Reação álcali-agregado nas usinas hidrelétricas do Complexo Paulo Afonso/CHESF: influência da reação nas propriedades do concreto. / Alkali-aggregate reaction at the Paulo Afonso Hydreletric Complex/CHESF: influence of the reaction in the properties of the concrete.

AUTOR(ES)

Patricia Neves Silva

DATA DE PUBLICAÇÃO

2007

RESUMO

Several are the concrete deterioration processes and the alkali-aggregate reaction (AAR) is classified as a chemical deterioration process. As a reaction result and in an umid environment expansion products are formed, being able to cause cracking, loss of strength, increase of deformation, loss of functionality, reduction of the durability of the structure, amongst others. The knowledge of reaction prevention is vast, but the same cannot be said about its mechanism. Once the reaction exists, there is not yet a way to avoid its continuity. The study was carried out in five hydroelectric plants of the Paulo Afonso Hydroelectric System, whose concrete was affeted by AAR. These dams are responsable for generating energy for the northeast of Brazil. The ages of the concretes are between 20 to 50 years. Some physical, chemical, mineralogical, mechanical and elastic properties of the concrete were evaluated, such as: potential reactivity, alkali content, deterioration index, bulk density, compressive strength, tensile strength, modulus of elasticity, Poissons ratio and creep. The main objective of this study is to evaluate if some of the characteristics of the concretes are affected by the AAR. The results indicate that, although the concretes have been manufactured decades ago, the potential reactivity is still high, but the concrete structures are not much deteriorated. With regard to the mechanical properties, it was not observed significant reduction on the compressive strength, tensile strength, creep, but the modulus of elasticity was the most sensible concrete characteristic affected by the AAR.

ASSUNTO(S)

constructions pathology concreto (propriedades) patologia das contruções usinas hidrelétricas hydroelectricpower plants concrete (properties)

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