Experimental investigation on the flexural behavior of prestressed concrete beams under the influence of accelerated corrosion

One of the early deterioration factors of reinforced concrete structures is the corrosion of its steels, and in structures with greater sensitivity, such as prestressed structures, where steel elements, including prestressed tendons, play a much larger role in supporting the structure, the importance of this issue increases. In this research, an experimental evaluation of the flexural behavior of prestressed concrete beams under the influence of corrosion. To this end, four prestressed concrete beams with a rectangular cross-section (150 mm × 300 mm) and a length of 2 m were fabricated. The method for causing corrosion in specimens was accelerated by using constant electric current in prestressing tendons and in a pool containing 5% sodium chloride electrolyte solution. One prestressed concrete beam without corrosion was considered as a control specimen, and in the other three studied beams, corrosion occurred at three levels of 5, 10 and 15%. After exposure corrosion, the specimens were subjected to four-point bending test in order to check the structural behavior. The results indicated that the corrosion created at different levels reduced the bearing capacity and other behavioral characteristics of the specimen under study, including the amount of energy absorption, effective hardness and midspan displacement. Increase of the corrosion level, increases the decreasing trend of the studied parameters. At the highest level of corrosion (15% level), the values of the parameters of bearing capacity, absorbed energy, effective hardness, and mid-span deflection decreased by 24%, 34%, 37%, and 19%, respectively. Also, the investigations showed that there is a non-uniform distribution of corrosion caused by the accelerated method along the prestressing cables and difference between the actual and calculated corrosion rates based on the Faraday's law.