Abstract
The first Mexican specification of low alloy reinforcing bars of weldable grade and optimal mechanical response during plastic deformation caused by earthquakes was issued in 1987. The modifications of the Construction Code of Mexico City after the 1985 earthquakes included the recomendation of using low alloy rebars as a first option for the reinforced concrete bulding main structural components. The low alloy rebars are fabricated employing low carbon steels microalloyed with niobium or vanadium in order to combine the weldability and high ductility of the low carbon steels with the high strength provided by the microalloying elements. The present paper reports the results of a comparative study of standard(medium carbon) and microalloyed rebars considering features of microstructure, mechanical behavior, weldability and the electrochemical properties of these two materials embedded in plain and chloride contaminated concrete. The main differences were observed in microstructural features, mechanical behavior and weldability. The corrosion rate measurements of standard and microalloyed rebars are similar. The weldability of the rebars is discussed in terms of the better electrical connectivity of the reinforcement and cathodic protection.
