Estimation of the depth of cracks in concrete through the velocity of ultrasonic waves

Abstract

Cracks are the most recurrent pathological manifestations in concrete, due to the different forms of exposure that the material is subject to. In this scenario, it is important that buildings undergo inspections through different methods, among which non-destructive testing (NDT) appear as an alternative tool. Among the NDTs, the ultrasonic wave propagation velocity test, known as Ultrasound, was used in this study. The purpose of this study was to evaluate the application of the method in concrete prisms to estimate the depth of cracks using a mathematical model in the literature. The influence of the test distance was also evaluated. The results were compared with the depths simulated in the concrete prisms, using a statistical analysis. It was noticed that the ultrasound test is effective to detect the presence of cracks, as it changes the propagation time of the wave. The mathematical model tested, with the use of ultrasound, was able to estimate the depth of the cracks in 88.5% of cases, but with very dispersed results and a high margin of error, making it impossible to apply them to real structures. It was concluded that the distances of execution of up to 20 cm presented better results.