Reação álcali-agregado: estudo do fenômeno em rochas silicosas
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Data
2008-08-29
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Universidade Federal de Goiás
Resumo
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.
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COUTO, Tiago Andrade. Reação álcali-agregado: estudo do fenômeno em rochas silicosas. 2008. 191 f. Dissertação (Mestrado em Engenharia Civil) - Universidade Federal de Goiás, Goiânia, 2008.