Formação da reação álcali-agregado em diferentes tipos de agregado no nordeste: análise microestrutural versus métodos convencionais

Abstract

The alkali-aggregate reaction is present in a large number of constructions and is one of the pathological manifestations of a greater degree of deterioration of the concrete. This reaction, even if slow, leads to an irreversible pathological condition and is usually associated with the integration of chemical processes of some aggregate mineralogical compounds with alkali hydroxides from cement, water and external agents. The most common reports of this reaction occur in hydraulic structures, such as dams, due to the permanent contact with water. However, in recent years, numerous of other types of structures have been affected, including building foundations, leaving the problem in evidence. The city of Recife was the first in the country where, since 2005, there have been numerous cases of cracking in residential and commercial building blocks and constructions such as bridges, viaducts and urban train system sleepers. Due to this, this study sought to verify the correlation between the concrete prisms test (CPT) and the accelerated mortar bars test (AMBT) of the Northeast of Brasil aggregates, since until the present moment, no study was carried out using the concrete prisms test in the northeast region. In addition, a comparison was created between conventional methods and new methods that emerge in the academic environment, such as X-ray diffractometry, Scanning Electron Microscopy (SEM) and X-ray fluorescence (XRF). With the results obtained, a correlation was observed between the unconventional tests with the expansion tests in the accelerated mortar bars test and the concrete prisms test.