Title
FT-IR and 29 Si-NMR for evaluating aluminium silicate precursors for geopolymers
Author
Valcke, S.L.A.
Pipilikaki, P.
Fischer, H.R.
Verkuijlen, M.H.W.
Eck, E.R.H.
Publication year
2014
Abstract
Geopolymers are systems of inorganic binders that can be used for sustainable, cementless concrete and are formed by alkali activation of an aluminium–silicate precursor (often secondary resources like fly ash or slag). The type of aluminium– silicate precursor and its potential variations within one batch may influence geopolymer performance. Therefore, if geopolymers are to be applied for sustainable concrete with reproducible quality, a characterization tool for quality control of precursors and optimizing mix design is needed, which links the (variable) secondary resource characteristics to the performance of geopolymers. This paper shows the potential of using FT-IR and solid state 29Si-NMR for a (semi-)quantitative evaluation of secondary resources suitable for geopolymers. More specifically, the aim is to investigate whether the presence of particular aluminium–silicate phases may have a dominant influence on the strength of a simple geopolymer system. Based on deconvolution of FT-IR and NMR spectra of 9 source materials (fly ash and slag) and their geopolymers, relative amounts of different (aluminium– silicate) phases were estimated and trends with strength were evaluated. A clear trend is observed for bothNMRand FT-IR results: the precursors containing a higher amount of ‘active bonds’, predominantly from silicates with a medium amount of aluminium and alkalis incorporated in their framework, result in higher paste strengths. As such, due to its relatively quick and easy measurements, FT-IR for estimating relative amounts of these aluminium–silicate phases, can be a useful tool for evaluating geopolymer precursors
Subject
Building Engineering & Civil Engineering
SR - Structural Reliability
TS - Technical Sciences
Buildings and Infrastructure
Materials
Built Environment
FT-IR
Solid state
Si-NMR
Geopolymer
Secondary resources
Fly ash
Blast furnace slag
Sustainable concrete
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TNO identifier
519581
Source
Materials and Structures, 1-13
Document type
article