Influence of Iron Mining Tailing Addition on Geopolymeric Binders

Geopolymers are inorganic binders given during the 1970s by Davidovits, with reference to inorganic or mineral materials. Geopolymers have a network structure made up by aluminates and silicate tetrahedrons. They are included in the class of alkali activated materials, and their hardening mechanism, known as geopolymerization, is essentially based on the polycondensation of aluminosilicate tetrahedrons. With the innovation of geopolymers, the incorporation of mining tailings in their synthesis is sought. The present research deals with the study of the influence of the iron mine tailings addition in different binders of metakaolin-based geopolymers. Metakaolin was obtained by calcining kaolin from GH Areias Company, Inhaúma, Brazil. Previous works have demonstrated the influence of kaolin calcination. The factors studied in the current research were the calcination time, the heating rate, and the composition in mass percentage. Through the Analysis of Variance, it was possible to verify that the geopolymer having the highest percentage of metakaolin, 8h of calcination time and heating rate of 10 °C/min presented the higher values of compressive strength, with an average of 50 MPa. After the iron mining tailing addition, the compressive strength varied between 18 MPa and 38 MPawith 95% confidence level. The goal is to develop geopolymers from this kaolinite in order to obtain products with higher added value.