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Recycling 2018, 3(4), 50; https://doi.org/10.3390/recycling3040050

Characterization and Leachability Behaviour of Geopolymer Cement Synthesised from Municipal Solid Waste Incinerator Fly Ash and Volcanic Ash Blends

1
Department of Chemistry, Faculty of Sciences, University of Douala, P.O. Box 24157, Douala, Cameroon
2
Department of Geosciences and Environment, Faculty of Sciences, University of Douala, P.O. Box 24157, Douala, Cameroon
3
CSIR-National Metallurgical Laboratory, Jamshedpur 831007, India
*
Author to whom correspondence should be addressed.
Received: 13 October 2018 / Revised: 6 November 2018 / Accepted: 7 November 2018 / Published: 11 November 2018
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Abstract

Municipal solid waste incinerator fly ash (MSWI-FA) was used synergistically with volcanic ash (VA) to synthesize Geopolymer cement. The effects of the incorporation of 0%, 30%, and 50% of VA and the alkalinity of activating solution on the structure and properties were studied by using the X-ray diffractometer (XRD), Fourier transform infrared spectroscopy (FTIR), field emission gun scanning electron microscopy (FEG-SEM), and mechanical testing. The encapsulation efficiency of the cements was carried out by using a toxicity characteristic leaching procedure (TCLP). The geopolymerization of MSWI-FA promoted the formation of new minerals such as Thernadite (Na2SO4), Hydrocalumite (Ca4Al2O6(CO3)0.67(SO3)0.33), C-S-H, and Faujasite-Na(Na2Ca)0.075(Al0.3Si0.7)O2(H2O)0.22. The Geopolymer cement synthesized with the addition of 50% of VA at 6M NaOH concentration, which exhibited the most compact microstructure. This was the highest strength with the best encapsulation ability. The microstructure analysis of the MSWI-FA-VA system revealed the coexistence of C-S-H and N-A-S-H phases as the main cementitious binders. The TCLP results of cement vis a vis raw MSWI-FA showed the leaching of metals reduced to a great extent. This was much lower than the permissible limit fixed by the United States Environmental Protection Agency (USEPA) for the toxicity characteristic. Furthermore, an attempt was made to correlate the microstructure with mechanical properties. View Full-Text
Keywords: MSWI-FA; volcanic ash; Geopolymer; characterization; leachability MSWI-FA; volcanic ash; Geopolymer; characterization; leachability
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Tome, S.; Etoh, M.-A.; Etame, J.; Sanjay, K. Characterization and Leachability Behaviour of Geopolymer Cement Synthesised from Municipal Solid Waste Incinerator Fly Ash and Volcanic Ash Blends. Recycling 2018, 3, 50.

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