In this experimental study, we synthesized geopolymer materials with different amounts of nano-ZnO (0.3%, 0.5% and 0.7%). The effects of the nano-ZnO concentration on the mechanical, structural and thermal properties were studied in detail. XRD investigation revealed the formation of a glassy phase in all the samples and a small shift of the intense peak, which confirmed the incorporation of nano-ZnO into the geopolymer matrix. FTIR analyses showed an increase in the geopolymerization after the addition of nano-ZnO to geopolymer paste. The morphology of the inorganic polymers was studied by mercury intrusion porosimetry (MIP) and scanning electron microscopy (SEM). The addition of nano-ZnO improved the ultrasonic pulse velocity and increased the compressive strength from 30 to 38 MPa. It was found that the strength reached its maximum value at a critical nano-ZnO concentration of 0.5 at.%. The thermal properties of geopolymer nano-ZnO were also investigated using thermogravimetric analysis (TGA), which showed that the incorporation of nano-ZnO decreased weight loss by the geopolymers. The density and the absorption water were also tested and all the results were discussed.

This paper reports on a study of the effects of nano-alumina on the structural, mechanical and thermal properties of geopolymer matrices. Sample composites were produced by mixing metakaolin, an alkaline solution and nano-alumina (1%, 2% and 3%) with a constant L/S ratio 0.55. The resulting products were investigated by XRD, XRF, FTIR, SEM, MIP, TG/DTA and a compressive strength test. The results showed that the insertion of nano-alumina powder improves geopolymer strength. From FTIR and XRD spectra, we found that the structure and geopolymer gel content were enhanced, especially for the optimized proportion of nano alumina (2%), leading to a more homogenous structure, as shown in SEM images. Thus, the density and water absorption of the nano-alumina geopolymer mixture were improved. The introduction of the nano-alumina also had the effect on the thermal properties of the geopolymers, of increasing the weight loss of the composite.