Avaliação do concreto de obras de arte especiais através de caracterização física, química, análise microestrutural e ensaios não destrutivos

Abstract

Monitoring and maintenance during the useful life of and viaducts (SEWs) is extremely im-portant, as they consist of critical points in the Brazilian road and rail transport systems. The interdiction of these structures entails social, environmental and economic losses. Thus, the general object of this research is to evaluate the durability of concrete through microstruc-tural and physicochemical characterizations in three bridges of different ages (93 years, 61 years and 3 years) located in the state of Minhas Gerais, Brazil. Thus, the procedures con-sisted of technical inspections to identify possible pathological manifestations, as well as the performance of non-destructive tests: pacometry, sclerometry and carbonation. Water absorption, void index and specific mass, chemical composition, crystalline phases, differ-ential thermal analysis, Fourier Transform Infrared Reflection (FT-IR) and Scanning elec-tron microscopy (SEM) were evaluated, which sought to identify the hydrated cement com-pounds and the presence of aggressive agents. It was found that the concrete structures are seriously degraded due to carbonation, lack of covering and corroded reinforcement. The ef-fect of carbonation and aggressive agents present in rivers could be identified in chemical and microstructural analyses, altering the hydrated compounds. It is concluded from the re-sults that to avoid compromising the useful life of reinforced concrete structures, the indica-tions of the technical standards (design, materials, execution and maintenance) and the pro-motion of inspection and routine maintenance aiming at the recovery/strengthening of bridges and viaducts. Thus, it is evident that the results allowed a greater knowledge of the history of the characteristics of the materials used, as well as the need for preventive inspec-tions to be carried out in the SEWs.