Caracterização tecnológica dos resíduos da indústria de reciclagem de alumínio e da cinza do bagaço da cana-de-açúcar como materiais pozolânicos

• Ano de defesa: 2014
• Autor(a) principal: Braz, Inara Guglielmetti [UNIFESP]
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de São Paulo
• Palavras-chave em Português: Waste from aluminum recycling; Sugarcane bagasse ashes; Zeolite; Pozzolanic activity; Cement; Resíduos da reciclagem de alumínio; Cinza do bagaço da cana-de-açúcar; Zeólita; Atividade pozolânica; Cimento
• Link de acesso: https://sucupira.capes.gov.br/sucupira/public/consultas/coleta/trabalhoConclusao/viewTrabalhoConclusao.jsf?popup=true&id_trabalho=2104531; https://repositorio.unifesp.br/handle/11600/48070

Over the last decades, the increase in industrial waste production has created several socio-economic and environmental problems, promoting discussions aiming to resolve problems, such as waste disposal and recycling. In this scenario, aluminum recycling and sugar-alcohol industries, due to a considerable increase in production, have an important participation in waste production. The main waste from these industries is rich in alumina (aluminum recycling) and silica (sugarcane bagasse ashes), and is commonly disposed of in landfills or soil. With this in mind, this study aims to analyze the main technological properties of these materials and to evaluate their potential as pozzolanic materials. Pozzolans are siliceous or silico aluminous materials that react with water and calcium hydroxide (Ca(OH)2) to form compounds with agglomerating properties. Partial addition of zeolite to improve agglutination of the waste studied in this paper was also tested. Tests showed that the studied materials are in compliance with the chemical specifications laid down by standard NBR12653/12 for type E pozzolans and that more than 66% of their particles are smaller than 44µm. Therefore, these materials can be used for this purpose. The pozzolanic activity of waste was determined using three tests (electrical conductivity measurement, modified Chapelle test and index of pozzolanic activity with Portland cement) in pure samples and in mixtures with zeolites. The first two tests classified samples as pozzolans, whereas the third test showed that the addition of both waste from aluminum recycling and sugarcane bagasse ashes reduced the resistance of mortar to compression. The reduction of the resistance of mortars made with aluminum waste was the result of the formation of hydrogarnets, such as synthetic katoites (Ca3Al2(OH)12). The absence of amorphous silica in sugarcane bagasse ashes, in turn, was the main factor for the decrease in the pozzolanic activity index of waste. On the other hand, calcium silicate hydrates (C- S-H) - products of the pozzolanic reaction that increase the resistance of mortar - were formed only in samples with sugarcane bagasse ashes and zeolite, that is, with higher content of silica. Therefore, it was demonstrated that, although the aluminum hydroxide and the alumina present in waste from aluminum recycling do not show good pozzolanic activity, they are very reactive with Ca(OH)2, forming hydrogarnets. This property should be studied further to allow the use of waste from aluminum recycling as additive, for example, in aluminous or refractory cements.