Effect of Composition on Structure and Mechanical Properties of Metakaolin Based PSS-Geopolymer

Najet Saidi, Basma Samet;Samir Baklouti;


Geopolymer is a type of cross linked long-chain inorganic compound, built in three-dimensional structures and has different attractive properties (thermal, mechanical, chemical, etc).<br>This study elucidated the structure and mechanical properties of PSS type geopolymer obtained by alkaline attack of metakaolin. A systematic investigation was conducted to comprehend the effect of molar ratios Si/Al and Na/Al on the properties of this geopolymer by using 29Si and 27Al magnetic angle spinning nuclear magnetic resonance (MAS NMR) spectroscopy, X-Ray diffraction and mechanical measurements. The results indicate that an increase of Si/Al ratio improves the geopolymer mechanical properties due probably to the formation of Si-O-Si bond in the geopolymer at the expense of Si-O-Al one. It was also shown that an introduction of NaOH in the geopolymer composition enhances the mechanical properties until a molar ratio Na/Al=1. Beyond this value, the excess of Na+ cation causes fragility of the geopolymer structure confirmed by a decrease of the mechanical strength.


Geopolymer; Metakaolin; Structure Evolution; 29Si; 27Al NMR; XRD Resolution; Alkali Activation

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