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Effect of Na2O Content on Performance of Fly ash Geopolymers at Elevated Temperature

Authors: Suresh Thokchom, Kalyan Kr. Mandal, Mithun Roy


The present paper reports results of an experimental program conducted to study performance of fly ash based geopolymer pastes at elevated temperature. Three series of geopolymer pastes differing in Na2O content (8.5%, 10% and 11.5%) were manufactured by activating low calcium fly ash with a mixture of sodium hydroxide and sodium silicate solution. The paste specimens were subjected to temperatures as high as 900oC and the behaviour at elevated temperatures were investigated on the basis of physical appearance, weight losses, residual strength, shrinkage measurements and sorptivity tests at different temperatures. Scanning electron microscopy along with EDX and XRD tests were also conducted to examine microstructure and mineralogical changes during the thermal exposure. Specimens which were initially grey turned reddish accompanied by appearance of small cracks as the temperature increased to 900oC. Loss of weight was more in specimens manufactured with highest Na2O content. Geopolymer paste specimen containing minimum Na2O performed better than those with higher Na2O content in terms of residual compressive strength.

Keywords: fly ash, Scanning Electron Microscopy, Geopolymer, compressive strength, XRD, EDX, elevated temperature

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[1] M. Husem, "The effects of high temperature on compressive and flexural strength on ordinary and high performance concrete" Fire safety Journal , vol.41, pp. 155-163, 2006.
[2] M.S.Culfik and T.Ozturan, "Effect of elevated temperatures on residual mechanical properties of high performance mortar", Cement and Concrete Research, vol. 32, pp.809-816, 2002.
[3] J.Davidovits, "properties of geopolymer cements," Proceedings of the first International conference on alkaline cements and concretes, vol. 1,pp. 131-149, 1994.
[4] T. Bakharev, "Resistance of geopolymer materials to acid attack", Cement & Concrete Research 35, pp.658 - 670. 2005
[5] X. J. Song, M. Marosszeky, M. Brungs, R. Munn, "Durability of fly ash based Geopolymer concrete against sulphuric acid attack", presented at 10 DBMC Int. Conference on Durability of Building Materials and Components, Lyon, France, 2005.
[6] S. Thokchom, P. Ghosh, S. Ghosh, " Acid resistance of fly ash based geopolymer mortars" Int. Journal of recent trends in Engg."1(6), pp.36- 40. 2009
[7] S. Thokchom, P. Ghosh, S. Ghosh, "Resistance of fly ash based geopolymer mortars in sulfuric acid" J. of Engg. And Applied sciences", 4(1), pp. 65-70, 2009.
[8] S.E. Wallah, B.V. Rangan, "Low calcium fly ash based geopolymer concrete: Long term properties, Research report GC2, Curtin University of Technology, Australia, 2006.
[9] T. Bakharev, "Durability of geopolymer materials in magnesium and sodium sulphate solution," Cement & Concrete Research 35, pp.1233- 1246, 2005.
[10] A. Allahverdi, F. Skavara, "Sulfuric acid attack on hardened paste of geopolymer cements, Part 2 Corrosion mechanism at mild and relatively low concentrations, Ceramics-Silikaty 50(1), pp.1 - 4,2006.
[11] A. Allahverdi, F. Skavara, "Sulfuric acid attack on hardened paste of Geopolymer cements, Part 1. Mechanism of corrosion at relatively high concentrations", Ceramics - Silikaty 45 (3) pp.81 - 88, 2001.
[12] A. Allahverdi, F. Skavara, "Nitric acid attack on hardened paste of geopolymeric cements, Part 1, Ceramics-Silikaty 45 (3), pp.81 -88 2001..
[13] A. Allahverdi, F. Skavara, "Nitric acid attack on hardened paste of geopolymeric cements, Part 2, Ceramics-Silikaty 45 (4), pp.143- 149.2001.
[14] T.Bakharev, J.Sanjayan and Y.B Cheng, "Effect of elevated temperature curing on properties of alkali activated slag concrete," Cement and Concrete Research 29, pp.1619-1625, 1999.
[15] D.Kong, J.Sanjayan and K.S.Crentsil, " The behaviour of geopolymer paste and concrete at elevated temperatures,"International conference on pozzolana, concrete and geopolymer, Khon Kaen, Thailand, pp. 105- 119, 2006.
[16] D.L.Y. Kong, and J.Sanjayan, " Effect od elevated temperature on geopolymer paste, mortar and concrete," Cement and Concrete Research 40, pp. 334-339, 2010.
[17] T. Bakharev, "The thermal behaviour of geopolymer prepared using class F fly ash and elevated temperature curing,"cement and Concrete Research , 36, pp.1134-1147, 2006.