How does Na, K alkali metal concentration change the early age structural characteristic of kaolin-based geopolymers

A comparative study of two methods to produce geopolymer composites from volcanic scoria and the role of structural water contained in the volcanic scoria on its reactivity

“…The formation of Si-rich geopolymeric gels in GfZ G and GfZ K (Fig. 5, IR spectra) promotes a relatively low compressive strength in comparison to that of Alrich geopolymeric in GZ G and GZ K [22]. The results of compressive strength correlated those FTIR spectra of geopolymers which exhibited more intense absorption band at around 3500 cm −1 on the FTIR spectrum of geopolymer mortars GfZ G , GfZ K and could be correlated with diminishing compressive strengths [23].…”

“…The absorption bands at around 1473 cm -1 observed on the spectra of all geopolymers can be attributed to Na 2 CO 3 species. They are probably formed by the atmospheric carbonation of the unreacted sodium silicate or sodium hydroxide [22]. The intensity of these bands is higher on the FTIR spectrums of geopolymers from fusion process.…”

Comparison of the microstructure and the compressive strength of two geopolymers derived from Metakaolin and an industrial sludge

“…This sludge contains a substantial amount of silica and alumina as crystalline kaolinite, which can be used to produce geopolymer cement. Physicochemical and mechanical properties of geopolymer cement depend on the nature of Aluminosilicate source (mineralogical composition, degree of crystallinity) [13][14][15][16][17], calcination method and temperature [18][19][20], nature of alkali metal cations [21,22], Si/Al molar ratio [23,24], Na 2 SiO 3 /NaOH mass ratio [25,26], Na 2 O/Al 2 O 3 molar ratios [27], temperature and curing time [28][29][30]. This research introduces a comparative study between two geopolymers, synthesized from two different raw materials: The industrial sludge and Metakaolin.…”

Preparation of alkali-activated fly ash-based geopolymer and their application in the adsorption of copper (II) and zinc (II) ions

“…It is clearly shown that the alkali-activated fly ash has a higher adsorption amount than raw fly ash as fly ash contains some impurities that can block the pores and retard the target solute from being adsorbed efficiently. Synthesized geopolymer has resulted in the shift of chemical system from the species with larger rings and complex structures to become monosilicates, have chains and become species with smaller rings [17][18]. This change can increase surface area and pore volume significantly making geopolymer have more sorption sites for metal ions.…”