Reação álcali-agregado: estudo do fenômeno em rochas silicosas

• Ano de defesa: 2008
• Autor(a) principal: Couto, Tiago Andrade
• Orientador(a): Carasek, Helena
• Banca de defesa: Carasek, Helena, Hasparyk, Nicole Pagan, Cascudo, Oswaldo, Kuperman, Selmo Chapira
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Goiás
• Programa de Pós-Graduação: Programa de Pós-graduação em Engenharia Civil (EEC)
• Departamento: Escola de Engenharia Civil - EEC (RG)
• País: Brasil
• Palavras-chave em Português: Reação álcali-agregado; Agregado; Expansão; Durabilidade
• Palavras-chave em Inglês: Alkali-aggregate reaction; Aggregate; Expansion; Durability
• Área do conhecimento CNPq: ENGENHARIAS::ENGENHARIA CIVIL
• Link de acesso: http://repositorio.bc.ufg.br/tede/handle/tede/3166

The symposium on Alkali-Aggregate Reaction (AAR) held in Goiânia in 1997 led to a greater dissemination of this deleterious reaction in Brazil, motivating engineers to find solutions for the problem. Recently, in Brazil, this occurrence has occurred in several building foundations in the Recife metropolitan area besides hydraulic powers plants, as can be seen in some publications from the last AAR Symposium in 2006. This study presents an investigation of several aggregates commercially used in the State of Goiás, Brazil, in order to determine their potential reactivity. In addition, their behavior were compared to the ones from aggregates from several Brazilian classic cases such as Furnas HPP (MG), Moxotó HPP (AL/BA), Pedro Beicht Dam (SP/MG) and Jaguara HPP (SP), beyond aggregates used in civil works of Pernambuco and also a highly reactive basalt from Paraná. The experimental program tested twenty-two rock samples with varied lithology and two local types of cements that had the same clinker (cement A and B). The research uses petrographic analyses, accelerated mortar bar test (NBR 15577), chemical test method (NBR 9774) and accelerated concrete prisms test (based on NBR 15577), to assess the reactivity of the rocks. The results indicate that aggregates show varied expansivity and reactivity among them and sometimes one specific aggregate present different behavior by comparing the results form the test methods performed. This study also discusses the possibility of preventing deleterious expansion from tested aggregates by using the correct type of cement.