Influência das condições de queima nas características físico-químicas das cinzas do bagaço de cana-de-acúcar

Abstract

The use of sugarcane bagasse ashes as an additive for concretes has demonstrated to be an economically viable alternative to the production of low carbon construction materials. One of the obstacles for a large scale use of this waste for the production of concrete is its variety. Depending on the soil characteristics, the sugarcane species and the burning conditions, the physicochemical properties of the ashes are altered, rendering them adequate or inadequate for use with cementitious materials. Therefore, this work presents a laboratory evaluation of the influence of the variables of the sugarcane bagasse burning process in the physicochemical properties of the resulting ashes from a certain sugarcane lot from the Triângulo Mineiro and Alto Paranaíba regions. The ashes were produced in a muffle furnace, especially adapted for air injection. The evaluated parameters were temperature, burning time, aircirculation in the furnace and cooling method. To determine the burningtemperatures, differential thermal and thermo gravimetric analysis were conducted in the bagasse, both raw and dried in a greenhouse. The properties of the resulting ashes were evaluated with a scanning electron microscope (MEV), x-ray diffraction (DRX), energy dispersive x-ray spectrometry (EDS) and granulometric analysis by laser granulometer. The results were compared with results of two types of ashes obtained from an industrial process in a sugar-ethanol mill with energy cogeneration. The data were compared with results from two types of ash obtained by industrial processes in sugar-ethanol mill with power cogeneration. The results indicate that the physico-chemical properties of ash depend significantly on the degree of contamination of the sand mulch the soil conditions of burning of bagasse and the fineness of the ash. Data analysis obtained the light of current regulations shows theneed to evaluate further the mechanisms of action of the ash and the criteria for definition of pozzolanic materials.