Abstract
The partial substitution of Portland cement by bauxite residue (BR) results in products with, at least, properties similar of products with pure binder. However, the physicochemical interactions between Portland cement and BR during the chemical hydration reaction is still poorly explored in literature. The high amount of sodium and presence of Al2O3, SiO2 and Fe2O3 are factors that affect the formation of hydrated products and depends on the type of Portland cement used. The main purpose of this work was to evaluate the impact of use bauxite residue in substitution of part of cement on the early age of hydration. Isothermal conduction calorimetry, X-ray diffraction, thermogravimetry and FTIR were the methods to this monitoring. The results show that the presence of BR, from Alcoa (Poços de Caldas, Brazil), increases the induction period, the portlandite consumption and the amount of ettringite and monosulfoaluminate produced. At the same time, there are the formation of sodium silicoaluminate hydrate and sodium bicarbonate, due to the reactions with silicates, aluminates and with carbonate from cement.
Keywords:
bauxite residue; cement; hydration; thermogravimetry; X-ray diffraction; FTIR
