Synthesis and properties of alkali-activated iron ore tailings blended with metakaolin

Abstract

In this study, synthesis, microstructural characteristics, mechanical proper-ties, and environmental compatibility of alkali-activated binders derived fromiron ore tailings (IOT)—with partial replacement with metakaolin (MK)—wereinvestigated. The binders were produced with a NaOH solution, IOT, and MK.A thermal cure at 100◦C was used and the MK was applied as a partial replace-ment of IOT in three proportions (10, 20, and 30 wt%). The IOT-based specimenspresented an average of 98.0 and 18.0 MPa at 7 days age of curing for com-pressive and flexural strength, respectively. The mechanical properties of thealkali-activatedbinderswithMKdecreasedasthesubstitutionratioincreased.Bythe microstructural analysis, it was found a zeolite-type phase in alkali-activatedIOT, while in the bindersblendedwith MK, threenewmineral phases were iden-tified. Furthermore, Fourier transform infrared, quantitative X-ray diffraction,and environmental analysis suggest that the Fe species present in IOT acted inthe alkali-activation reaction.