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The alkali activation of fly ashes: From macro to nanoscale



Title: The alkali activation of fly ashes: From macro to nanoscale
Author(s): Angel Palomo, Ana Fernández-Jiménez, María Criado, María Mar Alonso
Paper category : conference
Book title: NICOM 2: 2nd International Symposium on Nanotechnology in Construction
Editor(s): Y. de Miguel, A. Porro and P.J.M. Bartos
Print-ISBN: 2-912143-87-X
e-ISBN: 2912143888
Publisher: RILEM Publications SARL
Publication year: 2006
Pages: 95 - 104
Total Pages: 10
Nb references: 27
Language: English


Abstract: The alkali activation of fly ashes is a chemical process by which the vitreous component of the ash is rapidly transformed into a compact cementitious skeleton. The main reaction product of alkali activated fly ash is an alkaline aluminosilicate gel, described by the authors to be a “zeolite precursor”. This aluminosilicate compound is characterized by a short range three-dimensional structure but mid-long-range disorder that makes it X-ray amorphous.
In the present paper some data have been gathered in order to propose a model describing the alkaline activation process of fly ashes. These data have also been used for monitoring the microstructural development, over time, of the cementitious matrix.
As a conclusion, authors have established that this process is governed by a dissolution phenomenon in the early stages of the reaction and by a diffusion mechanism thereafter. At short curing times, an Al-rich phase (meta-stable / intermediate phase) has been found. This phase evolves with the curing time to a more stable Si-rich phase (“zeolite precursor”) consisting of partially aggregated ultra-small nanocrystals. Finally this material has demonstrated to develop excellent technological properties.


Online publication: 2005-11-17
Publication type : full_text
Public price (Euros): 0.00


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