Study of the mechanical performance of geopolymer produced with self iron content

The most common feature of geopolymer cements is that they contain a relatively small amount of iron oxides. This is due to the fact that several scientists suspect the harmful action of some Fe++ ferrous compounds in the development of the geopolymeric reaction. For some researchers, Fe can interfere negatively in the geopolyme-rization process of the material, while, in some new studies, the role of Fe has revealed interesting results for geopolymers. In order to verify the mechanical resistance achieved by the geopolymer obtained from the bauxite washing waste, which has a high iron content in its composition, the present research intends to use 100% of this calcined raw material as a precursor, and reagents such as NaOH and Na2SiO3 as activators in the process. All materials were characterized in terms of their physical and mineralogical properties, in order to enable the correct dosage of materials. With the geopolymers obtained, the compressive strength was evaluated, varying the concentration of NaOH in 8 M and 10 M for different curing times (7 and 28 days). X-ray diffraction analy-sis (DRX), Fourier Transform Infrared Spectroscopy (FTIR), granulometric analysis and mechanical resistance tests. Even with approximately 25% of iron, the geopolymers presented a mechanical behavior compatible with assigned functions and similar to the norms established for Portland cement, with a maximum resistance of 25.85 MPa.