Evaluation of the variation in NDT results in reinforcing bars of concrete slabs, subjected to accelerated corrosion processes

Abstract

Abstract

Non-Destructive Testing (NDT) measurements were used to monitor the degradation process of concrete slabs reinforced with commercial steel bars, subjected to a severe corrosion process by induced current and in the presence of a 5% NaCl solution. Sclerometry, ultrasound, and electrical resistivity were used to follow the degradation, while measurements of half-cell potential and polarization resistance were used to evaluate the probability of corrosion, and corrosion rate of the system concrete/rebar. The results obtained confirm an accelerated corrosion process in the exposed bars, represented by the shift in half-cell potential to the active zone, as well as by the increased corrosion rate of the steel. The results obtained from the application of NDT revealed changes in behavior, primarily in the electrical resistivity of the concrete and in the speed of ultrasound propagation within it. Sclerometry measurements were challenging, showing an increase in the rebound index, which suggests a surface hardening of the concrete. Experimentation will continue to establish a possible correlation between the NDT measurements obtained and the corrosion degradation of the reinforcing bar.