Alternative binder produced with magnesium oxide and metakaolin

Abstract

Portland cement is widely used today. However, its production process causes several environmental impacts, requiring studies of new alternative formulations to the binder. Thus, this paper aimed to study the behavior of an alternative binder to Portland cement composed of MgO and metakaolin (as a source of SiO₂ for the system), with compressive strength tests; x-ray diffraction (XRD); thermogravimetry (TG); Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The combination of MgO with metakaolin produced an alternative binder that reached a compressive strength of 7,23 MPa, with the formation of hydration products characteristic of the MgO + SiO₂ system being recorded. In addition, the presence of alumina in the chemical composition of metakaolin resulted in the formation of hydrotalcite, a voluminous hydration product that seems to have caused internal stresses in the pastes, followed by cracking, with a consequent decrease in its final strength. Thus, studies regarding this hydration product must be conducted for a complete understanding of the functioning of the system.