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Open AccessArticle

Glass-Ceramic Foams from ‘Weak Alkali Activation’ and Gel-Casting of Waste Glass/Fly Ash Mixtures

1
Department of Industrial Engineering, University of Padova, Via Marzolo 9, Padova 35131, Italy
2
Institute of Biomaterials, Department of Materials Science and Engineering, University of Erlangen-Nuremberg, Cauerstraße 6, 91058 Erlangen, Germany
*
Author to whom correspondence should be addressed.
Materials 2019, 12(4), 588; https://doi.org/10.3390/ma12040588
Received: 10 December 2018 / Revised: 25 January 2019 / Accepted: 12 February 2019 / Published: 15 February 2019
(This article belongs to the Special Issue Advanced Glasses, Composites and Ceramics for High Growth Industries)
A ‘weak alkali activation’ was applied to aqueous suspensions based on soda lime glass and coal fly ash. Unlike in actual geopolymers, an extensive formation of zeolite-like gels was not expected, due to the low molarity of the alkali activator (NaOH) used. In any case, the suspension underwent gelation and presented a marked pseudoplastic behavior. A significant foaming could be achieved by air incorporation, in turn resulting from intensive mechanical stirring (with the help of a surfactant), before complete hardening. Dried foams were later subjected to heat treatment at 700–900 °C. The interactions between glass and fly ash, upon firing, determined the formation of new crystal phases, particularly nepheline (sodium alumino–silicate), with remarkable crushing strength (~6 MPa, with a porosity of about 70%). The fired materials, finally, demonstrated a successful stabilization of pollutants from fly ash and a low thermal conductivity that could be exploited for building applications. View Full-Text
Keywords: alkali activation; inorganic gel casting; glass–ceramic foams; waste glass; fly ash alkali activation; inorganic gel casting; glass–ceramic foams; waste glass; fly ash
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MDPI and ACS Style

Rincón Romero, A.; Toniolo, N.; Boccaccini, A.R.; Bernardo, E. Glass-Ceramic Foams from ‘Weak Alkali Activation’ and Gel-Casting of Waste Glass/Fly Ash Mixtures. Materials 2019, 12, 588.

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