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Several geopolymer-based materials were produced and characterized by mixing metakaolin, a commercial sodium silicate solution, a sodium hydroxide solution, and a loose waste olivine sand deriving from a metallurgical process devoted to the production of a high manganese steel. Olivine sand was added either in the as-received form or after a thermal treatment at 900 °C. Hardened materials containing different amounts of olivine sand were characterized and their behavior was compared to that of a blank geopolymeric matrix. Materials were examined by X-ray diffraction, Fourier Transform Infrared Radiation, and optical and scanning electron microscope investigation; mechanical compressive strength was discussed taking into account water absorption and microstructure. It has been observed that all compositions containing the as-received olivine sands badly perform, whereas those prepared using thermally treated olivine have higher compressive strength than the reference blank composition. In particular, samples with composition containing 100 g of metakaolin and 75 g of olivine displayed the best overall behavior. Graphical Abstract |
