Abstract
This paper aims at finding the coupled effect of hot and humid environment on the corroded repaired patches of chloride contaminated steel reinforced concrete. Chloride induced corrosion under coupled environmental effects of high humidity and high temperature often found in gulf marine environment is a very serious threat for durability of reinforced concrete structures. In the previous research, the authors experimentally corroborated re-corrosion in the repaired reinforced concrete patches in the form of macro-cells. But, whether this formation of macro-cell is influenced by the coupled effect of high temperature and high relative humidity remained a question and formed the basis of this research. This coupled effect is investigated by laboratory controlled experimentation at varying temperature at 30, 40 and 50 degrees C and a high ambient relative humidity of 85% in environmental control chambers. Specimens were prepared having total chloride concentration in mixing water 3% and 5 % by mass of binder. From the experiment results interesting and novel observations, trends and behaviors have been identified. A non-uniform and non-linear corrosion reaction was observed even after the breaking of passive layer. Furthermore, a decrease in electrochemical corrosion potential and corrosion mass loss at 50 degrees C in comparison to 30 and 40 degrees C temperature conditions was seen. This may be due to the reduction of oxygen solubility in the pore solution at high temperature and blockage of concrete pores at high relative humidity. It is expected that a stable oxide layer may have developed under limiting oxygen controlled corrosion reaction. This can form basis for the development of a new technique to passivate steel bar embedded in chloride contaminated concrete and improve the method of repairs.