Electrochemical Behavior of Reinforced Concrete Beams with Different Flexural Tensile Stresses in the Steel Reinforcement

In this work, the electrochemical and structural behavior of reinforced concrete beams subjected to flexure is studied. Eight beams with and without corrosion were considered. The study variable was the tensile stress in the longitudinal steel reinforcement. Stresses of 40% and 80% of the yielding stress of steel were considered. The beams were subjected to sustained loads using a post-tensioning system. Corrosion in the steel reinforcement was induced by chloride contamination of fresh concrete and wet and dry cycles. The corrosion rate of the steel, as well as the resistivity and concentration of chlorides of the concrete, were measured. The beams were tested two times using a four-point loading system. The first one before that corrosion was induced; a load associated with the target tensile stress in the steel reinforcement was applied to determine the initial structural parameters of the beams: crack pattern, crack resistance, and initial and postcrack stiffness. The second time after the corrosion was induced; incremental loads were applied until the failure of beams to determine the change in yielding and maximum strength, as well as the postyielding stiffness of the beams. It was found that the electrochemical behavior of the beams with corrosion was similar regardless of the tensile stress in the steel considered (40% or 80%). The measured electrochemical parameters indicated a high level of corrosion in accordance with Mexican standards; however, from the structural point of view, the strength and stiffness were not significantly affected by the corrosion status. Beams with electrochemical parameters associated with a higher level of corrosion are needed to study the initial degradation of the structural parameters, for example, strength degradation.