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. Keywords: concrete, water permeability, deterioration, alkali-aggregate reaction. Resumo A usina hidroelétrica Guaricana, localizada no sul do Brasil, foi investigada após 50 anos de sua operação. O estudo mostrou que uma parte da argamassa extraída dos testemunhos alterou para etringita e outros sub-produtos. Defeitos internos nas superfícies polidas e de fratura das amostras foram detectados por CT e MEV. As amostras foram extraídas de duas partes da barragem do topo ao vale. A composição elementar e as fases químicas foram determinadas por EDS e difração de raios X. Análises da água do

The Sulphate Effect on Lijiaxia Concrete Dam (China) Gallery

“…The drilled core method is one of the most common methods because the inside of the concrete could be revealed and exposed directly by this method. Moreover, the concrete core could be used as the samples of laboratory tests [14]. Some other methods, including indentation method, rebound method, and ultrasonic method, are also applied to the dam concrete degradation examination [15].…”

“…Hu et al [19] have shown that the concrete of Yongan Dam is deteriorated due to the thaumasite form of sulphate attack, according to microanalytical investigations, SEM and energy disperse Xray (EDX). Portella et al [14] analyzed the elemental chemical composition and phases of a concrete dam with over 50 years of operation by EDS and XRD techniques. However, most of the microanalytical studies on the dam concrete degradation are based on single or two experimental techniques, which might cause the local uncertainty of the precipitations.…”