Uso de ensaios não destrutivos na avaliação de dormentes de concreto protendido

Abstract

In the last two decades, there has been an increase in pathological manifestations in concrete sleepers, which have reduced their useful life in a situation of use, leading them to rupture and increasing the operational cost of railways. In order to control these problems, inspections are usually carried out visually by inspectors, resulting in a difficult and time-consuming job that makes decision-making difficult for the technicians involved due to the subjectivity of the process. In this research, the use of non-destructive tests was proposed as an alternative method for such inspections in order to bring quantitative data and correlation with the real situation of the sleeper. Thus, in a laboratory environment, depending on the manufacturer, exposure conditions, age and city of manufacture, the sleepers were organized into 09 (nine) groups, totaling 107 sleepers. In these, tests were performed on surface hardness, ultrasound, ultrasonic dynamic modulus, surface electrical resistivity, reinforcement corrosion potential, ultrasound tomography and GPR. The results showed that the technique of tomography by ultrasound and georadar are not very suitable for inspection of sleepers; the sclerometry technique alone was not able to detect any variability in the sleeper properties. Ultrasound, surface electrical resistivity, ultrasonic dynamic modulus and corrosion potential tests have shown to be promising in the evaluation of sleepers in a laboratory environment. Correlation curves were plotted using simple regression. Different types of regressions were tested, such as: linear, polynomial and power. In all tests, the curve that best fitted the coefficient of determination R2 was the second-degree polynomial, as it presented greater values in relation to the others. Even so, the correlation curves found were not similar to those presented by several authors.