Effect of Na2O Content on Performance of Fly ash Geopolymers at Elevated Temperature
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.
[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.
[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.
@article{"International Journal of Earth, Energy and Environmental Sciences:52411", author = "Kalyan Kr. Mandal and Suresh Thokchom and Mithun Roy", title = "Effect of Na2O Content on Performance of Fly ash Geopolymers at Elevated Temperature", abstract = "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 = "Compressive strength, EDX, Elevated temperature,
Fly ash, Geopolymer, Scanning electron microscopy, XRD", volume = "5", number = "1", pages = "17-7", }