Physical chemistry research of a concrete dam with over 50 years of operation

Abstract

Guaricana hydroelectric power plant concrete dam, located in the South of Brazil, was investigated after 49 years of operation. A part of the mortar was altered to ettringite, and other by-products. The inner defects in the fracture and polished sample surfaces were detected by CT and SEM. The samples were extracted from two parts of the dam from top to valley. Elemental chemical composition and phases were determined by EDS and XRD analysis. The reservoir water showed that it was less aggressive to the concrete structure. Percolated dam water analyses revealed a mortar-mass loss of 3 kg/year. Onsite visual inspection, mechanical tests, and other usual forms of investigation confirmed concrete deterioration, such as leaching, stalactites and stalagmites formation, alkali-aggregate reaction and ettringite. Furthermore, mortar damage was detected in a particular area according to the dam depth, and autogenous healing of cracks were visible in some parts of the inspected galleries.