Caracterização microestrutural do Metacaulim de alta reatividade

• Autor(a) principal: Guilherme Gallo Neves da Rocha
• Data de Publicação: 2005
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da UFMG
• Texto Completo: http://hdl.handle.net/1843/BUOS-8DJH7D
• topic: Engenharia Metalúrgica e de Minas; Engenharia metalúrgica; Concreto; Cimento Portland

High Reactivity Metakaolin has been considered a highly effective mineral admixture for concrete and Ordinary Portland Cement (OPC) based products, used to improve mechanical strength and durability of structures manufactured with this material. Its physical and chemical properties, as well as the amount used influence greatly on finished products and concrete characteristics. Besides, it is also used in several other applications such as in the manufacturing of granulated and fibrous refractory materials, ceramics, paper and cellulose, and has extensive use as mineral filler in paint, polymeric resins, cosmetics, tires and rubber, animal ration and agribusiness [WMB, WMT, WEF,WEN]. This dissertation was aimed at the microstructural characterization of three commercially available samples of High Reactivity Metakaolin, with the purpose of knowing some of their main physical and chemical properties. The characterization was performed through the determination of chemical composition by using techniques suchas X-ray fluorescence, chemical analysis and EDS (Energy Dispersive Spectometry), phase identification through X-ray diffraction, particle size distribution analysis through laser beam diffraction, BET specific surface area, scanning electronic microscopy, picnometry and sieving. It could be observed that there are slight differences in the characteristics of the three analyzed samples. The presence of impurities such as alkali,magnesium and calcium oxides was not significant in any sample. The specific surface area values were always above 16 m2/g; alumina, silica and iron oxide percentages, added together, were always above 90%, and loss on ignition values were below 3% in any case, thus leading to the conclusion that all samples can be classified as being HighReactivity Metakaolin. It could be concluded that some characterization techniques appeared more effective as other to, in fact, determine the Metakaolin level of quality. The BET specific surface area determination, the chemical composition and loss on ignition can be considered the most relevant.