Strategies to control the high temperature shrinkage of fly ash based geopolymers

Vickers, Les; Rickard, William D.A.

doi:10.1016/j.tca.2014.01.020

Cited by 65 publications

(37 citation statements)

References 14 publications

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“…A large standard derivation in compressive strength after heating, such as the large errors indicated in Fig. 7, has also been found in other research [32,33]. Fig.…”

Section: Thermal Resistancesupporting

confidence: 81%

“…Although some other dilatometric studies [38,39] also showed a similar small expansion before 100°C, a certain extent of shrinkage is normally observed at 100°C when starting from as-cured (moist) samples [32,34,35,40]. The small expansion before 100°C observed in some research is probably due to the thermal expansion properties of the solid geopolymer gel.…”

Section: Thermal Resistancementioning

confidence: 77%

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Mechanical, thermal insulation, thermal resistance and acoustic absorption properties of geopolymer foam concrete

Zhang

Provis

Reid³

et al. 2015

Cement and Concrete Composites

443

160

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This study reports the synthesis and characterization of geopolymer foam concrete (GFC). A Class F fly ash with partial slag substitution was used for GFC synthesis by mechanical mixing of preformed foam. The GFCs exhibited 28 day compressive strengths ranging from 3 to 48 MPa with demolded densities from 720 to 1600 kg/m 3 (105°C oven-dried densities from 585 to 1370 kg/m 3 ), with the different densities achieved through alteration of the foam content.The thermal conductivity of GFCs was in the range 0.15 to 0.48 W/m·K, showing better thermal insulation properties than normal Portland cement foam concrete at the same density and/or at the same strength. The GFC derived from alkali activation of fly ash as a sole precursor showed excellent strength retention after heating to temperatures from 100 to 800°C, and the post-cooling compressive strength increased by as much as 100% after exposure at 800°C due to densification and phase transformations. Partial substitution of slag for fly ash increased the strength of GFC at room temperature, but led to notable shrinkage and strength Preprint of: Z Zhang, JL Provis, A Reid, H Wang, Mechanical, thermal insulation, thermal resistance and acoustic absorption properties of geopolymer foam concrete (GFC), Cement and Concrete Composites, 62(2015): 97-105. Final published version is at: http://dx.doi.org/10.1016/j.cemconcomp.2015.03.013 2 loss at high temperature. Thin GFC panels (20 -25 mm) exhibited acoustic absorption coefficients of 0.7-1.0 at 40 to 150 Hz, and 0.1-0.3 at 800 to 1600 Hz.

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“…A large standard derivation in compressive strength after heating, such as the large errors indicated in Fig. 7, has also been found in other research [32,33]. Fig.…”

Section: Thermal Resistancesupporting

confidence: 81%

Section: Thermal Resistancementioning

confidence: 77%

Mechanical, thermal insulation, thermal resistance and acoustic absorption properties of geopolymer foam concrete

Zhang

Provis

Reid³

et al. 2015

Cement and Concrete Composites

443

160

View full text Add to dashboard Cite

show abstract

“…e effects of different measures on thermal contraction are listed in Table 1 [26,[51][52][53]. It can be seen that the thermal deformation results of FA and MK geopolymers are consistent with the thermal strain process.…”

Section: Ermal Expansion/shrinkage Process Of Geopolymersmentioning

confidence: 54%

Thermal and Mechanical Properties of Geopolymers Exposed to High Temperature: A Literature Review

Dai

Wang

2020

Advances in Civil Engineering

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Geopolymers are prepared by alkali solution-activated natural minerals or industrial waste materials, which have been widely used as new sustainable building and construction materials for their excellent thermal and mechanical properties. The thermal and mechanical properties of geopolymers at high temperature have attracted great attention from many researchers. However, there are few systematic works concerning these two issues. Therefore, this work reviewed the thermal and mechanical behaviors of geopolymers at high temperature. Firstly, the thermal properties of geopolymers in terms of mass loss, thermal expansion, and thermal conductivity after high temperature were explained. Secondly, the mechanical properties of residual compressive strength and stress-strain relationship of fly ash geopolymers and metakaolin geopolymers after high temperature were analyzed. Finally, the microstructure and mineralogical characteristics of geopolymers upon heating were interpreted according to the changes of microstructures and compositions. The results show that the thermal properties of geopolymers are superior to cement concrete. The geopolymers possess few mass loss and a low expansion ratio and thermal conductivity at high temperature. The thermal and mechanical properties of the geopolymers are usually closely related to the raw materials and the constituents of the geopolymers. Preparation and testing conditions can affect the mechanical properties of the geopolymers. The stress-strain curves of geopolymer are changed by the composition of geopolymers and the high temperature. The silicon-type fillers not only improve the thermal expansion of the geopolymers but also enhance mechanical properties of the geopolymers. But, they do not contribute to reducing the thermal conductivity. the different raw materials, aluminosilicate precursor and reinforcement materials, result in different geopolymer damage during the heating. However, phase transitions can occur during the process of heating regardless of the raw materials. The additional performance enhancements can be achieved by optimizing the paste formulation, adjusting the inner structure, changing the alkali type, and incorporating reinforcements.

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“…In recent years, research works dealing with the thermal behavioural of geopolymers exposed to high temperature or fire have been widely carried out1516. Geopolymers decreased in strength when exposed to elevated temperature as OPC does.…”

mentioning

confidence: 99%

Thermal Resistance Variations of Fly Ash Geopolymers: Foaming Responses

Cheng-Yong

Yun-Ming

Abdullah

et al. 2017

Sci Rep

109

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This paper presents a comparative study of the characteristic of unfoamed and foamed geopolymers after exposure to elevated temperatures (200–800 °C). Unfoamed geopolymers were produced with Class F fly ash and sodium hydroxide and liquid sodium silicate. Porous geopolymers were prepared by foaming with hydrogen peroxide. Unfoamed geopolymers possessed excellent strength of 44.2 MPa and degraded 34% to 15 MPa in foamed geopolymers. The strength of unfoamed geopolymers decreased to 5 MPa with increasing temperature up to 800 °C. Foamed geopolymers behaved differently whereby they deteriorated to 3 MPa at 400 °C and increased up to 11 MPa at 800 °C. Even so, the geopolymers could withstand high temperature without any disintegration and spalling up to 800 °C. The formation of crystalline phases at higher temperature was observed deteriorating the strength of unfoamed geopolymers but enhance the strength of foamed geopolymers. In comparison, foamed geopolymer had better thermal resistance than unfoamed geopolymers as pores provide rooms to counteract the internal damage.

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Strategies to control the high temperature shrinkage of fly ash based geopolymers

Cited by 65 publications

References 14 publications

Mechanical, thermal insulation, thermal resistance and acoustic absorption properties of geopolymer foam concrete

Mechanical, thermal insulation, thermal resistance and acoustic absorption properties of geopolymer foam concrete

Thermal and Mechanical Properties of Geopolymers Exposed to High Temperature: A Literature Review

Thermal Resistance Variations of Fly Ash Geopolymers: Foaming Responses

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