Keywords
Alkali-activation
fly ash
nuclear magnetic resonance. álcali-ativação
cinza volante
resonancia magnética nuclear
fly ash
nuclear magnetic resonance. álcali-ativação
cinza volante
resonancia magnética nuclear
How to Cite
Díaz Rosero, J. E., de Vargas, A. S., Dal Molin, D. C. C., Masuero, A. B., San Gil, R. A. D. S., & Mejía de Gutiérrez, R. (2016). Geopolymers based on fly ash activated with naoh and Ca(OH)2: microstructural characterization by nmr-mas 29Si Y 27Al. Informador Tecnico, 80(2), 151–158. https://doi.org/10.23850/22565035.487
Abstract
In fly-ash alkali-activation technology, depending on the combination of activators, deleterious reactions may result in a drop in resistance with age. This Studiy aimed to evaluate the compressive strength of alkali-activated fly ash from combined solutions of NaOH and Ca(OH)2. Three molar ratio CaO/SiO2 (C/S) were studied: 0.05 (M5), 0.15 (M15) e 0.25 (M25). Resistances order of 21 MPa (M15) and 19 MPa (M25) were reached at the age of 7 days. However, after 28 and 91 days, the resistances were 8 MPa and 7 MPa, respectively. The M5 samples showed rising behavior of resistance with age. Thus, the drop in resistance has conditioned the C/S matrices. In the 29Si NMR spectra of the M25 sample Si has decreased species Q4 (3Al) and Q4 (2Al), those responsible for the mechanical properties of activated samples.
References
Andersen, M. D.; Jakobsen, H.J.; Skibsted, J.(2014).Incorporation of aluminum in the calcium silicate hydrate (C-S-H) of hydrated Portland cements: a high-field 27Al and 29Si MAS NMR investigation". Inorg. Chem. nº 42, pp2280-2287.
ASTM C618. (1998). Standard Specification for Coal Fly abd Raw or Calcined Original Pozzolan for Use as a Mineral Admixture in Concrete".In: Annual Book of ASTM, n° 04.02.
Criado, M., Fernandez-Jimenez, A.; Garcia-Loderiro, I Carcelan Taboda, V. (2012).Effect of relative humidity on the reaction products of alkali activated fly ash. Journal of the European Ceramic Society, n° 32, pp.2799–2807.
https://doi.org/10.1016/j.jeurceramsoc.2011.11.036
Fernández-Jiménez, A. Palomo, A, I. Sobrados I, &.Sanz, J. (2006) The role played by the reactive alumina content in the alkaline activation of fly ashes". Microporous and Mesoporous Materials, n° 91, pp. 111-119.
https://doi.org/10.1016/j.micromeso.2005.11.015
García-Lodeiro, I., Fernández-Jiménez, A., & Palomo, A. (2011) .Compatibility studies between N-A-S-H and C-A-S-H gels. Study in the ternary diagram Na2O-CaO-Al2O3-SiO2-H2O,Cement and Concrete Research, nº 41; pp.923-931.
https://doi.org/10.1016/j.cemconres.2011.05.006
García-Lodeiro, Fernández-Jiménez, A., & Palomo, A. (2013). Variation in hybrid cements over time. Alkaline activation of fly ash-portland cement blends, Cement and Concrete Research, n° 52; pp. 112-122.
Granizo, M.L. Alonso, S., Blanco-Varela & Palomo, A. (2002). Alkaline activation of metakaolin:effect of calcium hydroxide in the products of reaction". J. Am. Ceram. Soc., 2002, nº 85 (1), pp 225–231. Mingyu, H. Xiaomin, Z & Fumei,L (2009). Alkaliactivated fly ash-based geopolymer with zeolite or bewntonite as additives". Cement & Concrete Composites, n° 31, pp. 762-768.
Jeon, D.; Jun, Y.; Jeong, Y; Eun Oh, J. (2015).Microstructural and strength improvements through the use of Na2CO3 in a cementless Ca(OH)2-activated Class F fly ash system. Cement and Concrete Research, 2015, n° 67,pp. 215-225.
https://doi.org/10.1016/j.cemconres.2014.10.001
Palomo, A.C., Grutzeck, M.W., Blanco, T (1999).Alkali-activated Fly Ashes. A Cement for Future". Cement and Concrete Research, nº29, pp. 1323-1329.
https://doi.org/10.1016/S0008-8846(98)00243-9
Palomo, A. Fernández-Jiménez, A., Kovalchu, G. Ordo-ez, M & Naranjo, C (2006). OPC–fly ash cementitious systems. Study of gel binders formed during alkaline hydration".J. Mater. Sci, n° 42, pp 2958–2966.
Peng, Z., Vance, K., Dakhane, A., & Neithalath, N (2015). Microstructural and 29Si MAS NMR spectroscopic evaluations of alkali cationic effects on fly ash activation, Cement and Concrete Composites, n° 57, pp. 34-43.
https://doi.org/10.1016/j.cemconcomp.2014.12.005
Puertas,F.& Jiménez, A.F. (2003). Mineralogical and microstructural characterisation of alkaliactivated ash/slag pastes. Cement and Concrete composites, nº 25, pp 287-292.
https://doi.org/10.1016/S0958-9465(02)00059-8
Richardson,I. G., R., Groves G.W. & Dobson C.M. (1993) . et al, "Location of aluminum in substituted calcium silicate hydrate (C-S-H) gels as determined by 29Si and 27Al NMR and EELS". J. Am. Ceram. Soc., 2005,n°, pp 2285–2288.
Shi, C. (1995). Acelaration of the reactivity of fly ash by chemical activation". Cement and Concrete Research, n° 25, pp 15-21.
https://doi.org/10.1016/0008-8846(94)00107-A
Van Jaarsveld, J. G. S. & van Deventer (1997). The potential use of Geopolymeric materials to immobilise toxic metals: part I. Theory and applications". Minerals Engineering, nº 10,pp. 659-669.
https://doi.org/10.1016/S0892-6875(97)00046-0
Vargas, A.S.; Dal Molin, D.C.C.; Vilela, A.C.F.; Jalali,S. & Gomes, J.C. (2007). Cinzas volantes álcali-ativadas com solução combinada de NaOH e Ca(OH)2". Matéria, n° 12, pp. 462-469.
https://doi.org/10.1590/s1517-70762007000300006
Vargas, A.S Denise C.C. Dal Molin, Â B., . Vilela,.ACF. Castro-Gomes,j. & M. de Gutierrez,R (2014). Strength development of alkaliactivated fly ash produced with combined NaOH and Ca(OH)2 activators". Cement & Concrete Composites, n° 53, pp. 341-349.
https://doi.org/10.1016/j.cemconcomp.2014.06.012
Vargas, AS., Dal Molin, Â B.& Vilela,ACF (2011).Cement & Concrete Composites, n° 33, pp.653-660.
https://doi.org/10.1016/j.cemconcomp.2011.03.006
Yip, C. K., (2003). Microanalysis of calcium silicate hydrate gel formed within a geopolymeric binder. Journal of Materials Science, 2003, n°38, pp. 3851-3860.
https://doi.org/10.1023/A:1025904905176
Yip, C. K. & Van Deventer, J. S. J. (2003). Microanalysis of calcium silicate hydrate gel formed within a geopolymeric binder". Journal of Materials Science, n° 38, pp 3851-3860.
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