of cement kiln dust (CKD). The mixture of liquid sodium silicate (Na2SiO3) and sodium hydroxide (NaOH) was used as alkaline activator solution with fixed ratio 2.5 and the concentration of sodium hydroxide was 10 Molar. The obtained geopolymer specimens were cured in water at ambient temperature (25°C) for 28 days and then subjected to various elevated temperatures 200, 400, 600 and 800°C for one hour. Geopolymer cements were characterized before and after temperature exposure via visual appearance, X-ray diffraction (XRD), Fourier Transform infrared spectrometry (FTIR) and the compressive strength test. Some selected samples were investigated by using thermo gravimetric analysis (TGA/DTG).The results show that, all geopolymer specimens loss their compressive strength from ambient temperature to 400°C. This is due to the escape of moisture and dehydroxylation of aluminosilicate gel from the geopolymer matrix. However, geopolymer samples gained strength upon heating to 600°C as a result of further polymerization of unreacted silicate species. At 800°C, the geopolymer mix with 20% CKD retained highest strength and thermal stability than other mixes due to viscous sintering process which induced crack healing thus enhanced the mechanical properties of geopolymer under high temperature. This suggests that geopolymer paste that contains 80% MK and 20% CKD can withstand high temperature as well as very suitable for refractory and fire resistance applications.

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Review of Geopolymer Behaviour in Thermal Environment

Cited by 28 publications

References 33 publications

XRD and TG-DTA Study of New Alkali Activated Materials Based on Fly Ash with Sand and Glass Powder

XRD and TG-DTA Study of New Alkali Activated Materials Based on Fly Ash with Sand and Glass Powder

Strength Development and Elemental Distribution of Dolomite/Fly Ash Geopolymer Composite under Elevated Temperature

Effect of Elevated Temperatures on The Performance of Metakaolin Geopolymer Pastes Incorporated by Cement kiln dust

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