Effect of Mechanical Activation of Fluidized Bed Fly Ash on Geopolymer Properties

Abstract:

This paper is focused on the elucidation of mechanical activation effect of circulating fluidized bed combustion fly ash (Amgalan Thermal Station, Mongolia) on mechanical properties of geopolymers. Fluidized bed fly ash was mechanically activated for 15-120 minutes with a vibratory mill. The effect of mechanical activation was quite visible on the particle size reduction and on the degree of amorphization.Geopolymer samples were prepared from the raw and milled fluidized bed fly ashes by alkaline activation. Chemical activation was performed with 10M sodium hydroxide solution, as well as solutions containing a mixture of sodium silicate and sodium hydroxide with a weight ratio of 2:1. The geopolymer cubic specimens were cured at 70°C for 24 hrs and their 7 days uniaxial compressive strength was measured. After curing and drying, the bulk density, water absorption and apparent porosity of geopolymer samples were evaluated.X-ray powder diffractometry (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and thermogravimetry-differential thermal analysis (TGA-DTA) have been used for the structural characterization of the CFA and the resulting geopolymers. The highest compressive strength of 32.4 MPa was achieved for the fly ash milled for 30 minutes and activated with the solution containing the sodium silicate and 10M sodium hydroxide at a weight ratio of 2:1. Non-milled CFA based geopolymers showed the compressive strength of 16.2 MPa after activation with the same solution. Mechanical activation resulted in an increase in the reactivity of the fluidized bed fly ash and that enhances the geopolymerization reactions.

• Periodical: Solid State Phenomena (Volume 288)
• Pages: 51-58
• DOI: https://doi.org/10.4028/www.scientific.net/SSP.288.51
• Online since: March 2019
• Authors: Gendenjamts Oyun-Erdene, Jadambaa Temuujin*
• Keywords: Amorphization, Fluidized Bed Combustion Fly Ash, Geopolymers, Mechanical Activation

References

[1] J.Temuujin, A.Minjigmaa, G.Oyun-Erdene, B.Davaabal, U.Bayarzul, J.Amgalan, Characterization of fly ash from Amgalan, fluidized bed combustion thermal station in Ulaanbaatar city and its applicability for the production of alkali activated material, in: Jacob Parker (Eds.), Fly ash, Nova Science Publishers Inc., New York, 2017, pp.123-135.

DOI: 10.1109/ifost.2013.6616970

[2] R.E. Conn, K.Sellakumar, Utilization of CFB fly ash for construction application, in: Proceedings of the 15th International Conference on Fluidized Bed Combustion, (1999) FBC99-0144.

[3] G.Sheng, J.Zhai, Utilization of fly ash coming from a CFBC boiler co-firing coal and petroleum coke in Portland cement, Fuel, 86 (2007) 2625-2631.

DOI: 10.1016/j.fuel.2007.02.018

[4] J.Temuujin, A.Minjigmaa, U.Bayarzul, Ts.Zolzaya, B.Davaabal, J.Amgalan, Fundamentals of geopolymers and related alkali activated materials, Mater.Sci. Forum 803 (2015) 144-147.

DOI: 10.4028/www.scientific.net/msf.803.144

[5] J.Temuujin, A.Minjigmaa, B.Davaabal, U.Bayarzul, A.Ankhtuya, Ts.Jadambaa, K.J.D. MacKenzie, Utilization of radioactive high-calcium Mongolian flyash for the preparation of alkali-activated geopolymers for safe use as construction materials, Ceram.Int. 40 (2014) 16475-16483.

DOI: 10.1016/j.ceramint.2014.07.157

[6] J.Temuujin, A.Minjigmaa, U.Bayarzul, D.S. Kim, S-Ho Lee, H.J. Lee, C.H. Ruescher, K.J.D. MacKenzie, Properties of geopolymer binder prepared from milled pond ash, Materials de Construccion 67 (2017) e134.

DOI: 10.3989/mc.2017.07716

[7] J.G.S. van Jaarsveld, J.S.J. van Deventer, G.C. Lukey, The characterisation of source materials in fly ash-based geopolymers, Mater.Lett. 57 (2003) 1272-1280.

DOI: 10.1016/s0167-577x(02)00971-0

[8] E.I. Diaz, E.N. Allouche, S.Eklund, Factors affecting the suitability of fly ash as source material for geopolymers, Fuel, 89 (2010) 992-996.

DOI: 10.1016/j.fuel.2009.09.012

[9] European standard, EN 197-1:2011, Cement part 1: composition, specification and conformity criteria for common cement (2011).

[10] ASTM C618, Standard specification for coal fly ash and raw or calcined natural pozzolan for use in concrete (2012).

DOI: 10.1520/c0618-99

[11] P.Balaz, Mechanochemistry in Nanoscience and Minerals Engineering, Springer, Verlag Berlin Heidelberg, (2008).

[12] J.Temuujin, R.P. William, A.van Riessen, Effect of mechanical activation of fly ash on the properties of geopolymer cured at ambient temperature, J.Mat.Process.Tech. 209 (2009) 5276-5280.

DOI: 10.1016/j.jmatprotec.2009.03.016

[13] S.Kumar, R.Kumar, Mechanical activation of fly ash: Effect on reaction, structure and properties of resulting geopolymer, Ceram.Int. 37 (2011) 533-541.

DOI: 10.1016/j.ceramint.2010.09.038

[14] J.Temuujin, J.Mapiravana, U.Bayarzul, G.Oyun-Erdene, Ts.Zolzaya, B.Darkhijav, M.Dlamini, C.H. Ruscher, Comparative studies of activated South African F and Mongolian class C fly ashes, Waste Biomass Valor. 9 (2018) 1047–1060.

DOI: 10.1007/s12649-017-9881-5

[15] P.J. Sanchez-Soto, J.L. Perez-Rodriguez, I.Sobrados, J.Sanz, Influence of grinding in pyrophyllite – mullite thermal transformation assessed by 29Si and 27Al MAS NMR spectroscopies, Chem.Mater. 9 (1997) 677-684.

DOI: 10.1021/cm960224+

[16] ASTM C20-00, Standard test methods for the apparent porosity, water absorption, apparent specific gravity, and bulk density of burned refractory brick and shapes by boiling water (2010).

DOI: 10.1520/c0020-00

[17] А.Minjigmaa, G.Oyun-Erdene, Ts.Zolzaya, B.Davaabal, J.Amgalan, J.Temuujin, Phosphorus fertilizer prepared from natural Burenkhaan phosphorite (Mongolia) by a mechanical activation, Geosystem Engineering, 19 (2016) 119-124.

DOI: 10.1080/12269328.2015.1137501