Testing the corrosion rate of prestressed beams under variable temperature and humidity conditions

The purpose of this study was to evaluate the effect of temperature rise on the development of corrosion processes in prestressed concrete beams. Tests were performed on the rate of corrosion processes both under conditions of increasing temperature and humidity, which were reproduced in a climatic chamber, as well as in an environment exposed to chloride ions. The process of migration of chloride ions into the concrete was accelerated by the application of an electric field. In addition, selected beams were subjected to long-term loading in order to induce scratching. Corrosion rate tests were carried out using the non-destructive linear polarization method (LPR). Strength tests of the beams, as well as displacement and deformation measurements using the digital image correlation technique in the Aramis system were also performed. Beams without chloride addition exhibited a fairly stable low level of corrosion current density throughout the test period, indicating the passive state of the reinforcement. In an environment with a humidity of 30% and a temperature of 20°C, the increase in corrosion current density was much faster than for beams in an environment with a humidity of 60% and a temperature of 30°C in both beams with and without chloride addition. A greater increase in corrosion current density could be observed in the unscratched beams compared to the scratched beams. The results of strength tests indicated that in beams subjected to accelerated migration of chloride ions, the deflection at scratching was significantly lower than in beams without chloride addition. In these beams, lower deformations on the surface of the elements at the time of scratching were also registered.