Influência da requeima na pozolanicidade de cinzas de bagaço de cana-de-açúcar de diferentes características

Abstract

The use of alternative materials that can minimize the environmental impact (due to the emission of gases and the consumption of energy and raw materials) for the production of Portland cement in recent years became the focus of several studies. Among these studies, we can highlight the research on the use of agro-industrial waste that can act as pozzolanic material, cement, filler or aggregate. The partial replacement of Portland cement with rice husk ash is a common practice in some parts of the world. In Brazil, several studies point to the use of bagasse ash cane sugar as supplementary cementitious materials, since the country is one of the largest producers of cane sugar. Studies in the literature indicate that, depending on the type of cane sugar cultivation process as well as the bagasse burning conditions, the ashes may present pozzolanic characteristics, witck contibutes to greater durability of the cementitious compounds. These characteristics usually are associated with particle size, silica content, and the presence of amorphous silica in the material. In this context, this paper studies the blight as beneficiation process and homogenization of bagasse ash cane sugar from different sources. For this, ashes before and after the reburn were characterized by X-ray fluorescence, loss on ignition, density, X-ray diffraction, thermal analysis, particle size distribution, pozzolanic activity index, modified Chapelle test, electric conductivity test, modulus of elasticity and traction in flexion. The analisys of the results obtained indicate that the mechanical properties of cementitious compounds produced by replacing 10% of the cement mass the equivalent volume of cane bagasse ash justify its use. However, the reburn does not appears to favor the pozzolanic activity of the ashes of sugarcane bagasse as it did not contributed to the improvement of the mechanical properties studied. The global analysis of the data indicates that the mechanism of action of the ashes was to fill the empty spaces.