Effect of nano-silica on microstructure formation of low-cost geopolymer binder

What is it about?

Influence of Nano-SiO2 (NS) addition on properties of Geopolymer materials has been studied through measurement of physicomechanical and morphological characteristics of the hardened specimens. Alumino–silicate materials are water-cooled slag, albite, kaolin, and metakaoline. Materials were prepared at water/binder ratios in a range of 0.244:0.320 for water-cooled slag based materials, while it increased to 0.46 for albite-based mixes, whereas the used activator sodium hydroxide is 10 wt.%.

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Why is it important?

(1) Addition of NS results in an enhancement in mechanical and morphological characteristics of the formed geopolymer specimens incorporating fired and unfired precursors. (2) The enhancement and modification of the hardened geopolymer specimens achieved when using NS up to 2.5%, however further increase results in agglomeration and decrease in the efficiency of the added nanomaterials. (3) SEM micrographs have proved an increased enhancement in the microstructural properties of the NS-mixes up to formation of dense and homogenous morphological shape when using 2.5% NS, whilst an increase in porosity is a common feature of higher NS-mixes.