Using isothermal calorimetry, X-ray diffraction, thermogravimetry and FTIR to monitor the hydration reaction of Portland cements associated with red mud as a supplementary material

This study is part of a global project to find some large-scale application for red mud. A previous work confirmed that the use of RM as partial substitution for cement can affect its rheological properties; however, it is possible to produce cementitious materials without lose mechanical performances at harden state. The main goal of the work was to assess the impact of red mud (RM) as replacement of different Brazilian Portland cements by monitoring the formation of hydrated products over time, by thermogravimetry, X-ray diffraction and FTIR. Results show that the presence of RM increases the induction period, the gypsum and portlandite consumption as well as the amount of ettringite and monosulfoaluminate produced. The formation of sodium silicoaluminate hydrate (NASH) was also observed, regardless the kind of cement, as a result of the reaction with aluminates and silicates from the binder.