Investigação de potencialidade pozolânica do resíduo de beneficiamento de rochas ornamentais após tratamento térmico para produção de pasta cimentícia

Abstract

This work investigates the potential use of ornamental stone waste after thermal treatment as pozzolanic admixture in cement pastes. The ornamental stone waste was ground and sieved after thermal treatment at 1.200 ºC, being henceforth named OSWTT. The OSWTT was evaluated according to parameters specified by NBR 12.653 (ABNT, 2014) and used, in different dosages, for the production of cement pastes. The OSWTT was analysed in the following manner: chemical composition, by X-ray fluorescence; mineralogy, by X-ray diffraction; microstructure, by scanning electron microscope with attached energy dispersive X-ray; specific surface, using the method of Blaine; fineness, with 75 m and 45 m sieves; and pozzolanicity, by calculating the pozzolanic activity index in mixtures with hydrated lime and in mixtures with Portland cement, by the method of Fratini and by the method of Luxán. The microstructure of the cement pastes was analysed using images captured by the scanning electron microscope. The results indicate that the OSWTT possesses pozzolanical capacity when utilized in the production of cement pastes, being capable of generating in the final product a denser microstructure because of the pozzolanic reactions and of the filler effect. The OSWTT was used in 5% and 10% as additive and the best performance was obtained with the addition of 5% with respect to the mass of Portland cement of OSWTT in cement pastes.