Revisiting Concrete Structures from a Hydroelectric Power Plant Affected by ASR in Brazil, with a New Diagnose of Coupled Attack (ASR + DEF)

Monitoring concrete structures is a customary practice by hydropower companies during the service life of construction projects. Constructed in the 1970s, structures from a Hydroelectric Power Plant (HPP) in Brazil were diagnosed in the past with alkali-silica reaction (ASR) solely due to map cracking and little laboratory analyses and tests. In the meantime, further assessments on concrete structures. Larger data from instrumentation, and more detailed experimental program with concrete cores drilled in field followed by mechanical and stiffness tests and microstructural analyses pointed to the presence of secondary ettringite in the concrete samples, besides ASR gel. Deterioration indexes and microstructural aspects signaled that those concretes suffered from coupled attack, with DEF and ASR occurring simultaneously. This paper aims to present the main results from more recent investigations that elucidated this new diagnosis of deterioration and the different behavior of elements according to its structure in the field.